GB903822A - Improvements in and relating to the production of ammonium sulphate - Google Patents

Abstract

Ammonium sulphate and sulphur are obtained from flue gas washing liquor containing ammonium sulphite and bisulphite by addition of sulphuric acid, passing the mixture through a preheater and thence to the reaction zone of a reactor wherein part of the reacted liquor is returned to the inlet of the reaction zone and mixed with the fresh liquor so as to maintain the proportion of acid to reactants. The amount of sulphuric acid required in the liquor may be 0,147 gram molecules per litre and the proportion of acid returned to the inlet 0,1 gram molecules per litre. The preheater may be at 150 DEG C. and the pressure in the reaction zone between 150 and 200 p.s.i. The liquor enters the steam-heated preheater coil 26 through conduit 51 and then to the reaction vessel 11 of the type described in Specification 903,821. It enters reaction tube 30 through Venturi 33, which causes a reduction in pressure at the throat and hence liquor from space 31 is sucked down into tube 30. The liquor circulates up through return tubes 36 back to <PICT:0903822/III/1> space 31 and mixes with fresh liquor. The excess liquor which is not returned flows over baffle 37 and out through conduit 29. Large sulphur globules follow this latter course while small globules tend to be recirculated until they grow larger. The whole of the reaction apparatus is provided with a steam jacket. The reacted liquor and sulphur pass through a steam jacket 47 to keep the sulphur molten, and into a sulphur separator 12. The ammonium sulphate liquor and sulphur flow over cone 46 and the sulphur sinks to the bottom of the vessel, which is provided with a steam jacket. Sulphur is removed via conduit 41 and ammonium sulphate liquor via conduit 44. Specification 852,024 also is referred to.