A bidirectional high temperature and high pressure self-balancing cut-off valve

Abstract

The present invention discloses a bidirectional high-temperature and high-pressure self-balancing shut-off valve, comprising a valve body, a valve cover, a valve disc and a valve stem; a balancing hole is arranged on the valve disc or the valve stem; a composite sealing ring is arranged between the inner surface of the valve body and the outer surface of the valve disc; the composite sealing ring comprises an upper gasket, an upper sealing ring, an upper dividing ring, a lower dividing ring and a lower sealing ring in order from top to bottom, and a blocking ring is sleeved on the outer side of the upper gasket. The present invention has a bidirectional pressure self-balancing and bidirectional self-sealing structure, which greatly reduces the operating force of opening and closing the valve. Compared with the prior art, it can not only significantly reduce the energy consumption of the driving device of the electric, pneumatic and hydraulic valves, but also has reliable sealing, long service life and simple manufacturing method, and is suitable for various pressure pipelines with bidirectional or unidirectional flow; at the same time, the seal is made of high temperature and corrosion resistant materials, especially for large diameter high temperature and high pressure pipelines in the power, petrochemical and other industries.

Description

Technical Field

[0001] The invention relates to a valve, in particular to a bidirectional high-temperature and high-pressure self-balancing cut-off valve for cutting off or connecting a bidirectional flow medium pipeline in a high-temperature, high-pressure or corrosive environment. Background Art

[0002] Valves are important and indispensable mechanical products for pressure pipelines, and are widely used in the fields of petrochemical, oil fields, metallurgy, thermal power, nuclear power, and ships. In the use of existing valve products, it is necessary to overcome the medium pressure on the opening and closing parts to open and close the valve. When the valve is used in high-temperature, high-pressure and large-diameter pipelines, an external bypass auxiliary valve must be configured to release the pressure before it can be opened and closed. The medium pressure not only makes the valve operation very difficult, but also easily causes damage and leakage to the valve sealing surface.

[0003] The pressure self-balancing valve can balance the medium pressure acting on the opening and closing parts through the principle of pressure self-balancing, fundamentally eliminating the influence of medium pressure on valve operating performance, sealing quality and sealing life. The pressure self-balancing valve is an important way to transform and upgrade existing valve products, and the key technology to realize the pressure self-balancing stop valve is the sealing of the pressure self-balancing structure. In the existing technology, "O" type, "Y" type and other sealing rings are usually used to seal the pressure self-balancing structure. Since this type of sealing technology can convert the medium pressure into the pressure self-sealing of the sealing ring to the medium, the sealing ring can obtain a very good sealing effect without a large sealing pre-tightening force. In the process of using the sealing ring, the sealing effect of the sealing ring is not only independent of the level of the medium pressure, but also does not change with the decrease of the sealing pre-tightening force after the sealing ring is worn. Therefore, it has a long-lasting and reliable sealing quality and sealing life. However, in actual applications, there are a large number of bidirectional high-temperature and high-pressure pipelines in pipeline systems such as petrochemical, oil fields, metallurgy or power plants. For example, a high-pressure valve must be configured in front of a high-pressure water pump used to replenish water to boilers, mines, oil wells, etc. When the water pump supplies water, the valve needs to be opened to make the water supply pipeline unobstructed, and when the water pump stops supplying water, the valve needs to be closed to prevent the backflow of the supplied high-pressure water. For example, in the power generation process of a thermal power plant, the high-temperature and high-pressure steam generated by multiple boilers needs to be sent to the common mother pipe through high-pressure valves. When the gas supply of some boilers is stopped, the valve also needs to be closed to prevent the backflow of high-temperature and high-pressure steam. Since the high-density elastic materials that can be used to make "O" type and "Y" type sealing rings are all rubbers and plastics that are not resistant to high temperatures, the existing pressure self-balancing stop valve is only suitable for medium environments below 200°C, and cannot be used for high-temperature pressure pipelines with large areas such as steam.

[0004] To solve the above problems, the invention patent application submitted by the inventor in 2018 (application number 201810862132.3) provides a bidirectional pressure self-balancing stop valve, in which a composite sealing ring is arranged on the valve disc, and the composite sealing ring includes a pressure ring, a blocking ring, an upper gasket, an upper sealing ring, an upper spacer ring, a lower spacer ring and a lower sealing ring from top to bottom. The lower end face of the pressure ring and the upper end face of the upper gasket are shaped as a conical surface, an inclined surface, a plane or a spherical surface that squeezes the blocking ring toward the inner direction of the valve disc, the lower end face of the upper gasket and the upper end face of the upper spacer ring are shaped as a conical surface, an inclined surface or a spherical surface that squeezes the upper sealing ring toward the outer direction of the valve disc, and the lower end face of the lower spacer ring and the upper end face of the valve disc are shaped as a conical surface, an inclined surface or a spherical surface that squeezes the lower sealing ring toward the outer direction of the valve disc; but the structure of the above-mentioned valve is relatively complicated, especially the blocking ring is arranged on the upper gasket, and the upper gasket is arranged on the elastic sealing ring. When the pressure ring presses the blocking ring, due to the lack of limiting measures for the upper gasket, the upper gasket will slide downward along the sealing ring, making it difficult for the extrusion force applied by the pressure ring to effectively act on the blocking ring, so it is also difficult to obtain a sufficiently large sealing blocking force on the inner circle of the blocking ring and the upper end face of the upper gasket. Therefore, not only is the assembly difficult, but it also directly affects the sealing effect of the high-pressure medium. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a shut-off valve for installation on a medium bidirectional flow pipeline under high temperature, high pressure or corrosive environment.

[0006] Technical solution: The bidirectional high-temperature and high-pressure self-balancing shut-off valve of the present invention includes a valve body, a valve cover, a valve stem and a valve disc. The valve body is provided with an upper valve body channel, a lower valve body channel and a valve body channel connecting the upper valve body channel and the lower valve body channel; it also includes a composite sealing ring and a blocking ring. The composite sealing ring includes an upper gasket, an upper sealing ring, an upper split ring, a lower split ring and a lower sealing ring which are sequentially sleeved on the outside of the valve disc from the valve cover to the valve body. The blocking ring is sleeved on the outside of the upper gasket. A balancing hole connecting the inner cavity of the valve disc and the upper cavity of the valve body is opened on the valve disc or the valve stem.

[0007] The side end face of the upper gasket is a conical surface, inclined surface, plane or spherical surface that squeezes the blocking ring toward the valve body; the lower end face of the upper gasket and the upper end face of the upper sub-ring are shaped like a conical surface, inclined surface or spherical surface that squeezes the upper sealing ring toward the valve body; the lower end face of the lower sub-ring and the upper end face of the valve body are shaped like a conical surface, inclined surface or spherical surface that squeezes the lower sealing ring toward the valve body.

[0008] The inner surface of the valve body is provided with an annular sealing ring accommodating groove and a blocking ring accommodating groove; the outer surface of the valve disc and the inner surface of the valve body are gap-matched with the upper gasket, upper sub-ring and lower sub-ring; there is a gap between the lower end surface of the upper sub-ring and the upper end surface of the lower sub-ring; the lower end surface of the valve disc and the inner channel of the valve body have matching sealing surfaces, and the sealing surfaces are plane, conical or spherical; a clamping piece is installed between the upper gasket and the valve cover, and the clamping piece is threadedly connected to the valve body; the blocking ring, upper sealing ring and lower sealing ring are made of flexible graphite or polytetrafluoroethylene material.

[0009] Beneficial effects: Compared with the prior art, the present invention has the following advantages: a bidirectional pressure self-sealing structure is proposed, which uses a sealing ring made of low-density, high-temperature resistant or corrosion-resistant materials to form a sealing structure, which has excellent pressure self-sealing characteristics and durable and reliable sealing quality and sealing life, simple assembly, high reliability, more reasonable force relationship between seals, and can be applied to high temperature, high pressure or corrosive environments. The medium pressure on the valve disc is self-balanced, the valve operation is easy, the labor intensity of manual operation of manual valves and the energy consumption of electric and pneumatic valves are reduced, and it is suitable for pipelines with large diameters and bidirectional flow of media, with good safety and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of a preferred embodiment of the present invention;

[0011] Figure 2 for Figure 1 A partial enlarged view of the middle A;

[0012] Figure 3 This is a schematic diagram of the extrusion force when the upper sealing ring of the present invention is pre-tightened;

[0013] Figure 4 This is a schematic diagram of the extrusion force when the lower sealing ring of the present invention is pre-tightened;

[0014] Figure 5 It is a schematic diagram of the medium pressure self-sealing force of the upper sealing ring of the present invention;

[0015] Figure 6 It is a schematic diagram of the medium pressure self-sealing force of the lower sealing ring of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0017] The bidirectional high-temperature and high-pressure self-balancing cut-off valve of this embodiment is as follows: Figure 1As shown, it includes a valve body 1, a valve disc 4, a valve cover 18, a valve stem 19, a clamping piece 17, a blocking ring 13 and a composite sealing ring composed of an upper gasket 15, an upper sealing ring 11, an upper sub-ring 10, a lower sub-ring 9 and a lower sealing ring 7. The blocking ring 13 is arranged outside the upper gasket 15, and a clamping piece 17 is installed between the upper gasket and the valve cover.

[0018] The valve cover 18 is fixedly connected to the valve body 1, the valve stem 19 passes through the valve cover 18, the lower end of the valve stem is connected to the valve disc 4 and can carry the valve disc 4 to move up and down along the inner surface of the valve body 1 to complete the opening or closing of the valve.

[0019] An upper channel 3, a lower channel 33 and an inner channel 35 connecting the upper channel 3 and the lower channel 33 are provided in the valve body 1. The valve flap 4 is arranged in the cavity of the valve body 1. The upper end surface of the inner channel 35 and the lower end surface of the valve flap 4 are provided with sealing surfaces that cooperate with each other, and the shape of the sealing surfaces is a plane, a conical surface or a spherical surface.

[0020] The valve disc 4 or the valve stem 19 is provided with a balancing hole 21 for connecting the lower channel 33 located below the lower end surface 34 of the valve disc 4 and the upper cavity 16 of the valve body located above the upper end surface 20 of the valve disc 4;

[0021] An annular sealing ring receiving groove and a blocking ring receiving groove are provided on the inner surface of the valve body 1. The upper gasket 15, the upper sealing ring 11, the upper sub-ring 10, the lower sub-ring 9 and the lower sealing ring 7 are arranged in the sealing ring receiving groove from top to bottom, and the blocking ring is located in the blocking ring receiving groove;

[0022] There is a gap between the lower end surface 26 of the upper sub-ring 10 and the upper end surface 27 of the lower sub-ring 9. The outer circle 5 of the valve disc 4 is in clearance fit with the inner circle of the upper gasket 15, the upper sub-ring 10, the lower sub-ring 9 and the valve body 1;

[0023] The blocking ring 13, the upper sealing ring 11 and the lower sealing ring 7 are made of sealing materials. In this embodiment, in order to achieve the purpose of high temperature resistance, the sealing material is flexible graphite. In practical applications, different sealing materials can be used as needed.

[0024] The shape of the side end surface 14 of the upper gasket 15 is a conical surface, an inclined surface, a plane or a spherical surface that presses the blocking ring 13 toward the side end surface 12 of the valve body 1. The purpose is to tighten the clamping member 17 so that the side end surface 14 of the upper gasket 15 presses the blocking ring 13 toward the side end surface 12 of the valve body 1, thereby blocking the medium from penetrating into the outer cylindrical surface 23 of the upper sealing ring 11 and continuing to flow along the medium channel between the upper gasket 15 and the valve body 1;

[0025] The lower end surface 22 of the upper gasket 15 and the upper end surface 25 of the upper sub-ring 10 are shaped as a conical surface, an inclined surface or a spherical surface that presses the upper sealing ring 11 inwardly of the valve body 1; by tightening the pressing piece 17, the upper gasket 15 and the upper sub-ring 10 jointly press the upper sealing ring 11 inwardly, and the inner circular surface 24 of the upper sealing ring 11 obtains a greater sealing pre-tightening force than its outer circular surface 23, so that the medium is convenient to squeeze into the outer circular surface 23 of the upper sealing ring 11 with a smaller pre-tightening force along the gap between the lower end surface 26 of the upper sub-ring 10 and the upper end surface 27 of the lower sub-ring 9, and then along the gap between the outer circle of the upper sub-ring 10 and the inner cavity 8 of the valve body 1, thereby pressing the upper sealing ring 11 inwardly, forcing the inner circular surface 24 of the upper sealing ring 11 to be further close to the outer circle 5 of the valve disc 4, forming a pressure self-seal of the upper sealing ring 11 to the valve disc 4. The stress condition of the upper sealing ring when pre-tightened is as shown in Figure 3 As shown, N1 and N1' represent the extrusion forces in different directions, and N2 represents the sealing preload force;

[0026] Similarly, the shapes of the lower end surface 28 of the lower sub-ring 9 and the upper end surface 31 of the valve body 1 are conical surfaces, inclined surfaces or spherical surfaces that press the lower sealing ring 7 inwardly of the valve body 1. By tightening the clamping piece 17, the lower sub-ring 9 and the valve body 1 jointly press the lower sealing ring 7 inwardly, and the inner circular surface 30 of the lower sealing ring 7 obtains a greater sealing pre-tightening force than its outer circular surface 29, so that the medium can penetrate into the outer circular surface 29 of the lower sealing ring 7 with smaller pre-tightening force along the gap between the lower end surface 26 of the upper sub-ring 10 and the upper end surface 27 of the lower sub-ring 9, and then along the gap between the outer circle of the lower sub-ring 9 and the inner cavity 8 of the valve body 1, forming an extrusion inwardly of the lower sealing ring 7, forcing the inner circular surface 30 of the lower sealing ring 7 to be further close to the outer circle 5 of the valve disc 4, thereby forming a pressure self-seal of the lower sealing ring 7 on the valve disc 4. The stress condition of the lower sealing ring when pre-tightened is as shown in Figure 4 As shown, N1 and N1' represent the extrusion forces in different directions, and N2 represents the sealing preload force;

[0027] There is a gap between the lower end face 26 of the upper sub-ring 10 and the upper end face 27 of the lower sub-ring 9, the purpose of which is to facilitate the upward extrusion of the medium along the lower end face 26 of the upper sub-ring 10, forcing the upper sealing ring 11 to further fit against the lower end face 22 of the upper gasket 15, thereby forming a pressure self-seal of the upper sealing ring 11 against the lower end face 22 of the upper gasket 15; the medium is squeezed downward along the upper end face 27 of the lower sub-ring 9, forcing the lower sealing ring 7 to further fit against the upper end face 31 of the valve body 1, thereby forming a pressure self-seal of the lower sealing ring 7 against the upper end face 31 of the valve body 1.

[0028] After the cut-off valve of the present invention is connected to the pressure pipeline, when the valve is in the closed state, if the medium enters from the lower channel 33, it will enter the upper cavity 16 of the valve body through the balance hole 21, so that the upper end face 20 and the lower end face 34 of the valve disc are subjected to a pair of opposite and mutually offsetting forces along the axial direction of the valve disc 4, so as to achieve the self-balance of the axial pressure of the medium along the valve disc 4; if the medium enters from the upper channel 3, the medium pressure acts on the outer circumferential surface 5 of the valve disc to form mutually offsetting radial forces, so as to achieve the self-balance of the radial pressure of the medium along the outer circumferential surface 5 of the valve disc. When the present invention is in the open state, under the pull of the valve stem 19, the valve disc 4 is lifted and the medium flows out through the valve body outlet along the inner channel 35 of the valve body until the valve is fully opened.

[0029] The valve stem 19 pushes the valve disc to move downward along the inner surface of the valve body, so that the second sealing surface on the lower end surface 34 of the valve disc is tightly attached to the sealing surface on the upper end surface of the channel 35 in the valve body to achieve sealing. At this time, the valve is in the closed state. When the pressure medium enters from the channel 3 on the valve body, the medium pressure self-sealing principle is as follows Figure 5 As shown: N3 and N3' represent the medium adhesion force in different directions, and N4 represents the medium pressure; the pressure medium flows upward through the gap between the outer circle 5 of the valve disc and the inner circle 6 of the valve body. Due to the preload force on the lower sealing ring 7, the pressure medium will squeeze through the inner circle surface 30 of the lower sealing ring 7, and then flow into the outer circle surface 23 of the upper sealing ring 11 with smaller preload force along the gap between the outer circle 5 of the valve disc and the inner circle of the lower sub-ring 9, the gap between the upper end face 27 of the lower sub-ring 9 and the lower end face 26 of the upper sub-ring 10, and the gap between the outer circle of the upper sub-ring 10 and the inner cavity 8 of the valve body. 3 blocks the medium passage between the upper gasket 15 and the valve body 1, and the medium flowing into the lower end surface 26 of the upper sub-ring 10 presses the upper sealing ring 11 along the lower end surface 26 of the upper sub-ring 10, forming a pressure self-sealing of the upper sealing ring 11 against the lower end surface 22 of the upper gasket 15, and blocks the medium passage between the upper sealing ring 11 and the upper gasket 15, so that the medium flowing into the outer circumferential surface 23 of the upper sealing ring 11 is pressed toward the inner direction of the upper sealing ring 11, forcing the inner circumferential surface 24 of the upper sealing ring 11 to be further close to the outer circumference 5 of the valve disc 4, forming a pressure self-sealing of the upper sealing ring 11 against the valve disc 4.

[0030] When the pressure medium enters from the lower channel 33 of the valve body, the medium pressure self-sealing principle is as follows Figure 6As shown: N3 and N3' represent the medium adhesion force in different directions, N4 represents the medium pressure, the pressure medium is transmitted to the upper cavity 16 of the valve body through the balance hole 21 set on the valve disc 4 or the valve stem 19, and the pressure medium flows downward through the gap between the inner circle of the upper gasket 15 and the outer circle 5 of the valve disc. Due to the preload force on the upper sealing ring 11, the pressure medium will squeeze through the inner circle surface 24 of the upper sealing ring 11, and then flow along the gap between the outer circle 5 of the valve disc and the inner circle of the upper sub-ring 10, the gap between the lower end face 26 of the upper sub-ring 10 and the upper end face 27 of the lower sub-ring 9, and the gap between the outer circle of the lower sub-ring 9 and the valve The gap between the inner cavities 8 of the valve body flows into the outer circumferential surface 29 of the lower sealing ring 7 with smaller preload force. Due to the medium flowing into the upper end surface 27 of the lower sub-ring 9, it is squeezed downward along the upper end surface 27 of the lower sub-ring 9, forming a pressure self-seal of the lower sealing ring 7 against the upper end surface 31 of the valve body 1, blocking the medium channel between the lower sealing ring 7 and the upper end surface 31 of the valve body 1, so that the medium flowing into the outer circumferential surface 29 of the lower sealing ring 7 is squeezed inwardly of the lower sealing ring 7, forcing the inner circumferential surface 30 of the lower sealing ring 7 to be further fitted with the outer circumference 5 of the valve disc 4, forming a pressure self-seal of the lower sealing ring 7 against the valve disc 4.

[0031] In summary, since the pressing force of the squeeze seal ring is a self-sealing force formed by the medium pressure itself, it will become more reliable as the medium pressure increases. Its sealing effect is not only independent of the medium pressure, but also independent of the size of the sealing preload force of the inner circular surface 24 of the upper seal ring 11 or the inner circular surface 30 of the lower seal ring 7 on the outer circular surface 5 of the valve disc 4. Therefore, the seal ring can be made of loose but high-temperature resistant elastic material to achieve self-sealing of the medium pressure. At the same time, although the wear of the outer circular surface 5 of the valve disc 4 on the inner circular surface 24 of the upper seal ring 11 or the inner circular surface 30 of the lower seal ring 7 will cause the decrease of the sealing preload force of the present invention, it will not cause the decrease of the sealing effect of the present invention. The present invention does not only achieve sealing by squeezing between parts and seals, but by tightening the pressing member 17, so that the seal can obtain sufficient material density, and form a sealing preload force far less than the medium pressure on the inner circular surface 24 of the upper seal ring 11 and the inner circular surface 30 of the lower seal ring 7 and the outer circular surface 5 of the valve disc 4, so as to obtain a lasting and reliable sealing quality and sealing life.

[0032] The results of testing the cut-off valve of the present invention under the conditions of a valve diameter of 250 mm, a sealing test pressure ≥ 42 MPa, and a duration ≥ 60 s show that the present invention achieves zero leakage, and the operating torque required for the valve is less than 450 N·m, which is only 1 / 20 of that of the traditional technology valve. Therefore, the present invention has excellent sealing performance and a small operating torque, and is suitable for large-diameter pipelines.

[0033] The above is only a preferred embodiment of the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made. For example, the upper gasket can be a part or a combination of multiple parts, the upper gasket and the clamping part and the valve cover can be made into one part, etc. The number and combination of seals can also be varied. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bidirectional high-temperature and high-pressure self-balancing cut-off valve, comprising a valve body (1), a valve cover (18), a valve stem (19) and a valve disc (4); the valve body is provided with a valve body upper channel (3), a valve body lower channel (33) and a valve body inner channel (35) connecting the valve body upper channel (3) and the valve body lower channel (33); a composite sealing ring and a blocking ring (13) are provided between the valve body (1) and the valve disc (4); the characteristics are as follows: The composite sealing ring comprises an upper gasket (15), an upper sealing ring (11), an upper split ring (10), a lower split ring (9) and a lower sealing ring (7) which are sequentially sleeved outside the valve disc from the valve cover (18) toward the valve body (1); the blocking ring (13) is sleeved outside the upper gasket (15); and a pressing member (17) is arranged between the upper gasket (15) and the valve cover (18); an annular sealing ring accommodating groove and a blocking ring accommodating groove are formed on the inner surface of the valve body (1); the upper gasket (15), the upper sealing ring (11), the upper split ring (10), the lower split ring (9) and the lower sealing ring (7) are arranged in the sealing ring accommodating groove from top to bottom; and the blocking ring (13) is located in the blocking ring accommodating groove; The valve disc (4) or the valve stem (19) is provided with a balancing hole (21) communicating with the inner cavity (36) of the valve disc and the upper cavity (16) of the valve body.

2. The bidirectional high-temperature and high-pressure self-balancing cut-off valve according to claim 1 is characterized in that: The side end surface (14) of the upper gasket (15) is a conical surface, inclined surface, plane or spherical surface that presses the blocking ring (13) in the direction of the valve body (1); the lower end surface (22) of the upper gasket (15) and the upper end surface (25) of the upper split ring (10) are shaped as a conical surface, inclined surface or spherical surface that presses the upper sealing ring (11) in the direction of the valve body (1); the lower end surface (28) of the lower split ring (9) and the upper end surface (31) of the valve body (1) are shaped as a conical surface, inclined surface or spherical surface that presses the lower sealing ring (7) in the direction of the valve body.

3. The bidirectional high-temperature and high-pressure self-balancing cut-off valve according to claim 1 is characterized in that: The outer surface of the valve flap (4) and the inner surface of the valve body are clearance-matched with the upper gasket (15), the upper sub-ring (10), and the lower sub-ring (9).

4. The bidirectional high-temperature and high-pressure self-balancing cut-off valve according to claim 1 is characterized in that: There is a gap between the lower end surface (26) of the upper sub-ring (10) and the upper end surface (27) of the lower sub-ring (9).

5. The bidirectional high-temperature and high-pressure self-balancing cut-off valve according to claim 1 is characterized in that: The lower end surface of the valve flap (4) and the valve body inner passage (35) have matching sealing surfaces, and the sealing surfaces are plane, conical or spherical.

6. The bidirectional high-temperature and high-pressure self-balancing cut-off valve according to claim 1 is characterized in that: The pressing piece (17) is threadedly connected to the valve body (1).

7. The bidirectional high-temperature and high-pressure self-balancing cut-off valve according to claim 1 is characterized in that: The blocking ring (13), the upper sealing ring (11) and the lower sealing ring (7) are made of flexible graphite or polytetrafluoroethylene material.

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