I. Overview:
At present, the airflow delivered by the reliable shut-off gas pipeline is usually combined with a blind plate, a plug-in plate, an eye valve and a sector valve to form a partition device after sealing the butterfly valve or the gate valve, or a double-plate shut-off valve is used as the partition device. This article describes a new single-valve multi-pass liquid-sealing valve to replace the eye valve, sector valve and double-plate shut-off valve.
Second, analysis:
The combined partitioning device uses a rigid blocking plate between the valve body flange or the pipe flange. When inserting or withdrawing the rigid blocking plate, the manual or mechanical method must be used to loosen-clamp the sealing pair to realize the partition of the medium. After the pipeline is put into use, there may be deposits in the seat of the sealing butterfly valve, the gate valve or the inserting plate, which affects the close contact between the sealing pair of the valve plate and the valve seat when the valve is closed. Therefore, when the blind plate operation or the opening or closing of the eye valve or the fan valve is performed, the harmful gas escapes, resulting in high work intensity and high risk. In addition, the combined partition device has many sealing parts and a complicated mechanical structure.
The double-plate shut-off valve blocking device may have deposits in the valve seat after the pipeline is put into use, which affects the close connection between the sealing pair of the valve plate and the valve seat when the valve is closed. At this time, the valve plate and the valve are continuously passed to both sides. The body is formed into a cavity to ensure that the hydrostatic pressure at the sealing pair is greater than the pressure of the gaseous medium, thereby ensuring that the gaseous medium does not leak to the side that is blocked. The double-plate shut-off valve is difficult to manufacture, especially the assembly precision of the two valve plates and the grinding of the sealing surface. The two valve plates of the valve are synchronously turned or lifted by the link transmission mechanism, and the failure of the single block affects the opening and closing of the valve plate, and the troubleshooting is difficult.
In order to overcome the shortcomings of the combined and double-plate cut-off blocking device, a new single-valve multi-pass liquid sealing valve (referred to as liquid sealing valve, the same below) has been designed. The valve has applied for a national invention patent (application number 2009103037153).
Third, the working principle:
The liquid sealing valve is mainly composed of a valve body, a valve plate, a valve seat, a valve plate transmission mechanism, an upper partition plate and an upper diaphragm transmission mechanism. A separate liquid sealing chamber is disposed in the valve body, and is formed by nesting the upper partition plate and the lower bottom plate of the valve body. The upper partition is an inverted cup shape, and the whole can be moved up and down. The upper partition is provided with an annular multi-layer partition. The lower bottom plate of the valve body is cup-shaped and fixed, and the annular bottom plate is also provided on the lower bottom plate.
When the valve is closed, the valve plate is first closed, and then the upper partition plate is driven by the transmission mechanism, so that the annular multi-layer partition plate of the upper partition plate is inserted from the upper and lower sides into the annular multi-layer partition plate on the lower bottom plate, and the upper partition plate is The annular multi-layer baffle and the annular multi-layer baffle on the lower bottom plate are nested with each other to form a multi-pass liquid seal inner cavity. Open the discharge valve on the valve body after the discharge port/liquid seal height observation port to the atmosphere, and observe whether the gas medium continuously escapes to determine whether the sealing seat of the valve seat and the valve plate are in close contact. Even if the sealing seat of the valve seat and the valve plate fails to fit closely, the liquid injection valve is then opened to inject liquid into the liquid sealing chamber, and the liquid gradually overflows to the outside along the inner annular partition until the liquid is viewed from the height of the discharge port/liquid seal. After the mouth overflows, the injection can be stopped. The height of the liquid seal in the liquid seal chamber ensures that the gaseous medium does not leak to the side that is blocked.
When opening the valve, first open the liquid discharge valve at the liquid discharge port on the valve body, drain the liquid in each step of the liquid seal inner cavity, and then close each liquid discharge valve in turn, then close the discharge port/liquid seal height observation port. After the valve. Then, the upper partition plate is moved to the upper part of the valve body by the transmission mechanism, so that the annular multi-layer partition plate of the upper partition plate is separated from the nested structure formed by the annular multilayer partition plate on the lower bottom plate, and the valve body can be turned into a smooth gas. Flow channel, and finally open the valve plate.
Fourth, the structural design:
According to different design and installation requirements, the liquid sealing valve has three types: vertical type, horizontal type and horizontal-vertical type. Corresponding to the vertical section, horizontal section and turning section installed in the pipeline. The vertical type is based on the axis of the gas inlet height direction, and the axis of the gas outlet height direction can be adjusted according to the actual installation requirements, that is, in actual application, one or two elbows on the pipeline can be saved. The horizontal type is based on the horizontal axis of the gas inlet, and the horizontal axis of the gas outlet can be arbitrarily arranged within ±90°. The horizontal-vertical horizontal gas inlet/outlet horizontal axis can be arbitrarily arranged within ±180°, and the horizontal gas inlet/outlet height can be adjusted according to the actual installation requirements. In practical applications, the pipeline can also be saved. 1 to 2 bends.
According to the flow direction of the gas, the liquid sealing chamber is arranged behind the valve plate. The gas flow cross-sectional area at any point in the valve body is not less than the cross-sectional area of ​​the pipe. Since the liquid sealing chamber is a nesting structure that can be separated up and down, the gas flow passage in the liquid sealing chamber after the valve is closed is not a normal gas flow passage when the valve is opened, so that the volume of the valve body is greatly reduced.
The number of liquid seal chambers can be any number of passes, usually 2 to 6 passes. The annular multilayer separator corresponding to the upper and lower substrates is also any number of layers, usually 2 to 6 layers of separator. The effective liquid seal height designed in the liquid seal chamber must meet the requirements and specifications of the corresponding gas medium. Taking gas as an example, it must comply with the provisions of GB6222-2005 for the effective liquid seal height, that is, the effective liquid seal height is at least 5000 Pa for the gas calculation pressure.
The multi-pass liquid seal greatly reduces the actual liquid injection height, and reduces the operation quality of the valve under the premise of ensuring the effective liquid seal height. The liquid sealing liquid selected should be a chemically stable liquid which is non-volatile or low-volatile under normal temperature and pressure, and does not react with the gas medium and the liquid-sealed cavity base material which are blocked, and should have good flame retardancy. Common liquid sealing fluids include water and fluoro oil. If a higher density fluoro oil is used, the volume of the valve can be further reduced.
The wall thickness of the valve body of the liquid sealing valve is not less than the wall thickness of the corresponding installation pipe. The material of the valve body is the same as or better than the material of the corresponding installation pipe. Since the liquid sealing chamber is designed in the valve body, it is inconvenient to repair or replace. Therefore, the materials of the central tube, the partition plate and the like which constitute the liquid sealing chamber inner part are superior to the material of the valve body, such as 304, 316 or 316L. Stainless steel, the thickness of each component is also greater than the wall thickness of the valve body.
V. Conclusion
The liquid sealing valve has many characteristics for blocking the gas flow delivered by the gas pipeline.
1 The independent liquid sealing chamber is used to avoid the influence of the leakage of the gas medium caused by the close contact between the sealing pair of the valve plate and the valve seat during the use. 2 In the liquid-sealed cavity, the nested structure can be separated up and down to form a multi-pass liquid seal, which ensures sufficient liquid seal height in a small space, reduces the valve volume, and reduces the quality and operation quality of the valve itself. 3 Valves are suitable for installation in different parts of the pipeline, such as horizontal sections, vertical sections or elbows, to meet different design and installation requirements, especially suitable for large-diameter gas pipelines and applications in tight spaces. 4 The mechanical structure is simple and the manufacturing cost is reduced. 5 The operation failure rate is low, and the maintenance and repair is simple and convenient.
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Label: Features of single valve multi-pass liquid seal valve
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