GB701986A - An improved process for de-acidification of ammonia liquor by distillation - Google Patents

Abstract

<PICT:0701986/III/1> In a process of freeing ammoniacal liquor from hydrogen sulphide and carbon dioxide, without appreciable loss of ammonia, by submitting part of the liquor to distillation and passing the vapours through a fractionating column which is supplied at or near the top with the remainder of the (cold) liquor, the vapours are conducted in a multiple loop - like path through the lower stages of the column and the mean temperature of the liquor in these lower stages is maintained approximately constant between 70 DEG and 80 DEG C. The column shown comprises a boiler A, de-acidifier B, and a water-scrubber C. The middle and lower sections of de-acidifier B comprise five stages, separated by horizontal plates each containing five to seven bubble plates. Part of the ammoniacal liquor (about one-third) is introduced at 20 DEG C. through inlet C into the top of the de-acidifier B. The main bulk of the ammoniacal liquor is pre-heated and introduced through inlet a into boiler A, where it is heated, by indirect heating, to 95 DEG C. The vapours evolved are led through pipes b1 from stage 1 to stage 4 and from the latter, via stages 3 and 2, to stage 5; and a constant temperature between 70 DEG and 80 DEG C. is thereby maintained throughout stages 1 to 5. The last traces of ammonia are removed from the vapours leaving the top of the de-acidifier by passing them through scrubber C, which is supplied with water through inlet d. The scrubbing water is withdrawn through outlet f. In an example a liquor containing 13.0 grm./litre of NH3, 6.8 grm./litre of H2S and 3.0 grm./litre of CO2 is treated by the process to give a deacidified liquor containing 12.9 grm./litre of NH3, 0.4 grm./litre of H2S and 0.2 grm./litre of CO2.