JP2016025005A - Fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell device in which an excessive decrease in the temperature of a cell stack hardly occurs when an amount of power generation is small.SOLUTION: A fuel cell device includes: a reformer RF reforming raw fuel through a steam reforming reaction to produce reformed fuel and having a heating means; and a cell stack CS receiving the supply of the reformed fuel and an oxidant to generate electric power. In the fuel cell device, heat generated by the power generation of the fuel cell stack CS is transferred to the reformer RF, and an amount of heat generation of the heating means of the reformer RF is controlled in accordance with an amount of power generation of the cell stack CS or the temperature of the cell stack CS.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell device.

  A fuel cell device is a power generation device that directly converts chemical energy of a fuel and an oxidant into electrical energy. Its power generation efficiency is very high, and the discharged gas is relatively clean, so it is attracting attention as a next-generation power generation device.

  Hydrogen is used as the fuel, but at present, the hydrogen infrastructure is not sufficiently developed. For this reason, the fuel cell apparatus is generally provided with a reformer that generates hydrogen by reforming raw fuel (city gas, LPG, etc.) obtained from the existing infrastructure. A reforming catalyst is disposed inside the reformer. In the reformer, when the supplied raw fuel and steam come into contact with the reforming catalyst, a steam reforming reaction occurs and hydrogen is generated. The gas containing hydrogen is supplied from the reformer to the fuel cell stack (cell stack) as fuel.

  Since the steam reforming reaction is an endothermic reaction, it is necessary to supply heat to the reformer in order to continue the reaction. As a configuration for that purpose, there is known a fuel cell device provided with a heating burner in the vicinity of the reformer. There is also known a fuel cell device configured such that heat generated by power generation of the fuel cell stack (hereinafter also referred to as “power generation heat”) is transmitted to a reformer (for example, Patent Document 1 below).

  In the fuel cell apparatus configured to transmit the generated heat to the reformer, the fuel cell stack is cooled by taking heat away from the reformer. During rated operation where the amount of power generated by the fuel cell device is large, the temperature of the fuel cell stack is suitable for power generation by maintaining a balance between the heat generated in the fuel cell stack and the heat transmitted to the reformer. Temperature. For example, in the case of a solid oxide fuel cell device, the fuel cell stack is maintained at a high temperature of about 700 degrees.

JP-A-8-287937

  When the power generation amount is smaller than the rating (for example, at the time of startup or at a low load), the heat generated by the power generation in the fuel cell stack is also reduced. On the other hand, the amount of heat taken from the fuel cell stack by the reformer in which the steam reforming reaction occurs does not change greatly even if the power generation amount changes. As a result, when the power generation amount is small, the amount of heat taken away by the reformer becomes larger, and the temperature of the fuel cell stack further decreases. If the temperature of the fuel cell stack is too low, power generation may not be performed, which is not preferable.

  In order to prevent the temperature of the fuel cell stack from decreasing as described above, for example, the oxidant (air) supplied to the fuel cell stack is heated in advance by a burner, and the temperature is rated. It is also conceivable to supply the fuel cell stack after raising it from the time of operation. However, in such a configuration, the fuel (or raw fuel) needs to be further supplied to the burner, which may reduce the efficiency of the entire fuel cell device. In addition, the temperature of the burner may rise too much, and the burner and members disposed around it may deteriorate.

  The present invention has been made in view of such problems, and an object of the present invention is a fuel cell device configured to transmit heat generated by power generation of a fuel cell stack to a reformer, and the power generation amount is small. It is an object of the present invention to provide a fuel cell device in which the temperature of the fuel cell stack does not excessively decrease.

  In order to solve the above problems, a fuel cell device according to the present invention includes a reformer (RF) that reforms a raw fuel by a steam reforming reaction to generate a reformed fuel, a reformed fuel and an oxidant. A fuel cell stack (CS) that generates power upon receipt of the fuel, and is configured to transmit heat generated by power generation of the fuel cell stack to the reformer. (BL2) is provided.

  According to the fuel cell device of the present invention, when the heat (generated heat) transmitted from the fuel cell stack to the reformer is reduced, the temperature of the reformer can be raised by the heat generated by the heating means. It becomes possible. That is, the temperature of the fuel cell stack is prevented from being excessively lowered by adjusting the balance between the heat generated in the fuel cell stack and the heat transmitted from the fuel cell stack to the reformer by the heat generating means. be able to.

  According to the present invention, the fuel cell device is configured such that the heat generated by the power generation of the fuel cell stack is transmitted to the reformer, and the temperature of the fuel cell stack is too low when the power generation amount is small. It is possible to provide a fuel cell device that does not end up.

1 is a block diagram showing an overall configuration of a fuel cell device according to an embodiment of the present invention. It is a figure explaining the various sensors with which the fuel cell apparatus shown by FIG. 1 was equipped. It is a flowchart which shows the process performed by the control apparatus of the fuel cell apparatus shown by FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  As shown in FIG. 1, the fuel cell apparatus FS includes a casing CA, a cell stack CS (fuel cell stack), a reformer RF, a flow rate adjustment valve VV, a water supply pump WP, and a first blower BL1. And a second blower BL2 and a control unit CU.

  Casing CA is a heat-resistant container formed of stainless steel. A plate-like base plate BP arranged along a horizontal plane is fixed inside the casing CA. The internal space of the casing CA is divided into a module chamber SP1 that is a space above the base plate BP and an accessory chamber SP2 that is a space below the base plate BP. The periphery of the casing CA is covered with a heat insulating material (not shown) so that heat does not leak out from the inside of the casing CA (particularly, the module chamber SP1).

  The cell stack CS is an assembly of a plurality of fuel cells (not shown) and is disposed in the module chamber SP1. Each fuel cell is a solid oxide fuel cell (SOFC), and a fuel electrode (anode) is formed on one surface of a flat solid electrolyte, and the other surface. In this configuration, an air electrode (cathode) is formed. These fuel electrode and air electrode are both porous bodies formed of conductive ceramics. In the cell stack CS, all the fuel cells are stacked in the vertical direction, and these are electrically connected in series. Fuel gas is supplied to each fuel electrode, and air is supplied to each air electrode, whereby power generation is performed in the cell stack CS.

  In the cell stack CS, not all of the supplied fuel gas is used for power generation, and a part of the fuel gas is discharged from the cell stack CS without being used for power generation. Similarly, not all of the air supplied to the cell stack CS is used for power generation, and some air is discharged from the cell stack CS without being used for power generation. A pipe (not shown) for discharging fuel gas and air that has not been used for power generation is connected to the cell stack CS. One end of the pipe is connected to the cell stack CS, and the other end is connected to a burner (not shown) described later. The fuel gas (arrow A12) discharged from the cell stack CS is supplied to the burner through the pipe. Thereafter, the fuel gas is burned in the burner to become combustion exhaust gas, and is discharged to the outside from the fuel cell device FS.

  The reformer RF generates fuel gas (reformed fuel: hydrogen-containing gas) from city gas (raw fuel) by a steam reforming reaction, and supplies this to the cell stack CS. The reformer RF is a metal container containing a reforming catalyst therein, and is disposed in the module chamber SP1 together with the cell stack CS. The reforming catalyst is a catalyst in which a catalytic metal such as nickel is supported on the surface of an alumina sphere.

  In the module chamber SP1, the reformer RF and the cell stack CS are arranged close to each other. For this reason, when the cell stack CS becomes high temperature, the radiant heat RT from the cell stack CS reaches the reformer RF. In other words, the cell stack CS is cooled by taking heat away from the reformer RF.

  The reformer RF and the cell stack CS are connected by a pipe (not shown). Fuel gas is supplied from the reformer RF to the cell stack CS through the pipe (arrow A11).

  The flow rate adjusting valve VV is a valve for adjusting the flow rate of the city gas supplied from the external city gas supply source GS to the reformer RF. The city gas supply source GS is, for example, a gas meter. The flow rate adjusting valve VV is provided in the middle of a pipe (not shown) connecting the city gas supply source GS and the reformer RF, and is disposed in the auxiliary machine room SP2. The opening degree of the flow rate adjusting valve VV, that is, the flow rate of the city gas supplied to the reformer RF is controlled by the control unit CU.

  The water supply pump WP is a pump for supplying water from an external water supply source WS to an evaporator (not shown). The water supply pump WP is a tank that stores pure water, for example. The water supply pump WP is disposed in the auxiliary machine room SP2. The evaporator is a metal container disposed in the auxiliary machine room SP2, and is heated by a burner (not shown) to a high temperature. Instead of such a configuration, an evaporator may be arranged in the module chamber SP1, and the evaporator may be heated by radiant heat from the cell stack CS or the like.

  The water sent out from the water supply pump WP is supplied to the evaporator through a pipe (not shown), and is heated inside the evaporator to become water vapor. Thereafter, the steam is supplied to the reformer RF through a pipe (not shown). In the reformer RF, a position where a pipe for supplying water vapor from the evaporator is connected is in the vicinity of a position where a pipe for supplying city gas from the flow rate adjusting valve VV is connected. Instead of such a mode, a mode in which a mixed gas of water vapor and city gas is supplied to the reformer RF through one pipe may be used. The flow rate of water delivered from the water supply pump WP, that is, the flow rate of water vapor supplied to the reformer RF is controlled by the control unit CU.

  The first blower BL1 is a blower for supplying air from the air supply source AS to the cell stack CS. In the present embodiment, the air supply source AS is the atmosphere. The first blower BL1 is disposed in the auxiliary machine room SP2. The first blower BL1 and the cell stack CS are connected by a pipe (not shown). The air supplied from the first blower BL1 to the cell stack CS reaches the air electrode of each fuel cell, and is then used for power generation as an oxidant. For this reason, the air supplied from the first blower BL1 to the cell stack CS is hereinafter also referred to as “power generation air”. The rotational speed of the first blower BL1, that is, the flow rate of power generation air supplied to the cell stack CS is controlled by the control unit CU.

  The second blower BL2 is a blower for supplying air from the air supply source AS to the reformer RF. The second blower BL2 is disposed in the auxiliary machine room SP2. The second blower BL2 and the reformer RF are connected by a pipe (not shown). In the reformer RF, the position where the pipe for supplying air from the second blower BL2 is connected is in the vicinity of the position where the pipe for supplying city gas from the flow rate adjusting valve VV is connected. . As will be described later, when air is supplied from the second blower BL2 to the reformer RF, a partial oxidation reforming reaction occurs in the reformer RF. For this reason, the air supplied from the second blower BL2 to the reformer RF is hereinafter also referred to as “reforming air”.

  The control unit CU is a computer system that includes a CPU, a ROM, a RAM, and an input / output interface, and controls the overall operation of the fuel cell device FS. The control device CU adjusts the flow rate of the power generation air supplied to the cell stack CS by controlling the rotation speed (air flow rate) of the first blower BL1. Similarly, the flow rate of the reforming air supplied to the reformer RF is adjusted by controlling the rotation speed (air flow rate) of the second blower BL2. In addition, the flow rate of the city gas supplied to the reformer RF (also referred to as the flow rate of the fuel gas supplied to the cell stack CS) is adjusted by controlling the opening degree of the flow rate adjustment valve VV. Furthermore, the flow rate of the water vapor supplied to the reformer RF is adjusted by controlling the operation of the water supply pump WP.

  As shown in FIG. 2, the fuel cell device FS is provided with various sensors. Specifically, the fuel cell device FS includes a current sensor IS, a voltage sensor VS, a power generation air flow rate sensor AFS1, a reforming air flow rate sensor AFS2, a city gas flow rate sensor GFS, and a water flow rate sensor WFS. A cell stack temperature sensor TCS, a city gas temperature sensor TG, a reforming air temperature sensor TA, a reformer inlet temperature sensor TRI, and a reformer outlet temperature sensor TRO. The physical quantity detected by each sensor is input to the control unit CU as an electrical signal.

  The current sensor IS is a sensor that detects a current value of electric power that is taken out from the cell stack CS and output to the outside. The voltage sensor VS is a sensor that detects a voltage value of electric power that is taken out from the cell stack CS and output to the outside. Based on the current value detected by the current sensor IS and the voltage value detected by the voltage sensor VS, the control unit CU always sets the magnitude of the power output from the fuel cell device FS toward the external load. Calculate and monitor.

  The power generation air flow rate sensor AFS1 is a flow rate sensor for detecting the flow rate of power generation air supplied to the cell stack CS. The power generation air flow rate sensor AFS1 is disposed in the middle of the piping connecting the first blower BL1 and the cell stack CS, and detects the flow rate of air flowing through the piping. The control unit CU controls the operation of the first blower BL1 based on the flow rate of the power generation air detected by the power generation air flow rate sensor AFS1, so that the flow rate of the power generation air supplied to the cell stack CS is appropriate. It adjusts so that it may become (consistent with a control target value).

  The reforming air flow rate sensor AFS2 is a flow rate sensor for detecting the flow rate of the reforming air supplied to the reformer RF. The reforming air flow rate sensor AFS2 is disposed in the middle of the piping connecting the second blower BL2 and the cell stack CS, and detects the flow rate of air flowing through the piping. The control unit CU controls the operation of the second blower BL2 based on the flow rate of the reforming air detected by the reforming air flow rate sensor AFS2, thereby controlling the reforming air supplied to the reformer RF. Adjust the flow rate to be appropriate.

  The city gas flow rate sensor GFS is a flow rate sensor for detecting the flow rate of the city gas supplied to the reformer RF. The city gas flow rate sensor GFS is disposed in the middle of the pipe connecting the flow rate adjustment valve VV and the reformer RF, and detects the flow rate of the city gas flowing through the pipe. The control unit CU controls the opening degree of the flow rate adjustment valve VV based on the flow rate of the city gas detected by the city gas flow rate sensor GFS, so that the flow rate of the city gas supplied to the reformer RF becomes appropriate. Adjust as follows.

  The water flow rate sensor WFS is a flow rate sensor for detecting the flow rate of water supplied to the evaporator. The water flow rate sensor WFS can also be referred to as a sensor that detects the amount of water vapor supplied to the reformer RF. The water flow rate sensor WFS is disposed in the middle of the pipe connecting the water supply pump WP and the evaporator, and detects the flow rate of water flowing through the pipe. The control unit CU controls the operation of the water supply pump WP based on the flow rate of water detected by the water flow rate sensor WFS, so that the flow rate of water supplied to the evaporator (the supply amount of water vapor to the reformer RF) is controlled. ) To be appropriate.

  The cell stack temperature sensor TCS is a temperature sensor for detecting the temperature of the cell stack CS. The cell stack temperature sensor TCS is attached in the vicinity of the position on the most upstream side of the piping for discharging the fuel gas from the cell stack CS. That is, the cell stack temperature sensor TCS directly detects the temperature of the fuel gas immediately after being discharged from the cell stack CS. The temperature is substantially equal to the temperature of the cell stack CS. As will be described later, the control unit CU adjusts the rotation speed of the second blower BL2 based on the temperature of the cell stack CS detected by the cell stack temperature sensor TCS.

  The city gas temperature sensor TG is a temperature sensor for detecting the temperature of the city gas supplied to the reformer RF. The city gas flow rate sensor GFS is attached in the vicinity of the most downstream position in the piping connecting the flow rate adjustment valve VV and the reformer RF. That is, the city gas temperature sensor TG detects the temperature of the city gas immediately before being supplied to the reformer RF. As will be described later, the control unit CU adjusts the flow rate of the reforming air supplied to the reformer RF based on the temperature of the city gas detected by the city gas temperature sensor TG.

  The reforming air temperature sensor TA is a temperature sensor for detecting the temperature of the reforming air supplied to the reformer RF. The reforming air temperature sensor TA is attached in the vicinity of the position on the most downstream side of the piping connecting the second blower BL2 and the cell stack CS. That is, the reforming air temperature sensor TA detects the temperature of the reforming air immediately before being supplied to the reformer RF. As will be described later, the control unit CU adjusts the flow rate of the reforming air supplied to the reformer RF based on the temperature of the reforming air detected by the reforming air temperature sensor TA.

  The reformer inlet temperature sensor TRI is a temperature sensor for detecting the temperature of the upstream portion of the reformer RF. The reformer inlet temperature sensor TRI is attached in the vicinity of an upstream portion of the reformer RF, that is, a portion to which a pipe for supplying city gas from the flow rate adjusting valve VV is connected (city gas inlet). It has been. As will be described later, the control unit CU adjusts the flow rate of the reforming air supplied to the reformer RF based on the temperature of the reformer RF detected by the reformer inlet temperature sensor TRI.

  The reformer outlet temperature sensor TRO is a temperature sensor for detecting the temperature of the downstream portion of the reformer RF. The reformer outlet temperature sensor TRO is attached in the vicinity of the downstream portion of the reformer RF, that is, the portion where the pipe for supplying the fuel gas to the cell stack CS is connected (fuel gas outlet). ing. As will be described later, the control unit CU adjusts the flow rate of the reforming air supplied to the reformer RF based on the temperature of the reformer RF detected by the reformer outlet temperature sensor TRO.

  The operation of the fuel cell device FS will be described. In the cell stack CS, power is generated by receiving the supply of fuel gas from the reformer RF and the supply of power generation air from the first blower BL1. Along with power generation, heat is generated in the cell stack CS. For this reason, during the operation of the fuel cell device FS, the cell stack CS is heated by the generated heat, and the radiant heat RT from the cell stack CS is dissipated to the surroundings.

  In a state where the second blower BL2 is stopped, only the city gas and water vapor are supplied to the reformer RF. At this time, only the steam reforming reaction occurs inside the reformer RF. Since the steam reforming reaction is an endothermic reaction, it is necessary to supply heat from the outside in order to continue the reaction.

  As already described, in the present embodiment, the reformer RF and the cell stack CS are arranged in a state of being close to each other so that a part of the radiant heat RT from the cell stack CS reaches the reformer RF. It has become a structure. In the reformer RF, the radiant heat RT is used for the steam reforming reaction, so that the steam reforming reaction continuously occurs.

  Further, the cell stack CS is cooled by taking part of the generated heat by the reformer RF. When the power generated in the cell stack CS is relatively large and is at or close to the rated power, the balance between the heat generated in the cell stack CS and the heat transmitted to the reformer RF is maintained. The temperature of the cell stack CS is maintained at a temperature (700) suitable for power generation.

  It is not only the generated heat and the radiant heat that affect the temperature of the cell stack CS during the operation of the fuel cell device FS. In addition to these, power generation air supplied from the first blower BL1 and fuel gas supplied from the reformer RF to the cell stack CS also affect the temperature of the cell stack CS. The control unit CU performs control such that the temperature of the cell stack CS is maintained in the vicinity of 700 degrees by controlling the rotation speed and the like of the first blower BL1. This control will be described in detail later.

  The fuel cell device FS is configured to perform an operation for adjusting the electric power to be generated according to the increase or decrease of the output electric power, that is, a so-called load following operation. For this reason, when the demand power of the external load decreases, the power generated by the cell stack CS is reduced, and the generated heat generated in the cell stack CS is also reduced.

  On the other hand, when only the steam reforming reaction occurs in the reformer RF, the temperature of the reformer RF does not change greatly even if the generated power changes. That is, the amount of heat taken from the cell stack CS by the reformer RF does not change greatly even if the power generation amount changes. For this reason, when the amount of power generation is small, the amount of heat taken away by the reformer RF is larger than the amount of heat generated by the cell stack CS, so that the temperature of the cell stack CS decreases. Become.

  Therefore, in the fuel cell device FS according to the present embodiment, when the generated heat in the cell stack CS becomes small, the reformer RF is supplied with reforming air by operating the second blower BL2. It is configured to supply. When reforming air is supplied to the reformer RF, a partial oxidation reforming reaction occurs in addition to the steam reforming reaction inside the reformer RF. Unlike the steam reforming reaction, which is an endothermic reaction, the partial oxidation reforming reaction is an exothermic reaction. For this reason, the temperature of the reformer RF can be raised by operating the second blower BL2 to cause the partial oxidation reforming reaction. The second blower BL2 and the pipe connecting the second blower BL2 and the reformer RF can be referred to as “heating means” that generates heat (partial oxidation reforming reaction) inside the reformer RF.

  When operating the second blower BL2, the water supply pump WP may be stopped. That is, an operation may be performed in which only the partial oxidation reforming reaction is caused in the reformer RF and the steam reforming reaction is not caused. In this case, since the calorific value in the reformer RF increases, for example, the cell stack CS whose temperature has been lowered can be heated by the reformer RF.

  Details of the control performed by the control unit CU will be described with reference to FIG. During the operation of the fuel cell device FS, the control unit CU repeatedly executes the control shown in the flowchart of FIG.

  Based on the current value detected by the current sensor IS and the voltage value detected by the voltage sensor VS, the control unit CU outputs power from the fuel cell device FS to the external load, that is, the amount of power generated by the cell stack CS. Is always calculated and sampled. In step S01, it is determined whether or not the change in the sampled power generation amount (the absolute value of the difference from the previously sampled power generation amount) exceeds a predetermined threshold. If the change in the power generation amount exceeds the threshold value, the process proceeds to step S02.

  In step S02, the target value of the fuel gas supply amount is determined so that the fuel gas supply amount to the cell stack CS becomes a supply amount suitable for the current power generation amount. At the same time, the target value of the supply amount of power generation air is determined so that the supply amount of power generation air to the cell stack CS becomes a supply amount suitable for the current power generation amount. The target value of the supply amount of power generation air may be determined based on the temperature of the cell stack CS. When the process of step S02 is completed, the process proceeds to step S03.

  In step S03, the control unit CU adjusts the amount of city gas supplied to the reformer RF by adjusting the opening of the flow rate adjusting valve VV so that the amount of fuel gas supplied to the cell stack CS is equal to the target value. . By the way, the relationship between the target value of the fuel gas supply amount and the corresponding city gas supply amount varies depending on the ratio of the steam reforming reaction and the partial oxidation reforming reaction performed in the reformer RF. . For this reason, the control unit CU adjusts the opening degree of the flow rate adjustment valve VV based on the ratio. When the process of step S03 is completed, the process proceeds to step S04.

  In step S04, the control unit CU adjusts the rotation speed of the first blower BL1 so that the amount of power generation air supplied to the cell stack CS is equal to the target value. When the process of step S04 is completed, the process proceeds to step S05.

  In step S05, heat generated by the power generation of the cell stack CS is calculated. The power generation heat is calculated by subtracting the actual power generation amount from the power generation amount when the power generation efficiency is 100%. “The amount of power generation when the power generation efficiency is 100%” means the current value detected by the current sensor IS at the voltage of the cell stack CS (1.23 V × the number of fuel cells) when the power generation efficiency is 100%. This is the amount of power generated by multiplying by. When the process of step S05 is completed, the process proceeds to step S06.

  In step S06, the amount of heat (cooling amount) taken from the reformer RF by various gases (city gas, water vapor, and reforming air) supplied to the reformer RF is calculated. In other words, the total amount of heat applied to the various gases when passing through the reformer RF is calculated. The amount of cooling depends on the temperature of the inlet portion of the reformer RF detected by the reformer inlet temperature sensor TRI, the temperature of the outlet portion of the reformer RF detected by the reformer outlet temperature sensor TRO, and It is calculated by the control unit CU based on the flow rate and specific heat of each of various gases supplied to the mass device RF. When the process of step S06 is completed, the process proceeds to step S07.

  In step S07, the heat absorption amount of the reformer RF necessary for setting the temperature of the cell stack CS to a temperature suitable for power generation is calculated. “The endothermic amount of the reformer RF” is the amount of heat obtained by subtracting the exothermic amount due to the exothermic reaction (partial oxidation reforming reaction) from the endothermic amount due to the endothermic reaction (steam reforming reaction) occurring inside the reformer RF. That is. The necessary endothermic amount can be obtained by subtracting the “heat amount (cooling amount) taken from the reformer RF by various gases” calculated in step S06 from the generated heat calculated in step S05. When the process of step S07 is completed, the process proceeds to step S08.

  In step S08, the supply amount of reforming air necessary to match the actual “endothermic amount of the reformer RF” with the “necessary endothermic amount” calculated in step S07 is calculated. Such calculation is performed based on the theoretical value of the reforming rate obtained based on the shape and temperature of the reformer RF. In addition, instead of such a mode, the relationship between the temperature of the reformer RF detected by the cell stack temperature sensor TCS and the optimal amount of reforming air supplied at the temperature is obtained in advance through experiments or the like. Alternatively, the relationship between the two may be stored as a table. When the process of step S08 is completed, the process proceeds to step S09.

  In step S09, the rotation speed of the second blower BL2 is adjusted by the control unit CU so that the supply amount of reforming air to the reformer RF matches the supply amount calculated in step S08. As a result, the amount of heat generated inside the reformer RF is adjusted, and the temperature of the reformer RF changes. As a result, the amount of heat taken from the cell stack CS as the radiant heat RT becomes an optimum value, and the temperature of the cell stack CS is maintained at a temperature suitable for power generation.

  If the change in power generation amount does not exceed the threshold value in step S01, the process proceeds to step S10. In step S10, it is determined whether or not the temperature of the cell stack CS measured by the cell stack temperature sensor TCS is higher than a predetermined threshold value TH1. When the temperature of the cell stack CS is higher than the threshold value TH1, the process proceeds to step S11.

  In step S11, the control unit CU reduces the amount of reforming air supplied to the reformer RF by reducing the rotational speed of the second blower BL2. As a result of the reduction in the supply amount of the reforming air, the exothermic reaction (partial oxidation reforming reaction) occurring in the reformer RF is suppressed, and the temperature of the reformer RF decreases to fall below the threshold value TH1. .

  In step S10, when the temperature of the cell stack CS is equal to or lower than the threshold value TH1, the process proceeds to step S20. In step S20, it is determined whether or not the temperature of the cell stack CS measured by the cell stack temperature sensor TCS is lower than a predetermined threshold value TH2. The threshold value TH2 is set as a value lower than the threshold value TH1. When the temperature of the cell stack CS is lower than the threshold value TH2, the process proceeds to step S21.

  In step S21, the control unit CU increases the amount of reforming air supplied to the reformer RF by increasing the rotational speed of the second blower BL2. As a result of the increase in the supply amount of reforming air, the exothermic reaction (partial oxidation reforming reaction) occurring in the reformer RF is promoted, and the temperature of the reformer RF rises and falls below the threshold value TH2. .

  In step S20, when the temperature of the cell stack CS is equal to or higher than the threshold value TH2, the temperature of the cell stack CS is an appropriate temperature (threshold value TH2 or higher and lower than the threshold value TH1). The control device CU ends the process without changing the rotational speed of the second blower BL2.

  As described above, in the fuel cell device FS according to the present embodiment, the exothermic reaction (partial oxidation reforming reaction) generated in the reformer RF is adjusted by the control performed by the control unit CU, and thereby the cell stack CS. The fluctuation of temperature is suppressed. Specifically, the exothermic reaction that occurs in the reformer RF is adjusted by adjusting the amount of reforming air supplied to the reformer RF.

  Instead of such an embodiment, an electric heater HT may be attached to the reformer RF, and the reformer RF may be heated by the electric heater HT. In FIG. 1, the attachment position of the electric heater HT in such a configuration is indicated by a dotted line. The electric heater HT generates heat by consuming a part of the electric power generated by the cell stack CS, and heats substantially the entire reformer RF from the outside.

  In such an embodiment, the control unit CU replaces the supply amount of the reforming air to the reformer RF (steps S09, S11, S21 in FIG. 3), and the energization amount to the electric heater HT. By adjusting the temperature, the temperature of the cell stack CS can be adjusted to a temperature suitable for power generation.

  Further, for example, instead of increasing (decreasing) the rotation speed of the second blower BL2, the endothermic amount of the reformer RF is adjusted by decreasing (increasing) the amount of steam supplied to the reformer RF. Also good.

  In the present embodiment, the control unit CU adjusts the supply amount of reforming air based on the power generation amount of the cell stack CS (step S09), and also uses the temperature of the cell stack CS for reforming. The supply amount of air is adjusted (steps S11 and S21). As a result, the temperature of the cell stack CS can be maintained within the optimum temperature range even when an error occurs in the adjustment of the supply amount of reforming air based on the power generation amount.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

FS: Fuel cell device CS: Cell stack RF: Reformer BL1: First blower BL2: Second blower CU: Control device HT: Electric heater

Claims (9)

A reformer (RF) that reforms the raw fuel by a steam reforming reaction to generate a reformed fuel;
A fuel cell stack (CS) that generates electricity by receiving the supply of the reformed fuel and the oxidant,
The heat generated by the power generation of the fuel cell stack is configured to be transmitted to the reformer,
The reformer is provided with a heat generating means (BL2).   2. The fuel cell device according to claim 1, further comprising a control unit (CU) that controls a heat generation amount in the heat generating unit so as to suppress a change in temperature of the fuel cell stack.   The fuel cell device according to claim 2, wherein the heat generating means causes a partial oxidation reforming reaction in the reformer.   4. The fuel cell device according to claim 3, wherein the control unit controls a heat generation amount in the heat generation unit by adjusting a supply amount of air to the reformer. 5.   4. The fuel cell device according to claim 3, wherein the control unit controls a heat generation amount in the heat generation unit by adjusting a supply amount of water vapor to the reformer. 5.   The fuel cell apparatus according to claim 2, wherein the heat generating means is an electric heater (HT).   3. The fuel cell device according to claim 2, wherein the control unit controls a heat generation amount in the heat generation unit based on a temperature of the fuel cell stack.   3. The fuel cell device according to claim 2, wherein the control unit controls a heat generation amount in the heat generation unit based on a power generation amount in the fuel cell stack.   9. The fuel cell apparatus according to claim 8, wherein the control means increases the heat generation amount in the heat generation means when the power generation amount in the fuel cell stack decreases.

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