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.
