Air separation unit, increase the size of the amount of air on the distillation column, increase 20% without taking any measures, can work normally. When the amount of process air is too large, it is necessary to increase the diameter of sieve on the tray to reduce the steam velocity. Increase the heat transfer area of the main cooler to reduce the temperature difference and ensure the normal operation of the distillation column.
Because when the amount of process air increases, the rising steam in the distillation tower will increase, and the amount of liquid to be condensed in the main cooling tower will also increase accordingly, so there is no effect on the reflux ratio in the tower. In a certain range, the purity of oxygen and nitrogen can basically remain unchanged, and the yield will increase proportionally with the increase of air volume. However, with the increase of the amount of condensate in the main cooling, the heat load of the main cooling increases. When the heat transfer area is insufficient, the temperature difference between the main cooling tower and the lower tower will increase. At the same time, with the increase of gas velocity in the tower, the amount of downflow liquid increases, and the liquid layer on the tray thickens, which increases the resistance of the tray and the pressure of the upper and lower columns. This will have an adverse effect on the separation of oxygen and nitrogen, and also increase the power consumption. When the gas volume is too large, the resistance of tray and the resistance of downstream liquid flowing through the overflow bucket will increase a lot, resulting in the increase of liquid level in the overflow bucket, and even the flooding phenomenon that the liquid can not flow down, which will destroy the normal working condition of the distillation column. In addition, as the rising steam flow rate increases, it is easy to bring the droplets to the last tray, which affects the distillation effect and reduces the nitrogen purity, thus reducing the extraction rate of low oxygen.
Therefore, the increase of air volume in the air separation unit will have a certain impact on the distillation column, and some measures need to be taken.
