U.S. patent application number 10/451729 was filed with the patent office on 2005-03-10 for device for combustion of a carbon containing fuel in a nitrogen free atmosphere and a method for operating said device.
Invention is credited to Bruun, Tor, Gronstad, Leif, Kristiansen, Kare, Linder, Ulf, Werswick, Bjornar.
Application Number | 20050053878 10/451729 |
Document ID | / |
Family ID | 19911963 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050053878 |
Kind Code |
A1 |
Bruun, Tor ; et al. |
March 10, 2005 |
Device for combustion of a carbon containing fuel in a nitrogen
free atmosphere and a method for operating said device
Abstract
The present invention relates to a device for combustion of a
carbon containing fuel in a nitrogen free atmosphere, and a method
for operating said device. The device may be integrated with a
power generation plant (i.e. gas turbine(s)) to obtain an energy
efficient process for generation of power with reduced emission of
carbon dioxide and NOx to the atmosphere. Furthermore, the device
may be integrated with a chemical plant performing endothermic
reactions.
Inventors: |
Bruun, Tor; (Porsgrunn,
NO) ; Gronstad, Leif; (Sannidal, NO) ;
Kristiansen, Kare; (Skien, NO) ; Werswick,
Bjornar; (Langesund, NO) ; Linder, Ulf;
(GB--Leicester, GB) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
19911963 |
Appl. No.: |
10/451729 |
Filed: |
August 25, 2004 |
PCT Filed: |
December 19, 2001 |
PCT NO: |
PCT/NO01/00499 |
Current U.S.
Class: |
431/11 |
Current CPC
Class: |
Y02P 20/10 20151101;
F02C 1/04 20130101; Y02P 20/123 20151101; F23L 7/007 20130101; F23C
6/04 20130101; F02C 3/20 20130101; Y02E 20/348 20130101; F23L
2900/07006 20130101; F23L 15/04 20130101; Y02E 20/34 20130101; C01B
13/0251 20130101; B01D 53/22 20130101; F02C 6/10 20130101; Y02E
20/344 20130101; Y02P 20/126 20151101; C01B 2210/0046 20130101 |
Class at
Publication: |
431/011 |
International
Class: |
F23L 015/00; F23D
011/44 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 2000 |
NO |
200006690 |
Claims
1-17. (Cancelled).
18. A device for combustion of a carbon containing fuel in a
nitrogen free atmosphere, wherein said device comprises a hollow
shell having an inlet for conveying said fuel, an inlet for
conveying a compressed oxygen containing gas stream, an outlet for
discharging an oxygen depleted gas stream and an outlet for
discharging a bleed stream; and said shell encloses one or more
heat exchange modules arranged to heat the incoming compressed
oxygen containing gas stream; one or more mixed conducting membrane
modules arranged to separate oxygen from said oxygen containing gas
stream resulting in an oxygen rich gas stream and said oxygen
depleted gas stream; a first and possibly a second combustion
chamber for combustion of said fuel having an inlet connected to
said inlet for fuel to convey fuel to said chamber, an inlet
connected to said heat exchange module(s) to convey hot oxygen rich
gas to said chamber and an outlet connected to said membrane
module(s) to convey exhaust gas from the combustion chamber to the
membrane module; a pressure booster installed prior to the first
combustion chamber; means (11,21) for connecting said heat
exchanger module(s) and membrane module(s); means (7,23) for
connecting said heat exchanger module(s) and said membrane
module(s) to the inlet for the compressed oxygen containing gas
stream and the outlet for the oxygen depleted gas stream and means
for conveying a part of said exhaust gas stream directly to said
heat exchange module(s) and back to said inlet from the combustion
chamber.
19. A device according to claim 18, wherein said heat exchange
module(s), said membrane module(s), said means (7,11,21,23), an
outlet for said hot oxygen rich gas stream, said outlet for
discharged oxygen depleted gas stream, an inlet for said exhaust
gas and said inlet for compressed oxygen containing gas stream are
all installed in a pressure vessel (reactor).
20. A device according to claim 18, wherein said heat exchange
module(s), said membrane module(s), said second combustion chamber,
said means (7,11,21,23), an outlet for said hot oxygen rich gas
stream, said outlet for discharged oxygen depleted gas stream, an
inlet for said exhaust gas and said inlet for compressed oxygen
containing gas stream are all installed in a pressure vessel.
21. A device according to claim 18, wherein said modules and said
second combustion chamber are vertically interconnected one above
the other.
22. A device according to claim 18, wherein said modules are
vertically interconnected one above the other.
23. A device according to claim 18, wherein said membrane module is
installed between two heat exchange modules.
24. A device according to claim 18, wherein said second combustion
chamber is installed between one of the heat exchange module and a
membrane module.
25. A device according to claim 19, wherein said outlet for said
hot oxygen rich gas stream is connected to the inlet to the first
combustion chamber and said inlet for said exhaust gas is connected
to the outlet from the first combustion chamber.
26. A device according to claim 18, wherein said pressure booster
is a fan or a compressor.
27. A device according to claim 18, wherein said heat exchange
module(s) and said membrane module(s) comprise a multichannel
monolithic structure.
28. A method for operating a device according to claim 18, wherein
said method comprises the following steps: a compressed oxygen
containing gas stream is fed to a first heat exchange module where
it is heated by means of heat generated by combustion of a fuel in
a combustion chamber; said heated gas stream is fed to a mixed
conducting membrane module(s) where most of the oxygen is separated
from said gas stream and an oxygen depleted gas stream is obtained;
a sweep gas is fed to said membrane module to pick up oxygen and
the oxygen enriched sweep gas is further fed to a pressure booster;
the pressurized sweep gas stream enters the combustion chamber
where it is mixed with a fuel for combustion; and said oxygen
depleted gas stream is fed to another heat exchange module for
further heating before leaving said device.
29. A method for operating a device according to claim 28, wherein
said combustion product; the exhaust gas, is applied as sweep
gas.
30. A method for operating a device according to claim 28, wherein
a part of the exhaust gas is taken out as a bleed stream to prevent
accumulation of mass in the device.
31. Use of a device and a method according to claim 18 in a plant
for generation of power.
32. Use of a device and a method according to claim 18 in a
chemical plant performing an endothermic reaction.
Description
[0001] The present invention relates to a device for combustion of
a carbon containing fuel in a nitrogen free atmosphere and a method
for operating said device.
[0002] The device may be integrated with a power generation plant
(i.e. gas turbine(s)) to obtain an energy efficient process for
generation of power with reduced emission of carbon dioxide and NOx
to the atmosphere. Furthermore, the device may be integrated with a
chemical plant performing endothermic reactions.
[0003] Conventional combustion processes, used for carbon
containing fuels, will in addition to producing the main end
products carbon dioxide and water (steam), generate a considerable
amount of heat (heat of combustion). A conventional combustion
reaction between e.g. methane and oxygen will generate
approximately 804 KJ per mol methane:
CH.sub.4+2O.sub.2-->CO.sub.2+2H.sub.2O
[0004] When this combustion process is integrated with e.g. a power
generation plant (i.e. gas turbines) or a chemical plant performing
endothermic reactions, it is crucial that the total energy loss
from the combustion process is as low as possible.
[0005] Furthermore, due to the environmental aspects of CO.sub.2
and NO.sub.x it is crucial that the emission of these components to
the atmosphere is considerably reduced compared to conventional
processes. Conventional combustion processes produce an exhaust gas
with a CO.sub.2-concentration between 3 and 15% dependent on the
fuel and the combustion- and heat recovery process applied. The
reason the concentration is this low is because air comprises about
78% by volume of nitrogen. In high-temperature combustion processes
in air, nitrogen will react with oxygen and produce the
environmental hazardous gas pollutant NO.sub.x.
[0006] A reduction in the emission of carbon dioxide to the
atmosphere makes it necessary to either separate the carbon dioxide
from the exhaust gas, or raise the concentration in the exhaust gas
to levels suitable for use in different chemical processes or for
injection in e.g. a geological formation for long term deposition
or for enhanced recovery of oil from an oil reservoir.
[0007] CO.sub.2 can be removed from cooled exhaust gas, normally
discharged at near atmospheric pressure, by means of several
separation processes, e.g. chemical active separation processes,
physical absorption processes, adsorption by molecular sieves,
membrane separation and cryogenic techniques. Chemical absorption,
for instance by means of alkanole amines, is considered as the most
practical and economical method to separate CO.sub.2 from exhaust
gas. These separation processes consume energy and require heavy
and voluminous equipment. Applied in connection with a power
generation process, these separation processes will reduce the
power output with 10% or more.
[0008] An increase of the concentration of CO.sub.2 in exhaust gas
from a combustion reaction to levels suitable for use in different
chemical processes or for injection in e.g. a geological formation
for long term deposition or for enhanced recovery of oil from an
oil reservoir is possible by burning the carbon containing fuel
with pure oxygen instead of air.
[0009] Commercial air separation methods (e.g. cryogenic separation
or pressure swing absorption (PSA)) applied for producing pure
oxygen require 250 to 300 KWh/ton oxygen produced. If these methods
are used for supplying oxygen to a combustion process in a gas
turbine cycle these methods will reduce the net power output from
the gas turbine cycle by at least 20%. The expenses of producing
oxygen in a cryogenic unit will increase the price of produced
electric power substantially and may amount to as much as 50% of
the cost of the electric power.
[0010] However, a less energy demanding method than these
separation methods is known from the European Patent Application
658 367-A2. The patent application describes an application of a
mixed conducting membrane (MCM) integrated with a gas turbine
system and where the membrane separates oxygen from a heated air
stream.
[0011] The mixed conducting membrane (MCM) is defined as a membrane
made of materials with both ionic and electronic conductivity. The
membrane selectively transports oxygen. The driving force through
the membrane is proportional to the logarithmic relation between
oxygen partial pressures; log (pO.sub.2(I)/pO.sub.2(II)), where (I)
represents the oxygen delivering side (air) of the membrane and
(II) represents the oxygen receiving side of the membrane. To keep
a high transport rate (flux) of oxygen it is important to keep a
low partial pressure on the oxygen receiving side.
[0012] Thus, to further improve the efficiency of this membrane
process, a sweep gas is applied to reduce the partial pressure of
oxygen on the oxygen receiving side of the membrane and thereby
increase the flux of oxygen through the membrane; as e.g. described
in U.S. Pat. No. 5,562,754 and NO-A-972632.
[0013] To obtain practical applications of mixed conducting
membranes (MCM) when applied as an oxygen supplier in a combustion
process the following criteria are essential:
[0014] a) The driving force of the oxygen transport through the
membrane expressed as the logarithmic relation between oxygen
partial pressures; log (pO.sub.2 (I)/pO.sub.2 (II)), has to be kept
at a high level.
[0015] b) The membrane has to operate at high temperature levels
(>600.degree. C.) to achieve a sufficient oxygen flux through
the membrane. Thus air or any other gases in contact with the
membrane must have a high temperature.
[0016] To ensure that the driving force through the membrane is
kept at a high level oxygen on the oxygen receiving side of the
membrane has to be:
[0017] i) transported away from the membrane surface, by applying a
sweep gas, or
[0018] ii) consumed by a chemical reaction (e.g. a combustion
process) directly on the oxygen receiving side.
[0019] This implies that the device which shall perform an energy
efficient combustion in a nitrogen free atmosphere must be designed
to operate under process conditions as mentioned above. There
remains therefore a need for such a device and a method for
operating said device that is not described in the prior art.
[0020] The main object of the present invention was to provide a
device effective to achieve combustion of a carbon containing fuel
in a nitrogen free atmosphere.
[0021] Another object of the present invention was to provide a
device effective to achieve a combustion process resulting in an
exhaust gas with a high concentration of CO.sub.2 and a low
concentration of NOx.
[0022] Furthermore, another object of the invention was to provide
a method for operating said device.
[0023] Yet another object of the invention was to provide a plant
and a method for an energy efficient generation of power.
[0024] Still yet another object of the invention was to provide a
plant and a method for generation of power with reduced emission of
carbon dioxide and NOx to the atmosphere.
[0025] The inventors found that the described objects were
fulfilled by utilizing a device where one or more mixed conducting
membrane module(s), one or more heat exchange module(s) and one or
more combustion chamber(s) were enclosed within a hollow shell (a
pressure vessel) defining an enclosure. The device may further be
integrated with gas turbine(s) in a plant for generation of power.
The device may also be integrated with a chemical plant performing
an endothermic reaction to supply necessary heat to the
reaction.
[0026] The mixed conducting membrane(s) (MCM) which is utilized in
the device according to the present invention will at conditions
described above (a) and b)) transport oxygen from an oxygen
delivering gas (e.g. air) to an oxygen receiving gas. The oxygen
receiving gas has a lower partial pressure of oxygen than the
oxygen delivering gas. To the oxygen receiving gas a carbon rich
fuel (e.g. natural gas) is added and a heat generating combustion
reaction between oxygen and added fuel takes place.
[0027] Combustion of natural gas with pure oxygen will produce an
exhaust gas containing the two main products carbon dioxide and
water (steam). According to the present invention the exhaust gas
is utilized as the oxygen receiving gas. The oxygen rich gas stream
(i.e. the oxygen enriched exhaust gas) is fed to the combustion
chamber and applied as oxidant in the combustion reaction. Thus, a
production of the environmental harmful NOx gas is avoided.
[0028] The thermal energy produced by the combustion reaction is by
means of heat exchanger(s) utilized to heat air fed to the
MCM-module(s) as well as to heat oxygen depleted air leaving the
MCM-module(s) before it may enter a power generation turbine or a
chemical plant performing an endothermic reaction.
[0029] Thus the air stream fed to the membrane is heated without
producing CO.sub.2 or NOx, in the stream. In the combustion
reaction almost all oxygen is consumed and thus the exhaust gas,
now having a very low partial pressure of oxygen, can be
recirculated to the MCM as a sweep gas picking up oxygen before
entering the combustion chamber again. Thus we have a continuous
combustion. From the exhaust gas a bleed stream has to be taken out
to balance the added fuel and oxygen received to prevent
accumulation of mass. This bleed gas leaving the device at elevated
pressure and temperature could also be fed to a power generation
system (turbine). In the turbine the pressure of the bleed gas is
decreased and further cooled to condense almost all steam to water.
Thus the gas flow will consist mainly of carbon dioxide. This
carbon dioxide gas flow has to be compressed to a pressure that
allows injecting in an underground reservoir, a reservoir that
could be an aquafier layer or a gas or oil reservoir. These
reservoirs should be qualified for ensuring long term
deposition.
[0030] As mentioned above the exhaust gas is utilized as a sweep
gas to pick up oxygen in the membrane module(s) and transport
oxygen to one or more combustion chambers where fuel is added. The
heat generated in the exhaust gas should in an efficient way be
transported to the air stream, and in such a way, that leakage
between sweep gas and air is prevented or minimised to an
acceptable level.
[0031] Furthermore, the inventors found that by utilizing a
multiplate or a multichannel structure as a MCM-module and/or as a
heat exchange module a very efficient device was achieved.
Multichannel structures are found to be the most advantageous due
to the fact that they can be extruded in one piece (i.e. a
monolith) and thus a large surface area in one piece is obtained.
Most preferably both the heat exchange module(s) and the
MCM-modules are made of a ceramic material that is able to
withstand the present process conditions (atmosphere, temperature
and pressure).
[0032] Such structures, especially with channel diameter below 10
mm, give a very high surface area/unit volume. By preparing every
second row of channels by inlet slots as described in U.S. Pat. No.
4,271,110 a simplified manifold system to every second row of
channels could be achieved and thus give a low leakage rate
probability between the air side and the oxygen receiving side.
[0033] To obtain a largest possible surface area for heat exchange
and/or oxygen transfer (when utilized as a MCM-module), the
channels should be very small and every air channel should be
surrounded by (i.e. have common walls with) the other gas (i.e.
sweep/exhaust gas). Such a configuration needs a very complicated
system for leading the two gases (manifolding) to each adjacent
channel.
[0034] According to the present invention such multichannel
monolithic structures are connected or linked together in such a
way that the MCM-module is installed between two heat exchange
modules. Furthermore, these modules are installed in a pressure
vessel hereinafter defined as the reactor. Such a system will
ensure that the MCM is able to operate at a defined temperature
higher than the temperature in the air stream fed to the system and
below the temperature of combustion (i.e. the exhaust gas
temperature from the combustion chamber).
[0035] Another important feature of the present invention is the
flow pattern of the two gas streams. The first gas stream (the air
stream) has a flow from inlet to outlet of the reactor that follows
longitudinal to the direction of channels in the monolithic
structures (i.e. heat exchangers and MCM). This means that the gas
enters and leaves the open channels from the short ends and flows
through an open room or closed structure that connects these ends.
The second gas stream has a flow direction in and out of the side
slots of the monolith, through bypass rooms or connectors to the
side slot of the adjacent monolithic structures. These bypass rooms
are surrounding the inner open room of the first gas.
[0036] Such a flow system of the gases will allow one of the gases,
here the second gas, to leak and fill all available space or
"empty" room of the reactor. The requirement for a gas tight
sealing is then reduced for the first gas only to be a sealing
towards the second gas (not to the "empty" space of the reactor)
located at the inner coupling connectors between the monolithic
structures.
[0037] This feature is very important because a controlled leakage
of gas is necessary to build up and equalise the pressure inside
the reactor house, and only one of the gases is allowed to leak to
prevent mixing. This controlled and necessary leakage allows a
flexible sealing of defined leakage rate for the bypassing
connectors of the second gas. Flexibility to avoid thermal stress
in connecting parts/monolithic structures is very important to
prevent fatal cracks.
[0038] By filling the reactor with gas of almost the same pressure
as the gas inside the monolith channels only the outer pressure
shell of the reactor has to withstand the absolute or total
pressure of the process. The pressure on the monolith walls is then
reduced to withstand the differential pressure between the two
gases (Gas 1 and Gas 2 in FIG. 3).
[0039] The scope of the invention and its special features are as
defined by the attached claims.
[0040] The invention will be further explained and envisaged in the
following figures.
[0041] FIG. 1 shows a sketch of one embodiment of the device
according to the present invention including its functional parts
as heat exchange module, MCM-module and combustion chamber. Also
included is a pressure booster, here shown as a jet ejector driven
by high pressure (HP) steam. In this embodiment the modules are all
installed within the reactor.
[0042] FIG. 2 shows another embodiment of the device according to
the present invention including the same functional parts as heat
exchange module, MCM-module as well as a combustion chamber and a
pressure booster, but in this embodiment the combustion occurs in a
separate vessel connected to the reactor. The pressure booster is
installed in the connecting pipes, preferably prior to the
combustion chamber where the sweep gas has its lowest
temperature.
[0043] FIG. 3 shows a sketch of a multichannel monolith structure
utilized as a MCM-module and/or as a heat exchange module.
[0044] FIG. 4 shows one embodiment of the reactor with the
different modules as well as the other functional components in the
reactor.
[0045] FIG. 5 shows different shapes of connectors between the MCM-
and the heat exchange modules as well as different methods applied
for sealing of the connectors between the modules.
[0046] FIG. 6 shows one embodiment of the device according to the
present invention where the combustion chamber is installed outside
the reactor as well as some of the internal components taken out of
the reactor for the purpose of better illustrating these individual
components.
[0047] FIG. 7 shows a more detailed illustration of the whole
device according to the present invention as well as the individual
components of the reactor.
[0048] FIG. 8.1 shows one embodiment of a plant for generation of
power where the device according to the present invention is
integrated with gas turbines.
[0049] FIG. 8.2 shows another embodiment of a plant for generation
of power where the device according to the present invention is
integrated with gas turbines and where more than one reactor have a
common combustion chamber.
[0050] FIG. 9.1 shows one embodiment of the device according to the
present invention where each process stream is given a tag number
according to Table 1.
[0051] FIG. 9.2 illustrates the internal flow path of the air in
the reactor.
[0052] FIG. 1 shows a principal sketch of the device according to
the present invention where the process streams and the important
process units (H-01), (X-01), (H-02), (F-01) and (I-01) are shown.
The units are all installed inside the reactor pressure shell which
is in this example identical to the device shell. The figure shows
that an oxygen containing gas stream (here air) is conducted trough
a compressor. The compressed air stream (AN-030) is further fed to
the heat exchange module (H-01) where it is heated (AN-050) before
entering the mixed conducting membrane module (X-01) in which
oxygen is separated from the air stream resulting in an oxygen
depleted air stream (AL-010). The oxygen depleted air stream
(AL-010) enters the heat exchanger (H-02) for further heating
before leaving the device (AL-020). The depleted air stream
(AL-020) may be fed to a power generation turbine or a chemical
plant performing endothermic reactions. A sweep gas (EG-020) is fed
to the MCM-module (X-01) and is picking up oxygen at the oxygen
receiving side of the membrane and further transported through heat
exchange module (H-01). The oxygen enriched gas stream (EGO-030) is
then pressurized in a pressure booster (I-01) before entering the
combustion chamber (F-01). The combustion chamber (F-01) where fuel
(NG-010) is added and burned is in this example installed inside
the reactor pressure shell. The combustion gas or exhaust (EG-010)
is now almost oxygen free due to combustion in (F-01).
[0053] A part of the hot combustion product or exhaust gas (EG-010)
is taken out as a bleed stream (EG-040) to prevent accumulation of
mass in the reactor while the rest of the product gas is fed to the
heat exchange module (H-02) and heated to the operational
temperature of the membrane. In the membrane module stream (EG-020)
is acting as a sweep gas. The hot and oxygen enriched sweep gas
stream (EGO-020) is fed to the heat exchange module (H-01) to heat
the incoming gas stream (AN-030). The heated air stream (AN-050) is
entering the MCM-module (X-01) at the operational temperature of
the MCM-modules (X-01). A pressure booster (I-01) has to be
installed to enhance circulation in the sweep gas loop and ensure a
continuous combustion. In FIG. 1 this is a jet pump driven by
injection of high pressure (HP) steam. The jet pump has the
advantage of no moving parts and might be built in a material (i.e.
ceramic) that can withstand very high temperatures. For power
generation the oxygen depleted gas stream (AL-020) and the bleed
gas stream (EG-040) may be fed to gas turbines to generate power.
The bleed gas (EG-040) containing the main combustion products
(CO.sub.2+H.sub.2O) will have a high temperature (combustion gas
temperature). To generate power directly from the stream a gas
turbine capable of handling the CO.sub.2 and H.sub.2O mixture is
needed. Another power generating alternative for this stream is to
cool down the gas to a temperature <550.degree. C. where a
conventional steam turbine can be used. This can be done by
injecting water to stream (EG-040) or heat exchange with the
incoming "cold" air stream (AN-030).
[0054] FIG. 2 shows another embodiment of the device according to
the present invention where the pressure booster (I-01) and the
combustion chamber (F-01) are installed outside the reactor
pressure shell but within the device shell. This feature
contributes to simplify the construction of the device. The
advantage of installing (I-01) and (F-01) outside the reactor is to
facilitate the maintenance work and makes it possible to apply
cooling apparatus. Thus a rotary pressure increasing machine can be
used as a pressure booster (I-01) as envisaged in this figure. The
flow path in this embodiment is the same as in the embodiment shown
in FIG. 1. The only difference is that no high pressure (HP) steam
is injected (because no jet pump is used), but this will not amend
the principle flow pattern. Injecting high pressure (HP) steam as
shown in FIG. 1 will reduce the net power generation efficiency of
the process and thus a rotary machine as shown in FIG. 2 is with
respect to efficiency more advantageous.
[0055] An external combustion chamber will also simplify the fuel
(NG-010) injection system and makes it easier to upscale the device
as will be shown in FIG. 8.
[0056] FIG. 3 shows a multichannel monolith structure which,
according to the present invention might preferably be utilized as
both a heat exchange module and a membrane module. As mentioned
above, such structures are advantageous mainly because of their
simple way to be manufactured. However, the present invention is
not restricted to application of such structures only and other
configurations (e.g. plates) may be an alternative.
[0057] According to FIG. 3, using stream notation as in FIGS. 1 and
9, Gas 1 represents gas streams (AN-030) and (AN-050) if the
monolith structure is module (H-01), gas streams (AN-050) and
(AL-010) if the monolith structure is module (X-01). If the
monolith structure is module (H-02), then Gas 1 is gas streams
(AL-010) and (AL-020).
[0058] Gas 2 represents the gas streams (EGO-020) and (EGO-030) if
the module is (H-01), the gas streams (EG-030) and (EGO-010/020) if
the module is (X-01) and gas streams (EG-020) and (EG-030) if the
module is (H-02).
[0059] Gas 1 follows the straight path through the channels and is
thus always fed in and let out from the open rows of channels at
the monolith ends. Gas 2, normally the sweep gas, is always fed in
and taken out from the open slots in the side wall of the monolith
structures. Since these monolithic structures preferably will be
made by extrusion, all channels will be of the same length. The
inlet and the outlet slots of Gas 2 must be made after extrusion by
machining every second column of channels as visualised on the
figure. After machining down to the preferred depth the open row of
channels (made by machining) has to be closed by a sealing in such
a way that a sufficient opening area for the side slot is kept
(inlet and outlet for Gas 2).
[0060] The problem of preventing leakage in the manifold system of
two different gases leading in and out of the multichannel
monolithic structures is minimised by making these inlet and outlet
slots as described and shown in FIG. 3.
[0061] According to the present invention a channel diameter below
10 mm is used. A diameter between 1 and 8 is preferred.
[0062] FIG. 4 shows one embodiment of the reactor as described in
FIG. 2, where the combustion chamber and the pressure booster are
mounted outside the reactor shell. In the figure the connecting
flanges for the inlet (EG) and the outlet (EGO) of the sweep gas
stream as well as the inlet (AN) of the air stream and the outlet
(AL) of the oxygen depleted air stream are shown. Inside the
reactor the flow path of these streams is visualized by dotted
lines. Heat exchanger (H-01), MCM-modules (X-01) and the outlet
heat exchanger (H-02) are fixed together by the connectors between
(H-019, (X-01) and (H-02). These connectors are preferably glass
sealed, before installed in the reactor, to ensure no leakage and
thus will be one whole part (i.e. sealed together). During heating
this whole part has to be allowed to expand. This will be further
described in FIG. 7.
[0063] FIG. 5 shows alternative shapes for the connectors between
the (X-01) and (H-01/H-02). Thus (H-01) and (X-01) as well as
(X-01) and (H-02) could be connected and sealed to each other by
different components as shown. The most important factor is to have
a tight sealing without leakage between the inner gas (i.e. Gas 1
as described in FIG. 3, preferably air) and the outer gas (i.e. Gas
2 described in FIG. 3, preferably sweep gas).
[0064] FIG. 6 shows one embodiment of the device according to the
illustration in FIG. 2, where the combustion chamber (F-01), as
well as the pressure booster (I-01) are installed outside the
reactor. Fuel (NG) is injected in the low temperature zone prior to
(I-01) to ensure a good mixing with the oxygen enriched sweep gas
(EGO) before entering the combustion chamber (F-01). Due to a too
low temperature the combustion, at least partly, might be enhanced
by a catalyst. The sweep gas stream (EGO) leaving (H-01) is cooled
down by the air stream (AN) and has its lowest temperature before
(I-01). The pressure in the stream (EGO) is increased by means of
(I-01) before entering the combustion chamber (F-01) outside the
reactor. In (F-01) oxygen in stream (EGO) reacts with added fuel
and a combustion is obtained. In the combustion nearly all oxygen
is consumed. Thus the exhaust gas (EG), mainly containing the
reaction products (CO.sub.2 and H.sub.2O), will have a low content
of oxygen. (EG) enters the second heat exchanger (H-02) where it is
heating the oxygen depleted air stream (AL) leaving the
reactor.
[0065] (EG) is thus somewhat cooled down by (AL) in (H-02) before
it enters the membrane module(s) (X-01). In (X-01) (EG) acts as a
sweep gas picking up oxygen transferred through the membrane wall
from the air side. The oxygen enriched sweep gas leaving (X-01),
now named (EGO), is then entering the first heat exchanger (H-01)
where the air stream (AN) is heated and the stream (EGO) is cooled.
Thus a cooled oxygen containing sweep gas (EGO) is now returning
via (I-01) to (F-01) and thus an exhaust/sweep gas loop is obtained
enhancing a continuous combustion.
[0066] Either from the oxygen enriched sweep gas (EGO) or from the
exhaust gas (EG) a bleed gas has to be taken out to prevent
accumulation of mass in the sweep gas loop due to the oxygen
transfer from the air and the addition of the fuel. Example of
bleed gas outlet is shown in FIGS. 8.1 and 9.1.
[0067] Also shown in FIG. 6 are some of the individual components
of the reactor.
[0068] FIG. 7 shows a more detailed embodiment of the device
according to the present invention.
[0069] Reactor pressure vessel 1 contains the low temperature heat
exchanger 9, the high temperature heat exchanger 19 and the
MCM-modules 15. Thus all other parts are built up around these
units 9, 15 and 19 which ensure good heat transfer (from
sweep/exhaust gas to air) and oxygen transfer (from air to sweep
gas). The parts 8, 14 and 18 are used to make a round shape at the
outer wall of the heat exchangers and MCM-modules to ensure less
complicated sealing. These parts could also be made with channels
in such a way that they can be used as heat exchangers 8 and 18 or
as MCM-modules 14. The individual parts 10, 11, 12 and 13 will fit
together and make the connection between the low temperature heat
exchanger 9 and the MCM-modules 15 as shown in FIG. 5.3. In the
same way the individual parts 16, 17, 20 and 21 will make the
connection between the MCM-modules 15 and the high temperature heat
exchanger 19. The coupling part 11 preferably will be glass sealed
in both ends to 9 and 15 and part 21 respectively will be sealed to
15 and 19. Thus the material in 11 has to match the thermal
expansion of both 9 and 15 and respectively the material in 21 has
to match the thermal expansion of 15 and 19. One option is to
extrude these connection parts 11 and 21 with a gradual change in
composition of material such that the material in the end of 11
connected to 9 matches its thermal expansion, respectively the
other end of 11 matches the thermal expansion of 14. In the same
way 21 also could be made in such a way that thermal expansion is
matching material in both 15 and 19 to prevent cracks. Also the
inlet plenum room for air, unit 7 could be glass sealed to the low
temperature heat exchanger 9 to ensure minimum leakage. Thus also
the material in 7 has to match the thermal expansion of 9. In the
same way the outlet plenum 23 for oxygen depleted air might be
glass sealed to 18 and 19 and thus 23 has to be made of a material
that matches 18 and 19 in thermal expansion. Part 7 is in the inlet
end (incoming air) made of a round shape (pipe) to make it easier
to fit into a flexible sealing 5. Respectively this is also done
for the outlet plenum 23 (of the oxygen depleted high temperature
air). Also here, in same way as inlet, a ring sealing, 24 is shown.
For a vertical orientation as shown in FIG. 7 a lower flexible
sealing may not be necessary. This end could be fixed and thermal
expansion allowed to take place in the upper end through the
flexibility of seal 5. Thus, in at least one end, a sealing that
allows expansion in the longitudinal direction has to be included.
In the present invention this is solved by designing the inlet
and/or outlet connectors 4 and 25 in a round shape (pipe end). Thus
this makes it easier to have a flexible sealing. Flexible sealing
rings 5 and 24 have to be made of a temperature resistant material
(ceramic or metal). Also other flexible "pipe" sealing systems is
possible.
[0070] The inlet and outlet pipes 4 and 25 may have the same shape
to simplify the fabrication. Inlet pipe 4 leads the air stream to
the inlet plenum made up by 7 and made in such a way that flexible
sealings 5 can be mounted. The inlet pipe 4 is most preferably made
of a material that also acts as a thermal barrier or lining between
the hot inlet air and the outer metal pipe connected to the
pressure vessel shell. This is especially important for the outlet
pipe 25 in the high temperature end. Also shown are parts 6 and 22
that act as a thermal barrier or lining between exhaust/sweep gas
and the flanged inlet/outlet metal pipe of the pressure vessel.
[0071] Also shown is the thermal barrier and insulation 3 between
the high temperature inner parts and the outer metal wall or shell
of the pressure vessel Keeping a low temperature (<500.degree.
C.) in the outer pressure shell will reduce heat loss and allow the
pressure shell to be made of a common engineering material (i.e.
carbon steel). By lowering the temperature, the thickness of the
wall and thus also the total weight of the device is reduced. This
is important for an offshore installation.
[0072] Parts 3 are also made in a shape and of such a material that
it can act as support for the inner parts. 2 is a layer of a
flexible material between the inner wall (pressure shell) and 3
allowing for some movement caused by thermal expansion.
[0073] FIG. 8.1 shows one embodiment of the device according to the
present invention where the device is integrated with gas
turbines.
[0074] FIG. 8.2 shows another embodiment of integrating the reactor
with gas turbines where more than one reactor have a common
combustion chamber.
[0075] According to the present invention one or more reactor units
can be coupled together and share a common combustion chamber as
shown in FIG. 8.1. This will allow multiple production of standard
sized reactors and a cost efficient production by increasing total
power output (upscaling) by integrating or coupling standard sized
reactors together as shown in FIG. 8.2. If for example the single
device in the plant as shown in FIG. 8.1 is producing 10 MW of
power, the plant shown in FIG. 8.2 having 6 reactors of the same
size as a standard single reactor the plant will produce about 60
MW.
[0076] Shown in FIG. 8.1 are two different alternatives for
discharging the bleed stream. One alternative (Alt. 1) is to
discharge a bleed stream from the cold part of the sweep gas loop.
The bleed stream will have a temperature that allows it to be sent
directly to a steam turbine. The bleed stream taken out as shown in
alternative one contains oxygen and this process stream can thus be
used for further heat generation in a nitrogen free atmosphere and
further as a heat source in an endothermic process. In alternative
two (Alt. 2) a bleed stream is discharged after the combustion and
thus it is almost oxygen free and at a high temperature level. If a
steam turbine is to be used to enhance power generation from this
stream, the temperature must be lowered, i.e. by injecting water.
The bleed stream can be discharged anywhere in the sweep gas stream
loop. Also shown in FIG. 8.1 is that the inlet air pipe (from
compressor to reactor) is longer than outlet lean air pipe (from
reactor to turbine). This is found advantageous due to the higher
temperature of the outlet oxygen lean air stream compared to the
inlet air stream.
[0077] FIG. 9.1 shows the device according to the present invention
with the flow direction of the different gas streams. The figure
shows that an oxygen containing gas stream (AN-030), preferably a
compressed air stream, is fed to the heat exchange module (H-01)
where the gas stream is heated before entering the mixed conducting
membrane module (X-01). Oxygen is transported through the membrane
wall to be picked up by the sweep gas stream (EG-030). An oxygen
enriched sweep gas stream leaves the module (X-01) now named
(EGO-010).
[0078] A part of the total fuel, (NG-030), is mixed with stream
(EGO-010) in an additional combustion chamber (F-02) situated
between (X-01) and (H-01) where the heat generated from this
combustion will be supplied to heat exchanger (H-01) for heating
incoming air. It has to be emphasized that the present invention
will work without this combustion chamber (F-02) as explained in
FIG. 6. For this embodiment the sweep gas stream (EGO-020) entering
the heat exchanger (H-01) will have somewhat higher temperature
than the stream (EGO-010) and somewhat lower content of oxygen. The
sweep gas stream (EGO-020) is then fed to the heat exchanger (H-01)
for heating incoming air to the MCM-module (X-01). The sweep gas
stream (EGO-030) leaving (H-01) has now its lowest temperature and
is supplied to the main combustion chamber (F-01) outside the
reactor where most of the fuel (NG-020) is burned. A pressure
booster (I-01) is installed close to the inlet of the main
combustion chamber (F-01). The pressure increase from (EGO-030) to
(EGO-040) enhanced by the pressure booster (I-01) is to ensure
circulation in the sweep/exhaust gas loop.
[0079] A part of the hot exhaust gas (EG-040) is discharged as a
bleed stream to prevent accumulation of mass in the exhaust/sweep
gas loop. In principle the bleed gas stream (EG-040) can be
discharged anywhere in the sweep gas circulation loop. For example
it can be discharged in the cold end, from (EGO-030), and sent
directly to a steam turbine. The exhaust gas (EG-020) is fed via
the high temperature heat exchanger (H-02) to the membrane module
(X-01). Acting as sweep gas, (EG-030) is receiving oxygen
transported through the membrane from the air side and further
transports the oxygen to the combustion chamber. Thus a closed loop
with a continuous combustion of a carbon rich fuel with O.sub.2 in
a CO.sub.2 and H.sub.2O rich atmosphere is obtained.
[0080] FIG. 9.2 shows how the plenum inlet and outlet 7 and 23 and
heat exchangers (H-01) and (H-02) and the MCM-module (X-01) can be
built into one sealed unit. This is to illustrate one important
feature of the present invention which is the flow direction or
flow paths of the two main streams air and sweep gas that
contributes to minimize the leakage between air and sweep gas
stream. The air stream has a straight flow and flows directly
through the inner closed rooms between the heat exchangers (H-01)
and (H-02) and the MCM-module (X-01), while the sweep gas stream
flows in and out of the open side slots of (H-01), (X-01) and
(H-02). To ensure a pressure build up inside the reactor the sweep
gas should be allowed to fill the open space of the reactor. This
will ensure that only outer reactor shells have to be designed for
withstanding total pressure of the process.
[0081] Table 1 below gives example of data for the process flows
with numbers according to FIG. 9.1. Inlet conditions for the air
stream; 20 bar, 450.degree. C. and 79 kg/s. Oxygen transport
through membrane is 6.12 kg/s (membrane area is installed according
to this). Fuel is added to match the stoichiometry of the
combustion reaction.
[0082] A further advantage will be to have a low pressure
difference (<5 bar) between the air side and the sweep gas side,
preferably with somewhat higher pressure on the sweep gas side.
This will ensure, in case of leakage between the stream and the
sweep gas stream, that the direction of leakage will be from the
sweep gas side (CO.sub.2 and H.sub.2O) into the air side. This will
be less harmful than if air leaks into the combustion loop (sweep
gas), especially from an environmental point of view because in
case of nitrogen (air) leakage into combustion (sweep gas loop) the
NO.sub.x gas could be produced.
[0083] Further, a low pressure difference between air and sweep gas
side will allow designing with thinner walls in monoliths and thus
better heat and oxygen (only X-01) transfer. This will also result
in lower weight.
[0084] Table 1 below gives example of data for the process flows
with numbers according to FIG. 9.1. Inlet conditions for the air
stream; 20 bar, 450.degree. C. and 79 kg/s. Oxygen transport
through membrane is 6.12 kg/s (membrane area is installed according
to this). Fuel is added to match the stoichiometry of the
combustion reaction.
1 TABLE 1 Stream tag no.: Components: AL-010 AL-020 AN-030 AN-050
EG-010 EG-020 Mole Flow kmol/sec CH4 0 0 0 0 0.005724 0.004866 C2+
0 0 0 0 0 0 CO2 0.00090 0.00090 0.00090 0.00090 0.68614 0.58322 N2
2.123768 2.123768 2.123768 2.123768 0.006194 0.005265 O2 0.3784649
0.3784649 0.5697220 0.5697220 0 0 Ar 0.0254891 0.0254891 0.0254891
0.0254891 0 0 H2O 0.0120752 0.0120752 0.0120752 0.0120752 1.212909
1.030973 Total Flow kmol/sec 2.540698 2.540698 2.731956 2.731956
1.91097 1.624324 Total Flow kg/sec 72.88 72.88 79.00 79.00 52.31
44.47 Total Flow cum/sec 13.99 16.33 8.31 14.67 12.16 10.33
Temperature C. 1019 1221 453 1000 1256 1256 Pressure bar 19.60
19.40 20.00 19.80 20.05 20.05 Entholpy kJ/kmol 30140.18 36894.61
11691.54 29700.68 -240270 -240270 Entholpy kJ/kg 1050.729 1286.197
404.3137 1027.1 -8776.913 -8776.913 Entholpy kW 76577.1 93738.07
31940.78 81140.93 -459150 -390280 Entropy J/kmol-K 24739.17
29681.75 6514.543 25024.88 22507.69 22507.69 Entropy J/kg-K
862.4418 1034.747 225.2841 865.4033 822.1919 822.1919 Density
kmol/cum 0.1815737 0.1555783 0.3286462 0.186165 0.1572019 0.1572019
Density kg/cum 5.208446 4.462768 9.503466 5.383335 4.303437
4.303437 Average MW 28.68503 28.68503 28.91701 28.91701 27.37522
27.37522 Stream tag no.: Components: EG-030 EG-040 EGO-010 EGO-020
EGO-030 Mole Flow kmol/sec CH4 0.004866 0.000859 0.004866 0 0 C2+ 0
0 0 0 0 CO2 0.58322 0.10292 0.58322 0.59091 0.59091 N2 0.005265
0.000929 0.005265 0.005290 0.005290 O2 0 0 0.1912572 0.1762761
0.1762761 Ar 0 0 0 0 0 H2O 1.030973 0.1819364 1.030973 1.045701
1.045701 Total Flow kmol/sec 1.624324 0.2866454 1.815581 1.818177
1.818177 Total Flow kg/sec 44.47 7.85 50.59 50.63 50.63 Total Flow
cum/sec 8.96 1.82 9.85 10.47 5.93 Temperature C. 1050 1256 1028
1093 505 Pressure bar 20.00 20.05 19.80 19.80 19.75 Entholpy
kJ/kmol -250840 -240270 -221900 -221700 -248760 Entholpy kJ/kg
-9162.846 -8776.913 -7964.114 -7960.869 -8932.566 Entholpy kW
-407440 -68872.29 -402870 -403080 -452280 Entropy J/kmol-K 15111.08
22507.69 17971.26 20163.23 -5530.105 Entropy J/kg-K 551.9985
822.1919 645.0031 724.0367 -198.5793 Density kmol/cum 0.1812482
0.1572019 0.1843344 0.1737103 0.3064727 Density kg/cum 4.96171
4.303437 5.135978 4.837547 8.53476 Average MW 27.37522 27.37522
27.86228 27.84835 27.84835 Stream tag no.: Components: EGO-040
NG-020 NG-030 OX-010 (*) Mole Flow kmol/sec CH4 0 0.069575 0.001946
0 C2+ 0 0.0009874728 0.00029685977 0 CO2 0.59091 0.00254 0.00007 0
N2 0.005290 0.000904 0.000025 0 O2 0.1762761 0 0 0.1912572 Ar 0 0 0
0 H2O 1.045701 5.02105E-005 1.40470E-006 0 Total Flow kmol/sec
1.818177 0.0836758 2.34093E-003 0.1912572 Total Flow kg/sec 50.63
1.68 0.05 6.12 Total Flow cum/sec 5.83 0.05 0.0015 0.97 Temperature
C. 511 34 34 1000 Pressure bar 20.25 36.00 36.00 21.00 Entholpy
kJ/kmol -248530 -87413.69 -87413.69 32362.44 Entholpy kJ/kg
-8924.502 -4353.816 -4353.816 1011.364 Entholpy kW -451880
-7314.411 -204.6293 6189.548 Entropy J/kmol-K -5449.594 -122240
-122240 21762.67 Entropy J/kg-K -195.6882 -6088.488 -6088.488
680.109 Density kmol/cum 0.3120345 1.533792 1.533792 0.1975274
Density kg/cum 8.689646 30.7947 30.7947 6.32064 Average MW 27.84835
20.07749 20.07749 31.9988 (*) The oxygen flow (OX-010) is not a
physical gas flow as shown in the table. Oxygen is transported
through the membrane as oxygen ions and thus (OX-010) in Table 1 is
for the purpose of calculation.
* * * * *