SINGLE EXPANDER AND A COLD COMPRESSOR PROCESS TO PRODUCE OXYGEN

摘要

In a process for the cryogenic distillation of air in a distillation column syst em that contains at least one distillation column wherein the boil-up at the bottom of t he distillation column producing the oxygen product is provided by condensing a str eam whose nitrogen concentration is equal to or greater than that in the feed air st ream, which comprises the steps of: (a) generating work energy which is in excess of t he overall refrigeration demand of the distillation column system by at least one o f the following three methods: (1) work expanding a first process stream with nitrogen content equal to or greater than that in the feed air and then condensing at least a por tion of the expanded stream by latent heat exchange with at least one of the two liquids: (i ) a liquid at an intermediate height in the distillation column producing oxygen product an d (ii) one of the liquid feeds to this distillation column having an oxygen concentration e qual to or preferably greater than the concentration of oxygen in the feed air; (2) condens ing at least a second process stream with nitrogen content equal to or greater than tha t in the feed air by latent heat exchange with at least a portion of an oxygen-enriched l iquid stream which has oxygen concentration equal to or preferably greater than the concentration of oxygen in the feed air and which is also at a pressure greater than the pressure of the distillation column producing oxygen product, and after vaporiza tion of at least a portion of oxygen-enriched liquid into a vapor fraction due to latent he at exchange, work expanding at least a portion of the resulting vapor stream; and ( 3) work expanding a fraction of the feed air; (b) using the work which is generated in e xcess of the refrigeration need of the distillation column system to cold compress a proc ess stream at a temperature lower than the ambient temperature.