JP3104316B2 - Fuel cell power generation equipment - 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 generation system.

[0002]

2. Description of the Related Art A conventional molten carbonate fuel cell power generator has, for example, a configuration as shown in FIG.
In FIG. 2, 1 is a raw fuel gas line, 2 is a steam line, 3 is a heat exchanger, 4 is a reformer, 5 is an anode inlet line, 6 is a fuel cell body having an anode A and a cathode C, and 7 is A fuel cell unit including the battery body 6;
8 is an anode outlet line, 9 is a heat exchanger, 10 is a steam separator, 11 is a blower, 12 is a reformer combustion exhaust gas line,
13 is a heat exchanger, 14 is a cathode inlet line, 15 is a cathode outlet line, and 16 is an exhaust gas turbine described later. Reference numeral 18 denotes a turbine exhaust line, 19 denotes an exhaust heat recovery boiler, 20 denotes a water line, 21 a water supply treatment device, 22 denotes a pump, 23 denotes a cathode gas circulation line, 24 denotes a circulation blower, 25 denotes an air compressor described later, and 26 denotes An intake air line, 27 is a compressed air line, 28 is a turbine inlet line, 29 is an auxiliary combustor described later, 30 is an auxiliary fuel supply line, 31 is an auxiliary air line, and 32 is a generator. That is, in the fuel cell power generator shown in FIG. 2, the raw fuel gas is supplied to the system from the raw fuel gas line 1, mixed with the steam supplied from the steam line 2, and preheated through the heat exchanger 3. Thereafter, the gas enters the reformer 4, is reformed into a gas containing H ₂ as a main component, and is sent to the anode electrode of the fuel cell body 6 of the fuel cell unit 7 through the anode inlet line 5. The anode outlet gas contains combustibles and water vapor, is cooled through a heat exchanger 9 provided in the anode outlet line 8, and is separated into steam and water by a steam separator 10. As a result, the gas generates more heat per unit weight,
It becomes easy to burn. The liquid is water.
0, is sent to the exhaust heat recovery boiler 19 through the feed water treatment device 21 and the pump 22 to be turned into steam, and then becomes the raw fuel reforming steam through the steam line 2. If the amount of water is insufficient,
Supply water from outside.

[0004] The exhaust gas turbine 16 drives an air compressor 25 and a generator 32. The air compressor 25 sucks air from an intake air line 26, and discharge air is discharged through a compressed air line 27, a part of which is supplied to a cathode inlet side, and another part is supplied to an auxiliary combustor 29 described later. The others are preheated by the heat exchanger 13 for combustion in the reformer 4 and supplied to the reformer 4. A portion of the cathode outlet gas branches off from the card outlet line 15 and is circulated to the cathode inlet side by a circulation blower 24 to maintain the temperature of the cathode inlet line 14 at a design value and to replenish the CO ₂ component. .

In the exhaust gas turbine 16, a part of the cathode gas from the cathode outlet line 15 reaches the turbine inlet line 28 and is driven by the cathode gas. Of course, at the time of load or low load, the output of the exhaust gas turbine 16 is lower than the required power for driving the air compressor 25 and the generator 32. Auxiliary fuel is supplied to the auxiliary combustor 29 from an auxiliary fuel supply line 30, compressed air is supplied from an auxiliary air line 31 and burned, and the combustion gas is mixed with cathode gas from a cathode outlet line 15 to form a turbine. Exhaust gas turbine 1 from inlet line 28
6 In this way, the driving source gas that is insufficient in the exhaust gas turbine 16 is supplied.

[0006]

However, in the prior art shown in FIG. 2, there is an auxiliary combustor 29 upstream of the exhaust gas turbine 16, which complicates the system and reduces the safety because fire is used. In addition, there was a problem that ignition operation was extinguished and driving operability was poor. Further, the size of the auxiliary combustor 29 is considerably large, and in a fuel cell power plant requiring compactness, there is a problem that the space is consumed, the cost is increased, and the equipment cost is increased. Moreover, the plant thermal efficiency at the time of partial load at the time of ignition of the auxiliary combustor 29 is low, and the energy of the fuel supplied to the auxiliary combustor 29 is recovered as electric energy by the exhaust gas turbine 16, but the thermal efficiency is low due to the thermal cycle. As a result, there is a problem that the partial load efficiency is deteriorated.

[0007] The present invention is to solve the above problems. That is, the present invention provides a fuel cell power generation facility that improves safety and driving operability, enables simplification and compactness of the system, and improves thermal efficiency at full load, particularly at partial load. It is intended for.

[0008]

To achieve the above object, the present invention provides a cathode outlet of a fuel cell unit (7).
By cathode gas supplied directly from line (15)
The driven exhaust gas turbine (16) and the fuel cell unit
Supply air only to the cathode inlet side of the reactor and the reformer (4).
Air compressor (25) to supply, exhaust gas turbine and air
Power generation that is connected to the rotating shaft of the compressor and can be both power generation and electric
And an electric motor (17), and
When the output of the engine falls below the required power,
Electric power is supplied and the electric power is used as an electric motor to compensate for the insufficient power .

[0009]

According to the present invention, since the exhaust gas turbine is connected to a generator / motor capable of both power generation and electric power, the generator / motor is used when the output of the exhaust gas turbine is sufficiently large and the plant is under a high load. When the output of the exhaust gas turbine falls below the required power for driving the air compressor, such as during stoppage, startup, or at no load or at low load, the generator is also used as the generator. Electric power can be supplied to the electric motor and the electric power can be used as the electric motor to make up for the insufficient power of the exhaust gas turbine. Therefore, since the conventional auxiliary combustor can be eliminated, the problem of the conventional technology is solved.

[0010]

FIG. 1 shows an embodiment of the present invention. FIG.
, 1 to 16 and 18 to 28 are
This is the same as that described in FIG. Reference numeral 17 denotes a generator / motor that is capable of both power generation and electric power, and is connected to the exhaust gas turbine 16.

In the fuel cell power generation system configured as shown in FIG. 1, when the output of the exhaust gas turbine 16 becomes sufficiently large and the plant is under a high load, the generator / motor 17
As a generator. Conversely, when the output of the exhaust gas turbine 16 falls below the required power for driving the air compressor 25, such as during stoppage, start-up, no load, or low load, power is supplied to the generator / motor 17. Thus, it can be used as an electric motor to compensate for the power shortage of the exhaust gas turbine 16.

Accordingly, in the fuel cell power generation system configured as shown in FIG. 1, the conventional auxiliary combustor 29 can be eliminated, so that the system is simplified and the equipment accompanied by combustion is provided. Therefore, the safety can be improved, and the space required for the plant can be reduced. In addition, ignition and extinction become unnecessary, and the exhaust gas turbine 16 and the air compressor 2
The starting operation of the system of the motor 5 and the generator / motor 17 becomes easy. In other words, in the conventional system, the operation of the exhaust gas turbine and the air compressor system until the self-sustaining operation is complicated, and the self-sustaining operation point is as high as about 80% load, and when the operation is less than about 80%, auxiliary fuel is used. Since the air compressor had to be operated under conditions corresponding to an unnecessarily high load, the thermal efficiency was low. However, as shown in FIG. The elimination of the auxiliary combustor improves the thermal efficiency, especially at partial load.

In FIG. 1, the gas for driving the exhaust gas turbine 16 is the cathode outlet gas from the cathode outlet line 15. However, as in a certain phosphoric acid type fuel cell power generator, the combustion gas of the reformer 4 is used. A similar effect can be obtained by using a piping configuration in which the line 12 and the turbine inlet line 28 are connected and using the exhaust gas of the reformer 4.

[0014]

As described above, according to the present invention,
An exhaust gas turbine that drives an air compressor that supplies air to the fuel cell power generation system is connected to a generator / motor that can both generate and drive electricity. When the generator / motor is used as a generator to generate power, conversely, when the output of the exhaust gas turbine falls below the required power for driving the air compressor, such as during stop or startup or at no load or at low load. In addition, electric power can be supplied to the electric generator / motor, and the electric power can be used as the electric motor to make up for the insufficient power of the exhaust gas turbine.

Therefore, conventionally, it was necessary to provide an auxiliary combustor on the upstream side of the exhaust gas turbine. However, in the present invention, the need for the auxiliary combustor has been eliminated, the system has been simplified, and the number of devices involved in combustion has been reduced. In addition, safety can be improved, and downsizing and equipment cost can be reduced.
In addition to improving driving operability, full load, especially,
Thermal efficiency at partial load is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a conventional technique.

[Explanation of symbols]

 4: Reformer 15: Cathode outlet line 16: Exhaust gas turbine 17: Generator / motor 25: Air compressor 27: Compressed air line 28: Turbine inlet line

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/00-8/24 F02C 6/00-6/20

Claims (1)

(57) [Claims] 1. A cathode outlet of a fuel cell unit (7)
By cathode gas supplied directly from line (15)
The driven exhaust gas turbine (16) and the fuel cell unit
Supply air only to the cathode inlet side of the reactor and the reformer (4).
Air compressor (25) to supply, exhaust gas turbine and air
Power generation that is connected to the rotating shaft of the compressor and can be both power generation and electric
And an electric motor (17), and
When the output of the engine falls below the required power,
A fuel cell power generation facility that supplies electric power and uses it as an electric motor to compensate for the lack of power .