JPH0579813B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention utilizes waste heat energy from a fuel cell main body to drive a turbine of a turbo compressor, and extracts energy from the compressor of the turbo compressor to the fuel cell main body. The present invention relates to a fuel cell power generation system that supplies compressed air necessary for.

[Conventional technology]

As is well known, a fuel cell power generation system includes a fuel cell main body consisting of an air electrode, a fuel electrode, and an electrolyte layer, and a reformer that reforms hydrocarbon fuel such as natural gas and supplies it to the fuel cell main body. The fuel cell main body includes a fuel cell main body and a compressor that supplies compressed air to the fuel cell main body.

The performance of this fuel cell main body tends to improve as the pressure of the reaction gas consisting of the above-mentioned reformed fuel and air increases, so the operating pressure of the above-mentioned reaction gas is increased to about 4 to 6 kg/ ^cm2. It is necessary to pressurize and maintain the

In order to obtain this pressure of the reaction gas, air must be compressed, which requires a large amount of energy, so in order to cool the combustion exhaust gas from the reformer and the fuel cell main body Thermal efficiency is improved by supplying surplus steam from the cooling water of the fuel cell and surplus air from the air electrode of the fuel cell main body to the turbine of the turbo compressor.

In such a fuel cell power generation system, the pressure of the compressed air supplied to the fuel cell main body is determined from the viewpoint of maintaining the characteristics of the fuel cell main body, and suppressing the differential pressure between the cell fuel and the pressure, preventing gas leakage between the two electrodes. That is, in order to prevent a crossover phenomenon, control is required to maintain a constant value.

As a specific conventional method, for example,
There is something proposed in Publication No. 61-80765,
The schematic configuration is shown in FIG. 2.

In the figure, 1 is a fuel cell main body including a reformer, etc., 2 is a turbine 2a that is driven by exhaust gas from the fuel cell main body 1 and supplies the compressed air necessary for the fuel cell main body 1, and this turbine 2a. A turbo compressor consisting of a compressor 2b arranged coaxially with a turbo compressor, 3 an air supply pipe installed on the outlet side of the compressor 2b for supplying air from the compressor 2b to the fuel cell main body 1, 4 an air supply pipe for supplying the air from the compressor 2b to the fuel cell main body 1; Compressor 2 installed in supply piping 3
5 is an exhaust gas pipe that guides the exhaust gas from the fuel cell main body 1 to the turbine 2a; 6 is an auxiliary pipe installed in the middle of the exhaust gas pipe 5 to compensate for the lack of turbine power; combustor,
7 is a fuel pipe that supplies fuel to the auxiliary combustor 6; 8 is a flow control valve installed in the fuel pipe 7; 9 is a fuel flow rate control valve that detects the flow rate of fuel flowing through the fuel pipe 7 and adjusts the flow rate control valve 8; 10 is an air pipe branched from the air supply pipe 3 and connected to the auxiliary combustor 6; 11 is a flow control valve installed in the air pipe 10; 12 is the air pipe 1;
The flow rate control valve 12 detects the air flow rate flowing through the
13 is a pressure controller that provides a control signal to the flow rate controller 9 and the flow rate controller 12 in accordance with the discharge air pressure of the compressor 2b detected by the pressure detector 4.

To explain the operation of the conventional fuel cell power generation system configured as described above, normally in such a fuel cell power generation system, the turbine power is equal to or even insufficient than the power required for the compressor.

This lack of turbine power is particularly noticeable at partial loads, so the auxiliary combustor 6 is installed to compensate for this lack of turbine power. If the pressure decreases, or if the discharge air pressure of the compressor 2b fluctuates due to changes in the supply air flow rate to the fuel cell main body 1, changes in the exhaust gas flow rate/temperature, changes in the suction conditions of the compressor 2b, etc., the pressure By controlling the combustion amount of the auxiliary combustor 6 through the flow rate controllers 9 and 12 so that the pressure detected by the pressure detector 4 becomes a constant target value, the controller 13 compensates for the deficit in turbine power and discharges. The air pressure is kept constant.

As a result, stable compressed air is supplied to the fuel cell main body, and crossover can be prevented by suppressing the pressure difference between the compressed air and the cell fuel.

[Problem to be solved by the invention]

Conventional fuel cell power generation systems configured as described above not only have a large number of control valves and controllers, making the configuration complex, but also require fast response control of the compressed air pressure supplied to the fuel cell main body. In addition, only a portion of the combustion energy from the auxiliary combustor is recovered as turbine power, resulting in a reduction in overall thermal efficiency.

This invention has a simple configuration and good control responsiveness.
Moreover, the purpose is to obtain an efficient fuel cell power generation system.

[Means to solve the problem]

As shown in the basic embodiment shown in FIG. 1, a turbine 2a is driven by exhaust gas from the fuel cell main body 1, and a compressor is directly connected to and driven by this turbine and supplies compressed air to the fuel cell main body. 2b, the compressed air supply device 14 supplies compressed air controlled so that the supply pressure from the compressor 2b to the fuel cell main body 1 is a predetermined value. The above compressor 2
It is characterized by being provided on the inlet side piping of b.

[Effect]

In a fuel cell power generation system, only the exhaust gas from the fuel cell main body 1 is used to generate the turbo compressor 2.
When driving the turbine 2a, the exhaust gas normally does not provide sufficient driving force for the turbine, so the supply pressure of compressed air from the compressor 2b to the fuel cell main body 1 is insufficient.

According to the present invention, the compressed air supply device 14, such as a blower or an electric compressor, provided on the inlet side of the compressor 2b of the turbo compressor 2 increases the pressure of the air on the outlet side of this device 14. Not only can it compensate for the lack of supply pressure of compressed air supplied to section 1, but also
By controlling the pressure on the outlet side, the compressed air supply pressure to the fuel cell main body 1 can be quickly controlled.

〔Example〕

In the basic embodiment shown in FIG. 1, a fuel cell main body 1, a turbine 2a and a compressor 2b
including a turbo compressor 2, air supply piping 3,
Since the pressure detector 4 for detecting the air pressure in the air supply pipe 3 and the exhaust gas pipe 5 are the same as those described for the conventional example shown in FIG. 2, a detailed description thereof will be omitted.

The compressed air supply device 14 provided on the inlet side of the compressor 2b of the turbo compressor 2 according to the present invention may be, for example, a blower, an electric compressor, or the like.

The pressure of the compressed air in the supply air pipe 3 from the compressor 2b to the fuel cell main body 1 is detected by the pressure detector 4, and is detected by the pressure controller 15.
The pressure is compared with the pressure set value at the step 2, and feedback is sent back to the compressed air supply device 14 so that the error is "0".

As a result, the pressure of the compressed air supplied to the fuel cell main body 1 quickly follows the above pressure setting value, so compared to the case where the auxiliary combustor 6 described in the conventional example is used, the pressure of the compressed air supplied to the fuel cell main body 1 is faster and more stable. Pressure control can be performed.

〔Effect of the invention〕

In the fuel cell power generation system according to the present invention, the supply pressure of the compressed air supplied to the fuel cell main body is quickly controlled by controlling the air pressure on the inlet side of the compeller. This not only simplifies the configuration significantly, but also significantly improves the precision of the pressure of compressed air to the fuel cell main body and the control response speed compared to when an auxiliary combustor is used.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a basic embodiment of a fuel cell power generation system according to the present invention, and FIG. 2 is a schematic diagram of a conventional fuel cell power generation system. 1 is a fuel cell main body, 2 is a turbo compressor, 2a is a turbine, 2b is a compressor, 3 is an air supply pipe, 5 is an exhaust gas pipe, and 14 is a compressed air supply device.

Claims (1)

[Scope of Claims] 1. A fuel comprising a turbo compressor consisting of a turbine driven by exhaust gas from the fuel cell main body and a compressor directly connected to and driven by the turbine to supply compressed air to the fuel cell main body. The battery power generation system is characterized in that a compressed air supply device is provided on the inlet side of the compressor for supplying compressed air controlled so that the supply pressure from the compressor to the fuel cell main body becomes a predetermined value. A fuel cell power generation system.