Multifunctional protective valve

Abstract

The present invention relates to a multifunctional protective valve, comprising a valve body, a valve disc and a valve cover; the valve disc is characterized in that: a water hammer absorbing device and a forced closing device are arranged on the back of the valve disc; the positive medium pressure pushes the valve disc to open; when the medium is in the reverse direction, the valve disc is automatically closed by the gravity and back pressure of the valve disc, and at the same time, the negative pressure suction force generated by the water hammer absorbing device on the valve disc causes the valve disc to close slowly, avoiding the collision between the valve disc and the valve seat, eliminating the sound and absorbing the water hammer; when closing in an emergency, the pressure reducing valve of the forced closing device is opened to introduce the medium pressure of the valve body inlet into the upper piston chamber connected with the valve disc, and the valve disc is forced to close. The dual functions of a check valve and a stop valve are realized, and the valve disc has the advantages of simple structure, low manufacturing cost, good effect of eliminating sound and absorbing water hammer, reliable closing and sealing performance, etc.

Description

Technical Field

[0001] The invention belongs to the field of valves, and in particular to a multifunctional protective valve capable of preventing medium backflow and forcibly cutting off medium flow. The invention is suitable for protective valves at outlets of steam turbines, water turbines, and pump stations to prevent medium backflow and protect equipment safety. Background Art

[0002] In the pipeline system of steam turbines, water turbines, and pump stations, in order to prevent the medium from flowing back and damaging the equipment when the equipment is shut down, a check valve is generally installed at the outlet of the steam turbine, water turbine, and pump station. At the same time, for maintenance needs, a stop valve is generally installed on the inlet pipeline of the check valve. At present, the check valves used at the outlets of steam turbines, water turbines, and pump stations generally adopt hydraulically controlled slow-closing check valves, such as the accumulator-type hydraulically controlled slow-closing check valve with patent number CN201922245459.9, which includes a valve body, a valve disc, a valve shaft, a valve seat, a valve cover, a heavy hammer, and a hydraulic control device. The medium pressure and the energy storage of the heavy hammer are used to automatically control the opening and closing of the butterfly plate. It has the dual functions of a check valve and a stop valve, which reduces the installation space of the equipment, and reduces the equipment investment cost and operation and maintenance costs. Its main disadvantages are: the valve disc relies on the potential energy of the heavy hammer and the hydraulic cylinder to achieve slow closing, and its valve disc slow closing control performance is poor, the silencing and water hammer resistance effects are poor, the cut-off closing sealing performance is poor, and the structure is complex, and the product manufacturing cost is high. Summary of the invention

[0003] The purpose of the present invention is to provide a multifunctional protective valve with simple structure, low manufacturing cost, good effect of eliminating sound and absorbing water hammer, reliable closing and sealing performance, and check and cut-off functions in view of the shortcomings of the prior art.

[0004] The technical scheme of the present invention comprises a valve body, a valve disc and a valve cover. The valve body is a bottom-in and top-out structure. A valve seat is arranged between the inlet channel and the outlet channel of the valve body. The lower end face of the valve disc has a sealing surface that cooperates with the valve seat. The lower end face of the valve cover is sealed and connected with the upper end face of the valve body. The feature of the present invention is that a water hammer absorbing device and a forced closing device are arranged on the back of the valve disc. The water hammer absorbing device is composed of a lower piston cavity, an upper piston cavity, a lower piston and an upper piston. The lower piston cavity is composed of the lower end face of the valve cover and the inner cavity of the piston cylinder installed between the valve cover and the valve body. The upper piston cavity is composed of a cylindrical cavity arranged on the upper end of the valve cover and a sealed cavity composed of an upper cover. There is a balancing hole connecting the upper piston cavity and the lower piston cavity, the upper piston cooperates with the upper piston cavity in dynamic sealing, the lower piston cooperates with the lower piston cavity in dynamic sealing, the upper end of the guide rod on the back of the valve disc penetrates into the piston cylinder cavity and is fixedly connected to the lower piston, the diameter of the upper piston is larger than the diameter of the lower piston and the valve disc; low-pressure medium is injected into the lower piston cavity and the upper piston cavity between the upper end face of the lower piston and the lower end face of the upper piston through the injection valve; the forced closing device adopts a pressure reducing valve arranged between the upper end face of the upper piston and the inlet channel of the valve body, the inlet of the pressure reducing valve is connected with the inlet channel of the valve body through a conduit, and the outlet is connected with the upper piston cavity of the upper end face of the upper piston.

[0005] Preferably, the injection valve is mounted on the valve cover, and a pressure gauge is installed at the outlet of the injection valve; the outlet of the injection valve is connected to the lower piston chamber through a one-way valve, and the inlet of the injection valve is connected to the outlet channel of the valve body.

[0006] Preferably, the pressure of the medium injected into the lower piston cavity and the upper piston cavity between the upper end surface of the lower piston and the lower end surface of the upper piston is 0.1 MPa.

[0007] Compared with the prior art, the present invention has the following beneficial effects: a water hammer absorbing device and a forced closing device are arranged on the back of the valve disc; the positive medium pressure overcomes the low pressure medium pressure in the lower piston chamber and the upper piston chamber, and pushes the valve disc to open; in the case of reverse medium, the valve disc gravity and back pressure automatically close the valve disc, and when the lower piston moves downward, the negative pressure suction force on the valve disc generated in the process of pressure balance between the upper piston chamber and the lower piston chamber causes the valve disc to close slowly, avoiding the collision between the valve disc and the valve seat, eliminating the sound, and absorbing the water hammer; when closing in an emergency, the pressure reducing valve is opened to introduce the medium pressure of the valve body inlet into the upper end face of the upper piston, and the upper piston end face area is larger than the lower end face area of ​​the valve disc, and the downward thrust of the medium of the valve body inlet on the back of the valve disc is greater than the upward thrust of the lower end face of the valve disc, so that the valve disc is forced to close. The dual functions of the check valve and the stop valve are realized, and the advantages of simple structure, low manufacturing cost, good effect of eliminating sound and absorbing water hammer, reliable closing and sealing performance, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a structural schematic diagram of the present invention.

[0009] In the figure: 1 valve body, 2 valve seat, 3 valve disc, 4 guide rod, 5 piston cylinder, 6 lower piston, 7 injection valve, 8 pressure gauge, 9 valve cover, 10 upper cover, 11 pressure reducing valve, 12 conduit, 13 upper piston, 14 upper piston chamber, 15 lower piston chamber. DETAILED DESCRIPTION

[0010] like Figure 1The multifunctional protective valve shown comprises a valve body 1, a valve disc 3 and a valve cover 9. The valve body 1 is a bottom-in and top-out structure. A valve seat 2 is arranged between the inlet channel and the outlet channel of the valve body 1. The lower end face of the valve disc 3 has a sealing surface that cooperates with the valve seat 2. The lower end face of the valve cover 9 is sealed and connected with the upper end face of the valve body 1. The two are fixedly connected by bolts, nuts and flanges. The valve body 1 is characterized in that a water hammer absorbing device and a forced closing device are arranged on the back of the valve disc 3. The water hammer absorbing device is composed of a lower piston chamber 15, an upper piston chamber 14, a lower piston 6 and an upper piston 13. The lower piston chamber 15 is composed of the lower end face of the valve cover 9 and the inner cavity of a piston cylinder 5 installed between the valve cover 9 and the valve body 1. The upper piston chamber 14 is a sealed chamber composed of a cylindrical chamber at the upper end of the valve cover 9 and an upper cover 10. The upper cover 10 is fixedly mounted on the upper end surface of the cylindrical chamber of the valve cover 9 by bolts and nuts, and a sealing gasket is arranged between the two. The valve cover 9 is provided with a balancing hole connecting the upper piston chamber 14 and the lower piston chamber 15. The upper piston 13 is dynamically sealed with the upper piston chamber 14. The axial thickness of the upper piston 13 is less than 1 / 2 of the axial depth of the upper piston chamber 14, so that the upper piston 13 has sufficient axial up and down movement distance in the upper piston chamber 14. The lower piston 6 is dynamically sealed with the lower piston chamber 15. The axial thickness of the lower piston 6 is less than 1 / 2 of the axial height of the lower piston chamber 15, so that the lower piston 6 has a sufficient axial up-and-down moving distance in the lower piston chamber 15, the upper end of the guide rod 4 on the back of the valve disc 3 penetrates into the inner cavity of the piston cylinder 5 and is fixedly connected to the lower piston 6, and low-pressure medium is injected into the lower piston chamber 15 and the upper piston chamber 14 between the upper end surface of the lower piston 6 and the lower end surface of the upper piston 13 through the injection valve 7. The diameter of the upper piston 13 is larger than the diameter of the lower piston 6 and the valve disc 3. When the reverse medium pressure closes the valve disc 3, a large negative pressure is generated in the upper piston chamber 14 to control the valve disc 3 to close slowly, so as to avoid the collision between the valve disc 3 and the valve seat 2 to generate noise, vibration and water hammer; the forced closing device adopts a pressure relief valve 7 between the upper end surface of the upper piston 13 and the inlet channel of the valve body 1. A pressure reducing valve 11 is arranged in between, the inlet of the pressure reducing valve 11 is communicated with the inlet channel of the valve body 1 through the conduit 12, and the outlet is communicated with the upper piston cavity between the upper end face of the upper piston 13 and the lower end face of the upper cover 10. When the pipeline system equipment is overhauled, the pressure reducing valve 11 is opened to introduce the inlet medium pressure of the valve body 1 into the upper end face of the upper piston 13. By utilizing the fact that the end face area of ​​the upper piston 13 is larger than the end face area of ​​the valve disc 3, the downward thrust of the inlet medium of the valve body 1 on the back of the valve disc 3 is greater than the upward thrust of the lower end face of the valve disc 3, and the valve disc 3 is forced to be closed, realizing the function of the stop valve. By adjusting the pressure reducing valve 11, the pressure introduced into the end face of the upper piston 13 can be controlled to achieve reliable closure of the valve disc 3.

[0011] The injection valve 7 is installed on the valve cover 9, and a pressure gauge 8 is installed at the outlet of the injection valve 7 to detect the pressure value in the lower piston chamber 15. The outlet of the injection valve 7 is connected to the lower piston chamber 15 through a one-way valve, and the inlet of the injection valve 7 is connected to the outlet channel of the valve body 1. The outlet of the one-way valve is connected to the lower piston chamber 15 to prevent the medium of the lower piston chamber 15 from flowing to the outlet channel of the valve body 1. The medium of the outlet channel of the valve body 1 is decompressed by the injection valve 7 and then injected into the lower piston chamber 15 through the one-way valve. When the pressure value displayed by the pressure gauge 8 reaches the set pressure, the injection valve 7 is closed to prevent the medium of the outlet channel of the valve body 1 from flowing into the lower piston chamber 15 when the valve disc 3 is closed, so as to ensure the slow closing effect during the closing process of the valve disc 3. The injection valve 7 adopts an automatic control valve, which automatically closes when the detection value of the pressure gauge 8 reaches the pressure setting value, and automatically opens when the detection value of the pressure gauge 8 is lower than the pressure setting value. A manual control valve can also be adopted, and the injection valve 7 is opened and closed by manual operation.

[0012] The pressure of the medium injected into the lower piston chamber 15 and the upper piston chamber 14 between the upper end surface of the lower piston 6 and the lower end surface of the upper piston 13 is 0.1 MPa. The pressure value of the injected medium can be adjusted according to the pressure of the operating conditions, and the optimal value of the present invention is 0.1 MPa.

Claims

1. A multifunctional protective valve, comprising a valve body (1), a valve disc (3), and a valve cover (9); the valve body (1) is a bottom-in and top-out structure; a valve seat (2) is provided between an inlet channel and an outlet channel of the valve body (1); a lower end surface of the valve disc (3) has a sealing surface that cooperates with the valve seat (2); and a lower end surface of the valve cover (9) is sealingly connected to an upper end surface of the valve body (1); wherein: A water hammer absorbing device and a forced closing device are provided on the back of the valve disc (3); the water hammer absorbing device is composed of a lower piston chamber (15), an upper piston chamber (14), a lower piston (6), and an upper piston (13); the lower piston chamber (15) is composed of a lower end surface of the valve cover (9) and an inner chamber of a piston cylinder (5) installed between the valve cover (9) and the valve body (1); the upper piston chamber (14) is a sealed chamber composed of a cylindrical chamber at the upper end of the valve cover (9) and an upper cover (10); a balancing hole connecting the upper piston chamber (14) and the lower piston chamber (15) is formed on the valve cover (9); the upper piston (13) and the upper piston chamber (14) are dynamically sealed; the lower piston (6) and the lower piston chamber (15) are dynamically sealed; the valve disc ( 3) The upper end of the guide rod (4) on the back side penetrates into the inner cavity of the piston cylinder (5) and is fixedly connected to the lower piston (6); a low-pressure medium is injected into the lower piston cavity (15) and the upper piston cavity (14) between the upper end surface of the lower piston (6) and the lower end surface of the upper piston (13) through the injection valve (7); the diameter of the upper piston (13) is larger than the diameters of the lower piston (6) and the valve disc (3); the forced closing device is composed of a pressure reducing valve (11) arranged between the upper end surface of the upper piston (13) and the inlet channel of the valve body (1); the inlet of the pressure reducing valve (11) is connected to the inlet channel of the valve body (1) through the conduit (12), and the outlet is connected to the upper piston cavity between the upper end surface of the upper piston (13) and the lower end surface of the upper cover (10); The injection valve (7) is mounted on the valve cover (9), and a pressure gauge (8) is mounted at the outlet of the injection valve (7); the outlet of the injection valve (7) is connected to the lower piston chamber (15) via a one-way valve, the inlet of the injection valve (7) is connected to the outlet channel of the valve body (1), and the outlet of the one-way valve is connected to the lower piston chamber (15).

2. The multifunctional protective valve according to claim 1 is characterized in that: The pressure of the medium injected into the lower piston chamber (15) and the upper piston chamber (14) between the upper end surface of the lower piston (6) and the lower end surface of the upper piston (13) is 0.1 MPa.

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