U.S. patent application number 13/216019 was filed with the patent office on 2011-12-22 for method of operating a three-phase slurry reactor.
Invention is credited to Berthold Berend Breman, Derk Willem Frederik Brilman, Andre Peter Steynberg.
Application Number | 20110311402 13/216019 |
Document ID | / |
Family ID | 36604252 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110311402 |
Kind Code |
A1 |
Steynberg; Andre Peter ; et
al. |
December 22, 2011 |
METHOD OF OPERATING A THREE-PHASE SLURRY REACTOR
Abstract
A method of operating a three-phase slurry reactor includes
feeding at a low level at least one gaseous reactant into a
vertically extending slurry body of solid particles suspended in a
suspension liquid, the slurry body being contained in a plurality
of vertically extending horizontally spaced slurry channels inside
a common reactor shell, the slurry channels being defined between
vertically extending horizontally spaced divider walls or plates
and each slurry channel having a height, width and breadth such
that the height and breadth are much larger than the width. The
gaseous reactant is allowed to react as it passes upwardly through
the slurry body present in the slurry channels, thereby to form
non-gaseous and/or gaseous product. Gaseous product and/or
unreacted gaseous reactant is allowed to disengage from the slurry
body in a head space above the slurry body.
Inventors: |
Steynberg; Andre Peter;
(Vanderbijlpark, ZA) ; Breman; Berthold Berend;
(AG Zutphen, NL) ; Brilman; Derk Willem Frederik;
(LS Delden, NL) |
Family ID: |
36604252 |
Appl. No.: |
13/216019 |
Filed: |
August 23, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11908916 |
Sep 17, 2007 |
8013025 |
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PCT/IB2006/050836 |
Mar 17, 2006 |
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13216019 |
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Current U.S.
Class: |
422/140 ;
422/141 |
Current CPC
Class: |
B01J 2219/00015
20130101; B01J 8/22 20130101; B01J 2208/0015 20130101; B01J 8/1836
20130101; B01J 2219/0002 20130101; B01J 2219/2462 20130101; B01J
2219/2496 20130101; B01J 2219/2474 20130101; B01J 19/249 20130101;
B01J 2219/2481 20130101; B01J 2208/022 20130101; B01J 2219/2458
20130101; B01J 8/226 20130101; C10G 2/32 20130101; B01J 2219/2453
20130101; C10G 2/342 20130101 |
Class at
Publication: |
422/140 ;
422/141 |
International
Class: |
B01J 8/18 20060101
B01J008/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2005 |
ZA |
2005/02264 |
Claims
1.-32. (canceled)
33. A three-phase-slurry reactor, the reactor including a reactor
shell containing a plurality of vertically extending horizontally
spaced open-ended slurry channels which, in use, will contain a
slurry of solid particles suspended in a suspension liquid, the
slurry channels being defined between vertically extending
horizontally spaced divider walls or plates and each slurry channel
having a height, width and breadth such that the height and breadth
are much larger than the width, the slurry channels being grouped
together in reactor modules or sub-reactors; a gas inlet in the
reactor shell for introducing a gaseous reactant or gaseous
reactants into the reactor; and a gas outlet in the shell for
withdrawing gas from a head space in the shell above the slurry
channels.
34. The reactor as claimed in claim 33, in which at least some of
the divider walls or plates at least partially define heat transfer
medium flow spaces or channels.
35. The reactor as claimed in claim 33, in which the slurry zone
has a normal slurry level above open upper ends of the slurry
channels so that at least some of the slurry channels are in slurry
flow communication above their open upper ends.
36. The reactor as claimed in claim 33, in which the reactor
modules or sub-reactors are horizontally disposed across the
cross-sectional area of the reactor shell.
37. The reactor as claimed in claim 36, in which the sub-reactors
have vertically extending side walls separating them from adjacent
horizontally spaced sub-reactors and in which the vertically
extending side walls are configured to prevent slurry flow
communication between adjacent horizontally spaced sub-reactors at
all elevations between upper and lower open ends of the slurry
channels of the adjacent horizontally disposed sub-reactors.
38. The reactor as claimed in claim 36, in which the slurry
channels are defined by divider walls or plates that are parallel
within each sub-reactor so that the adjacent sub-reactors each have
a breadth axis, and in which the breadth axes of adjacent
horizontally disposed sub-reactors are perpendicular.
39. The reactor as claimed in claim 36, which includes reactor
modules or sub-reactors which are vertically spaced, with the open
upper ends of the slurry channels of a lower sub-reactor or
sub-reactors being below the open lower ends of the slurry channels
of an upper sub-reactor or sub-reactors.
40. The reactor as claimed in claim 39, which includes an
intermediate zone between upper sub-reactor(s) and lower
sub-reactor(s), with said intermediate zone being in flow
communication with slurry channels of an upper sub-reactor or
sub-reactors and with slurry channels of a lower sub-reactor or
sub-reactors.
41. The reactor as claimed in claim 40, which includes a gas inlet
into said intermediate zone between upper and lower
sub-reactors.
42. The reactor as claimed in claim 33, in which one or more
downcomer zones or downcomers extend from at or above the open
upper ends of the slurry channels, or the slurry channels of an
upper sub-reactor if present, to at or below open lower ends of the
slurry channels, or slurry channels of a lower sub-reactor if
present, and/or in which one or more downcomer zones or downcomers
extend from at or above the open upper ends of the slurry channels
in a sub-reactor, to at or below open lower ends of the slurry
channels of said sub-reactor.
43. A three-phase slurry reactor, the reactor including a reactor
shell containing a plurality of vertically extending horizontally
spaced slurry channels which, in use, will contain a slurry of
solid particles suspended in a suspension liquid, the slurry
channels being located in a slurry zone inside the reactor shell
which has a normal slurry level above open upper ends of the slurry
channels so that at least some of the slurry channels are in slurry
flow communication above their open ends, the slurry channels being
grouped together in reactor modules or sub-reactors; a heat
transfer medium flow space or spaces defined by walls of the slurry
channels separating the slurry channels from the heat transfer
medium flow space or spaces so that in use heat transfer in
indirect heat transfer relationship can take place between slurry
in the slurry channels and a heat transfer medium in the heat
transfer medium flow space or spaces; one or more downcomer zones
or downcomers through which slurry can pass from a high level in
the slurry zone to a lower level thereof; a gas inlet in the
reactor shell for introducing a gaseous reactant or gaseous
reactants into the reactor; a gas outlet in the shell for
withdrawing gas from a head space in the shell above the slurry
channels; and if necessary, a liquid inlet for adding or
withdrawing slurry or suspension liquid to or from the reactor.
44. The reactor as claimed in claim 43, in which at least some of
the slurry channels are in slurry flow communication below open
lower ends of the slurry channels, the slurry channels having walls
configured to prevent slurry flow from or into the slurry channels
other than through open upper and open lower ends of the slurry
channels.
45. The reactor as claimed in claim 43, in which the slurry
channels in the reactor are defined by vertically extending tubes
between tube sheets, with the heat transfer medium flow space being
defined between the tubes sheets and surrounding the tubes.
46. The reactor as claimed in claim 43, in which the slurry
channels are defined by vertically extending horizontally spaced
divider walls or plates, with the heat transfer medium flow spaces
also being defined between vertically extending horizontally spaced
divider walls or plates, and at least some of the divider walls or
plates being parallel to each other, defining slurry channels and
heat transfer medium flow spaces with a height, width and breadth
such that the height and breadth are much larger than the
width.
47. The reactor as claimed in claim 43, in which the reactor
modules or sub-reactors are horizontally disposed across the
cross-sectional area of the reactor shell.
48. The reactor as claimed in claim 47, in which the sub-reactors
have vertically extending side walls separating them from adjacent
horizontally spaced sub-reactors and in which the vertically
extending side walls are configured to prevent slurry flow
communication between adjacent horizontally spaced sub-reactors at
all elevations between upper and lower open ends of the slurry
channels of the adjacent horizontally disposed sub-reactors.
49. The reactor as claimed in claim 47, in which the slurry
channels are defined by divider walls or plates that are parallel
within each sub-reactor so that the adjacent sub-reactors each have
a breadth axis, and in which the breadth axes of adjacent
horizontally disposed sub-reactors are perpendicular.
50. The reactor as claimed in claim 47, which includes reactor
modules or sub-reactors which are vertically spaced, with the open
upper ends of the slurry channels of a lower sub-reactor or
sub-reactors being below the open lower ends of the slurry channels
of an upper sub-reactor or sub-reactors.
51. The reactor as claimed in claim 50, which includes an
intermediate zone between upper sub-reactor(s) and lower
sub-reactor(s), with said intermediate zone being in flow
communication with slurry channels of an upper sub-reactor or
sub-reactors and with slurry channels of a lower sub-reactor or
sub-reactors.
52. The reactor as claimed in claim 51, which includes a gas inlet
into said intermediate zone between upper and lower
sub-reactors.
53. The reactor as claimed in claim 43, in which one or more
downcomer zones or downcomers extend from at or above the open
upper ends of the slurry channels, or the slurry channels of an
upper sub-reactor if present, to at or below open lower ends of the
slurry channels, or slurry channels of a lower sub-reactor if
present, and/or in which one or more downcomer zones or downcomers
extend from at or above the open upper ends of the slurry channels
in a sub-reactor, to at or below open lower ends of the slurry
channels of said sub-reactor.
Description
[0001] THIS INVENTION relates to a method of operating a
three-phase slurry reactor and to a three-phase slurry reactor.
[0002] Considerable risk is encountered when technology is scaled
up from pilot plant scale to commercial plant scale in order to
reap the benefits of economy of scale. Three-phase slurry reactors
typically exhibit scale-dependent macro-mixing effects and the
aforementioned risk is thus applicable when three-phase slurry
reactors are scaled up. It will thus be an advantage if a method
can be found which can significantly reduce the risk associated
with upscaling of three-phase slurry reactors. In addition, reactor
designs in which the mixing patterns inside the reactor can be more
readily modelled or predicted from experimentation have the benefit
that the extent of usually undesirable back-mixing can be limited
thereby potentially allowing an optimal combination of desirable
plug-flow characteristics (usually good productivity and good
selectivity) and well-mixed characteristics (often required for
desirable solids distribution and even temperature profiles).
[0003] A solution that has been proposed is to create zones in the
reactor that effectively mimic the behaviour of a reactor with a
smaller characteristic diameter. In this manner the behaviour of
the large scale reactor can be predicted to some extent, since it
effectively consists of the sum of a number of smaller reactors of
effectively pilot plant scale. However, one is still largely
dependent on working within the bounds of the macro-mixing patterns
that are established in the reactor with a smaller characteristic
diameter. It would thus be an advantage if a method can be found
that allows designers additional degrees of freedom to, at least to
some extent, control the mixing patterns that are established in a
three-phase slurry reactor.
[0004] Three-phase slurry reactors are commonly used for highly
exothermic reactions due to their excellent heat removal
characteristics. However, with the introduction of ever more active
catalysts and more intensive use of reactor volume, even the heat
removal ability of three-phase slurry reactors is being tested.
[0005] In light of what has been said before, it will thus be an
advantage if a method can be found which significantly reduces the
risk associated with upscaling of three-phase slurry reactors by
allowing the designer additional degrees of freedom to exert some
control over the mixing patterns in the reactor, while
simultaneously increasing the heat removal ability of the
reactor.
[0006] According to one aspect of the invention, there is provided
a method of operating a three-phase slurry reactor, the method
including [0007] feeding at a low level at least one gaseous
reactant into a vertically extending slurry body of solid particles
suspended in a suspension liquid, the slurry body being contained
in a plurality of vertically extending horizontally spaced slurry
channels inside a common reactor shell, the slurry channels being
defined between vertically extending horizontally spaced divider
walls or plates and each slurry channel having a height, width and
breadth such that the height and breadth are much larger than the
width; [0008] allowing the gaseous reactant to react as it passes
upwardly through the slurry body present in the slurry channels,
thereby to form non-gaseous and/or gaseous product; [0009] allowing
gaseous product and/or unreacted gaseous reactant to disengage from
the slurry body in a head space above the slurry body; [0010]
withdrawing gaseous product and/or unreacted gaseous reactant from
the head space; and [0011] if necessary, maintaining the slurry
body at a desired level by withdrawing slurry or suspension liquid,
including non-gaseous product if present, or by adding slurry or
suspension liquid.
[0012] The method may include allowing slurry to pass downwardly
from a high level in the slurry body to a lower level thereof,
using one or more downcomer zones or downcomers inside the reactor
shell.
[0013] At least some of the slurry channels may be in slurry flow
communication above upper ends of the slurry channels.
[0014] The divider walls or plates of at least some of the slurry
channels may separate said slurry channels from adjacent heat
transfer medium flow spaces. The method may include passing a heat
transfer medium through the heat transfer medium flow spaces to
exchange heat in indirect relationship with the slurry body present
in the slurry channels.
[0015] Heat transfer surfaces of the reactor, such as those of the
divider walls or plates, may optionally be shaped or textured to
increase their heat transfer surface area or to improve heat
transfer coefficients compared to those of smooth divider walls or
plates. The shaping or texturing may include, amongst other methods
known to persons skilled in the art, the use of dimpled, ribbed or
finned walls or plates.
[0016] According to a second aspect of the invention, there is
provided a method of operating a three-phase slurry reactor, the
method including [0017] feeding at a low level at least one gaseous
reactant into a vertically extending slurry body of solid particles
suspended in a suspension liquid, the slurry body being contained
in a plurality of vertically extending horizontally spaced slurry
channels inside a common reactor shell, at least some of the slurry
channels being in slurry flow communication above open upper ends
of the slurry channels and at least some of the slurry channels
being defined by walls separating the slurry channels from a heat
transfer medium flow space or spaces; [0018] allowing the gaseous
reactant to react as it passes upwardly through the slurry body
present in the slurry channels, thereby to form a non-gaseous
and/or a gaseous product; [0019] passing a heat transfer medium
through the heat transfer medium flow space or spaces to exchange
heat in indirect relationship with the slurry body present in the
slurry channels; [0020] allowing slurry to pass downwardly from a
high level in the slurry body to a lower level thereof, using one
or more downcomer zones or downcomers inside the reactor shell;
[0021] allowing gaseous product and/or unreacted gaseous reactant
to disengage from the slurry body in a head space above the slurry
body; [0022] withdrawing gaseous product and/or unreacted gaseous
reactant from the head space; and [0023] if necessary, maintaining
the slurry body at a desired level by withdrawing slurry or
suspension liquid, including non-gaseous product if present, or by
adding slurry or suspension liquid.
[0024] The slurry channels are preferably isolated from each other
between their open upper ends and open lower ends, and are
preferably separated from each other by heat transfer medium flow
spaces. In other words, the method preferably includes preventing
slurry flow communication at all elevations between the open upper
ends and lower ends of the slurry channels, so that the slurry
channels are discrete, defining completely individualised reaction
chambers.
[0025] The slurry channels used in the method according to the
second aspect of the invention may be defined by vertically
extending tubes between tube sheets, with the heat transfer medium
flow space being defined between the tube sheets and surrounding
the tubes. The tubes typically have diameters of at least about 10
cm.
[0026] Instead, the slurry channels may be defined by vertically
extending horizontally spaced divider walls or plates, with heat
transfer medium flow spaces also being defined between vertically
extending horizontally spaced divider walls or plates, at least
some of the slurry channels being separated from adjacent heat
transfer medium flow spaces by common or shared divider walls or
plates.
[0027] The divider walls or plates may be parallel to each other,
defining slurry channels and heat transfer medium flow spaces with
a height, width and breadth such that the height and breadth are
typically much larger than the width. In other words, each divider
wall has a height and a breadth which are substantial, a relatively
small thickness and is spaced relatively closely from an adjacent
divider wall, thereby defining vertically extending
parallelipipedal channels or spaces with one dimension much smaller
than the other two dimensions.
[0028] Heat transfer surfaces of the reactor, such as those of the
divider walls or plates or tubes, may optionally be shaped or
textured to increase their heat transfer surface area or to improve
heat transfer coefficients compared to those of smooth divider
walls or smooth cylindrical tubes. The shaping or texturing may
include, amongst other methods known to persons skilled in the art,
the use of dimpled, ribbed or finned walls or plates or tubes.
[0029] When the slurry channels are defined by divider walls, the
slurry and heat transfer medium may be present in slurry channels
and heat transfer medium flow spaces that are arranged alternately.
Each slurry channel may thus be flanked by, or sandwiched between,
two heat transfer medium flow spaces, except possibly for radially
outer slurry channels.
[0030] The downward flow of slurry in the downcomer zones or
downcomers may be sufficiently high that there is substantially no
downward flow of slurry in the slurry channels.
[0031] While it is believed that the method can, at least in
principle, have broader application, it is envisaged that the solid
particles will normally be catalyst particles for catalysing the
reaction of the gaseous reactant or gaseous reactants into a liquid
product and/or a gaseous product. The suspension liquid will
normally, but not necessarily always, be liquid product, with
liquid phase or slurry thus being withdrawn from the slurry body to
maintain the slurry body at a desired level.
[0032] Furthermore, while it is also believed that, in principle,
the method can have broader application, it is envisaged that it
will have particular application in hydrocarbon synthesis where the
gaseous reactants are capable of reacting catalytically
exothermically in the slurry body to form liquid hydrocarbon
product and, optionally, gaseous hydrocarbon product. In
particular, the reaction or hydrocarbon synthesis may be
Fischer-Tropsch synthesis, with the gaseous reactants being in the
form of a synthesis gas stream comprising mainly carbon monoxide
and hydrogen, and with both liquid and gaseous hydrocarbon products
being produced and the heat transfer medium being a cooling medium,
e.g. boiler feed water.
[0033] For hydrocarbon synthesis, the slurry channels will
typically have a height of at least 0.5 m, preferably at least 1 m,
more preferably at least 2 m, but may even be 4 m or higher. The
slurry channels will typically have a width of at least 2 cm,
preferably at least 3.8 cm, more preferably at least 5 cm. The
width of the slurry channels will typically not exceed 50 cm, more
preferably the width will not exceed 25 cm, more preferably the
width will not exceed 15 cm. The slurry channels will typically
have a breadth in the range of approximately 0.2 m to 1 m. The
reactor shell will typically have a diameter of at least 1 m,
preferably at least 2.5 m, more preferably at least 5 m, but one
should note that an object of the invention is to neutralise the
effect of reactor diameter on the reactor behaviour.
[0034] As will be appreciated, each slurry channel, whether defined
between divider walls or defined by a tube, functions independently
from the reactor shell and can be configured to function to a large
extent independently from other slurry channels. Design and testing
of a single slurry channel or a small subgroup of slurry channels
on a pilot scale is feasible, with scale-up to a commercial scale
reactor comprising a plurality of the slurry channels then becoming
quite easy and being less risky, provided scale-dependent
macro-mixing effects are managed properly.
[0035] Furthermore, when downcomers or downcomer zones are employed
with a sufficient downward slurry flow such that there is
substantially no downward flow of slurry in the slurry channels,
the establishment of a macro-mixing pattern, other than that
dictated by the defined downflow and upflow zones, over the reactor
is practically impossible.
[0036] The method may include cooling the gas from the head space
to condense liquid product, e.g. liquid hydrocarbons and reaction
water, separating the liquid product from the gases to provide a
tail gas, and recycling at least some of the tail gas to the slurry
body as a recycle gas stream.
[0037] Vertically extending, horizontally disposed reactor zones
may be defined inside the reactor shell, where each horizontally
disposed reactor zone includes a plurality of slurry channels and
optionally one or more heat transfer medium flow spaces. The method
may include preventing slurry flow communication between adjacent
vertically extending, horizontally disposed reactor zones and at
all elevations between upper and lower open ends of the slurry
channels in a horizontally disposed reactor zone. This may be
achieved, for example, by providing the horizontally disposed
reactor zones with vertically extending side walls, or by arranging
the divider walls in adjacent horizontally disposed reactor zones
at perpendicular angles so that an end divider wall in one of the
horizontally disposed reactor zones in effect forms a side wall for
the adjacent horizontally disposed reactor zone.
[0038] The method may include containing the slurry body in
vertically spaced reactor zones each including a plurality of
slurry channels and optionally one or more heat transfer medium
flow spaces. An intermediate slurry zone may be defined between
vertically spaced reactor zones.
[0039] The method may include feeding at least one gaseous stream
into an intermediate zone between two vertically spaced reactor
zones. The gaseous stream may be a recycle gas stream. If desired,
the gaseous stream may be fed such that a portion of the
cross-sectional area of the reactor is not gassed with the gaseous
stream.
[0040] One or more of the downcomer zones or downcomers may extend
from at or above the open upper ends of the slurry channels, or
slurry channels in an upper vertically spaced reactor zone, to at
or below open lower ends of the slurry channels, or slurry channels
in a bottom vertically spaced reactor zone.
[0041] Instead, one or more of the downcomer zones or downcomers
may extend from at or above the open upper ends of the slurry
channels of a vertically spaced reactor zone, to at or below open
lower ends of the slurry channels of said vertically spaced reactor
zone, often into an intermediate zone below said vertically spaced
reactor zone. A lower or higher vertically spaced reactor zone may
include a similar downcomer zone or downcomer, which may be
staggered in plan view from the downcomer zone or downcomer in the
vertically spaced reactor zone above or below, or which may be in
register with the downcomer zone or downcomer in the vertically
spaced reactor zone above or below.
[0042] If desired, a downcomer zone may include a heat transfer
medium flow space or spaces, and/or a filter to separate solid
particles from the suspension liquid.
[0043] Allowing slurry to pass downwardly in a downcomer zone or
downcomer may include preventing or inhibiting gaseous reactant or
reactants from entering the downcomer zone, e.g. by providing a
baffle, and/or it may include degassing the slurry in the downcomer
zone or downcomer, e.g. by providing a degasser at an upper end of
the downcomer zone or downcomer.
[0044] The method may include allowing slurry flow communication
between horizontally disposed reactor zones in one or more of the
intermediate zones, and/or in the bottom of the reactor below the
open lower ends of slurry channels.
[0045] The method may include limiting the axial mixing of the
solid particles over the entire reactor length. This can be
achieved through the selection of vertically spaced reaction zones
and downcomers spanning the length of a single reaction zone.
[0046] According to a third aspect of the invention, there is
provided a three-phase slurry reactor, the reactor including [0047]
a reactor shell containing a plurality of vertically extending
horizontally spaced slurry channels which, in use, will contain a
slurry of solid particles suspended in a suspension liquid, the
slurry channels being defined between vertically extending
horizontally spaced divider walls or plates and each slurry channel
having a height, width and breadth such that the height and breadth
are much larger than the width; [0048] a gas inlet in the reactor
shell for introducing a gaseous reactant or gaseous reactants into
the reactor; and [0049] a gas outlet in the shell for withdrawing
gas from a head space in the shell above the slurry channels.
[0050] At least some of the divider walls or plates may define heat
transfer medium flow spaces or channels. The heat transfer medium
flow channels may also have a height, breadth and width such that
the height and breadth are much larger than the width.
[0051] Heat transfer surfaces of the reactor, such as those of the
divider walls or plates, may optionally be shaped or textured to
increase their heat transfer surface area or to improve heat
transfer coefficients. The shaping or texturing may include,
amongst other methods known to persons skilled in the art, the use
of dimpled, ribbed or finned walls or plates.
[0052] The channels may be as hereinbefore described.
[0053] The slurry channels are thus located in a slurry zone inside
the reactor shell. The slurry zone may have a normal slurry level
above open upper ends of the slurry channels so that at least some
of the slurry channels may be in slurry flow communication above
their open upper ends.
[0054] The reactor may include one or more downcomer zones or
downcomers, in use through which slurry can pass from a high level
in the slurry zone to a lower level thereof.
[0055] According to a fourth aspect of the invention, there is
provided a three-phase slurry reactor, the reactor including [0056]
a reactor shell containing a plurality of vertically extending
horizontally spaced slurry channels which, in use, will contain a
slurry of solid particles suspended in a suspension liquid, the
slurry channels being located in a slurry zone inside the reactor
shell which has a normal slurry level above open upper ends of the
slurry channels so that at least some of the slurry channels are in
slurry flow communication above their open ends; [0057] a heat
transfer medium flow space or spaces defined by walls of the slurry
channels separating the slurry channels from the heat transfer
medium flow space or spaces so that in use heat transfer in
indirect heat transfer relationship can take place between slurry
in the slurry channels and a heat transfer medium in the heat
transfer medium flow space or spaces; [0058] one or more downcomer
zones or downcomers through which slurry can pass from a high level
in the slurry zone to a lower level thereof; [0059] a gas inlet in
the reactor shell for introducing a gaseous reactant or gaseous
reactants into the reactor; [0060] a gas outlet in the shell for
withdrawing gas from a head space in the shell above the slurry
channels; and [0061] if necessary, a liquid inlet for adding or
withdrawing slurry or suspension liquid to or from the reactor.
[0062] At least some of the slurry channels may be in slurry flow
communication below open lower ends of the slurry channels. The
slurry channels may have walls configured to prevent slurry flow
from or into the slurry channels other than through open upper and
lower ends of the slurry channels. In other words, the walls
typically prevent radial or transverse slurry flow between slurry
channels, so that the slurry channels are completely individualised
reaction chambers.
[0063] The slurry channels in the reactor according to the fourth
aspect of the invention may be defined by vertically extending
tubes between tube sheets, with the heat transfer medium flow space
being defined between the tubes sheets and surrounding the tubes.
The tubes typically have diameters of at least about 10 cm.
[0064] Instead, the slurry channels may be defined by vertically
extending horizontally spaced divider walls or plates, with the
heat transfer medium flow spaces also being defined between
vertically extending horizontally spaced divider walls or plates,
at least some slurry channels being separated from adjacent heat
transfer medium flow spaces by common or shared divider walls or
plates.
[0065] The divider walls or plates may be parallel to each other,
defining slurry channels and heat transfer medium flow spaces as
hereinbefore described. Typically, the divider walls or plates
correspond with chords of the circular cylindrical reactor shell,
when seen in plan view.
[0066] When the slurry channels are defined by divider walls, the
slurry channels and heat transfer medium flow spaces may be
alternately arranged. Each slurry channel may thus be flanked by,
or sandwiched between, two heat transfer medium flow spaces, except
possibly for radially outer slurry channels.
[0067] Heat transfer surfaces of the reactor, such as those of the
divider walls or plates or tubes, may optionally be shaped or
textured to increase their heat transfer surface area or to improve
heat transfer coefficients compared to those of smooth divider
walls or smooth cylindrical tubes. The shaping or texturing may
include, amongst other methods known to persons skilled in the art,
the use of dimpled, ribbed or finned walls or plates or tubes.
[0068] The slurry channels, optionally together with one or more
heat transfer medium flow spaces, may be grouped together in
reactor modules or sub-reactors. Sub-reactors may be horizontally
disposed across the cross-sectional area of the reactor shell. A
sub-reactor may have vertically extending side walls separating it
from an adjacent horizontally spaced sub-reactor. The vertically
extending side wall may be configured to prevent slurry flow
communication between adjacent horizontally disposed sub-reactors
at all elevations between upper and lower open ends of the slurry
channels of the adjacent horizontally disposed sub-reactors.
[0069] The slurry channels of horizontally disposed or horizontally
spaced adjacent sub-reactors may each have a breadth axis, when the
slurry channels are defined by divider walls or plates, with the
breadth axes of the slurry channels of adjacent horizontally
disposed sub-reactors being parallel. Instead, the breadth axes of
adjacent horizontally disposed sub-reactors may be perpendicular.
In such an embodiment, an end divider wall of a sub-reactor may
thus form a side wall separating the sub-reactor from a
horizontally disposed adjacent sub-reactor.
[0070] The reactor may include reactor modules or sub-reactors
which are vertically spaced, with the open upper ends of the slurry
channels of a lower sub-reactor or sub-reactors being below the
open lower ends of the slurry channels of an upper sub-reactor or
sub-reactors.
[0071] The reactor may include an intermediate zone between upper
sub-reactor(s) and lower sub-reactor(s). The intermediate zone may
be in flow communication with slurry channels of an upper
sub-reactor or sub-reactors and with slurry channels of a lower
sub-reactor or sub-reactors. In other words, transverse or
horizontal flow or mixing of slurry in the intermediate zone may be
allowed by having the intermediate zone free of barriers which
would prevent transverse flow between open ends of slurry channels
opening out into the intermediate zone.
[0072] The reactor may include a gas inlet into an intermediate
zone between upper and lower sub-reactors. The gas inlet may be a
recycle gas inlet. The gas inlet may be configured to introduce gas
only into a portion of the cross-sectional area of the reactor
shell. In other words, the gas inlet may be arranged in use to gas
only a selected cross-sectional region of the reactor, e.g. only
certain sub-reactors or certain slurry channels.
[0073] One or more downcomer zones or downcomers may extend from at
or above the open upper ends of the slurry channels, or the slurry
channels of an upper sub-reactor, to at or below open lower ends of
the slurry channels, or slurry channels of a lower sub-reactor.
[0074] Instead, one or more of the downcomer zones or downcomers
may extend from at or above the open upper ends of the slurry
channels in a sub-reactor, to at or below open lower ends of the
slurry channels of said sub-reactor, often into an intermediate
zone below said sub-reactor. Downcomer zones or downcomers of
vertically spaced sub-reactors may be staggered in plan view, or
may be in register.
[0075] A downcomer or downcomer zone may be defined by slurry
channels adapted to function as a downcomer or downcomer zone. Such
an adapted slurry channel may have or may be associated with a
gassing prevention device, e.g. a baffle, or it may have or it may
be associated with a degasser at an upper end thereof.
[0076] A downcomer zone or downcomer may include a heat transfer
medium flow space or spaces and/or it may include a filter to
separate solid particles from suspension liquid.
[0077] The heat transfer medium flow spaces, when in the form of
channels, are close-ended, and are provided with heat transfer
medium inlet and outlet arrangements. The heat transfer medium
inlet and outlet arrangements may open out into the channels
through their closed ends, i.e. axially or vertically, or the heat
transfer medium flow channels or spaces may be in flow
communication transversely or horizontally, reminiscent of a plate
heat exchanger in which every second flow space is in flow
communication, whilst being sealed from intervening flow
spaces.
[0078] The invention will now be described, by way of example, with
reference to the accompanying diagrammatic drawings, in which
[0079] FIG. 1 shows a schematic sectional elevational view of one
embodiment of a three-phase slurry reactor in accordance with the
invention;
[0080] FIG. 2 shows a schematic sectional elevational view of
another embodiment of a three-phase slurry reactor in accordance
with the invention;
[0081] FIG. 3 shows a schematic three-dimensional view of some
reactor modules or sub-reactors and downcomers or downcomer zones
of a three-phase slurry reactor in accordance with the
invention;
[0082] FIG. 4 shows a schematic top plan view of the reactor
modules and downcomers of FIG. 3;
[0083] FIG. 5 shows a schematic three-dimensional view of some
upper and lower reactor modules or sub-reactors and downcomers of a
three-phase slurry reactor in accordance with the invention;
[0084] FIGS. 6 to 9 show schematic sectional elevational views of
various embodiments of three-phase slurry reactors in accordance
with the invention, with or without downcomers;
[0085] FIGS. 10 to 12 show schematic sectional elevational views of
various embodiments of three-phase slurry reactors in accordance
with the invention, with stage introduction of gas and various
downcomer arrangements;
[0086] FIGS. 13 to 16 show schematic top plan views of various
arrangements of divider walls of three-phase slurry reactors in
accordance with the invention;
[0087] FIGS. 17 to 20 show schematic sectional plan views of
various three-phase slurry reactors in accordance with the
invention, illustrating various downcomer arrangements; and
[0088] FIGS. 21 to 28 show schematic sectional plan views of
various three-phase slurry reactors in accordance with the
invention, illustrating various arrangements of horizontally
disposed reactor modules or sub-reactors and downcomer zones.
[0089] Referring to FIG. 1 of the drawings, reference numeral 10
generally indicates one embodiment of a three-phase slurry reactor
in accordance with the invention. The reactor 10 includes a reactor
shell 12 which houses a plurality of vertically extending,
horizontally spaced parallel divider walls or plates 14. The plates
14 define a plurality of slurry channels 16.
[0090] The shell 12 is circular cylindrical and the plates 14
correspond with or fall on chords of the shell 12, when viewed in
plan. Each slurry channel 16 has a relatively small width, i.e. the
spacing between the plates 14, compared to its height and its
breadth, where its breadth is taken along an axis perpendicular to
the page on which the drawing is shown.
[0091] Although not shown in the drawings, at least some of the
divider walls or plates 14 may be shaped or textured to increase
their heat transfer surface area or to improve heat transfer
coefficients. The shaping or texturing may include, amongst other
methods known to persons skilled in the art, the use of dimpled,
ribbed or finned walls or plates.
[0092] The reactor 10 also includes a gas inlet 18 leading into a
sparger arrangement 20 below the slurry channels 16. A gas outlet
22 is provided which is in flow communication with a head space 24
above the slurry channels 16. A liquid outlet 26 leads from a
bottom of the reactor 10, below the slurry channels 16, but can be
at any convenient level.
[0093] The reactor 10 has a slurry zone extending from the bottom
of the reactor 10 to a normal slurry level indicated by reference
numerals 28 and 30. As can be seen in FIG. 1, the normal slurry
level 28 can thus either be below the open upper ends of the slurry
channels 16, or the normal slurry level 30 may be above the open
upper ends of the slurry channels 16, thereby in use completely
submerging the plates 14.
[0094] In a slurry reactor such as the reactor 10, there would be
limited or substantially no interaction between the slurry channels
16 where they open out into the bottom of the reactor 10. Reaction
spaces, defined by the slurry channels 16, are essentially
two-dimensional and if the slurry channels are operated essentially
independent of each other the dependency upon the diameter of the
reactor shell 12 largely or completely disappears. This facilitates
scale-up, as a representative unit, consisting of one or a few
slurry channels, can be studied separately and independently from
commercial scale reactor dimensions.
[0095] When the plates 14 are not fully submerged in the slurry
body, i.e. when the normal slurry level is the level 28, the
reactor 10 essentially behaves as a stack of parallel, vertically
extending two-dimensional three-phase slurry columns. Differences
between these two-dimensional columns and conventional
three-dimensional columns, relating to mixing, gas hold-up and heat
and mass transfer, may be used advantageously.
[0096] For fully submerged plates 14, when the normal slurry level
is indicated by the level 30, even more opportunities present
themselves. A slurry circulation flow pattern over the slurry
channels 16 can be established, allowing for better plug flow
characteristics for the phases in the slurry channels 16, a more
uniform solids distribution throughout the slurry and higher heat
transfer coefficients (reactors with heat transfer arrangements
will be discussed in more detail later on).
[0097] Referring to FIG. 2 of the drawings, reference numeral 100
generally indicates another embodiment of a three-phase slurry
reactor in accordance with the invention. The reactor 100 is
similar to the reactor 10 in many respects and the same reference
numerals are thus used to indicate the same or similar parts or
features, unless otherwise indicated. In the reactor 100, heat
transfer medium channels 32 are also defined between some of the
plates 14. The heat transfer medium channels 32 have closed lower
ends and upper ends, but are in flow communication with each other
at their ends and with heat transfer medium inlet and outlet
arrangements (not shown). In use, heat transfer medium can thus be
passed through the heat transfer medium channels 32, either
upwardly or downwardly.
[0098] The slurry channels 16 and the heat transfer medium channels
32 are arranged alternately, so that each slurry channel 16 is
flanked by or sandwiched between two heat transfer medium channels
32, except possibly for radially outer slurry channels 16,
depending on the particular construction of the reactor 100.
[0099] In the reactor 100, the slurry channels 16 and the heat
transfer medium channels 32 are grouped into an upper group,
defining an upper plate bank or sub-reactor 34 and a lower group
defining a lower plate bank or sub-reactor 36. The upper
sub-reactor 34 is vertically spaced from the lower sub-reactor 36
so that the open lower ends of the slurry channels 16 of the upper
sub-reactor 34 are above the open upper ends of the slurry channels
16 of the lower sub-reactor 36. Between the upper sub-reactor 34
and the lower sub-reactor 36 an intermediate zone 38 is defined. A
gas inlet, which is a recycle gas inlet and which is indicated by
reference numeral 40 enters the intermediate zone 38 from two
diagonally opposed sides of the reactor 100. Each recycle gas inlet
40 is associated with a sparger arrangement 42.
[0100] A downcomer 44 with a degasser 46 is provided centrally in
the reactor shell 12 and extends from above the open upper ends of
the slurry channel 16 of the upper sub-reactor 34 to below the open
lower ends of the slurry channels 16 of the upper sub-reactor 34,
i.e. into the intermediate zone 38. Between the reactor shell 12
and the plates 14 of the lower sub-reactor 36, an annular downcomer
zone 48 is defined. As will be noticed, the sparger arrangements 42
are configured not to gas the downcomer 44 and the sparger
arrangement 18 is configured not to gas the downcomer zone 48. As
will be appreciated, the downcomer 44 is in effect staggered
relative to the downcomer zone 48, ensuring a slurry recycle or
redistribution flow as indicated by the arrows 50.
[0101] The reactor 100 in principle is suitable for many processes
requiring a three-phase slurry reactor and requiring heat transfer
to or from the slurry. However, only one use, namely hydrocarbon
synthesis, will now be described.
[0102] In use, fresh synthesis gas comprising mainly carbon
monoxide and hydrogen as gaseous reactants, is fed into the bottom
of the reactor 100 through the gas inlet 18 and the sparger
arrangement 20. By means of the sparger arrangement 20, the
synthesis gas is uniformly distributed throughout the slurry
present in the bottom of the reactor 100. Simultaneously, a recycle
gas stream (typically cooled) comprising typically hydrogen, carbon
monoxide, methane and carbon dioxide is returned to the reactor 100
through the recycle gas inlets 40 and the sparger arrangements 42.
All of the recycle gas stream may be fed into the intermediate zone
38 by means of the recycle gas inlets 40 or, if desired, a portion
of the recycle gas stream may be returned to the bottom of the
reactor 100, by means of the gas inlet 18.
[0103] By means of the sparger arrangements 42, the slurry channels
16 of the upper sub-reactor 34 are specifically targeted with
recycle gas, and the downcomer 44 is avoided. By using the recycle
gas inlets 40, it is thus possible to allow a portion of the
recycle gas to bypass the slurry located in the portion of the
reactor 100 below the sparger arrangements 42. In this fashion, the
overall gas hold-up in the reactor 100 can be reduced, thereby
surprisingly increasing the reactor capacity.
[0104] The gaseous reactants, comprising the fresh synthesis gas
and any recycle gas, pass upwardly through a slurry body 52 which
occupies the slurry channels 16 of the upper and lower sub-reactors
34, 36 and which extends from the bottom of the reactor 100 to the
level 30. The slurry body 52 comprises Fischer-Tropsch catalyst
particles, typically an iron- or cobalt-based catalyst, suspended
in liquid product (mostly wax). The slurry body 52 is controlled to
have the slurry level 30 above the open upper ends of the slurry
channels 16 of the upper sub-reactor 34 and above the degasser
46.
[0105] As the synthesis gas bubbles through the slurry body 52, the
gaseous reactants therein react catalytically and exothermically to
form liquid product, which thus forms part of the slurry body 52.
From time to time, or continuously, slurry or liquid phase
including liquid product is withdrawn through the liquid outlet 26,
with the slurry level 30 thereby being controlled. The catalyst
particles are separated from the liquid product in a suitable
internal or external separation system, e.g. using filters (not
shown). If the separation system is located externally to the
reactor 100, an additional system (not shown) to return the
separated catalyst particles to the reactor 100 is then
provided.
[0106] The fresh synthesis feed gas and the recycle gas are
introduced into the reactor 100 at a rate sufficient to agitate and
suspend all of the catalyst particles inside the reactor 100
without settling. The gas flow rate will be selected depending on
the slurry concentration, catalyst density, suspending medium
density and viscosity, and particular particle size used. Suitable
gas flow rates include, for example, from about 5 cm/s to about 50
cm/s. However, gas velocities up to about 85 cm/s have been tested
in bubble columns. The use of higher velocities has the
disadvantage that it is accompanied by a higher gas hold-up in the
reactor leaving relatively less space to accommodate the
catalyst-containing slurry. Whatever gas flow rate is however
selected, it should be sufficient to avoid particle settling and
agglomeration in the reactor 100.
[0107] Some slurry continuously passes downwardly through the
downcomer 44 and the downcomer zone 48 as indicated by the arrows
50, thereby to achieve redistribution of catalyst particles within
the slurry body 52 and to promote uniform heat redistribution
throughout the slurry body 52. As will be appreciated, depending on
the arrangement of the downcomers or downcomer zones, slurry
redistribution over selected vertically extending regions of the
reactor 100 is possible.
[0108] The reactor 100 is operated such that the slurry body 52 in
the slurry channels 16 is in a heterogeneous or churn-turbulent
flow regime and comprises a dilute phase consisting of fast-rising
larger bubbles of gaseous reactants and gaseous product which
traverse the slurry body 52 virtually in plug flow fashion and a
dense phase which comprises liquid product, solid catalyst
particles and entrained smaller bubbles of gaseous reactants and
gaseous product. By means of the use of the slurry channels 16, the
plug flow behaviour of the entire reactor 100 is promoted, since
each slurry channel 16 has a high aspect ratio when height and
width are considered, which is well in excess of the aspect ratio
of the reactor shell 12.
[0109] Preferably, the downflow rate of slurry in downcomer zones
44 and 48 is sufficiently high, that there is substantially no
downward flow of slurry in the slurry channels 16. In this manner,
the establishment of a macro-mixing pattern other than downward in
the downcomer zones 44 and 48 and upwards in the slurry channels 16
is largely precluded.
[0110] The slurry body 52 is present in alternate, open-ended,
slurry channels 16 in the upper sub-reactor 34 and the lower
sub-reactor 36. Boiler feed water as cooling medium is circulated
through the closed-ended heat transfer medium channels 32 to remove
the heat of the exothermic reactions. As will be appreciated, the
plates 14 provide large heat transfer surface areas for removing
heat from the slurry body 52 by means of indirect heat transfer to
the boiler feed water.
[0111] Light hydrocarbon products, such as a C.sub.20 and below
fraction are withdrawn from the reactor 100 through the gas outlet
22 and passed to a separation unit (not shown). Typically, the
separation unit comprises a series of coolers and a vapour-liquid
separator and may optionally include further coolers and separators
and possibly also a cryogenic unit for removal of hydrogen, carbon
monoxide, methane and carbon dioxide from the C.sub.20 and below
hydrocarbon fraction. Other separation technologies such as
membrane units, pressure swing adsorption units and/or units for
the selective removal of carbon dioxide may be employed. The
separated gases comprising nitrogen, carbon monoxide and other
gases are compressed and recycled by means of a compressor (not
shown) to provide the recycle gas stream. Condensed liquid
hydrocarbons and reaction water are withdrawn from the separation
unit for further working-up.
[0112] It is to be appreciated that, although the reactor 100, as
illustrated, allows for the recycle of gas to the reactor 100, it
is not necessarily so that a recycle gas stream will be employed in
all embodiments.
[0113] As a result of the presence of the plates 14, no slurry flow
communication is possible between the slurry channels 16, at all
elevations between their open upper ends and their open lower ends.
However, above the open upper ends of the slurry channels 16 of the
upper sub-reactor 34, there is no restriction on the flow of
slurry. Similarly, in the intermediate zone 38 and below the open
lower ends of the slurry channels 16 of the lower sub-reactor 36
there is no restriction on the flow of slurry.
[0114] A three-phase slurry reactor in accordance with the
invention may include a plurality of horizontally disposed reactor
modules or sub-reactors, which will thus be at the same elevation
inside the reactor shell 12 but disposed across the cross-sectional
area of the reactor shell 12. In FIGS. 3 and 4, a few of these
horizontally disposed reactor modules or sub-reactors or plate
banks are shown and indicated by reference numeral 60. Associated
with the sub-reactors 60, are downcomer zones indicated by
reference numeral 62. A sparger arrangement 64 is provided below
the sub-reactors 60 and downcomer zones 62.
[0115] As will be noted, the downcomer zones 62 also include a
plurality of vertically extending divider walls or plates 14 in the
same fashion as the sub-reactors 60. However, the sparger
arrangement 64 does not gas the downcomer zones 62, allowing the
zones 62 to function as downcomers and not as sub-reactors or
risers.
[0116] Like the sub-reactors 60, the downcomer zones 62 have slurry
channels and heat transfer medium channels which are alternately
arranged.
[0117] In FIGS. 3 and 4, the height of the sub-reactors 60 and the
downcomer zones 62 are shown as being equal. It is however to be
appreciated that they can be different in height, width and channel
breadth.
[0118] As indicated by the crossed arrows 61 in FIG. 4, there is no
slurry exchange between the sub-reactors 60 or between the
sub-reactors 60 and the downcomer zones 62, except above the open
upper ends of the slurry channels and below the lower open ends of
the slurry channels.
[0119] The parallel plates of a sub-reactor or plate bank may
define channels 16 with open sides, as shown in FIG. 13, or the
sub-reactors may have side walls 63 as shown in FIG. 14. When the
sides of the channels 16 are closed by side walls 63, as shown in
FIG. 14, there can be no interaction between the slurry in the
channels 16 of one such sub-reactor with the slurry in the channels
16 of an adjacent sub-reactor, unless apertures are provided in the
side walls 63. Naturally, side walls may enclose more than one
sub-reactor or plate bank.
[0120] When two sub-reactors are arranged with their plates 14
parallel, as shown in FIG. 15, and in the absence of side walls,
slurry in the channels 16 of one sub-reactor can interact with the
slurry in the channels 16 of the adjacent sub-reactor. When the
plates 14 of adjacent sub-reactors are perpendicular, as shown in
FIG. 16, the end plate of one sub-reactor in effect defines a side
wall, preventing interaction between slurry in the channels 16 of
the two sub-reactors.
[0121] Referring to FIG. 5 of the drawings, upper sub-reactors 34
and lower sub-reactors 36 as well as two downcomers or downcomer
zones 62 are shown. Two sparger arrangements 64, one below the
upper sub-reactors 34 and one below the lower sub-reactors 36, are
also shown. In the reactor layout shown in FIG. 5, the downcomers
or downcomer zones 62 extend from the upper open ends of the slurry
channels of the upper sub-reactors 34 through the intermediate zone
38 to below the open lower ends of the lower sub-reactors 36 and in
fact to below the lower sparger arrangement 64. With this
arrangement, large scale axial circulation of slurry in a known and
controlled pattern can be achieved. It is also possible to allow
for limited slurry exchange between adjacent sub-reactors 34.a and
34.b or 36.a and 36.b. As will be appreciated, the slurry channels
can be designed to have a desired heat transfer surface area,
hydraulic diameter, etc. If desired, additional gas sparging can be
installed in between vertically spaced sub-reactors, in the
intermediate zone 38 and internal filtration devices can be
installed in the intermediate zone 38 or in one of the downcomers
or downcomer zones 62. One advantage of placing internals such as
filters in a downcomer or downcomer zone is the reduced gas hold-up
and relatively high velocities encountered in a downcomer zone. By
selecting the locations of the downcomers or downcomer zones 62 and
placing them in particular positions on the cross-sectional area of
the reactor shell 12, large scale slurry circulation can be
severely influenced to achieve desired objects.
[0122] Downcomers or downcomer zones can be helpful in levelling
the solids hold-up profile and temperature profile over the height
of a three-phase slurry reactor. At the same time, however, they
induce axial mixing, which sometimes may not be desirable. By
design, the axial mixing can be promoted (resulting in a kind of
riser-downcomer mode of operation) or it can be suppressed in order
to promote plug flow characteristics for the reactor.
[0123] FIGS. 6 to 9 show various embodiments of three-phase slurry
reactors in accordance with the invention, with various downcomer
arrangements. In FIG. 6, the reactor has four vertically spaced
sub-reactors or plate banks, with no downcomer. In FIG. 3, it is
shown that a top to bottom downcomer, extending linearly axially
through the sub-reactors or plate banks, can be employed. FIG. 8
illustrates how downcomers in each sub-reactor or plate bank can be
arranged so that the downcomers, when viewed in plan, are staggered
between upper and lower sub-reactors or plate banks. FIG. 9
illustrates a three-phase slurry reactor with divider walls or
plates extending substantially the entire length of the reactor,
from a bottom region to a head space region, with a single
downcomer extending from the head space to the bottom region.
[0124] Various arrangements of downcomers or downcomer zones are
shown in FIGS. 17 to 20 in which the downcomers or downcomer zones
are indicated by reference numeral 70. In FIG. 17, the downcomer
zones 70 are distributed across the cross-sectional area of the
reactor shell 12. In FIG. 18, the downcomer zone 70 is adjacent the
reactor shell 12, being roughly annular in plan view. The downcomer
zone 70 in FIG. 19 is against one side of the reactor shell 12 and
in FIG. 20, the downcomer zone 70 is centrally located.
[0125] By means of the arrangement selected for the sub-reactors
and downcomer or downcomer zones, it is possible to allow or
prevent slurry flow interaction between different upflow zones in
the reactor (defined by the slurry channels), and to prevent or
deny interaction between these upflow zones and downflow zones
(defined by the downcomers or downcomer zones). Thus, in a reactor
such as the reactor 100, at a particular elevation such as the
elevation indicated by reference numeral 72 in FIG. 2, many
configurations are possible, some of which are shown in FIGS. 21 to
28 of the drawings.
[0126] In FIG. 21, the downflow zones 70 are against the sides of
the reactor shell 12. Each sub-reactor, indicated by reference
numeral 74 has side walls, thereby preventing slurry interaction
between the sub-reactors 74, and between the sub-reactors 74 and
the downflow zones 70.
[0127] The sub-reactors 74 in FIG. 22 do not have side walls and
the slurry channels of adjacent sub-reactors 74 are parallel. The
slurry in these slurry channels can thus interact. In contrast, in
FIG. 23, the slurry channels of adjacent sub-reactors 74 are
arranged perpendicularly. The individual sub-reactors 74 do not
have side walls, although the group of twenty-five sub-reactors has
a side wall 76. The sub-reactors 74 are spaced slightly, allowing
limited slurry interaction between adjacent sub-reactors 74 but
with the perpendicular arrangement of the plates preventing a more
free slurry interaction between adjacent sub-reactors 74. No slurry
interaction is allowed between the upflow zones, i.e. the
sub-reactors 74 and the downcomer zones 70.
[0128] In FIG. 24, the sub-reactors 74 are all provided with side
walls and the downcomer zones 70 are distributed. There is thus no
slurry interaction between the sub-reactors 74, or between the
sub-reactors 74 and the downcomer zones 70. In contrast, in FIG.
25, the sub-reactors 74 do not have side walls and the downcomer
zones 70 are only adjacent the shell 12. Substantial slurry
interaction between the sub-reactors 74, and between the
sub-reactors 74 and the downcomer zones 70 can take place. In FIG.
26, the sub-reactors 74 are again without side walls, but many are
arranged with their slurry channels perpendicular to the slurry
channels of adjacent sub-reactors 74. Although there will thus be
some interaction between adjacent sub-reactors 74 and between the
sub-reactors 74 and the downcomer zones 70, the slurry interaction
will be more limited than in the case of the reactor shown in FIG.
25.
[0129] FIG. 27 shows a reactor similar to the reactor shown in FIG.
26, but in the case of the reactor of FIG. 27, the downcomer zones
70 are disposed across the cross-sectional area of the reactor.
[0130] In FIG. 28, the downcomer zone 70 is located against one
side of the reactor shell 12. There is limited slurry interaction
between the sub-reactors 74 as a result of the slight spacing
between the sub-reactors 74, although they are arranged at
perpendicular angles. A barrier or side wall 76 substantially
prevents slurry interaction between the slurry in the sub-reactors
74 and the slurry in the downcomer zone 70.
[0131] Various gas sparging strategies are shown in FIGS. 10 to 12.
In FIG. 10, the gas is introduced in two stages, a portion of the
gas entering a bottom region of the reactor and another portion of
the gas entering an intermediate zone between two sub-reactors or
plate banks. In FIGS. 11 and 12, the gas spargers are shown in
combination with downcomers or downcomer zones. As can be clearly
seen, it is possible to gas only a portion of the cross-sectional
area of the reactor, in both the bottom and in the intermediate
zones.
[0132] The method and apparatus of the present invention therefore
allow for much reduced risk when upscaling slurry flow reactor
designs, since the formation of macro-scale mixing patterns are
largely prevented by the presence of slurry channels. In addition,
and especially for designs including downcomers or downcomer zones,
the reaction zone consists of a number of slurry channels in which
a known upward superficial liquid flow rate and a known upward
superficial gas velocity exist. These slurry channels are amenable
to piloting and modelling, giving the designer a greater degree of
control over the large scale reactor mixing patterns. Furthermore,
the slurry channels are formed by heat exchanger surfaces. This
leads to much improved heat removal ability for these designs over
standard designs in which serpentine cooling coils are employed.
Not only is the available heat removal surface area increased, but
also more uniformly spread over the reactor.
* * * * *