Solvent is purified from liquefied petroleum gas,its main components are propane,butane,boiling point are below 0℃.Subcritical oil extraction equipment in the extraction process is in a certain pressure(0.1~0.7 MPa for liquid)and room temperature,to achieve normal temperature oil extraction.Solvents in meal and crude oil are removed under low temperature and vacuum condition,and the solvent is liquefied and recycled.Brief description of production flow chart and process flow(see figure 1).

（Figure 1）

　　E201 condenser,P201 solvent pump,P202 finished product pump,P203 vacuum pump,P204 compressor,V201 extraction tank,V202 mixed liquid temporary storage tank,V203 evaporation tank,V204 solvent tank,V205 buffer tank
　　The process is as follows:
　　1.Load oil into extraction tank V201.
　　2.Solvent pump P201 will inject No.4 solvent into the extraction tank to soak the oil.
　　3.The solvent pump P201 extracts the mixed oil from the extraction tank and pumps it into the evaporation tank V203.
　　4.Connected extraction tank and compressor P204 suction port,the residual meal dissolved gasification,into the compressor,after compression,condenser E201 condensation and liquefaction,solvent back to solvent circulation tank V204,recycling for use.Meal extraction and leaching system.
　　5.the mixed oil into the evaporation system,the solvent after evaporation and oil separation.The solvent vapor is compressed and liquefied and then recycled.Raw oil discharge and leaching system.
　　Process conditions:
　　The extraction temperature was 35℃,the extraction pressure was 0.4~0.7MPa,and the extraction times were 3~5 times(depending on the oil content).The concentration of mixed oil is 15~25%,the temperature is 30~35℃,the evaporation temperature of mixed oil is 45~60℃,and the vacuum degree of the mixed oil is-0.095 MPa.The desolvation temperature of meal was 45℃,and the desolvation pressure was-0.085MPa.The residual solvent of crude oil was less than 30ppm,and the residual solvent of meal was less than 50ppm.