Note: Descriptions are shown in the official language in which they were submitted.
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REACTOR FOR PARTIAL OXIDATION WITH HEAT-TRANSFER
SHEET MODULES
The invention relates to a reactor for partial oxidations of a fluid reaction
mixture in the
presence of a heterogeneous particulate catalyst, and also to its use.
In chemical process technology, a multitude of partial oxidation reactions of
fluid, i.e.
gaseous, liquid or gaseous/liquid, reaction mixtures are known and are carried
out in the
presence of heterogeneous particulate catalysts. Such reactions are generally
exothermic,
frequently strongly exothermic. On the industrial scale, they have hitherto
been carried out
predominantly in tube bundle reactors having catalyst tubes, in which the
heterogeneous
particulate catalyst is installed and through which the fluid reaction mixture
is passed, and the
heat of reaction which is released is removed indirectly via a heat carrier
which circulates in
the intermediate space between the catalyst tubes. The heat carrier used is
frequently a salt
melt.
As an alternative, it is also possible to remove the heat of reaction via a
heat carrier which is
passed through plate-type heat transferors. The terms heat exchanger plates,
heat transferor
plates and thermoplates are used substantially synonymously for plate-type
heat exchangers.
Heat transferor plates are defined predominantly as sheetlike structures which
have an interior
provided with inlet and outlet lines and having a low thickness in comparison
to the surface
area. They are generally produced from metal sheets, frequently from steel
sheets. However,
depending on the application case, in particular the properties of the
reaction medium and of
the heat carrier, special, in particular corrosion-resistant, or else coated
materials may be used.
The inlet and outlet devices for the heat carriers are generally arranged at
opposite ends of the
heater exchange plates. The heat carriers used are frequently water, or else
Diphyl (mixture
of from 70 to 75% by weight of diphenyl ether and from 25 to 30% by weight of
diphenyl),
which sometimes also evaporate in a boiling procedure; it is also possible to
use other organic
heat carriers having a low vapor pressure and also ionic liquids.
The use of ionic liquids as heat carriers is described in the German patent
application 103 16
418.9 which was unpublished at the priority date of the present application.
Preference is
given to ionic liquids which contain a sulfate, phosphate, borate or silicate
anion. Also
particularly suitable are ionic liquids which contain a monovalent metal
cation, in particular
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an alkali metal cation, and also a further cation, in particular an
imidazolium cation. Also
advantageous are ionic liquids which contain an imidazolium, pyridinium or
phosphonium
cation as the cation.
The term thermoplates is used in particular for heat transferor plates whose
single, usually
two, metal plates are joined together by point and/or roll welds and are
frequently shaped
using hydraulic pressure plastically to form pockets.
In the present context, the term thermoplates is used in the sense of the
above definition.
Reactors for carrying out partial oxidations using thermoplates are known, for
example, from
DE-A 199 52 964. The arrangement is described of a catalyst for carrying out
partial
oxidations in a bed around heat transferor plates in a reactor. The reaction
mixture is fed at
one reactor end to the reactor interior between the heat transferor plates and
removed at the
opposite end and thus flows through the interior between the heat transferor
plates. As a
result, there is constant transverse mixing of the reaction mixture with the
consequence of
high homogeneity thereof, and, for a predefined conversion, a substantially
better selectivity
is achieved compared to carrying out the reaction in a tube bundle reactor.
DE-C 197 54 185 describes a further reactor having indirect heat removal via a
cooling
medium which flows through the heat transferor plates, the heat transferor
plates being
designed as thermal plates which consist of at least two steel plates which
are joined together
at predefined points to form flow channels.
An advantageous development thereof is described in DE-A 198 48 208, according
to which
heat transferor plates which are configured as thermal plates flowed through
by a cooling
medium are combined to plate assemblies having, for example, rectangular or
square cross
section, and the plate assemblies have a casing. The encased plate assembly
needs no
adaptation on the circumferential side and is consequently used with
predefined spacings to
the interior wall of the cylindrical reactor vessel. The free surfaces between
the plate heat
transferor or its casing and the vessel interior wall are covered in the upper
and lower regions
of the casing with guide plates, in order to prevent the reaction medium from
bypassing the
chambers filled with catalyst.
A further reactor having devices for removing the heat of reaction which are
in the form of
plate heat transferors is described in WO-A01/85331. The reactor of
predominantly
cylindrical shape contains a continuous catalyst bed, into which a plate heat
transferor is
embedded.
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Extended experiments on reactors having thermoplates have shown that
problems occur in particular by deformation as a consequence of high stress
on one side of the thermoplates at too high a pressure differential between
the reaction mixture and the external environment, and also mechanical
stability problems as a result of deformation under high thermal stress. These
problems can occur when the reaction mixture is under elevated pressure, but
also when the reaction is operated at reduced pressure.
It is an object of the present invention to provide a reactor which has
removal
of the heat of reaction via a heat carrier which flows through thermoplates,
and can be operated in an economic and trouble-free manner, in particular
avoiding the problems illustrated above. The invention should ensure the
geometric stability of the thermoplate modules, particularly of the gaps
designated to accommodate the catalyst.
We have found that this object is achieved by a reactor for partial oxidations
of a fluid reaction mixture in the presence of a heterogeneous particulate
catalyst, comprising
- one or more cuboidal thermoplate modules which are each formed from two
or more rectangular thermoplates arranged parallel to each other while in
each case leaving a gap which can be filled with the heterogeneous
particulate catalyst and is flowed through by the fluid reaction mixture, the
heat of reaction being absorbed by a heat carrier which flows through the
thermoplates and thus at least partly evaporates, and also having
- a predominantly cylindrical shell which releases the pressure at the
thermoplate modules, completely surrounds them and comprises a cylinder
jacket and hoods which seal it at both ends and whose longitudinal axis is
aligned parallel to the plane of the thermoplates, and also having
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- one or more sealing elements which are arranged in such a way that the
fluid reaction mixture, apart from flowing through the reactor interior spaces
bounded by the hoods, only flows through the gap.
An embodiment of the invention relates to a reactor for partial oxidations of
a
fluid reaction mixture in the presence of a heterogeneous particulate
catalyst,
comprising:
= at least one cuboidal thermoplate module that includes at least two
rectangular thermoplates arranged parallel to each other such that a
gap in the at least one cuboidal thermoplate module between
respective adjacent rectangular thermoplates is configured to be filled
with the heterogeneous particulate catalyst and is configured to
receive a flow of the fluid reaction mixture, the at least two rectangular
thermoplates being configured to receive a flow of a heat carrier that is
configured to absorb a heat of reaction between the fluid reaction
mixture and the heterogeneous particulate catalyst and at least partly
evaporate;
= a cylindrical shell configured to release a pressure formed at the at
least one cuboidal thermoplate module, the shell completely
surrounding the at least one cuboidal thermoplate module and
including
o a cylinder jacket,
o a bottom hood configured to seal a bottom end of the shell,
o a top hood configured to seal a top end of the shell,
o a longitudinal axis that is aligned parallel to a vertical plane of
the at least two thermoplates,
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o a first interior space between the bottom hood and a bottom
portion of the at least one cuboidal thermoplate module, and
o a second interior space between a top portion of the at least
one cuboidal thermoplate module and the top hood; and
= at least one sealing element arranged to limit the flow of the fluid
reaction mixture within the shell from the first interior space to the
second interior space to only flow through the gap.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein the reactor includes at least two
cuboidal thermoplate modules each having the same dimensions. More
preferably, the reactor may comprise 4, 7, 10 or 14 thermoplate modules.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein the at least two thermoplates include
two rectangular metal sheets joined at longitudinal and end sides by roll seam
welding, and wherein an edge of the two rectangular metal sheets that
protrudes over the roll seam is removed at an outer edge of the roll seam or
in the roll seam itself. More preferably, each of the at least one cuboidal
thermoplate modules may be arranged in a pressure-stable rectangular
stabilization frame. Much more preferably the reactor may include at least two
cuboidal thermoplate modules, and rectangular stabilization frames of
adjacent cuboidal thermoplate modules may be welded and sealed together.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein the at least one sealing element is a
holding base which seals an intermediate space between the at least one
cuboidal thermoplate module and the cylindrical shell at the bottom portion of
the at least one cuboidal thermoplate module. More preferably, a metal sheet
cover may seal the intermediate space between the thermoplate modules and
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the cylindrical shell at the top portion of the at least one cuboidal
thermoplate
module. Much more preferably, the metal sheet cover may include a plurality
of orifices.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein an intermediate space between the
at least one cuboidal thermoplate module and the shell is filled with an inert
material. More preferably, the inert material may be expanded perlite or
expanded vermiculite.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein pressure is applied to an
intermediate space between the at least one cuboidal thermoplate module
and the cylindrical shell with a gas. More preferably, the pressure applied
may
be constant. Much more preferably, the constant application of pressure may
be effected by pressure-regulated feed and removal of nitrogen.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein pressure is applied to an
intermediate space between the at least one cuboidal thermoplate module
and the cylindrical shell with a gas, and wherein the pressure is applied by
continuously feeding the gas through the intermediate space, and wherein the
gas is inert or intrinsic to the process. More preferably, the gas may be
combined with the fluid reaction mixture at an outlet from the thermoplate
modules.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment wherein compensators for radial expansion
are provided in or on the holding base.
= CA 02532646 2011-09-13
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Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment wherein compensators for axial or radial
expansion are provided in or on the metal sheet cover.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment wherein each thermoplate module includes at
least one distribution device and at least one collection device configured to
receive the heat carrier.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment wherein each thermoplate module includes
one distribution device and two collection devices configured to receive the
heat carrier.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment further comprising a plurality of distribution
and collection devices that are configured to receive the heat carrier and
that
have equal nominal widths.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment further comprising a plurality of distribution
devices and collection devices that are configured to receive the heat carrier
and that are welded into a slotted base.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment further comprising a plurality of distribution
devices and collection devices that are configured to receive the heat carrier
that flows through the thermoplates and that each include compensation for
the accommodation of the thermal expansion of the thermoplate modules
relative to the cylindrical shell.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment wherein a thermal expansion of the
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thermoplate modules relative to the cylindrical shell is accommodated by a
curved geometric design of a tubing of a plurality of distribution devices and
collection devices that are configured to receive the heat carrier that flows
through the thermoplates.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment wherein each thermoplate modules includes
two catalyst holding grates per thermoplate module.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment further comprising manholes configured to
facilitate the introduction of a plurality of catalyst holding grates into the
cylinder jacket.
Another embodiment of the invention relates to a reactor as defined in the
above-mentioned embodiment, wherein the cylinder jacket includes at least
one compensator configured to accommodate axial thermal expansion.
The invention therefore provides thermoplate modules which comprise
thermoplates, through which a heat carrier flows, absorbs the heat of reaction
and thus at least partly evaporates, and are configured with a cuboidal shape
and are installed with pressure release in a predominantly cylindrical shell
which completely surrounds them.
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The plate modules are formed from in each case two or more rectangular
thermoplates which
are arranged parallel to each other while in each case leaving a gap.
The thermoplates are manufactured from corrosion-free materials, preferably
from stainless
steel, for example having the materials number 1.4541 or 1.4404, 1.4571 or
1.4406, 1.4539 or
else 1.4547, or from other alloyed steels.
The material thickness. of the metal sheets used for this purpose may be
selected between 1
and 4 mm, 1.5 and 3 mm, or else between 2 and 2.5 mm, or as 2.5 mm.
In general, two rectangular metal sheets may be joined at the longitudinal and
end sides to
give a thermoplate, in which case a roll seam or lateral weld joint or a
combination of both is
possible so that the space in which the heat carrier is later disposed is
sealed on all sides. The
edge of the thermoplates is advantageously removed at or even in the lateral
roll seam of the
longitudinal edge so that the edge region, which is poorly cooled if at all,
and in which
catalyst is usually also installed, has a very low geometric expansion.
The metal sheets are joined together by point welding distributed over the
rectangular surface.
An at least partial connection by straight or else curved and also circular
roll seams is also
possible. It is also possible for the volume flowed through by the heat
carrier to be divided by
additional roll seams into a plurarity of separate regions.
One possibility of arranging the weld points on the thermoplates is in rows
with equidistant
point separations of from 30 to 80 mm or else from 35 to 70 mm, although
separations of 40
to 60 mm are also possible and a further embodiment has separations of from 45
to 50 mm
and also from 46 to 48 mm. Typically, as a result of the manufacture, the
point separations
vary by up to 1 mm and the weld points of immediately adjacent rows, viewed
in the
longitudinal direction of the plates, are each arranged offset by half a weld
point separation.
The rows of the point welds in the longitudinal direction of the plates may
equidistant with
separations of from 5 to 50 mm, or else from 8 to 25 mm, although separations
of from 10 to
20 mm and also from 12 to 14 mm, may also be used. Moreover, pairings of the
weld point
separations and row separations mentioned which are adapted to the application
case are also
possible. The row separations may be in a defined geometric relationship to
the point
separation, typically 1/4 of the point separations or somewhat lower, so that
there is a defined
uniform expansion of the thermoplates in the course of the production. For
predefined weld
point and row separations, a corresponding number of weld points per m2 of
plate surface area
is designated.
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width of the thermoplates is limited substantially by manufacturing technology
The
considerations and may be between 100 and 2500 mm, or else between 500 and
1500 mm.
The length of the thermoplates is dependent upon the reaction, in particular
upon the
temperature profile of the reaction, and may be between 500 and 7000 mm, or
else between
3000 and 4000 mm.
In each case two or more thermoplates are arranged parallel and separated from
one another to
form a thermoplate module. This results in shaftlike gaps forming between
immediately
adjacent plates which, at the narrowest points of the plate separation, for
example, have a
width of between 8 and 150 mm, or else from 10 to 100 mm. One possible
embodiment is
also widths of from 12 to 50 mm or else from 14 to 25 mm, although from 16 to
20 mm may
also be selected. A gap separation of 17 mm has also been tested.
Between the individual thermoplates of a thermoplate module, for example in
the case of
large-surface-area plates, spacers can additionally be installed in order to
prevent
deformations which can change plate separation or position. To install these
spacers, sections
of the metal plates can be removed from the flow region of the heat carrier,
for example by
circular roll seams, in order, for example, to be able to introduce holes into
the plates for
securing screws of the spacers.
The gaps may have the same separation, but, if required, the gaps may also be
of different
width when the reaction permits it or the desired reaction requires it, or
apparatus or cooling
technology advantages can be achieved.
The gaps of a thermoplate module filled with catalyst particles may be sealed
with respect to
each other, for example sealed by welding, or else be joined together on the
process side.
To adjust the desired gap separation when joining the individual thermoplates
together to
form a module, the plates are secured in their position and in separation.
The weld points of immediately adjacent thermoplates may be opposite each
other or offset
from each other.
In general, preference is given for manufacturing reasons to configuring the
arrangement with
two or more cuboidal thermoplate modules with in each case identical
dimensions. In the case
of arrangements of 10 or 14 thermoplate modules, it may be advantageous for
the
compactness of the overall apparatus to select two module types having
different edge length
or different edge length ratios.
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Preference is given to arrangements of 4, 7, 10 or 14 thermoplate modules
having in each case
identical dimensions. The projection surface of a module which is visible in
the flow direction
may be square, or else rectangular is a side ratio of 1.1 or else 1.2.
Combinations of 7, 10 or
14 modules having rectangular module projections are advantageous, so that the
diameter of
the external cylindrical shell is minimized. Particularly advantageous
geometric arrangements
can be achieved when, as detailed above, a number of 4, 7 or 14 thermoplate
modules is
selected.
It should advantageously be possible in this connection to exchange the
thermoplate modules
individually, for example in the case of leaks, deformations of the
thermoplates or in the case
of problems which affect the catalyst.
Advantageously, the thermoplate modules are each arranged in a pressure-
stable, rectangular
stabilization frame.
Each thermoplate module is advantageously kept in position by a suitable
guide, for example
by the rectangular stabilization frames, with a laterally penetrating wall,
or, for example, by
an angle construction.
In one embodiment, the rectangular stabilization frames of adjacent
thermoplate modules are
sealed with respect to each other. This prevents bypass flow of the reaction
mixture between
the individual thermoplate modules.
The installation of cuboidal thermoplate modules into a predominantly
cylindrical pressure-
rated shell results in relatively large free intermediate spaces remaining at
the edge toward the
cylindrical jacket wall of the shell, in which accumulation, side reactions or
decomposition of
the material product can take place. Cleaning or decontamination of product,
for example in
the event of the necessity of assembly operations, is only possible there with
great difficulty.
It is therefore advantageous to separate this intermediate space from the
reaction chamber, i.e.
from the gaps between in each case immediately adjacent thermoplates.
To this end, the intermediate space between the thermoplate modules and the
predominantly
cylindrical shell is sealed at the lower end of the thermoplate module with a
holding base. In
order to prevent bypass flow of the reaction mixture, the bearing or holding
base should seal
the intermediate space gas-tight.
Advantageously, the intermediate space between the thermoplate modules and the
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predominantly cylindrical shell may also be sealed at the upper end of the
thermoplate module
by a metal sheet cover. However, a gas-tight seal is not necessary for this
purpose; it is
possible in one embodiment to configure the metal sheet cover with orifices.
The metal sheet cover at the upper end of the intermediate space between the
thermoplate
modules and the predominantly cylindrical shell may advantageously also be
configured
similarly to a valve tray.
The venting of the gas used to apply pressure may also be produced by means of
an overflow
unit, configured as a perforated plate, valve or force-loaded (for example
with a spring or gas
pressure), self regulating unit, also in combination with a blowback
safeguard. These
overflow units may also be disposed outside the cylindrical external shell.
The upper metal sheet cover may rest on struts which additionally stabilize
the rectangular
stabilization frames in which the thermoplate modules are installed.
The intermediate space between the thermoplate modules and the predominantly
cylindrical
shell may advantageously be filled with inert materials, in order to reduce
the free gas volume
there and in order to prevent gas convection which may lead, for example, to
uncontrolled
heat release.
In the cylindrical shell, it is advantageous to provide nozzles for the inlet
and outlet of the
inert bed material which are configured in suitable size and mounted at a
suitable angle in
such a way that blockage-free filling and emptying is possible under the force
of gravity.
Possible embodiments of the nozzles are nominal widths of 80, 100, 150 or 200
mm.
The inert material bed used may in principle be any chemically inert and
sufficiently
mechanically and thermally stable material, for example expanded perlite
and/or expanded
vermiculite.
It is possible to charge the intermediate space between the thermoplate
modules and the
predominantly cylindrical shell, which may be filled with inert material, with
a gas pressure.
The application of pressure may be substantially constant and advantageously
brought about
by the pressure-regulated input and output of nitrogen. The regulation signal
selected may be,
for example, the pressure differential between the pressure in the
intermediate space between
the thermoplate modules and the predominantly cylindrical shell and the
pressure at the lower
end of the catalyst bed in the gaps of the thermoplate modules or at the upper
end thereof.
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Advantageously, the differential pressure signal may be corrected by an offset
value; a mean
value, in particular the arithmetic mean value, of the pressure over the
height of the catalyst
bed may preferably be selected as the regulation signal.
To apply pressure, appropriate nozzles and/or an internal ring line having
small drillholes,
which are preferably directed downward, may be provided in the predominantly
cylindrical
shell.
Alternatively, it is also possible to bring about the application of pressure
with continuous
flow through the intermediate space with a gas which is inert or intrinsic to
the process, in
particular nitrogen or cycle gas.
The gas used to apply pressure is advantageously combined with the fluid
reaction mixture at
its outlet from the thermoplate modules, generally still within the
predominantly cylindrical
shell of the reactor. The outlet points of the gas used for pressure charging
are advantageously
located in flow dead zones of the fluid reaction mixture, in order to purge
them.
The flow rate of the gas used to apply pressure will generally be
significantly less than the
flow rate of the fluid reaction gas mixture and is advantageously selected in
such a way that it
is not harmful to the reaction in process technology terms.
The thermoplate modules should advantageously each be individually
exchangeable, in order
that, as already outlined above, problems which occur, for example leakages,
deformations of
the thermoplates or problems with the catalysts, can be remedied in a targeted
manner. For
this purpose, it is advantageous to configure the thermoplate modules with
some play with
respect to the wall of the rectangular stabilization frames.
Since the thermoplate modules in this advantageous embodiment rest in the
rectangular
stabilization frames without sealing, bypass flows of the reaction medium, may
occur. In order
to prevent this, the sites between the thermoplate modules and the rectangular
stabilization
frames where there is no seal are sealed in a suitable manner, for example
with metal sheet
strips which are mounted on the exterior of the thermoplate modules and press
onto the wall
of the rectangular stabilization frame when inserted into it. Alternatively,
gas-tight metal sheet
covers and connections, for example in the form of weld lip seals are
possible.
Once the thermoplate modules have been inserted into the rectangular
stabilization frames,
they can be sealed with respect to the holding base, which seals the
intermediate space
between the thermoplate modules and the predominantly cylindrical shell at the
lower end of
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the thermoplate modules. It is possible in principle to use any known sealing
means for this
purpose. These may be, for example, conventional seals which, for example, are
additionally
screw-secured.
It is also possible to bring about the sealing by weld lips, for example, by a
variant in which a
weld lip is secured to the holding base and a second weld lip to the outer
edge of the
thermoplate module or of the rectangular stabilization frame. Both weld lips
are configured in
such a way that they fit together geometrically and can be welded together. To
exchange the
thermoplate module, the weld seam is separated and, if required, renewed.
The thermoplate modules can be tensioned from above with the rectangular
stabilization
frames by a device. Sufficient tensile pressure from above ensures adequate
surface pressure
on the seal and advantageous securing of the thermoplate modules.
It is not obligatory for the rectangular stabilization frames to be sealed
with respect to each
other, as long as an impermissible bypass flow past the gaps is prevented. It
is also possible to
connect the rectangular stabilization frames together with small drillholes,
through which the
inert gas can flow in from the intermediate space and between thermoplate
modules and the
predominantly cylindrical shell, which prevents reactions in the space between
the
thermoplate module and the rectangular stabilization frame.
The thermoplate modules may additionally have guiding and directing elements
on the
exterior. It is possible, for example, to provide corner brackets of any form
on the corners of
these elements and conical metal sheet strips on their side. It is also
advantageous to mount
attachment devices or attachment auxiliaries on the modules, such as eyes,
loops or threaded
drillholes, in order to enable simple insertion by means of a hoist or, for
example, of a crane.
To insert the thermoplate modules by crane, they can also be held on tie bars
which reach
vertically through the initially empty gap down to the lower edge of the
plates and are
connected there to a transverse support to take up the load.
In a particular embodiment, the outermost thermoplate of a thermoplate module,
at the
exterior thereof, is formed from a thicker and therefore more stable metal
sheet than the other
metal sheets used to produce the thermoplates.
To compensate for the thermal expansion, annular compensators in particular
are
advantageously provided in or on the holding base which seals the intermediate
space
between the thermoplate modules and the predominantly cylindrical shell at the
lower end of
the thermoplate modules. Annular compensation with an approximately z-shaped
profile
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viewed in the direction at right angles to the surface of the metal sheet base
is particularly
suitable. However, other conventional, wave-shaped compensators are equally
suitable.
Preference is also given to also providing compensators for the axial and/or
radial expansion
in or on the metal metal sheet cover at the upper end of the intermediate
space between
thermoplate modules and predominantly cylindrical shell.
Each thermoplate module is supplied with the heat carrier by one or more
distribution devices.
The heat carrier, after flowing through the interior in the individual
thermoplates, is removed
at the other end of the thermoplate module via one or more collection devices.
Since, in
accordance with the invention, a heat carrier is used which absorbs the heat
of reaction
released and thus partly evaporates, it is particularly advantageous for the
adjustment of the
flow rates to provide in each case one distribution device, but two collection
devices, per
thermoplate module.
The distribution and collection devices are preferably configured in such a
way that they each
have a compensation for the accommodation of the thermal expansion of the
thermoplate
modules relative to the surrounding predominantly cylindrical shell.
Compensation is possible
here, for example, by a curved pipeline design.
To accommodate the thermal expansion of the thermoplate modules relative to
the
surrounding predominantly cylindrical shell, it is possible to ensure a
suitable curved or Z- or
omega-shaped geometric configuration of the tubing of the distribution and
collection devices
for the heat carrier flowing through the thermoplates. In a further
embodiment, this
compensation may be effected by axial or lateral compensators, in which case
any pipe
support required may be effected on an internal support structure.
Particular preference is given to configuring the collection tubes in the
thermoplates for the
feed and distribution, and also collection and removal, of the heat carrier by
welding into a
slotted tray as follows: the individual thermoplates of a module are initially
joined to a
channel-shaped metal sheet which is curved toward the interior of the
thermoplates and has an
approximately semicircular cross section and also orifices or slits for the
output of the heat
exchanger. At this stage of manufacture, it is possible to check that the
weldings into the
slotted tray are free of manufacturing faults, even in a representative
specimen or else in the
whole area, for example by X-ray. Subsequently, this first, approximately
channel-shaped
metal sheet is joined on both longitudinal sides to a second similarly shaped
metal sheet,
except having opposite curvature and no orifices or slots, in particular by
longitudinal seam
welding, to form a tubular component having virtually circular cross section.
The two ends of
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this tubular component are sealed by lids which may optionally be strengthened
by an internal
tie rod.
In a further embodiment, it is also possible to directly weld tube parts
having a relatively
small nominal width of, for example, from 4 to 30 mm, onto the thermoplates,
frequently onto
the metal sheet edges, to feed and remove the heat carrier.
The gaps between the individual thermoplates of each thermoplate module serve
to
accommodate the heterogeneous particulate catalyst.
In order to rule out flow of the catalyst particles out of the gaps under the
influence of gravity,
catalyst grates have to be provided at the lower end thereof. This may be
effected, for
example, with perforated or mesh plates, and it is particularly advantageous
for this purpose
to use edge gap sieves, which ensure good retention of the catalyst with
simultaneously high
dimensional stability and low pressure drop for the reaction medium flowing
through.
The catalyst retention grates may be installed, for example, in such a way
that they can be
swiveled.
It is particularly advantageous when the distribution devices for the heat
carrier to the
thermoplates are installed in such a way that the lateral separations from the
distribution
devices to the edge of the thermoplate assembly are the same, so that only a
single type of
catalyst-retaining grate is required. In each case two catalyst-retaining
grates are provided per
thermoplate module, i.e. on both sides of the distribution device for the heat
carrier.
The catalyst-retaining grates are advantageously dimensioned in such a way
that they can
installed and deinstalled via the manholes in the approximately cylindrical
shell. The
manholes frequently have an internal diameter of 700 mm. Correspondingly,
preference is
given to an edge length for the catalyst inlay grates of 650 mm.
In a further embodiment, it is possible to further divide these retaining
grates into smaller
units, but also to individually seal each gap or each gap half individually,
so that it can also be
emptied separately.
Alternatively, it is also possible to fill the thermoplate modules with
catalyst before they are
installed into the reactor, i.e. outside the reactor.
The shell surrounding the thermoplate modules has been described above as
predominantly
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cylindrical. In this context, this means that it has a cylindrical jacket with
circular cross
section which is sealed at both ends in each case by a hood.
The predominantly cylindrical shell is generally installed vertically.
The fluid reaction medium is passed into the reactor interior via one hood,
frequently via the
lower hood, flows through the gap which is filled with the heterogeneous
particulate catalyst
and is between the individual thermoplates, and is removed at the other end of
the reactor, via
the other, frequently the upper, hood.
The hoods are preferably manufactured from stainless steel or are stainless
steel-plated.
The hoods may be connected to the cylinder jacket of the shell by secure
welding or
separably, for example via a flanged connection. The flange connection may be
configured in
such a way that it can be lowered by means of a hydraulic system.
It is advantageously possible to reach the circumference of the hoods on foot
via one of more
manholes which generally have a diameter of 700 mm. For this purpose, a
widened
cylindrical section is advantageous, which, like the hood, is, for example,
manufactured from
stainless steel or is stainless steel-plated.
It is possible via the manholes in the hoods to access the upper side of the
modules, so that the
catalyst can be introduced into the gaps between the thermoplates, and to the
lower side of the
modules, so that the retaining grids can be installed and de-installed easily.
To deinstall the catalyst, devices may additionally be installed in the lower
hood to retain
auxiliaries and to collect the catalyst, which may have already been installed
in the course of
operation, and also one or more nozzles to discharge the catalyst.
The material used for the holding base sealing the intermediate space between
the thermoplate
modules and the interior wall of the predominantly cylindrical shell , and for
the rectangular
stabilization frames for the thermoplate modules too, may be carbon steel.
Alternatively, it is
possible to use stainless steel for this purpose.
In one or both hoods, it is advantageous to install nozzles, through which
multithermoelements can be introduced into the individual thermoplate modules.
In addition,
nozzles may be mounted there for further field instruments and process
analytical devices.
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Preference is given to providing, in the cylindrical jacket of the
predominantly cylindrical
shell, one or more compensators to accommodate preferably the axial thermal
expansion.
The invention provides the use of a reactor for carrying out partial
oxidations of a fluid
reaction mixture, in which the heat of reaction is removed by a heat carrier
flowing through
the thermoplates which thus at least partly evaporates.
In this case, the reactor, especially in strongly exothermic reactions, is
operated in such a way
that the fluid reaction mixture is fed via the lower hood and removed from the
reactor via the
upper hood.
Since the heat carrier medium, which removes the heat of reaction in
particular by evaporative
cooling, is passed from below into the thermoplates, when the reaction mixture
is fed from
below, i.e. when there is cocurrent flow of reaction mixture and heat carrier,
sufficient heat
carrier is always available.
In addition, both in terms of construction and the flow control of the
reaction medium and the
operation, it has to be ensured that neither is the reaction medium
excessively cooled by
supercooled heat carrier before it reaches the active catalyst zone, nor is
the heat carrier pre-
evaporated to an impermissibly high degree.
The heat carrier medium used may be feed water as typically utilized in power
stations for
steam generation and corresponding to the prior art (Technische Regeln fur
Dampfkessel
[Technical rules for vapor vessels] (TRD 611 of October 15, 1996 in BArbBl.
12/1996 p. 84,
last altered on June 25, 2001 in BArbBI. 8/2001 p. 108). Typical parameters of
the feed water
may be: conductivity less than 0.4, or less than 0.2, microsiemens/cm, calcium
and
magnesium hardness less than 0.005 millimole per liter or below the detection
limit, sodium
less than 5 micrograms per liter, silicon dioxide less than 20 micrograms per
liter, iron less
than 50 micrograms per liter and oxygen less than 20 micrograms per liter, and
a total content
of dissolved carbon of less than 0.2 milligram per liter. In addition, the
feed water should be
low in or free of halogen, in particular chlorine. It is also possible to
condition the feed water
in a targeted manner, for example by adding auxiliaries such as hydrazine,
ammonia, and in
particular to make it alkaline; in addition, corrosion inhibitors can be added
to the feed water.
The upper hood, through which the reaction medium leaves the reactor in the
above-described
preferred process control, may consist of carbon steel.
In order to ensure access to the thermal plate modules for the purpose of
repair or exchange, it
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likewise has to be possible to remove the upper hood. When there is no flange
connection, the
upper hood can be removed and welded on again after module assembly.
It is possible to integrate the steam removed from the thermoplates into
different steam rails.
The reactor may optionally be attached to two steam rails, one of which has a
higher pressure
and is utilized for the heating of the reactor to operating temperature.
It is advantageous to operate on only one steam rail.
The reactor can preferably be operated with natural circulation of the cooling
medium, water,
and a ratio of feed water to steam of generally from 3 to 12, preferably from
5 to 10.
It is possible to operate with forced circulation, in which case a wider load
variation of the
cooling is possible. To this end, the feed water is fed at a higher pressure
than present in the
cooling system, for example by means of a pump.
The feed water circulation rate in the distribution devices may be set between
0.5 and 3.0 m/s,
or else from 1.0 to 2.0 m/s, and the water circulation number between 3 and
12. The flow rate
of the biphasic flow (steam/water) in the collection devices may be between
0.5 and 15 m/s,
or else between 2.0 and 6.0 m/s.
Particular preference is given to carrying out the heating of the thermoplate
modules to start
up the reactor from the same heat carrier network into which the heat is
removed at by least
partly evaporated heat carrier medium in the course of reaction operation.
The regulation of the steam pressure in the cooling system makes it possible
to precisely
adjust the cooling temperature. Experience has shown that the thermoplates can
be operated
up to a pressure of about 80 bar in the coolant. The reactor according to the
invention enables
direct steam generation at pressure levels up to 80 bar.
The reactor according to the invention can be used to carry out partial
oxidations on the
industrial scale.
Compared to the filling of a large number, frequently a five-figure number, of
catalyst tubes,
the provision of the catalyst and the filling with catalyst of a two- or three-
figure number of
gaps between the thermoplates is associated with distinctly reduced cost and
inconvenience.
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The modular configuration allows the reactor to be adapted flexibly to the
required capacity.
A relatively small number of thermoplate modules may be installed or operated
in comparison
to the maximum possible number restricted by the relative geometry of the
shell and of the
thermoplate modules. It is also possible when required to isolate individual
modules from
process gas flow and to operate the reaction with reduced capacity under the
same external
conditions.
It is possible to deliver the reactor in individual parts and assemble it at
the use location.
The invention is illustrated in detail hereinbelow with the aid of drawings.
Specifically:
Figure 1 shows a longitudinal section through a preferred embodiment of a
reactor
according to the invention with the cross section C-C in Figure 1A, and also
further preferred arrangements of thermoplate modules in cross section in
Figures 1B to IF,
Figure 2 shows a detailed illustration of a thermoplate module in cross
section to the
thermoplates, with longitudinal section illustrations in the planes A-A and B-
B
in Figure 2A and 2B respectively,
Figure 3 shows two possible embodiments of seals between holding base and
stabilization frames,
Figure 4 shows a detailed illustration with driliholes in the rectangular
stabilization
frames,
Figures show detailed illustrations with additional guiding and, directing
elements on
5A, 5B the exteriors of the thermoplate module and
and 5D to
51
Figure 6 shows a detailed illustration of a tension device for securing the
thermoplate
modules in the rectangular stabilization frames.
The longitudinal section illustration through a preferred embodiment in Fig. 1
shows a reactor
having thermoplate modules 1 which are surrounded by a predominantly
cylindrical shell 4.
The intermediate space 6 between the thermoplate modules 1 and the
predominantly
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cylindrical shell 4 is sealed gas-tight in the region of the lower end of the
thermoplate module
1 by a holding base 7, and, in the region of the upper end of the thermoplate
modules 1, by a
sheet metal cover 8 which, preferred embodiment illustrated in the figure, has
orifices 9.
Also, the holding base 7 of said preferred embodiment illustrated in the
figure, is further
provided with compensators 10 for the radial expansion.
At the lower end of the thermoplate modules 1 is provided a distribution
device I l for the
heat carrier, frequently feed water, and, in the region of the upper end of
the thermoplate
modules 1, a collection device 12 for the heat carrier, which is frequently
present in this
region as steam or as a water/steam mixture. The predominantly cylindrical
shell 4 has
compensators 13 for the thermal expansion.
In the preferred embodiment illustrated in Fig. 1, the fluid reaction medium
is fed via the
lower hood 15 and removed via the upper hood 16. In the region of the lower
hood 15, and
also in the region of the upper hood 16, is disposed in each case an
additional cylindrical
section with in each case two manholes 17. In the predominantly cylindrical
shell 4 are
provided nozzles 18 for the emptying of the inert material from the
intermediate space 6
between the thermoplate modules I and the predominantly cylindrical shell 4,
and also
nozzles 19 for the feeding of nitrogen into the intermediate space 6. The
catalyst is retained by
catalyst grates 24 which are configured, for example, as edge gap sieves.
The cross-sectional illustration in the plane C-C in Fig. IA shows a preferred
arrangement of
advantageously seven thermoplate modules 1 with intermediate space 6 between
the
thermoplate modules 1 and the shell 4, which is preferably filled with inert
material.
Figure 1 B shows a cross-sectional illustration having a single thermoplate
module with square
cross section which is arranged in the shell 4.
Figure IC shows an embodiment with four thermoplate modules 1 having a square
cross
section in the shell 4.
Figure 1D shows an embodiment with seven thermoplate modules, having a
rectangular cross
section and a side ratio of in each case 1 : 1.2.
Figure 1E shows an embodiment with eleven thermoplate modules having a
rectangular cross
section and a side ratio of in each case 1 : 1.1.
Figure IF shows an embodiment with ten thermoplate modules 1 with in each case
rectangular cross section and a side ratio of in each case 1 : 1.1.
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2 illustrates a section of a thermoplate module 1 with thermoplates 2 and gaps
3 between
Fig.
the thermoplates to accommodate the heterogeneous particulate catalyst. The
figure illustrates
the weld points between the metal sheets forming the individual thermoplates
2, and also the
securing of the thermoplates 2 at their lateral edges in a lateral boundary
20. The thermoplate
module is inserted into a rectangular stabilization frame 5.
The sectional illustration in the plane A-A in Fig. 2A illustrates the lateral
roll seam weld 22
which seals the individual thermoplates, and also the sealing strips 23
between the
thermoplates 2 of the thermoplate module 1 and the wall of the rectangular
stabilization frame
5. The figure also shows a preferred arrangement of the weld points on the
thermoplates 2.
The section B-B which is shown in Fig. 2B is located in a plane through the
gap 3 filled with
the particulate catalyst. Between the lateral boundary 20 of the thermoplate
module 1 and the
wall of the rectangular stabilization frame 5 are provided sealing strips 23.
Figure 3 shows two different variants for sealing the thermoplate modules with
respect to the
holding base. The left-hand side of the diagram shows a seal 25 between the
holding base 7
and the lateral boundary 20 of a thermoplate module, and the connection is
secured by a screw
26. The detail also shows a section of the edge gap sieve 24 used as a
catalyst grate, and also a
sealing strip 23 between the lateral boundary 20 of the thermoplate module and
the
rectangular stabilization frame 5.
The right-hand side of the diagram in Figure 3 shows a further variant of a
seal between
holding base 7 and thermoplate module, specifically by means of two weld lips
27, one of
which is welded to the holding base 7 and the second to the lateral boundary
20 of the
thermoplate module. The two weld lips are subsequently joined together with a
weld seam.
Figure 4 shows an embodiment with drillholes 28 in the rectangular
stabilization frames 5,
which allows gas used to apply pressure to flow from the intermediate space
between the
thermoplate modules and the shell into the spaces between the thermoplate
modules 1 and the
rectangular stabilization frames 5.
Figure 5A shows a detailed illustration of a corner bracket 29 on the exterior
of the lateral
boundary 20 of a thermoplate module 1 for conducting and directing with
respect to the
rectangular stabilization frame 5.
The detailed illustration in Figure 5B shows, in addition to the corner
bracket 29, conical
metal sheet strips 30 on the side of the thermoplate modules 1 as guiding and
directing
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elements.
In addition, Figure 5B shows a possible embodiment for the outermost thermo
plate 2 in the
thermoplate module 1, and specifically the outer metal sheet of the outermost
thermoplate 2 of
the thermoplate module 1 is thicker and thus more stable compared to the
remaining metal
sheets forming the thermoplates 2.
Figures 5D to 51 show schematics of different variants for securing the
thermoplates 2 to the
lateral boundary 20:
in the embodiment in Figure 5D, the thermoplates 2 are welded on;
in Figure 5E, two angles welded onto the lateral boundary 20 are provided to
secure the
thermoplates;
in the embodiment in Figure 5F, square tubes;
in the embodiment in Figure 5G, half tubes,
in the embodiment in Figure 5H, U-profiles; and
in Figure 51, angled profiles.
Figure 6 shows a schematic of a tension device 32 for tensioning between
thermoplate
modules and the rectangular stabilization frames 5.
