JP4728567B2 - Fuel cell system and its start / stop storage method - Google Patents

Description

  The present invention relates to a fuel cell system that can be safely started and stopped and stored without purging with nitrogen gas or the like, and a start and stop storage method thereof.

  The fuel cell system includes a fuel reforming system, reforms the raw fuel into a hydrogen-rich fuel gas, and generates power by reacting hydrogen in the fuel gas with oxygen in the air in the fuel cell body. Yes.

  However, if flammable raw fuel or fuel gas remains in the fuel reforming system or the like while the fuel cell system is stopped, it may leak out of the machine and ignite.

  Therefore, a proposal has been made to perform nitrogen purge in order to discharge the raw fuel or fuel gas remaining in the fuel reforming system outside the system when the fuel cell system is stopped (see Patent Document 1).

  FIG. 5 is a diagram showing a schematic configuration of such a fuel cell system. The fuel cell system includes a fuel cell main body 1, a fuel reforming system 2, a nitrogen supply facility 5, and the like.

  When the fuel cell system is stopped, the fuel reforming system inlet valve 3 is closed and the supply of raw fuel to the fuel reforming system 2 is stopped.

  Thereafter, the nitrogen valve 6 is opened to introduce nitrogen gas into the fuel reforming system 2 from the nitrogen supply facility 5, and the raw fuel or fuel gas remaining in the fuel reforming system 2 and the like is replaced with nitrogen gas.

In recent years, considering the introduction of fuel cell systems to general households, for example, the fuel reforming system 2 or the like is purged with steam to replace combustible gas, and then the condensation generated in the fuel reforming system 2 or the like A stopping method of purging with air to remove water and a method of purging the fuel reforming system 2 and the like by effectively using plant exhaust gas have been proposed.
JP 2002-151124 A

  However, when purging the fuel reforming system 2 and the like using nitrogen gas, the nitrogen supply equipment 5 and nitrogen gas are required separately, and the piping of nitrogen gas is necessary, which complicates and enlarges the system. There was a problem that caused an increase in system cost and running cost.

  In addition, when introducing a fuel cell system for purging with such nitrogen gas to ordinary households, it becomes difficult to secure an installation area as the size increases, and the nitrogen gas supply system is immature, so it is widely used. There was a problem that did not progress.

  Further, the method of purging the fuel reforming system 2 and the like using steam and air has a problem that it cannot be applied to a fuel cell system equipped with a partial oxidation reformer having no steam system.

  Further, the method of purging the fuel reforming system 2 and the like using plant exhaust gas is provided with auxiliary power such as raw fuel blower and burner air blower for generating exhaust gas, and the auxiliary power after the plant is stopped. Therefore, there is a problem that new equipment is required and power for driving the auxiliary machine power is required.

  Accordingly, the present invention provides a fuel cell system and a start / stop storage method for safely starting and stopping the fuel cell system and storing the fuel cell system without providing the above-described nitrogen supply equipment and auxiliary equipment. For the purpose.

In order to solve the problems, an invention relating to a fuel cell system includes a fuel reforming system that reforms raw fuel to generate a hydrogen-rich fuel gas, hydrogen in the fuel gas from the fuel reforming system, and air In a fuel cell system comprising a fuel cell main body that generates electricity by reacting with oxygen, an inlet switch that opens and closes the inlet of the fuel reforming system, and an outlet switch that opens and closes the outlet of the fuel reforming system And a control unit that controls the inlet switch and the outlet switch to close the inlet and the outlet of the fuel reforming system when the fuel cell system is stopped, and the control unit includes the fuel cell system. When starting the engine, the inlet switch and the outlet switch are controlled to open the inlet and outlet of the fuel reforming system. At that time, the inlet of the fuel reforming system is first opened and the fuel reforming system is opened. Set the pressure of the quality system above atmospheric pressure and then And controlling to open the outlet of the fuel reformer system.

The invention relating to the start / stop storage method of the fuel cell system includes a fuel reforming system that reforms raw fuel to generate a hydrogen-rich fuel gas, and hydrogen and air in the fuel gas from the fuel reforming system. When stopping a fuel cell system including a fuel cell main body that generates electricity by reacting with oxygen therein, the fuel gas remaining in the fuel reforming system is made an isolated system the confined within the fuel reforming system, when starting the fuel cell system, after the raw fuel to flow into the fuel reforming system, have lines supplying the fuel gas generated in the fuel reforming system, In that case, first, the fuel reforming system is controlled such that the inlet of the fuel reforming system is opened to set the pressure of the fuel reforming system to atmospheric pressure or higher, and then the outlet of the fuel reforming system is opened .

  According to the present invention, since the residual fuel gas of the fuel reforming system is confined in this fuel reforming system, the start and stop of the fuel cell system can be performed without purging the residual fuel gas with nitrogen gas or water vapor. Storage can be performed safely, and the fuel cell system can be simplified, reduced in cost, reduced in size, and reduced in running cost.

  Further, since no nitrogen supply facility is required, the spread of the fuel cell system 10 to general households can be promoted.

  Furthermore, since it can be applied to a fuel cell system equipped with a partial oxidation reformer that does not have a steam system, it can be used widely.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the main part of the invention of the fuel cell system applied to the description of the first embodiment. In addition, about the same structure as before, the same code | symbol is used and description is abbreviate | omitted suitably.

  The fuel cell system 10 includes a fuel cell main body 1, a fuel reforming system 2, an inlet switch 7 and an outlet switch 8 provided at the inlet and outlet of the fuel reforming system 2, the inlet switch 7 and the outlet opening / closing. And a control unit 6 for controlling the device 8.

  In addition, as the inlet switch 7 and the outlet switch 8, a valve that operates in a binary manner of “open” and “closed” can be applied, but a valve whose opening degree can be adjusted may be used.

  Such starting and stopping of the fuel cell system 10 are performed as follows. First, when the fuel cell system 10 is stopped, the control unit 6 controls the inlet switch 7 and the outlet switch 8 to close the inlet and outlet of the fuel reforming system 2 in this order.

  As a result, the residual fuel gas in the fuel reforming system 2 is confined in the fuel reforming system 2, so that there is no possibility that the residual fuel gas leaks to the outside.

  On the other hand, when starting from such a stop state, as shown in FIG. 2, the control unit 6 first controls the inlet switch 7 to open the inlet (in the state of P1), thereby supplying the raw fuel to the fuel. Introduce into the reforming system 2. As a result, when the pressure of the fuel reforming system 2 rises and becomes atmospheric pressure or higher, the outlet switch 8 is controlled to open the outlet (state of P2).

  The reason why the inlet is opened first and then the outlet is opened is as follows.

  That is, when the inlet and outlet are closed and the fuel cell system 10 is stopped, the pressure of the fuel reforming system 2 that has become an isolated system may drop with a decrease in temperature and become a negative pressure state.

  When the outlet is opened before the inlet in this negative pressure state, if air is contained in the pipe downstream of the fuel reforming system 2, the air flows back to the fuel reforming system 2, and the fuel reforming system The situation which reacts with hydrogen in 2 arises.

  Therefore, first, the inlet is opened to bring the pressure of the fuel reforming system 2 to atmospheric pressure or higher, and then the outlet is opened, so that even if air is contained in the piping on the downstream side of the fuel reforming system 2, the air is fuel-modified. It does not flow into the quality system 2.

  With the above configuration, the fuel cell system can be safely started and stopped without purging the residual fuel gas with nitrogen gas, water vapor, etc., and the fuel cell system can be simplified, reduced in cost, and made compact. In addition, the running cost can be reduced.

  Further, since no nitrogen supply facility is required, the spread of the fuel cell system 10 to general households can be promoted.

  Furthermore, since it can be applied to a fuel cell system equipped with a partial oxidation reformer that does not have a steam system, it can be used widely.

  In the above description, when the inlet switch and the outlet switch 8 are controlled to open the inlet and outlet, the case of opening in steps has been described, but the present invention is not limited to this, You may make it open gradually.

  FIG. 3 is a diagram showing the timing when the inlet is gradually opened. When starting up, the inlet is gradually opened (P3 state), and the pressure of the fuel reforming system 2 becomes equal to or higher than atmospheric pressure. The inlet switch 7 and the outlet switch 8 are controlled so that the outlet is opened (state of P4) when there is no possibility that the air in the pipe flows back to the fuel reforming system 2.

  In this way, the inlet is gradually opened to prevent the raw fuel from entering the fuel reforming system 2 by opening the inlet stepwise, and is used for the fuel reforming system 2 due to the entry of the raw fuel. This is to suppress the influence on the catalyst and the like.

  In addition, when opening an exit, it is preferable to open gradually for the same reason. That is, when the outlet is opened, the inlet is already opened. Therefore, when the outlet is opened stepwise, the pressure of the fuel reforming system 2 is suddenly reduced, and the raw fuel enters. In order to prevent this, it is preferable to control the outlet switch 8 so that it gradually opens when the outlet is opened.

  However, since the pressure fluctuation of the fuel reforming system 2 when the outlet is opened stepwise is smaller than the pressure fluctuation of the fuel reforming system 2 when the inlet is opened stepwise, the outlet is faster than the inlet by that amount. It is possible to open at speed.

  As described above, in order to gradually open the inlet and the outlet, for example, the inlet switch 7 and the outlet switch 8 are motorized valves, and the controller 6 gradually increases the drive current in an analog or digital manner. This can be achieved by changing the drive.

  As described above, it is possible to start and stop the fuel cell system 10 safely while preventing deterioration of characteristics of the catalyst and the like.

  Next, a second embodiment of the present invention will be described. FIG. 4 is a timing chart showing the operation of the inlet switch during stop storage of the fuel cell system applied to the description of the present embodiment. In addition, about the same structure as 1st Embodiment, description is abbreviate | omitted suitably using the same code | symbol.

  The first embodiment relates to the start and stop of the fuel cell system 10. In contrast, the present embodiment relates to storage (stopping) of the fuel cell system 10.

  As described above, when the fuel cell system 10 is stopped, the pressure of the fuel reforming system 2 gradually decreases. Normally, the fuel reforming system 2 is designed to withstand the pressure of the raw fuel, but the state in which the fuel reforming system 2 becomes negative pressure at that time is not much considered.

  Therefore, if the inlet and outlet of the fuel reforming system 2 are closed and isolated for a long time, there is a concern that explosion may occur in some cases.

  Therefore, in the present invention, when the fuel cell system 10 is stopped every predetermined time or when the pressure of the fuel reforming system 2 becomes a predetermined pressure, the control unit 6 opens and closes the inlet for a predetermined time t as shown in FIG. The raw fuel is introduced into the fuel reforming system 2 by controlling the vessel 7 and opening the inlet.

  As a result, even when the fuel cell system 10 is stopped, the pressure of the fuel reforming system 2 is adjusted, so that it is possible to prevent inconvenience such as contraction.

It is a block diagram which shows the principal part of the fuel cell system applied to description of each embodiment of this invention. It is a timing chart which shows the operation timing of an entrance switch and an exit switch at the time of starting. It is a timing chart in the case of opening an inlet switch gradually at the time of starting. It is a timing chart which shows operation of an entrance switch at the time of stop storage of a fuel cell system applied to explanation of a 2nd embodiment. It is a figure which shows schematic structure of the fuel cell system applied to description of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell main body 2 Fuel reforming system 6 Control part 7 Inlet switch 8 Outlet switch 10 Fuel cell system

Claims (6)

A fuel reforming system that reforms the raw fuel to generate a hydrogen-rich fuel gas, and a fuel cell body that generates electricity by reacting hydrogen in the fuel gas from the fuel reforming system with oxygen in the air; In a fuel cell system comprising:
An inlet switch for opening and closing the inlet of the fuel reforming system;
An outlet switch for opening and closing the outlet of the fuel reforming system;
A control unit that controls the inlet switch and the outlet switch to close the inlet and outlet of the fuel reforming system when stopping the fuel cell system;
Wherein the control unit is, when starting the fuel cell system, the inlet switch and controls the exit switch, it said open the inlet and outlet of the fuel reformer system, firstly the fuel reforming in that case And controlling the fuel reforming system so that the pressure of the fuel reforming system is at or above atmospheric pressure and then the outlet of the fuel reforming system is opened .   2. The control unit according to claim 1, wherein the control unit controls the inlet switch and the outlet switch to open the inlet prior to the outlet and to gradually open the inlet. Fuel cell system.   The control unit controls the inlet switch so that only the inlet is opened according to the pressure of the fuel reforming system or at predetermined time intervals when the fuel cell system is stopped. Item 4. The fuel cell system according to Item 1. A fuel reforming system that reforms the raw fuel to generate a hydrogen-rich fuel gas, and a fuel cell body that generates electricity by reacting hydrogen in the fuel gas from the fuel reforming system with oxygen in the air; When the fuel cell system including the fuel cell system is stopped, the fuel reforming system is made an isolated system and the fuel gas remaining in the fuel reforming system is confined in the fuel reforming system. when starting the system, after allowed to flow into the raw fuel to the fuel reforming system, have row the supply of the fuel gas generated in the fuel reforming system, firstly the fuel reforming in that case A start-stop storage method for a fuel cell system , wherein control is performed such that the inlet of the system is opened to bring the pressure of the fuel reforming system to atmospheric pressure or higher and then the outlet of the fuel reforming system is opened .   5. The fuel cell according to claim 4, wherein when the fuel cell system is started, the inflow amount of the raw fuel and the outflow amount of the fuel gas are adjusted so that the pressure of the fuel reforming system gradually changes. System start / stop storage method.   When the fuel cell system is stopped and stored, the raw fuel is introduced into the fuel reforming system every predetermined time or according to the pressure of the fuel reforming system, and the pressure of the fuel reforming system is reduced. 6. The start / stop storage method for a fuel cell system according to claim 4, wherein negative pressure is prevented.