Multi-stage thin film evaporator having a helical vapor flow path

Claim 2

Evaporator, comprising an evaporator chamber, means for introducing the liquid to be evaporated into the evaporator chamber and for conducting the vapor there produced out of the evaporator chamber, a vertical heat exchanger within the evaporator chamber wherein the liquid to be evaporated flows downwardly, means for heating said heat exchanger with a fluid warmer than the liquid to be evaporated, whereby at least part of the liquid evaporates and a mixture of liquid and vapor is discharged onto the bottom of the evaporator chamber, means for removing the liquid from the bottom of the evaporator, a stationary helically shaped flow duct within the evaporator chamber into which flow duct the vapour ascends from the bottom of the evaporator chamber and is set into a powerful rotary motion, apertures on the outer periphery of said flow duct, a space surrounding the flow duct and closed at its top so that through said apertures the liquid droplets present in the vapor are flung into said space, whence the liquid flows back to the bottom of the evaporator chamber, an aperture above the flow duct so that the pure vapor escapes through said aperture to the means for conducting the vapor out of the evaporator chamber.

Claim 3

Distilling apparatus, comprising an evaporator according to claim 1 and, furthermore, a condenser wherein the vapor produced in the evaporator is condensed to become a distillate.

Claim 4

Distilling apparatus comprising a plurality of consecutive evaporators operating at stepwise lower temperatures, each of these comprising a heat exchanger consisting of at least one vertical pipe wherein the vapor originating in the preceding distilling stage is condensed and on the opposite side of the heat exchange surface of which the liquid to be distilled flows downwardly from above, at the same time partly evaporating, and discharges together with the vapor produced into the lower part of the evaporator, a droplet separator, consisting of a helically shaped vapor flow duct into which the vapor rises from the lower part of the evaporator and in the course of its flow is set into rotary motion, apertures on the outer periphery of said flow duct, into which apertures the liquid droplets present in the vapor are flung by centrifugal force action, and an enclosed space surrounding said duct, which is closed at its top and communicates at its lower end with the lower part of the evaporator, into which space the droplets are flung from said apertures and return to the lower part of the evaporator, means for transferring the liquid to be evaporated from the lower part of the evaporator to the upper part of the next evaporator''s heat exchanger, means for transferring the pure vapor from above said droplet separator into the heat exchanger of the next evaparator there to serve as heating medium, and means for removing the distillate formed by condensation from the vapor from the bottom of the evaporator''s heat exchanger.

Claim 5

Distilling apparatus comprising a plurality of consecutive evaporators operating at stepwise lower temperatures, each of these comprising a heat exchanger consisting of at least one vertical pipe wherein the vapor originating in the preceding distilling stage is condensed and on the opposite side of the heat exchange surface of which the liquid to be distilled flows downwardly from above, at the same time partly evaporating, and discharges together with the vapor produced into the lower part of the evaporator, a droplet separator, consisting of a helically shaped vapor flow duct into which the vapor rises from the lower part of the evaporator and in the course of its flow is set into rotary motion, apertures on the outer periphery of said flow duct, into which apertures the liquid droplets present in the vapor are flung by centrifugal force action, and an enclosed space surrounding said duct, which is closed at its top and communicates at its lower end with the lower part of the evaporator, into which space the droplets are flung from said apertures and return to the lower part of the evaporator, means for transferring the liquid to be evaporated from the lower part of the evaporator to the upper part of the next evaporator''s heat exchanger, means for transferring the pure vapor from above said droplet separator into the heat exchanger of the next evaparator there to serve as heating medium, and means for removing the distillate formed by condensation from the vapor from the bottom of the evaporator''s heat exchanger.

Claim 6

Distilling apparatus according to claim 3, comprising in each evaporator an auxiliary heat exchanger, through which heat exchangers the lIquid to be distilled flows from the coldest to the warmest evaporator and is heated by steps prior to its discharge into the warmest evaporator.

Claim 7

Distilling apparatus according to claim 3, wherein the warmest distilling stage is heated by the aid of external energy and at least part of the vapor produced in the coldest distilling stage is condensed in heat exchange with a fluid which does not flow into the other distilling stage.

Claim 8

Distilling apparatus according to claim 3, wherein part of the vapor liberated in a given distilling stage is compressed to have a higher pressure and temperature and condensed in heat exchange with the liquid to be distilled which resides in a distilling stage having a temperature higher than that of the distilling stage in which the vapor was liberated.

Claim 9

Appartus according to claim 6, wherein the waste heat produced at the compression of vapor is utilized for heating the liquid to be evaporated.