Apparatus and method for osmotic membrane distillation

Apparatus for enhancing the concentration of a first inorganic compound in a first aqueous solution having a first water vapor pressure provided by a first process of a heavy chemical plant by osmotic membrane distillation, said apparatus comprising

• osmotic membrane distillation means comprising
• (i) a hydrophobic, gas and water permeable membrane;
• (ii) a first chamber for receiving said first solution;
• and
• (iii) a second chamber for receiving a receiver feed aqueous solution having a second water vapor pressure lower than said first water vapor pressure and separated from said first chamber by said membrane means;
• means for feeding said first solution to said first chamber and means for feeding said receiver feed aqueous solution to said second chamber as to operably effect transfer of water vapor through said membrane from said first chamber to said second chamber, and to produce
• (i) a diluted receiver feed aqueous solution;
• (ii) a diluted receiver feed aqueous solution;
• means for collecting said resultant first solution;
• and
• means for collecting said diluted receiver feed solution.

An improved haloalkali production plant comprising

• an electrolytic cell for the electrolytic production of alkali metal hydroxide and halogen from an alkali metal halide solution;
• means for feeding alkali metal halide solution to said cell;
• means for collecting spent alkali metal halide solution having a spent water vapor pressure from said cell;
• means for collecting said alkali metal hydroxide from said cell;
• the improvement comprising
• osmotic membrane distillation means comprising
• (i) a hydrophobic, gas and water vapor permeable membrane;
• (ii) a first chamber for receiving said spent alkali metal halide solution and wherein the production of re-concentrated alkali metal halide solution is effected;
• and
• (iii) a second chamber for receiving a receiver feed aqueous solution having a receiver water vapor pressure lower than said spent water vapor pressure, separated from said first chamber by said membrane and wherein the production of a diluted receiver feed aqueous solution is effected;
• means for feeding said spent alkali metal halide solution to said first chamber;
• means for feeding said receiver feed aqueous solution to said second chamber;
• means for recycling said re-concentrated alkali metal halide solution in whole or in part, directly or indirectly from said first chamber to said electrolytic cell;
• and
• means for collecting said diluted receiver feed aqueous solution from said second chamber