The Research Of Aerostatic Gas Seal

From the current situation at home and abroad, dry gas seal's research and application are mainly for high-speed rotary machinery like centrifugal compressor etc., this type of dry gas seal called dynamic pressure gas seal. In the high-speed operation, the dynamic pressure gas seal has a strong effect of dynamic pressure, can get large opening force and membrane rigidity in order to achieve the stable operation of sealing. But in the pump, the reactor and the other low speed operations dynamic pressure gas seal will be unable to operate properly, and even cause failure while aerostatic gas seal shows excellent performance at this condition and becomes the focus of research.Based on relevant literature of dry gas seal profiles, the working principle and the typical structure of aerostatic gas seal were introduced. Parameters which affecting the dry gas seal performance has been analyzed and numerical simulation has been done on the end face flow field. Finally structure design and experimental research have been done on a aerostatic gas seal applied on BYD stirrer (stirred tank reactor).On the basis of basic principle of hydro-mechanics, governing equations for the end face gas film and gas flow through the orifice and both sides of the surface are established under isothermal condition and converted into dimensionless form. Formula of the main parameters such as film pressure, stiffness, leakage and opening force are also established.From the point of computing hydro-mechanics view, the 3d geometry model of aerostatic gas seal is established with Pro/E .At the same time the part which cut off from the whole model as computational domain has been meshed with Gambit. And FLUNT is used in numeral simulation of the end face flow field. Impact of face clearance and orifice parameters on face pressure, opening force and leakage are analyzed. Analysis shows that as the surface gap increases the orifice exit pressure reduces which is more clear with small gap, opening force decreases with increasing gap overall with a minimum near zero and change of the opening force varies a lot with different gap extent. The leakage increases with different gap and there is a maximum value decided by size of the orifice, obvious differences can be found among leakage with different gap range.BYD Company stirred tank reactor for the use of condition, designed a set of external hydrostatic pressure type dry gas seal system. The End main dimensions are: orifice diameter of 0.2mm, the number of end-shallow groove 4; end diameter R1 = 48mm, inner diameter R2= 36mm; shallow groove outer radius Rd1= 44mm, inner radius Rd2 = 40mm. Axis is given in the assembly diagram, the possible leakage of the seal means; on the selection of materials for the main components were introduced; and design of the aerostatic gas seal for the static and dynamic pressure and other performance testing, The measured parameters are within normal range, to meet the requirements.