JP5086743B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a reformer, a fuel cell system, and a method for operating the reformer, and in particular, reduces the time required to raise the temperature of the reforming unit, the shift unit, and the selective oxidation unit to an appropriate temperature during steady operation. The present invention relates to a reformer, a fuel cell system, and a method for operating the reformer.

A fuel cell that uses hydrogen and oxygen to generate electric power through these electrochemical reactions has attracted attention as an environmentally friendly power generator. Fuel cells require hydrogen for power generation, but they are relatively difficult to obtain because the infrastructure for supplying hydrogen itself is not widespread. In many cases, a reformer for generating a quality gas is provided in the fuel cell. The reformer includes a reforming unit that introduces and reforms a raw material that serves as a reformed gas, a transformation unit that selectively reduces the concentration of carbon monoxide in the gas generated in the reforming unit, and a selective oxidation unit. It is common to have a heating unit that generates reforming heat used for reforming in the reforming unit. Each of the reforming unit, the shift unit, and the selective oxidation unit of the reformer has a temperature suitable for the reaction in each unit (see, for example, Patent Document 1).
JP 2006-210131 A

  In the reformer, the temperature in a stopped state (a state in which no reformed gas is generated) is typically the ambient temperature (room temperature or outside temperature). When starting from the state where the reforming apparatus is stopped, the reforming section rises in a relatively short time because of heat received from the heating section. On the other hand, since the temperature of the shift unit and the selective oxidation unit is raised by heat transferred from the reforming unit via the constituent members or heat generated during the reaction in the shift unit and the selective oxidation unit, the temperature is increased to an appropriate temperature during steady operation. It took considerable time to raise the temperature.

  In view of the above-described problems, the present invention takes time required to raise the temperature of the reforming unit, the shift unit, and the selective oxidation unit to an appropriate temperature during steady operation when the reformer is started from a stopped state. It is an object of the present invention to provide a reformer capable of shortening the time, a fuel cell system including the reformer, and a method for operating the reformer.

  In order to achieve the above object, the reformer according to the first aspect of the present invention, for example, as shown in FIG. 1, introduces a reforming raw material m and reforms it to enrich the hydrogen-rich gas r1 rich in hydrogen. A reforming part 21 that generates hydrogen; a reforming part 23 that introduces a hydrogen-rich gas r1 and produces a modified gas r2 having a carbon monoxide concentration lower than that of the hydrogen-rich gas r1; A selective oxidation unit 25 that generates a reformed gas g having a lower carbon monoxide concentration; a portion adjacent to the reforming unit 21, a portion adjacent to the shift unit 23, and a portion adjacent to the selective oxidation unit 25 in this order. And a first heat medium flow path 83 through which the heat medium w flows.

  If comprised in this way, since the 1st heat-medium flow path which flows a heat medium in this order is provided in the part adjacent to a reforming part, the part adjacent to a transformation part, and the part adjacent to a selective oxidation part, a reformer It is possible to transfer the heat of the reforming unit to the transformation unit and the selective oxidation unit by the heat medium when starting from a state where the gas is stopped, and the reforming unit, the transformation unit, and the selective oxidation unit are in steady operation. The time required to raise the temperature to an appropriate temperature can be shortened.

  Further, the reforming apparatus according to the second aspect of the present invention is, for example, as shown in FIG. 1, in the reforming apparatus 20 according to the first aspect of the present invention, a portion adjacent to the selective oxidation unit 25, The part adjacent to the part 23 and the part adjacent to the reforming part 21 are provided with a second heat medium flow path 83 through which the heat medium w flows in this order.

  If comprised in this way, when the temperature of a selective oxidation part becomes higher than the suitable temperature at the time of steady operation, a selective oxidation part can be cooled with a heat medium, and a heat medium can be heated as the reaction. it can.

  Moreover, the reforming apparatus according to the third aspect of the present invention includes, as shown in FIG. 1, for example, in the reforming apparatus 20 according to the second aspect of the present invention, the first heat medium flow path and the second These heat medium flow paths are one flow path 83, and are configured so that the first heat medium flow path and the second heat medium flow path are switched over time. Here, the first heat medium flow path and the second heat medium flow path are one flow path. The one flow path is the first heat medium flow path and the second heat medium flow path. It means to serve as both.

  If comprised in this way, the installation space of a heat carrier channel can be made small, and a reformer can be made compact.

  Further, the reforming apparatus according to the fourth aspect of the present invention includes a reforming unit 21 in the reforming apparatus 20 according to the second aspect or the third aspect of the present invention as shown in FIG. A reforming water flow path 85 is provided for guiding the heat medium w flowing through the second heat medium flow path 83 that has passed through the adjacent portion to the reforming unit 21; the heat medium w reforms the reforming raw material m. It is the water for reforming s used at the time.

  If comprised in this way, the heat | fever of a modification part can be given to the water for a modification | reformation.

  In order to achieve the above object, a fuel cell system according to a fifth aspect of the present invention is provided in any one of the first to fourth aspects of the present invention as shown in FIG. And a fuel cell 30 that generates power by introducing the reformed gas g and an oxidant gas t containing oxygen.

  If comprised in this way, the time required until it starts from the state which the fuel cell system has stopped can be shortened.

  In order to achieve the above object, the operation method of the reforming apparatus according to the sixth aspect of the present invention is, for example, shown by referring to FIG. 1 and FIG. A reforming unit 21 that generates a hydrogen-rich hydrogen-containing gas r1, a reforming unit 23 that introduces the hydrogen-rich gas r1 and generates a modified gas r2 having a lower carbon monoxide concentration than the hydrogen-rich gas r1, A method of operating a reformer 20 having a selective oxidation unit 25 that introduces a gas r2 and generates a reformed gas g having a carbon monoxide concentration lower than that of the modified gas r2; A heat transfer process (St1, St2) for transferring to at least one of the transformation unit 23 and the selective oxidation unit 25 is provided.

  With this configuration, when the reformer is started from a stopped state, the time required to raise the temperature of the reforming unit, the shift unit, and the selective oxidation unit to an appropriate temperature during steady operation is shortened. be able to.

  The reformer operating method according to the seventh aspect of the present invention is, for example, referring to FIG. 1 and FIG. 3, in the reformer operating method according to the sixth aspect of the present invention. A cooling step (St3, St4) for cooling at least one of the unit 23 and the selective oxidation unit 25 is provided.

  If comprised in this way, a reforming part, a change part, and a selective oxidation part can be maintained at the appropriate temperature at the time of steady operation.

  According to the present invention, when the reforming apparatus is started from a stopped state, it becomes possible to transfer the heat of the reforming section to the transforming section and the selective oxidation section by the heat medium. The time required to raise the temperature of the part and the selective oxidation part to an appropriate temperature during steady operation can be shortened.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same or corresponding members are denoted by the same or similar reference numerals, and redundant description is omitted.

  First, the structure of the reformer 20 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic system diagram of the reformer 20. The reforming apparatus 20 includes a reforming unit 21, a transformation unit 23, a selective oxidation unit 25, a heating unit 26, and a heating / cooling channel serving as both a first heat medium channel and a second heat medium channel. 83, a reforming water pipe 85 that forms a reforming water flow path, and a control device 38 that controls the operation of the reforming device 20. The reforming unit 21 and the shift unit 23 are connected to each other by being connected via the hydrogen-rich gas flow path 22. The hydrogen-rich gas flow path 22 is typically a pipe, but may be formed by directly connecting the openings of both portions 21 and 23. The shift unit 23 and the selective oxidation unit 25 are connected to each other by being connected via the shift gas channel 24. The metamorphic gas channel 24 is typically a pipe, but may be formed by directly connecting the openings of both portions 23 and 25.

  The reforming unit 21 introduces the reforming raw material m and steam s as reforming water, and reforms the reforming raw material m into a hydrogen-rich hydrogen-containing gas r1 by a steam reforming reaction. The hydrogen-rich gas r1 rich in hydrogen is a gas mainly composed of hydrogen, and is contained in the fuel cell 30 (see FIG. 2) containing 40% by volume or more, typically about 70 to 80% by volume of hydrogen. Gas to be supplied. The hydrogen concentration in the hydrogen-rich gas r1 may be 80% by volume or higher, that is, at a concentration that enables power generation by an electrochemical reaction with oxygen in the oxidant gas t when supplied to the fuel cell 30 (see FIG. 2). I just need it. The hydrogen-rich gas r1 typically contains about 10% by volume of carbon monoxide. The reforming material m is typically composed mainly of chain hydrocarbons such as methane and ethane (including natural gas), or hydrocarbons such as methanol and petroleum products (kerosene, gasoline, naphtha, LPG, etc.). This is a hydrocarbon fuel. The reforming unit 21 is filled with a reforming catalyst (not shown) and configured to promote a steam reforming reaction. As the reforming catalyst, a nickel-based reforming catalyst or a ruthenium-based reforming catalyst is typically used. In addition, a raw material introduction pipe 41 for introducing the reforming raw material m is connected to the reforming unit 21. The raw material introduction pipe 41 is provided with a vaporizer (not shown) that vaporizes when the reforming raw material m is liquid. The proper temperature during steady operation of the reforming unit 21 is about 680 ° C. to 750 ° C. in the present embodiment. The reforming unit 21 is provided with a reforming unit temperature sensor 21t that detects the internal temperature. The reforming unit temperature sensor 21t is connected to the control device 38 via a signal cable, and is configured to transmit the detected temperature in the reforming unit 21 as a signal to the control device 38.

  The shift unit 23 introduces the hydrogen-rich gas r1 from the reforming unit 21, and converts carbon monoxide contained in the hydrogen-rich gas r1 with water contained in the hydrogen-rich gas r1 to produce carbon dioxide. And hydrogen are generated to produce a modified gas r2 having a reduced carbon monoxide concentration from the hydrogen-rich gas r1. The modification reaction is an exothermic reaction. The shift section 23 is filled with a shift catalyst (not shown), and is configured to promote the shift reaction. As the shift catalyst, typically, an iron-chromium shift catalyst, a copper-zinc shift catalyst, a platinum shift catalyst, or the like is used. The metamorphic gas r2 produced in the metamorphic section 23 typically has a carbon monoxide concentration reduced to about 5000 to 10,000 ppm. In this embodiment, the appropriate temperature during steady operation of the transformation section 23 is about 180 ° C to 250 ° C. The transformation section 23 is provided with a transformation section temperature sensor 23t that detects the internal temperature. The transformer temperature sensor 23t is connected to the control device 38 with a signal cable, and is configured to transmit the detected temperature in the transformer 23 as a signal to the control device 38.

  The selective oxidation unit 25 introduces the modified gas r2 from the modified unit 23, introduces oxygen by introducing air a (hereinafter referred to as “selective oxidized air a”) from outside the system, and remains in the modified gas r2. By the selective oxidation reaction between the carbon monoxide thus introduced and the introduced oxygen, a reformed gas g having a further reduced carbon monoxide concentration is generated from the modified gas r2. The selective oxidation reaction is an exothermic reaction. The selective oxidation unit 25 is filled with a selective oxidation catalyst (not shown). As the selective oxidation catalyst, typically, a platinum-based selective oxidation catalyst, a ruthenium-based selective oxidation catalyst, a platinum-ruthenium-based selective oxidation catalyst, or the like is used. The selective oxidation unit 25 is connected to a selective oxidation air pipe 43 for introducing the selective oxidation air a. A selective oxidation air blower 13 is disposed in the selective oxidation air pipe 43. The selective oxidation air blower 13 is connected to the control device 38 through a signal cable, and is configured to receive a signal from the control device 38 and adjust the amount of selective oxidation air a introduced into the selective oxidation unit 25. ing. The appropriate temperature during steady operation of the selective oxidation unit 25 is about 130 ° C. to 160 ° C. in the present embodiment. The selective oxidation unit 25 is provided with a selective oxidation unit temperature sensor 25t that detects the internal temperature. The selective oxidation unit temperature sensor 25t is connected to the control device 38 through a signal cable, and is configured to transmit the detected temperature in the selective oxidation unit 25 as a signal to the control device 38. The selective oxidation unit 25 is connected to a reformed gas pipe 51 for deriving the reformed gas g. The reformed gas g derived from the reformed gas pipe 51 during steady operation is typically a gas containing about 75% hydrogen, and the carbon monoxide concentration in the reformed gas g is about 10 ppm or less.

  Typically, the heating unit 26 has a burner (not shown), one or more of combustion fuel (not shown), anode offgas p, reformed gas g, and combustion. Air (not shown) is introduced and combustion fuel or the like is burned to generate reforming heat. Here, the anode off gas p is a gas exhausted from the fuel cell 30 (see FIG. 2) and containing hydrogen that has not been used in the electrochemical reaction in the fuel cell 30. The combustion fuel is typically the same as the reforming raw material m, but may be a different type of fuel. The heating unit 26 is disposed close to the reforming unit 21 to such an extent that heat used for reforming can be given to the reforming unit 21, and preferably a space is formed in the center of the reforming unit 21. Thus, when it is formed in a bamboo ring shape and disposed in the central space, the reforming heat can be effectively transmitted to the reforming section 21. A combustion exhaust gas pipe 88 is connected to the heating unit 26 as a flow path for discharging the combustion exhaust gas e generated by burning the fuel out of the system. The combustion exhaust gas pipe 88 is disposed so as to be guided out of the system after being disposed in the vicinity of the reforming unit 21 and the transformation unit 23.

  The heating unit 26 is connected to a combustion fuel introduction pipe (not shown) for introducing combustion fuel (not shown) and an anode off gas pipe 52 for introducing the anode off gas p and the reformed gas g. The first combustion that enables heat exchange between the combustion exhaust gas e and the anode off gas p or the reformed gas g in the combustion exhaust gas pipe 88 and the anode off gas pipe 52 outside the system in the vicinity of the portion near the shift portion 23. An exhaust gas heat exchanger 29A is inserted and arranged.

  The heating / cooling channel 83 is a channel through which the heat medium w flows. The heating / cooling flow path 83 is disposed so as to pass through a portion adjacent to the reforming unit 21, then pass through a portion adjacent to the transformation unit 23, and then pass through a portion adjacent to the selective oxidation unit 25. Here, “adjacent” means that the heat transfer between the adjacent portion (the reforming portion 21 and the like) and the heat medium w in the heating / cooling flow path 83 is close to a certain degree. That means. The heating / cooling channel 83 typically has a reforming unit 21, a transformation unit 23, a selective oxidation unit in order to increase the amount of heat exchanged between the adjacent part and the heat medium w (in order to increase the channel area). It is comprised by the jacket (heat exchanger) structure formed so that the circumference | surroundings of each catalyst layer of the part 25 might be enclosed. The heating / cooling flow path 83 may be configured by piping, and the piping may be arranged to meander at a portion adjacent to the portion. In view of the purpose of increasing the amount of heat exchanged, it is assumed that the concept of meandering also includes arranging the heating / cooling channel 83 in a spiral shape, for example.

  The heating / cooling flow path 83 between the part adjacent to the reforming part 21 and the part adjacent to the transformation part 23 and the hydrogen-rich gas flow path 22 are between the heat medium w and the hydrogen-rich gas r1. A hydrogen-rich gas heat exchanger 27 that enables heat exchange is inserted and arranged. Further, the heating / cooling channel 83 between the portion adjacent to the shift unit 23 and the portion adjacent to the selective oxidation unit 25 and the shift gas channel 24 have heat between the heat medium w and the shift gas r2. A modified gas heat exchanger 28 is inserted to allow replacement.

  The front end portion of the heating / cooling flow path 83 extending in the direction opposite to the direction from the portion disposed adjacent to the reforming unit 21 to the transformation unit 23 receives the reforming water s from the reforming unit 21. To the reforming water pipe 85. In other words, the heating / cooling channel 83 and the reforming water pipe 85 are connected at the connection point J1. The end of the reforming water pipe 85 opposite to the connection point J1 is connected to a raw material introduction pipe 41 (typically a vaporizer (not shown) disposed in the raw material introduction pipe 41).

  In addition, a heating water introduction pipe 82 for flowing the heat medium w is connected to the connection point J1. The heated water introduction pipe 82 is at the end opposite to the connection point J1, and in the direction opposite to the direction from the portion disposed adjacent to the selective oxidation unit 25 of the heating / cooling flow path 83 to the transformation unit 23. It is connected with the end part which extended to. In other words, the heated water introduction pipe 82 and the heating / cooling flow path 83 are connected at the connection point J2. An open / close valve 82v capable of blocking the flow of the heat medium w is inserted and disposed in the heated water introduction pipe 82. An opening / closing valve 83v capable of blocking the flow of the heat medium w is inserted and disposed in the heating / cooling flow path 83 between the connection point J2 and the portion adjacent to the selective oxidation unit 25. The on-off valve 82v and the on-off valve 83v are each connected to the control device 38 by a signal cable, and are configured to be able to open and close the valve by receiving a signal from the control device 38, respectively.

  In addition, a heating / cooling water introduction pipe 81 that guides the heat medium w from outside the system to the heating water introduction pipe 82 and the heating / cooling flow path 83 is connected to the connection point J2. A reforming water pump 14 for pumping the heat medium w is inserted and disposed in the heating / cooling water introduction pipe 81. The reforming water pump 14 is connected to the control device 38 through a signal cable, and receives a signal from the control device 38 to adjust the introduction amount of the heat medium w into the heating water introduction pipe 82 or the heating / cooling flow path 83. It is configured to be able to. The second combustion exhaust gas that enables heat exchange between the heat medium w and the combustion exhaust gas e is provided in the heating / cooling water introduction pipe 81 and the combustion exhaust gas pipe 88 between the reforming water pump 14 and the connection point J2. A heat exchanger 29B is inserted and arranged. By disposing the second combustion exhaust gas heat exchanger 29B on the downstream side of the reforming water pump 14, it is possible to avoid a negative pressure inside the second combustion exhaust gas heat exchanger 29B. When the heat medium w introduced from outside the system and flowing in the heating / cooling water introduction pipe 81 is steam, the reforming water pump 14 may not be provided.

  A heating water outlet pipe 84 for leading the heat medium w out of the reformer 20 is connected to the heating / cooling flow path 83 between the portion adjacent to the selective oxidation unit 25 and the connection point J2. An opening / closing valve 84v that can block the flow of the heat medium w is inserted into the heating water outlet pipe 84. The on-off valve 84v is connected to the control device 38 by a signal cable, and is configured to receive a signal from the control device 38 and to open and close the valve. In addition, a cooling water outlet pipe 86 for leading the heat medium w out of the reformer 20 is connected to the heating water inlet pipe 82 between the connection point J1 and the open / close valve 82v. An on-off valve 86v that can block the flow of the heat medium w is inserted into the cooling water outlet pipe 86. The on-off valve 86v is connected to the control device 38 through a signal cable, and is configured to receive a signal from the control device 38 and open and close the valve.

  The control device 38 is configured to control the operation of the reforming device 20. The control device 38 is connected to each of the reforming unit temperature sensor 21t, the transformation unit temperature sensor 23t, and the selective oxidation unit temperature sensor 25t via a signal cable, and receives a temperature signal. The control device 38 transmits an open / close signal for opening or closing the valve to each of the open / close valves 82v, 83v, 84v, 86v. Each on-off valve may be configured to be able to adjust the opening of the valve (including fully open and fully closed) by a signal received from the control device 38. In addition, the control device 38 transmits a flow rate adjustment signal for adjusting the flow rate of the fluid to each of the selective oxidation air blower 13 and the reforming water pump 14. The description of the control by the control device 38 (the operation of the reforming device 20) will be described later.

  Next, the configuration of the fuel cell system 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic system diagram of the fuel cell system 10. The fuel cell system 10 includes the reformer 20 described so far, a fuel cell 30 that generates electric power by an electrochemical reaction between hydrogen and oxygen, and a controller 38 that controls the fuel cell system 10. In the present embodiment, the control device that controls the fuel cell system 10 and the control device that controls the reforming device 20 are common, but may be configured separately.

  The fuel cell 30 is typically a polymer electrolyte fuel cell. The fuel cell 30 includes a fuel electrode that introduces the reformed gas g, an air electrode that introduces the oxidant gas t, and a cooling unit that removes heat generated by the electrochemical reaction. The oxidant gas t is typically air. Although the fuel cell 30 is shown in a simplified manner in the figure, in practice, a single cell is formed by sandwiching a solid polymer film between a fuel electrode and an air electrode, and a plurality of cells are formed via a cooling unit. It is configured by stacking sheets. In the fuel cell 30, hydrogen in the reformed gas g supplied to the fuel electrode is decomposed into hydrogen ions and electrons, and the hydrogen ions pass through the solid polymer film and move to the air electrode. It moves to the air electrode through a conducting wire connecting to the air electrode, reacts with oxygen in the oxidant gas t supplied to the air electrode to generate water, and generates heat during this reaction. In this reaction, the direct current can be taken out by passing electrons through the conducting wire. A power conditioner (not shown) that converts DC power to AC power is connected to the fuel cell 30 as necessary.

  The fuel electrode of the fuel cell 30 and the selective oxidation unit 25 (see FIG. 1) of the reformer 20 are connected via a reformed gas pipe 51. A reformed gas opening / closing valve 61 is inserted into the reformed gas pipe 51. The fuel electrode of the fuel cell 30 and the heating unit 26 (see FIG. 1) of the reformer 20 are connected via the anode off-gas pipe 52 and hydrogen that has not been used for the electrochemical reaction in the fuel cell 30. The anode off gas p containing can be introduced into the heating unit 26 (see FIG. 1). An anode off-gas on / off valve 62 is inserted into the anode off-gas pipe 52. A reformed gas pipe 51 upstream of the reformed gas on-off valve 61 and an anode off-gas pipe 52 downstream of the anode off-gas on / off valve 62 are connected by a bypass pipe 53. A bypass opening / closing valve 63 is inserted into the bypass pipe 53. At the air electrode of the fuel cell 30, an oxidant gas tube 54 for introducing the oxidant gas t and a cathode offgas tube 55 for discharging the cathode offgas q containing oxygen that has not been used for the electrochemical reaction in the fuel cell 30. And are connected. An oxidant gas blower 18 for pumping the oxidant gas t is inserted and disposed in the oxidant gas pipe 54. The oxidant gas blower 18 is configured to be activated and stopped (including adjustment of the rotation speed when the rotation speed is adjustable) in response to a command (including a control signal) from the control device 38. Each of the on-off valves 61 to 63 is connected to the control device 38 via a signal cable, and receives an open / close signal from the control device 38 to adjust the opening degree (including full open and full close) of the valve. It is configured to be able to.

Next, the operation of the reformer 20 and the fuel cell system 10 including the reformer 20 will be described.
First, with reference to FIG. 3, and with reference to FIGS. 1 and 2 as appropriate, the operation at the start-up of the reformer 20 will be described. FIG. 3 is a flowchart for explaining the operation at the start-up of the reforming apparatus 20. The outline of the operation at the start-up of the reformer according to the present invention is as follows.

  Reforming from the state in which the temperature of each part 21, 23, 25 of the reforming apparatus 20 is at or near the ambient environmental temperature (indoor temperature or outside air temperature) while the reforming apparatus 20 is stopped. When the apparatus 20 is started, first, the burner of the heating unit 26 is ignited, and the heat medium w is allowed to flow in the order adjacent to the reforming unit 21, the transformation unit 23, and the selective oxidation unit 25 (heat transfer step: St1). , St2). Since the reforming unit 21 is disposed at a position closest to the heating unit 26, the temperature of the reforming unit 21 is raised to a target temperature (a temperature at which the performance of each unit 21, 23, 25 can be exhibited) in a relatively short time. Since the selective oxidation unit 25 is separated from the heating unit 26, it is difficult to raise the temperature to the target temperature in a short time. However, the heat of the reforming unit 21 is transferred to the transformation unit 23 and / or the selective oxidation unit 25 through the heat medium w through the heat transfer process, so that the temperatures of the transformation unit 23 and the selective oxidation unit 25 rise to the target temperature. The time required for heating can be shortened.

  When the shift unit 23 and the selective oxidation unit 25 reach the target temperature, the flow of the heat medium w is reversed to flow the selective oxidation unit 25, the shift unit 23, and the portion adjacent to the reforming unit 21 in this order (cooling step: St3, St4). By changing the flow of the heat medium w in this way, it is possible to prevent the temperatures of the transformation unit 23 and the selective oxidation unit 25 from rising above the appropriate temperature. The outline is as described above, and will be described in detail below.

  In the present embodiment, the heat medium w and the reforming water s are water. Therefore, both are the same as substances, but paying attention to their functions, when water acts as a heat medium, it acts as water used for reforming the heat medium w and the reforming raw material m. In this case, it is called reforming water s. When the reformer 20 is started, the control device 38 transmits a signal to each of the on-off valves 82v to 86v, closes the on-off valves 83v and 86v, and opens the on-off valves 82v and 84v (St1). Further, the control device 38 transmits a signal to the reformed gas on-off valve 61 (see FIG. 2) and the bypass on-off valve 63 (see FIG. 2), and closes the reformed gas on-off valve 61 and the bypass on-off valve 63. By closing the reformed gas on-off valve 61 and the bypass on-off valve 63, the heat medium w is prevented from flowing into the reforming section 21 via the reforming water pipe 85. When each of the on-off valves is in the state, the control device 38 ignites the burner of the heating unit 26 (at this time, the combustion fuel is introduced into the heating unit 26), and starts the reforming water pump 14. Then, the heat medium w flows in the order of the heating / cooling water introduction pipe 81, the heating water introduction pipe 82, the heating / cooling flow path 83, and the heating water outlet pipe 84 (hereinafter, the flow of the heat medium w in this direction is referred to as “heating direction”). (It is referred to as a direction indicated by a symbol H in FIG. 1). In this flow, the heat medium w receives heat from the reforming unit 21 when flowing through a portion adjacent to the reforming unit 21, and gives heat to the transforming unit 23 when flowing through a portion adjacent to the transforming unit 23. In addition, when flowing through a portion adjacent to the selective oxidation unit 25, heat is applied to the selective oxidation unit 25, and thereafter, it is led out of the system. By transferring the heat of the heat medium w, the time required for the transformation unit 23 and the selective oxidation unit 25 to rise to a target temperature, which will be described later, can be shortened compared to the conventional case. This shortening of the startup time also contributes to a reduction in energy consumed at startup. The heating / cooling flow path 83 when the heat medium w flows in the heating direction H forms the first heat medium flow path of the present invention.

  When the heat medium w flows in the heating direction H, the control device 38 receives temperature signals from the temperature sensors 21t, 23t, and 25t. Based on the temperature signal from the reforming section temperature sensor 21t, the control device 38 burns in the heating section 26 (typically, the amount of fuel injected) so that the temperature of the reforming section 21 does not exceed the appropriate temperature. To control. Further, the control device 38 receives temperature signals from the shift temperature sensor 23t and the selective oxidation temperature sensor 25t, and determines whether or not the temperatures of the shift temperature 23 and the selective oxidation temperature 25 have reached the target temperature (St2). ). The target temperature here may be the lower limit temperature of the appropriate temperature of each part 23, 25 (in this embodiment, the shift part 23 is 180 ° C. and the selective oxidation part 25 is 130 ° C.) or a temperature within the appropriate temperature range. The temperature may be lower than the lower limit temperature of the appropriate temperature. As described above, since the reaction in the transformation unit 23 and the selective oxidation unit 25 is an exothermic reaction, heat is generated when the reforming raw material m is input and the reaction is started, and the temperature is lower than the lower limit temperature of the appropriate temperature. Even so, the temperature of both parts 23 and 25 rises to an appropriate temperature. In view of this point, it is preferable that the target temperature is set to a temperature at which the reaction temperature is quickly brought to an appropriate temperature when the reactions in both portions 23 and 25 are started.

  In the step (St2) of determining whether or not the temperatures of the shift unit 23 and the selective oxidation unit 25 have reached the target temperature, when the target temperature has not been reached, the flow of the heat medium w in the heating direction H is maintained. When the target temperature is reached, the control device 38 transmits a signal to each of the on-off valves 82v to 86v, opens the on-off valves 83v and 86v, and closes the on-off valves 82v and 84v (St3). Then, the heat medium w flows in the order of the heating / cooling water introduction pipe 81, the heating / cooling flow path 83, the heating water introduction pipe 82, and the cooling water outlet pipe 86 (hereinafter, the flow of the heat medium w in this direction is referred to as “cooling direction”). (The direction indicated by the symbol C in FIG. 1). In this flow, the heat medium w is cooled so that the temperature of the selective oxidation unit 25 and the transformation unit 23 does not exceed the appropriate temperature, and flows through a portion adjacent to the reforming unit 21 and then is led out of the system. . Due to the flow of the heat medium w, the temperatures of the transformation unit 23 and the selective oxidation unit 25 are maintained at appropriate temperatures. The heating / cooling flow path 83 when the heat medium w flows in the cooling direction C forms the second heat medium flow path of the present invention.

  Even when the heat medium w flows in the cooling direction C, the control device 38 receives temperature signals from the temperature sensors 21t, 23t, and 25t. The control device 38 rotates the reforming water pump 14 based on the temperature signals from the shift section temperature sensor 23t and the selective oxidation section temperature sensor 25t so that the temperatures of the shift section 23 and the selective oxidation section 25 are maintained at appropriate temperatures. The flow rate of the heat medium w is adjusted by adjusting the speed. Further, the control device 38 receives the temperature signal from the reforming unit temperature sensor 21t, and determines whether or not the reforming unit 21 has reached a predetermined temperature (St4). The predetermined temperature here is a temperature at which the reforming material m can be charged into the reforming section 21 (typically a temperature at which the reforming catalyst m can act to reform the reforming material m). It is. If the reforming unit 21 has not reached the predetermined temperature, the flow of the heat medium w in the cooling direction C is maintained, and the reforming unit 21 by the heating unit 26 is maintained while maintaining appropriate temperatures of the transformation unit 23 and the selective oxidation unit 25. Continue to heat up. On the other hand, when the reforming unit 21 reaches a predetermined temperature, the control device 38 transmits a signal to each of the on-off valves 82v to 86v, 63 (see FIG. 2), and opens the bypass on-off valve 63 (see FIG. 2). And the on-off valve 86v is closed (St5). The on-off valve 83v is kept open, and the on-off valves 82v and 84v and the reformed gas on-off valve 61 (see FIG. 2) are kept closed. Then, the heat medium w is introduced into the reforming unit 21 through the reforming water pipe 85 as the reforming water s, and thereafter the steady operation is performed.

  When the reforming water s is introduced into the reforming section 21, the sections 21, 23, and 25 are at an appropriate temperature. At this time, the reforming water s (heat medium w) rises in temperature as it flows through the part adjacent to the selective oxidation unit 25 and the part adjacent to the transformation unit 23, and steam flows when flowing through the part adjacent to the reforming unit 21. It has become. Therefore, in the present embodiment, the reforming water s (heat medium w) that was liquid when flowing through the heating / cooling water introduction pipe 81 is introduced into the reforming unit 21 as steam. Hereinafter, the steady operation of the reformer 20 will be described with reference to FIG.

When the reforming water s is introduced into the reforming unit 21, the reforming material m is also introduced into the reforming unit 21. In the reforming unit 21, a steam reforming reaction as shown in the following formula (1) is performed, the reforming raw material m is reformed, and a hydrogen-rich gas r1 is generated.
CH ₄ + H ₂ O → 3H ₂ + CO (1)
In the present embodiment, methane is used as the reforming material m. As described above, the hydrogen-rich gas r1 contains about 75% by volume of hydrogen, about 10% by volume of carbon monoxide, and other gases not shown in the above formula (1) such as water vapor. It is.

The hydrogen-rich gas r1 generated in the reforming unit 21 is then sent to the shift unit 23. When the hydrogen-rich gas r1 flows through the hydrogen-rich gas flow path 22, heat exchange is performed between the hydrogen-rich gas heat exchanger 27 and the reforming water s. This heat exchange reduces the temperature of the hydrogen-rich gas r1 and increases the temperature of the reforming water s, thereby suppressing the temperature of the shift section 23 from exceeding the appropriate range and promoting the vaporization of the reforming water s. ing. When the hydrogen-rich gas r1 is introduced into the shift section 23, a shift reaction with water vapor as shown in the following equation (2) is performed by the action of the shift catalyst, and the shift gas r2 is generated.
CO + H ₂ O → H ₂ + CO ₂ (2)
During the shift reaction, the temperature of the shift section 23 is about 180 ° C to 250 ° C. The shift reaction is an exothermic reaction, and the heat generated by the shift reaction is transferred to the reforming water s flowing through the heating / cooling channel 83. The carbon monoxide concentration in the shift gas r2 is reduced to about 5000 to 10,000 ppm by the shift reaction in the shift section 23.

The shift gas r <b> 2 generated in the shift unit 23 is then sent to the selective oxidation unit 25. When the modified gas r2 flows through the modified gas flow path 24, heat is exchanged with the reforming water s in the modified gas heat exchanger 28. By this heat exchange, the temperature of the reformed gas r2 is lowered and the temperature of the reforming water s is raised, thereby suppressing the temperature of the selective oxidation unit 25 from exceeding an appropriate range and promoting the vaporization of the reforming water s. Yes. In addition to the modified gas r2, the selective oxidation air a is introduced into the selective oxidation unit 25, and a selective oxidation reaction as shown in the following equation (3) is performed to generate a reformed gas g.
2CO + O ₂ → 2CO ₂ (3)
During the selective oxidation reaction, the temperature of the selective oxidation unit 25 is about 130 ° C to 160 ° C. The selective oxidation reaction is an exothermic reaction, and the heat generated by the selective oxidation reaction is transferred to the reforming water s flowing through the heating / cooling channel 83. By the selective oxidation reaction in the selective oxidation unit 25, the carbon monoxide concentration in the reformed gas g is about 10 ppm or less. By preventing the carbon monoxide concentration in the reformed gas g from being about 10 ppm or less, the electrode catalyst of the fuel cell is prevented from being poisoned when the reformed gas g is supplied to the fuel cell 30 (see FIG. 2). Can do. The reformed gas g generated in the selective oxidation unit 25 is led out from the reformed gas pipe 51 toward the fuel cell 30 (see FIG. 2).

  Next, the operation of the fuel cell system 10 will be described with reference mainly to FIG. The reformed gas g generated by the reformer 20 is led out toward the fuel cell 30 via the reformed gas pipe 51. When the reformed gas g is first generated, the composition of the reformed gas g is started. Therefore, the reformed gas on-off valve 61 and the anode off-gas on-off valve 62 are closed, the bypass on-off valve 63 is opened, and the reformed gas g whose composition is not stable is not supplied to the fuel cell 30. Then, it is guided to the heating unit 26 of the reformer 20 and burned. When the composition of the reformed gas g produced by the reformer 20 becomes stable, the controller 38 switches the reformed gas on-off valve 61 and the anode off-gas on-off valve 62 to open and the bypass on-off valve 63 to close. The reformed gas g is introduced into the fuel cell 30. As a result, the reformed gas g is introduced into the fuel electrode of the fuel cell 30. On the other hand, the control device 38 starts the oxidant gas blower 18 and introduces the oxidant gas t into the air electrode of the fuel cell 30.

In the fuel cell 30, an electrochemical reaction is performed between hydrogen in the reformed gas g introduced into the fuel electrode and oxygen in the oxidant gas t introduced into the air electrode. In the electrochemical reaction, the reaction shown in the following formula (4) is performed on the fuel electrode side, and the reaction shown in the following formula (5) is performed on the air electrode side.
_{^{2H 2 → 4H + + 4e -}} ··· (4)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (5)
Electricity is generated by this electrochemical reaction, heat is generated, and moisture is generated. In further explanation, electric power can be obtained when electrons on the fuel electrode side move to the air electrode side through the external electric circuit. Hydrogen ions on the fuel electrode side move to the air electrode side through the solid polymer membrane, and combine with oxygen to generate moisture. This electrochemical reaction is an exothermic reaction.

  The electric power obtained by the fuel cell 30 is direct-current power, which is converted into alternating-current power by a power conditioner (not shown) as necessary and transmitted to an electric power load (not shown). On the other hand, the heat generated in the fuel cell 30 is stored, for example, in a hot water storage tank (not shown), and is consumed in a heat load such as hot water supply or heating as necessary. By effectively using the heat generated in the fuel cell 30, the efficiency of the fuel cell system 10 is improved.

  The anode off gas p is discharged from the fuel electrode of the fuel cell 30. The discharged anode off gas p is led to the reformer 20 and burned to generate reforming heat. On the other hand, the cathode offgas q is discharged from the air electrode of the fuel cell 30 and discharged outside the system through the cathode offgas pipe 55. The combustion exhaust gas e generated by the combustion of the anode off gas p and the like in the heating unit 26 of the reformer 20 is discharged out of the system through the combustion exhaust gas pipe 88. In the process in which the combustion exhaust gas e is discharged out of the system through the combustion exhaust gas pipe 88, first, heat exchange is performed with the anode off-gas p (initial reformed gas g) in the first combustion exhaust gas heat exchanger 29A. Then, heat exchange is performed with the reforming water s (heat medium w) in the second combustion exhaust gas heat exchanger 29B. In the first combustion exhaust gas heat exchanger 29A, the temperature of the combustion exhaust gas e decreases due to heat exchange, and the temperature of the anode off gas p increases, so that the exhaust heat can be used to approach the ignition temperature of the anode off gas p. In the second combustion exhaust gas heat exchanger 29B, the temperature of the combustion exhaust gas e further decreases due to heat exchange, and the temperature of the reforming water s rises, thereby suppressing the occurrence of thermal pollution and vaporizing the reforming water s. Promoted.

  In the above description, the heating / cooling flow path 83 serves as both the first heat medium flow path and the second heat medium flow path, but each may be provided separately. When the first heat medium flow path and the second heat medium flow path are formed by separate pipes, the number of on-off valves can be reduced. However, if the first heat medium flow path and the second heat medium flow path are shared by a single tube, the reformer 20 can be made compact, and the degree of freedom of installation location is improved.

  In the above description, the reformer 20 has the reforming unit temperature sensor 21t, the shift unit temperature sensor 23t, and the selective oxidation unit temperature sensor 25t, and feeds back the flow of the heat medium w (reforming water s) according to the detected temperature. Although the control is performed, the flow of the heat medium w is sequence-controlled without the temperature sensors 21t, 23t, and 25t (for example, the flow direction of the heat medium w is changed in accordance with the elapsed time from the start-up). It is good as well. If the temperature sensors 21t, 23t, and 25t are not used, the cost can be reduced. However, when feedback control is performed using each of the temperature sensors 21t, 23t, and 25t, even when a disturbance such as a change in ambient environment temperature occurs, appropriate control according to the state of the reformer 20 at that time can be performed. This enables efficient heat balance.

  In the above description, the fuel cell 30 has been described as a solid polymer fuel cell, but it may be a fuel cell other than a solid polymer fuel cell such as a phosphoric acid fuel cell. However, the polymer electrolyte fuel cell can be operated at a relatively low temperature and can be downsized, so that it is suitable for installation in a general household.

1 is a schematic system diagram of a reformer according to an embodiment of the present invention. 1 is a schematic system diagram of a fuel cell system according to an embodiment of the present invention. It is a flowchart explaining the operation | movement at the time of starting of the reforming apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell system 20 Reformer 21 Reformer 23 Transformer 25 Selective oxidizer 30 Fuel cell 83 First and second heat medium channels 85 Reforming water channel g Reformed gas m Reforming raw material r1 Hydrogen Multi-containing gas r2 Metamorphic gas w Heat medium

Claims (6)

A reforming section for introducing a reforming raw material to generate a hydrogen-rich gas rich in hydrogen;
A shift section that introduces the hydrogen-rich gas and generates a shift gas having a lower carbon monoxide concentration than the hydrogen-rich gas;
A selective oxidation unit that introduces the modified gas and generates a reformed gas having a lower carbon monoxide concentration than the modified gas;
A first heat medium flow path for flowing a heat medium in this order through a part adjacent to the reforming part, a part adjacent to the shift part, and a part adjacent to the selective oxidation part ;
Portion adjacent to the selective oxidation unit, the portion adjacent to the shift converter, e Bei a second heat medium passage for flowing a thermal medium in this order in a portion adjacent to the reforming portion;
The first heat medium flow path and the second heat medium flow path are one flow path, and the first heat medium flow path and the second heat medium flow path are in accordance with the passage of time. Configured to switch ;
A heated water outlet pipe for leading out the heat medium flowing through the first heat medium flow path that has passed through the portion adjacent to the selective oxidation section;
A cooling water outlet pipe for leading out the heat medium flowing through the second heat medium flow path that has passed through the portion adjacent to the reforming section;
The heat medium flowing through the second heat medium channel passing through the portion adjacent to the reforming portion, the reforming water passage leading to the reformer;
A heated water introduction on-off valve that blocks the flow of the heat medium introduced into the first heat medium flow path;
A cooling water introduction opening / closing valve that blocks the flow of the heat medium introduced into the second heat medium flow path;
A heated water outlet opening / closing valve for blocking the flow of the heat medium in the heated water outlet pipe;
A cooling water outlet opening / closing valve for blocking the flow of the heat medium in the cooling water outlet pipe;
In order to switch the flow so that the heat medium first flows through the first heat medium flow path and the heating water discharge pipe, and then flows through the second heat medium flow path and the cooling water discharge pipe, And further comprising a control device for controlling the heating water introduction opening / closing valve, the cooling water introduction opening / closing valve, the heating water outlet opening / closing valve, and the cooling water outlet opening / closing valve;
The heat medium is reforming water used when reforming the reforming raw material;
A reformer ;
A fuel cell that generates electricity by introducing the reformed gas and an oxidant gas containing oxygen;
Fuel cell system. A transformer temperature sensor for detecting a temperature inside the transformer;
A selective oxidation part temperature sensor for detecting a temperature inside the selective oxidation part;
When the temperature detected by the shift temperature sensor and the temperature detected by the selective oxidation temperature sensor reach a target temperature, the control device flows through the first heat medium flow path and the heating water outlet pipe. Switching the flow of the heat medium that has flown through the second heat medium flow path and the cooling water outlet pipe;
The fuel cell system according to claim 1. A reforming water pump that guides the heat medium to the first heat medium flow path and the second heat medium flow path, and to the first heat medium flow path and the second heat medium flow path A reforming water pump configured to adjust the introduction amount of the heat medium;
When the heat medium is flowing through the second heat medium flow path and the cooling water outlet pipe, the control device, based on the temperature detected by the shift temperature sensor and the selective oxidation unit temperature sensor, Adjusting the rotation speed of the reforming water pump so that the temperature of the shift section and the selective oxidation section is maintained at an appropriate temperature;
The fuel cell system according to claim 2. When the control device has passed a predetermined time from the start of the reformer, the flow of the heat medium flowing through the first heat medium flow path and the heating water outlet pipe is changed to the first heat medium flow path. Switching to flow through the two heat medium flow paths and the cooling water outlet pipe;
The fuel cell system according to claim 1 .   A reforming unit temperature sensor for detecting a temperature inside the reforming unit;
  When the temperature detected by the reformer temperature sensor reaches a predetermined temperature when the heat medium is flowing through the second heat medium flow path and the cooling water outlet pipe, the control device The heating water introduction on / off valve, the cooling water introduction on / off valve, the heating water derivation on / off valve, and the cooling water derivation on / off valve are controlled to switch the flow so that the heat medium flows through the reforming water flow path. Configured as follows;
  The fuel cell system according to any one of claims 1 to 4.   A reformed gas pipe for guiding the reformed gas derived from the selective oxidation unit to the fuel cell;
  A bypass pipe for bypassing the reformed gas so as not to be introduced into the fuel cell;
  A reformed gas on-off valve disposed in the reformed gas pipe;
  A bypass on-off valve disposed in the bypass pipe;
  The control device closes the reforming gas on-off valve and the bypass on-off valve when the reforming water does not flow into the reforming water flow path, and flows the reforming water into the reforming water flow path Configured to open the bypass on-off valve;
  The fuel cell system according to any one of claims 1 to 5.

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