JPS62160667A - Fuel cell power generation system - Google Patents

Abstract

PURPOSE:To improve the responsiveness to a load on a fuel cell by providing a pressure/flow controller for eliminating mutual intervention between oxidant gas flow control and cathode pressure control. CONSTITUTION:An oxidant gas flow controller and a cathode pressure controller are omitted respectively and a pressure/flow noninterference controller 9 is provided in stead of them. Then, an oxidant gas flow detection value signal (b) and oxidant gas flow target value signal (a) from a flow detector 5, and an oxidant electrode pressure detection value signal (f) and oxidant electrode pressure target value signal (e) from a pressure detector 6 are inputted respectively. Based on these respective signals, a valve opening command signal (i) for an oxidant gas flow controller 3 and a valve opening command signal (j) for a pressure control valve 4 are inputted respectively.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel cell power generation system, and particularly relates to a fuel cell power generation system capable of improving load responsiveness of gas flow rate and pressure control in a fuel cell. be.

[Technical background of the invention]

Conventionally, fuel cells have been known as devices that directly convert chemical energy contained in fuel into electrical energy. This fuel-flour cell typically includes a pair of electrodes, each consisting of a fuel species (hereinafter referred to as anode) and an oxidizer electrode (hereinafter referred to as cathode), sandwiching a matrix impregnated with an electrolyte and having a thickness of one shoe or less, and A fuel gas such as hydrogen gas is supplied to the anode, and an oxidizing gas such as air is supplied to the cathode, and the electrochemical reaction that occurs at this time is used to extract electrical energy from between the two electrodes. As long as the fuel gas and oxidant gas are supplied, electrical energy can be extracted with high conversion efficiency.

In such fuel cells, fuel gas or oxidant gas easily permeates due to the pressure difference between the anode and cathode (hereinafter referred to as interelectrode pressure difference), reducing the power generation efficiency, that is, the single cell characteristics. This will not only accelerate the deterioration of the equipment, but also accelerate the deterioration of the equipment. Furthermore, it has been confirmed that if this interelectrode differential pressure exceeds a certain permissible value, the matrix constituting the fuel cell will be damaged. On the other hand, fuel cells require a high degree of load responsiveness in their operating method, so it is necessary to ensure appropriate gas flow rates at the anode and cathode in response to load fluctuations. Therefore, as a device for controlling the pressure and flow rate in such a fuel cell, it is necessary to suppress the differential pressure between the electrodes to maintain the system, and to control the anode and flow rate as load responsiveness.
It is required to perform each gas flow control of the cathode at the same time.

FIG. 3 is a block diagram showing an example of the configuration of a fuel cell power generation system using a conventional pressure/flow rate control device.

In FIG. 3, reference numeral 1 consists of a pair of electrodes, an anode 1a and a cathode 1b, arranged with an electrolyte-impregnated matrix in between.
This is a fuel cell in which an oxidant gas is supplied to each of the electrodes 1a and 1b, and electrical energy is extracted from between the electrodes 1a and 1b through the electrochemical reaction that occurs at this time. Reference numerals 2 and 3 refer to a fuel gas flow rate control valve and an oxidant gas flow rate control valve provided on the fuel gas and oxidant gas supply lines to the fuel cell 1, respectively; 4 indicates the oxidant gas supplied from the fuel cell 1; 5 is a flow rate detector for detecting the gas flow rate passing through the oxidant gas supply line, and 6 is a pressure detector for detecting the pressure of the cathode 1b.

On the other hand, the flow rate control of the oxidizing gas is obtained by comparing the oxidizing gas flow rate target value signal a determined based on the battery output etc. and the oxidizing gas flow rate detected value signal S from the flow rate detector 5. Based on the deviation signal C, the oxidizing gas flow rate controller 7 outputs the oxidizing gas flow ff1X [valve opening command signal d to the oxidizing gas flow rate regulating valve 3, thereby opening the oxidizing gas flow rate. There is. Further, the pressure control of the cathode 1b is performed using a deviation signal q obtained by comparing a cathode pressure target value signal e given based on the pressure of the anode 1a and a cathode pressure detection value signal f from the pressure detector 6. Based on this, the cathode pressure regulator 8 outputs a cathode pressure regulating valve opening command signal to the pressure regulating valve 4. Note that the fuel gas flow rate control is performed by a fuel gas flow rate control valve 2.

In a fuel cell power generation system with such a configuration, when the cell load increases, the amount of fuel gas and oxidant gas consumed by the fuel cell 1 increases, but the supply of fuel gas is insufficient to compensate for this increase. The supply of the oxidizing gas is performed by controlling the flow rate of the oxidizing gas. On the other hand, such a load change causes a change in the gas balance at each of the anode 1a and cathode 1b of the fuel cell 1, and this appears as a pressure fluctuation in the fuel cell 1. When the pressure of the fuel cell 1 fluctuates, the cathode pressure regulator 8 controls the cathode 1b pressure to be equal to the anode 1a pressure in order to suppress the generation of interelectrode pressure difference due to this.

[Problems in the Background Art] However, in a fuel cell power generation system equipped with such a pressure/flow rate control device, mutual interference between the oxidant gas flow rate control valve 3 and the pressure control valve 4 is very strong, and they may adversely affect each other. There is a problem in that control is not performed satisfactorily. That is, when the opening degree of the oxidant gas flow rate control valve 3 changes, this causes a change in the cathode 1b pressure, causing a disturbance to the cathode pressure control. Conversely, if the opening degree of the pressure control valve 4 changes, this will affect the cathode 1b pressure, and this will change the secondary side pressure and cause disturbance to the oxidant gas flow 11111.11111. .

From the above, it is strongly desired to improve controllability and load response by taking into account the mutual interference between oxidant gas flow control and cathode pressure control and eliminating their respective negative effects. There is.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and its purpose is to improve the load response of a fuel cell by eliminating mutual interference between oxidant gas flow control and cathode pressure control. Our goal is to provide a highly reliable fuel cell power generation system that is capable of

[Summary of the Invention] In order to achieve the above object, the present invention comprises a pair of electrodes consisting of a fuel electrode and an oxidizer electrode, which are arranged with a matrix impregnated with an electrolyte sandwiched therebetween. In a fuel cell in which an oxidant gas is supplied to each of the electrodes and electrical energy is extracted from between the two electrodes through an electrochemical reaction that occurs, a fuel cell is provided on the fuel gas and oxidant gas supply lines to the fuel cell, respectively. a fuel gas 1M control valve and an oxidant gas flow aS control valve, a pressure control valve provided on the oxidant gas discharge line from the fuel cell, and a gas flow rate passing through the oxidant gas supply line. A flow rate detector detects the pressure of the oxidant electrode, a pressure detector detects the pressure of the oxidant electrode, and a first value obtained by comparing the oxidant gas flow rate detection value signal from the flow rate detector and the oxidant gas flow rate target value signal. A first flow control valve opening command signal and a first pressure control valve opening command signal are derived based on the comparison signal of No. 1, and the oxidant extreme pressure detection value signal from the pressure detector and the oxidizer pole are derived. A second flow control valve opening command signal and a second pressure control valve opening command signal are derived based on a second comparison signal obtained by comparing the pressure target value signal, and the first flow rate is Control valve opening command signal and second flow f
A composite signal with the 1 control valve opening command signal is output as a valve opening command signal for the oxidant gas flow rate control valve.

Pressure/flow non-interference υ111 which outputs a composite signal of the first pressure regulating valve opening command signal and the second pressure regulating valve opening command signal as a valve opening command signal for the pressure regulating valve.
The present invention is characterized in that load responsiveness is improved by providing a pressure/flow rate control device composed of one means.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows in block form an example of the configuration of a fuel cell power generation system equipped with a pressure/flow rate control device according to the present invention, and the same parts as in Fig. 3 are given the same reference numerals and their explanation is omitted. However, only the different parts will be described here.

That is, in FIG. 1, the oxidizing gas flow rate regulator 7 and the cathode pressure regulator 8 in FIG. The oxidizing agent gas flow rate target value signal a, the oxidizing agent extreme pressure detected value signal f from the pressure detector 6, and the oxidizing agent extreme pressure target value signal e are inputted, respectively, and the oxidizing agent gas flow rate is adjusted based on each of these signals. The valve opening command signal i for the a-section valve 3 is
Further, a pressure/flow rate non-interference control device 9 is provided which outputs a valve opening command signal j to the pressure regulating valve 4, respectively.

FIG. 2 shows a detailed circuit configuration example of the pressure/flow non-interference control bag [9 in FIG. 1, and the same parts as in FIG.

In FIG. 2, 91 indicates an oxidizing gas flow rate detected value signal from the flow rate detector 5, and an oxidizing gas flow rate target value signal a.
Based on the first deviation signal C obtained by comparing the
The first flow rate WA for deriving the flow rate control valve opening command signal k of
Similarly, the moderator 92 outputs the first deviation signal @C obtained by comparing the detected oxidant gas flow rate signal from the flow rate detector 5 with the target oxidant gas flow rate signal a. This is the first pressure regulator that derives the pressure regulating valve opening command signal 1. Further, reference numeral 93 indicates a second flow rate adjustment based on a second deviation signal q obtained by comparing the oxidant extreme pressure detected value signal f from the pressure detector 6 and the oxidant extreme pressure target value signal e. a second flow fIi regulator for deriving a valve opening command signal m;
94 is a second pressure regulating valve based on a second deviation signal Q obtained by comparing the oxidizer extreme pressure detected value signal f from the pressure detector 6 and the oxidizer extreme pressure target value signal e. This is a second pressure regulator that derives the opening command signal @n.

Then, the addition signal of the first flow rate control valve opening command signal and the second flow I control valve opening command signal m is output as the valve opening command signal @i for the oxidant gas flow rate control valve 3. At the same time, the first pressure regulating valve opening command signal 1 and the second
The sum signal of the pressure regulating valve opening command signal n and the pressure regulating valve opening command signal n is outputted as the valve opening command signal j for the pressure regulating valve 4.

Next, the operation of the fuel cell power generation system equipped with the pressure/flow control fIl device configured as described above will be described.

First, by supplying a fuel gas such as hydrogen to the anode 1a and an oxidizing gas such as air to the cathode 1b according to the load amount of the fuel cell 1, they are caused to react electrochemically, and both electrodes 1a .

Electrical energy is extracted from between 1b and power generation is performed. Further, the a-oxidizing agent gas flow rate detection value signal (a) and the oxidizing agent gas flow rate target value signal (a) from the flow rate detector 5 are provided.

Oxidizer extreme pressure detection value signal f from the pressure detector 6.

The oxidant extreme pressure target value signal e is inputted to the pressure/flow rate non-interference control device 9, respectively.

Now, from this state, due to a change in the load amount of the fuel cell 1, for example, the oxidant gas flow rate tF! When the value signal a changes and thereby the first deviation signal @C is generated and the opening degree of the oxidizing gas flow rate control valve 3 changes, this changes to the cathode 1b.
the first pressure regulator 9 so as to cancel the effect on the pressure;
2 operates the pressure regulating valve 4 according to the pressure regulating valve opening command signal 1.

Further, for example, when the second deviation signal Ω is generated due to a change in the cathode 1b pressure and the opening degree of the pressure regulating valve 4 is changed thereby, a second deviation signal Ω is generated so as to cancel the influence of this on the oxidant gas flow rate. The flow rate regulator 93 of No. 2 operates the oxidizing gas flow rate regulating valve 3 based on the flow rate regulating valve opening command signal m.

That is, this configuration acts so as to cancel out the effects of the oxidizing gas flow rate control on the cathode pressure and the effects of the cathode pressure control on the oxidizing gas flow rate. the result,
This eliminates the mutual interference between the oxidizing gas flow rate control and the cathode pressure control, thereby eliminating the negative effect of a change in either one of the cylinder control operations causing disturbance to the other control.
Each controllability is improved and it becomes possible to perform better υIWJ.

As described above, in this embodiment, a pair of electrodes consisting of the anodes 1a and 1b and the cathode 1b are arranged with an electrolyte-impregnated matrix in between, and the anode 1a is supplied with fuel gas and the cathode 1b is supplied with oxidizing gas. In the fuel cell 1, in which electrical energy is extracted from between the electrodes 1a and 1b through an electrochemical reaction that occurs at the time of supply, electrical energy is provided on the fuel gas and oxidant gas supply lines to the fuel cell 1, respectively. Fuel gas flow control valve 2
and an oxidant gas flow rate control valve 3, and a pressure control valve 4 provided on the oxidant gas discharge line from the fuel cell 1.
, a flow rate detector 5 that detects the gas flow rate passing through the oxidizing gas supply line, a pressure detector 6 that detects the pressure of the cathode 1b, and a detected oxidizing gas flow rate value from the flow rate detector 5. Based on the first deviation signal C obtained by comparing the signal A and the oxidant gas flow rate target value signal a, the first
A first flow rate regulator 91, a first pressure regulator 92, which derives a flow rate regulating valve opening command signal and a first pressure regulating valve opening command signal 1. Based on the second g difference signal Q obtained by comparing the oxidant extreme pressure detection value signal f from the pressure detector 6 and the cathode pressure target value signal e, a second flow rate control valve opening command signal is generated. m and a second flow rate regulator 93 that derives the second pressure regulating valve opening command signal n. A second pressure regulator 94 is provided, and the addition signal of the first flow rate control valve opening command signal and the second flow control valve opening command signal 1 is used to adjust the oxidizing gas flow rate. In addition to outputting the valve opening command signal i to the valve 3, a sum signal of the first pressure regulating valve opening command signal m and the second pressure regulating valve opening command signal n is output as the valve opening command signal i to the pressure regulating valve 4. A fuel cell power generation system is constructed by including a pressure/flow control device including a pressure/flow non-interference control device 9 that outputs an opening command signal j.

Therefore, it is possible to improve the followability of the oxidizing gas flow rate control of the fuel cell 1 and the stability of the cathode pressure control with respect to various operating conditions of the fuel cell power generation system including load changes. In particular, in the fuel cell 1, it is essential to suppress the differential pressure between electrodes well, so improving the stability of cathode pressure control described above has a large effect on improving the load response of the entire system. It is something.

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, extremely reliable fuel cell power generation can be achieved in which mutual interference between oxidant gas flow rate control and cathode pressure control can be eliminated to improve the load response of the fuel cell. system can provide.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG.
The figure is a block diagram showing details of the pressure/flow rate non-interference control device in the same embodiment, and FIG. 3 is a block diagram showing the structure of a conventional fuel cell power generation system. DESCRIPTION OF SYMBOLS 1... Fuel cell, 1a... Anode, 1b... Cathode, 2... Fuel gas flow rate control valve, 3... Oxidizing gas flow rate control valve, 4... Pressure control valve, 5... ...Flow rate detector, 6...Pressure detector, 7...Oxidant gas flow rate regulator, 8...Cathode pressure regulator, 9...Pressure/flow rate non-interference control device, 91... first flow regulator, 92
... first pressure regulator, 93... second flow regulator, 94... second pressure regulator, a... oxidizing gas flow rate target value signal, b... oxidizing agent Gas flow rate detection value signal, C
...First deviation signal, e... Oxidizer extreme pressure target value signal, f... Oxidizer extreme pressure detected value signal, Q... Second deviation signal, i... Valve opening degree Command signal, j...Valve opening command signal, k...Flow control valve opening command signal, 1...Pressure control valve opening command signal, m...Flow II node valve opening command signal, n...Pressure control valve opening command signal. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] A pair of electrodes, a fuel electrode and an oxidizer electrode, are arranged with an electrolyte-impregnated matrix sandwiched between them, and fuel gas is supplied to the fuel electrode and oxidant gas is supplied to the oxidizer electrode, respectively, and the electrochemical reaction that occurs at this time is performed. In a fuel cell configured to extract electrical energy from between both electrodes, a fuel gas flow rate control valve and an oxidant gas flow rate control valve are provided on the fuel gas and oxidant gas supply lines to the fuel cell, respectively; a pressure control valve provided on an oxidant gas discharge line from the fuel cell; a flow rate detector that detects a gas flow rate passing through the oxidant gas supply line; and a pressure that detects the pressure of the oxidant electrode. A detector generates a first flow rate control valve opening command signal based on a first comparison signal obtained by comparing the detected oxidizing gas flow rate signal from the flow rate detector and the target oxidizing gas flow rate signal. and a first pressure regulating valve opening command signal, and a second comparison signal obtained by comparing the oxidizer extreme pressure detected value signal from the pressure detector and the oxidizer extreme pressure target value signal. derive a second flow control valve opening command signal and a second pressure control valve opening command signal based on the first flow control valve opening command signal and the second flow control valve opening command signal; output a composite signal of the first pressure regulating valve opening command signal and the second pressure regulating valve opening command signal as a valve opening command signal for the oxidizing gas flow rate regulating valve. A fuel cell power generation system comprising a pressure/flow rate control device comprising a pressure/flow rate non-interference control means that outputs a valve opening command signal to the pressure regulating valve.