摘要 |
<p>Each stage of the evaporator has a heat exchanger compartment (7,9,10,11) and an evaporation compartment (2,3,4,6) in open communication. Liquid is heated as it passes in one direction through a heat exchanger conduit (28) in the heat exchanger chambers and then evaporated as it passes in counter-flow through the evaporation chambers. To provide a sufficient degree of control of liquid levels in the evaporation compartments, a circulation conduit (32) with a control valve (33) is arranged to convey the heated fluid directly from the discharge chamber (31) to the evaporation compartment of a selected one of the last stages.</p> |