Multi-Stage Membrane Distillation Process

摘要

Portions of a feed liquid are passed through respective condensers and liquid-liquid heat exchangers. The feed liquid is then heated and injected into a first feed-liquid containment chamber, where vapor from the feed is passed through a first gas-permeable membrane and directed into a first condenser, where the vapor is cooled by the feed liquid passing through the first condenser and condenses as it cools to produce a first liquid permeate. The first liquid permeate is passed through the first liquid-liquid heat exchanger where the first liquid permeate is cooled by the feed liquid passing therethrough. After the vapor is removed from the feed liquid in the first feed-liquid containment chamber, the remaining feed liquid from the first feed-liquid containment chamber is injected into a second feed-liquid containment chamber, where the process is repeated. The first liquid permeate from the first liquid liquid-liquid heat exchanger is combined with the second liquid permeate from the second condenser to form a combined liquid permeate; and the combined liquid permeate is passed through the second liquid-liquid heat exchanger where the combined liquid permeate is cooled by the feed liquid passing therethrough.

主权项

1. A multi-stage membrane distillation apparatus, comprising:
a source of liquid feed; a plurality of purification stages, each respectively including:
a vacuum membrane distillation module, including:
a feed inlet in fluid communication with the source of liquid feed;a gas-permeable membrane contained in the vacuum membrane distillation module;a feed-liquid containment chamber for containing liquid feed from the feed inlet, wherein the feed-liquid containment chamber is positioned on one side of the gas-permeable membrane and is in fluid communication with the feed inlet;a vapor-permeate containment chamber for containing vapor permeated from liquid feed through the gas-permeable membrane, wherein the vapor-permeate-containment chamber is positioned on an opposite side of the gas-permeable membrane from the feed-liquid containment chamber; anda vapor-permeate outlet in fluid communication with the vapor-permeate-containment chamber for extracting the vapor permeate from the vapor-permeate-containment chamber;a condenser configured to condense the vapor permeate and including (a) a vapor-permeate inlet in fluid communication with the vapor-permeate outlet of the vacuum membrane distillation module and (b) a condensed liquid-permeate outlet through which condensed liquid permeate can be removed from the condenser; and at least one vacuum source in fluid communication with and configured to establish a reduced pressure in the vacuum membrane distillation modules and in the condensers.