Continuous solvent recovery from air-cleaner adsorption towers - by switching air flow through four towers with associated microwave heaters and vacuum pumps

摘要

Discharged air contaminated by solvent is continuously purified and the solvent recovered with a set of four towers filled with adsorption medium, and coupled in two pairs (1, 2 and 3,4). A blower directs the laden air in succession through the first tower of each pair. At the head of these first towers a sensor (5) records the increasing moisture content which corresponds to increasing solvent build-up in the second of each pair. When absorber satn. in the first towers is recorded, three-way valves switch the air flow to the second tower of each pair. Adsorbed moisture is extd. by cleaned dried air in conjunction with a first vacuum pump (8). Similar moisture sensing for the other pair of towers controls further switching of the three-way valve. Adsorbed solvent is vaporised by applicn. of a microwave heater (15) to the towers involved, and extd. by a further vacuum pump (9) for collection and re-use. ADVANTAGE - Normal commercial active carbon adsorbent is desorbed and the solvent recovered without requiring any third medium as thermal desorbent.