After the organic waste gas containing methylene chloride enters the device, the compressor automatically runs and adapts the operating frequency to balance with the intake air volume. After the compression pressure is increased to 0.8 MPaG, the waste gas enters the precooler and is condensed in the precooler At 0°C, the partial pressure of steam of methylene chloride will greatly exceed its corresponding saturated partial pressure of steam and liquefy into liquid for recovery.

The condensation temperature of the secondary condenser is -30 ℃. The permeate gas in the membrane separator is rich in dichloromethane to achieve separation from air under the effect of pressure difference. After circulating compression, return to the workshop for reuse. The dichloromethane concentration in the residual gas is less than 60 ppm, and the non-condensable gas is mainly air. After the air is decompressed, return directly to the workshop for reuse.