Research On Accelerated Separation Method Of Drilling Fluid Centrifuge And Key Structure Design

As one of the solid control equipment,decanter centrifuge plays an important role in the recovery of weighting material and removal of harmful solid phases from the wasted drilling fluids with its advantages of small-particle handing capacity,strong adaptability and ease of use.However,the changeability of physic properties of drilling fluids during the drilling process would raise a series of issues for the working process of decanter centrifuge such as vibration caused by uneven distribution of material,decline of handing capability caused by the reflux of the material and material accumulation caused by overloading.Therefore,combined with the research status and problems encountered in practical application,the large-capacity centrifuges are the tendency of research.In order to solve the problems mentioned above,the key structure of existing centrifuge is optimized based on theoretical analysis and numerical simulation in terms of the points of the low spreading speed of feeding drilling fluid and the lag of tangential velocity in this article,which is valuable for the proposition of the centrifuge with fast settling speed,high separation efficiency and large handling capacity.In this paper the structure of the centrifuge with model of LW355-1250 was optimized based on the design theory of the decanter centrifuge.In detail,it includes the following steps:first of all,the structural parameters of the centrifuge rotor were calculated based on the design criteria and followed the outer diameter and wall thickness of the feed cavity can be determined.Then,the improving design for the structure of the feeding cavity was completed by optimizing the shape of accelerating impeller.Furthermore,the optimal length for the outlet of feeding cavity was determined based on the analysis of the fluid field affected by the sizes of inlet and outlet.Besides,the optimal structure of feeding cavity and accelerating impeller can be obtained by the analysis of the velocity and turbulence intensity of the flow field in the feeding cavity,which affected by the shape of accelerating impeller blade(cylindrical blade,twisted blade and combined blade),profile(single circular and double circular arc),curve parameters(inlet and outlet diameter,entrance and export placement angle)and number of blades.Finally,the optimal blade profile was obtained by analyzing the velocity and pressure characteristics of the flow field on the basis of the selected blade shape of cylinder.By comparing the flow field between the conventional centrifuge with the design parameters and the accelerated centrifuge based on the distribution of materials,tangential velocity changes and the separation efficiency,the separation capability of the accelerated settling centrifuge was verified.In addition,it was found that the accelerated centrifuge showed the better adaptability to the feeding materials under different parameters compared with the conventional centrifuge.Finally,the structure strength of the scroll-carrier of conventional and accelerated centrifuge was studied based on the fluid-solid coupling theory,which verified the strength of the centrifuge.