JP2003297402A - Fuel cell power generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power generating device capable of preventing the combustible gas from being emitted to the outside and ensuring the safety. <P>SOLUTION: The fuel cell power generating device is composed of a power generating stack 3 to make power generation using a fuel gas chiefly containing hydrogen, inflow pipings 41 and 42 installed to the stack 3 and admitting flowing-in of the fuel gas, a first gas-water separator 21 installed on the pipings 41 and 42 for separating the gas from water, an outflow piping 43 installed to the stack 3 for flowing out the exhaust gas discharged from the stack 3, and a second gas-water separator 22 installed on the outflow piping 43 and for separating the gas from the water and arranged to drain the exhaust water of the first gas-water separator 21 from the draining hole. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a power generation stack,
The present invention relates to a fuel cell power generator including a reformer, a reformer heating burner, and the like.

[0002]

2. Description of the Related Art FIG. 6 shows, for example, JP-A-8-162137.
FIG. 6 is a configuration diagram showing a conventional fuel cell power generation device disclosed in Japanese Patent Publication No. In FIG. 6, 1 is a reformer for reforming a reforming raw material such as city gas into a gas containing hydrogen as a main component, and 2 is a CO remover for reducing carbon monoxide in the reformed gas generated by the reformer. Is.

Reference numeral 3 denotes a power generation stack in which a plurality of fuel cells composed of a fuel electrode 3a, an air electrode 3b, etc. are laminated, 4 a burner for heating the reformer 1, and 11 to 15 flow rates of air, water and city gas. Is a regulating valve for adjusting. 31 to 33 are CO
On-off valves 41 to 44 for switching the flow path of the reformed gas sent from the remover 2 are pipes for circulating the reformed gas.

Next, the operation of the conventional fuel cell power generator will be described with reference to FIG. During the steady operation, water and city gas as reforming raw materials are supplied to the reformer 1 with their flow rates adjusted by the adjusting valves 12 and 13, and are reformed into hydrogen-based gas. Carbon monoxide in the reformed gas sent from the reformer 1 is reduced in the CO remover 2. This is the power generation stack 3
This is because if the carbon monoxide concentration in the reformed gas supplied to the fuel cell is high, the power generation output may be reduced or the fuel electrode 3a may be deteriorated.

At this time, since the on-off valve 31 and the on-off valve 32 are open and the on-off valve 33 is closed, the reformed gas delivered from the CO remover 2 is supplied to the fuel electrode 3a of the power generation stack 3. . On the other hand, the air electrode 3b of the power generation stack 3 is supplied with the air whose flow rate is adjusted by the adjusting valve 11. Oxygen in the air reacts with hydrogen in the reformed gas supplied to the fuel electrode 3a to generate electricity.

Generally, 70% to 80% of hydrogen contained in the reformed gas is consumed for power generation at the fuel electrode 3a, and the remaining reformed gas is supplied to the burner 4 via the on-off valve 32 and the pipe 43. It The burner 4 receives the supply of the air whose flow rate is adjusted by the adjusting valve 15 and burns the reformed gas to heat the reformer 1 to obtain the heat necessary for the reforming reaction. The air that has consumed oxygen at the air electrode 3b of the power generation stack 3 is released to the outside.

When the amount of heat required for the reforming reaction of the reformer 1 cannot be covered by the reformed gas discharged from the fuel electrode 3a, the city gas whose flow rate is supplementarily adjusted by the regulating valve 14 is supplied to the burner 4. Supply. Further, even during the transitional period in which the power generation output is increased, the amount of heat required for the reforming reaction of the reformer 1 cannot be obtained only by the reformed gas discharged from the fuel electrode 3a.
The city gas is supplied from the adjusting valve 14 to.

At the time of startup, it is necessary to raise the temperature of the reformer 1, the CO remover 2, etc. to the temperature required for each reaction, and therefore the operation is performed in the following procedure. First, the air whose flow rate is adjusted by the adjusting valve 15 and the city gas whose flow rate is adjusted by the adjusting valve 14 are supplied to the burner 4 and burned to heat the reformer 1. When the temperature of the reformer 1 rises to a temperature at which the reforming reaction can be performed, city gas whose flow rate is adjusted by the adjusting valve 13 and water whose flow rate is adjusted by the adjusting valve 12 are supplied to start reforming.

The CO remover 2 is fed with the reformed gas from the reformer 1 and is heated by a reaction for reducing carbon monoxide.
The on-off valve 31 and the on-off valve 32 are closed and the on-off valve 32 is opened. The reformed gas sent from the CO remover 2 is directly supplied to the burner 4 and burned through the pipe 44 without being consumed by the power generation stack 3. This has an effect of preventing the power generation stack 3 from being deteriorated by the incomplete reformed gas generated while the reformer 1 and the CO remover 2 have not risen to the predetermined temperature.

When the reformed gas is supplied to the burner 4, the city gas supplied from the adjusting valve 14 is reduced in order to adjust the calorific value of the burner 4. When the reformer 1 and the CO remover 2 are heated to a predetermined temperature and a reformed gas having a composition that can be supplied to the power generation stack 3 is obtained, the on-off valve 31 and the on-off valve 32 are opened and the on-off valve 33 is opened. The closed gas is supplied to supply the reformed gas to the fuel electrode 3a. At the same time, air is supplied to the air electrode 3b and power generation is started.

Generally, in the pipes 41 to 43 and 44,
The reformed gas is cooled by the heat radiation of the piping, and condensed water is generated. Further, when the reformed gas having a temperature higher than the operating temperature is supplied to the power generation stack 3, condensed water may be generated in the flow path of the fuel electrode 3a. When the reformed gas discharged from the power generation stack 3 is used as a fuel for the burner 4, if condensed water flows into the burner 4 as water droplets, it may cause misfire or unstable combustion.

[0012] In order to prevent this, in general
As shown in Japanese Patent Publication No. 0-21430 (see FIG. 7), steam separators 21 and 22 are installed on the upstream side of the burner 4.
Further, regarding the reformed gas supplied from the CO remover 2 to the power generation stack 3, in order to avoid the adverse effect of the condensed water generated in the pipe 41 on the operation of the power generation stack 3, steam or water is provided on the upstream side of the fuel electrode 3a. A separator is installed. FIG. 7 is a configuration diagram in which these steam separators are installed.

In FIG. 7, the components denoted by the same reference numerals as those in FIG. 6 are the same or corresponding components. In FIG. 7, reference numerals 21 and 22 are steam separators, 34 and 35 are on-off valves for controlling discharge of condensed water accumulated in the steam separators 21 and 22, and 45 and 46 are drainage pipes. The on-off valves 34 and 35 are normally closed, and the reformed gas is sent to the fuel electrode 3a and the burner 4, respectively.

When condensed water accumulates in the steam separators 21 and 22 and reaches a predetermined amount, a water level detector (not shown) detects it,
The on-off valves 34 and 35 are opened and the water is drained through the pipes 45 and 46. When the water in the steam separators 21 and 22 is discharged, the open / close valves 34 and 35 are closed. At this time, the steam separator 21,
Since the reformed gas will be discharged if the opening / closing valves 34, 35 are opened until the water in 22 is completely discharged, the opening / closing is performed with a slight amount of water remaining in the steam separators 21, 22. The valves 34, 35 need to be closed.

[0015]

By the way, the reformed gas discharged from the CO remover 2 during steady operation contains about 60% of combustible gas containing hydrogen as a main component, and this is released to the outside. Since it is very dangerous if the operation is performed, an accurate and highly reliable operation of the condensed water discharge system including the steam separator 21, the on-off valve 34, and the like is required.

Incidentally, the combustible gas concentration of the reformed gas flowing through the steam / water separator 22 during steady operation is reduced to about 20% by the consumption of hydrogen at the fuel electrode 3a. In some cases, the reformed gas directly discharged from 21 contains foreign matter such as fine powder generated from the catalyst filled in the reformer 1 and the CO remover 2. Open / close valves 34, 35
Generally, a solenoid valve is used for the above, but there is a case where a foreign matter contained in the reformed gas enters the valve portion, and a phenomenon of not completely closing occurs when it is desired to close the valve portion.

In this case, the flammable gas is discharged from the pipe 45 to the outside. Also, the steam separators 21 and 22
If the water level detector built into the unit malfunctions due to foreign matter, etc., the level of accumulated water, especially the level of water remaining when draining, cannot be detected correctly and the on-off valve cannot be closed. Occur.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a safe fuel cell power generator which prevents the release of flammable gas to the outside.

[0019]

A fuel cell power generator according to the present invention includes a power generation stack for generating power using a fuel gas containing hydrogen as a main component, an inflow pipe provided in the power generation stack for inflowing the fuel gas, and A first steam separator provided in the inflow pipe for separating gas and water, an outflow pipe provided in the power generation stack for outflowing exhaust gas output from the power generation stack, and a gas and water provided in the outflow pipe And a second steam-water separator configured to discharge the wastewater of the first steam-water separator from its drain port.

The drain port of the first steam separator is directly connected to the second steam separator.

Further, the drain port of the first steam / water separator is connected to a pipe connecting the power generation stack and the second steam / water separator.

Further, a reformer for reforming the reforming raw material into a gas containing hydrogen as a main component and a burner for heating the reformer are provided,
One end of the inflow pipe is connected to the reformer, one end of the outflow pipe is connected to the burner, is configured to supply the exhaust gas to the burner, the first steam separator and the power generation stack A first valve provided in the connecting pipe, a second valve provided in the drain port of the first steam separator, and a drain valve provided in the second steam separator. The third valve and the second valve at the time of start-up are opened to supply the reformed gas to the burner through the first steam-water separator, the second valve and the second steam-water separator. It is configured to be supplied for use.

Further, a third pipe connecting the first pipe between the first steam / water separator and the power generation stack and the second pipe between the power generation stack and the second steam / water separator. When,
And a valve provided in the third pipe.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a configuration diagram showing a fuel cell power generation device according to Embodiment 1 of the present invention, and FIG. 2 is a configuration diagram showing the steam separator shown in FIG. In FIGS. 1 and 2, the same reference numerals as those in FIGS. 6 and 7 are the same or equivalent.
Reference numeral 47 denotes water that has accumulated in the steam / water separator 21 during steady operation and flows to the steam / water separator 22.
2 is a pipe for circulating the reformed gas. During steady-state operation, the water and city gas, which are the reforming raw materials, are adjusted by the control valves 12, 13
The flow rate is adjusted by and is supplied to the reformer 1, and is reformed into a gas containing hydrogen as a main component.

The reformed gas sent from the reformer 1 is reduced in carbon monoxide by the CO remover 2 and sent to the steam separator 21. At this time, since the on-off valve 31 and the on-off valve 32 are open and the on-off valve 34 is closed, the reformed gas delivered from the steam separator 21 is supplied to the fuel electrode 3a of the power generation stack 3. On the other hand, the air electrode 3b of the power generation stack 3 has a regulating valve 11
It receives the supply of air whose flow rate is adjusted. Oxygen in the air reacts with hydrogen in the reformed gas supplied to the fuel electrode 3a to generate electricity.

The reformed gas discharged from the fuel electrode 3a passes through the on-off valve 32, the pipe 43 and the steam separator 22 and the burner 4
Is supplied to. The burner 4 receives the supply of the air whose flow rate is adjusted by the adjusting valve 15 and burns the reformed gas to heat the reformer 1 to obtain the heat necessary for the reforming reaction. The air that has consumed oxygen at the air electrode 3b of the power generation stack 3 is released to the outside. When the amount of heat required for the reforming reaction of the reformer 1 cannot be covered by the reformed gas discharged from the fuel electrode 3a, the city gas whose flow rate is adjusted by the adjusting valve 14 is supplementarily supplied to the burner 4.

At the time of start-up, the reformer 1, the CO remover 2, etc. are operated in the following procedure in order to raise the temperature to the temperature required for each reaction. First, the air whose flow rate is adjusted by the adjusting valve 15 and the city gas whose flow rate is adjusted by the adjusting valve 14 are supplied to the burner 4 and burned to heat the reformer 1. Reformer 1
When the temperature rises to a temperature at which the reforming reaction can be performed, city gas whose flow rate is adjusted by the adjusting valve 13 and water whose flow rate is adjusted by the adjusting valve 12 are supplied to start reforming.

The CO remover 2 is supplied with the reformed gas from the reformer 1 and is heated by a reaction for reducing carbon monoxide. The on-off valve 31 and the on-off valve 32 are closed, the on-off valve 34 is opened, and the reformed gas sent from the CO remover 2 is passed directly through the pipe 47 without being consumed by the power generation stack 3.
Is supplied to and burned. When the reformed gas is supplied to the burner 4, the city gas supplied from the adjusting valve 14 is reduced in order to adjust the heat generation amount of the burner 4.

When the reformer 1 and the CO remover 2 are heated to a predetermined temperature and a reformed gas having a composition that can be supplied to the power generation stack is obtained, the on-off valve 31 and the on-off valve 32 are opened,
The on-off valve 34 is closed to supply the reformed gas to the fuel electrode 3a.
At the same time, air is supplied to the air electrode 3b and power generation is started. The on-off valve 34 is normally closed except that it is opened to directly supply the reformer gas sent from the CO remover 2 to the burner 4 at the time of startup.

A predetermined amount (water level high level 2) is added to the steam separator 21.
When the water 21B (amount exceeding 1b) is accumulated, the water level detector (float switch) 21A detects it, an electric contact (not shown) is turned on, the on-off valve 34 is opened, and the water is discharged to the steam separator 22 through the pipe 47. To do. Specifically, referring to FIG. 2, when the water 21B is accumulated up to the water level high level 21b, the float 21a rises to the water level high level 21b, an electric contact (not shown) is turned on, and an electromagnetic relay (not shown) is operated to operate the solenoid valve. A certain open / close valve 34 is opened for a predetermined time by a timer (not shown), and the steam / water separator 22 is passed through the pipe 47.
Drain to.

The predetermined time is a little shorter than the time when all the water 21B accumulated to the high water level is discharged.
In addition to the high water level 21b, a low water level and its detector may be provided to close the solenoid valve 34 when the water level becomes low. In this case, the timer is unnecessary. When the water in the steam separator 21 is discharged, the opening / closing valve 34
Is closed. If the opening / closing valve 34 is opened until the water in the steam / water separator 21 is completely drained, the reformed gas will be discharged. Therefore, opening / closing the steam / water separator 21 with a slight amount of water remaining therein The valve 34 is closed.

Similarly, the on-off valve 35 is normally closed.
The water sent from the steam separator 21 to the steam separator 22,
When a predetermined amount of water condensed in the power generation stack 3 and the pipe 43 is accumulated, a water level detector (not shown) detects it and opens the open / close valve 35 to drain it to the outside through the pipe 46. Close. If the opening / closing valve 35 is opened until the water in the steam / water separator 22 is completely drained, the reformed gas will be discharged. Therefore, the opening / closing valve 35 is opened / closed with a slight amount of water remaining in the steam / water separator 22. The valve 35 is closed. In addition, the steam separator 22
The basic configuration of is the same as that of the steam separator 21 shown in FIG.

Comparing the air / water separator 21 and the air / water separator 22, it is necessary to pass a predetermined flow rate of the reformed gas through the pipe 47 at the time of start-up, so that the pipe diameter required from the drainage function of the water 21B is smaller than the pipe diameter. A large diameter pipe 47 is required, and the pipe 46
Larger diameter is required. Therefore, the water 21B
Since the drainage time is short, it is preferable to employ an electromagnetic valve whose time can be easily set as the opening / closing valve 34 and combine it with the steam separator 21 as shown in the first embodiment.

When foreign matter or the like enters and the opening / closing valve 34 is not completely closed, a part of the reformed gas in the steam / water separator 21 is sent to the steam / water separator 22 through the pipe 47 and further to the burner 4. It is sent and burned. Even when the water level detector 21A built in the steam separator 21 cannot detect that all the water has been discharged and the on-off valve 34 cannot be closed, the reformed gas in the steam separator 21 is connected to the pipe 47. Through steam separator 2
2, sent to the burner 4 and burned. Therefore, it is possible to prevent the gas having a high hydrogen component concentration from leaking to the outside, and to obtain a safe fuel cell power generator.

When the amount of the reformed gas supplied to the power generation stack 3 decreases or the amount of the combustible gas supplied to the burner 4 increases in the above-mentioned state, the output of the power generation stack 3 lowers, An abnormal temperature rise of the burner 4 and the reformer 1 is detected, and safe and appropriate processing such as stopping the power generator is performed. Further, it is possible to omit the dedicated pipe and the on-off valve (the on-off valve 33 and the pipe 44 in FIG. 7), which also contributes to the reduction of the manufacturing cost, the simplification of the structure, and the downsizing.

Embodiment 2. In the first embodiment, the pipe 47 for draining the water in the steam separator 21 is connected to the steam separator 22.
However, as shown in FIG. 3, the same operation can be expected by connecting the open / close valve 32 to the pipe 43 between the steam separators 22. In this case, consideration should be given to increasing the diameter of the pipe 43 so that the water sent from the pipe 47 does not block the pipe 43, or providing a gradient for pouring the water in the pipe 43 into the steam separator 22. Is preferred.

Since the other structure is the same as that of the first embodiment, the description thereof will be omitted. In this case, since it is sufficient to connect the pipe 47 and the pipe 43, the pipe 47 is connected to the steam separator 2.
The number of pipes connected to the steam separator 22 is reduced as compared with the case where the steam separator 22 is connected, so that the steam separator 22 can be downsized and the connecting work of the pipe 47 can be simplified.

Embodiment 3. In the first and second embodiments, the pipe 47 for draining the water of the steam separator 21 at the time of startup.
Since the reformed gas is supplied to the reformer 1 through the open / close valve 34 and the open / close valve 34, large pipes 47 and open / close valves 34 are required. In the third embodiment, as shown in FIG. 4, a bypass line for starting the on-off valve 33 and the pipe 44 is provided. The other configurations are similar to those of the first and second embodiments, and therefore the description thereof will be omitted.

At startup, the on-off valves 31, 32 and 34 are closed and the on-off valve 33 is opened. The reformed gas output from the reformer 1 is CO removed by the CO remover 2, and the on-off valve 33 and the pipe 44 are provided. Then, it is supplied to the burner 4 through the pipe 43 and the steam separator 22. On the other hand, during steady operation, the on-off valves 33 and 34 are closed, the on-off valves 31 and 32 are opened, and the reformed gas output from the reformer 1 has CO removed by the CO remover 2 and the on-off valve 3
The gas having a reduced hydrogen content is supplied to the burner 4 through the open / close valve 32, the pipe 43, and the steam separator 22.

Therefore, since the reformed gas passes through the on-off valve 33 and the pipe 44 at the time of startup, the diameter of the pipe 47 can be reduced and the on-off valve 34 can be reduced. Furthermore, since small pipes 47 and open / close valves 34 can be used, the amount of water drained from the steam separator 21 is small, and a large amount of water can be prevented from flowing into the steam separator 22 in a short time. Valve 34
Other than the solenoid valve, and the steam-water separator 21 other than the float type can also be used. Note that, as shown in FIG. 5, even if a bypass line is provided at the time of starting the on-off valve 33 and the pipe 44, the same effect as above can be obtained.

[0041]

Since the present invention is constructed as described above, it has the following effects.

According to the present invention, a second steam separator provided in the outflow pipe and configured to separate the gas and the water and to discharge the waste water of the first steam separator from the drain port thereof. With this configuration, it is possible to prevent the gas having a high concentration of hydrogen components from leaking to the outside, and to obtain a safe fuel cell power generator.

Further, by constructing the drain port of the first steam separator by directly connecting it to the second steam separator, it is possible to prevent the gas having a high hydrogen component concentration from leaking to the outside. Therefore, a safe fuel cell power generator can be obtained.

Further, by constructing the drain port of the first steam / water separator by connecting it to the pipe connecting the power generation stack and the second steam / water separator, the gas having a high hydrogen component concentration is discharged to the outside. It is possible to prevent leakage and obtain a safe fuel cell power generator.

Further, at the time of start-up, the second valve is opened so that the reformed gas is supplied to the burner for fuel through the first steam / water separator, the second valve and the second steam / water separator. By doing so, it is possible to prevent the gas having a high hydrogen component concentration from leaking to the outside, and it is possible to obtain a safe fuel cell power generation device.

A first pipe between the first steam / water separator and the power generation stack, a third pipe connecting the second pipe between the power generation stack and the second steam / water separator, and a third pipe Since the reformed gas can pass through this valve and the third pipe at the time of start-up, the first steam separator and the second steam can be provided. Since the diameter of the pipe between the separators can be made small and the valve provided in this pipe can be made small, a large amount of water can be prevented from flowing from the first steam separator to the second steam separator.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a fuel cell power generation device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a (first) steam separator according to Embodiment 1 of the present invention.

FIG. 3 is a configuration diagram showing a fuel cell power generation device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a fuel cell power generation device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing another fuel cell power generation device according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram showing a conventional fuel cell power generation device.

FIG. 7 is a configuration diagram showing another form of a conventional fuel cell power generation device.

[Explanation of symbols]

1 reformer, 2 CO remover, 3 power generation stack, 4
Burner, 21, 22 steam separator, 21A water level detector,
31-35 on-off valve, 41-47 piping.

Claims (5)

[Claims] 1. A power generation stack for generating power using a fuel gas containing hydrogen as a main component, an inflow pipe provided in the power generation stack for inflowing the fuel gas, and a first pipe provided in the inflow pipe for separating gas and water. Water vapor separator, an outflow pipe provided in the power generation stack for outflowing the exhaust gas output from the power generation stack, and gas and water separated in the outflow pipe and A fuel cell power generation device comprising: a second steam separator configured to discharge wastewater from its drainage port. 2. The fuel cell power generator according to claim 1, wherein a drain port of the first steam / water separator is directly connected to the second steam / water separator. 3. The fuel cell power generation system according to claim 1, wherein a drain port of the first steam / water separator is connected to a pipe connecting the power generation stack and the second steam / water separator. apparatus. 4. A reformer for reforming a reforming raw material into a gas containing hydrogen as a main component, and a burner for heating the reformer. One end of an inflow pipe is connected to the reformer, and an outflow pipe is provided. A first valve connected to the burner and configured to supply exhaust gas to the burner, the first valve being provided in a pipe connecting the first steam separator and the power generation stack; The second valve provided at the drain port of the first steam separator, the third valve provided at the drain port of the second steam separator, and the second valve at startup An open reformed gas is configured to be supplied to the burner for fuel through the first steam-water separator, the second valve and the second steam-water separator. The fuel cell power generator according to any one of 1 to 3. 5. A third pipe connecting the first pipe between the first steam / water separator and the power generation stack and the second pipe between the power generation stack and the second steam / water separator. And a valve provided in the third pipe, and the fuel cell power generator according to any one of claims 1 to 4.