JP3312498B2 - Fuel cell generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generator.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features that are not found in conventional power generators, such as high efficiency and little impact on the environment. They are attracting attention as power generation systems following hydro, thermal and nuclear power. And research is being conducted in various countries around the world.

FIG. 2 shows an example of a molten carbonate fuel cell power generator using natural gas as a fuel. As shown in the figure, a power generator includes a reformer 3 for reforming a fuel gas 1 in which natural gas and steam are mixed into an anode gas 2 containing hydrogen, a cathode gas 4 containing oxygen, and the anode gas 2.
And a fuel cell 5 for generating electricity from the fuel cell 5. The anode gas 2 produced by the reformer 3 is supplied to the anode An of the fuel cell 5. 6, and is supplied to the combustion chamber Co of the reformer 3 as combustion gas by the anode exhaust gas line 7. Note that the fuel cell 5 is stored in the storage container 8 to prevent flammable gas and the like from leaking to the outside to enhance safety.

The reformer 3 burns combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 6 leaving the fuel cell 5 and a part of the cathode exhaust gas 9 to produce a high-temperature combustion exhaust gas 10. A combustion chamber Co is formed, and a reforming chamber Re filled with a reforming catalyst to reform the fuel gas 1 by heat transfer from the combustion chamber Co. The high-temperature anode gas 2 containing hydrogen is cooled through the fuel heater 11 and supplied to the anode An of the fuel cell 5. On the other hand, the combustion exhaust gas 10 whose temperature has been lowered by the heat release passes through an exhaust gas supply line 12, is cooled by an air preheater 13, moisture is removed by a condenser 14 and a steam separator drum 15, and pressurized by a low temperature blower 16, 17 and heated by the air preheater 13 to enter the cathode circulation line 18.

The cathode gas 4 partially reacts with the cathode Ca of the fuel cell 5 to become a high-temperature cathode exhaust gas 9,
After the power is recovered by being guided to the turbine compressor 21 that compresses the air 17 by the cathode exhaust gas line 34, the steam 23 is generated by the steam generator 22 for exhaust heat recovery, and is discharged outside the system. Has become. The steam 23 is sent to a fuel gas supply line 25 by a steam line 24 and mixed with a source gas 26 such as a natural gas sent from a source blower 27 to become a fuel gas 1 and a reforming chamber Re of the reformer 3.
It is supplied to.

A part of the cathode exhaust gas 9 of the fuel cell 5 is supplied to the air preheater 13 by a cathode circulation line 18.
And is circulated and supplied as cathode gas 4 to the cathode Ca of the fuel cell 5 by the high-temperature blower 28.

The air 17 compressed by the air compressor C of the turbine compressor 21 joins the exhaust gas 10 from which the moisture has been removed at the outlet of the low-temperature blower 16. An air line 51 downstream of the air compressor C of the turbine compressor 21 is provided with a bypass line 30 having an air blower 29, and a capacity of the air 17 compressed by the air compressor C of the turbine compressor 21. The air blower 29 is used as a backup when a shortage occurs. In FIG. 2, reference numeral 63 denotes a check valve.

That is, the air blower 29 is connected to the fuel cell 5
Even when the flow rate of the cathode exhaust gas 9 sent to the turbine compressor 21 is low, such as during low load operation including the start-up of the air, the air 1
In order to satisfy the required quantity of 7, the air compressor C is operated so as to compensate for the shortage.

In FIG. 2, at the outlet of the raw material blower 27,
A fuel supply valve 31 is provided, and an outlet of the fuel supply valve 31 is provided.
The N side fuel gas supply line 25 has N_TwoEquipped with a supply valve 32
N_Two The gas purge line 33 is connected.

On the other hand, the fuel cell power generator is provided with a starting hot air generator 50 used at the time of starting. The starting hot air generating furnace 50 is provided with the air compressor C of the turbine compressor 21 or the air blower. An air line 52 for a hot air generating furnace branched from an air line 51 through which the air 17 is pumped by 29 is connected, and an air valve 53 for a hot air generating furnace is provided in the air line 52 for the hot air generating furnace. A fuel line 54 for a hot air generating furnace branched from the fuel gas supply line 25 between the fuel gas supply line 27 and the fuel supply valve 31 is connected, and a fuel supply valve 55 for a hot air generating furnace is provided in the middle of the hot air generating furnace fuel line 54. , The hot air generator 50 for startup
A starting heater 57 for heating the cathode gas 4 with the exhaust gas 56 discharged from the cathode circulation line 1
8, an exhaust gas line 58 for a hot air generating furnace through which the exhaust gas 56 after heating the cathode gas 4 by the starting heater 57 flows from the cathode exhaust gas line 34 to the combustion chamber Co of the reformer 3. Cathode branch line 59 leading
They are joined on the way.

A reforming furnace fuel line 6 which branches off from the middle of the hot air generating furnace fuel line 54 upstream of the hot air generating furnace fuel supply valve 55 and communicates with the anode exhaust gas line 7.
0, a fuel supply valve 61 for the reformer is provided in the middle of the fuel line 60 for the reforming furnace, and a main air valve 62 is provided in the middle of the air line 51 downstream from the branch point of the air line 52 for the hot blast generating furnace. Is provided.

When the fuel cell power generator as described above is started, the fuel supply valve 31, the reformer fuel supply valve 61 and the main air valve 62 are closed, the N ₂ supply valve 32 is slightly opened, and the N ₂ gas purge line 33 is opened. While supplying N ₂ gas little by little, the cathode circulation line 1 is driven by driving the high-temperature blower 28.
8 circulates the gas in the hot air generating furnace air valve 5.
3 to drive the air blower 29 to start the hot air generator 5
In addition, the air 17 is supplied to the hot air generating furnace 50 and the fuel supply valve 55 for the hot air generating furnace is opened to drive the raw material blower 27 to supply the raw material gas 26 such as natural gas to the starting hot air generating furnace 50. The high temperature exhaust gas 56 due to the combustion generated in the cathode circulation line 18 is guided to the starting heater 57.
The temperature of the fuel cell 5 is increased by heating the gas circulated in the step (1).

An exhaust gas 56 discharged from the starting hot air generator 50 and radiated by the starting heater 57 is supplied to a combustion chamber Co of the reformer 3 via a cathode branch line 59, and is subjected to the reforming. By opening the dexterous fuel supply valve 61 and supplying a part of the raw material gas 26 such as natural gas to the combustion chamber Co of the reformer 3 through the anode exhaust gas line 7, the raw material gas 26 is contained in the exhaust gas 56 in the combustion chamber Co. The raw material gas 26 is burned by using the remaining O _2, and the temperature of the reformer 3 is raised.
When the temperature reaches 70 ° C.), the supply of the raw material gas 26 to the hot air generating furnace 50 for startup is stopped by closing the fuel supply valve 55 for hot air generating furnace, and the air valve 53 for hot air generating furnace is closed to generate hot air for starting. The supply of the air 17 to the furnace 50 is stopped, and the fuel supply valve 61 for the reformer is closed to supply the raw material gas 2 to the combustion chamber Co.
6, the supply of N ₂ gas is stopped by closing the N ₂ supply valve 32, and the main air valve 62 is opened to release the air 17 from the air blower 29 by driving the low-temperature blower 16. The fuel is supplied to the combustion chamber Co of the reformer 3 via the air preheater 13, the cathode circulation line 18, the high-temperature blower 28, the starting heater 57, the fuel cell 5, the cathode exhaust gas line 34, the cathode branch line 59, and the fuel. By opening the valve 31, the supply of the fuel gas 1 obtained by adding the steam 23 to the raw material gas 26 to the reforming chamber Re of the reformer 3 is started, and the operation is shifted to a steady operation.

After the start-up of the fuel cell power generator to the steady operation, the flow rate of the cathode exhaust gas 9 sent to the turbine compressor 21 is secured, and the air 17
Is satisfied, the air blower 29 is stopped.

[0015]

However, in the case of the fuel cell power generator as described above, the cathode exhaust gas 9 is hardly supplied to the turbine T of the turbine compressor 21 at the time of startup, and the air compressor C does not operate. Since the air blower 29 provided in the bypass line 30 is driven to supply the air 17 to the hot air generator 50 for starting, the pressure at the outlet of the air compressor C of the turbine compressor 21 becomes negative pressure. When the lubricating oil of the shaft of the turbine compressor 21 leaks to the outlet side of the air compressor C and the operation shifts to the steady operation after the start, the lubricating oil leaked together with the air 17 is introduced into the fuel cell 5. In addition, the performance and life of the fuel cell 5 are reduced due to the sulfur content in the lubricating oil.

According to the present invention, in view of such circumstances, the pressure on the outlet side of the air compressor C of the turbine compressor 21 becomes a negative pressure at startup, and the lubricating oil on the shaft of the turbine compressor 21
Can be prevented from leaking to the outlet side of the fuel cell, and even if the operation shifts to a steady operation after startup, the lubricating oil can be prevented from being introduced into the fuel cell 5 together with the air 17 and is included in the lubricating oil. It is an object of the present invention to provide a fuel cell power generator capable of preventing the performance and the life of the fuel cell 5 from being reduced by the sulfur content.

[0017]

According to the present invention, the fuel gas 1 obtained by adding steam 23 to the raw material gas 26 from the raw material blower 27 during the steady operation is led to the reforming chamber Re of the reformer 3 for reforming. The anode gas 2 containing the reformed hydrogen into the fuel cell 5
And the cathode gas 4 is supplied to the cathode Ca of the fuel cell 5 to generate electricity, and the cathode exhaust gas 9 from the cathode Ca is led to the turbine T of the turbine compressor 21, and the turbine compressor 21
17 from the air compressor C and air 17 from the air blower 29 provided in the bypass line 30 formed in the air line 51 on the downstream side of the air compressor C.
To the cathode Ca of the fuel cell 5,
Further, at the time of startup, the fuel cell power generator is configured to guide the air 17 from the air blower 29 to the startup hot air generator 50 for raising the temperature of the fuel cell 5. Detector 64, an on-off valve 66 which is provided in the middle of the inlet line 65 of the air compressor C and is closed when the fuel cell 5 is started, and a halfway of the inlet line 65 upstream of the on-off valve 66. And an auxiliary suction line 68 connected in the middle of the bypass line 30 on the upstream side of the air blower 29 and provided with a check valve 67 in the middle, and the middle of the bypass line 30 on the downstream side of the air blower 29. A pressure adjustment line 69 that is branched and connected in the middle of the inlet line 65 between the on-off valve 66 and the air compressor C, and provided in the middle of the pressure adjustment line 69; Based on the pressure values detected by the serial pressure detector 64, it is characterized in that the pressure value is a pressure regulating valve 70 that is opening adjusted to be positive.

[0018]

Therefore, when the fuel cell power generator is started, the on-off valve 66 is closed. When the air blower 29 is driven in this state, the air 17 is sucked into the bypass line 30 via the auxiliary suction line 68, and the air blower is turned on. The pressure is increased by 29 and sent to the hot-air generating furnace 50 for activation. The pressure detector 64 detects the pressure at the outlet side of the air compressor C. Based on the detected pressure value, the opening of the pressure regulating valve 70 is determined. In the event that the pressure on the outlet side of the air compressor C becomes a negative pressure, the opening of the pressure regulating valve 70 becomes large, and the air 17 pressure-fed from the air blower 29 becomes large.
Is introduced from the pressure adjustment line 69 to the inlet side of the air compressor C, whereby the pressure on the outlet side of the air compressor C of the turbine compressor 21 is always maintained at a positive pressure. The lubricating oil of the shaft does not leak to the outlet side of the air compressor C, and the lubricating oil leaked with the air 17 is not introduced into the fuel cell 5 even if the operation shifts to the steady operation after the start.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
The same reference numerals as in FIG. 2 denote the same parts, and the basic configuration is the same as the conventional one shown in FIG. 2, but the feature of this embodiment is shown in FIG. as,
A pressure detector 64 for detecting the pressure on the outlet side of the air compressor C is provided in the middle of the air line 51, and an on-off valve 66 which is closed when the fuel cell 5 is started is provided in the middle of the inlet line 65 of the air compressor C. An auxiliary suction line 68 is formed which branches off from the middle of the inlet line 65 upstream of the on-off valve 66 and is connected to the middle of the bypass line 30 upstream of the air blower 29. A stop valve 67 is provided, and a pressure adjusting line 69 that branches off from the middle of the bypass line 30 downstream of the air blower 29 and is connected to the middle of the inlet line 65 between the on-off valve 66 and the air compressor C is provided. A pressure regulating valve 70 is provided in the middle of the pressure regulating line 69 so as to adjust the opening so that the pressure value becomes a positive pressure based on the pressure value detected by the pressure detector 64. Located in.

With the above-described structure, when the fuel cell power generator is started, the on-off valve 66 is closed. When the air blower 29 is driven in this state, the auxiliary suction line is moved from the inlet line 65 on the upstream side of the on-off valve 66. The air 17 is sucked into the bypass line 30 through 68, pressurized by the air blower 29, sent to the hot air generator 50 for startup through the hot air generator air line 52, and compressed by the pressure detector 64. The outlet pressure of the compressor C is detected, the opening of the pressure regulating valve 70 is adjusted based on the detected pressure value, and the outlet pressure of the air compressor C becomes negative pressure , The opening degree of the pressure regulating valve 70 becomes large, and a part of the air 17 pressure-fed from the air blower 29 is introduced from the pressure regulating line 69 to the inlet side of the air compressor C. Outlet side pressure of the air compressor C of the turbine compressor 21 is kept at the positive pressure, the lubricating oil of the axis of the turbine compressor 21 does not leak to the outlet side of the air compressor C,
Even after the startup, the operation shifts to the steady operation, and the lubricating oil leaked together with the air 17 is not introduced into the fuel cell 5.

Thus, when the fuel cell power generator is started,
The pressure on the outlet side of the air compressor C of the turbine compressor 21 becomes negative pressure, and it is possible to prevent the lubricating oil of the shaft of the turbine compressor 21 from leaking to the outlet side of the air compressor C. Even when the operation shifts to operation, the lubricating oil is supplied with the fuel
Can be avoided, and the performance and life of the fuel cell 5 can be prevented from being reduced by the sulfur content in the lubricating oil.

It should be noted that the fuel cell power generator of the present invention is not limited to the above-described embodiment, but may be variously modified without departing from the gist of the present invention.

[0024]

As described above, according to the fuel cell power generator of the present invention, the pressure on the outlet side of the air compressor C of the turbine compressor 21 becomes negative at the time of start-up, and the turbine compressor 2
It is possible to prevent the lubricating oil of the shaft 1 from leaking to the outlet side of the air compressor C.
It is possible to prevent the lubricating oil from being introduced into the fuel cell 5 together with the fuel cell 5, and to prevent the performance and life of the fuel cell 5 from being lowered by the sulfur content in the lubricating oil. .

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Anode gas 3 Reformer 4 Cathode gas 5 Fuel cell 9 Cathode exhaust gas 17 Air 21 Turbine compressor 23 Steam 26 Raw material gas 27 Raw material blower 29 Air blower 30 Bypass line 50 Hot air generator 51 for starting 51 Air line 64 Pressure Detector 65 Inlet line 66 Open / close valve 67 Check valve 68 Auxiliary suction line 69 Pressure adjustment line 70 Pressure adjustment valve An Anode Ca Cathode Re Reforming chamber T Turbine C Air compressor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/04 H01M 8/06

Claims (1)

(57) [Claims] 1. A fuel gas (1) obtained by adding steam (23) to a raw material gas (26) from a raw material blower (27) during a steady operation is led to a reforming chamber (Re) of a reformer (3). Anode gas (2) containing reformed hydrogen is supplied to the anode (An) of the fuel cell (5) and the cathode gas (4) is supplied to the cathode (Ca) of the fuel cell (5) Then, the cathode exhaust gas (9) from the cathode (Ca) is led to the turbine (T) of the turbine compressor (21), and the air from the air compressor (C) in the turbine compressor (21) is generated. (17) and an air blower (2) provided in a bypass line (30) formed in an air line (51) downstream of the air compressor (C).
The air (17) from the air blower (9) is supplied to the cathode (Ca) of the fuel cell (5), and the air (17) from the air blower (29) is supplied at the time of startup.
A fuel cell power generator for guiding a heating hot air generating furnace (50) for temperature rise, comprising: a pressure detector (64) for detecting a pressure at an outlet side of an air compressor (C); An on-off valve (66) which is provided in the middle of the inlet line (65) of the machine (C) and is closed when the fuel cell (5) is started; and an inlet line (6) upstream of the on-off valve (66).
5) The auxiliary suction line (6) which branches off in the middle and is connected in the middle of the bypass line (30) upstream of the air blower (29) and in which a check valve (67) is provided in the middle.
8) and branching from the midpoint of the bypass line (30) downstream of the air blower (29) to the midpoint of the entry line (65) between the on-off valve (66) and the air compressor (C). A pressure adjusting line (69) connected to the pressure adjusting line (69), and opened so that the pressure value becomes a positive pressure based on the pressure value detected by the pressure detector (64). Pressure control valve (70) to be adjusted
And a fuel cell power generator.