GB768830A - Method of working up aqueous liquors containing ammonia - Google Patents

Abstract

768,830. Distilling ammoniacal liquors. METALLGES AKT.-GES. April 29, 1955 [May 3, 1954], No. 12543/55. Addition to 733,796. Class 32 [Also in Group XII] In a method of extracting ammonia from aqueous liquors containing phenols, ammonia, carbon dioxide, hydrogen sulphide and possibly other organic or inorganic substances, as described in the parent Specification, the heat of the ammoniacal vapours produced when the ammonia is driven off from the liquors is used before treating the vapours with acid for the purpose of stripping the ammonia from the liquors. As shown, ammoniacal liquor, which has been dephenolized by extraction with oxygencontaining organic solvents which are insoluble or only slightly soluble in water and which have a lower boiling point than the phenols, is passed through pipe 1, heat exchanger 2 and pipe 3 into plant 4 in which the solvent residue is stripped from the liquor. The liquor passes through pipe 6, heat exchanger 7 and pipe 8 to stripper 9 the mixture of water vapour and ammonia passing therefrom through pipe 10 compressor 11 and pipe 12 to an evaporator 13. Here the vapour mixture gives up heat to produce water vapour whilst a part of the vapour mixture condenses. The remaning vapour passes through pipe 14 to a saturator 15 wherein the ammonia is reacted with sulphuric acid to form ammonium sulphate which is removed at 16. Gases and vapours, such as carbon dioxide and hydrogen sulphite, are returned through pipe 51 to plant 4 leaving the latter at 5. The condensate formed in evaporator 13 flows through pipe 17, container 18, pump 19 and pipe 20 as reflux to column 9. From the sump of column 9 water freed from ammonia passes through pipe 21 to evaporator 13, the water vapour produced therein passing through pipe 22 into column 9. Additional steam may be supplied at 23. Another part of the ammonia-free water passes from column 9 to the heat exchangers 2 and 7. In a modification vapour mixture from the stripper passes directly to an evaporator the steam generated therein flowing to the stripper through a compressor which may be operated by steam which is also supplied to the stripper. In modifications a turbo-compressor, piston compressor, or blower are used. Fresh water, cooling water or condensate may be passed to the evaporator instead of using water from the sump of the stripper.