JPS59108808A - Starting method of combined cycle power plant - Google Patents

Abstract

PURPOSE:To start a combined cycle power plant safely by opening a steam governer valve with predetermined speed and maintaining at constant opening thereafter controlling with some opening characteristic. CONSTITUTION:At first a gas turbine 1 is started while maintaining a steam governer valve 15 at the minimum to rotate a directly coupled steam turbine 2. Upon reaching to rated rotation, said valve 15 is fully closed. Upon reaching to such timing where high temperature high pressure steam is produced in a waste heat recovery boiler 4 to open said valve 15, an open command signal is provided to a start controller 13 and if the water level in a drum 14 indicated by a level meter 20 is lower than setting level, said valve 15 is opened with constant speed while upon reaching to setting level the opening is maintained constant immediately and when dropping below the setting level, it is opened again with constant speed to full open while repeating said operation thus to complete start control. Consequently tripping fault caused by the water level in the drum can be prevented to realize safe starting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improved start-up control method for a combined cycle power plant that controls the opening degree of a steam control valve in relation to the drum water level of an exhaust heat recovery boiler.

[Technical background of the invention and its problems]

Combined cycle power plants are gas turbines.

A generator and a steam turbine are arranged on one shaft (in two rows) and combined with one exhaust heat recovery boiler to form a system. To start up this combined cycle power plant, first connect the gas turbine to the steam turbine and generator. 4m is directly connected, the ignition is started and the rotational speed is increased.The rated rotational speed (2 is the gas turbine control device: 2 is the same speed,
The generator takes the minimum load. From around this time, the temperature of the exhaust gas from the gas turbine also rises, and high-temperature, high-pressure steam is also generated from the exhaust heat recovery boiler. From this point on, the steam control valve is gradually opened at a constant speed, and steam is sent to the steam turbine to start the load.Meanwhile, the gas turbine is also operated at the required load by increasing the load.
Become.

Therefore, the starting method using the conventional starting device of a combined cycle power plant (2), after the generator is connected during startup (2), the steam control valve of the exhaust heat recovery boiler is gradually opened The phenomenon that the water level of the drum rises abnormally (2) often occurs, and sometimes the drum water level rises so high that the power plant trips (2).The cause of this is that the steam booster valve is opened, and the pressure inside the drum increases. This is thought to be due to a phenomenon known as the so-called reverse response phenomenon of water level, in which the water rapidly rises and the water level rises.If this phenomenon occurs, the drum Even if the water level is controlled by obtaining three control signals, that is, a water level regulator signal, a feed water flow rate signal, and a steam flow rate signal, it is difficult to suppress the rise in the water level in the drum.

[Object of the Invention] The object of the present invention is to maintain a stable water level in the drum of the exhaust heat recovery boiler during startup, and also to enable smooth startup of an Indian cycle power plant. There are two methods (providing a control method).

[Summary of the invention]

The start-up control method for a combined cycle power plant according to the present invention is characterized in that, upon start-up, the opening degree of the steam control valve is controlled in relation to the drum water level of the exhaust heat recovery boiler.

[Embodiments of the invention]

The present invention will be described below with reference to the embodiments shown in the drawings. First, FIG. A single plant is constructed by arranging the generators 3 on one axis and combining them with a canned exhaust heat recovery boiler 4.

The gas turbine device 1 includes a gas turbine 5, a compressor 6, and a combustor 7, and the load on the gas turbine 5 is controlled by adjusting the amount of fuel supplied to the combustor 7, and the exhaust gas g is used for exhaust heat recovery. The exhaust heat is sent to the boiler 4 for use (2).Then, in the exhaust heat recovery boiler 4, the exhaust gas g from the gas turbine 5 is used as a heat source to run a coal saver 8 and a vaporizer 9.
And the superheater 10 generates steam.

That is, the feed water condensed in the condenser 11 of the steam turbine 2 is pressurized in the condensate bonder 12, and is led to the drum 14 via the feed water control valve 13 and the economizer 8 of the exhaust heat recovery boiler 4.

Furthermore, it becomes steam as it passes through the vaporizer 9 from the double drum 14, returns to the drum 14 again, and is separated from brackish water, and then becomes superheated steam in the superheater 10.

At this time, the water level of the drum 14 is adjusted by the opening degree of the water supply control valve 13. The superheated steam from the superheater 10 is
Through steam control valve 15 and steam stop valve 16.

Steam turbine 2 (2 guided to do work. Also superheater 1
The 0 outlet has a turbine bypass that releases steam when the steam pressure becomes abnormal (two steams are released, and after the pressure and temperature are reduced by the pressure reducing valve 17 and temperature reducing valve 18, the steam is released to the condenser. However, the present invention (in the second aspect, the activation control device 19
is provided, and the opening degree of the steam control valve 15 is controlled by obtaining a water level signal from a drum water level measuring device. This I5:,IJJ'l91J control device 190 control function is
The flowchart shown in FIG. 2 and the time chart shown in FIG. 3 are explained.

Next, we will explain the method for starting a combined cycle power plant according to the present invention. First, the gas turbine device 1 is ignited and started to increase the rotation speed. At this time, the directly connected steam turbine 2 also rotates. However, the exhaust gas still remains. Since the temperature of g is not high enough, high temperature and pressure steam is not generated. At this time, the steam stop valve 16 is fully opened, while the A gas control valve 15 is fully opened.
is the minimum opening; 2 is maintained at the steam turbine 2 (2 supplies cooling steam).

This is due to the fact that the gas turbine unit 1 causes the steam turbine 2 to increase in rotation. This is to prevent this.

In this way, when the rated rotation a (2) is reached, the steam control valve 21 is also fully closed, and the control device (2 and 4) of the gas turbine device 1 is added.Then, the generator 3 takes the minimum load. (Secondly, the temperature of the exhaust gas g also rises, and high-temperature local pressure steam is generated in the exhaust heat recovery boiler 4.

At this point, in the present invention, the steam control valve 15
When the time has come to open the engine, start control device 1 is activated at time 1 in Figure 3.
When an open command signal is input to 9, the water level of the drum 14 is input from the drum water level measuring device. The drum water level is then compared to the set point. This set value is set somewhat higher than the control target water level of the drum.

This set value is determined based on the capacity t of the drum 14, etc.

If the value is less than the set value, the steam regulating valve 15 is opened at a constant rate of A/min. This operation is repeated until the steam regulating valve 15 is fully opened, and the steam regulating valve 15 is continuously opened. (2) constant speed A/min (2) opened.

However, when the water level in the drum 14 exceeds the set value at a certain time T2 in FIG. 3, the steam control valve 15 is immediately operated to maintain a constant opening. and drum 14
When the water level drops by more than X times from the set value (2), the steam control valve 15 begins to open at a speed of A times per minute from time T3 in Figure 3. After these operations are repeated, the final When the steam control valve 15 is fully opened, the command from the startup control device 19 disappears at time T in FIG. 3, and the startup control ends.

That is, in the present invention, the command from the start-up control device 19 (2) controls the steam control valve 15 at the time T in FIG.
The section from 1 to T2 opens at a certain speed and reaches time T.

The section from ~T3 is maintained at a constant opening, and at time T, the section from ~T opens again at a certain speed and at 100% opening, so to speak, under the two-stage characteristic (this is a two-step control method). This (2) The conventional steam control valve 15 is shown in Figure 3 (2) at time T.
Gradually (
In the case of the method of opening (2), it was possible to effectively (= eliminate) the trouble caused by the rise in the water level of the drum 14 that occurred from time to time.

〔Effect of the invention〕

As described above, in the present invention, the steam control valve is opened at a certain speed, then maintained at a constant opening, and then restarted again. Control with the opening characteristic to open at a certain speed (from the second point)
Accidents such as tripping of the photoelectric station due to the high water level of the drum of the exhaust heat recovery boiler 2 can be prevented, and the start-up operation can be continued safely.

[Brief explanation of the drawing]

Figure 1 is an equipment configuration diagram of the Koton Plant to give an overview of the method of starting up the Indian Cycle Power Plant according to the present invention;
This figure and FIG. 3 are a flowchart and a time chart for explaining the operation of the activation control device used on the C2 side of the present invention. 1... Cast turbine device 2... Steam turbine 3.
... Generator 4 ... Exhaust heat recovery boiler 5 ...
・Ganu turbine 6...Compressor 7...Combustor
8... Energy saver 9... Evaporator
10... Superheater 11... Condenser 12.
... Condensate pump 13 ... Water supply control valve 14 ...
・Drum 15...Steam control valve 16...Steam stop valve 17...Pressure reducing valve 18...Desuperheater 19...Start control device

Claims (2)

[Claims] (1) Combined vehicle power plant consisting of gas turbine, steam turbine and exhaust heat recovery boiler (2)
At its startup (= steam control valve initially (2) gradually at a certain speed (
A method for starting a combined cycle power plant characterized by double opening, maintaining a constant opening midway through, and then gradually opening again at a certain speed. (2) In a combined cycle power plant consisting of a gas turbine, a steam turbine, and an exhaust heat recovery boiler,
The drum water level of the exhaust heat recovery boiler is set to a first setting value and a second setting value lower than this, and when the power plant is started up, the steam control valve is gradually turned at a certain speed (double opening, drum water level). Claim 1, characterized in that when the water level becomes equal to or higher than the first set value, the opening degree is maintained constant, and when the water level becomes equal to or less than the second set value, C2 opens again at a certain speed. How to start up a combined cycle power plant as described in section.