Finite Element Analysis And Optimization Of Double-cone Seal

With the rapid development of modern industry,the development of the petrochemical enterprise scale expansion and chemical equipment of large scale has become a trend in today’s industry.As chemical equipment has becoming larger,so it will increase the difficulty of the seal of high pressure vessel.In order to solve the sealing problems,in recent years,the various forms of seal appeared for different types of pressure vessel.And double-cone sealing structure due to its good sealed performance is integrated in the various types of pressure vessel,that is widely used in sealing structure.According to different sealing force,high pressure sealing structure used in common can be divided into mandatory seal,half self-tightening seal and the tight closure.Double-cone sealing is a kind of half self-tightening seal structure,it has the advantages of simple structure,easy processing and convenient installation and adaptability to the pressure and temperature fluctuations.On the current specification,the limited number of specification parameters is presented.When the relative parameters in the actual project and these specifications are not adaptable,to effectively adjust parameters,ensuring the sealing effect will need to discuss the double-cone sealing principle of possible conditions.Including double-cone ring of material,thickness,height,number,diameter,taper Angle,the influence of pressure on the sealing effect.Based on the combination of JingMen refinery hydrogenation reactor of the specific conditions of the double-cone sealing,we should adopt the method of combining theoretical analysis.Numerical simulation of double cone sealing process was studied,and we examine the GB150-2011 “pressure vessel ”for the applicability of the large double-cone sealing structure design,and propose the corresponding adjustment.Main work and conclusions are as follows:(1)In this paper,it is based on double-cone sealing principle of sealing by using the finite element numerical analysis method to solve the preloaded double-cone ring gasket and a work situation of compression force,the double-cone ring deformation and the stress of the twin cone ring,and we explore gasket pressure fluctuations in the change of pressure force;(2)Simulated by the finite element analysis,under the same size,we calculate different thickness and angle of the double-cone change trend of radial displacement and strain of the ring in the case of preloaded,so as to change the standard within a certain scope the thickness of the double-cone ring and cone angle to adapt to the special condition.And we compare flat cover bearing surface exist or not(and double-cone ring forming cylinder radial clearance g)to the double-cone sealing effect;(3)Simulated by the finite element analysis,we get operating conditions of double-cone ring Mises equivalent stress distribution and the gasket stress distribution,and the gasket stress,double taper ring strain and radial clearance along with the change of pre-tightening load and internal pressure load curve.If a radial clearance g by the 0.15% of D1 to design,the double-cone ring material inevitable overall yield will happen;If a radial clearance g by the 0.05% of D1 design,in the process of pressurized sealing performance is not guaranteed.The study found that: when the other conditions remain unchanged,with the increase of radial compression displacement of double-cone ring thickness decreases gradually with the increase of compression;radial displacement of double cone-ring increases with the angle increases gradually;So,in the special condition,we can change the standard of double-cone ring’s thickness and angle to adapt to the special conditions within a certain range.For the operating conditions,to ensure that when the double cone ring just for an instant,from flat cover supporting surface cylinder is ‘m’ times the sealing face of the pressure to achieve internal pressure(m is for gasket coefficient);Overall stress and double-cone ring shall not be higher than its yield strength;So,according to this two conditions,the limit of radial clearance ‘g’ should be designed in 0.075% ~ 0.125% D1,that is more reasonable.(4)For flat pad seals,the sealing element has a simple flat gasket and the gasket has a certain yield limit,so that the residual pretension of the unit area in the pretreated state can not exceed the yield limit of the gasket.And when the working pressure is too large,the flat cover has trend of raise,the gasket sealing pressure will drop,then it relies the flat gasket deformation to make up the loss.If the working pressure causes the gasket to lose the pressure of the gasket beyond the residual force of the gasket to compensate for the specific pressure,it will inevitably lead to leakage of the device.For the double-cone ring,the sealing element is composed of double-cone ring and gasket together,double-cone ring generally use 35 steel,16 Mn and other rigid materials,the yield limit is much higher than the aluminum gasket,and the sealing element.The structure is also more special.Sealing surface is the double cone,and the vertical direction will be into a certain angle(usually 30 degrees).When the pressure is too large,the flat cover will have the trend of upward lifting and the sealing pressure will decrease.While at the same time,pre-tight state when the double-cone ring will produce a certain radial displacement(the displacement of g).And the internal pressure increases,the double-cone ring cylindrical surface will expand at the same time,the expansion of the release of the elastic force and the direction of the sealing surface will form a certain angle,so it can give the sealing surface to provide a certain force to increase the sealing pressure(this part of the sealing ratio Pressure is self-tight pressure).