JPS61152914A - Starting of thermal power plant - Google Patents

Abstract

PURPOSE:To reduce incurring of starting loss and to improve the efficiency of a load regulating operation and the like, by a method wherein a turbine for driving a water feed pump is started by means of steam from other unit, and after, after ignition of a boiler, generated steam is increased enough in temperature and pressure, steam is extracted from the boiler. CONSTITUTION:During the starting of a plant, steam from other unit is fed to a water feed pump turbine 26 through an auxiliary steam header 28. This starts a water feed pump 37, and starts the feed of water to a boiler 31. After ignition of the boiler 31, after boiler generation steam is increased in temperature and a pressure to a value being high enough to allow driving of the water feed pump turbine 26, boiler generation steam is fed to the water feed pump turbine 26 through a steam line 27 for starting from the outlet of a heat transfer pipe 35 at the rear of a ceiling, and is switched to steam from an auxiliary steam header 28. This reduces incurring of starting loss and performs efficient load regulating operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for starting a thermal power plant, and particularly to a method for starting a thermal power plant suitable for starting a plant for load adjustment operation.

(Technical Background of the Invention) With the diversification of electric power demand in recent years, there is an increasing demand for load adjustment operation according to load fluctuation in thermal power plants that are highly flexible in terms of operation.

For example, there is a DSS operation in which load operation (power generation) is performed during the day when power demand is high, and operation is stopped at night when power demand is low.

By the way, thermal power plants are generally composed of so-called master equipment such as boilers, turbines, and generators that are directly involved in power generation, and so-called auxiliary equipment such as water pumps that are indirectly involved in power generation.

When starting up a thermal power plant, a procedure is adopted in which the auxiliary machines are first driven one after the other, and then the main machine is driven. That is, until the generated power is delivered to the grid, a certain amount of loss of power, fuel, etc., called startup loss, occurs. Although the occurrence of this startup loss cannot be avoided, as mentioned above, there is a growing demand for load adjustment operation that increases the number of plant startups and shutdowns, so it is possible to reduce this startup loss from an energy-saving perspective. An important issue for thermal power plants is to minimize the amount of heat generated.

(Problems with Background Art) A method of starting up a conventional thermal power plant will be explained with reference to FIG.

Figure 2 does not show an example of the water supply and steam system of a thermal power plant using a once-through boiler. The boiler 1 includes a coal saver 2, a furnace path 3, a steam/water separator 4, a heat transfer section 5, a superheater 6, and the like, and water is supplied to the boiler 1 from a water supply pump 7. When the required amount of water supply is secured, the boiler is ignited and fuel is injected, and the water supply whose temperature and pressure have been raised thereby is separated into steam and water by the steam-water separator 4. The separated steam passes through a heat transfer section 5 and a superheater 6, and is sent to a main steam pipe 8. At the time of plant startup, the steam is guided to the condenser 10 via a startup bypass system 9 branched from the middle of the main steam pipe 8 until the steam reaches a predetermined temperature and pressure.

The water separated by the steam-water separator 4 passes through the separation tank 11, and some of the water is returned to the inlet water supply pipe of the economizer 2 by the boiler recirculation pump 12, and the other water is sent to the flash tank 1.
3 and is led to the condenser 10.

As the amount of fuel input increases, the steam generated in the steam separator 4 is heated and pressurized, and after reaching the turbine ventilation condition, it is sent to the turbine 16 via the main steam stop valve 14 and control valve 15, which are opened. Ventilated. After that, it goes through the process of joining and increasing the load, and then returns to normal operation.

Note that during normal operation, for example, the exhaust gas of the high-pressure turbine 16a is supplied to the low-pressure turbine 16b via the reheater 17, and then turned into exhaust steam and guided to the condenser 10. Condensate is handled by a condensate pump 18, a gland steam condenser 19, and a low pressure heater 21.
The water is fed back to the water supply pump 7 via the deaerator 22, etc., heated by the high-pressure heater 23, and fed to the boiler 1 as boiler feed water.

By the way, in the conventional starting method described above, since the water supply pump 7 is started by the electric motor 24, the electric power is
J11 driving power is generated as a starting loss. In addition, most of the heat given to the feed water by fuel injection during startup is led to the condenser 10 via the bypass system as steam or condensate, and is discharged to the outside of the system via the condenser cooling water. Therefore, all of that heat becomes startup loss.

[Purpose of the invention]

The present invention has been developed in view of these circumstances, and it eliminates the need for electricity for starting the feed water pump, which conventionally occurred as a starting loss, and eliminates the startup-specific steam that was conventionally discharged to the bypass system when starting the plant. An object of the present invention is to provide a method for starting a thermal power plant in which a part of the water can be effectively used for starting a water supply pump, thereby reducing starting loss and efficiently performing load adjustment operations, etc.

[Summary of the invention]

In order to achieve the above object, the present invention starts supplying water to the boiler before igniting the boiler, and after the necessary amount of water supply is secured, ignites the boiler and inputs fuel to raise the generated steam to a predetermined temperature and pressure state. In a method for starting a thermal power plant, a turbine-driven water pump is used in the water supply system, and the turbine for driving the water pump is first started with steam from the steam generation system of another unit. When the temperature and pressure of the steam generated after ignition of the boiler is raised to a value capable of driving the turbine, steam is extracted from the middle of the boiler, and the extracted steam is switched and supplied for starting the turbine.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an example of a water supply and steam system of a thermal power plant using a once-through boiler.

The boiler 31 includes a economizer 32, a furnace bus 33, and a steam/water separator 3.
4, a heat transfer section 35, a superheater 36, etc., and water is supplied to this boiler 31 from a water supply pump 37. The feed water pump 37 is of a steam turbine-driven type, and a turbine for driving the feed water pump (hereinafter referred to as a water feed pump turbine) 26 is connected to a part of the boiler 31, for example, a heat transfer section (
Specifically, a starting steam pipe line 27 for supplying boiler-generated steam is connected from the outlet of the ceiling rear heat transfer section (35).

In addition, an auxiliary steam header 2 is connected to a steam generation source (not shown) of another unit in the middle of this starting steam pipe line 27.
8 are connected via an auxiliary conduit 29.

When starting up the plant, steam from other units is first transferred to the water supply pump turbine 26 via the auxiliary steam header 28.
This starts the water supply pump 37 and starts supplying water to the boiler 31.

Once the required water supply amount is secured, the boiler 31 is ignited and fuel is supplied. As the amount of fuel input increases, the temperature of the water supply increases,
It is pressurized, separated into steam and water by the steam-water separator 34, and flows from the ceiling rear heat transfer section 35 to the superheater 36 side. Therefore,
When this boiler-generated steam is heated and pressurized to a value that allows the feedwater pump turbine 26 to be driven, the boiler-generated steam is extracted from the outlet of the ceiling rear heat transfer section 35 via the startup steam pipe 27, and the steam is The steam from the auxiliary steam header 28 is switched and supplied to the water supply pump turbine 26 as starting steam.

The feed water pump turbine 26 can be driven by relatively low temperature, low pressure steam to operate the feed water pump 37, and this level of steam is obtained from the ceiling rear heat transfer section 35 shortly after the boiler is ignited. be.

Note that the initially generated steam other than that required for driving the feedwater pump turbine 26 is sent to the main steam pipe 38 via the superheater 36. The steam is guided to the condenser 40 via the start-up bypass system 39 branched from the middle of the main steam pipe 38 until the steam reaches a certain temperature and pressure rise state that enables power generation.

Note that the water separated by the steam-water separator 34 is transferred to the separation tank 41.
Some of the water is returned to the inlet water supply pipe of the economizer 32 by the boiler recirculation pump 42, and the other water is led to the condensate Fi 40 via the flash tank 43.

As the amount of fuel input increases, the steam generated in the steam separator 34 is gradually heated and pressurized, and when the turbine ventilation conditions for power generation are reached, the main steam stop valve 44 and the control valve 45 are opened. The turbine 46 is vented through the air. After that, normal operation resumes after the process of merging and load increase.

Note that during normal operation, for example, the exhaust gas of the high-pressure turbine 46a is supplied to the low-pressure turbine 46b via the reheater 17, and then turned into exhaust steam and guided to the condenser 40. Condensate is handled by a condensate pump 48, a gland steam condenser 49, and a low pressure heater 51.
, is returned to the water supply pump 37 via the deaerator 52 etc.,
It is further heated via a high-pressure heater 53 and fed to the boiler 31.

According to the above startup method, water is supplied to the boiler at the time of plant startup by supplying natural air to the water supply pump turbine 26, so unlike the conventional startup method using an electric motor-driven water pump, driving loss of electric power related to water supply is reduced. will not occur.

In addition, since the steam generated during the initial heating of the boiler is used as the steam used to drive the water supply pump 37, conventionally all steam generated during startup was discharged outside the machine via the bypass system and condenser. Unlike conventional models, effective use of in-house power can be achieved,
The starting loss can be reduced accordingly.

〔Effect of the invention〕

As detailed above, the present invention relates to a method for starting a thermal power plant that uses steam generated by an in-house boiler to drive a water pump during plant startup without driving an electric motor-driven water pump. , it is possible to reduce the starting loss related to electrical power and internal heat m.

Therefore, startup loss can be significantly reduced, so startup,
This makes it possible to perform load adjustment operations more efficiently than in recent years, where the number of repeated stops is increased, and economic efficiency can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the present invention, and FIG. 2 is a system diagram showing a conventional example. 26... Water pump turbine, 31... Boiler, 3
7... Water supply pump, 38... Main steam pipe, 39...
Startup bypass system.

Claims (1)

[Claims] In a thermal power plant, water supply to the boiler is started before the boiler is ignited, and after the required amount of water supply is secured, the boiler is ignited, fuel is added, and the generated steam is circulated through the startup bypass system until the specified temperature and pressure are reached. In the startup method, a turbine-driven water supply pump is used in the water supply system, and the turbine for driving the water supply pump is first started with steam from a steam generation system of another unit, and after the boiler is ignited, the generated steam can drive the turbine. 1. A method for starting a thermal power plant, which comprises extracting steam from the middle of a boiler after the temperature and pressure have been raised to a certain value, and switching and supplying the extracted steam for starting the turbine.