Ceramic kiln off-gas cleaning - using adsorption and catalytic oxidn. appts. with high temp. by=pass channel, which is protected against catalyst poisoning

摘要

(A) in the cleaning of off-gas from ceramic firing kilns by adsorption of inorganic matter in an adsorber honeycomb and subsequent catalytic oxidn., the off-gas is passed at 50-400 deg.C successively through an adsorber honeycomb, an electric heater and a honeycomb catalyst but, when at a higher temp., is passed through a by-pass line. Appts. for carrying out the process consists of a channel, contg. the honeycombs and the electric heater, and a parallel by-pass channel having an inlet flap which is electrically actuated by a thermocouple. The adsorber honeycomb is pref. coated with Na2CO3. The electric heater pref. comprises catalyst-coated heating wires. The catalyst honeycomb is pref. coated with successive layers of LaCoO3 with excess rare earth and a mixt. of Al2O3 and precious metal, pref. Pt. ADVANTAGE - The appts. is protected against overheating and poisoning of the catalyst.