JPH0610404B2 - Steam turbine controller - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a control hydraulic pressure self-supplying steam turbine that supplies a control hydraulic pressure by a driving force of a turbine, and in particular, for example, in a turbine pump system of a reactor isolation cooling system. As described above, the present invention relates to a steam turbine control device that requires a quick start.

[Technical background of the invention and its problems]

Generally, in a steam turbine plant, for example, a geothermal power plant that has only a DC power supply that can be used for a short period of time for driving signals, a turbine for backup power supply in an emergency, or an emergency in a nuclear power plant. Although it has a steam source in the steam turbine plant, such as the turbine pump system of the reactor isolation cooling system, which is one of the reactor auxiliary systems for backup, the hydraulic pressure for turbine control and lubrication. There is a turbine that does not have any other source or auxiliary power source and has a function of supplying oil by driving an oil pump by itself.

For example, FIG. 3 shows that when the reactor is isolated from the turbine condenser, cooling water is supplied from the condensate storage tank to the reactor to maintain the water level of the reactor and cool the core. The system diagram of the cooling system during isolation is shown. The reactor 2 arranged in the containment vessel 1 is supplied with the coolant through the water supply line 3, and the steam generated there is passed through the main steam line 4. It is supplied to a main steam turbine (not shown). On the other hand, a reactor isolation cooling system steam line 5 is branched to the main steam line 4, and a part of the main steam is electrically operated by a motor-operated valve 6 provided in the reactor isolation cooling system steam line 5 and steam. Stop valve 7,
Then, it is introduced into the reactor isolation cooling system turbine (RCIC turbine) 9 through the steam control valve 8 and then returned to the pressure suppression pool 11 through the steam turbine disposal line 10. Further, the RCIC turbine 9 is directly connected to an oil pump 12 that sends lubricating oil to the turbine control device and a reactor isolation cooling system feed water pump 13 that feeds the cooling water in the condensate storage tank to the reactor 2. ing.

Then, in the reactor power generation system, when the reactor 2 is isolated in an emergency such as when the reactor water supply is stopped, the reactor water level is lowered, and the reactor isolation cooling system activation signal is output,
The motor-operated valve 6 starts to open, and the main steam is passed through the steam stop valve 7 and the steam control valve 8 which are already waiting in the fully opened state to generate RCI.
It is supplied to the C turbine 9, the RCIC turbine 9 is driven, and cooling water is sent from the condensate storage tank to the reactor 2 by the reactor isolation cooling system feed water pump 13 to cool the core.

FIG. 4 shows in detail the steam turbine control device for the reactor isolation cooling system. When the reactor isolation cooling system activation signal a is input to the motor-operated valve 6, the motor-operated valve is operated as described above. 6
Is opened and the RCIC turbine 9 is started through the steam stop valve 7 and the steam control valve 8. The oil pump 12 directly connected to the turbine 9 generates control oil for driving the steam control valve 8 in response to the activation of the turbine 9.

When the motor-operated valve 6 is opened, the position detector 14 detects the slightly opened state of the motor-operated valve 6 and generates the turbine starting signal b. The turbine start signal b ₁ is the ramp signal calculator 1
5, the ramp signal calculator 15 outputs the ramp signal c, and the ramp signal c is applied to the speed request signal calculator 16 including a low value priority circuit. On the other hand, a flow rate detector 17 is provided on the discharge side of the reactor isolation cooling system feed water pump 13, and the flow rate signal d is added to the flow rate calculator 18.
The flow rate request signal e is input to the speed request signal calculator 16, where the low value signal of the ramp signal c is added to the speed control calculator 19 as the speed request signal f.

The rotation speed detecting gear 20 and the electromagnetic pickup 21 provided on the turbine shaft detect the actual rotation speed of the RCIC turbine 9, and the rotation speed calculator 22 generates a turbine actual measurement signal g from the output signal of the electromagnetic pickup 21. It is sent to the speed control calculator 19. This speed control calculator 19
The deviation signal between the speed request signal f of the speed request signal calculator 16 and the actual speed signal g from the rotation speed calculator 22 is sent to the electro-oil converter 23 as a speed control signal h. The electro-oil converter 23 controls the control oil from the oil pump 12 based on the speed control signal h and supplies the control oil to the oil cylinder 24 to control the opening degree of the steam control valve 8. Specifically, in the initial stage of starting the RCIC turbine 9, the ramp signal c becomes the speed request signal f through the speed request calculator 16 so as to keep the rate of increase of the turbine constant, and the speed control calculator 19 supplies the electric oil. Converter 23
The opening degree of the steam control valve 8 is controlled accordingly. In this way, the RCIC turbine 9 is activated, and the amount of water supplied from the reactor isolation cooling system water supply pump 13 is increased.
When the flow rate request signal d reaches a predetermined value, the flow rate request signal e is output from the speed request signal calculator 16 as a speed request signal f, and the opening degree of the steam control valve 8 is controlled based on the signal. Like

However, in such a device, although the oil pump 12 is directly connected to the turbine shaft in spite of the fact that the oil pump 12 is always required to be rapidly started, the number of revolutions of the RCIC turbine 9 reaches a certain constant number of revolutions and the oil is not oiled. It takes some time for the hydraulic pressure required to operate the cylinder 24 to be established, which may cause an abnormal initial peak rotation speed such that the rotation speed of the RCIC turbine 9 exceeds the rated rotation speed. I have a problem.

That is, FIG. 5 is a diagram showing each state value at the time of startup of the reactor isolation cooling system. As described above, in the RCIC turbine, the steam control valve opening is fully opened so that a large starting torque can be obtained. Is started in the state of. In addition, the electric valve 6,
The steam stop valve 7 and the steam control valve 8 are defined so that the steam of 2 to 3 times the steam flow rate required for steady operation can pass in order to obtain the starting torque. Therefore, the motor operated valve 6
However, when it begins to open, a large amount of steam flows into the turbine almost at the same time, so the turbine speed rapidly increases as shown in FIG. When the turbine speed exceeds the ramp signal and the control oil pressure is established as the turbine speed increases, the steam control valve is operated in the fully closing direction. In other words, since there is a time delay before the steam control valve operates, the turbine speed rapidly increases during this period, causing an abnormal initial peak speed n in which the turbine speed exceeds the rated speed. There is a risk that an emergency stop may occur due to the operation of a speed machine, etc., and there is a problem that the reactor becomes even more dangerous.

In the above, the conventional control hydraulic self-supplying steam turbine of the cooling system during reactor isolation was taken as an example.However, such a sudden overspeed of the turbine at the time of steam turbine start-up also applies to other control hydraulic self-supplying steam turbines. It is a similar problem.

[Object of the Invention]

Therefore, an object of the present invention is to provide a control device for a steam turbine that prevents sudden overspeed at the time of starting the control hydraulic pressure self-supplied steam turbine.

[Outline of Invention]

In order to achieve this object, the present invention has a steam stop valve, a steam control valve, and an electric valve located upstream thereof, and the steam stop valve and the steam control valve are fully opened in advance when the turbine is started. In a control hydraulic self-supplying steam turbine that starts a turbine by opening the electrically operated valve and supplies control oil by the driving force of the turbine, a bypass passage that bypasses the electrically operated valve and a bypass passage provided in the bypass passage are provided. And a control means for opening the bypass valve prior to the electrically operated valve in response to a start signal.

Example of Invention

An embodiment of the steam turbine control device according to the present invention will be described below with reference to FIGS. 1 and 2 in which the same parts as those in FIGS. 3 to 5 are designated by the same reference numerals.

FIG. 1 shows an embodiment in which a steam turbine control device according to the present invention is applied to a reactor isolation cooling system. A reactor isolation cooling system steam line 5 includes a bypass passage bypassing an electrically operated valve. 25 are connected. This bypass 25
An electric valve bypass valve 26 and an orifice 27 are provided downstream thereof. This bypass valve 26
Is selected to be about 1/3 to 1/4 of the diameter of the motor-operated valve 6. Further, the orifice 27 is set so that the rotation speed of the RCIC turbine 9 is near the minimum value required to establish the control oil pressure from the oil pump 12 even when the bypass valve 26 is fully opened.
The flow rate of the bypass valve 26 is limited. The bypass valve 26 is provided with a bypass valve timer 28. When the bypass valve timer 28 receives the reactor isolation cooling system activation signal a, the bypass valve 26 is fully opened for a predetermined time from the receipt, and then the bypass valve 26 is fully opened again. Close it. Further, a delay timer 29 is attached to the motor-operated valve 6, and when the delay timer 29 receives the cooling system signal a, the motor-operated valve 6 is opened after a predetermined time delay from the reception. This delay time is set to be shorter than the predetermined time of the bypass valve timer 28. The other structure is exactly the same as that shown in FIGS.

The operation of the device according to the invention will now be described.

When the reactor isolation cooling system activation signal a is generated at the time point t ₀ shown in FIG. 2, the bypass valve timer 28 and the delay timer 29 start operating, and the bypass valve timer 28 starts the predetermined time from the time point t _0. time _(t 0 ~t ₂₎ sends a valve open signal only to the bypass valve 26. In response to this valve opening signal, the bypass valve 26 is fully opened for a fixed time, for example, 3 to 7 seconds. This causes the steam to pass through the bypass valve 25 and become RCI.
It flows into the C turbine 9 and starts it. Since the flow rate of the bypass passage 25 is limited by the orifice 27, the turbine speed does not rise excessively rapidly,
As shown in FIG. 2, it is suppressed to the low rotation required for establishing the hydraulic pressure by the oil pump 12.

On the other hand, when a predetermined delay time, for example, 2 to 5 seconds elapses from time t ₀ when the cooling system activation signal a is generated, and time t ₁ is reached,
The delay timer 29 opens the motor-operated valve 6. When the motor-operated valve 9 starts to open, a large amount of steam flows into the turbine 9. The position detector 14 detects the opening of the motor-operated valve 6 and generates a turbine start signal b. The delay time (t _{0 to} t ₁ ) is selected so that the electric valve 6 is opened after the control hydraulic pressure to the oil cylinder 24 is established by opening the bypass valve 26, and thus the electric valve 6 is opened. Even if a large amount of steam flows into the turbine 9 by opening the valve 6, the steam control valve 8 is already controllable. Therefore, the turbine 9 follows the speed control signal h from the speed control calculator 19 and smoothly increases the rotation speed. In this way, the bypass valve 26 is opened prior to the opening of the motor-operated valve 6 in response to the cooling system activation signal a, and the steam whose flow rate is restricted is supplied to the turbine 9 to establish the control oil pressure, and then the motor-operated valve is opened. 6 is opened, and the steam flow rate to the turbine 9 is adjusted based on the speed control signal h.

In addition, the fully open time of the bypass valve 26 set by the bypass valve timer 28 and the delay time by the delay timer 29 increase the turbine speed to a value necessary for establishing the control hydraulic pressure during the fully open time of the bypass valve 26, Moreover, it is desirable to determine that the motor-operated valve 6 opens immediately after the control oil pressure is established. As a result, the rapid start-up time can be shortened without overspeeding the turbine.

Further, the drive of the bypass valve 26 can be appropriately selected according to the conditions to be used such as a motor drive system and an air actuation system.

In the present embodiment, the bypass valve 26 and the orifice 27 are installed in the bypass passage 25. However, if the flow rate of the bypass passage 25 can be set to an appropriate value only by appropriately selecting the diameter of the bypass valve 26, the orifice 27 is unnecessary. Becomes

Further, in the above-described embodiment, the control device of the RCIC turbine of the reactor isolation cooling system in the nuclear power plant has been described. However, the present invention has, for example, a DC power source that can be used only for a short period for a start signal or the like. It has a so-called steam source such as a power generation system and a turbine for backup power supply in an emergency, but it has no other hydraulic source or auxiliary power source for turbine control or lubrication, and it is driven by itself and is an oil pump. It can also be applied to a steam turbine system that has a function of rotating and supplying oil.

〔The invention's effect〕

As is apparent from the above description, the present invention provides the bypass valve in the bypass path that bypasses the motor-operated valve, opens the bypass valve prior to the motor-operated valve at the time of turbine startup, and limits the steam flow rate at the initial stage of turbine startup. Therefore, it is possible to prevent a sudden overspeed at the time of starting the turbine and the occurrence of expansion due to this. Further, the bypass passage provided with the bypass valve can easily be additionally attached to the existing steam turbine control device.

[Brief description of drawings]

FIG. 1 is a system diagram showing a control device for a nuclear reactor isolation cooling system equipped with a steam turbine control device according to the present invention, and FIG. 2 is a graph showing a state of each part of FIG. 1 at turbine startup. Fig. 3 is a system diagram showing a conventional reactor isolation cooling system, Fig. 4 is a system diagram showing the control device of Fig. 3, and Fig. 5 is a state of each part of Fig. 4. FIG. 6 ... motorized valve, 7 ... steam stop valve, 8 ... steam control valve,
9 ... Turbine, 25 ... Bypass passage, 26 ... Bypass valve, 28 ... Bypass valve timer, 29 ... Delay timer.

Claims (5)

[Claims] 1. A steam stop valve, a steam control valve, and a motor-operated valve located upstream thereof. The steam stop valve and the steam control valve are fully opened in advance when the turbine is started, and the motor-operated valve is opened. In the control hydraulic self-supplying steam turbine that starts the turbine by valve and supplies the control hydraulic pressure by the driving force of the turbine, a bypass path that bypasses the electric valve, and a bypass valve provided in the bypass path, A steam turbine control device comprising: a control unit that opens the bypass valve prior to the electrically operated valve in response to a start signal. 2. A bypass valve timer for opening the bypass valve for a first predetermined time in response to the activation signal, and a delay time for a second predetermined time in response to the activation signal. The steam turbine control device according to claim 1, further comprising a delay timer that opens the motor-operated valve. 3. The first and second predetermined times are set so that the motor-operated valve is opened during opening of the bypass valve. A steam turbine control device according to item. 4. The steam turbine control device according to claim 1, wherein the amount of steam flowing through the bypass passage is selected so that the turbine speed can establish a control hydraulic pressure. 5. The steam turbine controller according to claim 4, wherein the bypass passage has an orifice for limiting a flow rate of the bypass passage.