| 摘要 |
Argon is recovered from a tail gas stream remaining after recovery of hydrogen values from ammonia synthesis purge gas. In a first step, tail gas is cooled, preferably in a first heat exchanger then a refluxing exchanger, to separate a condensate containing methane, argon and some nitrogen and uncondensed gas containing substantially all residual hydrogen and some nitrogen. The condensate, after expansion, is fed into a first distillation column where methane is condensed, the overhead nitrogen and argon product being fed to a second column where argon product is condensed. The cold requirements of the process and heat for reboil and cooling for reflux for the columns are provided by an open cycle supplied with gaseous nitrogen from the second column as heat transfer fluid. Cooling for the refluxing exchanger is provided by an evaporating coolant comprising transfer fluid combined with the uncondensed nitrogen-hydrogen gas after expansion thereof.
|
