Sealing Performance Research Of Cryogenic Ball Valve And Thermal-mechanical Coupled Analysis

Low temperature device has developed toward the mode of high parameter,large scale.Cryogenic valve as an important supporting equipment,the number of applications in the field is also increasing.However,the design of this kind of valve is still lack of theoretical analysis and standard basis,and less experience during in the use of it,it is prone to some problems,such as cold deformation,sealing leakage,etc.As the key equipment of Low temperature industry,large caliber cryogenic valves is lack of theoretical research and standards when designing relevant parameter,so it used to leak in practice due to cold shock and seat leakage problem.It is extremely necessary to do technical research and development.In low temperature device,the working condition of cryogenic valve is much more difficult than ordinary industrial valve.The ball valve temperature distribution,thermal stress of low temperature and the sealing property are the key factors to ensure the safe operation of the valve,especially the stuffing box seal.Cryogenic ball valve of the main metal seal performance is a key factor about valve design and reliable operation.In this paper,the parametric study on the seal structure.This thesis focused on the LNG cryogenic ball valve(including the structure,pressure drop and material properties)as the research object.Firstly,sealing specific pressure formula in the ideal smooth was deduced;Based on the theory of heat transfer and boiling heat transfer principle,experiential equations and researched results have been reviewed to propose the convection heat transfer coefficient of valve material,which is immersed into liquid nitrogen.Secondly,finite element analysis method is adopted to establish the main sealing structure finite element analysis model,combined with numerical simulation method of cryogenic ball valve under the low temperature heat transfer and sealing problems on study to get the seat sealing pressure distribution on the surface of the seal.Sealing performance evaluation model is proposed to determine the main design parameters affecting the seat sealing characteristics(including sealing width,pressure Angle).Simulating the cryogenic treatment,the transient temperature variation of the temperature field was studied and the effect of the thermal mechanical coupling on the sealing surface was explored.And the design of large diameter cryogenic ball valve is of important guiding significancefor practical use.