US 4,168,211 AGranted

Distillation apparatus and method

OwnerJohn E. Pottharst, Jr.inventor

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Abstract

A vapor compression type distillation unit is provided for distilling brackish water or seawater wherein high heat transfer rates are achieved in a vertical shell and tube type vaporizer while avoiding carry-over normally resulting from excessive foaming and its entrainment of liquid droplets in the vapor. A pool of liquid is maintained at the lower end of the vaporizer to be fed into the tubes with the level of the liquid being relatively low so that most of the length of the tube is filled with a frothy mixture conducive to high heat transfer rates. The mixture of vapor and liquid discharged from the upper ends of the tubes is caused to flow laterally and then downwardly through a downtake passage communicating with the lower end of the vaporizer. A vapor outlet is provided intermediate the ends of the downtake passage in such a manner that the vapor must change its direction of flow, preferably substantially 180.degree., thereby facilitating the removal of droplets, and also slugs and bubbles, by centrifugal action. The incoming feed is preferably released above the body of liquid in such a manner that any gases or vapors contained therein can escape from the feed while the latter is falling downwardly into the body of liquid.

Claims14

Dependent claims

A vapor compression distillation apparatus comprising, in combination, a vertical shell and tube vaporizer having upper and lower tube sheets with tubes extending vertically therebetween and also having upper and lower closure members forming upper and lower chambers in fluid communication with said tubes;

means forming a substantially unrestricted downtake passage vertically from the upper to lower chamber with the passage having an inlet from the upper chamber laterally displaced from the upper tube sheet and having an upper edge substantially flush with and extending along a substantial portion of the periphery of such tube sheet so that liquid on the upper tube sheet can flow laterally thereacross and across said edge to then directly fall vertically down the downtake passage to the lower chamber, said downtake passage inlet also being disposed so that vapor emerging from said tubes must flow downwardly in the downtake passage along with said liquid;
means forming an upwardly extending vapor outlet passage laterally displaced and along side a portion of said downtake passage and having an inlet from the downtake passage at a level below that of the upper tube sheet so that vapor flowing downwardly in the downtake passage must reverse its direction of flow in order to flow up said vapor outlet passage;
vapor compression means having a suction inlet in an upper portion of said vapor outlet passage and a vapor discharge outlet into the shell side of said vaporizer;
a distillate outlet from the shell side of the vaporizer;
means for maintaining a liquid level in the lower portion of the vaporizer on the tube side thereof but above the level of the lower tube sheet;
and a feed inlet arranged to discharge feed into the tube side of the vaporizer.

3 more elements

A vapor compression distillation apparatus for distilling brackish water or seawater comprising, in combination, an evaporator including an upright shell and upper and lower tube sheets with a plurality of tubes extending vertically therebetween, said upper tube sheet being trapezoidal in shape and having a length at least twice its width so as to provide one elongated edge lengthwise thereof;

said evaporator also including means providing upper and lower chambers above and below said tube sheets and a substantially unrestricted vertical downtake passage communicating therebetween, said downtake passage extending vertically downwardly along one side of the shell into the lower chamber and having an upper inlet extending substantially flush along said elongated upper tube sheet edge to facilitate drainage of liquid off of the upper tube sheet for vertical downward flow to the lower chamber, an upwardly extending steam outlet passage disposed laterally of and along side a portion of the downtake passage and having an inlet opening from said downtake passage intermediate the ends of the downtake passage and at a level below that of the upper tube sheet so that steam flowing downwardly in said downtake passage from the upper chamber must substantially change its flow direction to flow from said downtake passage through said steam outlet passage;
vapor compression means having a suction inlet from said steam outlet passage and a discharge outlet into the shell side of said evaporator;
a distillate outlet from the shell side of said evaporator;
means for maintaining the level of liquid in the lower portion of the evaporator on the tube side thereof at a level above the lower ends of said tubes but not exceeding one-fourth of the length of said tubes;
and a feed inlet arranged to discharge feed into the liquid in the lower portion of the evaporator.

2 more elements

Dependencies are inferred from the claim text.