JP2007059212A - Fuel cell power generating system and heat exchanger built-in type catalyst combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger built-in type catalyst combustion device excellent in durability, with little heat radiation and high efficiency, not exhausting combustible gas even at starting or in case that heat value is less and the temperature of the catalyst is low. <P>SOLUTION: A combustion catalyst 32 serving as a burner and a cooling tube 33 serving as a combustion gas heat exchanger are integrated by housing them in one container 31. A flame extinguishing plate 34 for preventing back fire toward upstream side is arranged at upstream side of the combustion catalyst 32. A supply gas temperature sensor 35a is arranged at upstream side of the flame extinguishing plate 34, a combustion catalyst layer temperature sensor 35b is arranged to the combustion catalyst 32, and a combustion catalyst layer outlet temperature sensor 35c is arranged at downstream side of the combustion catalyst layer. Outside of the container 31 is covered by a heat insulation material to restrain heat radiation toward outside. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell power generation system, and more particularly to a fuel cell power generation system in which a catalyst combustor and a combustion gas heat exchanger are integrated, and a heat exchanger built-in type catalyst combustor used in the system.

  The fuel cell power generation system uses hydrogen as a fuel and oxygen as an oxidant to react electrochemically to directly extract electricity, which can extract electric energy with high efficiency, and at the same time is quiet and harmful. It is a system that has excellent environmental characteristics that it does not emit exhaust gas. Recently, development of small PEFC (solid polymer fuel cell) has been activated, and the popularization of household fuel cell power generation systems has become imminent.

  Such a relatively small fuel cell power generation system for households or small businesses is used as a so-called cogeneration apparatus that supplies electric power and exhaust heat accompanying power generation.

  Such small fuel cell power generation systems are currently being developed mainly for fuel cell power generation systems that generate power using hydrocarbon fuels such as city gas, LP gas, and kerosene due to restrictions on the fuel supply base. Yes. However, in the future, the development of a hydrogen supply infrastructure is planned, and it is considered that a hydrogen circulation society will arrive. Fuel cell power generation systems are expected to become an important component of the hydrogen circulation society. Yes. That is, it is considered that a pure hydrogen fuel cell cogeneration power generation device will supply energy for homes or small businesses.

  FIG. 6 shows a general configuration of such a pure hydrogen fuel cell cogeneration system (hereinafter referred to as a fuel cell power generation system) used for each household or small business. That is, the conventional pure hydrogen fuel cell power generation system is configured such that hydrogen or a hydrogen-rich fuel is supplied to the fuel cell package 1 from a pipeline, a storage facility, or a centrally installed fuel processor. . The fuel supplied to the fuel cell package 1 is always supplied to the fuel electrode 2a of the fuel cell main body 2 at a constant pressure by the secondary pressure control valve 26, and a part of the fuel is consumed for the power generation reaction in the fuel cell main body 2. The Further, the flow rate set by the fuel electrode exhaust flow rate adjustment valve 27 is discharged from the fuel electrode 2 a and supplied to the combustor 21.

  On the other hand, the air electrode 2b of the fuel cell main body 2 is configured to be supplied with air from which impurities and dust have been removed by an air filter by an air blower 7. This air flow rate can be adjusted by variable speed control of the air blower 7 or a flow rate adjustment valve, and the flow rate is determined as a function of the opening command of the fuel electrode exhaust flow rate adjustment valve 27 and the power generation amount of the fuel cell body 2. The That is, an air flow rate proportional to the total amount of fuel input to the fuel cell package 1 is supplied.

  Further, the exhaust gas from the fuel electrode 2 a whose flow rate is adjusted by the fuel electrode exhaust flow rate adjustment valve 27 and the exhaust gas from the air electrode 2 b are premixed before being introduced into the combustor 21 and then supplied to the combustor 21. Is done. In the combustor 21, the exhaust from the fuel electrode 2 a is combusted to become a high-temperature combustion gas, which passes through the combustion gas heat exchanger 22 and the condenser 9 disposed on the downstream side of the combustor 21, and is discharged at a low temperature. It is configured to be discharged to the outside of the fuel cell package 1.

  In addition, the heat utilization of the fuel cell power generation system as described above is performed by the exhaust heat recovery circulation system 12, and here, a heat supply system using water to a hot water storage tank, which has many application examples, will be described. The supply form of heat to the user is not limited to the hot water storage tank, and the medium flowing through the exhaust heat recovery circulation system 12 is not limited to water.

  That is, when low-temperature water is supplied from the hot water storage tank 13 to the fuel cell package 1, this low-temperature water is first supplied to the condenser 9, recovering latent heat of condensation from the combustion gas containing a large amount of water vapor, and fuel cell power generation Collect the water required for The water exiting the condenser 9 is heated from 60 ° C. to 80 ° C. by the battery cooling water heat exchanger 10 and further heated by the combustion gas heat exchanger 22 to store hot water as high-temperature water at 80 ° C. or higher. It is supplied to the tank 13.

  Further, the flow rate of the exhaust heat recovery circulation system 12 is controlled so as to maintain the exhaust heat supply temperature at a set temperature. That is, when the heat utilization load increases and a command to extract a large amount of heat output is issued, the amount of combustion in the combustor 21 increases and the amount of circulating water in the exhaust heat recovery circulation system 12 increases. Yes.

  Further, the exhaust heat recovery circulation system 12 is provided with a bypass pipe 28 that bypasses the battery cooling water heat exchanger 10 and a bypass flow rate adjustment valve 29 that switches the flow path to the bypass pipe 28 and adjusts its flow rate. ing. The bypass flow rate adjustment valve 29 bypasses the battery cooling water heat exchanger 10 so as to maintain a battery cooling water temperature sensor (not shown) installed in the battery cooling water circulation system 11 in a predetermined temperature range, The flow rate flowing through the bypass pipe 28 is adjusted.

  Thus, in the conventional pure hydrogen type fuel cell power generation system, the combustor 21 for treating unreacted hydrogen contained in the exhaust gas from the fuel electrode 2a of the fuel cell main body 2 is provided. The method of recovering heat from the combustion exhaust gas as hot water is used.

  In this case, the combustion amount of the combustor 21 is determined by the fuel utilization rate in the fuel electrode 2a of the fuel cell main body 2. In such a fuel cell power generation system, by making the fuel utilization rate variable, the heat output and It has been proposed to control the ratio of the power generation output. According to such a thermoelectric ratio variable fuel cell power generation system, electric power and hot water can be supplied most efficiently to each household having various energy consumption patterns.

In addition, as a combustor used in the fuel cell power generation system as described above, one using catalytic combustion has been proposed (Patent Document 1, Patent Document 2). However, these are used in fuel cell power generation systems with a focus on power generation, and use catalytic combustion to discharge a small amount of combustible components in the anode exhaust outside the system in a safe manner. And the function of actively collecting the heat obtained here was not provided.
JP 2002-231294 A JP 2004-207025 A

  As described above, the catalytic combustor in the fuel cell power generation system of variable thermoelectric ratio type using pure hydrogen or a gas rich in hydrogen as a raw fuel has the following problems to be solved. No means for solving this problem has been found yet.

  First, as a first problem, in a conventional thermoelectric ratio variable fuel cell power generation system, the turndown of the fuel electrode exhaust gas flow rate supplied to the catalytic combustor is large, and the combustor is large relative to the heat amount at the minimum flow rate. Therefore, the heat radiation becomes relatively large and heat recovery is difficult. That is, when the required power generation amount for the fuel cell power generation system is low and the ratio of the heat demand of the thermoelectric ratio is small, the heat recovery efficiency becomes extremely low.

  As a second problem, in the conventional catalytic combustor as described above, when the required power generation amount for the fuel cell power generation system is small and the required heat amount is large, that is, the ratio of heat demand of the thermoelectric ratio is large, The amount of hydrogen supplied to the catalyst layer is the largest, and the combustion temperature is as high as 450 ° C. or higher. On the other hand, when the heat demand of the thermoelectric ratio in the fuel cell power generation system is low and the amount of hydrogen supplied to the catalyst layer is small, or when the fuel cell power generation system is started, the exhaust from the fuel electrode is burned at a catalyst layer temperature of 100 ° C or less It is necessary to prevent the combustible gas from being discharged from the combustor outlet.

  However, a combustion catalyst generally has a low reaction characteristic at a low temperature of 100 ° C. or lower when used for a long time at a high temperature of 450 ° C. or higher. Therefore, in order to prevent the combustible gas from being discharged to the atmosphere, it is necessary to heat the catalyst layer or the supply gas at the start-up, and when the hydrogen supply amount to the combustor is small, the supply air amount is reduced. It was necessary to increase the combustion temperature with less.

  In addition, as a third problem, when the amount of hydrogen supplied to the combustion catalyst layer is small, mixing with air is deteriorated and combustibility is lowered. Therefore, exhaust from the fuel electrode supplied to the combustor and air from the air electrode are reduced. The exhaust gas is mixed with the exhaust gas in advance (so-called premixing) and then supplied to the combustor. In that case, there has been a concern of backfire in which combustion proceeds to the upstream side of the combustion catalyst layer.

  Furthermore, as a fourth problem, the exhaust gas from the fuel electrode and the exhaust gas from the air electrode supplied to the catalytic combustor contain a lot of water vapor, and the water condensed during the start-up or the like is used as the combustion catalyst. There was also a problem that the catalyst performance deteriorated due to adhesion.

The present invention has been made in order to solve the above-described problems of the prior art. The first object of the present invention is high efficiency with less heat dissipation, less heat generation, less heat generation, and a low catalyst layer temperature. Another object of the present invention is to provide a fuel cell power generation system including a catalytic combustor for fuel electrode exhaust gas that does not discharge flammable gas and has excellent durability.
In addition, the second object of the present invention is a highly efficient built-in heat exchanger that does not emit flammable gas even when starting up or when the catalyst layer is low temperature with low heat dissipation and high efficiency. It is to provide a catalytic combustor.

  In order to achieve the above object, a catalyst combustor with a built-in heat exchanger according to claim 1 discharges a fuel gas containing a combustible component discharged from a fuel electrode of a fuel cell from an air electrode of the fuel cell. A combustion section provided with a combustion catalyst layer that is mixed and burned with exhausted air, and a heat exchange section that is located downstream of the combustion section and recovers the heat held by the combustion gas that has passed through the combustion section as hot water However, it is characterized by being integrated.

  According to the invention described in claim 1 having the above-described configuration, the combustion section provided with the combustion catalyst layer and the heat exchange section that recovers the heat held by the combustion gas that has passed through the combustion section as hot water are integrated. Therefore, it is possible to reduce the size of the apparatus. Moreover, since heat radiation can be minimized, the heat recovery efficiency can be improved.

According to a second aspect of the present invention, in the catalyst combustor with a built-in heat exchanger according to the first aspect, the combustion catalyst layer includes any one or more of palladium, platinum, and rhodium as an active component. It is characterized by being.
The invention described in claim 2 specifically defines the active components used in the combustion catalyst layer.

  The invention according to claim 3 is the heat exchanger built-in type catalyst combustor according to claim 1 or claim 2, wherein the inlet portion, the intermediate portion, and the outlet portion of the combustion catalyst layer along the flow direction of the combustion gas. Each is provided with a temperature measuring means, and a means for evaluating the deterioration degree of the combustion catalyst by monitoring the temperature of the combustion catalyst layer during the power generation operation is provided.

  According to the invention described in claim 3 having the above-described configuration, the temperature is measured by the temperature measuring means disposed inside the combustion catalyst layer, thereby monitoring the temperature of the combustion catalyst layer during the fuel cell power generation operation. Since the degree of deterioration of the catalyst can be determined, it is possible to accurately grasp the replacement timing of the combustion catalyst.

According to a fourth aspect of the present invention, in the heat exchanger built-in type catalytic combustor according to any one of the first to third aspects, the combustion catalyst layer is not in contact with the upstream side of the combustion catalyst layer. A flame extinguishing plate is provided.
According to the invention described in claim 4 having the above-described configuration, it is possible to prevent the combustion at the combustion catalyst from back-fired upstream.

  According to a fifth aspect of the present invention, in the catalyst combustor with a built-in heat exchanger according to any one of the first to fourth aspects, the condensate contained in the fuel gas is retained at 100 ° C. or lower, and is combustible. An inert layer that does not undergo a combustion reaction even in a state where gas and oxygen coexist is provided on the upstream side of the combustion catalyst layer.

  According to the invention described in claim 5 having the above-described configuration, a large amount of water vapor contained in the fuel gas supplied to the combustion section is held by the inert material when the fuel cell power generation system is started. Therefore, only the gas from which moisture has been sufficiently removed comes into contact with the combustion catalyst and undergoes a combustion reaction. As a result, it is possible to prevent sintering of the active metal on the surface of the combustion catalyst and prevent a decrease in the catalyst function.

A sixth aspect of the present invention is the catalyst combustor with a built-in heat exchanger according to the fifth aspect, wherein the inert material is any one of alumina, zirconia, and silica.
The invention described in claim 6 specifically defines the substance used for the inactive substance.

  The invention according to claim 7 is the heat exchanger built-in type catalyst combustor according to any one of claims 1 to 6, wherein the combustion gas of the heat exchange unit located downstream of the combustion catalyst layer An exhaust gas purification catalyst layer for combusting and removing combustible substances that could not be combusted by the combustion catalyst layer is provided in the flow passage.

  According to the invention described in claim 7 having the above-described configuration, the exhaust gas purification catalyst layer disposed in the heat exchange section is maintained at 100 ° C. or lower even during the power generation operation of the fuel cell power generation system. , Low temperature activity of 100 ° C. or less can be maintained for a long time. As a result, even if the combustion catalyst is started at a low temperature, the combustible gas that cannot be burned in the combustion catalyst layer can be removed at the portion filled with the exhaust gas purification catalyst, so that the startup time can be shortened. it can.

The invention according to claim 8 is the catalyst combustor with a built-in heat exchanger according to claim 7, wherein the exhaust gas purification catalyst contains any one or more of palladium, platinum or rhodium as an active component thereof. It is characterized by being.
The invention according to claim 8 specifically defines the active components used in the exhaust gas purification catalyst.

The invention according to claim 9 is the catalyst combustor with a built-in heat exchanger according to claim 7, wherein the combustion catalyst and the exhaust gas purification catalyst are made of the same substance.
According to the invention described in claim 9 having the above-described configuration, since only one type of catalyst is required to fill the inside of the container, the manufacturing process of the device is simplified. In addition, since the combustion catalyst filled in the heat exchange section is protected from being exposed to a high temperature, the activity at a low temperature can be maintained, so the combustion catalyst layer filled in the upstream side remains in a low temperature state. Even so, since the fuel gas can be introduced, the startup time of the fuel cell power generation system can be shortened.

  According to a tenth aspect of the present invention, in the fuel cell power generation system that generates electricity using hydrogen or a gas rich in hydrogen as a fuel and air as an oxidant, the heat exchange according to any one of the first to ninth aspects. A fuel cell power generation system comprising a built-in type catalytic combustor.

  According to invention of Claim 10 which has the above structures, it has the heat exchanger built-in type catalyst combustor in any one of Claim 1 thru | or 9 which has an effect | action and effect as mentioned above. Thus, it is possible to provide a fuel cell power generation system equipped with an excellent heat supply system that has low heat dissipation and high efficiency, and that does not emit flammable gas even at startup or when the catalyst layer is low and the catalyst layer is at a low temperature. .

According to the present invention as described above, catalytic combustion for fuel electrode exhaust gas with excellent durability that does not emit flammable gas even when the catalyst layer is cold at start-up or heat generation is low, with low heat dissipation and high efficiency. It is possible to provide a fuel cell power generation system equipped with a vessel.
In addition, according to the present invention, the heat exchanger built-in type catalyst combustor is excellent in durability, with low heat dissipation and high efficiency, and does not discharge flammable gas even when the catalyst layer is low at start-up or heat generation. Can be provided.

  Embodiments of a fuel cell power generation system according to the present invention will be described below with reference to the drawings. The fuel cell power generation system according to the present invention is characterized in that the combustor 21 and the combustion gas heat exchanger 22 that are separately provided in the conventional type shown in FIG.

(1) Configuration of the First Embodiment (1-1) As shown in FIG. 1, in the fuel cell power generation system of this embodiment, the combustion section 30a having the function of the combustor 21 in the conventional type shown in FIG. And a combustion gas heat exchanging portion 30b having the function of the combustion gas heat exchanger 22 are integrated into a heat exchanger built-in type catalyst combustor 30 between the fuel cell main body 2 and the condenser 9. It is installed.

  As shown in FIG. 2, this heat exchanger built-in type catalytic combustor 30 includes a combustion catalyst 32 that functions as a combustor and a cooling pipe 33 that functions as a combustion gas heat exchanger in a single container 31. Are integrated and configured. That is, the combustion catalyst 32 is disposed above the center of the container 31, and a flame extinguishing plate 34 is installed in the upper space (upstream of the combustion catalyst 32). The flame extinguishing plate 34 is provided so that combustion in the combustion catalyst 32 does not backfire upstream. The combustion catalyst 30 and the flame extinguishing plate 34 constitute a combustion unit 30a.

  Further, a cooling pipe 33 is disposed inside the container 31 below the center thereof, and the cooling medium introduced from the refrigerant inlet 40 provided in the lower part of the container 31 flows through the cooling pipe 33. The refrigerant outlet 41 is configured to be discharged to the outside of the container 31. The cooling pipe 33 constitutes a combustion gas heat exchange unit 30b.

  Further, a supply gas temperature sensor 35a is disposed on the upstream side of the flame extinguishing plate 34, two combustion catalyst layer temperature sensors 35b are disposed on the combustion catalyst 32, and further, on the downstream side of the combustion catalyst layer. Is provided with a combustion catalyst layer outlet temperature sensor 35c. In FIG. 2, the number of combustion catalyst layer temperature sensors 35b is two, but more may be provided.

  Further, an exhaust gas supply port 42 from the fuel cell main body 2 is provided in the upper part of the container 31, and the exhaust gas of the fuel electrode 2 a and the exhaust gas of the air electrode 2 b mixed in advance on the upstream side of the supply port 42 are supplied. The gas is supplied into the heat exchanger built-in type catalytic combustor 30 through the port 42, and the gas comes into contact with the combustion catalyst 32 to cause a combustion reaction.

  On the other hand, an exhaust port 43 for combustion exhaust gas discharged from the heat exchanger built-in type catalyst combustor 30 is provided at the lower portion of the container 31, and the combustion gas exiting the combustion catalyst 32 layer is water that flows in the cooling pipe 33. After being cooled by exchanging heat with the refrigerant, etc., the refrigerant is discharged from the outlet 43 and sent to the condenser 9 shown in FIG. And after passing through the condenser 9, it is configured to be exhausted to the outside of the fuel cell package 1 as low-temperature exhaust. Moreover, the outer side of the container 31 is covered with a heat insulating material 36, and is configured so that heat radiation to the outside can be suppressed.

  In addition, the heat exchanger built-in type catalyst combustor 30 provided with the combustion part 30a and the combustion gas heat exchange part 30b as mentioned above can also be comprised as shown in FIG. In other words, the diameter of the central portion of the container 31 that houses the combustion unit 30a and the combustion gas heat exchange unit 30b may be reduced so as to be divided vertically. For example, if the upper container 31a and the lower container 31b composed of the upper unit containing the combustion unit 30a and the lower unit containing the combustion gas heat exchange unit 30b are configured to be detachable by a screw type or a fitting type, Even when the combustion catalyst 32 deteriorates and needs to be replaced, only the upper unit containing the combustion catalyst 32 can be easily replaced. Moreover, the cooling pipe 33 may be provided with a heat radiation fin to improve the cooling efficiency.

(1-2) Action / Effect According to the fuel cell power generation system of the present embodiment having the above-described configuration, the following action / effect can be obtained.

  The combustion reaction of the heat exchanger built-in type catalyst combustor 30 in the present embodiment includes a combustion catalyst layer temperature sensor 35b installed inside the combustion catalyst 32 layer and a combustion catalyst installed in the outlet gas flow path of the combustion catalyst 32 layer. This can be detected by the temperature rise of the layer outlet temperature sensor 35c.

  That is, the reaction activity of the combustion catalyst 32 decreases with time when the fuel cell package 1 is operated for a long time. In the initial stage, there are many combustion reactions at the inlet, the inlet temperature becomes higher than the intermediate temperature, and the temperature at the inlet decreases as the activity decreases. By monitoring this temporal temperature change with the combustion catalyst layer temperature sensor 35b disposed inside the combustion catalyst layer, it is possible to accurately grasp the replacement timing of the combustion catalyst 32.

  Further, in the present embodiment, the flame extinguishing plate 34 is installed upstream of the combustion catalyst 32 in order to prevent the combustion in the combustion catalyst 32 from flashing back to the upstream. Even in this case, an abnormally high temperature can be detected by the supply gas temperature sensor 35a installed in the gas flow path upstream of the flame extinguishing plate 34. As a result, when an abnormally high temperature is detected by the supply gas temperature sensor 35a, the fuel supply can be stopped immediately and the apparatus can be safely stopped.

  Thus, according to the present embodiment, the combustion part 30a filled with the combustion catalyst 32 and the combustion gas heat exchange part 30b are integrated into one container 31, and the periphery of the container 31 is covered with the heat insulating material 36. Thus, it is possible to provide a highly efficient heat exchanger built-in type catalyst combustor which is small and suppresses heat radiation. In addition, by incorporating this heat exchanger built-in type catalytic combustor into the fuel cell power generation system, it is possible to provide a fuel cell power generation system including a highly efficient heat supply system that is small and suppresses heat radiation.

  In addition, according to the present embodiment, in the combined heat and power fuel cell power generation system, even when high temperature water can be taken out and the thermoelectric output ratio is variable, the temperature of the fuel cell main body 2 is not cooled too much, and the predetermined temperature is reached. It becomes possible to stably maintain the range.

(2) Second Embodiment (2-1) Configuration The present embodiment is a modification of the first embodiment described above, in which the configuration of the heat exchanger built-in catalyst combustor is changed.

  The heat exchanger built-in type catalytic combustor 50 in the present embodiment is configured as shown in FIG. That is, the combustion catalyst 32 is disposed inside the container 31 above the center thereof, and the upstream side of the combustion catalyst 32 is filled with an inert body 37. As this inactive body 37, the condensed water contained in the fuel gas is maintained at 100 ° C. or lower, and does not cause a combustion reaction even in a state where the combustible gas and oxygen coexist. For example, porous alumina, silica, zirconia Etc. are used.

  A flame extinguishing plate 34 is installed in the upper space of the inert body 37 (upstream of the inert body 37). The flame extinguishing plate 34 is provided so that combustion in the combustion catalyst 32 does not backfire upstream. The combustion catalyst 32, the inert body 37, and the flame extinguishing plate 34 constitute a combustion section 50a. Although not shown in FIG. 4, it goes without saying that the temperature sensors 35a to 35c described in the first embodiment may be provided in the combustion unit 50a.

  Further, a cooling pipe 33 is disposed inside the container 31 below the center thereof, and the cooling medium introduced from the refrigerant inlet 40 provided in the lower part of the container 31 flows through the cooling pipe 33. The refrigerant outlet 41 is configured to be discharged to the outside of the container 31. The cooling pipe 33 constitutes a combustion gas heat exchange unit 30b.

  Further, in the present embodiment, the combustion gas flow path of the combustion gas heat exchange unit 50b is filled with the exhaust gas purification catalyst 38, and is configured to burn and remove the combustible gas that has not been reacted in the combustion catalyst 32 layer. ing. That is, in the present embodiment, the exhaust gas purification catalyst 38 is filled around the cooling pipe 33 disposed in the combustion gas heat exchange unit 50b. For the combustion catalyst 32 and the exhaust gas purification catalyst 38, a similar catalyst using a noble metal such as palladium, platinum or rhodium as an active component is used.

  Further, an exhaust gas supply port 42 from the fuel cell main body 2 is provided in the upper portion of the container 31, and the exhaust gas of the fuel electrode 2 a and the exhaust gas of the air electrode 2 b mixed in advance on the upstream side of the supply port 42 are used for heat exchange. The gas is supplied to the built-in type catalyst combustor 50, and the gas comes into contact with the combustion catalyst 32 to cause a combustion reaction. On the other hand, an exhaust port 43 for combustion exhaust gas discharged from the heat exchanger built-in type catalyst combustor 50 is provided at the lower portion of the container 31. Moreover, the outer side of the container 31 is covered with a heat insulating material 36, and is configured so that heat radiation to the outside can be suppressed.

(2-2) Operation / Effect The fuel cell power generation system of the present embodiment having the above-described configuration operates as follows.
That is, a gas in which the exhaust gas from the fuel electrode 2a and the exhaust gas from the air electrode 2b are premixed is supplied from the upper part of the container 31 and comes into contact with the combustion catalyst 32 to cause a combustion reaction. Below the temperature, the condensed water contained in the fuel gas is retained, and the inert substance 37 that does not undergo a combustion reaction even in the state where the combustible gas and oxygen coexist is filled, so the following effects are obtained.

  That is, the exhaust gas from the fuel electrode 2a and the exhaust gas from the air electrode 2b supplied to the combustion unit 50a contain a large amount of water vapor. When the fuel cell power generation system is started, the condensed water is converted into a combustion catalyst. It is held by an inert material 37 filled upstream of 32 layers. As a result, only the gas from which moisture has been sufficiently removed comes into contact with the combustion catalyst 32 and undergoes a combustion reaction. Further, since the inert body 37 is also heated with the temperature rise of the combustion catalyst 32 layer, the water held by the inert body 37 is evaporated and removed by the temperature rise of the inert body 37.

  On the other hand, when there is no such inactive substance 37, the condensed water directly hits the combustion catalyst 32, and the repetition of the evaporation causes the active metal sintering on the catalyst surface and the like. However, according to the present embodiment, such a problem does not occur.

  In addition, since the exhaust gas purification catalyst 38 is filled in the combustion gas flow path of the combustion gas heat exchange unit 50b, the combustible gas that has not reacted in the combustion catalyst 32 layer is burned and removed by the exhaust gas purification catalyst 38. . As described above, the combustion catalyst 32 and the exhaust gas purification catalyst 38 are similar catalysts using a noble metal such as palladium, platinum or rhodium as an active component, but the combustion catalyst 32 layer is used during the power generation operation of the fuel cell power generation system. By being exposed to a high temperature of 100 to 600 ° C., the low temperature activity of 100 ° C. or less tends to decrease after a long operation.

  On the other hand, the exhaust gas purification catalyst 38 layer is provided with the cooling pipe 33 inside the layer, and therefore, particularly on the downstream side, it is maintained at 100 ° C. or lower even during the power generation operation of the fuel cell power generation system. Therefore, the exhaust gas purification catalyst 38 can maintain a low temperature activity of 100 ° C. or lower for a long time. In particular, when the exhaust gas purification catalyst 38 is not provided at the start-up of the fuel cell power generation system, it is necessary to raise the temperature of the combustion catalyst 32 layer to a temperature of 100 ° C. or higher at which the function can be exhibited. It was supposed to require.

  However, since the exhaust gas purification catalyst 38 used in the present embodiment can maintain the catalytic activity at a low temperature of 100 ° C. or less, the exhaust gas purification catalyst 38 is disposed in the combustion gas heat exchange section 50b, whereby the combustion catalyst 32 is provided. Even if the engine is started at a low temperature, the combustible gas that could not be combusted in the combustion catalyst 32 layer can be removed at the portion filled with the exhaust gas purification catalyst 38, so that the startup time can be shortened.

  Here, since the temperature of the combustion catalyst 32 layer rises due to its own heat generation, the leakage of the unburned portion downstream is gradually reduced. Thus, shortening the start-up time leads not only to its convenience, but also to improving the efficiency of its economy when operating the fuel cell power generation system, such as suppressing heater power consumption for raising the temperature of the catalyst layer. .

(3) Third Embodiment (3-1) Configuration This embodiment is a modification of the first embodiment and the second embodiment described above, and is a modification of the configuration of the heat exchanger built-in type catalyst combustor. is there.

  The heat exchanger built-in type catalyst combustor 60 in the present embodiment is configured as shown in FIG. That is, similarly to the second embodiment, the condensed water contained in the supply gas is retained upstream of the combustion catalyst 32 layer at 100 ° C. or lower, and the combustion reaction does not occur even in the state where the combustible gas and oxygen coexist. An active body 37 is provided.

  Further, in the present embodiment, the combustion catalyst 32 is filled up to the position of the combustion gas heat exchange section 60b. That is, in the present embodiment, the combustion catalyst 32 is filled around the cooling pipe 33. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

(3-2) Operation / Effect The fuel cell power generation system of the present embodiment having the above-described configuration operates as follows.
That is, as described in the second embodiment, since the functions of the combustion catalyst 32 and the exhaust gas purification catalyst 38 are the same, in this embodiment, the combustion catalyst 32 is filled up to the position of the combustion gas heat exchange section 60b. However, the cooling pipe 33 is configured to protect the downstream combustion catalyst 32 from being exposed to a high temperature. As a result, the activity at a low temperature can be maintained in the downstream combustion catalyst 32 portion.

  Thus, in the present embodiment, the presence of the downstream combustion catalyst 32 that maintains the activity at a relatively low temperature, the combustion catalyst 32 layer filled on the upstream side remains in a low temperature state. However, since the fuel gas can be introduced, the startup time of the fuel cell power generation system can be shortened. Further, in this embodiment, only one type of catalyst may be filled in the container, and there is no need to separate the combustion catalyst layer and the exhaust gas purification catalyst layer as in the second embodiment. The manufacturing process of the vessel can be simplified.

(4) Other Embodiments The present invention is not limited to the above-described embodiments, and a temperature sensor monitoring control device disposed in the combustion sections 30a, 50a, 60a is provided. If it is configured to control the flow rate of the fuel cell exhaust gas supplied to the heat exchanger built-in type catalyst combustor and the replacement timing of the combustion catalyst 32 based on the detected value, a more accurate fuel cell power generation system can be obtained. Obtainable.

1 is a schematic diagram showing the overall configuration of a fuel cell power generation system according to the present invention. Sectional drawing which shows the structure of 1st Embodiment of the heat exchanger built-in type catalyst combustor used for the fuel cell power generation system which concerns on this invention. Sectional drawing which shows the structure of the modification of the heat exchanger built-in type catalyst combustor shown in FIG. Sectional drawing which shows the structure of 2nd Embodiment of the heat exchanger built-in type catalyst combustor used for the fuel cell power generation system which concerns on this invention. Sectional drawing which shows the structure of 3rd Embodiment of the catalyst combustor with a built-in heat exchanger used for the fuel cell power generation system which concerns on this invention. Schematic diagram showing the overall configuration of a conventional fuel cell power generation system

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell package 2 ... Fuel cell main body 2a ... Fuel electrode 2b ... Air electrode 7 ... Air blower 8 ... Air filter 9 ... Condenser 10 ... Battery cooling water heat exchanger 11 ... Battery cooling water circulation system 12 ... Waste heat recovery circulation System 13 ... Hot water storage tank 21 ... Combustor 22 ... Combustion gas heat exchanger 26 ... Secondary pressure control valve 27 ... Fuel electrode exhaust flow rate adjustment valve 28 ... Bypass piping 29 ... Bypass flow rate adjustment valve 30, 50, 60 ... Heat exchanger Built-in catalyst combustors 30a, 50a, 60a ... combustion units 30b, 50b, 60b ... combustion gas heat exchange unit 31 ... vessel 32 ... combustion catalyst 33 ... cooling pipe 34 ... extinguishing plate 35 ... temperature sensor 35a ... supply gas temperature sensor 35b ... Combustion catalyst layer temperature sensor 35c ... Combustion catalyst layer outlet temperature sensor 36 ... Heat insulator 37 ... Inert body 38 ... Exhaust gas purification catalyst

Claims (10)

  A combustion section having a combustion catalyst layer for mixing and burning fuel gas containing a combustible component discharged from the fuel electrode of the fuel cell with exhaust air discharged from the air electrode of the fuel cell; A heat exchanger built-in type catalyst combustor, which is integrated with a heat exchanging unit that is located on the downstream side and collects heat held by the combustion gas that has passed through the combustion unit as hot water.   The catalyst combustor with a built-in heat exchanger according to claim 1, wherein the combustion catalyst layer contains one or more of palladium, platinum, and rhodium as an active component.   Deterioration of the combustion catalyst by providing temperature measuring means at each of the inlet, middle and outlet along the flow direction of the combustion gas in the combustion catalyst layer, and monitoring the temperature of the combustion catalyst layer during power generation operation The heat exchanger built-in type catalytic combustor according to claim 1 or 2, further comprising means for evaluating the degree.   The heat exchanger built-in type catalyst combustor according to any one of claims 1 to 3, wherein a flame extinguishing plate is provided at a position not in contact with the combustion catalyst layer upstream of the combustion catalyst layer. .   An inert layer that retains condensed water contained in the fuel gas at a temperature of 100 ° C. or less and does not undergo a combustion reaction even in the state where the combustible gas and oxygen coexist is provided on the upstream side of the combustion catalyst layer. The catalyst combustor with a built-in heat exchanger according to any one of claims 1 to 4.   6. The heat exchanger built-in type catalytic combustor according to claim 5, wherein the inert material is any one of alumina, zirconia, and silica.   An exhaust gas purification catalyst layer for combusting and removing combustible substances that could not be combusted in the combustion catalyst layer is provided in a combustion gas flow passage of the heat exchange unit located downstream of the combustion catalyst layer. The heat exchanger built-in type catalytic combustor according to any one of claims 1 to 6.   8. The heat exchanger built-in type catalyst combustor according to claim 7, wherein the exhaust gas purifying catalyst contains at least one of palladium, platinum, and rhodium as an active component thereof.   8. The heat exchanger built-in type catalyst combustor according to claim 7, wherein the combustion catalyst and the exhaust gas purification catalyst are made of the same substance. In a fuel cell power generation system that generates electricity using hydrogen or hydrogen-rich gas as fuel and air as oxidant,
A fuel cell power generation system comprising the heat exchanger built-in type catalyst combustor according to any one of claims 1 to 9.

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