GB520064A - Improvements in and relating to multiple effect evaporation processes and apparatus for juices and other liquids - Google Patents

Abstract

520,064. Multiple effect evaporators evaporating saccharine solutions. SHROFF, R. D. Jan. 9, 1939, No. 709. Convention date, Jan. 7, 1938. [Class 32] Cane and beet juices and like liquids are evaporated in multiple effect by heating the liquid to boiling point, subjecting the heated liquid in the form of a fine shower to reduced pressure, passing the vapours thus formed in heat exchange with the residual liquid, and again subjecting the thus reheated liquid in the form of a shower to further reduction of pressure, the successive steps being repeated as often as required. The liquid is passed through the heat exchange stage in a thin layer, preferably in film form, e.g. by passing it down the inner surfaces of tubes surrounded by the vapour. The size of the evaporating and heat exchange units may be reduced in each successive stage. The apparatus comprises alternate evaporator and heat exchange units A, B. The heated liquid is fed through a pipe 3 onto a perforated trough 1 from which it falls in a shower through the chamber A. Unevaporated liquid flows through tubes 11 in the heat exchanger unit B while the vapours formed pass off through a canvas-covered metallic screen 8 and flow downwardly over perforated plates 16 around the tubes 11. The condensate thus formed and residual gases are collected in a pipe 17 and passed to a vessel 20. The reheated juice is collected on a plate 26 and fed through a constant level valve C, forming a seal for the vapours, to a similar perforated trough in the next effect. Residual liquid is pumped through a pipe 24 to a further similar apparatus while condensate and gases are fed to a vessel 20 through a pipe 18 one end of which is connected to the vacuum pipe 22. The juice is preferably fed to the tubes 11 through feeder devices shown in Figs. 2 and 3, by which it is caused to flow in films down the insides of the tubes.