JPH04133270A - Fuel cell - Google Patents

Abstract

PURPOSE:To continually keep pressure inside a gas passage constant by providing an anode gas exhaust pipe with an equalizing valve to open and close corresponding to the pressure inside a cathode gas passage and also providing a cathode gas exhaust pipe with a equalizing valve to open and close corresponding to the pressure inside an anode gas passage. CONSTITUTION:Since the inside of a bellows 35 of an equalizing valve 37 is being kept at the same pressure as the upper stream side than an equalizing valve 31 of an anode gas exhaust pipe 18 with which the bellows 35 communicates through a pilot pipe 36, when the pressure of a cathode gas passage is lower than that of the exhaust pipe 18, the bellows 35 extends due to the pressure difference and a valve body 33 approaches a valve seat 32 to throttle the equalizing valve 37. Thereby the pressure of the cathode gas passage rises and becomes equal to the pressure of the exhaust pipe 18. When the pressure of the cathode gas passage is higher than that of the exhaust pipe 18 to the contrary, the bellows 35 contracts due to the pressure difference and the valve body 33 separates from the valve seat 32 to open the equalizing valve 37. Thereby the pressure of the cathode gas passage falls and becomes equal to the pressure of the exhaust pipe 18.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to fuel cells.

[Conventional technology] Hereinafter, a conventional fuel cell will be explained using FIG. 3.

In the figure, reference numeral 1 denotes a fuel cell main body, which is composed of a stack 2 and a stack container 3 that encloses the stack 2 in nitrogen gas at a constant pressure.

The stack 2 has two sides of an electrolyte 4 (third
Anode 5 (negative electrode) made of porous material (upper and lower surfaces in the figure)
and the cathode 6 (positive electrode), and the anti-type solute 4 of the anode 5
An anode gas passage 7 is formed on the side, and a cathode gas passage 8 is formed on the side of the anti-mold solute 4 of the cathode 6.

9 is an anode gas supply pipe that supplies an anode gas 10 (fuel gas) containing hydrogen and carbon monoxide such as coal gas, natural gas, or methanol to the anode gas passage 7; 11 is provided in the middle of the anode gas supply pipe 9; The flow rate control valve 12 is a flow rate controller that detects the flow rate of the anode gas supply pipe 9 and adjusts the flow rate control valve 11.

13 is a cathode gas supply pipe that supplies cathode gas 14 (oxidant gas obtained by adding carbon dioxide to gas such as air containing oxygen) to cathode gas passage 8; 15 is a flow rate provided in the middle of cathode gas supply pipe 13; A control valve 16 is a flow rate controller that detects the flow rate of the cathode gas supply pipe I3 and adjusts the flow control valve 15, and 17 is provided between the flow control valve 15 of the cathode gas supply pipe 13 and the cathode gas passage 8. It is a catalytic combustor.

18 guides the anode gas 10 discharged from the anode gas passage 7 to the catalytic combustor 17 (anode gas exhaust pipe, 19
20 is a pressure control valve provided in the middle of the anode gas exhaust pipe 18; 20 detects the pressure inside the stack container 3 and the pressure in the anode gas exhaust pipe 18; This is a pressure regulator that measures the pressure difference between the two pressures and adjusts the pressure regulating valve 19 so that the differential pressure becomes zero.

21 is a cathode gas exhaust pipe for discharging the cathode gas 14 from the cathode gas passage 8; 22 is a cathode gas exhaust pipe 2;
A pressure regulating valve 23 provided in the middle of the stack container 3 detects the pressure inside the stack container 3 and the pressure in the cathode gas exhaust pipe 21, and also detects the difference between the pressure inside the stack container 3 and the pressure in the cathode gas exhaust pipe 2. A pressure regulator 24 takes the pressure and adjusts the pressure regulating valve 22 so that the differential pressure becomes zero, and 24 is connected to the outlet side of the pressure regulating valve 22 of the cathode gas exhaust pipe 21 and the catalytic combustor 1.
A cathode gas recycle pipe 25 is connected to the cathode gas recycle pipe 7, and a cathode gas recycle blower 25 is provided in the middle of the cathode gas recycle pipe 24.

When generating electricity, the anode gas 10 (fuel gas containing hydrogen and carbon monoxide) is supplied to the anode gas supply pipe 9 while adjusting the flow rate with the flow control valve 11, and at the same time, the flow rate is adjusted to the cathode gas supply pipe 13. A gas such as air containing oxygen is supplied as the cathode gas 14 (as described later, carbon dioxide is added to the catalytic combustor 17 to form an oxidizing gas) while adjusting the flow rate using the regulating valve 15 .

Then, the cathode gas 14 enters the cathode gas passage 8 of the stack 2 via the catalytic combustor 17, where carbon dioxide and oxygen in the cathode gas 14 react by receiving electrons from the cathode 6 (positive electrode). carbonate ions are generated. Unreacted cathode gas 14 is discharged from the cathode gas passage 8 to the outside through the cathode gas exhaust pipe 21, and a portion of it is sent to the catalytic combustor 17 through the cathode gas recycle pipe 24 by the cathode gas recycle blower 25. .

Then, the carbonate ions generated on the cathode 6 side move the electrolyte 4 to the anode 5 (negative electrode) side, and at the anode 5, hydrogen and hydrogen in the anode gas supply pipe passed from the anode gas supply pipe 9 to the anode gas passage 7 are transferred. Reacts with carbon oxide to produce water, carbon dioxide, and electrons. In this way, electricity is generated, and water and carbon dioxide generated at the same time are sent from the anode gas passage 7 to the catalytic combustor 17 through the anode gas exhaust pipe 18.

In the catalytic combustor 17, unreacted hydrogen contained in the anode gas 1o after the reaction from the anode gas exhaust pipe 18 and unreacted oxygen contained in the cathode gas 14 after the reaction from the cathode gas recycle pipe 24 are catalyzed. The carbon dioxide contained in the anode gas 10 is supplied to the cathode gas 14.

The pressure in the anode gas passage 7 is controlled by a pressure regulator 20.
is the pressure inside the stack container 3 and the anode gas exhaust pipe 18.
Detect the pressure inside the stack container 3, take the pressure difference between the pressure inside the stack container 3 and the pressure in the anode gas exhaust pipe 18, and adjust the pressure regulating valve 19 so that the pressure difference becomes zero, so that the pressure is equal to the pressure inside the stack container 3. The pressure in the cathode gas passage 8 is determined by the pressure regulator 23 detecting the pressure inside the stack container 3 and the pressure in the cathode gas exhaust pipe 21. The pressure difference between the stack container 3 and the stack container 3 is maintained at the same pressure as the inside of the stack container 3 by adjusting the pressure regulating valve 22 so that the pressure difference becomes zero. As a result, the anode gas passage 7 and the cathode gas passage 8 are kept at the same pressure, and the anode gas passage 7
The pressure difference between the anode 5, the cathode 6 and the electrolyte 4, which are made of extremely thin layers, is prevented from breaking due to the pressure difference between the anode 5 and the cathode gas passage 8.

[Problems to be Solved by the Invention] However, the conventional fuel cell described above has the following problems.

That is, in order to prevent the anode 5, cathode 6, and electrolyte 4 from being ruptured due to a pressure difference between the anode gas passage 7 and the cathode gas passage 8, an expensive gas exhaust pipe 18 and cathode gas exhaust pipe 21 are installed. Since pressure regulating valves 19.22 and pressure regulators 20.23 were used, the cost of the entire equipment increased.

In view of the above-mentioned circumstances, the present invention has been developed to maintain the same pressure on the anode and cathode sides without using expensive pressure control valves or pressure regulators. It is an object of the present invention to provide a fuel cell that can be prevented from being ruptured due to differential pressure.

[Means for Solving the Problems] The present invention sandwiches an electrolyte between an anode and a cathode, provides an anode gas passage capable of supplying an anode gas consisting of fuel on the anode side, and supplies a cathode gas consisting of an oxidizing agent on the cathode side. In a fuel cell equipped with a possible cathode gas passage, the anode gas exhaust pipe connected to the outlet side of the anode gas passage is provided with a pressure equalizing valve that opens and closes depending on the pressure inside the cathode gas passage; The present invention relates to a fuel cell characterized in that a pressure equalizing valve that opens and closes depending on the pressure inside the anode gas passage is provided in the cathode gas exhaust pipe.

[Function] According to the present invention, the pressure equalizing valve provided in the anode gas exhaust pipe opens and closes depending on the pressure inside the cathode gas passage, and the pressure equalizing valve provided in the cathode gas exhaust pipe opens and closes depending on the pressure inside the anode gas passage. The pressure inside the anode gas passage and the pressure inside the cathode gas passage are always maintained at the same pressure.

[Implementation example] Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention.

In addition, the basic structure of the fuel cell and the details of each component in the figure include those similar to those shown in FIG. 3, so the same components are denoted by the same reference numerals. Therefore, the explanation will be omitted, and only the configuration specific to the present invention will be explained below.

A valve seat 26 is provided in the middle of the anode gas exhaust pipe 18, and the anode gas 1
A valve body 27 that can open and close the valve seat 26 is disposed on the zero outlet side, and the valve body 27 is supported on the anode gas exhaust pipe 18 using a hollow bellows 29 that is movable in the valve seat opening and closing direction 28. The interior of the bellows 29 and the cathode gas 7 exhaust pipe 21 are communicated via a pilot pipe 30 to form a self-balancing pressure equalizing valve 31.

A valve seat 32 is provided on the downstream side of the cathode gas 14 flow direction from the pilot pipe 30 connection position of the cathode gas exhaust pipe 21, and the valve seat 32 is opened and closed on the cathode gas 14 outlet side with respect to the valve seat 32 of the anode gas exhaust pipe 18. The valve body 33 is supported on the cathode gas exhaust pipe 21 using a hollow bellows 35 movable in the valve seat opening/closing direction 34, and the interior of the bellows 35 and the anode gas exhaust pipe 18 are The pressure equalizing valve 31 is connected to the upstream side of the anode gas 10 in the flow direction through a pilot pipe 36, and a self-balancing type pressure equalizing valve 3 is formed.
7.

Next, the effect will be explained.

The process by which electricity is generated in the fuel cell main body 1 is the same as that shown in FIG. 3, so a description thereof will be omitted.

In the anode gas exhaust pipe 18, the pressure equalizing valve 37 is opened and closed in the following manner, and the pressure in the anode gas passage 7 is adjusted.

That is, in the pressure equalizing valve 31, the inside of the bellows 29 is maintained at the same pressure as the pressure on the upstream side of the pressure equalizing valve 37 of the cathode gas exhaust pipe 21 communicated via the pilot pipe 30, so that the pressure in the anode gas passage 7 is Cathode gas exhaust pipe 21
When the pressure is lower than , the bellows 29 expands due to the pressure difference, and the valve element 27 supported by the bellows 29 approaches the valve seat 26, thereby throttling the pressure equalizing valve 31. As a result, the pressure in the anode gas passage 7 increases and becomes equal to the pressure in the cathode gas exhaust pipe 21.

On the other hand, when the pressure in the anode gas passage 7 is higher than the pressure in the cathode gas exhaust pipe z1, the bellows 29 contracts due to the pressure difference, and the valve body 27 supported by the bellows 29 moves toward the valve seat 26.
The pressure equalizing valve 31 is opened.

As a result, the pressure in the anode gas passage 7 decreases and becomes equal to the pressure in the cathode gas exhaust pipe 21.

On the other hand, in the pressure equalizing valve 37, the inside of the bellows 35 is maintained at the same pressure as the pressure on the upstream side of the pressure equalizing valve 31 of the anode gas exhaust pipe 18 communicated via the pilot pipe 36, so that the pressure in the cathode gas passage 8 is maintained. Anode gas exhaust pipe 18
When the pressure is lower than , the bellows 35 expands due to the pressure difference, and the valve element 33 supported by the bellows 35 approaches the valve seat 32, thereby throttling the pressure equalizing valve 37. As a result, the pressure in the cathode gas passage 8 increases to become equal to the pressure in the anode gas exhaust pipe 18.

On the other hand, when the pressure in the cathode gas passage 8 is higher than the pressure in the anode gas exhaust pipe 18, the bellows 35 contracts due to the pressure difference, and the valve body 33 supported by the bellows 35 moves toward the valve seat 32.
The pressure equalizing valve 37 is opened.

As a result, the pressure in the cathode gas passage 8 decreases and becomes equal to the pressure in the anode gas exhaust pipe 18.

Therefore, the pressure inside the anode gas passage 7 and the pressure inside the cathode gas passage 8 are always maintained at the same pressure.

It should be noted that the present invention is not limited only to the above-described embodiments, and it goes without saying that the structure of the pressure equalizing valve is arbitrary, and that various other changes can be made without departing from the gist of the present invention. be.

[Effects of the Invention] As explained above, according to the fuel cell of the present invention, since a pressure equalizing device using a liquid seal tube is used, the anode side and cathode side can be connected without using an expensive pressure regulating valve or pressure regulator. This has the excellent effect of making it possible to equalize the pressures of the two layers, and preventing the anode, cathode, and electrolyte, which are made of extremely thin layers, from being ruptured due to differential pressure.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram of one embodiment of the present invention, and FIG.
A partially enlarged view of the figure, and FIG. 3 is an overall system diagram of a conventional example. In the figure, 4 is an electrolyte, 5 is an anode, 6 is a cathode, 7 is an anode gas passage, 8 is a cathode gas passage, 10 is an anode gas, 14 is a cathode gas, 18 is an anode gas exhaust pipe, 21 is a cathode gas exhaust pipe, 31.37 indicates a pressure equalization valve.

Claims (1)

[Claims] 1) In a fuel cell in which an electrolyte is sandwiched between an anode and a cathode, an anode gas passage capable of supplying an anode gas consisting of fuel is provided on the anode side, and a cathode gas passage capable of supplying a cathode gas consisting of an oxidizing agent is provided on the cathode side. , a pressure equalizing valve that opens and closes depending on the pressure inside the cathode gas passage is installed in the anode gas exhaust pipe connected to the outlet side of the anode gas passage, and a pressure equalizing valve that opens and closes depending on the pressure inside the cathode gas passage A fuel cell characterized by being equipped with a pressure equalizing valve that opens and closes depending on pressure.