Valve for centrifugal pump test

Abstract

The utility model discloses a valve for testing a centrifugal pump, relates to the field of pipeline systems, and aims to solve the problem that the valve position of a pipeline is easy to leak to cause cavitation when the centrifugal pump is tested at present, a shell is sleeved outside the rotary sealing position of a valve rod and a valve cover, and the shell is combined with the valve cover to form a water seal cavity for accommodating water; after water is injected into the water seal cavity, the sealing filler at the rotary sealing position can be immersed, so that water sealing of the rotary sealing position is achieved, when leakage occurs due to negative pressure, water in the water seal cavity is supplemented into a pipeline, the problem that external air enters the pipeline is solved, the cavitation problem is weakened, and the centrifugal pump testing requirement is met.

Description

Technical Field

[0001] The utility model relates to the field of pipeline systems, and particularly relates to a valve for centrifugal pump testing. Background Art

[0002] When the centrifugal pump is filled with water, the impeller of the pump rotates to generate centrifugal force. The water in the impeller flow path is thrown to the periphery under the action of centrifugal force and flows into the pump body. As a result, the pressure at the center of the pump impeller decreases. This pressure is lower than the pressure in the inlet pipe. Under the action of this pressure difference, water is sucked into the impeller from the storage tank. To save costs and reduce site occupation, the storage tank is usually set underground below the plane of the test pump. This requires the centrifugal pump to suck the medium from a lower position to a higher position during the experiment. This process will generate negative pressure in the pipeline for transporting the medium, making the pressure in the pipeline lower than the atmospheric pressure. Under the action of this negative pressure, the air outside the pipeline will flow into the pipeline from the valve seal. The traditional valve uses packing Graphite (graphite) for sealing, which is difficult to ensure tightness. After the air enters the pipeline, because the density of the gas is less than that of the liquid, the centrifugal force generated is small, and the centrifugal pump cannot throw the air out. The negative pressure generated when the fluid in the pump body makes a centrifugal motion with the motor is not enough to suck new liquid into the pump body, which will cause cavitation in the centrifugal pump, resulting in violent vibration and accompanied by strong and harsh noise, affecting the efficiency and normal operation of the centrifugal pump for transporting liquid. Seriously, it will cause the pump to run idly, resulting in dry friction and burning of parts such as the impeller, causing serious consequences.

[0003] Chinese Patent (CN108533761 A) discloses a multi-sealed bellows globe valve, which adopts a double-sealed design. A packing pad and a combined packing seal are provided at the part of the valve stem above the bellows. If the bellows fails, the valve stem packing will also prevent leakage. It improves the sealing performance by increasing the number of sealing structures, but the method of using packing is still difficult to cope with gas leakage under negative pressure, resulting in external gas entering the pipeline through the valve, easily causing cavitation in the centrifugal pump and causing vibration of the centrifugal pump, affecting the test process of the centrifugal pump. Summary of the Utility Model

[0004] The purpose of the utility model is to address the deficiencies existing in the prior art and provide a valve for centrifugal pump testing. A housing is sleeved outside the rotational sealing position of the valve stem and the valve cover. The housing and the valve cover form a water seal cavity for containing water. After the water seal cavity is filled with water, the sealing packing at the rotational sealing position can be immersed, so as to realize the water seal of the rotational sealing position. When leakage occurs due to negative pressure, the water in the water seal cavity is replenished into the pipeline to reduce the problem of external gas entering the pipeline, thereby weakening the cavitation problem and meeting the test requirements of the centrifugal pump.

[0005] To achieve the above purpose, the following technical solutions are adopted:

[0006] A valve for centrifugal pump testing, comprising:

[0007] It includes a valve body, a valve cover, a valve stem and a housing. The valve cover is detachably connected to the valve body. One end of the valve stem passes through the valve cover and extends into the valve body to connect to the valve flap, and the other end is located outside the valve cover and connected to the handwheel. A valve seat is provided in the valve body, and the valve seat divides the valve cavity in the valve body into a liquid inlet cavity and a liquid outlet cavity. The valve flap and the valve seat form a sealing pair; a sealing packing is provided between the valve stem and the valve cover, the valve cover is connected with a packing gland, and the packing pressing rod axially presses the sealing packing along the valve stem.

[0008] The part of the valve stem located outside the valve cover is provided with a threaded section, which is matched with a valve stem nut, and the valve stem nut is fixed to the valve cover; a housing is sleeved outside the valve stem. The housing is cylindrical. One end of the housing is connected to the valve cover to seal, and the other end is open and located between the handwheel and the packing gland. The housing and the end face of the valve cover form a water seal cavity to accommodate water to form a water seal at the sealing packing.

[0009] Further, the housing and the valve stem are coaxially distributed, there is an interval distribution between the housing and the valve stem, and the outer circumference of the housing is flush with the outer circumference of the valve cover.

[0010] Further, a liquid level viewing window is provided on the side wall of the housing, and the liquid level viewing window is distributed along the generatrix direction of the side wall of the housing.

[0011] Further, a through hole penetrating the side wall in the radial direction is provided on the side wall of the housing, and the through hole is blocked by a transparent plate, and scale lines are provided on the transparent plate.

[0012] Further, waterproof layers are provided on the inner wall of the housing corresponding to the water seal cavity, the packing gland, the valve stem, the valve cover, and the surface of the valve stem nut.

[0013] Further, the valve stem nut is fixed above the valve cover through a bracket, the valve stem passes through the packing gland and the sealing packing, and the packing gland is located between the valve stem nut and the valve cover.

[0014] Further, the valve cover and the valve body are connected by flange and fasteners.

[0015] Further, a cylindrical part for accommodating the sealing packing is provided on the valve cover. The valve stem passes through the cylindrical part, and the sealing packing is located between the inner wall of the cylindrical part and the outer wall of the valve stem. One end of the packing gland extends into the cylindrical part axially to contact the sealing packing, and the other end of the packing gland is installed on the valve cover through a gland fastener.

[0016] Further, a blind hole is provided on the valve flap. One end of the valve stem extends into the blind hole of the valve flap. A split ring is sleeved outside the valve stem located in the blind hole. A valve flap cover is installed at the open end of the blind hole, and the valve flap cover axially presses the split ring to make the split ring expand radially, so as to establish a connection between the valve stem and the valve flap.

[0017] Further, the valve flap cover is fixed to the valve flap.

[0018] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0019] Aiming at the problem that the valve position in the pipeline is prone to leakage and cavitation during the current centrifugal pump test, a housing is sleeved outside the rotational sealing position of the valve stem and the valve cover. The housing and the valve cover form a water seal cavity for containing water. After the water seal cavity is filled with water, the sealing packing at the rotational sealing position can be immersed, so as to realize the water seal of the rotational sealing position. When leakage occurs due to negative pressure, the water in the water seal cavity is supplemented into the pipeline to reduce the problem of external gas entering the pipeline, thereby weakening the cavitation problem and meeting the requirements of centrifugal pump testing.

[0020] In the present utility model, waterproof layers are provided on the inner wall of the housing corresponding to the water seal cavity, the packing gland, the valve stem, the valve cover, and the surface of the valve stem nut to reduce the corrosion problem of each component in the water seal cavity and ensure the long-term service of the valve for centrifugal pump testing. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the valve for centrifugal pump testing in the embodiment of the present utility model.

[0022] Label description (in the order of first appearance): 1. Valve body, 2. Valve flap, 3. Split ring, 4. Valve flap cover, 5. Valve stem, 6. Valve cover, 7. Sealing packing, 8. Packing gland, 9. Valve stem nut, 10. Handwheel, 11. Handwheel nut, 12. Housing, 13. Gland nut, 14. Gland bolt, 15. Flange nut, 16. Sealing gasket, 17. Flange bolt, 18. Valve seat. Detailed Embodiment

[0023] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application.

[0024] In the current pipeline for testing centrifugal pumps, the rotational sealing position of the valve is prone to leakage, resulting in external gas entering the pipeline through the valve, which is likely to cause cavitation in the centrifugal pump, resulting in vibration of the centrifugal pump and affecting the testing process of the centrifugal pump. Based on this, a valve for centrifugal pump testing is provided in this embodiment. The housing 12 and the valve cover 6 can form a water seal cavity, and the rotational sealing position is located in the water seal cavity. After the water seal cavity is filled with water, the rotational sealing position can be immersed, thereby forming a water seal. The water in the water seal cavity is used to compensate for the leakage caused by negative pressure in the pipeline, reduce the gas entering the pipeline, and thus weaken the cavitation problem.

[0025] As Figure 1As shown in the figure, the valve for centrifugal pump testing includes a valve body 1, a valve stem 5, a valve cover 6, and a housing 12. A bracket is fixedly connected to the valve cover 6, and a valve cover 6 nut is installed through the bracket. The valve cover 6 and the valve body 1 are detachably and fixedly connected. A handwheel 10 and a valve flap 2 are respectively arranged at the top and bottom of the valve stem 5. A valve seat 18 is arranged inside the valve body 1, and the valve seat 18 divides the valve cavity of the valve body 1 into a liquid inlet cavity and a liquid outlet cavity. The valve flap 2 is arranged in the liquid inlet cavity and forms a sealing pair with the valve seat 18. A sealing packing 7 is arranged between the valve stem 5 and the valve cover 6. The sealing packing 7 is tightly installed by a packing gland 8 arranged at the top end of the valve cover 6 and a cylinder body preset on the valve cover 6. A sealing gasket 16 is arranged at the bottom end of the valve cover 6 to achieve the sealing of the connection position between the valve cover 6 and the valve body 1.

[0026] When the valve for centrifugal pump testing is fully opened, the valve stem 5 moves upward to drive the valve flap 2 to lift away from the valve seat 18, so that the liquid inlet cavity and the liquid outlet cavity are communicated; when the valve for centrifugal pump testing is blocked, the valve stem 5 moves downward to drive the valve flap 2 to descend and fit the valve seat 18, thereby isolating the liquid inlet cavity and the liquid outlet cavity.

[0027] As Figure 1 shown in the figure, the valve cover 6 and the valve body 1 are detachably connected. One end of the valve stem 5 passes through the valve cover 6 and extends into the valve body 1 to connect the valve flap 2, and the other end is located outside the valve cover 6 and connects the handwheel 10; the valve cover 6 is connected with a packing gland 8, and the packing rod axially presses the sealing packing 7 along the valve stem 5. Among them, the end of the valve stem 5 fixes the handwheel 10 through a handwheel nut 11, so that the handwheel 10 can be coaxially matched with the valve stem 5 and simultaneously rotate synchronously under the action of external force.

[0028] A threaded section is arranged on the part of the valve stem 5 located outside the valve cover 6. The threaded section is matched with a valve stem nut 9. The valve stem nut 9 is fixed to the valve cover 6. By driving the valve stem 5 to rotate relative to the valve stem nut 9 through the handwheel 10, the valve stem 5 moves axially.

[0029] A housing 12 is sleeved outside the valve stem 5. The housing 12 is in a cylindrical shape. One end of the housing 12 is connected to the valve cover 6 for blocking, and the other end is open and located between the handwheel 10 and the packing gland 8. The housing 12 and the end face of the valve cover 6 form a water seal cavity to accommodate water to form a water seal at the sealing packing 7.

[0030] The valve cover 6 and the valve body 1 are connected by flanges and fasteners. The valve cover 6 and the valve body 1 are filled and squeezed for sealing through a sealing gasket 16. In this embodiment, the fasteners include a flange nut 15 and a flange bolt 17. The valve body 1 and the valve cover 6 are connected by the flange bolt 17 and the flange nut 15.

[0031] For the rotating sealing position, as Figure 1As shown, the valve cover 6 is provided with a cylindrical part for accommodating the packing 7. The valve stem 5 passes through the cylindrical part, and the packing 7 is located between the inner wall of the cylindrical part and the outer wall of the valve stem 5. One end of the packing gland 8 extends axially into the cylindrical part to contact the packing 7, and the other end of the packing gland 8 is installed on the valve cover 6 through a gland fastener.

[0032] A stepped hole is formed in the cylindrical part. The packing 7 is extruded into a cylindrical shape. One axial end of it is subjected to the extrusion of the packing gland 8, and the other axial end is blocked by the stepped position of the stepped hole in the cylindrical part, thereby realizing the extrusion seal of the packing 7.

[0033] On the outside of the cylindrical part, there is an ear plate with holes. The ear plate with holes cooperates with the gland fastener to connect the packing gland 8. The gland fastener includes a gland bolt 14 and a gland nut 13. The gland bolt 14 passes through the openings on the ear plate with holes and the openings on the packing pressing rod and then cooperates with the gland nut 13 to realize the fixed pressing of the packing gland 8.

[0034] As Figure 1 shown, the valve flap 2 is provided with a blind hole. One end of the valve stem 5 extends into the blind hole of the valve flap 2. A split ring 3 is sleeved outside the valve stem 5 located in the blind hole. A valve flap cover 4 is installed at the open end of the blind hole. The valve flap cover 4 axially squeezes the split ring 3 to make the split ring 3 expand radially, so as to establish a connection between the valve stem 5 and the valve flap 2.

[0035] The split ring 3 can be composed of two rubber half rings. An annular groove is provided on the section of the valve stem 5 extending into the blind hole. The two rubber half rings are embedded in the annular groove. After being squeezed by the valve flap cover 4, the two rubber half rings can expand radially, thereby filling the space between the valve stem 5 and the inner wall of the blind hole to realize expansion fixation.

[0036] The valve flap cover 4 is fixed to the valve flap 2, and can be fixed by welding.

[0037] As Figure 1 shown, the housing 12 and the valve stem 5 are coaxially distributed, and there is an interval between the housing 12 and the valve stem 5. The water seal chamber is located within this interval, and the outer circumference of the housing 12 is flush with the outer circumference of the valve cover 6.

[0038] The outside of the valve stem nut 9 is sleeved with the housing 12. The housing 12 is in a cylindrical structure. One end of the housing 12 is connected to the valve cover 6 to realize sealing, and the other end is open. And the open end of the cylindrical structure is located above the packing seal. A columnar water seal chamber is formed within the inner circle of the housing 12 and above the valve cover 6. Water can be accommodated in the water seal chamber, and the water level in the water seal chamber is controlled to be above the packing seal of the valve stem 5 to realize the water seal of the packing seal position of the valve stem 5.

[0039] To ensure the water level in the water seal chamber, water can be added to the water seal chamber regularly to keep the water level in the water seal chamber above the packing seal of the valve stem 5; or water can be continuously added to the water seal chamber to keep the water seal chamber full of water.

[0040] In addition, after the water seal chamber is filled with water, the components on the surface of the water seal chamber are prone to rust due to water level changes during long-term use. To address this, the components in the water seal chamber can be sprayed with anti-rust paint or anti-rust material components can be used to reduce the rust problem of each component in the water seal chamber. A waterproof layer is provided on the inner wall of the housing 12 corresponding to the water seal chamber, the packing gland 8, the valve stem 5, the valve cover 6, and the surface of the valve stem nut 9.

[0041] In this embodiment, the surfaces of the valve cover 6, the inner wall of the housing 12, the packing gland 8, the valve stem nut 9, and the gland fastener are sprayed with an anti-rust layer to establish a waterproof layer. A lubricating grease is covered on the section of the valve stem 5 located in the water seal chamber to achieve the purpose of isolating the water in the water seal chamber and establish a waterproof layer. The valve stem 5 can also be made of stainless steel to improve its anti-rust ability.

[0042] Specifically, the anti-rust layer can be an anti-rust coating such as anti-rust paint. The threaded section of the valve stem 5 is coated with lubricating grease to isolate the section of the valve stem 5 in the water seal chamber from the water in the water seal chamber, improving its anti-rust ability and meeting the requirements of long-term water seal.

[0043] For the housing 12, after forming the water seal chamber for accommodating water in combination with the valve cover 6, it is necessary to ensure that the water level in the water seal chamber is above the packing seal 7, so that the packing seal 7 is immersed in the water in the water seal chamber, thereby plugging the leakage at the rotational seal position of the valve stem 5 and the valve cover 6.

[0044] To control the water level, a water level window is provided on the side wall of the housing 12. The water level window is composed of a through hole opened on the side wall of the housing 12 and a transparent plate. The through hole penetrates the side wall of the housing 12 and extends along the generatrix direction of the side wall of the housing 12. The through hole is blocked by the transparent plate. Through the through hole and the transparent plate, the water level in the water seal chamber of the housing 12 can be observed. When the entire centrifugal pump test valve is at a high position, the water level in the water seal chamber can still be quickly grasped through the side water level window. Scale lines are provided on the transparent plate to facilitate reading the water level in the water seal chamber.

[0045] It can be understood that the warning water level is determined according to the lowest water level that can achieve water seal and is marked on the transparent plate in scale. When the water level is flush with or lower than the warning water level, water is added to the water seal chamber in a timely manner. The scale of the warning water level can be marked with eye-catching marks, such as red arrows, red leads, etc., to facilitate comparison between the actual water level in the water seal chamber and the warning water level.

[0046] The specific embodiments of the utility model have been described in detail above, but they are only examples, and the utility model is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the utility model are also within the scope of the utility model. Therefore, all equivalent transformations, modifications, improvements, etc. made without departing from the spirit and principles of the utility model should be covered within the scope of the utility model.

Claims

1. A valve for centrifugal pump testing, characterized in that, It includes a valve body, a valve cover, a valve stem and a housing. The valve cover is detachably connected to the valve body. One end of the valve stem passes through the valve cover and extends into the valve body to connect to the valve disc, and the other end is located outside the valve cover and connects to the handwheel. A valve seat is provided in the valve body, and the valve seat divides the valve cavity in the valve body into a liquid inlet cavity and a liquid outlet cavity. The valve disc and the valve seat form a sealing pair. A sealing packing is provided between the valve stem and the valve cover. The valve cover is connected with a packing gland, and the packing rod axially presses the sealing packing along the valve stem. The part of the valve stem outside the valve cover is provided with a threaded section, and the threaded section is matched with a valve stem nut, and the valve stem nut is fixed to the valve cover. A housing is sleeved outside the valve stem. The housing is in a cylindrical shape. One end of the housing is connected to the valve cover for sealing, and the other end is open and located between the handwheel and the packing gland. The housing and the valve cover end face form a water seal cavity to accommodate water to form a water seal at the sealing packing.

2. The valve for centrifugal pump testing according to claim 1, characterized in that, The housing and the valve stem are coaxially distributed, and there is an interval between the housing and the valve stem. The outer circumference of the housing is flush with the outer circumference of the valve cover.

3. The valve for centrifugal pump testing according to claim 1 or 2, characterized in that, A liquid level viewing window is provided on the side wall of the housing, and the liquid level viewing window is distributed along the generatrix direction of the housing side wall.

4. The valve for centrifugal pump testing according to claim 3, characterized in that, A through hole penetrating the side wall in the radial direction is provided on the side wall of the housing, and the through hole is blocked by a transparent plate, and scale lines are provided on the transparent plate.

5. The valve for centrifugal pump testing according to claim 1, characterized in that, A waterproof layer is provided on the inner wall of the housing corresponding to the water seal cavity, the packing gland, the valve stem, the valve cover and the surface of the valve stem nut.

6. The valve for centrifugal pump testing according to claim 1, characterized in that, The valve stem nut is fixed above the valve cover through a bracket. The valve stem passes through the packing gland and the sealing packing, and the packing gland is located between the valve stem nut and the valve cover.

7. The valve for centrifugal pump testing according to claim 1 or 5 or 6, characterized in that, The valve cover and the valve body are connected by flange and fasteners.

8. The valve for centrifugal pump testing according to claim 7, wherein, A cylindrical part for accommodating the sealing packing is provided on the valve cover. The valve stem passes through the cylindrical part. The sealing packing is located between the inner wall of the cylindrical part and the outer wall of the valve stem. One end of the packing gland extends into the cylindrical part axially to contact the sealing packing, and the other end of the packing gland is installed on the valve cover through a gland fastener.

9. The valve for centrifugal pump testing according to claim 1, characterized in that, A blind hole is provided on the valve disc. One end of the valve stem extends into the blind hole of the valve disc. A split ring is sleeved outside the valve stem located in the blind hole. A valve disc cover is installed at the open end of the blind hole. The valve disc cover axially presses the split ring to make the split ring expand radially, so as to establish a connection between the valve stem and the valve disc.

10. The valve for centrifugal pump testing according to claim 9, characterized in that, The valve disc cover is fixed to the valve disc.

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