JPH09280006A - Quick closing device of valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To moderate collision energy between a valve disc and a valve seat at quick closing of the valve by providing a second hydraulic damper formed out of a stopper shaft projectingly provided on the lower end of a piston and a guide hole for the stopper shaft drilled on the bottom part of a cylinder. SOLUTION: In a first hydraulic damper 12, a piston 1 is provided on a cylinder shaft 16 in a cylinder 15. A second hydraulic damper is formed out of a stopper shaft 2 projectingly provided on the lower end of the piston 1, and a guide hole 4 for the stopper shaft drilled on the bottom part of the cylinder 15. That is, the auxiliary second hydraulic damper is provided under the piston 1 of the first hydraulic damper 12, and it generates cushioning effect by resistance of fluid in the bottom part of the first hydraulic damper 12. By constituting the first hydraulic damper 12 into a double hydraulic damper construction as a whole, collision energy between a valve disc and a valve seat at quick closing of the valve is lightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve quick-closing device applied to a large-diameter valve of a steam turbine for thermal power generation.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory diagram of a conventional emergency speed governor (servo motor) used in a steam turbine for thermal power generation. In the figure, if the steam turbine is in an overspeed state for some reason, the steam flowing into the steam turbine must be shut off to stop the steam turbine in an emergency. This emergency speed governor is used for shutting off this steam, and relays high-pressure oil and control oil in the relay section 11 to drop the piston 13 of the hydraulic damper 12 in the direction shown by the arrow and connect it to the piston 13. The main shutoff valve (not shown), reheat shutoff valve, steam control valve, intercept valve, and other steam turbine valve levers 14 are pulled to rapidly close these valves. The hydraulic damper 12 is provided with a piston 13 on a cylinder shaft 16 in a cylinder 15, and a piston ring 17 is fitted on the piston 13. A stopper shaft 18, which also serves as a guide hole for the cylinder shaft 16, is projected from the lower end of the piston 13, and is inserted into the guide hole formed at the bottom of the cylinder 15.

[0003]

In the conventional emergency speed governor as described above, the main shutoff valve, the reheat shutoff valve, the steam control valve, due to the recent increase in capacity of the steam turbine for thermal power generation,
The diameters of steam turbine valves such as intercept valves are increasing, and the closing speed is also increasing in an emergency, and the collision energy of the valve bodies during the sudden closing of these valves becomes extremely large, which may damage the valve seat. There is.

[0004]

The quick closing device for a valve according to the present invention is intended to solve the above-mentioned problems, and the piston of the first fluid pressure damper is dropped and the lever connected to the piston is pulled. A second fluid pressure damper is formed by a stopper shaft projecting from the lower end of the piston and a guide hole of the stopper shaft formed in the cylinder bottom of the piston in the valve rapid closing device for closing the valve by the ing. In this way, the auxiliary second fluid pressure damper is also provided below the piston of the first fluid pressure damper, and the auxiliary second fluid pressure damper is used for the fluid at the bottom of the first fluid pressure damper. The resistance creates a cushioning effect. By making the first fluid pressure damper as a whole a dual fluid pressure damper structure, the collision energy between the valve body and the valve seat when the valve is rapidly closed is relaxed.

[0005]

1 and 2 are explanatory views of an emergency speed governor according to an embodiment of the present invention. In the figure, the emergency speed governor (servo motor) according to these embodiments is used in a steam turbine for thermal power generation, etc., and if the steam turbine becomes overspeed for some reason, The steam turbine must be shut down by shutting off the incoming steam. This emergency speed governor is used for the emergency shutoff of this steam. High pressure oil and control oil are relayed by a relay section (not shown) to drop the piston 1 of the hydraulic damper 12 in the direction shown by the arrow, and A main turbine stop valve, a reheat stop valve, a steam control valve, an intercept valve, and the like, which are not shown, are connected to pull a lever of a steam turbine valve, so that these valves are rapidly closed. The hydraulic damper 12 is a cylinder shaft 16 inside a cylinder 15.
1 is provided with a piston 1, and a piston ring 17 is fitted on the piston 1. A stopper shaft 2 which also serves as a guide for the cylinder shaft 16 is projected from the lower end of the piston 1, and is inserted into a guide hole 4 formed at the bottom of the cylinder 15.

In addition, as shown in FIG. 1A, the emergency speed governor according to the embodiment of the present invention has an outer periphery of the stopper shaft 2 which also serves as a guide for the cylinder shaft 16 formed at the lower end of the piston 1. Circumferential grooves 3 are engraved to increase the pressure loss. No piston ring is fitted in this groove 3. Further, the gap between the stopper shaft 2 and the guide hole 4 at the bottom of the cylinder 15 is made minute so as to have a cushion effect by hydraulic pressure. The groove 3
May be engraved in multiple layers. Further, as shown in FIG. 3B, an axial step 3a may be formed on the outer circumference of the stopper shaft 2 instead of the groove 3. In this way, by engraving the groove 3 or the step 3a on the outer periphery of the stopper shaft 2 at the lower end of the piston 1 and making the gap with the guide hole 4 small,
A hydraulic damper is also formed at the lower end of the piston 1. This auxiliary hydraulic damper produces a cushioning effect due to the resistance between the oil in the groove of the hydraulic damper 12 and the oil at the bottom.

Since the hydraulic damper is also formed at the lower end of the piston 1 as described above, the piston 1 has a double hydraulic damper structure as a whole. Fig. 2 shows the valve closing speed when the steam turbine valve is operated by the emergency speed governor in order to shut off the steam urgently, and is indicated by the dotted line in comparison with the case of the conventional emergency speed governor shown by the solid line in the figure. In the case of this emergency governor shown in, the valve closing speed in an emergency is slower, and therefore the collision energy is also smaller.

In the conventional emergency speed governor, due to the recent increase in the capacity of steam turbines for thermal power generation, the diameters of steam turbine valves such as a main stop valve, a reheat stop valve, a steam control valve, and an intercept valve have been changed. As the valve speed increases and the closing speed in an emergency also increases, the collision energy of the valve element at the time of sudden closing of these valves may become very large and may damage the valve seat. In the emergency speed governor according to the present invention, in order to eliminate such a defect, the groove 3 in the circumferential direction or the step in the axial direction is formed on the outer circumference of the stopper shaft 2 which also serves as a guide for the cylinder shaft 16 formed at the lower end of the piston 1. 3a is engraved, and the gap between the stopper shaft 2 and the guide hole 4 corresponding to the stopper shaft 2 is made minute so that the piston 1 and the stopper shaft 2 form a double hydraulic damper. Since the hydraulic damper 12 has the double hydraulic damper structure as described above, there is a risk that the collision energy between the valve body and the valve seat at the time of the rapid closing of the steam turbine valve is alleviated and the valve seat is damaged. As a result, the diameter of the steam turbine valve can be increased to increase the capacity of the steam turbine for thermal power generation.

[0009]

The valve rapid closing device according to the present invention is constructed as described above, and the first fluid pressure damper has a double fluid pressure damper structure, so that the valve body when the valve is rapidly closed. Since the collision energy between the valve seat and the valve seat is relaxed,
For example, even when the steam turbine valve for thermal power generation has a large capacity and the diameter of the steam turbine valve increases, the risk of the valve seat being damaged is reduced.

[Brief description of drawings]

FIG. 1 (a) is a sectional view of a hydraulic damper of an emergency speed governor according to an embodiment of the present invention, and FIG. 1 (b) is an emergency speed governor according to another embodiment of the present invention. 3 is a cross-sectional view of the hydraulic damper of FIG.

FIG. 2 is an explanatory diagram of these functions.

FIG. 3A is a sectional view of a conventional emergency speed governor, and FIG. 3B is a sectional view of a hydraulic damper thereof.

[Explanation of symbols]

 1 Piston 2 Stopper shaft 3 Groove 3a Step 4 Guide hole 12 Hydraulic damper 15 Cylinder 16 Cylinder shaft 17 Piston ring

Claims (1)

[Claims] 1. A quick closing device for a valve in which a valve of a first fluid pressure damper is dropped and a lever connected to the piston is pulled to close the valve, and a stopper shaft protruding from a lower end of the piston is provided. A quick closing device for a valve, comprising a second fluid pressure damper formed by a guide hole of the stopper shaft formed in the bottom of the cylinder of the piston.