METHOD OF TREATING GASES TO REMOVE TOXIC IMPURITIES Russian patent published in 2000 - IPC

FIELD: gas treatment. SUBSTANCE: process is conducted in cyclic mode, each of the cycles being composed of two steps. Absorption of toxic impurities from gas is first accomplished by passing gas through catalyst and maintaining temperature in the catalyst bed below oxidation point of toxic impurities in catalyst bed. Adsorbed toxic impurities are then oxidized by passing oxygen-containing gas alternately in forward and backward directions through catalyst bed heated to temperature above oxidation point of toxic impurities. In the beginning of this step, gas is heated in the central part of catalyst bed while changing its passage direction is changed when temperature 0 to 200 C is attained in catalyst bed cross- section situated at distance from gas outlet end of the bed equal to 0 to 30% bed length. When maximum temperature 200 to 800 C (superior to oxidation point of toxic impurities) is reached in catalyst bed cross- section situated at distance from gas outlet end of the bed equal 0 to 20% bed length, oxygen-containing gas is no longer heated and its passage direction is changed. EFFECT: increased degree of purification of emission gases. 7 cl, 10 ex