JP2005310765A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system switching starting operation to normal operation without increasing the density of a carbon monoxide contained in reformed gas drawn out from a reforming device. <P>SOLUTION: First to third ports of a lead-in side three-way valve are connected to a reformed gas exhaustion port, a reformed gas lead-in port of the fuel cell, and a burner of a combustion part, respectively. The three-way valve shuts a the second port by making the first port communicate with the third port at the starting operation, gradually increases a communicating area between the first port and the second port, and gradually decreases a communication area between the first port and the third port when switching the starting operation to the normal operation, shuts the third port by making the first port communicate with the second port at the normal operation, and shuts the mutual communication of every ports at stopping. By this, when switching the starting operation to the normal operation, the reformed gas is prevented from being suctioned into the fuel cell of which the pressure is turned into negative pressure at stopping, and the stable state of the reforming device is not disturbed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates a reformed gas from supplied reforming fuel and steam and supplies the reformed gas and air to a fuel cell to generate electric power.

  In Patent Document 1, as shown in FIG. 1, methanol and water are heated and evaporated by an evaporator 13 using combustion gas generated in the combustion section 11, and the reformed catalyst is filled with the evaporated methanol and water vapor. The reforming unit 3 performs steam reforming to a so-called hydrogen-rich reformed gas, and carbon monoxide contained in the reformed gas is converted into a shift reaction unit 5 and a selective oxidation reaction unit 7 (hereinafter referred to as a CO selective oxidation unit 7). The excess reformed gas derived from the fuel cell 9 (hereinafter referred to as anode off gas) is generated by supplying the reformed gas from the CO selective oxidation unit 7 and the air from the compressor to the fuel cell 9 to generate power. In the fuel cell system in which the fuel is sent to the combustion unit 11 and combusted, the first flow rate control valve 17 is provided between the reformed gas delivery port of the CO selective oxidation unit 7 and the fuel cell 9, and the modification of the CO selective oxidation unit 7 is performed. Quality gas outlet The fuel cell system is disclosed in which between the inlet of the tempering unit 11 and the second flow rate control valve 19 was bypassed by the bypass circuit 15 connected. In this fuel cell system, during normal operation, the first flow rate control valve 17 is opened, the second flow rate control valve 19 is closed, and all the reformed gas coming out of the CO selective oxidation unit 7 is sent to the fuel cell 9. However, when the load increases during acceleration or the like, the second flow rate control valve 19 is opened to reduce the supply amount of the reformed gas to the fuel cell 9 and take out the power from the fuel cell (power generation amount). By temporarily limiting and bypassing the reformed gas for that amount to the combustion unit 11, the amount of heat generated in the combustion unit 11 is increased to increase the evaporation amount of methanol and water, and the responsiveness of the reformer 1 is increased. It has improved.

However, in the fuel cell system described in Patent Document 1, since a valve is not provided between the anode offgas outlet for extracting the anode offgas of the fuel cell 9 and the combustion unit 11, the fuel cell system from the combustion unit 11 after the operation is completed. Air may enter the anode electrode of the fuel cell 9 and oxidize the anode electrode. For this reason, as shown in FIG. 7, the first valve 21 is provided between the reformed gas delivery port of the CO selective oxidation unit 7 and the fuel cell 9, and the delivery port of the CO selective oxidation unit 7 and the combustion unit 11 are provided. A bypass circuit 24 to which a second valve 22 is connected is bypassed between the inlet and the third valve on the upstream side of the connection point of the bypass circuit 24 between the anode off-gas outlet of the fuel cell 9 and the combustion unit 11. 23 is performed. In such a conventional apparatus, the first and third valves 21 and 23 are closed during the start-up operation and the second valve 22 is opened, thereby bypassing the fuel cell 9 with the reformed gas having a high carbon monoxide concentration at the start-up. It is sent to the combustion section 11 and burned. Thereby, carbon monoxide contained in the reformed gas during start-up operation is prevented from poisoning the anode electrode of the fuel cell 9. During normal operation, the reformed gas is introduced into the fuel cell 9 by opening the first and third valves 21 and 23 and closing the second valve 22. At the time of stoppage, the first to third valves 21 to 23 are closed to block the air from entering the fuel cell 9 and the reforming device 3 from the combustion unit 11, and the durability due to the oxidative deterioration of the anode electrode and the reforming catalyst.・ Prevents performance degradation.
Japanese Patent Laid-Open No. 2001-23659 (page 3, FIG. 1)

   In the fuel cell system shown in FIG. 7, the first and third valves 21 are the reformed gas inlet for introducing the reformed gas into the anode electrode of the fuel cell 9 and the anode offgas outlet for extracting the anode offgas from the anode electrode when stopped. , 23, the pressure in the fuel cell 9 is reduced by cooling the sealed gas. In this state, the first and third valves 21 and 23 are closed, the second valve 22 is opened, and the starting operation is started. That is, the combustion fuel gas is burned by the burner of the combustion unit 11, the generated combustion gas heats the catalyst in the reforming unit 3, and steam is generated by the evaporator 13. Subsequently, the reforming fuel gas and steam are mixed and supplied to the reforming unit 3, and the reformed gas is generated by the steam reforming reaction and the carbon monoxide shift reaction by the catalyst. The reformed gas derived from the reforming unit 3 is reduced in carbon monoxide gas by the CO shift unit 5 and the CO selective oxidation unit 7. During the start-up operation in which the concentration of carbon monoxide gas contained in the reformed gas delivered from the CO selective oxidation unit 7 is higher than a predetermined value, the reformed gas delivered from the CO selective oxidation unit 7 passes through the bypass circuit 24. Burned in the combustion section 11. When the system becomes stable and the concentration of carbon monoxide gas contained in the reformed gas sent from the CO selective oxidation unit 7 has decreased to a predetermined value or less, the catalyst temperature of the CO selective oxidation unit 7 exceeds the predetermined value. Is detected, the first and third valves 21 and 23 are opened, the second valve is closed, and the normal operation is started. However, the pressure in the fuel cell 9 is lowered by cooling the enclosed gas while it is stopped, and is lower than the pressure at the outlet of the CO selective oxidation unit 7 during the start-up operation. Is suddenly opened, a large amount of reformed gas is sucked into the fuel cell 9 from the CO selective oxidation unit 7, the stable state of the system is broken, and the carbon monoxide gas of the reformed gas sent from the CO selective oxidation unit 7 The problem arises that the concentration increases.

   Further, the first to third valves 21 to 23 used in the fuel cell system shown in FIG. 7 press the valve body against the valve seat by the spring force of the compression spring to close the valve hole and close the valve. Since the valve body is opened by opening the valve against the spring force against the spring force by the magnetic force, the closing performance from the outlet side to the inlet side is poor, and the CO selective oxidation unit 7 and the fuel cell 9 are stopped after stopping. When the internal pressure becomes negative due to cooling, the air from the combustion unit 11 connected to the outlet side separates the valve body from the valve seat against the spring force, and the second and third valves 22 and 23. And then enters the fuel cell 9 and the reformer 1 to oxidize the anode electrode and the reforming catalyst. Further, during normal operation, the solenoids of the first and third valves 21 and 23 must be urged against the spring force, which increases power consumption.

   The present invention has been made in order to solve the above-described problems, and the fuel cell system is normally operated from the start-up operation without increasing the concentration of carbon monoxide gas contained in the reformed gas derived from the reformer. It is to switch to driving.

  In order to solve the above-described problem, the structural feature of the invention according to claim 1 includes a reformer that generates a reformed gas using a catalyst heated by the combustion gas generated in the combustion section. The reformed gas inlet of the reformer is connected to the reformed gas inlet for introducing the reformed gas into the anode electrode, and the combustion section is connected to the anode offgas outlet for extracting the anode offgas from the anode electrode. In the fuel cell system, the first to third ports include a reformed gas delivery port of the reformer, a reformed gas inlet of the fuel cell, and an inlet side three-way valve connected to a burner of the combustion unit. The first port communicates with the third port during the start-up operation, the second port is closed, and the communication area between the first port and the second port is gradually increased in the switching from the start-up operation to the normal operation. Port and Gradually decreases the area of communication between the third port, the third port is closed communicating the first port to the second port during normal operation, it is to cut off all communication between the ports during shutdown.

  The structural feature of the invention according to claim 2 is that, in claim 1, the first to third ports of the outlet side three-way valve are the burner of the combustion section, the anode off-gas outlet port, and the inlet side three-way valve. The derivation side three-way valve is connected to each of the third ports, and communicates the first port with the third port during the start-up operation and closes the second port. When switching from the start-up operation to the normal operation, the first port The communication area between the first port and the second port is gradually increased, and the communication area between the first port and the third port is gradually decreased. In normal operation, the first port is connected to the second port, and the third port is connected. It is closed and all communication between each port is cut off when the operation is stopped.

  The structural feature of the invention according to claim 3 is that, in claim 1, the third port of the introduction-side three-way valve is connected to the burner of the combustion section through a warm-up section, and the anode off-gas outlet port is It is connected to the burner of the combustion section through a valve that is closed when the operation is stopped.

  The structural feature of the invention according to claim 4 is the three-way ball according to any one of claims 1 to 3, wherein the introduction-side and lead-out-side three-way valves are configured to rotate a ball-shaped valve element by an actuator. It is a valve.

  A structural feature of the invention according to claim 5 is that, in any one of claims 1 to 4, the introduction side and outlet side three-way valves are closed positions that block all communication between the ports when the power is shut off. And an emergency shut-off device for switching the valve body.

   In the invention according to claim 1 configured as described above, when the start-up operation is switched to the normal operation, the reformed gas delivery port of the reformer and the reformed gas introduction of the fuel cell are introduced by the operation of the introduction side three-way valve. The communication area between the inlet and the outlet is gradually increased, and the communication area between the reformer gas outlet of the reformer and the burner in the combustion section is gradually reduced and shut off. A large amount of reformed gas is not suddenly sucked. As a result, a large amount of the reformed gas is suddenly sucked into the fuel cell from the reformer, the stable state of the reformer is broken, and the concentration of carbon monoxide gas contained in the reformed gas increases. It is possible to prevent the anode electrode from being poisoned. Furthermore, the flow of the reformed gas sent from the reformer to the burner via the introduction side three-way valve and the anode off-gas sent from the anode off-gas outlet to the burner do not stop at the same time, and burner misfire or non-combustion is prevented. Increase in emission due to stability can be suppressed.

  In the invention according to claim 2 configured as described above, when the start-up operation is switched to the normal operation, the reformed gas delivery port of the reformer and the reformed gas introduction of the fuel cell are introduced by the operation of the introduction side three-way valve. The communication area between the outlet is gradually increased, the communication area between the reforming gas delivery port of the reformer and the outlet side three-way valve is gradually decreased, and the operation of the outlet side three-way valve causes the anode off-gas outlet port to Since the communication area between the burner in the combustion section is gradually increased and the communication area between the three-way valve on the introduction side and the burner in the combustion section is gradually reduced and shut off, the fuel cell that is negative pressure when stopped The reformed gas is not suddenly sucked. As a result, a large amount of the reformed gas is suddenly sucked into the fuel cell from the reformer, the stable state of the reformer is broken, and the concentration of carbon monoxide gas contained in the reformed gas increases. It is possible to prevent the anode electrode from being poisoned. Then, the reformed gas sent from the reformer to the burner of the combustion section through the inlet side and outlet side three-way valve is gradually changed into the anode off gas sent from the anode off gas outlet to the burner via the outlet side three-way valve. Therefore, it is possible to suppress an increase in emission due to burner misfire or combustion instability.

  In the invention according to claim 3 configured as described above, since the reformed gas is sent from the reformer to the burner of the combustion section through the warm-up section at the start-up operation, the number of valves used is simple. According to the configuration, in addition to the effect exhibited by the invention according to claim 1, it is possible to easily raise the temperature of a portion that requires a temperature increase during the start-up operation. Further, since the anode off-gas outlet is closed by a valve when the operation is stopped, air can be prevented from entering the fuel cell during the stop.

  In the invention according to claim 4 configured as described above, the introduction-side and outlet-side three-way valves are configured by simple three-way ball valves, and therefore, the fuel cell system is less likely to have foreign matter caught in the valves. It is possible to smoothly and reliably switch to each operation state. The three-way ball valve has a configuration in which the ball-shaped valve body is rotated by an actuator, so that the closing performance from the outlet side to the inlet side is good, and the reformer and the fuel cell are cooled after the stop so that the internal pressure is negative. Even in this case, air does not enter the fuel cell and the reformer from the combustion section connected to the outlet side, and the anode electrode and the reforming catalyst can be reliably prevented from being oxidized.

  Furthermore, the three-way ball valve can maintain the ball valve body at a predetermined rotational phase position with low power consumption during normal operation, and can improve power generation efficiency.

   In the invention according to claim 5 configured as described above, the introduction-side and outlet-side three-way valves prevent all communication between the ports from being interrupted by the emergency shut-off device when the power is shut off such as a power failure. It is possible to prevent the electrodes and the catalyst of the reformer from being in contact with the invading air and being oxidized.

  Hereinafter, a first embodiment of a fuel cell system according to the present invention will be described. As shown in FIG. 1, the fuel cell system 10 includes a fuel cell 11 and a reformer 12 that generates and supplies hydrogen gas necessary for the fuel cell 11. The reformed gas is supplied from the reformer 12 to the anode electrode of the fuel cell 11, and air from the outside is supplied to the cathode electrode of the fuel cell 11 by an air pump. The gas and oxygen gas in the air react to generate power.

  The reformer 12 evaporates pure water supplied from a reforming unit 13 that generates a reformed gas by supplying a hydrocarbon-based reforming fuel gas such as natural gas or LPG and water vapor, and a water pump. An evaporator 15 that generates water vapor to be supplied to the reforming unit 13, a combustion unit 14 that generates combustion gas for heating the reforming unit 13 and the evaporator 15 by mixing and burning combustion fuel gas and combustion air. The carbon monoxide contained in the reformed gas stacked in the lower part of the reforming unit 13 and generated in the reforming unit 13 and cooled in the heat exchanging unit 16 is stacked in the lower part of the heat exchanging unit 16. A carbon monoxide shift reaction section (hereinafter referred to as a CO shift section) 17 to be removed, and carbon monoxide contained in the reformed gas sent from the CO shift section 17 connected to the CO shift section 17 is further removed to send out the outlet. Acid supplied to the fuel cell 11 from Carbon selective oxidation unit (hereinafter, referred to as the CO selective oxidizing unit.) 18 and a. The outlet of the CO selective oxidation unit 18 becomes the reformed gas outlet 46 of the reformer 12. The reformed gas introduced into the anode electrode from the reformed gas inlet 47 of the fuel cell 11 reacts with the oxygen gas in the air introduced into the cathode electrode to generate power and become water, but it is an excess reformed gas. A certain anode off gas is sent from the anode off gas outlet of the fuel cell 11 to the combustion section 14 and burned.

  The reaction chamber 19 filled with the catalyst of the reforming unit 13 is surrounded by the heating chamber 20 of the combustion unit 14 at the top and outer periphery, and the burner 21 provided in the heating chamber 20 is a combustion fuel sent by a gas pump. The gas and combustion air sent by the air pump are mixed and burned to generate combustion gas. The combustion gas heats the catalyst in the reaction chamber 19 while flowing through the heating chamber 20, and then flows into the evaporator 15 to evaporate pure water. The reforming fuel gas pumped by the gas pump 22 and the water vapor generated by the evaporator 15 are mixed and introduced into the heat exchanging unit 16, preheated by the heat exchanging unit 16 and supplied to the reaction chamber 19 for combustion. A reformed gas is generated by a steam reforming reaction and a carbon monoxide shift reaction by a catalyst heated by the gas.

   The common port 33C of the introduction-side three-way valve 24 connected between the reformer 12 and the fuel cell 11 is a first port to the reformed gas delivery port 46 of the reformer 12, and the port 34A is a second port. As described above, the reformed gas inlet 47 of the fuel cell 11 and the port 34B are connected to the bypass 26 as a third port. The bypass passage 26 is for bypassing the reformed gas sent from the reformer 12 to the combustion unit 14 by bypassing the fuel cell 11. The common port 33C of the outlet side three-way valve 25 is connected to the combustion section 14 as a first port, the port 34A is connected to the anode off-gas outlet of the fuel cell 11 as a second port, and the port 34B is connected to the bypass path 26 as a third port. Has been.

   As shown in FIGS. 2 and 3, the inlet side and outlet side three-way valves 24, 25 have a valve shaft 29 projecting from the ball valve body 28. Is connected to the motor 31 via the speed reduction mechanism 30. The housing 27 has a valve chamber 32 into which the ball valve body 28 is fitted, a common port 33C having one end opened on the bottom surface of the valve chamber 32 and the other end opened on the lower surface of the housing 27, and each end of the valve chamber 32. Ports 34 </ b> A and 34 </ b> B are formed in the side surface so as to open from directions orthogonal to each other and the other ends open to the side surface of the housing 27. The ball valve body 28 has a valve hole 35 that opens on the lower surface of the ball valve body 28 and always communicates with the common port 33C, and communicates with the valve hole 35 and opens on the side surface of the ball valve body 28 to communicate with the ports 34A and 34B. A valve hole 36 for blocking is formed. A torsion coil spring 37 is interposed between the valve shaft 29 and the housing 27, and the ball valve body 28 does not communicate with the ports 34A and 34B due to the spring force of the torsion coil spring 37 when the motor 31 is in an inactive state (FIG. 4 ( It is biased to the closed position shown in b). The emergency shut-off device in which the three-way valves 24 and 25 are switched to the closed position that shuts off all communication between the ports when the power is shut off is constituted by a torsion coil spring 37 and the like. When the ball valve body 28 is rotated by the motor 31 against the spring force of the torsion coil spring 37 through the speed reduction mechanism 30, the common port 33C is connected to the valve hole as shown in FIGS. Through 35 and 36, the position is sequentially indexed to a CB position communicating with the port 34B, a C-AB position communicating with the ports 34A and 34B, and a C-A position communicating with the port 34A.

   When the inlet side and outlet side three-way valves 24 and 25 are switched from the CB position to the CA position via the C-AB position according to the rotation of the ball valve body 28, the vicinity of the CB position. Then, the communication area between the common port 33C and the port 34A gradually increases from the fully closed state, the communication area between the common port 33C and the port 34B gradually decreases from the fully open state, and both communication areas are equal at the C-AB position. Thus, at the C-A position, they are fully opened and fully closed, respectively. As a result, the gas flow rate characteristics when the inlet side and outlet side three-way valves 24, 25 are switched from the CB position to the CA position are as shown in FIG. Accordingly, the flow rate QA of the gas flowing through the port 34A gradually increases near the C-B position, rapidly increases near the C-AB position, gradually increases near the C-A position, and the flow rate QB of the gas flowing through the port 34B becomes C- It gradually decreases near the B position, rapidly decreases near the C-AB position, and gradually decreases near the C-A position. At the C-AB position, the flow rates of the gas flowing through the ports 34A and 33B are substantially equal.

   Next, the operation of the above embodiment will be described. When the operation is stopped, the introduction side and outlet side three-way valves 24, 25 are stopped at the closed position by the spring force of the torsion coil spring 37, and a reformed gas inlet 47 for introducing the reformed gas into the anode electrode of the fuel cell 11 and The anode off-gas outlet 48 for extracting the anode off-gas from the anode electrode is closed, and the pressure in the fuel cell 11 and the reformer 12 is lowered by cooling the sealed gas. In this state, the ball valve bodies 28 of the inlet side and outlet side three-way valves 24 and 25 are rotated against the spring force of the torsion coil spring 37 by the motor 31 and stopped at the CB position. The reformed gas outlet 46 is bypassed to the combustion section 14 via the common port 33C, port 34B, bypass path 26, port 34B of the outlet side three-way valve 25 and common port 33C of the inlet side three-way valve 24, and the starting operation is performed. Is started.

   In the reformer 12, combustion fuel gas and combustion air are supplied to the burner of the combustion unit 14 and burned, and the generated combustion gas flows through the heating chamber 20 to heat the catalyst in the reaction chamber 19 and evaporates. Steam is generated in the vessel 15. The reforming fuel gas and the steam generated in the evaporator 15 are mixed and supplied to the reaction chamber 19, and the reformed gas is generated by the steam reforming reaction and the carbon monoxide shift reaction by the catalyst. The reformed gas derived from the reforming unit 13 is reduced in carbon monoxide gas by the CO shift unit 17 and the CO selective oxidation unit 18. During the start-up operation in which the concentration of carbon monoxide gas contained in the reformed gas delivered from the CO selective oxidation unit 18 is higher than a predetermined value, the reformed gas delivered from the CO selective oxidation unit 18 passes through the bypass 26. It is burned in the combustion unit 14.

   It is detected that the catalyst temperature of the CO selective oxidation unit 18 has reached a predetermined value or more, the system 10 becomes stable, and the concentration of carbon monoxide gas contained in the reformed gas sent from the CO selective oxidation unit 18 is a predetermined value. When reduced to the following, in order to switch from the starting operation to the normal operation, the ball valve bodies 28 of the introduction-side and outlet-side three-way valves 24 and 25 are rotated by the motor 31 from the CB position to change the C-AB position. Via, it is indexed to the CA position. Thereby, in the vicinity of the CB position, the communication area between the common port 33C and the port 34A of the introduction side and outlet side three-way valves 24, 25 gradually increases from the fully closed state, and the reformed gas of the reformer 12 Since the communication area between the outlet 46 and the reformed gas inlet 47 of the fuel cell 11 and the communication area between the anode offgas outlet 48 and the combustion section 14 are gradually increased, a large amount of reforming is performed from the reformer 12. The gas is not rapidly aspirated into the fuel cell 11, and the stable state of the reformer 12 is not broken, and the concentration of carbon monoxide gas contained in the reformed gas does not increase. The communication area between the common port 33C and the port 34B gradually decreases from the fully open state, and the communication area between the reformer 12 and the combustion unit 14 via the bypass path 26 gradually decreases. In the vicinity of the C-AB position, the communication area between the common port 33C and the port 34A of the introduction-side and outlet-side three-way valves 24, 25 increases rapidly, the communication area between the port 34B decreases rapidly, and C-A In the vicinity of the position, the communication area with the port 34A gradually increases, the communication area with the port 34B gradually decreases, and the port 34B closes at the C-A position. As a result, while the ball valve bodies 28 of the inlet side and outlet side three-way valves 24, 25 are rotated from the CB position to the CA position, the inlet side and outlet side three-way valves 24, 25 The sum of the flow rate of the gas flowing through the port 34B and the flow rate of the gas flowing through the port 34A is substantially constant as shown in FIG. 5 and does not change rapidly. Therefore, the reformer is used when switching from the startup operation to the normal operation. The 12 stable states can be maintained well.

   In addition, when the valve between the CO selective oxidation unit and the fuel cell is suddenly opened at the time of switching from start-up operation to normal operation as in the prior art, the anode off-gas flow temporarily stops, causing problems such as burner misfire. Although there is a possibility, in the above-described embodiment, the communication area between the reformer 12 and the reformed gas inlet 47 of the fuel cell 11 and the off-gas outlet and the combustion unit 14 when switching from the startup operation to the normal operation. Is gradually increased, and the communication area between the reformer 12 and the combustion section 14 via the bypass passage 26 is gradually reduced and shut off, so that the burner 21 is passed from the reformer 12 via the bypass passage 26. The flow of the reformed gas sent to the fuel cell 11 and the anode off gas sent from the anode off gas outlet 48 of the fuel cell 11 to the burner 21 do not stop at the same time, resulting in burner misfire or unstable combustion. The increase in emission can be suppressed that.

   In the above-described embodiment, the common port 33C of the outlet side three-way valve 25 is the first port to the combustion unit 14, the port 34A is the second port to the off-gas outlet of the fuel cell 11, and the port 34B is the third port. 26, the port 34B as a first port to the combustion section 14, the port 34A as a second port to the anode offgas outlet 48 of the fuel cell 11, and the common port 33C as a third port 26 You may connect to each. In this case, the outlet side three-way valve 25 is maintained at the C-AB position during normal operation.

   Next, with respect to the fuel cell system 40 according to the second embodiment, parts different in configuration from those in the first embodiment will be described with reference to FIG. 6, and the same constituent parts will be described with the same reference numerals. Omitted.

   An introduction side three-way valve 41 is connected between the reformer 12 and the fuel cell 11 via a reformed gas condenser 42. The common port 33C of the introduction side three-way valve 41 is connected as a first port to the reformed gas outlet 46 of the reformer 12 via the condenser 42, and the port 34A is used as the second port for the reformed gas of the fuel cell 11. Connected to the introduction port 47, the port 34 </ b> B is connected to the burner 21 of the combustion unit 14 through the warm-up unit 43 of the reformer 12.

   The warm-up unit 43 introduces a reformed gas and an oxidant gas, which is derived from the CO selective oxidation unit 18 and supplied without passing through the fuel cell 11, and incorporates a built-in combustion catalyst (for example, a palladium-based catalyst, A platinum-based catalyst, a platinum-palladium-based catalyst), and the combustion gas is supplied to a heat exchanger. In the heat exchanger, the temperature of the reformed gas introduced into the CO shift unit 17 during the start-up operation is increased by exchanging heat with the combustion gas.

   The anode offgas outlet 48 of the fuel cell 11 is connected to the burner 21 of the combustion unit 14 via a valve 44 and an anode offgas condenser 45. The valve 44 is pressed against the valve seat by the spring force of the compression spring to close the valve hole to close the valve, and the valve body is released from the valve seat against the spring force by the magnetic force of the solenoid. Open. The valve 44 may be a check valve that allows the anode off-gas flow from the anode off-gas outlet 48 side of the fuel cell 11 to the burner 21 side and blocks the flow from the burner 21 side to the fuel cell side 11. .

  The reformed gas condenser 42 condenses water vapor in the reformed gas supplied to the reformed gas inlet 47 of the fuel cell 11. The anode off-gas condenser 45 is provided in the middle of a pipe that connects the anode off-gas outlet 48 of the fuel cell 11 and the burner 21 of the combustion unit 14, and condenses water vapor in the anode off-gas flowing through the pipe. . The condensers 42 and 45 are supplied with a low-temperature liquid (not shown) or a liquid cooled by a radiator, and water vapor in each gas is condensed by heat exchange with the liquid.

   In the second embodiment, when the operation is stopped, the introduction side three-way valve 41 is stopped at the closed position by the spring force of the torsion coil spring 37, so that the reformed gas inlet 47 of the fuel cell 11 and the reformer 12 are modified. The quality gas outlet 46 and the warming-up portion 43 are closed, and the valve 44 is closed by urging the valve body by the spring force of the compression spring, whereby the anode off-gas outlet 48 of the fuel cell 11 is closed. . At this time, the pressure in the fuel cell 11 and the reformer 12 is lowered by cooling the sealed gas. In this state, the ball valve body 28 of the introduction side three-way valve 41 is rotated against the spring force of the torsion coil spring 37 by the motor 31 and stopped at the CB position, and the reformed gas outlet 46 of the reformer 12 is reached. Is bypassed to the combustion section 14 via the common port 33C, port 34B, and warm-up section 43 of the introduction side three-way valve 41, and the start-up operation is started. The reformed gas delivered from the reformed gas outlet 46 of the reformer 12 during the start-up operation has a carbon monoxide gas concentration higher than a predetermined value, and therefore passes through the warm-up unit 43 to the burner 21 of the combustion unit 14. It is sent and burned with combustion air along with fuel gas for combustion. Before the reformed gas is sent to the combustion unit 14, the warm-up unit 43 performs catalytic combustion to generate heat, and the temperature of the reformed gas introduced into the CO shift unit 17 is increased. Shorten the start-up time until carbon monoxide shift reaction in a stable state.

   It is detected that the catalyst temperature of the CO selective oxidation unit 18 has reached a predetermined value or more, the system 40 becomes stable, and the concentration of carbon monoxide gas contained in the reformed gas sent from the CO selective oxidation unit 18 is a predetermined value. When reduced to the following, in order to switch from the start-up operation to the normal operation, the valve 44 is opened, the anode off-gas outlet 48 of the fuel cell 11 is communicated with the combustion unit 11, and the ball valve body of the introduction-side three-way valve 41. 28 is rotated from the C-B position by the motor 31 and is indexed to the C-A position via the C-AB position. In the vicinity of the CB position, the communication area between the common port 33C and the port 34A of the introduction side three-way valve 41 gradually increases from the fully closed state, and the reformed gas outlet 46 of the reformer 12 and the fuel cell 11 The communication area between the reformed gas introduction port 47 gradually increases, the communication area between the common port 33C and the port 34B gradually decreases from the fully open state, and the reformer 12, the warm-up unit 43, and the combustion unit 14 The communication area between them gradually decreases.

   As a result, a large amount of reformed gas is rapidly sucked into the fuel cell 11 from the reformer 12, the stable state of the reformer 12 is broken, and the concentration of carbon monoxide gas contained in the reformed gas increases. The anode electrode of the fuel cell is not poisoned. Further, the reformed gas sent from the reformer 12 to the burner 21 through the port 34B of the introduction side three-way valve 41 and the anode offgas sent from the anode offgas outlet of the fuel cell 11 to the burner 21 through the valve 44. The flow does not stop at the same time, and an increase in emission due to burner misfire or combustion instability can be suppressed.

   In the second embodiment, the port 34B of the introduction side three-way valve 41 is connected to the combustion unit 14 via the warm-up unit 43 of the reformer 12, but the introduction side three-way valve 41 and the combustion unit 14 are connected. The warming-up part interposed between the two may be a warming-up part that raises the temperature of the refrigerant of the cooling device such as the fuel cell 11 during the start-up operation.

   In the above embodiment, the three-way valve is a three-way ball valve having a spherical valve body, but may be a direct-acting three-way valve in which the valve body is formed of a spool.

   In the above embodiment, the reformer reforms the supplied reforming fuel gas and steam to generate reformed gas, but reforms the reforming methanol to reform. A reformer that generates gas may be used.

1 is a schematic diagram showing an overview of a fuel cell system according to a first embodiment of the present invention. Sectional drawing of the three-way valve used for a fuel cell system. 3-3 sectional drawing of FIG. The figure which shows the communication relation of each port of a three-way valve. The figure which shows the flow volume characteristic of each port of a three-way valve. The schematic diagram which shows the outline | summary of the fuel cell system which concerns on 2nd Embodiment. The figure which shows the conventional fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,40 ... Fuel cell system, 11 ... Fuel cell, 12 ... Reformer, 13 ... Reforming part, 14 ... Combustion part, 15 ... Evaporator, 16 ... Heat exchange part, 17 ... Carbon monoxide shift reaction part ( CO shift unit), 18 ... carbon monoxide selective oxidation unit (CO selective oxidation unit), 19 ... reaction chamber, 20 ... heating chamber, 21 ... burner, 22 ... gas pump, 24, 41 ... introduction side three-way valve, 25 ... Derived side three-way valve, 26 ... Bypass passage, 27 ... Housing, 28 ... Ball valve element, 29 ... Valve shaft, 30 ... Deceleration mechanism, 31 ... Motor, 32 ... Valve chamber, 33C ... Common port, 34A, 34B ... Port 35, 36 ... valve hole, 37 ... torsion coil spring, 42, 45 ... condenser, 43 ... warm-up part, 44 ... valve, 46 ... reformed gas outlet, 47 ... reformed gas inlet, 48 ... anode off gas Outlet.

Claims (5)

A reformer that generates reformed gas by a catalyst heated by the combustion gas generated in the combustion section is provided, and the reformer is modified at the reformed gas inlet for introducing the reformed gas into the anode electrode of the fuel cell. In the fuel cell system, wherein a gas outlet is connected, and the combustion section is connected to an anode offgas outlet for extracting anode offgas from the anode electrode,
The first to third ports include a reformed gas delivery port of the reformer, a reformed gas inlet of the fuel cell, and an inlet side three-way valve respectively connected to the burner of the combustion section. 1 port communicates with the 3rd port, the 2nd port is closed, and the communication area between the 1st port and the 2nd port is gradually increased in switching from the start operation to the normal operation, and the 1st port and the 3rd port The communication area is gradually reduced, the first port communicates with the second port during normal operation and the third port is closed, and all communication between the ports is shut off when the operation is stopped. system. In Claim 1, the 1st thru | or 3rd port of the derivation | leading-out three-way valve is respectively connected to the burner of the said combustion part, the said anode offgas derivation | leading-out port, and the 3rd port of the said introduction | transduction side three-way | valve, The valve communicates the first port with the third port and closes the second port during start-up operation, and gradually increases the communication area between the first port and the second port when switching from start-up operation to normal operation. The communication area between the first port and the third port is gradually reduced. In normal operation, the first port is connected to the second port and the third port is closed. A fuel cell system characterized by being cut off. 2. The combustion section according to claim 1, wherein a third port of the introduction side three-way valve is connected to a burner of the combustion section via a warm-up section, and the anode offgas outlet is closed when the operation is stopped. A fuel cell system characterized by being connected to a burner. 4. The fuel cell system according to claim 1, wherein the introduction-side and lead-out-side three-way valves are three-way ball valves configured to rotate a ball-shaped valve body with an actuator. 5. 5. The inlet side and outlet side three-way valve according to claim 1, further comprising an emergency shut-off device that switches the valve body to a closed position that shuts off all communication between the ports when the power is shut off. A fuel cell system.

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