Regarding the theoretical plate number
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A beginner seeking advice: The laboratory uses triangular spiral packing; the tower height is 600 mm and the diameter is 20 mm. The theoretical half-value was determined to be 33 using heptane + methylcyclohexane. However, by using a D=35mm tube with the same packing and height, the theoretical number of plates was measured to be 12 using the same method. What is the reason? Is an insufficient evaporation rate leading to poor separation, which in turn results in incorrect values for the number of theoretical plates? Theoretically, with the filler and height remaining constant, what impact does a change in tower diameter have on the number of theoretical plates and the separation efficiency?
By the way, it’s Saturday today; I guess only we need to go to work.
Is it because the backflow volume is too low? If you’ve never done this work before, you can post a diagram of your setup; at least that way we can know where the sampling takes place and whether there is continuous feeding If your tubes become thicker, the processing capacity will definitely increase; accordingly, the amount of reflux and heating required will also rise. Otherwise, there will be an uneven distribution within the tower, and insufficient material volume will lead to a poorer separation effect
Of course it has an impact; gas-liquid exchange, fouling on the walls of the tower, and the tower’s processing capacity all affect the calculated value of the theoretical number of theoretical plates