JP2007257923A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system equipped with a four-way valve capable of adequately connecting a reforming part of a reformer and a combustion part according to an operation state. <P>SOLUTION: When a valve element is rotated to a first state, by a first communication groove and a second communication groove formed on the outer peripheral surface of the valve element, a reformed gas leading out port of the reformer and the combustion part, and an off gas leading out part of a fuel cell and a reformed gas introduction port are communicated respectively, and when the valve element is rotated to a second state, the reformed gas leading out port of the reformer and the reformed gas introduction port of the fuel cell, and the offgas leading out port and the combustion part are communicated respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In Patent Document 1, as shown in FIG. 1, a reformed gas outlet port of a CO remover 16 connected to a reformer 14, a reformed gas inlet port of a fuel cell 9, and catalytic combustion A CO remover switching valve 16a, which is an electromagnetic three-way valve, is connected between the gas generator 18 and the reformed gas from the CO remover 16 bypasses the fuel cell 9 by the electromagnetic three-way valve during the warm-up operation, and the catalyst. A fuel cell system is described in which the reformed gas from the CO remover 16 is supplied to the fuel cell 9 when it is sent to the combustor 18 and the temperature of each device is increased to a predetermined temperature.

As described above, Patent Document 2 discloses a valve device that sends the reformed gas to the combustion unit while bypassing the fuel cell during the warm-up operation, and sends the reformed gas to the fuel cell when each device is heated to a predetermined temperature. The use of a rotary valve that controls a plurality of flow paths by the rotation of a ball valve 13 as shown has not been conventionally performed.
JP 2003-20203 A (Page 4, FIG. 1) JP-A-9-329250 (page 3, FIG. 3)

  In the fuel cell system described in Patent Document 1, since the off-gas outlet of the fuel cell is in communication with the combustion part during the warming-up operation when the fuel cell is stopped, the fuel cell has a high air or CO concentration. There is a possibility that the reformed gas flows in and deteriorates the electrode part. In order to prevent this, if an electromagnetic on-off valve is provided between the off-gas outlet and the combustion section, the number of valves increases and the cost increases.

  Further, in the electromagnetic three-way valve, the valve body is released from the valve seat in a short time by the energization of the solenoid. Therefore, when the warm-up operation is finished and the solenoid is energized, the reformed gas is rapidly changed to the fuel cell. May cause deterioration and damage of the anode electrode.

   An object of the present invention is to provide a fuel cell system including a four-way valve device capable of appropriately connecting a reforming unit and a combustion unit of a reforming device and a fuel cell according to an operation state.

  In order to solve the above problems, the structural feature of the invention according to claim 1 is that a reforming unit that reforms reforming fuel with a reforming catalyst to generate reformed gas rich in hydrogen, and combustible A reformer that includes a combustion section that generates a combustion gas for heating the reforming section by burning a reactive fuel, and that sends out the reformed gas generated in the reforming section from a reformed gas outlet; A reformed gas inlet for introducing the reformed gas into the anode electrode connected to the reformed gas outlet, an oxidant gas inlet for introducing the oxidant gas into the cathode electrode, and an anode off-gas from the anode electrode are led out. A fuel cell having an off-gas outlet, and provided with a valve device that selectively connects the reformed gas outlet, the reformed gas inlet, the off-gas outlet and the combustion section, The valve device communicates with the reformed gas outlet A valve housing provided with a first inflow path, a first outflow path communicating with the reformed gas inlet, a second inflow path communicating with the off-gas outlet, a second outflow path communicating with the combustion section; A valve hole formed in the valve housing, in which the first and second inflow passages and the first and second outflow passages are open, and a circular cross-section valve closely fitted in the valve hole so as to be rotatable about the rotation axis Body and a groove shape on the outer peripheral surface of the valve body, and when the valve body is turned to the first state, the first inflow path, the second outflow path, the first outflow path, and the First and second communication grooves communicating with the first inflow path and the first outflow path, and communicating with the second inflow path and the second outflow path when the second inflow path is communicated and rotated to the second state. And a drive device that rotates the valve body between the first state and the second state.

  The structural feature of the invention according to claim 2 is that, in the first aspect, the first communication groove is formed at a central portion in the course of switching in which the valve body is rotated from the first state to the second state. The first outflow path and the front end communicate with the first inflow path, the rear end communicates with the second inflow path, and the second communication groove includes the second outflow path at the center and the front end at the front end. The second inflow path and the rear end portion communicate with the first inflow path.

  According to a third aspect of the present invention, in the first or second aspect, the first state is a stop / warm-up position where the valve device is rotated when the fuel cell system is stopped / warm-up. The second state is that the power generation position is rotated during the power generation operation.

  In the invention according to claim 1 configured as described above, when the valve body is rotated to the first state, the first communication groove and the second communication groove which are engraved in a groove shape on the outer peripheral surface of the valve body. Thus, when the reformed gas outlet and the combustion section of the reformer, the off-gas outlet and the reformed gas inlet of the fuel cell are communicated with each other and rotated to the second state, the reformed gas guide of the reformer is introduced. The outlet, the reformed gas inlet of the fuel cell, the off-gas outlet and the combustion section are communicated with each other. As a result, for example, when the fuel cell system is in the stop / warm-up operation and the power generation operation, the fluid passage communication relationship between the reformer and the fuel cell is required for one simple four-way valve device. This can be achieved by switching.

   In the invention according to claim 2 configured as described above, each communication area between the reformed gas outlet of the reformer and the reformed gas inlet of the fuel cell, the off-gas outlet and the combustion section is determined by the rotation of the valve body. While gradually increasing as the valve moves, the communication areas of the reformed gas outlet and the combustion section, the off-gas outlet and the reformed gas inlet gradually decrease as the valve body rotates. Thereby, it is possible to switch from the warm-up operation to the power generation operation, for example, while maintaining a stable state of the entire system without causing a sudden change in the flow path area. In particular, a large amount of reformed gas is suddenly sucked into the fuel cell, so that the stable state of the reformer is not broken and the concentration of carbon monoxide gas contained in the reformed gas does not increase. Further, it is possible to prevent the combustion part from being blown out by temporarily stopping the anode off-gas flow, or the emission from being increased due to unstable combustion.

  In the invention according to claim 3 configured as described above, when the valve body is turned to the stop / warm-up position, the reformed gas outlet and the combustion section of the reformer, the off-gas outlet of the fuel cell, When the reformed gas inlet is communicated and rotated to the power generation position, the reformed gas outlet of the reformer, the reformed gas inlet of the fuel cell, the offgas outlet and the combustion section are in communication with each other. , Achieves fluid flow path communication between the reformer and the fuel cell, which are necessary for stopping and warming up the fuel cell system and during power generation, by switching one simple four-way valve device can do.

  Embodiments of a fuel cell system according to the present invention will be described below. As shown in FIG. 1, the fuel cell system includes a fuel cell 11 and a reformer 12 that generates a reformed gas rich in hydrogen necessary for the fuel cell 11 and supplies the reformed gas through a reformed gas outlet 12a. Yes. A reformed gas is supplied from the reformer 12 to the anode electrode of the fuel cell 11, and air from the outside is supplied as an oxidant gas to the cathode electrode of the fuel cell 11 by an air pump. Hydrogen in the gas and oxygen in the cathode air react to generate power. Therefore, the fuel cell 11 includes a reformed gas inlet 11a that is connected to the reformed gas outlet 12a and introduces the reformed gas into the anode electrode, an oxidant gas inlet 11b that introduces the oxidant gas into the cathode electrode, and An off-gas outlet 11c for leading out anode off-gas from the anode electrode is provided.

  The reformer 12 evaporates the pure water supplied from the reforming unit 13 and the water pump 24 that are supplied with a hydrocarbon-based reforming fuel gas such as natural gas or LPG and steam to generate reformed gas. An evaporator 15 that generates water vapor to be supplied to the reforming unit 13, and a combustion unit that generates combustion gas for heating the reforming unit 13 and the evaporator 15 by mixing and burning combustion fuel gas and combustion air 14. Carbon monoxide contained in the reformed gas stacked at the lower part of the reforming unit 13 and generated at the reforming unit 13 and cooled by the heat exchanging unit 16 stacked at the lower part of the heat exchanging unit 16 CO shift unit 17 that removes CO, and a CO selective oxidation unit that is connected to CO shift unit 17 and further removes carbon monoxide contained in the reformed gas sent from CO shift unit 17 and supplies the fuel cell 11 from the outlet It is comprised from 18. The outlet of the CO selective oxidation unit 18 serves as the reformed gas outlet 12a of the reformer 12. The reformed gas introduced into the anode electrode from the reformed gas introduction port 11a of the fuel cell 11 reacts with oxygen in the cathode air introduced into the cathode electrode through the oxidant gas introduction port 11b to generate electricity and generate water. However, the anode off-gas that is an excessive reformed gas is sent from the off-gas outlet 11c 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.

  In the heat exchange unit 16 and the CO selective oxidation unit 18 of the reformer 12, the reforming fuel gas and the CO selective oxidizing air that are sent from the gas pump 22 and the air pump 23 while controlling the flow rate are supplied to the reforming fuel gas channel 25. And are supplied simultaneously through the air flow path 26.

   When the fuel cell system is stopped or warmed up, the reformed gas outlet 12a of the reformer 12 and the combustion section 14 are communicated, and the offgas outlet 11c of the fuel cell 11 and the reformed gas inlet 11a are communicated. ing. During the power generation operation, the reformed gas outlet 12a of the reformer 12 and the reformed gas inlet 11a of the fuel cell 11 communicate with each other, and the offgas outlet 11c of the fuel cell 11 and the combustion unit 14 communicate with each other. In order to form such a flow path, a valve device 27 is interposed across the reformed gas flow path 41 and the off-gas flow path 42.

  As shown in FIG. 2, the valve device 27 has a seat member 29 integrally fixed to the inner hole of the valve housing 28, and a ball valve body 31 having a circular cross section is formed in a spherical valve hole 30 formed in the seat member 29. It is closely fitted so as to be rotatable around the rotation axis 32. The seat member 29 is divided into left and right at the center of the spherical valve hole 30 by a plane parallel to the rotation axis 32, and the ball valve element 31 is sandwiched between the left and right seat members 29 a and 29 b and is closely fitted in the spherical valve hole 30. Has been. As shown in FIG. 3, the valve housing 28 and the left and right seat members 29 a and 29 b are not equidistant from the center O of the ball valve body 31 in a plane perpendicular to the rotation axis 32 and including the center O of the ball valve body 31. The flow paths 33 and 34 that are parallel to each other are penetrated. The flow paths 33 and 34 are divided by the valve hole 30 into first and second inflow paths 33a and 34a and first and second outflow paths 33b and 34b that open to both outer surfaces of the valve housing 28 and the valve hole 30, respectively. ing.

  A first communication groove 35 and a second communication groove 36 are formed on the outer peripheral surface of the ball valve body 31 so as to correspond to the first and second inflow paths 33a and 34a and the first and second outflow paths 33b and 34b. ing. When the ball valve body 31 is rotated to the first state shown in FIG. 3A, the first communication groove 35 communicates with the second inflow path 34a and the first outflow path 33b in opposition to each other. The second communication groove 36 is opposed to and communicates with the first inflow passage 33a and the second outflow passage 34b. When the ball valve body 31 is rotated to the second state shown in FIG. 3C, the first communication groove 35 communicates with the first inflow path 33a and the first outflow path 33b in opposition to each other. The second communication groove 36 is opposed to and communicates with the second inflow passage 34a and the second outflow passage 34b. During the switching shown in FIG. 3B in which the ball valve body 31 is rotated from the first state to the second state, the first communication groove 35 has a first outlet channel 33b at the center and a first at the tip. The inflow channel 33a communicates with the second inflow channel 34a at the rear end, and the second communication groove 36 has a second outflow channel 34b at the center, a second inflow channel 34a at the tip, and a second at the rear end. 1 communicates with the inflow path 33a.

  The first inflow passage 33a and the first outflow passage 33b are connected to the reformed gas outlet 12a of the reformer 12 and the reformed gas inlet 11a of the fuel cell 11 by the reformed gas channel 41, respectively. The passage 34 a and the second outflow passage 34 b are connected to the off-gas outlet 11 c of the fuel cell 11 and the combustion unit 14 by an off-gas passage 42, respectively.

  A valve shaft 37 protruding from the ball valve body 31 on the rotation axis 32 passes through the contact portions of the left and right seat members 29 a and 29 b and is connected to a motor 39 via a speed reduction mechanism 38. A torsion coil spring 40 is interposed between the valve shaft 37 and the valve housing 28, and the ball valve body 31 is rotated to the first state by the spring force of the torsion coil spring 40 when the motor 39 is in an inactive state. The ball valve body 31 is rotated by the motor 39 from the first state to the second state against the spring force of the torsion coil spring 40 via the speed reduction mechanism 38.

   Next, the operation of the above embodiment will be described. When the start-up operation of the fuel cell system is commanded, the combustion fuel gas and the combustion air are supplied to the burner 21 of the combustion unit 14 and burned, and the generated combustion gas flows through the heating chamber 20 and flows into the reforming unit 13. While heating the catalyst, the evaporator 15 generates water vapor. When the reforming unit 13 rises to a predetermined temperature, the reforming fuel gas and the steam that are sent out by controlling the flow rate by the gas pump 22 are supplied to the reforming unit 13 of the reforming device 21 via the heat exchange unit 16. At the same time, CO selective oxidation air that is sent out by controlling the flow rate by the air pump 23 is simultaneously supplied to the CO selective oxidation unit 18. The reforming fuel gas and water vapor are preheated in the heat exchange unit 16 and supplied to the reforming unit 13, and the reformed gas is subjected to a steam reforming reaction and a carbon monoxide shift reaction by a catalyst heated by the combustion gas. Generated. The reformed gas derived from the reforming unit 13 is reduced in concentration of carbon monoxide gas by the CO shift unit 17 and the CO selective oxidation unit 18 to which CO selective oxidation air is supplied from the air pump 23.

   During the stop / warm-up operation, the valve device 27 rotates the ball valve element 31 to the first state by the spring force of the torsion coil spring 40, and the reformed gas outlet 12a of the reformer 12 and the combustion section 14 are connected. The off-gas outlet 11c and the reformed gas inlet 11a of the fuel cell 11 communicate with each other via the second communication groove 36, and communicate with each other via the first communication groove 35. As a result, during the warm-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 is fuel. The battery 11 is bypassed and sent to the combustion unit 14 to be combusted, and the offgas outlet 11c of the fuel cell 11 communicates with the reformed gas inlet 11a.

   It is detected that the catalyst temperature of the CO selective oxidation unit 18 has reached a predetermined value or more, the reformer 12 becomes stable, and the concentration of carbon monoxide gas contained in the reformed gas sent from the CO selective oxidation unit 18 is increased. When it decreases below the predetermined value, the ball valve body 31 of the valve device 27 is rotated by the motor 39 to the second state against the spring force of the torsion coil spring 40 in order to switch from the stop / warm-up operation to the power generation operation. The reformed gas sent from the reformed gas outlet 12a of the reformer 12 is supplied to the reformed gas inlet 11a of the fuel cell 11 through the reformed gas channel 41, and the offgas outlet 11c of the fuel cell 11 is supplied. The anode off gas sent out from the gas passes through the off gas passage 42 and is sent to the combustion unit 14.

   In the middle of the switching in which the ball valve body 31 is rotated from the first state to the second state, the central portion of the first communication groove 35 communicates with the first outflow passage 33b, and the first end portion of the first communication groove 35 and the first portion. As the communication area with the inflow passage 33a gradually increases, the communication area between the rear end portion of the first communication groove 35 and the second inflow passage 34a gradually decreases. The central portion of the second communication groove 36 communicates with the second outflow passage 34b, and the rear end of the second communication groove 36 gradually increases as the communication area between the front end portion of the second communication groove 36 and the second inflow passage 34a gradually increases. The communication area between the portion and the first inflow passage 33a gradually decreases. Accordingly, the communication areas of the first inflow path 33a and the first outflow path 33b, the second inflow path 34a and the second outflow path 34b gradually increase as the ball valve body 31 rotates at an appropriate speed, and the first inflow path 33a. The communication areas of the second outflow path 34b, the second inflow path 34a, and the first outflow path 33b are gradually reduced. Thereby, it is possible to switch from the warm-up operation to the power generation operation while maintaining a stable state of the entire system without causing a rapid change in the flow path area. In particular, a large amount of reformed gas is not suddenly sucked 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. Further, the anode off gas flow temporarily stops, so that the burn-out of the burner 21 or an increase in emission due to unstable combustion can be suppressed.

   In the above embodiment, the valve body of the valve device 27 is a spherical ball valve body. However, the valve body may be a rotary body around the rotation axis and a valve body having a circular cross section.

   In the above-described embodiment, the reformer reforms the supplied reforming fuel gas and steam in the reforming section to generate reformed gas. However, methanol is used as the reforming fuel. A reformer that generates a reformed gas by evaporating in a mixed state and water and reforming in a reforming unit may be used.

1 is a schematic diagram showing an outline of a fuel cell system according to an embodiment of the present invention. The figure which shows the 4-way valve apparatus used for the fuel cell system shown in FIG. The figure which shows the state which the ball valve body of the four-way valve apparatus rotated to each position.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Fuel cell, 11a ... Reformed gas inlet, 11c ... Off-gas outlet, 12 ... Reformer, 12a ... Reformed gas outlet, 13 ... Reformer, 14 ... Combustor, 15 ... Evaporator, 16 DESCRIPTION OF SYMBOLS ... Heat exchange part, 17 ... CO shift part, 18 ... CO selective oxidation part, 19 ... Reaction chamber, 20 ... Heating chamber, 21 ... Burner (combustion part), 22 ... Gas pump, 23 ... Air pump, 24 ... Water pump, 25 ... reforming fuel gas flow path, 26 ... air flow path, 27 ... valve device, 28 ... valve housing, 29 ... seat member, 30 ... valve hole, 31 ... ball valve element, 32 ... rotation axis, 33a ... first Inflow passage, 33b ... first outflow passage, 34a ... second inflow passage, 34b ... second outflow passage, 35 ... first communication groove, 36 ... second communication groove, 37 ... valve shaft, 38 ... deceleration mechanism, 39 ... Motor 40 ... Torsion coil spring 41 ... Reformed gas flow path 42 ... Off gas flow path

Claims (3)

A reforming section that reforms reforming fuel with a reforming catalyst to generate a reformed gas rich in hydrogen, and a combustion that burns combustible fuel to generate a combustion gas for heating the reforming section And a reformer that sends out the reformed gas generated in the reformer from the reformed gas outlet, and a reformer that is connected to the reformed gas outlet and introduces the reformed gas into the anode electrode In a fuel cell system comprising a gas inlet, an oxidant gas inlet for introducing an oxidant gas into the cathode electrode, and a fuel cell having an off-gas outlet for deriving an anode off-gas from the anode electrode,
Provided is a valve device for selectively connecting the reformed gas outlet, the reformed gas inlet, the off-gas outlet and the combustion section,
A first inflow path communicating with the reformed gas outlet, a first outflow path communicating with the reformed gas inlet, a second inflow path communicating with the offgas outlet, and a second outflow path communicated with the combustion section A valve housing provided with
A valve hole formed in the valve housing and opening the first and second inflow passages and the first and second outflow passages;
A valve body having a circular cross section tightly fitted in the valve hole so as to be rotatable around the rotation axis;
When the valve body is engraved in a groove shape on the outer peripheral surface of the valve body and the valve body is turned to the first state, the first inflow path, the second outflow path, the first outflow path, and the second inflow path A first communication groove that communicates the first inflow path and the first outflow path, the second inflow path and the second outflow path, and the first and second communication grooves,
A fuel cell system comprising: a four-way valve device including a drive device that rotates the valve body between the first state and the second state. 2. The first communication groove according to claim 1, wherein the first communication groove is formed at a center portion of the first outflow path and a front end portion of the valve body during the switching in which the valve body is rotated from the first state to the second state. The second communication groove is communicated with the second inflow path at the center, the second inflow path at the front end, and the first at the rear end. A fuel cell system that communicates with an inflow channel. 3. The first state according to claim 1, wherein the first state is a stop / warm-up position where the valve device is rotated while the fuel cell system is stopped / warm up, and the second state is during a power generation operation. A fuel cell system, wherein the fuel cell system is a power generation position that is rotated by

Images