CRYOGENIC DISTILLATION METHOD AND APPARATUS FOR PRODUCING PRESSURIZED AIR BY MEANS OF EXPANDER BOOSTER IN LINKAGE WITH NITROGEN EXPANDER FOR BRAKING

摘要

Provided are a method and apparatus for producing nitrogen and oxygen by means of cryogenic distillation of air. Nitrogen products are extracted only from the top of a tower (11). If a customer needs nitrogen with lower pressure, part of pure nitrogen (124) which is partially located at a first nitrogen product pressure is reheated in a main heat exchanger (1), then decompressed to a second nitrogen product pressure by means of a nitrogen expander (23), further reheated by means of the main heat exchanger (1), and output as a low-pressure nitrogen product. The nitrogen expander (23) can be braked by an expander booster (24) for compressing air. By means of the method, nitrogen with different pressures can be suitably produced, and moreover, the energy consumption for producing the pressurized air can be reduced by utilizing the expansion work of nitrogen.