JPH0363642B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a valve drive device that opens and closes a steam control valve used in thermal or nuclear power generation, for example, and particularly relates to a disk dump valve incorporated in the valve drive device. The present invention relates to an improvement in a valve driving device that operates relatively more slowly than before.

[Technical background of the invention]

For example, in recent years, in nuclear power plants, in order to obtain stable output from the core of a nuclear reactor, the core is outputting power without stopping even when there is a load or interruption, instead of cutting off the steam flowing into the turbine. A so-called full bypass system is used in which the steam is passed directly to the condenser. That is, FIG. 1 shows a schematic system of a conventional nuclear power plant, in which the steam generated in the nuclear power plant 1 is passed through the main steam stop valve 7 and the steam control valve 8.
The steam that has completed its work passes through a moisture separator 6 and an intermediate check valve 23 and enters a low-pressure turbine 3, which turns a generator 4. The steam that has completed its work enters the condenser 5, condenses there, becomes condensed water, and returns to the reactor 1 via a feed water heater, a feed water pump, etc. (not shown).

On the other hand, when a nuclear power plant receives a command to cut off the load due to a system accident, the steam control valve 8 closes,
The entire amount of steam discharged from the reactor 1 is configured to flow into the condenser 5 via the bypass valve 9 and attemperator 10 built into the turbine bypass line 9a.
This allows a fixed amount of steam to be output from the nuclear reactor 1, in preparation for post-accident recovery.

By the way, the control device that opens and closes the steam control valve is
It is constructed as shown in FIG. 3, and is fully opened in the illustrated state. From this state, now
When there is a load cutoff command, the signal is applied to the quick-acting solenoid valve 14 and the servo valve 13. Then, the piston 14a of the rapid-acting solenoid valve 14 is energized,
Ports a and b communicate with each other. When the ports a and b communicate with each other, the pressure oil at the lower part of the disc dump valve 12 incorporated in the oil cylinder 11 is drawn out through the communication path, and thereby the disc dump valve 12
falls downward against the spring 11f, and at the same time, the piston 15a of the pilot valve 15 also falls downward from the illustrated state, cutting off communication between ports c and d and cutting off the supply of pressure oil to the servo valve 13. .

When the disk dump valve 12 moves downward, the empty chamber 1
Pressure oil 0a is sent to a tank (not shown) through port e, while passing through oil path OP to servo valve 13.
is also sent to the tank from port f.

When the pressure oil in the empty chamber 11a in the oil cylinder 11 is drawn out in this way, the piston 11b is moved by the spring 11c.
The link 11d also moves downward with the point OX as a fulcrum, and the valve body 11e becomes fully closed.

To shift the valve body 11e of the steam control valve 8 from fully closed to fully open, first, the rapid-acting solenoid valve 14 is demagnetized and the piston 14a is moved to bring ports h and a into communication. Then, the pressure oil passes through the communication path and presses the disk dump valve 12, causing the empty chamber 11 to be pressed.
Close the base of a. At the same time, pilot valve 15
The piston 15a also moves, and ports c and d are also brought into communication. Then, the pressure oil is sent to the servo valve 13, and during this time, the spool (not shown) is moving due to the supply of pressure oil from the port g, and the oil cylinder 11 is sent from the communicating port through the oil path OP. Pressure oil is conducted to the empty chamber 11a. Pressure oil is piston 11
When biased to b, the link 11d is pulled upward, and the valve body 11e of the steam control valve 8 is opened.

[Problems with background technology]

By the way, as shown in FIG. 2, the opening/closing relationship between the steam control valve 8 and the bypass valve 9 is linked when a load cutoff command is input, and the steam control valve 8 is fully closed at time _t1 . On the other hand, the bypass valve 9 is designed to fully open at time _t2 . In other words, as is clear from the figure, the steam control valve 8 closes earlier than the time required for the bypass valve 9 to close completely. This is because if the steam control valve 8 is not closed quickly when the load cutoff command is received, it will cause the turbine impeller to overspeed, so the steam entering the turbine is cut off as soon as possible to prevent an accident from occurring. This is to prevent this.

However, while closing the steam control valve rapidly as described above is preferable from the perspective of overspeed prevention, on the other hand, the steam control valve closes before the bypass valve has yet to fully open, which would cause the reactor to react. The steam generation from the reactor becomes unstable, causing undesirable excessive thermal stress in the reactor core, etc., and also causes excessive vibration to the piping system of the turbine bypass line.

[Purpose of the invention]

Based on the above circumstances, the present invention, when closing the steam regulating valve, controls the operation of the disk dump valve incorporated in the valve drive device of the steam regulating valve within a range that does not affect overspeed prevention of the turbine. It is an object of the present invention to provide a valve drive device whose structure has been improved so that it operates relatively more slowly than before.

[Summary of the invention]

In order to achieve the above object, the present invention incorporates a piston that moves forward and backward and a disk dump valve into the casing of an oil cylinder that drives a valve body, and supplies and discharges pressure oil through a port drilled in the casing. In a valve driving device that moves the disk dump valve forward and backward by supplying and discharging this pressure oil, and moves the piston forward and backward with the help of this movement, the valve body is rapidly opened and closed. A protruding portion is provided to define a pressure oil passage communicating with the disk dump valve, and a constriction portion is provided transversely to the protruding portion.

With this configuration, when the pressure oil is discharged from the pressure oil passage to the outside of the oil cylinder, the area through which the amount of pressure oil passes through the pressure oil passage is reduced, and the time for discharging the pressure oil is made comparatively slower than in the past.

[Embodiments of the invention]

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

FIG. 4 shows an oil cylinder 40, which is part of a valve driving device for opening and closing a steam control valve used in thermal or nuclear power plants, for example. This oil cylinder 40 has ports 40a, 40b, 40c on both sides.
It has a cylindrical casing 4.

A piston 42 that opens and closes a steam control valve (not shown) is housed in the upper part of the casing 41 so as to be able to move forward and backward. A pressure oil passage 43 for moving the piston 42 forward and backward is provided. Note that the illustration shows the state when the steam control valve is closed, and the piston 42 is blocking the pressure oil passage 43.

The pressure oil passage 43 is located approximately at the center of the casing 41 and is partitioned by protrusions 44a and 44b that are integrally connected to the casing 41 and extend downward. In addition, there are vents 51 on both outsides of the pressure oil passage 43.
a, 51b are provided, and the ports 51a, 51b communicate with the port 40b.

On the other hand, a disk dump valve 45 is provided at the lower part of the pressure oil passage 43.
5 is adapted to move freely forward and backward by supplying and discharging pressure oil from the port 40c and by the elastic action of the spring 46 using a stopper pin 47 fitted into the base of the casing 41 as a guide.

On the other hand, the pressure oil passage 43 is provided with a constriction part 49 that adjusts the amount of pressure oil passing therethrough, and this constriction part 49 is specifically designed to be thick and thin as shown in FIG. A stepped rod portion 49a is formed to variably adjust the amount of pressurized oil. As shown in FIG. 5, this rod portion 49a moves back and forth across the pressure oil passage 43, and variably adjusts the amount of pressure oil passing through the pressure oil passage 43. On one side thereof, an O-ring 50a It is removably connected to a flange 50 interposed therebetween.

Therefore, in the valve driving device having the above configuration, when the steam regulating valve is rapidly closed (FIG. 4 shows the state in which the steam regulating valve is closed), the pressure oil in the empty chamber 51 of the oil cylinder 40 and the pressure oil passage 43 is is pulled out from the port 40a, whereby the piston 42 is connected to the pressure oil passage 43.
begins to descend below. Next, when the pressure oil is pulled out from the port 40c, the disk dump valve 45 instantly moves downward, and with this help, the pressure oil passage 43
The pressure oil inside is reversed through the pressure oil passage 43 and passed through the ports 51a and 5.
1b, flows to port 40b, and is sent out from here to the outside of casing 41. In this way, the pressure oil passage 4
During this period, the passage area of the pressure oil drawn out from 3 to the port 40b via the ports 51a and 51b is restricted by the restrictor 49, so the amount of pressure oil passing through is reduced by this amount. The closing speed is also slower than before. This delay is to keep pace with the full opening operation of the bypass valve mentioned above. Note that when the steam control valve closes and the piston 42 reaches the position shown in the fourth figure, the disk dump valve 45
is returned to the position shown by the elastic action of spring 46.

7 and 8 show other embodiments of the present invention, in which an orifice 70 is used as the throttle part and this orifice 70 is arranged transversely to the protrusions 44a and 44b that partition the oil passage 43. In addition, in FIG. 8, a raised portion 80 is provided at the tip of the protruding portions 44a and 44b that partition the pressure oil passage 43. Since the orifice 70 and the raised portion 80 also reduce the pressure oil passage area of the pressure oil passage 43, the same effect as in the first embodiment can be achieved.

〔Effect of the invention〕

As explained above, the present invention provides a protrusion for forming a pressure oil passage in the casing of an oil cylinder, and also provides a constriction portion that crosses this protrusion and the casing. , the pressure oil passage area of the pressure oil passage is reduced, and the valve can be closed later by that amount. Therefore, even if there is a load cut-off command, the closing and closing reverse operation times of the steam control valve and the bypass valve can be forced to match, and the conventional problems can be easily solved, making it practical. It can be provided to the public.

[Brief explanation of drawings]

Figure 1 is a schematic system diagram of a typical nuclear power plant, Figure 2 is a line diagram showing the opening/closing relationship between the steam regulator and bypass valve, and Figure 3 is a schematic control system showing the opening/closing operation of the steam regulator. 4 is a cross-sectional view showing a part of the oil cylinder that opens and closes the steam control valve according to the present invention, and FIG. 5 is a cross-sectional view taken along the - arrow in FIG.
FIG. 6 is a diagram showing that a plug is used as the throttle part according to the present invention, and FIGS. 7 and 8 are diagrams showing other embodiments of the present invention. 8...Steam control valve, 9...Bypass valve, 9a...
...Turbine bypass line, 11,40...Oil cylinder, 12,45...Disk dump valve, 41...
Casing, 43...Pressure oil passage, 44a, 44b...
...protruding part, 49... constriction part, 49a... plug,
70...orifice, 80...ridge.

Claims (1)

[Claims] 1. In the casing of the oil cylinder that drives the valve body,
It incorporates a piston that can move forward and backward, and a disk dump valve, and supplies and discharges pressure oil through a port drilled in the casing, and by supplying and discharging this pressure oil, the disk dump valve moves forward and backward, and with the help of this movement. In a valve drive device that rapidly opens and closes a valve body by advancing and retracting the piston, a protrusion is provided to define a pressure oil passage through which the piston and the disk dump valve communicate, and a transverse 1. A valve drive device characterized by having a throttle section for arranging the valve. 2. The valve driving device according to claim 1, wherein the throttle part is a rod part that moves forward and backward across the protrusion and makes variable the amount of pressure oil passing through the pressure oil passage. 3. The valve driving device according to claim 1, wherein the throttle portion is an orifice in which a protrusion is arranged transversely. 4. The valve driving device according to claim 1, wherein the throttle portion is a raised portion formed on the protruding portion.