JPH0729582A - Fuel cell power generating system - Google Patents

Abstract

PURPOSE:To decrease the capacity of an air compressor in a system and power used by supplying part of air in an air line to a cathode circulation line through a circulation blower bearing. CONSTITUTION:Pressure of a cathode gas 3 circulating with a circulation blower 23 is 1-20kg/cm<2>, and the pressure of an air line 14 is also the same level as the cathode gas pressure. The air pressure is slightly increased than the pressure in the blower 23 to supply cooling air from the air line 14. The air used to cool the bearing of the blower 23 is mixed with the cathode gas 3, and the gas 23 mixed with the air is supplied to a cathode. The capacity of a compressor in a system is almost halved, the compact compressor is realized, and the power for the compressor is decreased half or less. Since the amount of air supplied to cool the bearing of the blower 23 is increased, the load of the compressor in the air line 14 is increased. Increase in output caused by increase in the air amount is small compared with the total output of the compressor, and increase in the output is smaller than decrease in the output of the compressor, and efficiency of the whole system is enhanced.

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 having a circulation blower in a cathode gas circulation line.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have characteristics that conventional power generators do not have, such as high efficiency and little impact on the environment. Collected, and researches are now underway all over the world.

FIG. 2 is a diagram showing an example of power generation equipment using a molten carbonate fuel cell using natural gas as a fuel. In the figure, the power generation facility includes a reformer 10 for reforming a fuel gas 1 obtained by mixing natural gas and water vapor into an anode gas 2 containing hydrogen, a cathode gas 3 containing oxygen, and an anode gas 2.
And a fuel cell 20 for generating electricity from the fuel cell 20. The anode gas 2 produced in the reformer 10 is supplied to the fuel cell 20, and most of it is consumed in the fuel cell 20 to become the anode exhaust gas 4. It is supplied to the combustion chamber Co of the reformer 10 as a combustion gas.

In the reformer 10, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 4 are combusted in a combustion chamber to generate high temperature combustion gas, and the high temperature combustion gas is used to reform the reformer 10. Is heated to reform the fuel gas 1 passing through the reformer 10. The combustion exhaust gas 5 exiting the reformer 10 merges with the air 6 and enters the cathode circulation line 21, where the cathode gas 3
The cathode gas 3 partially reacts in the fuel cell 20 to become the high-temperature cathode exhaust gas 7, and after the power is recovered by the turbine compressor 40 that compresses the air 6, the exhaust heat recovery steam not shown is further generated. The power is recovered by the device and discharged to the outside of the system.

A circulation blower 23 driven by an electric motor is provided in the cathode circulation line 21 to circulate the cathode gas 3. The temperature of the cathode gas 3 is 50
Since the temperature is 0 to 600 ° C., the temperature of the circulation blower 23 itself becomes considerably high. Therefore, it is necessary to cool the bearing portion and prevent seizure. FIG. 3 is a diagram showing an example of the circulation blower 23. This figure shows a single-stage blower, but the single-stage blower is advantageous in terms of sealing because there is only one shaft penetration. Reference numeral 60 denotes an impeller, which rotates integrally with the shaft 61. 62 is a bearing 2
The shaft 61 is supported at a point. Reference numeral 63 denotes an annular air supply passage for supplying air from openings 64 provided at a constant pitch to cool the air. Reference numeral 65 denotes a gap between the shaft 61 and the air that has cooled the bearing 62 enters the passenger compartment 66 through the gap 65 and mixes with the cathode gas 3. A mechanical seal 67 prevents the cathode gas 3 and the supplied air from leaking.

In the case of the circulation blower 23, air is used as the cooling gas. Therefore, conventionally, the air compressor 50 is provided as shown in FIG. The air compressor 50 often uses a local air compressor 50 that controls a valve or the like. Normally, about 1 Nm ³ / h of air is required for valve control, but in the case of the circulation blower 23, if the power generation amount of the fuel cell 20 is 40 KW, for example, 60 Nm
^It requires air volume of ³ / h.

[0007]

Therefore, when the cooling air for the circulation blower 23 is supplied from the indoor air compressor 50, about half the capacity of the indoor air compressor 50 is required. Since the in-house compressor 50 performs valve control and the like, it is necessary to maintain the pressure and the flow rate and the like with high accuracy, but it is not necessary to maintain the cooling air with such accuracy.
However, since the control air and the cooling air are supplied by the same compressor, there is a problem in that all control must be performed with the accuracy of the control air. In addition, the indoor air compressor 50
There is also a problem in that the capacity of the plant becomes large, the power used for it also increases, and the plant efficiency decreases.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fuel cell power generator in which the capacity of a domestic air compressor and the power used are reduced.

[0009]

To achieve the above object, a reformer for reforming a fuel gas containing water vapor into an anode gas containing hydrogen, and a fuel cell for generating electricity from a cathode gas containing oxygen and an anode gas. A cathode circulation line that circulates the cathode exhaust gas of the fuel cell to the cathode; a circulation blower that is provided in the cathode circulation line and has a bearing portion that is cooled by air; and an anode exhaust gas of the fuel cell that reforms the reformer. An exhaust line for exhausting the exhaust gas to the combustion chamber, an exhaust gas supply line for supplying air to the cathode circulation line by mixing air with the combustion exhaust gas of the reformer, and an air line for supplying the air to the exhaust gas supply line. In the fuel cell power generator provided, a cooling air line connecting the air line and the circulation blower is provided, and a part of the air in the air line is circulated. And supplies the cathode circulation line through the bearing portion of the blower.

[0010]

The pressure of the cathode gas circulated by the circulation blower is 1 to ² kg / cm ² . On the other hand, since the pressure in the air line is about the same, the cooling air can be supplied from the air line by setting this air pressure to a pressure slightly higher than the pressure in the circulation blower. As a result, the air that has cooled the bearing of the circulation blower is mixed with the cathode gas and becomes cathode gas, which is supplied to the cathode. As a result, the capacity of the on-site compressor is almost halved, and downsizing is possible,
The power used is less than half. Note that the load on the air line compressor increases because the amount of air supplied to the bearing cooling of the circulation blower increases, but the increase in output due to the increasing air amount is small compared to the output of the compressor as a whole. The output is less than the output reduction of the in-house compressor. Therefore, the efficiency of the fuel cell power generator as a whole is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a fuel cell power generator according to the present invention. In this figure, the same parts as those in FIG. 2 are represented by the same reference numerals. The fuel cell power generation facility includes a reformer 10 for reforming a fuel gas 1 containing water vapor into an anode gas 2 containing hydrogen, and a fuel cell 20 generating electricity from the anode gas 2 and a cathode gas 3 containing oxygen. The anode exhaust gas 4 discharged from the fuel cell 20 is supplied to the combustion chamber Co of the reformer 10 through the discharge line 12 and burned, and the combustion exhaust gas 5 passes through the exhaust gas supply line 13 and the cathode circulation line 21 and is discharged from the fuel cell 20. It is supplied to the cathode side C.

In FIG. 1, the fuel gas 1 is a fuel heater 11
After being heated at 1, it is supplied to the reformer 10. The reformer 10 includes a combustion chamber Co that combusts with the anode exhaust gas 4 and the cathode exhaust gas 7 that have exited the fuel cell 20, and a reforming chamber Re that reforms the fuel gas 1 by heat transfer from the combustion chamber Co. The reforming chamber Re is filled with a reforming catalyst, and the combustion chamber C
The fuel gas 1 is reformed into the high-temperature anode gas 2 containing hydrogen by the high-temperature combustion gas generated in o
And is supplied to the fuel cell 20 after cooling. On the other hand, the combustion exhaust gas 5 whose temperature has dropped due to heat radiation is the exhaust gas supply line 1
3 enters the cathode circulation line 21, but is cooled in the exhaust gas supply line 13 by the air preheater 32, and the condenser 3
3 and the steam separator 34 removes water, is pressurized by the low temperature blower 35, is mixed with the air 6, is heated by the air preheater 32, and enters the cathode circulation line 21.

A part of the cathode exhaust gas 7 drives the turbine of the turbine compressor 40 and is supplied to an exhaust heat recovery steam generator (not shown). The air 6 compressed by the turbine compressor 40 passes through the air line 14 and joins with the combustion exhaust gas 5 at the outlet of the low temperature blower 35. The turbine compressor 40 is provided with a bypass line 41 having an electric blower 42, and works as a backup when the capacity of the turbine compressor 40 is insufficient.

The fuel cell 20 comprises an anode side A through which the anode gas 2 passes and a cathode side C through which the cathode gas 3 passes. Hydrogen and carbon monoxide in the anode gas 2 and oxygen in the cathode gas 3 are contained in the fuel cell 20. , Generates electricity by a chemical reaction with carbon dioxide. The fuel cell 20 includes a storage container 22.
It is stored inside and prevents flammable gas from leaking to the outside to enhance safety.

A part of the cathode exhaust gas 7 is a part of the air preheater 3.
It is mixed with the combustion exhaust gas 5 and air 6 heated in 2, and is supplied to the cathode through the cathode circulation line 21. The cathode circulation line 21 circulates the cathode gas 3 by a circulation blower 23.

The cooling air line 43 connecting the air line 14 and the circulation blower 23 supplies the air 6 to the circulation blower 23. In the circulation blower 23, as shown in FIG. 3, the cooling air first enters the air supply passage 63 and is discharged from the openings 64 provided in the periphery to cool the bearing 62. After cooling the bearing 62, it passes through the gap 65, enters the compartment 66, mixes with the cathode gas 3 and enters the cathode, and supplies oxygen necessary for the cell reaction.

[0017]

As is apparent from the above description, according to the present invention, the cooling air for the bearing of the circulation blower is supplied from a part of the air supplied to the cathode circulation line so as to be supplied from the on-site compressor. Since it is not necessary, the capacity and power consumption of the on-site compressor can be greatly reduced, and the efficiency of the entire plant is improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel cell power generator according to the present invention.

FIG. 2 is an overall configuration diagram of a conventional fuel cell power generator.

FIG. 3 is an illustration of air-cooling a bearing of a circulation blower.

[Explanation of symbols]

 1 Fuel Gas 2 Anode Gas 3 Cathode Gas 4 Anode Exhaust Gas 5 Combustion Exhaust Gas 6 Air 7 Cathode Exhaust Gas 10 Reformer 11 Fuel Heater 12 Exhaust Line 13 Exhaust Gas Supply Line 14 Air Line 20 Fuel Cell 21 Cathode Circulation Line 22 Containment Vessel 23 Circulation Blower 32 Air preheater 33 Condenser 34 Steam separator 35 Low temperature blower 40 Turbine compressor 41 Bypass line 42 Electric blower 43 Cooling air line 60 Impeller 61 Shaft 62 Bearing 63 Air supply path 64 Opening 65 Gap 66 Vehicle compartment 67 Mechanical Seal Re Reforming chamber Co Combustion chamber A Anode side C Cathode side

Claims (1)

[Claims] 1. A reformer for reforming a fuel gas containing water vapor into an anode gas containing hydrogen, a fuel cell for generating electricity from a cathode gas containing oxygen and an anode gas, and a cathode exhaust gas of the fuel cell as a cathode. A circulating cathode circulation line, a circulating blower provided in the cathode circulating line and having a bearing portion cooled by air, an exhaust line for exhausting the anode exhaust gas of the fuel cell to the combustion chamber of the reformer, A fuel cell power generator comprising: an exhaust gas supply line that mixes air with a combustion exhaust gas of a reformer and supplies the air to the cathode circulation line; and an air line that supplies the air to the exhaust gas supply line. And a cooling air line connecting the circulating blower and a part of the air in the air line through the bearing portion of the circulating blower. Fuel cell power generation apparatus characterized by being adapted to supply to the down.