Solvent recovery - by activated carbon bed adsorption and desorption by membrane sepn. and condensation

摘要

A process to separate solvent contained in the outgoing air from lacquer spray cabins and to purify the waste air is based on the passage through activated carbon. The latter is regenerated by hot gas resulting in a desorption gas circuit which is conc. by a membrane sepn. The solvent is finally extracted by condensation. The waste air is passed through a slowly revolving rotor (2) with an activated carbon bed (3) which has a large adsorption zone (6) and a small desorption zone (7). The desorption gas is heated to 120-150 deg.C in two heat exchangers (19, 20). Cool air (8) from a blower (9) helps to cool the bed. The desorption circuit (10) passes through a membrane separator (11). The permeate gas circuit (15) loses the solvent by condensation in a freezing trap (25). ADVANTAGE - This causes no emissions because both desorption and permeate gas flows from closed loops.