Air separation unit distillation column

When the air separation unit is in normal operation, the liquid flows down and can only flow on the tray and flow to the lower tray through the overflow bucket because the supporting force of the rising steam prevents the liquid from flowing down from the small hole of the tray. After shutdown, due to the interruption of rising gas flow, the liquid on the tray can flow from the overflow bucket to the lower tray, and also can flow through the small hole on the tray to the lower tray. This will cause the surface of liquid oxygen and liquid air rise, which may exceed the position of the expansion air outlet pipe, resulting in liquid carrying accident of the expander during restart. Therefore, pay attention to the liquid level position when stopping.

The plant operation cycle between two large heating is related to many factors. From an operational point of view, this mainly depends on when the air passage of the main heat exchanger is blocked. The main reason for the blockage is that the moisture and carbon dioxide content in the air entering the unit exceeds the standard, which accumulates and freezes in the main heat exchanger until it is blocked. The abnormal operation of molecular sieve purification system will shorten the operation cycle of the unit. It is mainly caused by the following reasons: 1. The molecular sieve adsorption bed is short circuited. In the process of operation, due to the unstable gas velocity control or switching, the pressure difference between the two tanks is too large, which will affect the bed layer, make the molecular sieve bed uneven and make the bed layer short circuit. In serious cases, the dust screen of the adsorber will break and the molecular sieve powder will enter the heat exchanger c