JPH0690930B2 - Start / stop control method for fuel cell power generation equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a start / stop control method for a fuel cell power generation facility in which a fuel cell and a fuel reformer are combined, and in particular, gas switching control corresponding to start / stop. Regarding the method.

[Conventional technology]

First, a system diagram of the fuel cell power generation facility shown in Fig. 3 is shown. In the figure, 1 is a fuel cell, 2 is a fuel reformer, and the fuel cell 1 comprises a fuel electrode 1a, an oxidant electrode 1b, an electrolyte layer 1c, a fuel gas chamber 1d, and an oxidant chamber 1e. The quality device 2 is configured by equipping a burner 2d in a combustion furnace 2c containing a vaporizer 2a of a reforming raw material and a reforming reactor 2b. Here, a reforming raw material tank 4 is connected to the inlet of the carburetor 2a of the fuel reformer 2 via a pump 3, and a burner 2d, together with an auxiliary fuel tank 5 and an air blower 6, are connected to the fuel gas chamber of the fuel cell 1. A fuel gas outlet pipe 7 drawn from the outlet side of 1d is connected to the pipe. Reference numeral 8 is an exhaust pipe of the combustion furnace 2c. Further, with respect to the fuel gas chamber 1d of the fuel cell 1, a fuel gas inlet pipe 9 drawn out from the reforming reactor 2b of the fuel reformer 2 and an inert gas supply pipe leading to an inert gas source are provided on the inlet side thereof. A bypass connecting the fuel gas inlet pipe 9, the outlet pipe 7, the inert gas supply pipe 10, and the fuel cell 1 and connecting the fuel gas inlet pipe 9 and the outlet pipe 7 to each other. The pipe 11 has a fuel gas inlet valve 12, an outlet valve 13 and an inert gas supply valve 1 respectively.
4, and a bypass valve 15 are provided. Reference numeral 16 is a blower for supplying reaction air to the oxidant chamber 1e of the fuel cell 1.

In such a fuel cell power generation facility, at the time of preparation for starting the fuel cell, the burner 2d of the fuel reformer 2 is supplemented with auxiliary fuel
Combustion air is supplied and burned, and in this state, the reforming raw material is supplied to the vaporizer 2a. As a result, the reforming raw material is vaporized by the vaporizer 2a and then enters the reforming reactor 2b, where it is reformed into a hydrogen-rich fuel gas by a catalytic reaction with the reforming catalyst. Further, the reformed fuel gas is supplied to the burner 2d through the bypass pipe 11 and the bypass valve 15 which is in an open state, and the amount of heat required for the reforming reaction is given by the combustion here. On the other hand, at this time, the fuel gas chamber 1d of the fuel cell 1 is filled with an inert gas, and the fuel gas inlet valve 12 and the outlet valve 1
3 is closed.

Next, in order to start the fuel cell 1 from the state where the preparation for starting is established, the fuel gas inlet valve 12 and the outlet valve 13 for the fuel gas chamber 1d are opened, the bypass valve 15 is closed, and the fuel gas chamber 1d is connected to the oxidant chamber 1e. The supply of reaction air is started by the air blower 16. As a result, the fuel gas reformed and produced in the fuel reformer 2 is introduced into the fuel gas chamber 1d of the fuel cell through the inlet valve 12, where the inert gas that has been contained in the fuel gas chamber is expelled. At the same time as the replacement, the fuel cell 1 starts power generation by an electromotive reaction. Also fuel gas chamber
The surplus of the fuel gas supplied to 1d that is not involved in the electromotive reaction is supplied as off-gas from the fuel gas chamber 1d through the outlet valve 13 to the burner 2d of the fuel reformer 2 and the amount of heat required for the reforming reaction by combustion. give.

On the other hand, when stopping the fuel cell from the power generation operating state,
The fuel gas inlet valve 12 is closed and the bypass valve 15 is opened to stop the fuel gas supply to the fuel cell, and in the process, the inert gas supply valve 14 is opened to supply the inert gas into the fuel gas chamber. The interior of the room is gas-replaced from the fuel gas with the inert gas. After that, the fuel gas outlet valve 13 is closed to contain the inert gas in the fuel gas chamber 1d.

A time chart of the gas switching control by the conventional control method at the time of starting and stopping the fuel cell described above is shown in FIG. 2. At the time of starting and stopping, the fuel gas inlet valve 12, the outlet valve 13, and the bypass are shown. The valves 15 were simultaneously switched at the same timing (however, the operation when the outlet valve 13 was stopped was excluded).

[Problems to be solved by the invention]

By the way, the above-mentioned conventional start / stop control method of the fuel cell has the following problems. That is, when the fuel gas inlet valve 12, the outlet valve 13 and the bypass valve 15 are simultaneously opened and closed, the internal pressure of the fuel gas chamber 1d on the fuel cell side momentarily fluctuates greatly due to the deviation of the opening / closing response of each valve and the like. . For this reason, an excessive differential pressure is generated between the fuel gas chamber 1d and the oxidant chamber 1e, and as a result, reaction gas crossover occurs through the electrolyte layer 1c, or the electrode is destroyed by the excessive differential pressure. There is a risk of Further, especially at the time of startup, the inert gas filled in the fuel gas chamber 1d during the previous stop period is expelled by the fuel and returned to the burner 2d of the fuel reformer 2 at once, so that the burner is insufficient due to lack of fuel. There is a risk that the combustion of will accidentally ignite.

The present invention has been conceived in view of the above points, and an object thereof is an excessive differential pressure between a fuel gas chamber and an oxidant chamber when switching gas at the time of starting and stopping a fuel cell, and a reformer burner. Provide a start-up / shutdown control method for a fuel cell power generation facility, which prevents accidental misfires in advance and improves safety, and also enables smooth gas replacement by an inert gas in a fuel gas chamber. Especially.

[Means for solving problems]

In order to solve the above problems, according to the present invention, a fuel cell and an oxidant electrode provided with an electrolyte layer sandwiched between them, and a fuel gas chamber and an oxidant gas chamber provided corresponding to each of the electrodes are provided. Of the fuel cell, a fuel cell provided with a reforming reactor for supplying a reforming raw material to generate a hydrogen-rich fuel gas, and a burner for supplying heat of the reforming reaction, An inert gas supply system for filling the fuel gas chamber with an inert gas when stopped, and an air supply means for supplying air to the oxidant gas chamber and the burner,
A fuel gas inlet pipe for supplying the fuel gas generated by the reforming reaction to the fuel gas chamber, and an off fuel gas discharged from the fuel gas chamber without being consumed by the electromotive reaction in the fuel cell to the burner. A fuel gas outlet pipe for supplying and a bypass pipe connecting between the fuel gas inlet pipe and the fuel gas outlet pipe for supplying the fuel gas generated by the reforming reaction to the burner by bypassing the fuel cell. A fuel gas inlet valve and a fuel gas outlet valve, which are disposed on the fuel cell side of the bypass pipe connection portion and on the lines of the fuel gas inlet pipe and the fuel gas outlet pipe, respectively, and on the line of the bypass pipe. In a start-up / shutdown control method for a fuel cell power generation facility including a bypass valve interposed in a fuel cell, the fuel gas outlet valve is first opened when the fuel cell is started, and then the fuel gas inlet valve is opened. Closed the bypass valve, and at the time of stop, first opened the bypass valve and then closed the fuel gas inlet valve.Here, the fuel gas chamber was replaced with the inert gas supplied through the inert gas supply system, and then the fuel gas outlet valve was closed. The respective valves are opened and closed by giving a time difference to each other so as to close them.

[Action]

By adopting the above control method, the fuel gas outlet valve is first opened and then the inlet valve is opened when the fuel cell is started, so the fuel gas chamber is not affected by the mechanical opening response time delay of the valve. It is possible to reliably avoid a sudden increase in internal pressure due to the introduction of fuel gas into the fuel cell, and by closing the bypass valve with a time lag after opening the inlet valve,
Even in the process of expelling the inert gas filled in the fuel gas chamber toward the burner of the fuel reformer, the supply of fuel gas to the burner is secured through the bypass valve, and therefore accidental misfire of the burner can be prevented.

Even when stopped, the bypass valve is opened, the inlet valve is closed prior to the fuel gas outlet valve, and the fuel gas chamber is replaced with an inert gas in this state, so that the oxidant chamber is replaced with the oxidant chamber. The gas replacement can be smoothly performed while avoiding the generation of excessive pressure difference between the two and burner misfire of the fuel reformer.

〔Example〕

FIG. 1 is a time chart of the start / stop control of the fuel cell according to the present invention. The gas switching operation at the time of start / stop of the fuel cell will be described with reference to FIG. 3 together with the time chart.

First, when the fuel cell is ready to start up, the reforming raw material is reformed into the hydrogen-rich fuel gas in the fuel reformer 2 as in the conventional case, and then the burner of the reformer is passed through the bypass valve 15 which is in the open state.
Reflux to 2d, where it burns to provide the heat necessary for the reforming reaction. On the other hand, at this time, the fuel gas inlet valve 12 and the outlet valve 13 of the fuel cell 1 are closed, the inside of the fuel gas chamber 1d is filled with the inert gas, and the inert gas supply valve 14 is also closed. is there.

When starting the fuel cell 1, the fuel gas outlet valve 13 is first opened, and the inlet bias 12 is opened with a delay of a designated time difference t1. As a result, the fuel gas obtained in the reformer 2 becomes the fuel gas chamber.
While being introduced into 1d to push out the inert gas to replace the gas, the fuel cell 1 starts power generation by an electromotive reaction with the reaction air supplied to the oxidant chamber 1e. At this time, the bypass valve 15 is open, and a part of the fuel gas is continuously supplied to the burner 2d of the reformer through the bypass valve 15.
The inert gas expelled from the fuel gas chamber due to the gas replacement does not accidentally cause the burner to misfire, and the internal pressure of the fuel gas chamber does not suddenly increase. on the other hand,
After the inlet valve 12 is opened, the bypass valve 15 is closed after a delay of time t2 required to completely replace the gas in the fuel gas chamber 1d, and the entire amount of the fuel gas generated in the reformer 2 is changed to the fuel gas of the fuel cell. While supplying to room 1d to shift to steady power generation,
The off gas is returned to the burner 2d of the reformer 2 to continue the reforming operation.

On the other hand, when shutting down the fuel cell, first the bypass valve 15
Is opened, and a part of the fuel gas generated in the reformer 2 is bypass-supplied to the burner 2d of the reformer through the bypass valve 15. Next, the fuel gas inlet valve 12 is closed with a delay of time difference t3,
In this state, the inert gas supply valve 14 is opened to open the fuel gas chamber 1d.
The inside is replaced with an inert gas. Further, the fuel gas outlet valve 13 is closed with a delay of the time t4 required for this gas replacement to contain the inert gas in the fuel gas chamber 1d. As a result, gas replacement can be performed smoothly, a sudden change in the internal pressure of the fuel gas chamber 1d, an excessive pressure difference between the fuel gas chamber 1d and the oxidant chamber 1e, and a fuel gas supply interruption on the reformer side It is possible to reliably prevent accidental misfire of the burner 2d due to.

〔The invention's effect〕

As described above, according to the present invention, when the fuel cell is activated, the fuel gas outlet valve is first opened, then the inlet valve is opened and then the bypass valve is closed, and when stopped, the bypass valve is first opened and then the inlet valve is closed. At the time of starting and stopping the fuel cell, the fuel gas chamber is replaced with the inert gas supplied through the inert gas supply system, and then the valves are opened and closed by giving a time difference to each other so that the outlet valves are closed. Improving safety by preventing sudden changes in the internal pressure of the fuel gas chamber, generation of excessive differential pressure between it and the oxidant chamber, and accidental misfires in the burner of the fuel reformer. At the same time, the gas replacement between the fuel gas and the inert gas in the fuel gas chamber can be smoothly performed.

[Brief description of drawings]

FIG. 1 is a time chart of gas switching control when starting and stopping a fuel cell according to an embodiment of the present invention, and FIG. 2 is a time chart of a conventional control method corresponding to FIG.
FIG. 3 is a system diagram of a fuel cell power generation facility. In the figure, 1: fuel cell, 1d: fuel gas chamber, 2: fuel reformer, 2d: combustion burner, 4: reforming raw material tank, 10: inert gas supply pipe, 12: fuel gas inlet valve, 13: Fuel gas outlet valve, 14: inert gas supply valve, 15: fuel gas bypass valve.

Claims (1)

[Claims] 1. A fuel cell provided with a fuel electrode and an oxidant electrode sandwiching an electrolyte layer, and a fuel gas chamber and an oxidant gas chamber provided corresponding to each of the electrodes, and a reforming raw material. Is supplied to produce a hydrogen-rich fuel gas and a fuel reformer having a burner for supplying heat of the reforming reaction, and an inert gas in the fuel gas chamber when the fuel cell is stopped. An inert gas supply system for filling the air, an air supply means for supplying air to the oxidant gas chamber and the burner, and a fuel gas for supplying the fuel gas generated by the reforming reaction to the fuel gas chamber. An inlet pipe, a fuel gas outlet pipe for supplying the burner with off-fuel gas exhausted from the fuel gas chamber without being consumed by an electromotive reaction in the fuel cell, and a fuel gas produced by the reforming reaction as fuel. Bypass the battery A bypass pipe connecting between the fuel gas inlet pipe and the fuel gas outlet pipe for supplying to the burner, and a fuel cell side of the bypass pipe connecting portion of the fuel gas inlet pipe and the fuel gas outlet pipe. A start and stop control method for a fuel cell power generation facility comprising a fuel gas inlet valve and a fuel gas outlet valve respectively installed on a line, and a bypass valve installed on the line of the bypass pipe, When the fuel cell is started, the fuel gas outlet valve is first opened, then the fuel gas inlet valve is opened and then the bypass valve is closed, and when the fuel cell is stopped, the bypass valve is first opened and then the fuel gas inlet valve is closed. A fuel characterized in that after the fuel gas chamber is replaced with an inert gas supplied through a supply system, the fuel gas outlet valve is closed and a time lag is applied to open and close each valve. Start-up of the cell power plant, stop control method.