Liquid air separation units

The load regulation range of low pressure air separation unit is related to the regulating performance of feed air compressor, the regulating performance of expander and the structural characteristics of distillation column. At present, the flow regulation range of turbine air compressor with inlet guide vane is 75% to 100%, and that of turbocharged expander with adjustable nozzle is 65% to 100%. Next, the most important thing is to adjust the residual of the distillation column. At present, the load regulation range of distillation column with structured packing can reach 50% - 100%, while that of traditional sieve tray column is 70% - 100%. If the load is too low, it will cause liquid leakage because the speed of steam passing through the sieve is too slow. When oxygen is sufficient and the oxygen output needs to be reduced, first reduce the output of oxygen products, then reduce the air flow accordingly, and adjust the expansion air volume according to the main cooling level. The

In the distillation column of air separation, the air is usually pre separated in the lower column, and then distilled into oxygen rich liquid air and pure nitrogen, and then further distillation in the upper column to obtain oxygen and nitrogen products. As a condensing evaporator connecting the upper and lower columns, the pressure nitrogen of the lower column is used to heat the liquid oxygen of the upper column. When the liquid oxygen is evaporated, the gas nitrogen is condensed. The two-stage distillation column can make oxygen and nitrogen products obtain higher extraction rate and higher purity. The working principle of single-stage distillation column is similar to that of the lower column of two-stage distillation column. Oxygen enriched liquid air is at the bottom of the column, and pure nitrogen gas can be obtained at the top of the column. The single-stage distillation column can't separate the air perfectly, so it is seldom used in practice. However, because of its simple