The air separation column mainly includes main heat exchanger, liquefier, distillation column, condensing evaporator, etc. The main heat exchanger, condensing evaporator and liquefier are plate type of heat exchangers. It is a new type of all aluminum metal composite partition heat exchanger. The average temperature difference is small, and the heat exchange efficiency is as high as 98-99%. Distillation column is the unit of air separation. The types of column unit are classified according to the internal parts. The sieve plate column with sieve plate, the bubble cap column with bubble cap plate, and the packed column with packing material. The sieve plate is widely used in air separation distillation column because of its simple structure, easy manufacture and high efficiency. Packed column is mainly used for distillation column with diameter less than 0.8m and height less than 7m. Bubble column is seldom used because of its complicated structure and difficult manufacture.
Turbine expander is a rotating blade machine used by nitrogen generator to produce cold energy. It is a gas turbine used at low temperature. According to the flow direction of gas in the impeller, the turbine expander is divided into axial flow, radial radial flow and radial axial flow. According to whether the gas continues to expand in the impeller, it is divided into counterattack and impulse. Single stage radial axial flow counter attack turbine expander is widely used in air separation unit.
Low temperature air separation nitrogen production unit is complex, covers a large area, high infrastructure cost, one-time unit investment is large, operation cost is high, gas production is slow, installation requirements are high and cycle is long. Low temperature air separation nitrogen production unit is suitable for large-scale industrial nitrogen production, but it is not economical in small and medium-sized nitrogen production. For the unit less than 3500Nm³ / h, the investment scale of PSA unit with the same specification is 20% - 50% lower than that of cryogenic air separation unit.
