JPH0622150B2 - Fuel cell power generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel cell power generator using methanol, natural gas, or the like as an energy source, and in particular to an excessive increase in pressure of the reaction gas supplied to and exhausted from the fuel cell body. The present invention relates to a fuel cell power generator equipped with a water sealing device for prevention.

[Prior art and its problems]

FIG. 4 is a schematic configuration diagram of a fuel cell power generator showing an example of a conventional technique. In the figure, 1 is a raw material 1 such as a mixed liquid of methanol and water or a mixed gas of natural gas and steam.
0 through the system 11 to generate a hydrogen-rich fuel gas (hydrogen ratio of about 75 to 80%) and burn combustible gas such as residual hydrogen and carbon dioxide in the exhaust gas of the fuel cell. The reformer 2 is composed of a combustion section or the like for generating the heat energy necessary for the reaction, and 2 is composed of a fuel gas chamber 5, a matrix 6 composed of hydrogen electrodes, oxygen electrodes and the like, an air chamber 7, a cooling plate 8 and the like. A fuel cell body that electrochemically reacts hydrogen and oxygen in a reaction gas consisting of air and air to generate direct current power, and is suitable for reaction by the refrigerant 50 flowing through the cooling plate 8 in the fuel cell body 2 during power generation. By maintaining the temperature at approximately 200 ° C., the temperature of the exhaust gas discharged from the fuel gas chamber and the air chamber 7 is close to 200 ° C.,
Moisture mixed in the reformer 1 is contained in the exhaust gas of the fuel gas chamber,
Exhaust gas in the air chamber contains a large amount of reaction product water.
Reference numeral 3 denotes a steam separator for cooling the exhaust gas from the air chamber 7 and the exhaust gas (hereinafter referred to as combustion gas) from the combustion chamber of the reformer 1 to approximately 40 ° C. or lower to condense and separate water in the exhaust gas. Reference numeral 4 is a recovered water tank for recovering and reusing the water condensed in the steam separator 3.

To start the fuel cell power generator configured as described above from the stopped state, the reformer 1 is heated to a predetermined temperature in advance, the on-off valve 23 for bypass is opened, and the raw material gas supply systems 12, 13 are opened. , 14 the on-off valves 21 and 22 of the closed state 1
The raw material 10 is supplied to the reformer 1 from system 1. The reformed fuel gas is returned to the combustion quality of the reformer 1 through the systems of 12, 13, 17, and 16, and the combustible components are combusted by the air 30 supplied from the system of 35, and the exhaust system 19 of the combustion gas is generated.
After the water is separated from the water through the steam separator 3, the exhaust pipe 33
Is discharged from the outside. The reason why the fuel gas is not supplied to the fuel cell main body by closing the valves 21 and 22 before starting and bypassing the entire amount of fuel gas to the reformer via the on-off valve 23 is that the temperature of the reformer is stable immediately after the start of reforming. This is because the component ratio in the fuel gas is not stable because it has not been performed, and there is a possibility that unreformed raw material or carbon monoxide that poisons the catalyst of the matrix 6 is contained in the allowable value or more. When the ratio of the components in the reformed fuel gas becomes stable, the on-off valves 22, 21 are opened and the fuel gas for closing 23 is passed through the fuel gas supply system 12, 13, 14 and the fuel gas chamber 5 of the fuel cell body 2 is closed. The exhaust gas, which has been supplied to the exhaust gas and has completed the reaction, is returned to the reformer 1 via the exhaust gas systems 15 and 16 and, after burning the combustible gas, is sent to the steam separator 3 via the exhaust gas system 19. On the other hand, the air 30 is supplied to the air chamber 7 of the fuel cell main body 2 from the system of 31, the generated water is separated by the steam-water separator 3 through the exhaust gas system of 32, and the remaining gas is discharged from 33. In this state, power generation is started by connecting an external load device (not shown) to the fuel cell main body. The heat generated by the power generation is removed by the refrigerant supplied to and discharged from the system 51 of the cooling plate 8, and the fuel cell is maintained at about 200 ° C. The water produced by the fuel cell body 2 and the reformer 1 is steam-water separator 3
After being once condensed water 44 and collected in the collected water tank 4, it is reused as, for example, mixed water of the raw material 10 or cooling water via the water supply pipe 42.

By the way, the bypass valve 23 is closed and the fuel gas supply system 1
Since the exhaust gas systems 15, 16, 32, etc. of the fuel gas chamber 5 and the air chamber 7 are not sufficiently warmed at the time when the on-off valves 21, 22, 14 of the fuel cells 2, 13, 14 are opened to start power generation of the fuel cell, etc. Moisture in the exhaust gas is condensed on the pipe wall and collected in the lower part of the pipe, and the exhaust gas passage is narrowed by the banded water. There is a problem that the matrix 6 that increases and holds the electrolyte that divides both chambers is applied with a differential pressure exceeding an allowable value, and sometimes the matrix 6 is broken. Further, there is a risk that a similar accident may occur even when the heat insulation treatment of the exhaust gas systems 1, 16, 32, etc. is insufficient, or the valve 22 or the like malfunctions. Therefore, in order to prevent such an excessive increase in the internal pressure of the fuel cell, the tank 9 storing water 90 at a predetermined depth.
1. A communicating pipe 18 having one end opened in the stored water 90 and the other end connected to a reaction gas supply system such as a fuel gas supply system 12, 13, 14 or an air 30 supply system 31. The exhaust gas system 1 including the valve 22 and the like is provided with a water sealing device 9 made of water and maintaining the liquid level 93 at a constant water level so that the water head difference H is equal to or less than the allowable pressure difference of the matrix 6.
It is known that the internal pressure of the fuel cell 2 does not rise above an allowable value even when the resistance of 5, 16 or 32 rises abnormally. However, in addition to requiring the water tank 91, a water supply pipe 92 for automatically detecting and replenishing water is required for operating the fuel cell unattended, which not only causes an economic disadvantage but also a water source. However, there is a problem in that it is difficult to secure the fuel consumption, for example, the use of a portable fuel cell power generator or a desert area is restricted.

[Object of the Invention]

The present invention has been made in view of the above situation, and an object of the present invention is to provide a fuel cell power generator that includes an inexpensive water sealing device that does not require external water supply.

[Main points of the invention]

The present invention relates to a fuel cell power generator, a fuel cell main body having a fuel gas chamber, a matrix, and an air chamber, a reformer, and a fuel gas supply system for supplying fuel gas from the reformer to the fuel gas chamber. And a reaction gas supply system having an air supply system for supplying air to the air chamber, an exhaust gas system for discharging the remaining fuel gas and air that have completed the reaction in the fuel cell body, and the exhaust gas system. A steam / water separator connected to condense and separate water in exhaust gas, a water tank for storing the recovered water separated by the steam / water separator, and one of a predetermined depth from the liquid surface in the recovered water tank. An external water source and water supply pipe are required by providing a communication pipe having an open end and the other end connected to a reaction gas supply system, and an exhaust pipe for exhausting gas from the upper part of the recovery tank. Inexpensive fuel cell power generation It is obtained as location is obtained.

Example of Invention

 The present invention will be described below based on examples.

FIG. 1 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention, and the same components as those in the prior art are designated by the same reference numerals and detailed description thereof will be omitted. In the figure, reference numeral 40 denotes a water sealing device which also serves as a recovered water tank, receives water condensed and separated by the steam separator 3 through a system 34, and adjusts the water level by a liquid level adjusting unit 45 including an overflow outlet, for example. A recovered water tank 47 that allows the recovered water 44 to be kept constant, and a fuel gas supply system with one end open at a position at a water depth H in the recovered water 44 and the other end indicated by 12, 13, and 14 The connecting pipe 48 is connected.

In the device configured as described above, when the fuel cell 2 is in operation, condensed water is accumulated in the exhaust systems 15 and 16 of the fuel gas chamber 5 to hinder the flow of exhaust gas, or the on-off valve 22 malfunctions. When the internal pressure of the fuel gas chamber 5 rises, the internal pressure of the fuel gas chamber 5 rises, and this internal pressure communicates with the on-off valve 2
1, the internal pressure of the supply systems 14, 13, 12 and the communication pipe 48 is increased, the water invading the part of the communication pipe 48 immersed in the recovered water 44 is pushed out, and the internal pressure exceeds the water head difference of the water depth H. At this time, the fuel gas blows into the recovered water from the opening of the communication pipe 48, the internal pressure of the fuel gas chamber 5 is kept substantially at the above water head difference, and it is possible to prevent an unexpected accident such as breakage of the matrix 6. The relationship between the water depth H and the matrix damage prevention will be described more specifically below.

The allowable differential pressure between the fuel gas chamber and the air chamber (hereinafter referred to as AP) for preventing the matrix from being damaged is, for example, 50
It is about 0 mmAq. In addition, the differential pressure between the fuel gas chamber and the air chamber during operation of the fuel cell under normal conditions (hereinafter referred to as RP)
Is about 50 to 200 mmAq at maximum.

In the above, if the water depth H is set to 400 mm, for example, the pressure is released within the differential pressure increase range of 200 to 350 mmAq, and damage to the matrix can be prevented.

That is, as the water depth H, a predetermined value within the following range is selected.

RP <H <AP Further, the temperature of the recovered water is 40 by passing through the steam separator 3.
Since it is cooled to below ℃, the fuel gas that has blown out as bubbles in the recovered water 44 is cooled in the recovered water, and the exhaust pipe 4
Since it is released into the atmosphere via 1 and 33 and diffuses, the risk of ignition of fuel gas can be eliminated. Further, the water level of the recovered water 44 can be always kept constant by the overflow discharge port 45, and there is no need to supply water from the outside or a pipe for that purpose.

In the above-described embodiment, the example in which the other end of the communication pipe 48 is connected to the fuel gas supply systems 12, 13 and the like has been described, but the communication pipe 48 is connected to the supply system 31 of the air 30 as the oxidant. By doing so, it is possible to prevent an excessive increase in the internal pressure of the air chamber 7.

FIG. 2 is a structural diagram of the main part showing a different embodiment, in which a water sealing device 60 also serving as a recovery tank is constructed by a partition wall 66 whose upper end is located at a predetermined liquid level 43 inside the recovery water tank 67. The communication pipe 4 is divided into compartments, and the compartment 68 has a small area.
8 is different from the above-described embodiment in that one end is opened and the condensed water from the steam separator 3 is supplied into the compartment 68 via the system 64. By supplying, for example, the reformer 1 or the like with a suitable amount of recovered water via the drain pipe 65 provided at the bottom of the recovered water tank 67, the partition wall 66 functions as a liquid level adjusting unit and the liquid level 43 is kept at a constant level. Can be held.

FIG. 3 is a structural view of the main part of another embodiment, in which the float valve 79 is provided on the inlet side of the drainage pipe 75 to maintain the liquid level 43 at a predetermined level. The liquid surface can be maintained at a constant level as in the above-described embodiment.

〔The invention's effect〕

The present invention, as described above, is provided with a water level adjusting means in the recovered water tank that stores the water in the exhaust gas of the fuel cell condensed and separated by the steam separator, while maintaining a constant water level, and one end of the recovered water is A water sealing device which doubled as a recovered water tank was constructed by adding a communication pipe which was opened and the other end of which was connected to the reaction gas supply system. As a result, the use of water in the exhaust gas eliminates the need for external water supply or water supply piping, which was a problem in the conventional technology, and therefore there is no restriction on the installation location or application of the device, and excessive pressure differential It is possible to provide a fuel cell power generator in which the risk of matrix damage is eliminated. Further, since the recovered water tank in the prior art is also used as the water sealing device, the number of tanks can be reduced, and the external water supply pipe and its laying work are not required, so that the fuel cell power generator is economically advantageous. Can be provided to.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention, FIG. 2 is a structural view of a main part showing a different embodiment, FIG. 3 is a structural view of a main part showing another embodiment, and FIG. It is a schematic block diagram which shows an example of a conventional technique. 1 ... Reformer, 2 ... Fuel cell main body, 3 ... Steam separator, 4 ... Recovery water tank, 5 ... Fuel gas chamber, 6 ... Matrix, 7 ... Air chamber, 8 ... Cooling plate, 12, 1
3, 14 ... Fuel gas supply system, 15, 16 ... Exhaust gas system (fuel chamber side), 19 ... Exhaust gas system (fuel gas side) 21, 22 ... Open / close valve, 23 ... Bypass valve, 3
1 ... Air supply system, 32 ... Exhaust gas system (air chamber side), 9 ... Water sealing device, 40, 60 ... Water sealing device that also serves as a recovered water tank, 44 ... Recovered water, 47, 67 ... ... Recovered water tank, 18,48 ... Communication pipe, 45,66,79 ...
... Liquid level adjusting means, 10 ... Raw material, 30 ... Air, 90 ...
… Make-up water.

Claims (1)

[Claims] 1. A fuel cell main body having a fuel gas chamber, a matrix and an air chamber, a reformer, a fuel gas supply system for supplying fuel gas from the reformer to the fuel gas chamber, and air for the air. A reaction gas supply system having an air supply system for supplying to the chamber, and an exhaust gas system for discharging the remaining fuel gas and air after the reaction in the fuel cell main body,
A steam / water separator connected to the exhaust gas system for condensing and separating water in exhaust gas, a recovered water tank for storing recovered water separated by the steam / water separator, and a predetermined level from the liquid surface in the recovered water tank A fuel cell power generator comprising: a communication pipe having one end open to the depth and the other end connected to a reaction gas supply system; and an exhaust pipe for exhausting gas from an upper portion of the recovery tank.