Small air separation units, large air separation units and liquid air separation plants in the distillation of the air separation tower, gas and liquid flow on the tower plate is very complex, must control the flow rate of gas. Too high or too low flow rate can spoil the working conditions of distillation. Liquid overhang is one of these abnormal conditions. In normal distillation, the liquid level on the tower plate is higher than the exit weir, and the liquid is not allowed to escape from the screen holes, but flows through the exit weir into the overflow pipe. When the liquid level of the overflow pipe rises to the upper plate, the liquid can not be left behind, which produces a liquid overhang, which can seriously damage the distillation process.
