A full-bore bidirectional sealing butterfly valve and a method for determining the outer diameter of its floating valve seat

Abstract

The present invention discloses a full-bore, two-way sealed butterfly valve and a method for determining the outer diameter of a floating valve seat thereof, comprising a valve body, a valve stem and a butterfly plate, the valve stem being inserted into the valve body along the radial direction of the valve body, the valve stem and the valve body being rotatably and sealingly connected, the butterfly plate being arranged in the valve body, a shaft sleeve being arranged on one side of the butterfly plate, the valve stem passing through the shaft sleeve and being fixedly connected to the butterfly plate, a floating valve seat being arranged on the outer edge of the butterfly plate, an annular groove being arranged in the valve body, the floating valve seat being slidably arranged in the annular groove, the sealing surface of the floating valve seat and the sealing surface of the butterfly plate being both inclined surfaces and cooperating to form a sealing pair, in the present invention, the inner diameter of the floating valve seat is controlled to be slightly smaller than the nominal diameter of the valve body, and at the same time, the outer wall of the valve body is protruded outwardly, a groove is formed inside, and the floating valve seat is placed in the groove, thereby greatly reducing the size of the valve body channel occupied by the floating valve seat, greatly reducing the fluid resistance, and greatly reducing the energy consumption.

Description

Technical Field

[0001] The invention relates to the field of valve technology, and in particular to a full-diameter bidirectional sealing butterfly valve and a method for determining the outer diameter of a floating valve seat thereof. Background Art

[0002] The existing two-way sealing butterfly valve relies on the two-way movement of the floating valve seat to achieve its two-way sealing function. In order to ensure sufficient sealing pressure during reverse sealing, the floating valve seat must have sufficient radial height. Therefore, the floating valve seat will occupy a certain valve channel space size. As a result, the actual channel size of the valve is much smaller than the nominal channel size of the valve, and the fluid resistance will increase significantly, which is not conducive to energy saving and consumption reduction. Summary of the invention

[0003] The object of the present invention is to provide a full-diameter bidirectional sealing butterfly valve and a method for determining the outer diameter of its floating valve seat in view of the above-mentioned deficiencies in the prior art.

[0004] To solve the above problems, the technical solution adopted by the present invention is:

[0005] A full-bore, two-way sealed butterfly valve comprises a valve body, a valve stem and a butterfly plate, wherein the valve stem is inserted into the valve body radially along the valve body, the valve stem and the valve body are rotatable and sealed, the butterfly plate is arranged in the valve body, a shaft sleeve is arranged on one side of the butterfly plate, the valve stem passes through the shaft sleeve and is fixedly connected to the butterfly plate, a floating valve seat is arranged on the outer edge of the butterfly plate, an annular groove is arranged in the valve body, the floating valve seat is slidably arranged in the annular groove, and the sealing surface of the floating valve seat and the sealing surface of the butterfly plate are both inclined surfaces and cooperate to form a sealing pair.

[0006] Furthermore, the valve body includes a left valve body, a right valve body and a bottom cover, which together form a valve cavity. The left valve body and the right valve body are connected by bolts, and the bottom cover is located at the bottom of the right valve body and is connected by bolts. The right valve body is provided with a valve stem hole for inserting the valve stem, and the bottom of the valve stem abuts against the bottom cover.

[0007] Furthermore, the annular groove is located on the right valve body.

[0008] Furthermore, a rubber sealing ring is provided between the floating valve seat and the valve body.

[0009] Furthermore, the mid-surface diameter of the butterfly plate is 8-10 mm smaller than the nominal diameter of the valve body.

[0010] A method for determining the outer diameter of a floating valve seat of a full-bore bidirectional sealing butterfly valve comprises the following steps:

[0011] 1) Thrust F of the medium on the floating valve seat during reverse sealing

[0012]

[0013] Where: F—thrust of the medium on the floating valve seat plane during reverse sealing, unit: N,

[0014] D—Outer diameter of floating valve seat, unit: m,

[0015] d—Minimum inner diameter of floating valve seat, unit: m,

[0016] P—medium pressure, unit: Pa;

[0017] 2) Sealing pair positive pressure Fn = F / sinθ

[0018] Where: θ—seal pair inclination angle, unit: degree;

[0019] 3) Sealing force area S

[0020] S=πRB+πrB=πB(R+r)=πφB

[0021] Where: R—the maximum radius of the sealing pair, unit: m,

[0022] r—Minimum radius of the sealing pair, unit: m,

[0023] φ—diameter of the middle surface of the butterfly plate, unit: m,

[0024] B—seal pair width, unit: m;

[0025] 4) Sealing pressure Σ

[0026]

[0027] From the above formula, we can get:

[0028]

[0029] Where: Σ—seal specific pressure, unit: Pa.

[0030] Furthermore, a method for calculating the sealing pair inclination angle θ is also included:

[0031]

[0032] Where: e—eccentricity, the distance between the center line of the sealing sub and the center line of the valve stem, unit: m,

[0033] φ—mid-surface diameter of butterfly disc, unit: m.

[0034] Furthermore, the calculation method of the eccentricity e is also included:

[0035] e=A+K+T

[0036] Where: A—the radius of the valve stem, unit: m,

[0037] K—the gap between the valve stem and the butterfly plate, unit: m,

[0038] T—half the thickness of the butterfly plate 5, unit: m.

[0039] Furthermore, the sealing specific pressure Σ should satisfy the following conditions: Σx>Σ>Σb;

[0040] Where: Σx—permissible sealing specific pressure of the material,

[0041] Σb—Required sealing specific pressure of the material.

[0042] The beneficial effects of adopting the above technical solution are:

[0043] In the present invention, the inner diameter of the floating valve seat is controlled to be slightly smaller than the nominal diameter of the valve body. At the same time, the outer wall of the valve body is protruded outward, a groove is formed inside, and the floating valve seat is placed in the groove. This greatly reduces the size of the valve body channel occupied by the floating valve seat, greatly reduces fluid resistance, and greatly reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the structure of the present invention;

[0045] Figure 2 yes Figure 1 A magnified view of part A;

[0046] In the figure: 1. left valve body; 2. right valve body; 3. bottom cover; 4. valve stem; 5. butterfly plate; 6. shaft sleeve; 7. floating valve seat; 8. annular groove; 9. rubber sealing ring. DETAILED DESCRIPTION

[0047] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0048] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0049] like Figure 1-2As shown, it is a specific embodiment of a full-bore bidirectional sealing butterfly valve of the present invention, including a valve body, a valve stem 4 and a butterfly plate 5. The valve body includes a left valve body 1, a right valve body 2 and a bottom cover 3. The left valve body 1, the right valve body 2 and the bottom cover 3 are enclosed to form a valve cavity. The left valve body 1 and the right valve body 2 are connected by bolts. The bottom cover 3 is located at the bottom of the right valve body 2 and is connected by bolts. The right valve body 2 is provided with a valve stem hole for inserting the valve stem 4. The valve stem 4 is inserted into the right valve body 2 along the radial direction of the valve body. The upper part of the valve stem 4 is rotatably and hermetically connected to the right valve body 2. The upper end of the valve stem 4 can be connected to a driving device, such as a turbine box, an electric Device and pneumatic device, through the driving device to drive the valve stem 4 and the butterfly valve 5 to rotate, to achieve the opening and closing of the valve, the bottom of the valve stem 4 is in contact with the bottom cover 3, the butterfly plate 5 is arranged in the valve body, a shaft sleeve 6 is arranged on one side of the butterfly plate 5, the valve stem 4 passes through the shaft sleeve 6 and is fixedly connected to the butterfly plate 5, a floating valve seat 7 is arranged on the outer edge of the butterfly plate 5, the floating valve seat 7 is a circular ring body, an annular groove 8 is arranged on the side of the right valve body 2 connected to the left valve body 1, the floating valve seat 7 can be slid left and right in the annular groove 8, the sealing surface of the floating valve seat 7 and the sealing surface of the butterfly plate 5 are both inclined surfaces and cooperate to form a sealing pair.

[0050] Furthermore, when the materials of the left valve body 1 and the right valve body 2 are weldable materials, the left valve body 1 and the right valve body 2 can be welded into a whole.

[0051] Furthermore, a rubber sealing ring 9 is provided between the floating valve seat 7 and the valve body. A groove is provided on the outer ring surface of the floating valve seat 7, and the rubber sealing ring 9 is embedded in the groove to isolate the medium at both ends of the floating valve seat 7.

[0052] Furthermore, the mid-surface diameter of the butterfly plate 5 is 8-10 mm smaller than the nominal diameter of the valve body to prevent the butterfly plate 5 from interfering with the inner cavity of the right valve body 2 when rotating, thereby maximally retaining the valve channel size, reducing fluid resistance, and reducing energy consumption.

[0053] When the medium is under positive pressure, the medium thrust and the preload force generated by the eccentric valve stem are superimposed in the same direction. The higher the medium pressure P, the greater the thrust, the greater the sealing specific pressure Σ of the sealing pair, and the better the sealing effect.

[0054] When the medium is under reverse pressure, the medium thrust and preload force decrease in the opposite direction; when the sealing specific pressure Σ is less than the required sealing specific pressure Σb, the sealing pair will leak.

[0055] At the same time, the medium thrust pushes the floating valve seat 7 to move to the left, pressing the sealing pair. The greater the medium pressure P, the greater the force-bearing area of ​​the floating valve seat 7, and the greater the thrust on the floating valve seat 7. When the sealing specific pressure Σ is greater than the required sealing specific pressure Σb, sealing can be achieved.

[0056] The medium pressure in different working conditions may be different, but all of them are less than the nominal pressure PN; since the higher the medium pressure P value, the greater the medium thrust and the better the sealing effect. Therefore, as long as the medium pressure P is relatively small, the valve does not leak and the entire valve can achieve reliable sealing. In general, when the P value is 10% of the PN value, it can meet the use requirements of more than 99% of the working conditions. In special cases, the P value can be determined according to the actual working conditions.

[0057] When the P value is determined, the value of the outer diameter D of the floating valve seat 7 is very critical: if the D value is too small, the sealing pressure Σ of the sealing pair may be less than the required sealing pressure Σb, and the valve may not be able to seal. If the D value is too large, the sealing pressure Σ may be greater than the allowable sealing pressure Σx of the material, causing damage to the sealing surface material and ultimately leading to valve seal failure. At the same time, if the D value is too large, it will also cause the valve body flange to be bulky and waste materials.

[0058] Therefore, in order to solve the above problems, the present invention also provides a method for determining the outer diameter of a floating valve seat of a full-diameter bidirectional sealing butterfly valve, comprising the following steps:

[0059] 1) Thrust F of the medium on the floating valve seat during reverse sealing

[0060]

[0061] Where: F—thrust of the medium on the floating valve seat plane during reverse sealing, unit: N,

[0062] D—Outer diameter of floating valve seat, unit: m,

[0063] d—Minimum inner diameter of floating valve seat, unit: m. The inner diameter d of floating valve seat is slightly smaller than the nominal DN of valve, usually d=DN-0.02

[0064] P—medium pressure, unit: Pa;

[0065] 2) Sealing pair positive pressure Fn = F / sinθ

[0066] Where: θ—seal pair inclination angle, unit: degree;

[0067] 3) Sealing force area S

[0068] S=πRB+πrB=πB(R+r)=πφB

[0069] Where: R—the maximum radius of the sealing pair, unit: m,

[0070] r—Minimum radius of the sealing pair, unit: m,

[0071] φ—diameter of the middle surface of the butterfly plate, unit: m,

[0072] B—seal pair width, unit: m;

[0073] 4) Sealing pressure Σ

[0074]

[0075] From the above formula, we can get:

[0076] Floating valve seat outer diameter

[0077] Where: Σ—seal specific pressure, unit: Pa.

[0078] Furthermore, a method for calculating the sealing pair inclination angle θ is also included:

[0079]

[0080] Where: e—eccentricity, the distance between the center line of the sealing sub and the center line of the valve stem, unit: m,

[0081] φ—mid-surface diameter of the butterfly disc, unit: m, usually taken as φ=DN-0.01.

[0082] Furthermore, the calculation method of the eccentricity e is also included:

[0083] e=A+K+T

[0084] Where: A is the radius of the valve stem, unit: m, its value is determined by the valve stem strength calculation, which can be found in the "Valve Design Manual";

[0085] K—the gap between the valve stem and the butterfly plate, unit: m, to prevent the butterfly plate and the valve stem from colliding during assembly. When the valve nominal size DN≤0.5m, the K value is 0.01m; when DN>0.5m, the K value is 0.02m;

[0086] T is half of the thickness of the butterfly plate 5, in m. Its value is determined by the butterfly plate strength calculation and can be found in the Valve Design Manual.

[0087] Furthermore, the sealing specific pressure Σ should satisfy the following conditions: Σx>Σ>Σb;

[0088] Where: Σx—permissible sealing specific pressure of the material, which can be found in the Valve Design Manual.

[0089] Σb—Required sealing specific pressure of the material, which can be found in the "Valve Design Manual".

[0090] Furthermore, when the floating valve seat 7 and the rubber sealing ring 9 move to the left, friction will be generated with the valve body, which is opposite to the thrust of the medium, but its value is very small, usually only 0.1-0.3% of the thrust of the medium, and therefore can be ignored.

[0091] Embodiment: Select the butterfly valve with nominal pressure PN=1.0MPa, nominal size DN=1000mm, sealing surface material 304 stainless steel, and calculate and determine the diameter D value of the floating valve seat.

[0092] Determine the minimum medium pressure: P = 10% PN = 10% × 1.0 = 0.1 (MPa) = 1 × 10 5 Pa;

[0093] Determine the minimum inner diameter of the floating valve seat: d = DN-20 = 1000-20 = 980 (mm) = 0.98m;

[0094] Determine the mid-surface diameter of the butterfly plate: φ = DN-10 = 1000-10 = 990 (mm) = 0.99m;

[0095] According to the structural design requirements, and taking into account the valve nominal size DN, nominal pressure PN and sealing surface material strength and other factors, the sealing pair width B = 5mm = 0.005m is tried;

[0096] Calculate the eccentricity e

[0097] e=A+K+T=0.065+0.02+0.020=0.1025(m);

[0098] Where: A = 0.0625m, calculated according to the valve stem radius calculation method provided in the Valve Design Manual and rounded off;

[0099] K = 0.02m, calculated according to the disc thickness calculation method provided in the Valve Design Manual and rounded off;

[0100] T = 0.02m, based on experience;

[0101] 1) Determine the sealing cone angle θ

[0102]

[0103] For the convenience of calculation and processing, the calculated value of θ is rounded to θ=12°.

[0104] Calculate the thrust F of the medium on the floating valve seat during reverse sealing

[0105]

[0106] =(78500D 2 -75391.4)N·m;

[0107] Calculate the positive pressure Fn of the sealing pair

[0108] Therefore: Fn = F / sinθ = (78500D 2-75391.4) / sin12°

[0109] =(377564D 2 -362612)N·m;

[0110] Calculate the sealing force area S

[0111] S=π×B×φ=3.14×0.005×0.99=0.0155(m 2 );

[0112] Calculate the seal specific pressure Σ (pressure per unit area)

[0113] Σ=Fn / S=(377564D 2 -362612) / 0.0155=(24.2D 2 -23.4)×10 6 (Pa)

[0114] =(24.2D 2 -23.4)MPa;

[0115] In order to ensure a good sealing effect and prevent the sealing surface from being damaged due to excessive pressure, Σ should meet the following conditions: Σx>Σ>Σb;

[0116] Among them: Σx—the allowable sealing specific pressure of 304 material, which can be obtained by checking the Valve Design Manual; Σx=40MPa;

[0117] Σb—Required sealing specific pressure of 304 material, according to the Valve Design Manual; Σb=4.5MPa;

[0118] By (24.2D 2 -23.4)≤40, we can get: D≤1.619m

[0119] By (24.2D 2 -23.4)≥4.5, we can get: Then D≥1.074m

[0120] Determine the outer diameter D value of the floating valve seat based on actual working conditions, material properties and structural design requirements.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the outer diameter of a floating valve seat of a full-bore bidirectional sealing butterfly valve, characterized in that: The valve body comprises a valve stem (4) and a butterfly plate (5), wherein the valve stem (4) is inserted into the valve body along the radial direction of the valve body, the valve stem (4) and the valve body are rotatably and sealedly connected, the butterfly plate (5) is arranged in the valve body, a shaft sleeve (6) is arranged on one side of the butterfly plate (5), the valve stem (4) passes through the shaft sleeve (6) and is fixedly connected to the butterfly plate (5), a floating valve seat (7) is arranged on the outer edge of the butterfly plate (5), an annular groove (8) is arranged in the valve body, the floating valve seat (7) is slidably arranged in the annular groove (8), the sealing surface of the floating valve seat (7) and the sealing surface of the butterfly plate (5) are both inclined surfaces and cooperate to form a sealing pair; The method for determining the outer diameter of the floating valve seat comprises the following steps: 1) Thrust F of the medium on the floating valve seat during reverse sealing Where: F—thrust of the medium on the floating valve seat plane during reverse sealing, unit: N, D—Outer diameter of floating valve seat, unit: m, d—Minimum inner diameter of floating valve seat, unit: m, P—medium pressure, unit: Pa; 2) Sealing pair positive pressure Fn = F / sinθ Where: θ—seal pair inclination angle, unit: degree; 3) Sealing force area S S=πRB+πrB=πB(R+r)=πφB Where: R—the maximum radius of the sealing pair, unit: m, r—Minimum radius of the sealing pair, unit: m, φ—diameter of the middle surface of the butterfly plate, unit: m, B—seal pair width, unit: m; 4) Sealing pressure Σ From the above formula, we can get: Floating valve seat outer diameter Where: Σ—seal specific pressure, unit: Pa.

2. The method for determining the outer diameter of the floating valve seat of a full-bore bidirectional sealing butterfly valve according to claim 1, characterized in that: It also includes the calculation method of the sealing pair inclination angle θ: Where: e—eccentricity, the distance between the center line of the sealing sub and the center line of the valve stem, unit: m, φ—mid-surface diameter of butterfly disc, unit: m.

3. The method for determining the outer diameter of the floating valve seat of a full-bore bidirectional sealing butterfly valve according to claim 2, characterized in that: It also includes the calculation method of eccentricity e: e=A+K+T Where: A—the radius of the valve stem, unit: m, K—the gap between the valve stem and the butterfly plate, unit: m, T—half of the thickness of the disc, in m.

4. The method for determining the outer diameter of the floating valve seat of a full-bore bidirectional sealing butterfly valve according to claim 1, characterized in that: The sealing specific pressure Σ should satisfy the following conditions: Σx>Σ>Σb; Where: Σx—permissible sealing specific pressure of the material, Σb—Required sealing specific pressure of the material.

5. A full-diameter bidirectional sealing butterfly valve, based on the determination method according to any one of claims 1 to 4, characterized in that: The valve body comprises a left valve body (1), a right valve body (2) and a bottom cover (3); the left valve body (1), the right valve body (2) and the bottom cover (3) together form a valve cavity; the left valve body (1) and the right valve body (2) are connected by bolts; the bottom cover (3) is located at the bottom of the right valve body (2) and is connected by bolts; the right valve body (2) is provided with a valve stem hole for inserting the valve stem (4); the bottom of the valve stem (4) abuts against the bottom cover (3).

6. A full-bore bidirectional sealing butterfly valve according to claim 5, characterized in that: The annular groove (8) is located on the right valve body (2).

7. A full-bore bidirectional sealing butterfly valve according to claim 5, characterized in that: A rubber sealing ring (9) is provided between the floating valve seat (7) and the valve body.

8. A full-bore bidirectional sealing butterfly valve according to claim 5, characterized in that: The mid-surface diameter of the butterfly plate (5) is 8-10 mm smaller than the nominal diameter of the valve body.

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