GB1199116A - Evaporator - Google Patents

Abstract

1,199,116. Evaporators, progressive flow type. BATTELLE DEVELOPMENT CORP. 3 July, 1968 [4 July, 1967], No. 31832/68. Heading B1B. A solution is concentrated by evaporation in chamber 5 within a rotary casing 1 from the inner wall 3 of which project a series of annular, heatable blades 6a . . 6l which define, in conjunction with wall 3, a series of annular channels 7a .. 7l connected in pairs of passages 8a . . 8f formed along the radially outer edges of alternate blades 6a, 6c ... The radial length of the successive blades decreases in the downward direction. In the evaporator as shown, the blades are hollow, and steam for heating the blades is supplied to chamber 4 through duct 15; and the condensate, driven out of the blades by centrifugal force, is discharged from chamber 4 through nozzle 19 into spiral trough 20. It is mentioned that the blades may be heated in a different manner, e.g. by electrical means. The solution to be concentrated is fed through nozzle 9 into channel 7a, flows by centrifugal force outwardly over the upper surface of blade 6a and passes through passage 8a into channel 7b between the hot surface of blades 6a and 6b. When channel 7b is full of solution, channel 7a is still not quite full since blade 6a is longer than blade 6b. Thus further flow of solution into channel 7a causes the solution in channel 7b to overflow over the radially inner edge of blade 6b. This overflow is urged by centrifugal force along channel 7c and thence through passage 8b into channel 7d. This alternate inward and outward movement of the solution continues down the evaporator. While thus flowing in the channels between the hot blades, the solution is caused to boil, and the vapour which is given off leaves the solution as it flows over the inner edges of blades 6b, 6d ... The vapour flows out of the evaporator through duct 10 which is connected to a centrifugal condenser 21. Concentrated solution is forced out of the evaporator through channel 7m and nozzle 13 into spiral trough 14. In a modified design, the length of each non-apertured blade is the same as the length of the apertured blade beneath it. Several evaporator chambers can be arranged along a common axis of rotation, with the solution passing from one chamber to another in series, while the solvent vapour given off in each chamber (except the last) is used to heat the next chamber.