Study On Silo Reciprocating Seal And Blocking Powder Structure In Silo Supercritical Carbon Dioxide Continuous Extraction

Supercritical carbon dioxide continuous extraction technology overcomes the shortcomings of the previous equipment and process that can not continuously enter and exit materials and continuous extraction,and has the advantages of high automation,low operation cost and high safety level.However,in the process of equipment production molding and extraction process test,the following high-pressure sealing problems were encountered: on the premise of ensuring sealing to minimize the impact of powder on seals,at the same time,the design of high-pressure seal structure for silo,to ensure the efficient and stable extraction separation process.Firstly,the author analyzes the working principle of the continuous extraction separation equipment and system of supercritical carbon dioxide,and summarizes the extraction environment and sealing requirements of the supercritical continuous extraction.The existing O-shaped,Y-shaped,Y cup with auxiliary lip and X-shaped ring were selected to analyze the sealing characteristics of different sealing structures.After reference to sub-lip and the four lip structure,a kind of H-shaped sealing ring for bidirectional sealing is designed and its structure is adjusted.Then,finite element models of H-shaped and X-shaped ring pushing process were established to analyze the influence of different leading Angle,leading Angle inner end fillet,pre-compression amount and friction coefficient on the seal in the pushing process,and determine the best pushing condition.The results show that the change of the leading Angle does not affect the maximum stress value of the seal,but with the increase of the pre-compression amount and friction coefficient and the decrease of the leading Angle fillet,the stress values of the seal all increase.Then,on the basis of the best push-in condition,the sealing performance of the seal is analyzed.According to the stress distribution,the gap extrusion phenomenon appeared in the X ring,and the bottom lip of the H ring was the weakest.The maximum contact stress of X ring and H ring exceeds the maximum internal pressure of the medium,and has good sealing performance.The damage of X ring can be prevented by adding baffle ring.The simulation results show that the H ring has strong sealing ability without retaining ring in the process of pressure working,and produces less wear,and is more stable and reliable than the X ring.Finally,the discrete element simulation software EDEM and finite element simulation software ANSYS were coupled to simulate the movement of powder in the sealing gap,and the powder resistance effect of A ring,holes with Yx ring and Che’s combination ring was compared.The results show that the effect of A ring blocking powder is the best;The Che’s combination ring powder resistance has failed.A small number of particles into the Yx ring sealing gap.Experiments on the effect of Yx ring blocking powder at medium pressures of 0MPa,2.5MPa and 5MPa were carried out.The results show that the combination of sealing element and powder resistance ring can effectively prevent the infiltration of particles when there is no pressure.However,with the increase of medium pressure,the particles become paste and adhere to the outer lip,causing wear and leakage to the resistance ring in the reciprocating movement,which is consistent with the simulation results.