Research And Application Of Purification And Recovery Technology Of Highly Emulsified Waste Oil

Emulsified waste oil can be produced in transportation pipeline pigging,oil storage tank cleaning,sewage treatment and oil recovery as well as device maintenance in petroleum industry.The composition of emulsified sewage oil is complex,and its properties vary greatly due to different sources.The three-phase emulsification of oil,water and solid is serious,and it is difficult to separate and purify.This thesis takes the highly emulsified slop oil produced in the production process of a refinery in South China as the research object.By analyzing its basic composition and emulsifying characteristics,the appropriate demulsification method was found out,and the demulsified waste oil was further purified to meet the requirements of refining.The demulsified mud water phase and centrifugal slag phase were mixed deeply to remove oil,and then the demulsified oil was put into the "three mud" treatment device for further treatment.Finally,a set of 400 L/h highly emulsified sewage oil purification and recovery sideline test device is constructed,and the technical feasibility is verified through field tests.The results show that:(1)highly emulsified sewage oil is W/O emulsion,with oil content of 38.48～60.95%,solid content of 0.97～2.02% and water content of 37.21%～59.56%;Among them,the saturated and aromatic fractions of the four components of oil phase are relatively high,reaching 44.25% and 25.50%,respectively.The absorption peak of saturated alkanes is obvious,the ratio of hydrogen to carbon is 1.78,and the content of sulfur and nitrogen is low,which has good reuse value.The average proportion of colloid and asphaltene is 9.66% and 20.59%,respectively.The viscosity and emulsification stability of waste oil are greatly increased;The solid particles in the emulsified sewage oil are mainly fine particles,mainly composed of Fe,Si and Al elements,with an average particle size of 16.28 μm,which are easy to emulsify with asphalt and water.Solid particle components have a certain degree of lipophilicity,easy to be wettable by oil.After ultrasonic treatment,solid particle lipophilicity is weakened,hydrophilicity is enhanced,and it is easier to achieve demulsification effect.(2)Laboratory research used ultrasonic-assisted chemical reagents to break demulsification of highly emulsified waste oil.When the demulsification temperature is70℃,the demulsifier is oil-soluble YT-PE-02 type demulsifier,and the dosage is 0.5%,the best demulsification effect is obtained when the ultrasonic power is 80%,the ultrasonic frequency is 80 k Hz,and the ultrasonic time is 30 min;After demulsification,the waste oil is further purified by centrifugation.When the centrifugation temperature is 70℃,the centrifugal speed is 8000 r/min and the centrifugation time is 30 min,the water content of the purified oil is less than 0.15%,the ash content is less than 0.5‰,and the salt content is less than 20 mg/L,all of which meet the requirements of refining;after demulsification,the mud water phase is mixed with the centrifugal residue,and 2.5g/L deep degreaser can make the oil content of the mixed sample less than 1%,which meets the acceptance requirements of the refinery’s "three mud" treatment device.(3)The 400 L/h side line test device runs stably for 37 days continuously under the best conditions.The total operating cost is about 140 yuan/t waste oil.After purification,the purified oil reaches the quality of crude oil,with water content less than 0.1%,ash content less than 0.5‰,salt content less than 30 mg/L and oil recovery more than 98%.After deep oil removal treatment,the sludge water phase oil content is less than 1%,which can be further treated in the refinery "three mud" treatment device,which verifies the feasibility of the process.It not only effectively solves the problem of emulsified waste oil disposal in the refinery,but also brings good economic benefits,which is of popularization significance.