FIELD: chemical industry. SUBSTANCE: flue gases may contain SO2 which is kept from escaping into the atmosphere, oxidized into SO3 and condensed by aqueous vapors to vapor-like H2SO4 which is condensed in vertical externally-cooled glass tubes. Condensate is accumulated in the lower parts of the tubes. The cooling process produces a mist consisting of minute H2SO4 drops which tend to escape into the atmosphere. The stipulations regarding the environment impose evergrowing demands on reducing the amount of such escaping mist. The method involves passing the gas through an aerosol filter having a gas-tight connection with the upper part of the tubes. Such a filter can be made from acid-resistant fibers or threads 0.04-0.7 mm thick which may be arranged so as to ensure a pressure drop below 20 mbar. Besides, sulfuric acid trapped by the filter must flow through the tube against the flow of delivered gas. The description submits various embodiments of filters and filter materials. EFFECT: recovery of high-purity concentrated sulfuric acid. 4 dwg, tbl
