Characteristics and working principle of the hotte

The characteristics and working principle of single valve plate multi pass liquid seal valve

this paper introduces the structural characteristics of the new single valve plate multi pass liquid seal valve. The valve can inject liquid into the independent liquid seal cavity after the valve plate is closed through the combination of the valve plate and the independent liquid seal cavity, forming a reliable isolation device, so as to avoid the blind plate pumping and blocking operation

I. overview:

at present, the reliable isolation of the gas flow transmitted by the gas pipeline usually adopts the combination of one of the blind plate, plug plate, eye valve and sector valve after sealing the butterfly valve or gate valve to form an isolation device, or the double plate shut-off valve is used as the isolation device. This paper introduces a new type of single valve plate multi pass liquid seal valve to replace eye valve, sector valve and double plate shut-off valve

II. Analysis:

combined isolating devices use rigid blanking plates between valve body flanges or pipe flanges. When inserting or extracting rigid blanking plates, large equipment such as tensile testing machine must be used to loosen and clamp the sealing pair manually or mechanically to realize the isolation of media. After the pipeline is put into use, there may be sediment in the valve seat of the sealing butterfly valve, gate valve or plug plate, which will affect the tight fit between the sealing pair of the valve plate and the valve seat when the valve is closed. Therefore, when the blind plate is pulled and blocked or the eye valve or sector valve is opened and closed, hazardous gas will escape, resulting in high operation intensity and high risk. In addition, the combined partition device has many sealing parts and complex mechanical structure

there may be deposits in the valve seat of the double plate shut-off valve isolation device after the pipeline is put into use, which will affect the close fitting between the sealing pair of the valve plate and the valve seat when the valve is closed. At this time, by continuously injecting liquid into the cavity formed by the valve plates and the valve body on both sides, it is ensured that the static pressure of the liquid at the sealing pair is greater than the pressure of the gas medium, so as to ensure that the gas medium does not leak to the isolated side. It is difficult to manufacture the double plate shut-off valve, especially the concentric assembly accuracy of the two valve plates and the grinding of the sealing surface. The two valve plates of the valve are overturned or lifted synchronously by the linkage transmission mechanism. The failure of a single valve affects the opening and closing of the valve plate, which is difficult to troubleshoot

in order to overcome the shortcomings of combined and double plate cut-off isolation devices, a new single valve plate multi-way liquid seal valve (hereinafter referred to as liquid seal valve), which has applied for the national invention patent (application No.)

III. working principle:

the liquid seal valve is mainly composed of valve body, valve plate, valve seat, valve plate transmission mechanism, upper diaphragm and upper diaphragm transmission mechanism. The independent liquid seal cavity is arranged in the valve body, which is composed of the upper diaphragm and the lower bottom plate of the valve body. The upper diaphragm is an inverted cup shape, which can be moved up and down directionally as a whole, and an annular multilayer diaphragm is arranged on the upper diaphragm. The lower bottom plate of the valve body is cup-shaped and fixed, and the lower bottom plate is also provided with an annular multilayer diaphragm

when the valve is closed, first close the valve plate, and then the upper diaphragm is driven by the transmission mechanism, so that the annular multi-layer diaphragm of the upper diaphragm is inserted between the annular multi-layer diaphragms on the lower bottom plate from up to down. The annular multi-layer diaphragm of the upper diaphragm and the annular multi-layer diaphragm on the lower bottom plate are nested with each other to form a multi-pass liquid seal inner cavity. Open the blow off valve behind the blow off port/liquid seal height observation port on the valve body and blow it out to the atmosphere. You can judge whether the valve seat and the sealing pair of the valve plate are closely fitted by observing whether there is continuous escape of gas medium. Even if the sealing pair of the valve seat and the valve plate fails to fit closely, then open the liquid injection valve to inject liquid into the liquid seal cavity, and the liquid gradually overflows outward along the inner annular diaphragm until the liquid overflows from the vent/liquid seal height observation port, then the liquid injection can be stopped. The liquid seal height in the liquid seal cavity ensures that the gas medium does not leak to the isolated side

when opening the valve, first open the drain valves at the drain port on the valve body, drain the liquid in each pass of the liquid seal inner cavity, then close the drain valves in turn, and then close the valves behind the drain port/liquid seal height observation port. Then, the transmission mechanism drives the upper diaphragm to move to the upper part of the valve body, so that the annular multilayer diaphragm of the upper diaphragm is separated from the nested structure formed by the annular multilayer diaphragm on the lower bottom plate, and the valve body can become a smooth gas flow channel, and finally open the valve plate

IV. structural design:

according to different design and installation requirements, liquid seal valves have three structures: vertical, horizontal and horizontal vertical. It corresponds to the vertical section, horizontal section and turning section of the pipeline. The vertical type is subject to the axis in the height direction of the gas inlet, and the axis in the height direction of the gas outlet can be adjusted according to the actual installation needs, that is, in practical application, 1 ~ 2 elbows on the pipe can be saved. The horizontal type is subject to the axis in the horizontal direction of the gas inlet, and the axis in the horizontal direction of the gas outlet can be arbitrarily arranged within the range of ± 90 °. Horizontal vertical gas inlet 1. Steel wire and steel strand in the horizontal direction can be arbitrarily arranged within ± 180 ° due to the high hardness of the sample/outlet horizontal axis. The height of gas inlet/outlet in the horizontal direction can be adjusted according to the actual installation needs. In practical application, 1 ~ 2 elbows on the pipe can also be saved

set according to the flow direction of gas, and the liquid seal chamber is arranged behind the valve plate. The cross-sectional area of any gas passage in the valve body shall not be less than the cross-sectional area of the pipe. Because the liquid seal cavity is a nested structure that can be separated up and down, the gas flow channel in the liquid seal cavity after the valve is closed is not the normal gas flow channel when the valve is opened, which greatly reduces the volume of the valve body

the number of passes of the liquid seal cavity can be any number of passes, usually 2 ~ 6 passes. The annular multi-layer diaphragm corresponding to the upper diaphragm and the lower bottom plate is also any multi-layer, usually 2-6 layers. The effective liquid seal height designed in the liquid seal cavity must meet the requirements of specifications and regulations corresponding to different gas media. Take gas as an example, it must comply with the provisions of GB on the effective liquid seal height, that is, the effective liquid seal height is the calculated pressure of gas plus at least 5000Pa

multi pass liquid seal greatly reduces the actual liquid injection height, and reduces the operation quality of the valve on the premise of ensuring the effective liquid seal height. The selected liquid sealing liquid should be a non-volatile or low volatile liquid with stable chemical properties under normal temperature and pressure, not react with the isolated gas medium and the base metal of the liquid sealing cavity, and should have good flame retardancy. Common liquid sealing fluids include water and fluorine oil. If fluorine oil with higher density is selected, the volume of the valve can be further reduced

the wall thickness of the valve body of the liquid seal valve is not less than that of the corresponding installation pipeline. The material of the valve body is the same as that of the corresponding installation pipeline or better than that of the pipeline, and it is suitable for Tianjin University to use high-temperature and high-pressure molding material. Because the liquid seal cavity is designed in the valve body, it is inconvenient to repair or replace. Therefore, the materials of the central pipe, diaphragm and other components that constitute the liquid seal cavity are better than those of the valve body. For example, 304, 316 or 316L stainless steel is used, and the thickness of each component is also greater than the wall thickness of the valve body

v. conclusion

the liquid seal valve is used to isolate the gas flow transported by the gas pipeline, which has many characteristics

① an independent liquid seal chamber is adopted to avoid the influence of gas medium leakage caused by the sediment in the valve seat hindering the close fitting between the sealing pair of the valve plate and the valve seat during use

② adopt the nested structure design that can be separated up and down in the liquid seal cavity to form a multi-pass liquid seal, ensure sufficient liquid seal height in a small space, reduce the volume of the valve, and reduce the quality of the valve itself and operation quality

③ the valve is suitable for installation in different parts of the pipeline, such as horizontal section, vertical section or elbow, to meet different design and installation requirements, especially suitable for large-diameter gas pipelines and layout applications in narrow spaces

④ simple mechanical structure and low manufacturing cost

⑤ low failure rate during operation, simple and convenient maintenance