There are many separation methods beyond those normally found in standard texts. Diverse evaporators and dryers have been employed to effect separation of liquids from solids with which they are admixed or otherwise associated.
Although "distillation" is commonly used in the sense of vaporizing a single constituent from a solution, e.g., distilling water, the term is properly applied only where vaporization of a liquid mixture yields a vapor phase containing more than one constituent, and it is desired to recover one or more of these constituents in a nearly pure state. Thus, the process of separating liquids from solids by vaporizing the liquid is properly referred to as evaporation or drying.
Caffes (U.S. Pat. No. 4,292,121) provides a singlechamber flash-evaporation and condensation apparatus to separate solids from a suspension, solution or other admixture of solids and liquid.
Angelucci (U.S. Pat. No. 1,885,402) concerns continuous evaporation or distillation apparatus for concentrating a liquid component under vacuum by vaporizing and then separately condensing water therefrom.
Although Thomas (U.S. Pat. No. 2,803,589) pertains to concentrating salt water and sludge and separating fresh water therefrom, his process comprises:
(a) heating to a high temperature at a pressure which prevents vaporization,
(b) withdrawing in liquid phase under pressure,
(c) spraying through a series of vertical flash evaporators or pressure containers and
(d) separating liquid portions of two produced streams.
According to Waddill (U.S. Pat. No. 2,956,934) a flashed vaporized distillable material is passed in an elongated distillation zone from a flashing section at one end of the zone to an annulus surrounding a combination condensing-demisting zone substantially axially disposed in a mid-section of the distillation zone and then through the combination condensing-demisting zone, recovering condensate from within said condensing-demisting zone and recovering any non-condensables from the other end of the distillation zone.
Frank (U.S. Pat. No. 3,250,687) provides apparatus for film-type distillation in which liquid flows upon an evaporating surface in a relatively thin film; it is subjected to distillation in a spread-out condition, the distillate and distillate residue being separately collected.
Starmer (U.S. Pat. No. 3,444,049) uses a multi-staged evaporator comprising a vessel divided internally into a number of compartments by partitions serving as heat-transfer surfaces, in which means are provided for feeding liquid onto one side of each of the surfaces and in which distillate-collecting means are arranged on the other side of each surface. Vapor produced from the liquid can flow from one heat-transfer surface to another where it is condensed by giving up heat to liquid on the other side of the surface.
Webb (U.S. Pat. No. 3,791,934) has a multistage flash system which includes a continuous, downwardly spiralling, substantially enclosed passage with a plurality of transverse partitions dividing the passage into a series of flash evaporator stages through which flashing distill and flows during its passage from the top to the bottom end of the passage. A central core (around which the helical passage winds) contains a condensing section divided into a series of condenser stages (one above the other), each of which is in vapor communication with an adjacent flash stage in the helical passage.
To prevent adherence of precipitated solids to a contacted surface of apparatus for evaporating an aqueous solution containing dissolved solids, Erwin (U.S. Pat. No. 4,119,485) evaporates the solution in apparatus (wherein a hot contacted surface is preferentially oil wettable and zero absorbent of water from the solution) while continuously wetting the contacted surface with an organic liquid which is immiscible with the aqueous solution being evaporated, the contacted surface comprising a fluorocarbon polymer.
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