U.S. patent application number 13/727507 was filed with the patent office on 2014-06-26 for controlled temperature ion transport membrane reactor.
This patent application is currently assigned to KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS. The applicant listed for this patent is KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS. Invention is credited to RACHED BEN-MANSOUR, MOHAMED ABDEL-AZIZ HABIB, MEDHAT AHMED NEMITALLAH.
Application Number | 20140174329 13/727507 |
Document ID | / |
Family ID | 50973180 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140174329 |
Kind Code |
A1 |
NEMITALLAH; MEDHAT AHMED ;
et al. |
June 26, 2014 |
CONTROLLED TEMPERATURE ION TRANSPORT MEMBRANE REACTOR
Abstract
The controlled temperature ion transport membrane reactor is a
combustion-type ion transport membrane reactor for combusting a
hydrocarbon fuel with oxygen. The reactor includes an oxygen
permeable ion transport membrane for separating oxygen from air. In
order to control temperature within the reactor, a thermally
conductive plate is positioned between a mixing passage, where a
diluent gas and the permeated oxygen are mixed, and a reaction
zone. The reaction zone is in fluid communication with the mixing
passage and a fuel chamber through a porous plate for combusting
the hydrocarbon fuel with the oxygen.
Inventors: |
NEMITALLAH; MEDHAT AHMED;
(DHAHRAN, SA) ; HABIB; MOHAMED ABDEL-AZIZ;
(DHAHRAN, SA) ; BEN-MANSOUR; RACHED; (DHAHRAN,
SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS |
Dhahran |
|
SA |
|
|
Assignee: |
KING FAHD UNIVERSITY OF PETROLEUM
AND MINERALS
Dhahran
SA
|
Family ID: |
50973180 |
Appl. No.: |
13/727507 |
Filed: |
December 26, 2012 |
Current U.S.
Class: |
110/190 |
Current CPC
Class: |
Y02E 20/322 20130101;
Y02E 20/344 20130101; F23L 7/007 20130101; F23L 2900/07001
20130101; Y02E 20/32 20130101; Y02E 20/34 20130101 |
Class at
Publication: |
110/190 |
International
Class: |
F23L 7/00 20060101
F23L007/00; F23N 3/00 20060101 F23N003/00 |
Claims
1. A controlled temperature ion transport membrane reactor,
comprising: a reactor housing having first and second laterally
opposed ends, an upper wall, and a lower wall; an oxygen-permeable
ion transport membrane disposed within the reactor housing; an air
passage defined between the oxygen-permeable ion transport membrane
and the upper wall of the reactor housing; an air inlet formed
through the first end of the reactor housing for receiving
pressurized air, the pressurized air passing through the air
passage; a depleted air outlet formed through the second end of the
reactor housing for expelling depleted air following removal of
oxygen therefrom; a thermally conductive plate disposed within the
reactor housing; a mixture passage defined between the
oxygen-permeable ion transport membrane and the thermally
conductive plate; a diluent inlet formed through the second end of
the reactor housing for receiving a diluent gas, the diluent gas
and oxygen permeated through the oxygen-permeable ion transport
membrane mixing in the mixture passage; a porous plate disposed
within the reactor housing; a reaction zone defined between the
thermally conductive plate and the porous plate, the reaction zone
being in fluid communication with the mixture passage; an exhaust
outlet formed through the second end of the reactor housing for
expelling combustion products, a fuel inlet formed through the
second end of the reactor housing; and a fuel chamber defined
between the porous plate and the lower wall of the reactor housing,
the fuel inlet being in fluid communication with the fuel chamber;
wherein a hydrocarbon fuel injected into the fuel inlet passes from
the fuel chamber through the porous plate and reacts with the
diluent gas and the oxygen in the reaction zone to generate heat
and the combustion products.
2. The controlled temperature ion transport membrane reactor as
recited in claim 1, further comprising a channel positioned
adjacent the first end of the reactor housing, the channel
connecting the reaction zone with the mixture passage.
3-7. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to combustion reactors, and
particularly to a controlled temperature ion transport membrane
reactor including a thermally conductive plate for controlling
reaction temperatures.
[0003] 2. Description of the Related Art
[0004] FIG. 2 illustrates a conventional ion transport membrane
reactor 100. In the example of FIG. 2, an oxygen combustion reactor
is illustrated. Such reactors are typically cylindrical, including
an outer cylindrical wall 114 and an inner cylindrical ion
transport membrane 116 positioned coaxially therein. As shown,
pressurized environmental air A (typically provided by a compressor
or the like) is pumped within annular regions 126, which are
defined between the cylindrical shell of the respective inner
cylindrical ion transport membrane 116 and the inner surface of the
cylindrical wall 114.
[0005] Gaseous hydrocarbon fuel F is pumped into a central region
124 (which often includes additional carbon dioxide, depending upon
the particular application and implementation of the reactor),
defined by the inner cylindrical ion transport membrane 116. The
inner cylindrical ion transport membrane 116 separates O.sub.2 from
air A, allowing only O.sub.2 to pass therethrough from the annular
region 126 into the central region 124.
[0006] The gaseous O.sub.2 is transported from the annular region
126 to the inner surface of the inner cylindrical ion transport
membrane 116 for combustion with fuel F within the central region
124. This combustion results in the production of gaseous CO.sub.2
and H.sub.2O vapor. Combustion of the fuel F with the O.sub.2
within reactor 100 generates heat, resulting in high temperature
combustion products, which are then used to drive some external
apparatus, such as a turbine or the like. Further, gaseous nitrogen
(N.sub.2), which remains after the O.sub.2 is removed from the air
A, is channeled to an external reservoir or the like.
[0007] The driving force for oxygen permeation across the membrane
116 is the oxygen potential gradient, i.e., the oxygen partial
pressure. Thus, an ion transport membrane (ITM) air separation unit
model must include an expression relating the local oxygen flux
through the membrane to the local temperature, the oxygen partial
pressures of each stream, and the membrane thickness for a given
material. The "oxygen partial pressures" refer to the local values
directly adjacent to either side of the membrane surface in the
gaseous phase. Similarly, "temperature" refers to the local value
at the membrane surface. The oxygen permeation flux J.sub.02 as a
function of partial pressure of O.sub.2 on both sides (P'.sub.02
and P''.sub.02) and the membrane temperature is given by:
J O 2 = D V K r ( P O 2 ' - P O 2 '' ) 2 LK f P O 2 ' P O 2 '' + D
V ( P O 2 ' + P O 2 '' ) , ##EQU00001##
where D.sub.v, K.sub.r and K.sub.f are functions of temperature and
the specific properties of the membrane, and are determined by
fitting experimental oxygen flux data as a function of temperatures
and oxygen partial pressure gradients.
[0008] The oxygen permeation at low temperatures
(.about.750.degree. C.) is limited by the rate of oxygen-ion
recombination, but is dominantly controlled by bulk diffusion at
high temperatures (.about.950.degree. C.). However, the oxygen
permeation is very low at low temperatures. ITM systems, however,
operate at relatively high temperatures; e.g., above 1000 K, and
rely on a difference in O.sub.2 chemical potential to drive the
separation process. Typical ITM operating conditions consist of a
membrane surface temperature between 1000 K and 1270 K, and an
oxygen partial pressure difference across the membrane ranging from
0.2 to a few bars. Thermal stresses can lead to membrane cracks due
to the multi-layered nature of the fabrication process, or
non-uniform temperature fields inside the ITM reactor.
[0009] The local membrane temperature is a critical ITM parameter
that must be monitored and controlled. Specifically, the oxygen
permeation through the membrane has Arrhenius dependence on the
local temperature, which, in general, is different from the bulk
temperature. Further, excessive membrane temperatures must be
avoided in order to avoid material failure. Thus, the heat transfer
between the feed and permeate must be calculated as a function of
operating conditions in order to correctly model ITM performance
and operating constraints.
[0010] For separation-only ITM reactors, acceptable inlet
temperatures eliminate the possibility of local excessive heating,
but the local temperature must still be determined in order to
calculate the local oxygen flux. However, for reactive ITM
applications, the local heat transfer away from the reaction zone
must be large enough to accommodate the local heat release from the
chemical reactions.
[0011] For low local membrane temperature, the flux is nearly
insensitive to the partial pressure gradient because of the
relatively slow kinetics resulting from the Arrhenius dependence.
However, in the high-temperature range, the sensitivity to partial
pressure gradients is significant as the diffusive resistance
becomes dominant. In other words, the Arrhenius term e.sup.-Ea/RT
included in the diffusion coefficient of oxygen vacancies in the
oxygen permeation flux equation is extremely small for low
temperatures. This implies that the membrane axial temperature
profile must be controlled and maintained near the maximum
temperature limit in order for large partial pressure differences
to matter. Thus, an ITM reactor designed with the intent to exploit
large partial pressure differences would only be successful if the
temperature is maintained at a high level. It can be clearly seen
that both oxygen partial pressures and local temperature are
important in the high-performance operating regime. Thus, it would
be desirable to provide an ITM reactor that takes advantage of
both.
[0012] Thus, a controlled temperature ion transport membrane
reactor solving the aforementioned problems is desired.
SUMMARY OF THE INVENTION
[0013] The controlled temperature ion transport membrane reactor
includes a reactor housing having first and second laterally
opposed ends, an upper wall, and a lower wall. An oxygen-permeable
ion transport membrane is disposed within the reactor housing. An
air passage is defined between the oxygen-permeable ion transport
membrane and the upper wall of the reactor housing. An air inlet is
formed through the first end of the reactor housing for receiving
pressurized air, which passes through the air passage, and a
depleted air outlet is formed through the second end of the reactor
housing for expelling depleted air following removal of oxygen
therefrom. A thermally conductive plate is also disposed within the
reactor housing. A mixture passage is defined between the
oxygen-permeable ion transport membrane and the thermally
conductive plate. A diluent inlet is formed through the second end
of the reactor housing for receiving a diluent gas. The diluent gas
and the oxygen permeated through the oxygen-permeable ion transport
membrane mix in the mixture passage.
[0014] A porous plate is disposed within the reactor housing. A
reaction zone is defined between the thermally conductive plate and
the porous plate. An exhaust outlet is formed through the second
end of the reactor housing for expelling combustion products. The
reaction zone is in fluid communication with the mixture passage. A
fuel inlet is formed through the second end of the reactor housing.
The fuel inlet is in fluid communication with a fuel chamber
defined between the porous plate and the lower wall of the reactor
housing. A hydrocarbon fuel passes through the porous plate to
react with the diluent gas and the oxygen in the reaction zone to
generate heat and the combustion products.
[0015] In an alternative embodiment, the controlled temperature ion
transport membrane reactor includes a reactor housing having first
and second laterally opposed ends, an upper wall, and a lower wall.
An oxygen-permeable ion transport membrane is disposed within the
reactor housing. An air passage is defined between the
oxygen-permeable ion transport membrane and the upper wall of the
reactor housing. An air inlet is formed through the first end of
the reactor housing for receiving pressurized air, which passes
through the air passage, and a depleted air outlet is formed
through the second end of the reactor housing for expelling
depleted air following removal of oxygen therefrom.
[0016] A thermally conductive plate is disposed within the reactor
housing. A mixture passage is defined between the oxygen-permeable
ion transport membrane and the thermally conductive plate. A
diluent inlet is formed through the second end of the reactor
housing for receiving a diluent gas. The diluent gas and the oxygen
that permeates through the oxygen-permeable ion transport membrane
mix in the mixture passage. In this alternative embodiment, the
thermally conductive plate is divided into first and second
portions. The first portion is formed from a first material and the
second portion is formed from a second material. A thermal
conductivity of the first material is greater than a thermal
conductivity of the second material.
[0017] A fuel inlet is formed through the first end of the reactor
housing. The fuel inlet is in fluid communication with a fuel
chamber defined between the thermally conductive plate and the
lower wall of the reactor housing. The fuel chamber is in fluid
communication with the mixture passage, such that a hydrocarbon
fuel entering the fuel chamber through the fuel inlet reacts with
the diluent gas and the oxygen in the fuel chamber. The fuel
chamber is divided into a flame zone adjacent the second portion of
the thermally conductive plate and a combustion products portion
adjacent the first portion of the thermally conductive plate. An
exhaust outlet is formed through the first end of the reactor
housing.
[0018] These and other features of the present invention will
become readily apparent upon further review of the following
specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a diagrammatic side view in section of a first
embodiment of a controlled temperature ion transport membrane
reactor according to the present invention.
[0020] FIG. 2 is a diagrammatic side view in section of a
conventional oxygen transport reactor of the prior art .
[0021] FIG. 3 is a diagrammatic side view in section of an
alternative embodiment of a controlled temperature ion transport
membrane reactor according to the present invention.
[0022] Similar reference characters denote corresponding features
consistently throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] As shown in FIG. 1, the controlled temperature ion transport
membrane reactor 10 includes a reactor housing 14 having first and
second laterally opposed ends, 40, 38, respectively, an upper wall
36, and a lower wall 34. An oxygen-permeable ion transport membrane
16 is disposed within the reactor housing 14. An air passage 26 is
defined between the oxygen-permeable ion transport membrane 16 and
the upper wall 36 of the reactor housing 14. An air inlet 12 is
formed through the first end 40 of the reactor housing for
receiving pressurized air A adjacent the upper wall 36, which
passes through the air passage 26, and a depleted air outlet 60 is
formed through the second end 38 of the reactor housing 14 for
expelling depleted air following removal of oxygen therefrom. The
depleted air is primarily N.sub.2 gas.
[0024] A thermally conductive plate 20 is also disposed within the
reactor housing 14. A mixture passage 24 is defined between the
oxygen-permeable ion transport membrane 16 and the thermally
conductive plate 20. The material forming the plate 20 is
preferably selected to have a desired conductivity in order to
control the required amount of heat that will reach the membrane
surface. In conventional membrane reactors, the membrane surface
temperature has a certain thermal limit, and once temperatures
beyond this limit have been passed, the membrane will be destroyed.
The controlled temperature of the present reactor 10, provided by
thermally conductive plate 20, allows for avoidance of such
membrane rupture.
[0025] A diluent inlet 18 is formed through the second end 38 of
the reactor housing 14 for receiving a diluent gas D. The diluent
gas D and oxygen permeated through the oxygen-permeable ion
transport membrane 16 mix in the mixture passage 24. The diluent
gas D may be pressurized carbon dioxide. The diluent gas D
(sometimes referred to as a "sweep gas") purges the oxygen in order
to reduce the partial pressure of O.sub.2, thus increasing the
oxygen flux through the membrane 16.
[0026] A porous plate 30 is disposed within the reactor housing 14.
A reaction zone 28 is defined between the thermally conductive
plate 20 and the porous plate 30. An exhaust outlet 22 is formed
through the second end 38 of the reactor housing 14 for expelling
combustion products, which are primarily carbon dioxide and water
vapor. The reaction zone 28 is in fluid communication with the
mixture passage 24 via a channel 52 formed adjacent the first end
40.
[0027] A fuel inlet 32 is formed through the second end 38 of the
reactor housing 14. The fuel inlet 32 is in fluid communication
with a fuel chamber 50 defined between the porous plate 30 and the
lower wall 34 of the reactor housing 14. A hydrocarbon fuel F is
injected through the fuel inlet 32, into the fuel chamber 50, and
passes through the porous plate 30 to react with the mixture of
diluent gas D and oxygen in the reaction zone 28 to generate heat
and the combustion products. The diluent gas D works in the
reaction zone 28 as the energy carrier medium. The flow of the
diluent gas D in the mixing passage 24, preferably at high
velocity, causes more oxygen to be extracted from the air A in
order to be used in the adjacent reaction zone 28 in the combustion
process.
[0028] The counter-current profile of reactor 10 provides
advantages over the conventional reactor design of FIG. 2. The
partial pressure difference is essentially constant along the
reactor length, thus providing good material stability potential by
minimizing chemical expansion stress. Further, in this
counter-current flow configuration, the more sensitive region where
the permeate partial pressure is low coincides with the region
where the feed partial pressure is low, thus providing a better
match than the conventional co-current case, where the
high-pressure feed matches up with the low-low pressure
permeate.
[0029] In an alternative embodiment, illustrated in FIG. 3,
controlled temperature ion transport membrane reactor 200 includes
a reactor housing 214 having first and second laterally opposed
ends 240, 238, respectively, an upper wall 236, and a lower wall
234. An oxygen-permeable ion transport membrane 216 is disposed
within the reactor housing 214. An air passage 226 is defined
between the oxygen-permeable ion transport membrane 216 and the
upper wall 236 of the reactor housing 214. An air inlet 212 is
formed through the first end 240 of the reactor housing 214 for
receiving pressurized air A. The pressurized air A passes through
the air passage 226, and a depleted air outlet 260 is formed
through the second end 238 of the reactor housing 214 for expelling
depleted air following removal of oxygen therefrom.
[0030] A thermally conductive plate 254 is disposed within the
reactor housing 214. A mixture passage 224 is defined between the
oxygen-permeable ion transport membrane 216 and the thermally
conductive plate 254. A diluent inlet 218 is formed through the
second end 238 of the reactor housing 214 for receiving a diluent
gas D. The diluent gas D and oxygen permeated through the
oxygen-permeable ion transport membrane 216 mix in the mixture
passage 224. In this alternative embodiment, the thermally
conductive plate 254 is divided into first and second portions 220,
221, respectively. The first portion 220 is formed from a first
material, and the second portion 221 is formed from a second
material. The thermal conductivity of the first material is greater
than the thermal conductivity of the second material.
[0031] A fuel inlet 232 is formed through the first end 240 of the
reactor housing 214. The fuel inlet 232 is in fluid communication
with a fuel chamber 250 defined between the thermally conductive
plate 254 and the lower wall 234 of the reactor housing 214. The
fuel chamber 250 is in fluid communication with the mixture passage
224 via a channel 252 adjacent the first end 240, such that a
hydrocarbon fuel F entering the fuel chamber 250 through the fuel
inlet 232 reacts with the mixture of diluent gas D and oxygen in
the fuel chamber 250.
[0032] The fuel chamber 250 is divided into a high temperature
flame zone 230 adjacent the second portion 221 of the thermally
conductive plate 254 and a lower temperature combustion products
portion 228 adjacent the first portion 220 of the thermally
conductive plate 254. An exhaust outlet 222 is formed through the
first end 238 of the reactor housing 214. In reactor 200, in order
to maintain the surface temperature of the membrane 216 constant
along the whole reactor length, two different materials with
different thermal conductivities are used to form the plate 254.
The lower conductivity portion 221 is used adjacent the high
temperature flame zone 230, and the high conductivity portion 220
is used adjacent the low temperature combustion product zone 228.
The length of each conductive portion 220, 221 is preferably
controlled according to the amount of permeated oxygen, the fuel
flow, and, accordingly, the flame length, i.e., the reactor design
function decides the length of each portion 220, 221 according to
the flame length.
[0033] It is to be understood that the present invention is not
limited to the embodiments described above, but encompasses any and
all embodiments within the scope of the following claims.
* * * * *