Patent ID: 8074371

Claim:
An evaporator apparatus ( 1 ) comprising a heat exchanger ( 4 ), said heat exchanger being comprised of a plurality of parallel heat exchanger tubes ( 8 ) surrounded by a jacket ( 10 ), each of said heat exchanger tubes having a first end and a second end, the first ends of said heat exchanger tubes being terminated at a first perforated tray ( 3 ) and the second ends of said heat exchanger tubes being terminated at a second perforated tray ( 9 ), a feed chamber adjoining said first perforated tray and a devolatilization chamber adjoining said second perforated tray, said feed chamber having an inlet, said devolatilization chamber having a discharge and a vapor outlet and said jacket having an inlet and an outlet for heat transfer media, wherein said heat exchanger tubes have a rectangular or elliptical cross-section over the greater part of their length.