超临界CO_(2)萃取与白土精制相结合再生废润滑油

Supercritical CO_(2) extraction combined with clay refiningto regenerate waste lubricating oil

建立了一套半连续式超临界CO_(2)萃取装置,开展车用废润滑油再生研究,通过Box-Behnken响应面设计法,对各因素进行二次回归拟合,得到3组关于萃取率、通光率和酸值的多项式模型,结合模型的方差分析,优化条件后得到最优萃取条件:萃取压力为16 MPa,萃取温度为45℃,萃取时间为47 min。在该条件下,废润滑油再生萃取率为71.1%,通光率为92.1%,酸值(以KOH计,下同)为2.5 mg/g。添加质量分数为25%的活性白土,在125℃条件下以300 r/min的搅拌速率精制40 min,离心过滤后得到精制润滑油。精制后润滑油的密度(20℃)为0.8355 g/cm^(3),运动黏度(100℃)为5.6 mm^(2)/s,闪点为213℃,酸值为0.02 mg/g,机械杂质和水分质量分数均为痕迹,硫元素质量分数为0.08%,满足GB 11121—2006《汽油机油》标准。

A set of semi-continuous supercritical carbon dioxide extraction device was built to carry out the study of automotive waste lubricating oil regeneration.Three sets of polynomial models about extraction rate,transmittance and acid value were obtained by Box-Behnken response surface design method with quadratic regression fitting for each factor.As a result,the optimal extraction was carried out at the pressure of 16 MPa,temperature of 45℃and 47 min.Under these conditions,the extraction rate of waste lubricating oil was 71.1%,transmittance is 92.1%and the acid value(in terms of KOH,the same below)was 2.5 mg/g.The lubricating oil was refined at 125℃for 40 min with a stirring rate of 300 r/min by adding 25%of active white clay and subsequently filtered by centrifugation to obtain the refined oil.The refined lubricating oil has a density of 0.8355 g/cm^(3) at 20℃,a kinematic viscosity of 5.6 mm^(2)/s at 100℃,a flash point of 213℃,an acid value of KOH 0.02 mg/g,traces mechanical impurities and water,and the mass fraction of sulfur as 0.08%,which meets the standard of“Gasoline Engine Oil”(GB 11121-2006).