Flow Field Analysis And Performance Evaluation Of Coalescence-Cyclone Coupling Separator

A large amount of oily sewage is produced in the process of oil exploitation,and the purification and treatment capacity of oily sewage is improved with the gradual increase of environmental protection requirements.As a kind of oil-water separation equipment,hydraulic cyclone has the advantages of compact structure and short treatment time,but it is difficult to achieve efficient separation of small particle size oil droplets in oilfield sewage.Although the material coalescence deoiling method can realize the efficient separation of small particle size oil droplets,the oil removal efficiency is easily affected by the properties of the material itself,the flow rate of the mixed liquid,the coalescence time and other factors,and its application in the hydrocyclone has the problems of high processing cost and discontinuity.The cyclone coalescence technology has the advantages of low cost and light equipment,so it is widely used.Therefore,it is of great significance to study the coalesce and crushing characteristics of oil droplets in cyclone field,master the influence of oil droplets coalesce on the oil-water separation performance,and guide the design of new structures to change the particle size distribution of oil droplets to improve the oil-water separation performance of hydrocyclone.Based on the principle of cyclone coalescing and the principle of cyclone separation,a new equal-path cyclone coalescing is designed in this paper.The PBM population balance model coupled with Luo coalescing and Luo breaking models are used to analyze the flow field of the new cyclone coalescing and axial flow hydrocyclone,and to study the flow field and oil droplet coalescing and breaking characteristics in their respective structures.The locations of oil droplet coalescing and the effects of operating parameters such as processing capacity and oil concentration on the coalescing performance were studied.According to the simulation results,the initial structure of the cyclone coalesce can coalesce the oil droplet with an average particle size of 23μm to an average particle size of 580μm.Plackett-Burman test design was used to order the significance of the structural parameters that affect the coalescating performance of the cyclone coalescator.The average oil droplet size at the exit was used as the test index to optimize the structural parameters of the cyclone coalescator by orthogonal test optimization method.The optimized structural parameters are as follows: the length of the spiral runner is 90 mm and the number of spiral runner roots is 5.The diameter of the coalescing inner core is 10 mm and the length of the coalescing cavity is 155 mm.The results show that the coalescing performance of the optimized structure is better than that of the initial structure.The optimized cyclone coalesce was connected in series to the front end of the axial flow hydrocyclone to form a coalesce-cyclone coupling separator.The flow field analysis inside the separator was carried out by using numerical simulation.According to the optimized structural parameters of the cyclone coalesce and the axial flow hydrocyclone structural parameters,a matching test process system was constructed to carry out laboratory test verification.The particle size distribution of oil droplets at the inlet and outlet under different operating parameters was compared with the Marvin laser particle size analyzer,and the oil-water separation efficiency of the coalescent-cyclone coupling separator and the single axial flow hydrocyclone under the same boundary conditions was compared with the infrared spectrophotometer.The experimental results show that the particle size distribution of the oil droplets at the exit of the cyclone coalesce is always higher than that at the entrance,and the oil-water separation efficiency of the coalesce-cyclone coupling separator is always higher than that of the axial flow hydrocyclone.