| 摘要 |
PURPOSE:To easily change preferential sampling of oxygen or argon by introducing feed air in each fractionating stage allowing the feed air before being introduced in a composite fractionator to branch to increase or decrease to the pressure corresponding to the pressure of the upper tower of the composite fractionator. CONSTITUTION:In the case where an oxygen gas (GO) is sampled preferentially, a valve 25 of a lower introduction passage is opened while a valve 26 of an upper introduction passage 24 is closed and feed air (At) expanded and contracted in an expansion turbine 5 is allowed to introduce in approximately the same fractionating stages as the tower gas phase composition of an upper tower 6 is air composition. In addition, in the case where argon (Ar) is sampled preferentially, the valve 26 of the upper introduction passage 24 is opened while the valve 25 of the lower introduction passage 23 is closed and the feed air (At) expanded and contracted in the expansion turbine 5 is introduced in a fractionating stage of nitrogen-richer composition than the gas phase of the upper tower 6 is air composition, namely, introduced upward of the fractionating stage for introducing at the time of said oxygen sampling priority. Thereby, argon thickened in the neighborhood of an introduction stage for an argon tower 8 can be prevented from being diluted with a large quantity of the feed air (At) and a yield of argon (At) can be improved. |
