U.S. patent application number 12/901716 was filed with the patent office on 2011-04-14 for process for treating heavy oil.
Invention is credited to Kai Tod Paul Jarosch, Stephen Claude LeViness, Edward Rode, Laura J. Silva, Anna Lee Tonkovich.
Application Number | 20110083997 12/901716 |
Document ID | / |
Family ID | 43853980 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110083997 |
Kind Code |
A1 |
Silva; Laura J. ; et
al. |
April 14, 2011 |
PROCESS FOR TREATING HEAVY OIL
Abstract
This invention relates to a process for hydroprocessing heavy
oil under process intensification conditions to form an upgraded
hydrocarbon product.
Inventors: |
Silva; Laura J.; (Dublin,
OH) ; Tonkovich; Anna Lee; (Dublin, OH) ;
LeViness; Stephen Claude; (Columbus, OH) ; Jarosch;
Kai Tod Paul; (Bexley, OH) ; Rode; Edward;
(Dublin, OH) |
Family ID: |
43853980 |
Appl. No.: |
12/901716 |
Filed: |
October 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61250282 |
Oct 9, 2009 |
|
|
|
Current U.S.
Class: |
208/60 ;
208/66 |
Current CPC
Class: |
B01J 2219/00835
20130101; B01J 2219/00889 20130101; B01J 2219/00867 20130101; C10G
49/00 20130101; B01J 2219/00006 20130101; C10G 47/00 20130101; B01J
19/0093 20130101; C10G 2300/4087 20130101; B01J 2219/00783
20130101; C10G 45/00 20130101; C10G 65/12 20130101; Y02P 30/20
20151101; C10G 2300/205 20130101; C10G 2300/1011 20130101; B01J
2219/00873 20130101; C10G 2300/202 20130101 |
Class at
Publication: |
208/60 ;
208/66 |
International
Class: |
C10G 69/02 20060101
C10G069/02 |
Claims
1. A process, comprising: flowing heavy oil and hydrogen in a
reactor in contact with a hydroprocessing catalyst under process
intensification conditions, the heavy oil comprising one or more
heteroatoms; reacting at least some of the heteroatoms with the
hydrogen to form one or more heteroatom containing compounds; and
hydrocracking the heavy oil to form an upgraded hydrocarbon
product.
2. The process of claim 1 wherein the reactor comprises a process
microchannel, the heavy oil and hydrogen flowing in the process
microchannel in contact with the hydroprocessing catalyst.
3. The process of claim 1 wherein the hydroprocessing catalyst
comprises a hydrotreating catalyst.
4. The process of claim 1 wherein the hydroprocessing catalyst
comprises a hydrocracking catalyst.
5. The process of claim 1 wherein the heteroatom containing
compounds are separated from the upgraded hydrocarbon product.
6. The process of claim 1 wherein the heavy oil comprises water,
the process further comprising removing water from the upgraded
hydrocarbon product.
7. The process of claim 1 wherein the heavy oil is reacted in the
presence of a hydrotreating catalyst to form an intermediate
hydrocarbon product, and the intermediate hydrocarbon product is
reacted in the presence of a hydrocracking catalyst to form the
upgraded hydrocarbon product.
8. The process of claim 7 wherein the reaction with the
hydrotreating catalyst is conducted in a process microchannel and
the reaction with the hydrocracking catalyst is conducted in a
process microchannel, the hydrotreating catalyst and the
hydrocracking catalyst being in the same process microchannel.
9. The process of claim 7 wherein the reaction with the
hydrotreating catalyst is conducted in a first process microchannel
and the reaction with the hydrocracking catalyst is conducted in a
second process microchannel.
10. The process of claim 7 wherein the reaction with the
hydrotreating catalyst is conducted in a first microchannel reactor
and the reaction with the hydrocracking catalyst is conducted in a
second microchannel reactor.
11. The process of claim 1 wherein the heteroatoms comprise
nitrogen, sulfur, oxygen, metal, ora combination of two or more
thereof.
12. The process of claim 1 wherein the pressure in the reactor is
in the range from about 0.5 to about 25 MPa.
13. The process of claim 1 wherein the temperature in the reactor
is in the range from about 100.degree. C. to about 500.degree.
C.
14. The process of claim 1 wherein the ratio of hydrogen to heavy
oil in the reactor is in the range from about 10 to about 6000
standard cubic centimeters of hydrogen per cubic centimeter of
heavy oil.
15. The process of claim 1 wherein the heavy oil entering the
reactor is in the form of a liquid, a vapor, or a combination of
liquid and vapor.
16. The process of claim 1 wherein the reactor comprises one or
more process microchannels, the heavy oil and hydrogen being mixed
with each other in the one or more process microchannels.
17. The process of claim 1 wherein the reactor comprises a process
microchannel and the process microchannel is in a microchannel
reactor, the microchannel reactor comprising a reactant stream
channel adjacent to the process microchannel, the process
microchannel and the reactant stream channel having a common wall,
and a plurality of openings in the common wall, the process further
comprising flowing the pyrolysis oil in the process microchannel
and flowing the hydrogen from the reactant stream channel through
the openings in the common wall into the process microchannel in
contact with the pyrolysis oil.
18. The process of claim 1 wherein the heavy oil and hydrogen are
mixed prior to entering the reactor.
19. The process of claim 1 wherein the reactor comprises a
microchannel reactor comprising a plurality of process
microchannels, the microchannel reactor comprising a manifold
providing a flow passageway for the heavy oil and hydrogen to flow
into the process microchannels.
20. The process of claim 1 wherein the reactor comprises a
microchannel reactor comprising a plurality of the process
microchannels, the microchannel reactor comprising a first manifold
providing a flow passageway for the heavy oil to flow into the
process microchannels, and a second manifold providing a flow
passageway for the hydrogen to flow into the process
microchannels.
21. The process of claim 1 wherein heat is transferred from the
reactor to a heat exchanger.
22. The process of claim 1 wherein the reactor comprises a
microchannel reactor comprising a plurality of process
microchannels, the microchannel reactor further comprising at least
one heat exchange channel in thermal contact with the process
microchannels, a heat exchange fluid being in the heat exchange
channel, and heat is transferred from the process microchannels to
the heat exchange fluid in the heat exchange channel.
23. The process of claim 22 wherein the heat exchange fluid
undergoes a phase change in the heat exchange channel.
24. The process of claim 22 wherein reactants flow in the process
microchannel in a first direction, and the heat exchange fluid
flows in the heat exchange channel in a second direction, the
second direction being cross current relative to the first
direction.
25. The process of claim 1 wherein the reactor comprises a process
microchannel and a tailored heat exchange is provided along the
length of the process microchannel to maintain a substantially
isothermal temperature profile along the length of the process
microchannel.
26. The process of claim 1 wherein the heavy oil entering the
reactor comprises heavy oil vapor, the heavy oil vapor being at
least partially condensed in the reactor.
27. The process of claim 1 wherein the reactor comprises a first
stage reactor, the hydroprocessing catalyst comprising a first
hydrocracking catalyst, the process also employing a second stage
reactor containing a second hydrocracking catalyst, the heavy oil
comprising heavy oil vapor, the process comprising: flowing the
heavy oil vapor and hydrogen in the first stage reactor in contact
with the first hydrocracking catalyst, condensing and hydrocracking
the heavy oil vapor to form a first hydrocracked hydrocarbon
product comprising a first hydrocarbon liquid product and a first
hydrocarbon vapor; separating the first hydrocarbon liquid product
from the first hydrocarbon vapor; flowing the first hydrocarbon
vapor and hydrogen in the second stage reactor in contact with the
second hydrocracking catalyst, condensing and hydrocracking the
first hydrocarbon vapor to form a second hydrocracked hydrocarbon
product comprising a second hydrocarbon liquid product and a second
hydrocarbon vapor; and separating the second hydrocarbon liquid
product from the second hydrocarbon vapor.
28. The process of claim 27 wherein the first hydrocarbon liquid
comprises water and the second hydrocarbon liquid comprises water,
the process further comprising separating water from the first
hydrocarbon liquid, and separating water from the second
hydrocarbon liquid.
29. The process of claim 1 wherein the reactor comprises a first
stage reactor, the hydroprocessing catalyst comprising a first
hydrocracking catalyst, the process also employing a second stage
reactor containing a second hydrocracking catalyst, the first stage
reactor and the second stage reactor being positioned in a
distillation column, the second stage reactor being positioned
above and/or downstream of the first stage reactor, the
distillation column having a distillate end and a bottoms end and
being equipped with a distillate condenser; the heavy oil
comprising heavy oil vapor, the process comprising: flowing the
heavy oil vapor and hydrogen in the first stage reactor toward the
distillate end in contact with the first hydrocracking catalyst,
condensing and hydrocracking the heavy oil vapor to form a first
hydrocracked hydrocarbon product comprising a first liquid
hydrocarbon oil product and a first hydrocarbon vapor; separating
the first liquid hydrocarbon oil product from the first hydrocarbon
vapor, and flowing the first liquid hydrocarbon oil product out of
the distillation column; flowing the first hydrocarbon vapor and
hydrogen in the second stage reactor toward the distillate end in
contact with the second hydrocracking catalyst, condensing and
hydrocracking the first hydrocarbon vapor to form a second
hydrocracked hydrocarbon product comprising a second liquid
hydrocarbon oil product and a second hydrocarbon vapor; separating
the second liquid hydrocarbon oil product from the second
hydrocarbon vapor, and flowing the second liquid hydrocarbon oil
product out of the distillation column; and condensing at least
part of the second hydrocarbon vapor in the distillate condenser to
provide a liquid reflux back to the distillation column.
30. The process of claim 1 wherein the hydroprocessing catalyst is
in the form of particulate solids.
31. The process of claim 1 wherein the hydroprocessing catalyst is
supported on a structure which comprises a foam, felt, wad,
honeycomb, monolith, fin, structured packing, or a combination of
two or more thereof.
32. The process of claim 1 wherein the hydroprocessing catalyst is
in the form of a bed of particulate solids positioned in a process
microchannel, and additional catalyst is washcoated and/or grown on
one or more interior walls of the process microchannel.
33. The process of claim 1 wherein the hydroprocessing catalyst is
a hydrotreating catalyst which comprises Ni, Mo, Co, W, or a
combination of two or more thereof.
34. The process of claim 1 wherein the hydroprocessing catalyst is
a hydrocracking catalyst which comprises Pt, Pd, Ni, Co, Mo, W, or
a combination of two or more thereof.
35. The process of claim 1 wherein the upgraded hydrocarbon product
comprises a middle distillate oil, a light oil, or a mixture
thereof.
36. The process of claim 1 wherein the reactor comprises a process
microchannel, the channel Bond number for the process microchannel
being less than about 1.
37. The process of claim 1 wherein the hydroprocessing catalyst is
in a process microchannel, the hydroprocessing catalyst being
regenerated in-situ in the process microchannel.
38. The process of claim 1 wherein the process is conducted in a
plant facility, the plant facility comprising a plurality of
process microchannels, or one or more microchannel reactors
containing a plurality of process microchannels, or one or more
reactor housing vessels containing one or more microchannel
reactors, the hydroprocessing catalyst in one or more process
microchannels, microchannel reactors or reactor housing vessels
being regenerated while the process is carried out in other process
microchannels, microchannel reactors or reactor housing vessels in
the plant facility.
39. The process of claim 1 wherein the heavy oil is derived from
the gasification, pyrolysis or liquefaction of coal, shale, tar
sands, bitumen, biomass, or a combination of two or more
thereof.
40. The process of claim 1 wherein the heavy oil comprises
pyrolysis oil, pyrolysis oil vapor, or a mixture thereof.
41. The process of claim 1 wherein the heavy oil is formed in a
plant, and the reactor is in the plant, the process comprising
forming the heavy oil and transporting the heavy oil to the
reactor.
42. The process of claim 26 wherein the catalyst is positioned in a
distillation column, the distillation column comprising a single
stage catalytic distillation hydrocracker.
Description
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Application Ser. No. 61/250,282,
filed Oct. 9, 2009, which is incorporated herein by reference in
its entirety.
TECHNICAL FIELD
[0002] This invention relates to a process for treating heavy oil.
More particularly, this invention relates to a process for
upgrading heavy oil by hydroprocessing the oil using process
intensification techniques.
BACKGROUND OF THE INVENTION
[0003] Untreated heavy oils are typically in the form of a dark
brown, free-flowing liquids. Unconventional sources of these heavy
oils include those made from the gasification, pyrolysis or
liquefaction of carbonaceous materials such as coal, shale, tar
sand, bitumen, biomass, and the like. These unconventional heavy
oil sources are often distributed in locations far from large
central processing facilities that are required to upgrade these
oils to useful products such as middle distillate fuels, and the
like. Additionally many of these oils are unstable in long-term
storage and not miscible with conventional hydrocarbon-based fuels,
making transportation to central processing facilities difficult or
uneconomical.
SUMMARY OF THE INVENTION
[0004] The problem relates to providing a viable process for
upgrading heavy oil to produce useful hydrocarbon products such as
middle distillate fuels and the like, using equipment that is
modular or relatively small in size so that the process can be
conducted economically at locations closer to the source of the
heavy oil and thus avoid the problems of storage and transportation
incurred when using large central processing facilities. It would
be advantageous if the equipment could be readily adapted to
process the heavy oil at any desired production volume. This
invention provides a solution to this problem. With the present
invention, heavy oil is upgraded to form useful hydrocarbon
products by hydroprocessing the oil using process intensification
techniques. Heavy oil in the form of a liquid, vapor or combination
thereof may be treated using the inventive process.
[0005] This invention relates to a process, comprising: flowing
heavy oil (that is, heavy oil in the form of a liquid, vapor, or
combination thereof) and hydrogen (i.e., H.sub.2 or reactant
streams containing H.sub.2) in a reactor in contact with a
hydroprocessing catalyst under process intensification conditions,
the heavy oil comprising heteroatoms (e.g., sulfur, nitrogen,
oxygen and/or metals such as Ni, V, and the like); reacting at
least some of the heteroatoms with the hydrogen to form one or more
heteroatom containing compounds; and hydrocracking the heavy oil to
form an upgraded hydrocarbon product. The hydroprocessing catalyst
may be a hydrotreating catalyst or a hydrocracking catalyst. The
heteroatom containing compounds may be separated from the upgraded
hydrocarbon product. In one embodiment of the invention, the
reactor comprises a process microchannel, and the heavy oil and
hydrogen flow in the process microchannel in contact with the
hydroprocessing catalyst and undergo reaction. The process may be
conducted in one or more process microchannels or one or more
microchannel reactors.
[0006] In one embodiment, the heavy oil comprises water, the
process further comprising removing water from the upgraded
hydrocarbon product.
[0007] In one embodiment, the heavy oil is reacted in the presence
of a hydrotreating catalyst to form an intermediate hydrocarbon
product, and then the intermediate hydrocarbon product is reacted
in the presence of a hydrocracking catalyst to form the upgraded
hydrocarbon product. In one embodiment, the reaction with the
hydrotreating catalyst is conducted in a process microchannel and
the reaction with the hydrocracking catalyst is conducted in a
process microchannel, the hydrotreating catalyst and the
hydrocracking catalyst being in the same process microchannel. In
one embodiment, the reaction with the hydrotreating catalyst is
conducted in a first process microchannel and the reaction with the
hydrocracking catalyst is conducted in a second process
microchannel. In one embodiment, the reaction with the
hydrotreating catalyst is conducted in a first microchannel reactor
and the reaction with the hydrocracking catalyst is conducted in a
second microchannel reactor.
[0008] In one embodiment, the pressure in the reactor is in the
range from about 0.5 to about 25 MPa.
[0009] In one embodiment, the temperature in the reactor is in the
range from about 100.degree. C. to about 500.degree. C.
[0010] In one embodiment, ratio of hydrogen to heavy oil in the
reactor is in the range from about 10 to about 6000 standard cubic
centimeters of hydrogen per cubic centimeter of heavy oil.
[0011] In one embodiment, the heavy oil entering the reactor is in
the form of a liquid, a vapor, or a combination of liquid and
vapor.
[0012] In one embodiment, the reactor comprises one or more process
microchannels, the heavy oil and hydrogen being mixed with each
other in the one or more process microchannels.
[0013] In one embodiment, the reactor comprises a process
microchannel and the process microchannel is in a microchannel
reactor, the microchannel reactor comprising a reactant stream
channel adjacent to the process microchannel, the process
microchannel and the reactant stream channel having a common wall,
and a plurality of openings in the common wall, the process further
comprising flowing the pyrolysis oil in the process microchannel
and flowing the hydrogen from the reactant stream channel through
the openings in the common wall into the process microchannel in
contact with the pyrolysis oil.
[0014] In one embodiment, the heavy oil and hydrogen are mixed
prior to entering the reactor.
[0015] In one embodiment, the reactor comprises a microchannel
reactor comprising a plurality of process microchannels, the
microchannel reactor comprising a manifold providing a flow
passageway for the heavy oil and hydrogen to flow into the process
microchannels.
[0016] In one embodiment, the reactor comprises a microchannel
reactor comprising a plurality of the process microchannels, the
microchannel reactor comprising a first manifold providing a flow
passageway for the heavy oil to flow into the process
microchannels, and a second manifold providing a flow passageway
for the hydrogen to flow into the process microchannels.
[0017] In one embodiment, heat is transferred from the reactor to a
heat exchanger.
[0018] In one embodiment, the reactor comprises a microchannel
reactor comprising a plurality of process microchannels, the
microchannel reactor further comprising at least one heat exchange
channel in thermal contact with the process microchannels, a heat
exchange fluid being in the heat exchange channel, and heat is
transferred from the process microchannels to the heat exchange
fluid in the heat exchange channel. The heat exchange fluid may
undergo a phase change in the heat exchange channel. The reactants
may flow in the process microchannel in a first direction, and the
heat exchange fluid may flow in the heat exchange channel in a
second direction, the second direction being cross current relative
to the first direction.
[0019] In one embodiment, the reactor comprises a process
microchannel and a tailored heat exchange is provided along the
length of the process microchannel to maintain a substantially
isothermal temperature profile along the length of the process
microchannel.
[0020] In one embodiment, the heavy oil entering the reactor
comprises heavy oil vapor, the heavy oil vapor being at least
partially condensed in the reactor. In this embodiment, the
catalyst may be positioned in a distillation column, the
distillation column comprising a single stage catalytic
distillation hydrocracker. Hydrogen may be mixed with the heavy oil
vapor prior to entering the reactor, or the hydrogen and heavy oil
may be separately manifolded into the reactor. Further, hydrogen
and/or another reactive feed or a non-reactive gas or liquid (i.e.,
a third fluid) may be fed downstream of the first manifold region.
In one embodiment, a second fluid may be used to tailor the
reactions or to inhibit unwanted side reactions. The third fluid
may be added to reduce coking or the formation of longer chain
hydrocarbons. The third fluid, in one embodiment may be steam or an
oxygen containing stream. In one embodiment, the third fluid may
comprise hydrogen or a hydrogen-containing stream, containing, for
example, other carbonaceous matter.
[0021] In one embodiment, the reactor comprises a first stage
reactor, the hydroprocessing catalyst comprising a first
hydrocracking catalyst, the process also employing a second stage
reactor containing a second hydrocracking catalyst, the heavy oil
comprising heavy oil vapor, the process comprising: flowing the
heavy oil vapor and hydrogen in the first stage reactor in contact
with the first hydrocracking catalyst, condensing and hydrocracking
the heavy oil vapor to form a first hydrocracked hydrocarbon
product comprising a first liquid hydrocarbon product and a first
hydrocarbon vapor, and optionally a first aqueous phase product;
separating the first hydrocarbon liquid product from the first
hydrocarbon vapor, and optionally separating the first gaseous
phase product from the first hydrocarbon liquid; flowing the first
hydrocarbon vapor and hydrogen in the second stage reactor in
contact with the second hydrocracking catalyst, condensing and
hydrocracking the first hydrocarbon vapor to form a second
hydrocracked hydrocarbon product comprising a second hydrocarbon
liquid product and a second hydrocarbon vapor, and optionally a
second aqueous phase product; and separating the second hydrocarbon
liquid product from the second hydrocarbon vapor, and optionally
separating the second aqueous phase product from the second
hydrocarbon liquid product. Additional hydroprocessing and/or
separation stages may be added.
[0022] In one embodiment, the hydroprocessing is conducted in a
catalytic distillation unit (CDU) which contains a hydroprocessing
catalyst. The heavy oil and the hydrogen are fed to the CDU. A
portion of the light overhead product is condensed and recycled to
the CDU. At least two product streams exit the CDU, including at
least one product stream which has been converted to an upgraded
hyrocarbon product. Optionally, the heavy oil feed to the CDU may
comprise heavy oil vapor. Further, the hydrogen for the CDU may be
premixed with the heavy oil vapor feed prior to being fed to the
CDU. The heavy oil vapor feed may be fed to the CDU below the
catalyst, so that the refluxing liquid may be used to wash down
entrained solids into the bottom of the CDU to prevent the solids
from entering the catalyst and causing fouling or plugging. In this
embodiment, the hydroprocessing is integrated in the heavy oil
production flowsheet. As the heavy oil is being reacted, it is
being upgraded to a more stable, useable product. Further, the
heavy oil may be upgraded as it is being condensed, a further
integration, so that unstable liquids are not formed.
[0023] In one embodiment, the process comprises a first stage
reaction section containing a first hydroprocessing catalyst, the
process also employing a second stage reaction section containing a
second hydroprocessing catalyst, the first stage reaction section
and the second stage reaction section being positioned in a
distillation column, the second stage reaction section being
positioned above the first stage reaction section, the distillation
column having a distillate end and a bottoms end and being equipped
with a distillate condenser; the heavy oil comprising heavy oil
vapor, the process comprising: flowing the heavy oil vapor and
hydrogen in the first stage reaction section toward the distillate
end in contact with the first hydroprocessing catalyst, condensing
and hydrocracking the pyrolysis oil vapor to form a first
hydroprocessed hydrocarbon product comprising a first hydrocarbon
liquid product and a first hydrocarbon vapor; separating the first
hydrocarbon liquid product from the first hydrocarbon vapor, and
flowing the first hydrocarbon liquid product out of the
distillation column; flowing the first hydrocarbon vapor and
hydrogen, with optional addition of hydrogen, in the second stage
reaction section toward the distillate end in contact with the
second hydroprocessing catalyst, condensing and hydroprocessing the
first hydrocarbon vapor to form a second hydroprocessed hydrocarbon
product comprising a second hydrocarbon liquid product and a second
hydrocarbon vapor; separating the second hydrocarbon liquid product
from the second hydrocarbon vapor, and flowing the second
hydrocarbon liquid product out of the distillation column; and
condensing at least part of the second hydrocarbon vapor in the
distillate condenser to form another hydrocarbon liquid product, a
portion of the another hydrocarbon liquid product being refluxed to
the distillation column. One or more of the liquid products may
subsequently be sent to a phase separation step for removal of
immiscible water, if present.
[0024] In one embodiment, the reactor comprises a first stage
reactor, the hydroprocessing catalyst comprising a first
hydrocracking catalyst, the process also employing a second stage
reactor containing a second hydrocracking catalyst, the first stage
reactor and the second stage reactor being positioned in a
distillation column, the second stage reactor being positioned
above and/or downstream of the first stage reactor, the
distillation column having a distillate end and a bottoms end and
being equipped with a distillate condenser; the heavy oil
comprising heavy oil vapor, the process comprising: flowing the
heavy oil vapor and hydrogen in the first stage reactor toward the
distillate end in contact with the first hydrocracking catalyst,
condensing and hydrocracking at least part of the heavy oil vapor
to form a first hydrocracked hydrocarbon product comprising a first
liquid hydrocarbon oil product and a first hydrocarbon vapor;
separating the first liquid hydrocarbon oil product from the first
hydrocarbon vapor, and flowing the first liquid hydrocarbon oil
product out of the distillation column; flowing the first
hydrocarbon vapor and hydrogen in the second stage reactor toward
the distillate end in contact with the second hydrocracking
catalyst, condensing and hydrocracking at least part of the first
hydrocarbon vapor to form a second hydrocracked hydrocarbon product
comprising a second liquid hydrocarbon oil product and a second
hydrocarbon vapor; separating the second liquid hydrocarbon oil
product from the second hydrocarbon vapor, and flowing the second
liquid hydrocarbon oil product out of the distillation column; and
condensing at least part of the second hydrocarbon vapor in the
distillate condenser to provide a liquid reflux back to the
distillation column.
[0025] In one embodiment, the hydroprocessing catalyst is
positioned in a process microchannel, the hydroprocessing catalyst
being in the form of particulate solids.
[0026] In one embodiment, the hydroprocessing catalyst is supported
on a structure which comprises a foam, felt, wad, honeycomb,
monolith, fin, structured packing, or a combination of two or more
thereof.
[0027] In one embodiment, the hydroprocessing catalyst is in the
form of a bed of particulate solids positioned in a process
microchannel, and additional catalyst is washcoated and/or grown on
one or more interior walls of the process microchannel.
[0028] In one embodiment, the hydroprocessing catalyst is a
hydrotreating catalyst which comprises Ni, Mo, Co, W, or a
combination of two or more thereof.
[0029] In one embodiment, the hydroprocessing catalyst is a
hydrocracking catalyst which comprises Pt, Pd, Ni, Co, Mo, W, or a
combination of two or more thereof.
[0030] In one embodiment, the upgraded hydrocarbon product
comprises a middle distillate oil, a light oil, or a mixture
thereof.
[0031] In one embodiment, the reactor comprises a process
microchannel, the channel Bond number for the process microchannel
being less than about 1.
[0032] In one embodiment, the hydroprocessing catalyst is in a
process microchannel, the hydroprocessing catalyst being
regenerated in-situ in the process microchannel.
[0033] In one embodiment, the heat exchange fluid is hydrogen or a
hydrogen-containing fluid that is preheated from the heat of
reaction or internal thermal recuperation before adding to the
hydrocarbon reactant. The hydrogen-containing fluid may be combined
with the hydrocarbon reactant before the reaction or distributed
along the length of the reactor in two or more discrete
locations.
[0034] In one embodiment, the inventive process is conducted in a
plant facility, the plant facility comprising an integrated process
for producing a heavy oil vapor product, the process comprising
condensing the heavy oil vapor product, and hydroprocessing the
heavy oil vapor product.
[0035] In one embodiment, the process is conducted in a plant
facility, the plant facility comprising a plurality of process
microchannels, or one or more microchannel reactors containing a
plurality of process microchannels, or one or more reactor housing
vessels containing one or more microchannel reactors, the
hydroprocessing catalyst in one or more process microchannels,
microchannel reactors or reactor housing vessels being regenerated
while the process is carried out in other process microchannels,
microchannel reactors or reactor housing vessels in the plant
facility.
[0036] In one embodiment, the heavy oil is derived from the
gasification, pyrolysis or liquefaction of coal, shale, tar sand,
bitumen, biomass, or a combination of two or more thereof.
[0037] In one embodiment, the heavy oil comprises pyrolysis oil,
pyrolysis oil vapor, or a mixture thereof.
[0038] In one embodiment, the heavy oil is formed in a plant, and
the reactor is in the plant, the process comprising forming the
heavy oil and transporting the heavy oil to the reactor.
[0039] With the inventive process, increased process efficiency may
be achieved as a result of relatively high mass and energy transfer
rates that can be achieved as a result of conducting the process
under process intensification conditions. This may provide for the
following advantages when compared to conventional processing:
[0040] significant increases in productivity, [0041] significant
reductions in process footprint for the same throughput, [0042]
increased processing windows and operational flexibility
(opportunities to operate at lower pressures and temperatures),
[0043] increased process control (reduced problems with hot spots),
[0044] reduced operating costs, [0045] reduced energy consumption,
[0046] easy variation in process throughput (by numbering-up
scaling approach), [0047] integration of multiple unit operations
in single and movable device systems, [0048] optimization of
catalyst functionality, [0049] easy implementation of catalyst
regeneration schemes.
[0050] These benefits can eliminate cost and distribution issues
that often constrain operation, allowing energy to be produced on
site, adopting readily available, local and renewable feedstocks
that may include agricultural resources, waste and/or other
biological materials, as well as coal, shale, tar sand, bitumen,
biomass, and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] In the annexed drawings, like parts and features have like
designations.
[0052] FIG. 1 is a schematic illustration of a microchannel that
may be used with the inventive process.
[0053] FIGS. 2A, 2B and 2C are illustrations of a microchannel
reactor that may be used to conduct the inventive process. This
microchannel reactor comprises a plurality of process
microchannels, reactant stream channels and heat exchange channels
positioned side-by-side. Hydrocarbon reactants (i.e., heavy oil or
intermediate hydrocarbon product) as well as the desired upgraded
hydrocarbon product flow in the process microchannels. Hydrogen
flows into the reactant stream channels and then from the reactant
stream channels into the process microchannels where it mixes with
the hydrocarbon reactants and undergoes a hydroprocessing reaction.
Heat exchange fluid flows in the heat exchange channels. The
reactants and product flow in a direction that is cross-current to
the flow of the heat exchange fluid. FIG. 2A shows the microchannel
reactor without headers providing for the flow of fluids into and
out of the microchannel reactor. FIG. 2B shows the headers for
providing for the flow of fluid into and out of the process
microchannels, reactant stream channels and heat exchange channels.
FIG. 2C is an orthographic projection of the reactor shown in FIG.
2B, with the reactor being positioned in reactor housing
vessel.
[0054] FIG. 3 is a flow sheet illustrating the inventive process
for hydrotreating and hydrocracking heavy oil to form one or more
upgraded hydrocarbon products.
[0055] FIG. 4 is a schematic illustration of two reactor housing
vessels which are used in sequence, one being identified as a first
stage vessel, the other being identified as a second stage vessel.
Each microchannel reactor housing vessel contains a plurality of
microchannel reactors. In the first stage vessel, heavy oil is
hydrotreated to form an intermediate hydrocarbon product. In the
second stage vessel, the intermediate hydrocarbon product from the
first stage is hydrocracked to form an upgraded hydrocarbon
product.
[0056] FIG. 5 is a schematic illustration of two layers of process
microchannels that are positioned in the same microchannel reactor.
A layer of heat exchange channels is positioned between the process
microchannel layers. In the first layer of process microchannels
heavy oil is hydrotreated to form a intermediate hydrocarbon
product or hydrotreated product. In the second layer of process
microchannels the hydrotreated product from the first layer is
hydrocracked to form an upgraded hydrocarbon product or
hydrocracked product.
[0057] FIGS. 6 and 7 are schematic illustrations of a microchannel
reactor housing vessel which may be used for housing a plurality of
the microchannel reactors used with the inventive process. FIG. 7
is a cutaway image of the vessel illustrated in FIG. 6.
[0058] FIGS. 8-13 are schematic illustrations of repeating units
that may be used in the microchannel reactors used with the
inventive process.
[0059] FIGS. 14 and 15 are schematic illustrations of surface
features that may be used in the microchannels used with the
inventive process.
[0060] FIGS. 16-24 are schematic illustrations of catalysts or
catalyst support structures that may be used in the microchannels
used with the inventive process. FIG. 22(b) is a cross sectional
view of FIG. 22(a) taken along line (b)-(b) in FIG. 22(a). FIG.
23(b) is a cross sectional view of FIG. 23(a) taken along line
(b)-(b) in FIG. 23(a).
[0061] FIGS. 25 and 26 are schematic illustrations of repeating
units that may be used in the microchannel reactors used with the
inventive process. Each of these repeating units includes a section
for preheating the reactants and a section for quenching the
product.
[0062] FIG. 27 is a flow sheet illustrating a process for gasifying
heavy oil to form a heavy oil vapor and then hydrocracking the
heavy oil vapor using a condenser hydrocracker.
[0063] FIGS. 28 and 29 are schematic illustrations of the condenser
hydrocracker shown in FIG. 27.
[0064] FIG. 30 is a flow sheet illustrating a two-stage process for
hydrocracking heavy oil vapor.
[0065] FIG. 31 is a flow sheet illustrating a process for
hydrocracking heavy oil vapor utilizing a distillation column.
[0066] FIGS. 32 and 33 illustrate the construction of a
microchannel reactor using waveforms.
DETAILED DESCRIPTION OF THE INVENTION
[0067] All ranges and ratio limits disclosed in the specification
and claims may be combined in any manner. It is to be understood
that unless specifically stated otherwise, references to "a," "an,"
and/or "the" may include one or more than one, and that reference
to an item in the singular may also include the item in the plural.
All combinations specified in the claims may be combined in any
manner.
[0068] The term "heavy oil" refers to C.sub.5+ hydrocarbons
produced by the gasification, liquefaction or pyrolysis of solid
carbonaceous materials (e.g., coal, shale, tar sand, bitumen,
biomass, and the like). Heavy oils may also comprise crude oil
fractions with an initial boiling point of about 250.degree. C. or
above. Heavy oils include vacuum gas oils, atmospheric residiuum,
vacuum residiuum, light catalytic cracking oil, heavy catalytic
cracking oil, and the like. Heavy oils may have polyaromatic
concentrations above about 2% by weight and total aromatic
concentrations above about 10% by weight. Heavy oils may have
heteroatom concentrations above about 2% by weight, the heteroatoms
being sulfur, nitrogen, oxygen and/or metal (e.g., Ni, V, and the
like).
[0069] The term "pyrolysis oil" refers to a synthetic oil which is
extracted from biomass as well as other carbonaceous materials
using pyrolysis. Pyrolysis oil has tar-like characteristics and
often contains high levels of heteroatoms such as sulfur, nitrogen,
oxygen and/or metal (e.g., Ni, V, and the like). Pyrolysis oil may
be referred to as pyrolytic oil or bio-oil.
[0070] The term "middle distillate oil" refers to hydrocarbons
boiling in the range of about 125.degree. C. to about 375.degree.
C. Middle distillate oils include middle distillate fuels such as
kerosene, jet fuel, diesel fuel, heating oil, fuel oil, and the
like.
[0071] The term "light oil" refers to hydrocarbons boiling in the
range of about 20.degree. C. to about 125.degree. C. Light oils may
be referred to as light distillates. Examples include liquefied
petroleum gas (LPG), gasoline, naphtha, and the like
[0072] The term "biomass" refers to biological material that may be
used as fuel. The biological matter may be living or dead. The term
biomass may refer to plant matter grown for use as biofuel. The
term biomass may include plant or animal matter used for production
of fibers, chemicals or heat. Biomass may include biodegradable
wastes that can be burnt as fuel. Biomass may comprise plants such
as switchgrass, hemp, corn, poplar, willow, sugarcane, oil palm,
and the like.
[0073] The term "char" refers to a solid material that remains
after gases have been driven out or released from a carbonaceous
material. Char may be formed during the combustion of a
carbonaceous material.
[0074] The term "tar" refers to a viscous black liquid derived from
a carbonaceous material, for example, by pyrolysis.
[0075] The term "process intensification" refers to the
miniaturization of unit operations and processes where a smaller
compact piece of equipment takes the place of a larger piece of
equipment or multiple pieces of equipment, but still provides for
the same capacity or mass flow rate as the larger piece of
equipment or multiple pieces of equipment. In one embodiment,
process intensification may be achieved using catalytic
distillation in order to conduct reactions and separations in
integrated equipment. In one embodiment, process intensification
may be achieved using microchannel process technology where
chemical processors are employed that are characterized by parallel
arrays of microchannels. Processes are intensified using
microchannel process technology by decreasing transfer resistance
between process fluids and channel walls. Process intensification
allows for use of more active catalysts than conventional
processes, greatly increasing the throughput per unit volume. As a
result of process intensification, overall system volumes can be
reduced by about ten to one hundred fold or more when compared to
conventional hardware.
[0076] The term "process intensification conditions" refers to a
process conducted in a reactor where as a result of enhanced mass
and/or energy transfer the volume of the reactor is reduced by at
least about 2 fold, or at least about 10 fold, or at least about 50
fold, or at least about 100 fold, as compared to a conventional
reactor and yet the throughput of product in the reactor is the
same or greater than the throughput of product in the conventional
reactor.
[0077] The term "hydroprocessing" process refers to a hydrocracking
process or a hydrotreating process.
[0078] The term "hydrotreating process" refers to a process wherein
heteroatoms bonded to one or more hydrocarbon compounds are reacted
with hydrogen to form heteroatom containing compounds. The
heteroatom containing compounds may then be separated from the
hydrocarbon compounds. The heteroatoms may include sulfur,
nitrogen, oxygen, and/or metals (e.g., Ni, V, and the like).
[0079] The term "hydrocracking" process refers to a process wherein
hydrocarbon molecules are split into smaller molecules. For
example, a C.sub.1-2 alkane may be hydrocracked to form a C.sub.7
alkane and a C.sub.5 alkane. The hydrocracked products may be
isomerized. The hydrocracked products may comprise straight chain
hydrocarbons, branched chain hydrocarbons (e.g., isoparaffins)
and/or ring compounds.
[0080] The term "hydrocarbon" refers to purely hydrocarbon
compounds; that is, aliphatic compounds, (e.g., alkane, alkene or
alkyne), alicyclic compounds (e.g., cycloalkane, cycloalkylene),
aromatic compounds, aliphatic- and alicyclic-substituted aromatic
compounds, aromatic-substituted aliphatic compounds,
aromatic-substituted alicyclic compounds, and the like. The term
"hydrocarbon" also refers to substituted hydrocarbon compounds;
that is, hydrocarbon compounds containing non-hydrocarbon
substituents. Examples of the non-hydrocarbon substituents may
include hydroxyl, acyl, nitro, etc. The term "hydrocarbon" also
refers to hetero substituted hydrocarbon compounds; that is,
hydrocarbon compounds which contain atoms other than carbon in a
chain or ring otherwise containing carbon atoms. The heteroatoms
may include, for example, nitrogen, oxygen, sulfur and/or metals
(e.g., Ni, V, and the like).
[0081] The term "microchannel" refers to a channel having at least
one internal dimension of height or width of up to about 10
millimeters (mm), and in one embodiment up to about 5 mm, and in
one embodiment up to about 2 mm. An example of a microchannel that
may be used with the inventive process is illustrated in FIG. 1.
Referring to FIG. 1, microchannel 10 has a height (h), width (w)
and length (l). Fluid flows through the microchannel 10 in the
direction indicated by arrows 12 and 14. Both the height (h) and
width (w) are perpendicular to the bulk flow direction of the flow
of fluid in the microchannel 10. The microchannel may comprise at
least one inlet and at least one outlet wherein the at least one
inlet is distinct from the at least one outlet. The microchannel
may not be merely an orifice. The microchannel may not be merely a
channel through a zeolite ora mesoporous material. The length of
the microchannel may be at least about two times the height or
width, and in one embodiment at least about five times the height
or width, and in one embodiment at least about ten times the height
or width. The height or width may be referred to as the gap between
opposed internal walls of the microchannel. The internal height or
width of the microchannel may be in the range of about 0.05 to
about 10 mm, and in one embodiment from about 0.05 to about 5 mm,
and in one embodiment from about 0.05 to about 2 mm, and in one
embodiment from about 0.05 to about 1.5 mm, and in one embodiment
from about 0.05 to about 1 mm, and in one embodiment from about
0.05 to about 0.75 mm, and in one embodiment from about 0.05 to
about 0.5 mm. The other internal dimension of height or width may
be of any dimension, for example, up to about 3 meters, and in one
embodiment about 0.01 to about 3 meters, and in one embodiment
about 0.1 to about 3 meters. The length of the microchannel may be
of any dimension, for example, up to about 10 meters, and in one
embodiment from about 0.5 to about 10 meters, and in one embodiment
from about 0.05 to about 6 meters, and in one embodiment from about
0.05 to about 3 meters, and in one embodiment about 0.05 to about 2
meters, and in one embodiment from 0.05 to about 1.5 meters, and in
one embodiment from about 0.1 to about 0.7 meter. The microchannel
may have a cross section having any shape, for example, a square,
rectangle, circle, semi-circle, trapezoid, etc. The shape and/or
size of the cross section of the microchannel may vary over its
length. For example, the height or width may taper from a
relatively large dimension to a relatively small dimension, or vice
versa, over the length of the microchannel.
[0082] The term "process microchannel" refers to a microchannel
wherein a process is conducted. The process may be a hydrocracking
or hydrotreating process.
[0083] The term "microchannel reactor" refers to an apparatus
comprising one or more process microchannels wherein a reaction
process is conducted. The process may be a hydrocracking process or
a hydrotreating process. When two or more process microchannels are
used, the process microchannels may be operated in parallel. The
microchannel reactor may include a header or manifold assembly for
providing for the flow of reactants into the one or more process
microchannels, and a footer or manifold assembly providing for the
flow of product out of the one or more process microchannels. The
microchannel reactor may further comprise one or more heat exchange
channels adjacent to and/or in thermal contact with the one or more
process microchannels. The heat exchange channels may provide
heating and/or cooling for the fluids in the process microchannels.
The heat exchange channels may be microchannels. The microchannel
reactor may include a header or manifold assembly for providing for
the flow of heat exchange fluid into the heat exchange channels,
and a footer or manifold assembly providing for the flow of heat
exchange fluid out of the heat exchange channels.
[0084] The term "conventional reactor" refers to a reactor that is
not a microchannel reactor.
[0085] The term "microchannel processing unit" refers to an
apparatus comprising one or more process microchannels wherein a
process is conducted. The process may be a reaction process or it
may be any other unit operation wherein one or more fluids are
treated.
[0086] The term "volume" with respect to volume within a process
microchannel includes all volume in the process microchannel a
process fluid may flow through or flow by. This volume may include
volume within surface features that may be positioned in the
process microchannel and adapted for the flow of fluid in a
flow-through manner or in a flow-by manner.
[0087] The term "adjacent" when referring to the position of one
channel relative to the position of another channel means directly
adjacent such that a wall or walls separate the two channels. In
one embodiment, the two channels may have a common wall. The common
wall may vary in thickness. However, "adjacent" channels may not be
separated by an intervening channel that may interfere with heat
transfer between the channels. One channel may be adjacent to
another channel over only part of the another channel. For example,
a process microchannel may be longer than and extend beyond one or
more adjacent heat exchange channels.
[0088] The term "thermal contact" refers to two bodies, for
example, two channels, that may or may not be in physical contact
with each other or adjacent to each other but still exchange heat
with each other. One body in thermal contact with another body may
heat or cool the other body.
[0089] The term "fluid" refers to a gas, a liquid, a mixture of a
gas and a liquid, or a gas or a liquid containing dispersed solids,
liquid droplets and/or gaseous bubbles. The droplets and/or bubbles
may be irregularly or regularly shaped and may be of similar or
different sizes.
[0090] The terms "gas" and "vapor" have the same meaning and are
sometimes used interchangeably.
[0091] The term "residence time" or "average residence time" refers
to the internal volume of a space within a channel occupied by a
fluid flowing in the space divided by the average volumetric flow
rate for the fluid flowing in the space at the temperature and
pressure being used.
[0092] The terms "upstream" and "downstream" refer to positions
within a reactor or a channel (e.g., a process microchannel) or in
a process or process flow sheet that is relative to the direction
of flow of a fluid in the reactor, channel, process or process flow
sheet. For example, a position within a reactor or channel or
process or process flow sheet not yet reached by a portion of a
fluid stream flowing toward that position would be downstream of
that portion of the fluid stream. A position within the reactor or
channel or a process or process flow sheet already passed by a
portion of a fluid stream flowing away from that position would be
upstream of that portion of the fluid stream. The terms "upstream"
and "downstream" do not necessarily refer to a vertical position
since the reactor or channels used herein may be oriented
horizontally, vertically or at an inclined angle.
[0093] The term "shim" refers to a planar or substantially planar
sheet or plate. The thickness of the shim may be the smallest
dimension of the shim and may be up to about 4 mm, and in one
embodiment in the range from about 0.05 to about 2 mm, and in one
embodiment in the range of about 0.05 to about 1 mm, and in one
embodiment in the range from about 0.05 to about 0.5 mm. The shim
may have any length and width. Process microchannels and/or heat
exchange channels may be positioned on or in a shim.
[0094] The term "surface feature" refers to a depression in a
channel wall and/or internal channel structure (e.g., fin) and/or a
projection from a channel wall and/or internal channel structure
that disrupts flow within the channel. Examples of surface feature
designs that may be used are illustrated in FIGS. 14, 15 and 24.
The surface features may be in the form of circles, spheres,
hemispheres, frustrums, oblongs, squares, rectangles, angled
rectangles, checks, chevrons, vanes, air foils, wavy shapes, and
the like. Combinations of two or more of the foregoing may be used.
The surface features may contain subfeatures where the major walls
of the surface features further contain smaller surface features
that may take the form of notches, waves, indents, holes, burrs,
checks, scallops, and the like. The surface features may have a
depth, a width, and a length. The surface features may be formed on
or in one or more of the interior walls of the process
microchannels and/or heat exchange channels used in accordance with
the inventive process. The surface features may be referred to as
passive surface features or passive mixing features. The surface
features may be used to disrupt flow (for example, disrupt laminar
flow streamlines) and create advective flow at an angle to the bulk
flow direction.
[0095] The term "waveform" refers to a contiguous piece of
thermally conductive material that is transformed from a planar
object to a three-dimensional object. The waveform may be used to
form one or more microchannels. The waveform may comprise a right
angled corrugated insert which may be sandwiched between opposed
planar sheets or shims. In this manner one or more microchannels
may be defined on three sides by the waveform and on the fourth
side by one of the planar sheets or shims. The waveform may be made
of any of the thermally conductive materials disclosed herein as
being useful for making the microchannel reactor. These may include
copper, aluminum, stainless steel, and the like. The thermal
conductivity of the waveform may be about 1 W/m-K or higher. The
waveform may comprise a composite material which includes two or
more layers, where the thermal conductivity of the two or more
materials may differ by about 20% or more. The waveform may
comprise three layered constructions wherein, for example, an
aluminum or copper layer may be positioned between two stainless
steel layers. A thermally conductive waveform may be used to remove
the heat of reaction while retaining an inert surface for
contacting the catalyst. A composite waveform may be used for any
exothermic reaction, including a hydroprocessing reactions.
[0096] The term "bulk flow direction" refers to the vector through
which fluid may travel in an open path in a channel.
[0097] The term "bulk flow region" refers to open areas within a
channel (e.g., a process microchannel). A contiguous bulk flow
region may allow rapid fluid flow through a channel without
significant pressure drop. In one embodiment, the flow in the bulk
flow region may be laminar. A bulk flow region may comprise at
least about 5% of the internal volume and/or cross-sectional area
of a microchannel, and in one embodiment from about 5% to about
100%, and in one embodiment from about 5% to about 99%, and in one
embodiment about 5% to about 95%, and in one embodiment from about
5% to about 90%, and in one embodiment from about 30% to about 80%
of the internal volume and/or cross-sectional area of the
microchannel.
[0098] The term "open channel" refers to a channel (e.g., a
microchannel) with a gap of at least about 0.01 mm that extends all
the way through the channel such that fluid may flow through the
channel without encountering a barrier to flow. The gap may have an
internal dimension normal to the flow of fluid through the
microchannel in the range from about 0.01 to about 10 mm, and in
one embodiment from about 0.01 to about 5 mm, and in one embodiment
from about 0.01 to about 2 mm, and in one embodiment from about
0.01 to about 1 mm.
[0099] The term "cross-sectional area" of a channel (e.g., process
microchannel) refers to an area measured perpendicular to the
direction of the bulk flow of fluid in the channel and may include
all areas within the channel including any surface features that
may be present, but does not include the channel walls. For
channels that curve along their length, the cross-sectional area
may be measured perpendicular to the direction of bulk flow at a
selected point along a line that parallels the length and is at the
center (by area) of the channel. Dimensions of height and width may
be measured from one interior channel wall to the opposite interior
channel wall. These dimensions may be average values that account
for variations caused by surface features, surface roughness, and
the like.
[0100] The term "open cross-sectional area" of a channel (e.g.,
process microchannel) refers to an area open for bulk fluid flow in
a channel measured perpendicular to the direction of the bulk flow
of fluid flow in the channel. The open cross-sectional area may not
include internal obstructions such as surface features and the like
which may be present.
[0101] The term "superficial velocity" for the velocity of a fluid
flowing in a channel refers to the velocity resulting from dividing
the volumetric flow rate of the fluid at the inlet temperature and
pressure of the channel divided by the cross-sectional area of the
channel.
[0102] The term "free stream velocity" refers to the velocity of a
stream flowing in a channel at a sufficient distance from the
sidewall of the channel such that the velocity is at a maximum
value. The velocity of a stream flowing in a channel is zero at the
sidewall if a no slip boundary condition is applicable, but
increases as the distance from the sidewall increases until a
constant value is achieved. This constant value is the "free stream
velocity."
[0103] The term "process fluid" refers to reactants, product,
diluent and/or other fluid that enters, flows in and/or flows out
of a process microchannel.
[0104] The term "reactants" refers to hydrocarbon reactants and
hydrogen when used with reference to the inventive hydroprocessing
process.
[0105] The term "reaction zone" refers to the space within a
microchannel wherein a chemical reaction occurs or wherein a
chemical conversion of at least one species occurs. The reaction
zone may contain one or more catalysts.
[0106] The term "graded catalyst" refers to a catalyst with one or
more gradients of catalytic activity. The graded catalyst may have
a varying concentration or surface area of a catalytically active
metal. The graded catalyst may have a varying turnover rate of
catalytically active sites. The graded catalyst may have physical
properties and/or a form that varies as a function of distance. For
example, the graded catalyst may have an active metal concentration
that is relatively low at the entrance to a process microchannel
and increases to a higher concentration near the exit of the
process microchannel, or vice versa; or a lower concentration of
catalytically active metal nearer the center (i.e., midpoint) of a
process microchannel and a higher concentration nearer a process
microchannel wall, or vice versa, etc. The thermal conductivity of
a graded catalyst may vary from one location to another within a
process microchannel. The surface area of a graded catalyst may be
varied by varying size of catalytically active metal sites on a
constant surface area support, or by varying the surface area of
the support such as by varying support type or particle size. A
graded catalyst may have a porous support where the surface area to
volume ratio of the support is higher or lower in different parts
of the process microchannel followed by the application of the same
catalyst coating everywhere. A combination of two or more of the
preceding embodiments may be used. The graded catalyst may have a
single catalytic component or multiple catalytic components (for
example, a bimetallic or trimetallic catalyst). The graded catalyst
may change its properties and/or composition gradually as a
function of distance from one location to another within a process
microchannel. The graded catalyst may comprise rimmed particles
that have "eggshell" distributions of catalytically active metal
within each particle. The graded catalyst may be graded in the
axial direction along the length of a process microchannel or in
the lateral direction. The graded catalyst may have different
catalyst compositions, different loadings and/or numbers of active
catalytic sites that may vary from one position to another position
within a process microchannel. The number of catalytically active
sites may be changed by altering the porosity of the catalyst
structure. This may be accomplished using a washcoating process
that deposits varying amounts of catalytic material. An example may
be the use of different porous catalyst thicknesses along the
process microchannel length, whereby a thicker porous structure may
be left where more activity is required. A change in porosity for a
fixed or variable porous catalyst thickness may also be used. A
first pore size may be used adjacent to an open area or gap for
flow and at least one second pore size may be used adjacent to the
process microchannel wall.
[0107] The term "volume of catalyst" or "cubic meter of catalyst"
refers to the volume of the catalytically active portion of a
catalyst. For a bed of particulate solids the terms "volume of
catalyst" or "cubic meter of catalyst" may refer to the volume of
the space in which the active catalyst is loaded.
[0108] The term "heat exchange channel" refers to a channel having
a heat exchange fluid in it that gives off heat and/or absorbs
heat. The heat exchange channel may absorb heat from or give off
heat to an adjacent channel (e.g., process microchannel) and/or one
or more channels in thermal contact with the heat exchange channel.
The heat exchange channel may absorb heat from or give off heat to
channels that are adjacent to each other but not adjacent to the
heat exchange channel. In one embodiment, one, two, three or more
channels may be adjacent to each other and positioned between two
heat exchange channels.
[0109] The term "heat transfer wall" refers to a common wall
between a process microchannel and an adjacent heat exchange
channel where heat transfers from one channel to the other through
the common wall.
[0110] The term "heat exchange fluid" refers to a fluid that may
give off heat and/or absorb heat.
[0111] The term "heat exchange medium" refers to a substance or
device that absorbs heat or gives off heat and may be used to cool
or heat another substance or device. The another substance or
device may be, for example, a channel that is adjacent to or in
thermal contact with the heat exchange medium. An example of a heat
exchange medium would be a heat exchange fluid in a heat exchange
channel.
[0112] The term "conversion of reactant" refers to the reactant
mole change between a fluid flowing into a microchannel reactor and
a fluid flowing out of the microchannel reactor divided by the
moles of reactant in the fluid flowing into the microchannel
reactor.
[0113] The term "converted basis yield" or "CBY" is used herein
with respect to a hydrocracking process to refer to the mass of
product with 10 to 22 carbon atoms, minus the mass of feed with 10
to 22 carbon atoms, divided by the mass of feed with more than 22
carbon atoms. Converted basis yield or CBY may be represented by
the expression:
CBY=[(Mass C.sub.10-C.sub.22 Product)-(Mass C.sub.10-C.sub.22
Feed)]/(Mass C.sub.22.sup.+Feed)
[0114] The term "total basis yield" or "TBY" is used herein with
respect to hydrocracking to refer to the mass of product with 10 to
22 carbon atoms minus the mass of feed with 10 to 22 carbon atoms
divided by the mass of feed. Total base yield or TBY may be
represented by the expression:
TBY=[(Mass C.sub.10-C.sub.22 Product)-(Mass C.sub.10-C.sub.22
Feed)]+(Mass Feed)
[0115] The term "selectivity" is used herein with respect to a
hydrocracking process to refer to the mass of product with 10 to 22
carbon atoms minus the mass of feed with the 10 to 22 carbon atoms
divided by the mass of feed with more than 22 carbon atoms minus
the mass of product with more than 22 carbon atoms. Selectivity may
be represented by the expression:
Selectivity=[(Mass C.sub.10-C.sub.22 Product)-(Mass
C.sub.10-C.sub.22 Feed)]+[(Mass C.sub.22.sup.+Feed)-(Mass
C.sub.22.sup.+Product)]
[0116] The term "cycle" is used herein to refer to a single pass of
the reactants through a process microchannel.
[0117] The term "solid substrate" may refer to a granular particle
with a mean diameter of less than about 2 mm, and in one embodiment
less than about 1 mm, and in one embodiment in the range from about
0.01 to about 2 mm, and in one embodiment in the range from about
0.05 to about 2 mm, and in one embodiment in the range from about
0.05 to about 1.5 mm, and in one embodiment in the range from about
0.05 to about 1 mm, and in one embodiment in the range from about
0.05 mm to about 0.5 mm. The solid substrate may comprise a
continuous porous medium that substantially spans the gap of a
microchannel. The porous medium may be in the form of a foam, wad,
strands, and/or monolith with either regular or irregular shaped
pores. The pores may be interconnected. The porous medium may
comprise a waveform with a porosity throughout the thickness of the
waveform of from about 5% to about 95% or with a porosity for a
portion of the thickness of the waveform ranging from about 5% to
about 95%. The solid substrate may be housed continuously
throughout the entire length of a process microchannel or part of
the length of a process microchannel. The solid substrate may be
housed in several regions along the length of a process
microchannel. The width and/or height of the process microchannel
within the one or more regions may vary along the length of the
process microchannel.
[0118] The term "quench" refers to a process by which a chemical
reaction is terminated using a rapid reduction in temperature of
the reaction mixture, a rapid introduction of a reactant or
non-reactant fluid into the reaction mixture, or flowing the
reaction mixture through a restricted opening or passageway having
a dimension at or below the quench diameter.
[0119] The term "quench diameter" refers to the internal dimension
(e.g., height, width, diameter) of an opening or passageway for a
reaction mixture to flow through below which the reaction
terminates.
[0120] The term "ash" refers to the solid residue that remains
after a carbonaceous material is burned.
[0121] The term "mm" may refer to millimeter. The term "nm" may
refer to nanometer. The term "ms" may refer to millisecond. The
term ".mu.s" may refer to microsecond. The term ".mu.m" may refer
to micron or micrometer. The terms "micron" and "micrometer" have
the same meaning and may be used interchangeably. The term m/s may
refer to meters per second. Unless otherwise indicated, all
pressures are expressed in terms of absolute pressure.
[0122] The inventive process involves reacting heavy oil and
hydrogen in the presence of a hydroprocessing catalyst in a reactor
under process intensification conditions to form an upgraded
hydrocarbon product. The reactor may be in the form of one or more
process microchannels, or in the form of a microchannel reactor
containing a plurality of process microchannels. The
hydroprocessing catalyst may be a hydrotreating catalyst or a
hydrocracking catalyst.
[0123] Heavy oil typically contains heteroatoms (e.g., nitrogen,
sulfur, oxygen and or metals such as Ni, V, and the like) and the
hydroprocessing process may be used to eliminate or reduce the
level of heteroatoms in the product produced by the process. The
hydrogen reacts with the heteroatoms to produce heteroatom
containing compounds which may then be separated from the
hydroprocessed hydrocarbon product. The process may be used to
reduce the concentration of heteroatoms by to at least about 50% by
weight, or at least about 70% by weight, or at least about 90% by
weight, or at least about 95% by weight, or at least about 99% by
weight. Surprisingly, when the process is conducted under process
intensification conditions and the hydroprocessing catalyst is a
hydrotreating catalyst, the process also hydrocracks the oil to
form a hydrotreated hydrocarbon product which may comprise more
useful upgraded hydrocarbon products (e.g., middle distillate oil,
light oil, or a mixture thereof).
[0124] In one embodiment, the hydrotreated hydrocarbon product may
be further processed in a reactor under process intensification
conditions, such as in one or more process microchannels, or in one
or more microchannel reactors, to provide further hydrocracking and
upgrading of the hydrotreated hydrocarbon product. In this
embodiment, the hydrotreated hydrocarbon product, which may be
referred to as an intermediate hydrocarbon product, reacts with
hydrogen in the presence of a hydrocracking catalyst to further
hydrocrack the hydrotreated hydrocarbon product and form the
desired upgraded hydrocarbon product. The hydrotreating and
hydrocracking processes may be conducted in the same process
microchannel or microchannel reactor, or in different process
microchannels or microchannel reactors.
[0125] The hydrotreating reaction requires reaction between
hydrogen and heavy oil in the presence of a hydrotreating catalyst.
As indicated above, the product produced by the hydrotreating
reaction can be further hydrocracked to form an upgraded
hydrocarbon product. Each of these reactions may be referred to as
hydroprocessing reactions.
[0126] In one embodiment of the invention, the overall process for
converting a heavy oil source (e.g., coal, shale, tar sand,
bitumen, biomass, and the like) to an upgraded hydrocarbon product
is illustrated in FIG. 3. Referring to FIG. 3, the heavy oil source
is converted to heavy oil using gasification, pyrolysis or
liquefaction process. The gasification, pyrolysis or liquefaction
processes may be conducted using conventional techniques or they
may be conducted in a microchannel reactor. Gases and char may be
separated from heavy oil which can be subjected to an optional
cracking process prior to hydroprocessing in accordance with the
inventive process. The optional cracking process may be a thermal
cracking and/or catalytic cracking process. This cracking process
may be conducted using microchannel process technology or
conventional process technology.
[0127] The heavy oil is advanced to a Stage 1 microchannel reactor
wherein the heavy oil undergoes hydrotreating. In the hydrotreating
process the heavy oil is reacted with hydrogen in the presence of a
hydrotreating catalyst under process intensification conditions.
The heavy oil typically contain heteroatoms (e.g., sulfur,
nitrogen, oxygen and/or metals such as Ni, V, and the like). The
heteroatoms react with the hydrogen to form heteroatom-containing
compounds which can be separated from the hydrotreated heavy oil
using conventional or microchannel process techniques (e.g.,
vaporization, condensation, filtration, ionic liquid separation,
temperature swing adsorption, pressure swing adsorption, and the
like). At least about 50% by weight of the heteroatoms in the heavy
oil may be reacted and separated of the heteroatoms in the heavy
oil may be reactant and separated, or at least about 70% by weight,
or at least about 90% by weight, or at least about 95% by weight,
or at least about 99% by weight. Surprisingly, the hydrotreating
process, when conducted under process intensification conditions
such as provided when conducting the process in a process
microchannel or microchannel reactor, also results in a
hydrocracking of the heavy oil wherein at least some of the
hydrocarbons in the oil are hydrocracked to form upgraded
hydrocarbon products such as middle distillate or light oils. Vapor
and water may be separated from the hydrotreated product. The
hydrotreated product, which may be referred to as an intermediate
hydrocarbon product, may then be further processed during Stage 2
in a process microchannel or microchannel reactor by reacting the
hydrotreated hydrocarbon product with hydrogen in the presence of a
hydrocracking catalyst to provide additional hydrocracking with the
result being the formation of an upgraded hydrocracked hydrocarbon
product, which may be in the form of a hydrocracked liquid product.
Vapor and water may be separated from the hydrocracked liquid
product.
[0128] The hydrotreating Stage 1 process and hydrocracking Stage 2
process may be conducted in separate microchannel reactors, with
the hydrocracking Stage 2 reactor being connected in series to the
hydrotreating Stage 1 reactor, the Stage 2 hydrocracking reactor is
downstream of the Stage 1 hydrotreating reactor. This is
illustrated in FIG. 4. Referring to FIG. 4, a plurality of Stage 1
microchannel reactors are housed within a first stage microchannel
reactor housing vessel, which may be referred to as a microchannel
reactor assembly. In FIG. 4, two Stage 1 microchannel reactors are
shown in phantom, although any desired number of Stage 1
microchannel reactors can be housed within the first stage
microchannel reactor housing vessel, for example, from 1 to about
50 Stage 1 microchannel reactors, or from about 3 to about 30
reactors, or from about 3 to about 25 reactors, or from about 5 to
about 20 reactors, or from about 10 to about 20 reactors, or about
15 reactors. In the Stage 1 microchannel reactors, heavy oil is
reacted with hydrogen in the presence of a hydrotreating catalyst
under process intensification conditions to form a hydrotreated
product. As indicated above, the heavy oil contains heteroatoms
which during the hydrotreating reaction react with hydrogen to form
heteroatom-containing compounds. The heavy oil also undergoes
hydrocracking wherein at least some of the hydrocarbon compounds
are hydrocracked. The heteroatom-containing compounds can be
separated from the hydrotreated product. This is not shown in FIG.
4. The hydrotreated product is at least partially hydrocracked and
thus is in the form of a more useable upgraded hydrocarbon product.
The hydrotreated hydrocarbon product may have use, for example, as
a middle distillate or light oil.
[0129] The hydrotreated product, which may be referred to as an
intermediate hydrocarbon product, may be further processed during
Stage 2 wherein the hydrotreated product is hydrocracked in the
Stage 2 microchannel reactors. The Stage 2 microchannel reactors
are housed within the second stage microchannel reactor housing
vessel, which may be referred to as a microchannel reactor
assembly. The Stage 2 microchannel reactors are shown in phantom in
FIG. 4. In FIG. 4, two Stage 2 microchannel reactors are
illustrated, but any desired number, for example, from 1 to about
50 microchannel reactors, or from 1 to about 30 reactors, or from
about 3 to about 25 reactors, or from about 5 to about 20 reactors,
or from about 10 to about 20 reactors, or about 15 reactors may be
used. In the Stage 2 microchannel reactors, the hydrotreated
product from Stage 1 and hydrogen contact a hydrocracking catalyst
under process intensification conditions and undergo a
hydrocracking reaction. The resulting hydrocracked product, which
may be referred to as an upgraded hydrocarbon product, and may be
useful as a middle distillate or light oil.
[0130] The Stage 1 and Stage 2 microchannel reactor housing vessels
contain internal manifolds for flowing reactants into the
microchannel reactors and flowing product out of the microchannel
reactors. The hydrotreating and hydrocracking reactions are
exothermic, and heat exchange fluid flows in heat exchange channels
in the Stage 1 and Stage 2 microchannel reactors to control the
temperature of the reactions. Internal manifolds within the Stage 1
and Stage 2 microchannel reactor housing vessels are provided to
permit the flow of heat exchange fluid into the microchannel
reactor housing vessels, through heat exchange channels in the
microchannel reactors, and then out of the microchannel reactor
housing vessels.
[0131] The Stage 1 hydrotreating step and Stage 2 hydrocracking
step of the inventive process can be conducted in a single
microchannel or microchannel reactor. These process steps can be
conducted in a single microchannel by positioning separate
hydrotreating and hydrocracking catalysts in the same microchannel,
the hydrocracking catalyst being downstream of the hydrotreating
catalyst. Heavy oil and hydrogen flow through the microchannel in
contact with the hydrotreating catalyst to react under process
intensification conditions and form a hydrotreated product.
Additional hydrogen may be added to the microchannel downstream of
the hydrotreating catalyst. The hydrotreated product and hydrogen
flow through the microchannel in contact with the hydrocracking
catalyst to react under process intensification conditions and to
form the desired hydrocracked product, which may be referred to as
an upgraded hydrocarbon product.
[0132] The Stage 1 hydrotreating process and Stage 2 hydrocracking
process may be conducted in a single microchannel reactor. This is
illustrated in FIG. 5. Referring to FIG. 5, process microchannel
layers A and B are positioned one above the other with a heat
exchange channel layer positioned between the process microchannel
layers. Heavy oil and hydrogen flow through the process
microchannel layer A in contact with a hydrotreating catalyst to
react under process intensification conditions and form a
hydrotreated product, which may be referred to as an intermediate
hydrocarbon product. The hydrotreated product flows from process
microchannel layer A to process microchannel layer B where it flows
with additional hydrogen in contact with a hydrocracking catalyst
to react and form the desired hydrocracked product, which may be
referred to as an upgraded hydrocarbon product. Heat exchange fluid
flows through the heat exchange channel layer and is used to
control the temperature in the process microchannel layers.
[0133] With enhanced mass and energy transfer characteristics that
are available when conducting the inventive process under process
intensification conditions such as those available when conducting
the process in process microchannels or microchannel reactors, it
is possible to hydroprocess, that is, hydrotreat and/or hydrocrack,
heavy oil more efficiently using an increased liquid hourly space
velocity (LHSV), a reduced temperature, a reduced pressure, and/or
a reduced H.sub.2 oil (i.e., heavy oil or intermediate hydrocarbon
product) feed ratio, as compared to conventional processing, that
is, processes not employing process intensification conditions such
as available when using microchannels or microchannel reactors.
When conducting the inventive process under process intensification
conditions in process microchannel or microchannel reactors, the
temperature within the process microchannels or microchannel
reactors may be in the range from about 100 to about 500.degree.
C., and in one embodiment from about 250 to about 400.degree. C.
The pressure within the process microchannels or microchannel
reactors may be in the range from about 0.5 to about 25 MPa and in
one embodiment from about 1 to about 20 MPa. The pressure within
the process microchannels or microchannel reactors may be in the
range from about 100 to about 3000 pounds per square inch gauge
(psig) (from about 0.69 to about 20.7 MPa), and in one embodiment
from about 500 to about 2000 psig (from about 3.45 to about 13.8
MPa). The LHSV within the process microchannels or microchannel
reactor may be in the range from about 0.1 to about 200 hr.sup.-1,
and in one embodiment from about 1 to about 100 hr.sup.-1. As
indicated above, the hydrotreating and hydrocracking processes may
be conducted in separate stages within a process microchannel, or
within separate microchannels within a microchannel reactor, or
within separate microchannel reactors. In each case, the reaction
may be conducted in a first stage for hydrotreating and a second
stage for hydrocracking. In the first stage, the LHSV may be in the
range from about 0.1 to about 50 hr.sup.-1, and in one embodiment
from about 5 to about 50 hr.sup.-1. In the second stage the LHSV
may be in the range from about 0.1 to about 20 hr.sup.-1, and in
one embodiment from about 1 to about 20 hr.sup.-1.
[0134] When the Stage 1 and Stage 2 reactions are conducted in a
single process microchannel, multiple reaction zones within the
process microchannel may be employed. Each zone may contain a
different catalyst, or be operated at a different temperature, or
the fluids flowing in the process microchannel may flow in
different zones at different superficial velocities. The employment
of different superficial velocities within different zones within a
process microchannel may be achieved by employing different
internal dimensions (e.g., different heights and/or widths) for the
microchannel. The ratio of H.sub.2 to oil (i.e., heavy oil or
intermediate hydrocarbon product) may be varied by the addition of
additional amounts of H.sub.2 between the separate reaction
zones.
[0135] With the inventive process employing one or more process
microchannels, one or more microchannel reactors, or one or more
microchannel reactor assemblies, it is possible to conduct the
process at any desired production level. For example, it is
possible to process heavy oil at relatively low levels of
production and yet conduct the hydroprocessing process at an
efficient and cost effective level. For example, it is possible to
convert a heavy oil source such as biomass to heavy oil and then
hydroprocess the heavy oil in a single plant at a relatively low
production level of, for example, up to about 5000 barrels per day
(bpd) of heavy oil, or even less, for example, up to about 500 bpd.
The plant site may be used to both hydrotreat and hydrocrack the
heavy oil to provide an upgraded hydrocarbon product for transport
from the plant, e.g., via truck transport or pipeline, or for
further refining at the plant. The plant may also be used to
initially convert the heavy oil source material, e.g., biomass, to
heavy oil and then hydrotreat to form an intermediate hydrocarbon
product at the plant followed by transportation of the intermediate
hydrocarbon product to another location for further processing. The
intermediate hydrocarbon product is suitable for transportation
although it may contain a higher heteroatom content than desired
for a finished upgraded hydrocarbon product. The high heteroatom
content can be removed by further hydroprocessing. For example, the
heavy oil may be converted to a partially hydrogenated intermediate
hydrocarbon product in which more than about 50% by weight of the
heteroatom components are converted on site, and then the partially
hydrotreated intermediate hydrocarbon product is transported to a
facility for blending with other hydrocarbons for further
refining.
[0136] The inventive process may be used to convert heavy oil vapor
to an upgraded hydrocarbon product. This process is illustrated in
FIG. 27. Referring to FIG. 27, heavy oil and oxygen are gasified in
a heavy oil gasifier. The gasification step may be conducted in a
counter-current fixed bed gasifier, a co-current fixed bed
gasifier, a fluidized bed gasifier or an entrained flow gasifier.
In the gasifier, heavy oil vapor and char are formed. The char is
separated from the heavy oil vapor. In alternative embodiments, the
heavy oil vapor may be created by pyrolysis. The heavy oil vapor is
cooled to a temperature in the range of about 200.degree. C. to
about 500.degree. C., and in one embodiment from about 350.degree.
C. to about 450.degree. C. The cooled heavy oil vapor is reacted
with hydrogen in the presence of a hydrocracking catalyst in a
condenser hydrocracker under process intensification conditions.
The condenser hydrocracker comprises one or more process
microchannels or one or more microchannel reactors. The heavy oil
vapor and hydrogen may be mixed with each other in the condenser
hydrocracker or upstream of the condenser hydrocracker. In the
condenser hydrocracker, the heavy vapor is condensed and
hydrocracked to form an upgraded hydrocarbon product. Heat exchange
fluid flows in and out of the condenser hydrocracker to provide
coolant to control the hydrocracking reaction, which is exothermic,
and to condense the upgraded hydrocarbon product. The upgraded
hydrocarbon product flows out of the condenser hydrocracker, and
then through a heat exchanger where it is further cooled and flows
to a liquid/vapor phase separator. In the liquid/vapor phase
separator, the upgraded hydrocarbon product is separated into a
vapor and an upgraded hydrocarbon liquid product. The vapor may be
recycled to the condenser hydrocracker or it may be used as a
valuable hydrocarbon vapor product, or it may be vented to an
exhaust.
[0137] The condenser-hydrocracker shown in FIG. 27 is illustrated
in FIGS. 28 and 29. The condenser hydrocracker comprises one or
more vertically oriented process microchannels containing a
hydrocracking catalyst. The heavy oil vapor and hydrogen flow
downwardly through the process microchannels in contact with the
hydrocracking catalyst, condense and undergo a hydrocracking
reaction. Heat exchange fluid flows through heat exchange channels
that are aligned in a cross-current direction relative to the flow
of fluid in the process microchannels. The heat exchange fluid
provides coolant to control the reaction, which is exothermic, and
condense the hydrocracked hydrocarbon product.
[0138] The heavy oil vapor may be hydrocracked in a two-stage
hydrocracking process. This is illustrated in FIG. 30. Referring to
FIG. 30, heavy oil vapor and hydrogen flow into hydrocracking
reactor Stage 1 where the heavy oil vapor and hydrogen contact a
hydrocracking catalyst, react under process intensification
conditions and form a first hydrocracked hydrocarbon product. The
first hydrocracked hydrocarbon product flows to a liquid/vapor
separator where heavy upgraded oil is separated from vaporous oil.
The vaporous oil is combined with hydrogen and flows to
hydrocracking reactor Stage 2 where the vaporous oil and hydrogen
react in the presence of a hydrocracking catalyst under process
intensification conditions to form a second hydrocracked
hydrocarbon product. The second hydrocracked hydrocarbon product is
advanced to a liquid/vapor phase separator where it is separated
into a light upgraded oil and vapor. The vapor can be recycled to
the Stage 1 or Stage 2 hydrocracking reactor or it can be vented to
exhaust. The vapor may also be employed as a valuable hydrocarbon
product.
[0139] The heavy oil may be hydrocracked in a catalytic
distillation column in which one or more catalyst beds comprising
hydrotreating or hydrocracking catalysts are positioned in a
distillation column.
[0140] The heavy oil may be hydrocracked in a series of condenser
hydrocrackers positioned in a distillation column. This is
illustrated in FIG. 31. Referring to FIG. 31, heavy oil vapor and
hydrogen are advanced to distillation column 500 which, as
illustrated, contains three condenser hydrocrackers 502, 504 and
506, positioned one above another, a distillate end 510 and a
bottoms end 512. It will be understood that any number of condenser
hydrocrackers may be employed in the distillation column 500, for
example, from 1 to about 1000 condenser hydrocrackers may be used,
or from 1 to about 100, or from 1 to about 20, or from 1 to about
10, or from 1 to about 5. The distillation column 500 has a
distillate end 510 and bottoms end 512. Heavy oil vapor and
hydrogen flow upwardly through each of the condenser hydrocrackers
502, 504 and 506 toward the distillate end 510. In each condenser
hydrocracker heavy oil vapor contacts a hydrocracking catalyst, and
condenses and undergoes a hydrocracking reaction under process
intensification conditions. The catalyst in each of the condenser
hydrocrackers 502, 504 and 506 may be in the form of a packing
(e.g., bales, monoliths, structured packings comprising catalyst,
structured packing coated with catalyst, foams, felts, honeycombs,
and the like). Hydrocarbon vapor flows out of the distillate end
510 of the distillation column 500. The hydrocarbon vapor flowing
out of the distillation column 500 is cooled in heat exchanger 514
and advanced to a liquid/vapor phase separator 516. In the
liquid/vapor phase separator 516, the distillate is separated into
a gas and a light oil. The gas contains H.sub.2 and may be recycled
to a gasifier where the heavy oil is vaporized. The light oil is
either removed as a valuable product or recycled back through the
distillation column 500 flowing toward the bottoms end 512 for
further hydrocracking. At midway points in the distillation column
Oil Cut Number 1 and Oil Cut Number 2 are removed from the
distillation column. Other oil cuts not shown in the drawings may
also be removed. Oil Cut Numbers 1 and 2 may be referred as middle
distillates. A bottoms fraction is extracted from the bottoms end
512 of the distillation column.
[0141] The heavy oil source material may comprise any carbonaceous
material that can be converted to a heavy oil. The carbonaceous
material may be a solid carbon-containing material. The
carbonaceous material may comprise coal, shale, tar sand, bitumen
or biomass. The carbonaceous material may comprise a food resource
such as corn, soybean, and the like. The carbonaceous material may
comprise a non-food resource. The non-food resource may be referred
to as a second generation biofuel. The non-food resource may
comprise any carbonaceous material not generally used as a food.
The non-food resource may be referred to as a non-food carbonaceous
material. Examples of the non-food carbonaceous materials that may
be used may comprise coal (e.g., low grade coal, high grade coal,
and the like), oil (e.g., crude oil, heavy oil, tar sand oil, and
the like), biomass, solid wastes, or a mixture of two or more
thereof. The non-food carbonaceous material may comprise municipal
solid waste (MSW), hazardous waste, refuse derived fuel (RDF),
tires, petroleum coke, trash, garbage, biogas from a digester,
sewage sludge, animal waste (e.g., chicken manure, turkey manure,
cow manure, horse manure, as well as other animal waste),
agricultural waste, corn stover, switch grass, timber, wood
cuttings, grass clippings, construction demolition materials,
plastic materials (e.g., plastic waste), cotton gin waste, landfill
gas, natural gas, and the like. The non-food carbonaceous material
may comprise polyethylene or polyvinyl chloride. Mixtures of two or
more of any of the foregoing may be used.
[0142] The carbonaceous material may contain solids or solid
forming species. These may include products derived from coal
(which may contain coal ash constituents) biomass (minerals, etc.),
animal derived products (chicken fat, fryer oils, etc.), heavy
crudes (which often contain Ni and/or V species). It may therefore
be necessary to remove these species prior to processing, whether
using conventional or microchannel operations. The removal process
may include filtration (especially for coal or mineral ashes and
for animal derived feeds, for example, chicken fat may contain
feathers, beaks, bones, etc.) or reactive removal such as a guard
bed, which may comprise a removable cartridge in a microchannel
reactor system. This may be particularly important for Ni, V, and
the like, in heavy crudes where the metals may not be formed as a
solid until the metal compounds are decomposed by higher
temperatures, with or without additional reactants, for example,
H.sub.2.
[0143] Conventional hydrotreating and hydrocracking catalysts may
be used. Examples of conventional hydrotreating and hydrocracking
catalysts may include those with a support which may comprise an
amorphous material (e.g., alumina, silica alumina, titania,
zirconia, or a combination of two or more thereof), zeolite,
layered clay, pillared clay, or any material with acid sites, or a
combination of two or more of the foregoing materials. The support
may be further impregnated with a metal species which enhances
hydrotreating or hydrocracking. The metal species may comprise
platinum, palladium, nickel, molybdenum, tungsten, or a combination
of two or more of the foregoing metals. As a result of the
inventive process being conducted under process intensification
conditions, the catalyst may be in a more active form than those
used in conventional processes.
[0144] The use of microchannels for hydrotreating and hydrocracking
reactions provides for process intensification conditions on a
number of fronts. These may include kinetics, pressure drop, heat
or energy transfer, and mass transfer. Conventional hydroprocessing
reactions (e.g., hydrocracking reactions and hydrotreating
reactions) not employing microchannel processing may be constrained
by heat removal and require catalysts of sufficient but not high
activity. On the other hand, microchannels may allow for higher
activity catalysts than may be typically used with conventional
reactors. For example, the heat of reaction may be removed more
effectively with a microchannel reactor than with a conventional
reactor by using heat exchange channels interspersed or in thermal
contact with process microchannels in the microchannel reactor. A
microchannel processing unit may be used as a polishing unit
downstream of a conventional hydroprocessing unit in order to add
additional hydrotreating and/or hydrocracking to the product
produced by the conventional hydroprocessing unit.
[0145] Although the microchannel dimension of height or width may
be smaller than the diameter of a conventional reactor, pressure
drop may be dominated by flow through the catalyst bed, which may
comprise a packed bed, porous media, or other catalyst form. The
catalyst may take the form of pellets, beads, particles, foam, wad,
felt, honeycomb, or other structure with either regular or
irregular shape or form. Flow lengths in the process microchannel
may range from 0.05 to about 10 meters, and in one embodiment from
about 0.05 to about 5 meters, and in one embodiment from about 0.05
to about 2 meters, and in one embodiment from about 0.1 to about
1.5 meters, and in one embodiment from about 0.1 to about 1 meter,
and in one embodiment from about 0.1 to about 0.7 meter. Shorter
flow lengths may allow for a reduction in catalyst particle
diameter to achieve a net neutral or lower process pressure drop
than with a conventional hydrocracker. In some embodiments, a
higher pressure drop may be useful. Further, the inlet pressure of
the liquid stream and the gaseous stream may not be the same. A
pressure drop or pressure let down before the reaction zone within
a process microchannel may be useful to control the flow
distribution of the gas and liquid. The inlet pressure of the
liquid may be greater than the inlet pressure for gas. The pumping
power for a liquid may be less than the compression required for a
gas. Alternatively, the gas may be at a higher inlet pressure than
the liquid.
[0146] For the hydrotreating and hydrocracking reactions, heat
release control may require reactor designs with interstage
cooling, liquid redistribution, and/or quench sections.
Microchannel reactors employing process microchannels for
conducting the hydroprocessing reactions may employ local heat
removal with heat exchange or coolant channels interspersed with
the process microchannels.
[0147] Microchannel reactors may be used to enable a reduction in
both intraparticle and interparticle mass transfer resistance. When
using a catalyst in the form of catalyst particles or particulates,
the average particle diameter may be in the range from about 0.01
to about 1.5 mm, and in one embodiment from about 0.05 to about 0.5
mm, and in one embodiment from about 0.1 to about 0.3 mm. On the
other hand, a conventional hydrocracker may use a catalyst pellet
with an average diameter that ranges from about 2 to about 10
mm.
[0148] The reduction in catalyst particle diameter may improve the
effective use of internal catalyst sites over conventional
hydrocracking reactors. The effectiveness factor for a catalyst may
be a function of the Thiele modulus. For a spherical catalyst
particle, the Thiele modulus is proportional to the radius divided
by 3. For equal intrinsic reaction rates on the active catalyst
sites, a ten-fold reduction in the catalyst diameter will result in
a tenfold reduction in the Thiele modulus. The Thiele modulus is
not directly proportional to effectiveness factor. For a Thiele
modulus less than one a fairly high effectiveness factor may be
expected. If the Thiele modulus is greater than one, a much steeper
decline in the effectiveness factor may be expected. The actual
impact of particle size depends upon the intrinsic reaction rates,
the diffusivity of reactants within the catalyst particle, and the
tortuosity of mass diffusion within the catalyst particle.
[0149] The reduction in interparticle mass transfer resistance may
be less straightforward. The microchannel dimension and associated
small catalyst particles housed therein may promote capillary
forces over viscous and body forces. The net result may be a well
dispersed liquid film that improves the contact of all phases with
the catalyst to improve the apparent catalyst activity.
[0150] The Capillary number (Ca) defines the ratio of viscous to
interfacial forces
Ca = .mu. velocity .sigma. ##EQU00001##
where the viscosity of a liquid feedstock can been approximated
using known high temperature and high pressure hydrocarbon data and
surface tension values. In this formula .mu. velocity refers to
viscosity, and .delta. refers to surface tension. For example, the
viscosity of an eicosane fluid at 200 psi and 261.degree. C. is
0.338 cP. Creating a functional dependency on temperature for this
fluid results in an exponential dependency, where the viscosity is
proportional to 3.53.times.exp(-0.0091.times.Temperature (in
degrees C.)). For a 370.degree. C. hydrocracking reaction mixture,
the viscosity is approximated as 0.12 cP. Measurements of the
surface tension of the feedstock on the catalyst particle are
roughly one-third the surface tension of water. For a reaction
system with an actual linear velocity of 0.3 m/s, which corresponds
to a hydrocracking process with a LHSV of 30 hr.sup.-1, a bed void
of 0.35, and 1500:1 hydrogen to feed ratio, the estimated capillary
number is about 1.5.times.10.sup.-3. For this reaction condition,
the conversion of a hydrocarbon product with a boiling point below
350.degree. C. may be essentially complete, or greater than 99%. In
one embodiment, the conversion may be greater than 50%, or greater
than 80%, per pass. The capillary number for a multiphase reaction
in a microchannel reactor may be in the range from about 10.sup.-2
to about 10.sup.-6.
[0151] The Bond number (Bo) defines the ratio of body forces (e.g.,
gravity) to interfacial forces (capillary forces). For low Bond
numbers, interfacial capillary forces that spread the liquid
throughout the reaction chamber may be stronger than gravitational
forces that force the liquid to coalesce and drip or trickle
through the reactor.
Bo = .rho. gL 2 .sigma. , ##EQU00002##
where the density of the feedstock can be approximated by known
high temperature and high pressure hydrocarbon data and surface
tension values for the liquid hydrocarbon feedstock. In this
formula, .rho. refers to density, g refers to the gravitational
constant, L refers to the critical length, and .delta. refers to
surface tension. A bond number may be calculated for a
microchannel, e.g. channel bond number, where the critical length
is the smallest channel dimension which is typically the channel
gap or height of the microchannel. A bond number may be calculated
for the particle, e.g. particle bond number, where the critical
length is the particle diameter. A bond number may be calculated
for the microchannel length, e.g. length bond number, where the
critical length is the flow length of the reactor itself. The three
bond numbers may help determine whether the hydrocracker liquid may
preferentially spread via capillary forces in the defined critical
length or fall with gravity.
[0152] The channel bond number may be in the range from about 0.001
to about 2. The bond number may be less than about 1, and in one
embodiment in the range from about 0.001 to about 0.999, and in one
embodiment from about 0.01 to about 0.95, and in one embodiment
from about 0.1 to about 0.9. Using the numbers from the previous
example for a microchannel reaction zone with a height of 1.75 mm
and a liquid density of 0.6 gm/cc, the Bond number is 0.75. For
smaller reaction zones, the Bond number reduces further and is 0.25
for a reaction zone with a height of 1 mm.
[0153] The channel Bond number for a hydroprocessing reaction zone
or other multiphase reaction zones with an internal dimension below
about 2 mm may be less than about 1. This suggests that the
interfacial forces to disperse the liquid within the microchannel
may be greater than gravitational forces thus showing the
propensity for the liquid to wet the walls of the microchannel
rather than coalesce and flow down the channel walls with rivulets.
The channel Bond number for a conventional hydrocracking reactor
bed with a diameter as large as 4.5 meters may be greater than
about 10, and typically greater than about 100 or greater than
about 1000. This suggests that gravity dominates in flow of liquid
within the reactor vessel. The conventional hydrocracker or
multiphase reaction chamber faces challenges to keep the liquid
well dispersed and to avoid liquid flow channeling or rivulets
within the packed bed.
[0154] The Bond number for a catalyst particle placed within a
microchannel may be many orders of magnitude below about 1,
suggesting the capillary force may be sufficient to overcome those
forces exerted by gravity and thus the liquid may well wet the
particles rather than coalesce and trickle around the particles in
poorly dispersed streams. For a conventional hydrocracking reactor
particle diameter, the particle Bond number may exceed 1 because
the catalyst particle exceeds 2 mm and is typically in the range
from about 3 to 50 mm. For the hydrocracking reaction fluid
properties, the particle Bond number may approach 1 for a particle
diameter of about 2 mm. The flow of liquid in a conventional
hydroprocessing reactor or other multiphase reactor may be
dominated by gravity and viscous forces rather than the capillary
forces which may act to spread the liquid laterally throughout the
bed. Experiments have been conducted with a 1.5 mm particle and a 3
mm particle, where a liquid oil flows in a downflow orientation
with a co-flow of nitrogen gas under ambient conditions. The
experiment with the 3 mm particle forms uneven flow and rivulets
where the liquid does not fully wet the particle. In comparison,
the experiment with the 1.5 mm particle demonstrates a well wet
liquid and stable flow. There are no rivulets observed for liquid
flow past the 1.5 mm particles where the particle bond number is
less than about 1.
[0155] In an alternate embodiment with the use of a structured
catalyst which is made of any contiguous porous material unlike a
discontinuous particle bed which is comprised of discrete particles
touching each other but not otherwise joined or fused, the critical
length is defined by the minimum dimension of the porous structure.
As an example, if a porous felt, foam, wad, regular structure, or
graded structure with internal porosity has a thickness of 1 mm and
a length and width greater than 1 mm, the particle bond number
would be calculated to be roughly 0.5 for the test conditions of a
flowing oil at 370.degree. C. The use of a particle bond number
includes the extension to a porous structure with a small critical
dimension such that the particle bond number is less than about
1.
[0156] Laboratory test reactors for conventional hydrocrackers are
often tested with very small particles interspersed around
conventional pellets to improve the lateral flow of liquid in the
reactor. While this dual sized particle solution may not be
practical from a pressure drop perspective for a conventional
hydrocracker, it shows the importance of internal liquid
distribution on the performance of the catalyst and that the large
catalyst particles selected for conventional hydrocracking reactors
may retain poor wetting by the liquid.
[0157] The result may be that the small catalyst particles in
microchannels may create a fluidic environment dominated by
capillary forces for the reaction. Unlike conventional
hydrocrackers, where the liquid channels within the bed, liquid
flow in a microchannel may remain well dispersed across the
channel. A conventional reactor requires periodic collection and
redistribution of liquid within the reactor, whereas a microchannel
may not. Further, a laterally well distributed liquid flow allows a
gas to shear or thin the liquid film rather than segment the
reactor bed into unsteady and intermittent zones of gas and liquid
films.
[0158] The length bond number for a microchannel will typically
exceed 1 as it does for a conventional hydrocracking reactor. The
length bond number may not be the critical parameter, where the
particle and channel bond number are more important for
establishing well wetted catalyst particles with stable liquid
flow. An additional component to reducing mass transfer resistance
for the contact of the gas, liquid, and solid catalyst may be built
upon processes with a particle bond number less than about 1. The
stable and thin films may be further thinned by the high gas
velocity.
[0159] With a laterally well dispersed liquid film within a
microchannel reactor, that has sufficient capillary force to resist
segmentation or flow rivulets, the film thickness may be further
thinned by high gas velocity in the microchannel. The reduction in
liquid film around the particle may reduce the mass transfer
resistance for a gas such as hydrogen to access the catalyst
particle. For a hydroprocessing reaction, the mean film thickness
for the liquid when using hydrogen gas with a 0.24 m/s superficial
velocity may be about 5 microns. For a hydrogen gas with a velocity
of 0.009 m/s passing against a thin film of the hydrocarbon liquid,
a mean film thickness of about 20 microns may be expected. For
these two cases, a four-fold reduction in liquid film thickness may
correspond to a 16 fold reduction in time for the gaseous hydrogen
to diffuse through the liquid film to the catalyst surface.
Further, the time for the liquid reactant to diffuse within the
liquid film to the catalyst on and in the catalyst particles or
surface may also be reduced roughly with the square of the film
thickness. Given that diffusivity of a liquid may be two to three
orders of magnitude greater than the diffusion of a gas, the liquid
diffusion within the liquid layer to the catalyst surface may
dominate the transport resistance contribution to the overall
apparent rate of reaction. The surface rate of reaction on the
catalyst may be rate limiting. From a control volume analysis
around a catalyst particle, a comparison of diffusion time to
convection time may suggest the importance of reduced film
thickness on the hydroprocessing reaction rate. As the amount of
time available for a gas such as hydrogen to diffuse through a
thicker liquid film increases, the corresponding amount of
additional gas fed to the reaction system in excess may decrease
thus providing surprising results with a lower excess hydrogen
required for a microchannel hydrocracker.
[0160] The diffusion time for a thin film may be the square of the
diffusion distance divided by the diffusivity. The diffusivity for
hydrogen in a hydrocarbon liquid may be about 4.3.times.10.sup.-4
cm.sup.2/s. For a 20 micron film thickness, the diffusion time may
be about 10 ms. For a 5 micron film thickness, the time for
diffusion across the thin film surrounding a catalyst particle may
be about 0.5 ms.
[0161] The convection time in a control volume around a catalyst
particle of about 110 microns diameter for a superficial gas
velocity of about 0.3 m/s may be about 1 ms. For the same
microchannel dimensioned particle size of a mean diameter of about
110 microns, the impact of a film thickness ranging from about 5
microns to about 20 microns imparts a capture number difference of
about 2 to about 0.1. The capture number is the time for convection
divided by the time for diffusion. For the 5 micron thin film, the
gas spends roughly twice the amount of time around the catalyst as
it takes to diffuse to the active catalyst sites. For the 20 micron
film at equal superficial gas velocity, the gas requires roughly
ten times more time to diffuse to the catalyst sites (10 ms) than
available as it flows around the particle (1 ms). In this latter
case, there may be much more catalyst required to achieve the same
level of reaction. This excess catalyst may range from about 2 to
about 200 times more catalyst as compared to a high velocity
microchannel. The result may be that a higher excess amount of
hydrogen is required as the capture number drops below 1.
[0162] For a larger particle size, as expected in a conventional
reactor (where roughly 2 mm is near the low end of diameter), the
convection time in a control volume around a catalyst particle is
longer. However, the flow dynamics of the lower velocity gas around
this larger particle also give rise to much thicker films. For a
100 micron liquid film that is either regular or intermittent
flowing or trickling down a conventional reactor, the required time
for diffusion across the film is roughly about 200 milliseconds.
Correspondingly, for a superficial velocity of about 0.02 m/s, the
convection time in a control volume around a 2 mm particle is
roughly 100 ms. The capture number may remain less than 1, near 1
or even greater than 1, suggesting the importance of excess
hydrogen that may remain in the liquid film to conduct the reaction
in a conventional hydrocracker. The thick films found in a
conventional hydrocracker may require substantially more mass
transfer time for the hydrogen and liquid reactants to reach the
solid catalyst particle to react.
[0163] The result of this may be less access of the hydrogen to the
catalyst. A conventional hydrocracker may overcome this limitation
by increasing the amount of hydrogen excess fed to the system. A
microchannel reaction system offers the potential to reduce the
amount of excess hydrogen.
[0164] The inventive process is applicable to any hydroprocessing
reaction conducted in a microchannel when the particle Bond number
is less than about 1 and/or the reaction chamber Bond number is
less than about 1.
[0165] The heavy oil feed, intermediate hydrocarbon product feed
and/or H.sub.2 feed may be introduced into a manifold on one side
of the reactor. Flow may traverse laterally across the reactor or a
shim through a submanifold. From the submanifold, flow may pass
through a flow restriction section, where pressure drop may be
imparted to improve the uniformity of the flow in each of the
mating microchannels. The flow may then pass through connection
apertures to enter the reactor. The connection apertures may be
positioned upstream from the catalyst, but in alternate embodiments
the connection apertures may be adjacent to the catalyst. In one
embodiment, the liquid may flow through the submanifold and through
adjacent connection apertures. The connection apertures may be
regular or irregular in shape.
[0166] The heavy oil feed composition and/or intermediate
hydrocarbon product feed composition may include one or more
diluent materials. Examples of such diluents may include inert
compounds such as nitrogen or non-reactive hydrocarbon diluents,
and the like. The diluent concentration may be in the range from
zero to about 99% by weight based on the weight of the hydrocarbon
reactant, and in one embodiment from zero to about 75% by weight,
and in one embodiment from zero to about 50% by weight. The
diluents may be used to reduce the viscosity of viscous liquid
reactants. An advantage of at least one embodiment of the invention
is that the use of such diluents is avoided, and operation of the
inventive process is more efficient and compact.
[0167] The viscosity of the heavy oil feed composition and/or
intermediate hydrocarbon product feed composition may be in the
range from about 0.001 to about 1000 centipoise, and in one
embodiment from about 0.01 to about 100 centipoise, and in one
embodiment from about 0.1 to about 10 centipoise. The heavy oil
feed composition and/or intermediate hydrocarbon product feed
composition may be in the form of a liquid, a gas, or a combination
thereof.
[0168] The ratio of hydrogen to oil in the heavy oil feed
composition and/or intermediate hydrocarbon product feed
composition may be in the range from about 10 to about 6000
standard cubic centimeters (sccm) of hydrogen per cubic centimeter
(ccm) of oil, and in one embodiment from about 50:1 to about 4000:1
sccm/ccm, and in one embodiment from about 100:1 to about 2000:1
sccm/ccm, and in one embodiment from about 300:1 to about 1500:1
sccm/ccm. The hydrogen feed may further comprise water, methane,
carbon dioxide, carbon monoxide or nitrogen.
[0169] The H.sub.2 in the hydrogen feed may be derived from another
process such as a steam reforming process (product stream with
H.sub.2/CO mole ratio of about 3), a partial oxidation process
(product stream with H.sub.2/CO mole ration of about 2), an
autothermal reforming process (product stream with H.sub.2/CO mole
ratio of about 2.5), a CO.sub.2 reforming process (product stream
with H.sub.2/CO mole ratio of about 1), a coal gasification process
(product stream with H.sub.2/CO mole ratio of about 1), and
combinations thereof. With each of these feed streams the
concentration of H.sub.2 may be increased through the use of
water-gas shift and/or the H.sub.2 may be separated from the
remaining ingredients using conventional techniques such as
membranes or adsorption.
[0170] The upgraded hydrocarbon product made by the inventive
process may be a middle distillate fraction boiling in the range of
about 260-700.degree. F. (127-371.degree. C.). The term "middle
distillate" is intended to include the diesel, jet fuel and
kerosene boiling range fractions. The terms "kerosene" and "jet
fuel" boiling range are intended to refer to a temperature range of
260-550.degree. F. (127-288.degree. C.) and "diesel" boiling range
is intended to refer to hydrocarbon boiling points between about
260 to about 700.degree. F. (127-371.degree. C.). The product may
be a gasoline or naphtha fraction. These are normally considered to
be the C.sub.5 to 400.degree. F. (204.degree. C.) endpoint
fractions.
[0171] The product produced from the inventive process may comprise
C.sub.5.sup.+ hydrocarbons with an iso/normal ratio greater than
about 0.5. The product may comprise C.sub.20.sup.+ hydrocarbons
with an iso/normal ratio that is greater than about 1. The product
may comprise C.sub.10.sup.+ hydrocarbons with an iso/normal ratio
greater than about 1 when the weight hourly space velocity (WHSV)
for the flow of liquid product is less than about 20 hr.sup.-1. The
cloud point for the product may be less than about -10.degree.
C.
[0172] When the inventive process is conducted using, for example,
a low operating pressure or low hydrogen partial pressure, the
resulting product that is formed may comprise straight chain
aliphatic compounds as well as alicyclic and aromatic compounds.
The formation of alicyclic and aromatic compounds is undesirable
and is typically avoided in conventional processing using
non-microchannel reactors due to the fact that these compounds tend
to interfere with the catalyst. However, the formation of these
compounds is permissible with the inventive process due to the fact
that the catalyst can be regenerated periodically without causing
significant production disruptions.
[0173] The reactants or process feed may further comprise a recycle
stream from which the hydrocracked products, and optionally other
components, have been separated out, for example, by distillation
or partial condensation.
[0174] The reactants may comprise one or more gases at reaction
conditions which react to form a liquid. The reactants may comprise
one or more gases that form a liquid that continues to react. The
reactants may comprise a liquid and gas at reaction conditions that
flow concurrently through the process microchannel. The reactants
may comprise one or more liquids that are fed with an inert gas to
improve interfacial contact with the catalyst to enhance the
reaction rate.
[0175] The local conditions in a process microchannel or a
microchannel reactor may be controlled via tailoring temperature
and/or composition profiles via one or more of the following: heat
exchange with heat exchange channels adjacent to or in thermal
contact with the one or more process microchannels in the
microchannel reactor; heat exchange with multiple combinations of
heat exchange channels strategically placed to correspond to
individual reaction sections within the process microchannels;
addition of one or more reactants and/or diluents using staged
addition along the axial length of the process microchannels. An
isothermal reactor profile may be employed. With such a thermal
profile, a partial boiling heat exchange fluid may be used. A
tailored temperature profile along the length of the process
microchannels may be used. Heat may be removed with a single phase
fluid, such as a hot oil, steam, a gas or the like. The heat
exchange fluid may flow in a direction that is co-current,
counter-current or cross-current to the flow of the process fluids
in the process microchannels. The heat exchange fluid may comprise
one of reacting species or non-reacting species that subsequently
joins the reaction mixture after receiving heat from the reaction.
The heat exchange fluid may be used to remove exothermic reaction
heat from the process microchannels, and to preheat the reactants
entering the process microchannels. The reactants may be preheated
to substantially the reaction conditions or they may be partially
preheated from the inlet temperature of the feed to an intermediate
temperature between the average reaction temperature and the inlet
temperature. The heavy oil or intermediate hydrocarbon reactant may
enter the reactor at a temperature below the reaction temperature
to minimize coking and then be heated to the reaction temperature
in the reactor. The heavy oil or intermediate hydrocarbon reactant
entering the microchannel reactor may be at a temperature that is
about 10.degree. C., or about 50.degree. C., or about 100.degree.
C., or more, less than the reaction temperature. In one embodiment,
the heavy oil or intermediate hydrocarbon reactant entering the
microchannel reactor may be at a temperature that is in the range
from about 200.degree. C. to about 250.degree. C., and the reaction
temperature in the microchannel reactor may be in the range from
about 300.degree. C. to about 400.degree. C.
[0176] In order to control the exothermic reaction via heat
exchange with a heat exchange medium, for example, a heat exchange
fluid, the process may employ a heat flux at or near the entrance
to the microchannel reactor that is higher than the heat flux near
the outlet of the microchannel reactor.
[0177] The microchannel reactor used with the inventive process may
contain one or more repeating units, as discussed below. Each of
the repeating units discussed below contains one or more process
microchannels and one or more heat exchange channels. Examples of
some of the repeating units that may be used are illustrated in
FIGS. 8-13 and 25-26. Each of the process microchannels may contain
one or more reaction zones wherein the reactants react to form the
desired product. A catalyst in solid form may be present in the one
or more reaction zones. The catalyst may comprise a homogeneous
catalyst immobilized on a solid. Each repeating unit may contain
one or more heat exchange channels. In one embodiment, each process
microchannel may be combined with one or more adjacent reactant
stream channels to provide for the staged addition of hydrogen into
the process microchannel. The process microchannel and the adjacent
reactant stream channel may have a common wall with a plurality of
openings in the common wall. These openings may be used to provide
for the flow of hydrogen from the adjacent reactant stream channel
into the process microchannel. A feed stream header may be used for
distributing mixtures of the reactants to the process
microchannels. Alternatively, one feed stream header may be used
for distributing hydrocarbon reactants (i.e., heavy oil or
intermediate hydrocarbon reactant) to the process microchannels,
and another header may be used to distribute H.sub.2 to the
adjacent reactant stream channels.
[0178] Although an advantage of the inventive process is that a
high converted basis yield to the desired intermediate hydrocarbon
product or upgraded hydrocarbon product may be obtained with one
pass through the microchannel reactor, in one embodiment, one or
more hydrocarbon reactants may be separated from the hydrotreated
or hydrocracked product using conventional or microchannel
techniques and recycled back through the microchannel reactor. The
hydrotreated or hydrocarbon reactants may be recycled through the
microchannel reactor any number of times, for example, one, two,
three, four times, etc.
[0179] The reactants may be preheated prior to entering the
microchannel reactor. The reactants may be preheated to the average
temperature employed in the reaction zone of the one or more
process microchannels used in the microchannel reactor or to a
temperature that is less than the average temperature employed in
the reaction zone. The hydrotreating and hydrocracking processes
are exothermic. In order to control the reaction, heat may be
transferred from the process microchannels to a heat exchange
medium. That is, during the inventive process the process
microchannels may be cooled using a heat exchange medium. The heat
exchange medium may comprise a heat exchange fluid in one or more
heat exchange channels. The heat exchange channels may be adjacent
to and/or in thermal contact with the process microchannels. The
heat exchange channels may be microchannels. Heat transfer between
the process fluids and heat exchange fluid may be effected using
convective heat transfer. In one embodiment, heat transfer may be
enhanced using a heat exchange fluid wherein the heat exchange
fluid undergoes an endothermic reaction and/or a full or partial
phase change (e.g., partial boiling). Multiple heat exchange zones
may be employed along the length of the process microchannels to
provide for different temperatures at different locations along the
axial lengths of the process microchannels. Also, at the end of the
reaction the product may be quenched in order to reduce or
eliminate the formation of undesired by-products. Quenching may be
effected in the microchannel reactor or downstream of the
microchannel reactor.
[0180] With the inventive process, intermixing of the gaseous and
liquid phases may be enhanced using catalyst beds employing
relatively small particulate solids, for example, particulate
solids with average diameters in the range from about 0.01 to about
1.5 mm, and in one embodiment from about 0.05 to about 0.5 mm, and
in one embodiment from about 0.1 to about 0.3 mm.
[0181] The microchannel reactor may be used in combination with one
or more storage vessels, pumps, compressors, valves,
microprocessors, flow control devices, and the like, which are not
shown in the drawings, but would be apparent to those skilled in
the art.
[0182] The microchannel reactor may be constructed as illustrated
in FIGS. 2A-2C. Referring to FIG. 2A, microchannel reactor 100
comprises a plurality of process microchannels 110, reactant stream
channels 150 and heat exchange channels 170 positioned side-by-side
to provide microchannel reactor 100 in the form of a cubic block.
The cubic block may have a length in the range from about 10 to
about 1000 cm, and in one embodiment in the range from about 20 to
about 200 cm. The cubic block may have a width in the range from
about 10 to about 1000 cm, and in one embodiment in the range from
about 20 to about 200 cm. The cubic block may have a height in the
range from about 10 to about 1000 cm, and in one embodiment in the
range from about 20 to about 200 cm. The heavy oil or intermediate
hydrocarbon enters the process microchannels 110 as indicated by
arrow 112. H.sub.2 enters reactant stream channels 150 as indicated
by arrow 152. The H.sub.2 flows from the reactant stream channels
150 into the process microchannels 110 where it contacts the heavy
oil or hydrocarbon intermediate product. The reactants react and
product flows out of the process microchannels 110 as indicated by
arrow 118. Heat exchange fluid enters the heat exchange channels
170 as indicated by arrow 172. Heat exchange fluid flows out of the
heat exchange channels 170 as indicated by arrow 174.
[0183] Referring to FIGS. 2B and 2C, the microchannel reactor 100
has a feed stream header 114 to provide for the flow of the heavy
oil or intermediate hydrocarbon reactant into the process
microchannels 110, a reactant stream channel header 154 to provide
for the flow of H.sub.2 into the reactant stream channels 150, a
product footer 120 to provide for the flow of product out of the
process microchannels 110, and a heat exchange inlet header 176 to
provide for the flow of heat exchange fluid into the heat exchange
channels 170. As shown in FIGS. 2C and 6, the heat exchange fluid
flows out of heat exchange channels through side 111 of the
microchannel reactor 100 into the interior of the microchannel
housing vessel.
[0184] The microchannel reactor may contain a plurality of
repeating units, each of which may include one or more process
microchannels and one or more heat exchange channels. Staged
addition of the H.sub.2 may be used (as indicated in FIGS. 2A, 2B
and 2C), and when used, the repeating units contain one or more
reactant stream channels positioned adjacent to each process
microchannel. The repeating units that may be used include
repeating units 200, 200A, 200B, 200C, 200D, 200E, 200F and 200G
illustrated in FIGS. 8-13 and 25-26, respectively. The microchannel
reactor may comprise from 1 to about 1000 or more of the repeating
units 200, 200A, 200B, 200C, 200D, 200E, 200F or 200G, and in one
embodiment from about 10 to about 500 of such repeating units. The
catalyst used in the repeating units 200, 200A, 200B, 200C, 200D,
200E, 200F or 200G may be in any form, including particulate solids
or the various catalyst structured forms described below.
[0185] Repeating unit 200 is illustrated in FIG. 8. Referring to
FIG. 8, process microchannel 210 is positioned adjacent to heat
exchange channel 230. The heat exchange channel 230 may be a
microchannel. A common wall 232 separates the process microchannel
210 and the heat exchange channel 230. The common wall 232 may be
referred to as a heat transfer wall. The process microchannel 210
includes reaction zone 212. A catalyst (not shown in the drawing)
is positioned in the reaction zone 212. The reactants or reactant
composition (i.e., heavy oil or intermediate hydrocarbon product,
and hydrogen) flow into the reaction zone 212, as indicated by
arrow 214, contact the catalyst in reaction zone 212, and react to
form the desired product. The product comprises an intermediate
hydrocarbon product or upgraded hydrocarbon product. The product
flows out of the process microchannel 210 as indicated by arrow
216. Heat exchange fluid flows in the heat exchange channel 230 in
a direction that is cross-current to the flow of reactants and
product in the process microchannel 210 (that is, into or out of
the page, as illustrated in FIG. 8). The process conducted in the
process microchannel 210 is exothermic and the heat exchange fluid
provides cooling for the reaction. Alternatively, the heat exchange
fluid may flow through the heat exchange channel 230 in a direction
that is counter-current to the flow of reactants and product in the
process microchannel 210 or co-current to the flow of the reactants
and product in the process microchannel 210.
[0186] Repeating unit 200A is illustrated in FIG. 9. Referring to
FIG. 9, process microchannel 210 is positioned adjacent to reactant
stream channel 250. The process microchannel 210 includes reaction
zone 212. The process microchannel 210 and reactant stream channel
250 have a common wall 252. The common wall 252 has a plurality of
openings 254 that are of sufficient dimension to permit the flow of
hydrogen from the reactant stream channel 250 into the process
microchannel 210 as indicated by arrows 256. This hydrogen reactant
may be referred to as a staged addition reactant or the second
reactant. The openings 254 may be referred to as apertures. The
section 258 in the common wall 252 containing the openings 254 may
be referred to as an apertured section. Heat exchange channel 230
is positioned adjacent to the process microchannel 210. The heat
exchange channel 230 and the process microchannel 210 have a common
wall 232. The common wall 232 may be referred to as a heat transfer
wall. In operation, the hydrocarbon reactant (i.e., heavy oil or
intermediate hydrocarbon product) flows into the process
microchannel 210 as indicated by arrow 217. The hydrogen reactant
flows into the reactant stream channel 250 as indicated by arrow
218, and from the reactant stream channel 250 through the openings
254 into the process microchannel 210. In the process microchannel
210, the reactants contact the catalyst in the reaction zone 212
and react to form the desired product which comprises an
intermediate hydrocarbon product or an upgraded hydrocarbon
product. The reaction is exothermic, and the heat exchange channel
230 provides cooling to control the temperature of the reaction.
The heat exchange fluid may flow in the heat exchange channel 230
in a direction that is cross-current relative to the flow of
reactants and product in the process microchannel 210.
Alternatively, the heat exchange fluid may flow in a direction that
is counter-current or co-current to the flow of reactants and
product in the process microchannel 210.
[0187] The repeating unit 200B illustrated in FIG. 10 is similar to
the repeating unit 200A illustrated in FIG. 9, with the exception
that the process microchannel 210 is an E-shaped or M-shaped
microchannel which includes two reaction zones. Also, two adjacent
reactant stream channels are used. With this embodiment, staged
addition of the hydrogen is provided for the reaction process. The
process microchannel 210 has an E-shape or M-shape with entrances
indicated by arrows 217 and 217A and an outlet indicated by arrow
216. The process microchannel 210 includes reaction zones 212 and
212A. Reactant stream channels 250 and 250A are positioned between
the legs of the E-shaped or M-shaped process microchannel 210. The
reactant stream channel 250 and process microchannel 210 have a
common wall 252 which contains a plurality of openings 254. The
reactant stream channel 250A and the process microchannel 210 have
a common wall 252A which contains a plurality of openings 254A. The
hydrocarbon reactant (i.e., heavy oil or intermediate hydrocarbon
product) enters the process microchannel 210 as indicated by arrows
217 and 217A, and flows into the reaction zones 212 and 212A,
respectively. The hydrogen enters the reactant stream channels 250
and 250A as indicated by arrows 218 and 218A, respectively. The
hydrogen flows from the reactant stream channels 250 and 250A to
and through openings 254 and 254A into the reaction zones 212 and
212A, contacts the hydrocarbon reactant and the catalyst, and
reacts to form the desired product. The product flows out of the
E-shaped or M-shaped process microchannel 210 as indicated by arrow
216. Heat exchange fluid flows in the heat exchange channel 230 in
a direction that is cross-current relative to the flow of reactants
and product in the process microchannel 210 and provides cooling
for the exothermic reaction. Alternatively, the heat exchange fluid
may flow in a direction that is co-current or counter-current
relative to the flow of reactants and product in the reaction zones
212 and 212A.
[0188] Repeating unit 200C is illustrated in FIG. 11. Referring to
FIG. 11, repeating unit 200C comprises process microchannel 210,
heat exchange channel 230, reactant stream channel 250, and
apertured section 258. A common wall 252 separates process
microchannel 210 and reactant stream channel 250. The apertured
section 258, which contains openings 254, is positioned in common
wall 252. The apertured section 258 extends partially along the
axial length of process microchannel 210. The process microchannel
210 has a mixing zone 211, and a reaction zone 212. A catalyst 215
is positioned in the reaction zone 212. The mixing zone 211 is
upstream from the reaction zone 212. The hydrocarbon reactant
(i.e., heavy oil or intermediate hydrocarbon product) flows into
process microchannel 210, as indicated by the arrow 217, and then
into the mixing zone 211. The hydrogen flows into reactant stream
channel 250, as indicated by arrow 218, and from the reactant
stream channel 250 through the openings 254 into mixing zone 211,
as indicated by arrows 256. The hydrocarbon reactant and the
hydrogen contact each other in the mixing zone 211 and form a
reactant mixture. The reactant mixture flows from the mixing zone
211 into the reaction zone 212, contacts the catalyst 215, and
reacts to form the desired product which comprises an intermediate
hydrocarbon product or an upgraded hydrocarbon product. The product
flows out of the process microchannel 210, as indicated by arrow
216. Heat exchange fluid flows in heat exchange channel 230 in a
direction that is cross-current to the flow of fluid flowing in
process microchannel 210. Alternatively, the heat exchange fluid
may flow in a direction that is counter-current or co-current to
the flow of fluid in the process microchannel 210.
[0189] In an alternate embodiment of the repeating unit 200C
illustrated in FIG. 11, a supplemental mixing zone may be provided
in the process microchannel 210 between the mixing zone 211 and
reaction zone 212. The residence time for mixing in the
supplemental mixing zone may be defined using the sum of the total
of the flow through the openings 254 and the flow of the first
reactant in process microchannel 210, at standard conditions of
temperature (i.e., 0.degree. C.) and pressure (i.e., atmospheric
pressure), and the volume defined by the process microchannel 210
between the end of the mixing zone 211 and the beginning of the
reaction zone 212. This residence time for mixing in the
supplemental mixing zone may be in the range up to about 500
milliseconds (ms), and in one embodiment from about 0.25 ms to
about 500 ms, and in one embodiment from about 0.25 ms to about 250
ms, and in one embodiment from about 0.25 to about 50 ms, and in
one embodiment from about 0.25 to about 2.5 ms.
[0190] The repeating unit 200D illustrated in FIG. 12 is the same
as the repeating unit 200C illustrated in FIG. 11 with the
exception that the repeating unit 200D does not contain the
separate mixing zone 211. With repeating unit 200D, the hydrogen
flows through the openings 254 into the reaction zone 212 where it
contacts the hydrocarbon reactant (i.e., heavy oil or intermediate
hydrocarbon product) and the catalyst 215, and reacts to form the
desired product which comprises an intermediate hydrocarbon product
or an upgraded hydrocarbon product. The product then flows out of
the process microchannel 210, as indicated by arrow 216.
[0191] The repeating unit 200E illustrated in FIG. 13 is the same
as the repeating unit 200C illustrated in FIG. 11 with the
exception that part of the hydrogen mixes with the hydrocarbon
reactant (i.e., heavy oil or intermediate hydrocarbon product) in
the mixing zone 211, and the remainder of the hydrogen mixes with
the resulting reactant mixture in the reaction zone 212. The amount
of the hydrogen that mixes with the heavy oil or hydrotreated
product in the mixing zone 211 may be from about 1% to about 99% by
volume of the hydrogen used in the overall reaction, and in one
embodiment from about 5% to about 95% by volume, and in one
embodiment from about 10% to about 90% by volume, and in one
embodiment from about 20% to about 80% by volume, and in one
embodiment from about 30% to about 70% by volume, and in one
embodiment from about 40% to about 60% by volume of the hydrogen
used in the overall reaction. The remainder of the hydrogen mixes
with the resulting reactant mixture in the reaction zone 212.
[0192] The repeating unit 200F illustrated in FIG. 25 is the same
as the repeating unit 200 in FIG. 8 with the exception that the
process microchannel 210 illustrated in FIG. 26 includes a reaction
zone 212, a preheating zone 240 and a quenching zone 245. The
preheating zone 240 is upstream of the reaction zone 212. The
quenching zone 245 is downstream of the reaction zone 212. The
preheating zone 240 is heated by heating section 236. The reaction
zone 212 is cooled by cooling section 234. The quenching zone 245
is cooled by cooling section 238. The heating section 236, and the
cooling sections 234 and 238 may each comprise heat exchange
channels with appropriate heat exchange fluids flowing in the heat
exchange channels. The reactants (i.e., heavy oil or intermediate
hydrocarbon reactant, and hydrogen) enter the preheating section
240, as indicated by 214, and flow through the preheating section
240 where they are preheated to a desired temperature for entering
the reaction zone 212. The reactants flow from the preheating
section 240 into the reaction zone 212 where they undergo reaction
to form the desired product. The product flows from the reaction
zone 212 through the quenching zone 245 wherein the product is
quenched. The product flows from the quenching zone 245 out of the
process microchannel 210 as indicated by arrow 218.
[0193] The repeating unit 200G illustrated in FIG. 26 is similar to
the repeating unit 200F with the exception that the process
microchannel 210 is in the form of a U laying on its side. Also,
the preheating zone 240 and the quenching zone 245 are adjacent to
each other and exchange heat with each other. The reaction zone 212
of the process microchannel 210 is cooled by the cooling section
234 of heat exchange channel 230. The reactants (i.e., heavy oil or
intermediate hydrocarbon reactant, and hydrogen) enter the process
microchannel 210 as indicated by arrow 214, flow through preheating
section 240 where they are preheated and then through reaction zone
212 where the reactants undergo reaction to form the desired
product. The product flows from the reaction zone 212 through the
quenching zone 245 where the reaction is quenched. The product
flows out of the process microchannel 210 as indicated by arrow
218. The relatively cool reactants flowing in the preheating zone
240 are heated by the relatively hot product flowing through the
quenching zone 245. As a result, heat transfers from the quenching
zone 245 to the preheating zone 240.
[0194] The repeating units 200F and 200G provide for quenching the
product in the microchannel reactor 100. Alternatively, the product
may be quenched downstream of the microchannel reactor 100. The
product quenching may involve reducing the temperature of the
product by at least about 200.degree. C. within a period of up to
about 500 milliseconds (ms). The temperature may be reduced by at
least about 150.degree. C., and in one embodiment at least about
100.degree. C., within a time period of up to about 500 ms, and in
one embodiment up to about 400 ms, and in one embodiment up to
about 300 ms, and in one embodiment up to about 200 ms, and in one
embodiment up to about 100 ms, and in one embodiment up to about 50
ms, and in one embodiment up to about 35 ms, and in one embodiment
up to about 20 ms, and in one embodiment up to about 15 ms, and in
one embodiment up to about 10 ms, and in one embodiment within a
time period of up to about 5 ms. The temperature may be reduced by
at least about 200.degree. C., and in one embodiment at least about
100.degree. C., and in one embodiment at least about 50.degree. C.,
within a time period of about 5 to about 100 ms, and in one
embodiment about 10 to about 50 ms. The product may be quenched in
the microchannel reactor as illustrated in FIGS. 25 and 26, or it
may be quenched in a quenching device that is separate from the
microchannel reactor. The quenching device may comprise a
microchannel heat exchanger. The quenching device may comprise a
heat exchanger that is adjacent to or interleaved with the product
stream exiting the microchannel reactor. The quenching device may
comprise a mixer capable of rapidly mixing the product with a
secondary cooling fluid. The secondary cooling fluid may be a low
temperature steam.
[0195] The quenching device may comprise a narrow gap or passageway
for the process fluids to flow through. The gap or passageway may
have a dimension equal to or below the quench diameter for the
reaction. In this embodiment, the reaction may terminate as the
reactants flow through the gap or passageway as a result of wall
collisions. The gap or passageway may have a height or width of up
to about 5 mm, and in one embodiment up to about 3 mm, and in one
embodiment up to about 1 mm, and in one embodiment up to about 0.5
mm, and in one embodiment up to about 0.1 mm, and in one embodiment
up to about 0.05 mm. This quenching device may comprise a
microchannel or a plurality of parallel microchannels. This
quenching device may comprise part of the process microchannels
used with the inventive process downstream of the catalyst
contained within the microchannels. The narrow gap or passageway
may be used in conjunction with one or more of the other quenching
devices (e.g., heat exchangers).
[0196] The heat exchange channels and reactant stream channels may
be microchannels or they may have dimensions that would
characterize them as not being microchannels. For example, these
channels may have internal heights or widths up to about 50 mm, and
in one embodiment up to about 25 mm, and in one embodiment up to
about 15 mm. The process microchannels are microchannels. Each of
the channels may have a cross-section having any shape, for
example, a square, rectangle, circle, semi-circle, etc. Each
microchannel may have an internal height of up to about 10 mm, and
in one embodiment up to about 5 mm, and in one embodiment up to
about 2 mm, and in one embodiment up to about 2 mm. The height of
each microchannel may be in the range of about 0.05 to about 10 mm,
and in one embodiment from about 0.05 to about 5 mm, and in one
embodiment from about 0.05 to about 2 mm, and in one embodiment
about 0.05 to about 1.5 mm. The width of each of these
microchannels may be of any dimension, for example, up to about 3
meters, and in one embodiment from about 0.01 to about 3 meters,
and in one embodiment about 0.1 to about 3 meters. The length of
each microchannel may be of any dimension, for example, up to about
10 meters, and in one embodiment from about 0.05 to about 10
meters, and in one embodiment from about 0.05 to about 5 meters,
and in one embodiment from about 0.05 to about 2 meters, and in one
embodiment from about 0.1 to about 2 meters, and in one embodiment
from about 0.1 to about 1.5 meters, and in one embodiment from 0.1
to about 1 meter, and in one embodiment from about 0.1 to about 0.7
meter.
[0197] The process microchannels, heat exchange channels and
reactant stream channels may have rectangular cross sections and be
aligned in side-by-side vertically oriented planes or horizontally
oriented stacked planes. These planes may be tilted at an inclined
angle from the horizontal. These configurations may be referred to
as parallel plate configurations. These channels may be arranged in
modularized compact units for scale-up.
[0198] The microchannel reactor may be made of any material that
provides sufficient strength, dimensional stability and heat
transfer characteristics to permit operation of the inventive
process. These materials may include aluminum; titanium; nickel;
copper; chromium; alloys of any of the foregoing metals; brass;
steel; quartz; silicon; or a combination of two or more thereof.
Use of non-metal materials of construction, (e.g., plastic, glass
or ceramic materials) may be employed.
[0199] The microchannel reactor may be fabricated using known
techniques including wire electrodischarge machining, conventional
machining, laser cutting, photochemical machining, electrochemical
machining, molding, water jet, stamping, etching (for example,
chemical, photochemical or plasma etching) and combinations
thereof.
[0200] The microchannel reactor may be constructed by forming shims
with portions removed that allow flow passage. A stack of shims may
be assembled via diffusion bonding, welding, diffusion brazing, and
similar methods to form an integrated device. The microchannel
reactor may be assembled using a combination of shims or laminae
and partial sheets or strips. In this method, the channels or void
areas may be formed by assembling strips or partial sheets to
reduce the amount of material required.
[0201] The microchannel reactor may be constructed using waveforms
in the form of right angled corrugated inserts. The small width
between the tines of the waveform may provide the characteristic
microchannel dimensions. The waveforms may be made of copper,
stainless steel, and the like. These inserts may be sandwiched
between opposing planar sheets or shims. In this manner the
microchannels may be defined on three sides by the corrugated
insert and on the fourth side by one of the planar sheets. The
process microchannels as well as the reactant stream channels and
heat exchange channels may be formed in this manner. This is shown
in FIGS. 32 and 33. The hydroprocessing catalyst may be coated on
or packed around each waveform either before or after stacking and
bonding the layers. Microchannel reactors made using waveforms are
disclosed in WO 2008/030467, which is incorporated herein by
reference.
[0202] The feed entering the first microchannel reactor for
conducting the hydrotreating process may comprise liquid or
vaporous heavy oil, or a mixture of liquid and vaporous heavy oil,
and gaseous or vaporous hydrogen. The feed entering the second
microchannel reactor conducting the hydrocracking process may
comprise the hydrotreated product from the first microchannel
reactor, and hydrogen. The microchannel reactor may comprise a
manifold providing a flow passageway for the reactants to flow into
the process microchannels. The microchannel reactor may comprise
separate manifolds for flowing the reactants into the process
microchannels, one of the manifolds being for the hydrocarbon
reactant (i.e., heavy oil or intermediate hydrocarbon product), and
the other manifold being for the hydrogen.
[0203] Hydroprocessing may be achieved where there is superior
wetting of the catalyst due to the assistance of capillary forces.
These may be further assisted by thin layers of liquid on the
catalyst for enhanced mass transfer. The architecture for
conducting hydroprocessing may include structures such as honeycomb
monoliths (metal and/or ceramic), which may be filled or coated
with catalyst particles.
[0204] An assembly for microchannel mixing of hydrogen and liquid
may be installed upstream of or inside a conventional trickle bed
reactor in order to achieve improved contacting.
[0205] One or more of the microchannel reactors 100 may be housed
in microchannel reactor housing vessel 300 which is illustrated in
FIGS. 6 and 7. Referring to FIGS. 2A, 2B, 2C, 6 and 7, the vessel
300 contains twelve microchannel reactors 100. These are identified
in FIG. 7 as microchannel reactors 100-1, 100-2, 100-3, 100-4,
100-5, 100-6, 100-7, 100-8, 100-9, 100-10, 100-11 and 100-12.
Although twelve microchannel reactors 100 are disclosed in the
drawings, it will be understood that the vessel 300 may contain any
desired number of microchannel reactors. For example, the vessel
300 may contain from about 1 to about 1000 or more microchannel
reactors, and in one embodiment from 1 to about 750, and in one
embodiment from 1 to about 500, and in one embodiment from 1 to
about 250, and in one embodiment from 1 to about 100, and in one
embodiment from about 1 to about 50, and in one embodiment from 1
to about 20 microchannel reactors, and in one embodiment from 5 to
about 20 microchannel reactors 100, and in one embodiment from
about 10 to about 20 microchannel reactors. The vessel 300 may be a
pressurizable vessel. The vessel 300 includes inlets 310 and 320,
and outlets 330 and 340. The inlet 310 is connected to a header 114
which is provided for flowing hydrocarbon reactants into the
microchannel reactors 100. An inlet (now shown in FIG. 6 or 7) is
provided for flowing H.sub.2 into the microchannel reactors 100.
The inlet 320 is connected to header 176 which is provided for
flowing heat exchange fluid (e.g., steam) into the microchannel
reactors 100. The outlet 330 is connected to footer 120 which
provides for the flow of product out of the microchannel reactors
100. The outlet 340 provides for the flow of the heat exchange
fluid out of the heat exchange channels in the microchannel
reactors 100. The vessel 300 also includes a manway with demister
360, steam outlet 362, blowdown 364, pressure relief valve 366,
level transmitter 368, and temperature control device 370.
[0206] The housing vessel 300 may be constructed using any suitable
material sufficient for operating under the pressures and
temperatures required for operating the microchannel reactors 100.
For example, the shell 350 and heads 352 of the vessel 300 may be
constructed of cast steel. The flanges, couplings and pipes may be
constructed of 316 stainless steel. The vessel 300 may have any
desired diameter, for example, from about 10 to about 1000 cm, and
in one embodiment from about 50 to about 300 cm, and in one
embodiment from about 100 to about 200 cm. The axial length of the
vessel 300 may be of any desired value, for example, from about 0.5
to about 50 meters, and in one embodiment from about 1 to about 20
meters, and in one embodiment from about 5 to about 20 meters, and
in one embodiment from about 5 to about 10 meters.
[0207] In the design and operation of the microchannel reactor it
may be advantageous to provide a tailored heat exchange profile
along the length of the process microchannels in order to optimize
the reaction. This may be accomplished by matching the local
release of heat given off by the hydrotreating or hydrocracking
reaction conducted in the process microchannels with heat removal
or cooling provided by heat exchange fluid in heat exchange
channels in the microchannel reactor. The extent of the
hydrotreating or hydrocracking reaction and the consequent heat
release provided by the reaction may be higher in the front or
upstream sections of the reaction zones in the process
microchannels as compared to the back or downstream sections of the
reaction zones. Consequently, the matching cooling requirements may
be higher in the upstream section of the reaction zones as compared
to the downstream sections of the reaction zones. Tailored heat
exchange may be accomplished by providing more heat exchange or
cooling channels, and consequently the flow of more heat exchange
or cooling fluid, in thermal contact with upstream sections of the
reaction zones in the process microchannels as compared to the
downstream sections of the reaction zones. Alternatively or
additionally, a tailored heat exchange profile may be provided by
varying the flow rate of heat exchange fluid in the heat exchange
channels. In areas where additional heat exchange or cooling is
desired, the flow rate of the heat exchange fluid may be increased
as compared to areas where less heat exchange or cooling is
required. For example, a higher rate of flow of heat exchange fluid
may be advantageous in the heat exchange channels in thermal
contact with the upstream sections of the reaction zones in the
process microchannels as compared to the heat exchange channels in
thermal contact with the downstream sections of the reaction zones.
Heat transfer from the process microchannels to the heat exchange
channels may be designed for optimum performance by selecting
optimum heat exchange channel dimensions and/or the rate of flow of
heat exchange fluid per individual or groups of heat exchange
channels. Additional design alternatives for tailoring heat
exchange may relate to the selection and design of the catalyst
(such as, particle size, catalyst formulation, packing density, use
of a graded catalyst, or other chemical or physical
characteristics) at specific locations within the process
microchannels. These design alternatives may impact both heat
release from the process microchannels as well as heat transfer to
the heat exchange fluid. Temperature differentials between the
process microchannels and the heat exchange channels, which may
provide the driving force for heat transfer, may be constant or may
vary along the length of the process microchannels.
[0208] The process microchannels and/or heat exchange channels may
contain one or more surface features in the form of depressions in
and/or projections from one or more interior walls or interior
structures of the process microchannels and/or heat exchange
channels. Examples are shown in FIGS. 14, 15 and 24. The surface
features may be used to disrupt the flow of fluid flowing in the
channels. These disruptions in flow may enhance mixing and/or heat
transfer. The surface features may be in the form of patterned
surfaces. The microchannel reactors may be made by laminating a
plurality of shims together. One or both major surfaces of the
shims may contain surface features. Alternatively, the microchannel
reactors may be assembled using some sheets or shims and some
strips, or partial sheets to reduce the total amount of metal
required to construct the device. In one embodiment, a shim
containing surface features may be paired (on opposite sides of a
microchannel) with another shim containing surface features.
Pairing may create better mixing or heat transfer enhancement as
compared to channels with surface features on only one major
surface. In one embodiment, the patterning may comprise diagonal
recesses that are disposed over substantially the entire width of a
microchannel surface. The patterned surface feature area of a wall
may occupy part of or the entire length of a microchannel surface.
In one embodiment, surface features may be positioned over at least
about 10%, and in one embodiment at least about 20%, and in one
embodiment at least about 50%, and in one embodiment at least about
80% of the length of a channel surface. Each diagonal recess may
comprise one or more angles relative to the flow direction.
Successive recessed surface features may comprise similar or
alternate angles relative to other recessed surface features.
[0209] In embodiments wherein surface features may be positioned on
or in more than one microchannel wall, the surface features on or
in one wall may have the same (or similar) pattern as found on a
second wall, but rotated about the centerline of the main channel
mean bulk flow direction. In embodiments wherein surface features
may be on or in opposite walls, the surface features on or in one
wall may be approximately mirror images of the features on the
opposite wall. In embodiments wherein surface features are on or in
more than one wall, the surface features on or in one wall may be
the same (or similar) pattern as found on a second wall, but
rotated about an axis which is orthogonal to the main channel mean
bulk flow direction. In other words, the surface features may be
flipped 180 degrees relative to the main channel mean bulk flow
direction and rotated about the centerline of the main channel mean
bulk flow. The surface features on or in opposing or adjacent walls
may or may not be aligned directly with one another, but may be
repeated continuously along the wall for at least part of the
length of the wall. Surface features may be positioned on three or
more interior surfaces of a channel. For the case of channel
geometries with three or fewer sides, such as triangular, oval,
elliptical, circular, and the like, the surface features may cover
from about 20% to about 100% of the perimeter of the
microchannel.
[0210] In one embodiment, a patterned surface may comprise multiple
patterns stacked on top of each other. A pattern or array of holes
may be placed adjacent to a heat transfer wall and a second
pattern, such as a diagonal array of surface features may be
stacked on top and adjacent to an open channel for flow. A sheet
adjacent to an open gap may have patterning through the thickness
of the sheet such that flow may pass through the sheet into an
underlying pattern. Flow may occur as a result of advection or
diffusion. As an example, a first sheet with an array of through
holes may be placed over a heat transfer wall, and a second sheet
with an array of diagonal through slots may be positioned on the
first sheet. This may create more surface area for adhering a
catalyst. In one embodiment, the pattern may be repeated on at
least one other wall of the process microchannel. The patterns may
be offset on opposing walls. The innermost patterned surfaces
(those surfaces bounding a flow channel) may contain a pattern such
as a diagonal array. The diagonal arrays may be oriented both
"with" the direction of flow or one side oriented with the
direction of flow and the opposing side oriented "against" the
direction of flow. By varying surface features on opposing walls,
different flow fields and degrees of vorticity may be created in
the fluid that travels down the center and open gap.
[0211] The surface features may be oriented at angles relative to
the direction of flow through the channels. The surface features
may be aligned at an angle from about 1.degree. to about
89.degree., and in one embodiment from about 30.degree. to about
75.degree., relative to the direction of flow. The angle of
orientation may be an oblique angle. The angled surface features
may be aligned toward the direction of flow or against the
direction of flow. The flow of fluid in contact with the surface
features may force some of the fluid into depressions in the
surface features, while other fluids may flow above the surface
features. Flow within the surface features may conform with the
surface feature and be at an angle to the direction of the bulk
flow direction in the channel. As fluid exits the surface features
it may exert momentum in the x and y direction for an x,y,z
coordinate system wherein the bulk flow direction is in the z
direction. This may result in a churning or rotation in the flow of
the fluids. This pattern may be helpful for mixing.
[0212] Two or more surface feature regions within the process
microchannels may be placed in series such that mixing of the
fluids may be accomplished using a first surface feature region,
followed by at least one second surface feature region where a
different flow pattern may be used.
[0213] The surface features may have two or more layers stacked on
top of each other or intertwined in a three-dimensional pattern.
The pattern in each discrete layer may be the same or different.
Flow may rotate or advect in each layer or only in one layer.
Sub-layers, which may not be adjacent to the bulk flow path of the
channel, may be used to create additional surface area. The flow
may rotate in the first level of surface features and diffuse
molecularly into the second or more sublayers to promote reaction.
Three-dimensional surface features may be made via metal casting,
photochemical machining, laser cutting, etching, ablation, or other
processes where varying patterns may be broken into discrete planes
as if stacked on top of one another. Three-dimensional surface
features may be provided adjacent to the bulk flow path within the
microchannel where the surface features have different depths,
shapes, and/or locations accompanied by sub-features with patterns
of varying depths, shapes and/or locations.
[0214] An example of a three-dimensional surface feature structure
may comprise recessed oblique angles or chevrons at the interface
adjacent the bulk flow path of the microchannel. Beneath the
chevrons there may be a series of three-dimensional structures that
connect to the surface features adjacent to the bulk flow path but
are made from structures of assorted shapes, depths, and/or
locations. It may be further advantageous to provide sublayer
passages that do not directly fall beneath an open surface feature
that is adjacent to the bulk flow path within the microchannel but
rather connect through one or more tortuous two-dimensional or
three-dimensional passages. This approach may be advantageous for
creating tailored residence time distributions in the
microchannels, where it may be desirable to have a wider versus
more narrow residence time distribution.
[0215] The length and width of a surface feature may be defined in
the same way as the length and width of a channel. The depth may be
the distance which the surface feature sinks into or rises above
the microchannel surface. The depth of the surface features may
correspond to the direction of stacking a stacked and bonded
microchannel device with surface features formed on or in the sheet
surfaces. The dimensions for the surface features may refer the
maximum dimension of a surface feature; for example the depth of a
rounded groove may refer to the maximum depth, that is, the depth
at the bottom of the groove.
[0216] The surface features may have depths that are up to about 5
mm, and in one embodiment up to about 2 mm, and in one embodiment
in the range from about 0.01 to about 5 mm, and in one embodiment
in the range from about 0.01 to about 2 mm, and in one embodiment
in the range from about 0.01 mm to about 1 mm. The width of the
surface features may be sufficient to nearly span the microchannel
width (for example, herringbone designs), but in one embodiment
(such as fill features) may span about 60% or less of the width of
the microchannel, and in one embodiment about 50% or less, and in
one embodiment about 40% or less, and in one embodiment from about
0.1% to about 60% of the microchannel width, and in one embodiment
from about 0.1% to about 50% of the microchannel width, and in one
embodiment from about 0.1% to about 40% of the microchannel width.
The width of the surface features may be in the range from about
0.05 mm to about 100 cm, and in one embodiment in the range from
about 0.5 mm to about 5 cm, and in one embodiment in the range from
about 1 to about 2 cm.
[0217] Multiple surface features or regions of surface features may
be included within a channel, including surface features that
recess at different depths into one or more microchannel walls. The
spacing between recesses may be in the range from about 0.01 mm to
about 10 mm, and in one embodiment in the range from about 0.1 to
about 1 mm. The surface features may be present throughout the
entire length of a microchannel or in portions or regions of the
channel. The portion or region having surface features may be
intermittent so as to promote a desired mixing or unit operation
(for example, separation, cooling, etc.) in tailored zones. For
example, a one-centimeter section of a channel may have a tightly
spaced array of surface features, followed by four centimeters of a
flat channel without surface features, followed by a two-centimeter
section of loosely spaced surface features. The term "loosely
spaced surface features" may be used to refer to surface features
with a pitch or feature to feature distance that is more than about
five times the width of the surface feature.
[0218] The surface features may be positioned in one or more
surface feature regions that extend substantially over the entire
axial length of a channel. In one embodiment, a channel may have
surface features extending over about 50% or less of its axial
length, and in one embodiment over about 20% or less of its axial
length. In one embodiment, the surface features may extend over
about 10% to about 100% of the axial length of the channel, and in
one embodiment from about 20% to about 90%, and in one embodiment
from about 30% to about 80%, and in one embodiment from about 40%
to about 60% of the axial length of a channel.
[0219] Each surface feature leg may be at an oblique angle relative
to the bulk flow direction. The feature span length or span may be
defined as being normal to the feature orientation. As an example,
one surface feature may be a diagonal depression at a 45 degree
angle relative to a plane orthogonal to the mean direction of bulk
flow in the main channel with a 0.38 mm opening or span or feature
span length and a feature run length of 5.6 mm. The run length may
be the distance from one end to the other end of the surface
feature in the longest direction, whereas the span or feature span
length may be in the shortest direction (that is not depth). The
surface feature depth may be the distance way from the main
channel. For surface features with a nonuniform width (span), the
span may be the average span averaged over the run length.
[0220] A surface feature may comprise a recess or a protrusion
based on the projected area at the base of the surface feature or
the top of the surface feature. If the area at the top of the
surface feature is the same or exceeds the area at the base of the
surface feature, then the surface feature may be considered to be
recessed. If the area at the base of the surface feature exceeds
the area at the top of the surface feature, then it may be
considered to be protruded. For this description, the surface
features may be described as recessed although it is to be
understood that by changing the aspect ratio of the surface feature
it may be alternatively defined as a protrusion. For a process
microchannel defined by walls that intersect only the tops of the
surface features, especially for a flat channel, all surface
features may be defined as recessed and it is to be understood that
a similar channel could be created by protruding surface features
from the base of a channel with a cross section that includes the
base of the surface features.
[0221] The process microchannels and/or heat exchange channels may
have at least about 20%, and in one embodiment at least about 35%,
and in one embodiment at least about 50%, and in one embodiment at
least about 70%, and in one embodiment at least about 90% of the
interior surface of the channel (measured in cross-section
perpendicular to length; i.e., perpendicular to the direction of
net flow through the channel) that contains surface features. The
surface features may cover a continuous stretch of at least about 1
cm, and in one embodiment at least about 5 cm. In the case of an
enclosed channel, the percentage of surface feature coverage may be
the portion of a cross-section covered with surface features as
compared to an enclosed channel that extends uniformly from either
the base or the top of the surface feature or a constant value
in-between. The latter may be a flat channel. For example, if a
channel has patterned top and bottom surfaces that are each 0.9 cm
across (wide) and unpatterned side walls that are 0.1 cm high, then
90% of the surface of the channel would contain surface
features.
[0222] The process microchannel may be enclosed on all sides, and
in one embodiment the channel may have a generally square or
rectangular cross-section (in the case of rectangular channel,
surface feature patterning may be positioned on both major faces).
For a generally square or rectangular channel, the channel may be
enclosed on only two or three sides and only the two or three
walled sides may be used in the above described calculation of
percentage surface features. In one embodiment, the surface
features may be positioned on cylindrical channels with either
constant or varying cross section in the axial direction.
[0223] Each of the surface feature patterns may be repeated along
one face of the channel, with variable or regular spacing between
the surface features in the channel bulk flow direction. Some
embodiments may have only a single leg to each surface feature,
while other embodiments may have multiple legs (two, three, or
more). For a wide-width channel, multiple surface features or
columns of repeated surface features may be placed adjacent to one
another across the width of the channel. For each of the surface
feature patterns, the feature depth, width, span, and spacing may
be variable or constant as the pattern is repeated along the bulk
flow direction in the main channel. Also, surface feature
geometries having an apex connecting two legs at different angles
may have alternate embodiments in which the surface feature legs
may not be connected at the apex.
[0224] An advantage of the inventive process, at least in one
embodiment, is that the gap distances between the process
microchannels, optional reactant stream channels, and heat exchange
channels may be the same whether the process is intended for
laboratory or pilot plant scale or for full production scale. As a
result, the dispersion of the hydrogen reactant into the reaction
mixture used in the inventive process may be substantially the same
whether the microchannel reactor is built on a laboratory, pilot
plant scale or as a full scale plant unit.
[0225] The catalyst may be segregated into separate reaction zones
in the process microchannels in the direction of flow through the
process microchannels. The same or different catalyst or catalyst
composition may be used in each reaction zone. In each reaction
zone the length of one or more adjacent heat exchange zone(s) may
vary in their dimensions. For example, in one embodiment, the
length of the one or more adjacent heat exchange zones may be less
than about 50% of the length of each reaction zone. Alternatively,
the one or more heat exchange zones may have lengths that are more
than about 50% of the length of each reaction zone up to about 100%
of the length of each reaction zone.
[0226] The catalyst may be in the form of a catalyst bed that is
graded in composition or graded with a thermally conductive inert
material. The thermally conductive inert material may be
interspersed with the active catalyst. Examples of thermally
conductive inert materials that may be used include diamond powder,
silicon carbide, aluminum, alumina, copper, graphite, and the like.
The bed fraction may range from 100% by weight active catalyst to
less than about 10% by weight active catalyst. In an alternate
embodiment the thermally conductive inert material may be deployed
at the center or within the catalyst particles. The active catalyst
may be deposited on the outside, inside or intermittent within a
composite structure that includes the thermally conductive inert.
The resulting catalyst composite structure may have an effective
thermal conductivity when placed in a process microchannel that is
at least about 0.5 W/m/K, and in one embodiment at least about 1
W/m/K, and in one embodiment at least about 2 W/m/K.
[0227] The catalyst may be in the form of a catalyst bed that is
graded only locally within the reactor. For example, a process
microchannel may contain a catalyst bed with a first reaction zone
and a second reaction zone. The top or bottom (or front or back) of
the catalyst bed may be graded in composition whereby a more or
less active catalyst is employed in all or part of the first or
second reaction zone. The composition that is reduced in one
reaction zone may generate less heat per unit volume and thus
reduce the hot spot and potential for the production of undesirable
by-products. The catalyst may be graded with an inert material in
the first and/or second reaction zone, in full or in part. The
first reaction zone may contain a first composition of catalyst or
inert material, while the second reaction zone may contain a second
composition of catalyst or inert material.
[0228] In one embodiment, different particle sizes may be used in
different axial length regions of the process microchannels to
provide for graded catalyst beds. For example, very small particles
may be used in a first reaction zone while larger particles may be
used in a second reaction zone. The average particle diameters may
be less than half the height or gap of the process microchannels.
The very small particles may be less than one-fourth of the process
microchannel height or gap. Larger particles may cause lower
pressure drops per unit length of the process microchannels and may
also reduce the catalyst effectiveness. The effective thermal
conductivity of the catalyst bed may be lower for larger size
particles. Smaller particles may be used in regions where improved
heat transfer is sought throughout the catalyst bed or
alternatively larger particles may be used to reduce the local rate
of heat generation.
[0229] In one embodiment, relatively short contact times, high
selectivity to the desired product and relatively low rates of
deactivation of the catalyst may be achieved by limiting the
diffusion path required for the catalyst. This may be achieved when
the catalyst is in the form of a thin layer on an engineered
support such as a metallic foam or on the wall of the process
microchannel. This allows for increased space velocities. In one
embodiment, the thin layer of catalyst may be produced using
chemical vapor deposition or by a chemical reaction in a solution,
for example, electroless plating. This thin layer may have a
thickness in the range up to about 5 microns, and in one embodiment
from about 0.1 to about 5 microns, and in one embodiment from about
0.5 to about 3 microns, and in one embodiment from about 1 to about
3 microns, and in one embodiment about 2.5 microns. These thin
layers may reduce the time the reactants are within the active
catalyst structure by reducing the diffusional path. This decreases
the time the reactants spend in the active portion of the catalyst.
The result may be increased selectivity to the product and reduced
unwanted by-products. An advantage of this mode of catalyst
deployment is that, unlike conventional catalysts in which the
active portion of the catalyst may be bound up in an inert low
thermal conductivity binder, the active catalyst film may be in
intimate contact with either the engineered structure or the wall
of the process microchannel. This may leverage high heat transfer
rates attainable in the microchannel reactor and allow for close
control of temperature. This may result in the ability to operate
at increased temperature (faster kinetics) without promoting the
formation of undesired by-products, thus producing higher
productivity and yield and prolonging catalyst life.
[0230] The microchannel reactor configuration may be tailored to
match the reaction kinetics. For example, near the entrance or top
of a first reaction zone of the reactor, the microchannel height or
gap may be smaller than in a second reaction zone near the exit or
bottom of the reactor. Alternatively, the zones may be much smaller
than half the reactor length. For example, a first process
microchannel height or gap may be used for the first 25%, 50%, 75%,
or 90% of the length of the process microchannel, while a larger
second height or gap may be used in a second reaction zone
downstream from the first reaction zone. Alternatively, different
configurations may be used. For example, a larger process
microchannel height or gap may be used near the entrance of the
process microchannels and a smaller process microchannel height or
gap may be used near the reactor exit. In one embodiment, other
gradations in the process microchannel height or gap may be used.
For example, a first height or gap may be used near the entrance of
the microchannel to provide a first reaction zone, a second height
or gap downstream from the first reaction zone may be used to
provide a second reaction zone, and a third height or gap may be
used to provide a third reaction zone near the exit of the
microchannel. The first and third heights or gaps may be the same
or different. The first and third heights or gaps may be larger or
smaller than the second height or gap. The third height or gap may
be smaller or larger than the second height or gap. The second
height or gap may be larger or smaller than the third height or
gap.
[0231] The openings or apertures 254 (FIGS. 9-13) may be of
sufficient size to permit the flow of the hydrogen reactant through
the apertured sections. The openings 254 may be referred to as
pores. The apertured section 258 may have thicknesses in the range
from about 0.01 to about 50 mm, and in one embodiment about 0.05 to
about 10 mm, and in one embodiment about 0.1 to about 2 mm. The
openings 254 may have average diameters in the range up to about
1000 microns, and in one embodiment up to about 250 microns, and in
one embodiment up to about 50 microns, and in one embodiment in the
range from about 0.001 to about 50 microns, and in one embodiment
from about 0.05 to about 50 microns, and in one embodiment from
about 0.1 to about 50 microns. In one embodiment, the openings 254
may have average diameters in the range from about 0.5 to about 10
nanometers (nm), and in one embodiment about 1 to about 10 nm, and
in one embodiment about 5 to about 10 nm. The number of openings
254 in the apertured section 258 may be in the range from about 1
to about 5.times.10.sup.8 openings per square centimeter, and in
one embodiment about 1 to about 1.times.10.sup.6 openings per
square centimeter. The openings 254 may or may not be isolated from
each other. A portion or all of the openings 254 may be in fluid
communication with other openings 254 within the apertured section
258; that is, a fluid may flow from one opening to another opening.
The ratio of the thickness of the apertured section 258 to the
length of the apertured section along the flow path of the fluids
flowing through the process microchannels 210 may be in the range
from about 0.001 to about 1, and in one embodiment about 0.01 to
about 1, and in one embodiment about 0.03 to about 1, and in one
embodiment about 0.05 to about 1, and in one embodiment about 0.08
to about 1, and in one embodiment about 0.1 to about 1.
[0232] The apertured section 258 may be constructed of any material
that provides sufficient strength and dimensional stability to
permit the operation of the inventive process. These materials
include: steel (e.g., stainless steel, carbon steel, and the like);
monel; inconel; brass; aluminum; titanium; nickel; copper;
chromium; alloys of any of the foregoing metals; polymers (e.g.,
thermoset resins); ceramics; glass; composites comprising one or
more polymers (e.g., thermoset resins) and fiberglass; quartz;
silicon; microporous carbon, including carbon nanotubes or carbon
molecular sieves; zeolites; or a combination of two or more
thereof. The openings 254 may be formed using known techniques such
as laser drilling, microelectro machining system (MEMS),
lithography electrodeposition and molding (LIGA), electrical
sparkling, or electrochemical or photochemical etching. The
openings 254 may be formed using techniques used for making
structured plastics, such as extrusion, or membranes, such as
aligned carbon nanotube (CNT) membranes. The openings 254 may be
formed using techniques such as sintering or compressing metallic
powder or particles to form tortuous interconnected capillary
channels and the techniques of membrane fabrication. The openings
254 may be reduced in size from the size provided by any of these
methods by the application of coatings over the apertures internal
side walls to partially fill the apertures. The selective coatings
may also form a thin layer exterior to the porous body that
provides the smallest pore size adjacent to the continuous flow
path. The smallest average pore opening may be in the range from
about one nanometer to about several hundred microns depending upon
the desired droplet size for the emulsion. The apertures may be
reduced in size by heat treating as well as by methods that form an
oxide scale or coating on the internal side walls of the apertures.
These techniques may be used to partially occlude the apertures to
reduce the size of the openings for flow.
[0233] The apertured section 258 may be made from a metallic or
nonmetallic porous material having interconnected channels or pores
of an average pore size in the range from about 0.01 to about 200
microns. These pores may function as the openings 254. The porous
material may be made from powder or particulates so that the
average inter-pore distance is similar to the average pore size.
When very small pore sizes are used, the inter-pore distance may
also be very small. The porous material may be tailored by
oxidization at a high temperature in the range from about
300.degree. C. to about 1000.degree. C. for a duration of about 1
hour to about 20 days, or by coating a thin layer of another
material such as alumina by sol coating or nickel using chemical
vapor deposition over the surface and the inside of pores to block
the smaller pores, decrease pore size of larger pores, and in turn
increase the inter-pore distance.
[0234] The cooling of the process microchannels during the
inventive process, in one embodiment, is advantageous for reducing
the formation of undesired coke. As a result of this cooling, in
one embodiment, the temperature of the feed streams entering the
entrance to the process microchannels may be within about
200.degree. C., and in one embodiment within about 100.degree. C.,
and in one embodiment within about 50.degree. C., and in one
embodiment within about 20.degree. C., of the temperature of the
product exiting the process microchannels.
[0235] The hydrotreating catalyst may be any hydrotreating
catalyst. The hydrotreating catalyst may comprise Ni, Mo, Co, W, or
combinations of two or more thereof. These may be supported on
alumina. The catalyst may comprise Mo-W/Al.sub.2O.sub.3.
[0236] The hydrocracking catalyst may be any hydrocracking
catalyst. These catalysts may include zeolite catalysts including
beta zeolite, omega zeolite, L-zeolite, ZSM-5 zeolites and Y-type
zeolites. The hydrocracking catalyst may comprise one or more
pillared clays, MCM-41, MCM-48, HMS, or a combination of two or
more thereof. The hydrocracking catalyst may comprise Pt, Pd, Ni,
Co, Mo, W, or a combination of two or more thereof. The
hydrocracking catalyst may include a refractory inorganic oxide
such as alumina, magnesia, silica, titania, zirconia and
silica-alumina. The hydrocracking catalyst may comprise a
hydrogenation component. Examples of suitable hydrogenation
components include metals of Group IVB and Group VIII of the
Periodic Table and compounds of such metals. Molybdenum, tungsten,
chromium, iron, cobalt, nickel, platinum, palladium, iridium,
osmium, rhodium and ruthenium may be used as the hydrogenation
component. These catalysts are described in U.S. Pat. No. 6,312,586
B1, which is incorporated herein by reference.
[0237] The hydrotreating and hydrocracking catalysts that are used
in the microchannel reactor may have any size and geometric
configuration that fits within the process microchannels. The
catalyst may be in the form of particulate solids (e.g., pellets,
powder, fibers, and the like) having a median particle diameter of
about 1 to about 1000 .mu.m (microns), and in one embodiment from
about 10 to about 500 .mu.m, and in one embodiment from about 25 to
about 300 .mu.m, and in one embodiment from about 80 to about 300
.mu.m.
[0238] The catalyst may be in the form of a bed of particulate
solids. The median particle diameter may be in the range from about
1 to about 1000 .mu.m, and in one embodiment from about 10 to about
500 .mu.m. This is shown in FIG. 16 wherein a bed of particulate
solids 400 is packed in process microchannel 402. Reactants flow
into the process microchannel as indicated by arrow 404 and product
flows out of the process microchannel as indicated by arrow 406.
Microfibers (e.g. within a catalyst bed or catalyst bale and/or
coated with catalyst) to promote good liquid distribution across a
catalyst may be used.
[0239] Foams for retaining catalyst particles and/or coated foams,
including graphite foams, silicon carbide, metal (e.g., Fecralloy),
ceramic, and/or internal coatings of grapheme for high thermal
conductivity coating may be used.
[0240] The catalyst may be supported on a porous support structure
such as a foam, felt, wad or a combination thereof. The term "foam"
is used herein to refer to a structure with continuous walls that
include pores positioned along the length or the structure or
throughout the structure. The pores may be on the surface of the
continuous walls and used for adhering catalyst material (e.g.,
catalyst metal particles) to the walls of the foam structure. The
term "felt" is used herein to refer to a structure of fibers with
interstitial spaces there between. The term "wad" is used herein to
refer to a structure of tangled strands, like steel wool. The
catalyst may be supported on a monolith or honeycomb structure.
[0241] The catalyst may be supported on a flow-by support structure
such as a felt with an adjacent gap, a foam with an adjacent gap, a
fin structure with gaps, a washcoat on any inserted substrate, or a
gauze that is parallel to the flow direction with a corresponding
gap for flow. An example of a flow-by structure is illustrated in
FIG. 17. In FIG. 17, the catalyst 410 is contained within process
microchannel 412. An open passage way 414 permits the flow of fluid
through the process microchannel 412 in contact with the catalyst
410 as indicated by arrows 416 and 418.
[0242] The catalyst may be supported on a flow-through support
structure such as a foam, wad, pellet, powder, or gauze. An example
of a flow-through structure is illustrated in FIG. 18. In FIG. 18,
the flow-through catalyst 420 is contained within process
microchannel 422 and the fluid flows through the catalyst 420 as
indicated by arrows 424 and 426.
[0243] The support structure for a flow-through catalyst may be
formed from a material comprising silica gel, foamed copper,
sintered stainless steel fiber, steel wool, alumina, poly(methyl
methacrylate), polysulfonate, poly(tetrafluoroethylene), iron,
nickel sponge, nylon, polyvinylidene difluoride, polypropylene,
polyethylene, polyethylene ethylketone, polyvinyl alcohol,
polyvinyl acetate, polyacrylate, polymethylmethacrylate,
polystyrene, polyphenylene sulfide, polysulfone, polybutylene, or a
combination of two or more thereof. In one embodiment, the support
structure may be made of a heat conducting material, such as a
metal, to enhance the transfer of heat away from the catalyst.
[0244] The catalyst may be directly washcoated on the interior
walls of the process microchannels, grown on the walls from
solution, or coated in situ on a fin structure or other support
structure. The catalyst may be in the form of one or more pieces of
porous contiguous material. In one embodiment, the catalyst may be
comprised of a contiguous material and has a contiguous porosity
such that molecules can diffuse through the catalyst. In this
embodiment, the fluids flow through the catalyst rather than around
it. In one embodiment, the cross-sectional area of the catalyst
occupies about 1 to about 99%, and in one embodiment about 10 to
about 95% of the cross-sectional area of the process microchannels.
The catalyst may have a surface area, as measured by BET, of
greater than about 0.5 m.sup.2/g, and in one embodiment greater
than about 2 m.sup.2/g.
[0245] The catalyst may comprise a porous support, an interfacial
layer on the porous support, and a catalyst material deposited on
or mixed with the interfacial layer. In one embodiment, a buffer
layer may be positioned between the porous support and the
interfacial layer. The buffer layer may be grown or deposited on
the porous structure. For example, the porous support may be made
of an alumina forming material such as Fecralloy (an alloy of Fe,
Cr. Al and Y), and the porous structure may be heat treated in air
to form an alumina layer on the surface of the porous support. This
alumina layer would be a buffer layer. The interfacial layer may be
coated or solution deposited on the surface of the porous support
or it may be deposited by chemical vapor deposition or physical
vapor deposition. Any of the foregoing layers may be continuous or
discontinuous as in the form of spots or dots, or in the form of a
layer with gaps or holes.
[0246] The porous support may have a porosity of at least about 5%
as measured by mercury porosimetry. The porous support may have an
opening or gap with a height or width normal to the bulk flow
direction of reactants flowing through the catalyst in the range
from about 1 to about 2000 .mu.m, and in one embodiment from about
1 to about 1500 .mu.m. The reactants flowing through the opening or
gap may contact catalyst on the walls of the porous support. The
porous support may be a ceramic or a metal support. Other porous
supports that may be used include carbides, nitrides, and composite
materials. The porous support may have a porosity of about 30% to
about 99%, and in one embodiment about 60% to about 98%. The porous
support may be in the form of a foam, felt, wad, or a combination
thereof. The foam may have a porous construction on the surface of
its walls with about 20 pores per inch (ppi) to about 3000 ppi, and
in one embodiment about 20 to about 1000 ppi, and in one embodiment
about 40 to about 120 ppi. The term "ppi" refers to the largest
number of pores per inch (in isotropic materials the direction of
the measurement is irrelevant; however, in anisotropic materials,
the measurement is done in the direction that maximizes pore
number).
[0247] The buffer layer, when present, may have a different
composition and/or density than both the porous support and the
interfacial layers, and in one embodiment has a coefficient of
thermal expansion that is intermediate the thermal expansion
coefficients of the porous support and the interfacial layer. The
buffer layer may be a metal oxide or metal carbide. The buffer
layer may be comprised of Al.sub.2O.sub.3, TiO.sub.2, SiO.sub.2,
ZrO.sub.2, or combination thereof. The Al.sub.2O.sub.3 may be
.alpha.-Al.sub.2O.sub.3, .gamma.-Al.sub.2O.sub.3 or a combination
thereof. .alpha.-Al.sub.2O.sub.3 provides the advantage of
excellent resistance to oxygen diffusion. When the porous support
is made of an alumina forming material such as Fecralloy (an alloy
of Fe, Cr, Al and Y), the buffer layer may be Al.sub.2O.sub.3 on
the surface of the porous support formed by heating the porous
support in air.
[0248] The buffer layer may comprise two or more compositionally
different sublayers. For example, when the porous support is metal,
for example a stainless steel foam, a buffer layer formed of two
compositionally different sub-layers may be used. The first
sublayer (in contact with the porous support) may be TiO.sub.2. The
second sublayer may be .alpha.-Al.sub.2O.sub.3 which is placed upon
the TiO.sub.2. In one embodiment, the .alpha.-Al.sub.2O.sub.3
sublayer is a dense layer that provides protection of the
underlying metal surface. A less dense, high surface area
interfacial layer such as alumina may then be deposited as support
for a catalytically active layer.
[0249] The porous support may have a thermal coefficient of
expansion different from that of the interfacial layer. In such a
case a buffer layer may be needed to transition between the two
coefficients of thermal expansion. The thermal expansion
coefficient of the buffer layer can be tailored by controlling its
composition to obtain an expansion coefficient that is compatible
with the expansion coefficients of the porous support and
interfacial layers. The buffer layer should be free of openings and
pin holes to provide superior protection of the underlying support.
The buffer layer may be nonporous. The buffer layer may have a
thickness that is less than one half of the average pore size of
the porous support. The buffer layer may have a thickness of about
0.05 to about 10 .mu.m, and in one embodiment about 0.05 to about 5
.mu.m.
[0250] The buffer layer may be used to increase the adhesion of the
interfacial layer to the surface of the porous support. However, in
one embodiment of the invention, adequate adhesion and chemical
stability may be obtained without a buffer layer and, consequently,
in this embodiment the buffer layer may be omitted.
[0251] The interfacial layer may comprise nitrides, carbides,
sulfides, halides, metal oxides, carbon, or a combination thereof.
The interfacial layer provides high surface area and/or provides a
desirable catalyst-support interaction for supported catalysts.
[0252] The interfacial layer may be comprised of any material that
is conventionally used as a catalyst support. The interfacial layer
may be comprised of a metal oxide. Examples of metal oxides that
may be used include Al.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2,
TiO.sub.2, tungsten oxide, magnesium oxide, vanadium oxide,
chromium oxide, manganese oxide, iron oxide, nickel oxide, cobalt
oxide, copper oxide, zinc oxide, molybdenum oxide, tin oxide,
calcium oxide, aluminum oxide, lanthanum series oxide(s),
zeolite(s) and combinations thereof. The interfacial layer may
serve as a catalytically active layer without any further
catalytically active material deposited thereon. Usually, however,
the interfacial layer is used in combination with a catalytically
active layer. The interfacial layer may also be formed of two or
more compositionally different sublayers. The interfacial layer may
have a thickness that is less than one half of the average pore
size of the porous support. The interfacial layer thickness may
range from about 0.5 to about 100 .mu.m, and in one embodiment from
about 1 to about 50 .mu.m. The interfacial layer may be either
crystalline or amorphous. The interfacial layer may have a BET
surface area of at least about 1 m.sup.2/g.
[0253] The catalyst may be deposited on the interfacial layer.
Alternatively, the catalyst material may be simultaneously
deposited with the interfacial layer. The catalyst layer may be
intimately dispersed on the interfacial layer. That the catalyst
layer is "dispersed on" or "deposited on" the interfacial layer
includes the conventional understanding that microscopic catalyst
particles are dispersed: on the support layer (i.e., interfacial
layer) surface, in crevices in the support layer, and in open pores
in the support layer.
[0254] The catalyst may be in the form of a bed of particulate
solids positioned in a reaction zone wherein one or more interior
walls of the reaction zone includes additional catalyst washcoated
and/or grown thereon. The catalyst in the bed of particulate solids
may be the same as the catalyst washcoated and/or grown on the
interior walls of the reaction zone, or it may be different.
[0255] The catalyst may be supported on an assembly of one or more
fins or other structures positioned within the process
microchannels. Examples are illustrated in FIGS. 19-21. Referring
to FIG. 19, fin assembly 430 includes fins 432 which are mounted on
fin support 434 which overlies base wall 436 of process
microchannel 438. The fins 432 project from the fin support 434
into the interior of the process microchannel 438. The fins 432
extend to and may contact the interior surface of upper wall 440 of
process microchannel 438. Fin channels 442 between the fins 432
provide passage ways for fluid to flow through the process
microchannel 438 parallel to its length. Each of the fins 432 has
an exterior surface on each of its sides, this exterior surface
provides a support base for the catalyst. With the inventive
process, the reactant composition flows through the fin channels
442, contacts the catalyst supported on the exterior surface of the
fins 432, and reacts to form the product. The fin assembly 430a
illustrated in FIG. 20 is similar to the fin assembly 430
illustrated in FIG. 19 except that the fins 432a do not extend all
the way to the interior surface of the upper wall 440 of the
microchannel 438. The fin assembly 430b illustrated in FIG. 21 is
similar to the fin assembly 430 illustrated in FIG. 20 except that
the fins 432b in the fin assembly 430b have cross sectional shapes
in the form of trapezoids. Each of the fins may have a height
ranging from about 0.02 mm up to the height of the process
microchannel 438, and in one embodiment from about 0.02 to about 10
mm, and in one embodiment from about 0.02 to about 5 mm, and in one
embodiment from about 0.02 to about 2 mm. The width of each fin may
range from about 0.02 to about 5 mm, and in one embodiment from
about 0.02 to about 2 mm and in one embodiment about 0.02 to about
1 mm. The length of each fin may be of any length up to the length
of the process microchannel 438, and in one embodiment up to about
10 m, and in one embodiment about 0.5 to about 10 m, and in one
embodiment about 0.5 to about 6 m, and in one embodiment about 0.5
to about 3 m. The gap between each of the fins may be of any value
and may range from about 0.02 to about 5 mm, and in one embodiment
from about 0.02 to about 2 mm, and in one embodiment from about
0.02 to about 1 mm. The number of fins in the process microchannel
438 may range from about 1 to about 50 fins per centimeter of width
of the process microchannel 438, and in one embodiment from about 1
to about 30 fins per centimeter, and in one embodiment from about 1
to about 10 fins per centimeter, and in one embodiment from about 1
to about 5 fins per centimeter, and in one embodiment from about 1
to about 3 fins per centimeter. Each of the fins may have a
cross-section in the form of a rectangle or square as illustrated
in FIG. 19 or 20, or a trapezoid as illustrated in FIG. 21. When
viewed along its length, each fin may be straight, tapered or have
a serpentine configuration. The fin assembly may be made of any
material that provides sufficient strength, dimensional stability
and heat transfer characteristics to permit operation for which the
process microchannel is intended. These materials include: steel
(e.g., stainless steel, carbon steel, and the like); aluminum;
titanium; nickel; platinum; rhodium; copper; chromium; alloys of
any of the foregoing metals; monel; inconel; brass; polymers (e.g.,
thermoset resins); ceramics; glass; composites comprising one or
more polymers (e.g., thermoset resins) and fiberglass; quartz;
silicon; or a combination of two or more thereof. The fin assembly
may be made of an Al.sub.2O.sub.3 forming material such as an alloy
comprising Fe, Cr, Al and Y, or a Cr.sub.2O.sub.3 forming material
such as an alloy of Ni, Cr and Fe.
[0256] The catalyst may be supported by a microgrooved support
strip. Examples of these support strips are illustrated in FIGS. 22
and 23. Referring to FIG. 23, process microchannel 450 includes
support strip 452 mounted on interior wall 454 of the process
microchannel 450. Bulk flow region 456 is defined by the space
within the process microchannel 450 between the support strip 452
and the top channel wall 457. Process fluid flows through the
process microchannel 450 as indicated by arrows 458 and 460. In
flowing through the process microchannel 450, the process fluid
flows through the bulk flow region 456 in contact with the catalyst
support strip 452. The catalyst may be in the form of microsized
particulates positioned in the microgrooves 462. The support strip
452 is a flow-by support strip. However, some of the process fluid
may flow in the microgrooves 462 in contact with the catalyst. The
flow of the process fluid through the microgrooves 462 may be in
the general direction from the front edge 463 and the first side
edge 464 toward the second side edge 466 and the back edge 468. The
process microchannel illustrated in FIG. 23 is similar to the
process microchannel illustrated in FIG. 22 with the exception that
the process microchannel 450 illustrated in FIG. 23 contains
opposite interior walls 454 and 457 and a catalyst supporting
support strip 452 mounted on each of the opposite interior walls.
Additional details concerning the construction and use of the
microgrooved support strip 452 can be found in US Patent
Publication No. U.S. 2007-0225532A1, which is incorporated herein
by reference.
[0257] Surface features can be used in combination with a supported
catalyst to enhance contact between the reactants and the catalyst.
This is shown in FIG. 24. Referring to FIG. 24, process
microchannel 450 which has support strip 452 mounted on interior
wall 454 and surface features 470 formed in the opposite interior
wall 457. Process fluid flows through the process microchannel 450
as indicated by arrows 472. The flow of the process fluid is
modified as the process fluid flows through surface features 470.
The surface features 470 illustrated in FIG. 24 are in the form of
hemispherical depressions in the microchannel wall 457. The
modification of the flow of the process fluids by the surface
features 470 enhances contact between the process fluid and the
catalyst supported by the support strip 452.
[0258] A sintered ceramic or metal material (e.g., one micron,
Inconel sintered metal) may be used to contact the catalyst or to
support the catalyst in the microchannel reactor. The sintered
material may be contained or attached to interior walls of solid
metal "sleeves" to form a unit, which may serve as individual
pressure vessels and may be added for capacity/replacement. The
sintered metal and/or metal sleeves may comprise a high thermal
conductivity metal such as copper, aluminum or titanium. Catalyst
particles may be loaded into the subassemblies. The catalyst may be
coated using solution coating, slurry coating, sol-gel coating,
physical vapor deposition, chemical vapor deposition or electroless
plating onto the sintered metal.
[0259] The catalyst may be regenerated. This may be done by flowing
a regenerating fluid through the process microchannels in contact
with the catalyst. The regenerating fluid may comprise hydrogen or
a diluted hydrogen stream, hydrogen sulphide (or other sulphur
containing compound) or a diluted hydrogen sulphide (or other
sulphur containing compound) stream, oxygen or an oxygen containing
stream, or a stream containing a halogen containing gas or a
mixture of oxygen and a halogen containing gas. Halogen compounds
may include metal halides and organic halides. The diluent may
comprise nitrogen, argon, helium, methane, ethylene, carbon
dioxide, steam, or a mixture of two or more thereof. The
regenerating fluid may flow from the header through the process
microchannels and to the footer, or in the opposite direction from
the footer through the process microchannels to the header. The
temperature of the regenerating fluid may be from about 20 to about
600.degree. C., and in one embodiment about 150 to about
400.degree. C. The pressure within the process microchannels during
this regeneration step may range from about 0.1 to about 4 MPa, and
in one embodiment about 0.1 to about 2 MPa, and in one embodiment
about 0.1 to about 0.5 MPa. The residence time for the regenerating
fluid in the process microchannels may range from about 0.01 second
to about 3 hours, and in one embodiment about 0.1 second to about
100 seconds.
[0260] The catalyst may be regenerated in-situ in the process
microchannels by oxidizing a carbonaceous material on the surface
of the catalyst or by removing carbonaceous materials via
hydrogenation. The catalysts may be regenerated via sulphiding. The
regeneration process may also occur ex situ, whereby the feed is
bypassed from the reactor, the temperature is dropped to ambient,
and a liquid or gaseous fluid is used to remove carbonaceous
materials. In one embodiment, the regeneration process utilizes a
dissolution process to remove the carbonaceous material. The
pressure drop through the reactor may be lower after regeneration
than before by about 10% or more
[0261] The plant facility used for conducting the inventive process
may comprise a plurality of process microchannels, microchannel
reactors, or reaction vessels containing one or more microchannel
reactors. The catalyst in one or more of the process microchannels,
microchannel reactors or reaction vessels may be regenerated, while
the inventive process may be carried out simultaneously in other
process microchannels, microchannel reactors or reaction vessels in
the plant facility.
[0262] The inventive process may be conducted using a regenerated
catalyst at relatively high liquid hourly space velocities (LHSV),
for example, at about 5 hr.sup.-1 or above, or about 10 hr.sup.-1
or above. The process may be conducted under stable operating
conditions using the regenerated catalyst for extended periods of
time, for example, periods in excess of about 1000 hours.
[0263] The process microchannels may be characterized by having a
bulk flow path. The term "bulk flow path" refers to an open path
(contiguous bulk flow region) within the process microchannels. A
contiguous bulk flow region allows rapid fluid flow through the
microchannels without large pressure drops. In one embodiment, the
flow of fluid in the bulk flow region is laminar. Bulk flow regions
within each process microchannel may have a cross-sectional area of
about 0.05 to about 10,000 mm.sup.2, and in one embodiment about
0.05 to about 5000 mm.sup.2, and in one embodiment about 0.1 to
about 2500 mm.sup.2. The bulk flow regions may comprise from about
5% to about 95%, and in one embodiment about 30% to about 80% of
the cross-section of the process microchannels.
[0264] The heat exchange fluid may be any fluid. These may include
air, steam, liquid water, steam, gaseous nitrogen, other gases
including inert gases, carbon monoxide, molten salt, oils such as
mineral oil, a gaseous hydrocarbon, a liquid hydrocarbon, heat
exchange fluids such as Dowtherm A and Therminol which are
available from Dow-Union Carbide, or a mixture of two or more
thereof. "Dowtherm" and "Therminol" are trademarks.
[0265] The heat exchange fluid may comprise a stream of one or more
of the reactants and/or the product. This can provide process
cooling for the process microchannels and/or pre-heat for the
reactants and thereby increase the overall thermal efficiency of
the process.
[0266] The heat exchange channels may comprise process channels
wherein an endothermic process is conducted. These heat exchange
process channels may be microchannels. Examples of endothermic
processes that may be conducted in the heat exchange channels
include steam reforming and dehydrogenation reactions. Steam
reforming of an alcohol that occurs at a temperature in the range
from about 200.degree. C. to about 300.degree. C. is an example of
an endothermic process suited for an exothermic reaction such as an
ethylene oxide synthesis reaction in the same temperature range.
The incorporation of a simultaneous endothermic reaction to provide
an improved heat sink may enable a typical heat flux of roughly an
order of magnitude above the convective cooling heat flux.
[0267] The heat exchange fluid may undergo a partial or full phase
change as it flows through the heat exchange channels. This phase
change may provide additional heat removal from the process
microchannels beyond that provided by convective cooling. For a
liquid heat exchange fluid being vaporized, the additional heat
being transferred from the process microchannels would result from
the latent heat of vaporization required by the heat exchange
fluid. An example of such a phase change would be a heat exchange
fluid such as oil or water that undergoes partial boiling. In one
embodiment, up to about 50% by weight of the heat exchange fluid
may be vaporized.
[0268] The gaseous fraction of reactants and products may flow in
the reaction zone in contact with the catalyst to produce a
Reynolds number up to about 100000, and in one embodiment up to
about 10000, and in one embodiment up to about 100, and in one
embodiment in the range from about 10 to about 100, and in another
in the range from about 0.01 to about 10, and in one embodiment in
the range from about 0.1 to about 5.
[0269] The heat flux for heat exchange in the microchannel reactor
may range from about 0.01 to about 500 watts per square centimeter
of surface area of the heat transfer walls (W/cm.sup.2) in the
microchannel reactor, and in one embodiment from about 0.1 to about
350 W/cm.sup.2, and in one embodiment from about 1 to about 250
W/cm.sup.2, and in one embodiment from about 1 to about 100
W/cm.sup.2, and in one embodiment from about 1 to about 50
W/cm.sup.2, and in one embodiment from about 1 to about 25
W/cm.sup.2, and in one embodiment from about 1 to about 10
W/cm.sup.2.
[0270] The cooling of the process microchannels during the
inventive process, in one embodiment, is advantageous for
controlling selectivity towards the main or desired product due to
the fact that such added cooling reduces or eliminates the
formation of undesired by-products from undesired parallel
reactions with higher activation energies. As a result of this
cooling, in one embodiment, the temperature of the reactants at the
entrance to the process microchannels may be within about
20.degree. C., and in one embodiment within about 10.degree. C.,
and in one embodiment within about 5.degree. C., and in one
embodiment within about 3.degree. C., and in one embodiment within
about 2.degree. C., and in one embodiment within about 1.degree.
C., of the temperature of the product (or mixture of product and
unreacted reactants) at the outlet of the process microchannels. In
one embodiment, the process microchannels may be operated with an
isothermal or substantially isothermal temperature profile.
[0271] The contact time of the reactants with the catalyst in the
process microchannels may range from about 1 to about 2000
milliseconds (ms), and in one embodiment from about 10 to about
1000 ms, and in one embodiment from about 100 to about 500 ms.
[0272] The liquid hourly space velocity (LHSV) for the flow of
liquid reactant in the process microchannels may be at least about
0.1 liters of liquid reactant per hour per liter of volume in the
process microchannel (hr.sup.-1), and in one embodiment at least
about 1 hr.sup.-1, and in one embodiment at least about 5
hr.sup.-1, and in one embodiment at least about 10 hr.sup.-1, and
in one embodiment at least about 20 hr.sup.-1, and in one
embodiment at least about 30 hr.sup.-1, and in one embodiment at
least about 35 hr.sup.-1, and in one embodiment at least about 40
hr.sup.-1, and in one embodiment from about 0.1 to about 40
hr.sup.-1, and in one embodiment from about 1 to about 40
hr.sup.-1. The LHSV may be in the range from about 0.1 to about 200
hr.sup.-1, and in one embodiment from about 1 to about 100
hr.sup.-1, and in one embodiment from about 2 to about 100
hr.sup.-1.
[0273] The gas hourly space velocity (GHSV) for the flow of gases
(e.g., vapor, H.sub.2) in the process microchannels may be in the
range from about 500 to about 500,000 hr.sup.-1.
[0274] In the hydrotreating and hydrocracking processes, the
conversion of hydrocarbon fractions with boiling points above about
350.degree. C. to hydrocarbons with boiling points below about
350.degree. C. may be at least about 50% by weight, and in one
embodiment at least about 55% by weight, and in one embodiment at
least about 60% by weight, and in one embodiment at least about 65%
by weight, and in one embodiment at least about 70% by weight, and
in one embodiment at least about 75% by weight, and in one
embodiment at least about 80% by weight, and in one embodiment at
least about 85% by weight, and in one embodiment at least about 90%
by weight.
[0275] The pressure drop for the process fluids as they flow in the
process microchannels may range up to about 50 bars per foot of
length of the process microchannel (bars/ft) (0.16 MPa/cm), and in
one embodiment up to about 10 bars/ft (0.032 MPa/cm), and in one
embodiment up to about 1.5 bars/ft (0.005 MPa/cm), and in one
embodiment up to 1 bar/ft (0.0033 MPa/cm), and in one embodiment up
to about 0.5 bar/ft (0.0016 MPa/cm).
[0276] The flow of the process fluids in the process microchannels
may be laminar or in transition, and in one embodiment it is
laminar. The Reynolds Number for the flow of process fluids in the
process microchannels may be up to about 10,000, and in one
embodiment up to about 4000, and in one embodiment up to about
2300, and in one embodiment in the range of about 1 to about 2000,
and in one embodiment in the range from about 100 to about
1500.
[0277] The superficial velocity for process gas flowing in the
process microchannels may be at least about 0.01 meters per second
(m/s), and in one embodiment in the range from about 0.01 to about
5 m/s, and in one embodiment in the range from about 0.01 to about
2 m/s, and in one embodiment in the range from about 0.01 to about
1 m/s, and in one embodiment in the range from about 0.05 to about
0.5 m/s.
[0278] The heat exchange fluid in the heat exchange channels may
have a temperature in the range from about 100.degree. C. to about
800.degree. C., and in one embodiment from about 250.degree. C. to
about 500.degree. C. The difference in temperature between the heat
exchange fluid and the process fluids in the process microchannel
may be up to about 50.degree. C., and in one embodiment up to about
30.degree. C., and in one embodiment up to about 10.degree. C. The
residence time of the heat exchange fluid in the heat exchange
channels may range from about 1 to about 1000 ms, and in one
embodiment about 1 to about 500 ms, and in one embodiment from 1 to
about 100 ms. The pressure drop for the heat exchange fluid as it
flows in the heat exchange channels may be up to about 3 bar/ft,
and in one embodiment up to about 1 bar/ft. The flow of the heat
exchange fluid in the heat exchange channels may be laminar or in
transition, and in one embodiment it is laminar. The Reynolds
Number for the flow of heat exchange fluid in the heat exchange
channels may be up to about 50,000, and in one embodiment up to
about 10,000, and in one embodiment up to about 2300, and in one
embodiment in the range of about 10 to about 2000, and in one
embodiment about 10 to about 1500.
[0279] The control of heat exchange during the hydrotreating and
hydrocracking processes may be advantageous for controlling
selectivity towards the desired product due to the fact that added
cooling may reduce or eliminate the formation of undesired
by-products from undesired parallel reactions with higher
activation energies.
[0280] The pressure within each individual heat exchange channel in
the microchannel reactor may be controlled using passive structures
(e.g., obstructions), orifices and/or mechanisms upstream of the
heat exchange channels or in the channels. By controlling the
pressure within each heat exchange channel, the temperature within
each heat exchange channel can be controlled. A higher inlet
pressure for each heat exchange channel may be used where the
passive structures, orifices and/or mechanisms let down the
pressure to the desired pressure. By controlling the temperature
within each heat exchange channel, the temperature in the process
microchannels may be controlled. Thus, for example, each process
microchannel may be operated at a desired temperature by employing
a specific pressure in the heat exchange channel adjacent to or in
thermal contact with the process microchannel. This may provide the
advantage of precisely controlled temperatures for each process
microchannel. The use of precisely controlled temperatures for each
process microchannel provides the advantage of a tailored
temperature profile and an overall reduction in the energy
requirements for the process.
[0281] In a scale up device, for certain applications, it may be
required that the mass of the process fluid be distributed
uniformly among the microchannels. Such an application may be when
the process fluid is required to be cooled down with adjacent heat
exchange channels. The uniform mass flow distribution may be
obtained by changing the cross-sectional area from one parallel
microchannel to another microchannel. The uniformity of mass flow
distribution may be defined by Quality Index Factor (Q-factor) as
indicated below. A Q-factor of 0% means absolute uniform
distribution.
Q = m . max - m . min m . max .times. 100 ##EQU00003##
A change in the cross-sectional area may result in a difference in
shear stress on the wall. In one embodiment, the Q-factor for the
microchannel reactor 100 may be less than about 50%, and in one
embodiment less than about 20%, and in one embodiment less than
about 5%, and in one embodiment less than about 1%.
[0282] The free stream velocity for process fluid flowing in the
process microchannels may be at least about 0.001 m/s, and in one
embodiment at least about 0.01 m/s, and in one embodiment in the
range from about 0.001 to about 200 m/s, and in one embodiment in
the range from about 0.01 to about 100 m/s, and in one embodiment
in the range from about 0.01 to about 200 m/s.
[0283] Advantages of the inventive process may include the
potential for process intensification. Conventional processes of
the prior art (that is, non-microchannel processes) often operate
under conditions of reactant dilution to prevent runaway reactions,
while the inventive process may be operated, if desired, under more
intense conditions leading to greater throughput.
[0284] While the invention has been explained in relation to
various embodiments, it is to be understood that various
modifications thereof will become apparent to those skilled in the
art upon reading the specification. Therefore, it is to be
understood that the invention disclosed herein is intended to cover
such modifications as fall within the scope of the appended
claims.
* * * * *