A key factor in the successful operation of an intube falling film evaporator is the uniform distribution of feed to all tubes and the uniformity of flow around the periphery of the tubes.
The film shown to the left was formed using only an orifice plate located above the tubesheet. This film is unacceptable due to poor fluid distribution and random film breaks around the periphery of the tube.
The falling film shown to the right uses the same orifice plate but with the tubes extended above the tubesheet. This M & L innovation adds nothing to the cost of the unit with the resultant film being uniform and stable. Heat transfer to the thin film is high with a holdup and time of contact low which is of great advantage in handling heat sensitive liquids. Evaporation at very low absolute pressures is possible since there is no hydrostatic head to affect the boiling temperature. All M & L distribution devices are tested in our research laboratory prior to production.
Intube Falling Film Evaporators