JPS581246B2 - Steam turbine starting device with turbine bypass system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam turbine having a turbine bypass system, and particularly to a means for starting the steam turbine.

FIG. 1 shows a system diagram of a turbine having a turbine bypass system.

Turbine bypass is a system that circulates the steam generated in the boiler heater through the steam turbine, the boiler reheater, and the condenser to shorten the boiler startup time and continue independent operation within the plant. It is something to do.

With reference to FIG. 1, the flow of steam during turbine bypass system operation will be explained.

Steam generated from the heater 18 of the boiler 1 flows from the main steam system 21 into the turbine bypass system 23 and passes through the steam conversion valves (SCVs) 14 of the turbine bypass system to bias the high pressure turbine 4 and supply the steam to the boiler 1. Flows into the reheater 6.

The steam reheated through the reheater 6 is passed through the spillover valve (sO
V) 1 5 and flows into the condenser 12 from the steam system 24 .

Therefore, the intermediate pressure turbine 10 and the low pressure turbine 11 are also bypassed.

As mentioned above, the steam generated in the boiler 1 is transferred to the main steam system 21,
Turbine bypass system 23, reheat system 22, steam system 2
4 into the condenser 12, bypassing the steam turbine.

The check valve 5 is for preventing backflow of steam from the turbine bypass system 23 to the high pressure turbine 4.

The main steam system 21 from the heater 18 of the boiler 1 to the high-pressure turbine 4 includes a main steam stop valve (MSV) 2 and a main steam stop valve bypass valve (MSBV) provided in the main steam stop valve.
) 1 6 and a control valve (CV) 3 for controlling the steam flow rate, and the reheat system 22 from the reheater 6 of the boiler 1 to the intermediate pressure turbine 10 is provided with a reheat steam stop valve (RSV) 7 and a steam control valve (CV) 3 for controlling the steam flow rate. An intercept valve (ICV) 8 and an intercept valve bypass valve (ICV-BPV) 9 are provided to control the flow rate.

The condensate from the condenser 12 is fed to the heater 18 of the boiler 1 by a condensate system 25 equipped with a pump device 19.

Moreover, the generator 13 takes the load of the steam turbine.

When starting a steam turbine having a turbine bypass system, such as the above-mentioned steam turbine device, first reset the steam turbine, and then operate the main steam stop valve 2 and the reheat steam stop valve 7.
is fully opened, and the control valve 3 and intercept bypass valve 9 are gradually opened to allow steam to flow into the steam turbine and increase the load in the speed-up region.

After the intercept bypass valve 9 is fully opened, the intercept valve 8 is opened to allow even more steam to flow into the steam turbine.

As the amount of steam flowing into the steam turbine increases, the steam conversion valve 14 in the turbine bypass system 23 and the spillover valve 15 in the steam system 24 close, and eventually close completely to complete startup operation and resume normal operation. It will be in operation state.

However, the method for starting the steam turbine described above is generally referred to as partial injection starting, in which a specific valve is opened among the control valves 3, which are usually installed in plurality, to allow steam to flow into the steam turbine. As a result, the temperature distribution inside the vehicle becomes non-uniform, and cracks are likely to occur due to thermal stress.

In order to improve this shortcoming and to perform a rapid start-up, an all-around injection starting method has been adopted, but this all-around injection method for starting a steam turbine is not easily applicable to steam turbines that have a turbine bypass system. Can not.

That is, the intercept valve 8 of a steam turbine that does not have a turbine bypass system does not have an intercept bypass valve 9, and when the steam turbine is started by the all-round injection system, the situation is as shown in Table 1.

The main steam stop valve 2 and the main steam stop valve bypass valve 16 are built into the same valve body, and the main steam stop valve bypass valve 2 opens subsequently after the main steam stop valve bypass valve 16 is fully opened. Stop valve means main steam stop valve and main steam stop valve bypass valve.

Moreover, "1" in the intercept bypass valve means that the valve is provided.

In the conventional all-round injection starting method for a steam turbine as described above, in the case of a steam turbine equipped with a turbine bypass system as shown in FIG. Since the steam is flowing down, the reheat system 22 is full of steam, and if the intercept valve 8 had been fully opened in advance, steam would flow into the intermediate pressure turbine from the reheat system and cause the steam turbine to start. Due to the increase in speed, it was impossible to apply all-round injection startup, which is suitable for countermeasures against thermal stress in the casing and rapid startup of the steam turbine.

An object of the present invention is to provide a steam turbine starting means for starting a steam turbine having a turbine bypass system using an all-round injection method.

The present invention is characterized by a main steam system that supplies steam generated in a boiler heater to a high-pressure part of a steam turbine, and is equipped with a main steam stop valve having a bypass valve and a control valve that adjusts the steam flow rate. , a reheat system equipped with an intercept valve having a bypass valve that reheats the steam that has passed through the high pressure section of the steam turbine in a reheater of the boiler and then supplies it to the medium and low pressure section of the steam turbine to adjust the steam flow rate; I worked on the turbine bypass system that bypasses the steam turbine from the main steam system in front of the main steam stop valve to the boiler reheater, the steam system that branches off from the reheat system and goes to the condenser, and the steam turbine. In a steam turbine having a turbine bypass system including a condensation system that condenses steam in a condenser and then supplies the steam to a Boym heater, the bypass valve and the intercept valve of the main steam stop valve when starting the steam turbine. Both bypass valves are operated in the open direction to allow steam to gradually flow into the steam turbine, and then both the control valve and the intercept valve are operated in the open direction to generate a large amount of steam again. It flows into the turbine to start the steam turbine.

Next, one embodiment of the present invention will be described with reference to the drawings.

In the case of a steam turbine having a turbine bypass system, the reheat system 23 is filled with steam even during startup, so the intercept valve 8 and the intercept bypass valve 9 cannot be fully opened even during full-circle injection startup.

Therefore, the following control means is required.

i) A control means that fully closes the main steam stop valve 2, opens only the main steam stop valve bypass valve 16, and fully opens the moderator valve 3 at the time of starting all-around injection; 11) Intercept by fully opening the moderator valve 3 at this time; a control means for preventing the valve 8 and the intercept bypass valve from fully opening; 111) during full-circle injection activation, the main steam stop valve bypass valve 16 and the intercept bypass valve 9 are interlocked to control the amount of steam flowing into the steam turbine; 1) A control means for maintaining the opening degree of the intercept bypass valve 9 constant during the switch from full-circle injection to partial injection to avoid changes in the load of the steam turbine; and 2) Control means for switching to partial injection. The rest is a control means for controlling the steam flowing into the turbine in conjunction with the control valve 3 and the intercept bypass valve 9 or the intercept valve 8. The present invention is equipped with the above control means.

In FIG. 2, one of the output signals No of the rotation speed/load setter 101 becomes an input signal of the operational amplifier 102, which compares it with the actual rotation speed Na of the steam turbine and outputs a deviation signal between the two. The output signal further becomes an input signal to an operational amplifier 103, where it is added to a setting signal that is the output of a full-circle injection/partial injection switch (FA-PA switch) 104, and is added to a servo amplifier 105 of the main steam stop valve.
becomes the input signal.

The FA-PA switching device 104 outputs a setting signal to the main steam stop valve 2, which is a fully open signal during partial injection and a fully closed signal during full circumference injection.

The output of the servo amplifier 105 drives the coil 106 of an electro-hydraulic converter (servo valve), where the electric signal is converted into a hydraulic signal to operate the hydraulic mechanism 131 that opens and closes the main steam stop valve. 2 and the opening degree of the main steam stop valve bypass valve 16 is adjusted.

The opening degree of the main steam stop valve 2 is converted into an electrical signal by, for example, a differential transformer 107 and fed back to the servo amplifier 105 to obtain localization.

On the other hand, the other output signal of the speed/load setter 101 becomes an input signal of the operational amplifier 108, which compares it with the actual rotational speed Na and outputs a deviation signal between the two.

This output signal is divided into three parts, one is an operational amplifier 109
becomes the input signal.

The operational amplifier 109 uses a full-circle injection/partial injection switch (FA).
-A setting signal which is the output of the PA switch) 110, and becomes the input signal of the control valve servo amplifier 111.

Both FA/PA switchers 4 and 10 are mechanically interlocked, and when one is in the FA position, the other adjusts the magnitude of the setting signal so that it is in the PA position.

The output signal of the servo amplifier 111 is transmitted to the coil 1 of the servo valve.
12. A hydraulic mechanism 132 that opens and closes the adjustment valve 3 operated by the coil 112 and a differential transformer 113 form a servo loop to control the opening and closing of the adjustment valve 3.

One of the output signals of the output signal 108 of the operational amplifier 108 becomes an input signal of the servo amplifier 114 for the intercept bypass valve 9, and the coil 115 of the servo valve, the coil 1
A hydraulic mechanism 133 that opens and closes the intercept bypass valve 9 operated by the servo loop 133 and the differential transformer 116 operate by a servo loop to control the opening and closing of the intercept bypass valve 9.

One of the output signals of the operational amplifier 108 becomes an input signal of the operational amplifier 117, where it is compared with the output signal of the bias setting device 118 that sets the opening start of the intercept valve, and a difference signal between the two is output.

The bias setting device 118 is set so that the intercept valve starts opening after the intercept bias valve 9 is almost fully opened.
The purpose is to set a reverse bias on the output signal of operational amplifier 108.

The output signal of the operational amplifier 117 becomes the input signal of the servo amplifier 119 of the intercept valve 8, and the coil 120 of the servo valve, the hydraulic mechanism 134 that opens and closes the intercept valve 8 operated by the coil 120, and the differential transformer 121.
A servo loop is configured to control the opening and closing of the intercept valve 8.

Table 2 shows the all-round injection starting method using the starting device for a steam turbine having these turbine bypass systems.

In Table 2, the reason why the intercept valve 8 is fully open or in controlled operation during all-round injection activation is because if the intercept bypass valve 9 is not fully open, the intercept valve 8 is in fully closed operation, and the intercept bypass valve 9 is fully open. The rest is controlled driving.

In addition, in FIG. 2, FA/PA switching devices 104, 110
The position indicates the position of FA.

That is, the bias value of this switch for the main steam stop valve 2 is 0, and the bias value for the control valve 3 is set to the maximum, so that the control valve is fully opened.

As the switch 110 is switched from FA to PA, the bias value to the regulator valve 3 gradually decreases, and the bias value finally reaches 0 as the regulator valve 3 moves in the closing direction.

On the other hand, the bias value of the main steam stop valve 2 gradually increases and the main steam stop valve moves in the opening direction, and finally reaches the maximum bias value and the main steam stop valve 2 fully opens, completing the switching and steaming. Full-circle injection start-up of the turbine is achieved.

FIG. 3 shows the operation status of each valve of a steam turbine having a turbine bypass system when the present invention is used.

As is clear from the figure, the intercept bypass valve (ICVBPV) 9 is the main steam stop valve (MSV) during all-round injection activation.
It opens in the same way as 2, and controls the control valve (CV) during partial injection activation.
It is open like 3.

Further, during FA/PA switching, the opening degree of the intercept bypass valve (ICVBPV) 9 is constant regardless of the movements of MSV and CV.

In other words, since F A/P A switching is performed after system parallelization, it does not affect the steam turbine speed.

The intercept valve (ICV) 8 is configured by setting the bias setting device 118 in FIG.
It opens at the same time as V9 is fully opened, allowing reheated steam to flow into the steam turbine.

According to the present invention, even in a steam turbine equipped with a turbine bypass system, the steam turbine can be started using the all-round injection method C, and the thermal stress generated in the casing and turbine rotor of the steam turbine can be reduced. is achieved.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a steam turbine plant having a turbine bypass system, Fig. 2 is an all-round injection starting device which is an embodiment of the present invention, and Fig. 3 is a diagram showing the operation status of steam valves in all-around injection starting. FIG. Explanation of symbols, 1...Boiler, 2...Main steam stop valve, 3...Adjustment valve, 4...High pressure turbine, 6... ... Reheater, 7 ... Reheat steam stop valve, 8 ... Intercept valve, 9.
...Intercept bypass valve, 10...
・Intermediate pressure turbine, 11...Low pressure turbine, 12
...Condenser, 16...Main steam stop valve bypass valve, 18...Heater, 21...
Main steam system, 22... Reheat system, 23...
... Turbine bypass system, 24 ... Steam system, 101 ... Rotation speed/load setting device, 102 ...
... operational amplifier, 103 ... operational amplifier,
108... operational amplifier, 109... operational amplifier, 117... operational amplifier, 104...
...FA/PA switch, 110...F A
/PA A switch, 105... Servo amplifier, 1
11... Servo amplifier, 114... Servo amplifier, 119... Servo amplifier, 118
...Bias setting device.

Claims (1)

[Claims] 1. A main steam system that supplies steam generated in a boiler heater to a high-pressure section of a steam turbine and is equipped with a main steam stop valve having a bypass valve and a control valve that adjusts the steam flow rate, and a high-pressure section of the steam turbine. The steam that has passed through the boiler is reheated in the reheater of the boiler and then supplied to the medium and low pressure section of the steam turbine. There is a turbine bypass system that bypasses the steam turbine from the main steam system of the boiler to the inlet of the boiler's reheater, a steam system that branches off from the reheat system and reaches the condenser, and a steam system that carries the steam that has done work in the steam turbine. In a steam turbine having a turbine bypass system that includes a condensate system that condenses water in a condenser and then supplies it to a boiler heater, a speed signal of the steam turbine and a speed setting signal are compared and a deviation signal is output. A first arithmetic unit, a second arithmetic unit, a switching device that changes a setting signal according to selection of full-circle injection start or partial injection start, a setting signal changed by the switching device and an output of the first arithmetic unit a third computing unit that adds the signals; a fourth computing unit that adds the setting signal changed by the switching device and the output signal of the second computing unit; A first calculator comprising a fifth calculator that calculates an operation signal to a hydraulic device that drives the stop valve and the bypass valve of the main steam stop valve, and returns the operation amount of the hydraulic device to the fifth calculator as a return signal. a servo loop, a sixth computing unit that computes an operation signal to a hydraulic system that drives a regulating valve in accordance with an output signal of a fourth computing unit, and the sixth computing unit uses an operating amount of the hydraulic system as a return signal. a second servo loop that returns to the second servo loop, and a seventh computing unit that computes an operation signal to the hydraulic system that drives the bypass valve of the intercept valve according to the output signal of the second computing unit, and operates the hydraulic system. a bias setting device that generates a third servo loop bias signal for returning the quantity as a return signal to a seventh arithmetic unit, and comparing the output signal of the second arithmetic unit with the bias signal of the bias setting device; , the eighth outputting the deviation signal
a ninth computing unit that computes an operating signal to the hydraulic system that drives the intercept valve according to the output signal of the eighth computing unit; A steam coupin starting device having a turbine bypass system configured with a fourth servo lube that returns to a computing unit.