The spacing between the tower plates determines the height of the whole distillation column. Therefore, it is hoped that the spacing between the tower plates should be as small as possible. The minimum plate spacing is limited by two conditions:
1) liquid flooding should be avoided.
That is to say, the plate spacing should be larger than the minimum spacing to ensure that the liquid flows smoothly from the previous plate to the next plate. It is calculated by the flow resistance of the reflux liquid through the overflow bucket. Obviously, it is closely related to the structural form of overflow bucket and the height of tower plate inlet baffle;
2) make sure that there is no fog clip.
On the tower plate, the steam rises through the sieve hole and the liquid layer bubble, and the mass transfer area on the sieve plate basically consists of the following parts: close to the sieve plate is the static liquid layer, which is very thin; then is the bubble layer; which is the foam layer with honeycomb structure. Due to the burst of foam and the effect of spraying by vapor, splashing drops are also included in it, which forms a mist layer. If the vapour clamps up to the upper tower plate, it will form mist clamps. In order to ensure the normal operation of the rectification working condition and the minimum spacing between the tower plates without mist, it should be the height of the foam layer of the tower plate plus the gas-liquid separation space.
