JP2005276836A - Method and system for start and transient operation of fuel cell-gas turbine combined system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell-gas turbine combined system. <P>SOLUTION: This fuel cell-gas turbine combined system 100 can include a solid electrolyte type fuel cell 102, an air compressor 106, a fuel treating device 110, a starting combustor 112 for generating exhaust gas, the first control means for orienting a pressurized air flow from the air compressor 106 to the starting combustor 112 and the solid electrolyte type fuel cell 102, and the second control means for orienting the pressurized air flow to the starting combustor 112 and the fuel treating device 110. The first control means and the second control means can control feeding of the pressurized air and a pressurized fuel to the starting combustor 112 so as to heat the fuel treating device 110 up to a prescribed temperature by the exhaust gas from the starting combustor 112 before the pressurized fuel is fed to the fuel treating device 110 and the pressurized air is fed to the solid electrolyte type fuel cell 102. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates generally to a power generation fuel cell-gas turbine combined system, such as a solid oxide fuel cell-gas turbine combined system. More specifically, the present invention relates to a system and method for startup and transient operation of a fuel cell-gas turbine combined system.

  It has been proposed to combine a fuel cell generator with a gas turbine. A gas turbine compressor can supply the pressurized air required by a fuel cell operating at high pressure, and a fuel cell that can be a high temperature fuel cell, such as a solid oxide fuel cell, is installed in the turbine. Hot gas for expansion can be generated. Thus, power can be generated by both the fuel cell generator and the turbine.

  Many such systems use a fuel processor that reforms a fuel, such as natural gas, into a hydrogen-containing gas. Due to the nature of chemical reactions that take place inside the fuel processor, heat must generally be supplied to the fuel processor. By-product heat is generated in the fuel cell during normal operation. In addition, unreacted fuel and / or new fuel and air from the fuel cell can be burned to obtain additional thermal energy. By-product heat from the fuel cell and / or excess fuel and energy from the combustion of air can be used to provide the heat required by the fuel processor.

Fuel cells, particularly solid oxide fuel cells, generally operate at high temperatures. Therefore, this battery generally requires a long heating time from the atmospheric temperature at start-up. Fuel cells and external fuel processors exhibit large thermal inertia and require temperature ramp rates to be controlled during system startup and rapid transients.
US Pat. No. 5,413,879

  Therefore, it would be beneficial to improve start-up and transient operation of the fuel cell-gas turbine combined system. Specifically, the thermal complex of the solid oxide fuel cell, the gas turbine, and the additional heat source can provide more efficient start-up and transient operation, and can increase the system peak capacity. .

  Accordingly, the present invention can provide a fuel cell-gas turbine combined system, the fuel cell-gas turbine combined system comprising a fuel cell, an air compressor, a fuel processing device, and startup combustion that generates exhaust. And a first control means for directing the pressurized air stream from the air compressor to the startup combustor and the fuel cell, and a second for directing the pressurized fuel stream to the startup combustor and the fuel processor. Control means. The first control means and the second control means are configured to cause the fuel processor to be exhausted by the start-up combustor exhaust before the pressurized fuel stream is delivered to the fuel processor and the pressurized air stream is delivered to the fuel cell. Delivery of the pressurized air stream and pressurized fuel stream to the startup combustor can be controlled to heat to a predetermined temperature. The fuel cell can be a solid oxide fuel cell.

  In certain embodiments, the first control means may initially direct all of the pressurized air flow to the startup combustor and the second control means may initially start up all of the pressurized fuel flow. Can be oriented in the vessel. When the fuel processor reaches a predetermined temperature, the first control means solidifies the incremental portion of the pressurized air flow until all of the pressurized air flow is delivered to the solid oxide fuel cell. The second control means can be directed to the electrolyte fuel cell and the second control means fuel treats the incremental portion of the pressurized fuel stream until all of the pressurized fuel stream is delivered to the fuel processor. It can be oriented to the device. The predetermined temperature may be a required operating temperature of the fuel processor.

  The first control means can be a three-way valve or, in other embodiments, two two-way valves. The second control means can be an activation valve and a flow control valve. The start valve may be a two-way valve that controls the delivery of pressurized fuel flow to the start combustor. The flow control valve can be a two-way valve that controls the delivery of pressurized fuel flow to the fuel processor.

  In certain embodiments, the solid oxide fuel cell can generate exhaust that is used to supply heat to the fuel processor. The incremental portion of the pressurized air flow that is directed to the solid oxide fuel cell at start-up is the exhaust of the solid oxide fuel cell until all of the pressurized air flow is directed to the solid oxide fuel cell. Can be increased at a first predetermined rate that allows it to be sufficient to supply all of the heat used in the fuel processor. Similarly, the incremental portion of the pressurized fuel stream that is directed to the fuel processor is such that the exhaust of the solid oxide fuel cell is not subject to the fuel treatment until all of the pressurized fuel stream is directed to the fuel processor. It can be increased at a second predetermined rate that allows it to be sufficient to supply all of the heat used in the device.

  The system can include a SOFC combustor. The SOFC combustor is supplied with unreacted fuel and excess air from the solid oxide fuel cell, and can burn the unreacted fuel with excess air to increase the heat of the exhaust of the solid oxide fuel cell. The system can further include a SOFC check valve located downstream of the SOFC combustor.

  The turbine of the solid oxide fuel cell-gas turbine combined system can generate exhaust. The system may further include a fuel preheater / steam generator that exchanges heat between the turbine exhaust and feed water to provide steam to the fuel processor. The fuel preheater / steam generator can also exchange heat between the turbine exhaust and the pressurized fuel stream to deliver a heated pressurized fuel stream to the fuel processor.

  In certain embodiments, once the fuel processor has reached a predetermined temperature, the first time until the exhaust of the solid oxide fuel cell is sufficient to supply all of the heat used by the fuel processor. The control means can direct the incremental portion of the pressurized air flow to the solid oxide fuel cell, and the second control means can direct the incremental portion of the pressurized fuel flow to the fuel processor. When reaching the point where the exhaust of the solid oxide fuel cell is sufficient to supply all of the heat used in the fuel processor, the first control means converts all of the pressurized air flow to the solid electrolyte type. Oriented to the fuel cell and the second control means directs all of the pressurized fuel stream to the fuel processor.

  The present invention further provides a method for start-up operation of a solid oxide fuel cell-gas turbine combined system having a solid oxide fuel cell, a fuel processing device, a compressor, a fuel pump, and a start-up combustor. . The method includes directing a pressurized air stream from an air compressor to the starter combustor, directing a pressurized fuel stream to the starter combustor, and a pressurized air stream directed to the starter combustor and an additive. Combusting a pressurized fuel stream in the startup combustor to produce exhaust, heating the fuel processor with the exhaust of the startup combustor, and generating a pressurized air stream when the fuel processor reaches a predetermined temperature. Transitioning from the startup combustor to the solid oxide fuel cell and transitioning the pressurized fuel stream from the startup combustor to the fuel processor. The phase of moving the pressurized air stream from the startup combustor to the solid oxide fuel cell starts the incremental portion of the pressurized air stream until all of the pressurized air stream is directed to the solid oxide fuel cell Orienting from the combustor to the solid oxide fuel cell may be included. Similarly, the step of transferring the pressurized fuel stream from the startup combustor to the fuel processor is to start up the incremental portion of the pressurized fuel stream until all of the pressurized air stream is directed to the fuel processor. Orienting the vessel to the fuel processor. The predetermined temperature of the fuel processor can be a required operating temperature of the fuel processor.

  In certain embodiments, the method may further comprise heating the fuel processor with the exhaust of the solid oxide fuel cell. In this case, the gradually increasing portion of the pressurized air flow oriented to the solid oxide fuel cell is the same as that of the solid oxide fuel cell until all of the pressurized air flow is directed to the solid oxide fuel cell. The exhaust can be increased at a first predetermined rate that allows the exhaust to be sufficient to supply all of the heat used in the fuel processor. Similarly, the incremental portion of the pressurized fuel stream that is directed to the fuel processor is such that the exhaust of the solid oxide fuel cell is not subject to the fuel treatment until all of the pressurized fuel stream is directed to the fuel processor. It can be increased at a second predetermined rate that allows it to be sufficient to supply all of the heat used in the device.

  The pressurized air stream can be directed to the start-up combustor and / or solid oxide fuel cell by a three-way valve. The pressurized fuel stream can be directed to the starter combustor and / or fuel processor by the starter valve and the flow control valve. The start-up valve can include a two-way valve that controls the delivery of pressurized fuel flow to the start-up combustor. The flow control valve can include a two-way valve that controls the delivery of pressurized fuel flow to the fuel processor.

  In certain embodiments, the method may further comprise the step of combusting the feed unreacted fuel from the solid oxide fuel cell with feed excess air to increase the heat of the solid oxide fuel cell exhaust. In another embodiment, the method further includes generating exhaust from the turbine, supplying heat to the fuel processor by exchanging heat between the turbine exhaust and feed water, and exhausting and adding to the turbine. Heat exchange with the pressurized fuel stream and delivering a heated pressurized fuel stream to the fuel processor.

  The method further includes heating the fuel processor with the exhaust of the solid oxide fuel cell. In this case, the stage of moving the pressurized air stream from the start-up combustor to the solid oxide fuel cell is sufficient for the exhaust of the solid oxide fuel cell to supply all the heat used in the fuel processor. Until then, the method may include directing an increasing portion of the pressurized air flow from the startup combustor to the solid oxide fuel cell. Similarly, the phase of moving the pressurized fuel stream from the startup combustor to the fuel processor is sufficient until the exhaust of the solid oxide fuel cell is sufficient to supply all the heat used by the fuel processor. May include directing an incremental portion of the pressurized fuel stream from the startup combustor to the fuel processor. When the exhaust of the solid oxide fuel cell reaches a point where it is sufficient to supply all of the heat used in the fuel processor, all of the pressurized air flow can be directed to the solid oxide fuel cell. And all of the pressurized fuel stream can be directed to the fuel processor.

  The present invention further provides a method of operating a solid oxide fuel cell-gas turbine combined system having a solid oxide fuel cell, a fuel processor, a turbine, a compressor, a fuel pump, and a startup combustor. The method includes directing a pressurized air stream from a compressor to a startup combustor and a solid oxide fuel cell, directing the pressurized fuel stream to a startup combustor and a fuel processor, and startup. Heating the fuel processor with the exhaust of the combustor and the exhaust of the solid oxide fuel cell. During steady state operation of the system, all of the pressurized air stream can be directed to the solid oxide fuel cell and all of the pressurized fuel stream can be directed to the fuel processor. During transient operation of the system, the pressurized fuel flow can be increased so that the increasing portion of the pressurized fuel flow and the increasing portion of the pressurized air flow can be directed to the startup combustor for combustion and The pressurized air flow can be increased.

  The method further expands the startup combustor exhaust and the solid oxide fuel cell exhaust through the turbine to generate mechanical energy, which is generated by the turbine by the resulting increase in startup combustor exhaust during the transient. Including causing an increase in the amount of mechanical energy produced. The increased amount of mechanical energy can be directed to the generator. Alternatively, the increased amount of mechanical energy can be directed to the compressor so that the compressor can further increase the pressurized air flow using the increased amount of mechanical energy. In this case, the method further directs a portion of the increased pressurized air stream to the solid oxide fuel cell and uses the increased start-up combustor exhaust to provide additional heat to the fuel processor. A step of increasing the supply of reformed fuel delivered to the solid oxide fuel cell using additional heat, an increased pressurized air flow and an increased reformed fuel supply. Reacting inside the fuel cell.

  In certain embodiments, the method further includes providing increased exhaust air flow from the solid oxide fuel cell due to the increased pressurized air flow delivered to the solid oxide fuel cell and the increased reformate supply. Generating a quantity. Once the increased exhaust supply from the solid oxide fuel cell is sufficient to supply all of the heat used by the fuel processor to produce the increased reformate supply, A pressurized air stream is transferred from the startup combustor to the solid oxide fuel cell and a pressurized fuel stream is transferred from the startup combustor to the fuel processor. The phase of moving the pressurized air stream from the startup combustor to the solid oxide fuel cell starts the incremental portion of the pressurized air stream until all of the pressurized air stream is directed to the solid oxide fuel cell Orienting from the combustor to the solid oxide fuel cell may be included. Similarly, the step of transferring the pressurized fuel stream from the startup combustor to the fuel processor is to start up the incremental portion of the pressurized fuel stream until all of the pressurized air stream is directed to the fuel processor. Orienting the vessel to the fuel processor.

  These and other features of the present invention will become apparent upon review of the following detailed description of this embodiment of the invention, taken in conjunction with the drawings and claims.

  Referring now to the drawings, FIG. 1 illustrates a solid oxide fuel cell-gas turbine system 100 that is an exemplary embodiment of the present invention. It will be apparent to those skilled in the art that other high temperature fuel cells can be used in such a system, and the use of solid oxide fuel cells is merely exemplary. The main components of the solid oxide fuel cell-gas turbine system 100 include a solid oxide fuel cell 102, a turbine 104, a compressor 106, a generator 108, a fuel processing device 110, and a startup combustor 112. A pressurized air valve 114, which can be one three-way valve or two two-way valves, an activation valve 116, and a flow control valve 118 can be included. In the solid oxide fuel cell-gas turbine system 100, other components including a fuel preheater / steam generator 122, a recuperator 124, a SOFC combustor 126, and a fuel cell air preheater 128 are provided. It can also increase the overall efficiency of the system.

  In general, during normal steady state operation, hot gas supplied from the exhaust of the solid oxide fuel cell 102 can be expanded through the turbine 104. The turbine 104 can sequentially drive the compressor 106 and the generator 108. The compressor 106 can supply pressurized air to the solid oxide fuel cell 102 operable at a high pressure. The solid oxide fuel cell 102 can generate electricity by electrochemically reacting the supplied pressurized air with the supplied reformed fuel from the fuel processor 110. The solid oxide fuel cell 102 can generate high-temperature gas supply exhaust. Unreacted fuel and air contained in the exhaust of the solid oxide fuel cell 102 can be combusted in the SOFC combustor 126 to give additional heat energy to the exhaust. Further, in certain embodiments, the new electrolyte fuel and air in the SOFC combustor 126 are added to the unreacted fuel and air from the solid oxide fuel cell 102 and the solid electrolyte after passing through the SOFC combustor 126. The heat of the exhaust of the fuel cell 102 can be increased. Heat from the exhaust of the solid oxide fuel cell 102 can be used to supply heat to the fuel processor 110 that reforms a gaseous fuel such as natural gas. The fuel processor 110 can be supplied with pressurized gas fuel. Once the cycle is complete, the exhaust from the solid oxide fuel cell 102 can then be expanded through the turbine. Accordingly, both the solid oxide fuel cell 102 and the turbine 104 can generate electric power.

  During start-up operation, the solid oxide fuel cell-gas turbine system 100 can be operated as follows. The start valve 116 and the flow control valve 118 can be supplied with pressurized fuel from the fuel feed 129. Supply pressurized fuel can be supplied to the fuel feed 129 by methods commonly known in the art, including by a radial fuel pump (not shown). The fuel can be natural gas or coal derived fuel. For example, natural gas, naphtha, propane, JP-8, methane, gasoline or other types of similar gases can be used.

  At the start of the startup process, the startup valve 116 is opened, thereby allowing the supplied pressurized fuel to reach the startup combustor 112. At the start of the start-up process, the flow control valve 118 is closed, thereby preventing the supplied pressurized fuel from reaching the fuel processor 110, the solid oxide fuel cell 102, and other downstream components. Activation valve 116 and flow control valve 118 can be any suitable type of commercially available valve known in the art. For example, ball valves, butterfly valves, or other similar valves can be used. In another embodiment, a single three-way valve can replace the start valve 116 and the flow control valve 118.

  The supplied pressurized fuel can be injected into the startup combustor 112 and can be mixed within the startup combustor 112 with the supplied pressurized air that can be supplied from the compressor 106 as described below. The resulting mixture can be ignited by an igniter to cause an exothermic reaction, thereby producing a supplied thermal energy combustion gas. Start-up combustor 112 can be any suitable type of combustor known in the art. Examples of suitable combustors that can be purchased may include low NOx combustors, catalytic combustors, or other similar combustors that can be used. The supplied thermal energy combustion gas then moves from the startup combustor to the mixing point 130 where the supplied thermal energy combustion gas from the startup combustor 112 mixes with the supply exhaust from the solid oxide fuel cell 102. can do. In the first stage of the start-up process, the flow control valve 118 is kept closed (thus preventing the supplied fuel from reaching the solid oxide fuel cell 102), and thus the solid oxide fuel cell 102. There will be no supply exhaust from. The SOFC check valve 131 can be disposed upstream of the mixing point 130 on a line for supplying exhaust from the solid oxide fuel cell 102. The SOFC check valve 131 can prevent the supplied thermal energy combustion gas from flowing back from the startup combustor 112 to upstream components including the solid oxide fuel cell 102.

  The start-up combustor and the solid oxide fuel cell feed mixed exhaust can then be directed from the mixing point 130 through the fuel processor 110. Inside the fuel processor 110, the mixed stream is directed through one or more heat exchangers, thereby supplying heat to the fuel processor 110. The fuel processor 110 must be heated from ambient temperature at start-up to a sufficient temperature before fuel reforming can be performed. Once heated, the fuel processor 110 can partially convert the fuel to a hydrogen-containing gas using steam reforming, autothermal reforming, partial oxidation reforming, or other processes. For illustration purposes only, FIG. 1 uses a steam reformer in which gaseous hydrocarbons are reformed in the presence of steam and catalyst to a gas comprising essentially hydrogen and carbon monoxide. Indicates the system. The fuel is preheated and supplied to the fuel processor 110 by the fuel preheater / steam generator 122 as described in more detail below. Examples of suitable commercially available fuel processors 110 known in the art include steam reformers, automatic thermal reformers, or other similar processors. Heat exchange from the mixed exhaust stream to the fuel processor 110 can be performed by heat exchange methods known in the art.

  The mixed feed thermal energy combustion gases from the startup combustor 112 and the exhaust of the solid oxide fuel cell 102 can then exit the fuel processor 110 and be directed to the turbine 104. The mixed stream can be expanded through the turbine 104 to produce turbine output. Examples of suitable commercially available turbines known in the art include centrifugal turbines, axial turbines or other similar turbines that can be used. The turbine output drives the compressor 106 and the generator 108 in sequence. The generator 108 can generate electric power, and the electric power can be converted into alternating current by the inverter 132 and supplied to the power grid 134. The compressor 106 can receive supply of air from the air feed 135 and generate supply pressurized air. Supply pressurized air can be delivered to the pressurized air valve 114.

  The recuperator 124 can be placed upstream of the pressurized air valve 114 to increase the overall efficiency of the system. The recuperator 124 can transfer the heat of the supply exhaust gas from the turbine 104 to the supply pressurized air from the compressor 106. Preheating the supplied pressurized air in this manner can reduce the fuel consumption of the system 100 and increase its overall efficiency. The pressurized air can be circulated through the low temperature side passage of the recuperator 124 and can absorb heat from the turbine exhaust gas that can be circulated through the high temperature side passage. Thus, if a recuperator 124 is present in the system 100, the supplied pressurized air can be heated so that the supplied heated pressurized air can be directed to the pressurized air valve 114.

  In the pressurized air valve 114 shown as a three-way valve, the supplied pressurized air (or supplied heated pressurized air) is oriented to either the start-up combustor 112 or the solid oxide fuel cell 102 or supplied pressurized air. Can be split and fed to both components. During start-up operation, the pressurized air valve 114 can be set to initially direct the flow of pressurized air toward the start-up combustor 112. The pressurized air valve 114 can be any suitable type of three-way valve known in the art, such as a ball valve or other similar valve that can be used. In another embodiment, the function of the pressurized air three-way valve 114 can be achieved by a connection and two separate two-way valves.

  Accordingly, the supplied pressurized air can be delivered to the startup combustor 112 and burned with the supplied pressurized gas fuel in the startup combustor 112. As described above, the exhaust from the startup combustor 112 can then be used to heat the fuel processor 110 during the initial stage of the startup process. Accordingly, the pressurized air valve 114, the start valve 116, the flow control valve 118, and the SOFC check valve 131 remove the solid oxide fuel cell 102 from the air flow and the fuel flow and the back flow of the start combustor 112 exhaust during the start process. Isolation can protect the fuel cell components. For example, the SOFC check valve 131 can also prevent backflow of combustion gases from the startup combustor 112 that can damage the solid oxide fuel cell 102 and its components.

  As the startup process continues, the temperature of the fuel processor 110 can rise to the required temperature for fuel reforming. For example, the temperature at which the steam fuel processor begins efficient fuel reforming can be about 450 ° C. (840 ° F.). When this temperature is reached, the flow control valve 118 can be opened to supply a portion of the supplied pressurized fuel to the fuel processor 110 to initiate reforming. In order to increase the overall efficiency of the system, the pressurized fuel supply initially bypasses the fuel preheater / steam generator 122. The fuel preheater / steam generator 122 can exchange heat between the exhaust of the turbine 104 and the supplied pressurized fuel. The fuel preheater / steam generator 122 can also exchange heat between the exhaust of the turbine 104 and the feed water. The fuel preheater / steam generator 122 can provide either one or both functions, depending on system configuration and needs, or these components can be replaced by separate components instead of composite components. Note that each of the functions can be provided. Water can be supplied by the water feed 136 to the fuel preheater / steam generator 122 to produce steam and then supplied to the fuel processor 110 for steam reforming of the supplied pressurized fuel. In other embodiments, other types of fuel reforming that do not require steam can be used. Heat exchange between the turbine 104 exhaust and the pressurized fuel / feedwater within the fuel preheater / steam generator 122 can be performed by heat exchange methods known in the art. Turbine 104 exhaust can exit system 100 via system exhaust 137 after exiting fuel preheater / steam generator 122.

  The supplied pressurized fuel can then be reformed in the fuel processor 110 as described above to produce a hydrogen-containing gas. The supplied reformed fuel can be supplied from the fuel processing apparatus 110 to the solid oxide fuel cell 102. As described above, the solid oxide fuel cell 102 can also be supplied with a pressurized air flow via the pressurized air valve 114. When the flow control valve 118 is opened to supply the supply reformed fuel to the solid oxide fuel cell 102, the pressurized air valve 114 also provides the appropriate supply pressurized air as well as the solid oxide fuel cell 102. And can be opened to allow the feed reformed fuel to react electrochemically. To increase the overall efficiency of the system, the supplied pressurized air delivered to the solid oxide fuel cell 102 can be heated by a fuel cell air preheater 128. The fuel cell air preheater 128 can receive the heat of the exhaust of the solid oxide fuel cell 102 as will be described in more detail below.

  Inside the solid oxide fuel cell 102, the reformed fuel and the supplied pressurized air can react electrochemically to generate electricity by methods known in the art. For example, the solid oxide fuel cell 102 can include a porous air electrode, an airtight electrolyte, and a fuel electrode. The supplied pressurized air is introduced into an cathode or anode, which can be made of strontium-doped lanthanum manganite, for example. The electrolyte can be made of yttria-stabilized zirconia and covers the entire effective length of the cathode, excluding the thin strip. The fine strip of the cathode can be covered by a magnesium-doped lanthanum chromate hermetic layer, which forms the cell interconnect. The reformed fuel is introduced into a fuel electrode, also known as the cathode, which can be made of nickel-zirconia cermet and covers the electrolyte excluding the interconnect region. Examples of suitable solid oxide fuel cells are disclosed in JP-A-57-130181, JP-A-61-91880, JP-A-61-225778, and JP-A-63-110560. Each of which is incorporated herein by reference in its entirety. Examples of suitable solid oxide fuel cells that can be purchased include tubular, flat plate, or other similar solid oxide fuel cells that can be used.

  Thus, the reformed fuel can reach the cathode, where it can react with oxygen ions from the electrolyte, thereby releasing electrons to the external circuit. On the opposite side of the fuel cell, air can be supplied to the anode where it can supply oxygen ions to the electrolyte by receiving electrons from an external circuit. The electrolyte can conduct these ions between the electrodes and maintain the overall charge balance. The flow of electrons in the external circuit can supply active power. The solid oxide fuel cells 102 can be arranged in an array so that each is electrically connected to an adjacent fuel cell. The obtained direct current is supplied to the second inverter 138, where the direct current is converted into alternating current and can be supplied to the power grid 134.

  The solid oxide fuel cell 102 typically has a steady state operating temperature range of about 650 to 1000 ° C. (1200 to 1832 ° F.). In order to reach the steady state operating temperature, the solid oxide fuel cell 102 is configured to provide the reformed fuel flow from the fuel processor and the heated pressurized air of the fuel cell air preheater 128 and / or the recuperator 124 during start-up operation. Heat can be received from the flow and the electrochemical exothermic reaction performed in the solid oxide fuel cell 102.

The product of the electrochemical reaction on the anode side of the solid oxide fuel cell 102 includes carbon dioxide (CO ₂ ), water (H ₂ O), and unreacted gas fuel. Since the reforming process in the fuel processor 110 generally does not reform all of the supplied fuel, generally unreacted gas fuel remains in the reaction product of the anode. Furthermore, the solid oxide fuel cell 102 generally does not react with all of the fuel supplied to the anode side. Accordingly, the feed anode reaction product 140 can be fed to the SOFC combustor 126. Note that in another embodiment, a portion of the unreacted gas fuel can be further reformed by the water product therein to produce more power. The product from the cathode side contains excess air because the solid oxide fuel cell 102 generally does not react with all of the air supplied to the cathode side. Cathode reaction product 142 may also be fed to SOFC combustor 126. Feed anode reaction product 140 and feed cathode reaction product 142 are mixed in SOFC combustor 126 where high temperature excess air is used to burn unreacted gas fuel and thus the exhaust of solid oxide fuel cell 102. The temperature can be increased. In another embodiment, the SOFC combustor 126 can be fabricated inside the solid oxide fuel cell 102.

  The exhaust from the solid oxide fuel cell 102 (after leaving the SOFC combustor 126) can then be supplied through a fuel cell air preheater 128 to exchange heat with the supplied pressurized air from the compressor 106. . This heat exchange can be performed by methods and systems known in the art. Thus, the pressurized air supplied to the solid oxide fuel cell 102 can be heated by the exhaust of the solid oxide fuel cell 102 via the SOFC combustor 126. The exhaust of the solid oxide fuel cell 102 then exits the fuel cell air preheater 128 as described above, flows through the SOFC check valve 131 and reaches the mixing point 130, where the startup combustor 112 Can be mixed with exhaust. The mixed exhaust of the starter combustor 112 and the SOFC combustor 126 is then used to heat the fuel processor 110 to its required temperature and then directed to the turbine 104 where the exhaust expands to produce turbine output. Can be generated. It should be noted that in another embodiment, the exhaust of the solid oxide fuel cell 102 and the start-up combustor 112 are not mixed and can be supplied independently to the fuel processor 110 and / or the turbine 104.

  The start-up process includes start-up valve 116 and flow control valve 118 such that more of the pressurized fuel is directed toward solid oxide fuel cell 102 (via fuel processor 110) and out of start-up combustor 112. Can be continued at a predetermined speed such that the setting can be controlled. When the supplied pressurized fuel is oriented in this manner, the setting of the pressurized air valve 114 will increase the pressurized air demand at the solid oxide fuel cell 102 and decrease the pressurized air demand at the start-up combustor 112. It can be controlled to meet. Thus, as the startup process continues, more of the supplied pressurized air can be directed toward the solid oxide fuel cell 102. When a predetermined steady state condition is reached in the solid oxide fuel cell-gas turbine system 100, the settings of the system valves (the flow control valve 118, the start valve 116 and the pressurized air valve 114) will maintain this requirement. Can be controlled.

  In certain embodiments, the required steady state operating conditions are such that the exhaust of the solid oxide fuel cell 102 / SOFC combustor 126 supplies the heat required by the fuel processor 110 to continue the required fuel reforming. It can be achieved when it is enough to do. Accordingly, the rate at which the pressurized air stream is transferred from the startup combustor 112 to the solid oxide fuel cell 102 is solid electrolyte type until all of the pressurized air is directed to the solid oxide fuel cell 102. The predetermined incremental rate can be such that the exhaust of the fuel cell 102 is sufficient to supply all of the necessary heat to the fuel processor 110. Similarly, the rate at which the pressurized fuel stream is transferred from the startup combustor 112 to the solid oxide fuel cell 102 is also solid electrolyte type until all of the pressurized fuel is directed to the fuel processor 110. The predetermined incremental rate can be such that the exhaust of the fuel cell 102 is sufficient to supply all of the necessary heat to the fuel processor 110. In another embodiment, the steady state operating conditions are such that all of the pressurized air is directed to the solid oxide fuel cell 102 or all of the pressurized fuel is directed to the fuel processor 110. This can be achieved when the exhaust of the solid oxide fuel cell 102 is sufficient to heat the fuel processor 110. In this case, the start valve 116 is set to the closed position, so that combustion in the start combustor 112 and exhaust flow from the start combustor 112 are stopped. The flow control valve 118 can be set to an open position so that all of the supplied pressurized fuel can be directed to the fuel processor 110, and thus the solid oxide fuel cell 102. The pressurized air valve 114 can be set so that all of the supplied pressurized air is directed to the solid oxide fuel cell 102. As described above, the exhaust of the solid oxide fuel cell 102 / SOFC combustor 126 can supply all of the necessary heat to the fuel processor 110 and can expand within the turbine 104 to produce the required turbine output. The necessary thermal energy gas stream can be supplied.

  In other embodiments, the system valves (flow control valve 118, start valve 116 and pressurized air valve 114) and start combustor 112 output system capacity to achieve system transient operation in a more efficient manner. It can be controlled to increase in accordance with a rapid increase in demand. For example, the solid oxide fuel cell-gas turbine system 100 may be required to increase power generation from steady state operating conditions. As described above, steady state operating conditions mean that the start-up combustor 112 has ceased operation, and this is what is intended for this example. Thus, the supply pressurized fuel can be increased to meet new requirements. Supply pressurized air can also be increased by diverting turbine output from the generator 108 to the compressor 106. The start valve 116 is closed during steady state operation, but can be opened to receive a progressive portion of the pressurized fuel flow. The pressurized air valve 114 can also be controlled to direct the appropriate pressurized air flow to the startup combustor 112. The start-up combustor 112 can supply additional heat to the fuel processor 110 by combusting its supplied pressurized fuel and thus increasing the mixed flow to the fuel processor 110. The additional heat allows for increased fuel reforming capacity within the fuel processor 110, which allows for an increase in additional energy gas that will then expand within the turbine 104. The resulting additional output from the turbine 104 can be used to provide an extra air flow to the solid oxide fuel cell 102, which extra air flow increases and increases the pressurized fuel flow. When combined with an increase in quality fuel, it can be used to generate more electricity within the solid oxide fuel cell 102. Alternatively, the resulting additional power output of the turbine 104 can be used to increase power generation at the generator 108.

  Thus, the demand for increased power increases the supply of pressurized air and reformed fuel to the solid oxide fuel cell 102 using the startup combustor 112, thereby increasing the output of the solid oxide fuel cell 102. Can be satisfied. In this case, once the increase in the output level in the solid oxide fuel cell 102 is achieved, the startup combustor 112 can be stopped again, and the increased displacement from the solid oxide fuel cell 102 causes the new output level to reach the new output level. It may be sufficient to supply the amount of pressurized air and reformed fuel necessary to hold. In another embodiment, the demand for increased power can be met by using the startup combustor 112 to increase the thermal energy gas supplied to the turbine 104, thereby increasing the turbine power. The increased turbine power can be directed to the generator 108 to increase power generation. In this case, the peak system power generation capacity can be increased by combining the startup combustor 112.

  Accordingly, the foregoing description is to be considered as illustrative only of the principles of the invention. The features and aspects of the present invention have been described and illustrated as examples and are therefore not intended to be construed as necessary or essential elements of the invention. Reference numerals in the claims are not intended to narrow the technical scope of the present invention, but are for easy understanding.

1 is a schematic view of a solid oxide fuel cell-gas turbine combined system according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Fuel cell-gas turbine combined system 102 Solid oxide fuel cell 104 Turbine 106 Compressor 108 Generator 110 Fuel processing device 112 Start-up combustor 114 Pressurized air valve 116 Start-up valve 118 Flow control valve 122 Fuel preheater / steam generator 124 Recuperator 126 SOFC combustor 128 Fuel cell air preheater 129 Fuel feed 131 SOFC check valve 132, 138 Inverter 134 Power network

Claims (10)

A fuel cell-gas turbine combined system (100) comprising a fuel cell, an air compressor (106), and a fuel processor (110),
A startup combustor (112) for generating exhaust;
First control means for directing a pressurized air flow from the air compressor (106) to the startup combustor (112) and a fuel cell;
Second control means for directing a pressurized fuel stream to the startup combustor (112) and the fuel processor (110);
The first control means and the second control means are configured to cause the startup combustor before a pressurized fuel stream is delivered to the fuel processor (110) and a pressurized air stream is delivered to the fuel cell. Controlling the supply of pressurized air flow and pressurized fuel flow to the startup combustor (112) so that the fuel processor (110) is heated to a predetermined temperature by the exhaust of (112);
Fuel cell-gas turbine combined system (100). The fuel cell-gas turbine combined system (100) of claim 1, wherein the fuel cell comprises a solid oxide fuel cell (102). The first control means initially directs all of the pressurized air flow to the startup combustor (112);
The second control means first directs all of the pressurized fuel stream to the startup combustor (112);
When the fuel processor (110) reaches the predetermined temperature, the first control means until all of the pressurized air flow is delivered to the solid oxide fuel cell (102). The incremental portion of the pressurized air flow is directed to the solid oxide fuel cell (102) and the second control means delivers all of the pressurized fuel flow to the fuel processor (110). Orienting the incremental portion of the pressurized fuel stream to the fuel processor (110) until
The fuel cell-gas turbine combined system (100) according to claim 2. The combined fuel cell-gas turbine system (100) of claim 3, wherein the predetermined temperature comprises a required operating temperature of the fuel processor (110). The second control means includes a start valve (116) and a flow control valve (118),
The start valve (116) includes a two-way valve that controls delivery of a pressurized fuel stream to the start combustor (112);
The flow control valve (118) includes a two-way valve that controls the delivery of pressurized fuel flow to the fuel processor (110).
The fuel cell-gas turbine combined system (100) according to claim 3. The solid oxide fuel cell (102) generates exhaust, and the exhaust of the solid oxide fuel cell (102) supplies heat to the fuel processor (110);
The incremental portion of the pressurized air stream that is directed to the solid oxide fuel cell (102) is not until the time when all of the pressurized air stream is directed to the solid oxide fuel cell (102). A solid oxide fuel cell (102) exhaust is increased at a first predetermined rate that allows sufficient exhaust to supply all of the heat used in the fuel processor (110). ,
The fuel cell-gas turbine combined system (100) according to claim 2. The solid electrolyte fuel until the incremental portion of the pressurized fuel stream directed to the fuel processor (110) becomes oriented until all of the pressurized fuel stream is directed to the fuel processor (110). The exhaust of the battery (102) is increased at a second predetermined rate that allows sufficient exhaust to supply all of the heat used in the fuel processor (110). The combined fuel cell-gas turbine system (100). A SOFC combustor (126);
The SOFC combustor (126) is supplied with unreacted fuel and excess air from the solid oxide fuel cell (102);
The SOFC combustor (126) burns the unreacted fuel with the excess air to increase the heat of the exhaust of the solid oxide fuel cell (102);
The fuel cell-gas turbine combined system (100) according to claim 7. When the fuel processor (110) reaches the predetermined temperature, the exhaust of the solid oxide fuel cell (102) is sufficient to supply all of the heat used by the fuel processor (110) Until the first control means directs the incremental portion of the pressurized air flow to the solid oxide fuel cell (102), and the second control means determines the incremental portion of the pressurized fuel flow. The combined fuel cell-gas turbine system (100) of claim 2, oriented to the fuel processor (110). When the exhaust of the solid oxide fuel cell (102) reaches a point where it is sufficient to supply all of the heat used in the fuel processor (110), the first control means is The whole pressurized air stream is directed to the solid oxide fuel cell (102) and the second control means directs all of the pressurized fuel stream to the fuel processor (110). Fuel cell-gas turbine combined system (100).

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