Study On The Influence Of Cylinder Speed Ratio Of Sleeper Screw Centrifuge On Separation Characteristics

Oily solid waste will be produced in the process of exploitation,transportation and treatment of crude oil,most of which are oil sands.If directly discharged,it will cause environmental pollution.Therefore,it is necessary to recycle the oil,which not only improves economic benefits,but also reduces environmental pollution.Oil sand separation is a solid-liquid separation process,usually using horizontal screw centrifuge.At present,the research on horizontal screw centrifuge for oil sand separation mainly focuses on its structural parameters,while ignoring the operating parameters.In this paper,the internal flow field of the decanter centrifuge is numerically simulated based on Fluent software.The movement process of the fluid in the decanter centrifuge is clarified.The influence of the speed ratio on the flow field and separation performance is analyzed,and the optimal speed ratio is explored.Through the study of the fluid motion process of the horizontal screw centrifuge,it is found that the pressure at the inlet is negative pressure,which is beneficial to the suction of the material.With the increase of the pressure of the drum cone section,the speed of the solid phase being thrown out also increases.The law of flow field and separation performance under different rotational speed ratios was explored.It was found that the smaller the rotational speed difference between the drum and the screw pusher,the greater the tangential velocity,axial velocity and radial velocity of the material,and the solid volume fraction of the cone section of the drum was greater than that of the column section of the drum.According to the two parameters of the moisture content of the slag outlet and the solid phase recovery rate,it is concluded that when the speed difference is 40r/min,that is,the speed ratio is 100:99,the oil sand separation efficiency of the horizontal screw centrifuge is the highest.On this basis,the optimal operating conditions under the optimal speed ratio are further explored.The results show that the smaller the sand diameter is,the larger the sand content is,the smaller the inlet velocity is,the smaller the settling velocity is.When the sand diameter is too small or too large,the solid phase volume fraction near the slag outlet is small.When the sand content is too small,the settlement layer is too thin to be disturbed.When the sand content is too large,it will affect the settled solid phase.In summary,the recommended operating parameters of the decanter centrifuge under the optimal speed ratio are obtained in this paper.The optimum sand diameter is in the range of 40μm-55μm,the optimum sand content is in the range of 40%-60%,and the optimum inlet velocity is in the range of 1m/s-2m/s.In this paper,through the detailed study of the speed ratio,the influence of the speed ratio on the flow field of the horizontal screw centrifuge is clarified,the applicable conditions of the optimal speed ratio are determined,the oil sand two-phase separation technology is improved,and the oil sand two-phase separation equipment provides a scientific basis.