CN206419609U - A kind of device for improving the anti-Cavitation of industrial valve - Google Patents

Abstract

The utility model relates to a device for improving the anti-cavitation performance of ordinary industrial valves, which is suitable for any form of industrial valves and can be directly modified on the basis of the original valve pipeline system: the utility model proposes to add an installation between the valve and the pipeline. The fluid diffusion pressurized section has the advantages of increasing the cavitation number of the valve, protecting the inner wall of the pipeline behind the valve, and reducing the scope of cavitation. It can effectively improve the anti-cavitation performance of industrial valves. It is simple to modify, small in investment, and easy to repair and maintain.

Description

A device for improving the anti-cavitation performance of industrial valves

technical field

The utility model relates to a device for improving the anti-cavitation performance of a valve, in particular to a standardized industrial valve suitable for any type, in order to improve the anti-cavitation performance of the pipeline through special transformation.

Background technique

When the internal pressure of the liquid is lower than its saturated vapor pressure, bubbles will form, and some gas dissolved in the liquid will also be precipitated to form bubbles. Subsequently, when the bubbles flow from the low-pressure area to the high-pressure area with the fluid, the bubbles collapse rapidly, and a huge impact force and high temperature are generated at the moment of collapse. This phenomenon is called cavitation.

In engineering, the relative cavitation number is generally used to measure the strength of cavitation. Calculation formula of cavitation number:

Among them, P is the pressure at the control point inside the fluid, pa; P _a is the atmospheric pressure, pa; P _v is the saturated vapor pressure of the fluid, pa; γ is the specific gravity of the fluid; v is the flow velocity at the control point, m/s.

The relative cavitation number is defined as the ratio of the current cavitation number σ to the critical cavitation number _σi ; the cavitation number calculated from the critical state of whether cavitation occurs is the critical cavitation number. Therefore, when the critical cavitation number is greater than 1, it indicates that cavitation has not occurred; when the critical cavitation number is equal to 1, it indicates that it is in a critical state of cavitation; if the critical cavitation number is less than 1, it indicates that cavitation has occurred at this position.

Under the action of high water head, the flow rate in the pipeline is high and the pressure is low. The industrial valve is the control part of the pipeline flow rate and has a throttling effect. Very prone to cavitation.

The hazards of valve cavitation are mainly reflected in three aspects:

1) The high-frequency impact force generated by the cavitation collapse acts on the inner surface of the valve and the pipeline behind the valve, causing material peeling off and directly threatening the safe operation of the valve;

2) When cavitation occurs, the valve will vibrate violently in the vertical and horizontal directions, resulting in loosening of fasteners and accelerating the mechanical wear of pipes and valves;

3) The phenomenon of cavitation will produce a noise similar to sand flowing through the valve due to the bursting of bubbles, which will seriously affect the manufacturing environment;

4) Cavitation is accompanied by the generation of bubbles, forming a blocked flow and affecting the flow capacity of the valve.

If the valve is used under poor conditions and the flow rate is high, cavitation is prone to occur. In general engineering, multi-stage pressure-reducing valves with strong cavitation resistance are used instead of ordinary industrial valves. The working principle is: the pressure drop of the control valve is divided into several stages. , Each small pressure drop ensures that the pressure at the vena contracta will not be lower than the saturated vapor pressure of the liquid, thereby eliminating the generation of air bubbles and preventing cavitation from occurring. However, the internal structure of the multi-stage pressure-reducing valve is complex and the price is high, which is several times the cost of ordinary valves.

Contents of the invention

The technical problem to be solved by the utility model is to propose an economical and reliable technical solution that can improve the anti-cavitation performance of the valve itself, aiming at the cavitation phenomenon of industrial valves under the condition of high flow rate.

The technical scheme that the utility model solves above technical problem is:

According to the mechanism of cavitation, the cross-sectional area at the valve is the smallest, so the flow rate is the largest and the pressure is the lowest, which is the cavitation area, and then the cavitation is carried by the fluid to the high-pressure area and collapses instantly, resulting in cavitation damage. It can be inferred from this The cavitation collapse area is mainly concentrated in the pipeline after the valve.

Based on the above analysis, this utility model avoids the difficulty of reforming the flow channel of the valve itself, and finds a new way, starting from the shape of the pipeline behind the valve, carrying out special design and key protection on the shape of the pipeline behind the valve, and proposes a method to improve the anti-cavitation performance of industrial valves The device is characterized in that the device is a hollow structure with a sudden or gradual change in cross-sectional area larger than the cross-sectional area of the water delivery pipeline, and it is arranged behind the industrial valve and in front of the water delivery pipeline.

Preferably,

The device may have a sudden change structure, and the flow cross-sectional area from the water inlet end to the water outlet end remains unchanged.

Another preference,

The device has a gradual change structure, and the flow cross-sectional area from the water inlet end to the water outlet end gradually expands first, and then gradually shrinks.

The utility model has the advantages of:

1) The increase of the outflow area behind the valve is conducive to the full diffusion of the fluid. There is no restriction on the flow direction of the original pipeline. To a certain extent, the flow rate is reduced while the pressure behind the valve is increased. According to the calculation formula of cavitation number, under the same working conditions , the flow rate decreases and the pressure increases, the value of the cavitation number increases accordingly while the critical cavitation number remains unchanged, so the value of the relative cavitation also becomes larger, indicating that the cavitation resistance of the valve is improved.

2) The inner wall of the ordinary pipeline is located in the cavitation collapse area, as shown in Figure 2. The cross-sectional area of the diffusion pressurized section is larger than the original valve pipe cross-sectional area, and its inner wall is far away from the cavitation collapse area, so that the cavitation acts inside the fluid and plays a role. To protect the inner wall from damage.

In the design of high-velocity pipelines, the cavitation problem of industrial valves directly affects the safe operation of the system. The utility model has a simple structure and is suitable for any form of industrial valves, which greatly reduces the cost and improves the safety of the project. Application prospect.

Description of drawings

Figure 1 is a comparison between the layout of the diffusion pressurization section in Embodiment 1 and the traditional pipeline layout.

Figure 2 is a schematic diagram of the cavitation collapse zone of a common industrial butterfly valve.

Fig. 3 is a schematic layout diagram of the second embodiment of the utility model.

detailed description

Embodiment one

The comparison between the layout of the fluid diffusion pressurized section after the valve and the shape of the traditional water pipe is shown in Figure 1.

A device for improving the anti-cavitation performance of industrial valves. A diffusion pressurization section 3 is added behind the industrial valve 1 and in front of the water delivery pipeline 2; through this special structure, the flow rate is reduced and the pressure is increased, thereby improving the anti-cavitation performance of the industrial valves.

The diffusion increasing section 3 adopts a gradual structure, and its water inlet and water outlet can be connected to the upstream and downstream pipes by welding. The flow cross-sectional area from the water inlet to the water outlet first gradually expands to about three times the cross-sectional area of the pipe, and then gradually shrinks. The length of the diffusion booster section is about five times the pipe diameter.

Embodiment two

As shown in Figure 3, the diffused pressurized section 3 for improving the anti-cavitation performance of industrial valves in this embodiment adopts a sudden change structure, and the flow cross-sectional area from the water inlet end to the water outlet end remains unchanged, which is about three times the cross-sectional area of the water delivery pipeline about. The length of the diffusion booster section is about five times the pipe diameter. After the cross-sectional area of the flow behind the valve is increased, the mainstream can diffuse quickly along the process, reducing the flow velocity of the mainstream, and at the same time increasing the pressure behind the working door, which is beneficial to improving the anti-cavitation performance of industrial valves.

According to the actual situation of the project, the utility model can also have other implementation plans, as long as an inclined surface (or curved surface) gradient or a right angle mutation is added behind the industrial valve and in front of the water pipeline, the diffusion booster section with a larger flow cross-sectional area can be used. Arrangement forms that can improve the cavitation resistance performance of industrial valves are all within the scope of protection required by the utility model.

Claims (3)

1. A device for improving the anti-cavitation performance of industrial valves, characterized in that the device is a hollow structure with a sudden or gradual change in cross-sectional area larger than the cross-sectional area of the water pipeline (2), which is set on the industrial valve (1) After, before the water pipeline (2). 2. The device for improving the anti-cavitation performance of industrial valves according to claim 1, characterized in that: the device is a sudden change structure, and the flow cross-sectional area from the water inlet end to the water outlet end remains unchanged. 3. The device for improving the anti-cavitation performance of industrial valves according to claim 1, characterized in that: the device is a gradual structure, and the flow cross-sectional area from the water inlet end to the water outlet end gradually expands first, and then gradually decreases.