JP2007220424A - Reformer and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reformer and fuel cell system which enable a combustor to achieve adequate combustion in each mode. <P>SOLUTION: This fuel cell system has a combustor 25 capable of burning a combustion fuel to be fed to a heat chamber 25b with combustion oxidants to be supplied via intakes 25d1 and 25d2 built in multiple stages of the corresponding heat chamber 25b to generate a combustion gas. Additionally, it has a combustion oxidant supply means which is provided with the intakes 25d1 and 25d2 built in each stage from a rear anchor to a forefront in the heat chamber 25b, and is capable of independently and selectively supplying combustion oxidants to the intakes 25d1 and 25d2 built in each stage; and a control means for controlling the means for supplying combustion oxidants so that each amount of combustion oxidant input via the intakes 25d1 and 25d2 in each stage equals the corresponding setting value depending on the operation mode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reformer and a fuel cell system.

  As one type of reforming apparatus, one disclosed in Patent Document 1 “Burner in Fuel Cell Reformer” is known. As shown in FIG. 1 of Patent Document 1, the combustion cylinder 20 in the fuel cell reformer 10 is provided with a high calorie fuel injection portion (nozzle 44) at the center thereof, and this high calorie fuel injection portion. A first oxidant injection portion (opening portion of the first oxidant passage 54) is provided at a position on the radially outer side of the first oxidant injection portion, and a low calorie fuel injection portion ( The opening portion of the low calorie fuel passage 56) is provided, and the second oxidant injection portion (opening portion of the second oxidant passage 58) is provided at a position radially outside the low calorie fuel injection portion. That is, the combustion fuel introduced into the combustion cylinder 20 is combusted by the combustion oxidant introduced from the inlets provided in a plurality of stages in the combustion cylinder 20 to generate combustion gas.

In the reformer configured as described above, when using a high calorie fuel such as natural gas or reformed gas, the fuel is injected from the central high calorie fuel injection unit, and the surrounding first oxidant is used. The oxidizer is jetted from the jet section and the second oxidizer jet section. Moreover, when using low calorie fuel, such as battery waste fuel, this is injected from a low calorie fuel injection part, and the 1st oxidant injection part and 2nd oxidant injection which are located in the radial direction inner side and the outer side The oxidant was sprayed from the part.
JP-A-5-303974 JP-A-8-162137 JP 2003-252604 A

  In the reforming apparatus described in Patent Document 1 described above, since each supply amount of the oxidant supplied from the first oxidant injection unit and the second oxidant injection unit is not controlled, in each operation mode There was a problem that the combustion part could not carry out proper combustion. For example, if the combustor cannot perform appropriate combustion in the start-up operation, there will be a problem that the start-up time cannot be shortened sufficiently, and if the combustor cannot perform appropriate combustion in the power generation operation, The problem of causing disappearance or high emission occurs.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to enable a combustion unit to perform appropriate combustion in each operation mode in a reformer and a fuel cell system.

  In order to solve the above-mentioned problems, the structural feature of the invention according to claim 1 is that the combustion fuel charged into the combustion cylinder is oxidized for combustion injected from a plurality of inlets provided in the combustion cylinder. In a reformer equipped with a combustion section that burns with an agent to generate combustion gas, the inlet of each stage is arranged from the base end to the tip of the combustion cylinder and is independent and selected with respect to the inlet of each stage The combustion oxidant supply means capable of supplying combustion oxidant and the amount of combustion oxidant charged from each stage inlet are set to values set according to the operation mode. And a control means for controlling the combustion oxidant supply means.

  Further, the structural feature of the invention according to claim 2 is that, in claim 1, the reforming unit that generates reformed gas from the supplied reforming fuel and steam and supplies the reformed gas to the fuel cell, and the supplied reforming unit. The operation mode further includes an evaporation section that generates water vapor from the deionized water and leads it to the reforming section, and a combustion gas passage that distributes the combustion gas generated in the combustion section in the order of the reforming section and the evaporation section. However, it has the 1st starting operation mode from the time of starting of a reformer to the time of starting production of water vapor in an evaporation part, and in the 1st starting operation mode, it is from the input port located in the tip side of a combustion cylinder. That is, the amount of combustion oxidant input is set to be larger than the amount of combustion oxidant input from the inlet located on the base end side of the combustion cylinder.

  Further, the structural feature of the invention according to claim 3 is that in claim 1 or claim 2, the operation mode has a second start-up operation mode after the time when the generation of water vapor is started in the evaporation section. In the two-startup operation mode, the amount of combustion oxidant charged from the inlet located on the proximal end side of the combustion cylinder is larger than the amount of combustion oxidant charged from the inlet located on the distal end side of the combustion cylinder. It is set to.

  A structural feature of the invention according to claim 4 is a fuel cell comprising the reformer according to claim 1 and a fuel cell that generates electric power using the reformed gas supplied from the reformer. In the system, when the operation mode is the power generation operation mode and the output power of the fuel cell is low or increasing, the oxidation for combustion from the inlet located at the base end side of the combustion cylinder is performed. The charging amount of the oxidant is set to a first predetermined flow rate at which fuel-rich combustion is performed, and the charging amount of the oxidant for combustion from the charging port located on the tip side of the combustion cylinder is set to a second predetermined flow rate at which low emission is achieved It has been done.

  In the invention according to claim 1 configured as described above, the combustion oxidant supply means performs combustion independently and selectively with respect to the inlet of each stage disposed from the base end to the front end of the combustion cylinder. It is possible to supply an oxidizing agent. In addition, the control means controls the combustion oxidant supply means so that the respective amounts of the combustion oxidant input from the input ports of the respective stages have values set in accordance with the operation modes. This makes it possible to independently and selectively control the input amount (supply amount) of the combustion oxidant input from the input port of each stage according to the operation mode. Therefore, the combustion section can perform appropriate combustion in each operation mode.

  In addition, after burning with the combustion oxidant from the inlet located on the proximal end side of the combustion cylinder, the combustion gas flow rate is reduced by supplying a specified amount of combustion oxidant from the inlet located on the distal end side. The heat can be efficiently applied to the evaporation section. Therefore, the evaporation part is heated early with the combustion gas, water vapor can be generated at an early stage, and as a result, the warm-up time can be shortened.

  In the invention according to claim 2 configured as described above, in the invention according to claim 1, the operation mode is the first start-up operation mode from the start time to the start of the generation of water vapor in the evaporator, Because the amount of combustion oxidant input from the inlet located on the front end side of the combustion cylinder is set to be larger than the amount of combustion oxidant input from the inlet located on the base end side of the combustion cylinder. By increasing the flow velocity of the combustion gas without blowing out the flame and causing the combustion gas to quickly reach the evaporation section, the heat of the combustion gas can be efficiently transmitted to the evaporation section. Therefore, the evaporating section is heated early by the combustion gas, and water vapor can be generated at an early stage, and as a result, the warm-up time can be shortened.

  In the invention according to claim 3 configured as described above, in the invention according to claim 2, the oxidizer for combustion from the tip of the combustion cylinder after the operation mode starts generation of water vapor in the evaporation section By reducing this, the combustion gas temperature can be increased. Therefore, the temperature and heat quantity required by the reforming section can be efficiently supplied from the combustion gas to the reforming section. As a result, it is possible to shorten the warm-up time of the reformer and improve the power generation efficiency during power generation.

  In the invention according to claim 4 configured as described above, when the operation mode is the power generation operation mode and the output power of the fuel cell is low or increasing, the base of the combustion cylinder is used. The charging amount of the combustion oxidant from the inlet located on the end side is set to the first predetermined flow rate at which fuel-rich combustion is performed, and the combustion oxidant is charged from the inlet located on the tip side of the combustion cylinder Since the amount is set to the second predetermined flow rate at which low emission is achieved, it is possible to surely prevent the flame from being blown off and realize low emission.

  Hereinafter, an embodiment of a fuel cell system to which a reformer according to the present invention is applied will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. The fuel cell system includes a fuel cell 10 and a reformer 20 that generates a reformed gas (fuel gas) containing hydrogen gas necessary for the fuel cell 10.

  The fuel cell 10 includes a fuel electrode 11, an air electrode 12 that is an oxidant electrode, and an electrolyte 13 interposed between the electrodes 11 and 12, and supplies the reformed gas supplied to the fuel electrode 11 and the air electrode 12. Electric power is generated using air (cathode air), which is the oxidant gas. Note that air-enriched gas may be supplied instead of air.

  The reformer 20 steam reforms the reforming fuel and supplies a hydrogen-rich reformed gas to the fuel cell 10. The reformer 20 includes a reforming unit 21, a cooling unit 22, a carbon monoxide shift reaction unit (hereinafter referred to as a “carbon monoxide shift reaction unit”). , A CO shift unit) 23, a carbon monoxide selective oxidation reaction unit (hereinafter referred to as a CO selective oxidation unit) 24, a combustion unit 25, and an evaporation unit 26. The reforming fuel includes natural gas, LPG, kerosene, gasoline, methanol, and the like. In the present embodiment, description will be made on natural gas.

  The reforming unit 21 generates and derives a reformed gas from a mixed gas that is a reforming raw material in which water vapor is mixed with the fuel supplied from the fuel supply source Sf. The reforming portion 21 is formed in a bottomed cylindrical shape, and is formed of an outer flow path 21a1 and an inner flow path 21a2 each formed in an annular shape, and is an annular fold extending along the axis in the annular cylindrical portion. A flow path 21a is provided.

  The return channel 21 a of the reforming unit 21 is filled with a catalyst 21 b (for example, a Ru or Ni-based catalyst) and introduced from the reforming fuel introduced from the cooling unit 22 and the steam supply pipe 52. The gas mixture with the steam reacts and is reformed by the catalyst 21b to generate hydrogen gas and carbon monoxide gas (so-called steam reforming reaction). At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide generated in the steam reforming reaction reacts with steam to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led to a cooling unit (heat exchange unit) 22. The steam reforming reaction is an endothermic reaction, and the carbon monoxide shift reaction is an exothermic reaction.

  The cooling unit 22 is a heat exchanger (heat exchange unit) in which heat exchange is performed between the reformed gas derived from the reforming unit 21 and a mixed gas of reforming fuel and reformed water (steam). The temperature of the reformed gas having a high temperature is lowered by the mixed gas having a low temperature and led to the CO shift unit 23, and the temperature of the mixed gas is raised by the reformed gas and led to the reforming unit 21. Yes. Specifically, a fuel supply pipe 41 connected to a fuel supply source Sf (for example, a city gas pipe) is connected to the cooling unit 22, and reforming 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, and a second fuel valve 45 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 reforming fuel supplied from the fuel supply source Sf and discharges it to the reforming unit 21 through the cooling unit 22. The fuel pump 43 supplies the reforming fuel supply amount in accordance with a command from the control device 30. To be adjusted. The desulfurizer 44 removes sulfur (for example, sulfur compounds) in the reforming fuel. Thereby, the sulfur content is removed from the reforming fuel and supplied to the reforming unit 21.

  Further, a steam supply pipe 52 connected to the evaporation section 26 is connected between the second fuel valve 45 of the fuel supply pipe 41 and the cooling section 22. The steam supplied from the evaporation unit 26 is mixed with the reforming fuel, and the mixed gas is supplied to the reforming unit 21 through the cooling unit 22. A water supply pipe 51 connected to a water tank Sw that is a reforming water supply source is connected to the evaporation unit 26. 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 evaporation unit 26, 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 evaporation section 26 heats and boiles the reformed water to generate water vapor and supplies the steam to the reforming section 21 via the cooling section 22. The evaporation section 26 is formed in a cylindrical shape and has a first shape of the combustion gas channel 27. 2 The outer peripheral flow path 27c is provided so as to cover the outer peripheral wall. The evaporation section 26 has a water supply pipe 51 and a water vapor supply pipe 52 connected to a lower side wall surface and an upper side wall surface, respectively, and water introduced from the water supply pipe 51 circulates in the evaporation section 26 and is heated to generate water vapor and Thus, the water is supplied to the water vapor supply pipe 52. In addition, a temperature sensor 87 for detecting the temperature of the water vapor or the temperature of the mixed gas is provided in the water vapor supply pipe 52 (or a portion of the fuel supply pipe 41 downstream from the junction with the water vapor supply pipe 52). The signal is output to the control device 30.

  The CO shift unit 23 is a unit that reduces carbon monoxide in the reformed gas supplied from the reforming unit 21 through the cooling unit 22, that is, a carbon monoxide reducing unit. The CO shift unit 23 includes a cylindrical casing 23a having an upper surface and a lower surface, and an inner cylinder 23b disposed coaxially within the casing 23a. The inner cylinder 23b has an upper end connected to the inner peripheral end of an annular support member 23c whose outer peripheral end is connected to the inner peripheral surface of the housing 23a. A reformed gas inlet 23a1 is provided on the upper surface of the housing 23a, and the other end of a connecting pipe 89 having one end connected to the CO selective oxidation unit 24 is connected to a side surface of the housing 23a. A catalyst 23d (for example, a Cu—Zn-based catalyst) is filled in the inner cylinder 23b of the CO shift portion 23 and between the inner cylinder 23b and the housing 23a. The CO shift unit 23 is provided with a temperature sensor 23e for detecting the temperature in the CO shift unit 23, for example, the temperature in the vicinity of the reformed gas inlet of the CO shift unit 23, and the detection signal is sent to the control device 30. It is output.

  In the CO shift unit 23 configured as described above, the reformed gas led out from the cooling unit 22 passes through the reformed gas introduction port 23a1, passes through the catalyst 23d in the inner cylinder 23b, and turns back to form the inner cylinder 23b. It is led out to the CO selective oxidation unit 24 through the catalyst 23d between the housing 23a. At this time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide and water vapor contained in the introduced reformed gas react with the catalyst 23d to be converted into hydrogen gas and carbon dioxide gas. This carbon monoxide shift reaction is an exothermic reaction.

  The CO selective oxidation unit 24 further reduces the carbon monoxide in the reformed gas supplied from the CO shift unit 23 and supplies it to the fuel cell 10, that is, a carbon monoxide reduction unit, and is formed in a cylindrical shape. Then, the outer peripheral wall of the evaporation part 26 is covered and provided. In this CO selective oxidation unit 24, a connecting pipe 89 and a reformed gas supply pipe 71 are respectively connected to a lower side wall surface and an upper side wall surface, and a catalyst 24a (for example, a Ru or Pt catalyst) is filled therein. The reformed gas introduced through the connection pipe 89 flows through the CO selective oxidation unit 24 and is led out from the reformed gas supply pipe 71.

  Further, the reforming gas supplied to the CO selective oxidation unit 24 is mixed with oxidizing air. That is, the connection pipe 89 is connected to the oxidation air supply pipe 61 connected to the air supply source Sa, and is supplied with oxidation air 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 an 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 air valve 64 opens and closes the oxidizing air supply pipe 61 according to a command from the control device 30. Thus, the oxidizing air is mixed with the reformed gas from the CO shift unit 23 and supplied to the CO selective oxidation unit 24.

  Therefore, carbon monoxide in the reformed gas introduced into the CO selective oxidation unit 24 reacts with oxygen in the oxidizing air to become carbon dioxide. This reaction is an exothermic reaction and is promoted by the catalyst 24a. Thereby, the reformed gas is derived by further reducing the carbon monoxide concentration (10 ppm or less) by the oxidation reaction, and is supplied to the fuel electrode 11 of the fuel cell 10.

  The combustion part 25 generates combustion gas for heating the reforming part 21 and supplying heat necessary for the steam reforming reaction. The lower end part is inserted into the inner peripheral wall of the reforming part 21. It is arranged with a space. As shown in FIG. 2, the combustion section 25 includes a main body 25a, a cylindrical combustion cylinder 25b that stands on the main body 25a and communicates with the main body 25a, and an electrode (not shown). The combustion unit 25 is ignited according to a command from the control device 30.

  The main body 25a is supplied with a combustion fuel, a combustible gas such as an anode off-gas and a reformed gas, and an oxidant gas such as combustion air for burning (oxidizing) the combustible gas. The combustion cylinder 25b includes an outer cylinder 25c and an inner cylinder 25d disposed coaxially with the outer cylinder 25c. The base end of the inner cylinder 25d is erected from the inner peripheral edge of the injection port 25a1 of the main body 25a. The inner cylinder 25d communicates with the main body 25a, and combustion fuel and combustion air derived from the main body 25a are introduced into the inner cylinder 25d through the base end opening 25d1 of the inner cylinder 25d. That is, the base end opening 25d1 of the inner cylinder 25d is the first stage insertion port.

  The base end of the outer cylinder 25c is connected to the main body 25a, and the inner peripheral end and the outer peripheral end of the annular plate 25e are connected to the distal ends of the inner cylinder 25d and the outer cylinder 25c, respectively. Thereby, the annular space S between the inner cylinder 25d and the outer cylinder 25c is not in communication with the main body 25a. A combustion air inlet 25c1 is formed in the outer cylinder 25c, and a combustion air outlet 25d2 is formed at the tip of the inner cylinder 25d. The combustion air supplied to the space S is introduced into the inner cylinder 25d through the outlet 25d2. That is, the outlet 25d2 of the inner cylinder 25d is the second stage inlet. As described above, the combustion cylinder 25b is provided with a plurality of stages (two stages in this embodiment) of inlets (supply ports) through which the combustion oxidant is supplied (supplied) from the base end to the front end. ing. In addition, the case where the insertion port is provided at the proximal end or the distal end is also included. In the present embodiment, only two stages of the inlets are provided, but three or more stages may be provided.

  As shown in FIG. 1, a combustion fuel supply pipe 47 branched from a fuel supply pipe 41 is connected to the main body 25a 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 combustion fuel supplied from the fuel supply source Sf and discharges it to the combustion unit 25, and adjusts the fuel supply amount for combustion according to a command from the control device 30. The main body 25a is connected to the other end of an off-gas supply pipe 72, one end of which is connected to the outlet of the fuel electrode 11, so that the reformed gas from the reformer 20 is modified during the start-up operation of the fuel cell 10. The anode off-gas supplied through the gas supply pipe 71, the bypass pipe 73 and the off-gas supply pipe 72 and discharged from the fuel cell 10 during the steady operation of the fuel cell 10 (reforms containing unused hydrogen at the fuel electrode 11). Quality gas) is supplied.

  Further, a first combustion air supply pipe 65 branched from the oxidation air supply pipe 61 is connected to the main body 25a upstream of the air pump 63 to burn the combustion fuel, reformed gas or anode off gas. Combustion air, which is a combustion oxidant gas, is supplied from the first stage inlet 25d1. A second combustion air supply pipe 85 branched from between the combustion air pump 66 of the first combustion air supply pipe 65 and the combustion section 25 is connected to the inlet 25c1 formed in the outer cylinder 25c of the combustion cylinder 25b. Combustion air, which is a combustion oxidant gas, is supplied from the second stage inlet 25d2. A combustion air pump 66 is provided in the first combustion air supply pipe 65, and a flow rate adjusting valve 86 (for example, a three-way proportional valve) is provided at a branch point with the second combustion air supply pipe 85. The combustion air pump 66 sucks the combustion air supplied from the air supply source Sa and discharges it to the combustion unit 25, and the total amount of combustion air supplied to the combustion unit 25 in accordance with a command from the control device 30. Is to adjust. The flow rate adjusting valve 86 adjusts each input amount (input ratio) input from the first stage input port 25d1 and the second stage input port 25d2 in accordance with a command from the control device 30.

  As described above, the first combustion air supply pipe 65, the second combustion air supply pipe 85, the combustion air pump 66, and the flow rate adjusting valve 86 are used for combustion independently and selectively with respect to the inlets of the respective stages. Combustion oxidant supply means capable of supplying oxidant is configured.

  In the combustion unit 25 configured as described above, when ignited by a command from the control device 30, the combustion fuel, reformed gas, or anode off gas supplied to the combustion unit 25 is input from the first stage input port 25d1. The combustion air or / and the combustion air introduced from the second stage inlet 25d2 are burned to generate high-temperature combustion gas.

  The combustion gas is folded back from the inner peripheral flow path 27a along the inner peripheral wall of the reforming section 21, the first outer peripheral flow path 27b along the outer peripheral wall of the reforming section 21 and the first outer peripheral flow path 27b. Then, the gas flows through the combustion gas flow path 27 constituted by the second outer peripheral flow path 27 c formed between the heat insulating portion 28 and the evaporation portion 26, and is exhausted as combustion exhaust gas through the exhaust pipe 81. That is, the combustion gas flow path 27 distributes the combustion gas generated in the combustion unit 25 in the order of the reforming unit 21 and the evaporation unit 26. The combustion gas passage 27 is covered with a heat insulating portion 28, and the heat of the combustion gas flowing through the inner peripheral flow passage 27a and the first outer peripheral flow passage 27b is suppressed from radiating to the outside by the heat insulating portion 28, so that the reforming portion. It is effectively used for heating 21.

  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. The combustion part 25 is connected to the outlet of the fuel electrode 11 via an off-gas supply pipe 72 so that anode off-gas discharged from the fuel cell 10 is supplied to the combustion part 25. 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 an off gas valve 75 between the junction with the bypass pipe 73 and the fuel cell 10. A second reformed gas valve 76 is provided in the bypass pipe 73. The first and second reformed gas valves 74 and 76 and the offgas valve 75 open and close the respective pipes and are controlled by the control device 30. During the start-up operation, the first reformed gas valve 74 and the offgas valve 75 are closed and the second reformed gas valve 76 is opened in order to avoid supplying reformed gas having a high carbon monoxide concentration from the reformer 20 to the fuel cell 10. During the steady operation (power generation operation), the first reformed gas valve 74 and the offgas valve 75 are opened and the second reformed gas valve 76 is closed in order to supply the reformed gas from the reformer 20 to the fuel cell 10. .

  The leading end of the cathode air supply pipe 67 branched from the first combustion air supply pipe 65 is connected to the inlet of the air electrode 12 of the fuel cell 10 upstream of the air pump 66. Air is supplied inside. 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 10, 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, the fuel cell system includes a control device 30. The control device 30 includes the temperature sensors 23e, 87, the pumps 43, 48, 53, 63, 66, 68, the valves 42, 45, 54, 64, 69, 74, 75, 76, the combustion section 25, and the flow rate adjusting valve 86 are connected (see FIG. 3). 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 inputs each temperature from each temperature sensor 23e, 87, and each pump 43, 48, 53, 63, 66, 68, each valve 42, 45, 54, 64, 69, 74, 75, 76, By controlling the combustion unit 25 and the flow rate adjustment valve 86, the start-up operation, the power generation operation, and the stop operation of the fuel cell system are performed. The RAM temporarily stores variables necessary for executing the program, and the ROM stores the program.

  The operation of the above-described fuel cell system will be described with reference to the flowchart of FIG. 4 and the time chart of FIG. When a start switch (not shown) is turned on at time t0, the control device 30 starts a warm-up operation (start-up operation) for warming up the fuel cell system. That is, the supply of combustion fuel and combustion air to the combustion unit 25 is started (ignition) to ignite the combustion unit 25 to start generation of combustion gas, and the reforming unit 21 is supplied with reforming water (steam). Start charging.

  Specifically, in step 102, the control device 30 controls the flow rate adjusting valve 86 so as to input combustion air only from the first stage input port 25d1. And the combustion air pump 66 is driven so that it may become predetermined supply amount A1-1. As a result, the combustion air of a predetermined supply amount (predetermined flow rate) A1-1 is supplied (introduced) into the combustion cylinder 25b through the first stage input port 25d1.

  In step 104, the control device 30 opens the first fuel valve 42, closes the second fuel valve 45, and connects the fuel supply source Sf only to the combustion unit 25. Further, the control device 30 drives the combustion fuel pump 48 so that the predetermined supply amount Mf1 is obtained. As a result, the combustion fuel of the predetermined supply amount Mf1 is supplied from the fuel supply source Sf to the combustion unit 25 through the combustion fuel supply pipe 47. Furthermore, since the control device 30 ignites the combustion section 25, combustion of the combustion fuel supplied as described above by the combustion air is started.

  In step 106, the control device 30 opens the water valve 54, drives the water pump 53 to reach the predetermined supply amount Mw 1, and supplies the reforming water (water or steam) to the reforming unit 21 via the evaporation unit 26. Start charging.

  Then, in step 108, control device 30 waits for timer Tm1 to elapse from time t0 and advances the program to step 110. As the timer Tm1, for example, a time during which the flame is stabilized after ignition is measured in advance, and the time is set. Instead of using the timer Tm1, the flame temperature or a factor related to the same temperature may be measured, and when it reaches a predetermined value, it may be determined that the flame has stabilized, and the program may proceed to step 110. In step 110, the control device 30 controls the flow rate adjusting valve 86 so as to input combustion air from both the first stage inlet 25d1 and the second stage inlet 25d2. Further, the control device 30 controls the flow rate adjusting valve 86 and the combustion air pump 66 to maintain the combustion fuel from the first stage inlet 25d1 at a predetermined supply amount (predetermined flow rate) A1-1, and The fuel for combustion from the two-stage inlet 25d2 is adjusted to a predetermined supply amount (predetermined flow rate) A2-1.

  The predetermined supply amount A1-1 and the predetermined supply amount A2-1 are respectively determined based on the combustion characteristics (emission, blow-off prevention condition) according to the operation mode. The predetermined supply amount A2-1 is set to be larger than the predetermined supply amount A1-1. That is, in the first start-up operation mode from the time t1 to the time point when the vaporizer 26 starts generating steam (time t2) from the time t1, the input port (second stage input) located on the tip side of the combustion cylinder 25b. The amount of combustion oxidant input A2-1 from the port 25d2) is greater than the amount of combustion oxidant input A1-1 from the input port (first stage input port 25d1) located on the base end side of the combustion cylinder 25b. It is set to increase. The predetermined supply amount A1-1 is set to an amount that keeps the emission as low as possible and the flame is not blown out. The predetermined supply amount A2-1 increases the flow rate of the combustion gas to increase the efficiency of the heat of the combustion gas. It is set to an amount that can be well transmitted to the evaporator 26.

  Therefore, during the period from time t1 to time t2 (steam generation start time), the second stage charging is performed without blowing off the combustion fire of the combustion section 25 by the combustion with the combustion air supplied from the first stage charging port 25d1. The flow rate of the combustion gas is increased from the second stage inlet 25d2 by the combustion air supplied from the inlet 25d2. Therefore, the combustion gas temperature is set to a temperature required by the evaporation unit 26, and the combustion gas flow rate is increased, whereby heat can be efficiently applied to the evaporation unit 26 and water vapor can be generated at an early stage.

  Note that the timer Tm1 may be set to 0, and in this case, the first start-up operation mode is from time t0 to time t2.

  Thus, while the reforming unit 21 and the evaporation unit 26 are heated and heated by the combustion gas, the reforming water is heated by the evaporation unit 26. After the evaporation section 26 is sufficiently heated, the reformed water boils and is supplied to the cooling section 22 in a gaseous state, that is, a steam or gas-liquid mixed state.

  In step 112, the control device 30 detects the temperature T1 of the reforming water flowing out from the evaporator 26 by the temperature sensor 87, and determines whether or not the detected temperature T1 is higher than a predetermined temperature T1a (for example, 100 ° C.). To do. When the temperature T1 of the reforming water is lower than the predetermined temperature T1a, the control device 30 determines “NO” and repeatedly executes the process of step 112, and the temperature T1 of the reforming water becomes equal to or higher than the predetermined temperature T1a. If YES, the determination is “YES” and the program proceeds to step 114. The predetermined temperature T1a is set to a temperature at which the reformed water is generated as water vapor.

  Therefore, when the temperature T1 becomes higher than the predetermined temperature T1a, the control device 30 determines that water vapor starts to be generated from the evaporation unit 26, and starts supplying reforming fuel in step 114. Specifically, the control device 30 opens the second fuel valve 45 and drives the fuel pump 43 so as to reach the predetermined supply amount Mf2, and starts to supply the reforming fuel to the reforming unit 21. Further, the air valve 64 is opened to connect the air supply source Sa to the CO selective oxidation unit 24 and the air pump 63 is driven to supply the air from the air supply source Sa to the CO selective oxidation unit 24 by a predetermined flow rate (predetermined supply amount). To do. Thus, the reformed fuel and steam mixed gas are supplied to the reforming unit 21, and the reforming unit 21 generates the reformed gas by causing the steam reforming reaction and the carbon monoxide shift reaction described above. The reformed gas derived from the reforming unit 21 is reduced in carbon monoxide gas by the CO shift unit 23 and the CO selective oxidizing unit 24 and derived from the CO selective oxidizing unit 24, and bypassed without passing through the fuel cell 10. It is directly supplied to the combustion section 25 through the pipe 73 and burned. Further, the CO shift unit 23 and the CO selective oxidation unit 24 are warmed up by the reformed gas derived from the reforming unit 21. With this control, the reforming raw material is supplied after the water vapor has been reliably supplied, so that coking of the reforming catalyst can be prevented and the durability of the reforming apparatus can be improved.

  Further, in step 116, the control device 30 sets each supply amount of combustion air from the first stage inlet 25d1 and the second stage inlet 25d2. Specifically, in step 116, the control device 30 controls the flow rate adjusting valve 86 and the combustion air pump 66 to supply the combustion fuel from the first stage inlet 25d1 to a predetermined supply amount (predetermined flow rate) A1-. 2 and the combustion fuel from the second stage inlet 25d2 is reduced to a predetermined supply amount (predetermined flow rate) A2-2.

  The predetermined supply amount A1-2 and the predetermined supply amount A2-2 are respectively determined based on the combustion characteristics (emission, blow-off prevention conditions) corresponding to the operation mode. Further, since the reformed gas that does not pass through the fuel cell 10 is combusted in the combustion unit 25, the combustion amount is excessive with respect to the amount of heat necessary for the reforming unit 21. The predetermined supply amount A1-2 and the predetermined supply amount A2-2 are set in consideration of suppressing the overheating of the reforming unit 21 due to the excessive combustion. The predetermined supply amount A1-2 and the predetermined supply amount A2-2 are set to such amounts that the emission can be suppressed as low as possible, the flame is not blown out, and the heat of the combustion gas can be efficiently transmitted to the reforming unit 21. ing. That is, when the operation mode is the second start-up operation mode after time t2, the amount of combustion oxidant input A2-2 from the input port (second stage input port 25d2) located on the tip side of the combustion cylinder 25b is It is set so as to be smaller than the charging amount A2-1 of the combustion oxidant from the second stage charging port 25d2 in the first start-up operation mode.

  Therefore, the flow rate of the combustion gas is reduced between time t2 and time t3 after the steam is generated early compared to before time t2. By reducing the flow velocity of the combustion gas, the combustion gas temperature is set to an optimum temperature for warming up the reforming unit 21. Thereby, heat can be efficiently transmitted to the reforming unit 21, and then moderate heat can be transmitted to the evaporation unit 26.

  In step 118, the control device 30 determines whether or not the warming up of the reforming device 20 is completed. That is, it is determined whether or not the temperature T2 of the CO shift unit 23 detected by the temperature sensor 23e is equal to or higher than the predetermined temperature T2a. When the temperature T2 of the CO shift unit 23 is lower than the predetermined temperature T2a, it is determined as “NO”, and the process of step 118 is repeatedly executed. When temperature T2 of CO shift unit 23 becomes equal to or higher than predetermined temperature T2a (time t3), control device 30 determines “YES” in step 122 and advances the program to step 120.

  In step 120, the control device 30 performs a warm-up end process. Specifically, the control device 30 opens the first reformed gas valve 74 and the off-gas valve 75 and closes the second reformed gas valve 76 to connect the CO selective oxidation unit 24 to the inlet of the fuel electrode 11 of the fuel cell 10. At the same time, the outlet of the fuel electrode 11 is connected to the combustion section 25. As a result, the reformed gas with reduced carbon monoxide derived from the CO selective oxidation unit 24 is supplied to the fuel electrode 11 and used for power generation. The anode off gas from the fuel electrode 11 is supplied to the combustion unit 25 and burned. That is, the start-up operation is terminated, and then the steady operation (power generation operation) is started.

  In step 122, the control device 30 performs a power generation operation (steady operation). During the power generation operation (power generation operation mode), the control device 30 is configured so that the amount of hydrogen generated by the reformer 20 becomes a predetermined amount, that is, the current / power consumed by the output current of the fuel cell system at the place where the power is used. The reforming fuel, the combustion fuel, the combustion air, the oxidizing air, the cathode air, and the reforming water are supplied so as to obtain a desired output current determined based on the above.

  During the power generation operation, as described above, the anode 25 offgas from the fuel cell 10 is supplied to the combustion unit 25, and unused hydrogen gas and unreformed fuel in the anode offgas are burned and modified by the heat. The mass part 21 is heated. However, when the amount of heat necessary for the reforming unit 21 cannot be compensated only by the combustion heat of the anode off gas, the fuel for combustion is introduced and burned to replenish the insufficient amount of heat. In addition, it is good also as a structure which can supply the required calorie | heat amount to the reforming part 21 only by combustion of anode off gas, without reheating of such a fuel for combustion.

  The supply amount of the combustion air will be described in detail. The control device 30 sets each supply amount of the combustion air from the first stage inlet 25d1 and the second stage inlet 25d2. Specifically, the control device 30 controls the flow rate adjusting valve 86 and the combustion air pump 66 to set the combustion fuel from the first stage inlet 25d1 to a predetermined supply amount (predetermined flow rate) A1-3. At the same time, the combustion fuel from the second stage inlet 25d2 is set to a predetermined supply amount (predetermined flow rate) A2-3.

  The predetermined supply amount A1-3 is a value determined based on the current / power consumed at the place where the power is used. This predetermined supply amount A1-3 is set so as to obtain heat necessary for generating hydrogen at high efficiency in the reforming section 21 by efficient combustion. The predetermined supply amount A2-3 is set to 0 (zero). That is, the supply of combustion air from the second stage inlet 25d2 is stopped.

  During the power generation operation, the combustion unit 25 is easily blown off when the power generation amount is low (for example, when the power generation amount is minimum) or when the power generation amount increases. This is because when the amount of power generation is low, the accuracy of each pump and the degree of influence due to pulsation are greatly blown out, and when the amount of power generation increases, the anode off-gas is greater than the required heat amount of the reforming unit 21. This is because it will be easy to blow out due to the delay in the return time. In such a case, it is desirable that the predetermined supply amount A2-3 is not set to 0 (zero) as described above, but is set to the second predetermined flow rate L2 that is low emission. In this case, it is desirable that the predetermined supply amount A1-3 be set to the first predetermined flow rate L1 such that the combustion at the first stage inlet 25d1 becomes fuel rich. The total flow rate of the first predetermined flow rate L1 and the second predetermined flow rate L2 is set so as to obtain heat necessary for generating hydrogen with high efficiency in the reforming unit 21 by efficient combustion. Thereby, it becomes difficult to blow out by performing fuel rich combustion at the first stage inlet 25d1. Further, the combustion gas burned with fuel rich at the first stage inlet 25d1 can be reduced in emissions by combustion at the second stage inlet 25d2. Each predetermined supply amount, input amount and each predetermined flow rate described above are flow rates.

  The control device 30 continues to determine the “NO” in step 124 and continue the power generation operation until there is an operation stop instruction such as pressing the stop switch. If there is an operation stop instruction, “YES” is determined in step 124, and the program is advanced to step 126 to stop the operation of the fuel cell system.

  In step 126, the control device 30 performs a system stop process. At this time, a purge process is performed on the fuel electrode side of the fuel cell 10 to reduce the hydrogen concentration to zero. As this purge process, a method of expelling the fuel gas with a purge gas such as an inert gas, air or combustion exhaust gas, a method of reducing the hydrogen concentration by sending an air to oxidize, and applying a voltage to the fuel cell 10 while circulating water vapor There is a method of transporting the hydrogen of the fuel electrode 11 to the oxidant electrode 12 to reduce the hydrogen concentration. In any method, the fuel electrode 11 stops the system with residual gas having a low hydrogen concentration remaining.

  In addition, each process of step 104,110,116,120 mentioned above is a control means.

  As is apparent from the above description, in this embodiment, the first combustion air supply pipe 65, the second combustion air supply pipe 85, the combustion air pump 66, and the flow rate adjusting valve 86 are used for combustion. The oxidant supply means can supply the oxidant for combustion independently and selectively to the input ports 25d1 and 25d2 of the respective stages arranged from the base end to the front end of the combustion cylinder 25b. In addition, the control means (control device 30; steps 104, 110, 116, 120) sets the respective amounts of the combustion oxidant input from the input ports 25d1, 25d2 of the respective stages according to the operation mode. The oxidant supply means for combustion is controlled so as to obtain the above value. Thereby, the input amount (supply amount) of the combustion oxidant input from the input ports 25d1 and 25d2 of each stage can be controlled independently and selectively according to the operation mode. Therefore, the combustion unit 25 can perform appropriate combustion in each operation mode.

  Further, in the first startup operation mode in which the operation mode is from the start time t0 to the time t2 at which the generation of water vapor is started in the evaporation unit 26, the second stage input port which is an input port located on the tip side of the combustion cylinder 25b. Since the amount of combustion oxidant input from 25d2 is set to be larger than the amount of combustion oxidant input from the first stage input port 25d1, which is the input port located on the base end side of the combustion cylinder 25b. By increasing the flow rate of the combustion gas without causing it to blow out and causing the combustion gas to reach the evaporation unit 26 quickly, the heat of the combustion gas can be efficiently transmitted to the evaporation unit 26. Therefore, the evaporation part 26 is heated early by combustion gas, water vapor | steam can be produced | generated early, and a warming-up time can be shortened by extension.

  In addition, in the second start-up operation mode from the time point t2 at which the evaporation unit 26 starts generating water vapor to the time point t3 at which the power generation operation of the fuel cell 10 is started, the input is positioned on the front end side of the combustion cylinder 25b. Since the amount of combustion oxidant input from the second stage input port 25d2 is set to be smaller than that in the first start-up operation mode, the flow rate of the combustion gas is reduced after the water vapor is generated. It is possible to reduce the temperature of the combustion gas so that the temperature of the combustion gas is optimal for warming up the reforming unit 21, and to efficiently transfer the heat of the combustion gas to the reforming unit 21. Therefore, the reforming part 21 can be heated early with the combustion gas, and as a result, the warm-up time can be shortened.

  In addition, although it is necessary to give heat to the evaporation part 26 from combustion gas at an early stage until water vapor | steam production | generation, as a temperature of combustion gas, high temperature like the time of operation is not required (If heat exchange efficiency is not considered, If it only creates water vapor, it should have a temperature of 100 ° C. or higher). Therefore, in the present invention, by introducing a combustion oxidant from the tip of the combustion cylinder 25b, steam generation is accelerated by circulating a large flow of combustion gas even at a relatively low temperature. On the other hand, at the time of power generation after the generation of steam, it is necessary to maintain the temperature of the reforming section 21 at a high temperature such as 700 ° C. in order to perform a reforming reaction with reforming fuel and steam. Therefore, it is necessary to make the temperature of the combustion gas also high. In the present invention, the combustion gas temperature is raised by reducing (including stopping) the injection of the combustion oxidant from the tip of the combustion cylinder 25b.

  Further, when the operation mode is the power generation operation mode and the output power of the fuel cell 10 is low or increased, the first input port located on the base end side of the combustion cylinder 25b is used. The input amount of the combustion oxidant from the stage input port 25d1 is set to the first predetermined flow rate L1 at which fuel-rich combustion is performed, and from the second stage input port 25d2 that is an input port located on the front end side of the combustion cylinder 25b. Since the amount of combustion oxidant input is set to the second predetermined flow rate L2 at which low emission is achieved, blow-off can be reliably prevented and low emission can be realized.

  In each of the above-described embodiments, the combustion oxidant supply means is constituted by the first combustion air supply pipe 65, the second combustion air supply pipe 85, the combustion air pump 66, and the flow rate adjusting valve 86. However, instead of providing the flow rate adjusting valve 86, a combustion air pump 85a may be provided in the second combustion air supply pipe 85 as shown in FIG. In this case, the combustion air pump 85a sucks air supplied from the air supply source Sa and discharges it to the combustion cylinder 25b, and adjusts the combustion air supply amount in accordance with a command from the control device 30. . The amount of combustion oxidant charged from the first stage inlet 25d1 and second stage inlet 25d2 is adjusted by controlling both combustion air pumps 66, 85a.

  The second combustion air supply pipe 85 may be branched from the first combustion air supply pipe 65 upstream of the combustion air pump 66.

  Moreover, in each embodiment mentioned above, you may make it use a blower instead of a pump.

1 is a schematic diagram showing an outline of an embodiment of a fuel cell system to which a reformer according to the present invention is applied. It is a figure which shows the cross section of the combustion part shown in FIG. 1, and its periphery. It is a block diagram which shows the reforming apparatus shown in FIG. 4 is a flowchart of a control program executed by the control device shown in FIG. 3. It is a time chart which shows operation | movement of the reforming apparatus by this invention. It is a figure which shows the modification of the cross section of the combustion part shown in FIG. 1, and its periphery.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Fuel electrode, 12 ... Air electrode, 20 ... Reformer, 21 ... Reformer, 22 ... Cooling part (heat exchange part), 23 ... Carbon monoxide shift reaction part (CO shift part) , 23e ... temperature sensor, 24 ... carbon monoxide selective oxidation reaction part (CO selective oxidation part), 25 ... combustion part, 25a ... main body, 25b ... combustion cylinder, 25c ... outer cylinder, 25d ... inner cylinder, 25d1 ... first Stage input port, 25d2 ... Second stage input port, 26 ... Evaporation section, 27 ... Combustion gas flow path, 28 ... Heat insulation section, 30 ... Control device (control means), 41 ... Fuel supply pipe, 42 ... First fuel valve , 43 ... Fuel pump, 44 ... Desulfurizer, 45 ... Second fuel valve, 47 ... Fuel supply pipe for combustion, 48 ... Fuel pump for combustion, 51 ... Water supply pipe, 52 ... Water supply pipe, 53 ... Water pump, 54 ... Water valve, 61 ... Oxidation air supply pipe, 62 ... Filter, 63 ... Air pump, 64 ... air valve, 65 ... first combustion air supply pipe, 66, 85a ... combustion air pump, 67 ... cathode air supply pipe, 68 ... cathode air pump, 69 ... cathode air valve, 71 ... reformed gas supply pipe, 72 ... off gas supply pipe, 73 ... bypass pipe, 74 ... first reformed gas valve, 75 ... off gas valve, 76 ... second reformed gas valve, 81, 82 ... exhaust pipe, 85 ... second Combustion air supply pipe, 86 ... Flow rate adjusting valve, 87 ... Temperature sensor, 89 ... Connection pipe, Sa ... Air supply source, Sf ... Fuel supply source, Sw ... Water tank.

Claims (4)

In a reformer having a combustion section that burns combustion fuel that is put into a combustion cylinder with a combustion oxidant that is supplied from a plurality of stages provided in the combustion cylinder to generate combustion gas,
The inlet of each stage is arranged along the tip from the base end of the combustion cylinder,
Combustion oxidant supply means capable of supplying the combustion oxidant independently and selectively to the inlet of each stage;
Control means for controlling the combustion oxidant supply means such that each amount of the combustion oxidant charged from each stage inlet is set to a value set in accordance with an operation mode; A reformer characterized by further comprising: The reforming unit according to claim 1, wherein a reforming unit that generates reformed gas from the supplied reforming fuel and steam and supplies the reformed gas to the fuel cell;
An evaporation section that generates the water vapor from the supplied reforming water and leads the steam to the reforming section;
A combustion gas flow path for allowing the combustion gas generated in the combustion section to flow in the order of the reforming section and the evaporation section,
The operation mode has a first start-up operation mode from the start-up time of the reformer to the time when the steam generation is started in the evaporation unit,
In the first start-up operation mode, the amount of the oxidant for combustion from the inlet located on the leading end side of the combustion cylinder is such that the amount of the oxidant for combustion from the inlet located on the proximal end side of the combustion cylinder is A reformer characterized in that it is set to be larger than the input amount. In Claim 1 or Claim 2, the said operation mode has the 2nd starting operation mode after the time of starting the production of the water vapor in the evaporation part,
In the second start-up operation mode, the amount of the oxidant for combustion from the input port located on the proximal end side of the combustion cylinder is the amount of the oxidant for combustion from the input port located on the distal end side of the combustion cylinder. A reformer characterized in that it is set to be larger than the input amount. A fuel cell system comprising: the reformer according to claim 1; and a fuel cell that generates electric power using the reformed gas supplied from the reformer.
When the operation mode is the power generation operation mode and the output power of the fuel cell is low or increases, the combustion oxidant from the inlet located on the base end side of the combustion cylinder Is set at a first predetermined flow rate at which fuel-rich combustion is achieved, and at a second predetermined flow rate at which the input amount of the combustion oxidant from the input port located on the front end side of the combustion cylinder is low. A fuel cell system characterized by being set.

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