PURIFICATION OF CARBON DIOXIDE

摘要

Impurities that are less volatile than carbon dioxide, e.g. hydrogen sulphide, are removed from crude carbon dioxide by processes involving sub-ambient distillation of said crude carbon dioxide in a distillation column system operating at super-atmospheric pressure(s) to produce carbon dioxide-enriched overhead vapour and bottoms liquid enriched with said impurities. Where such processes involve at least one heat pump cycle, significant savings in power consumption are realised when the process uses more than one recycle pressure in the heat pump cycle(s).