Abstract Method for distillation of a liquid, particularly sea water, in which the liquid flows thru a plurality of stages each of which includes at least one cell through which the liquid flows and in which steam produced by evaporation is separated from the unevaporated liquid in order to obtain a condensate. The method employs one or more expansion nozzles in each cell through which the liquid expands and is thus converted partly into its vapour phase as a result of the reduction in pressure. The composite liquid and gaseous fluid passes along a curved flow surface which, as a result of the centrifugal forces created effects separation of the liquid from the steam. The steam is then condensed and the remaining liquid is sent to a diffusor in which its speed is transformed into pressure, delivering thus a pressure greater than the one at the inlet of the expansion nozzle. The liquid passes then through a heat exchanger and may then either be re-cycled through the cell or passed to a warmer or cooler cell.
A method as claimed in claim 1 wherein the at least a portion of the unevaporated liquid, the pressure of which has already been increased, is reheated by the heat obtained by the condensation of the vapor from a warmer stage, said reheated liquid being returned cyclically to the same stage for re-evaporation.
Claim 2
Dependent Claim
46 words
A method as claimed in claim 1 wherein a part of the unevaporated impure liquid after having been pressurized and reheated is supplied to a warmer stage and mixing the reheated part of the unevaporated impure liquid with the impure liquid circulating in the warmer stage.
Claim 3
Dependent Claim
35 words
A method as claimed in claim 1 wherein a part of the unevaporated impure liquid is supplied to a colder stage and mixed with the flow of the impure liquid circulating in the colder stage.
Claim 4
Dependent Claim
134 words
A method as claimed in claim 1 wherein the plurality of stages is divided into a first and a second series of successive stages, passing at least a part of the unevaporated impure liquid and in the first series of stages from each stage to a warmer stage in the series, withdrawing at least a part of the unevaporated liquid from the last stage of said first series at the highest temperature and highest pressure of the first series, further heating the withdrawn liquid and introducing it to the second series of stages, passing the withdrawn reheated liquid through successively colder stages of the second series, removing the unevaporated liquid from the last stage of the second series at the Lowest temperature and lowest pressure of the second series and discarding said removed liquid.
Claim 5
Dependent Claim
41 words
A method as claimed in claim 1 wherein the second series of stages operate as multiflash distillation stages, and further comprising introducing to the stages of the second series only a portion of the unevaporated impure liquid from a preceeding stage.