Claus plant preprocessing systems and methods for removal of ammonia from claus plant feed gases

摘要

Systems and methods for pre-treatment of acid gas are presented in which ammonium is removed from the acid gas in an absorber that is operated at significantly elevated temperature using dilute phosphoric acid. While seemingly incompatible, absorbing ammonia at high heat in the absorber will allow for production of a diammonium phosphate product that is ultra-low in residual sulfurous compounds and prevent crystallization of phosphate salts due to the increased solubility of the salts in the hot diluted solvent.

主权项

1. A method of pre-processing a feed to a Claus plant, comprising:
feeding an acid gas stream comprising sulfurous compounds, optionally carbon dioxide, and ammonia to an absorber, and contacting in the absorber the acid gas stream with dilute phosphoric acid to thereby form an absorber overhead product and an absorber bottom product; using a heat source to heat the absorber to thereby maintain a temperature of the absorber overhead product at ≧100° C.; wherein the absorber bottom product contains substantially none of the sulfurous compounds of the acid gas stream and more than 50% of the ammonia of the acid gas stream, and wherein the absorber overhead product contains substantially all of the sulfurous compounds of the acid gas stream and less than 50% of the ammonia of the acid gas stream; feeding the absorber overhead product to a Claus unit, and feeding the absorber bottom product to a downstream device.