Experimental Study On The Separation Of Polymer Containing Wastewater By Gas-Injected Hydrocyclone

Tertiary oil recovery is an important measure to increase oil recovery of crude oil.Chemical flooding is the most widely used technology in tertiary oil recovery,and polymer flooding technology is one of the most effective methods.But a great amount of high viscosity,high polymer,and high degree of emulsification oil field wastewater would be produced,causing a lot of difficulties in oil-water separation and sewage treatment.Based on the summary of domestic and foreign sewage treatment and oil-water separation,the combination of cyclone technology and air flotation technology was used on treatment of polymer-contained wastewater.The chemical properties of oilfield polymer-contained wastewater were analyzed.The effects of cyclone physical parameters and operating parameters on separation efficiency were investigated.Results showed that in a certain range,the hydrocyclone is suitable for the treatment of high degree of emulsification and high oil content polymer-contained wastewater.Changing the entrance flow and the cyclone overflow ratio,the result showed that when the entrance flow reached 4.3m~3/h and the overflow ratio was 15%~20%,the hydrocyclone was in a stable and efficient separation zone.Combining the effect of separation efficiency and pressure drop,15%was the optimum overflow rate and the maximum separation efficiency reached 84.4%.The experiment is carried out with the air floating device installing on the hydrocyclone.The separation performance of the hydrocyclone was compared with that of the non-injected hydrocyclone under the same physical parameters,structural parameters and operating parameters.The influence of the location of gas injection,the gas injection area and the gas liquid ratio on the separation performance was analyzed.The results showed that the air flotation hydrocyclone can obviously improve the separation conditions of oil and water,and has more wide operating flexibility and better separation efficiency.Compared with the conventional liquid-liquid hydrocyclone,the separation efficiency of the air swirl coupling device was increased by about 5%-10%.Single row hole gas injection at A section near guide vane,the highest separation efficiency can reach 87.3%,and injection at B section,the highest separation efficiency was up to 85.6%.All the separation efficiency was higher than that without gas injection.But when opened the injection holes on the A and B cross sections at the same time,the separation efficiency decreased significantly,even lower than the separation efficiency under the condition of no gas injection.In the experiment of the influence of gas-liquid ratio on the separation efficiency,the separation efficiency can reach the maximum when inject gas in A section,the flow rate was 4.2m~3/h,the overflow ratio was15%,and the gas-liquid ratio was 9%.Finally,based on the experimental results,the orthogonal experiment was carried out to determine the optimal parameters of three factors:gas injection rate,overflow ratio and inlet flow rate.This paper provides a theoretical basis and experience for the further study of the separation mechanism and structural optimization design of the air floatation cyclone coupling device.The above research results provide reference for the practical industrial manufacture.