U.S. patent application number 10/834152 was filed with the patent office on 2004-10-14 for method for reducing the maximum water concentration in a multi-phase column reactor.
This patent application is currently assigned to ConocoPhillips Company. Invention is credited to Espinoza, Rafael L., Mohedas, Sergio R., Ortego, Beatrice C., Zhang, Jianping.
Application Number | 20040204508 10/834152 |
Document ID | / |
Family ID | 30114501 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040204508 |
Kind Code |
A1 |
Zhang, Jianping ; et
al. |
October 14, 2004 |
Method for reducing the maximum water concentration in a
multi-phase column reactor
Abstract
The present invention relates to a method and apparatus for
reducing the maximum water concentration in multi-phase reactors
operating at Fischer-Tropsch conditions. In a preferred embodiment
of the present invention, a method of reducing the maximum
concentration of water in a multi-phase reactor containing an
expanded slurry bed and a water-rich slurry region for
Fisher-Tropsch synthesis includes changing the flow structure of a
predetermined region in the reactor. The flow structure may be
changed by introducing a mixing enhancing fluid into the
predetermined region, installing baffles into the predetermined
region, or by other methods known in the art. Preferably the
predetermined region is located between 1/2 H and H and between 1/2
R and R, where H is the height of the expanded slurry bed and R is
the radius of the reactor.
Inventors: |
Zhang, Jianping; (Ponca
City, OK) ; Espinoza, Rafael L.; (Ponca City, OK)
; Mohedas, Sergio R.; (Ponca City, OK) ; Ortego,
Beatrice C.; (Ponca City, OK) |
Correspondence
Address: |
DAVID W. WESTPHAL
CONOCOPHILLIPS COMPANY
P.O. BOX 1267
PONCA CITY
OK
74602-1267
US
|
Assignee: |
ConocoPhillips Company
Houston
TX
|
Family ID: |
30114501 |
Appl. No.: |
10/834152 |
Filed: |
April 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10834152 |
Apr 28, 2004 |
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10193357 |
Jul 11, 2002 |
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10834152 |
Apr 28, 2004 |
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10034452 |
Dec 28, 2001 |
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6720358 |
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60344228 |
Dec 28, 2001 |
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60344229 |
Dec 28, 2001 |
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Current U.S.
Class: |
518/726 |
Current CPC
Class: |
B01J 8/22 20130101; C10G
2/342 20130101; B01F 33/406 20220101 |
Class at
Publication: |
518/726 |
International
Class: |
C07C 027/26 |
Claims
What is claimed is:
1. A Fischer-Tropsch reactor system, comprising: a slurry bed
reactor receiving a synthesis gas feed and containing a hydrocarbon
synthesis catalyst, said catalyst forming an expanded slurry bed
under reaction conditions effective to form a product stream
comprising hydrocarbons and water; and means for changing the flow
pattern within the reactor so as to cause mixing of slurry from a
predetermined region within the reactor with fluids from the rest
of the slurry bed.
2. The reactor system according to claim 1 wherein said
predetermined region is located between 1/2 H and H and between 1/2
R and R, where H is the height of the expanded slurry bed and R is
the radius of the reactor.
3. The reactor system according to claim 1 wherein said
predetermined region is located between 3/4 H and H and between 3/4
R and R.
4. The reactor system according to claim 1, further comprising a
fluid inlet in said predetermined region.
5. The reactor system according to claim 1 wherein said flow
changing means comprises an inlet for introducing a mixing
enhancing fluid into said predetermined region.
6. The reactor system according to claim 5 wherein the mixing
enhancing fluid is a gas or gas mixture selected from the group
comprising synthesis gas, inert gas, methane-rich gas, light
hydrocarbons, hydrogen containing gas, tail gas from a
Fischer-Tropsch reactor, tail gas from a GTL plant, tail gas from
an olefin plant, liquids vaporizing at operating conditions, and
combinations thereof.
7. The reactor system according to claim 5 wherein the mixing
enhancing fluid is a liquid that comprises liquid hydrocarbons from
the product stream of the Fischer-Tropsch reactor or from other
processes in a Gas-to-Liquids plant.
8. The reactor system according to claim 5 wherein said flow
changing means comprises at least one mixing enhancing fluid
distributor.
9. The reactor system according to claim 8 wherein the said mixing
enhancing fluid distributor comprises an annular ring having at
least one outlet port.
10. The reactor system according to claim 8 wherein a plurality of
mixing enhancing fluid distributors are positioned at different
heights in said predetermined region.
11. The reactor system according to claim 8 wherein a plurality of
mixing enhancing fluid distributors are positioned at different
radial positions in said water-rich slurry region.
12. The reactor system according to claim 5 wherein the mixing
enhancing fluid is introduced into said predetermined region
through at least one nozzle.
13. The reactor system according to claim 12 wherein said nozzles
are positioned at different heights in the water-rich slurry
region.
14. The reactor system according to claim 12 wherein said nozzles
are positioned at different radial positions in the water-rich
slurry region.
15. The reactor system according to claim 1 wherein said flow
changing means comprises at least one static mixing device in said
predetermined region.
16. The reactor system according to claim 1 wherein said flow
changing means comprises at least one passive movable device in
said predetermined region.
17. The reactor system according to claim 1 wherein said flow
changing means comprises at least one power-driven device in said
predetermined region.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 10/193,357. filed Jul. 11, 2002, entitled
Method for Reducing the Maximum Water Concentration in Multi-Phase
Column Reactor, which is related to commonly assigned, co-pending
U.S. Provisional Applications Serial No. 60/344,228, filed Dec. 28,
2001 and entitled "Method for Reducing Water Concentration in a
Multi-phase Column Reactor," Ser. No. 60/344,229, filed Dec. 28,
2001 and entitled Water Removal In Fischer-Tropsch Processes, and
Ser. No. 10/034,452, filed Dec. 28, 2001 and entitled Water
Stripping and Catalyst/Liquid Product Separation System, all of
which are hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for the
preparation of hydrocarbons from synthesis gas, i.e., a mixture of
carbon monoxide and hydrogen, typically labeled the Fischer-Tropsch
process. Particularly, this invention relates to a method for
reducing the maximum water concentration in multi-phase column
reactors operating at Fischer-Tropsch conditions.
BACKGROUND OF THE INVENTION
[0003] Large quantities of methane, the main component of natural
gas, are available in many areas of the world, and natural gas is
predicted to outlast oil reserves by a significant margin. However,
most natural gas is situated in areas that are geographically
remote from population and industrial centers. The costs of
compression, transportation, and storage make its use economically
unattractive. To improve the economics of natural gas use, much
research has focused on the use of methane as a starting material
for the production of higher hydrocarbons and hydrocarbon liquids,
which are more easily transported and thus more economical. The
conversion of methane to hydrocarbons is typically carried out in
two steps. In the first step, methane is converted into a mixture
of carbon monoxide and hydrogen (i.e., synthesis gas or syngas). In
a second step, the syngas is converted into useful
hydrocarbons.
[0004] This second step, the preparation of hydrocarbons from
synthesis gas, is well known in the art and is usually referred to
as Fischer-Tropsch synthesis, the Fischer-Tropsch process, or
Fischer-Tropsch reaction(s). Fischer-Tropsch synthesis generally
entails contacting a stream of synthesis gas with a catalyst under
temperature and pressure conditions that allow the synthesis gas to
react and form hydrocarbons.
[0005] More specifically, the Fischer-Tropsch reaction is the
catalytic hydrogenation of carbon monoxide to produce any of a
variety of products ranging from methane to higher alkanes,
olefins, and aliphatic alcohols. Research continues on the
development of more efficient Fischer-Tropsch catalyst systems and
reaction systems that increase the selectivity for high-value
hydrocarbons in the Fischer-Tropsch product stream.
[0006] There are continuing efforts to design reactors that are
more effective at producing these desired products. Product
distribution, product selectivity, and reactor productivity depend
heavily on the type and structure of the catalyst and on the
reactor type and operating conditions. Catalysts for use in such
synthesis usually contain a catalytically active metal of Groups 8,
9, or 10 (in the New notation of the periodic table of the
elements, which is followed throughout). In particular, iron,
cobalt, nickel, and ruthenium have been abundantly used as the
catalytically active metals. Cobalt and ruthenium have been found
to be most suitable for catalyzing a process in which synthesis gas
is converted primarily to hydrocarbons having five or more carbon
atoms (i.e., where the C.sub.5+ selectivity of the catalyst is
high).
[0007] Originally, the Fischer-Tropsch synthesis was operated in
packed bed reactors. These reactors have several drawbacks, such as
difficulty of temperature control, that can be overcome by using
gas-agitated slurry reactors or slurry bubble column reactors.
Gas-agitated reactors, sometimes called "slurry reactors," "slurry
bubble columns," or "multi-phase reactors" operate by suspending
catalytic particles in liquid and feeding gas reactants into the
bottom of the reactor through a gas distributor, which produces
small gas bubbles. As the gas bubbles rise through the reactor, the
reactants are absorbed into the liquid and diffuse to the catalyst
where, depending on the catalyst system, they are converted to
gaseous and/or liquid products. If gaseous products are formed,
they enter the gas bubbles and are collected at the top of the
reactor. Liquid products are recovered from the suspended solid
using any suitable technique, such as settling, filtration,
magnetic separation, hydrocycloning, or the like, and then
separating the liquids.
[0008] A known problem in multi-phase reactors, however, is that
water is continuously formed during Fisher-Tropsch synthesis in the
reactors. The presence of water limits conversion and prematurely
deactivates catalyst systems such as iron and cobalt-based
Fisher-Tropsch catalysts [e.g., Schanke et al., Catalysis Letter 34
(1995) 269; Hilnen et al., Applied Catalysis, 186 (1999) 169; van
Berge et al., Catalysis Today, 58 (2000) 321). Thus, a high water
partial pressure correlates to a high deactivation rate. In
addition, it is believed that above a certain partial pressure of
water, the catalyst deactivates faster. For example, some have
observed that partial pressures of water above about 6 bar
deactivate certain Fischer-Tropsch catalysts, while partial
pressures of water below that level do not [Schanke et al., Energy
& Fuels, 10 (1997) 867]. It is further believed that the
relationship between deactivation rate and water concentration may
have one or more thresholds, between which the relationship may or
may not be linear. Furthermore, the relationship between
deactivation rate and water concentration may depend on other
physical parameters of the system. Regardless of the precise nature
of the relationship, it is believed that reducing reactor water
concentration would reduce the rate of catalyst deactivation.
[0009] For any given cobalt-based catalyst, along with the
H.sub.2/CO ratio and the reaction temperature, the total pressure
has a direct influence on the wax selectivity, in that a higher
pressure will result in a higher wax selectivity. However, a higher
total pressure (at any given degree of per-pass conversion) also
correlates to a higher water partial pressure and therefore a
higher deactivation rate. Therefore, if reactors are operated at
conditions that are conducive to higher alpha values, per-pass
conversion will necessarily have to be low to avoid premature
catalyst deactivation due to water. A low per-pass conversion is
undesirable, however, because it results in higher capital
investment and operating costs. Additionally, for iron-based
catalysts, the water not only has a negative effect on the catalyst
deactivation rate, but it also inhibits the rate of reaction (see
for example, Kirillov, V. A. et al., in Natural Gas Conversion V,
Studies in Surface Science and Catalysis, vol. 119, A. Parmaliana
et al., ed., Elsevier Science, New York, pp. 149-154, 1998).
[0010] The water partial pressure is therefore a constraint that
prevents the realization of the kinetic and/or wax selectivity
potential of iron and cobalt-based Fisher-Tropsch catalysts.
Therefore, in order to improve the efficiency of multi-phase
reactors using iron and cobalt-based catalyst systems, there exists
a need for a method to reduce the maximum water concentration
reached in the system during Fisher-Tropsch synthesis.
SUMMARY OF THE INVENTION
[0011] The present invention relates to a method for reducing the
maximum water concentration in multi-phase reactors operating at
Fischer-Tropsch conditions. More particularly, the present
invention is based on the recognition of a high water concentration
region and alteration of the flow patterns within the reactor in
order to reduce the maximum water concentration in the reactor.
This method increases the catalyst lifetime, thereby reducing the
operating cost of the Fischer-Tropsch process.
[0012] In a preferred embodiment of the present invention, a method
of reducing the maximum concentration of water in a multi-phase
reactor containing an expanded slurry bed and a water-rich slurry
region for Fisher-Tropsch synthesis includes changing the flow
patterns of the fluids within the reactor and/or diluting the water
concentration in the high water concentration region. More
precisely, flow patterns are modified so as to cause a mixing of
fluids from a water-rich region in the reactor with fluids in the
rest of the reactor. The flow patterns may be changed by
introducing a mixing enhancing fluid into the predetermined region,
installing baffles into the predetermined region, or the
combination of the two, or by other mechanical mixing methods known
in the art. The introduction of the mixing enhancing fluid can also
lead to a dilution of the water concentration in the predetermined
region. In some reactors, the water-rich region is located between
1/2 H and H and between 1/2 R and R, where H is the height of the
expanded slurry bed and R is the radius of the reactor. The
expanded slurry bed is herein defined as the region within a
reactor where an intimate liquid-solid-gas phase contact exists.
The flow patterns are preferably changed or disrupted so that the
difference between the highest water concentration in the reactor
and the lowest water concentration in the reactor is minimized.
[0013] The present invention allows higher per-pass conversions of
syngas and/or use of higher total pressures at any degree of
conversion, while protecting the Fischer-Tropsch catalyst from an
excessive oxidation rate.
BRIEF DESCRIPTION OF THE FIGURES
[0014] A better understanding of the present invention can be
obtained when the following detailed description of the preferred
embodiment is considered in conjunction with the following
drawings, wherein:
[0015] FIG. 1 is a contour diagram of the water concentration in
the liquid phase in a multi-phase reactor operating at
Fischer-Tropsch conditions;
[0016] FIG. 2 is a plot of radial profiles of the dimensionless
water concentration at four elevations along the expanded slurry
bed;
[0017] FIG. 3 is a schematic cross-sectional side view of a
multi-phase reactor constructed in accordance with a preferred
embodiment of the present invention;
[0018] FIG. 4 is a schematic top view of an annular or toroidal
fluid distributor in accordance with a preferred embodiment of the
present invention;
[0019] FIG. 5 is a schematic cross-sectional side view of a
multi-phase reactor system in accordance with an alternative
embodiment of the present invention;
[0020] FIG. 6 is a schematic cross-sectional side view of a series
of nozzles flush mounted on or protruding from the reactor wall in
accordance with another preferred embodiment;
[0021] FIG. 7 is a schematic top view of a series of nozzles flush
mounted on or protruding from the reactor wall in accordance with
another preferred embodiment;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] In typical Fischer-Tropsch processes, water begins to
accumulate unevenly in the operating reactor, forming a water-rich
slurry region. As mentioned above, this is undesirable because
water has a negative effect on the catalyst deactivation rate and
inhibits the rate of reaction. To minimize this problem, the
present invention changes the fluid flow patterns such that slurry
from a water-rich region is mixed with slurry from regions having
lower water concentrations. This effectively reduces the maximum
water concentration in the reactor, thereby reducing the catalyst
deactivation rate in the reactor.
[0023] Referring initially to FIG. 1, a contour of water
concentration in the liquid phase in an exemplary multi-phase 100
reactor operating at Fischer-Tropsch conditions is shown. The
values of water concentration are color coded, where red indicates
a high water concentration and blue indicates a low water
concentration region. The water concentration distribution in the
reactor is further illustrated in FIG. 2, wherein the radial
profiles of the dimensionless water concentration are shown at four
elevations along the expanded slurry bed. The dimensionless water
concentration is defined as the local water concentration divided
by the average water concentration of the whole reactor. As shown
in FIGS. 1 and 2, the water concentration in the near wall region
at the upper half of the expanded slurry bed in the reactor is
significantly higher than in other regions in the reactor. More
specifically, if the expanded slurry bed is defined as having a
height H and a radius R, the high water concentration tends to be
located radially between approximately 0.5R and R and vertically
between approximately 0.5H and H, in the region labeled 101. Still
more specifically, the high water concentration is located radially
between approximately 0.75R and R, and still more specifically
between approximately 0.75R and 0.875R, and vertically between
approximately 0.75H and H, with the highest concentrations being in
region 103.
[0024] Referring now to FIGS. 3 and 4, in one embodiment of the
invention, a mixing enhancing fluid distributor 102 is included in
the reactor. The mixing enhancing fluid distributor 102 preferably,
but not necessarily, comprises an annular or toroidal ring 104
having output ports 106 and a feed line 108. Ports 106 are
preferably but not necessarily uniformly distributed on ring 104.
In one preferred embodiment, output ports 106 feed a mixing
enhancing fluid into the high water concentration region, i.e. the
mixing enhancing fluid distributor 102 is positioned in the slurry
between approximately 0.5R and R and between approximately 0.5H and
H. Still more specifically, the mixing enhancing fluid distributor
102 is positioned radially between approximately 0.75R and R and
still more preferably between 0.75R and 0.875R, and vertically
between approximately 0.75H and H. The mixing enhancing fluid can
be gas, or liquid, or gas and liquid mixtures. The mixing enhancing
gas can be synthesis gas, inert gas, methane-rich gas, light
hydrocarbons, hydrogen containing gas, tail gas from a
Fischer-Tropsch reactor, tail gas from a GTL plant, tail gas from
an olefin plant, liquids vaporizing at operating conditions, or a
combination thereof. The synthesis gas can comprise a mixture of
hydrogen and carbon monoxide having a hydrogen-to-carbon monoxide
ratio that is the same as, lower, or higher than that of the feed
to the reactor. Alternatively, the mixing enhancing gas can be a
stream from a tail gas from other processes in a Gas-to-Liquids
plant, including without limitation: hydrotreating, hydrocracking,
or olefin production plants. The mixing enhancing liquid can be
liquid hydrocarbons from the product streams of the Fischer-Tropsch
reactor or from other processes in a Gas-to-Liquids plant.
[0025] Output ports 106 are preferably but not necessarily
uniformly distributed around the circumference of the mixing
enhancing fluid distributor 102, so that the flow of the mixing
enhancing fluid into the high water concentration region disrupts
or shifts the pattern of slurry flow within the reactor. Thus, it
may also be desired to provide at least one, more preferably at
least four, and still more preferably at least eight output ports
106. Further, in some embodiments, it may be preferred to provide a
plurality of mixing enhancing fluid distributors 102 positioned at
different heights and/or different radial positions within the
reactor, preferably but not necessarily between approximately 0.5R
and R and between approximately 0.5H and H, more preferably between
approximately 0.75R and R and between approximately 0.75H and
H.
[0026] It is preferred that the degree of mixing attained be
sufficient to distribute the water present in the reactor evenly
throughout the reactor. More precisely, it is preferred that the
degree of mixing be such that the highest water concentration in
the reactor is no more than 50% greater than the average water
concentration in the reactor. It is still more preferred that the
highest water concentration in the reactor be no more than 20%
greater than the average water concentration in the reactor, and
most preferred that the highest concentration be less than 10%
greater than the lowest. In the embodiment shown in FIG. 3, the
rate of flow of gas or liquid or the gas and liquid mixtures
through mixing enhancing fluid distributor 102 is preferably
sufficient to cause the desired degree of mixing.
[0027] Referring now to FIG. 5, in another preferred embodiment,
one or more passive mixing devices, such as baffle plates 112, is
positioned in the slurry between approximately 0.5R and R and
between approximately 0.5H and H. The passive mixing device(s)
is/are positioned between approximately 0.75R and R and between
approximately 0.75H and H. Similarly to the mixing enhancing fluid
distributor 102, the passive mixing device disrupts or shifts the
pattern of slurry flow within the reactor, which in turn, reduces
the maximum water concentration in the reactor.
[0028] Alternatively, baffle plates 112, which are static, can be
replaced with one or more passive but movable devices, such as
non-driven paddles (not shown), or with one or more powered mixing
devices, such as power-driven paddles (not shown) or magnetic
mixing devices (not shown).
[0029] In another preferred embodiment of the invention, shown in
FIGS. 6 and 7, the mixing enhancing fluid is introduced into the
high water concentration region through a series of flush mounted
nozzles 207 or protruding nozzles 206. The number of nozzles is
preferably at least one, more preferably at least four, and still
more preferably at least eight. If two or more nozzles are used, it
is preferred that they be evenly distributed around the
circumference of the reactor. It may be preferred to provide a
plurality of mixing enhancing fluid nozzles positioned at different
heights and/or different radial positions within the reactor
between approximately 0.5R and R and between approximately 0.5H and
H, more preferably between approximately 0.75R and R and between
approximately 0.75H and H.
[0030] It will be understood that the configurations of either the
mixing enhancing fluid distributor 102, nozzles 206, 207, or the
baffle plates 112 or a combination thereof may be modified
significantly without departing from the scope of the invention.
More specifically, any method of disrupting the flow patterns that
cause a localized concentration of water is contemplated. These
include both powered and non-powered (static) mechanical devices,
such as baffles 112, fins, paddles, magnetically driven mixing
devices, and fluid devices such as gas or liquid distributor 102,
nozzles 206, 207, and the like.
[0031] It is further contemplated that in some cases it may be
desirable to remove water from the reactor in order to reduce the
total water concentration in the reactor. Any suitable water
removal means (i.e. separation methods) may be employed to remove
water from the water-rich slurry region. Some of the water removal
means may be incorporated into the multi-phase reactor itself,
while others may be independent of the reactor and utilize a slurry
transport means. It is contemplated that in cases where the water
removal means is independent of the reactor, gas-disengaging means
may be utilized between the reactor and the water removal means to
ease separation. In addition, different water removal means may be
combined with each other in various arrangements to increase the
efficiency of overall water removal. Preferred separation methods
include separation by phase addition or creation, separation by
barrier, separation by solid agent, and separation by external
field or gradient. Separation methods are disclosed in greater
detail in the co-pending U.S. patent applications cited above. Ser.
No. 60/344,229, filed Dec. 28, 2001 and entitled "Water Removal in
Fischer-Tropsch Processes," which is incorporated herein by
reference.
[0032] Fischer-Tropsch Operating Conditions
[0033] The feed gases charged to the process of the preferred
embodiment of the present invention comprise hydrogen, or a
hydrogen source, and carbon monoxide. H.sub.2/CO mixtures suitable
as a feedstock for conversion to hydrocarbons according to the
process of this invention can be obtained from light hydrocarbons
such as methane by means of steam reforming, partial oxidation, or
other processes known in the art. Preferably the hydrogen is
provided by free hydrogen, although some Fischer-Tropsch catalysts
have sufficient water gas shift activity to convert some water to
hydrogen for use in the Fischer-Tropsch process. It is preferred
that the molar ratio of hydrogen to carbon monoxide in the feed be
greater than 0.5:1 (e.g., from about 0.67 to 2.5). Preferably, the
feed gas stream contains hydrogen and carbon monoxide in a molar
ratio of about 2:1. The feed gas may also contain carbon dioxide.
The feed gas stream should contain a low concentration of compounds
or elements that have a deleterious effect on the catalyst, such as
poisons. For example, the feed gas may need to be pre-treated to
ensure that it contains low concentrations of sulfur or nitrogen
compounds such as hydrogen sulfide, ammonia and carbonyl
sulfides.
[0034] The feed gas is contacted with a catalyst in a reaction
zone. Mechanical arrangements of conventional design may be
employed as the reaction zone including but not limited to, for
example, slurry bubble column, reactive distillation column, or
ebulliating bed reactors, among others, may be used. Accordingly,
the size and physical form of the catalyst particles may vary
depending on the reactor in which they are to be used.
[0035] The Fischer-Tropsch process is typically run in a continuous
mode. In this mode, typically, the gas hourly space velocity,
defined by dividing the gas flow rate by the volume of the expanded
catalyst bed, may range from about 50 1/hr to about 10,000 1/hr,
preferably from about 300 1/hr to about 2,000 1/hr. The gas hourly
space velocity is defined at the standard condition where the
pressure is 1 bar and temperature is 0 degree centigrade. The
reaction zone temperature is typically in the range from about
160.degree. C. to about 300.degree. C. Preferably, the reaction
zone is operated at conversion promoting conditions at temperatures
from about 190.degree. C. to about 260.degree. C. The reaction zone
pressure is preferably in the range of from about 80 psig (653 kPa)
to about 1000 psig (6994 kPa), more preferably from 80 psig (653
kPa) to about 600 psig (4237 kPa), and still more preferably, from
about 140 psig (1066 kPa) to about 500 psig (3497 kPa).
[0036] The products resulting from the process will have a great
range of molecular weights. Typically, the carbon number range of
the product hydrocarbons will start at methane and continue to the
limits observable by modem analysis, about 50 to 100 carbons per
molecule. The process is particularly useful for making
hydrocarbons having five or more carbon atoms especially when the
above-referenced preferred space velocity, temperature and pressure
ranges are employed.
[0037] The wide range of hydrocarbons produced in the reaction zone
will typically result in liquid phase products being present at the
reaction zone operating conditions. Therefore, the effluent stream
of the reaction zone will often be a mixed phase stream including
liquid and vapor phase products. The effluent stream of the
reaction zone may be cooled to condense the additional amounts of
hydrocarbons and passed into a vapor-liquid separation zone
separating the liquid and vapor phase products. The vapor phase
material may be passed into a second stage of cooling for recovery
of additional hydrocarbons. The liquid phase material from the
initial vapor-liquid separation zone together with any liquid from
a subsequent separation zone may be fed into a fractionation
column. Typically, a stripping column is employed first to remove
light hydrocarbons such as propane and butane. The remaining
hydrocarbons may be passed into a fractionation column where they
are separated by boiling point range into products such as naphtha,
kerosene and fuel oils. Hydrocarbons recovered from the reaction
zone and having a boiling point above that of the desired products
may be passed into conventional processing equipment such as a
hydrocracking zone in order to reduce their molecular weight. The
gas phase recovered from the reactor zone effluent stream after
hydrocarbon recovery may be partially recycled if it contains a
sufficient quantity of hydrogen and/or carbon monoxide.
[0038] While the present invention has been disclosed and described
in terms of a preferred embodiment, the invention is not limited to
the preferred embodiment. For example, it will be understood that
the various mechanical arrangements disclosed herein for the
reducing the maximum water concentration in the reactor can be
modified in number, shape, size, and configuration. In addition,
various modifications to the operating conditions, feedstock,
catalyst, and slurry content, among others, can be made without
departing from the scope of the invention. In the claims that
follow, any recitation of steps is not intended as a requirement
that the steps be performed sequentially, or that one step be
completed before another step is begun, unless explicitly so
stated.
* * * * *