Anti-erosion cage type single-seat valve and optimization design method thereof

Abstract

The invention relates to an anti-erosion cage type single-seat valve and an optimization design method thereof, the anti-erosion cage type single-seat valve comprises a valve body, an upper valve cover, a valve core and a valve rod, and further comprises an inner sleeve, an outer sleeve and a cage sleeve type valve seat; a cage sleeve type valve seat is arranged at the communication part of the inlet runner and the outlet runner in the valve body, and a plurality of throttling holes I are formed in the lower part of the cage sleeve type valve seat; a main runner is formed between the cage sleeve type valve seat and the valve core; an inner sleeve is arranged on the periphery of the valve element and provided with a plurality of second throttling holes. An outer sleeve is arranged on the outer side of the inner sleeve and provided with a plurality of third throttling holes. And the inner sleeve, the outer sleeve and the cage sleeve type valve seat are pressed and fixed in the valve body through the upper valve cover. According to the cage type single-seat valve, under the condition that the flow characteristic is not affected, the number and the hole diameter of the throttling holes in the outer sleeve and the cage type valve seat are optimized, and the number and the diameter of the protruding structures on the outer side of the valve element are optimized, so that the erosion resistance of the cage type single-seat valve is effectively improved.

Description

Technical Field

[0001] The invention relates to a cage type single seat valve, in particular to an anti-erosion cage type single seat valve and an optimization design method thereof. Background Art

[0002] Single-seat valve is also called single-seat regulating valve. Its characteristic is that there is only one valve core and one valve seat in the valve body. The opening or closing action can be realized by changing the position relationship between the valve core and the valve seat. Single-seat valve has the advantage of small leakage, but its disadvantage is that the force of the medium on the valve core, that is, the unbalanced force, is large, and the allowable pressure difference is small. Therefore, single-seat valve is only suitable for clean media occasions with strict leakage requirements and small pressure difference. On the contrary, it is not suitable for unclean media and large pressure difference. Single-seat regulating valves are mainly divided into four types according to their structure: single-seat, sleeve, double-seat, and cage.

[0003] Single-seat valves are prone to erosion and wear under high pressure difference, high flow rate and two-phase flow field with solid particles, which can lead to valve trim failure. When the fluid moves at high speed, it will carry solid particles to impact the surface of the valve trim, causing obvious erosion and wear of the valve seat and valve core, resulting in failure of regulation and loss of working ability, affecting the safety and reliability of the working system. Compared with single-seat valves of other structures, the cage-type single-seat regulating valve adopts a multi-stage pressure reduction structure design, which can effectively slow down the fluid flow rate and inhibit erosion.

[0004] In nature, some organisms continuously evolve their structures to adapt to harsh environments, which expands the ideas for engineering design. When observing the bark of red willow, it was found that the irregular convex hull structure distributed on its surface has a significant effect on overcoming extreme erosion environments. By studying the bionic effect of this structure, a single-seat valve core surface structure was designed, which can improve the erosion resistance of the valve trim to solid-liquid two-phase flow and increase the service life of the valve.

[0005] Factors such as flow velocity, pressure drop, and streamline trajectory in the flow field of a single-seat valve affect the erosion resistance of the single-seat valve. Therefore, it is necessary to design a multi-stage pressure-reducing element and a bionic anti-erosion structure in the flow channel. Optimizing the number and aperture of the throttling holes on the throttling sleeve, as well as the number and diameter parameters of the bionic convex hull, can minimize the erosion phenomenon in the valve without affecting the flow characteristics, which is of great significance to ensuring the safe and stable operation of industrial production equipment. Summary of the invention

[0006] The present invention provides an erosion-resistant cage-type single-seat valve and an optimization design method thereof. An inner sleeve, an outer sleeve, a valve core and a cage-type valve seat are arranged in the valve body of the single-seat valve. Without affecting the flow characteristics, the erosion resistance of the cage-type single-seat valve is effectively improved by optimizing the number and aperture of throttling holes on the outer sleeve and the cage-type valve seat, as well as optimizing the number and diameter of protruding structures on the outer side of the valve core.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A kind of erosion-resistant cage-type single-seat valve, comprising a valve body, an upper valve cover, a valve core and a valve stem; it also comprises an inner sleeve, an outer sleeve and a cage-type valve seat; the valve core and the valve stem are an integrated structure; a fluid inlet is arranged on one side of the valve body to form an inlet flow channel, and a fluid outlet is arranged on the other side to form an outlet flow channel, the top of the inlet flow channel and the bottom of the outlet flow channel are connected in the middle of the valve body, and a cage-type valve seat is arranged at the connecting position; the lower part of the cage-type valve seat is located in the inlet flow channel and a plurality of throttling holes are arranged along the circumferential direction; an opening is arranged on the top of the cage-type valve seat to cooperate with the lower end of the valve core to form a main flow channel; an inner sleeve is arranged above the cage-type valve seat and on the periphery of the valve core, and a plurality of throttling holes are arranged along the circumferential direction at the lower part of the inner sleeve at the height corresponding to the outlet flow channel; an outer sleeve is arranged on the outer side of the lower part of the inner sleeve, and a plurality of throttling holes are arranged along the circumferential direction on the outer sleeve; the outer sleeve is located between the inner sleeve and the cage-type valve seat; the inner sleeve, the outer sleeve and the cage-type valve seat are pressed and fixed in the valve body by the upper valve cover.

[0009] The matching section between the lower part of the valve core and the cage-type valve seat is a multi-stage variable diameter structure, and the diameter of the multi-stage variable diameter structure gradually decreases from top to bottom; specifically, the multi-stage variable diameter structure is composed of a large-taper cone, a small-taper cone and a hemisphere in sequence, and the connections between the three are smoothly transitioned; a plurality of protrusion structures are evenly arranged along the circumferential direction on the outer sides of the large-taper cone and the hemisphere.

[0010] Gaskets are arranged at the contact surfaces of the outer sleeve, the inner sleeve and the cage-type valve seat.

[0011] The throttling hole 1 is a stepped hole, and the hole diameter close to the outer side is larger than the hole diameter close to the inner side.

[0012] The throttle hole three and the throttle hole two are arranged alternately.

[0013] The protrusion structure is a hemispherical protrusion.

[0014] An optimization design method for an erosion-resistant cage-type single-seat valve comprises the following steps:

[0015] 1) Formulate an optimization strategy on the premise of satisfying the flow characteristics of the single-seat valve: take the erosion rate of the valve trim as the optimization target, that is, minimize the erosion rate of the valve trim; take the number and diameter of throttle holes 1 and throttle holes 3, and the number and diameter of the protrusion structure on the valve core as design parameter variables;

[0016] 2) Sensitivity analysis of design parameter variables on optimization objectives, that is, analyzing the influence of each design parameter variable on the optimization objective: by adjusting the value range of each parameter, it is determined that each parameter has a significant influence on the optimization objective;

[0017] 3) Use finite element simulation erosion rate test to provide data samples: Use Design-Expert software for experimental design and data analysis, and use the Box-Behnken response surface optimization method to establish a quadratic polynomial fitting model, i.e., a second-order design model;

[0018] 4) The second-order design model is used to accurately approximate the optimal value of the response surface within the set investigation range, and the items that have no significant impact on the response value are eliminated to obtain the optimal parameter matching solution.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) Drawing on the special structure of red willow bark, which has strong anti-erosion ability in nature, a bionic convex structure is designed on the outside of the valve core to significantly enhance its erosion inhibition effect;

[0021] 2) Add a cage-type valve seat with a porous cage structure at the bottom of the valve seat, and set a porous outer sleeve outside the inner sleeve to achieve multi-stage pressure reduction and speed regulation functions;

[0022] 3) The valve core is in an inner sleeve with a porous structure. As the valve core moves upward, more and more throttling holes are exposed on the inner sleeve. Corresponding to the various openings of the single-seat valve, the throttling area of ​​the inner sleeve can be minimized while meeting the flow characteristics, thereby achieving pressure reduction and speed regulation to the maximum extent.

[0023] 4) When optimizing the structure of the anti-erosion cage single-seat valve, the present invention uses Design-Expert software for experimental design and data analysis, and uses the Box-Behnken response surface optimization method, which has high optimization efficiency and can accurately approximate the optimal value of the response surface;

[0024] 5) Through the analysis of the erosion characteristics of the optimized anti-erosion cage single-seat valve, it can be proved that after the cage valve seat, porous outer sleeve and valve core with a convex structure are set, the erosion of the valve trim is significantly improved and the erosion rate is significantly reduced; when the optimized single-seat valve is fully opened, the erosion rate is reduced from 8.0×10 -2 kg / (m 2 ·s) is reduced to 1.52×10 -2 kg / (m 2 ·s), good anti-erosion performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a front sectional view of an erosion-resistant cage-type single-seat valve according to the present invention.

[0026] Figure 2 It is a three-dimensional cross-sectional view of an erosion-resistant cage-type single-seat valve according to the present invention.

[0027] Figure 3 It is a schematic diagram of the local structure of the valve core of the present invention.

[0028] Figure 4 3 is a flow field velocity distribution diagram when the single seat valve is fully opened in an embodiment of the present invention.

[0029] Figure 5 3 is a flow field pressure distribution diagram when the single seat valve is fully opened in an embodiment of the present invention.

[0030] Figure 6 It is a Box-Behnken response surface optimization flow chart in an embodiment of the present invention.

[0031] Figure 7 This is a distribution diagram of the erosion rate when the single seat valve is fully opened before optimization in an embodiment of the present invention.

[0032] Figure 8 This is a distribution diagram of the erosion rate when the optimized single-seat valve is fully opened in an embodiment of the present invention.

[0033] In the figure: 1-upper valve cover; 2-valve stem; 3-valve body; 4-inner sleeve; 5-valve core; 51. protruding structure; 6-outer sleeve; 7-cage type valve seat. DETAILED DESCRIPTION

[0034] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0035] like Figure 1 , Figure 2 As shown, the erosion-resistant cage-type single-seat valve of the present invention comprises a valve body 3, an upper valve cover 1, a valve core 5 and a valve stem 2; it also comprises an inner sleeve 4, an outer sleeve 6 and a cage-type valve seat 7; the valve core 5 and the valve stem 2 are an integral structure; a fluid inlet is arranged on one side of the valve body 3 to form an inlet flow channel, and a fluid outlet is arranged on the other side to form an outlet flow channel, the top of the inlet flow channel and the bottom of the outlet flow channel are connected in the middle of the valve body 3, and a cage-type valve seat 7 is arranged at the connecting point; the lower part of the cage-type valve seat 7 is located in the inlet flow channel and is circumferentially arranged A plurality of throttling holes 1; an opening is provided at the top of the cage-type valve seat 7 to cooperate with the lower end of the valve core 5 to form a main flow channel; an inner sleeve 4 is provided above the cage-type valve seat 7 and on the periphery of the valve core 5, and a plurality of throttling holes 2 are circumferentially provided at the lower part of the inner sleeve 4 at a height corresponding to the outlet flow channel; an outer sleeve 6 is provided on the outer side of the lower part of the inner sleeve 4, and a plurality of throttling holes 3 are circumferentially provided at the outer sleeve 6; the outer sleeve 6 is located between the inner sleeve 4 and the cage-type valve seat 7; the inner sleeve 4, the outer sleeve 6 and the cage-type valve seat 5 are pressed and fixed in the valve body 3 by the upper valve cover 1.

[0036] The matching section between the lower part of the valve core 5 and the cage-type valve seat 7 is a multi-stage variable diameter structure, and the diameter of the multi-stage variable diameter structure gradually decreases from top to bottom; specifically, the multi-stage variable diameter structure is composed of a large-taper cone, a small-taper cone and a hemisphere in sequence, and the connections between the three are smoothly transitioned; a plurality of protrusion structures 51 are evenly arranged along the circumferential direction on the outer sides of the large-taper cone and the hemisphere.

[0037] Gaskets are provided at the contact surfaces of the outer sleeve 6 , the inner sleeve 4 and the cage-type valve seat 7 .

[0038] The throttling hole 1 is a stepped hole, and the hole diameter close to the outer side is larger than the hole diameter close to the inner side.

[0039] The throttle hole three and the throttle hole two are arranged alternately.

[0040] The protrusion structure 51 is a hemispherical protrusion.

[0041] An optimization design method for an erosion-resistant cage-type single-seat valve comprises the following steps:

[0042] 1) Formulate an optimization strategy on the premise of satisfying the flow characteristics of the single-seat valve: take the erosion rate of the valve trim as the optimization target, that is, minimize the erosion rate of the valve trim; take the number and diameter of throttle holes 1 and throttle holes 3, and the number and diameter of the protrusion structure on the valve core as design parameter variables;

[0043] 2) Sensitivity analysis of design parameter variables on optimization objectives, that is, analyzing the influence of each design parameter variable on the optimization objective: by adjusting the value range of each parameter, it is determined that each parameter has a significant influence on the optimization objective;

[0044] 3) Use finite element simulation erosion rate test to provide data samples: Use Design-Expert software for experimental design and data analysis, and use the Box-Behnken response surface optimization method to establish a quadratic polynomial fitting model, i.e., a second-order design model;

[0045] 4) The second-order design model is used to accurately approximate the optimal value of the response surface within the set investigation range, and the items that have no significant impact on the response value are eliminated to obtain the optimal parameter matching solution.

[0046] like Figure 1 , Figure 2As shown, a fluid inlet is arranged on the left side of the valve body 1 (in the direction shown in the figure), and a fluid outlet is arranged on the right side of the valve body 1, and a flow form of bottom inlet and side outlet is adopted. The cage-type valve seat 7 is arranged in the valve body 3, and the cage-type valve seat 7 is a traditional valve seat with a porous cage structure added to the lower part. When the valve stem 2 moves upward under the action of the actuator, the valve core 5 moves in the direction away from the opening on the cage-type valve seat 7 and forms different openings. The fluid passes through the throttling hole 1 on the cage-type valve seat 7, the gap (main flow channel) between the valve core 5 and the cage-type valve seat 7, the throttling hole 2 on the inner sleeve 4 and the throttling hole 3 on the outer sleeve 6 in sequence, and finally flows out from the fluid outlet of the valve body 1. After the fluid passes through the above-mentioned throttling element, a flow characteristic of step-by-step pressure reduction is formed to achieve speed regulation. The purpose of the present invention is to reduce the erosion of valve trim without affecting the flow characteristics of the single-seat valve.

[0047] The lower part of the valve core 5 adopts a multi-stage variable diameter structure, which consists of two sections of conical rotating bodies and a hemispherical body. As the valve core 5 moves upward, the cross-sectional diameter of the valve core 5 that matches the top opening of the cage-type valve seat 7 becomes smaller and smaller, and the flow area of ​​the main flow channel formed between the two becomes larger and larger. That is, the flow characteristics can be controlled by adjusting the cross-sectional diameter of each section of the multi-stage variable diameter structure on the valve core 5. At the same time, when the flow field velocity increases (such as Figure 4 As shown), the pressure will drop sharply (as shown Figure 5 shown).

[0048] The valve core 5 adopts a bionic design, drawing on the red willow bark with strong erosion resistance in nature, and a convex structure 51 (such as Figure 3 These protrusion structures 51 directly affect the streamline trajectory in the flow field, and can significantly reduce the erosion of the fluid medium on the valve trim.

[0049] The main body of the valve core 5 is a cylindrical structure, which is built into the inner sleeve 4. There are multiple throttling holes 2 distributed on the inner sleeve 4. As the valve core 5 moves upward, the number of throttling holes 2 on the inner sleeve 4 becomes more and more exposed, corresponding to the different openings of the single-seat valve. Under the premise of meeting the flow characteristics, the throttling area of ​​the inner sleeve 4 can be minimized to maximize the pressure reduction and speed regulation (such as Figure 4 , Figure 5 shown).

[0050] The cage-type valve seat 7 is a traditional valve seat with a porous cage structure added to the lower part, so as to achieve the functions of pressure reduction and speed regulation (such as Figure 4 , Figure 5 shown).

[0051] The outer sleeve 6 is arranged outside the inner sleeve 4 and fixed between the inner sleeve 4 and the cage valve seat 7. The outer sleeve 6 adopts a porous structure. When the fluid flows through the throttle hole 3 on the outer sleeve 6, pressure reduction and speed regulation can also be achieved (such as Figure 4 , Figure 5shown).

[0052] The following embodiments are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0053] [Example]

[0054] In this embodiment, the cross-sectional view of the erosion-resistant cage single-seat valve (single-seat valve for short) is as follows: Figure 1 , Figure 2 As shown, the engineering diameter of the single-seat valve is DN50, the valve core stroke is 25mm, and the flow capacity C v The linear flow characteristic has a value of 10. The inlet fluid pressure is 9.34MPa and the outlet fluid pressure is 0.5MPa.

[0055] In this embodiment, the erosion-resistant cage-type single-seat valve is composed of an upper valve cover 1, a valve stem 2, a valve core 5, a valve body 3, an inner sleeve 4, an outer sleeve 6 and a cage-type valve seat 7. The cage-type valve seat 7 is fixed in the valve body 3 under the pressure of the upper valve cover 1 and the inner sleeve 4 and the outer sleeve 6, and a gasket is arranged between the inner sleeve 4, the outer sleeve 6 and the cage-type valve seat 7 to prevent leakage and affect the flow characteristics.

[0056] The porous cage structure of the cage valve seat 7 sinks into the inlet flow channel at the bottom of the valve body 3, and a plurality of stepped holes, namely, throttling holes 1, are evenly distributed along the circumference thereof, through which one-stage pressure reduction and speed regulation are achieved.

[0057] The multi-stage variable diameter structure at the bottom of the valve core 5 contacts the side of the top opening of the cage-type valve seat 7, and the single-seat valve is in a fully closed state when the two fit tightly. When the valve stem 2 moves upward under the drive of the external actuator, an opening is formed between the multi-stage variable diameter structure at the bottom of the valve core 5 and the opening of the cage-type valve seat 7, and the main flow channel is opened. As the valve core 5 gradually moves upward, the cross-sectional diameter of the multi-stage variable diameter structure becomes smaller and smaller, and the flow area of ​​the main flow channel between the valve core 5 and the cage-type valve seat 7 becomes larger and larger. Therefore, the flow characteristics can be controlled by adjusting the size of the cross-sectional diameter of each section in the multi-stage variable diameter structure.

[0058] The inner sleeve 4 is placed between the upper valve cover 1 and the cage-type valve seat 7, and the valve core 5 is located inside the inner sleeve 4. As the valve core 5 moves upward, the throttle hole 2 at the bottom of the inner sleeve 4 is gradually exposed, and the flow area is getting larger and larger. The outer sleeve 6 is located outside the inner sleeve 4, and the two are concentrically arranged. The outer sleeve 6 is fixed between the inner sleeve 4 and the cage-type valve seat 7 along the axial direction, and the outer sleeve 6 adopts a porous structure.

[0059] The fluid first flows through the cage valve seat 7 to complete the first stage of pressure reduction and speed regulation. Then it flows upward from the gap between the valve core 5 and the cage valve seat 7. As the valve core 5 moves upward, the flow characteristics of the single seat valve can be controlled through the cross-sections of different diameters at different positions of the multi-stage variable diameter structure.

[0060] When the flow area is sharply reduced, the fluid flow rate will increase significantly and a certain pressure drop will occur. At this time, the multi-stage variable diameter structure at the bottom of the valve core 5 is severely eroded. The present invention draws on the special structure of the red willow bark with strong erosion resistance in nature, and designs a bionic convex structure 51 (such as Figure 3 These protrusion structures 51 are arranged at the position of the valve core 5 that is most significantly affected by erosion, directly affecting the streamline trajectory in the flow field, and can significantly reduce the erosion of the fluid medium on the valve inner parts.

[0061] The main body of the valve core 5 is a cylindrical structure, which is built into the inner sleeve 4. A plurality of throttle holes 2 are distributed in the lower part of the inner sleeve 4. As the valve core 5 moves upward, more and more throttle holes 2 on the inner sleeve 4 are exposed, which can coordinately control the flow characteristics of the single-seat valve, and has significant pressure reduction and speed regulation effects.

[0062] Finally, the fluid flows through the throttle hole 3 of the outer sleeve 6 and converges into the outlet flow channel. The throttle hole 3 of the outer sleeve 6 also forms a pressure reduction and speed regulation process (the flow field velocity and pressure distribution when fully opened are as follows Figure 4 , Figure 5 shown).

[0063] In this embodiment, the optimization design process of the erosion-resistant cage-type single-seat valve is as follows:

[0064] 1) Establish a three-dimensional simulation model of the erosion-resistant cage single-seat valve, such as Figure 2 As shown. Based on the erosion rate of the internal flow field analyzed by finite element simulation, the initial finite element model of the single-seat valve is established, the hexahedron and tetrahedron mixed grids are divided, and the grid near the sealing surface is encrypted. The number of divided grids is determined through the finite element grid independence experiment. After setting the boundary conditions, the erosion rate of the single-seat valve is simulated and analyzed to obtain the optimized basic data.

[0065] 2) Taking the working condition of 8.84MPa pressure difference before and after the single seat valve as an example, the erosion rate of the valve trim is taken as the optimization target (that is, minimizing the erosion rate of the valve trim), the number and aperture size of the throttling hole three of the outer sleeve and the throttling hole one of the cage-type valve seat, as well as the number and diameter of the protruding structure on the outer side of the valve core, a total of six parameters are used as design parameter variables.

[0066] 3) Analyze the sensitivity of the design parameter variables to the optimization target, that is, analyze the influence of each design parameter variable on the optimization target, and by adjusting the value range of the six parameters, determine whether the six parameters have a significant impact on the optimization target.

[0067] 4) Using the data samples provided by the finite element simulation erosion rate test, Design-Expert software was used for experimental design and data analysis, and the Box-Behnken response surface optimization method was used to establish a quadratic polynomial fitting model, namely a second-order design model.

[0068] 5) Using the second-order design model, the optimal value of the response surface is accurately approximated within the set investigation range, and the items that have no significant impact on the response value are eliminated to obtain the optimal parameter matching solution. The simulation design process is as follows: Figure 6 shown.

[0069] The optimal parameter matching solution obtained in this embodiment is as follows:

[0070]

[0071] In order to verify the anti-erosion performance of the anti-erosion cage single-seat valve after parameter optimization, the erosion rates of the main valve internal components were simulated and compared under the same working conditions according to the structural parameter models before and after optimization. Figure 7 To optimize the erosion rate distribution of the front valve core; Figure 8 The erosion rate distribution of the optimized valve core. It can be seen that after adopting the optimized structure of the present invention, the erosion of the valve core is significantly improved, and the erosion rate is significantly reduced. After optimization, the erosion rate at full opening is reduced from 8.00×10 -2 kg / (m 2 ·s) is reduced to 1.52×10 -2 kg / (m 2 ·s), good anti-erosion effect.

[0072] Conclusion: The erosion-resistant cage-type single-seat valve designed according to the optimization design method of the present invention has a good erosion-resistant effect. The optimization design method of the present invention can provide an optimal parameter combination of the throttle hole three on the outer sleeve, the throttle hole one on the cage-type valve seat, and the convex structure on the valve core, thereby improving the erosion resistance without affecting the flow characteristics of the single-seat valve.

[0073] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An erosion-resistant cage-type single-seat valve, comprising a valve body, an upper valve cover, a valve core and a valve stem; characterized in that: The valve body also includes an inner sleeve, an outer sleeve and a cage-type valve seat; the valve core and the valve stem are an integrated structure; a fluid inlet is arranged on one side of the valve body to form an inlet flow channel, and a fluid outlet is arranged on the other side to form an outlet flow channel, the top of the inlet flow channel and the bottom of the outlet flow channel are connected in the middle of the valve body, and a cage-type valve seat is arranged at the connecting point; the lower part of the cage-type valve seat is located in the inlet flow channel and a plurality of throttling holes are arranged circumferentially; an opening is arranged on the top of the cage-type valve seat to cooperate with the lower end of the valve core to form a main flow channel; an inner sleeve is arranged above the cage-type valve seat and on the periphery of the valve core, and a plurality of throttling holes are arranged circumferentially at the lower part of the inner sleeve at a height corresponding to the outlet flow channel; an outer sleeve is arranged on the outer side of the lower part of the inner sleeve, and a plurality of throttling holes are arranged circumferentially on the outer sleeve; the outer sleeve is located between the inner sleeve and the cage-type valve seat; the inner sleeve, the outer sleeve and the cage-type valve seat are pressed and fixed in the valve body by the upper valve cover.

2. The erosion-resistant cage-type single-seat valve according to claim 1, characterized in that: The matching section between the lower part of the valve core and the cage-type valve seat is a multi-stage variable diameter structure, and the diameter of the multi-stage variable diameter structure gradually decreases from top to bottom; specifically, the multi-stage variable diameter structure is composed of a large-taper cone, a small-taper cone and a hemisphere in sequence, and the connections between the three are smoothly transitioned; a plurality of protrusion structures are evenly arranged along the circumferential direction on the outer sides of the large-taper cone and the hemisphere.

3. The erosion-resistant cage-type single-seat valve according to claim 1, characterized in that: Gaskets are arranged at the contact surfaces of the outer sleeve, the inner sleeve and the cage-type valve seat.

4. The erosion-resistant cage-type single-seat valve according to claim 1, characterized in that: The throttling hole 1 is a stepped hole, and the hole diameter close to the outer side is larger than the hole diameter close to the inner side.

5. The erosion-resistant cage-type single-seat valve according to claim 1, characterized in that: The throttle hole three and the throttle hole two are arranged alternately.

6. The erosion-resistant cage-type single-seat valve according to claim 1, characterized in that: The protrusion structure is a hemispherical protrusion.

7. An optimization design method for an erosion-resistant cage-type single-seat valve according to any one of claims 1 to 6, characterized in that: The steps include: 1) Formulate an optimization strategy on the premise of satisfying the flow characteristics of the single-seat valve: take the erosion rate of the valve trim as the optimization target, that is, minimize the erosion rate of the valve trim; take the number and diameter of throttle holes 1 and throttle holes 3, and the number and diameter of the protrusion structure on the valve core as design parameter variables; 2) Sensitivity analysis of design parameter variables on optimization objectives, that is, analyzing the influence of each design parameter variable on the optimization objective: by adjusting the value range of each parameter, it is determined that each parameter has a significant influence on the optimization objective; 3) Use finite element simulation erosion rate test to provide data samples: Use Design-Expert software for experimental design and data analysis, and use the Box-Behnken response surface optimization method to establish a quadratic polynomial fitting model, i.e., a second-order design model; 4) The second-order design model is used to accurately approximate the optimal value of the response surface within the set investigation range, and the items that have no significant impact on the response value are eliminated to obtain the optimal parameter matching solution.

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