Multi-stage permeate gap membrane distillation system and process

A multistage permeate gap membrane distillation (MS-PGMD) system comprising a plurality of modules, wherein each module comprises:

• a feed chamber coupled to a feed line and a carrier gas line, wherein the feed line introduces a liquid feed into the feed chamber from a liquid feed tank, and wherein the carrier gas line introduces a carrier gas into the feed chamber;
• a coolant chamber coupled to a coolant line, wherein the coolant line introduces a coolant into the coolant chamber from a coolant feed tank;
• a permeate gap chamber intermediate of the feed chamber and the coolant chamber, the permeate gap chamber substantially filled with a liquid comprising water, wherein a width of the permeate gap chamber is non-uniform;
• a membrane separating the feed chamber from the permeate gap chamber, wherein the membrane allows transportation of vapor from the feed chamber to the permeate gap chamber while blocking liquid from moving from the feed chamber to the permeate gap chamber;
• and
• a thermally conductive plate separating the coolant chamber from the permeate gap chamber, wherein the thermally conductive plate and the coolant within the coolant chamber are cooperatively configured to condense at least a portion of the vapor from the feed chamber that transported through the membrane to form a distillate, wherein:
• the plurality of modules are fluidically coupled in series to the liquid feed,
• a liquid inlet to the feed chamber of a first module in the series is fluidically coupled to the feed line,
• a liquid outlet of the feed chamber of a last module in the series is fluidically coupled to a feed return line,
• each intervening module between the first module and the last module is fluidically coupled by a line from a liquid outlet on the feed chamber of the intervening module to a liquid inlet on the feed chamber of the next module, and
• the coolant chambers of the plurality of modules are fluidically coupled in parallel.