Numerical Simulation Of The Effect Of Liquid-solid Two-phase Flow On The Sealing Of Ball Valve

Ball valves are widely used in petrochemical industry and coal chemical industry because of full diameter,large flow rate,low flow resistance and convenient switching.However,the working conditions of these industries are often harsh,existing high temperature,high pressure,toxic,harmful,solid particles and two-phase flow medium,especially liquid and solid two-phase flow.The sealing structure of the ball valve is abrasion and invalid caused by them.Therefore,taken the metal hard sealed ball valve as the research object,using the liquid solid two-phase flow theory to analysis the abrasion characteristics of the sealing structure under different opening angles of the ball valve.Researching the influence rules of the liquid solid two-phase flow on the sealing performance of the valve seal structure based on the numerical simulation.The main work and conclusions are as follows:Firstly,discussing the relationship between sealing performance and the structural parameters by analyzing the sealing mechanism of the valve seal structure.Meanwhile,the formula of the seal ratio pressure,allowable specific pressure and necessary specific pressure on the seal pair is derived which combined with the theoretical and practical working conditions.And find that the ball valve is affected by the projection width of the sealing surface mostly when the other structural parameters are constant.Secondly,establishing three-dimensional model of ball valve seal structure with Solidworks,and the liquid solid two-phase flow erosion model under different open and close angles with Fluent.Numerical simulation analysis of flow field characteristics of different openness(20% opening,40% opening,60% openingand 80% opening)inside the ball valve,obtain flow state of internal flow field from closing to gradual opening.Thirdly,using Fluent to analysis liquid-solid two-phase flow field,obtain that the most serious erosion areas of the valve system are outer surface of the valve,the valve chamber and valve seat end face.By comparing the distribution of the sealing surface erosion of the ball valve under different opening and closing angles of the valve,pushing out that erosion will cause the seat surface to wear,as a result,the projection width of the sealing surface is reduced,the sealing specific pressure is increased,and the sealing performance of the ball valve is reduced.Finally,an optimized design of the outer surface of the vertical valve ball on the end surface of the valve seat is proposed to reduce the projection width of sealing surface caused by erosion.Obtain equivalent stress,displacement and distribution of ball valve by analysis the optimized ball valve with Finite element static.Making physical prototype,inspection of prototypes with valve presses and nitrogen leak detectors,the results show that all test items meet the corresponding standards.The correctness of the ball valve design after optimization was verified.In summary,in this paper,researching the sealing performance of metal hard seal fixed ball valve.Analyzing the effect of liquid-solid two-phase flow on the ball valve sealing structure with numerical simulation method.Optimizing the ball valve structure to improve the sealing performance.