Study On Ultrasonic-Centrifugation Technology Of Refined Sludge

The oily sludge produced in the process of crude oil exploitation,gathering and refining is a dangerous solid waste with large output,difficult treatment and great harm to the surrounding environment and human health.At present,there are advantages and disadvantages in the treatment technology of oily sludge at home and abroad.Most of them have problems such as high treatment cost and easy secondary pollution.Therefore,the problem of sludge treatment has long plagued the petrochemical industry.In this paper,ultrasonic-centrifugation experiments were carried out on the properties of refinery sludge.The optimum conditions of ultrasonic-centrifugation and the properties of oil in oil sludge,water quality,metal element migration,microstructure and solid particle structure were investigated.The impact of the oil sludge reduction and resource treatment provides a new idea,providing a theoretical basis for ultrasonic treatment of oily sludge.The main conclusions of this paper are as follows:(1)Ultrasound-centrifugation treatment has obvious advantages over direct centrifugation and traditional pharmacy-centrifugation.Under the same centrifugal conditions,the dewatering rate of the sludge after ultrasonic treatment is the highest,reaching 90.31%,and the volume reduction is the most obvious,the remaining sludge bottom slag volume is only 1/8 of the original,and the oil recovery rate of the separated oil layer exceeds 75%,and no pesticide is added.(2)Ultrasonic conditions have obvious effects on the dewatering effect of scum.Ultrasonic frequency,action time,input power and treatment temperature have suitable processing conditions.Above or below this range will result in a decrease in dewatering effect.Centrifugal conditions have a significant effect on the moisture content of the remaining sludge bottom slag,and the effect on the overall dewatering rate is general.The optimal ultrasonic-centrifugation conditions obtained in the experiment were as follows: ultrasonic frequency 25 k Hz,input power 240 W,action time 5 min,treatment temperature 30 ?,centrifugal speed 3000 r/min,and centrifugation time 10 min.(3)Ultrasonic-centrifugation treatment has obvious effects on oil properties,water quality and migration of metal elements in sludge.After ultrasonic-centrifugation,the oil is lightened and the oil-water emulsification is reduced.The oil content,chemical oxygen demand(COD)and solid suspended matter content(SS)in the water are significantly reduced over 99.5%,and the p H is not changed.Heavy metal elements are enriched in the solid phase,concentrated in the remaining sludge bottom slag after treatment,a small part migrates under the action of ultrasound and enters the liquid phase.(4)After ultrasonic treatment,oil droplets and solid particles in the sludge collide and aggregate to form large oil droplets and particle agglomerates;the emulsified oil breaks and separates from water;the surface structure of the particles changes,becomes smooth and flat,and the specific surface area becomes smaller;The solid agglomerates formed by the aggregation of the particles have a small pore size,pore volume and specific surface area,and the adsorption capacity to the liquid phase is lowered.The effect of ultrasonic on the microscopic morphology of the sludge and the solid particle structure makes the oil,water and solid in the sludge easier to separate and enhance the centrifugal treatment effect.