A method for alleviating erosion of high-speed jet on expansion section of angle valve and angle valve

Abstract

The present invention discloses a method for alleviating erosion of an expansion section of an angle valve caused by a high-speed jet, and an angle valve, wherein the internal flow field of the angle valve is, from top to bottom, a throttling area, a valve seat straight section, and a first-stage expansion section. The method comprises: taking the central axis of the first-stage expansion section as the axis, dividing the first-stage expansion section into an inlet side and an opposite-to-inlet side, the inlet side being close to the inlet of the angle valve, and the opposite-to-inlet side being the opposite side of the inlet side; reducing the expansion angle of the inlet side, and increasing the expansion angle of the opposite-to-inlet side, so that the first-stage expansion section is asymmetric based on the axis line of the valve seat straight section; the present invention is easy to implement and has low cost, and can effectively improve the problem of lateral erosion and wear of the expansion section caused by the eccentric jet of the high-pressure angle valve, thereby increasing the service life of the valve.

Description

Technical Field

[0001] The invention relates to the field of fluid control, in particular to a method for alleviating erosion of an expansion section of an angle valve by a high-speed jet and an angle valve. Background Art

[0002] Valves are indispensable fluid control equipment in various sectors of the national economy, including petroleum, chemical industry, power plants, long-distance pipelines, shipbuilding, nuclear industry, aerospace, and offshore oil production. Used to regulate flow and pressure, prevent leakage, and control opening and closing, angle valves are a primary design element for globe valves, throttle valves, check valves, safety valves, and pressure reducing valves due to their simple flow path, low resistance, and minimal leakage. They are suitable for regulating high-pressure differentials, high-viscosity fluids, and fluids containing suspended matter and particulate matter. They can avoid coking and clogging, and are easy to self-clean.

[0003] However, in industries such as petroleum, coal chemical industry, aerospace, and nuclear power, the harsh working environment requires valves to operate under high pressure conditions. After a certain period of use, by observing the erosion of the valve seat and valve body, it was found that during use, severe lateral erosion occurred in the Venturi expansion section on the opposite side of the inlet, causing punch-through and damage to the same part of the valve body, seriously affecting the normal and safe operation of the device. At the same time, due to the serious damage to the valve body, the entire valve must be replaced, resulting in increased costs in the later stage. For example, high-pressure Haitong valves used on warships and ships, turbine regulating valves, methanol feeding high-pressure valves in the chemical industry, oil-coal slurry control valves in the petroleum industry, black water angle valves in coal chemical industry, etc., these high-pressure angle valves all have side wall erosion and wear problems, which makes the valve service life extremely short, with an average service life of only 1-6 months, causing huge economic losses and even posing safety hazards. Summary of the Invention

[0004] Therefore, in order to solve the above-mentioned shortcomings, the present invention provides a method and an angle valve for alleviating the erosion of the expansion section of an angle valve by a high-speed jet. The present invention is easy to implement and has low cost. It can effectively improve the problem of lateral erosion and wear of the expansion section caused by the eccentric jet of the high-pressure angle valve, thereby increasing the service life of the valve.

[0005] On the one hand, the present invention provides a method for alleviating erosion of an angle valve expansion section by a high-speed jet, wherein the internal flow field of the angle valve is composed of a throttling area, a valve seat straight section, and a first-stage expansion section from top to bottom, and the method is characterized in that the method comprises:

[0006] The central axis of the first-stage expansion section is used as the axis center, and the first-stage expansion section is divided into an inlet side and an inlet opposite side, wherein the inlet side is close to the inlet of the angle valve, and the inlet opposite side is the opposite side of the inlet side;

[0007] Reduce the expansion angle on the inlet side and increase the expansion angle on the opposite side of the inlet, so that the first-stage expansion section is asymmetric based on the axis of the straight section of the valve seat.

[0008] Furthermore, the central axis of the first-stage expansion section is offset to the opposite side of the inlet, and forms an angle α with the central axis of the straight section of the valve seat.

[0009] Optionally, the angle α is in the range of 1 to 3°, preferably, the angle α is 2°.

[0010] The above method offsets the central axis of the first-stage expansion section to the opposite side of the inlet, and forms an angle of 1 to 3 degrees with the central axis of the straight section of the valve seat, thereby realizing the regulation of the angle valve pressure. It can effectively improve the problem of lateral erosion and wear of the expansion section caused by the eccentric jet of the high-pressure angle valve, thereby increasing the service life of the valve.

[0011] On the other hand, the present invention provides an angle valve, the internal flow field of which is composed of a throttling area, a valve seat straight section and a first-stage expansion section from top to bottom, wherein the first-stage expansion section is asymmetric based on the axis of the valve seat straight section.

[0012] The central axis of the first-stage expansion section is offset to the opposite side of the inlet, and forms an angle α with the central axis of the straight section of the valve seat; preferably, the angle α is 2°.

[0013] The improved angle valve is easy to implement and has low cost. It can effectively improve the problem of lateral erosion and wear of the expansion section caused by the eccentric jet of the high-pressure angle valve, thereby increasing the service life of the angle valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The three-dimensional model of the high-pressure angle valve (in the figure: 1, valve stem; 2, valve cover; 3, valve body; 4, valve core; 5, valve seat; 6, expansion section);

[0015] Figure 2 It is the meridian velocity distribution and local streamline of the high-pressure angle valve in the symmetrical expansion section;

[0016] Figure 3 It is the pressure parameter monitoring line (in the figure: A is the throttling area, B is the straight section of the valve seat, C is the first-stage expansion section, X and Z are the coordinate axis directions, and L and R are the monitoring lines);

[0017] Figure 4 is the pressure gradient ΔP at the symmetrical position on the monitoring lines L and R;

[0018] Figure 5 It is a schematic diagram of the forces acting on fluid microclusters;

[0019] Figure 6 It is a schematic diagram of the asymmetric expansion section of the present invention;

[0020] Figure 7 The velocity distribution and local streamlines of the meridian plane of the high-pressure angle valve in the asymmetric expansion section;

[0021] Figure 8 is the change in flow field pressure drop in the left and right areas of the high-pressure angle valve;

[0022] Figure 9 It is a three-dimensional high-speed fluid distribution valve with high pressure. DETAILED DESCRIPTION

[0023] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0024] In this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] As described in the background technology, after a certain period of use, the high-pressure angle valve was found to have severe lateral erosion on the venturi expansion section on the opposite side of the inlet during use by observing the erosion of the valve seat and valve body, resulting in punch-through and damage to the same part of the valve body, seriously affecting the normal and safe operation of the device. At the same time, due to the serious damage to the valve body, the entire valve must be replaced, resulting in increased costs in the later stage. For example, high-pressure sea valves used on warships and ships, steam turbine regulating valves, methanol feeding high-pressure valves in the chemical industry, oil-coal slurry control valves in the petroleum industry, black water angle valves in coal chemical industry, and other high-pressure angle valves all have side wall erosion and wear problems, which makes the valve service life extremely short, with an average service life of only 1-6 months, causing huge economic losses and even safety hazards.

[0026] Based on the above situation, this embodiment provides a method for alleviating erosion of the expansion section of an angle valve by a high-speed jet, wherein the internal flow field of the angle valve is composed of a throttling area, a valve seat straight section, and a first-stage expansion section from top to bottom, and is characterized in that the method comprises:

[0027] The central axis of the first-stage expansion section is used as the axis center, and the first-stage expansion section is divided into an inlet side and an inlet opposite side, wherein the inlet side is close to the inlet of the angle valve, and the inlet opposite side is the opposite side of the inlet side;

[0028] Reduce the expansion angle on the inlet side and increase the expansion angle on the opposite side of the inlet, so that the first-stage expansion section is asymmetric based on the axis of the straight section of the valve seat.

[0029] Furthermore, the central axis of the first-stage expansion section is offset to the opposite side of the inlet, and forms an angle α with the central axis of the straight section of the valve seat.

[0030] Optionally, the angle α ranges from 1 to 3°, and preferably, the angle α is 2°.

[0031] For example, Figure 1 As shown, this valve operates in a harsh environment, with an inlet pressure of 18.3 MPa, an outlet pressure of 4.5 MPa, and an ambient operating temperature of 415°C, making it a high-pressure, medium-temperature valve. The valve had an extremely short service life, experiencing unusual noises and unstable flow control after one month of operation. Disassembly of the angle valve revealed severe erosion and wear of the valve seat and expansion section opposite the inlet. Actual engineering observations and numerical simulations revealed a severe eccentric jet phenomenon in the expansion section, with high-speed fluid continuously eroding the opposite inlet wall.

[0032] The angle valve is mainly composed of three types of parts: pressure-bearing parts, throttling parts and driving parts. The pressure-bearing parts mainly include the valve body 3 and the valve cover 2, which are used to ensure the integrity of the flow boundary of the medium in the valve. The throttling part includes the valve core 4 and the valve seat 5, and is placed inside the valve body. It is mainly used to control the flow area of ​​the medium flowing in the valve to achieve the flow regulation function. The driving part includes the valve stem 1 and the actuator connected to it. The valve controls the liquid flow through the pipeline by moving the valve stem up and down to achieve the purpose of controlling the downstream liquid level. In addition, the expansion section 6 composed of a multi-stage bushing is used to achieve the deceleration and pressure expansion function of the fluid. Figure 1 The arrows in the figure indicate the direction of fluid flow. The valve stem travel is 95 mm, and the valve opening is proportional to the stem travel. Under normal operating conditions, the valve opening is 81%, or 76.95 mm. Therefore, the present invention analyzes and compares the flow field before and after the valve modification at this opening.

[0033] The expansion sections of the valve are composed of expansion channels with different angles connected in series. The fluid accelerates from the throttle port into the straight section of the valve seat and then enters the expansion sections of each level to decelerate and expand. However, due to the instability of the upstream flow, the symmetrical expansion sections will produce different degrees of expansion capacity, resulting in non-uniform pressure generation on the left and right sides. After numerical simulation calculations, such as Figure 2 As shown in the figure, from the velocity distribution of the flow field and the local streamline diagram, it can be seen that a serious eccentric jet phenomenon occurs after the fluid enters the expansion section. The high-speed fluid scours the right wall of the expansion section and forms a large vortex on the left.

[0034] In order to more clearly describe the internal flow field of the high-pressure angle valve, it is divided into sections according to its structure, such as Figure 3 As shown, A is the throttling area, B is the straight section of the valve seat, and C is the first-stage expansion section. Two pressure monitoring lines L and R are established.

[0035] Figure 4 is the pressure gradient ΔP at the symmetrical position on the monitoring lines L and R, that is, ΔP=P L -P R The results show that as the fluid moves from the minimum flow area to the inlet of the valve seat straight section, the rapid change in flow area leads to a significant pressure change in the local area, causing the left-right pressure differential ΔP to rise rapidly before rapidly falling. After entering the valve seat straight section, the pressure on the left side is substantially greater than that on the right side, i.e., ΔP>0. The rightward pressure forces the fluid to flow to the right, resulting in a severe eccentric jet phenomenon.

[0036] Figure 5 This is a schematic diagram of the forces acting on the fluid micro-groups inside the valve. After the fluid inside the angle valve enters the primary expansion section, the flow area increases, the fluid velocity decreases, and the pressure increases. The fluid pressure in the left area recovers quickly, indicating that it has a strong pressure expansion capability. The fluid micro-group is subjected to pressure on both sides, but the pressure to the right F L Greater than the leftward pressure F R The pressure gradient to the right causes the high-speed jet to flow to the right. The velocity gradient and pressure gradient of the fluid in the left area of ​​the first-stage expansion section are large, forming a strong shear layer. In addition, the viscosity of the fluid in the valve is large, and the fluid near the wall is subjected to a large viscous force. Under the adverse pressure F P and shear force F v Under this action, a large clockwise vortex is formed, causing separation. The large vortex will hinder the flow of fluid into the mainstream area, have a certain exclusion effect on the mainstream, aggravate the generation of eccentric jets, and force the high-speed fluid to flow to the opposite side of the inlet, continuously scouring the right wall, causing severe erosion and wear in the local area.

[0037] Based on the above analysis, to mitigate the eccentric jet phenomenon generated at the expansion section, the pressure distribution of the flow field can be controlled by varying the pressure expansion capacity on the left and right sides of the expansion section. Therefore, while maintaining the valve's original flow capacity, the present invention offsets the axis OO' of the first-stage expansion section toward the side opposite the inlet, reducing the expansion angle on the left side and increasing it on the right. This slows pressure recovery in the left region, reduces the adverse pressure gradient experienced by the fluid in this region, and mitigates the generation of separation vortices.

[0038] Its structural diagram is as follows Figure 6 As shown. Taking the first expansion section offset of 2° as an example, the constraints are as follows:

[0039] Constraint 1: The angle between the line OO" connecting the centers of the cross sections of the expanded section after modification and the original line OO' is 2°;

[0040] Constraint 2: The offset direction is the opposite side of the inlet;

[0041] Constraint 3: The cross-sectional circular area at the same height of the expansion section remains unchanged after the modification, that is, the pipe diameter at each location of the expansion section remains unchanged;

[0042] In addition, in order to explore the effect of different offset angles on the eccentric jet, this method offsets the first-stage expansion section by 1°, 2°, and 3° respectively. The flow field velocity and local streamline distribution are shown in the figure. Figure 7 shown.

[0043] After a 1° offset, the high-speed flow is still primarily distributed in the right region, but the degree of eccentricity is reduced. Local streamlines show a significant reduction in the vortex on the left. This indicates that the left-side expansion pressure capacity is reduced after the expansion section is offset by 1°. This reduces the adverse pressure gradient in this region, shrinking the separation zone, and thus alleviating the eccentric jet phenomenon to some extent.

[0044] After a 2° offset, the high-speed fluid concentrates primarily in the center of the valve body in the primary expansion section, forming two vortices of similar size and opposite directions in the lower portion of the expansion section. This phenomenon indicates that the velocity gradients and adverse pressure gradients of the fluid on the left and right sides are similar, the flow state is relatively symmetrical, and the eccentric jet phenomenon is significantly alleviated.

[0045] After a 3° offset, the separation zone on the left side of the primary expansion section is significantly reduced, leaving only a small low-velocity zone. Due to the increased right-side expansion angle, the pressure diffusion capacity is enhanced, and the pressure recovery rate is accelerated. The fluid in this area is subjected to a large adverse pressure gradient, resulting in a large vortex zone. The high-speed mainstream flow appears to be deviating to the left.

[0046] The above analysis demonstrates that the asymmetric expansion section structure can suppress the asymmetric pressure gradients between the left and right sides of the valve, thereby mitigating the deflection of the high-speed jet and reducing erosion and wear on the right wall. Different offset angles have varying degrees of influence on the flow field. A suitable offset angle aligns the flow patterns on both sides, allowing the high-speed jet to flow primarily downstream from the valve body axis. For this angle valve, a 2° offset in the first-stage expansion section is most effective.

[0047] Figure 8The pressure curves along the main flow direction for the left and right monitoring lines are shown. It can be seen that the pressure variation trends on the left and right sides of the angle valves with different structures are the same. After the fluid enters the constricted section of the valve seat from the pipeline, the flow area decreases, the flow velocity increases, and the pressure decreases. At the valve seat inflection point, the pressure drops to its lowest point, at which point the fluid velocity reaches its maximum. After entering the straight section of the valve seat, the flow area increases rapidly, the fluid velocity slows, and the pressure recovers quickly. Since the straight section of the valve seat has a constant diameter, the pressure in this area remains relatively stable. After entering the primary expansion section, the flow area continues to increase, and the fluid pressure continues to rise. However, the pressure fluctuations in the left area of ​​the symmetrical expansion angle valve are larger, indicating that the fluid flow is unstable and the pressure gradient is significantly greater than that of the asymmetrical expansion angle valve. Both unstable pressure fluctuations and large pressure gradients can lead to significant separation of the fluid in a localized area, resulting in the formation of larger vortices. In the right area of ​​the symmetrical expansion angle valve, no separation occurs, resulting in smaller pressure fluctuations. However, flow separation occurs in the right area of ​​the asymmetrical expansion angle valve, resulting in larger pressure fluctuations in this area.

[0048] Comparing the pressure distribution in the first-stage expansion section area (area C) with different offset angles, the expansion angle on both sides of the offset of 1° changes little, and the pressure changes on the monitoring lines L and R are slightly different from those of the symmetrical expansion section angle valve; the expansion angle on the left side of the offset of 3° is significantly reduced, the pressure diffusion capacity is weakened, and the pressure gradient on the monitoring line L decreases, while the expansion angle on the right side increases, generating a larger vortex, and the pressure fluctuation on the monitoring line R is larger; compared with the other structures, the pressure gradient on both sides of the offset of 2° is smaller, and the flow field is more stable.

[0049] In order to see the modification effect of the present invention more clearly, as shown in FIG. Figure 9 As shown in the figure, the high-speed flow distribution diagram for high-pressure angle valves with fluid velocities greater than 100 m / s shows that the high-speed jet in the symmetrical expansion section is primarily concentrated on the opposite side of the inlet, severely scouring the right wall. The eccentric jet phenomenon in the asymmetrical expansion section with different offset angles is improved to varying degrees. With an offset of 1°, the low-speed area on the left side is reduced, and the degree of eccentricity to the right is reduced. With an offset of 2°, the high-speed flow distribution becomes more symmetrical and uniform, mainly concentrated in the center. With an offset of 3°, an eccentric jet to the left appears.

[0050] In summary, the high-pressure angle valve designed based on the asymmetric expansion section of pressure regulation can better balance the non-uniform pressure generated inside the flow field. By offsetting the first-stage expansion section to change the pressure expansion capacity of the two side areas, the problem of biased flow erosion caused by the eccentric jet can be alleviated, and the service life of the valve can be increased. Different offset angles will have different degrees of influence on the internal flow field of the high-pressure angle valve. For valves with different structural sizes, it is necessary to select a suitable offset angle. In addition, under the premise of maintaining the original pipe diameter size unchanged, the present invention maintains the flow capacity of the original valve and also maintains the processing of other parts of the original high-pressure angle valve. The processing and manufacturing are relatively simple, low cost, and the effect is significant.

[0051] On the other hand, the present invention provides an angle valve, such as Figure 3 As shown, the internal flow field of the angle valve is composed of a throttling area, a valve seat straight section and a first-stage expansion section from top to bottom. The first-stage expansion section is asymmetric based on the axis of the valve seat straight section.

[0052] The first-stage expansion section is implemented by the above-mentioned method of alleviating the erosion of the angle valve expansion section by the high-speed jet.

[0053] The improved angle valve is easy to implement and has low cost. It can effectively improve the problem of lateral erosion and wear of the expansion section caused by the eccentric jet of the high-pressure angle valve, thereby increasing the service life of the angle valve.

[0054] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for alleviating erosion of the expansion section of an angle valve by a high-speed jet, wherein the internal flow field of the angle valve is composed of a throttling area, a valve seat straight section, and a first-stage expansion section from top to bottom, characterized in that: The method includes: The central axis of the first-stage expansion section is used as the axis center, and the first-stage expansion section is divided into an inlet side and an inlet opposite side, wherein the inlet side is close to the inlet of the angle valve, and the inlet opposite side is the opposite side of the inlet side; Reduce the expansion angle on the inlet side and increase the expansion angle on the opposite side of the inlet, so that the first-stage expansion section is asymmetric based on the axis of the straight section of the valve seat; The central axis of the first-stage expansion section is offset to the opposite side of the inlet. After the offset, the first-stage expansion section forms a non-rotating structure with a constant cross-sectional circular area at the same height, and forms an angle α with the central axis of the straight section of the valve seat; The angle α has a value range of 1 to 3 degrees.

2. The method for alleviating erosion of the expansion section of a diagonal valve by a high-speed jet according to claim 1, characterized in that: The angle α is 2°.

3. An angle valve, characterized in that: The first-stage expansion section of the angle valve is designed by the method described in any one of claims 1-2.

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