JPH02155172A - Gas purging equipment of fuel cell - Google Patents

Abstract

PURPOSE:To make volume small and to simplify maintenance by using liquefied inert gas as a purge gas used when operation of fuel cell is stopped. CONSTITUTION:An inert gas tank 10 into which liquefied inert gas is stored is installed. The liquefied inert gas in the tank 10 is vaporized with heat generated from a fuel cell 1 during operation, and vaporized inert gas is supplied to the fuel cell 1. Since the volume of liquefied inert gas is about 1/2 that of gaseous inert gas, the liquefied inert gas can be stored two times more in the same volume of the gas tank. Gas purging equipment having high efficiency can be installed without increase in its volume, and maintenance is also simplified.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a gas barge that replaces the gas remaining in the electrodes of a fuel cell with a non-performing gas when the operation of a fuel cell, especially a small mobile fuel cell, is stopped. Regarding equipment.

[Conventional technology]

As is well known, a fuel cell consists of a pair of fuel electrodes sandwiching an electrolyte (matrix) and an oxidizer electrode.
A cell stack is constructed by stacking a plurality of cell stacks A, and a fuel gas containing hydrogen and an oxidizing agent such as air or oxygen are supplied to the cell stack to generate electricity. - 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000ths of

At the time of shutdown (including emergency shutdown), it has conventionally been common practice to replace the entire fuel gas supply and exhaust system of the fuel IIL pond body with an inert gas, such as nitrogen gas, for safe operation. In other words, when starting up a stopped fuel cell, if hydrogen-rich fuel gas is supplied with air or oxygen remaining in the fuel system of the fuel cell, there is a risk that explosive gas will be formed and an explosion will occur. , and on the contrary, fuel 1! When stopping the pond, use fuel I! If fuel gas remains inside the pond body, the pressure of the fuel gas will decrease due to internal discharge or warm changes in the fuel pond.
There is a risk that air from outside the yarn may enter the fuel side and form explosive air, so the above-mentioned gas replacement is performed to ensure safety.

In particular, in a phosphoric acid fuel cell, in order to generate electricity effectively, the matrix must be sufficiently filled with phosphoric acid, and the fuel electrode and oxidizer electrode must be appropriately wetted with phosphoric acid. However, phosphoric acid, which is an electrolytic solution, is highly hygroscopic, and if there is a temperature change, such as when the fuel cell stops operating, it will absorb moisture from the atmosphere and its volume will increase dramatically, which is unwise.

For this reason, when the operation is stopped, dry inert gas is supplied to the fuel electrode and the oxidizer electrode as a purge gas to prevent the phosphoric acid from absorbing moisture.

[Problem to be solved by the invention]

By the way, in conventional fuel cell equipment, in order to perform the above-mentioned gas replacement, a high-pressure gas tank for storing inert gas is provided separately from the fuel and oxidizer supply system, and the fuel
Inert gas is supplied from this high-pressure gas tank to the reaction gas line of the fuel cell each time the system is stopped. However, in addition to fuel management, this method also requires time-consuming management of inert gas, such as constantly monitoring the remaining amount of gas in the high-pressure inert gas tank, securing the presence of rhinoceros, including reserves, and procuring personnel. This is troublesome, especially in mobile power supply equipment, which must be equipped with a high-pressure inert gas tank, which increases the size of the equipment.

For example, the high-pressure nitrogen gas filled in a 2° IJ container at 150"f/d is approximately 3001 in standard conditions, and it is approximately 3L for one purge. If necessary, it will be consumed in 10 shutdown operations. Particularly in small fuel cell equipment, such as mobile fuel cell equipment with a capacity of several kW to several tens of kW, the volume of the gas tank cannot be made very large, so only a small gas tank can be installed, and therefore the gas tank must be replaced frequently, causing many problems. .

The present invention has been made in view of the above, and an object of the present invention is to provide a fuel cell gas barge device that can simplify maintenance without increasing the size of the equipment.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, a raw material gas is reformed into a hydrogen-rich gas by a reformer and supplied to a fuel electrode as a fuel gas, and air is supplied as an oxidant to an oxidizer electrode. When a fuel cell that generates electricity through an electrochemical reaction between these two gases is stopped, the supply of the fuel gas and air to the fuel cell is stopped, and the gas remaining in the electrode is replaced with an inert gas. 71. In the gas purge device of M, an inert gas tank is provided to store liquefied inert gas, and the liquefied inert gas stored in this tank is vaporized by heat generated from fuel IIEO during operation and supplied to the fuel cell. shall be taken as a thing.

[Effect]

Compared to conventional gaseous inert gas, liquefied inert gas can be filled into a gas tank with the same volume as much i (approximately twice the volume converted to large fi). If the heat generated during operation of the EJr battery is used to vaporize it and supply it as purge gas, an efficient gas barge device can be obtained without increasing the size of the equipment.

〔Example〕

The present invention will be explained below based on examples. FIG. 1 is a system diagram showing an embodiment of the present invention. A fuel cell 1 is supplied with fuel gas reformed by a reformer 7 from a raw material through a fuel gas supply line 4. In FIG. Similarly, air as an oxidizing agent is
Air is supplied from the blower 6 to the fuel cell 1 via the air supply line 2, and undergoes an electrochemical reaction with the fuel gas to generate electricity within the fuel cell 1. The air and fuel gas after being used for power generation become exhaust air and off-gas and are discharged through an air exhaust pipe and an off-gas exhaust pipe, respectively. Heat generated during power generation in the fuel cell 1 is removed by circulating a cooling medium. That is,
The coolant discharged from the coolant circulation pump 8 enters the fuel cell via the coolant piping 9, where it absorbs heat and enters the heat exchanger 12, where it releases heat and passes through the coolant circulation pump 8.
Return to

When stopping the operation of the fuel cell 1, the air supply from the blower 6 is stopped, and at the same time, the supply of raw materials is stopped and the reformer 7 is stopped.
The supply of fuel gas to the fuel cell 1 is then stopped.

Thereafter, the inert gas filled in the liquefied inert gas tank 10 is supplied to the heat exchanger 12 via the inert gas piping 11 by opening the cell 13. Here, the liquefied inert gas is vaporized by receiving heat from the cooling medium heated by the fuel cell 1, enters the fuel cell 1 from the air supply line 2 and the fuel gas supply line 4 via the valve 13, and acts as a purge gas. do.

When a 2.11 tank is used as an example of a liquefied inert gas tank, approximately 760. , e dry carbon dioxide gas can be stored, so compared to the previously used high-pressure gas (filled with 150"f/cd) nitrogen gas 3002, the storage capacity is more than double, simplifying maintenance. .

〔Effect of the invention〕

According to this invention, since liquefied inert gas is used as the purge gas when the fuel tSa is stopped, it not only has the advantage of significantly extending the period of gas tank replacement for maintenance purposes as described above (also If the exchange cycles are made the same, the volume of the gas tank can be reduced, and the present invention can be favorably applied to equipment where downsizing is desired, such as mobile fuel cell equipment.

In addition, even after the fuel cell has stopped operating, the liquefied inert gas can be converted into a gaseous state by receiving heat of vaporization from the circulating cooling medium (including residual heat), so there is no need for a special vaporization device, and the fuel cell The cooling effect after the plant stops operating can be increased, and the temperature drop can be accelerated to improve safety.

[Brief explanation of the drawing]

Figure $1 is a system diagram of a fuel cell gas purge device showing one embodiment of the present invention.

Claims (1)

[Claims] 1) The raw material gas is reformed into a hydrogen-rich gas by a reformer and supplied to the fuel electrode as a fuel gas, and air is supplied as an oxidant to the oxidizer electrode, and an electrochemical reaction between these two gases occurs. In a gas purge device for a fuel cell, which stops the supply of the fuel gas and air to the fuel cell and replaces the gas remaining in the electrode with an inert gas when the operation of the fuel cell that generates electricity is stopped, the liquefied inert gas is used. A gas purge device for a fuel cell, comprising: an inert gas tank for storing liquefied inert gas; the liquefied inert gas stored in the tank is vaporized by heat generated from an operating fuel cell and supplied to the fuel cell;