Patent ID: 6889524

Claim:
A process for the temporary supply of a back-up quantity of a “first” gas, during the time taken for a vaporizer in a main back-up system to come fully on-line, maintain the level of production of the first gas from a cryogenic separation of a gaseous mixture comprising the first gas and at least one other gas in the event of reduction in the level of production of said first gas from the separation, said separation comprising: separating the mixture, or a mixture derived therefrom, in at least one cryogenic distillation system to produce liquefied first gas, the or each system retaining a portion of said liquefied first gas as inventory; and vaporizing further portion of said liquefied first gas by indirect heat exchange against a process stream in at least one heat exchanger to produce said first gas; said process comprising, in the event of reduction in the level of production of said first gas from the separation, withdrawing liquefied first gas inventory from the or at least one of said cryogenic distillation systems and vaporizing the withdrawn liquefied first gas inventory to produce said back-up quantity of first gas, wherein at least a portion of the vaporization duty required to vaporize said withdrawn liquefied first gas inventory is provided by heat inventory from the or at least one of said heat exchangers.