JP2005353347A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the starting time of a reformer by heating a catalyst to an activation temperature region in a short time without decreasing the durability of the catalyst inside a carbon monoxide shift reaction part. <P>SOLUTION: A fuel cell system is equipped with a warming up unit 86 heating a CO shift part 23 by burning reformed gas introduced from a CO selectively oxidizing part 24 and oxidant gas with a built-in combustion catalyst, and by conducting heat-exchange between the combustion gas and reformed gas supplied to the CO shift part 23, and first and second air valves 64, 97 adjustably distributing the oxidant gas to the warming up unit 86 and the CO selectively oxidizing part 24. A control device 30 controls the oxidant gas supply amount ratio to the warming up unit 86 and the CO selectively oxidizing part 24 by controlling the first and second air valves 64, 97 is set in consideration of an activation temperature region of a shift catalyst and a selectively oxidizing catalyst. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system including a reforming unit that generates a reformed gas containing hydrogen by reforming a supplied fuel with a reforming catalyst filled therein, and leads the fuel to a fuel cell. The present invention relates to a fuel cell system having early startability.

  The fuel cell system includes a reforming unit that generates and derives a reformed gas containing hydrogen by reforming the supplied fuel with a reforming catalyst filled therein, and the reforming unit derived from the reforming unit. A carbon monoxide shift reaction part derived by reducing the carbon monoxide concentration in the reformed gas with a shift catalyst filled inside, and the carbon monoxide in the reformed gas derived from the carbon monoxide shift reaction part There is known a device equipped with a carbon monoxide selective oxidation portion that is further reduced by oxidation with the supplied oxidant gas by a selective oxidation catalyst filled inside and supplied to the fuel cell.

  In such a fuel cell system, in order to obtain a reformed gas containing carbon monoxide at a predetermined concentration (about 10 ppm), the temperature of each catalyst is raised to the respective activation temperature range. The time required for all the catalysts to reach the active temperature range is the warm-up time, and it is required to shorten this time as much as possible to improve the early warm-up property (early start-up).

  As a solution to this problem, there is a fuel gas generator for a fuel cell described in Patent Document 1. In this apparatus, hydrogen is contained from an evaporator 22 that vaporizes liquid raw fuel to generate fuel vapor, and a raw fuel gas that is partially oxidized by adding reformed air to the fuel vapor generated by the evaporator 22. Autothermal reformer 11 that generates reformed gas, and CO removal that generates fuel gas from which carbon monoxide has been removed by adding CO removal air to the reformed gas generated by autothermal reformer 11 In the fuel gas generator 1 for a fuel cell comprising the heater 13, the supply amount of the reformed air when the fuel cell fuel gas generator is warmed up is changed to the reformed air during idle operation after the warm-up is completed. It controls so that it may increase rather than supply amount.

  Further, there is a reformer described in Patent Document 2. In this apparatus, air is introduced into the inlet of the carbon monoxide shift reaction section at the time of start-up, burned with reformed gas (hydrogen) generated by itself, and heated by this combustion gas.

Further, in the fuel cell system and the fuel cell cogeneration hot water system described in Patent Document 3, the fuel cell system is a fuel reformer (6) for generating H ₂ and CO from hydrocarbon-based raw fuel. A CO converter (7) for generating H ₂ and CO ₂ from the CO generated in the fuel reformer (6) by a water gas shift reaction, a fuel reformer (6), and a CO converter (7 The fuel cell (1) that generates electricity using the H ₂ produced in step ₂ ) as a fuel and a combustion reaction of the H ₂ produced in the fuel reformer (6) in the CO converter (7) for a predetermined time from the start-up. shall CO transformer (7) and a O ₂ supply means for supplying a O ₂ for. O ₂ supply means comprises an O ₂ supply amount control means for controlling the O ₂ supply amount (first on-off valve 11), the temperature of the Pt catalyst is detected by the temperature sensor, the CO transformer 7 accordingly The amount of air supply is controlled. That is, as the catalyst temperature rises, the degree of opening and closing of the first on-off valve 11 is adjusted to reduce the amount of air supplied to the CO converter 7 and suppress the combustion reaction of H ₂ , so that the catalyst temperature exceeds 500 ° C. Control is done so that nothing happens.

Further, there is a control device for a fuel cell system described in Patent Document 4. In this apparatus, a reforming catalyst (3) that generates a reformed gas containing hydrogen from raw fuel vapor using fuel and water as raw fuel, and a fuel cell stack that generates power using the reformed gas and air ( 1) and a combustion catalyst (9) for combusting exhaust gas discharged from the fuel cell stack, the flow rate of the reformed gas flowing into the combustion catalyst and the concentration of the reformed gas components are detected. Based on this detection result, the amount of air supplied to the combustion catalyst is controlled by the flow rate adjusting valve 12d and the compressor 2 so that the temperature of the combustion catalyst becomes an allowable temperature. This suppresses deterioration of the combustion catalyst due to abnormally high temperatures.
JP 2002-198081 A (page 1, FIGS. 1 to 3) Japanese Patent Application Laid-Open No. 11-43303 (pages 4, 5 and 1 to 3) Japanese Patent Laid-Open No. 2001-176533 (Page 1, FIGS. 1 to 3) Japanese Patent Laid-Open No. 2002-316801 (page 1, FIGS. 1 to 3)

  In the devices described in Patent Documents 1 to 3, although the catalyst in the carbon monoxide shift reaction section can be raised to the activation temperature range of the catalyst in a short time, the high-temperature (500 ° C. or higher) combustion gas is oxidized. Since the catalyst in the carbon shift reaction part is directly heated, a heat spot is likely to be generated, and there is a problem that the deterioration of the catalyst rapidly proceeds and the durability of the catalyst is remarkably lowered. Moreover, in the apparatus described in Patent Document 4, only the flow rate to the combustion catalyst is adjusted, and the flow rate is related to the flow rate to the other components (starting combustor 10 and premixer 11). Do not control.

  The present invention has been made to solve the above-described problems, and the catalyst is heated to the active temperature range in a short time without reducing the durability of the catalyst in the carbon monoxide shift reaction section. The purpose is to shorten the start-up time of the quality device, reduce the input energy required for start-up, and increase the average power generation efficiency during operation.

  In order to solve the above problems, the structural feature of the invention according to claim 1 is that a reformed gas containing hydrogen is generated by reforming the supplied fuel with a reforming catalyst filled therein. A reforming section to be derived, a carbon monoxide shift reaction section to be derived by reducing the concentration of carbon monoxide in the reformed gas derived from the reforming section with a shift catalyst filled therein, and the carbon monoxide The carbon monoxide selective oxidation unit that supplies the fuel cell with further reduction by oxidation with the oxidant gas supplied by the selective oxidation catalyst filled with carbon monoxide in the reformed gas derived from the shift reaction unit. In the fuel cell system equipped with the fuel cell system, the reformed gas and the oxidant gas derived from the carbon monoxide selective oxidation unit are introduced, burned by the built-in combustion catalyst, and supplied to the combustion gas and the carbon monoxide shift reaction unit. Heating means for heating the carbon monoxide shift reaction section by exchanging heat with the reformed gas, or directly heating the carbon monoxide shift reaction section by the heat of combustion, and the warming-up means and monoxide Provided in the oxidant gas supply means for supplying the oxidant gas to the carbon selective oxidation part and the oxidant gas supply means, the supply amount of the oxidant gas to the warm-up means and the carbon monoxide selective oxidation part can be adjusted. And the oxidant gas distribution means for distributing the oxidant gas to the warming means and the carbon monoxide selective oxidation unit at the time of start-up, and the ratio of the amount of oxidant gas supplied to the carbon monoxide selective oxidation unit at the start-up. And a control means having a predetermined ratio set in consideration of the active temperature range.

  Further, the structural feature of the invention according to claim 2 is that, in claim 1, the warm-up means is composed of a plurality of heat exchange parts, and the oxidant gas is distributed and supplied to each heat exchange part. That is.

  Further, the structural feature of the invention according to claim 3 is that, in claim 2, any one of the plurality of heat exchange parts of the warm-up means is at least the reformed gas inlet or the same of the carbon monoxide shift reaction part. That is, it is provided at any position between the reformed gas inlet and the reformed gas outlet.

  According to a fourth aspect of the present invention, the structural feature of the invention according to any one of the first to third aspects further includes a reforming water supply means for supplying the reforming water to the reforming section. The quality water supply means is to raise the temperature of the carbon monoxide shift reaction section by supplying a larger amount of reforming water than the supply amount during normal operation while the warm-up means is in operation.

  In the invention according to claim 1 configured as described above, the ratio of the amount of oxidant gas supplied to the warm-up unit and the carbon monoxide selective oxidation unit by controlling the oxidant gas distribution unit when the fuel cell system is started. However, the oxidant gas is supplied to the warm-up means and the carbon monoxide selective oxidation unit so that the predetermined ratio is set in consideration of the activation temperature range of the shift catalyst and the selective oxidation catalyst. Therefore, since the carbon monoxide shift reaction unit is quickly warmed up by the warming-up means and the carbon monoxide selective oxidation unit is also warmed up, the entire fuel cell system can be warmed up efficiently and quickly. Moreover, the input energy required for start-up is reduced, and the average power generation efficiency during operation is increased.

  In the invention according to claim 2 configured as described above, in the fuel cell system according to claim 1, the warm-up means includes a plurality of heat exchanging portions, and an oxidant gas is distributed to each heat exchanging portion. Since the carbon monoxide shift reaction unit is warmed up from a plurality of locations by being supplied, the warm-up time of the carbon monoxide shift reaction unit can be further shortened, and as a result, the warm-up time of the fuel cell system can be reduced. It can be shortened more.

  In the invention according to claim 3 configured as described above, in the fuel cell system according to claim 2, any one of the plurality of heat exchange parts of the warm-up means is at least a reformed gas of the carbon monoxide shift reaction part. The carbon monoxide shift reaction section can be efficiently warmed up by being provided at either the inlet or the intermediate position between the reformed gas inlet and the reformed gas outlet.

  In the invention according to Claim 4 configured as described above, in the fuel cell system according to any one of Claims 1 to 3, the reforming water supply means for supplying the reforming water to the reforming unit is further provided. The reforming water supply means is provided by heating the carbon monoxide shift reaction unit by supplying a larger amount of reforming water than the supply amount during normal operation while the warm-up means is in operation. The warm-up time of the carbon oxide shift reaction part can be further shortened, and as a result, the warm-up time of the fuel cell system can be further shortened.

  Hereinafter, an embodiment of a fuel cell system according to the present invention will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. As shown in FIG. 1, this fuel cell system includes a fuel cell 10 and a steam reforming reformer 20 that generates hydrogen gas necessary for the fuel cell 10. The fuel cell 10 includes a fuel electrode 11 and an air electrode 12, and generates power using the reformed gas supplied to the fuel electrode 11 and the air (cathode air) supplied to the air electrode 12.

  The reformer 20 includes a reforming unit 21 that reforms fuel and a carbon monoxide shift reaction unit (hereinafter referred to as a CO shift unit) that removes carbon monoxide contained in the reformed gas derived from the reforming unit 21. ) 23 and a carbon monoxide selective oxidation unit (hereinafter referred to as a CO selective oxidation unit) 24 that further removes carbon monoxide contained in the reformed gas derived from the CO shift unit 23. Examples of the fuel include natural gas, LPG, kerosene, gasoline, methanol, and the like. In the present embodiment, description will be made on natural gas.

  The reforming unit 21 includes a reaction chamber 21b that is formed in a bottomed cylindrical shape and is disposed so as to open downward, and is filled with a catalyst (reforming catalyst) 21a. The reforming unit 21 is provided with a combustion unit 22. The combustion unit 22 includes a heating chamber 22a that is provided in close contact with the reaction chamber 21b and heats the reaction chamber 21b, and a burner 22b that supplies high-temperature combustion gas to the heating chamber 22a.

  A fuel supply pipe 41 connected to a fuel supply source Sf (for example, a city gas pipe) is connected to the reaction chamber 21b, and fuel is supplied from the fuel supply source Sf. The fuel supply pipe 41 is provided with a first fuel valve 42, a fuel pump 43, a desulfurizer 44, a second fuel valve 45, and a heat exchange unit 46 in order from the upstream. The first and second fuel valves 42 and 45 open and close the fuel supply pipe 41 according to commands from the control device 30. The fuel pump 43 sucks the fuel supplied from the fuel supply source Sf and discharges it to the reaction chamber 21 b of the reforming unit 21, and adjusts the fuel supply amount according to a command from the control device 30. The desulfurizer 44 removes a sulfur content (for example, a sulfur compound) in the fuel. The heat exchange unit 46 supplies the preheated fuel to the reaction chamber 21b of the reforming unit 21 by exchanging heat with the high temperature reformed gas supplied from the reforming unit 21 to the CO shift unit 23. It is. Thereby, the sulfur content is removed from the fuel, and the fuel is preheated and supplied to the reaction chamber 21b.

  Further, a steam supply pipe 52 connected to the evaporator 55 is connected between the second fuel valve 45 of the fuel supply pipe 41 and the heat exchanging section 46, and the steam supplied from the evaporator 55 is mixed with the fuel. To the reaction chamber 21b of the reforming section 21. A water supply pipe 51 connected to a water tank Sw that is a reforming water supply source is connected to the evaporator 55. The water supply pipe 51 is provided with a water pump 53 and a water valve 54 in order from the upstream. The water pump 53 sucks the reformed water supplied from the water tank Sw and discharges it to the evaporator 55, and adjusts the reformed water supply amount according to a command from the control device 30. The water valve 54 opens and closes the water supply pipe 51 according to a command from the control device 30. The water supply pipe 51 is wound around the outer periphery of the heating chamber 22a, and the running water in the water supply pipe 51 is preheated by the high heat of the heating chamber 22a. The evaporator 55 is provided with an exhaust pipe 81 having one end connected to the heating chamber 22a and the other end opened to the outside. The evaporator 55 passes the preheated reformed water supplied to the exhaust pipe 81 through the exhaust pipe 81. Heating is performed by combustion gas (exhaust gas) discharged from the flowing heating chamber 22a to the outside and supplied to the reaction chamber 21b. As a result, the reformed water is preheated and supplied to the evaporator 55, and is supplied to the reaction chamber 21b as water vapor. Note that, in the first embodiment, the evaporation section 56 is constituted by the water supply pipe 51 and the portion wound around the heating chamber 22 a and the evaporator 55. The evaporator 55 is provided with a temperature sensor 55a that detects the internal temperature. Further, a temperature sensor 46 a for detecting the temperature of the mixed gas of fuel and water vapor is provided at the junction of the fuel supply pipe 41 and the water vapor supply pipe 52.

  The reaction chamber 21b is heated by the combustion gas of the burner 22b as will be described later, and the fuel and water vapor supplied into the reaction chamber 21b are converted into a reforming catalyst 21a (for example, Ru, The hydrogen gas and the carbon monoxide gas are generated by reaction and reforming by a Ni-based catalyst (so-called steam reforming reaction). At the same time, in the reaction chamber 21b, the so-called carbon monoxide shift in which carbon monoxide generated by the steam reforming reaction is converted into hydrogen gas and carbon dioxide by reacting with steam as shown in the following chemical formula 2. A reaction is occurring. The generated gas (so-called reformed gas) is cooled through the heat exchange unit 46 and led to the CO shift unit 23. A temperature sensor 21a1 for detecting the temperature of the reforming catalyst 21a is provided in the reaction chamber 21b.

(Chemical formula 1)
_{CH 4 + H 2 O → 3H} 2 + CO-Q1
(Chemical formula 2)
CO + H ₂ O → H ₂ + CO ₂ + Q2

  The steam reforming reaction is an endothermic reaction, and as is clear from the above chemical formula 1, when the reaction proceeds to the right side, the amount of heat Q1 is absorbed, and conversely, when the reaction proceeds to the left side, the amount of heat Q1 is generated. Further, the carbon monoxide shift reaction is an exothermic reaction, and as is clear from the chemical formula 2, the calorific value Q2 is generated when the reaction proceeds to the right side, and conversely, the calorific value Q2 is absorbed when the reaction proceeds to the left side.

  In the CO shift unit 23, the carbon monoxide contained in the supplied reformed gas is caused by the shift catalyst 23a (for example, Pt-based catalyst) filled in the CO shift unit 23, as shown in Chemical Formula 2 above. A so-called carbon monoxide shift reaction that reacts with water vapor and transforms into hydrogen gas and carbon dioxide gas occurs. As a result, the reformed gas is derived with the carbon monoxide concentration reduced by the carbon monoxide shift reaction described above. A temperature sensor 23a1 for detecting the temperature of the shift catalyst 23a is provided in the CO shift unit 23. The CO shift unit 23 has a folded structure, and the reformed gas is introduced from the center of the lower part and led out from the side surface of the folded lower part at the upper part.

  As shown in FIG. 2, the CO shift portion 23 includes an outer cylinder 23h and an inner cylinder 23b that is formed shorter in the axial direction than the outer cylinder 23h and is arranged coaxially with the outer cylinder 23h. An outer peripheral edge and an inner peripheral edge of a bottom plate 23c formed in an annular shape are integrally attached and fixed to lower end edges of the outer cylinder 23h and the inner cylinder 23b. An outer peripheral edge of a top plate 23d formed in a disc shape is integrally attached and fixed to the upper end edge of the outer cylinder 23h, and a gap is formed between the top plate 23d and the upper end of the inner cylinder 23b. A lead-out port 23e is provided at the outer peripheral lower portion of the outer cylinder 23h so as to extend radially outward. Thereby, the opening 23f of the bottom plate 23c, which is an introduction port, communicates with the outlet port 23e through the space inside the inner tube 23b and between the inner tube 23b and the outer tube 23h. Note that the CO shift portion 23 is integrally formed of a metal material (for example, a stainless steel material).

  Further, a first support member 23g formed in a disk shape and having a large number of holes is attached to the introduction port 23f of the CO shift portion 23, and a catalyst 23a filled in the inner cylinder 23b by the first support member 23g. Is supported. In addition, a second support member 23i formed in an annular disk and having a large number of holes at a distance from the bottom plate 23c is also attached below the outer cylinder 23h and the inner cylinder 23b. A catalyst 23a filled between the outer cylinder 23h and the inner cylinder 23b is supported. Further, a temperature sensor 23a1 for detecting the temperature of the catalyst 23a is provided in the lower part of the inner cylinder 23b of the CO shift unit 23.

  Further, the fuel cell system includes a warm-up unit 86 as warm-up means. The warm-up unit 86 introduces reformed gas derived from the CO shift unit 23 (more specifically, reformed gas discharged from the CO selective oxidation unit 24) and air that is an oxidant gas, and incorporates built-in combustion. The CO shift unit 23 is combusted by a catalyst (for example, a palladium-based catalyst or a palladium / platinum-based catalyst), and heat is exchanged between the combustion gas and the reformed gas supplied to the CO shift unit 23. Is to heat. The warm-up unit 86 includes first and second heat exchangers 87a and 87b provided at the lower part and the upper part of the CO shift unit 23, respectively. The first heat exchanger 87a exchanges heat between the reformed gas introduced into the CO shift unit 23 and the combustion gas, and the second heat exchanger 87b passes through the folded portion of the CO shift unit 23. Heat is exchanged between the reformed gas and the combustion gas. The first and second heat exchangers 87a and 87b can also lower the temperature of the reformed gas, which is high during normal operation, to the shift reaction temperature.

  The first heat exchanger 87a includes a casing 87a1 having a central portion formed in a square cross section and an upper portion and a lower portion formed in a circular section. The upper end and the lower end of the casing 87a1 are the inlets 23f of the CO shift portion 23. And the outlet of the heat exchange unit 46 of the reformer 20 are fixed in an airtight manner. Airtight left and right side chambers 87a4 and 87a5 are provided on the outer wall surfaces of the left and right side walls 87a2 and 87a3 of the cylindrical body 87a1 facing each other. The left and right chambers 87a4 and 87a5 are communicated with each other by a plurality of heat exchange pipes 87a6 extending in a substantially horizontal direction and having the left end and the right end fixed in an airtight manner to the left and right side chambers 87a4 and 87a5. The heat exchange pipe 87a6 is filled with a combustion catalyst 87a7. The right chamber 87a5 is connected to the other end of the combustion offgas supply pipe 88, one end of which is connected to the CO selective oxidation unit 24. The air supplied from the combustor air supply pipe 89 and the combustion offgas supply pipe 88 are connected to the right chamber 87a5. The off-gas supplied from is mixed at the junction 88a and supplied to the right chamber 87a5. The other end of the combustion gas supply pipe 90 whose one end is connected to the left chamber 87b4 of the second heat exchanger 87b is connected to the left chamber 87a4.

  The second heat exchanger 87b is configured similarly to the first heat exchanger 87a, and includes a housing 87b1, left and right side walls 87b2 and 87b3, left and right side chambers 87b4 and 87b5, a heat exchange pipe 87b6, and a combustion catalyst 87b7. Yes. The burner 22b is connected downstream of the rear stage of the right chamber 87b5, and the first heat exchanger 87a is connected to the left chamber 87b4 via the combustion gas supply pipe 90. Further, a supply pipe 89a branched from the combustor air supply pipe 89 is connected to the combustion gas supply pipe 90 so that air as an oxidant gas is also supplied to the second heat exchanger 87b. Yes.

  Reformed gas (reformed off gas) supplied from the CO selective oxidation unit 24 without passing through the fuel cell 10 passes through the right side chamber 87a5 via the condenser 77, the second reformed gas valve 76, and the condenser 78, and performs heat exchange. The oxidant gas supplied to the pipe 87a6 and simultaneously supplied in the heat exchange pipe 87a6 is burned in the combustion catalyst 87a7, and the combustion gas is supplied to the second heat exchanger 87b through the left chamber 87a4. On the other hand, the reformed gas supplied from the heat exchange unit 46 of the reformer 20 flows from below the casing 87a1, passes through the inside of the casing 87a1 between the heat exchange pipes 87a6 having a high temperature, and the CO shift unit 23. Is introduced into the inner cylinder 23b from the inlet 23f. Thereby, the temperature of the reformed gas having a low temperature is raised by heat exchange with the combustion gas or the combustion catalyst 87a7. Note that fins (not shown) are provided inside the heat exchange pipe 87a6 and between the heat exchange pipes 87a6, so that the efficiency of heat exchange can be improved. Moreover, the 1st heat exchanger 87a is formed with the stainless steel material, and can improve durability.

  A combustion off-gas supply pipe 88 branched from the off-gas supply pipe 72 downstream of the condenser 78 is connected to the introduction port of the first heat exchanger 87a, and the reformed gas (modified) from the CO selective oxidation unit 24 is connected. Quality off-gas). A combustor air supply pipe 89 branched from the oxidation air supply pipe 61 between the air pump 63 and the first air valve 64 is joined to the combustion offgas supply pipe 88 at a junction 88a, and the air supply source Sa. The air that is the oxidant gas from the first heat exchanger 87a is supplied to the first heat exchanger 87a. Further, the outlet of the first heat exchanger 87a is connected to a combustion gas supply pipe 90 that joins the off gas supply pipe 72 upstream of the burner 22b via the second heat exchanger 87b. The unburned reformed gas is supplied to the burner 22b through the second heat exchanger 87b. The combustion gas bypass pipe 91 bypasses the second heat exchanger 87b and directly connects the combustion gas supply pipe 90 and the off-gas supply pipe 72. The combustion gas discharged from the first heat exchanger 87a is the second heat. The burner 22b is supplied directly without going through the exchanger 87b.

  The off gas supply pipe 72 is provided with a second off gas valve 92 between a branch point with the combustion off gas supply pipe 88 and a junction with the combustion gas supply pipe 90 and the combustion gas bypass pipe 91. The combustion off gas supply pipe 88 is provided with a third off gas valve 93 between the branch point of the off gas supply pipe 72 and the combustor 86. The second and third off-gas valves 92 and 93 open and close the respective pipes, and supply the reformed gas from the CO selective oxidation unit 24 or the anode off-gas from the fuel cell 10 to the burner 22b or the warm-up unit 86. As described above, the control device 30 controls the opening and closing.

  The combustion gas supply pipe 90 is provided with a first combustion gas valve 94 between the first heat exchanger 87a and the second heat exchanger 87b, and the combustion gas bypass pipe 91 is provided with a second combustion gas valve 95. Yes. The first and second combustion gas valves 94 and 95 open and close the respective pipes. When the CO shift unit 23 is warmed up only by the first heat exchanger 87a, the control device 30 causes the first combustion gas valve 94 to open and close. Is closed and the second combustion gas valve 95 is opened, and when the CO shift unit 23 is warmed up by the first and second heat exchangers 87a and 87b, the first combustion gas valve 94 is opened and the second combustion gas valve 95 is closed.

  The combustor air supply pipe 89 is provided with a second air valve 97 between the branch point of the oxidation air supply pipe 61 and the branch point of the supply pipe 89a. Similar to the first air valve 64, the second air valve 97 opens and closes the combustor air supply pipe 89 according to a command from the control device 30, and adjusts the flow rate when the combustor air supply pipe 89 is open. As a result, a predetermined amount of air (oxidant gas) is supplied to the warm-up unit 86. The combustor air supply pipe 89 is provided with a third air valve 98 between the branch point of the supply pipe 89a and the branch point 88a. Similar to the first air valve 64, the third air valve 98 opens and closes the combustor air supply pipe 89 according to a command from the control device 30, and adjusts the flow rate when the combustor air valve is open. Further, a fourth air valve 99 is provided in the supply pipe 89a. Similar to the first air valve 64, the fourth air valve 99 opens and closes the supply pipe 89a according to a command from the control device 30, and adjusts the flow rate when it is in the open state. The third air valve 98 is opened to supply air to the first heat exchanger 87a, and the fourth air valve 99 is opened to supply air to the second heat exchanger 87b. At this time, the opening ratios of the third and fourth valves 98 and 99 can be adjusted to adjust the supply amount ratio. During normal startup, the third air valve 98 is opened and the fourth air valve 99 is closed to supply air only from the upstream side of the first heat exchanger 87a.

  The reformed gas having a reduced carbon monoxide concentration derived from the CO shift unit 23 is supplied to the CO selective oxidation unit 24. On the other hand, the CO selective oxidation unit 24 is connected to an oxidation air supply pipe 61 connected to an air supply source Sa, and air, which is an oxidant gas, is supplied from the air supply source Sa (for example, the atmosphere). . The oxidation air supply pipe 61 is provided with a filter 62, an air pump 63, and a first air valve 64 in order from the upstream. The filter 62 filters air. The air pump 63 sucks in air supplied from the air supply source Sa and discharges it to the CO selective oxidation unit 24, and adjusts the air supply amount in accordance with a command from the control device 30. The first air valve 64 opens and closes the oxidizing air supply pipe 61 according to a command from the control device 30, and adjusts the flow rate when it is open. As a result, a predetermined amount of air is supplied to the CO selective oxidation unit 24.

  The carbon monoxide remaining in the reformed gas supplied to the CO selective oxidation unit 24 is converted into the catalyst 24a (for example, Ru-based or Pt-based) filled in the CO selective oxidation unit 24 as shown in the following chemical formula 3. The catalyst) reacts with the oxygen in the air supplied as described above to become carbon dioxide. As a result, the reformed gas is derived by further reducing the carbon monoxide concentration by oxidation reaction (10 ppm or less), and is supplied to the fuel electrode 11 of the fuel cell 10. Note that hydrogen in the reformed gas is also oxidized into water.

(Chemical formula 3)
CO + 1 / 2O ₂ → CO ₂ + Q3
This reaction is an exothermic reaction, and as is clear from the chemical formula 3 above, the amount of heat Q3 is generated when the reaction proceeds to the right side, and conversely, the amount of heat Q3 is absorbed when the reaction proceeds to the left side.

  A CO selective oxidation unit 24 is connected to the inlet of the fuel electrode 11 of the fuel cell 10 via a reformed gas supply pipe 71 so that the reformed gas is supplied to the fuel electrode 11. A burner 22b is connected to the outlet of the fuel electrode 11 via an off-gas supply pipe 72, and anode off-gas discharged from the fuel cell 10 (reformed gas containing hydrogen that is unused in the fuel electrode 11). The burner 22b is supplied. The bypass pipe 73 bypasses the fuel cell 10 and directly connects the reformed gas supply pipe 71 and the offgas supply pipe 72. The reformed gas supply pipe 71 is provided with a first reformed gas valve 74 between the branch point of the bypass pipe 73 and the fuel cell 10. The off gas supply pipe 72 is provided with a first off gas valve 75 between the junction with the bypass pipe 73 and the fuel cell 10. The bypass pipe 73 is provided with a second reformed gas valve 76. The first and second reformed gas valves 74 and 76 and the first off gas valve 75 open and close the respective pipes and are controlled by the control device 30.

  The leading end of a cathode air supply pipe 67 branched from the oxidizing air supply pipe 61 is connected to the inlet of the air electrode 12 of the fuel cell 10 upstream of the air pump 63. Air, which is an oxidant gas, is supplied. The cathode air supply pipe 67 is provided with a cathode air pump 68 and a cathode air valve 69 in order from the upstream. The cathode air pump 68 sucks air supplied from the air supply source Sa and discharges it to the air electrode 12 of the fuel cell, and adjusts the cathode air supply amount in accordance with a command from the control device 30. The cathode air valve 69 opens and closes the cathode air supply pipe 67 according to a command from the control device 30. Further, one end of an exhaust pipe 82 whose other end is opened to the outside is connected to the outlet of the air electrode 12 of the fuel cell 10.

  Further, a combustion fuel supply pipe 47 branched from the fuel supply pipe 41 is connected to the burner 22b upstream of the fuel pump 43 so that combustion fuel is supplied. The combustion fuel supply pipe 47 is provided with a combustion fuel pump 48. The combustion fuel pump 48 sucks the fuel supplied from the fuel supply source Sf and discharges it to the burner 22b. The fuel supply amount for combustion is adjusted according to the above. Further, a combustion air supply pipe 65 branched from the oxidizing air supply pipe 61 is connected to the burner 22b upstream of the air pump 63, and combustion air for burning combustion fuel, reformed gas or off-gas. Is to be supplied. The combustion air supply pipe 65 is provided with a combustion air pump 66. The combustion air pump 66 sucks air supplied from the air supply source Sa and discharges it to the burner 22b. The combustion air supply amount is adjusted according to the above. When the burner 22b is ignited by a command from the control device 30, the combustion fuel, reformed gas or anode off-gas supplied to the burner 22b is combusted to generate a high-temperature combustion gas, and this combustion gas enters the heating chamber 22a. The reforming catalyst 21a is heated by heating the reaction chamber 21b. The combustion gas that has passed through the heating chamber 22a is exhausted to the outside through the exhaust pipe 81 and the evaporator 55 as exhaust gas.

  Further, a reformed gas condenser 77, an anode offgas condenser 78, and a cathode offgas condenser 79 are provided in the middle of the reformed gas supply pipe 71, the offgas supply pipe 72, and the exhaust pipe 82, respectively. The reformed gas condenser 77 condenses water vapor in the reformed gas supplied to the fuel electrode 11 of the fuel cell 10 flowing in the reformed gas supply pipe 71. The anode offgas condenser 78 condenses water vapor in the anode offgas discharged from the fuel electrode 11 of the fuel cell 10 flowing in the offgas supply pipe 72. The cathode offgas condenser 79 condenses the water vapor in the cathode offgas discharged from the air electrode 12 of the fuel cell 10 flowing in the discharge pipe 82. Each of the condensers 77 to 79 is provided with a refrigerant pipe through which a low-temperature liquid in a hot water tank (not shown) or a liquid cooled by a radiator and a cooling fan is supplied, and each gas is exchanged by heat exchange with the liquid. The water vapor inside is condensed.

  These condensers 77, 78, and 79 communicate with a pure water device 85 through a pipe 84, and condensed water condensed in each condenser 77, 78, and 79 is led out to the pure water device 85 and collected. It has become so. The deionizer 85 converts the condensed water supplied from each of the condensers 77, 78, 79, that is, recovered water into pure water by using a built-in ion exchange resin, and the purified water is led to the water tank Sw. To do. Note that a pipe for introducing makeup water (tap water) supplied from a tap water supply source (for example, a water pipe) is connected to the water purifier 85, and the amount of water stored in the water purifier 85 is below the lower limit water level. And tap water is supplied.

  In addition, the fuel cell system includes a control device 30 that is a control means. The control device 30 includes the temperature sensors 21a1, 23a1, 55a, the pumps 43, 48, 53, 63, 66, 68, Each valve | bulb 42,45,54,64,69,74,75,76,92-95,97 and the burner 22b are connected (refer FIG. 2). The control device 30 includes a microcomputer (not shown), and the microcomputer includes an input / output interface, a CPU, a RAM, and a ROM (all not shown) connected through a bus. The CPU executes a program corresponding to the flowcharts of FIGS. 4 and 5 to control the first and second air valves 64 and 97 to the warm-up unit 86 and the CO selective oxidation unit 24 when the fuel cell system is activated. The supply amount ratio of the oxidant gas is controlled to be a predetermined ratio set in consideration of the activation temperature range of the shift catalyst 23a and the selective oxidation catalyst 24a. The RAM temporarily stores variables necessary for executing the program, and the ROM stores the program.

  The oxidation air supply pipe 61, the combustor air supply pipe 89, and the air pump 63 described above are oxidant gas supply means for supplying an oxidant gas to the warm-up unit 86 and the CO selective oxidation unit 24. The first and second air valves 64 and 97 are provided in the oxidant gas supply means, and oxidant gas that distributes the oxidant gas to the warm-up unit 86 and the CO selective oxidation unit 24 so that the supply amount thereof can be adjusted. Distribution means.

  Further, the oxidant gas supply means described above is provided with only one air pump 63 as a supply source, and selectively oxidizes the air from the air pump 63 through the oxidation air supply pipe 61 and the combustor air supply pipe 89. The supply amount ratio is adjusted and controlled by the first and second air valves 64 and 97 so as to be supplied to the unit 24 and the warm-up unit 86, but the oxidation air supply pipe 61 and the combustor A pump (blower) as a supply source may be provided in each of the air supply pipes 89, and the discharge amount of each pump may be adjusted to control the supply amount ratio.

  Next, activation of the above-described fuel cell system will be described with reference to FIGS. When a start switch (not shown) is turned on at time t0, control device 30 executes the program shown in FIG. 4 and controls the fuel cell system as shown in FIG. In step 102, the control device 30 closes the first reformed gas valve 74, the first offgas valve 75, the third offgas valve 93, the second combustion gas valve 95, and the third combustion gas valve 96, The second off-gas valve 92 is opened to connect the CO selective oxidation unit 24 to the burner 22b, the first fuel valve 42 is opened, the second fuel valve 45 is closed, and the combustion fuel pump 48 and the combustion air pump 66 are driven. Combustion fuel and combustion air are supplied to the burner 22b to ignite the burner 22b. Thereby, the fuel for combustion is combusted, and the reforming catalyst 21a and the evaporator 55 in the reforming unit 21 are heated by the combustion gas.

  The control device 30 detects the temperature of the evaporator 55 by the temperature sensor 55a, and when the detected temperature is equal to or higher than the first predetermined temperature Th1 (time t1), the water valve 54 is opened and the water pump 53 is driven. Water in the water tank Sw is supplied to the reforming unit 21 (steps 104 and 106).

  The control device 30 starts counting the timer from the time (time t1) when the temperature of the evaporator 55 becomes equal to or higher than the predetermined temperature Th1. If the timer is equal to or longer than the first predetermined time T1 (for example, 1 minute) (time t2), the second fuel valve 45 is opened to drive the fuel pump 43, and the fuel from the fuel supply source Sf is supplied at a predetermined flow rate (predetermined supply amount: normal). The operating flow rate, for example, a flow rate at which S / C becomes 3) is supplied to the reforming unit 21, and the first air valve 64 is opened to drive the air pump 63, and the air from the air supply source Sa is supplied at a predetermined flow rate (predetermined flow rate). (Supply amount: normal operation flow rate) is supplied to the CO selective oxidation unit 24 (steps 108 and 110). Thereby, in the reforming part 21, the steam reforming reaction and the carbon monoxide shift reaction described above occur and the reformed gas is generated. The reformed gas derived from the reforming unit 21 is derived from the CO selective oxidizing unit 24 with the carbon monoxide gas reduced by the CO shift unit 23 and the CO selective oxidizing unit 24 and supplied to the burner 22b of the combustion unit 22. And burned.

  At this time, the control device 30 executes the program in parallel according to the flowchart shown in FIG. That is, the control device 30 opens the water valve 54 in Step 106 and starts supplying reformed water, and then the temperature of the mixed gas of fuel and water vapor detected by the temperature sensor 46a is the third predetermined temperature Th3. The amount of reforming water that is larger than the supply amount during normal operation is supplied only until the temperature reaches (for example, 110 ° C.) or higher. (Steps 202 to 206).

For example, the reforming water is supplied so that the second regeneration operation flow rate is S / C (steam / carbon ratio) = 15 with respect to the fuel of the normal operation flow rate. Thus, when only a large amount of reformed water is introduced into the reforming section 21 heated to a predetermined temperature, a large amount of steam is generated and this steam functions as a heat medium. Therefore, the heat conduction of the reforming catalyst 21a. As a result, the heat supplied from the combustion unit 22 and the heat received by the heat medium from the heat vessel of the reformer that has been locally heated easily propagate in the catalyst. Therefore, the temperature of the reforming unit 21 is raised from the steady operation temperature range. As a result, the reformed gas heated to a high temperature in a short time is supplied to the CO shift unit 23. Furthermore, since the high temperature due to the large amount of reforming water generated in the reforming unit 21 described above also occurs in the CO shift unit 23, the CO shift unit 23 is heated from the steady operation temperature range.

  At time t2, the control device 30 closes the second off-gas valve 92, opens the third off-gas valve 93, and the first combustion gas valve 94, connects the CO selective oxidation unit 24 to the first heat exchanger 87a, and selects CO. The reformed gas from the oxidation unit 24 is supplied to the first heat exchanger 87a, and the second air valve 97 is opened to supply the air from the air supply source Sa to the first heat exchanger 87a (step 110). Thereby, the reformed gas is combusted in the first heat exchanger 87a, the combustion gas is supplied to the second heat exchanger 87b, the reformed gas is combusted in the second heat exchanger 87b, and the combustion gas is burned. The combustible gas which is supplied to 22b and remains unburned is burned in the burner 22b. In step 112, the control device 30 controls the first and second air valves 64 and 97 to adjust the supply ratio or supply amount of the oxidant gas to the warm-up unit 86 and the CO selective oxidation unit 24. ing.

  In the first heat exchanger 87a, the reformed gas introduced into the CO shift unit 23, which is still at a low temperature at the time of startup, is heat-exchanged with the combustion gas, and the temperature is raised. The reformed gas thus introduced is introduced and the shift catalyst 23a is heated to the catalyst regeneration temperature (described later). In the second heat exchanger 87b as well, the reformed gas passing through the CO shift portion 23 that is still at a low temperature at the time of start-up is heat-exchanged with the combustion gas, and the temperature is raised. The temperature of the reformed gas after the turn-up portion of the reformed gas is raised to the catalyst regeneration temperature (described later).

  The temperature control of the CO shift unit 23 is performed by adjusting the amount of air supplied (supply amount) to the warm-up unit 86. When the fuel supply amount is 1, the input amount is 1.1 at the start of injection (at the start of warming up of the fuel cell system) and 0 at the end of input (at the completion of warming up of the fuel cell system). . From the start to the end of charging, the supply amount is variable, and the range is 0.2 to 1.1. In any case, the supply amount is set in consideration of the heat-resistant temperature of the shift catalyst (for example, 350 ° C. or less for Cu-based materials) and the activation temperature range (for example, 150 to 350 ° C. for Cu-based materials). The temperature of the CO shift unit 23, that is, the shift catalyst 23a is set to be an activation temperature range of 150 ° C to 350 ° C.

  On the other hand, the temperature control of the CO selective oxidation unit 24 is performed by adjusting the amount of air introduced into the CO selective oxidation unit 24. The input amount is 0.3 at the start of injection (when the fuel cell system warms up) when the fuel supply amount is 1, and 0.3 at the end of input (when the fuel cell system is warmed up). And From the start to the end of charging, the supply amount is variable, and the range is 0.3-1. In any case, the supply amount is set in consideration of the activation temperature range (110 to 200 ° C.) of the selective catalyst 24a of the CO selective oxidation unit 24. In practice, the inlet temperature of the CO selective oxidation unit 24 is It is set to be 110 ° C to 200 ° C.

  Thus, during the generation of the reformed gas, the control device 30 detects the temperature of the catalyst 23a of the CO shift unit 23 by the temperature sensor 23a1, and if this detected temperature is equal to or higher than the second predetermined temperature Th2 (time). t3) The second air valve 97 is closed to stop the supply of air to the warm-up unit 86 (steps 114 and 116). As a result, the amount of heat of the combustion gas supplied to the first and second heat exchangers 87a and 87b is reduced, that is, the temperature of the reformed gas is not increased by the combustion gas.

  The control device 30 starts counting the timer from time t3, and when the timer becomes equal to or longer than a second predetermined time T2 (for example, 3 minutes) (time t4), the first reformed gas valve 74, the first offgas valve 75, and the first The second off-gas valve 92 is opened, the third off-gas valve 93, the first and second combustion gas valves 94, 95 and the second reformed gas valve 76 are closed, and the CO selective oxidation unit 24 is connected to the inlet of the fuel electrode 11 of the fuel cell 10. And the outlet of the fuel electrode 11 is connected to the burner 22b (steps 118 and 120).

  In step 122, the control device 30 starts a steady operation (an operation mode in which the fuel cell 10 generates power). At this time, the fuel pump 43, the water pump 53, and the air pump 63 are continuously driven to supply fuel, water (water vapor), and air to the reformer 20. Specifically, the reforming water supply flow rate is substantially constant from time t1, and the fuel supply flow rate is substantially constant from time t2. Medium supply amount) of reforming water and fuel are continuously supplied at a predetermined ratio (for example, S / C (steam carbon ratio) = 3). The supply flow rate of the oxidizing air to the CO selective oxidation unit 24 is basically constant from time t2, but the temperature at the inlet of the CO selective oxidation unit 24 is controlled between 110 ° C. and 200 ° C. The supply flow rate is adjusted as follows. Further, the combustion fuel pump 48 and the combustion air pump 66 are driven so that the combustion fuel and the combustion air are supplied to the burner 22b so as to have a predetermined flow rate (predetermined supply amount: steady operation flow rate) in consideration of the supply amount of the anode off gas. Supply. When the stop switch is pushed, the fuel cell system stops.

  As can be understood from the above description, in this embodiment, when the fuel cell system is started, the first and second air valves 64 and 97 are controlled to the warm-up unit 86 and the carbon monoxide selective oxidation unit 24. The warming unit 86 and the carbon monoxide selective oxidation unit 24 are oxidized so that the supply ratio of the oxidant gas becomes a predetermined ratio set in consideration of the activation temperature range of the shift catalyst 23a and the selective oxidation catalyst 24a. Each agent gas is supplied. Accordingly, since the carbon monoxide shift reaction unit 23 is quickly warmed up by the warming-up unit 86 and the carbon monoxide selective oxidation unit 24 is also warmed up, the fuel cell system as a whole can be warmed up efficiently and quickly. Can do. Moreover, the input energy required for start-up is reduced, and the average power generation efficiency during operation is increased.

  Further, the warm-up unit 86 includes a plurality of heat exchange units (heat exchangers), and the oxidant gas is distributed and supplied to each heat exchange unit, so that a plurality of carbon monoxide shift reaction units 23 are provided. Since it warms up from a location, the warm-up time of the carbon monoxide shift reaction unit 23 can be further shortened, and as a result, the warm-up time of the fuel cell system can be further shortened.

  Further, any one of the plurality of heat exchange units of the warm-up unit 86 is at least the reformed gas introduction port 23f of the carbon monoxide shift reaction unit 23 or an intermediate between the reformed gas introduction port 23f and the reformed gas outlet port 23e. The carbon monoxide shift reaction unit 23 can be efficiently warmed up by being provided at any position (for example, the folded portion).

Further, it is further provided with a reforming water supply means for supplying the reforming water to the reforming section 21, and this reforming water supply means has a larger amount of reforming than the supply amount during normal operation while the warm-up unit 86 is in operation. By supplying water, the temperature of the carbon monoxide shift reaction unit 23 is increased, whereby the warm-up time of the carbon monoxide shift reaction unit 23 can be further shortened. As a result, the warm-up time of the fuel cell system can be reduced. Further shortening is possible. Furthermore, the following are mentioned as an effect which increases the supply amount of reforming water.
1) The start-up time can be shortened by increasing the flow rate and increasing the amount of heat exchange per hour.
2) The durability can be improved by suppressing the temperature rise of the catalyst.
3) Startability and durability can be improved by mitigating the temperature rise concentration at the inlet portion of the carbon monoxide shift reaction unit 23 and facilitating the temperature rise in the middle and subsequent stages of the carbon monoxide shift reaction unit 23. .
4) The startability can be improved by increasing the amount of heat input per time according to 2) and 3) above.

  In the above-described embodiment, the present invention is applied to the fuel cell system including the steam reforming reformer 20. However, the present invention is applicable to a fuel cell system including an autothermal reformer. It is.

  In the above-described embodiment, the warm-up unit 86 introduces the reformed gas and the oxidant gas derived from the carbon monoxide selective oxidation unit 24 and burns with the built-in combustion catalyst. The carbon monoxide shift reaction unit 23 may be heated by directly heating the carbon monoxide shift reaction unit 23. Further, the catalyst of the warm-up unit may be moved to another separately provided unit to generate combustion gas, and the combustion gas may be supplied to the first and second heat exchangers 87a and 87b. .

  In the above-described embodiment, the oxidant gas distribution unit is provided in the oxidant gas supply unit and distributes the oxidant gas to the warm-up unit 86 and the CO selective oxidation unit 24 so that the supply amount thereof can be adjusted. Is configured by the first and second air valves 64 and 97 capable of adjusting the flow rate, but the degree of opening and closing provided at the branch point of the oxidation air supply pipe 61 and the combustor air supply pipe 89 can be controlled. You may make it comprise with a port valve. The second air valve 97 may not be provided. In this case, the function of the second air valve 97 may be substituted by the third and fourth valves 98 and 99.

  In the above-described embodiment, the third and fourth air valves 98 and 99 are used as flow rate adjusting means for distributing the oxidant gas to the first and second heat exchangers 87a and 87b so that the supply amount thereof can be adjusted. However, it may be configured by a three-port valve provided at a branch point between the combustor air supply pipe 89 and the supply pipe 89a and capable of controlling the degree of opening and closing.

1 is a schematic diagram showing an outline of an embodiment of a fuel cell system according to the present invention. (A) is sectional drawing which shows the CO shift part and warming-up unit shown in FIG. 1, (b) is sectional drawing along the 2b-2b line | wire shown in FIG. 2 (a). It is a block diagram which shows the fuel cell system shown in FIG. It is a flowchart of the control program performed with the control apparatus shown in FIG. It is a flowchart of the control program performed with the control apparatus shown in FIG. It is a time chart which shows operation | movement of 1st Embodiment of the fuel cell system by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Fuel electrode, 12 ... Air electrode, 20 ... Reformer, 21 ... Reforming part, 21a ... Reforming catalyst, 21a1 ... Temperature sensor, 21b ... Reaction chamber, 22 ... Combustion part, 22b ... Burner, 23 ... CO shift unit, 23a ... catalyst, 24 ... CO selective oxidation unit, 24a ... catalyst, 24a1 ... temperature sensor, 30 ... control device, 41 ... fuel supply pipe, 42 ... first fuel valve, 43 ... fuel pump 44 ... desulfurizer, 45 ... second fuel valve, 46 ... heat exchange part, 46a ... temperature sensor, 47 ... combustion fuel supply pipe, 48 ... combustion fuel pump, 51 ... feed water pipe, 52 ... steam supply pipe, 53 ... Water pump, 54 ... Water valve, 55 ... Evaporator, 55a ... Temperature sensor, 61 ... Oxidation air supply pipe, 62 ... Filter, 63 ... Air pump, 64 ... First air valve, 65 ... Combustion air supply Pipe, 66 ... Combustion air , 67 ... cathode air supply pipe, 68 ... cathode air pump, 69 ... cathode air valve, 71 ... reformed gas supply pipe, 72 ... offgas supply pipe, 73 ... bypass pipe, 74 ... first reformed gas valve 75 ... first off gas valve, 76 ... second reformed gas valve, 77, 78, 79 ... condenser, 81,82 ... exhaust pipe, 84 ... recovered water outlet pipe, 86 ... warm-up unit, 87a, 87b ... first 1 and 2nd heat exchanger, 88 ... Combustion off gas supply pipe, 89 ... Combustor air supply pipe, 90 ... Combustion gas supply pipe, 91 ... Combustion gas bypass pipe, 92 ... Second off gas valve, 93 ... Third off Gas valve, 94, 95 ... 1st and 2nd combustion gas valve, 97 ... 2nd air valve, Sa ... Air supply source, Sf ... Fuel supply source, Sw ... Reformed water supply source.

Claims (4)

A reforming unit that generates and derives a reformed gas containing hydrogen by reforming the supplied fuel with a reforming catalyst filled therein, and one of the reformed gases derived from the reforming unit A carbon monoxide shift reaction part that is derived by reducing the carbon oxide concentration by a shift catalyst filled inside, and carbon monoxide in the reformed gas derived from the carbon monoxide shift reaction part is filled inside. In a fuel cell system including a carbon monoxide selective oxidation unit that is further reduced by oxidation with a supplied oxidant gas by a selective oxidation catalyst and is supplied to a fuel cell.
The reformed gas and the oxidant gas derived from the carbon monoxide selective oxidation unit are introduced and burned by a built-in combustion catalyst, and the combustion gas and the reformed gas supplied to the carbon monoxide shift reaction unit A warming-up means for heating the carbon monoxide shift reaction unit by directly exchanging heat between them or by directly heating the carbon monoxide shift reaction unit by the heat of combustion thereof,
An oxidant gas supply means for supplying an oxidant gas to the warm-up means and the carbon monoxide selective oxidation unit;
An oxidant gas distribution means provided in the oxidant gas supply means, for distributing the oxidant gas to the warm-up means and the carbon monoxide selective oxidation unit so that the supply amount thereof can be adjusted;
At the time of start-up, the oxidant gas distribution means is controlled to consider the ratio of the amount of oxidant gas supplied to the warm-up means and the carbon monoxide selective oxidation unit, taking into account the active temperature range of the shift catalyst and the selective oxidation catalyst. A fuel cell system comprising control means for setting a predetermined ratio.   2. The fuel cell system according to claim 1, wherein the warm-up unit includes a plurality of heat exchange units, and the oxidant gas is distributed and supplied to each heat exchange unit.   3. The heat exchange unit according to claim 2, wherein any one of the plurality of heat exchange units of the warm-up means is at least a reformed gas inlet of the carbon monoxide shift reaction unit or an intermediate between the reformed gas inlet and the reformed gas outlet. A fuel cell system provided at any one of the positions. The reforming water supply means according to any one of claims 1 to 3, further comprising reforming water supply means for supplying reforming water to the reforming section, wherein the reforming water supply means is operated while the warm-up means is in operation. A fuel cell system characterized in that the carbon monoxide shift reaction section is heated by supplying a larger amount of reforming water than the supply amount during normal operation.

Images