| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to avoid the contamination of ultrahigh pure product by gathering ultrahigh pure fluid product at the bottom of a distillation column, reboiling it by the heat exchange with low purity composition of the same composition as that of the product, and evaporating the low purity composition by the heat exchanger with the impure fluid. SOLUTION: A reboiler 10 has the indirect heat exchange relation with ultrahigh pure oxygen fluid 8 gathered in the sump of a distillation column 30. The heat for evaporating at least the part of ultrahigh pure oxygen product 8 is provided by the oxygen 6 vapor of the class sold in the market to be transported to the reboiler 10 via a conduit 26. The oxygen 6 of the class sold in the market is evaporated in the separated zone disposed under the reboiler 10, and heat is input to the reboiler 10. The condensed oxygen 6 of the class sold in the market is fed via a conduit 27, and heat is input by warm circulating nitrogen 22 in a second reboiler 20. Thus, even if leakage occurs in the reboilers 10, 20, the substantial contamination of the product 8 is not introduced.
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