Question

why are spining bands so efective at increasing the   number of theoretical plates in distillation columns?

Answer 1

when the solution is going to be heated for purification its vapors rise to the fractionating column. when it rises, it cools, condensing on the condenser walls and the surfaces of the packing material. Here, the condensate continues to be heated by the rising hot vapors and again it vaporizes . moreover, the composition of the fresh vapors are calculated once again by Raoult's law. Each vaporization-condensation cycle is known a theoretical plate will yield a more purer solution of the more volatile component. In reality, each cycle at a given temperature does not occur at exactly the same position in the fractionating column;