JPS5838309A - Uniaxial type composite generating plant - Google Patents

Abstract

PURPOSE:To enable to perform a safe operation of a composite generating plant, by a method wherein, in a subject plant provided with a gas turbine and a steam turbine, a regulating valve of a steam turbine is controlled by means of a steam pressure deviation, deviation of the number of revolutions, and a load limit signal. CONSTITUTION:A composite generating plant is provided with a gas turbine and a steam turbine. Based on a pressure set value 22 and an actual steam pressure 21, an operating signal 26 for a bypass valve is computed. A regulating valve operating signal 27 is selected from 3 factors of a regulating valve control signal 38 by deviation of the number of revolutions and a load limit signal 36 in addition to a steam pressure deviation 26. This enables to hold a steam pressure in a stabilizing manner, and permits the steady and safe operation of the composite generating plant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single-shaft exhaust heat recovery type combined cycle power plant in which a gas turbine, a steam turbine, and a generator are connected in series to a single shaft, and particularly relates to a control system for a steam turbine control valve. Kansui.

In general, is exhaust heat recovered from gas turbines? In a so-called single-shaft M11 combined power generation plant, a steam turbine is connected in series with a single shaft to convert the rotational energy of these turbines into electric energy. The generated power output is determined by the fuel supplied to the gas turbine.@4IK In the 7P combined cycle power generation system with no auxiliary combustion due to exhaust heat recovery, the power generation output cannot be generated by a steam turbine. Depends on exhaust heat co-conditions.

Due to this, the steam turbine control valve in the F-011 type combined power generator has been operated in a fully open state during normal operation.

On the other hand, the pressure of steam at which exhaust heat recovery generates Ij1c' changes approximately in proportion to the load of the gas turbine. Therefore, steam turbines are forced to operate under variable pressure depending on the load. This is not desirable for the steam turbine, as there is a risk that the temperature will increase and promote erosion of the steam turbine.

Figure 1 shows a general table schematic configuration diagram of a single-shaft type waste heat recovery combined cycle power plant, where l is a fundare, 2 is a gas turbine, 3 is a generator, 4 is a steam turbine, and 5 is a 6 is a condenser, 7 is a water ponder, and 8 is a combustor.

In the combustor 8, a fuel adjustment valve 9t is passed through the combustor 8, and an amount of fuel corresponding to the load command is supplied to the combustor 8.

Compressed air necessary for combustion of the fuel is sent from the combustion chamber 1 , which is combusted by the combustion WF 8 , and then high-temperature and high-pressure combustion gas is sent to the gas turbine 2 . This gas turbine 2 is driven by the high-temperature and high-pressure gas, and drives a generator 3, a compressor 1, and a steam turbine 4 that are directly connected to this shaft. However, the steam turbine 4 does not recover exhaust heat? At the inlet 5, when the steam generated by the exhaust gas discharged from the gas turbine 2 flows through the generator 3 and the exhaust gas, the combustion gas that has completed the above-mentioned work at the gas turbine 2 is used for exhaust heat recovery. 5) It is led to 5, and the water is supplied from the condenser 6 by the water supply point yf7. After converting the feed water delivered to Inn 5 into steam,
released into the atmosphere. Exhaust heat recovery? stomach? The steam generated by the steam turbine 5 is guided to the condenser 6 via the steam turbine control valve 101, the steam turbine 4, or the λ-earth valve 11Yt, and is condensed.

Now, uniaxial m compound power generation f? having the above-mentioned configuration? Exhaust heat recovery at the project? The steam generated in the inlet 5 is discharged from the gas turbine 2 when the load is low.
Because the amount of fi is small, the pressure and temperature that are sufficient to drive the steam turbine pipe cannot be reached.
1 to the condenser 6 directly, and the regulator valve 1o is closed to the steam turbine 4 to prevent the flow from flowing into the steam turbine 4. Eventually, when the load normally increases to about 25 hiss or more, the generated steam also becomes high pressure, so the regulator Open valve 10, close valve 11,
This will drive the steam turbine 4. However, the steam pressure generated at the exhaust heat recovery stage is sent out to the
is proportional, so the generated steam pressure will fluctuate greatly due to changes in operating load. The purpose of the pinhole valve 11 is to lower the steam pressure by protecting the steam turbine system, that is, the steam turbine 4 and steam piping, and for safe operation when the steam pressure becomes higher than the set pressure. protection,
The pinos valve 11 has no effect unless the pressure set for safety is higher than the set pressure.In other words, the bypass valve 11 reduces the steam pressure flowing into the steam turbine 4 in response to fluctuations in steam pressure below the set pressure. However, the control function of the control valve 10 is not so good, and the control valve 10 has not conventionally been provided with this function.

FIG. 2 shows a control diagram of such a conventional bypass valve during normal operation.The deviation calculator 23 calculates the pressure deviation 24 from the steam pressure set value 21 and the actual steam pressure 22.
is calculated and converted into a pinot master valve operation signal 26 by the bypass valve adjustment tt (Gt) 25, and the bypass valve 11 is operated. On the other hand, when the steam turbine is driven by steam, the control valve 10 is fully open as described above.

In the present invention, exhaust heat recovery is generated by inlet and steam pressure O
The object of the present invention is to provide a single-shaft combined power generation unit capable of supplying stable steam to a P1 steam turbine by controlling pressure fluctuations using a regulating valve.

The present invention will be described below with reference to the embodiments shown in the figures. Figure 3 shows a control system according to an embodiment of the present invention, with a pressure setting value 21 and an actual steam pressure 22t. - Based on the operation signal 26 of the bypass valve, the operation signal 26 is the same as in Fig. 2, but a control system for operating the regulator valve 1° is added, and the steam pressure deviation is used as the control signal for operating the regulator valve 'Ik. In addition, the control valve is controlled by three signals: a control valve control signal based on rotational speed deviation and a load limit signal.In other words, in this embodiment, the control valve is controlled by three signals: Without directly operating the pi/gas valve 11'l with the piis valve operator No. 26,
Control valve operation signal 271 is operated by a signal 29 corrected and subtracted by deviation calculator 28.

On the other hand, the adjustment valve is controlled by the conventional pinot bus valve operation signal 26, that is, the control signal based on the main steam deviation, and the adjustment valve controller ( 3Il of the control valve control (operation) signal 35 and the load limit signal 36, which are controlled and calculated by G,) 34.
The control signal of
Select the minimum control signal and obtain the final operation signal 27 of the control valve.
The steam pressure control function is achieved by controlling the regulating valve.

The control valve operation signal 27 includes not only the control signal 26 based on the steam pressure deviation signal but also the control signal 35 based on the rotation speed deviation.
and the control system using the load limit signal 36. Originally, the rotational speed of the combined power generation unit is determined by the gas turbine, but in transient conditions such as load fluctuations, rotational speed deviation occurs, so the steam turbine It was an attempt to actively contribute to rotation speed control on the side as well, and the load limit signal 36
is added to prevent the control valve from being operated too rapidly even in such a transient state.

As described above, according to the present invention, the control valve of the steam turbine f is controlled during operation, so that the steam pressure can be kept stable, and even when the steam turbine load fluctuates, the control valve can be controlled. , single-shaft combined cycle power generation that allows safe operation! Tsunt is obtained.

[Brief explanation of the drawing]

Fig. 1 is a general configuration diagram of a single-shaft combined cycle power plant, Fig. 2 is a diagram of a conventional control system for a steam system in the combined cycle plant, and Fig. 3 is a control block according to an embodiment of the present invention. Illustrated. 1... Combrev, 2... Gas turbine, 3...
- Generator, 4...Steam turbine, 5...Exhaust heat recovery in, 6...Condenser, 7...Water pump, 8...-
Combustor, 9... Combustion adjustment valve, 10... Adjustment valve, 11
... Pinotas valve, 21 ... Steam pressure setting value, 22
...Actual steam pressure, 23.Difference calculator, 24.
...Pressure deviation, 25...Pais valve adjustment needle (Gs
), 26.29...Piece valve operation signal, 27...
Adjustment valve operation signal, 28... Deviation calculator, 30... Rotation speed setting value, 31... Rotation speed signal, 32... Deviation calculator, 33... Rotation speed deviation signal, 34... - Rotation speed adjustment needle (G3), 35...Adjustment valve control signal based on rotation speed deviation, 36...Load limit signal, 37...Low value priority device. (7317) Representative Patent Attorney Kensuke Noriyuki Chika (and 1 other person) Hayabusa 1 Figure Hayabusa 20 #3 Procedure Amendment (Voluntary) December 25, 1939 Director General of the Japan Patent Office 1, Patent Application for Indication of Case No. 56-134326 2, Title of invention Control method for combined cycle power generation plant 3, Relationship with the amended case Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 4, Agent Address: 1 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100 -1-6 Tokyo Shibaura Electric Co., Ltd. Kinsha Tokyo Office (1) Full text of the specification and drawing 6, contents of amendments as shown in the appendix Description 1, Name of the invention Control method for a combined cycle power plant 2, Scope of claims ( 2. The combined power generation plant according to claim 1, wherein the control valve is controlled by the first of three signals: a steam pressure deviation signal, a rotational speed deviation signal, and a load limit signal. 1. Above m 3.Detailed Description of the Invention The present invention relates to a gas turbine, #l+heat recovery boiler.It relates to a method for controlling a combined cycle power generation plant for exhaust heat recovery, which is composed of a steam turbine and a generator.Generally, gas In a combined power generation plant, the exhaust heat of the turbine is converted into steam energy by an exhaust heat recovery boiler, this steam further drives a steam turbine, and the rotational energy of the gas turbine and steam turbine is converted into electrical energy by a generator. The power generation output that can be generated is almost determined by the fuel supplied to the gas turbine.Especially in the case of a power generation plant in which there is no auxiliary combustion in the exhaust heat recovery boiler, the power generation output that can be generated by the steam turbine depends on the exhaust heat conditions of the gas turbine. For this reason, the control valve that controls the amount of steam flowing into the steam turbine in this type of combined cycle power plant has been operated in a fully open state during normal operation, allowing the generated steam to directly flow into the steam turbine. Therefore, the pressure of the steam generated in the waste heat recovery boiler changes depending on the load on the gas turbine, so the steam turbine is forced to operate at variable pressure depending on the load.However, in partial load operation, the pressure of the steam generated, As the temperature decreases, the humidity of the steam increases as the steam temperature decreases in the low-pressure stage of the steam turbine, and there is a risk of promoting double lotion in the steam turbine, which is not desirable for the steam turbine. This figure shows an example of a general schematic configuration diagram of a type exhaust heat recovery type combined cycle power generation plant, where 1 is a compressor, 2 is a
3 is a gas turbine, 3 is a generator, 4 is a steam turbine, 5 is an exhaust heat recovery boiler, 6 is a condenser, 7 is a feed water pump, and 8 is a combustor. With this configuration, the amount of fuel according to the load command and the compressed air necessary for combustion of the fuel are sent from the compressor l to the combustor 8 through the fuel adjustment valve 9, and the high temperature and high pressure combusted in the combustor 8 The combustion gas is sent to the gas turbine 2. This gas turbine 2 is driven by the high-temperature and high-pressure gas, and drives a generator 3, a compressor 1, and a steam turbine 4 that are directly connected to this shaft. However, the steam turbine 4 serves as a power source for driving the generator 3 and the compressor 1 together with the gas turbine 2 when the steam generated by the exhaust gas discharged from the gas turbine 2 flows into the exhaust heat recovery boiler 5 . The combustion gas that has completed the above-mentioned work in the gas turbine 2 is led to the exhaust heat recovery boiler 5, and after converting the feed water sent from the condenser 6 to the boiler 5 by the feed water pump 7 into steam, it is Atmospheric pressure is released. The steam generated by the exhaust heat recovery boiler 5 passes through the steam turbine control valve 10 to the steam turbine 4 or the bypass valve 11.
The water is guided to the condenser 6 and condensed. Now, in the single-shaft combined cycle power plant having the above configuration, the steam generated in the heat recovery boiler 5 is not sufficient to drive the steam turbine because the flow rate of exhaust gas discharged from the gas turbine 2 is small when the load is low. Sufficient pressure and temperature are not reached. For this reason, the steam is made to flow directly into the condenser 6 via the bypass valve 11, and is not allowed to flow into the steam turbine 4 by closing the control valve IO. Eventually, when the load becomes more than the normal 25 -, the pressure of the generated steam also becomes high, so the control valve 10 is opened, the bypass valve 11 is closed, and the steam turbine 4 is driven. However, since the steam pressure generated in the exhaust heat recovery boiler changes depending on the amount of exhaust gas sent out from the gas turbine 2, that is, the operating load, the generated steam pressure also fluctuates greatly due to changes in the operating load. The bypass valve 11 is used to maintain the steam turbine system, that is, the steam turbine 4 and the steam piping, and to lower the steam pressure when the steam pressure becomes higher than the set pressure. The bypass valve 11 has no effect unless the pressure is higher than the preset pressure for safety reasons. That is, the bypass valve 11 does not have a function of controlling the steam pressure flowing into the steam turbine 4 in response to fluctuations in steam pressure below a set pressure, and the regulating valve 10 has not conventionally had this function. Figure 2 shows an example of a control block diagram of such a conventional bypass valve during normal operation.
and the actual steam pressure 21, the pressure deviation 2 is calculated by the deviation calculator 23.
4 is calculated and converted into a bypass valve operation signal 26 by the bypass valve adjustment needle (Gl) 25K, and the bypass valve 1 is
1 is operated. On the other hand, the control valve 10 is fully open as described above when the steam turbine is being driven at once. The present invention supplies stable steam to a steam turbine by controlling the fluctuations in steam pressure generated by an exhaust heat recovery boiler using a single pressure setting device, usually a control valve, and also prevents the pressure from becoming abnormally high. To provide a control method for a combined power generation plant that can prevent the overspeed of a steam turbine by controlling a regulating valve 10 to control rotational speed fluctuations of the steam turbine itself, as well as maintaining it with a bypass valve when purpose. Hereinafter, the present invention will be explained with reference to the embodiments shown in the figures. 's3
The figure shows a control block diagram according to an embodiment of the present invention, and the part where the bypass valve operation signal 26 is calculated based on the pressure setting value 22 and the actual steam pressure 21 is the same as in Figure 2. However, a control system for operating the regulating valve 10 is added,
A feature of the present invention is that the control valve is controlled by not only the steam pressure deviation, but also a control signal for controlling the control valve based on the rotational speed deviation and a load limit signal as the control signal for operating the control valve. That is, in this embodiment, the bypass valve 11 is not directly operated by the bypass valve operation signal 26 shown in FIG. On the other hand, the regulator valve is controlled by the conventional bypass valve operation signal 26, that is, the control signal based on the main steam pressure deviation, and the regulator valve adjustment needle (G ,
) 34, the control signal 35 and the load limit signal 360 select the lowest control signal using the low value priority device (LVG) 37, and perform the final operation of the regulator valve. The signal 27 serves as a steam pressure control function by controlling the regulating valve. Control valve operation signal 2
7, the control system was created using not only the control signal 26 based on the steam pressure deviation signal, but also the control signal 35 based on the rotational speed deviation and the load limit signal 36, because originally the rotational speed of the combined cycle power plant was determined almost entirely by the gas turbine side. However, under transient conditions such as a sudden load reduction, rotational speed deviation occurs, so the steam turbine side also actively tried to contribute to rotational speed control.Also, even under normal conditions, pressure deviation By lowering the rotation speed setting value 30 or lowering the pressure setting value 22 to reduce the deviation, it is possible to give priority to the rotation speed control system, and active governor control is performed to suppress frequency fluctuations in the system. It is also possible to do this. The load limit signal 36 is added for the purpose of preventing the control valve from being excessively operated in the opening direction even when an excessive frequency drop occurs during synchronous parallel operation. As described above, according to the present invention, the steam pressure is kept stable by controlling the control valve of the steam turbine during operation, and the steam turbine itself is also operated when the frequency decreases due to overspeed such as load cutoff or system failure. A combined power generation plant that prevents sudden increases in output and can operate stably and safely even when the steam turbine load fluctuates can be obtained. 4. Brief explanation of the drawings Figure 1 shows a combined power generation plant. FIG. 2 is a conventional control block diagram of the steam system in the combined power generation plant, and FIG. 3 is a control block diagram according to an embodiment of the present invention. 1...Compressor, 2...Gas turbine, 3...
・Generator, 4A steam turbine, 5...Exhaust heat recovery boiler, 6...Condenser, 7...Water pump, 8...Combustion spring 9...Combustion adjustment valve, 10... - Adjustment valve, 11...Bypass valve, 21...Actual steam pressure value, 22...Steam pressure set value, 23...Difference calculator, 24...Pressure deviation, 25...Bypass valve 11 Sekkei (G1), 26
, 29... Bypass valve operation signal, 27... Adjustment valve operation signal, 28... Deviation calculator, 30... Rotation speed setting value, 31... Rotation speed signal, 32... Deviation calculation vessel,
33... Rotation speed deviation signal, 34... Rotation speed controller r
Gg), 35... Regulating valve control signal due to rotation speed deviation,
36...Load limit number, 37...Low value priority device. (7317) Agent Patent Attorney Kensuke Norichika 1st
figure

Claims (2)

[Claims] (1) In a single-shaft combined power generation system in which the shafts of a gas turbine and a steam turbine are combined, exhaust heat recovery is achieved by controlling the pressure of the steam generated by the steam turbine with the control valve of the steam turbine, which easily changes depending on the load. A single-shaft combined cycle power generator characterized by maintaining the steam pressure generated by the exhaust heat recovery I-ra at a constant level, allowing stable steam to flow into the steam turbine, and enabling safe operation even under partial load. (2) In the scope of claim 1, the control valve! Control should be performed using the minimum signal among the three signals: steam pressure deviation signal, rotation speed deviation signal, and load limit signal.
Features of the single-shaft combined power generation ZORAN F.