JP2009007222A - Control unit of reformer for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control unit of a reformer for a fuel cell to keep a stable burning condition of a combustion burner during the on-off of a water supply route which supplies the water removed from anode gas etc. to a water storage tank, in a reformer for a fuel cell equipped with a combustion burner to heat the reforming catalyst. <P>SOLUTION: This control unit determines (S14) the supply quantity of the air to the combustion burner to heat the reforming catalyst, controls the water quantity of the removed water, which is the water removed from at least either one of anode gas supplied to the fuel cell and anode off gas discharged from the fuel cell and supplied to the water storage tank by opening or shutting of the water supply route, and, on one hand, corrects (S22-S26) the quantity of the air supply which is determined complying with the output of a discharge gas sensor equipped in the discharge gas line of the combustion burner and, on the other hand, keeps (S30) the quantity of the corrected air supply, when the water supply route is opened or shut. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a fuel cell reformer, and more specifically to a control device for a fuel cell reformer including a combustion burner that burns anode off gas and air to heat a reforming catalyst.

Conventionally, various control devices for a reformer for a fuel cell, in which fuel and water vapor are reformed into an anode gas by a reforming catalyst and supplied to the fuel cell, have been proposed. For example, the technique described in Patent Document 1 includes a combustion burner that heats the reforming catalyst by burning anode off-gas and air discharged from the fuel cell, and the flow rate of fuel supplied to the reformer. The amount of air supplied to the combustion burner is determined based on the above, and the correction is calculated by adding the correction amount calculated based on the temperature of the reforming catalyst to the determined air supply amount. The temperature of the reforming catalyst is adjusted while stabilizing the state.
Japanese Patent Laid-Open No. 08-45221 (paragraphs 0002, 0006 to 0008, FIG. 20, etc.)

  By the way, since both the anode gas and the anode off gas contain a large amount of moisture, if the anode gas is directly supplied to the fuel cell, the moisture is condensed inside the fuel cell and the gas passage is blocked, thereby reducing the output of the fuel cell. Inconvenience occurs. Further, if the anode off gas is directly supplied to the combustion burner, it may cause incomplete combustion or misfire. These problems can be solved by forcibly cooling the anode gas and the like to condense and remove moisture.

  The water removed from the gas is generally supplied to a water storage tank through a water supply path and used for reforming water or the like. When configured in this way, in order to prevent anode gas and the like from leaking outside through the water storage tank, the moisture is temporarily stored in the moisture supply path by inserting a shutoff valve in the moisture supply path, and the anode It is necessary to open and close the shut-off valve so that gas or the like does not flow out to the water storage tank, and to allow only water to flow into the water storage tank.

  However, if the above-described configuration for removing moisture in the gas is applied as it is to the technique described in Patent Document 1, there may be a disadvantage that it is difficult to maintain a stable combustion state in the combustion burner. That is, when the shutoff valve of the moisture supply path is opened and closed, the gas flow velocity changes and the pressure fluctuates in the piping through which the anode gas and the like are circulated. There is a possibility that the sensor output may fluctuate rapidly due to adhesion to a sensor or the like. When the sensor output fluctuates, the correction amount of air is not accurately calculated. As a result, there may be a disadvantage that a stable combustion state cannot be maintained in the combustion burner.

  Accordingly, an object of the present invention is to solve the above-described problems, and in a fuel cell reformer having a combustion burner for heating the reforming catalyst, a moisture supply path for supplying moisture removed from the anode gas or the like to the water storage tank An object of the present invention is to provide a control device for a reformer for a fuel cell that maintains a stable combustion state in a combustion burner when opening and closing the fuel.

  In order to solve the above-mentioned object, according to claim 1, the reforming catalyst for reforming the fuel into the anode gas, the anode off-gas discharged from the fuel cell, and the air are combusted to heat the reforming catalyst. A reformer for a fuel cell comprising a combustion burner, an air supply amount determination means for determining an air supply amount to the combustion burner, an anode gas supplied to the fuel cell, and an anode discharged from the fuel cell Moisture removing means for removing moisture contained in at least one of the off-gases, a moisture supply path for supplying the removed moisture to the water storage tank, and moisture for adjusting the supply amount of moisture by opening and closing the moisture supply path In a control device for a fuel cell reformer comprising a supply amount adjusting means, the supply of the air determined according to the output of an exhaust gas sensor provided in an exhaust gas discharge path of the combustion burner. With an air supply amount correcting means for correcting the amount of the air supply amount correcting means, when said water supply passage is opened and closed, and configured to hold a supply amount of the corrected air.

  The fuel supply amount detection means for detecting the supply amount of fuel reformed to anode gas by the reforming catalyst, the output current detection means for detecting the output current of the fuel cell, and An anode off-gas discharge amount estimating means for estimating a discharge amount of anode off-gas discharged from the fuel cell based on at least one of the detected fuel supply amount and output current; and the air supply amount determination means Is configured to determine the supply amount of the air based on the estimated discharge amount of the anode off gas.

  According to a third aspect of the present invention, the exhaust gas sensor is configured to include either an air-fuel ratio sensor or an oxygen concentration sensor.

  According to a fourth aspect of the present invention, the moisture removing unit condenses moisture contained in at least one of the anode gas supplied to the fuel cell and the anode off-gas discharged from the fuel cell to generate condensed water. It comprised so that it might consist of a condenser and the gas-liquid separator which isolate | separates and removes the condensed water condensed with the said condenser from gas.

  In the control device for a fuel cell reformer according to claim 1, the amount of air supplied to the combustion burner for heating the reforming catalyst is determined, and the anode gas supplied to the fuel cell and the exhaust from the fuel cell are determined. The moisture is removed from at least one of the anode off-gas to be supplied, and the moisture supply path for supplying the removed moisture to the water storage tank is opened and closed to adjust the amount of moisture supply, and is provided in the exhaust gas line of the combustion burner. Since the determined air supply amount is corrected according to the output of the exhaust gas sensor, while the moisture supply path is opened and closed, the corrected air supply amount is maintained. When opening and closing, a stable combustion state can be maintained in the combustion burner.

  Specifically, when the moisture supply path is opened and closed by, for example, a shutoff valve or the like, a change in gas flow velocity or a change in pressure occurs in the piping through which the anode gas or anode off gas flows, thereby causing, for example, moisture in the gas to flow. There is a possibility that the output of various sensors (specifically, exhaust gas sensors) fluctuates due to scattering. If the output of the exhaust gas sensor fluctuates, the determined air supply amount may not be accurately corrected. However, as described above, the corrected air supply amount is maintained when the moisture supply path is opened and closed. In other words, the air supply amount is not corrected according to the output of the exhaust gas sensor when the moisture supply path is opened and closed, and the previously corrected air supply amount is maintained. Therefore, even when the flow velocity or pressure in the pipe through which the anode gas or the like is circulated changes due to the opening and closing of the moisture supply path, a stable combustion state can be maintained in the combustion burner without being affected by the influence.

  In the control device for the reformer for a fuel cell according to claim 2, the supply amount of the fuel reformed into the anode gas by the reforming catalyst and the output current of the fuel cell are detected, and the detected fuel is detected. It is configured to estimate the amount of anode offgas discharged from the fuel cell based on at least one of the amount supplied and the output current, and to determine the amount of air supplied based on the estimated amount of anode offgas discharged Therefore, in addition to the above-described effects, the amount of air supplied to the combustion burner can be accurately determined according to the operating state of the reformer and the fuel cell.

  In the control device for a fuel cell reformer according to claim 3, the exhaust gas sensor is configured to include either an air-fuel ratio sensor or an oxygen concentration sensor. Since the oxygen concentration can be accurately detected, the determined supply amount of air can be corrected more accurately.

  In the control device for a fuel cell reformer according to claim 4, the moisture removing means supplies moisture contained in at least one of the anode gas supplied to the fuel cell and the anode off-gas discharged from the fuel cell. Since it is composed of a condenser that condenses to produce condensed water and a gas-liquid separator that separates and removes the condensed water condensed in the condenser from the gas, in addition to the above effects, anode gas and anode Moisture contained in the off-gas can be reliably removed, thus effectively preventing problems such as a decrease in output caused by moisture condensation inside the fuel cell, incomplete combustion and misfire in the combustion burner. it can.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a control device for a fuel cell reformer according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing a fuel cell reformer control device according to an embodiment of the present invention including a fuel cell as a whole.

  In FIG. 1, reference numeral 10 denotes a fuel cell. The fuel cell 10 is a single cell comprising an electrolyte membrane (solid polymer membrane), a cathode electrode (air electrode) and an anode electrode (fuel electrode) that sandwich the membrane, and a separator disposed outside each electrode. This is a known solid polymer fuel cell having a stack (all not shown) formed by stacking a plurality of (cells).

  The fuel cell 10 includes a cathode gas supply system 12 that supplies cathode gas (reaction air) to the cathode electrode, an anode gas supply system 14 that supplies anode gas (reformed gas) to the anode electrode, and the fuel cell 10 generates the fuel cell 10. A power control system 16 for controlling the power to be connected is connected.

  The cathode gas supply system 12 includes a cathode gas supply path 20 that supplies the cathode gas, and a cathode offgas discharge path 22 that discharges (exhausts) the cathode offgas discharged from the fuel cell 10 to the outside. Connected to the cathode gas supply path 20 is a cathode gas pump 24 that sucks air and pumps it as a cathode gas to the fuel cell 10. Further, a humidifier 26 is disposed in the middle of the cathode gas supply path 20 and the cathode offgas discharge path 22, where the cathode gas is humidified by the cathode offgas or the like.

  The anode gas supply system 14 reforms reformed fuel (fuel, for example, city gas mainly composed of methane), and generates fuel containing anode gas containing hydrogen to be supplied to the anode electrode of the fuel cell 10. A battery reformer (hereinafter simply referred to as “reformer”) 30, a first anode gas supply path 32 a that connects the reformer 30 and the fuel cell 10 and supplies anode gas to the fuel cell 10; The fuel cell 10 and a combustion burner (described later) of the reformer 30 are connected to each other, and an anode off gas supply path 34 for supplying anode off gas to the combustion burner is provided.

  The reformer 30 is connected to the reformed fuel pipe 30a into which the reformed fuel or the like flows, the reformed catalyst 30b that reacts the reformed fuel with water vapor to reform the anode gas, and the reformed fuel pipe 30a. A reforming pipe 30c filled with the reforming catalyst 30b, an anode gas pipe 30d connected to the reforming pipe 30c and discharging the anode gas reformed by the reforming catalyst 30b, and the fuel cell 10 Combustion burner 30e for heating the reforming catalyst 30b and the like by burning the anode off-gas and air discharged from the combustion chamber, and an exhaust pipe 30f connected to the combustion burner 30e and exhausting the exhaust gas generated by the combustion. A temperature sensor 30g is attached in the vicinity of the reforming catalyst 30b, and the temperature sensor 30g outputs a signal corresponding to the temperature of the reforming catalyst 30b.

  A reformed fuel pipe 30 a of the reformer 30 is stored in a reformed fuel supply path 36 for supplying a reformed fuel from a reformed fuel supply source (not shown) and a reformed water tank (water storage tank) 38. A reforming water supply path 40 for supplying reforming water (pure water used for reforming) is connected. In the reformed fuel supply path 36, a desulfurizer 42 that removes an odorant of the reformed fuel, such as an organic sulfur compound, and a flow rate of the reformed fuel that passes through the downstream side of the desulfurizer 42, in other words, A flow rate sensor (fuel supply amount detection means) 44 for detecting the supply amount of the reformed fuel that is subjected to anode gas reforming by the reforming catalyst 30b is provided. The flow sensor 44 outputs a signal corresponding to the supply amount of the reformed fuel. In this specification, “downstream” means downstream in the flow direction of gas or liquid (fluid) flowing therethrough.

  On the other hand, in the reforming water supply path 40, a water supply pump 46 that pumps the reforming water to the reformer 30, an ion filter 48 that removes impurities contained in the reforming water on the downstream side of the water pump 46, and an ion A first shut-off valve 50 that opens and closes the reforming water supply path 40 is installed on the downstream side of the filter 48.

  In addition, an air supply path 52 that supplies combustion air (hereinafter simply referred to as “air”) or the like is connected to the combustion burner 30 e of the reformer 30. The air supply path 52 is provided with an air pump 54 that pumps air toward the combustion burner 30e, and a flow rate adjustment valve 56 that adjusts the flow rate (supply amount) of air on the downstream side of the air pump 54. In the air supply path 52 downstream of the flow rate adjustment valve 56, when the fuel cell 10 is started, in other words, when the anode off-gas is not discharged from the fuel cell 10, for example, the city gas is supplied as heating fuel. A fuel supply path 58 is connected.

  An exhaust gas exhaust path 60 for exhausting exhaust gas to the outside (exhaust) is connected to the exhaust port 30f1 of the exhaust gas pipe 30f of the reformer 30, and an exhaust gas sensor 62 is provided in the middle of the exhaust gas exhaust path 60. Specifically, the exhaust gas sensor 62 includes either an air-fuel ratio sensor or an oxygen concentration sensor, and outputs a signal corresponding to the oxygen concentration in the exhaust gas.

  Connected to the first anode gas supply path 32a is a second anode gas supply path 32b that allows the first anode gas supply path 32a and the anode off-gas supply path 34 to communicate with each other. A second shutoff valve (solenoid valve) 64 that opens and closes the second anode gas supply path 32b is interposed in the second anode gas supply path 32b. The second shut-off valve 64 is closed when not energized. When the amount of anode gas required in the fuel cell 10 decreases, the second shut-off valve 64 is energized and opened, and the anode gas is opened via the second anode gas supply path 32b. To the anode off gas supply path 34.

  A third shutoff valve 66 for opening and closing the first anode gas supply path 32a is inserted downstream of the connection position of the second anode gas supply path 32b in the first anode gas supply path 32a. On the downstream side, an anode gas condenser (condenser; moisture removing means) 68 that condenses the moisture contained in the anode gas to generate condensed water, and the condensed water condensed by the anode gas condenser 68 from the anode gas. An anode gas gas-liquid separator (gas-liquid separator, moisture removing means) 70 to be separated and removed is connected.

  The anode gas condenser 68 is connected to a cooling water supply path 68a for supplying cooling water for cooling the anode gas, whereby the anode gas is cooled by the cooling water to condense the moisture and produce condensed water. Thus, the anode gas condenser 68 functions as a heat exchanger that cools the anode gas by exchanging heat with the cooling water.

  An anode gas condensed water tank 72 for storing the separated condensed water is connected to the anode gas gas-liquid separator 70. At an appropriate position of the anode gas condensate water tank 72, a water amount sensor 72a for detecting that the amount of water in the anode gas condensate water tank 72 is a predetermined value or more is provided. The water amount sensor 72a outputs an on signal when the amount of water in the anode gas condensate water tank 72 is equal to or greater than a predetermined value, and outputs an off signal when it is less than the predetermined value.

  Connected to the anode gas condensed water tank 72 is an anode gas moisture supply path (moisture supply path) 74 for supplying the condensed water stored, that is, moisture removed from the anode gas, to the above-described reformed water tank 38. . A fourth shut-off valve (moisture supply amount adjusting means) 76 that adjusts the supply amount of moisture by opening and closing the anode gas moisture supply passage 74 is interposed in the middle of the anode gas moisture supply passage 74, and A reforming water tank 38 is connected downstream of the fourth shutoff valve 76. Therefore, the condensed water obtained by condensing the moisture contained in the anode gas by the anode gas condenser 68 is the anode gas gas-liquid separator 70, the anode gas condensed water tank 72, the anode gas moisture supply path 74, and the fourth cutoff. It is supplied to the reforming water tank 38 via the valve 76 and stored (recovered) as reforming water.

  A fifth shut-off valve 80 that opens and closes the anode off gas supply path 34 is interposed in the anode off gas supply path 34. The fifth shut-off valve 80, the first and third shut-off valves 50 and 66, and the flow rate adjusting valve 56 described above are all electromagnetic valves, and the anode gas and the like flow out to the outside when the fuel cell 10 is not in operation. In order to prevent this, it is assumed that all the fuel cells 10 are closed at the end of the operation.

  An anode off-gas condenser (condenser; moisture removing means) 82 for condensing moisture contained in the anode off-gas to generate condensed water downstream of the fifth shutoff valve 80 in the anode off-gas supply path 34, and anode off-gas An anode off-gas gas-liquid separator (gas-liquid separator, moisture removing means) 84 that separates and removes the condensed water condensed by the condenser 82 from the anode off-gas is connected.

  The anode off-gas condenser 82 and the anode off-gas gas / liquid separator 84 are configured in substantially the same manner as the anode gas condenser 68 and the anode gas / gas separator 70 described above. More specifically, the anode off-gas condenser 82 is connected to a cooling water supply path 82a for supplying cooling water for cooling the anode off-gas, whereby the anode off-gas is cooled by the cooling water to condense and condense moisture. Water is produced. Thus, the anode offgas condenser 82 functions as a heat exchanger that cools the anode offgas by exchanging heat with the cooling water.

  An anode off-gas condensate water tank 86 for storing the separated condensed water is connected to the anode off-gas gas-liquid separator 84. A water amount sensor 86 a is provided at an appropriate position of the anode off-gas condensed water tank 86. The water amount sensor 86a outputs an on signal when the amount of water in the anode off-gas condensate water tank 86 is equal to or greater than a predetermined value, and outputs an off signal when it is less than the predetermined value.

  Connected to the anode off-gas condensed water tank 86 is an anode off-gas moisture supply path (moisture supply path) 90 that supplies the condensed water stored, that is, moisture removed from the anode off-gas, to the reformed water tank 38. A sixth shut-off valve (moisture supply amount adjusting means) 92 that adjusts the supply amount of moisture by opening and closing the anode offgas moisture supply passage 90 is inserted in the middle of the anode offgas moisture supply passage 90, and the sixth A reforming water tank 38 is connected to the downstream side of the shutoff valve 92. Therefore, the condensed water obtained by condensing the moisture contained in the anode off-gas in the anode off-gas condenser 82 is the anode off-gas gas-liquid separator 84, the anode off-gas condensed water tank 86, the anode off-gas moisture supply path 90, and the sixth cutoff. It is supplied to the reforming water tank 38 via the valve 92 and stored (recovered) as reforming water.

  The sixth shut-off valve 92 and the above-described fourth shut-off valve 76 are both electromagnetic valves, and their operations are controlled based on signals from the corresponding water volume sensors 72a and 86a, which will be described later. .

  The power control system 16 converts an electric control unit (Electronic Control Unit; hereinafter referred to as “ECU”) 100 including a microcomputer and the power (DC current) generated by the fuel cell 10 into an AC current having a predetermined frequency. And an inverter 104 that outputs to an electric load (AC power supply device) 102 and the like, and is connected to an output terminal 106 that outputs electric power generated in the fuel cell 10.

  A current sensor (output current detection means) 110 that detects the output current of the fuel cell 10 is connected to the electric wire connecting the inverter 104 and the electric load 102, and outputs a signal corresponding to the output current of the fuel cell 10. The ECU 100 receives signals from the current sensor 110, the temperature sensor 30g, the flow rate sensor 44, the exhaust gas sensor 62, the water amount sensors 72a and 86a, etc. via the signal line 112, and based on the signals of the inputted sensors. The operation of the auxiliary devices such as the flow rate adjusting valve 56, the first to sixth shutoff valves 50, 64, 66, 76, 80, 92 and the water pump 46 will be described later.

  In addition to the components described above, a cooling system for cooling the fuel cell 10 is also connected to the fuel cell 10, but these are not directly related to the gist of the present application. Omitted.

  Next, the operation of the fuel cell 10 and the reformer 30 will be outlined based on the above-described configuration.

  First, when an operator gives an instruction to start the fuel cell 10, anode gas is generated in the reformer 30. Specifically, the air pump 54 is operated and the flow rate adjustment valve 56 is opened. As a result, the air is sucked by the air pump 54 and is circulated toward the combustion burner 30 e via the air supply path 52 and the flow rate adjusting valve 56. Heated fuel is supplied to the air via the heated fuel supply path 58 to generate a premixed gas, which is supplied to the combustion burner 30e. The combustion burner 30e ignites (ignites) the supplied premixed gas by an ignition electrode (not shown) and burns it, and a relatively high temperature exhaust gas is generated by the combustion.

  As shown by the arrow in FIG. 1, the exhaust gas is circulated in the exhaust gas pipe 30f. Since the exhaust gas pipe 30f has a shape that covers the outer wall 30c1 of the reforming pipe 30c, the exhaust gas in the exhaust gas pipe 30f raises the temperature of the reforming catalyst 30b filled in the reforming pipe 30c. Thereafter, the exhaust gas in the exhaust gas pipe 30f is exhausted to the atmosphere via the exhaust port 30f1 and the exhaust gas discharge path 60.

  When the reforming catalyst 30b is heated to a temperature capable of reforming (for example, about 700 [° C.]), the first, third, and fifth shut-off valves 50, 66, and 80 are then opened and the water supply pump is opened. 46 is driven. Thereby, the reformed water in the reformed water tank 38 is supplied to the reforming catalyst 30b of the reformer 30 through the reformed water supply path 40, the water supply pump 46, the ion filter 48, and the first shutoff valve 50. .

  Further, the reformed fuel is supplied to the reforming catalyst 30b via the reformed fuel supply path 36, the desulfurizer 42, and the flow rate sensor 44, and the reforming operation is started. Specifically, the reformed water is heated by the exhaust gas of the combustion burner 30e and evaporated to become steam. After the steam is mixed with the reformed fuel, it is supplied to the reforming catalyst 30b heated to a reformable temperature, where a steam reforming reaction occurs, that is, the mixed reformed fuel and steam are converted into anode gas. Reform.

  After the removal of carbon monoxide and the like in the reformer 30, the anode gas is caused to flow into the anode gas condenser 68 through the anode gas pipe 30 d, the first anode gas supply path 32 a and the third shut-off valve 66. Where water is condensed to produce condensed water. The produced anode gas containing the condensed water is supplied to the anode gas gas-liquid separator 70 and the condensed water is separated, and then supplied to the anode electrode of the fuel cell 10. On the other hand, the condensed water separated from the anode gas in the anode gas gas-liquid separator 70 is temporarily stored in the anode gas condensed water tank 72.

  Here, the operation of the fourth shutoff valve 76 provided in the anode gas moisture supply path 74 will be described. The operation of the fourth shutoff valve 76 is controlled based on a signal from the water amount sensor 72a. Specifically, the fourth shut-off valve 76 is opened when the water amount sensor 72a outputs an ON signal, that is, when the amount of water in the anode gas condensate water tank 72 is equal to or greater than a predetermined value, Condensed water is supplied to the reformed water tank 38 via the anode gas moisture supply passage 74, and is closed when an off signal is output (when the amount of water in the anode gas condensed water tank 72 is less than a predetermined value). Thus, its operation is controlled. As a result, the amount of moisture supplied from the anode gas condensate water tank 72 to the reforming water tank 38 can be adjusted appropriately, and the anode gas leaks to the reforming water tank 38 and the outside via the anode gas condensate water tank 72. Can be prevented.

  Continuing the description of the operation of the fuel cell 10 and the like, the cathode gas pump 24 is then operated. As a result, the cathode gas is caused to flow into the humidifier 26 via the cathode gas supply path 20, where the cathode gas is supplied with moisture or the like contained in the cathode off gas and is humidified to a desired humidity, and then the fuel cell 10. To the cathode electrode.

  In the fuel cell 10, a power generation operation is performed by causing an electrochemical reaction between the anode gas supplied to the anode electrode and the cathode gas supplied to the cathode electrode. The electric power generated in the fuel cell 10 by the electrochemical reaction is taken out from the output terminal 106, a part of which is used as a power source for auxiliary equipment such as the ECU 100 and the water pump 46, and the rest is electrically connected via the inverter 104. It is supplied to the load 102.

  Cathode off-gas discharged from the fuel cell 10 is supplied to the humidifier 26 via the cathode off-gas discharge path 22, humidifies the cathode gas flowing through the cathode gas supply path 20, and then is exhausted to the atmosphere.

  The anode off-gas discharged from the fuel cell 10, more precisely, the anode off-gas (unreacted gas) discharged without being used in the power generation operation of the fuel cell 10 passes through the anode off-gas supply path 34 and the fifth cutoff valve 80. Through the anode off-gas condenser 82, where water is condensed to produce condensed water. The generated anode off gas containing condensed water is supplied to the anode off gas gas-liquid separator 84 and the condensed water is separated, and then supplied to the combustion burner 30e of the reformer 30 as a heating fuel. When the power generation operation is started in the fuel cell 10 and the anode off gas is supplied to the combustion burner 30e, a shut-off valve (not shown) installed in the heated fuel supply path 58 is closed, and the heated fuel (city gas) ) To the combustion burner 30e is cut off (stopped).

  The condensed water separated from the anode off gas in the anode off gas gas-liquid separator 84 is temporarily stored in the anode off gas condensed water tank 86 and then supplied to the reformed water tank 38 by the opening / closing operation of the sixth shut-off valve 92. Is done. More specifically, as with the fourth shutoff valve 76, the sixth shutoff valve 92 is opened when the water amount sensor 86a outputs an on signal, and the condensed water is passed through the anode offgas moisture supply passage 90. While being supplied to the reforming water tank 38, its operation is controlled so that it is closed when an off signal is output. As a result, the amount of moisture supplied from the anode off-gas condensate water tank 86 to the reforming water tank 38 can be appropriately adjusted, and the anode off-gas leaks to the reforming water tank 38 and the outside via the anode off-gas condensate water tank 86. Can be prevented.

  Next, processing for determining the amount of air supplied to the combustion burner 30e in the operation of the control device of the reformer 30 will be described with reference to FIG.

  FIG. 2 is a flowchart showing the operation of the ECU 100 that executes a process for determining the supply amount of air to the combustion burner 30e, and FIG. 3 is a time chart showing the process.

  In the following, in S10, the supply amount of reformed fuel, the output current of the fuel cell 10, and the temperature of the reforming catalyst 30b are detected. Next, the process proceeds to S12, and the anode off-gas discharge amount is estimated based on the detected supply amount of reformed fuel, the output current of the fuel cell 10 and the temperature of the reforming catalyst 30b. Specifically, the anode off gas emission amount is estimated by searching a preset map value (not shown) based on the supply amount of reformed fuel and the like.

  Next, in S14, the supply amount of air (basic supply amount) to the combustion burner 30e is determined based on the estimated discharge amount of the anode off gas. The determination of the air supply amount is also performed by searching a preset map value (not shown) based on the estimated anode off-gas discharge amount.

  Proceeding to S16, it is determined whether or not the water recovery flag is turned on. Since this water recovery flag is set to ON when at least one of the water amount sensors 72a and 86a outputs an ON signal in another process (not shown), this determination is made based on the anode gas condensed water tank 72 or the anode off gas condensed water. This corresponds to determining whether or not the amount of water in the tank 86 is equal to or greater than a predetermined value and it is necessary to supply condensed water to the reformed water tank 38.

  In the first program loop, the determination in S16 is generally denied and the process proceeds to S18, where the fourth and sixth shut-off valves 76 and 92 are closed. Since the fourth and sixth shut-off valves 76 and 92 are already closed in the first program loop, the process proceeds to S20, and the output of the exhaust gas sensor 62 is read to detect the oxygen concentration in the exhaust gas. Next, in S22, a correction amount (initial value 0) of air supplied to the combustion burner 30e is calculated based on the detected oxygen concentration in the exhaust gas. The correction amount of air is calculated such that the amount of air supplied to the combustion burner 30e can maintain a stable (optimum) combustion state in the combustion burner 30e, and is specifically set in advance. The calculated map value (not shown) is calculated by searching based on the oxygen concentration.

  Next, in S24, the correction amount value calculated at the previous program execution is replaced with the correction amount calculated this time, that is, updated. Next, in S26, the air supply amount is corrected by subtracting the correction amount updated in S24 from the air supply amount determined in S14. Thus, the determined supply amount of air is corrected according to the output of the exhaust gas sensor 62 provided in the exhaust gas discharge path 60 of the combustion burner 30e.

  Proceeding to S28, the flow rate adjusting valve 56 is opened and closed so that the air flow rate in the air supply path 52 becomes the air supply amount corrected in S26. As a result, a stable (optimum) combustion state is maintained in the combustion burner 30e, incomplete combustion and misfire can be prevented, and power consumption of the air pump 54 and the like can be reduced, resulting in the efficiency of the entire apparatus. Can be improved.

  On the other hand, when the answer in S16 is affirmative, that is, when the water recovery flag is turned on, the process proceeds to S30 to hold the corrected air supply amount, and then proceeds to S32, corresponding to the condensed water tank whose water amount is equal to or greater than a predetermined value. The shut-off valve is opened as described above, specifically, the fourth or sixth shut-off valves 76 and 92 are opened. Here, the processing from S16 to S32 will be described with reference to FIG. In the following description, the case where the amount of water in the anode gas condensate water tank 72 becomes equal to or greater than a predetermined value and the water recovery flag is turned on will be described as an example. As described above, it is also substantially valid when the water recovery flag is turned on.

As shown in FIG. 3, when the water recovery flag is turned on at time t _0, since the amount of water in the anode gas condensed water tank 72 is a predetermined value or more, then the time t ₁ in the fourth shut-off valve 76 opens To be spoken. Note that time from _{t 0} to time _{t 1} is about 0.1～1Sec. When the fourth shut-off valve 76 is opened and the anode gas moisture supply path 74 is opened and closed, the gas pressure inside the first anode gas supply path 32a and the anode offgas supply path 34 (in FIG. ”) And the like fluctuate rapidly.

  When the internal pressure of the pipe suddenly fluctuates, for example, moisture in the gas and water adhering / staying in the pipe scatter, and the output of various sensors (specifically, the exhaust gas sensor 62) fluctuates. When the output of the exhaust gas sensor 62 fluctuates, the correction amount calculated based on the output of the exhaust gas sensor 62 and the air supply amount to the combustion burner 30e corrected by the correction amount change as shown by the broken line in FIG. . If the operation of the flow rate adjusting valve 56 is controlled in such a state, the amount of heat of the combustion burner 30e changes, so that the change in the internal pressure of the pipe is further amplified, resulting in a stable (optimum) combustion state in the combustion burner 30e. It becomes difficult to hold.

  Accordingly, when the result in S16 is affirmative, the routine proceeds to S30, where the corrected air supply amount is held. In other words, when the anode gas moisture supply path 74 is opened and closed, the previously corrected air supply amount is held. I tried to do it. As a result, the flow rate adjusting valve 56 is opened and closed so that the air flow rate in the air supply passage 52 becomes the previously corrected air supply amount, so the flow rate of the gas in the first anode gas supply passage 32a Even when the pressure or the like changes due to the opening and closing of the anode gas moisture supply passage 74, a stable combustion state can be maintained in the combustion burner 30e without being affected by the change.

Incidentally, when the result in S16 is negative in subsequent program loops next (time _t 2), (in the S18 process) Then at time _{t 3} the fourth shut-off valve 76 is closed. When the fourth shut-off valve 76 is closed, the internal pressure of the piping does not change, but as shown in FIG. 3, the output of the exhaust gas sensor 62 takes a certain time to converge to a value indicating an accurate oxygen concentration. Cost. Therefore, after executing the process of S18, the system is configured to wait until a predetermined time (time point t _{3 to} t _4, for example, 10 to 15 sec) elapses.

Specifically, the fourth shutoff valve 76 at time t ₃ is closed, to start the counter (up-counter) in another program (not shown), when the counter value has reached a predetermined time (time t ₄ ) The output of the exhaust gas sensor 62 is read to detect the oxygen concentration in the exhaust gas (S20). In FIG. 3, a section in which the air supply amount to the combustion burner 30e is corrected by the output of the exhaust gas sensor 62 is referred to as a “correction control section”, and the corrected water supply amount is maintained by opening and closing the moisture supply path. This section is indicated as “control correction amount holding section”. Further, the predetermined time is appropriately set in consideration of piping handling and the like.

  As described above, in the embodiment of the present invention, the reforming catalyst 30b for reforming the fuel (reformed fuel) into the anode gas, the anode off-gas discharged from the fuel cell 10 and the air are combusted, and the modification is performed. A fuel cell reformer 30 comprising a combustion burner 30e for heating the quality catalyst, air supply amount determination means (ECU 100. S14) for determining the amount of air supplied to the combustion burner, and the fuel cell. Moisture removal means for removing moisture contained in at least one of the anode gas and the anode off gas discharged from the fuel cell (anode gas condenser 68, anode gas gas-liquid separator 70, anode off gas condenser 82, anode off gas gas) Liquid separator 84) and a water supply path (anode gas water supply path 7) for supplying the removed water to the water storage tank (reformed water tank 38). And an anode off-gas moisture supply channel 90) and moisture supply amount adjusting means (fourth shut-off valve 76 and sixth shut-off valve 92) for opening and closing the moisture feed channel and adjusting the amount of moisture supplied. In the control device for a fuel cell reformer, an air supply amount correction means (ECU 100, S22 to S22) that corrects the determined supply amount of air according to the output of an exhaust gas sensor provided in the exhaust gas discharge path of the combustion burner. S26), and the air supply amount correction means is configured to hold the corrected air supply amount when the moisture supply path is opened and closed (S30).

  Thereby, when opening and closing the moisture supply paths 74 and 90, a stable combustion state can be maintained in the combustion burner 30e. Specifically, when the moisture supply passages 74 and 90 are opened and closed by the shutoff valves 76 and 92, etc., a change in gas flow velocity and a change in pressure occur in the piping through which the anode gas and anode off gas are circulated. There is a possibility that the moisture in the gas scatters and the output of various sensors (specifically, the exhaust gas sensor 62) fluctuates. If the output of the exhaust gas sensor 62 fluctuates, the determined supply amount of air may not be accurately corrected. However, as described above, when the moisture supply paths 74 and 90 are opened and closed, It is configured to hold the supply amount, in other words, the air supply amount corrected according to the output of the exhaust gas sensor 62 when the moisture supply paths 74 and 90 are opened and closed is not corrected, and the previously supplied air supply is corrected. Since the amount is maintained, the combustion burner 30e is stable without being affected even when the flow velocity or pressure in the pipe through which the anode gas or the like is circulated changes due to the opening and closing of the moisture supply path. The combustion state can be maintained.

  Also, a fuel supply amount detection means (flow rate sensor 44, ECU 100. S10) for detecting the supply amount of fuel reformed to anode gas by the reforming catalyst, and an output current detection means for detecting the output current of the fuel cell. (Current sensor 110, ECU 100. S10), and anode off-gas emission amount estimation for estimating the amount of anode off-gas discharged from the fuel cell based on at least one of the detected fuel supply amount and output current. Means (ECU100; S12), and the air supply amount determination means is configured to determine the air supply amount based on the estimated discharge amount of the anode off gas (S14). Thus, the amount of air supplied to the combustion burner 30e can be accurately determined according to the operating state of the reformer 30 and the fuel cell 10.

  Further, the exhaust gas sensor 62 is constituted by either an air-fuel ratio sensor or an oxygen concentration sensor. Thereby, since the oxygen concentration in the exhaust gas can be accurately detected, the determined supply amount of air can be corrected more accurately.

  In addition, the moisture removing unit condenses moisture contained in at least one of an anode gas supplied to the fuel cell and an anode off-gas discharged from the fuel cell to generate condensed water (anode gas condensation). 68, an anode off-gas condenser 82), and a gas-liquid separator (anode gas gas-liquid separator 70, anode off-gas gas-liquid separator 84) that separates and removes the condensed water condensed in the condenser from the gas. It comprised so that it might become. As a result, moisture contained in the anode gas and anode off-gas can be surely removed, and therefore, output reduction caused by condensation of moisture inside the fuel cell 10, incomplete combustion and misfire in the combustion burner 30e, etc. Problems can be prevented.

  In the above description, the condenser and the gas-liquid separator, which are moisture removing means, are provided in the first anode gas supply path 32a and the anode off-gas supply path 34, respectively, but only in one of the supply paths. In that sense, in claim 1, “a moisture removing means for removing moisture contained in at least one of the anode gas supplied to the fuel cell and the anode off-gas discharged from the fuel cell” ".

Although particularly shown and modifiable temperature time and the reforming catalyst from time t ₀ to time t _1, their values are not limited to be illustrative.

  Further, although the fuel cell 10 is a solid polymer type, the present invention is not limited thereto, and other types may be used.

  Further, the city gas is used as the reformed fuel or the heating fuel. However, the present invention is not limited to this, and LP gas may be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a fuel cell reformer control device according to an embodiment of the present invention including a fuel cell as a whole. 2 is a flowchart showing the operation of the ECU shown in FIG. It is a time chart showing changes, such as the output of the exhaust gas sensor shown in FIG. 1, and the supply amount of the air to a combustion burner.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell, 30 Reformer (reformer for fuel cells), 30b Reforming catalyst, 30e Combustion burner, 38 Reformed water tank (storage tank), 44 Flow rate sensor (fuel supply amount detection means), 60 Exhaust gas discharge Path, 62 exhaust gas sensor, 68 anode gas condenser (moisture removal means), 70 anode gas gas-liquid separator (moisture removal means), 74 anode gas moisture supply path (moisture supply path), 76 fourth shutoff valve (moisture) Supply amount adjusting means), 82 anode off gas condenser (moisture removing means), 84 anode off gas gas-liquid separator (moisture removing means), 90 anode off gas moisture supply path (moisture supply path), 92 sixth shutoff valve (moisture) Supply amount adjusting means), 100 electronic control unit (ECU), 110 current sensor (output current detecting means)

Claims (4)

a. A reforming catalyst for reforming fuel into an anode gas; a reformer for a fuel cell comprising an anode off-gas discharged from the fuel cell and a combustion burner for heating the reforming catalyst by burning air; and
b. An air supply amount determining means for determining an air supply amount to the combustion burner;
c. Moisture removing means for removing moisture contained in at least one of the anode gas supplied to the fuel cell and the anode off-gas discharged from the fuel cell;
d. A water supply path for supplying the removed water to the water storage tank;
And e. Moisture supply amount adjustment means for adjusting the amount of moisture supply by opening and closing the moisture supply path;
In the control device for a fuel cell reformer, comprising: an air supply amount correction means for correcting the determined supply amount of air according to an output of an exhaust gas sensor provided in an exhaust gas discharge path of the combustion burner. In addition, the air supply amount correction means holds the corrected air supply amount when the moisture supply path is opened and closed. f. Fuel supply amount detection means for detecting the supply amount of fuel reformed to anode gas by the reforming catalyst;
g. Output current detection means for detecting the output current of the fuel cell;
And h. Anode offgas emission estimation means for estimating the amount of anode offgas discharged from the fuel cell based on at least one of the detected fuel supply amount and output current;
2. The fuel cell reformer control according to claim 1, wherein the air supply amount determination means determines the air supply amount based on the estimated anode offgas discharge amount. apparatus.   3. The control apparatus for a fuel cell reformer according to claim 1 or 2, wherein the exhaust gas sensor comprises either an air-fuel ratio sensor or an oxygen concentration sensor.   The moisture removing means includes a condenser that condenses moisture contained in at least one of an anode gas supplied to the fuel cell and an anode off-gas discharged from the fuel cell to generate condensed water, and the condenser The fuel cell reformer control device according to any one of claims 1 to 3, comprising a gas-liquid separator that separates and removes the condensed condensed water from the gas.

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