Chemical Engineering - Mass Transfer - Discussion

Isn't the packed tower should provide higher pressure drop?

I think the right answer is B.

In packed tower low-pressure drop and high contact.

What is correct?

I think the option A is correct.

The packed tower has a low-pressure drop but high contact time.

I think C is the correct answer.

Because in packed tower entrainment is less, so liquid hold up is less & obviously lower pressure drop in the packed column than plate column.

@Udit.

Explain how ∇P is low in packed tower.

C is the correct answer.

Low-pressure drop. The packed tower has a higher voltage, so the pressure drop is lower than the plate tower. In the normal condition, the pressure drop of the plate tower is about 0.4 - 1.1 kPa per unit theoretical stage while the packed tower is about 0.01- 0.27 kPa. The low-pressure drop can not only save the operating cost but also save energy. It is very suitable for heat-sensitive material separation.

Low liquid hold-up quantity. Liquid hold-up quantity refers to the liquid quantity on the packing surface, internals and plates. The liquid hold-up quantity of the packed tower is less than 6% while the plate tower is higher to 8-12%. Though the higher liquid hold-up quantity can ensure the stable structure of materials and tower, it needs long operating hours, long operating periods and expensive operating costs, which is bad for the distillation process.

The main points of advantages have been captured here,

It requires minimum structure.
The packed column causes a minimum pressure drop.
The liquid hold-up is relatively low in the packed column.
The packed column can easily handle highly corrosive, foaming fluid.