CNG acid gas removal process isolates environmental contaminants from crude coal gas

Carbon dioxide, hydrogen sulfide, carbonyl sulfide, and numerous other undersirable contaminants, can be effectively removed from crude coal gas by current acid gas removal (AGR) technology. However, the separation of absorbed acid gases from the AGR absorbent, and the simultaneous or subsequent sharp separation of sulfur-containing compounds and other contaminants from carbon dioxide which is necessary to prevent objectionable environmental emissions, are difficult to achieve with existing AGR technology. The CNG AGR Process described here concentrates absorbed acid gases and other contaminants, and regenerates pure AGR absorbent, by triplepoint crystallization of carbon dioxide.