U.S. patent application number 12/770525 was filed with the patent office on 2010-12-02 for reactor comprising cooling modules.
Invention is credited to Kelvin John Hendrie, Wouter Van Maaren, Remco Schilthuizen, Barend Roeland Vermeer, Ronald Vladimir Wisman.
Application Number | 20100303684 12/770525 |
Document ID | / |
Family ID | 41036733 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100303684 |
Kind Code |
A1 |
Hendrie; Kelvin John ; et
al. |
December 2, 2010 |
REACTOR COMPRISING COOLING MODULES
Abstract
The invention relates to a reactor for carrying out an
exothermic process comprising a reactor shell, inlets for
introducing reactants and coolant into the reactor shell, outlets
for removing product and coolant from the reactor shell, and a
plurality of cooling modules, the reactor comprising for at least
some of the modules a skirt for guiding gas underneath the
modules.
Inventors: |
Hendrie; Kelvin John;
(Amsterdam, NL) ; Maaren; Wouter Van; (Amsterdam,
NL) ; Schilthuizen; Remco; (Amsterdam, NL) ;
Vermeer; Barend Roeland; (Amsterdam, NL) ; Wisman;
Ronald Vladimir; (Amsterdam, NL) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
41036733 |
Appl. No.: |
12/770525 |
Filed: |
April 29, 2010 |
Current U.S.
Class: |
422/200 |
Current CPC
Class: |
B01J 8/0285 20130101;
B01J 2219/0002 20130101; B01J 8/22 20130101; C10G 2300/4056
20130101; C10G 2300/4006 20130101; C10G 2/34 20130101; B01J 12/007
20130101; F28D 7/163 20130101; B01J 2208/00132 20130101; B01J
2219/00081 20130101 |
Class at
Publication: |
422/200 |
International
Class: |
F28D 7/00 20060101
F28D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 4, 2009 |
EP |
09159295.6 |
Claims
1. A reactor for carrying out an exothermic process comprising a
reactor shell, inlets for introducing reactants and coolant into
the reactor shell, outlets for removing product and coolant from
the reactor shell, and a plurality of cooling modules, the reactor
comprising for at least some of the modules a skirt for guiding gas
underneath the modules.
2. A reactor according to claim 1, wherein at least some of the
skirts are provided with an individual gas supply.
3. A reactor according to claim 2, wherein the gas supplies
comprise pipes running below and parallel to the skirts and are
provided with orifices or nozzles directed towards the cavities
defined by the skirts.
4. A reactor according to claim 1, wherein one or more of the
cooling modules comprises a coolant inlet, a coolant distribution
chamber, a plurality of cooling tubes, a coolant collection
chamber, and a coolant discharge.
5. A reactor according to claim 4, wherein at least 80% of the
cooling tubes of the cooling modules are arranged separately with a
distance to the nearest cooling tube of at least 1 cm.
6. A reactor according to claim 4, wherein one or more of the
cooling modules comprises one or more passages extending through
the distribution chamber to enable fluid communication between the
space on one side of the distribution chamber and the space between
the cooling tubes, and wherein the cooling module comprises one or
more passages extending through the collection chamber to enable
fluid communication between the space between the cooling tubes and
the space above the collection chamber.
7. A reactor according to claim 4, wherein a structured catalyst is
placed between the cooling tubes.
8. A reactor according to claim 4, wherein the cooling tubes are
enveloped by one or more walls to contain reactants and product
within the module.
9. A reactor according to claim 1, wherein the cooling module
comprises one or more baffles along the height of the module, the
baffles preferably comprising perforations to redistribute the
reactants over the cross-section of the module.
Description
[0001] This application claims the benefit of European Application
No. 09159295.6 filed May 4, 2009, which is incorporated herein by
reference.
BACKGROUND
[0002] The present invention relates to a reactor for carrying out
an exothermic process, such as a Fischer-Tropsch process,
comprising cooling modules. The reactor is compartmentalized. The
invention further relates to the use of such a reactor for carrying
out an exothermic process.
[0003] As is explained in WO 2005/075065, Fischer-Tropsch processes
are often used for the conversion of gaseous hydrocarbon feedstocks
into liquid and/or solid hydrocarbons. The feedstock, e.g. natural
gas, associated gas, coal-bed methane, residual (crude) oil
fractions, coal and/or biomass is converted in a first step to a
mixture of hydrogen and carbon monoxide, also known as synthesis
gas or syngas. The synthesis gas is then converted in a second step
over a suitable catalyst at elevated temperature and pressure into
paraffinic compounds ranging from methane to high molecular weight
molecules comprising up to 200 carbon atoms, or, under particular
circumstances, more.
[0004] Numerous types of reactor systems have been developed for
carrying out the Fischer-Tropsch reaction. Fischer-Tropsch reactor
systems include fixed bed reactors, in particular multi-tubular
fixed bed reactors, fluidized bed reactors, such as entrained
fluidized bed reactors and fixed fluidized bed reactors, and slurry
bed reactors, such as three-phase slurry bubble columns and
ebullated bed reactors.
[0005] The Fischer-Tropsch reaction is highly exothermic and
temperature sensitive and thus requires careful temperature control
to maintain optimum operating conditions and hydrocarbon product
selectivity.
[0006] Commercial fixed-bed and three-phase slurry reactors
typically utilize boiling water to remove reaction heat. In
fixed-bed reactors, individual reactor tubes are located within a
shell containing water/steam typically fed to the reactor via
flanges in the shell wall. The reaction heat raises the temperature
of the catalyst bed within each tube. This thermal energy is
transferred to the tube wall forcing the surrounding water to boil.
In the slurry design, cooling tubes are placed within the slurry
volume and heat is transferred from the liquid continuous matrix to
the tube walls. The production of steam within the tubes provides
cooling.
[0007] U.S. Pat. No. 2,853,369 describes a compartmentalized slurry
reactor. The reactor comprises heat exchange pipes and vertical
shafts. The shafts are placed at a relatively high level in the
reactor, and form walls along the mid part of the heat exchange
pipes. Gas may enter the reactor via a single inlet in the bottom
of the reactor, or via a gas distribution means across the bottom
which directs the gas towards the bottom of the reactor. U.S. Pat.
No. 2,853,369 mentions that in the sump underneath the shafts the
gas distribution is large and uneven.
[0008] It would be an advancement in the art to provide a reactor
which allows relatively simple yet robust construction and
operation.
SUMMARY OF THE INVENTION
[0009] The reactor according to the present invention is
characterized in that the reactor comprises a plurality of cooling
modules and for at least some of the modules a skirt for guiding
gas underneath the modules.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a vertical cross-section of a reactor according to
the present invention.
[0011] FIGS. 2 and 3 are lateral cross-sections, at II and at III
respectively, of the reactor shown in FIG. 1. FIG. 2 shows a gas
distribution system.
[0012] FIG. 3 shows coolant inlet piping.
[0013] FIGS. 4A and 4B are perspective views of a cooling module
used in the reactor shown in FIG. 1.
[0014] FIG. 5 is a top view of the distribution chamber shown in
FIGS. 4A and 4B.
[0015] FIG. 6 is a top view of a perforated baffle.
[0016] FIGS. 7 and 8 show two different embodiments of a gas supply
for the cooling modules in the reactor.
DETAILED DESCRIPTION
[0017] The reactor is suitable for carrying out an exothermic
process, such as a Fischer-Tropsch process. The reactor comprises a
reactor shell, inlets for introducing reactants and coolant into
the reactor shell, outlets for removing product and coolant from
the reactor shell.
[0018] A reactor according to the present invention is a slurry
reactor. The cooling modules in the reactor according to the
present invention are suitable for use in a slurry reactor. The
cooling tubes of the cooling modules are normally placed within the
volume in which the reaction takes place and heat is transferred
from the liquid continuous matrix to the tube walls.
[0019] The catalyst in the reaction volume may be a particulate
catalyst. Additionally or alternatively, the catalyst in the
reaction volume may be a structured catalyst, for example a shaped
porous structure. A structured catalyst may form an ebullated bed.
A structured catalyst may be fixed in the reaction volume. When the
catalyst is fixed in the slurry reactor, the reactor may be
referred to as an "immobilized slurry reactor".
[0020] The cooling modules in the reactor of the current invention
may be any type of cooling module. Examples of suitable cooling
modules are described in WO 2005/035108, WO 2005/065813, WO
2005/075065, WO 2006/097906, and U.S. Pat. No. 6,060,524.
[0021] Preferably the cooling module comprises a coolant inlet, a
coolant distribution chamber, a plurality of cooling tubes, a
coolant collection chamber, and a coolant discharge.
[0022] The cooling tubes are preferably arranged as separate
cooling tubes. When the cooling module is in use, coolant may pass
from the coolant distribution chamber through the cooling tubes to
the coolant collection chamber. Preferably at least 80%, more
preferably at least 90%, of the cooling tubes are arranged
separately with a distance to the nearest cooling tube of at least
1 cm, preferably at least 2 cm. Preferably at least 80%, more
preferably at least 90%, of the cooling tubes have a distance of at
least 1 cm, preferably at least 2 cm, to its nearest cooling tube
along the length of the cooling tubes. The distance between two
adjacent cooling tubes in the cooling module of the present
invention preferably is less than 50 cm, more preferably less than
20 cm, along the length of the cooling tubes.
[0023] In one embodiment of the reactor of the present invention,
one or more of the cooling modules comprises one or more passages
extending through the distribution chamber to enable fluid
communication between the space on one side of the distribution
chamber, typically underneath the distribution chamber, and the
space between the cooling tubes. The cooling module(s) may
additionally comprise one or more passages extending through the
collection chamber to enable fluid communication between the space
between the cooling tubes and the space above the collection
chamber. The passages, preferably a plurality of tubes, extending
through the distribution chamber on the one hand provide an
effective (upward) passage for the (gaseous) reactants and, in some
embodiments, passage of the (liquid) product and on the other hand
enable a relatively straightforward construction of the bottom
header and, if desired, the top header of the cooling module.
Further, if the passages are evenly distributed, e.g. in rows or in
a pattern having a square, rectangular or triangular pitch, over
the cross-section of the distribution chamber, the bottom header
contributes to an even distribution of gaseous reactants entering
the module. In another aspect, at least one of the distribution
chamber and the collection chamber comprises two at least
substantially parallel plates interconnected by means of the
passage tubes. As a result of this structural connection, the
passage tubes add to the mechanical strength of the header and bear
part of the internal and external pressure load, exerted by the
(evaporating) cooling medium and reactants and product
respectively, as well as the structural load exerted on the bottom
header by the mass of the module itself.
[0024] In one embodiment of the reactor of the present invention, a
structured catalyst is placed between the cooling tubes of the
cooling modules, such as shaped porous structures e.g. woven or
non-woven and optionally compressed metal fabrics, e.g. in the form
of sheets or contained in a cage. This configuration combines the
advantage of a fixed bed reactor in that substantially no filtering
of catalyst particles is required and the advantage of a slurry
reactor, i.e. relatively high transfer of heat from the product to
the coolant.
[0025] In another aspect, the cooling tubes are enveloped by one or
more walls to contain reactants and product within the module, thus
compartmentalizing the reactor in the radial direction and
preferably at least up to the level of the structured catalyst
(catalyst bed) in the reactor. Compartmentalizing the reactor
facilitates scaling up in that a larger reactor can be obtained by
using more of the same compartments (multiplication) having
predictable hydrodynamic behavior. Thus, large scale hydrodynamics
can be avoided and the risks of scaling up are reduced.
[0026] In one aspect, the reactor comprises several cooling
modules, at least one cooling module being enveloped by one or more
walls. Two walls may be connected to each other. Alternatively,
there may be a space between two adjacent walls along the side of
the walls which is substantially parallel to the length of the
cooling tubes. The length of the walls may, for example, extend
along the cooling tubes from the distribution chamber up to the
collection chamber of the cooling module. Alternatively, the walls
may, for example, extend along the cooling tubes from the top of
the distribution chamber up to about 50 to 70% of the length of the
cooling tubes. The distance between two opposite substantially
parallel walls preferably is in the range of from 0.5 m to 10 m,
more preferably in the range of from 0.5 m to 6 m, even more
preferably in the range of from 0.5 m to 3 m. A wall preferably has
a thickness in the range of from 0.5 mm to 12 mm, more preferably
in the range of from 2 to 10 mm. The width of a wall preferably is
in the range of from 5 cm to 15 m, more preferably in the range of
from 1 m to 9 m.
[0027] In yet another aspect, the reactor comprises one or more
perforated baffles, preferably at regular intervals along the
length of the cooling tubes. The flow of gas and liquid can be
influenced by selecting a suitable pattern for and dimensions of
the perforations. I.e., the baffles can be used as redistributors
for the gas and liquid inside the modules. Further, the baffles can
provide support for any catalyst system that might be installed
between cooling tubes and add mechanical strength to the module,
e.g. by preventing tube buckling and module twisting. Baffles are
preferably placed substantially horizontal.
[0028] The shape, size and configuration of the cooling modules and
their arrangement within a reactor are governed primarily by
factors such as the capacity, operating conditions and cooling
requirements of the reactor. The cooling modules may have any
cross-section which provides for efficient packing of cooling
modules within a reactor, for example, the cooling module may be of
square, triangular, rectangular, trapezoidal (especially covering
three equilateral triangles) or hexagonal cross-section. A cooling
module having a square cross-section is advantageous in terms of
lateral movement of the modules within the reactor during
installation and removal and in providing uniform cooling
throughout the reactor volume.
[0029] The cross-sectional area of the cooling modules may
typically be about 0.1 to 5.00 m.sup.2, preferably about 0.16 to
2.00 m.sup.2, depending on the number and configuration of cooling
tubes employed and the cooling capacity required.
[0030] The cooling tubes preferably have a length of about 4 to
about 40 metres, more preferably a length of about 10 to about 25
metres. A cooling tube may have any cross section, for example,
square or circular, preferably circular. Further, the outer
diameter of each of the cooling tubes is preferably in a range from
about 1 to about 10 cm, more preferably in a range from about 2 to
about 5 cm.
[0031] A reactor according to the invention comprises a plurality
of cooling modules which are typically placed in parallel.
[0032] In one aspect, the reactor comprises a grid or set of beams
for supporting the modules near the bottom of the reactor and
optionally one or more further grids or sets of beams for guiding
the modules during installation in and removal from the
reactor.
[0033] At least some of the cooling modules in a reactor according
to the invention comprise a skirt, e.g. attached to or as an
integral part of the beams or grid or directly to the corresponding
modules or attached to the walls, for guiding feed gas underneath
the modules. Reactant gas is guided underneath the modules, flows
upwards, and enters the space between the cooling tubes. In some
embodiments the gas may pass through passages in the distribution
chamber of a cooling module before it enters the space between the
cooling tubes. In some embodiments the gas passes alongside the
distribution chamber of a cooling module before it enters the space
between the cooling tubes. Reactant gas might follow a preferred
path (bypass) instead of being evenly distributed over the cooling
modules. By guiding reactant gas underneath the modules, bypass of
gas can be reduced or avoided.
[0034] A skirt preferably has a thickness in the range of from 0.5
mm to 12 mm, more preferably in the range of from 2 to 10 mm. A
skirt preferably extends downwards from the module with a length in
the range of from 10 cm to 5 m, more preferably 10 cm to 2 m, even
more preferably in the range of from 50 cm to 1 m. The width of the
skirt, horizontally along a side of the cooling module, preferably
is in the range of from 5 cm to 15 m, more preferably in the range
of from 1 m to 9 m.
[0035] The reactants inlet of the reactor may be connected to a gas
distribution system with several gas outlets. A gas distribution
system may, for example, consist of pipes with orifices, nozzles
and/or spargers.
[0036] The gas outlets of a gas distribution system are preferably
directed towards the cooling modules, so that the gas flow is
guided and is evenly distributed over the cooling modules. The gas
outlets of a gas distribution system are preferably directed to the
cavities under the cooling modules that are defined by the
skirts.
[0037] The cooling modules, the skirts, and the optional walls,
baffles, and gas distribution system in a reactor according to the
invention preferably are able to withstand the conditions of an
exothermic reaction. More preferably, they are able to withstand
Fischer Tropsch reaction conditions. A cooling module, wall,
baffle, and/or skirt can be made of any material, and preferably is
made of sheet metal, titanium, carbon steel, graphite, stainless
steel, alumina, and/or carbon fibre reinforce steel. A cooling
module, wall, baffle, and/or skirt is most preferably steel,
especially carbon steel or stainless steel.
[0038] The reactor preferably comprises between 1 and 100 cooling
modules, more preferably between 2 and 100 cooling modules, even
more preferably between 12 and 65, most preferably between 24 and
50.
[0039] The invention will now be explained in more detail with
reference to the drawings, which show an example of a reactor
according to the invention.
[0040] FIGS. 1 to 3 show a reactor 1 for carrying out an exothermic
process, such as a Fischer-Tropsch process, comprising a reactor
shell 2, at least one reactant inlet 3, at least one product outlet
(not shown), at least one top outlet and liquid-gas separator (not
shown), a cooling system 5 comprising a plurality of cooling
modules 6, and inlets 7 and outlets 8 for a coolant. The reactor 1
further comprises skirts 30 for guiding reactant gas from the
reactant inlet and gas distribution system to the cooling modules 6
inside the reactor 1.
[0041] The upper part of the reactor 1 comprises a flanged dome 10
having an inner diameter equal to that of the main cylindrical
section of the reactor 1, which dome 10 provides access to the
interior of the reactor 1 and enables the cooling modules 6 to be
installed in and removed from the reactor 1.
[0042] FIGS. 4A to 8 show a cooling module 6 having a square
cross-section and comprising, from bottom to top, a coolant
distribution chamber 15, an array of cooling tubes 16, and a
coolant collection chamber 17.
[0043] As shown in FIGS. 5 and 6, the cooling tubes 16 are arranged
in rows separated by a distance sufficient to accommodate a
structured catalyst, in particular shaped porous structures such as
woven or non-woven and optionally compressed metal fabrics, e.g. in
the form of blankets 24 (only three shown), between the rows of
cooling tubes 16. Fischer-Tropsch catalysts are known in the art
and typically include a Group VIII metal component, preferably
cobalt, iron and/or ruthenium, more preferably cobalt. Suitable
catalyst structures are disclosed in, e.g., WO 2006/037776 and WO
2007/068732.
[0044] In the embodiment shown in the Figures, the collection
chamber 17 is identical to the distribution chamber 15. However,
typically, the collection chamber will be different, e.g. may
comprise an outlet having a larger diameter to take account of the
increased volume of evaporated coolant.
[0045] The cooling tubes 16 are enveloped by walls 25 (omitted in
FIGS. 4A to 6) extending from the level of the distribution chamber
15 to level of the collection chamber 17 to contain reactants and
product within the module 6. In an alternative embodiment, the
wall(s) terminate at a distance below the collection chamber, e.g.
extend just up to the top level of the structured catalyst
(catalyst bed) in the reactor.
[0046] Baffles 26 comprising, as shown in FIG. 6, rows of
relatively small perforations 27 are provided at regular intervals
along the length of the cooling tubes 16 to redistribute the gas
and product inside the modules 6 and to provide support for the
structured catalyst 24.
[0047] The cooling modules 6A adjacent the reactor wall 2 have a
different cross-section to maximize reactor volume utilization.
[0048] As shown in FIGS. 7 and 8, skirts 30 are present below each
of the modules 6 for guiding gas. In the embodiment shown in FIG.
7, pipes 31 run below and parallel to the skirts 30 and are
provided with orifices 32 or nozzles directed towards the cavities
defined by the skirts 30. In the alternative embodiment shown in
FIG. 8, an annular pipe 33 is provided around the inlet 22 of each
of the modules 6.
[0049] During operation, coolant, typically water and/or steam, is
fed through the inlet 7 to the distribution chamber of each of the
modules 6. There, the coolant is distributed over the cooling tubes
16 and flows through the tubes 16 to the collection chamber 17
where it is collected and discharged via the outlet 8. Heat is
transferred from the structured catalyst and the liquid surrounding
the cooling tubes 16 to the coolant as it passes through the
modules 6 and in particular as the coolant flows through the
cooling tubes 16.
[0050] Syngas is fed through the inlet 3 to the pipes 31, and into
the cavities defined by the skirts 30. Reactant gas is guided
underneath the modules by skirts 30.
[0051] The modules can be installed by removing the dome and
subsequently lowering the cooling modules into position in the
reactor shell without the need for any personnel to be inside at
the bottom of the reactor.
[0052] The invention is not limited to the embodiment described
above, which can be varied in several ways within the scope of the
claims. For instance, the reactor can be provided with a sub-dome
or manhole, having a diameter significantly smaller than that of
the cylindrical section of the reactor. In that case, internal
lifting means (not shown) such as a temporary internal hoist fixed
in the space above the cooling modules and below the ceiling of the
reactor shell can be provided to facilitate lateral movement of the
modules within the reactor shell, e.g. from the central-most
position to the designated positions and vice versa.
[0053] In a further example, the reactor according to the present
invention can be used for other exothermic processes including
hydrogenation, hydroformylation, alkanol synthesis, the preparation
of aromatic urethanes using carbon monoxide, Kolbel-Engelhard
synthesis, and polyolefin synthesis.
* * * * *