How is the tower plate resistance formed and what parts does it include?

The tower plate resistance refers to the pressure drop generated when the rising steam passes through the sieve hole of the tower plate and the liquid layer on the tower plate. When the vapour passes through the sieve hole of the tower plate, it will produce resistance to the flow due to the change of the cross section of the passageway. This resistance exists no matter whether there is liquid on the tower plate or not, so it is also called dry Tower plate resistance. It is related to factors such as the speed of steam passing through the sieve hole, the opening rate of the sieve plate and the roughness of the hole. Among them, the speed of the sieve has the greatest influence on it, which is proportional to the square of the speed of the sieve. Secondly, the rising vapor must overcome the resistance formed by the surface tension of the liquid to enter and escape the liquid layer. This resistance is called surface tension resistance. It is proportional to the surface tension of the liquid and inversely proportional to the diameter of the sieve hole. In addition, the rising vapor can only rise by overcoming the resistance formed by the static pressure of the liquid layer on the tower plate, which is the static pressure of the liquid column. It is related to the thickness of liquid layer and the density of liquid. Thus it can be seen that the resistance generated by each tower plate is composed of dry Tower plate resistance, surface tension resistance and static pressure of liquid column, which is generally 200 ~ 300Pa. The resistance of the lower tower measured in the distillation tower and the resistance of the upper, middle and lower sections of the upper tower respectively refer to the sum of the resistance of each tower plate in each section.