JP2588243B2 - Reheat steam stop valve operation test controller for steam turbine plant - Google Patents

Description

The present invention relates to a steam turbine plant, and more particularly, to an operation test of a reheat steam stop valve provided at an inlet of a low-pressure turbine during plant operation. The present invention relates to a reheat steam stop valve operation test control device used when carrying out the following.

(Prior art) In a steam turbine plant using a reheat cycle method, steam that has expanded and cooled to a low temperature in a high-pressure turbine is heated in a reheater and guided to a low-pressure turbine as superheated steam. It is preferred for large-capacity steam turbine plants with the intention of maximizing it. Less than,
An example of the steam turbine plant using the reheat cycle method will be described with reference to the drawings.

In FIG. 3, the steam generated by the steam generator 1 is guided to a high-pressure turbine 3 through a main steam pipe 2, expanded and worked, and then separated into a moisture separator 5 through a low-temperature reheat steam pipe 4. It is led to. The moisture separator 5 is constituted by arranging corrugated plates in a multilayer structure, and removes moisture contained in main steam while passing through the corrugated plates. Further, the main steam flows outside the heaters 6 and 7 which are separated by a heat transfer wall inside and outside, and is heated while flowing therethrough, and changes state from saturated steam to superheated steam. During this time, the superheated steam flowing inside the heaters 6 and 7 is guided through a heated steam pipe 8 connected to an appropriate stage of the high-pressure turbine 3 and a heated steam pipe 9 connected to the main steam pipe 2.

The main steam, which has stored energy as superheated steam, is led through a high-temperature reheat steam pipe 10 to a low-pressure turbine 11, where it works again, is discharged to a condenser 12, and is condensed by cooling water. Thereafter, the condensate extracted from the condenser 12 by the condensate pump 13 is extracted from the low-pressure turbine 11 while passing through the low-pressure feed water heater 14, and is heated by steam sent through the bleed pipe (not shown). Water supply pump 15
And is sent to the high pressure feed water heater 16, heated by the steam extracted from the high pressure turbine 3 and guided by the bleed pipe 17, and sent to the steam generator 1.

On the other hand, the heating steam whose heat is retained by the main steam while flowing in the heaters 6 and 7 is condensed, and a large amount of drain is generated. This drain is once collected in the heater drain tanks 20 and 21 through the heater drain pipes 18 and 19, and then collected in the high-pressure water heater 16 through the heater drain discharge pipes 22 and 23. Here, control valves 24 and 25 are provided in the paths of the heater drain dischargers 22 and 23, respectively, so that the water levels of the heater drain tanks 20 and 21 are kept constant. High pressure feed water heater
The drain sent to 16 is deprived of heat by the feed water passing through it and the temperature drops, and together with the drain generated by the condensation of steam when heating the feed water, it is collected in the drain tank 27 through the drain pipe 26 of the feed water heater Is done. Thereafter, the drain in the drain tank 27 is extracted by the drain pump 28, injected into the suction side of the water supply pump 15 through the drain injection pipe 29, mixed with the condensate sent from the low-pressure water heater 14, and retained. Heat is transmitted to the condensate. Normally, the drain injection pipe 29 is provided with a control valve 30, which receives a control signal from a water level controller (not shown) that detects the water level of the drain tank 27, and adjusts the valve opening. This changes the amount of drain injected into the condensate. In addition, the moisture separator drain is collected in the drain tank 27 by a moisture separator drain pipe 31 connecting the moisture separator 5 and the drain tank 27. In the drawing, reference numerals 32 and 33 denote heating steam stop valves, which open and close upon receiving control signals when heating steam is supplied to and stopped from the heaters 6 and 7. Reference numeral 34 denotes a reheat steam stop valve, and reference numeral 35 denotes a steam control valve.

(Problems to be Solved by the Invention) By the way, the reheat steam stop valve 34 provided at the inlet of the low-pressure turbine 11 instantaneously shuts off the steam flowing to the low-pressure turbine 11 when the speed of the steam turbine becomes higher than a certain value. This is an important security device provided to prevent the steam turbine from becoming dangerous due to overspeed, and an operation test is periodically performed to confirm that there is no abnormality in its operation. Normally, in the operation test of the reheat steam stop valve 34, an operation that affects the steam flow rate is scheduled even if the operation time from the fully open to the fully closed state of the reheat steam stop valve 34 is short,
The steam flow rate passing through the heaters 6 and 7 changes, and as a result, the amount of drain collected in the heater drain tank 27 also fluctuates.

For example, since two heaters 6 and 7 are usually provided for one plant, the reheat steam stop valve 34 is
When the number of 11 is one, two are incorporated, and when the number is 11, four are incorporated. Here, when the reheat steam stop valves 34 are fully closed one by one by the operation test, particularly when the number of the low-pressure turbines 11 is one, the amount of steam passing through the reheat steam stop valve 34 which is not the target of the operation test increases. As a result, the drain amount discharged from the heaters 6 and 7 communicating with the reheat steam stop valve 34 during the operation test and the separated drain amount from the moisture separator 5 become almost zero.

Due to such a decrease in the drain amount, the water level in the drain tank 27 decreases, the opening of the control valve 30 that regulates the drain injection amount is narrowed, and the drain injected into the condensate water decreases. As a result, the steam generator The amount of water supplied to 1 will fluctuate. As described above, the operation test of the reheat steam stop valve 34 must be performed periodically, but as a result of being affected by the change in the amount of water supplied each time such an operation test is performed, for example, the water supply control is unstable. It is expected to be a problem in maintaining plant safety.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reheat steam for a steam turbine plant that adjusts a plant output prior to a change in water supply during an operation test of a reheat steam stop valve, thereby increasing plant safety. An object of the present invention is to provide a stop valve operation test control device.

[Structure of the Invention] (Means for Solving the Problems) A reheat steam stop valve operation test control device for a steam turbine plant according to the present invention performs an operation of checking whether there is an abnormality in a reheat steam stop valve during plant operation. A steam turbine plant comprising a reheat steam stop valve test device to be examined by a test, an output control device for adjusting plant output, and a heater control device for controlling supply and stop of heating steam to a moisture separation heater. In the operation test, a reheat steam stop valve test device, an output control device and a heater control device are provided with a plant control device that outputs control signals in a predetermined order. The output is reduced to a predetermined output, and a signal for closing the heating steam stop valve is output to each of the output control device and the heater control device. When the steam control valve opening degree decrease signal and the heated steam stop valve close signal are given from the above, the test valve excitation signal is output to the reheat steam stop valve test device, and at the end of the operation test, the heated steam stop valve is opened, and A device for outputting a signal for returning the plant output to the rated output to the heater control device and the output control device is provided.

(Operation) The plant control device functions as follows. That is,
A control signal for adjusting the plant output to the set output is output simultaneously with the start of the operation test of the reheat steam stop valve, and when a decrease in the output of the plant is detected at an appropriate place in the plant,
The operation of the heater is stopped by the control signal issued at that time, and when the stop is detected at an appropriate place around the heater, the reheat steam stop valve is changed from fully open to fully closed by the control signal issued at that time. Be operated.

Further, when the reheat steam stop valve is fully opened and detected at an appropriate place around the reheat steam stop valve, the operation of the heater is started by the control signal issued at that time, and the start is detected. The plant output is returned from the set output to the output before the operation test by the control signal issued at that time.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG. 1 and FIG.

In this embodiment, the same components as those of the conventional steam turbine plant shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, a steam control valve 35, a heated steam stop valve 32,
33 and reheat steam stop valve 34 have opening transmitter 36, respectively.
37, 38 and 39 are provided. Among these opening degree transmitters, the opening degree transmitter 36 is such that when the steam control valve 35 has reached a predetermined opening degree, the opening degree transmitters 37 and 38 are the heating steam stop valve 32,
When the valve 33 is fully closed, the opening transmitter 39 turns on the reheat steam stop valve.
The control signal is output to each circuit of the plant control device 40 when the switch 34 is fully closed.

On the other hand, as a control signal to the plant control device 40,
A control signal described later is given from a reheat steam stop valve test device 41 provided in the plant. Then, this is processed in the plant control device 40 together with the control signal based on the output of the opening degree transmitters 36, 37, 38 and 39 described above, and the output control device
The control signal for the heater 42 and the heater control device 43 and the control signal for the reheat steam stop valve test device 41 (each described later) are respectively generated.

Next, the function of the plant control device 40 shown in FIG. 2 will be described with reference to a block diagram.

At the start of the operation test, the test button of the reheat steam stop valve test control device 41 is turned on, and a test button input signal issued at that time is input to the output control device 42, and the plant output is reduced to a predetermined set output. A set output reduction command signal is output to a reactor recirculation control device or the like. Thereafter, when a decrease in the opening of the steam control valve 35 is confirmed by the steam control valve opening decrease signal from the opening transmitter 36, the heater control device 43
, A control signal is output, and a heating steam stop valve closing signal is output. Thereafter, when the heating steam stop valve closing signals from the opening degree transmitters 37 and 38 confirm that the heating steam stop valves 32 and 33 are fully closed, a control signal is output to the reheat steam stop valve test device 41,
A test valve excitation signal is output. For this reason, the reheat steam stop valve 34 shifts from fully open to fully closed.

On the other hand, at the end of the operation test, the reheat steam stop valve test controller
The test button 41 is turned off, and the test valve is de-energized by the test button off signal issued at that time. afterwards,
When it is confirmed that the reheat steam stop valve 34 is fully opened by the reheat steam stop valve fully open signal from the opening degree transmitter 39, the heater controller
A control signal is output to 43 and a heating steam stop valve open signal is output. Then, when the heating steam stop valves 32 and 33 are fully opened by the heating steam stop full open signals of the opening degree transmitters 37 and 38, a control signal is output to the output control device 42, and the blunt output is rated output. Is output to a reactor recirculation control device or the like.

In the system provided with such a plant control device 40, the output of the steam turbine must be reduced in advance so as to match the drain amount that decreases during the operation test of the reheat steam stop valve 34, in other words, the water supply amount varies. It is possible to adjust the output to match it in anticipation of this and the water supply control is kept stable during the operation test.

Conventionally, a method of not compensating for a decrease in the drain amount with almost the same amount of condensate and not disturbing the water supply control and the water level control of the steam generator 1 has been adopted. In this case, a decrease in the drain amount is also expected. Although it is necessary to increase the equipment capacity upstream of the drain injection point, the present invention does not require such an excessive equipment.

In addition, the present invention does not depend on each configuration of the above embodiment,
It is also possible to combine the following means. That is, an output transmitter may be provided in a generator (not shown) to detect that the plant output has decreased to the set output.
Further, a flow meter for detecting the steam flow rate or a pressure gauge for detecting the steam pressure may be provided in the heating steam pipes 8 and 9 through which the heating steam flows in order to detect the operation stop or the operation start of the heaters 6 and 7.

[Effects of the Invention] As described above, in the present invention, at the start of the operation test of the reheat steam stop valve, the plant output is adjusted, the operation of the heater is stopped when the output reaches a certain set output, and then the operation is restarted Since the operation of fully closing and fully opening the thermal steam stop valve is performed, the plant output can be reduced prior to the fluctuation of the water supply amount. Therefore, there is an excellent effect that the water supply control is stably maintained even during the operation test of the reheat steam stop valve, and the safety of the plant is enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a reheat steam stop valve operation test control device according to the present invention, FIG. 2 is a block diagram showing an embodiment of a plant control device, and FIG. 3 shows a conventional steam turbine plant. It is a system configuration diagram. 3 High-pressure turbine 6, 7 Heater 8, 9 Heating steam pipe 11 Low-pressure turbine 16 High-pressure feed water heater 20, 21 Heater drain tank 27 Drain tank 32, 33 … Heated steam stop valve 34 …… Reheat steam stop valve 35 …… Steam control valve 36, 37, 38, 39 …… Opening transmitter 40 …… Plant control device 41 …… Reheat steam stop valve test device 42… … Output control device 43 …… Heating device control device

Claims (1)

(57) [Claims] 1. A reheat steam stop valve test device for checking the presence or absence of an abnormality of a reheat steam stop valve during an operation test during plant operation, an output control device for adjusting plant output, and a moisture separation heater. In a steam turbine plant comprising a heater control device for controlling the supply and the stop of the heating steam, during an operation test, the order determined by the reheat steam stop valve test device, the output control device and the heater control device Providing a plant control device that outputs a control signal at the start of the operation test, the plant control device reduces the plant output to a predetermined output, and the output control device and the signal to close the heating steam stop valve and the output control device When output to the heater control device and a steam control valve opening degree decrease signal and a heating steam stop valve closing signal are given from the respective detection ends,
A test valve excitation signal is output to the reheat steam stop valve test device, and at the end of the operation test, the heating steam stop valve is opened, and a signal for returning the plant output to the rated output is output to the heater control device and the output control. A reheat steam stop valve operation test control device for a steam turbine plant, comprising: a device that outputs a signal to a device.