JPS59123167A - Fuel cell system - Google Patents

Abstract

PURPOSE:To provide a fuel cell system having highly increased safety without decreasing performance by installing a discharge valve in a fuel gas exhaust part and oxidizing gas exhaust part respectively, and opening each discharge valve according to differential pressure of a fuel gas and oxidizing gas. CONSTITUTION:In a fuel cell system, control valves 24 and 25 are installed in a fuel gas supply pipe 11F and an oxidizing gas supply pipe 11A respectively and flow rate of fuel gas F and oxidizing gas A is controlled depending on the output of a cell main body 11. Differential pressure of fuel gas F and oxidizing gas A in the main body 11 is detected with a differential pressure gage 26 and inputted to a controller 27. A fuel gas discharge valve 28 is installed between a fuel gas exhaust part 11f2 and burning equipment 12, and an oxidizing gas discharge valve 29 is connected between an oxidizing gas exhaust part 11a2 and mixing equipment 13. The controller 27 opens discharge valves 28 and 29 according to a signal from the differential pressure gage 26 to discharge fuel gas and oxidizing gas which finished reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel cell device that controls the differential pressure between fuel gas and oxidizing gas within a fuel cell main body.

[Technical background of the invention]

A fuel cell device directly converts the chemical energy of fuel into electrical energy, and has a pair of porous electrodes sandwiching an electrolyte, and a fuel gas such as hydrogen or the like is placed on the back of one electrode. A chemical reaction is caused by bringing an oxidizing gas containing oxygen into contact with the back surface of the other electrode, and the electrical energy generated at this time is extracted from the pair of porous electrodes.

Examples of the electrolyte include molten salt, alkaline solution, and acidic solution, but here, a fuel cell device using phosphoric acid as the electrolyte will be described.

In FIG. 1, 1 is an electrolyte layer made of a fibrous sheet or mineral powder impregnated with phosphoric acid.

Further, in the figure, 2 is an anode, and 3 is a cathode.

Both the anode 2 and the cathode 3 are carbonaceous porous electrodes, and the surfaces in contact with the electrolyte layer 1 are usually coated with platinum as a catalyst. In the figure, 4 is a fuel gas inflow chamber into which fuel gas F containing hydrogen is introduced, and 5 is an oxidizing gas containing oxygen (
This is an oxidizing gas inflow chamber into which A (usually air) flows.

Therefore, hydrogen in the fuel gas F that has flowed into the fuel gas inlet chamber 4 comes into contact with the catalyst through the pores of the anode 2, which is a porous electrode. Here, hydrogen is dissociated into hydrogen ions and electrons by the action of a catalyst. The reaction formula at this time is H2→ 2H++2e ·−·−<1). The hydrogen ions then enter the electrolyte layer 1 and migrate toward the cathode 3 due to the action of electromotive force and concentration diffusion. Further, electrons separated by dissociation of hydrogen ions perform work through an external power load 6 and flow into the cathode 3. On the other hand, oxygen in the oxidizing gas A that has flowed into the oxidizing gas inflow chamber 5 contacts the catalyst through the pores of the cathode 3, which is a porous electrode, and passes through the hydrogen ions migrating from the anode 2 side and the external power load 6. 9 Together with the electrons returned to cathode 3, the next reaction occurs due to the action of the catalyst.

4H++4e+02→2H20 (2) Thus, hydrogen is oxidized and converted into water, and at the same time, chemical energy is converted into electrical energy and provided to the external power load 6.

At this time, part of the electrical energy is consumed in the electrolyte layer 1 by the external resistance of the battery. Therefore, in order to increase battery efficiency, it is necessary to shorten the migration distance of hydrogen ions 5- to reduce resistance.
Therefore, the electrolyte layer 1 is formed extremely thin.

Further, the fuel gas F and the oxidizing gas A flowing into the inlet chambers 4 and 5 are normally pressurized to several atmospheres in order to increase their concentration and reaction rate.

By the way, as mentioned above, the electrolyte layer 1 is formed extremely thin, so if the pressure difference between the fuel gas F on the anode 2 side and the oxidant gas A on the cathode 3 side is large, the fuel gas F-i or the oxidant gas A There is a risk that the bubbles will break through the electrolyte layer 1 against the surface tension of the phosphoric acid impregnated into the electrolyte layer 1, causing local combustion. Furthermore, there is a risk that the device may deteriorate or its performance may deteriorate. Therefore, the pressure difference mentioned above must be kept extremely small, for example, within 400 mmH2O (generally, the pressure of oxidant gas A is higher than the pressure of fuel gas F. For this reason, the pressure difference between fuel gas F and oxidant gas A must be controlled. That is, as shown in FIG. The reacted fuel gas F is sent from the fuel gas discharge section 11f2 to the combustor 12 through the fuel gas discharge pipe 11F', burns the remaining fuel components, and enters the mixer 13.On the other hand, the fuel gas F reacted in The oxidizing gas A flows from the oxidizing gas supply section 11 al to the oxidizing gas reaction section 11h in the fuel cell main body 11, and reacts within this main body 11. The oxidizing gas A is directly transferred to the mixer 13 from the oxidizing gas discharging section 11a through the oxidizing gas discharging pipe 11A'. Thus, the pressure of the residual fuel gas F and the pressure of the oxidant gas A match in the mixer 13. In the figure, 14.15 indicates the pressure of the fuel gas F and the oxidant gas A in the fuel cell main body 11.
16 in the figure is the flow path resistance to the fuel gas F in the combustor 12. Also, 17 in the figure
．． 18 is each discharge pipe 11F'.

118' with adjustable flow path resistances inserted respectively;
For example, it consists of a manual orifice, etc.

The flow path resistance 14.15 inside the fuel cell main body 11 is small, so it does not pose much of a problem when performing differential pressure control, but the flow path resistance 16 inside the combustor 12 is large, so the flow path resistance 17.1
8, the differential pressure between the fuel gas F and the oxidizing gas A within the fuel cell main body 1 is kept within a specified value.

Reference numerals 19 and 20 in the figure denote a fuel gas release valve and an oxidant gas release valve connected to the fuel gas supply pipe 11F and the oxidant gas supply pipe 11k, respectively, which have the following functions. That is, in the fuel cell device shown in FIG. 2, the flow path resistance 16 in the combustor 13 is large, and therefore the pressure drop at the rated flow rate is several thousand hours H20 (for example, 3000 degrees H20).
reach even. Therefore, as shown in Fig. 3, by controlling the fuel gas F side and the oxidant gas A side in proportion to the output, the differential pressure ΔP is set to a specified value (for example, 400 mm H2O
), but it is difficult to control the flow rate with high precision, and the relationship between the flow rate and pressure drop, especially on the fuel gas side, as it passes through the combustor 13, deviates from the square-law characteristic approximation. Put it away. Therefore, only by controlling the flow rate of the fuel gas F4 or the oxidizing gas A, it is not possible to respond particularly to transient characteristics. Therefore, when the differential pressure ΔP increases rapidly, the increase in the differential pressure ΔP is suppressed by operating the fuel gas release valve 19 or the oxidizing gas releasing valve 20 to release the fuel gas F or the oxidizing gas A.

[Problems with background technology]

In conventional fuel cell devices, when the differential pressure between the pressure of the fuel gas F and the pressure of the oxidizing gas inside the fuel cell main body 11 suddenly increases, the oxidizing gas release valve provided on the gas supply side of the fuel cell main body 11 20 or the fuel gas release valve 19 to suddenly release unreacted gas on the high pressure side to the atmosphere, which is not safe and may also degrade the characteristics of the fuel cell main body 11.

[Purpose of the invention]

The present invention (first invention, second invention) was made based on such circumstances, and its purpose is to obtain a high degree of safety and also to reduce the 9- characteristics of the fuel cell main body. The objective is to provide a fuel cell device that does not require a fuel cell device.

[Summary of the invention]

First, the first invention is to connect a fuel gas discharge valve and an oxidant gas discharge valve to a fuel gas discharge pipe and an oxidant gas discharge pipe on the outlet side of the fuel cell main body, respectively, so that the differential pressure between the fuel gas and the oxidant gas reaches a dangerous value. The system is configured to open the gas release valve on the high pressure side when the pressure reaches 1, thereby suppressing the rise in differential pressure.

Further, a second invention provides a fuel gas release valve and an oxidizing gas release valve similar to those of the first invention, and also includes housing the fuel cell main body in a sealed container and filling the sealed container with an inert gas. The pressure of the fuel gas and oxidizing gas are compared with the above reference pressure using the inert gas pressure in the sealed container as the reference pressure, and when either pressure difference reaches a dangerous value, the gas release valve on the relevant side is opened. It is configured to open the valve to suppress the rise in differential pressure.

[Embodiments of the invention]

FIG. 4 shows an embodiment according to the first invention.
The fuel gas flows from the oxidizing gas supply section 11a1 through the oxidizing gas supply pipe J7A, the flow path of the fuel gas F which flows into the fuel gas F from the fuel gas discharging section 11f2, passes through the fuel gas discharging pipe 11F', passes through the combustor 12, and reaches the mixer 13. The flow path of the oxidant gas A that flows into the oxidant gas reaction section 11h in the battery main body 11 and directly reaches the mixer 13 from the oxidant gas discharge section 11J via the oxidant gas discharge pipe 11A', as well as the flow inside the fuel cell main body 11. road resistance 1
4.16, the flow resistance 16 in the combustor 12 and the adjustable flow resistance 17.18 provided in each exhaust pipe 11 F', 11 A' are similar to the conventional device of FIG.

Therefore, the residual gas of several tens of grams of the fuel gas F used for power generation inside the fuel cell main body 11 reaches the mixer 13 via the flow path resistance 17 and the combustor 12.

Further, the oxidized gas A flowing out from the fuel cell main body 11 passes through the flow path resistance 18 and reaches the mixer 13 as it is.

A mixed gas of residual fuel gas F and oxidizing gas A flowing out from the mixer 13 is sent to the turbine 22 and drives the turbine 22. Further, the turbine 22 is the compressor 2
3, thereby consuming the remaining thermal and pressure energy. The compressor 23 takes in atmospheric air, compresses it, and sends it to the fuel cell main body 11.

A control valve 24 is inserted into the fuel gas supply pipe 11F, and a control valve 25 is inserted into the oxidizing gas supply pipe 11A.

These control valves 24 and 25 are for controlling the inflow amount of the fuel gas F and the oxidizing gas A according to the electrical output in the fuel cell main body 11.

On the other hand, the differential pressure ΔP between the fuel gas F and the oxidizing gas A in the fuel cell main body 11 is detected by a differential pressure gauge 26 connected between the fuel gas supply pipe 11F and the oxidizing gas supply pipe 11. The signal is input to controller 27. Further, a fuel gas discharge valve 28 is provided between the fuel gas discharge section 11fl of the fuel gas discharge pipe 11F' and the combustor 12, and a monoxide gas discharge section 11a of the oxidation gas discharge pipe 11A'.

Oxidizing gas release valves 29 are connected between the mixer 13 and the mixer 13, respectively.

The controller 27 monitors the differential pressure ΔP between the fuel gas F and the oxidizing gas A based on the signal from the differential pressure gauge 26, and when the differential pressure ΔP rises to a certain dangerous value, gas is released from the high pressure gas side. Open the valve 28 or 29 and open the gas exhaust pipe 11F.
' or 111, the reacted fuel gas or oxidizing gas after passing through the fuel cell main body 11 is discharged.

With the above configuration, when the differential pressure ΔP between the fuel gas F and the oxidizing gas A reaches a dangerous value, the gas on the high pressure side of the fuel gas F1 and the oxidizing gas A is released, causing an increase in the differential pressure ΔP. can be suppressed. Further, the gas released at this time is the reacted gas that has passed through the fuel cell main body 11, and unreacted gas is not released as in the conventional device, so safety is improved. Also, since the gas is released after passing through the fuel cell main body 11 = 13-, the fuel cell main body 1
It does not affect the characteristics of No. 1, and there is no risk of deterioration of the characteristics.

Note that the differential pressure gauge 26 in the above embodiment may be connected between the fuel gas exhaust pipe 11F' and the oxidizing gas exhaust pipe 11A'.

Next, FIG. 5 shows an embodiment according to the second invention. In this embodiment, the fuel cell main body 11 is housed in a sealed container 30, and the sealed container 30 is filled with an inert gas N such as nitrogen, and this pressure is maintained constant. Further, an inert gas supply pipe 3ON and an inert gas discharge pipe 3ON' are connected to the airtight container 30, and the exhaust pipe 3ON' is provided with an adjustable flow path resistance 3N consisting of a manual orifice or the like. . On the other hand, inert gas supply pipe 3
A control valve 32 for controlling the inflow amount of inert gas N is inserted into the ON state.

A fuel gas side differential pressure gauge 26F is connected between the fuel gas supply pipe 11F and the inert gas supply pipe 3ON, and an inert gas supply pipe 9ON is connected to the oxidizing gas supply pipe 11.
An oxidizing gas side differential pressure gauge 26k is inserted between the two. Similarly to the embodiment shown in FIG.
An oxidizing gas discharge valve 29 is connected between the oxidizing gas discharge portion 11a2 and the mixer 13, respectively.

34 in the figure is a controller, and this controller 33 controls the fuel gas F based on the detection signals from the differential pressure gauges 26F and 26k.
The differential pressure ΔPl between the oxidizing gas A and the inert gas N and the differential pressure ΔP2 between the oxidizing gas A and the inert gas N are monitored. When any of the differential pressures reaches a certain dangerous value, the corresponding gas release valve 28 or 29 is opened and the fuel gas exhaust pipe 1 is opened.
1F' or the oxidizing gas discharge pipe 11A', the fuel gas F
Alternatively, oxidizing gas A is released.

Therefore, according to this embodiment, first, the fuel cell main body 1
1 is housed in an airtight container 30 filled with inert gas N, so safety is enhanced. Also, since the gas pressures of fuel gas F and oxidizing gas A are monitored based on the gas pressure of inert gas N, which is maintained at a constant pressure, it is of course possible to Even when both the fuel gas F and the oxidizing gas A become high and the differential pressure between them does not become very high, both gases F and A are released, and an abnormal increase in gas pressure is suppressed. Also in this embodiment, the gas is released after the reaction within the fuel cell main body 11, so safety is enhanced, and the fuel cell main body 11
The characteristics in No. 1 do not deteriorate either.

Note that the inert gas N may be other than nitrogen.

〔Effect of the invention〕

As described above, according to the present invention (first and second inventions),
It is possible to provide a fuel cell device that provides a high degree of safety and does not cause deterioration in the characteristics of the fuel cell main body.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of a fuel cell device, Fig. 2 is a system diagram showing a conventional example of a fuel cell device, Fig. 3 is a graph showing the relationship between flow rate and pressure drop for the fuel gas side and the oxidizing gas side. FIG. 4 is a system diagram showing an embodiment of the first invention, and FIG. 5 is a system diagram showing an embodiment of the second invention. 11...Fuel cell body, 11! ... Fuel gas reaction section, 1111... Fuel gas supply section, 11f1... Fuel gas discharge section, 11a... Oxidizing gas reaction section, 11*1.
... Oxidizing gas supply section, 111L heavy... Oxidizing gas discharge section, 12... Combustor, 13... Mixer, 26.26'
F'. 26k...Differential pressure gauge, 27.33...Controller, 28.
... Fuel gas release valve, 29... Oxidizing gas release valve, 30
... airtight container, F... fuel gas, A... oxidizing gas, N... inert gas. Applicant's agent Patent attorney Takehiko Suzue 17- Figure 1

Claims (3)

[Claims] (1) A fuel cell body including a fuel gas reaction section having a fuel gas supply section and a fuel gas discharge section, and an oxidation gas reaction section having an oxidation gas supply section and an oxidation gas discharge section, and connected to the fuel gas discharge section. a combustor, and a mixer connected to the outlet side of the combustor and the oxidizing gas discharge section and mixing the residual fuel gas discharged from the combustor with the oxidizing gas discharged from the oxidizing gas discharge section. , a fuel gas release valve connected to the fuel gas discharge section, an oxidation gas release valve connected to the oxidation gas discharge section, and a gap between the fuel gas supply section and the oxidation gas supply section or between the fuel gas supply section and the oxidation gas supply section. A differential pressure gauge is connected between the exhaust part and the oxidizing gas discharge part to detect the differential pressure between the fuel gas and the oxidizing gas, and the differential pressure is monitored based on the detection signal of the differential pressure gauge to detect if the differential pressure is dangerous. 1. A fuel cell device comprising: a controller that opens a gas release valve connected to a high-pressure gas side when a certain value is reached. (2) A fuel cell main body including a fuel gas reaction section having a fuel gas supply section and a fuel gas discharge section and an oxidation gas reaction section having an oxidation gas supply section and an oxidation gas discharge section, and a fuel cell main body that is connected to the fuel gas discharge section. a combustor, a mixer connected to the outlet side of the combustor and the oxidizing gas discharge section and mixing the residual fuel gas discharged from the combustor with the oxidizing gas discharged from the oxidizing gas discharge section; a closed container that houses the fuel cell main body and is filled with an inert gas; a fuel gas discharge valve connected to the fuel gas discharge pipe;
An oxidizing gas release valve connected to the oxidizing gas discharge section, and connected between the fuel gas supply section or the fuel gas discharging section and the sealed container to control the pressure difference between the fuel gas and the inert gas in the sealed container. and an oxidizing gas side differential pressure gauge connected between the oxidizing gas supply section or the oxidizing gas discharge section and the sealed container to detect the differential pressure between the oxidizing gas and the inert gas in the sealed container. The differential pressures are monitored based on the side differential pressure gauges and the detection signals from these differential pressure gauges, and when the differential pressure between the fuel gas and the inert gas in the sealed container reaches a dangerous value, the fuel gas release valve is opened. 1. A fuel cell device comprising: a controller that opens an oxidizing gas release valve when the differential pressure between the oxidizing gas and the inert gas in the closed container reaches a dangerous value. (3) The fuel cell device according to claim (2), wherein the inert gas is nitrogen.