Conventional liquid air separation plants are cooled by isothermal throttling refrigeration and expander refrigeration, LNG cold energy air separation eliminates the need for an expander and utilises the cooling capacity of LNG and isothermal throttling refrigeration. The air separation unit uses circulating nitrogen gas to liquefy into liquid nitrogen in a liquefier, which is fed into the lower tower, where the cold is transferred to the distillation system to pump the dirty liquid nitrogen through the lower tower. The liquid-depleted air allows the air separation unit to recover the low temperature cold energy of the liquid air separation plant by liquefying the raw air in the liquefier without reducing the extraction rate due to the liquefaction of part of the raw air, and the cold energy of the liquid air separation plant is utilised in stages, resulting in a significant reduction in electricity and water consumption compared to conventional liquid air separation units. The liquid nitrogen liquefies the air through the liquefier and transfers the cold to the fractionation tower system, eliminating the leakage of methane to the fractionation system and making the separation unit safe. the liquid air separation plant is gradually heated up and vaporised in the high pressure heat exchanger, transferring the low temperature cold to the nitrogen, but not reheating to room temperature. the high temperature cold can be recovered through a suitable refrigerant and can be used for intermediate and final cooling of the air compressor.
The conventional liquid air separation plants designed and produced by Dear Air have been well received by our customers.
