Patent ID: 9718709
Date: 2017-08-01
CPC Classifications: C02F,Y02A

Claim:
1. A multi-stage membrane distillation apparatus, comprising: a source of liquid feed; a plurality of purification stages including at least a first purification stage configured to receive liquid feed from the source and a second purification stage configured to receive liquid feed from the first purification stage, each purification stage respectively including: a heat source configured to heat liquid feed only between the source of liquid feed and the first purification stage, wherein no heat source is configured to heat liquid feed in or between the purification stages; at least one liquid-remainder conduit configured to provide fluid communication from the feed-liquid containment chamber in the vacuum membrane distillation module of the first purification stage to the feed-liquid containment chamber in the vacuum distillation module of the second purification stages; and a plurality of regulators in fluid communication with and configured to establish a first reduced pressure in the vapor-permeate containment chamber of the first purification stage, a second reduced pressure in the vapor-permeate containment chamber of the second purification stage that is lower than the first reduced pressure, and a reduced condensing pressure in the condensers.