JP5311736B2 - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of preventing failure of a reformer and evading operation shutdown of a fuel cell in the case there is abnormality (failure) in a water supply means. <P>SOLUTION: This is the fuel cell system 1 equipped with the fuel cell 1, the reformer 4 in order to supply a reformed gas, a reformed gas supply means 5 in order to supply the reformed gas 4 and water, an oxygen containing gas supply means 6, and a water supply means 8 in order to supply water or vapor from a water tank 7, in which the oxygen containing gas supply means is shut down at the time of normal operation. In the case a water supply amount to the reformer 4 becomes over a preset prescribed amount or equal to or less than the prescribed amount, by being equipped with a control means 9 of switching the water supply means 8 to the oxygen containing gas supply means 6 or using both supply means at the same time, even in the case there is the abnormality in the water supply means 8, a stable reforming reaction can be carried out and the failure of the reformer 4 can be prevented, and operation shutdown of the fuel cell 2 can be evaded. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a fuel cell system including a fuel cell and a reformer for supplying a reformed gas necessary for power generation of the fuel cell.

  2. Description of the Related Art In recent years, various fuel cells in which a fuel cell stack formed by arranging a plurality of fuel cells is accommodated in a storage container and its operation method have been proposed as next-generation energy.

  Hydrogen is used as a fuel gas used for power generation in this fuel cell. Hydrogen gas and an oxygen-containing gas (usually air) are supplied to the fuel cell, and the oxygen-containing gas is supplied to the oxygen electrode in the fuel cell. Electric power is generated by bringing them into contact with each other and bringing hydrogen into contact with the fuel electrode in the fuel cell to cause a predetermined electrode reaction.

  As a method for producing hydrogen as the fuel gas, a steam reforming method and a partial oxidation reforming method are known.

The steam reforming method is an endothermic reaction in which hydrocarbon can be reacted with steam to obtain hydrogen, which can be expressed as CH ₄ + H ₂ → 3H ₂ + CO, and is known as an efficient reaction for obtaining hydrogen. Yes.

On the other hand, the partial oxidation reforming method is an exothermic reaction in which hydrocarbon can be reacted with oxygen to obtain hydrogen, and can be represented by CH ₄ + O ₂ → 2H ₂ + CO ₂ . Although this partial oxidation reforming method is inferior in efficiency to obtain hydrogen than the steam reforming method, it is a major feature that it is an exothermic reaction.

In the operation of the fuel cell, the partial oxidation reforming method is used at the time of starting the fuel cell, and when the fuel cell or the reformer exceeds a predetermined temperature, the steam reforming method that can generate hydrogen more efficiently is switched. A method is known (see, for example, Patent Document 1).
JP 2000-31004 A

  However, in a reformer that performs steam reforming, if the water supply means for supplying water has an abnormality (failure) and sufficient water is not supplied to the reformer, the reformer fails or a fuel cell There is a problem in that it is necessary to perform control to stop the operation.

  On the other hand, in a reformer that performs steam reforming, when the water supply means becomes abnormal (failure) and excessive water is supplied to the reformer, the partial pressure of steam in the reformed gas increases, or the temperature There is a possibility that the power generation efficiency of the fuel cell may be greatly reduced due to a significant change in the balance, resulting in a problem that the reformer fails or control that stops the fuel cell must be performed.

  Accordingly, an object of the present invention is to provide a fuel cell system capable of preventing a failure of a reformer and avoiding an operation stop of a fuel cell when an abnormality (failure) occurs in a water supply unit.

The fuel cell system of the present invention includes a fuel cell, a reformer for supplying a reformed gas to the fuel cell, and a reformed gas supply means for supplying a reformed gas to the reformer. An oxygen-containing gas supply means for supplying an oxygen-containing gas to the reformer, a water tank for storing water to be supplied to the reformer, and water or steam from the water tank to the reformer The oxygen-containing gas supply means is stopped during steady operation, and water or steam is supplied to the reformer by the water supply means to perform operation by steam reforming. In the fuel cell system being performed, when the amount of water supplied to the reformer is equal to or greater than a predetermined amount during the steady operation, it is determined that an abnormality or failure has occurred in the water supply means , Switch the water supply means to the oxygen-containing gas supply means. Characterized by comprising a control means for combination obtain either or both the supply means.

  When a predetermined amount or more of water is supplied to the reformer, the power generation efficiency may decrease significantly as the steam partial pressure in the reformed gas increases, and temporarily enters the reformer. There is a possibility that water may accumulate, and as a result, the temperature of the reformer decreases and the reforming reaction cannot be performed efficiently. Furthermore, there is a possibility that the reformer breaks down or the operation of the fuel cell needs to be stopped.

  In the fuel cell system of the present invention, the water supply means for supplying water from the water tank to the reformer is abnormal by connecting the water supply means and the oxygen-containing gas supply means in parallel to the reformer. When a failure occurs and the amount of water supplied to the reformer exceeds a predetermined amount, partial oxidation reforming can be performed by stopping the water supply means and switching to the oxygen-containing gas supply means. . Here, the water accumulated in the reformer can be removed by being evaporated by the reaction heat accompanying the partial oxidation reforming. Therefore, it is possible to suppress the failure of the reformer and the shutdown of the fuel cell.

  In this case, if the fuel cell is adversely affected by immediately stopping the water supply means, both the water supply means and the oxygen-containing gas supply means are used in combination for a certain period of time, and the partial oxidation reforming gradually. By switching to, the reforming reaction can be performed stably.

The fuel cell system of the present invention includes a fuel cell, a reformer for supplying a reformed gas to the fuel cell, a reformed gas supply means for supplying a reformed gas to the reformer, An oxygen-containing gas supply means for supplying an oxygen-containing gas to the mass device, a water tank for storing water to be supplied to the reformer, and for supplying water or steam from the water tank to the reformer. A fuel cell system comprising a water supply means, and when the water supply amount to the reformer exceeds a predetermined amount during steady operation, it is determined that an abnormality or failure has occurred in the water supply means ; Since the control means for controlling the water supply means to switch to the oxygen-containing gas supply means or to use both supply means together, it is possible to suppress the failure of the reformer and the shutdown of the fuel cell, A stable reforming reaction Kill.

  FIG. 1 is a block diagram schematically showing a fuel cell system 1 of the present invention. In the fuel cell main body 2 indicated by a dotted frame, a fuel cell (particularly, a solid electrolyte fuel cell) 3 that is an assembly of fuel cells in which an electrolyte is sandwiched between a pair of electrodes contains a reforming catalyst. It is configured to be adjacent to the reformer 4. As a result, the heat generated by the power generation reaction of the fuel cell 3 and the combustion heat of the surplus gas can be used for the reforming reaction in the reformer 4.

  A gas / water supply means 10 (indicated by a line frame in the figure) for supplying gas and water to the reformer 4 is provided, and the reformed gas supply for supplying the reformed gas. The means 5 comprises an oxygen-containing gas supply means 6 for supplying an oxygen-containing gas, a water supply means 8 for supplying water or water vapor from a water tank 7, and a control means 9 for controlling them. In addition, the same number shall be attached | subjected about the same member and it is the same below.

  In normal operation of the fuel cell, the operation by steam reforming is performed by stopping the oxygen-containing gas from the oxygen-containing gas supply means 6 to the reformer 4 and supplying water from the water supply means 8. This is because steam reforming has higher power generation efficiency than partial oxidation reforming.

  However, when performing steam reforming, an abnormality (failure) may occur in the water supply means 8 for supplying water from the water tank 7 to the reformer 4.

  In this case, when an abnormality or the like occurs in the water supply means 8 and the water supply amount to the reformer 4 becomes a predetermined amount or less, the reformer 4 cannot sufficiently perform the steam reforming. In some cases, the reformer 4 breaks down or control for stopping the operation of the fuel cell 2 has to be performed.

  Therefore, even if an abnormality or the like occurs in the water supply means 8, if the reformer 4 can perform the reforming reaction, the reformer 4 can be prevented from malfunctioning or the fuel cell 2 being stopped. can do.

Here, by connecting the reformer 4 in parallel with the water supply means 8 and an oxygen-containing gas supply means 6, the water supply means 8 cause abnormality, water supply to the reformer 4 is Tokoro When the amount is less than the fixed amount, the control device 9 controls the water supply means 8 to stop and switch to the oxygen-containing gas supply means 6. Thereby, in the reformer 4, it is possible to switch from steam reforming to partial oxidation reforming.

  Therefore, failure of the reformer 4 and stoppage of the fuel cell 2 can be suppressed.

  In the present invention, the predetermined amount of water supplied to the reformer 4 is appropriately changed according to the power generation amount of the fuel cell 2, the operation state such as start / stop, and S / C. It is preferable to be 15 cc / min.

  In this case, when the fuel cell 2 is adversely affected by stopping the water supply unit 8 immediately, both the water supply unit 8 and the oxygen-containing gas supply unit 6 are used in combination for a certain period of time. Switching to the partial oxidation reforming reaction may be performed, or the ratio between the steam reforming and the partial oxidation reforming may be gradually decreased or increased.

  Incidentally, the water supply means 8 can be appropriately selected and used as long as it can supply water to the reformer 4. For example, a water pump or a pipe can be used.

  By the way, in the above-described example, the case where an abnormality (failure) occurs in the water supply unit 8 and the water supply amount to the reformer 4 becomes a predetermined value or less has been described in detail. As a result, the amount of water supplied to the reformer 4 may become a predetermined amount or more.

  In this case, there is a risk that the power generation efficiency of the fuel cell 2 may be significantly reduced as the steam partial pressure in the reformed gas reformed by the reformer 4 increases. In addition, since a predetermined amount or more of water is supplied into the reformer 4, there is a possibility that water may accumulate in the reformer 4. In this case, since the temperature of the reformer 4 is lowered, there is a problem that the reforming reaction cannot be performed efficiently. As a result, the reformer 4 may fail or control that stops the operation of the fuel cell 2 may be performed.

  Here, in the present invention, by connecting the water supply means 8 and the oxygen-containing gas supply means 6 in parallel to the reformer 4, the water supply means 8 causes an abnormality and the like. When the supply amount of water becomes a predetermined amount or more, the control device 9 controls to stop the water supply means 8 and switch to the oxygen-containing gas supply means 6. Thereby, in the reformer 4, it is possible to switch from steam reforming to partial oxidation reforming.

  Therefore, failure of the reformer 4 and stoppage of the fuel cell 2 can be suppressed.

  As in the case described above, in the present invention, the predetermined amount of water supplied to the reformer 4 is appropriately changed according to the power generation amount of the fuel cell 2, the operation state such as start / stop, and S / C. However, it is preferably 1 to 15 cc / min.

  In this case, when the fuel cell 2 is adversely affected by stopping the water supply unit 8 immediately, both the water supply unit 8 and the oxygen-containing gas supply unit 6 are used in combination for a certain period of time. Switching to the partial oxidation reforming reaction may be performed, or the ratio between the steam reforming and the partial oxidation reforming may be gradually decreased or increased.

Figure 2 is a block diagram schematically showing a fuel cell system 11. In FIG. 2, the gas / water supply means 10 is further provided with a water supply means detection device 11.

  Here, when an abnormality occurs in the water supply means 8, the reformer 4 may fail, or the fuel cell 2 may be shut down. Therefore, by providing the water supply means detecting device 11 for detecting the operation of the water supply means 8 and monitoring the operation of the water supply means 8, it is possible to detect that an abnormality has occurred in the water supply means 8.

  Such a fuel cell system 11 will be described. First, the operation range of the operation of the water supply means 8 is set in advance. The water supply means detection device 11 monitors the operation of the water supply means 8 and transmits the information to the control means 9. The control means 9 determines that an abnormality has occurred in the water supply means 8 when the operation of the water supply means 8 is outside the preset setting range. When the control unit 9 determines that an abnormality has occurred in the water supply unit 8, the control unit 9 transmits a signal to the water supply unit 8 to stop its operation and supplies oxygen-containing gas to the oxygen-containing gas supply unit 6. A signal is transmitted to be supplied to the reformer 4.

  Note that such a water supply means detection device 11 may be any apparatus that can detect the operation of the water supply means 8, for example, detecting the amount of water, the number of revolutions of the pump, the number of pump shots, the power consumption of the pump, and the like. A device that can be used can be used.

  Thereby, when the operation of the water supply means 8 is outside the preset setting range (that is, when the predetermined allowable range of operation of the water supply means 8 is exceeded (exceeds or falls below)), Partial oxidation reforming can be performed by stopping the water supply means 8 and switching to the oxygen-containing gas supply means 6.

  Moreover, since the abnormality (operation | movement) of the water supply means 8 is detected by the water supply means detection apparatus 11, it is easy to detect the abnormality of the water supply means 8 due to, for example, fluctuations in the amount of water stored in the water tank 7. An abnormality (operation) of the water supply means 8 can be detected. Thereby, the water supply means 8 and the oxygen-containing gas supply means 6 can be switched accurately.

  Incidentally, if the water supply means 8 is immediately stopped to adversely affect the fuel cell 2, etc., both the water supply means 8 and the oxygen-containing gas supply means 6 are used together for a certain period of time, and the partial oxidation reforming gradually. It may be switched to a quality reaction, or the ratio of steam reforming and partial oxidation reforming may be gradually decreased or increased, respectively.

  Thereby, the failure of the reformer 4 and the operation stop of the fuel cell 2 can be suppressed, and the reforming reaction can be performed stably.

Figure 3 is a block diagram schematically showing a fuel cell system 13. Here, in FIG. 3, the reformer 4 is provided with a temperature sensor 14 for measuring the temperature of the reformer 4.

  When an abnormality occurs in the water supply means 8 and a predetermined amount or more of water is supplied to the reformer 4, water accumulates in the reformer 4 and the temperature of the reformer 4 decreases. Therefore, by providing the temperature sensor 14 in the reformer 4 and monitoring the temperature of the reformer 4, it is possible to detect that an abnormality has occurred in the water supply means 8 (or the possibility that an abnormality has occurred). it can.

  The operation of the fuel cell system 13 will be described. First, the lower limit temperature of the reformer 4 when steam reforming is normally performed is set. The temperature sensor 14 monitors the temperature of the reformer 4 and transmits the information to the control means 9. The control means 9 determines that an abnormality has occurred in the water supply means 8 when the temperature of the reformer 4 transmitted from the temperature sensor 14 falls below a preset temperature (lower limit temperature). When the control unit 9 determines that an abnormality has occurred in the water supply unit 8, the control unit 9 transmits a signal to the water supply unit 8 to stop its operation and supplies oxygen-containing gas to the oxygen-containing gas supply unit 6. A signal is transmitted to be supplied to the reformer 4.

  Thereby, when the temperature of the reformer 4 falls below a preset temperature, the partial supply reforming can be performed by stopping the water supply means 8 and switching to the oxygen-containing gas supply means 6. .

  Such a temperature sensor 14 can be appropriately installed as long as the temperature of the reformer 4 can be measured. For example, a vaporization provided near the inlet of the reformer 4 or inside the reformer 4. It can be installed in a section. In this case, the inlet temperature of the reformer 4 and the vaporizing section temperature of the reformer 4 are measured.

  For example, when the temperature sensor 14 is installed at the inlet of the reformer 4, the lower limit temperature of the inlet temperature of the reformer 4 can be set to 100 ° C. Moreover, when not only the reformer 4 but the vaporizer (not shown) which supplies water vapor | steam to the reformer 4 is installed, the same effect can be acquired by measuring the temperature of a vaporization part. it can.

  Incidentally, if the water supply means 8 is immediately stopped to adversely affect the fuel cell 2, etc., both the water supply means 8 and the oxygen-containing gas supply means 6 are used together for a certain period of time, and the partial oxidation reforming gradually. It may be switched to a quality reaction, or the ratio of steam reforming and partial oxidation reforming may be gradually decreased or increased, respectively.

  Thereby, the failure of the reformer 4 and the operation stop of the fuel cell 2 can be suppressed, and the reforming reaction can be performed stably.

  Incidentally, after the water supply means 8 is stopped and switched to the oxygen-containing gas supply means 6, the temperature of the reformer 4 does not fall within a predetermined temperature range after a certain time has elapsed, or the temperature rise does not exceed the predetermined range. In this case, it can be determined that an abnormality has occurred in the reformer 4.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

  For example, the fuel cell system of the present invention is effective as long as it is a fuel cell system using a steam reforming method, but the fuel cell 3 is preferably a solid oxide fuel cell. Thereby, the fuel cell system of the present invention becomes more effective.

  Further, the water supply means detection device and the temperature sensor described in the present invention can be incorporated into one fuel cell system. Thereby, the abnormality of the water supply means 8 can be detected more reliably by the plurality of detection means.

  In addition, although explanation is omitted, in the fuel cell system of the present invention, a heat exchanger for exchanging heat between exhaust heat of exhaust gas generated by power generation of the fuel cell 2 and water, or hot water storage for storing water after heat exchange A tank or the like may be provided.

  When the abnormality of the water supply means 8 is resolved, that is, when the water supply amount, the temperature of the reformer 4 and the like are improved within a predetermined allowable operation range, steam reforming is performed rather than partial oxidation reforming. It is also possible to return to

  Further, when steam reforming is performed in the reformer 4 in order to supply the reformed gas to the fuel cell 2, pulsation may occur as the water vaporizes. In this case, the pulsation causes, for example, a change in the voltage of the fuel cell 2 and a change in the pressure of the vaporizing section for purifying the steam for steam reforming.

  Therefore, the fuel cell device of the present invention is provided with, for example, a power generation amount monitor for monitoring the power generation amount, a pressure gauge for measuring the pressure of the vaporization section, etc., and when these exceed a predetermined range, water supply means Can be switched to oxygen-containing gas supply means, or both supply means can be used in combination.

1 is a block diagram schematically showing the configuration of a fuel cell system of the present invention. Another configuration of the fuel cell system shows schematically a block diagram of a case where the water supply means detecting device provided in the gas-water supply means. Still another configuration of the fuel cell system shows schematically a block diagram of a case where the temperature sensor is provided to the reformer.

Explanation of symbols

1, 11, 13, 15: Fuel cell system 2: Fuel cell body 3: Fuel cell 4: Reformer 5: Reformed gas supply means 6: Oxygen-containing gas supply means 7: Water tank 8: Water supply means 9 : Control means 10: Gas / water supply means 12: Water supply means detection device 14: Temperature sensor

Claims (1)

A fuel cell; a reformer for supplying a reformed gas to the fuel cell; a reformed gas supply means for supplying a reformed gas to the reformer; Oxygen-containing gas supply means for supplying gas, water tank for storing water to be supplied to the reformer, and water supply means for supplying water or steam from the water tank to the reformer A fuel cell system in which the oxygen-containing gas supply means is stopped during steady operation, and water or steam is supplied to the reformer by the water supply means and the operation is performed by steam reforming. In the steady operation, when the amount of water supplied to the reformer becomes a predetermined amount or more, it is determined that an abnormality or failure has occurred in the water supply means, and the water supply means includes the oxygen-containing unit. Switch to gas supply means or combine both supply means Fuel cell system characterized by comprising a control means for controlling to.

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