It is unsuitable for concentrating those liquids, which form a scale or deposit salt.
It is suitable for process, in which the final product is a liquor instead of solid.
Its usual dimensions are: tube dia = 2-3 cms; evaporator body dia = 1-4 metres and evaporator height = 2.5-4 metres.
Liquor flows inside the tube, while the steam is outside submerging the tube.
✅ The correct answer is option D.