Recovery of high purity ammonia and hydrogen sulfide from ammonium sulfides

Abstract

Abstract PROCESS EFFLUENT SOLUTIONS COMPRISING AQUEOUS HYDROGEN SULFIDE AND AMMONIA ARE TREATED TO RECOVER THE AMMONIA ESSENTIALLY FREE OF HYDROGEN SULFIDE IMPURITY. HYDROGEN SULFIDE IS FIRST STRIPPED FROM THE SOLUTION AND RECOVERED ESSENTIALLY FREE OF AMMONIA. AMMONIA IS THEN STRIPPED FROM THE AQUA AMMONIA BOTTOMS OF THE HYDROGEN SULFIDE STRIPPING OPERATION AND IS REMOVED AS AN OVERHEAD STREAM TOGETHER WITH WATER VAPOR AND SOME HYDROGEN SULFIDE IMPURITY. THE OVERHEAD STREAM IS FIRST COOLED SOMEWHAT TO CONDENSE A PORTION OF ITS WATER VAPOR CONTENT WHICH RETURNS TO THE AMMONIA DISTRILLATION AS REFLUX. THE REMAINDER OF THE OVERHEAD STREAM IS THEN FURTHER COOLED TO EFFECT TOTAL CONDENSATION AND TO REACT SUBSTANTIALLY ALL THE HYDROGEN SULFIDE IMPURITY WITH AMMONIA TO FORM NH4SH OR (NH4)2S SALTS, FOLLOWED BY FLASH VAPORAZTION WITH ACCOMPANYING AUTOREFRIGERATION. AT THE AUTOREFRIGERATION TEMPERATURE THE VAPOR PRESSURE OF THE SALTS IS SUBSTANTIALLY NIL SO THAT THE AMMONIA OVERHEAD OF THE FLASHING STEP IS ESSENTIALLY FREE OF HYDROGEN SULFIDE. THE AQUEOUS RESIDUE OF THE FLASHING STEP CONTAINING THE SALTS IS RECYCLED TO THE HYDROGEN SULFIDE DISTILLATION.

Inventors

• 👤 Nicholas E Kaparakos

Bibliographic Details