Degreaser science to set screw separation, pre filtering and condensing type fine filtration tertiary purification is an organic whole, can be effective in addition to water, oil removal, dust filtering, to shorten the purification process of compressed air, then through post-processing of the precision filter, the filtering precision can reach 0.1 um, residual oil content can be less than 0.03 mg/Nm3, air purification quality get the reliable guarantee.