JPS60204906A - Turbine bypassing control device - Google Patents

Abstract

PURPOSE:To securely reduce the temperature of a steam exhausted into a condenser by opening a bypass valve after opening a spray valve while, upon closing the bypass valve, leaving the spray valve opened until the bypass valve has been fully closed. CONSTITUTION:A turbine bypass control device controls a bypass valve 13 of a low pressure turbine bypass line and a spray valve 17 for allowing return water to pass through a temperature reducer. Upon issuing an instruction v1 that opening of the bypass valve is fully closed at timing t4, a full-close-bypass valve detector 15-6 is not operated and a contact 15-7b is closed. Accordingly, the spray valve 17 is left fully closed. Upon reaching timing t5, the actual opening v3 of the bypass valve is fully closed and further a reray 15-7b is energized at timing t6 to cause the spray valve 17 to start to be fully opened. Thus, steam exhausted from the bypass valve to a condenser is securely reduced in its temperature whereby enabling the condenser from being deteriorated.

Description

Detailed Description of the Invention (Technical Field of the Invention 1) The present invention relates to a turbine bypass control device that cools steam that has passed through a low-pressure turbine bypass valve by spraying condensate and introduces it into a condenser. It is.

[Technical background of the invention and its problems 1 The configuration of a general turbine bypass system is shown in FIG. 1.

In Figure 1, the steam generated in the boiler 1 is transferred to the main steam stop valve 2, the steam control valve 3, the high pressure turbine 4, and the high-pressure exhaust reverse IL.
The steam is exhausted to a condenser 10 through a valve 5 , a reheater 6 , a reheat steam valve 7 , an intermediate pressure turbine 8 , and a low pressure turbine 9 .

Furthermore, there is a high-pressure turbine bypass line that drops steam from before the main steam stop valve 2 to the inlet of the reheater 6 through the high-pressure turbine bypass valve 11.

In this case, since the steam generated from the boiler is high temperature and high pressure, water is injected from the water injection valve 12 to the high pressure turbine bypass valve,
The steam is cooled and depressurized before being released.

Also, from before the reheat steam valve 7, the low pressure turbine bypass valve 1
3, there is a low pressure turbine bypass line that reduces the temperature in an attemperator 14 and drops it into the condenser 10.

In this case, the opening degree of the low-pressure turbine bypass valve 13 is adjusted by the bypass valve control device 15, but the steam at this time cannot be directly exhausted due to its high temperature and large amount. 14 to reduce the temperature to about the saturation temperature in the condenser.

Temperature reduction is accomplished by directing condensate from the discharge of condensate booster pump 16 into the attemperator through spray valve 17.

The spray valve 17 is fully open when the low-pressure turbine bypass valve 13 is fully open because it does not need to be opened, and the spray valve interlock is set so that the spray valve is fully open when the low-pressure turbine bypass valve 13 is not fully open. The logic is incorporated into the bypass valve control wi[15 to fully close/open the spray valve 17.

The low pressure turbine bypass valve 13 and spray valve 171'
) The opening/closing timing diagram is shown in Figure 2.

As is clear from Figure 2, the spray valve is opened/closed near the low pressure turbine bypass valve fully closed position, so the period from [1 to At t2, steam whose temperature has not been reduced is exhausted to the condenser, and from t3 to t4, when the spray valve starts to open and the spray water pressure reaches the specified value, steam whose temperature is higher than the specified temperature is exhausted to the condenser. will be done.

This situation does not pose a problem if the low-pressure turbine bypass valve opens very slowly or the low-pressure turbine bypass valve opens very few times, but if the low-pressure turbine bypass valve opens due to load interruption or turbine trip, etc. When the condenser is suddenly opened, a large amount of high-temperature steam is exhausted into the condenser, which significantly shortens the life of the condenser's cooling pipes and may even lead to their destruction.

In addition, in power plants that operate under open loads, there is a problem in that the low-pressure turbine bypass valve is opened and closed frequently in order to start and stop the turbine every day, causing deterioration of the condenser.

Note that when the low pressure turbine bypass valve changes from open to fully open, there is no problem because the spray valve opens fully after the low pressure turbine bypass valve becomes fully open, as shown at t4 to [6 in FIG. 2.

[Object of the Invention] An object of the present invention is to provide a turbine bypass control device that prevents untemperatured steam from being exhausted to a condenser when a low-pressure turbine bypass valve opens from a fully open position.

[Summary of the Invention] The present invention controls a bypass valve that passes steam in a low-pressure turbine bypass line and a spray valve that passes condensate to an attemperator that cools the steam in the bypass line to return the cooled steam. In a turbine bypass control device for exhausting water to a water dispenser, the bypass valve is enabled to open when the spray valve is open, and the spray valve is opened while the bypass valve is given an open command or the bypass valve is open. Bypass valve and spray valve control devices are provided to ensure that the bypassed steam is cooled and exhausted to the condenser.

[Embodiments of the invention] An embodiment of the present invention is shown in FIG.

In Fig. 3, the part 15 within the dashed line frame is the bypass valve control device, and the command value 1 output from the bypass valve command value generator 15-1 indicates that the spray water pressure of the multiple spray valves is equal to or higher than the specified value. It passes through contact 15-12a, which is closed, and becomes v2, which is input to adder 15-2.

On the other hand, the command value ■1 is input to the bypass valve open command detector 15-3, and when it is detected that the command value is greater than the fully open value, that is, the value that opens the bypass valve, the relay 15-4 is energized, and the contact Close 15-4a.

The bypass valve opening detector 15-5 detects the actual opening of the low-pressure turbine bypass valve 13, and the opening signal v3 is input to the bypass valve fully closed detector 15-6 to indicate that the opening is less than fully open. When detected, relay 15-7 is energized and contact 15
-Open 7b.

The adder 15-2 inputs the command 1iv2 and the actual opening v3, and inputs the difference signal 4 to the bypass valve opening adjuster 15-8, and adjusts the low-pressure turbine so that the difference signal 4 becomes zero. A signal ν5 for adjusting the opening degree of the bypass valve 13 is output to the low pressure turbine bypass valve 13.

The spray valve full open bias 15-9 outputs a signal v6 that fully opens the spray valve, and the signal @v6 is the contact point of the relay 15-4 operated by the bypass valve open command detector 15-3, that is, the bypass valve opening command is fully opened. Contact 15-4a, which closes when the above occurs, or bypass valve fully open detector-15-6
Contact point 15-7 of relay 15-7 operated by , that is, contact point 15- which closes when the low pressure turbine bypass valve opening degree is fully open or more.
spray valve opening regulator 15- as a signal v7 through b.
10 is input.

The spray valve opening degree regulator 15-10 is a regulator that fully opens the spray valve when v7 has a bias to fully open the spray valve, and fully closes the spray valve when there is no bias to fully open the spray valve.
V8 is output to the spray valve 17.

When the spray valve 17 is fully opened and the spray water reaches a specified pressure, the spray water pressure detector 15-II detects this and operates the relay 15-12.

The operation of the present invention will be explained below with reference to the bypass valve-spray valve timing diagram shown in FIG.

Before the point in time, the bypass valve opening command v1 and the bypass valve actual opening are fully open, and the bypass valve opening command detector 15-
3 is not operating and the contact 15-4a of the relay 15-4 is open, and the bypass valve fully open detector 15-6 is also operating and the contact 15-7b of the relay 15-7 is also open.

Therefore, the spray valve fully open bias signal v6 is not input to the spray valve opening degree regulator 15-10, the spray valve 17 is fully opened, the spray water pressure is higher than the specified value, the spray water pressure detector does not operate, and the relay Contact 15 of 15-12
-12a is open, and the bypass valve opening adjustment signal v5 is a closing signal.

When bypass valve opening command ■1 changes from fully closed to open at time t1, bypass valve opening command detector 15-3 operates, and relay 1
5-4 is energized and the contact 15-48 is closed, and as a result, the spray valve fully open bias 6 is input to the spray valve opening adjuster 15-10, and the spray valve 17 moves in the opening direction, and at time t2. When the spray water pressure of the spray valve reaches the specified value, the spray water pressure detector 15-11 is activated, the relay 15-12 is energized, the contact 15-12a is closed, and the bypass valve command v1 is set to the adder 15-1. 2, the bypass valve actual tM[v3 starts changing in the opening direction, and at time t
3, the bypass valve fully closed detector 15-7 becomes inoperative, the relay 15-7 becomes non-energized, and the contact 15-7b becomes closed.

Next, at time t4, when the bypass valve opening command v1 is changed from open to fully open, the bypass valve open command detector 15-3 becomes inoperable and the relay contact 15-4a opens. Closed detector 15-6 is inoperative and contact 15-7
b is closed, the spray valve fully open bias 7 does not become zero, and the spray valve 17 continues to be fully open.

When time point [5] is reached, the bypass valve actual opening degree v3 becomes fully open, and furthermore, at time point t6, the bypass valve fully closed detector 15-6 is activated, the relay 15-7 is energized, and the contact point 15-1b is opened. Only then does the spray valve fully open bias v7 become zero, and the spray valve starts to change in the direction of 0 ports until time t7.
When the spray water pressure falls below the specified level, relay 15-12
is de-energized, contacts 15-12a are opened, and a standby state is entered for the next operation.

As a result, the command signal for the low-pressure turbine bypass valve is output only when the spray valve is fully open and the spray water pressure is above the specified value.Furthermore, the bypass valve is fully open even when the bypass valve is changed from open to fully open. Since the spray valve is fully open until this time, undehumidified steam will not be exhausted to the condenser through the bypass valve.

In the above embodiment, the spray water pressure detector 15-11 detects whether the spray valve is open, but a spray valve opening detector may also be used. Further, instead of turning on/off the bypass valve opening command under the spray valve opening condition 15-12a, the deviation signal (4) or the adjustment signal v5 may be turned on/off.

[Effects of the Invention] As explained above, according to the present invention, the bypass valve is opened after the spray valve is opened, and when the bypass valve is closed, the spray valve is kept open until the bypass valve is completely closed. A rational turbine bypass control device that reliably dehumidifies the steam exhausted from the valve to the condenser without adversely affecting the condenser can be obtained.

[Brief explanation of drawings]

Figure 1 is a general configuration diagram of a turbine bypass system.
Figure 2 is a conventional bypass valve-spray valve timing diagram.
FIG. 3 is a circuit diagram of a bypass valve control device showing an embodiment of the present invention, and FIG. 4 is a timing diagram of the Hyper 2 valve-spray valve in the present invention. 1...Boiler 4...High pressure turbine 6...Reheater 7...Reheat steam valve 8...Intermediate pressure turbine 9...Low pressure turbine 10...
- Condenser 13...Low pressure turbine bypass valve 14...Desuperheater 15...Bypass valve control device 16
... Condensate booster pump 17 ... Spray valve agent Patent attorney Noriyuki Chika (and one other person) Fig. 1 Fig. 2

Claims (1)

[Claims] Turbine bypass control I that controls a bypass valve that passes steam in a low-pressure turbine bypass line and a spray valve that passes condensate to an attemperator that cools the steam in the turbine bypass to exhaust the cooled steam to the condenser. In the apparatus, a bypass valve and a spray valve that enable the bypass valve to open when the spray valve is open and open the spray valve while the bypass valve is open and when the bypass valve is given an open command. A turbine bypass control device 1B characterized in that it is equipped with a m control device.