Apparatus for the recovery of volatile constituents in liquids containing fractions having different boiling points

摘要

PICT:0673545/III/1 PICT:0673545/III/2 Liquids are evaporated by passing the liquid through two heat exchangers connected in series and then introducing the heated liquid into a film evaporator. The first heat exchanger comprises three concentric tubes wherein the feed-liquid flows through the inner tube, the hot concentrated liquid from the evaporator flows through the annular passage between the inner and the intermediate tubes, and cooling water flows through the annular passage between the intermediate and outer tubes. The evaporation, which is preferably carried out under reduced pressure, is particularly useful in the concentration of fruit juices in the temperature-range of 170 DEG to 190 DEG F. Liquid-to-be-evaporated is pumped via pipe 21 into the inlet 25 of heat- PICT:0673545/III/3 exchanger 22 which comprises, Fig. 6, three sections of pipes 23 connected by bends 24, three tubes 28 concentric with pipes 23 and provided with headers 27, and three more tubes 32 connected by headers 29 disposed between pipes 23 and tubes 28. The liquid-to-be-evaporated flows through pipes 23. Unevaporated liquid leaves evaporator 11 through pipe 54, enters the heat-exchanger at inlet 30, flows through the annular passages between pipes 23 and 32, and leaves the heat-exchanger at outlet 31. Cooling water supplied through pipe 33, is passed through the outer annular passages of heat-exchanger 22. The partially-heated liquid leaving heat-exchanger 22 through outlet 26 is passed to heat-exchanger 35, Fig. 4, which is disposed behind heat-exchanger 22 in Fig. 1. Heat-exchanger 35 is also a system of three concentric pipes. The innermost pipes are connected by bend 37, and the others by headers 40 and 38. The liquid-to-be-evaporated flows through the inner annular passage of heat-exchanger 35; while hot water from tank 19 is pumped countercurrently to said liquid via pipes 47, 48 through the innermost pipe and through the outer annular passage of the heat-exchanger. The water leaving heat-exchanger 35 through outlets 51, 52, is returned to tank 19 via pipe 53. The heated liquid, which preferably only remains in heat-exchanger 35 for 3 to 8 seconds, is passed to evaporator 11 via pipe 44. The vapours from the evaporator are condensed in condenser 15, and the condensate is collected in vessel 17. The evaporator may be of the type disclosed in Specifications 595,597 and 673,543. Specification 673,544 also is referred to.