JPH0960505A - Pressurized fluidized bed combined cycle power plant startup method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent water in exhaust gas from condensing by heating each constitutional equipment, set up from a furnace to a gas turbine, to a dew point temperature or more, at the time of starting a pressure fluidized bed compound generating plant. SOLUTION: High temperature delivery air of a compressor 4, generated by reducing an inlet pressure of the compressor 4 by a compressor inlet throttle valve 15 and increasing compressor pressure ratio, is successively fed to a furnace 2, pipe 24, dust removing device 8 and a gas turbine 5, after each constitutional equipment is heated to a prescribed temperature, a damper valve 9 is closed, a damper valve 10 is opened, an air-heating furnace 7 is started, and a fluid medium 3 is heated. Here, a large amount of water is contained in combustion gas, but each constitutional equipment is preheated by heating air, so as to prevent condensing of water from being generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a pressurized fluidized bed combined cycle power plant.

[0002]

2. Description of the Related Art FIG. 2 shows the configuration of a conventional pressurized fluidized bed combined cycle power plant system. In the figure, the pressurized fluidized bed combined cycle power plant pressurizes the inside of the pressure vessel 1 with the discharge air of the compressor 4, and the fluidized medium (limestone, sand, etc.) 3 stored in the furnace 2 through the air pipe 21. And the steam generated by heating the heat transfer tubes 16 installed in the furnace 2 by fluidized combustion with coal supplied from a fuel supply system (not shown) to drive a steam turbine power generation system (not shown). It generates electricity.

The combustion gas after fluidized combustion in the furnace 2 is
Ashes are removed by the dust remover 8 through the pipe 24, and the pipe 2
The gas turbine 5 is driven via 5 and the generator of the generator / motor 6 generates electric power.

When the pressurized fluidized bed combined cycle power plant is started, the compressor 4 is driven by the electric motor of the generator / motor 6, the compressed air is introduced into the pressure vessel 1, and the damper valve 9 is used. Is closed, the damper valve 10 is opened, and fuel such as light oil supplied from a fuel supply system for a hot stove (not shown) is burned in the hot stove 7, and the combustion gas is passed through the dispersion plate 34. The fluidized medium 3 is heated while flowing. The combustion gas after heating the fluidized medium 3 is discharged from the chimney from the upper part of the furnace 2 through the pipe 24, the dust removing device 8, the pipe 25, the gas turbine 5 and an exhaust heat recovery system (not shown). When the fluidized medium 3 in the furnace 2 reaches the ignition temperature of coal, coal is introduced into the furnace 2 from a fuel supply system (not shown) and burned, and the hot-blast stove 7 is operated at a stage when the combustion is stable. When stopped, the damper valve 9 is opened, the damper valve 10 is closed, the rotation speed of the compressor 4 is gradually increased, the pressure of the compressor discharge air is increased, and the fuel supply amount of coal is increased. When the driving force can be secured by, the generator / motor 6 is switched to the generator to generate electricity.

On the other hand, in the steam turbine power generation system, the amount of generated steam increases because the amount of heat received by the heat transfer tubes 16 increases with the rise of the fluidized medium 3, and the steam is used to drive the steam turbine to generate power. Is.

There is also a known example (for example, Japanese Patent Laid-Open No. 5-264001) in which the combustion gas of the hot blast stove 7 is secondarily used to carry out preheating after the furnace. Even if it contains water, the amount of water is very small and it is usually dry.Therefore, preheating the furnace may cause disadvantages such as increased hot-air stove startup time and increased fuel consumption. is there.

[0007]

In the conventional pressurized fluidized bed combined cycle power generation plant described above, a large amount of water vapor is contained in the combustion gas of the fuel such as light oil in the hot blast stove 7. , The pipe 24, the dedusting device 8, and the pipe 25 are in a cold state, the moisture in the combustion gas is condensed in the initial stage of activation, and then a large amount of ash is contained in the exhaust gas when switching from hot stove combustion to coal combustion. Contained ash is contained in the pipe and the like, and solidified ash generated by the solidification may block the ash extraction pipe of the dust remover 8 or may collide with the gas turbine 5 and damage the gas turbine blade. There is.

As a solution to such a problem caused by the condensation of water in the combustion gas, Japanese Patent Laid-Open No. 5-264001 discloses a heat exchanger that uses air containing no combustion gas at the initial stage of starting the pressurized fluidized bed combined cycle power plant. It has been proposed to preheat each equipment provided between the pressurized fluidized bed boiler and the gas turbine by heating the equipment. However, this method for starting the pressurized fluidized bed combined cycle power generation plant has a problem that a heat source for heating air is separately required only when the plant is started up.

The present invention has been made in view of the above circumstances, and preheats the equipment downstream of the pressurized fluidized bed by generating a preheated gas having a small water content without requiring a special heat source. It is an object of the present invention to provide a method for starting a combined heating and fluidized bed power plant capable of performing the above.

[0010]

A method for starting a pressurized fluidized bed combined cycle power generation plant of the present invention is a combined pressurized fluidized bed combined power generation system that combines a pressurized fluidized bed boiler with a steam turbine power generation system and a gas turbine power generation system. In the power plant starting method, the compressor discharge air temperature is raised by reducing the compressor inlet pressure by a throttle valve provided at the compressor inlet for sending compressed air to the pressurized fluidized bed boiler, and the steam content is increased. It is characterized in that the exhaust gas system is preheated to a dew point temperature or higher before passing the combustion gas containing a large amount of the exhaust gas to the exhaust gas system.

A method for starting a pressurized fluidized bed combined cycle power plant according to the present invention is a method for starting up a pressurized fluidized bed combined cycle power plant for generating power by combining a pressurized fluidized bed boiler with a steam turbine power generation system and a gas turbine power generation system. In, the compressor discharge air temperature is raised by reducing the compressor inlet pressure by a throttle valve provided at the compressor inlet for sending compressed air to the pressurized fluidized bed boiler, and the compressor discharge air is It is characterized in that the exhaust gas system is preheated to a dew point temperature or higher before the combustion gas having a large amount of water vapor is passed through the exhaust gas system by exchanging heat with the heat exchanger to raise the temperature of the air flowing into the boiler.

[0012]

In the method of starting the pressurized fluidized bed combined cycle power plant having the above structure, the pressure vessel 1 constituting the pressurized fluidized bed boiler and each component of the exhaust gas system from the furnace 2 to the gas turbine 5 are preheated with air. Since it is heated above the dew point temperature at which water does not condense, it is possible to prevent the water from condensing even when the combustion gas containing a large amount of water is passed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an example of a pressurized fluidized bed combined cycle power generation plant to which the present invention is applied.

In the method for starting the pressurized fluidized bed combined cycle power plant according to this embodiment, the exhaust gas system from the furnace 2 in the cold state to the gas turbine 5 is preheated prior to the fuel injection into the hot stove 7. It is to prevent water from condensing on each component in the boiler exhaust gas system. That is, by providing the compressor inlet throttle valve 15 on the upstream side of the compressor 4 to reduce the compressor inlet pressure, the compressor pressure ratio is increased,
The compressor discharge air temperature is raised, and the high temperature air (for example, 200 to 300 ° C.) heats the furnace 2, the pipe 24, the dust removing device 8, and the pipe 25.

The principle of the present invention is based on the compressor discharge temperature characteristic according to the compressor pressure ratio shown in FIG. Compressor discharge pressure is approximately 1.5k in the initial stage of startup of a pressurized fluidized bed combined cycle power plant
Since it is about g / cm ³ · a and the compressor pressure ratio is about 1.5, the compressor discharge temperature is low and cannot be used for pipe preheating. Therefore, by reducing the compressor inlet pressure by the compressor inlet throttle valve 15, it is possible to apparently increase the compressor pressure ratio and obtain hot air. However, by reducing the compressor inlet pressure, the compressor inlet temperature decreases and the discharge temperature does not rise so much. As a preventive measure against this, the air in the intermediate stage of the compressor is rectified in the pipe 17 not shown. The compressor discharge temperature can be raised by bleeding to the section.

In the above structure, when the pressurized fluidized bed combined cycle power plant is started, the valves 12 and 14 are closed and the valve 13 is opened.
The compressor 4 and the gas turbine 5 are started by the electric motor of the generator / motor 6, and the speed is increased to the rated speed. After the rotation is stabilized, the valve 12 and the damper valve 9 are opened, hot air is passed while pressurizing the pressure vessel 1, and the furnace 2, the pipe 24, the dust removing device 8 and the pipe 25 are heated. After opening the valve 12, the valve 14 is opened with a time lag. The reason for this is that the air is temporarily prevented from flowing backward due to the delay of pressure propagation in the pipe.

Next, after opening the valve 14, the valve 13 is closed.
Perform preheating in this state to ensure that the exhaust gas system is
When heated to 100 to 130 ° C., preferably 130 ° C. or higher), the damper valve 10 in the closed state is opened, the damper valve 9 is closed, and fuel such as light oil is charged into the hot stove 7 from a fuel system (not shown), The hot stove 7 is started. The combustion gas generated by the hot stove 7 raises the temperature of the fluidized medium 3 to the coal ignition temperature. Although the combustion gas such as light oil contains a large amount of water, the water does not condense because the exhaust gas system has already been heated above the dew point temperature. When the fluidized medium 3 is heated up to the coal ignition temperature (about 600 ° C or higher) and becomes stable,
The damper valve 10 is closed, the damper valve 9 is opened, coal is introduced into the fluidized medium 3 from a coal supply system (not shown), and the combustion air that has passed through the pipe 22 is caused to flow and burn with the fluidized medium 3. .

For adjusting the flow rate of the combustion air suitable for flowing the fluidized medium 3, the proper air flow rate is calculated by the cross-sectional area of the dispersion plate 34, the temperature of the fluidized medium 3 and the pressure in the furnace 2, and the compressor 4 Adjustment is performed by the compressor inlet throttle valve 15 installed upstream. The fluidized bed in which the fluid medium 3 and coal are mixed is about
When the temperature reaches 850 ° C, the amount of coal supplied from the fuel system (not shown) is increased, and the fluid medium is introduced from the fluid medium supply system (not shown) to gradually raise the fluidized bed. As 16 is buried in the fluidized bed and the amount of steam generated increases, the steam is used to drive a steam turbine power generation system (not shown) and the temperature of exhaust gas discharged from the furnace 2 rises. Therefore, at the stage where the power of the compressor 4 can be covered by the gas turbine 5, the generator / motor 6 is switched to the generator to generate power,
The load is gradually increased up to the rated operation and the startup is completed.

FIG. 4 is a characteristic diagram showing the relationship between the valve opening / closing state and the approximate gas temperature at the gas turbine inlet in the above description. In the figure, the reason why the gas turbine inlet gas temperature rises after the shaft is started is that the compressor inlet pressure is reduced using the compressor inlet throttle valve 15, and the high temperature compressor discharge air passing through the valve 13 is Since the valve 13 is closed after the start of preheating, the high temperature compressor discharge air passes through the exhaust gas system and preheats the pipes, so that the temperature is lowered and the air temperature characteristics shown in the figure are obtained. Also,
If the preheating is not performed, the water will be condensed for a while after the ignition of the hot stove 7.

Next, FIG. 5 shows the configuration of another example of the pressurized fluidized bed combined cycle power plant to which the present invention is applied.

In the method for starting the pressurized fluidized bed combined cycle power plant according to this embodiment, the exhaust gas system from the furnace 2 in the cold state to the gas turbine 5 is preheated and discharged prior to the fuel injection into the hot stove. It is to prevent water from condensing in each component in the gas system and to shorten the preheating time. That is, the pipe 2 branched from the pipe 18 on the downstream side of the compressor 4
A heat exchanger 30 is provided at an intermediate portion of 9 to exchange the heat with a heat source such as auxiliary steam, and the heated air is introduced into the pressure vessel 1 and then passes through the valve 11 to enter the furnace 2, the pipe 24, and the dust removing device. 8. The feature is that the pipe 25 is heated.

In the above structure, the pressurized fluidized bed combined cycle power plant is started by closing the valves 12 and 14, opening the valve 13, and starting the compressor 4 and the gas turbine 5 by the electric motor of the generator / motor 6. After the shaft speed stabilizes, the valve 12 and the damper valve 27 are opened, the damper valve 28 is closed, heat is exchanged with the high temperature steam supplied from the auxiliary boiler 32 or the like which has already been started, and the compressor discharge air is discharged. Is heated and introduced into the pressure vessel 1. At this time, the valve 11 is opened and heated air is introduced into the furnace 2 to heat the furnace 2, the pipe 24, the dust removing device 8 and the pipe 25. After opening the valve 12, the valve 14 is opened and the valve 13 is closed with a time lag. The reason for this is the same as in the embodiment shown in FIG. Preheating is performed in this state, and when the exhaust gas system is sufficiently heated, the damper valve 10 in the closed state is opened, the valve 11 is closed, the valve 15 is gradually narrowed, and the hot-air stove 7 has a fuel system (not shown). Then, fuel such as light oil is put in to start the hot stove 7.

The combustion gas generated by the hot stove 7 raises the temperature of the fluidized medium 3 to the coal ignition temperature. Although the combustion gas such as light oil contains a large amount of water, the water does not condense because the exhaust gas system has already been heated above the dew point temperature. When the fluidized medium 3 has risen to the coal ignition temperature and becomes stable, the valve 10 is closed, the valve 9 is opened, coal is fed into the fluidized medium 3 from a coal supply system (not shown), and combustion is carried out through the pipe 22. Flowing medium with air for use 3
Flow with and burn.

To adjust the flow rate of the combustion air suitable for flowing the fluidized medium 3, an appropriate air flow rate is calculated by the cross-sectional area of the dispersion plate 34, the temperature of the fluidized medium 3 and the pressure in the furnace 2.
The valve 15 installed upstream of the compressor 4 is used for adjustment. When the fluidized bed in which the fluid medium 3 and coal are mixed reaches about 850 ° C, the coal supply is increased from the fuel system (not shown), and the fluid medium is supplied from the fluid medium supply system (not shown) to gradually flow. As you raise the floor, heat transfer tubes 16
Are buried in the fluidized bed to generate steam, the temperature of the exhaust gas discharged from the furnace 2 rises as the steam turbine power generation system (not shown) is driven, and the compressor in the gas turbine 5 When the power of No. 4 can be covered, the generator / motor 6 is switched to the generator to generate electric power, the load is gradually increased to the rated operation, and the startup is completed.

In the present embodiment, the heat source of the heat exchanger is the auxiliary steam of the auxiliary boiler, but it goes without saying that other exhaust gas from the auxiliary boiler, an electric heater or the like may be used. When the fluidized medium 3 is sufficiently dried, the valve 11 may not be installed and the damper valve 9 may perform the operation of the valve 11.

[0026]

According to the present invention as described above,
Each component equipment from the furnace to the gas turbine can be preheated, and the effect that ash in the combustion gas during coal combustion does not adhere to each equipment is obtained.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of an example of a pressurized fluidized bed combined cycle power generation plant to which the present invention is applied.

FIG. 2 is a system diagram showing a configuration of a conventional pressurized fluidized bed combined cycle power generation plant.

FIG. 3 is a characteristic diagram showing a relationship between a compressor pressure ratio and a compressor discharge temperature.

FIG. 4 is a characteristic diagram showing a relationship between an open / closed state of each valve in FIG. 1 and a gas turbine inlet temperature.

FIG. 5 is a system diagram showing the configuration of another example of the pressurized fluidized bed combined cycle power generation plant to which the present invention is applied.

[Explanation of symbols]

 1 Pressure Vessel 2 Furnace 3 Fluid Medium 4 Compressor 5 Gas Turbine 6 Generator / Motor 7 Hot Stove 8 Dust Removal Device 15 Compressor Inlet Throttle Valve

Claims (2)

[Claims] 1. A method for starting a pressurized fluidized bed combined cycle power plant that combines a pressurized fluidized bed boiler with a steam turbine power generation system and a gas turbine power generation system to generate compressed air for feeding compressed air to the pressurized fluidized bed boiler. The compressor discharge air temperature is raised by reducing the compressor inlet pressure by a throttle valve provided at the compressor inlet of the exhaust gas system, and the exhaust gas system is heated to a temperature above the dew point temperature before passing the combustion gas rich in water vapor to the exhaust gas system. A method for starting a pressurized fluidized bed combined cycle power generation plant, characterized in that preheating is performed on the plant. 2. A method for starting a pressurized fluidized bed combined cycle power plant for generating power by combining a pressurized fluidized bed boiler with a steam turbine power generation system and a gas turbine power generation system, for sending compressed air to the pressurized fluidized bed boiler. Compressor inlet pressure is reduced by the throttle valve provided at the compressor inlet to raise the compressor discharge air temperature, and the compressor discharge air is heat-exchanged by the heat exchanger to control the inflow air temperature to the boiler. A method for starting a pressurized fluidized bed combined cycle power generation plant, characterized in that the exhaust gas system is preheated to a dew point temperature or higher before the combustion gas having a large amount of water vapor is passed through the exhaust gas system by raising the temperature.