GB871207A - Process and apparatus for recovering ammonia - Google Patents

Abstract

<PICT:0871207/III/1> Ammonia is recovered from ammonia-containing gas by scrubbing the gas with a solution of ammonium bicarbonate to absorb the ammonia and saturating the resulting scrubbing solution with CO2 to precipitate NH4HCO3 which is recovered. Gases containing ammonia, e.g. coke oven gases, enter the base of chamber 1 and are scrubbed therein by contact with ammonium bicarbonate solution entering through conduit 13 and leaving through 7. Residual effluent gases exit chamber 1 through conduit 5 and pass through chamber 6 where they are contacted with fresh water which removes final traces of ammonia therefrom, the washing water being fed into conduit 7 as compensation for the water lost in the plant due to evaporation or reaction in forming bicarbonate. Scrubbing solution containing excess ammonia passes through conduit 7, in which filter 8 is provided to remove any traces of iron oxide which may be present, to chamber 2 where it is contacted with gaseous CO2, extracted say from smoke fumes, entering through distributer 9. Residual CO2 and any H2S formed is passed from the chamber by a conduit at the top thereof the CO2 being recovered and recycled if desired. Ammonium bicarbonate crystals precipitated during the CO2 treatment settle in hopper 10 at the bottom of chamber 2 from whence they are removed through valve 11 and passed to a drying device 12 where they are dried and recovered. The ammonium bicarbonate solution remaining in chamber 2 may be returned as scrubbing solution through return conduit 13.