JP2013030285A - Failure determination method for pressure detection means installed in fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure determination method for pressure detection means installed in a fuel cell capable of securely determining abnormality occurrence of pressure detection means installed in a fuel gas supply passage of a fuel cell.SOLUTION: A gas main electromagnetic valve and a booster blower are interposed on the upstream position and on the downstream position of a fuel gas supply passage for supplying fuel gas to the side of a fuel cell, respectively, and a negative pressure detection switch which is turned on when the inner pressure in the fuel gas supply passage between the gas main electromagnetic valve and the booster blower is in a prescribed negative pressure tendency is installed. The failure determination of negative pressure detection switch is performed at the time of start of fuel cell (YES at S1). The booster blower is actuated as the gas main electromagnetic valve is kept in a closed state (S2-S4). If the negative pressure detection switch is not turned on (NO at S5), it is determined that the negative pressure detection switch is in failure and is followed by notification (S9) or operation prohibition (S10).

Description

  The present invention relates to a failure determination method for pressure detection means installed in a fuel cell, and in particular, diagnoses whether or not a failure has occurred in a pressure detection means installed between an original solenoid valve and a booster blower in a fuel gas supply passage. It relates to the technology to be made possible.

  Conventionally, in order to ensure the opening / closing switching in the fuel gas supply passage of the fuel cell, in particular, the closing switching, electromagnetic valves are respectively provided at both upstream and downstream positions with respect to the fuel gas supply passage. A method for diagnosing a failure of a solenoid valve has been proposed (see, for example, Patent Document 1). In this case, both solenoid valves are closed together, and the failure diagnosis of the upstream solenoid valve is performed based on the detected hydrogen gas pressure in the fuel gas supply passage between the two solenoid valves. It has been proposed to open the valve once and then close it again to perform failure diagnosis of the downstream solenoid valve based on the detected hydrogen gas pressure in the fuel gas supply passage between the two solenoid valves.

  In addition, as a failure determination method for an air supply system that supplies air to the fuel cell, for example, a determination method based on a detected air flow rate has been proposed (see, for example, Patent Document 2). This document states that if it is not determined that the air flow sensor is normal, the air supply system failure determination is not performed, but whether or not the air flow sensor is normal is determined. No specific method of how to do this is described.

JP-A-9-22711 Japanese Patent No. 4307823

  By the way, in what uses city gas etc. as a fuel of a fuel cell, what is called a microcomputer meter (gas meter with a gas cutoff device) may be interposed in the supply side of the city gas. Further, in the case of a household fuel cell, exhaust heat is recovered from exhaust gas generated during power generation, hot water is stored, and used for hot water supply. In such a hot water supply system, a heat source device is attached so that it can be supplementarily heated, and city gas is branched and supplied to the heat source device from the same supply source as described above. In such a fuel cell system, when an abnormality is detected due to an earthquake or gas construction, the microcomputer meter automatically shuts off the city gas supply source. In order to avoid such inconvenience, if the fuel (city gas) is continuously sucked by the booster blower on the fuel cell side even after the automatic shut-off, air may flow backward from the heat source device side to the fuel cell side. In addition, the pressure detection means installed in the fuel gas supply passage of the fuel cell detects a negative pressure, so that the abnormality on the fuel gas supply is detected and the operation on the fuel cell side is safely stopped. It is considered to be.

  However, if the installed pressure detection means does not operate normally, it will be impossible to detect even if an abnormality occurs in the fuel gas supply. Therefore, it is required to develop a failure determination method for the pressure detection means installed in the fuel gas supply passage. Has been.

  The present invention has been made in view of such circumstances, and an object of the present invention is to install in a fuel cell that can reliably determine the occurrence of an abnormality in the pressure detection means installed in the fuel gas supply passage of the fuel cell. Another object of the present invention is to provide a failure determination method for the pressure detecting means.

  In order to achieve the above object, in the present invention, the original gas solenoid valve is disposed downstream of the fuel gas supply passage for supplying the fuel gas to the fuel cell that generates power by the reaction of the fuel gas and the oxygen-containing gas. Method for determining failure of pressure detecting means when pressure detecting means for detecting the pressure in the fuel gas supply passage between the original gas solenoid valve and the pressure increasing blower is installed at each side position of the pressure increasing blower The following specific items are to be provided. That is, when the booster blower is operated with the original gas solenoid valve closed at the start of the power generation operation of the fuel cell, if the pressure detected by the pressure detection means does not decrease, the pressure detection The means is determined to have failed (claim 1).

  In the case of the present invention, when the booster blower is operated, suction is performed from the upstream side, but the upstream gas gas from the booster blower to the original gas solenoid valve remains because the original gas solenoid valve remains closed. In the supply passage, the internal pressure decreases and tends to be negative. Nevertheless, if the pressure detected by the pressure detection means installed in the fuel gas supply passage from the booster blower to the original gas solenoid valve does not decrease, it can be determined that the pressure detection means has failed. Become. As a result, it is possible to reliably determine the occurrence of a failure in the pressure detection means. Based on this failure determination, the user is notified of the occurrence of the failure, or the subsequent operation of the fuel cell is forcibly stopped or prohibited. It becomes possible.

  The pressure detection means in the failure detection method of the pressure detection means described above can be used for determining whether or not fuel gas is supplied during the power generation operation of the fuel cell based on the detected pressure (claim) Item 2). For example, when a microcomputer meter is installed on the fuel gas supplier side, it is used for an important application to reliably detect and detect the stoppage of fuel gas supply due to the operation of the automatic shut-off function by the microcomputer meter. This makes it possible to reliably determine the failure of the pressure detection means.

  As described above, according to the failure determination method for the pressure detection means installed in the fuel cell of the present invention, it is possible to reliably determine the occurrence of an abnormality in the pressure detection means installed in the fuel gas supply passage of the fuel cell. On the basis of the failure determination, the user can be notified of the occurrence of the failure, and the subsequent operation of the fuel cell can be forcibly stopped or prohibited.

  In particular, according to claim 2, when a microcomputer meter is installed on the fuel gas supply side, the stoppage of the fuel gas supply accompanying the operation of the automatic shut-off function by the microcomputer meter is reliably determined and detected. This makes it possible to reliably determine the failure of the pressure detecting means used for an important application.

It is a schematic diagram which shows the example of the fuel cell system to which embodiment which concerns on the failure determination method of this invention is applied. FIG. 2 is a partial explanatory diagram of FIG. 1. It is a flowchart which performs the failure diagnosis which concerns on a failure determination method as a check process before starting.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a fuel cell system that implements a failure determination method according to an embodiment of the present invention. This fuel cell system is combined with a fuel cell unit 2 and a hot water storage hot water supply unit 3 that collects exhaust heat from the fuel cell unit 2 and stores it for hot water supply, and is controlled by a controller 1. It is a thing. Hereinafter, the case where the fuel cell unit 2 is configured by a solid oxide fuel cell (SOFC) will be described as an example.

  The fuel cell unit 2 includes a power generation unit 4, a preheating / evaporator 5, a fuel gas circuit 6, a reforming air supply circuit 7, a cathode air supply circuit 8, and a water supply processing circuit 9. . The power generation unit 4 includes a cell stack 41, a reformer 42, and an air heat exchanger 43. The supply of fuel gas, air, water vapor, etc. to the power generation unit 4 and the discharge of exhaust gas are all performed through a preheater / evaporator 5. A fuel gas circuit 6 including a fuel gas supply passage, a reforming air supply circuit 7 and a cathode air supply circuit 8 are passed through the preheating / evaporator 5, while exhaust gas from the power generation unit 4 side is used as a heat source for preheating. Is introduced to the water supply processing circuit 9 and the pure water obtained by collecting the moisture in the exhaust gas is returned to the fuel gas circuit 6 in the preheating / evaporator 5 and converted into steam for steam reforming. It has become so.

  The cell stack 41 is configured, for example, such that a plurality of cells are erected with a predetermined interval, and each cell has, for example, a small-diameter cylindrical anode (fuel electrode) and a large-diameter cylinder covering the outer peripheral side. The cathode (air electrode) having a shape is integrated concentrically with an electrolyte in between. The anode and the cathode are both made of ceramics containing a metal oxide such as Ni, and the electrolyte is made of a solid oxide such as YSZ (yttrium stabilized zirconia).

  From the reformer 42, the fuel gas made richer in hydrogen than the raw fuel fuel gas is flowed from the lower end toward the upper end from the reformer 42 to the inner hole of the anode of the cell. Cathode air as an oxygen-containing gas is supplied from the heat exchanger 43. At the cathode, oxygen in the cathode air becomes oxygen ions and passes through the electrolyte. At the anode, it reacts with hydrogen in the fuel gas to produce water (water vapor), and the electrons generated at that time move to the cathode side through the circuit. Electricity is generated by repeatedly ionizing oxygen again. After the fuel gas supplied to the inner hole of the anode is used for the above reaction, it is led to the reformer burner as an off gas and used as a fuel for combustion. The cathode air is exhausted upward and sent to the preheater / evaporator 5 as exhaust gas together with the combustion exhaust gas from the reformer burner. At that time, the exhaust gas passes through the air heat exchanger 43 as a heat source for heating the air.

  The fuel gas circuit 6 includes an original gas solenoid valve 60, a gas solenoid valve 61, a booster blower 62, a buffer tank 63, a gas flow sensor 64, a desulfurizer 65, a check valve 66, and the like from the upstream side of the fuel gas supply passage 67. The reforming air supply circuit 7 is joined before the preheating / evaporator 5 is inserted. In addition, between the original gas solenoid valve 60 and the booster blower 62, more precisely, between the original gas solenoid valve 60 and the gas solenoid valve 61, the internal pressure of the fuel gas (for example, city gas as the raw material gas) in the passage. A pressure switch 68 is provided as a pressure detecting means for detecting. The reforming air supply circuit 7 includes a reforming air blower 71 that sucks and supplies the air that has passed through the filter 70, a buffer tank 72, a reforming air flow sensor 73, an air valve 74, and vice versa. A stop valve 75 and the like are interposed. The fuel gas circuit 6 joined with the reforming air supply circuit 7 is supplied with pure water from the water supply processing circuit 9 in the preheating / evaporator 5, and the pure water is supplied to the fuel gas circuit 6 in the preheating / evaporator 5. It is sent to the reformer 42 in a state of being evaporated into water vapor. Similarly to the reforming air supply circuit 7, the cathode air supply circuit 8 sucks the air that has passed through the filter 80 and supplies it as an oxygen-containing gas, a buffer tank 82, and cathode air. A flow rate sensor 83 for use and the like are interposed.

  In the heat exchanger 91 for exhaust heat recovery, exhaust heat is recovered by exchanging heat with the exhaust gas after passing through the preheating / evaporator 5 using the circulating water circulated and supplied from the hot water storage hot water supply unit 3 as cooling water. In addition to storing hot water, the water contained in the exhaust gas is condensed to recover water. The water supply processing circuit 9 collects condensed water (drain water) generated in the heat exchanger 91 for exhaust heat recovery at the drain recovery unit 92, purifies the collected condensed water, and stores purified water after purification. And a circuit for supplying the preheated / evaporator 5 to reuse the stored pure water as water vapor. The water supply processing circuit 9 shown in the figure includes an ion exchange resin set 93 that performs a purification process for purifying the collected condensed water into pure water, and a pure water tank 94 that stores purified water after purification. A pure water pump 95 for taking pure water from the pure water tank 94 and supplying it to the preheating / evaporator 5 at a constant small flow rate, a pure water flow sensor 96 for detecting the pure water flow rate at that time, A check valve 97 is interposed in order from the upstream side. The pure water supplied from the water supply processing circuit 9 to the preheater / evaporator 5 is evaporated by the preheater / evaporator 5 to become water vapor and supplied to the reformer 42 and the anode side of the power generation unit 4. .

  The hot water storage type hot water supply unit 3 includes a hot water storage tank 11, a circulation circuit 12 that circulates and supplies hot water between the hot water storage tank 11 and the heat exchanger 91 for exhaust heat recovery, and a water inlet passage that allows water supply from the outside to enter the hot water storage tank 11. 13. Hot water outlet 14 for hot water supply from the top of the hot water storage tank 8, auxiliary heat source machine 15 for auxiliary heating when the hot water in the hot water storage tank 11 is lower than the temperature required for hot water supply, and auxiliary heat source machine The fuel gas supply passage 16 is configured to supply a gas for fuel (for example, city gas) to the combustion burner 151 in the engine 15. In this hot water storage type hot water supply unit 3, the circulation pump 121 interposed in the circulation circuit 12 is operated, and the hot water circulated from the bottom of the hot water storage tank 11 to the exhaust heat recovery heat exchanger 91 is exchanged with exhaust gas. Then, the heat recovered from the exhaust gas is stored in the hot water storage tank 11 in the form of hot water. On the other hand, the hot water in the hot water storage tank 11 is taken out from the hot water outlet 14 and heated with the auxiliary heat source unit 15 or supplied to the hot water tap 17 or poured into the bathtub 18 without auxiliary heating. Or you can.

  Here, the relationship between the fuel gas circuit 6 on the fuel cell system 2 side and the fuel gas supply passage 16 on the hot water storage hot water supply system 3 side will be described with reference to FIG. (Gas meter with automatic gas shut-off device) A fuel gas supply passage is branched downstream of 19, and one of the fuel gas supply passages 16 of the hot water storage hot water supply system 3 is extended to the combustion burner 151 of the auxiliary heat source unit 15. The other is a fuel gas supply passage 67 of the fuel gas circuit 6 and extends to the power generation unit 4 side of the fuel cell system 2. Therefore, when the automatic shut-off function of the microcomputer meter 19 is activated due to the occurrence of an abnormality such as an earthquake, the supply of fuel gas (city gas) to both the fuel gas supply passages 16 and 67 is stopped.

  Here, if the fuel cell system 2 side is activated and is in a normal operation state (power generation operation state), the controller 1 controls both the original gas solenoid valve 60 and the gas solenoid valve 61 of the fuel gas circuit 6 to be opened. In this state, the operation of the booster blower 62 is controlled, and fuel gas is supplied to the power generation unit 4 through the microcomputer meter 19 and the fuel gas supply passage 67 in a normal state (open state). If the microcomputer meter 19 is switched to the automatic shut-off state due to the occurrence of the abnormality in the normal operation state and the supply of the fuel gas is stopped, the fuel gas supply passage 67 tends to have a negative pressure tendency from the previous positive pressure state. As a result, the signal output state from the pressure switch 68 to the controller 1 changes. As the pressure switch 68, for example, for a fuel gas supply pressure of about 2 kPa, the negative pressure is such that the contact is turned on at an internal pressure of 0.23 to 0.46 kPa and the contact is turned off at an internal pressure of 0.49 to 0.75 kPa. If the pressure detection switch is configured, the pressure switch 68 may output an ON signal when the fuel gas supply is stopped by the automatic shutoff operation of the microcomputer meter 19. In that case, the controller 1 can receive the ON signal output from the pressure switch 68, detect the automatic shut-off of the microcomputer meter 19, and forcibly stop the fuel cell system 2 side safely.

  Regarding the pressure switch 68 that plays such an important role, the controller 1 performs a failure determination when the fuel cell system 2 is started. In other words, if there is a start request for the fuel cell system 2, a failure determination for the pressure switch 68 is executed before entering the operation control for the start, and only when it is determined that the pressure switch 68 is normal. Then, the start-up control of the fuel cell system 2 is started.

  Hereinafter, the processing for the pre-startup check (failure determination) of the pressure switch 68 will be described with reference to FIG. First, it is confirmed whether or not there is an activation request (step S1). If there is an activation request (YES in step S1), the subsequent pre-activation check is executed. Whether or not there is an activation request may be confirmed by, for example, the presence or absence of a fuel gas supply request signal output when the operation switch is turned on. If there is an activation request, the gas source electromagnetic valve 60 remains in the stopped state, that is, is maintained in the closed state, while the gas electromagnetic valve 61 is switched from the closed state to the open state (step S2). After waiting for elapse of a predetermined time α seconds (for example, continuous 0.1 seconds) until the state becomes stable (YES in step S3), the operation of the booster blower 62 is started (step S4).

  If the pressure switch 68 changes to the ON state (YES in step S5) and it is determined that β seconds (for example, continuous 0.5 seconds) have elapsed (YES in step S6), the original gas solenoid valve 60 is turned on. Since the booster blower 62 is actuated and sucked in spite of the closed state, the internal pressure of the fuel gas supply passage 67 from the original gas solenoid valve 60 to the booster blower 62 decreases, and the negative pressure tends to become a pressure switch. 68 has changed to the ON state, that is, it is determined that the pressure switch 68 is functioning normally, and the process proceeds to the normal operation control in the next step S7. The transition to the normal operation control may be performed by simply switching the opening of the original gas solenoid valve 60. For example, by executing the following process, the pressure fluctuation load is suppressed and a smooth transition is realized. Can be made. That is, the booster blower 62 is temporarily stopped, the original gas solenoid valve 60 is opened, and then the booster blower 62 is operated to supply the fuel gas.

  On the other hand, if the pressure switch 68 remains in the OFF state in step S5 (NO in step S5) and a predetermined time γ seconds (for example, continuous 10 seconds) have elapsed (YES in step S8), the original gas solenoid valve Although the pressure increasing blower 62 is operated and sucked while the valve 60 is in the closed state, that is, the internal pressure should be reduced, the contact is not turned ON but is maintained in the OFF state. Therefore, it is determined that the pressure switch 68 has failed, a notification is given that the pressure switch 68 is abnormal (step S9), and an abnormal stop process (forced stop process) for prohibiting activation of the fuel cell system 2 is performed. (Step S10). The notification of the abnormality may be performed by displaying on the display unit of the remote controller connected to the controller 1, lighting / flashing of a warning lamp, sounding an alarm buzzer, or sound warning using a sound circuit. .

  In the case of the failure determination method according to the above embodiment, a failure (occurrence of abnormality) of the pressure switch 68 installed in the fuel gas supply passage 67 can be reliably detected, and the fuel cell system 2 is forcibly stopped based on this. Thus, it is possible to reliably avoid the possibility of inconvenience such as damage on the fuel cell system 2 side when the automatic shut-off function of the microcomputer meter 19 is activated. In addition, the failure (occurrence of an abnormality) of the pressure switch 68 can be detected before the fuel electronic system 2 is activated, and thus the possibility of the occurrence of the inconvenience can be more reliably avoided.

<Other embodiments>
In addition, this invention is not limited to the said embodiment, Other various embodiment is included. That is, in the said embodiment, although the downstream of the microcomputer meter 19 interposed by the supply source demonstrated the case where the fuel supply path 16 extended to the auxiliary heat source machine 15 side other than the fuel supply path 67 branched, For example, the failure determination method of the present invention may be applied to a system branched to a gas stove, a gas fan heater, or the like instead of or in addition to the auxiliary heat source unit 15.

  In the above embodiment, the pressure switch 68 is shown as the pressure detection means. However, the pressure detection means is not limited to this, and a pressure sensor or a positive pressure detection switch corresponding to the fuel gas supply pressure is used as the pressure detection means. Also good.

DESCRIPTION OF SYMBOLS 1 Controller 2 Fuel cell system 4 Electric power generation part 6 Fuel gas circuit 60 Original gas solenoid valve 62 Booster blower 67 Fuel gas supply path 68 Pressure switch (pressure detection means)

Claims (2)

An original gas solenoid valve is interposed in the upstream position of the fuel gas supply passage for supplying the fuel gas to the fuel cell that generates power by reaction of the fuel gas and the oxygen-containing gas, and a booster blower is interposed in the downstream position, A failure determination method for the pressure detection means when a pressure detection means for detecting the pressure in the fuel gas supply passage between the original gas solenoid valve and the booster blower is installed,
When the booster blower is operated with the original gas solenoid valve closed at the start of power generation operation of the fuel cell, if the pressure detected by the pressure detector does not decrease, the pressure detector Judge that it is malfunctioning,
A failure determination method for pressure detection means installed in a fuel cell. A failure determination method for pressure detection means installed in the fuel cell according to claim 1,
The pressure detection means is used for determining whether or not fuel gas is supplied during the power generation operation of the fuel cell based on the detected pressure, and a failure determination method for the pressure detection means installed in the fuel cell.

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