JPH01277606A - Reheated steam stop valve operation test controller for steam turbine plant - Google Patents

Abstract

PURPOSE:To maintain the water supply control in stable state also during test by adjusting the output on the start of operation test of a reheated steam stop valve and stopping the operation of a heater when a set output is obtained and carrying out the perfect opening and perfect closing operations of the stop valve. CONSTITUTION:A controller 40 outputs a control signal for adjusting the plant output to a prescribed low set value into an output controller 42, simultaneously with the start of a reheated steam stop valve test device 41 and stops the operations of heaters 6 and 7 through a heater controller 43 when the set output is obtained, and when said stop is detected from the signals of the opening degree transmitters 37 and 38, a reheated steam stop valve 34 is operated from the perfect opening to the perfect closing. When the perfect opening state of the stop valve 34 is detected by an opening degree transmitter 39, the operations of the heaters 6 and 7 are started, and when the operation start is detected, the plant output is restored to the output before the operation test. Thus, the plant output is reduced in precedence with the variation of the supplied water quantity, and also during the test, the water supply control is held in stable state, and the safety of a plant can be improved.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a steam turbine plant, and more particularly to an operation test of a reheat steam stop valve provided at the 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 conducting a reheat steam stop valve operation test.

(Prior art) In a steam turbine plant using a reheat cycle system, steam that has been expanded to a low temperature in a high-pressure turbine is heated in a reheater and guided to a low-pressure turbine as superheated steam, improving thermal efficiency. It is preferred for large-capacity steam turbine plants with the intention of maximizing performance. An example of a steam turbine plant using this reheat cycle system will be described below with reference to the drawings.

In FIG. 2, steam generated in a steam generator 1 is led to a high-pressure turbine 3 through a main steam pipe 2, and after being expanded to do work, it is passed through a low-temperature reheat steam pipe 4 to a moisture separator 5. guided by. The moisture separator 5 is constructed by arranging corrugated plates in multiple layers, and the moisture contained in the main steam is removed while the main steam passes through it. Furthermore, the main steam is supplied to a heater 6 whose inside and outside are separated by a heat transfer wall.
．． 7 and is heated while flowing there, changing its state from saturated steam to superheated steam. During this time, the superheated steam flowing inside the heaters 6 and 7 is guided through a heating steam pipe 8 connected to an appropriate stage of the high-pressure turbine 3 and a heating steam pipe 9 connected to the main steam pipe 2.

Main steam that has stored energy as superheated steam is led to a low-pressure turbine 11 through a high-temperature reheat steam pipe 10, where it does work again, and then discharged to a condenser 12 where it is condensed with cooling water. After this, the condensate extracted from the condenser 12 by the condensate pump 13 passes through the low-pressure feedwater heater 14, where it is heated by steam extracted from the low-pressure turbine 11 and sent through a bleed pipe (not shown). The water is further pressurized by the feedwater pump 15 and sent to the high-pressure feedwater heater 16, heated by steam extracted from the high-pressure turbine 3 and guided through the bleed pipe 17, and sent to the steam generator 1.

On the other hand, the heated steam that loses its heat to the main steam while flowing in the heater 6.7 condenses, and a large amount of drainage is generated. This condensate is once collected in the heater drain tank 20.21 through the heater drain pipe 18.19, and from there to the high pressure feedwater heater 16 through the heater drain discharge pipe 22.23. Here, heater drain discharger 2
Control valves 24, 25 are provided in each of the paths 2, 23 to keep the water level of the heater drain tank 20, 21 constant. The condensate sent to the high-pressure feedwater heater 16 loses heat to the feedwater passing through it and its temperature drops, and along with the condensate produced by the condensation of steam during the heating of the feedwater mentioned above, the condensate is passed through the feedwater heater drain pipe 26. It is collected in the tank 27. Thereafter, the drain in the drain tank 27 is extracted by the drain pump 28 and injected into the suction side of the water supply pump 15 through the drain injection pipe 29, and
It is mixed with the condensate sent from No. 4, and the retained heat is transferred to the condensate. Normally, the drain injection pipe 29 is equipped with a control valve 30, and the valve opening degree is adjusted in response to a control signal from a water level controller (not shown) that detects the water level in the drain tank 27. The amount of condensate injected into the condensate can be changed.

In addition, moisture separator drain is collected into the drain tank 27 by a moisture separator drain pipe 31 that connects the moisture separator 5 and the drain tank 27 . In the figure, reference numerals 32 and 33 indicate heating steam stop valves, which open and close in response to control signals when supplying and stopping heating steam to the heater 6.7. Further, reference numeral 34 indicates a reheat steam stop valve, and reference numeral 35 indicates a steam control valve.

(Problem 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 instantly shuts off the steam flowing to the low-pressure turbine 11 when the speed of the steam turbine exceeds a certain level.
This is an important safety device installed to prevent the steam turbine from becoming dangerous due to overspeeding, and operational tests are periodically conducted to confirm that there are no abnormalities in its operation. Normally, in the operation test of the reheat steam stop valve 34, the reheat steam stop valve 34 is scheduled to perform an operation that affects the steam flow rate even if the operation time from fully opening to fully opening is short. .7 will vary, resulting in variations in the amount of condensate collected in the heater drain tank 27.

For example, typically 6.7 heaters are used per plant.
Therefore, two reheat steam stop valves 34 are installed when the number of low-pressure turbines 11 is one, and four when there are two low-pressure turbines 11. Here, the reheat steam stop valve 34 was tested to 1
When the reheat steam stop valve 3 is completely closed one by one, especially when the number of low pressure turbines 11 is one, the operation test is not performed.
4 increases, and the amount of condensate discharged from the heater 6.7 communicating with the reheat steam stop valve 34 during the operation test and the amount of separated condensate from the moisture separator 5 are almost the same. It becomes zero.

Due to such a decrease in the amount of drain, the water level in the drain tank 27 falls, and the opening degree of the control valve 30 that adjusts the amount of drain injection is narrowed, reducing the amount of drain injected into the condensate, and as a result, the steam generator The amount of water supplied to 1 will fluctuate. As mentioned above, the operation test of the reheat steam stop valve 34 must be carried out periodically, but as a result of fluctuations in the water supply amount every time such an operation test is performed, for example, the water supply control becomes unstable. This is expected to cause problems in maintaining plant safety.

An object of the present invention is to adjust the plant output in advance of fluctuations in the amount of water supply during an operation test of a reheat steam stop valve, thereby increasing the safety of the plant. An object of the present invention is to provide a stop valve operation test control device.

[Structure of the Invention] (Means for Solving the Problem) The reheat steam stop valve operation test control device according to the present invention is a device that outputs a control signal for adjusting the plant output at the start of the reheat steam stop valve operation test. , a device that outputs a control signal when the plant output decreases to a certain set output, a device that outputs a control signal when a heater stop or start is detected, and a device that outputs a control signal when a heater stop or start operation is detected, and a reheat steam stop valve opening. A device that outputs a control signal when the temperature is fully open, and based on these control signals, the heater is stopped, the reheat steam stop valve is fully closed or fully opened, the heater is started, and the plant is The present invention is characterized by comprising a plant control device that executes each operation of output restoration in a predetermined order.

(Operation) The plant control device functions as follows. In other words, a control signal to adjust the plant output to the set output is output at the same time as the operation test of the reheat steam stop valve starts, and when a decrease in the plant output is detected at an appropriate location in the plant, the control signal is output at that time. When the heater is shut down and the shutdown is detected at an appropriate location around the heater, the control signal issued at that time causes the reheat steam stop valve to operate from fully open to fully open.

Additionally, when the reheat steam stop valve is fully opened and this is detected at an appropriate location around the reheat steam stop valve, the heater operation is started by the control signal issued at that time, and the start is detected. The control signal issued at that time causes the plant output to return from the set output to the output before the operation test.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

In this example, the same components as the conventional steam turbine plant shown in FIG. 3 are designated by the same reference numerals.
Descriptions of these will be omitted.

In FIG. 1, a steam control valve 35 and a heating steam stop valve 32 are shown.
．． 33 and reheat steam stop valve 34 are provided with opening degree transmitters 36, 37, 38 and 39, respectively. Among these opening transmitters, the opening transmitter 36 is activated when the steam control valve 35 reaches a predetermined opening.
8 outputs control signals to each circuit of the plant control device 40 when the heating steam stop valves 32 and 33 are fully open, and the opening transmitter 39 outputs control signals when the reheat steam stop valve 34 is fully open. is configured to do so.

On the other hand, as a control signal to the plant control device 40,
A control signal, which will be described later, is given from a reheat steam stop valve testing device 41 provided in the plant.

And the above-mentioned opening transmitters 36, 37, 38 and 3
Plant control device 4 together with a control signal based on the output of 9.
This is processed within 0, and control signals for the output control device 42 and the heater control device 43 and the control signal for the reheat steam stop valve testing device 41 (all described later) are respectively generated.

Next, the functions of the plant control device 4° shown in FIG. 2 will be explained with reference to a block diagram.

When the test button of the reheat steam stop valve test device 41 is turned on, the test button input signal issued at that time is input to the output control device 42, and a set output range command signal is issued to reduce the plant output to a predetermined set output. Output to reactor recirculation control equipment, etc. Thereafter, when a decrease in the opening degree of the steam control valve 35 is confirmed by the output from the opening degree transmitter 36, a control signal is output to the heater control device 43, and a heating steam stop valve closing signal is output. After that, the opening transmitter 37.3
When it is confirmed that the heating steam stop valves 32 and 33 are fully opened by the output from the reheating steam stop valve 8, a control signal is output to the reheat steam stop valve testing device 41, and a test valve excitation signal is output. Therefore, the reheat steam stop valve 34 shifts from fully open to fully open.

On the other hand, the test button of the reheat steam stop valve testing device 41 is turned off, and the test valve is deenergized by the test button cut signal issued at that time. Thereafter, when it is confirmed by the output from the opening transmitter 39 that the reheat steam stop valve 34 is fully open, a control signal is output to the heater control device 43, and a heating steam stop valve open signal is output. After that, the opening transmitter 37.
38 confirms that the heating steam stop valves 32 and 33 are fully open, a control signal is issued to the output control device 42, and a return command signal to return the plant output to the rated output is sent to the reactor recirculation control device. etc. is output.

In a plant equipped with such a plant control device 40, the output of the steam turbine must be lowered in advance to match the amount of drain that decreases during the operation test of the reheat steam stop valve 34, in other words, the amount of water supply is changed. It is possible to adjust the output to match it by overcoming this, and water supply control is kept stable even during operational tests.

In addition, conventionally, a method has been adopted in which the decrease in the amount of drain is compensated for with approximately the same amount of condensate so as not to cause any disturbance to the water supply control and the water level control of the steam generator 1, but in this case, a decrease in the amount of drain is also expected. Although it is necessary to increase the capacity of the equipment upstream of the drain injection point, the present invention does not require such excessive equipment.

Note that the present invention is not limited to the configurations of the above embodiments, and can also be combined with the following means.

That is, an output transmitter may be provided on the generator (not shown) to detect when the plant output has decreased to a set output, and an output transmitter may be provided on the generator (not shown) to detect when the heater 6.7 is stopped or started. Heating steam pipe through which heating steam flows 8.
9 may be provided with a flow meter for detecting the steam flow rate or a pressure gauge for detecting the steam pressure.

[Effects of the Invention] As explained above, in the present invention, at the start of the operation test of the reheat steam stop valve, the plant output is adjusted, and when a certain set output is reached, the operation of the heater is stopped, and then the operation is restarted. Since the thermal steam stop valve is fully closed and fully opened, it is possible to reduce the plant output in advance of fluctuations in the amount of water supply. Therefore, even during the reheat steam stop valve operation test, water supply control is maintained stably, and the safety of the plant is improved, which is an excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the reheat steam stop valve operation test control device according to the present invention, Fig. 2 is a block diagram showing an embodiment of the 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] 1... Low pressure turbine 16...・・High pressure water heater 20.21・・
・Heater drain tank 27...Drain tank 32.33...Heating steam stop valve 34...Reheat steam stop valve 35...
...Steam control valve 36.37.38.39...Opening degree transmitter 40...
...... Plant control device 41 ...... Reheat steam stop valve testing device 42 ...... Output control device

Claims (1)

[Claims] At the start of the operation test of the reheat steam stop valve, there is a device that outputs a control signal to adjust the plant output, a device that outputs a control signal when the plant output decreases to a certain set output, and a device that outputs a control signal to adjust the plant output, and a device that outputs a control signal to stop or restart the heater. a device that outputs a control signal when a start is detected; a device that outputs a control signal when the reheat steam stop valve is fully opened; and a device that outputs a control signal when the reheat steam stop valve is fully opened; A steam turbine plant comprising: a plant control device that executes the following operations in a predetermined order: stopping the operation of the reheat steam stop valve, fully closing and fully opening the reheat steam stop valve, starting the operation of the heater, and restoring the plant output. Reheat steam stop valve operation test control device.