The plate spacing of sieve plate tower is related to the tower height and separation effect. Therefore, when determining the plate spacing, it is necessary to ensure that the gas and liquid phases have sufficient contact area and sufficient separation space to avoid serious entrainment of mist. Secondly, it is also necessary to ensure that the liquid can overcome the resistance of the overflow bucket, flow smoothly from the upper tray to the next tray, and flow down smoothly without flooding. On the premise of meeting the above two conditions, reduce the plate spacing as much as possible to reduce the height of the tower.