Regeneration Of Used Lube Oil By Solvent Technology

Solvent extraction-flocculation and solvent extraction were used to regenerate used lubeoil. In the solvent extraction-flocculation part, both single solvents including1-butanol andbutane and complex solvent composed of iso-propane and n-hexane were chosen to re-refineused lube oil. Influence of factors such as solvent oil ratio and temperature on sludgeproperties, sludge weight, recovered oil yield and properties was studied, in which propertiesincluding acid number, Ca concentration, Mg concentration, Zn concentration. Afterward,firstly recovered oil was treated by several solvents to obtain the best solvent for extractionfrom which the experiment results indicated NMP as the best one. During this step, influenceof factors including solvent oil ratio and temperature on recovered oil yield and propertieswas studied, herein properties including acid number, absorption, Ca, Zn, Mg concentration.During the solvent-flocculation part, results indicated that1-butanol was the best singlesolvent. Under the best conditions while solvent oil ratio=3:1, T=30℃, the recovered oil yieldwas87.0%, acid number decreased by71.2%, Ca, Zn, Mg concentration dropped by83.7%,63.0%,73.0%respectively compared to raw material. While the best complex solventcomposition (by weight) could be used oil: n-hexane: iso-propane=2:1:7, best temperaturewas30℃, recovered oil yield under such condition was76.8%, acid number dropped by84.6%, Ca, Mg, Zn concentration dropped79.7%,77.6%,76.2%individually compared toraw material.During the solvent extraction step, NMP was chosen to re-refine the firstly recovered oiltreated by n-butanol. As oil yield and oil properties such as acid number and metalconcentration et al. contradicted with each other, the relatively better condition was defined as:solvent oil ratio=3:1, T=60℃, recovered oil yield under such condition was73.2%, comparedwith n-butanol treated oil under the best condition, acid number of secondary recovered oildecreased by81.0%, Abs decreased by88.7%, Ca, Mg, Zn concentration dropped by76.2%,80.0%,78.9%respectively.