JP3137147B2 - Control method for turbine compressor device for fuel cell facility - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a turbine compressor driven by high-temperature exhaust gas from a fuel cell power generation system.

[0002]

2. Description of the Related Art In systems that require compressed air and discharge high-temperature exhaust gas, such as a molten carbonate fuel cell power generation system or a solid electrolyte fuel cell power generation system,
A turbine-compressor device comprising a turbine driven by hot exhaust gases from the system and a compressor mechanically coupled to the turbine is commonly used.

[0003] Such a turbine / compressor device has, for example, a configuration as shown in FIG. In this figure, 31 is an air intake line, 32 is an air intake valve, 33
Is an air compressor (compressor), 34 is an exhaust gas turbine (turbine), 35 is a speed reducer, 36 is a generator, 37 is an air amount control valve, 38 is an air release valve, 39 is a fuel cell power generation system (power generation system), 40 is an exhaust gas pipe, 41 is an auxiliary combustor, 42 is a fuel control valve, 43 is a fuel pipe, 44 is an exhaust gas pipe, and 45 is a waste heat boiler.

In the above-mentioned turbine / compressor apparatus, a turbine 34 is driven by high-temperature exhaust gas from an exhaust gas pipe 40 serving as an exhaust gas inlet line. Is supplied to the power generation system 39. That is, the basic functions of the turbine compressor device are to supply compressed air required by the power generation system 39 and to recover the surplus output of the turbine 34 in the form of power generation.

When the power generation system 39 is operated at a load of 100%, the turbine compressor is operated with the air intake valve 32 and the air amount control valve 37 fully opened and the air release valve 38 and the fuel control valve 42 fully closed. When the apparatus is operated, all the air generated by the compressor 33 is supplied to the power generation system 39, and the exhaust gas from the power generation system 39 is supplied to the turbine 34 without burning the fuel in the auxiliary combustor 41. In this case, the gas supplied to the turbine 34 is at a high temperature (for example, 700 ° C. or higher), the output of the turbine 34 exceeds the driving force of the compressor 33, and the surplus output is recovered by the generator 36. In addition, the temperature of the gas exiting the turbine 34 is high, and high-temperature superheated steam can be generated by the exhaust heat boiler 45. This superheated steam can be supplied to the power generation system 39 and used for reforming the fuel.

When the power generation system 39 operates at a partial load, the air intake valve 32 reduces the amount of intake air of the compressor 33, and the air amount control valve 37 supplies the air required for the power generation system 39 to the power generation system 39. The supplied excess air is supplied to the auxiliary combustor 41 through the air relief valve 38. In this case, the temperature of the mixed gas of the exhaust gas from the power generation system 39 and the excess air becomes low, so that the output of the turbine 34 decreases, and the compressor 33 cannot be driven. Therefore, in the conventional apparatus, fuel is supplied to the auxiliary combustor 41 via the fuel control valve 42, and the temperature of the mixed gas is increased by burning the fuel. in this case,
In order to minimize the decrease in plant efficiency due to the use of fuel, it has been proposed to reduce the fuel to the minimum that can drive the compressor 33 by the output of the turbine 34 and control the generator output to be almost zero. (JP-A-3-286150).

[0007]

However, in the method of controlling the turbine / compressor device at the time of partial load described above,
At partial load, it was found that a substantial amount of supplementary fuel was still required. Although the heat generated by the auxiliary fuel is recovered by the turbine and the exhaust gas boiler, the thermal efficiency is extremely low (for example, 10% or less) as compared with the power generation system. Was.

Further, the combustion of fuel by the auxiliary combustor is a normal combustion accompanied by a high-temperature flame.
Since Ox is generated, there is a problem that the low pollution characteristics of the power generation system are hindered. The present invention has been made to solve such a problem. That is, the object of the present invention is:
It is an object of the present invention to provide a control method of a turbine / compressor device capable of improving the plant efficiency of a fuel cell system and reducing the amount of generated NOx by further reducing the amount of auxiliary fuel used.

[0009]

According to the present invention, there is provided a fuel cell power generation system for generating electricity by a chemical reaction between compressed air and fuel to discharge high-temperature exhaust gas, and using exhaust gas from the fuel cell power generation system. A driven turbine, a compressor mechanically connected to the turbine, a generator / motor electrically connected to the turbine, an auxiliary combustor provided in an exhaust gas inlet line of the turbine, and the auxiliary combustion A fuel control valve for controlling the amount of fuel supplied to the fuel cell, detecting the temperature of the exhaust gas exiting the turbine at a partial load when the amount of compressed air supplied to the fuel cell power generation system is reduced; Supplying fuel to the auxiliary combustor so that the temperature is equal to or higher than a predetermined temperature, and when the output of the turbine is low, the compressor maintains a predetermined rotation speed. Driving the turbine by electrodeposition, the electric motor, characterized in that.

According to a preferred embodiment of the present invention, compressed air is generated by a compressor, and a necessary amount of the generated compressed air in the fuel cell power generation system is supplied to the fuel cell power generation system, and excess compressed air is supplied to the fuel cell power generation system. To the auxiliary combustor. Further, it is preferable that exhaust gas leaving the turbine is supplied to an exhaust heat boiler, high-temperature steam is generated by the exhaust heat boiler, and the steam is supplied to the fuel cell power generation system.

[0011]

According to the method of the present invention, when the system is partially loaded, the temperature of exhaust gas exiting the turbine is detected, and fuel is supplied to the auxiliary combustor so that the temperature is equal to or higher than a predetermined temperature. The amount of fuel used in the auxiliary combustor can be minimized while maintaining the temperature of steam generated by the heat boiler in a desired range. In particular, when the output of the turbine is low, the turbine is driven by the generator / motor so that the compressor maintains the predetermined rotation speed.
The amount of fuel used can be further reduced as compared with a case where the fuel is throttled to the minimum that can drive the compressor by the output of the turbine.

Therefore, according to this method, since the efficiency of the power generation / motor is much higher than the heat recovery efficiency of the auxiliary fuel (10% or less), a part of the electricity generated by the power generation system is generated. , The plant efficiency of the entire fuel cell facility can be increased. Also, by reducing the amount of auxiliary fuel used, the amount of NOx generated by fuel combustion can be reduced, and the low pollution characteristics of the fuel cell system can be maintained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method according to the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a turbine compressor device for a fuel cell facility for carrying out the method of the present invention. In this figure, the turbine compressor device includes a system 9 that requires compressed air and discharges high-temperature exhaust gas. This system 9 is preferably a power generation system such as a molten carbonate fuel cell power generation system or a solid oxide fuel cell power generation system. Such a power generation system includes, for example, a reformer, a heat exchanger, a blower, a steam-water separator, and the like, generates electricity by a chemical reaction from the supplied compressed air and fuel, and discharges high-temperature exhaust gas. ing.

Further, the turbine-compressor unit includes a turbine 4 driven by exhaust gas from the system 9, a compressor 3 mechanically connected to the turbine 4, and a generator / motor 6 mechanically connected to the turbine 4. And an auxiliary combustor 11 provided in an exhaust gas inlet line 10 of the turbine 4.
And a fuel control valve 12 for controlling the amount of fuel supplied to the auxiliary combustor 11. The generator / motor 6 has both functions of a generator and a motor. That is, power can be generated by the output of the turbine 4 like a normal power generator, and conversely, the turbine 4 can be driven by supplying power. Note that such a function is provided in a normal generator and electric motor as it is. The auxiliary combustor 1
1 is a normal burner for burning gas fuel or liquid fuel.

As shown in FIG. 1, the turbine compressor apparatus further includes an air intake line 1, an air intake valve 2, a speed reducer 5, an air flow control valve 7, an air release valve 8, and a fuel pipe 1.
3, an exhaust heat boiler 14, an exhaust gas line 15, a load control device 16, an exhaust gas temperature detector 17, a water supply line 18, a steam line 19, flow controllers 20, 22, and a pressure controller 21. As shown, the compressor 3, the turbine 4, the speed reducer 5, and the generator / motor 6 are mechanically connected. The air flow control valve 7 controls the air flow to the system 9 and, although not shown, usually has a plurality of lines.

When the system 9 is operated at 100% load, the turbine inlet and the air amount control valve 7 are fully opened, and the air release valve 8 and the fuel control valve 12 are fully closed.
The compressor device is operated, all the air generated by the compressor 3 is supplied to the system 9, and the exhaust gas from the system 9 is supplied to the turbine 4 without burning the fuel in the auxiliary combustor 11. In this case, the turbine 4
Is high temperature (for example, 700 ° C. or higher), the output of the turbine 4 exceeds the driving force of the compressor 3, and the surplus output is collected by the generator / motor 6.
Further, the temperature of the gas leaving the turbine 4 is high, and high-temperature superheated steam (for example, 450 ° C. or more) can be generated by the exhaust heat boiler 14.
And used for fuel reforming.

When the system 9 operates at a partial load, the air intake valve 2 reduces the intake air amount of the compressor 3, and the air amount control valve 7 supplies an amount of air necessary for the system 9 to the system 9. Excess air is supplied to the auxiliary combustor 11 through the air relief valve 8. In this case, the temperature of the mixed gas of the exhaust gas and the excess air from the system 9 decreases, the output of the turbine 4 decreases, and the compressor 3 cannot be driven. Therefore, the fuel control valve 1
The fuel is supplied to the auxiliary combustor 11 through 2 and the temperature of the mixed gas is increased by burning the fuel. In this case, according to the present invention, the temperature of the exhaust gas leaving the turbine 4 is detected by the exhaust gas temperature detector 17, and the fuel supplied to the auxiliary combustor 11 by the fuel control valve 12 so that this temperature is equal to or higher than a predetermined temperature. Control the amount of. At the same time, the generator / motor 6 is also used as a motor, and when the output of the turbine 4 is low despite the high temperature of the exhaust gas leaving the turbine 4,
The turbine is driven by the generator / motor 6 so that the compressor 3 maintains a predetermined rotation speed.

The above-mentioned predetermined temperature of the exhaust gas leaving the turbine 4 is preferably set to a sufficiently high temperature, for example, 475 ° C. or higher. As a result, high-temperature superheated steam (for example, 450 ° C.) can be generated by the exhaust heat boiler 14, and the superheated steam can be supplied to the system 9 and used for reforming fuel.

According to the method of the present invention described above, when the system is partially loaded, the temperature of the exhaust gas exiting the turbine is detected, and the auxiliary combustor is supplied with fuel so that the temperature is equal to or higher than a predetermined temperature. The amount of fuel used in the auxiliary combustor can be minimized while keeping the temperature of the steam generated by the exhaust heat boiler in a desired range. In particular, when the output of the turbine is low, the turbine is driven by the generator / motor so that the compressor maintains the predetermined rotation speed, so that the fuel is throttled to the minimum that can drive the compressor by the output of the turbine. The fuel consumption can be further reduced.

Therefore, according to this method, since the efficiency of the power generation / motor is much higher than the heat recovery efficiency of the auxiliary fuel (10% or less), a part of the electricity generated by the power generation system is generated. , The plant efficiency of the entire fuel cell facility can be increased. Also, by reducing the amount of auxiliary fuel used, the amount of NOx generated by fuel combustion can be reduced, and the low pollution characteristics of the fuel cell system can be maintained.

[0021]

In summary, according to the present invention, the amount of auxiliary fuel used can be further reduced, thereby increasing the plant efficiency of fuel cell equipment and reducing the amount of NOx generated.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a turbine compressor device for a fuel cell facility for carrying out a method of the present invention.

FIG. 2 is an overall configuration diagram of a conventional turbine / compressor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air intake line 2 Air intake valve 3 Compressor 4 Turbine 5 Reduction gear 6 Generator / motor 7 Air flow control valve 8 Air release valve 9 System 10 Exhaust gas inlet line 11 Auxiliary combustor 12 Fuel control valve 13 Fuel pipe 14 Exhaust heat boiler 15 Exhaust gas line 16 Load control device 17 Exhaust gas temperature detector 18 Water supply line 19 Steam line 20, 22 Flow controller 21 Pressure controller

Claims (3)

(57) [Claims] 1. Electricity is generated by a chemical reaction between compressed air and fuel.
Power was provided with a fuel cell power generation system for discharging hot exhaust gas, and a turbine driven by exhaust gas from the fuel cell power generation system, a compressor which is mechanically coupled to the turbine, mechanically coupled to the turbine And a fuel control valve for controlling the amount of fuel supplied to the auxiliary combustor , the compression to the fuel cell power generation system. Air supply reduced
During the partial load, the temperature of exhaust gas exiting the turbine is detected, fuel is supplied to the auxiliary combustor so that the temperature is equal to or higher than a predetermined temperature, and when the output of the turbine is low, the compressor Driving the turbine by the generator / motor so as to maintain the rotation speed of
A method for controlling a turbine / compressor device for a fuel cell facility, comprising: Wherein to generate the compressed air by the compressor, the amount required by the fuel cell power generation system of the compressed air generated is supplied to the fuel cell power generation system supplies the excess compressed air to the auxiliary burner, The method for controlling a turbine / compressor device for a fuel cell facility according to claim 1, wherein: 3. The exhaust gas leaving the turbine is supplied to an exhaust heat boiler, the exhaust heat boiler generates high-temperature steam, and the steam is supplied to the fuel cell power generation system. The control method of the turbine compressor device for fuel cell equipment according to the above.