JPH0730685B2 - Method and apparatus for controlling steam injection system in combined cycle power plant - Google Patents

Description

The present invention relates to a method and apparatus for controlling a steam injection system in a combined cycle power plant, and more particularly to a steam injection flow rate control at the time of starting the power plant. The present invention relates to a control method for a steam injection system capable of efficiently removing drainage generated on the upstream side of the device, and the device.

(Prior Art) FIG. 3 shows the overall configuration of a combined cycle power plant.

A conventional power plant of this type is a gas turbine device 1
And the exhaust heat recovery boiler device 7 and the steam turbine device 17.

The gas turbine device 1 is composed of a compressor 2, a combustor 3, and a gas turbine 5. The air sucked from the suction duct system A is compressed by the compressor 2, and the compressed air discharged from this is mixed with the fuel supplied from the fuel pipe system B by the combustor 3 and burned. The combustion gas of the above flows into the gas turbine 5 and performs work there.

The combustion gas leaving the gas turbine 5 is introduced into the exhaust heat recovery boiler 7 through the exhaust gas duct 6. Here, the combustion gas is used as a heat source for generating steam. The exhaust heat recovery boiler 7 includes a low pressure economizer 8, a low pressure drum 9, and a low pressure circulation pump.
10, low pressure evaporator 11, high pressure economizer 12, high pressure drum 13
A high pressure circulation pump 14, a high pressure evaporator 15, and a heater 16 are incorporated.

The steam turbine device 17 includes a steam turbine 18 and a condenser 19. The steam that has worked in the steam turbine 18 is condensed in a condenser 19 and sent to the low pressure economizer 8 via a water supply pump 21. Here, it is heated and enters the low-pressure drum 9, enters the low-pressure evaporator 11 through the low-pressure circulation pump 10,
Evaporated here, low-pressure main steam pipe 22 and low-pressure steam valve 23
Through the low pressure part of the steam turbine 17.

Further, a part of the steam from the low pressure drum 9 is sent to the high pressure economizer 12 via the transfer pump 25. Here, it is heated and enters the high-pressure drum 13, and then enters the high-pressure evaporator 15 through the high-pressure circulation pump 14, where it is evaporated and enters the heater 16, and is heated and passed through the high-pressure main steam pipe 26 and the high-pressure steam valve 27. Enters the high pressure section of the steam turbine 17.

These steams work in the steam turbine 17 and drive the generator 28 together with the gas turbine device 1.

Further, in the above combined cycle power plant, a steam injection piping system C is provided. This is for reducing nitrogen oxides generated during combustion in the combustor 3, and steam is injected into the combustor 3 via the steam injection piping system C. The steam injection piping system C includes a steam injection backup system C1 as a steam source for steam injection and a bleed air injection bleed system C2.

FIG. 4 shows the details of the components of the steam injection piping system C.

The steam injection backup system C1 has a backup stop valve 30
And a backup check valve 32, and the extraction injection extraction system C2 includes an extraction check valve 34 and an extraction stop valve 35.

Further, the steam injection piping system C includes a temperature reducing device 36, a flow rate detector 37, a steam injection flow rate stop valve 38, and a steam injection flow rate adjusting valve.
39 and a steam injection pipe ring header 40 for distributing steam for steam injection. The steam is injected into the combustor 3 through the steam injection pipe ring header 40, and the temperature and flow rate of the steam injected here are controlled as follows.

The cooling water regulating valve 44 is controlled by the signal of the temperature detector 43 for the temperature reducing device located on the downstream side of the temperature reducing device 36, whereby the temperature reducing device 36 is operated and the injected steam reaches a prescribed temperature. Controlled. Further, the steam injection flow rate control valve 39 operates based on the detection value of the flow rate detector 37, and the injected steam is controlled to a prescribed flow rate. The steam injection flow stop valve 38 is controlled by a steam injection permission temperature detector 43.

Further, the steam injection piping system C is provided with a drain discharge system C3 for eliminating the drain generated in the initial stage of steam introduction.

FIG. 5 shows the operation timing of each drain valve 50 to 54 of the drain discharge system C3. After the gas turbine 5 is ignited and started, the backup stop valve 30 is fully opened, and when the ventilation conditions for the steam injection piping system C are established, the steam injection flow stop valve 38
Is fully opened to prepare for ventilation of the gas turbine 5, and the drain valves 50 to 54 of the drain discharge system C3 are fully opened to eliminate stagnant drain.

In the initial stage of the steam injection piping system C, steam is introduced from the steam injection backup system C1 connected to the high-pressure main steam piping 26 to perform warming operation. During this period, the steam condition of the high-pressure main steam is gradually increased. Will be improved to.

When the ventilation conditions for the gas turbine 5 are satisfied after the power plant is installed, the temperature reducing device inlet drain valve 50 and the temperature reducing device outlet drain valve 51 are fully closed. After that, the control of the steam injection flow rate adjusting valve 39 for injecting steam to the combustor 3 is started.
At this time, the steam injection flow stop valve 52 is fully closed. When the steam injection flow rate adjusting valve 39 is slightly opened and enters the control state, the steam injection flow rate adjusting valve inlet drain valve 53 is fully closed, and after a lapse of time, the steam injection flow rate adjusting valve outlet drain valve 54 is fully closed. , The steam injection operation to the combustor 3 is started.

(Problems to be Solved by the Invention) By the way, in the initial stage of introducing the steam from the steam injection backup system C1 and performing the warming operation, the steam with a low degree of heating is introduced, so the drain is injected into the steam injection pipe. Is likely to occur, and more drainage is likely to occur due to heat radiation from the steam injection pipe. Therefore, the conventional drain discharge system C3 has a problem that these drains cannot be discharged sufficiently.

Further, in a region where the cooling water sprayed in the temperature reducing device 36 has a small flow rate, the control characteristics may deteriorate and drain may be generated. If a sufficient mixing distance with is not obtained, drain may be generated, and in such a case, the drain will be carried into the combustor 3, resulting in misfire or large flame temperature deviation and stable. There is a problem that the combustion operation characteristics described above cannot be obtained, and further the combustor 3 is damaged.

Therefore, an object of the present invention is to solve the problems of the above-described conventional technology, to positively eliminate the drain generated in the steam injection piping system at the time of starting the power plant, and to provide stable combustion operation characteristics. An object of the present invention is to provide a control method and apparatus for a steam injection system in a combined cycle power generation plant that is obtained.

[Structure of Invention]

(Means for Solving Problems) In order to achieve the above object, the present invention provides a gas turbine device, an exhaust heat recovery boiler device that generates steam by using exhaust gas from the gas turbine device as a heat source, and A steam turbine device using steam generated by a boiler device as a drive source, and a steam injection piping system for injecting steam for reducing nitrogen oxides generated by combustion in the combustor of the gas turbine device, During operation of the gas turbine device, the turbine extraction steam and the high-pressure main steam from the steam turbine device are introduced into the steam injection piping system, in the method and device for controlling the steam injection system in the combined cycle power plant, In the steam injection piping system, an auxiliary steam system for introducing heating steam from the outside into the steam injection piping, and in the steam injection piping And a drain forced discharge system including a steam separation device for separating drain from the steam of, the auxiliary steam system is operated prior to the start of the gas turbine device, and the heating steam introduced from the auxiliary steam system is operated as described above. It is characterized in that the drain is discharged from the forced drainage system so that the drain in the steam injection pipe can be eliminated in advance.

(Operation) According to the present invention, prior to starting the gas turbine device,
When the auxiliary steam system is operated, heated steam is introduced into the steam injection pipe from here, and the warmed-up operation of the power plant is performed by the heated steam. The heated steam is discharged from the drain forced discharge system, and the drain accumulated in the steam injection pipe is removed to the outside in advance. Further, in the steam injection pipe, the drain is reliably separated from the steam by the steam separator, and this separating operation is continuously performed during the operation of the power generation plant.

(Embodiment) An embodiment of a method for controlling a steam injection system and a device therefor in a combined cycle power plant according to the present invention will be described below with reference to FIGS. 1 and 2. The same parts as those shown in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

First, an embodiment of the control device for the steam injection system will be described.

As shown in FIG. 1, the steam injection piping system C in this combined cycle power plant is similar to the conventional one (see FIG. 4), and a steam injection backup system C1, a bleed air injection bleed air system C2, and a drain discharge. In addition to the system C3, the present embodiment is characterized by an auxiliary steam system P for introducing heating steam from the outside and a drain forced discharge system Q including a steam separator 55. The auxiliary steam system P includes an auxiliary steam check valve 57 and an auxiliary steam source valve 58, and the drain forced discharge system Q includes a steam separator drain valve 59.

Next, the operation of this embodiment will be described with reference to FIG.

Prior to starting the combined cycle power plant, the auxiliary steam source valve 58 is opened to introduce the warming-up heated steam from the auxiliary steam system P into the steam injection piping system C. At this time, the steam injection flow stop valve 38 is closed, and the drain valves 50, 51, 52 and 59 located upstream of the stop valve 38 are all opened. As a result, all the drain accumulated in the steam pipe is discharged. Moreover, since it is warmed up by the heated steam, drain generation can be suppressed even after switching to the steam injection backup system C1 under low steam conditions.

When the high-pressure main steam exceeds the specified pressure, all drain valves including the drain valves 53 and 54 located downstream of the steam injection flow stop valve 38 are used as in the conventional one (see FIG. 5). And the steam injection flow stop valve 38 is opened together therewith.

After joining the power plant, gas turbine 5 (see Figure 3)
When the ventilation conditions for the temperature reducing device are adjusted, the temperature reducing device inlet drain valve 50 and the temperature reducing device outlet drain valve 51 are fully closed. After that, the control of the steam injection flow rate adjusting valve 39 for injecting steam to the combustor 3 is started. At this time, the steam injection flow rate stop valve 52 and the steam / water separator drain valve 59 are fully closed.

When the steam injection flow rate adjusting valve 39 is slightly opened and enters the control state, the steam injection flow rate adjusting valve inlet drain valve 53 is fully closed, and after a lapse of time, the steam injection flow rate adjusting valve outlet drain valve 54 is fully closed. , The steam injection operation to the combustor 3 is started.

On the other hand, after shifting to the steam injection operation, in order to control the temperature of the steam injected to the combustor 3, the cooling water adjustment device 44 is controlled as described above, and the temperature control device 36 is controlled by the water supply pump.
Is supplied with cooling water. When the temperature reducing device 36 is controlled and operated, drainage also occurs here. However, according to the present embodiment, the steam / water separator 55 is installed in the drain forced discharge system Q.
Is provided, the drain is separated by the steam separator 55 and discharged to the outside through the drain trap 60. Further, since the steam / water separator 55 is provided, the reliability of the steam injection permission temperature detector 45 can be improved.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, a steam injection piping system for injecting steam for reducing nitrogen oxides generated by combustion is provided in the combustor of the gas turbine device, and the steam injection piping is provided. The system is provided with an auxiliary steam system for introducing heating steam from the outside into the steam injection pipe, and a drain forced discharge system including a steam separator for separating drain from the steam in the steam injection pipe, Prior to starting the gas turbine device, the auxiliary steam system was operated and the heated steam introduced from this was discharged from the drain forced discharge system so that the drain in the steam injection pipe could be eliminated in advance. Drain generated in the system can be positively removed, and inconveniences such as the injection of drain into the combustor of the gas turbine device can be avoided. The effect of such can be obtained a stable combustion operation characteristics of the plant.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a control device for a steam injection system of a combined cycle power plant according to the present invention, and FIG. 2 is a diagram showing the opening / closing timing of a drain valve in the steam injection system. Fig. 4 is a system diagram showing the overall configuration of a conventional combined cycle power plant, Fig. 4 is a system diagram showing the steam injection system of the same combined cycle power plant, and Fig. 5 is a diagram showing opening / closing of a drain valve in the steam injection system. It is a diagram showing a timing. 1 ... Gas turbine equipment, 7 ... Exhaust heat recovery boiler, 17 ...
… Steam turbine equipment, 28 …… combustor, 38 …… Steam injection flow stop valve, 39 …… Steam injection flow adjustment valve, 50 to 54 …… Drain valve, 55 …… Steam separation device, C …… Steam injection Piping system,
C1 ... Steam injection backup system, C2 ... Steam injection extraction system, C3 ... Drain discharge system, P ... Auxiliary steam system, Q
...... Drain forced discharge system.

Claims (2)

[Claims] 1. A gas turbine device, an exhaust heat recovery boiler device for generating steam by using exhaust gas from the gas turbine device as a heat source, a steam turbine device using steam generated by the boiler device as a drive source, and And a steam injection piping system for injecting steam for reducing nitrogen oxides generated by combustion in the combustor of the gas turbine device,
During operation of the gas turbine device, in the method for controlling a steam injection system in a combined cycle power plant, which introduces turbine extracted steam and high-pressure main steam from the steam turbine device into the steam injection piping system, the steam injection The piping system is provided with an auxiliary steam system for introducing heated steam from the outside into the steam injection pipe, and a drain forced discharge system including a steam separator for separating drain from the steam in the steam injection pipe. Prior to starting the gas turbine device, the auxiliary steam system is operated, the heating steam introduced from here is discharged from the drain forced discharge system, and the drain in the steam injection pipe is eliminated in advance. And a method for controlling a steam injection system in a combined cycle power plant. 2. A gas turbine device, an exhaust heat recovery boiler device for generating steam using exhaust gas from the gas turbine device as a heat source, a steam turbine device using the steam generated by the boiler device as a drive source, and In a combined cycle power plant including a steam injection piping system for injecting steam for reducing nitrogen oxides generated by combustion in a combustor of a gas turbine device, the steam injection piping system is a steam injection piping system. An extraction steam piping system for introducing extraction steam from the steam turbine device to the backup steam piping system for introducing high-pressure main steam into the steam injection pipe,
An auxiliary steam system for introducing heating steam from the outside into the steam injection pipe, and a drain forced discharge system including a steam separation device for separating drain from the steam in the steam injection pipe are provided. Controller for steam injection system in combined cycle power plant.