PURPOSE: To maintain the constant removing effect of corrosive gas without influence of the change of relative humidity by mixing corrosive gas in an industrial zone, etc. with ozonized air generated from dry, cleaned air, and subjecting is to be adsorbed by active carbon in a highly oxidized condition.
CONSTITUTION: An active carbon filter 12 that cleans the air to be processed is provided in the front part of a conduit 11 for corrosive gas, and a similar active carbon filter 13 is provided in the rear part of the conduit, and an opening of a mixer 18 that mixes ozonized air is provided between the two filters. Insufficiently oxidized corrosive gas not adsorbed by the filter 12 is oxidized in higher order by mixing with ozonized air, and adsorbed by the second stage filter 13 and removed. Thus, completely purified air is obtained. In the passage 14 of ozonized air, the purified air that comes out from the active carbon filter 13 is circulated by a pump 15. The efficiency of generation of ozonized air can be increased by providing a drying agent column before the ultraviolet lamp 16 for generation of ozone and irradiated part 17 and passing dried air. Thus, high efficiency of removing of corrosive gas can be maintained.
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