JP2005195254A - Catalytic combuster for fuel battery power generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalytic combuster, starting combustion of natural gas at low temperatures and having excellent durability in burning hydrogen. <P>SOLUTION: A Pt part supporting catalyst 45 and Pd supporting catalyst 33 are serially provided in order from the upstream side of the gas circulating direction in a container 38 having a gas inlet 39 and a gas outlet 40. The Pt part supporting catalyst 45 is formed by a metal honeycomb 34 with alternations of Pt support channel 35a supporting Pt44 and catalyst non-supporting channel 35d not supporting catalyst. The Pd supporting catalyst 33 is formed by supporting Pd37 on each channel 35 of the metal honeycomb 34. The Pt part supporting catalyst 45 burns premixture 41 in the Pt supporting channel 35a supporting Pt44 having low-temperature activity and circulates the same intact in the catalyst non-supporting channel 35b. As a whole, partial combustion is performed to restrain a temperature rise of the Pt part supporting catalyst. In the Pd supporting catalyst 33, premixture 41 after partial combustion, which causes a temperature rise due to partial combustion, is subjected to complete combustion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a fuel cell power generator for generating a reforming heat source of a reformer by being provided on the downstream side of an anode of a molten carbonate fuel cell and catalytically combusting combustible components in a gas discharged from an anode outlet. The present invention relates to a catalytic combustor for an apparatus.

  Among the molten carbonate fuel cells, for example, a power generator using a natural gas reformed molten carbonate fuel cell (hereinafter referred to as MCFC power generator) is configured as shown in FIG. . That is, the inlet of the cathode 2 in the molten carbonate fuel cell 1 having a structure in which a cell in which an electrolyte plate (not shown) is sandwiched between both electrodes of the cathode 2 and the anode 3 is stacked in a multilayer manner via a separator. On the side, an air supply line 8 having a blower 9 is connected in the middle. For example, air 10 compressed by a compressor 7 rotated by a turbine 5 of a supercharger 4 via a turbine shaft 6 Supply is made through a supply line 8. On the other hand, the natural gas 11 which is the raw fuel of the reformed gas 11a used as the power generation fuel in the fuel cell 1 is desulfurized by a desulfurizer (not shown) and then passes through the natural gas preheater 13 from the natural gas supply line 12. The reformed gas 11 a supplied to the reforming chamber 14 a of the reformer 14 and reformed in the reforming chamber 14 a passes through the fuel gas supply line 15, passes through the natural gas preheater 13, and the fuel cell 1. The fuel cell 1 is supplied to the anode 3, thereby generating power in the fuel cell 1.

  Note that unreacted hydrogen remains in the anode outlet gas 16 discharged from the outlet side of the anode 3. However, unreacted hydrogen in the anode outlet gas 16 is usually low in concentration, and is further diluted with water or carbon dioxide gas generated on the anode 3 side in accordance with the principle of the molten carbonate fuel cell 1. It is difficult to burn unreacted hydrogen contained in the anode outlet gas 16 with a normal burner.

For this purpose, a catalytic combustor 18 is installed on the outlet side of the anode 3, and the anode outlet gas 16 discharged from the outlet side of the anode 3 is introduced into the catalytic combustor 18 through the anode outlet gas line 17. The cathode outlet gas 19 discharged from the outlet side of the cathode 2 is introduced into the catalytic combustor 18 through the cathode outlet gas line 20 and is contained in the anode outlet gas 16 in the catalytic combustor 18. The unreacted hydrogen is burnt (oxidized) with oxygen remaining in the cathode outlet gas 19, and the combustion gas 21 generated at this time passes through the combustion gas line 22 to the heating chamber of the reformer 14. 14b so that the heat generated during combustion of the unreacted hydrogen can be used as a reforming heat source in the reformer 14. That. A part of the combustion gas 21 after being supplied to the reforming heat source in the heating chamber 14b of the reformer 14 joins in the middle of the air supply line 8 to recycle CO ₂ , but the rest is an exhaust gas line to be described later. It is made to discharge | emit after joining 28.

A part of the cathode outlet gas 19 discharged from the cathode 2 passes through a cathode recycling line 23 branched from the cathode outlet gas line 20, is pressurized by a high-temperature recycling blower on the way, and is recycled to the cathode 2 inlet side. It is like that. Further, a part of the cathode outlet gas 19 is introduced into the combustor 25 through a branch line 24 branched from the cathode outlet gas line 20. The combustor 25 is connected to a fuel supply line 26 for supplying the natural gas 11 as fuel and an air supply line (not shown) for supplying air as necessary. The natural gas 11 is burned with the cathode outlet gas 19 and air, and the combustion exhaust gas 27 generated by this combustion is guided to the turbine 5 of the supercharger 4 to drive the turbine 5. .
The combustion exhaust gas 27 after being used to drive the turbine 5 is discharged from the exhaust gas line 28 after heat recovery through a steam generator 29 with a steam superheater. Further, the steam 30 generated by the steam generator 29 and superheated by the steam superheater is guided to the natural gas supply line 12 through the steam line 31 (see, for example, Patent Document 1). Note that it has been conventionally considered to attach a generator as indicated by reference numeral 32 in FIG. 2 to the turbine shaft 6 of the supercharger 4.

  Meanwhile, the catalyst combustor 18 of the MCFC power generator converts unreacted hydrogen contained in the anode outlet gas 16 into cathode output gas during normal operation of the MCFC power generator, that is, during power generation by the fuel cell 1. 19 has a function of generating a reforming heat source of the reformer 14 by burning at about 800 ° C. using oxygen contained in the reformer 14. However, when the MCFC power generator is activated and the reforming chamber 14a of the reformer 14 is not heated, natural gas that is the raw fuel in the reforming chamber 14 is shown in FIG. The gas 11 is not reformed. For this reason, the natural gas 11 is supplied as it is from the reforming chamber 14a of the reformer 14 to the anode 3 of the fuel cell 1 instead of the reformed gas 11a. Therefore, the gas discharged from the outlet side of the anode 3 and sent to the catalytic combustor 18 through the anode outlet gas line 17 is not the gas containing unburned hydrogen but the natural gas 11. Therefore, the catalytic combustor 18 does not generate power as the start-up fuel, the natural gas 11 that is the raw fuel guided through the anode 3 from the reforming chamber 14a of the reformer 14. A function of generating a reforming heat source of the reformer 14 by passing through the cathode 2 of the fuel cell 1 as it is, followed by catalytic combustion using the air 10 supplied via the cathode outlet gas line 20. Is also required.

  Thus, when the natural gas 11 is directly catalytically combusted in the catalytic combustor 18, methane, which is the main component of the natural gas 11, is ignited as compared with the case where hydrogen ignites at a relatively low temperature of about 100 ° C. In order to achieve this, a high temperature of about 350 to 500 ° C. is required.

  Therefore, when starting the MCFC power generation apparatus, first, the natural gas 11 as the fuel is supplied to the combustor 25 and burned, and the combustion exhaust gas 27 generated at this time is led to the steam generator 29 and the high-temperature steam 30 is supplied. The hot water vapor 30 is supplied to the natural gas supply line 12 through the water vapor line 31, and the natural gas preheater 13, together with the natural gas 11 fed through the natural gas supply line 12, is supplied. After sequentially passing through the reforming chamber 14 a of the reformer 14 and the anode 3 of the fuel cell 1, the gas is led to the catalytic combustor 18, whereby the natural gas 11 that is the start-up fuel supplied to the catalytic combustor 18 is The natural gas 11 is preheated to a temperature at which the natural gas 11 can be ignited on the catalyst by the heat of the water vapor 30, and the combustion of the natural gas 11 in the catalytic combustor 18 is performed. By starting, so that causes the activation of the reformer 14 to generate a modified heat source.

  By the way, as a catalyst used in a general catalytic combustor, a catalyst carrying a platinum group catalyst component (active component) is used. Among such catalysts, a catalyst carrying platinum (Pt) as a catalyst component is highly active and excellent in low temperature ignition characteristics of natural gas, and can start combustion of natural gas from a relatively low temperature. However, since the Pt-supported catalyst has low heat resistance and deteriorates when used for a long time at a temperature exceeding about 700 ° C., hydrogen combustion is performed at about 800 ° C. during power generation by the fuel cell 1. It cannot be employed as a catalyst for a catalytic combustor 18 for a fuel cell.

  Therefore, as the catalyst of the catalytic combustor 18, a catalyst carrying palladium (Pd), which is a catalyst component having excellent high temperature resistance, is usually used.

  The catalytic combustor 18 using such a Pd-supported catalyst has the following configuration as schematically shown in FIGS. That is, as a catalyst supporting structure, for example, a Pd-supporting catalyst 33 in which Pd 37 as a catalyst component is supported on the inner surface of each channel 35 of the metal honeycomb 34 via a high surface area oxide (wash coat) 36. It is formed. Furthermore, a gas inlet 39 is provided at one end so that the downstream end of the cathode outlet gas line 16 and the anode outlet gas line 20 can be connected together, and at the other end upstream of the combustion gas line 22. The Pd-supported catalyst 33 is placed in a required position in a container 38 having a gas outlet 40 which can be connected to the side end and the inside serving as a gas flow path in the direction of each channel 35 of the metal honeycomb 34. Are arranged so as to be in a direction along the gas flow direction in the container 38 and attached to the inner surface of the container 38 so as to partition the upstream and downstream directions. Thus, during normal operation of the MCFC power generator, the mixed gas of the anode outlet gas 16 and the cathode outlet gas 19 and when the MCFC power generator is started, the mixed gas of the natural gas 11 and the air 10 are both combustible components. When the premixed gas 41 made by mixing oxygen flows into the container 38 from the gas inlet 39 and is sent to the gas outlet 40 through the channels 35 of the metal honeycomb 34, the channels 35 are supplied. Combustible components such as hydrogen and methane contained in the premixed gas 41 can be burned (oxidized) with oxygen on the Pd 37 supported on the inner surface of the gas.

  Furthermore, the catalytic combustor 18 is configured to discharge the anode outlet gas 16 having a higher hydrogen concentration than the anode 3 while the Pd-supported catalyst 33 is at a high temperature during normal operation of the MCFC power generator. As a result, when the premixed gas 41 having a high hydrogen concentration derived from the anode outlet gas 16 flows into the container 38 from the gas inlet 39, a flashback occurs due to contact with the Pd-supported catalyst 33 that is at a high temperature. There is a concern about the possibility of the occurrence. For this reason, the metal honeycomb 42 arranged so that the direction of the channel 43 is aligned with the direction of gas flow in the container 38 at a position upstream of the Pd-supporting catalyst 33 in the container 38 is attached so as to partition the upstream and downstream directions. Even if a backfire occurs from the Pd-supported catalyst 33, the catalyst is not supported and the combustible components are not combusted. The backfire is prevented from going back to the upstream side beyond the metal honeycomb 42 so that the temperature rise can be suppressed. In general catalytic combustors, as a measure for preventing the occurrence of flashback, a wire mesh flame arrester is often provided upstream of the catalyst for burning the combustible component. In the above case, it is difficult to reliably prevent backfire with the wire mesh frame arrester. Therefore, the catalyst combustor 18 for the fuel cell power generator is provided with a metal honeycomb 42 instead of a frame arrester. ing. In FIG. 3B, reference numeral 34a denotes partition walls between the channels 35 in the metal honeycomb 34 on which Pd 37 is supported.

  In addition, as a type of catalytic combustor comprising a plurality of catalysts arranged in series in a vessel, for example, in a catalytic combustor for a gas turbine, gas fuel is used for the purpose of achieving both the activity and durability of the catalyst. The premixed gas mixture of air and air is led to a low-temperature catalyst having high low-temperature activity but inferior heat resistance and burned, and further to the partial combustion gas whose temperature has been raised by combustion in the low-temperature catalyst on the downstream side, further gas fuel Has been proposed in which a premixed gas composed of the gas fuel and the partial combustion gas is introduced into a high-temperature catalyst having low low-temperature activity but excellent heat resistance and burned ( For example, see Patent Document 2).

  In addition, the catalyst includes a plurality of catalysts arranged in series and a plurality of heat exchangers arranged on the downstream side of each catalyst to exchange heat between the combustion gas and the medium to be heated. Conventionally, a catalytic combustor is also proposed in which the heat exchange performed by the heat exchanger immediately after that is repeated for each set of catalyst and heat exchanger (see, for example, Patent Document 3).

Japanese Patent No. 3151860 Japanese Patent Laid-Open No. 9-243079 JP 7-113508 A

  However, the conventional catalyst combustor 18 for the MCFC power generator shown in FIGS. 3 (a) and 3 (b) uses a Pd-supported catalyst 33 supporting Pd37 excellent in high temperature resistance as a catalyst component. In addition, when used as a catalytic combustor 18 that performs hydrogen combustion at about 800 ° C. during power generation by the fuel cell 1, the durability is stable even for long-term use. However, since Pd37 as the catalyst component has low low-temperature activity, in order to start combustion of the premixed gas 41 using natural gas as fuel, the premixed gas 41 supplied to the Pd-supported catalyst 33 is changed to 400 It is necessary to preheat until the temperature is higher than ℃. For this reason, when the catalytic combustor 18 using the Pd-supported catalyst 33 is employed as the catalytic combustor 18 for the MCFC power generator, it takes a long start-up time. Further, when the MCFC power generator is started, a large amount of energy is used to raise the temperature of the premixed gas 41 using the natural gas supplied to the Pd-supported catalyst 33 of the catalytic combustor 18 to the combustion start temperature of the natural gas. In reality, it is necessary to make the combustor 25 shown in FIG.

  The catalyst combustor shown in Patent Document 2 is configured such that a low-temperature catalyst and a high-temperature catalyst are arranged in series. However, a premixed gas mixture of gas fuel and air is used in the low-temperature catalyst. In order to ensure the durability of the low-temperature catalyst having low heat resistance during combustion, the premixed gas supplied to the low-temperature catalyst is strictly controlled by precisely controlling the mixing ratio of gas fuel and air. It is necessary to control the adiabatic flame temperature of the mixture. Further, a venturi for supplying and mixing the gaseous fuel to the partial combustion gas heated by the low temperature catalyst and heated at a position downstream of the low temperature catalyst and upstream of the high temperature catalyst. Since it needs to be provided, there is a problem that the apparatus becomes complicated.

  The catalyst combustor shown in Patent Document 3 has a problem that the apparatus becomes complicated because it is necessary to provide a heat exchanger immediately after each of a plurality of stages of catalysts arranged in series. Furthermore, in order to cause partial combustion of the premixed gas in each stage of the catalyst, it is necessary to make the effective volume of the catalyst of each stage sufficiently small or set the gas flow rate sufficiently high. As shown in the catalyst combustor 18 for the MCFC power generator, a catalyst in which the composition of the premixed gas supplied at the start-up and normal operation of the MCFC power generator and the concentration of the combustible component change significantly. It is difficult to adopt as a combustor.

  Furthermore, the catalyst combustors described in Patent Document 2 and Patent Document 3 above all constitute a catalyst in which a catalyst component is partially supported, like the catalyst combustor for a fuel cell power generator of the present invention described later. The idea of being part of a member is not shown or suggested at all.

  Accordingly, the present invention is intended to provide a catalytic combustor for a fuel cell power generator that can shorten the startup time of the MCFC power generator and can exhibit excellent durability.

  In order to solve the above problems, the present invention provides a catalytic combustor for a fuel cell power generator that generates a reforming heat source of a reformer by catalytic combustion of a combustible component in a gas guided from an anode of the fuel cell. A partially-supported low-temperature catalyst partially supporting a catalyst component with excellent ignition characteristics and a fully-supported high-temperature catalyst fully supporting a catalyst component with excellent heat resistance are arranged in series in order from the upstream side in the gas flow direction. Further, the partially supported low-temperature catalyst has a configuration in which a channel supporting a catalyst component having excellent low-temperature ignition characteristics and a channel not supporting the catalyst component are provided in a required ratio.

  Further, the partially supported low temperature catalyst in the above configuration is configured such that a channel in which a catalyst having excellent low temperature ignition characteristics is partially supported on a metal honeycomb and a channel in which no catalyst is supported are alternately provided.

  Furthermore, platinum is used as the catalyst having excellent low-temperature ignition characteristics in the above, and palladium is used as the catalyst component having excellent heat resistance.

According to the catalytic combustor for the fuel cell power generator of the present invention, the following excellent effects are exhibited.
(1) In a catalytic combustor for a fuel cell power generator that generates a reforming heat source of a reformer by catalytic combustion of a combustible component in a gas led from the anode of the fuel cell, the catalyst component having excellent low temperature ignition characteristics is partially supported. The partially supported low-temperature catalyst and the fully supported high-temperature catalyst in which the catalyst component having excellent heat resistance is fully supported are arranged in series in order from the upstream side in the gas flow direction. The catalyst is configured to have a channel that supports a catalyst component with excellent low-temperature ignition characteristics and a channel that does not support the catalyst component in the required ratio, so a partially supported low-temperature catalyst is started up with an MCFC power generator. It becomes possible to start partial combustion of a premixed gas containing natural gas used as fuel as a fuel from a relatively low temperature.
(2) In addition, the partially supported low-temperature catalyst can partially burn a premixed gas containing natural gas as fuel without requiring special control, thereby increasing the temperature of the partially supported low-temperature catalyst. Therefore, even when the catalyst component with excellent low-temperature ignition characteristics is not very heat-resistant, it can prevent deterioration and improve durability. .
(3) Furthermore, since the premixed gas containing the natural gas as a fuel can be partially burned by the partially supported low temperature catalyst and heated up, it can be led to the downstream full surface supported high temperature catalyst. Even when the catalyst component having excellent heat resistance in the full surface supported high temperature catalyst has a relatively low low temperature activity, it is possible to quickly start combustion of the premixed gas containing the natural gas as a fuel.
(4) Therefore, it becomes possible to shorten the start-up time in the MCFC power generator. Furthermore, it is possible to reduce the size of the combustor that generates heat for preheating the premixed gas containing natural gas that is the startup fuel of the MCFC power generation apparatus.
(5) The partially supported low-temperature catalyst has a configuration in which a channel in which a catalyst having excellent low-temperature ignition characteristics is partially supported on a metal honeycomb and a channel in which a catalyst is not supported are alternately provided. It is possible to easily produce a partially supported low-temperature catalyst that partially burns about half of the combustible components therein without requiring special control.
(6) By using platinum as a catalyst having excellent low-temperature ignition characteristics and using palladium as a catalyst component having excellent heat resistance, a premixed gas containing natural gas as a fuel has a relatively low temperature. Therefore, a catalyst combustor for a fuel cell power generator can be easily configured that has both the characteristics that allow combustion to be started from the above and the durability that can be used for a long time in the combustion of a premixed gas containing hydrogen as a fuel.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1 (a) and 1 (b) show an embodiment of a catalytic combustor for a fuel cell power generator according to the present invention. Pt44 as a low-temperature catalyst component which is excellent in low-temperature activity and not very good in heat resistance is partially shown. A partially supported Pt partial supported catalyst 45 as a partially supported low temperature catalyst to be supported is manufactured, and Pd37 as a high temperature catalyst component which is not so high in low temperature activity but excellent in heat resistance is supported on the entire surface. As a catalyst, a Pd-supported catalyst 33 similar to that shown in FIGS. 3A and 3B is manufactured, and the gas inlet 39 and the gas outlet 40 are provided at both ends in the same manner as shown in FIGS. In the container 38 provided, the Pt partial supported catalyst 45 and the Pd supported catalyst 33 are arranged in series in order from the upstream side, and the Pt partial supported catalyst 45 and the Pd supported catalyst 33 are respectively disposed on the inner surface of the container 38. Upstream / downstream direction Mount as partitions to form a fuel cell power plant for a catalytic combustor 18a of the present invention.

  In the above, “partial support” means that when a catalyst is formed by supporting a catalyst component for low temperature on a required structure for catalyst support having a number of channels through which gas can flow, the catalyst component for low temperature is used. When the premixed gas containing the combustible component and oxygen is passed through the channel supporting the low-temperature catalyst component, the channel supporting the catalyst component and the channel not supporting the catalyst component are present together in the required ratio. The heat generated when the combustible component is burned is exchanged with the premixed gas passing through the channel not supporting the catalyst component, so that the temperature of the entire catalyst including the low temperature catalyst component is reduced by the low temperature catalyst component. It means that the temperature can be lowered to a required temperature range that does not deteriorate even during long-term use and averaged.

  More specifically, the Pt partial supported catalyst 45 includes a metal honeycomb 34 having a large number of channels like the metal honeycomb 34 of the Pd supported catalyst 33 as a structure for supporting the catalyst. When Pt 44 is supported as a catalyst component for use, a channel 35a (hereinafter referred to as a Pt support channel) 35a in which Pt 44 is supported on the inner surface through a high surface area oxide 36, and a channel (in which no catalyst component is supported on the inner surface ( (Hereinafter referred to as catalyst non-supporting channels) 35b are arranged alternately.

  In FIG. 1B, for convenience of illustration, the high surface area oxide layer 36 is shown thick, and the particle size of Pt 44 is shown large. For this reason, the cross-sectional areas of the flow paths in the Pt-supported channel 35a and the non-catalyst-supported channel 35b are greatly different from each other in the drawing. The particle size is extremely small, and the cross-sectional areas of the Pt supporting channel 35a and the catalyst non-supporting channel 35b are substantially equal. In addition, the dimensions of the channels 35a and 35b of the metal honeycomb 34 in FIG. 1 (a) and the particle sizes of Pt44 and Pd37 are also convenient sizes for illustration, and therefore do not reflect actual dimensions. Absent. In addition, the same components as those shown in FIGS. 3A and 3B are denoted by the same reference numerals.

  When the premixed gas 41 containing a combustible component and oxygen is supplied from the gas inlet 39 to the catalyst combustor 18a for the fuel cell power generator according to the present invention having the above-described configuration, the premixed gas 41 is firstly Pt partial supported catalyst 45. The Pt support channel 35a and the catalyst non-support channel 35b in FIG. In the Pt carrying channel 35a, due to the presence of Pt 44 carried on the inner surface of the channel, the combustible component in the premixed gas 41 passing through the Pt carrying channel 35a is burned, and the temperature is raised by the generated combustion heat. Be able to. On the other hand, in the non-catalyst channel 35b, no catalyst is present on the inner surface of the channel, so that the premixed gas 41 is allowed to pass through without being burned with combustible components. Therefore, on the downstream side of the Pt partial supported catalyst 45, the gas in which combustible components are burned on the Pt 44 when passing through the Pt supported channel 35a into the premixed gas 41 that has passed through the non-catalyst supported channel 35b as it is. Therefore, the premixed gas 41 in which about half of the combustible component is partially burned is discharged.

  Further, since the premixed gas 41 passing through the catalyst non-supporting channel 35b does not receive a temperature rise due to the combustion heat of the combustible component in the premixed gas 41, the temperature rises as the combustible component is burned. A temperature difference is generated from the premixed gas 41 in the Pt carrying channel 35a. For this reason, the combustion heat generated by the combustion of the premixed gas 41 in the Pt carrying channel 35a is exchanged with the premixed gas 41 passing through the non-catalyst channel 35b as it is. By the exchange, the temperature of the Pt partial supported catalyst 45 is averaged as a whole. Moreover, as described above, when viewed as a whole of the Pt partial supported catalyst 45, only about half of the combustible components in the premixed gas 41 are partially burned. Therefore, as the fuel of the premixed gas 41, the anode outlet gas 16 containing unreacted hydrogen discharged to the outlet side of the anode 3 during normal operation of the MCFC power generator as shown in FIG. Even when the temperature of the Pt partial supported catalyst 45 does not exceed 700 ° C., the temperature generated during complete combustion of the anode outlet gas 16 is about 800 ° C. However, the possibility that the low-temperature catalyst component Pt44 is deteriorated is prevented.

  On the other hand, when supplying the natural gas 11 led from the outlet side of the anode 3 when starting the MCFC power generator as shown in FIG. 2 as the fuel of the premixed gas 41, it passes through the Pt partial supported catalyst 45. Since the combustible component is partially combusted, the premixed gas 41 partially combusted with the combustible component is heated to a temperature equal to or higher than the ignition temperature of the natural gas 11 in the Pd-supported catalyst 33. It is sent to the Pd-supported catalyst 33 on the downstream side.

  In the Pd-supported catalyst 33, when the premixed gas 41 is supplied while the combustible component is partially combusted by passing through the Pt partial-supported catalyst 45 and the temperature of the premixed gas 41 is supplied, all the channels 35 Since the Pd37 is supported on the inner surface of the premixed gas 41 supplied with the combustible component partially burned, the combustible component is completely burned on the Pd37 on the inner surface of each channel. .

  As described above, the catalyst combustor 18a for a fuel cell power generator according to the present invention can partially burn the premixed gas 41 by the Pt partial supported catalyst 45 without performing any special control, and thereafter this portion. The pre-mixed gas 41 after partial combustion whose temperature has been raised by combustion can be completely burned by the Pd-supported catalyst 33.

  Therefore, if the catalyst combustor 18a for a fuel cell power generator of the present invention is employed as the catalyst combustor of the MCFC power generator shown in FIG. 2, it is guided through the anode outlet gas line 17 during normal operation of the MCFC power generator. Even when the anode outlet gas 16 is burned, the possibility that the Pt partial supported catalyst 45 in the catalytic combustor 18a exceeds 700 ° C. can be prevented, and therefore, the deterioration of the Pt partial supported catalyst 45 can be prevented. It can be made durable and stable even for long-term use.

  Further, as described above, since the temperature of the Pt partial supported catalyst 45 can be made lower than 700 ° C., the anode outlet gas 16 having a hydrogen concentration higher than that of the anode 3 during normal operation of the MCFC power generator. Even when the anode outlet gas 16 having a high hydrogen concentration is prevented from coming into contact with a high-temperature catalyst, the risk of backfire can be suppressed. Control can be made easy.

  Furthermore, when the natural gas 11 as the raw fuel is supplied through the anode outlet gas line 17 at the start-up of the MCFC power generator, the natural gas 11 is loaded with Pt44, which is a catalyst component having excellent low-temperature activity. It is possible to start partial combustion at a relatively low temperature with the Pt partial supported catalyst 45 thus made, and to raise the temperature of the natural gas 11 after partial combustion sent to the downstream Pd supported catalyst 33 by this partial combustion. For this reason, since the combustion of the natural gas 11 in the Pd-supported catalyst 33 can also be started quickly, natural gas which is a start-up fuel for supplying to the catalytic combustor 18a and starting combustion is provided. The preheating temperature of 11 can be lowered as compared with the prior art. For this reason, it is possible to reduce the size of the combustor 25 used for preheating the natural gas 11. For example, a combustor included in a micro gas turbine that recovers exhaust heat from the fuel cell 1 and generates electric power is sufficient. The temperature can be raised. In addition, since the reformer 14 can be started from a lower temperature than in the prior art, the startup time of the MCFC power generator can be shortened.

  Note that the present invention is not limited to the above-described embodiment, and the heat of combustion of the premixed gas 41 in the Pt-supported channel 35a is exchanged with the premixed gas 41 that passes through the non-catalyst-supported channel 35b. As long as the overall temperature of the Pt partial supported catalyst 45 can be lowered to a temperature range where the Pt 44 does not deteriorate even when used for a long time, the arrangement of the Pt supported channels 35a and the non-catalyst supported channels 35b may not be arranged alternately. Further, the pre-mixed gas 41 is used in the Pt partial supported catalyst 45 by setting the ratio of both of them to a ratio deviating from about 1: 1, such as an arrangement in which the periphery of the Pt supported channel 35a is surrounded by the non-catalyst supported channel 35b. The ratio of partial combustion may be changed. The cross-sectional shapes of the Pt supporting channel 35a and the catalyst non-supporting channel 35b may be set freely. In consideration of pressure loss, the Pt partial supported catalyst 45 adopts a metal honeycomb 34 as a structure for supporting a catalyst component, and supports Pt 44 on the inner surface of the channel of the metal honeycomb 34 to form a Pt supported channel 35a. However, it is preferable that the heat of combustion of the premixed gas 41 generated in the Pt-supported channel 35a is exchanged with the premixed gas 41 flowing in the non-catalyst-supported channel 35b, so that Pt44 in the Pt-supported channel 35a is exchanged. If the temperature of the catalyst including the catalyst is lowered to a temperature range where Pt44 does not deteriorate even after long-term use, the structure for supporting catalyst components having a large number of relatively large channels can be coated with Pt44 on the surface. A channel filled with supported pellets and a channel filled with pellets not supporting catalyst. By providing the panel, it may be caused to form and the Pt-carrying channels 35a and catalyst carrying channel 35b. The Pt partial supported catalyst 45 and the Pd supported catalyst 33 are shown as having substantially the same length in the gas flow direction. However, after the premixed gas 41 is partially burned at the required ratio by the Pt partial supported catalyst 45. If the Pd-supported catalyst 33 can be completely combusted, the lengths of the Pt partial-supported catalyst 45 and the Pd-supported catalyst 33 in the gas flow direction may be appropriately changed. As a low-temperature catalyst component that is excellent in low-temperature activity and not very good in heat resistance, a catalyst component other than Pt44 may be employed, and as a high-temperature catalyst component that is not so high in low-temperature activity but excellent in heat resistance Catalyst components other than Pd37 may be employed. If the Pt partial supported catalyst 45 and the Pd supported catalyst 33 can be provided in order from the upstream side in the gas flow direction between the gas inlet 39 and the gas outlet 40 of the container 38, the shape of the container 38 can be arbitrarily set. The shapes of the Pt partial supported catalyst 45 and the Pd supported catalyst 33 may be arbitrarily set corresponding to the shape of 38. Of course, various changes can be made without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a catalytic combustor for a fuel cell power generator according to the present invention, in which (a) is a schematic cut side view, and (b) is an enlarged view of part A of (a). It is a schematic diagram which shows an example of an MCFC power generator. 1A and 1B show a conventional catalytic combustor for a fuel cell power generator, in which FIG. 1A is a schematic cut side view, and FIG. 2B is an enlarged view of a portion B of FIG.

Explanation of symbols

18a Catalytic combustor 33 Pd supported catalyst (full surface supported high temperature catalyst)
35 Metal honeycomb 35a Pt supporting channel (channel supporting catalyst component with excellent low temperature ignition characteristics)
35b Non-catalyst channel (channel not carrying catalyst component)
37 Pd (catalyst component with excellent heat resistance)
44 Pt (catalyst component with excellent low-temperature ignition characteristics)
45 Pt partially supported catalyst (partially supported low temperature catalyst)

Claims (4)

  In a catalytic combustor for a fuel cell power generator that generates a reforming heat source of a reformer by catalytic combustion of a combustible component in a gas guided from an anode of a fuel cell, a portion that partially supports a catalyst component having excellent low temperature ignition characteristics A fuel cell power generator having a configuration in which a supported low-temperature catalyst and a full-supported high-temperature catalyst in which a catalyst component having excellent heat resistance is fully supported are arranged in series in order from the upstream side in the gas flow direction. Catalytic combustor.   The catalyst for a fuel cell power generator according to claim 1, wherein the partially supported low temperature catalyst comprises a channel supporting a catalyst component having excellent low temperature ignition characteristics and a channel not supporting the catalyst component in a required ratio. Combustor.   2. The catalyst combustion for a fuel cell power generator according to claim 1, wherein the partially supported low-temperature catalyst comprises a channel in which a catalyst excellent in low-temperature ignition characteristics is partially supported on a metal honeycomb and a channel in which no catalyst is supported. vessel.   4. The catalytic combustor for a fuel cell power generator according to claim 1, wherein platinum is used as a catalyst having excellent low temperature ignition characteristics, and palladium is used as a catalyst component having excellent heat resistance.

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