U.S. patent application number 14/470266 was filed with the patent office on 2015-05-21 for process for pyrolysis and gasification of a coal feed.
The applicant listed for this patent is UOP LLC. Invention is credited to Paul T. Barger, Maureen L. Bricker, Joseph A. Kocal, Matthew Lippmann, Kurt M. Vanden Bussche.
Application Number | 20150136653 14/470266 |
Document ID | / |
Family ID | 53172211 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150136653 |
Kind Code |
A1 |
Vanden Bussche; Kurt M. ; et
al. |
May 21, 2015 |
PROCESS FOR PYROLYSIS AND GASIFICATION OF A COAL FEED
Abstract
A process for gasifying and pyrolyzing coal is described. A
first coal feed is pyrolyzed into a coal tar stream and a coke
stream in a pyrolysis zone. A second coal feed is gasified in a
gasification zone to produce an effluent stream. Contaminants are
removed from the effluent stream to provide a purified effluent
stream. The purified effluent stream is introduced to the pyrolysis
zone.
Inventors: |
Vanden Bussche; Kurt M.;
(Lake in the Hills, IL) ; Barger; Paul T.;
(Arlington Heights, IL) ; Bricker; Maureen L.;
(Buffalo Grove, IL) ; Kocal; Joseph A.; (Glenview,
IL) ; Lippmann; Matthew; (Chicago, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UOP LLC |
Des Plaines |
IL |
US |
|
|
Family ID: |
53172211 |
Appl. No.: |
14/470266 |
Filed: |
August 27, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61905992 |
Nov 19, 2013 |
|
|
|
Current U.S.
Class: |
208/400 |
Current CPC
Class: |
C10J 2300/0906 20130101;
C10G 45/02 20130101; C10J 2300/0909 20130101; C10G 11/18 20130101;
C10G 1/06 20130101; C10K 1/005 20130101; C10K 3/04 20130101; C10J
3/00 20130101; C10G 29/205 20130101; C10G 47/00 20130101; C10G
27/00 20130101; C10K 1/024 20130101; C10G 1/002 20130101; C10K
1/007 20130101; C10J 2300/093 20130101; C10K 1/004 20130101 |
Class at
Publication: |
208/400 |
International
Class: |
C10G 1/06 20060101
C10G001/06 |
Claims
1. A process comprising: pyrolyzing a first coal feed into a coal
tar stream and a coke stream in a pyrolysis zone; gasifying a
second coal feed in a gasification zone to produce an effluent
stream; removing contaminants from the effluent stream to provide a
purified effluent stream; and introducing the purified effluent
stream to said pyrolysis zone.
2. The process of claim 1 wherein the gasification zone is selected
from the group consisting of a moving bed gasifier, a fluidized bed
gasifier, and an entrained flow gasifier.
3. The process of claim 1 wherein the second coal feed is
pulverized and dry-fed into the gasification zone.
4. The process of claim 1 wherein gasifying the second coal feed
takes place at a temperature between about 800.degree. C. and about
1,400.degree. C.
5. The process of claim 1 wherein the effluent stream comprises
hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, steam,
or a combination.
6. The process of claim 1 wherein removing contaminants from the
effluent stream comprises filtering particulate matter from the
effluent stream.
7. The process of claim 1 wherein removing contaminants from the
effluent stream comprises removing one or more of carbon dioxide,
hydrogen sulfide, arsenic, and mercury.
8. The process of claim 1 wherein removing contaminants comprises
performing a water shift gas reaction to generate hydrogen and
carbon dioxide from carbon monoxide and steam in the effluent
stream.
9. The process of claim 1 further comprising: fractionating the
coal tar stream to provide at least a hydrocarbon stream.
10. The process of claim 9 further comprising recovering at least
one product from the hydrocarbon stream.
11. The process of claim 10, wherein the hydrocarbon stream is
processed by at least one of hydrotreating, hydrocracking, fluid
catalytic cracking, alkylation, transalkylation, oxidation, and
hydrogenation.
12. The process of claim 1 further comprising: dividing a coal feed
to provide the first coal feed and the second coal feed.
13. A process comprising: pyrolyzing a first coal feed into a coal
tar stream and a coke stream in a pyrolysis zone; gasifying a
second coal feed in a gasification zone to produce an effluent
stream; removing contaminants from the effluent stream to produce a
purified effluent stream comprising hydrogen and one or more of
carbon monoxide and steam; separating the purified effluent stream
in a separation zone to provide at least a first stream comprising
hydrogen and a second stream comprising the one or more of carbon
monoxide and steam; and introducing the first stream or the second
stream to the pyrolysis zone.
14. The process of claim 13, wherein separating the purified
effluent stream comprises separation by pressure swing
adsorption.
15. The process of claim 13, wherein separating the purified
effluent stream comprises membrane separation to provide a permeate
comprising the first stream and a retentate comprising the second
stream.
16. The process of claim 13, wherein the first stream is introduced
to the pyrolysis zone.
17. The process of claim 13, wherein the second stream is
introduced to the pyrolysis zone.
18. The process of claim 13 wherein removing contaminants
comprises: filtering the effluent stream to remove contaminants;
and performing a water shift gas reaction to remove acid gases in
the effluent stream.
19. The process of claim 13 wherein the second coal feed is
pulverized and dry-fed into the gasification zone.
20. A process comprising: pyrolyzing a first, dry coal feed into a
coal tar stream and a coke stream in a pyrolysis zone; gasifying a
second, dry coal feed in a gasification zone to produce an effluent
stream; introducing the effluent stream to the pyrolysis zone.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/905,992 filed on Nov. 19, 2013, the entirety of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Many different types of chemicals are produced from the
processing of petroleum. However, petroleum is becoming more
expensive because of increased demand in recent decades.
[0003] Therefore, attempts have been made to provide alternative
sources for the starting materials for manufacturing chemicals.
Attention is now being focused on producing liquid hydrocarbons
from solid carbonaceous materials, such as coal, which is available
in large quantities in countries such as the United States and
China.
[0004] Pyrolysis of coal produces coke and coal tar. The
coke-making or "coking" process consists of heating the material in
closed vessels in the absence of oxygen to very high temperatures.
Coke is a porous but hard residue that is mostly carbon and
inorganic ash, which can be used in making steel.
[0005] Coal tar is the volatile material that is driven off during
heating, and it comprises a mixture of a number of hydrocarbon
compounds. It can be separated to yield a variety of organic
compounds, such as benzene, toluene, xylene, naphthalene,
anthracene, and phenanthrene. These organic compounds can be used
to make numerous products, for example, dyes, drugs, explosives,
flavorings, perfumes, preservatives, synthetic resins, and paints
and stains. The residual pitch left from the separation is used for
paving, roofing, waterproofing, and insulation.
[0006] A feed of heavy coal materials can be sent to a gasification
zone, where the heavy coal feed is mixed with oxygen and steam and
reacted under heat and pressure in the gasification zone to form
syngas, which is a mixture of carbon monoxide and hydrogen. Carbon
dioxide is also generated.
[0007] Conventionally, before gasification the heavy coal feed is
pretreated by liquefaction, and the hydrocarbon ratio of the heavy
coal feed is adjusted to either increase the hydrogen ratio
(hydrogen addition) or decrease the carbon ratio (carbon
rejection). One example liquefaction process is disclosed in U.S.
Pat. No. 4,178,227. In this process, sulfur is added to a coal
feed, and the coal feed is hydrogenated to provide additional
hydrogen. As another example, heavy coal feeds for gasification can
include a liquid coal feed provided by suspending or dissolving
coal in an organic matrix, such a hydrocarbon liquid, before
gasifying. An example dissolution process is disclosed in U.S. Pat.
No. 4,159,238. This liquefied coal feed is coked, and heavy
materials from the liquid coal feed are gasified. Another process
disclosed in U.S. Pat. No. 4,159,238 adds fuel oil to dry
pulverized coal before gasification. This process requires
additional hydrocarbons. A publication to Zeng et al., "Coal
pyrolysis in a fluidized bed for adapting to a two-stage
gasification process," Energy and Fuels, v. 25, no. 3, March 17,
2011, p. 1092-1098, discloses an example process in which heavier
product from a pyrolyzer is sent to a gasifier.
[0008] Significant oxygen is needed to produce the very high
temperatures (e.g., about 1,200.degree. C.) needed for the
gasification process. The need to vaporize a liquid coal feed
introduces additional oxygen requirements. The increased oxygen
requirements significantly add to the expense of gasification.
[0009] There is a need for an improved gasification and pyrolysis
process.
SUMMARY OF THE INVENTION
[0010] One aspect of the invention involves a process for gasifying
and pyrolyzing coal. A first coal feed is pyrolyzed into a coal tar
stream and a coke stream in a pyrolysis zone. A second coal feed is
gasified in a gasification zone to produce an effluent stream.
Contaminants are removed from the effluent stream to provide a
purified effluent stream. The purified effluent stream is
introduced to the pyrolysis zone.
[0011] Another aspect of the invention involves a process for
gasifying and pyrolyzing coal. A first coal feed is pyrolyzed into
a coal tar stream and a coke stream in a pyrolysis zone. A second
coal feed is gasified in a gasification zone to produce an effluent
stream. Contaminants are removed from the effluent stream to
produce a purified effluent stream comprising hydrogen and one or
more of carbon monoxide and steam. The purified effluent stream is
separated in a separation zone to provide at least a first stream
comprising hydrogen and a second stream comprising the one or more
of carbon monoxide and steam. Either the first stream or the second
stream is introduced to the pyrolysis zone.
[0012] Another aspect of the invention involves a process for
gasifying and pyrolyzing coal. A first, dry coal feed is pyrolyzed
into a coal tar stream and a coke stream in a pyrolysis zone. A
second, dry coal feed is gasified in a gasification zone to produce
an effluent stream. The effluent stream is introduced to the
pyrolysis zone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an illustration of a first embodiment of the
process of the present invention.
[0014] FIG. 2 is an illustration of a second embodiment of the
process of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] FIG. 1 shows one embodiment of a coal conversion process 5.
A coal feed 10 can be split to provide a first coal feed 12 and a
second coal feed 14. The first coal feed 12 is delivered to a
pyrolysis zone 15, and the second coal feed 14 is delivered to a
gasification zone 70. Alternatively, the first coal feed 12 and the
second coal feed 14 can be from different sources.
[0016] In the pyrolysis zone 15, the first coal feed 12 is heated
at high temperature, e.g., up to about 2,000.degree. C.
(3,600.degree. F.), in the absence of oxygen to drive off the
volatile components. Coking produces a coke stream 25 and a coal
tar stream 20. The coke stream 25 can be used in other processes,
such as the manufacture of steel.
[0017] In the gasification zone 70, the second coal feed 14 is
mixed with oxygen and steam and reacted under heat and pressure in
the gasification zone 70. Preferably, this second coal feed 14 is
pulverized and dry-fed, e.g., injected, into the gasification zone
70. In an example embodiment, the coal feed 10 is pulverized and
dry-fed coal, which is split and fed as the first and second coal
feeds 12, 14. Other than pulverization or other size reduction for
both the first and second coal fees 12, 14, the physical and
chemical treatment of the second coal feed 14 can be independent of
the treatment for the first coal feed 12 to the pyrolysis zone
15.
[0018] The gasification zone 70 preferably is embodied in a dry-fed
gasifier, which accepts sprayed dry coal. Examples include a moving
bed gasifier, a fluidized bed gasifier, or an entrained flow
gasifier. An example moving bed gasifier can include a feed having
a particle size of 2-50 mm, air or oxygen feed, and operated
between about 800.degree. C. and about 1,400.degree. C. A fluidized
bed gasifier can be stationary bed, circulating bed, or transport
bed. It can accept a coal feed of about 8 mm (e.g., no fines or
sticky material). It typically has an air feed, and operates at
less than about 1,000.degree. C. An entrained flow gasifier accepts
a pulverized coal feed of about 0.1 mm. It is typically oxygen fed,
and is operated at greater than about 1,200.degree. C. Preferred
gasification conditions include a temperature between about
800.degree. C. and about 1,400.degree. C.
[0019] The gasification zone 70 outputs an effluent stream 75. This
effluent stream 75 is a syngas stream that includes desirable
components such as carbon monoxide, hydrogen, and steam, as well as
contaminants such as one or more of carbon dioxide, hydrogen
sulfide, arsenic, and mercury. The effluent stream 75 is fed to a
contaminant removal zone 80 for removing particulate and chemical
contaminants from the effluent stream to provide a decontaminated
effluent stream 85. The contaminant removal zone 80 can, for
instance, include a filtration zone that filters particulate matter
or a solvent absorption zone to remove chemical contaminants from
the effluent stream 75. Example particulate and chemical
contaminants that can be removed include metals, arsenic, SO.sub.2,
H.sub.2S and mercury.
[0020] The decontaminated effluent stream 85 is sent to a water gas
shift reaction zone 90. In the water gas shift reaction zone 90, a
water gas shift reaction generates hydrogen and carbon dioxide from
carbon monoxide and steam in the decontaminated effluent stream 85.
Example water gas shift reaction processes are disclosed in U.S.
Pat. Nos. 7,022,306; 7,935,245; 8,323,590; and 8,518,334, which are
incorporated herein by reference. An example water gas shift
reaction zone is a catalytic reactor that contacts a gas having CO
and water to form CO.sub.2 and H.sub.2. The reactor may include one
or a series of shift reaction zones that exothermically react the
carbon monoxide in the effluent stream 85 over a shift catalyst in
the presence of water. The catalyst can be a metal oxide, a metal
oxide on a support, or a mixture of metal and metal oxides. Example
metal oxides include iron oxide, chromic oxide, or mixtures of
copper, zinc oxide, and alumina. A water gas shift reaction
(CO+H.sub.2O.revreaction.CO.sub.2+H.sub.2) takes place, shifting
the carbon monoxide and steam to carbon dioxide and hydrogen.
Example operating conditions for the water gas shift reaction
include ambient pressure and temperatures between about 180.degree.
C. and about 450.degree. C. Heat may be removed by direct quench
with water which may serve as reactant, by indirect heat exchange
between product and feed water, or by other methods.
[0021] The resulting purified effluent stream 95, including one or
more of hydrogen, carbon monoxide, and steam, is introduced to the
pyrolysis zone 15. The addition of the purified effluent stream 95
need not significantly change the coking conditions (e.g.,
temperature, pressure) in the pyrolysis zone 15, but can provide a
more hydrogenating environment for coking This allows improvement
or tailoring of properties of the coal tar stream 20 exiting the
pyrolysis zone.
[0022] The coal tar stream 20 can be sent to a fractionation zone
30. Coal tar comprises a complex mixture of heterocyclic aromatic
compounds and their derivatives with a wide range of boiling
points. The number of fractions and the components in the various
fractions can be varied as is well known in the art. A typical
separation process involves separating the coal tar stream 20 into
four to six streams. For example, there can be a fraction 35
comprising NH.sub.3, CO, and light hydrocarbons, a light oil
fraction 40 with boiling points between 0.degree. C. and
180.degree. C., a middle oil fraction 45 with boiling points
between 180.degree. C. to 230.degree. C., a heavy oil fraction 50
with boiling points between 230 to 270.degree. C., an anthracene
oil fraction (not shown) with boiling points between 270.degree. C.
to 350.degree. C., and pitch 55.
[0023] The light oil fraction 40 contains compounds such as
benzenes, toluenes, xylenes, naphtha, coumarone-indene,
dicyclopentadiene, pyridine, and picolines. The middle oil fraction
45 contains compounds such as phenols, cresols and cresylic acids,
xylenols, naphthalene, high boiling tar acids, and high boiling tar
bases. The heavy oil fraction 50 contains creosotes. The anthracene
oil fraction (not shown) contains anthracene. Pitch 55 is the
residue of the coal tar distillation containing primarily aromatic
hydrocarbons and heterocyclic compounds.
[0024] One or more hydrocarbon fractions (middle oil fraction 45 is
shown in FIG. 1) can be introduced to hydrocarbon conversion zone
60 for providing one or more products from the hydrocarbon
fraction. Suitable hydrocarbon conversion zones include, but are
not limited to, hydrotreating zones, hydrocracking zones, fluid
catalytic cracking zones, alkylation zones, transalkylation zones,
oxidation zones and hydrogenation zones.
[0025] Hydrotreating is a process in which hydrogen gas is
contacted with a hydrocarbon stream in the presence of suitable
catalysts which are primarily active for the removal of
heteroatoms, such as sulfur, nitrogen, and metals from the
hydrocarbon feedstock. In hydrotreating, hydrocarbons with double
and triple bonds may be saturated. Aromatics may also be saturated.
Typical hydrotreating reaction conditions include a temperature of
about 290.degree. C. (550.degree. F.) to about 455.degree. C.
(850.degree. F.), a pressure of about 3.4 MPa (500 psig) to about
26.7 MPa (4,000 psig), a liquid hourly space velocity of about 0.5
hr.sup.-1 to about 4 hr.sup.-1, and a hydrogen rate of about 168 to
about 1,011 Nm.sup.3/m.sup.3 oil (1,000-6,000 scf/bbl). Typical
hydrotreating catalysts include at least one Group VIII metal,
preferably iron, cobalt and nickel, and at least one Group VI
metal, preferably molybdenum and tungsten, on a high surface area
support material, preferably alumina. Other typical hydrotreating
catalysts include zeolitic catalysts, as well as noble metal
catalysts where the noble metal is selected from palladium and
platinum.
[0026] Hydrocracking is a process in which hydrocarbons crack in
the presence of hydrogen to lower molecular weight hydrocarbons.
Typical hydrocracking conditions may include a temperature of about
290.degree. C. (550.degree. F.) to about 468.degree. C.
(875.degree. F.), a pressure of about 3.5 MPa (500 psig) to about
20.7 MPa (3,000 psig), a liquid hourly space velocity (LHSV) of
about 1.0 to less than about 2.5 hr.sup.-1, and a hydrogen rate of
about 421 to about 2,527 Nm.sup.3/m.sup.3 oil (2,500-15,000
scf/bbl). Typical hydrocracking catalysts include amorphous
silica-alumina bases or low-level zeolite bases combined with one
or more Group VIII or Group VIB metal hydrogenating components, or
a crystalline zeolite cracking base upon which is deposited a Group
VIII metal hydrogenating component. Additional hydrogenating
components may be selected from Group VIB for incorporation with
the zeolite base.
[0027] Fluid catalytic cracking (FCC) is a catalytic hydrocarbon
conversion process accomplished by contacting heavier hydrocarbons
in a fluidized reaction zone with a catalytic particulate material.
The reaction in catalytic cracking is carried out in the absence of
substantial added hydrogen or the consumption of hydrogen. The
process typically employs a powdered catalyst having the particles
suspended in a rising flow of feed hydrocarbons to form a fluidized
bed. In representative processes, cracking takes place in a riser,
which is a vertical or upward sloped pipe. Typically, a pre-heated
feed is sprayed into the base of the riser via feed nozzles where
it contacts hot fluidized catalyst and is vaporized on contact with
the catalyst, and the cracking occurs converting the high molecular
weight oil into lighter components including liquefied petroleum
gas (LPG), gasoline, and a distillate. The catalyst-feed mixture
flows upward through the riser for a short period (a few seconds),
and then the mixture is separated in cyclones. The hydrocarbons are
directed to a fractionator for separation into LPG, gasoline,
diesel, kerosene, jet fuel, and other possible fractions. While
going through the riser, the cracking catalyst is deactivated
because the process is accompanied by formation of coke which
deposits on the catalyst particles. Contaminated catalyst is
separated from the cracked hydrocarbon vapors and is further
treated with steam to remove hydrocarbon remaining in the pores of
the catalyst. The catalyst is then directed into a regenerator
where the coke is burned off the surface of the catalyst particles,
thus restoring the catalyst's activity and providing the necessary
heat for the next reaction cycle. The process of cracking is
endothermic. The regenerated catalyst is then used in the new
cycle. Typical FCC conditions include a temperature of about
400.degree. C. to about 800.degree. C., a pressure of about 0 to
about 688 kPag (about 0 to 100 psig), and contact times of about
0.1 seconds to about 1 hour. The conditions are determined based on
the hydrocarbon feedstock being cracked, and the cracked products
desired. Zeolite-based catalysts are commonly used in FCC reactors,
as are composite catalysts which contain zeolites, silica-aluminas,
alumina, and other binders.
[0028] Alkylation is typically used to combine light olefins, for
example mixtures of alkenes such as propylene and butylene, with
isobutane to produce a relatively high-octane branched-chain
paraffinic hydrocarbon fuel, including isoheptane and isooctane.
Similarly, an alkylation reaction can be performed using an
aromatic compound such as benzene in place of the isobutane. When
using benzene, the product resulting from the alkylation reaction
is an alkylbenzene (e.g. toluene, xylenes, ethylbenzene, etc.). For
isobutane alkylation, typically, the reactants are mixed in the
presence of a strong acid catalyst, such as sulfuric acid or
hydrofluoric acid. The alkylation reaction is carried out at mild
temperatures, and is typically a two-phase reaction. Because the
reaction is exothermic, cooling is needed. Depending on the
catalyst used, normal refinery cooling water provides sufficient
cooling. Alternatively, a chilled cooling medium can be provided to
cool the reaction. The catalyst protonates the alkenes to produce
reactive carbocations which alkylate the isobutane reactant, thus
forming branched chain paraffins from isobutene. Aromatic
alkylation is generally now conducted with solid acid catalysts
including zeolites or amorphous silica-aluminas.
[0029] The alkylation reaction zone is maintained at a pressure
sufficient to maintain the reactants in liquid phase. For a
hydrofluoric acid catalyst, a general range of operating pressures
is from about 200 to about 7,100 kPa absolute. The temperature
range covered by this set of conditions is from about -20.degree.
C. to about 200.degree. C. For at least alkylation of aromatic
compounds, the temperature range is about from 100.degree.
to200.degree. C. at the pressure range of about 200 to about 7,100
kPa.
[0030] Transalkylation is a chemical reaction resulting in transfer
of an alkyl group from one organic compound to another. Catalysts,
particularly zeolite catalysts, are often used to effect the
reaction. If desired, the transalkylation catalyst may be metal
stabilized using a noble metal or base metal, and may contain
suitable binder or matrix material such as inorganic oxides and
other suitable materials. In a transalkylation process, a
polyalkylaromatic hydrocarbon feed and an aromatic hydrocarbon feed
are provided to a transalkylation reaction zone. The feed is
usually heated to reaction temperature and then passed through a
reaction zone, which may comprise one or more individual reactors.
Passage of the combined feed through the reaction zone produces an
effluent stream comprising unconverted feed and product
monoalkylated hydrocarbons. This effluent is normally cooled and
passed to a stripping column in which substantially all Cs and
lighter hydrocarbons present in the effluent are concentrated into
an overhead stream and removed from the process. An aromatics-rich
stream is recovered as net stripper bottoms, which is referred to
as the transalkylation effluent.
[0031] The transalkylation reaction can be effected in contact with
a catalytic composite in any conventional or otherwise convenient
manner and may comprise a batch or continuous type of operation,
with a continuous operation being preferred. The transalkylation
catalyst is usefully disposed as a fixed bed in a reaction zone of
a vertical tubular reactor, with the alkylaromatic feed stock
charged through the bed in an upflow or downflow manner. The
transalkylation zone normally operates at conditions including a
temperature in the range of about 130.degree. C. to about
540.degree. C. The transalkylation zone is typically operated at
moderately elevated pressures broadly ranging from about 100 kPa to
about 10 MPa absolute. The transalkylation reaction can be effected
over a wide range of space velocities. That is, volume of charge
per volume of catalyst per hour; weight hourly space velocity
(WHSV) generally is in the range of from about 0.1 to about 30
hr.sup.-1. The catalyst is typically selected to have relatively
high stability at a high activity level.
[0032] Oxidation involves the oxidation of hydrocarbons to
oxygen-containing compounds, such as aldehydes. The hydrocarbons
include alkanes, alkenes, typically with carbon numbers from 2 to
15, and alkyl aromatics, Linear, branched, and cyclic alkanes and
alkenes can be used. Oxygenates that are not fully oxidized to
ketones or carboxylic acids can also be subjected to oxidation
processes, as well as sulfur compounds that contain --S--H
moieties, thiophene rings, and sulfone groups. The process is
carried out by placing an oxidation catalyst in a reaction zone and
contacting the feed stream which contains the desired hydrocarbons
with the catalyst in the presence of oxygen. The type of reactor
which can be used is any type well known in the art such as
fixed-bed, moving-bed, multi-tube, CSTR, fluidized bed, etc. The
feed stream can be flowed over the catalyst bed either up-flow or
down-flow in the liquid, vapor, or mixed phase. In the case of a
fluidized-bed, the feed stream can be flowed co-current or
counter-current. In a CSTR the feed stream can be continuously
added or added batch-wise. The feed stream contains the desired
oxidizable species along with oxygen. Oxygen can be introduced
either as pure oxygen or as air, or as liquid phase oxididents
including hydrogen peroxide, organic peroxides, or peroxy-acids.
The molar ratio of oxygen (O.sub.2) to alkane can range from about
5:1 to about 1:10. In addition to oxygen and alkane or alkene, the
feed stream can also contain a diluent gas selected form nitrogen,
neon, argon, helium, carbon dioxide, steam or mixtures thereof. As
stated, the oxygen can be added as air which could also provide a
diluent. The molar ratio of diluent gas to oxygen ranges from
greater than zero to about 10:1. The catalyst and feed stream are
reacted at oxidation conditions which include a temperature of
about 300.degree. C. to about 600.degree. C., a pressure of about
101 kPa to about 5,066 kPa and a space velocity of about 100 to
about 100,000 hr.sup.-1.
[0033] Hydrogenation involves the addition of hydrogen to
hydrogenatable hydrocarbon compounds. Alternatively hydrogen can be
provided in a hydrogen-containing compound with ready available
hydrogen, such as tetralin, alcohols, hydrogenated naphthalenes,
and others via a transfer hydrogenation process with or without a
catalyst. The hydrogenatable hydrocarbon compounds are introduced
into a hydrogenation zone and contacted with a hydrogen-rich
gaseous phase and a hydrogenation catalyst in order to hydrogenate
at least a portion of the hydrogenatable hydrocarbon compounds. The
catalytic hydrogenation zone may contain a fixed, ebulated or
fluidized catalyst bed. This reaction zone is typically at a
pressure from about 689 kPag (100 psig) to about 13790 kPag (2,000
psig) with a maximum catalyst bed temperature in the range of about
177.degree. C. (350.degree. F.) to about 454.degree. C.
(850.degree. F.). The liquid hourly space velocity is typically in
the range from about 0.2 hr.sup.-1 to about 10 hr.sup.-1 and
hydrogen circulation rates from about 200 standard cubic feet per
barrel (SCFB) (35.6 m.sup.3 /m.sup.3) to about 10,000 SCFB (1778
m.sup.3 /m.sup.3).
[0034] FIG. 2 shows a second embodiment of a coal conversion
process 98, where like reference characters refer to like features.
The purified effluent stream 95 from the water gas shift reaction
zone 90 includes hydrogen as well as carbon monoxide, steam, or
both. The purified effluent stream 95 is introduced to a separation
zone 100 for separation into a first stream 110 comprising hydrogen
and a second stream 105 comprising the carbon monoxide, steam, or
both. Example separation zones 100 include pressure swing
adsorption zones and membrane separation zones.
[0035] An example pressure swing adsorption (PSA) zone separates
and purifies hydrogen from a feed gas mixture of larger molecules.
The process provides adsorption of the adsorbable species, such as
carbon oxides, water and light hydrocarbon molecules, on an
adsorbent at a high adsorption pressure with passage of the smaller
hydrogen molecules and pressure reduction to a lower desorption
pressure to desorb the adsorbed species. It is generally desirable
to employ the PSA process in multiple bed systems such as those
described in U.S. Pat. No. 3,430,418, herein incorporated by
reference, in which at least four adsorption beds are employed. The
PSA process can be carried out in such systems on a cyclical basis,
employing a processing sequence.
[0036] A suitable adsorbent may be activated calcium zeolite A with
or without activated carbon. If this combination of adsorbents is
used, the activated carbon will adsorb the carbon dioxide and
water, while the zeolite A will adsorb the carbon monoxide and
hydrocarbons. An example pressure swing adsorption zone is
disclosed in U.S. Patent Publication No. 2010/0155295, which is
incorporated by reference.
[0037] Membrane separation involves thin, semipermeable membranes
that selectively separate some fluid components from others. The
separation is based on the relative permeabilities of the various
components in the mixture, resulting from a gradient of driving
forces, such as pressure, partial pressure, concentration, and
temperature. The selective permeation results in the separation of
the fluid mixture into portions commonly called "retentate" e.g.,
the slower permeating materials, and the permeate, e.g., the faster
permeating materials. An example membrane separation zone provides
a permeate comprising the first stream 110 and a retentate
comprising the second stream 105.
[0038] Either the first stream 110 or the second stream 105 is
selected and introduced to the pyrolysis zone 15 as a co-feed. In
the example process shown in FIG. 2, the first stream 110 including
hydrogen is introduced to the pyrolysis zone 15, but in other
embodiments the second stream 105 including carbon monoxide and
steam is introduced to the pyrolysis zone. The carbon monoxide and
steam in the second stream 105 can be further separated downstream
of the separation zone 100, and either carbon monoxide or steam can
be introduced to the pyrolysis zone 15, but this additional
separation is not necessary.
[0039] While at least one exemplary embodiment has been presented
in the foregoing detailed description of the invention, it should
be appreciated that a vast number of variations exist. It should
also be appreciated that the exemplary embodiment or exemplary
embodiments are only examples, and are not intended to limit the
scope, applicability, or configuration of the invention in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the invention. It being understood that
various changes may be made in the function and arrangement of
elements described in an exemplary embodiment without departing
from the scope of the invention as set forth in the appended
claims.
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