Structural Design And Optimization Of Hydrocyclone For Oil-water Separation Of Liquids Discharged From Abandoned Oil Wells At Sea

The oil-water separation hydrocyclone can separate liquids with different densities by centrifugal force.It has a simple structure and good separation effect,and can meet the requirements of offshore oilfields for compact platform layout.Due to the characteristics of small particle size,dispersed oil phase,and high water content in the oil phase of the discharge fluid from offshore well abandonment,the original hydrocyclone on site is not suitable for the current production conditions on site,the separation efficiency is low,and the downstream electric dehydrator Therefore,according to the current on-site working conditions,the sensitivity analysis of on-site operating parameters is carried out,and the structure optimization of the hydrocyclone is carried out.This paper uses Fluent software to carry out numerical simulation of hydrocyclone,and uses field data to verify the rationality of the model and algorithm.Based on the field data to verify the reasonable model and algorithm,by comparing the flow field,the oil phase distribution in the hydrocyclone and the oil-water separation efficiency,the influence of the oil phase particle size and other operating parameters on the oil-water separation effect was further analyzed.The influence of each operating parameter on the separation efficiency and the water content of the liquid at the overflow outlet is sorted.Three different overflow pipe structures are used to compare with the original thin-walled straight circular overflow pipe.By comparing the pressure field,velocity field and separation effect,the simulation results show that the W type overflow pipe with an included angle of 28° is used.The separation efficiency of the hydrocyclone is the highest,and the mass flow of the water phase at the outlet of the overflow pipe is the lowest,which can reduce the operating load of the downstream electric dehydrator.On this basis,the separation efficiency can be increased to 75.18% by using an overflow pipe with a diameter of 5 mm after the simulation calculation of overflow pipes with different diameters.The four entrance forms of the constricted entrance,the involute entrance,the involute entrance adopted by the Wangyuan and the Archimedes spiral entrance improved on the involute used by the Wangyuan are the same as the original.Compared with the tangential inlet,when the improved Archimedes spiral inlet is used,the separation efficiency reaches93.07%,and the oil phase is densely distributed.And compared the simulation results of this inlet with different aspect ratios,the results show that: after changing the aspect ratio of the inlet rectangle to 0.8,the separation efficiency is the highest of 94.42%,and the water mass flow of the overflow outlet is the lowest of 0.028kg/s,which can be Great downstream electrical dehydrator workload.The optimization study is carried out on the height of the swirl chamber,the cone angle of the large cone section,the cone angle of the small cone section and the length of the flat tail section.When the length of the flat tail section is 1000 mm,the separation efficiency can be increased to 99.07%,and the mass flow rate of the overflow outlet water can be reduced to 0.048kg/s,which can meet the normal downstream production.At the same time,the adaptive analysis of the selected hydrocyclone was carried out,and it was concluded that the high-efficiency separation zone of the hydrocyclone was in the range of the inlet velocity of 10-11.5m/s.