Solid Hollow Fiber Cooling Crystallization Methods

Abstract

A solid hollow fiber cooling crystallizer and method for crystallizing aqueous and organic solutions are provided. The solid hollow fiber crystallizer (SHFC) for carrying out cooling crystallization of inorganic/organic microsolutes/macrosolutes from solution generally includes a bundle of non-porous hollow fibers mounted within a shell where a feed solution for crystallization flows through the lumen side of the hollow fibers and a cooling solution flows through the shell side to form nuclei and subsequently crystals in the feed solution at a temperature below its saturation temperature. The solid hollow fiber crystallizer may be combined with a mixing device, such as a completely stirred tank or static mixer, to further effectuate crystallization. The solid hollow fiber crystallizer may be operated in a number of modes including feed recycle mode, once through mode, SHFC-in-line static mixer in series mode, and SHFC-CST in series mode. The advantages of solid hollow fiber cooling crystallization in comparison to conventional crystallization processes include improved temperature control between crystallizing solution and coolant, higher nucleation rates, improved control of crystal size and crystal size distribution, smaller crystal size, capability for decoupling crystal nucleation and crystal growth, decreased fouling of process equipment, and improved process scale-up.

1 . A method of forming nuclei and subsequently crystals in a feed solution, the method comprising the steps of:
 (a) conveying said feed solution into a solid hollow fiber crystallizer (SHFC) system, said solid hollow fiber crystallizer system including a plurality of non-porous hollow fibers mounted within a shell and said feed solution being conveyed to either a lumen side or a shell side of said plurality of non-porous hollow fibers;   (b) conveying a cooling solution into said solid hollow fiber crystallizer, said cooling solution being conveyed to an opposite side of said plurality of non-porous hollow fibers as compared to said feed solution; and   (c) cooling said feed solution below its saturation temperature to form nuclei and crystals.   
     
     
         2 . The method of  claim 1 , wherein said feed solution is selected from the group consisting of an aqueous solution and an organic solution. 
     
     
         3 . The method of  claim 1 , wherein said feed solution includes an inorganic or organic solute. 
     
     
         4 . The method of  claim 1 , wherein said feed solution includes at least one of microsolutes and macrosolutes. 
     
     
         5 . The method of  claim 1 , further comprising the step of subjecting said feed solution that contains nuclei and crystals to filtration. 
     
     
         6 . The method of  claim 1 , further comprising the step of recycling said cooled feed solution back through said solid hollow fiber crystallizer system. 
     
     
         7 . The method of  claim 1 , wherein said hollow fiber crystallizer system comprises a bundle of non-porous polymeric or ceramic hollow fibers mounted within said shell. 
     
     
         8 . The method of  claim 7 , wherein said hollow fiber crystallizer system includes a bundle of non-porous hollow fibers fabricated from a polymeric material selected from the group consisting of polypropylene, polyethersulfone (PES), polyetheretherketone (PEEK), a polyimide, polyphenyl sulfide (PPS), polyethylene, polytetrafluoroethylene (PTFE), polysulfone (PS) and poly-4-methyl-1-pentene (PMP). 
     
     
         9 . The method of  claim 7 , wherein said hollow fiber crystallizer system includes a bundle of non-porous hollow fibers fabricated from a ceramic material selected from the group consisting of alumina, silica and glass. 
     
     
         10 . The method of  claim 1 , wherein a temperature difference between said feed solution temperature and said chilled cooling solution is less than or equal to 2° C. 
     
     
         11 . The method of  claim 1 , wherein said plurality of hollow fibers is oriented in a helix within said shell. 
     
     
         12 . The method of  claim 1 , wherein said feed solution includes seed crystals and wherein said solid hollow fiber crystallizer (SHFC) system is effective to grow said seed crystals.