JPH01100303A - Control method and device for steam injection system in combined-cycle generating plant - Google Patents

Abstract

PURPOSE:To avoid such an improper phenomenon where the drain is injected into a combustion chamber by discharging the heated steam, which is introduced from an auxiliary steam system prior to the start of a gas turbine device, from a forced, drain discharge system, so that the drain in a steam injection pipe can be discharged in advance. CONSTITUTION:In the captioned plant, in which steam is injected from a steam injecting piping system C into a combustion chamber 3 in order to decrease the nitrogen oxide produced in the combustion chamber 3 of the captioned plant, a steam injection piping system C is provided with a steam injection backup system C1 as a steam source for steam injection, an extracted-steam- injection-extraction system C2, and a drain discharging system C3, which discharges the drain produced during the early period of steam introduction. In this case, an auxiliary steam system P, which introduces the heated steam from the outside, and a forced, drain discharging system Q, which contains a steam separator 55, are provided. Prior to the start of the gas turbine, the auxiliary steam system P is actuated, so that the heated steam is discharged from the forced, drain discharging system Q.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method and device for controlling a steam injection system in a combined cycle power plant, and particularly to a steam injection flow rate control method at the startup of a power plant. The present invention relates to a method for controlling a steam injection system and an apparatus for controlling a steam injection system that can efficiently eliminate drain generated on the upstream side of the apparatus.

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

This type of conventional power plant includes a gas turbine device 1, an exhaust heat recovery boiler device 7, and a steam turbine device 17.

The gas turbine device 1 includes a compressor 2, a combustor 3, and a gas turbine 5. The air taken in from the suction duct system A is compressed by the compressor 2, and the compressed air discharged from here and the fuel supplied from the fuel piping system B are mixed and combusted by the combustor 3. The combustion gas flows into the gas turbine 5 and does work there.

Combustion gas exiting the gas turbine 5 is introduced into an exhaust heat recovery boiler 7 through an exhaust gas duct 6. Here, the combustion gas is used as a heat source for steam generation.

The exhaust heat recovery boiler 7 includes a low pressure energy saver 8 and a low pressure drum 9.
A low-pressure circulation pump 10, a low-pressure evaporator 11, a high-pressure economizer 12, a 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 1
It consists of 9. The steam that has done work in the steam turbine 18 becomes condensed water in the condenser 19, and is sent to the low-pressure economizer 8 via the water supply pump 21. Here, it is heated and enters the low-pressure drum 9, passes through the low-pressure circulation pump 10 and enters the low-pressure evaporator 11, where it is evaporated and the low-pressure main steam pipe 2
2 and enters the low pressure section of the steam turbine 17 through the low pressure steam valve 23.

In addition, part of the steam from the low pressure drum 9 is transferred to the transfer pump 25.
is sent to the high-pressure economizer 12 via. Here, it is heated and enters the high-pressure drum 13, passes through the high-pressure circulation pump 14, enters the high-pressure evaporator 15, is evaporated here, enters the heater 16, is heated, and enters the high-pressure main steam pipe 26 and the high-pressure steam valve 2.
7 into the high pressure section of the steam turbine 17.

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

Moreover, in the above-mentioned combined cycle power plant, a steam injection piping system C is provided. This is to reduce nitrogen oxides generated during combustion within the combustor 3, and steam is injected into the combustor 3 via this steam injection piping system C. This steam injection piping system C includes a steam injection backup system C1 as a steam source for steam injection and an air extraction extraction system C2.

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

The steam injection backup system C1 includes a backup stop valve 30, a pressure regulating valve 31 that adjusts to the required steam pressure, and a backup reverse valve 32.
2 consists of a bleed check valve 34 and a bleed check valve 35.

Further, the steam injection piping system C includes a temperature reducing device 36, a flow rate detector 37, a steam injection flow stop valve 38, a steam injection flow rate adjustment valve 39, and a steam injection pipe ring header that distributes steam for steam injection. 40. 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.

Temperature detector 43 for temperature reduction device located downstream of temperature reduction device 36
The cooling water regulating valve 44 is controlled by the signal, which activates the temperature reduction device 36 and controls the temperature of the injected steam to a specified temperature. Further, the steam injection flow rate control valve 39 is operated based on the detected value of the flow/amount detector 37, and the injected steam is controlled to a specified flow rate. Steam injection flow stop valve 3
8 is controlled by a steam injection permission temperature detector 45.

Furthermore, the steam injection piping system C is equipped with a drain discharge system C3 for removing drain generated at the initial stage of steam introduction.

FIG. 5 shows each drain valve 50 to 5 of the drain discharge system C3.
4 shows the operation timing. After the gas turbine 59 is ignited and started, the backup stop valve 30 is fully opened and the ventilation conditions to the steam injection piping system C are established.The steam injection flow rate stop valve 38 is fully opened in preparation for ventilation to the gas turbine 5, and the drain is closed. Each of the drain valves 50 to 54 of the discharge system C3 is fully opened to remove accumulated drain.

At an initial stage, steam is introduced into the steam injection piping system C from the steam injection backup system C1 connected to the high pressure main steam piping 26 and a warming operation is performed, during which time,
Steam conditions for high-pressure main steam were gradually changed.

After the power generation plant is installed, when the ventilation conditions to the gas turbine 5 are established, the temperature reduction device artificial drain valve 50 and the temperature reduction device outlet drain valve 51 are fully closed. After that, control of the steam injection flow rate regulating valve 39 is started in order to inject steam into the combustor 3. At this time, the steam injection flow stop valve 52 is fully opened.

When the steam injection flow rate adjustment valve 39 opens slightly and enters the control state, the steam injection flow rate adjustment valve inlet drain valve 53 becomes fully open, and after a time limit, the steam injection flow rate adjustment valve outlet drain valve 54 fully closes. Shift to steam injection operation to the combustor 3.

(Problems to be Solved by the Invention) By the way, in the initial stage of introducing steam from the steam injection backup system C1 and performing a warming operation, steam with a low degree of heating is introduced, so there is a possibility that drainage may occur in the steam injection piping. A large amount of condensate is likely to be generated, and a large amount of drainage is likely to be generated due to heat radiation from the steam injection piping. Therefore, there is a problem in that the conventional drain discharge system C3 cannot sufficiently discharge these drains.

Furthermore, in areas where the cooling water sprayed in the temperature reduction device 36 has a small flow rate, the control characteristics may deteriorate and drainage may occur. If a sufficient distance for mixing with steam is not obtained, drainage may occur, and in such a case, the drainage may be carried into the combustor 3, causing a misfire or a large flame temperature deviation. There is a problem that stable combustion operation characteristics cannot be obtained and furthermore, the combustor 3 may be damaged.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional technology, to actively eliminate condensate generated in the steam injection piping system at the time of startup of a power plant, and to maintain stable combustion operation characteristics. An object of the present invention is to provide a method and apparatus for controlling a steam injection system in a combined cycle power plant.

[Structure of the invention]

(Means for solving the problem) In order to achieve the above object, the present invention includes a gas turbine device, an exhaust heat recovery boiler device that generates steam using exhaust gas from the gas turbine device as a heat source, A steam turbine device that uses steam generated by the boiler device as a driving source, and a steam injection piping system that injects steam for reducing nitrogen oxides generated by combustion into the combustor of the gas turbine device, A method and apparatus for controlling a steam injection system in a combined cycle power plant, wherein turbine bleed steam and high-pressure main steam from the steam turbine device are introduced into the steam injection piping system during operation of the gas turbine device. , the above steam injection piping system includes an auxiliary steam system for introducing heated steam from the outside into the steam injection piping, and a forced drain discharge system that includes a steam separation device for separating condensate from the steam in the steam injection piping. Prior to starting up the gas turbine device, the auxiliary steam system is operated to discharge the heated steam introduced from the auxiliary steam system from the forced drain outlet system, and the drain in the steam injection pipe is cleared in advance. It is characterized by being able to be eliminated.

(Function) 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 the auxiliary steam system, and this heated steam performs warming-up operation of the power generation plant. This heated steam is discharged from the drain forced discharge system, and the drain remaining in the steam injection pipe is previously discharged to the outside. Further, in the steam injection piping, condensate is reliably separated from steam by a steam/water separator, and this separation operation is continuously performed during operation of the power plant.

(Embodiment) Hereinafter, an embodiment of a method and apparatus for controlling a steam injection system in a combined cycle power plant according to the present invention will be described with reference to FIGS. 1 and 2. Note that the same parts as those shown in FIG. 4 are denoted by the same reference numerals, and the explanation thereof will be omitted.

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

As shown in Figure 1, the steam injection piping system C in this combined cycle power plant consists of a steam injection backup system C1, a bleed air injection bleed system C2, and a drain discharge system, similar to the conventional system (see Figure 4). Equipped with system C3,
Other features of this embodiment include an auxiliary steam system P for introducing heating steam from the outside, and a steam/water separator 55.
It is equipped with a forced drain discharge system Q including: and,
The auxiliary steam system P includes an auxiliary steam check valve 57 and an auxiliary steam source valve 58, and the forced drain discharge system Q includes a steam-water separator drain valve 59.

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

Prior to starting up the combined cycle power plant, the auxiliary steam source valve 58 is opened to introduce heating steam for warming up 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 all the drain valves 50, 51, 52, and 59 located upstream of this stop valve 38 are opened.

As a result, all condensate remaining in the steam piping is discharged. Furthermore, since the system is warmed up by heated steam, the generation of condensate can be suppressed even if the system is subsequently switched to the steam injection backup system C1 with lower 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, as in the conventional system (see Fig. 5). , and at the same time open the steam injection flow stop valve 38.

After adding the power plant, gas turbine 5 (see Figure 3)
When the ventilation conditions are established, the detemperature device artificial drain valve 50,
The detemperature device outlet drain valve 51 is fully closed. After that, the steam injection flow rate adjustment valve 39 is used to inject steam into the combustor 3.
control is started.

At this time, the steam injection flow stop valve 52 and the steam/water separator drain valve 59 are fully closed. When the steam injection flow rate adjustment valve 39 is slightly opened and enters the control state, the steam injection flow rate adjustment valve inlet drain valve 53 is fully closed, and after a time limit, the steam injection flow rate adjustment valve outlet drain valve 5-4 is fully closed. , and the steam injection operation to the combustor 3 is started.

On the other hand, after shifting to 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 cooling water is sent from the water supply pump to the temperature reduction device 36. is supplied.

When this temperature reduction device 36 is operated in a controlled manner, drainage is also generated here. However, according to this embodiment, since the forced drain discharge system Q is provided with the steam/water separator 55, the drain is separated by the steam/water separator 55 and discharged to the outside via the drain trap 60. . Further, since the steam/water separator 55 is provided, effects such as improved reliability of the steam injection permission temperature detector 45 can be obtained.

〔Effect of the invention〕

As is clear from the above description, the present invention includes a steam injection piping system that injects steam for reducing nitrogen oxides generated by combustion into a combustor of a gas turbine device. The system is provided with an auxiliary steam system for introducing heated steam from the outside into the steam injection piping, and a forced drain discharge system including a steam/water separator for separating condensate from the steam in the steam injection piping, Prior to the start-up of the gas turbine equipment, the auxiliary steam system is operated, and the heated steam introduced from this system is discharged from the drain forced discharge system, so that the condensate in the steam injection piping can be removed in advance. It is possible to actively eliminate condensate generated within the system, and it is possible to avoid inconveniences such as condensate being injected into the combustor of the gas turbine equipment, thereby improving the stable combustion operation characteristics of the power plant. It is possible to obtain the following effects.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the control device for the steam injection system of a combined cycle power plant according to the present invention, FIG. 2 is a diagram showing the timing of opening and closing of the drain valve in the steam injection system, and FIG. Figure 4 is a system diagram showing the overall configuration of a conventional combined cycle power plant, Figure 4 is a system diagram showing the steam injection system of the same combined cycle power plant, and Figure 5 shows the opening and closing of the drain valve in the same steam injection system. FIG. 3 is a diagram showing timing. 1... Gas turbine device, 7... Exhaust heat recovery boiler,
17...Steam turbine device, 28...Combustor, 38
...Steam injection flow rate stop valve, 3...Steam injection flow rate adjustment valve, 50-54...Drain valve, 55...Steam water 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. Applicant's agent Mr. Sato

Claims (1)

[Claims] 1. A gas turbine device, an exhaust heat recovery boiler device that generates steam using exhaust gas from the gas turbine device as a heat source, and a steam turbine device that uses the steam generated by the boiler device as a driving source. and a steam injection piping system for injecting steam for reducing nitrogen oxides generated by combustion into the combustor of the gas turbine device, wherein during operation of the gas turbine device, the steam injection piping system In the method for controlling a steam injection system in a combined cycle power plant in which turbine extracted steam and high-pressure main steam from the steam turbine device are introduced, heated steam from the outside is introduced into the steam injection piping system into the steam injection piping system. An auxiliary steam system for introducing the gas turbine, and a forced drain discharge system including a steam/water separator for separating the condensate from the steam in the steam injection piping are provided. A method for controlling a steam injection system in a combined cycle power plant, characterized in that the heated steam introduced therefrom is discharged from the forced drain discharge system, and the drain in the steam injection piping is removed in advance. . 2. A gas turbine device, an exhaust heat recovery boiler device that generates steam using the exhaust gas from the gas turbine device as a heat source, a steam turbine device that uses the steam generated by the boiler device as a driving source, and the gas turbine device In a combined cycle power plant equipped with a steam injection piping system for injecting steam to reduce nitrogen oxides etc. generated by combustion in a combustor, the steam injection piping system has a steam turbine installed in the steam injection piping. An extraction steam piping system that introduces extracted steam from the equipment, a backup steam piping system that introduces high-pressure main steam into the steam injection piping, an auxiliary steam piping system that introduces heated steam from outside into the steam injection piping, 1. A control device for a steam injection system in a combined cycle power plant, comprising: a forced drain discharge system including a steam/water separator for separating condensate from steam in an injection pipe.