Air separation unit molecular sieve

During the start-up phase, when the liquid volume accumulates in the condensing evaporator, the gas and liquid mixture will pass through the liquid air and liquid nitrogen throttle valves. When the throttle valve begins to close, due to the large opening of the valve, when the amount of gas and liquid mixture from the lower column to the upper column changes little, and the pressure of the lower column does not increase significantly, it means that the temperature difference of the condensing evaporator has not increased. At this time, the condensing evaporator and the surrounding insulation have been cooled to the low temperature required by the liquid accumulation stage. Due to a large amount of cold production and a large amount of gas liquefaction, the liquid evaporation in the condensing evaporator is also increased. The rising steam produced prevents the flow of liquid from the sieve plate hole, and gradually accumulates liquid on the tray, so the liquid level will drop. In ad

The amount of liquid nitrogen removed from the lower column of the air separation unit will affect the purity of the liquid nitrogen in the lower column and the oxygen enriched liquid air at the bottom of the column. When the liquid nitrogen removal amount of the lower column increases, the reflux liquid participating in the heat and mass exchange of the lower column will be reduced, the temperature rise of the rising steam on the column plate will be correspondingly reduced, the condensation of the rising steam will not be sufficient, the oxygen component will be condensed less, the purity of nitrogen at the column top will be reduced, and the purity of liquid nitrogen will be naturally reduced. At the same time, the temperature rise of the downflow liquid will increase, the liquid evaporation will be more sufficient, more nitrogen components will be evaporated to the top of the column, and the purity of the liquid air at the bottom of the column will be improved accordingly.