The main purpose of chemical cleaning technology also called thermochemical separation is to realize oil, sludge and water three-phase separation. The advantages of chemical cleaning method are simple, low cost, high reliability and high oil recovery rate. It’s suitable for oily sludge with high oil content and light emulsification. The separation efficiency of chemical cleaning method is affected by the type and dosage of reagent, washing temperature, liquid-solid ratio, stirring intensity, stirring time and pH value.