U.S. patent application number 11/431772 was filed with the patent office on 2006-09-07 for filtering medium and method for contacting solids containing feeds for chemical reactors.
Invention is credited to John N. Glover.
Application Number | 20060196826 11/431772 |
Document ID | / |
Family ID | 26776757 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196826 |
Kind Code |
A1 |
Glover; John N. |
September 7, 2006 |
Filtering medium and method for contacting solids containing feeds
for chemical reactors
Abstract
A filtering medium and method for removing contaminants from an
organic-based feed stream that includes the use of a layer of
ceramic filter units having a plurality of elliptical or trisoidal
openings extending therethrough to filter organic-based feed
streams and to provide liquid distribution upstream of the catalyst
beds.
Inventors: |
Glover; John N.; (Spring,
TX) |
Correspondence
Address: |
BRACEWELL & GIULIANI LLP
P.O. BOX 61389
HOUSTON
TX
77208-1389
US
|
Family ID: |
26776757 |
Appl. No.: |
11/431772 |
Filed: |
May 10, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09320950 |
May 27, 1999 |
|
|
|
11431772 |
May 10, 2006 |
|
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60087235 |
May 29, 1998 |
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Current U.S.
Class: |
210/510.1 ;
502/100; 502/178 |
Current CPC
Class: |
B01D 39/2068
20130101 |
Class at
Publication: |
210/510.1 ;
502/100; 502/178 |
International
Class: |
B01D 24/00 20060101
B01D024/00; B01J 27/224 20060101 B01J027/224 |
Claims
1. A catalyst composition which comprises a ceramic foam material
interspersed between solid catalyst particles.
2. The catalyst composition of claim 1, wherein the ceramic foam
material is comprised of a silicon carbide composition.
3. The catalyst composition of claim 1, wherein the ceramic foam
material is in the shape of hollow cubes.
4. The catalyst composition of claim 1, wherein the porosity of the
ceramic foam material is in the range of from 10 to 800 pores per
linear inch.
5. The catalyst composition of claim 4, wherein the porosity is
within the range of 10 to 80 pores per linear inch.
6. The catalyst composition of claim 4, wherein the porosity is in
the range of 10 to 30 pores per linear inch.
7. The catalyst composition of claim 1, wherein the void space in
the ceramic foam material ranges from about 80 to about 85 volume
%.
8. The catalyst composition of claim 7, wherein the void space is
about 85 volume %.
9. The catalyst composition of claim 1, wherein the crush strength
of the ceramic foam material ranges from 100 to 600 lbs/sq.
inch.
10. The catalyst composition of claim 9, wherein the crush strength
of the ceramic foam material ranges from 400 to 500 lbs/sq.
inch.
11. The catalyst composition of claim 1, wherein the percentage of
ceramic foam material in the mixture, based on volume, ranges from
20 to 60%.
12. The catalyst composition of claim 1, wherein the solid catalyst
particles comprise diatomaceous earth.
13. The catalyst composition of claim 1, wherein the solid catalyst
particles comprise a solid phosphoric acid catalyst.
14. The catalyst composition of claim 13, wherein the solid
catalyst particles comprise a diatomaceous earth impregnated with
phosphoric acid.
Description
RELATED APPLICATION
[0001] This application is a continuation patent application that
claims the benefit of U.S. application Ser. No. 09/320,950, filed
May 27, 1999, which claimed the benefit of U.S. Provisional
Application Ser. No. 60/087,235, filed May 29, 1998.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a filtering medium and method for
filtering solids from organic-based feed streams to chemical
reactors. In another aspect, this invention relates to a filtering
medium and method for providing flow distribution of organic-based
feed streams to chemical reactors. More particularly, the invention
relates to a filtering medium and method for filtering solids and
providing liquid distribution for organic-based feed streams that
are subsequently processed in chemical reactors having discrete
solid element catalyst bed(s). A further aspect of the invention
relates to a filtering medium and method for partially reacting
polymer precursors in organic-based feed streams to chemical
reactors to reduce fouling of the solid element catalyst
bed(s).
[0004] 2. Description of Related Art
[0005] Typically chemical reactor beds include discrete solid
catalyst particles contained in one or more fixed beds. Often these
beds are supported, or retained, at their inlet and/or outlet by
materials which are inert to the reaction. These inert materials
may trap all or some solid contaminants such as dirt, iron oxide,
iron sulfide, asphaltenes, coke fines, catalyst fines, sediments or
other entrained foreign particulate material in the reactor feed
stream. The trapping of the contaminants is to prevent undesirable
material from plugging, poisoning or otherwise deactivating the
catalyst bed. The inert materials, or inerts, traditionally used
are typically made of ceramic material in the form of pellets or
spheres and typically must be resistant to crushing, high
temperatures and/or high pressures. In addition, these materials
may facilitate distribution of the feed stream across the catalyst
bed in such a manner to reduce channeling through the catalyst
bed.
[0006] For the last ten to fifteen years, high void fraction
ceramic bed toppings, such as inert ceramic cylindrical filter
units with cross sections of approximately 3/8 inch thicknesses and
approximately 1/2 inch to 11/4 inches in diameter with five to ten
internal holes of approximately 1/8 inch size, the holes being
round or triangular shaped, have been used on the top of fixed bed
reactors processing organic feed streams. These bed toppings have
been relatively successful at reducing pressure drops by improving
liquid distribution. However, attempts to trap particulate matter
have not been as successful. Catalyst bed plugging with
contaminants such as dirt, iron oxide, iron sulfide, asphaltenes,
coke fines, catalyst fines, sediments, or other entrained foreign
particulate material remains to be a problem for the industry.
Skimming, or removal, of the top portion of the catalyst is
required when the filtering capacity of the bed topping or inerts
is exhausted resulting in the catalyst itself being used as a
filter. Thus, it is highly desirable to increase the efficiency of
the inert bed filtration.
[0007] In addition to catalyst fouling by particulate matter in the
organic-based stream, polymerization of polymer precursors, e.g.,
diolefins, found in the organic-based feed stream may also foul the
catalyst. In particular, two mechanisms of polymerization, free
radical polymerization and condensation-type polymerization, may
cause catalyst bed fouling, gumming or plugging. The addition of
antioxidants to control free radical polymerization has been found
useful where the organic-based feed stream has encountered oxygen.
Condensation polymerization of diolefins typically occurs after the
organic-based feed is heated. Therefore, filtering prior to the
organic-based feed stream entering the reactor may not be helpful
to remove these foulants as the polymerization reactions generally
take place in the reactors.
[0008] It is highly desirable to increase the efficiency of the
inert bed filtration and to control the rate of reaction of the
diolefins or other polymer precursors. Thus, the development of a
filtering medium and method for filtration that increases the
efficiency of the filtering of the contaminated feed stream may
also reduce the pressure drop associated with plugging. The method
of the present invention for filtration and flow distribution for
chemical reactors, when compared with previously proposed prior art
methods, has the advantages of providing more efficient filtering;
increasing catalyst life; decreasing catalyst losses; and reducing
the need to take the reactor off-line for maintenance when removal
or replacement of the inert material or any catalyst that is
plugged is required. These benefits may result in both capital and
operating savings.
[0009] Disadvantages associated with current filtration and liquid
distribution designs and methods in fixed bed chemical reactors may
result in poor liquid distribution to the catalyst bed. Partial
plugging of the catalyst bed with contaminants, or gumming by
reactive diolefins or other polymer precursors, may also cause
maldistribution. The maldistribution may result in channeling and
corresponding bypassing of portions of the catalyst bed, reducing
the catalyst efficiency. Usually, a maldistribution problem is
evidenced by radial temperature differences across the reactor.
Therefore, the art has sought a medium and method for flow
distribution that may spread the liquid more uniformly across and
subsequently through the catalyst bed, provide efficient filtering
and reduce fouling caused by undesired polymerization
reactions.
[0010] Accordingly, prior to the development of the present
invention, filtering media and methods for filtering, or
distributing, organic-based feed streams to chemical reactors had
limited abilities to provide both feed distribution and filtering
capacity without plugging or blinding. Relatively large pressure
drops across the filtering and/or distribution media of the
previous apparatus and methods require excessive capital and
operating costs and cause process safety and environmental concerns
arising from maintenance required shutdowns and start-ups.
Therefore, the art has sought a method for extending the run life
of catalyst beds by filtering and distributing organic-based feed
streams to chemical reactors which does not: require excessive
amounts of catalyst; cause relatively large pressure drops across
the bed; require relatively large capacity circulation pumps or
compressors; and cause process safety and environmental concerns
arising from reactor shutdowns and start-ups.
SUMMARY OF INVENTION
[0011] In accordance with the invention, the foregoing advantages
may be achieved through the present media and methods of filtering
and distributing an organic-based feed for chemical reactors. The
filtering medium of the present invention includes a plurality of
ceramic filter units, at least some of the ceramic filter units
having a plurality of openings extending therethrough, and at least
some of the openings selected from the group of ellipses or
trisoids. The elliptical and trisoidal shaped openings are believed
to increase particulate trapping. The elliptical and trisoidal
shaped openings create an area of reduced liquid velocity, similar
to that in a bend of a river. Sedimentation may occur on the inside
of the turn, or river bend, while no particulate trapping occurs on
the outside of the turn. The ceramic filter units may be made from
any commercially available ceramic precursors including fire clays
such as ball clay or silicate-aluminum clays such as
montmorillonite clays or preferably, kaolinite clay. Optionally,
ceramic precursor powders such as cordierite, mullite, zirconia
stabilized with magnesia or calcia, zirconia toughened alumina, and
the like may be used. The ceramic filter units may be formed by
molding, stamping, pressing or preferably, by extrusion.
[0012] The ceramic filter units of the present invention may have a
thickness from about 1/8 to 11/2 inches, preferably from about 1/4
to 1/2 inches, more preferably from about 1/4 to 3/8 inches. An
additional feature of the present invention may include ceramic
filter units in a variety of shapes. The shapes may include
irregular or closed plane cross-sectional configurations, including
but not limited to ellipses and circles, or substantially any
polygonal configuration, such as triangles, quadrilaterals, and
pentagons, among others. The closed plane cross-sectional
configurations may have widths of about 1/4 to 3 inches at the
widest point. Polygonal cross-sectional configurations used may
include sides having lengths of about 1/8 to 3 inches. In
particular, substantially circular cross-sectional configurations
of about 1/4 to 3 inch diameters; ellipses having minor axes of
about 1/4 to 2 and major axes ranging from about 3/8 to 3 inches;
square cross-sectional configurations of about 1/4 to 3 inch and
rectangles having lengths of about 1/4 to 3 inches, and widths of
about 1/4 to 3 inches may be used.
[0013] The periphery surface of the ceramic filter units may be
provided with flutes. As used herein, the term flutes encompasses
both flutes and grooves. The ceramic filter units also have top and
bottom surfaces. These top and bottom surfaces are generally
smooth. However, another feature of the present invention may
include contacting the solid particles with the ceramic filter
units have top and bottom surfaces, wherein at least one of the top
and bottom surfaces are irregularly shaped. A preferred embodiment
has irregularity shaped top and bottom surfaces which have ridges,
rounded beads, or waves. The irregular surfaces provide protruding
areas to contact the entrained solids, reducing the particle
velocity below of the fluid, effectively removing entrained solids.
The liquid flowing over the irregular surface is induced to form
eddies, which in turn forces more entrained solids to contact the
ceramic filter units' irregular surface, removing more entrained
solids. Another feature of this aspect of the preset invention is
that the amplitude and length of the waves of ridges may be
adjusted based upon the particles sizes, fluid velocity and
viscosity.
[0014] The number and size of the plurality of openings may be
varied to change the void fraction of the filter unit, the void
fraction of the filter unit being measured as the sum of the areas
of openings divided by one cross-sectional area including the area
of the openings. The void area of the ceramic filter units may
range from about 20 to 70 percentage void area, preferably from
about 40 to 65 percentage void area, more preferably from about 50
to 65 percentage void area.
[0015] Another feature of the present invention is to vary the
packing factor of the ceramic filter units to affect filtration of
varying particle sizes, wherein the packing factor is measured by
dividing the surface area of the randomly packed filter units (all
surfaces) in square feet by the volume unoccupied by the randomly
packed filter units (hereinafter called "void volume") as measured
the volume of water at 60.degree. F. required to fill one randomly
packed cubic foot. The packing factor may range from about 200 to
500 ft.sup.2/ft.sup.3, preferably from about 220 to 450
ft.sup.2/ft.sup.3, more preferably from about 240 to 400
ft.sup.2/ft.sup.3. In accordance with the invention, the size,
shape and void fraction of the ceramic filter units may be varied
to change the packing factor of the randomly dumped ceramic filter
unit layers.
[0016] In accordance with another aspect of the present invention,
at least some of the ceramic filter units are formed of a ceramic
which may comprise a substrate having a substantially uniform
coating of a selected catalyst including a porous alumina coating
with a Group VI-B metal or a Group VIII metal, or both. Preferably,
the Group VI-B metal is molybdenum and preferably, the Group VIII
metal is either nickel or cobalt. More preferably, the Group VI-B
metal and Group VIII metal are impregnated into at least some of
the ceramic filter units. This embodiment of the media of the
present invention is useful to extend the run life of the catalyst
bed. The catalytically active ceramic filter units may be utilized
to react diolefins or other polymer precursors and also to act as a
filter and distributor. By filtering solids and partially reacting
any polymer precursors, e.g., diolefins, fouling of the bed is
reduced, effectively extending the run time of the reactor. In
another embodiment of this invention, at least some of the ceramic
filter units are formed of a ceramic, which comprises a porous
inorganic oxide selected from the group consisting of alumina,
silica, silicaalumina, magnesia, silica-magnesia and titania. At
least some of the ceramic filter units of the present invention may
also contain a metal oxide, metal nitride, or metal carbide
selected from the group consisting of titanium, zirconium,
tungsten, silicon or boron. Another feature of this aspect of the
present invention is that the ceramic filter units may contain a
metal boride selected from the group consisting of titanium,
zirconium or tungsten. Still a further aspect of the present
invention includes at least some of the ceramic filter units may
contain a zeolite selected from the group consisting of zeolite L,
zeolite X and zeolite Y.
[0017] The method of the present invention for removing
contaminants from an organic-based feed stream, in a chemical
reactor may include the steps of providing a layer of ceramic
filter units, at least some of the ceramic filter units should have
a plurality of openings extending therethrough, at least some of
the openings having a shape selected from the group consisting of
ellipses or trisoids, the layer of ceramic filter units being in an
amount sufficient to filter some or all of the contaminants from
the organic-based feed stream, and passing the organic-based feed
stream through the layer of ceramic filter units. The organic-based
feed stream may be an organic-based liquid, a vapor phase, or both,
and the contaminants may include dirt, iron oxide, iron sulfide,
asphaltenes, coke fines, catalyst fines, sediments, other entrained
foreign particulate matter or polymer precursors such as
diolefins.
[0018] The ceramic filter units of the present invention should be
provided in a layer in an amount sufficient to remove some or all
of the contaminants from the organic-based feed stream. Preferably,
the elliptical or trisoidal shaped openings extend axially along
the longitudinal axis of the ceramic filter units. Another feature
of the present invention for removing contaminants from a
contaminated organic-based feed stream in a chemical reactor
includes the steps of providing a layer of ceramic filter units, at
least some of the filter units having a plurality of openings
extending therethrough, at least some of the openings having a
shape selected from the group consisting of ellipses or trisoids,
and contacting the contaminated organic-based feed stream with the
ceramic filter units to remove the contaminants from the
contaminated organic-based feed stream. Another feature of the
present invention may include the step of providing a
decontaminated organic-based feed stream for further
processing.
[0019] More particularly, the invention relates to a process for
improving feed quality of organic-based feed streams to chemical
reactors by providing a decontaminated organic based feed stream
for processing in the chemical reactor. Preferably, the chemical
reactors use discrete solid element catalyst beds. As used herein,
the term chemical reactors may include hydrotreater, hydrorefiner,
hydrocracker, reformer, alkylation, isomerization, and
polymerization reactors, among others. The discrete solid catalyst
particles may be contained in one or more fixed beds and in either
an upflow, downflow or radial flow design.
[0020] An additional feature of the present invention may include
the step of using the ceramic filter units of the present invention
having an overall thickness which may be varied from about 1/8 to
11/2 inches, preferably from about 1/4 to 1/2 inches, more
preferably from about 1/4 to 3/8 inches. An additional feature of
the present invention may include using ceramic filter units in a
variety of cross-sectional configurations. The cross-sectional
configurations may include free form or polygonal closed plane
shapes, including but not limited to ellipses and circles or
substantially any polygonal configuration, such as triangles,
quadrilaterals, and pentagons, among others. The cross-sectional
configurations may include widths of about 1/4 to 3 inches at the
widest point. Polygonal cross-sectional configurations may include
sides having lengths of about 1/8 to 3 inches. In particular,
substantially circular cross-sectional configurations of about 1/4
to 3 inch diameters; ellipses having minor axes of about 1/4 to 2
and major axes ranging from about 3/8 to 3 inches; square
cross-sectional configurations of about 1/4 to 3 inch and
rectangles having lengths of about 1/4 to 3 inches, and widths of
about 1/4 to 3 inches may be used. Additionally, each ceramic
filter unit periphery may be provided with a smooth or fluted
periphery surface. The ceramic filter units may also be provided
top and bottom surfaces that are substantially smooth. Optionally,
one or both of the top and bottom surfaces may be provided with an
irregular shape.
[0021] The number and size of the plurality of openings used may be
varied to change the void fraction of the ceramic filter units. The
void fraction of the ceramic filter units used may range from about
20 to 70 percentage void area, preferably from about 40 to 65
percentage void area, more preferably from about 50 to 65
percentage void area. Another feature of the present invention is
to vary the packing factor of the ceramic filter units used to
affect filtration of varying particle sizes. The packing factor
used may range from about 200 to 500 ft.sup.2/ft.sup.3, preferably
from about 220 to 450 ft.sup.2/ft.sup.3, more preferably from about
240 to 400 ft.sup.2/ft.sup.3. In accordance with the invention, the
size, shape and void area of the ceramic filter units used may be
varied to change the packing factor of the randomly dumped ceramic
filter unit layers.
[0022] The method of the present invention is useful to extend the
run life of the catalyst bed. Catalytically active ceramic filter
units may be utilized to react diolefins or other polymer
precursors and also to act as a filter and distributor. By
filtering solids and partially reacting any polymer precursors,
e.g., diolefins, fouling of the bed is reduced, effectively
extending the run time of the reactor. In accordance with another
aspect of the present invention, the step of contacting the
contaminated organic-based feed stream with the ceramic filter
units may include depositing a catalyst on at least some of the
ceramic filter units prior to contacting the contaminated
organic-based feed stream. Another feature of this aspect of the
present invention may include the use of at least some ceramic
filter units having a plurality of openings selected from the group
consisting of ellipses and trisoids as a substrate having a
substantially uniform coating of a selected catalyst including a
porous alumina coating with a Group VI-13 metal or a Group VIII
metal, or both. Preferably, the Group VI-B metal is molybdenum and
preferably, the Group VIII metal is either nickel or cobalt. More
preferably, the Group VI-B metal and Group VIII metal are
impregnated into at least some of the ceramic filter units having a
plurality of openings extending therethrough, at least some of the
openings having a shape selected from the group consisting of
ellipses and trisoids. In another embodiment of this invention, at
least some of the ceramic filter units used may comprise a porous
inorganic oxide selected from the group consisting of alumina,
silica, silica-alumina, magnesia, silica-magnesia and titania. At
least some of the ceramic filter units used in the present
invention may also be a metal oxide, metal nitride, or metal
carbide selected from the group consisting of titanium, zirconium,
tungsten, silicon or boron. Another feature of this aspect of the
present invention is using at least some ceramic filter units
comprising a metal boride selected from the group consisting of
titanium, zirconium or tungsten. Still a further aspect of the
present invention includes using at least some ceramic filter units
comprising a zeolite selected from the group consisting of zeolite
L, zeolite X and zeolite Y.
[0023] In accordance with another aspect of the present invention,
the present method of flow distribution in a chemical reactor
includes the steps of: providing a layer of ceramic filter units,
at least some of the ceramic filter units having a plurality of
openings extending therethrough, at least some of the openings
having a shape selected from the group consisting of ellipses and
trisoids, at least some of the ceramic filter units having a
plurality of flow passageways defined by the plurality of openings
extending through the ceramic filter units; contacting an
organic-based feed stream with the layer of ceramic filter units;
and subdividing the organic-based feed stream into a plurality of
smaller fluid streams by passing the organic-based feed stream
through the plurality of flow passageways defined by the plurality
of openings. A further feature of this aspect of the present
invention may include the steps of removing contaminants from a
contaminated organic-based feed stream, and providing a
decontaminated and uniformly spread organic-based feed stream to a
catalyst bed for further processing in the chemical reactor.
[0024] The method of the present invention for filtering
organic-based feed streams in chemical reactors, when compared with
prior art methods, has the advantages of: reducing the volume of
ceramic materials required; lowering capital costs; improving the
filtration of the solid particular matter from the feed streams;
decreasing the pressure drop across the system; increasing run time
of the reactor; lowering operating costs; increasing process
safety; and reducing environmental concerns.
BRIEF DESCRIPTION OF DRAWINGS
[0025] In the drawings:
[0026] FIG. 1 is partial a cross-sectional side view of a single
fixed bed chemical reactor showing a specific embodiment of the
present invention;
[0027] FIG. 2 is a partial cross-sectional side view of a multiple
fixed bed chemical reactor showing another embodiment of the
present invention;
[0028] FIG. 3 is a partial cross-sectional side view of a radial
flow reactor showing another embodiment of the present
invention;
[0029] FIG. 4 is a perspective view of a circular shaped ceramic
filter unit with a smooth periphery having a plurality of
elliptical openings extending therethrough in accordance with the
present invention;
[0030] FIG. 5 is a perspective view of a circular shaped ceramic
filter unit with a fluted periphery having a central circular
opening surrounded with a plurality of elliptical openings wherein
all openings extend axially through the longitudinal axis of the
ceramic filter unit in accordance with the present invention;
[0031] FIG. 6 is a perspective view of triangular shaped ceramic
filter unit having a plurality of elliptical openings extending
therethrough in accordance with the present invention;
[0032] FIG. 7 is a perspective view of a quadrilateral shaped
ceramic filter unit having a plurality of elliptical openings
extending therethrough in accordance with the present
invention;
[0033] FIG. 8 is a perspective view of a pentagonal shaped ceramic
filter unit having a plurality of elliptical openings extending
therethrough in accordance with the present invention;
[0034] FIG. 9 is a perspective view of a hexagonal shaped ceramic
filter unit having a plurality of elliptical openings extending
therethrough in accordance with the present invention;
[0035] FIG. 10 is a perspective view of a heptagonal shaped ceramic
filter unit having a plurality of elliptical openings extending
therethrough in accordance with the present invention;
[0036] FIG. 11 is a perspective view of an octagonal shaped ceramic
filter unit having a plurality of elliptical openings extending
therethrough in accordance with the present invention;
[0037] FIG. 12 is a perspective view of an elliptical shaped
ceramic filter unit having a plurality of elliptical openings
extending therethrough in accordance with the present invention;
and
[0038] FIG. 13 is a perspective view of a square shaped ceramic
filter unit having a plurality of elliptical openings extending
therethrough in accordance with the present invention.
[0039] FIG. 14 is a perspective view of a circular shaped ceramic
filter unit having a plurality of trisoidal openings extending
therethrough in accordance with the present invention.
[0040] FIG. 15 is a side view, taken along the cross-section A-A of
FIG. 4, showing a ceramic filter unit having substantially smooth
top and bottom surfaces.
[0041] FIG. 16 is a side view, taken along the cross-section A-A of
FIG. 4, showing a ceramic filter unit having irregularly shaped top
and bottom surfaces.
[0042] While the invention will be described in connection with the
preferred embodiment, it will be understood that it is not intended
to limit the invention to that embodiment. On the contrary, it is
intended to cover all alternatives, modifications, and equivalents,
as may be included within the spirit and the scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION AND SPECIFIC EMBODIMENTS
[0043] With reference to FIG. 1, unless otherwise noted, for
treatment of an organic-based feed stream, a single fixed bed
chemical reactor 22 is shown. If the reactor 22 is of a downflow
configuration, the contaminated organic-based feed stream 20 will
enter the reactor 22 at the inlet 24 and exit the outlet 44 as
stream 38. The invention may be used in fixed bed chemical
reactors. Preferably, the present invention is used in one or more
fixed beds, in either an upflow or downflow or radial flow
configuration. As used herein, the term "chemical reactors" may
include hydrotreaters, hydrorefiners, hydrocrackers, reformers,
alkylation, isomerization and polymerization reactors, among
others. Contaminants typically found in the feed stream include
dirt, iron oxide, iron sulfide, asphaltenes, coke fines, catalyst
fines, sediments or other entrained foreign particulate
material.
[0044] Still with reference to FIG. 1, a layer of ceramic filter
units 15 (FIGS. 4-16), at least some having a plurality of openings
89 extending therethrough, at least some of the openings having a
shape selected from the group consisting of ellipses 88 (FIG. 4-5)
or trisoids 87 (FIG. 14). A layer 26, preferably layers 26, 28, of
ceramic filter units 15, wherein at least some of the ceramic
filter units have a plurality of elliptical shaped openings 88
(FIGS. 4-5) or trisoidal shaped openings 87 (FIG. 14) is provided
in the reactor, or vessel, 22 in an amount sufficient to filter the
contaminants from the organic-based feed stream 20. Optionally, the
number or size of elliptical shaped openings 88 (FIGS. 4-5),
trisoidal shaped openings 87 (FIG. 14) or other shaped openings 108
(FIGS. 4-5) may be varied to change the void fraction of the
ceramic filter units 15.
[0045] Optionally, but preferably, the size, shape and thickness of
the ceramic filter units may also be varied to change the packing
factor for the layer of ceramic filter units 26. As illustrated in
FIG. 1, multiple layers 26, 28 may be provided wherein the packing
factor of layer of ceramic filter units 26, 28 is graduated from a
low value (larger void volume) in layer 26 to a higher value
(smaller void volume) in layer 28 as the incoming organic-based
feed stream flows through the ceramic filter units 15. The packing
factors of the layers 26, 28 of ceramic filter units 15 may be
graduated from a smaller packing factor to a larger packing factor
to lessen the pressure drop through the reactor attributable to
filtering of the suspended solids. Optionally, the present
invention may be practiced with or without conventional basket
screens 30.
[0046] The ceramic filter units 15 may be made from any
commercially available ceramic precursors fire clays for example,
ball clays or silicate-aluminum clays such as montmorillonite or
preferably kaolinite clays such as those found in the Southeastern
United States. Optionally, ceramic precursors such as cordierite,
mullite, magnesia aluminia, zirconia stabilized with magnesia or
calcia, zirconia toughened alumina, and the like may also be
used.
[0047] Still with reference to FIG. 1, in addition to filtering the
contaminated organic-based feed stream 20, the ceramic filter units
15 may also enable a uniform distribution and flow of the incoming
organic-based feed stream 20 to the catalyst bed 32. The incoming
organic-based feed stream 20 may be distributed by passing the
organic-based feed stream through a plurality of flow passageways
87, 88, 89, 108 (FIGS. 4, 5, 14). The flow passageways 87, 88, 89,
108 (FIGS. 4, 5, 14) are defined by the elliptical shaped openings
88 (FIG. 4), trisoidal shaped openings 87 (FIG. 14) or optionally,
other shapes, such as circular openings 108 (FIGS. 4-5) extending
through the ceramic filter units 15. Preferably, the openings 89
(FIGS. 4, 5, 14) extend axially through the ceramic filter units
along their longitudinal axis. The layers 26, 28, of ceramic filter
units 15 distribute the incoming organic-based feed stream 20 into
a plurality of smaller fluid streams by resubdividing, a plurality
of times, the smaller streams so that the incoming organic-based
feed stream 20 is spread across the fluid entry cross section 34,
taken along line 34-34, of the catalyst bed 32.
[0048] The organic-based feed stream 20 is reacted in the catalyst
bed 32. Preferably the catalyst bed 32 contains discrete solid
catalyst particles 36. Alternately, the filtering medium, or
ceramic filter units, 15 may also be used in an upflow reactor
configuration wherein the contaminated organic-based feed 46 would
instead enter the vessel at the outlet 44 at the lower end 39 and
the reacted organic-based stream 25 would exit the reactor at the
inlet 24 at the upper end 47 of reactor 22.
[0049] As previously discussed, another advantage of the present
invention is to react partially activated or activated ceramic
filter units 15 with polymer precursors in a contaminated
organic-based feed stream 20. Condensation polymerization of
diolefins may occur in the reactor bed 32 after the contaminated
organic-based feed stream 20 is heated, generally prior to
introduction into the chemical reactor 22, thereby forming foulants
in the reactor bed 32 itself which may gum or plug the bed 32. As
the foulants form in the bed, they cannot be filtered from the
contaminated organic-based feed stream 20 before flowing across the
fluid entry cross section 34. Therefore, the layer or layers 26, 28
of ceramic filter units 15 may be coated with an alumina powder
that may also act as a substrate for catalyst materials to form
activated ceramic filter units 15.
[0050] As used herein, an "activated support" means: a ceramic
filter unit 15, having at least some elliptical shaped openings 88
(FIGS. 4-5) or trisoidal shaped openings 87 (FIG. 14), which has
been impregnated with catalyst materials; a ceramic filter unit 15
having at least some elliptical shaped openings 88 (FIGS. 4-5), or
trisoidal shaped openings 87 (FIG. 14), which may contain an oxide,
nitride, or carbide of a metal; or a ceramic filter unit 15 having
at least some elliptical shaped openings 88 (FIGS. 4-5), or
trisoidal shaped openings 87 (FIG. 14), which contains zeolite or
porous inorganic oxides, e.g., alumina, silica, silica-alumina,
magnesia, silica-magnesia or titania. As used herein, a "partially
activated support" means an activated support material that has
been purposefully made less active, or partially deactivated, in
order to achieve a slower reaction rate or to partially react the
materials contacted.
[0051] Coated ceramic filter units 15 may also be used, wherein the
coating may comprise one of several conventional catalysts. Alumina
may be used as an active coating. Preferably, alumina may be used
as a support. The catalyst according to this invention preferably
comprises a metal of Group VI-B or a member of Group VIII, or both,
impregnated into an alumina-based support. Accordingly, the
catalyst may comprise at least one of chromium, molybdenum and
tungsten in combination with at least one of iron, nickel, cobalt,
platinum, palladium and iridium. Of the Group VI-B metals,
molybdenum is most preferred. The catalyst preferably will contain
from about 2% to about 14% by weight of Group VI-B metal. Of the
Group VIII metals, nickel and cobalt are most preferred. The amount
of Group VIII metal in the catalyst is preferably from about 0.5%
to about 10% by weight.
[0052] With reference to FIG. 2, a multiple fixed bed chemical
reactor 49 having two fixed catalyst beds 48, 50 with ceramic
filter units 15 will be described. The reactor 49 is illustrated in
a downflow configuration, wherein the contaminated organic-based
feed stream 51 will enter the reactor 49 at the inlet 52 and the
reacted organic-based stream 54 will exit the reactor at the
outlets 56, 61. A partially reacted organic-based stream 58 may be
accumulated at the outlet 61 of the first fixed bed 48 and
withdrawn at the collector tray 60. The partially reacted
organic-based stream 58 may be heated or quenched or otherwise
treated before reintroduction into the reactor 49 as a partially
reacted organic-based feed stream 62 at the mixing chamber 64. The
partially reacted organic-based stream 58 may be removed for
redistribution, heating, or other processing steps as required
before reintroducing the partially reacted organic-based feed
stream 62 into the reactor 49 for reaction with a succeeding
catalyst bed 50. An additional layer 70 of ceramic filter units 15
having at least some elliptical shaped openings 88 (FIGS. 4-5), or
trisoidal shaped openings 87 (FIG. 14), may be provided for
filtration and distribution to remove any contaminants entrained
from or formed by the processing equipment used in the additional
processing steps such as dirt, iron oxide, iron sulfide,
asphaltenes, coke fines, catalyst fines, sediments, or other
entrained foreign particulate material. The reacted stream 54 exits
the lower end 42 of the reactor 49 at the outlet 56.
[0053] Layers 66, 68, 70 of ceramic filter units 15 are provided in
the reactor 49 below the inlet 52 and mixing chamber 64 in an
amount sufficient to filter the organic-based feed stream 51 and
the partially reacted organic-based feed stream 62. Optionally, the
size, shape and thickness of the cross sections may also be varied
to change the packing factor for the layers 66, 68 of ceramic
filter units 15. Multiple layers may be provided wherein the
packing factor of the layered ceramic filter units 66, 68 is
graduated from a low value (larger void volume) in layer 66 to a
higher value (smaller void volume) in layer 68 as the incoming
organic-based feed stream flows through the ceramic filter units
15. Optionally, the present invention may be practiced with, or
without, conventional basket screens 72. Preferably, the fixed
catalyst beds 48, 50 contain discrete solid catalyst particles
74.
[0054] As previously discussed, an advantage of the present
invention is that it may also be used to distribute the
organic-based feed stream. The organic-based feed stream 51 may
also be distributed while being filtered by subdividing the
incoming organic-based, feed into a plurality of smaller fluid
streams. The organic-based feed stream 51 may be distributed or
spread across the fluid entry cross section of the catalyst bed 76
by passing the organic-based feed stream 51 through a layer 66 or
layers 66, 68 of ceramic filter units 15. The ceramic filters 15
resubdivide, a plurality of times, the smaller streams in a
plurality of flow passageways 87, 88, 89, 108 (FIGS. 4, 5, 14). The
organic-based feed 51 is then reacted in the catalyst bed 48,
before being withdrawn as a partially reacted organic-based stream
58 at the collector plate 60. The method of filtration and
distribution is then repeated for the partially reacted
organic-based feed stream 62 as it flows into the mixing chamber 64
and passes through the ceramic filter units layer 70.
[0055] A further advantage of the present invention is that at
least some of the ceramic filter units 15 may be activated or
impregnated with catalyst to react with polymer precursors in
organic-based feed streams 51, 62. As depicted in FIG. 2, layers
66, 68, 70 of ceramic filter units 15 at least some of the ceramic
filter units having a plurality of openings 89 extending
therethrough, at least some of the opening having a shape selected
from the group consisting of ellipses 88 (FIGS. 4-5), or trisoids
87 (FIG. 14), may contain an activated support including porous
inorganic oxides preferably selected from the group consisting of
alumina, silica, silica-alumina, magnesia, silica-magnesia or
titania or zeolites. The zeolites are preferably selected from the
group consisting of zeolite L, zeolite X, and zeolite Y, which may
be added to the ceramic filter units 15 as a substrate for catalyst
materials. Optionally, the ceramic filter units 15 may be
impregnated with catalyst materials which may be an oxide, nitride,
carbide or boride of a metal as disclosed in U.S. Pat. No.
5,399,535, which is hereby incorporated by reference to the extent
it is not inconsistent with the present invention.
[0056] Activated, or partially activated, ceramic filter units 15
may be used to control the hydrogenation rate of the diolefins or
other polymer precursors to prevent fouling or gum formation. When
endothermic reactions require the addition of heat to the partially
reacted organic-based stream 58, preferably the layer 70 of ceramic
filter units 15 is also activated or partially activated. The
invention may also be practiced with at least some coated ceramic
filter units 15, wherein the coating may comprise one of several
conventional catalysts. Alumina may be used on an active coating or
support. The catalyst according to this invention preferably
comprises a metal of Group VI-B or a member of Group VIII, or both,
impregnated into the active coating or support on the ceramic
filter units 15. Accordingly, the catalyst may comprise at least
one of chromium, molybdenum and tungsten in combination with at
least one of iron, nickel, cobalt, platinum, palladium and iridium.
Of the Group VI-B metals, molybdenum is most preferred. The
catalyst preferably will contain from about 2% to about 14% by
weight of Group VI-B metal. Of the Group VIII metals, nickel and
cobalt are most preferred. The amount of Group VIII metal in the
catalyst is preferably from about 0.5% to about 10% by weight. More
preferably, the Group VI-B metal and Group VIII metal are
impregnated directly into the ceramic filter units.
[0057] With reference to FIG. 3, for treatment of a contaminated
organic-based feed in vapor form, a radial flow fixed bed chemical
reactor 40 is illustrated. The contaminated organic-based feed in
vapor form 84 will enter the radial flow reactor 40 at the inlet
85. A layer 78 of ceramic filter units 15, more preferably layers
78, 80 of ceramic filter units 15, is provided in the reactor, or
vessel 40, between a deflection baffle 116 and the scallop 114. The
layers 78, 80 of ceramic filter units 15 aid in filtering
contaminants such as entrained dirt, iron oxide, iron sulfide,
asphaltenes, coke fines, catalyst fines, sediments, or other
foreign particulate material entrained in the contaminated
organic-based vapor feed 84. Following filtration, the vapor is
reacted in the fixed catalyst bed 128. The reacted organic stream
126 is discharged through the center pipe 120.
[0058] FIGS. 4 and 5 illustrate a specific embodiment of the
present invention as a ceramic filter unit 15 having a circular
shape, or cross-sectional configuration, 86 and at least some
elliptical shaped openings 88 (FIGS. 4-5). Trisoidal shaped
openings 87 may also be used (FIG. 14). Optionally, the ceramic
filter units 15 may have other shaped openings 108 mixed with the
elliptical shaped openings 88 (FIGS. 4-5) or the trisoidal shaped
openings 87 (FIG. 14). The other shaped openings may have a
circular shape, as illustrated in FIGS. 4-5 or may be irregular or
other closed plane shapes, such as squares, clover leaves, or
diamonds, among others. Optionally, the periphery surface of the
ceramic filter units 15 may be smooth as shown by arrow 98 (FIG. 4)
or be provided with flutes, or grooves, 102 (FIG. 5). As to the
ceramic filter units 15 of FIGS. 4 and 5, although four openings 88
disposed about a circular shaped opening 108 are shown, it will be
apparent to one of ordinary skill in the art that a greater, or
smaller, number of openings 88 may be provided. For example, three
openings 88 or five openings 88, could be utilized.
[0059] With reference to FIG. 15, the top surface 105 and bottom
surface 107 of the ceramic filter units 15 may also be used to
contact solid particles and effectively remove the entrained solids
by reducing the particle velocity below that of the fluid.
Irregularly shaped top and bottom surfaces 105, 107 (FIG. 16) may
augment this process. The amplitude and length of the ridges,
rounded beads of waves may be adjusted based upon the particle
sizes, fluid velocity and viscosity.
[0060] Other cross-sectional configurations used for the ceramic
filter units may include triangles 94 (FIG. 6), quadrilaterals 96
(FIG. 7), pentagons 104 (FIG. 8), hexagons 110 (FIG. 9), heptagons
100 (FIG. 10), octagons 106 (FIG. 11), ellipses 92 (FIG. 12), and
squares 90 (FIG. 13), among others. Each shape may be sized to
individual specifications. Sizes for the shapes used may include
circular shapes of about 1/4 to 3 inches in diameter; elliptical
shapes with major axes of about 1/4 to 2 inches and minor axes of
about 3/8 to 3 inches; and polygonal shapes with individual sides
of the polygon of about 1/8 to 3 inches.
[0061] It is to be understood that the invention is not to be
limited to the exact details of construction, operation, exact
materials, or embodiments shown and described, as obvious
modifications and equivalents will be apparent to one skilled in
the art. For example, a non-uniform thickness cross section could
be utilized rather than a uniform thickness for decreasing the
packing factor, if desired. Accordingly, the invention is therefore
to be limited only by the scope of the appended claims.
* * * * *