Research On Key Technologies Of Waste Engine Oil Purification

With the increasing number of automobile ownership,the treatment of waste engine oil has become a significant part of resource conservation and environmental protection.Based on the analysis of the physicochemical properties of waste engine oil samples and other aspects,a combined process of waste oil treatment combined with inorganic ceramic membrane filtration and biomass-clay two-stage adsorption was proposed in this paper.Simultaneously,the clay regeneration process was analyzed to recycle the waste clay.The research results provide a new idea for the treatment of waste oil produced in the production,transportation and use of petroleum products and the regeneration of clay.In the combined process of waste engine oil treatment,firstly,some large particles of mechanical impurities,moisture,and light components in waste engine oil were separated by thermal sedimentation pretreatment(80°C,12h)and vacuum distillation(70°C).The effects of operating temperature and pressure on membrane filtration flux and the membrane with different pore sizes on the physicochemical properties of recycled oil were studied.The optimal process conditions of the membrane separation process were determined as follows: operating temperature 80°C,operating pressure 0.095 MPa,and inorganic ceramic membrane pore size0.2μm.The experimental results showed that most of the impurities,such as colloids and asphaltenes,were removed from the oil.Subsequently,in the biomass-clay two-stage adsorption experiment,the waste sawdust from the factory was used as raw material to prepare biomass adsorbent through KOH activation.The optimal activation conditions were determined as follows: activation temperature 800°C,activation time 1h,and mass ratio of KOH to sawdust3:1.The biomass adsorbent and clay were used in combination to adsorb and refine the oil after membrane separation.By analyzing the influence of process conditions of biomass adsorption and clay adsorption on the transmittance of regenerated oil,the optimum process parameters of the two-stage adsorption process were determined as follows: biomass dosage 6%,adsorption temperature 120°C,adsorption time 50 min,white earth dosage 4%,adsorption temperature85°C,adsorption time 30 min.By comparing with the regenerated oil obtained by adsorption of clay alone,it was found that the treatment effect of two-stage adsorption was better,which reduced the usage amount of clay and the cost of treatment.The indexes of regenerated oil obtained through the whole process were determined.The results show that the waste engine oil was close to the new oil by this combined process,and the recovery rate was about 79%.In the study of clay regeneration,firstly,according to the principle of chemical similarity dissolution,the light oil from the distillation process of waste oil was used as the oil extraction solvent,and the effects of different process parameters on the residual oil rate of waste clay were analyzed.The optimum process conditions of oil extraction were determined as follows:the mass ratio of clay to extraction solvent was 1:1.5,the extraction temperature was 60°C,the extraction time was 40 min,and the extraction times were 3.Secondly,the de-oiled waste clay was acid-washed to obtain regenerated clay,and the mixture was separated by the dehydration heat exchanger independently developed by the laboratory.By analyzing the influencing factors of decolorization rate of regenerated clay,the optimal process conditions of the pickling were determined as follows: sulfuric acid concentration of 8%,the mass ratio of sulfuric acid solution to the clay of 2:1,pickling temperature of 100°C,pickling time of 2h,and pickling times of 1time.The results showed that the residual oil rate of regenerated clay was less than 3%,and the decolorization rate was 92.2%.By comparing the treatment effects of regenerated clay and fresh clay on waste oil under the same conditions,it can be seen that regenerated clay can be recycled in the system.The regeneration process proposed in this paper avoids solvent waste and environmental pollution caused by conventional solvent extraction methods and saves the cost of extraction solvent.