Compression condensation membrane separation, condensation recovery and membrane control

    VOCswaste gas treatment, a single process is often at the expense of one another. Condensation can recover solvents, but it is limited by vapor–liquid equilibrium, leaving residual concentrations in the off-gas that often fail to meet environmental protection standards. The membrane separation method can concentrate efficiently, but it cannot directly liquefy the solvent. The combined process of compression condensation membrane separation couples the two gradients to form a division of labor mode of "condensation is responsible for recovery and membrane separation is responsible for gatekeeping.

The first half of the process solves the problem of recycling. The exhaust gas enters the three-stage condensation unit after being pressurized by the compressor. The temperature drops from normal temperature to minus 15 to minus 25 degrees Celsius. The organic solvent above 90% in the exhaust gas is directly liquefied from gaseous state to liquid solvent, which flows out of the collection tank with a purity of more than 90% and is directly reused for production.

The second half of the process solves the problem of reaching the standard. After condensation, the tail gas still carries a small amount of unliquefied organic matter, usually in a concentration of several hundred to several thousand milligrams per cubic meter. This portion of the gas enters the membrane separation unit.gas separation membraneIt has selective permeation characteristics for organic molecules. VOCs preferentially permeate the membrane layer to form concentrated gas, which is sent back to the front end of condensation for circulation treatment. The concentration of VOCs in the untreated gas can be reduced to less than 50 milligrams per cubic meter.

Compared with single condensation or single membrane separation, this combined process integrates the recovery value and the standard discharge in the same system. Condensed solvent recovery creates economic benefits, and membrane separation controls emissions to ensure safety and compliance. Suitable for chemical storage tank area, pharmaceutical dichloromethane exhaust gas, printing ethyl acetate recovery and other high concentration, recovery value of VOCs exhaust gas scene.