| 摘要 |
Air is compressed in an air compressor and cooled in an air cooler whereafter the impurities which have condensed out are removed. The air is subsequently reheated in a heat exchanger which is connected on the hot air side between the air compressor and the air cooler. The reheated air is passed through a plurality of membrane-type nitrogen separators, whereby the permeate of the last separator is constituted by nitrogen of the desired purity. The concentrate of this separator is recirculated to the suction side of the air compressor. The output control of the apparatus can be effected by means of an air feedback line which branches off before the heat exchanger and leads to the suction side of the air compressor. The flow through the air feedback line can be controlled by a valve which operates in dependence on the outlet pressure of the air compressor.
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