JP3089784B2 - Molten carbonate fuel cell temperature rise control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a temperature rise of a molten carbonate fuel cell.

[0002]

2. Description of the Related Art A conventional means for raising the temperature of a molten carbonate fuel cell at the time of startup is, for example, as shown in FIG.
In FIG. 3, reference numeral 31 denotes a fuel cell having a cathode C and an anode A, etc., 32 denotes a cathode gas inlet line,
3 is a cathode gas inlet valve, 34 is a cathode exhaust gas line, 35 is a cathode gas outlet valve, 36 is a cathode gas circulation line, 37 is a cathode gas circulation blower, 38 is a gas heater, 39 is a heating line, and 40 is an anode gas inlet. Line 41 is an anode exhaust gas line. That is,
A method of raising the temperature at the time of starting the fuel cell 31 is to completely close the cathode gas inlet valve 33 and the cathode gas outlet valve 35 to form a closed loop with the cathode gas circulation line 36 and the cathode C of the fuel cell 31, Is circulated in the closed lube and is heated by the gas heater 38 on the way.

[0003]

However, in the above-described conventional temperature raising method, since appropriate control is not performed, when the temperature of the fuel cell 31 is raised, the fuel cell 31 may be rapidly heated. In this case, an excessive thermal stress is generated in the battery member, which causes a problem that the battery member is damaged or deformed such as a crack in the electrolyte.

[0004] The present invention is to solve the above problems. That is, the present invention provides a safe battery in which the temperature difference between the temperature of the cathode gas heated in the closed loop and the temperature of the battery member falls within an appropriate range, thereby preventing the battery from being heated quickly. It is an object of the present invention to provide a method for controlling a temperature rise of a molten carbonate fuel cell capable of raising the temperature of a molten carbonate fuel cell.

[0005]

In order to achieve the above object, the present invention provides a fuel cell plant having a cathode gas circulation blower and a gas heater in a cathode gas circulation line. A method of forming a closed loop with the cathode gas circulation line and the fuel cell by fully closing the gas inlet valve and the cathode gas outlet valve, and circulating and heating the cathode gas in the closed loop, wherein the cathode gas inlet of the closed loop and The temperature of each gas at the cathode gas outlet is detected, the temperature difference between the inlet and the outlet is obtained, and the calorific value of the gas heater is adjusted based on this temperature difference, so that the temperature difference falls within a predetermined range. It consisted of raising the temperature while keeping it.

[0006]

According to the present invention, the temperature is raised while maintaining the temperature difference between the cathode gas inlet and the cathode gas outlet of the closed loop within a predetermined range, so that the temperature of the heating gas heated by the gas heater and the temperature of the battery member are increased. Is also within an appropriate range, and the battery is not rapidly heated.

[0007]

FIG. 1 is an explanatory view showing a part of a fuel cell plant for carrying out a first embodiment of the method of the present invention. In FIG. 1, 1 is a cathode gas inlet line, 2 is a cathode gas inlet valve, 3 is a fuel cell having a cathode C and an anode A, 4 is a cathode gas outlet valve, 5 is a cathode exhaust gas line, 6 is cathode gas A circulation line, 7 is a cathode gas circulation blower, 8 is a gas heater using combustion gas or electric heat as a heat source, 9 is a heating line, 10 is an anode gas inlet line, 11 is an anode exhaust gas line, and 12 is a cathode inlet of a closed loop described later. Is a temperature detector for detecting the gas temperature at the cathode outlet, 13 is a temperature controller, and 15 is a calorific value adjuster.

That is, when the fuel cell 3 is started, it is necessary to raise the temperature of the cell 3 from room temperature. Therefore, the cathode gas inlet valve 2 and the cathode gas outlet valve 4 are fully closed, and the cathode gas circulation line 6 and the fuel gas A closed loop is formed with the cathode C of the battery 3, and the cathode gas is circulated in the closed loop and heated by the gas heater 8. In this case, the gas temperature at the cathode gas inlet of the closed loop is detected by the temperature detector 12, the gas temperature at the cathode gas outlet is detected by the temperature detector 13, and each detection signal is sent to the temperature difference controller 14,
The temperature difference controller 14 calculates the temperature difference between the inlet and the outlet, sends a signal corresponding to this temperature difference to the calorific value adjuster 15, and adjusts the calorific value of the gas heater 8 with the calorific value adjuster 15. The temperature is raised such that the temperature difference is kept within a predetermined range.

For example, when the melting point of the electrolyte is 490 ° C., the temperature difference is increased to about 50 ° C. per hour until just before 490 ° C.
The temperature is raised to about 10 ° C. per hour.

[0010] By doing so, the temperature difference between the heating gas temperature and the battery member temperature is also within an appropriate range, and the battery is not rapidly heated. Excessive cracking of the electrolyte, excessive thermal stress of the member, and excessive thermal strain can be prevented.

FIG. 2 is an explanatory view showing a part of a fuel cell plant for carrying out a second embodiment of the method of the present invention. In FIG. 2, reference numerals 1 to 15 are the same as those in FIG.
16 is a raw fuel gas line, 17 is a reformer, 18 is a reformer fuel supply line, 19 and 20 are air supply lines, 21 is a reformer combustion exhaust gas line, 22 is a heat exchanger,
Reference numeral 23 denotes a temperature detector that detects the temperature of the battery body (representative point).

That is, also in the second embodiment, when the temperature of the fuel cell 3 is raised, the cathode gas inlet valve 2 and the cathode gas outlet valve 4 are fully closed, as in the first embodiment. A closed loop is formed by the gas circulation line 6 and the cathode C of the fuel cell 3, and the cathode gas is circulated in the closed loop and heated by the gas heater 8. In this case, the temperature of the gas at the inlet and outlet of the cathode gas of the closed loop is detected by the temperature detectors 12 and 13, the temperature of the battery body (representative point) is detected by the temperature detector 23, and the respective detection signals are adjusted to the temperature difference. The temperature difference between the gas temperature at the cathode gas inlet (the temperature detected by the temperature detector 12) and the temperature of the battery body (the temperature detected by the temperature detector 23) is lower than a specified value. No, it is determined whether the temperature difference between the temperature at the cathode gas inlet and the temperature at the cathode gas outlet is equal to or less than a specified value, the deviation is obtained, and a signal corresponding to this deviation is sent to the calorific value adjuster 15 to generate heat. The amount adjuster 15 adjusts the amount of heat generated by the gas heater 8 so as to eliminate the deviation. Further, a signal is sent from the temperature difference controller 14 to the calorific value adjuster 15 so that the rate of temperature rise (temperature per unit opening) of the battery body temperature does not exceed a specified value, thereby limiting the calorific value of the gas heater 8. You can also. Thus, from the first embodiment,
The fuel cell can be safely heated by finer control. That is, in the second embodiment, similarly to the first embodiment, the temperature of the battery can be safely increased, and the cathode gas inlet valve 2 and the cathode gas When the cathode gas inlet temperature (detected by the temperature detector 12) becomes lower than a specified value, for example, 520 ° C. or less while the outlet valve 4 is fully opened, a signal corresponding to the temperature drop is sent to the temperature difference controller 14. To the calorific value adjuster 15 to heat the cathode circulating gas from the gas heater 8 to prevent solidification of the electrolyte. Note that the gas heater 8 is not used during the load operation.

[0013]

As described above, according to the present invention,
Since the temperature is raised while maintaining the temperature difference between the cathode gas inlet and the cathode gas outlet of the closed loop within a predetermined range, the temperature difference between the heating gas heated by the gas heater and the battery member is also within an appropriate range. In other words, it is possible to prevent trouble due to rapid heating of the battery and to safely raise the temperature of the battery.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a part of a fuel cell plant for implementing a first embodiment of the method of the present invention.

FIG. 2 is an explanatory diagram showing a part of a fuel cell plant for implementing a second embodiment of the method of the present invention.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 2: Cathode gas inlet valve 3: Fuel cell 4: Cathode gas outlet valve 6: Cathode gas circulation line 7: Cathode gas circulation blower 8: Gas heater 12, 13, 23: Temperature detector 14: Temperature difference controller 15: Calorific value adjuster

Claims (4)

(57) [Claims] 1. A fuel cell plant having a cathode gas circulation blower and a gas heater in a cathode gas circulation line, wherein the cathode gas inlet valve and the cathode gas outlet valve are fully closed when the temperature of the battery is raised. In a method of forming a closed loop between the gas circulation line and the fuel cell and circulating and heating the cathode gas in the closed loop, the gas temperature of each of the cathode gas inlet and the cathode gas outlet of the closed loop is detected, and the inlet and the cathode are detected. A molten carbonate fuel, characterized in that a temperature difference at an outlet is obtained, and a calorific value of the gas heater is adjusted based on the temperature difference, and the temperature is raised while maintaining the temperature difference within a predetermined range. Battery temperature control method. 2. The gas heater according to claim 1, wherein the gas heater is an electric heater.
A method for controlling a temperature rise of a molten carbonate fuel cell according to the above. 3. When the battery is started, the gas temperature difference between the inlet and outlet of the cathode gas is set to be large up to near the melting point of the electrolyte, and thereafter, the temperature difference is set to be small and the temperature is raised. 3. The method for controlling a temperature rise of a molten carbonate fuel cell according to 1 or 2. 4. The method according to claim 1, wherein when the battery is started, the temperature of the battery body is detected to determine a temperature difference from a cathode gas inlet temperature, and the temperature is raised while keeping the temperature difference within a predetermined range. A method for controlling a temperature rise of a molten carbonate fuel cell according to the above.