Development And Performance Study Of Horizontal Oily Wastewater Treatment Device

With most of the domestic oil fields entering the high water cut period,a great deal of oily wastewater will be produced in the process of oil refining.If not handled properly,it will cause environmental pollution,and even have a huge influence on the ecology.In this regard,the state has put forward relevant environmental protection policies to limit the oil content in the discharged sewage water,so it is of great significance to remove oil from oilfield produced water.Air flotation is one of the common processes of treatment of oilfield produced water,which has the advantages of short time,high efficiency and wide application,the principle is to make the oil droplets gather and integrate flocs by injecting small bubbles from the air flotation device into the oily sewage,and then float up to the surface of the water body under the action of gravity and buoyancy,and then remove the oil-water separation purpose.In this paper,a horizontal oily wastewater treatment device is designed and developed through a large number of research on air flotation separator.Firstly,a horizontal air floatation oil removal and separation test device is built,which mainly includes horizontal separator,jet device and dissolved gas system.Secondly,based on the experimental device,jet air floatation and pressurized dissolved air floatation were used to remove oil.According to the experimental results,when the oil concentration of influent water is 200 mg/L,the oil concentration at the outlet is about 36mg/L,and the oil removal efficiency is up to 82%by setting the optimal experimental parameters(treatment capacity of 1.5 m~3/h,treatment time of 25 min,gas-liquid ratio of 15%,demulsifier concentration of 15 mg/L,p H value of 7);When the pressurized dissolved gas method is used to treat the oily wastewater with the influent oil concentration of 200mg/L,by setting the optimal parameters(treatment capacity of 2 m~3/h,treatment time of 20 min,gas-liquid ratio of 20%,dissolved gas pressure of 0.35 MPa,reflux ratio of 40%,demulsifier concentration of 15 mg/L,p H value of 7),the lowest oil concentration in the outlet water of the air flotation oil removal equipment is about 31 mg/L,and the oil removal efficiency is about 84.5%.Finally,the CFD technology was used to establish the numerical calculation model of the horizontal air floating oil removal device,and the gas-liquid distribution and pressure distribution in the air floater were calculated under different treatment capacity(2 m~3/h,3m~3/h,4 m~3/h,5 m~3/h)and different gas holdup(20%,30%,40%).The numerical simulation results show that the gas phase distribution in the air flotation equipment is more uniform when the treatment capacity is small,and the oil removal effect is better in theory.With the gradual increase of the treatment capacity,the bubble density in the separation area of the air flotation equipment decreases,which will lead to poor oil removal effect.Therefore,the oil removal experiment should ensure that the treatment capacity is reduced as far as possible under the requirements of work efficiency.With the increase of gas holdup,the proportion of gas phase in the separation zone of air floatation increases,which is conducive to improving the oil removal efficiency.It can be seen from the numerical calculation results that the internal pressure of the air flotation equipment is basically unchanged under the conditions of different inflow flow and gas holdup.