Chromatographic Rectification of Ethanol

Abstract

A scalable technology for purifying ethanol from a dilute aqueous solution of ethanol, the technology incorporating vaporization of ethanol coupled with a chromatographic rectification process comprising feeding a vaporized ethanol/water mix onto a plurality of molecular sieve beds, to produce dehydrated ethanol vapor, which can then be condensed to recover purified dehydrated ethanol liquid. The scalable technology process is suitable for farm-scale production of fuel-grade ethanol, having the added benefit of allowing wet distillers grains to be used on-site as live-stock feed, thus eliminating the energy and shipping costs associated with drying and off-site distribution of the grains portions generated during the rectification process. Scalable technology, as provided herein, is also suitable for recovery of ethanol from processes which use ethanol during manufacture of a product. Current embodiments of the scalable technology as disclosed herein are suitable for production of fuel-grade ethanol at quantities of anywhere from about 1000 gallons per year to upwards of hundreds of millions of gallons per year, by reducing energy requirements and costs and reducing pollution, thereby minimizing the economy of scale effect to create a technology scalable to any output need. Embodiments disclose a plurality of smaller molecular sieve beds in series and use heat generated during desorption and regeneration of the molecular sieve beds as an energy source to aid in the vaporization step.

1 . A scalable purification system for the production of purified dehydrated ethanol from an aqueous solution of ethanol comprising:
 a still that vaporizes the aqueous solution of ethanol produce a vaporized gaseous mixture of ethanol;   a chromatographic rectifier that applies the vaporized gaseous mixture of ethanol obtained from the aqueous solution to produce enriched ethanol vapor, wherein the chromatographic rectifier comprises a plurality of molecular sieve beds and wherein at least one of the molecular sieve beds has a cross-sectional diameter different from another of the beds, so that purification is achieved without column rectification; and   a condenser that condenses the enriched ethanol vapor so as to recover purified dehydrated ethanol liquid.   
   
   
       2 . A scalable purification system for the production of dehydrated ethanol according to  claim 1 , further comprising a regenerator that regenerates the molecular sieve beds. 
   
   
       3 . A scalable purification system according to  claim 2 , wherein the regenerator comprises a vacuum desorption unit that exposes the sieve beds to vacuum desorption of water vapor therein using a pressure swing absorption process to produce desorbed vapor. 
   
   
       4 . A scalable purification system according to  claim 3 , wherein the regenerator further comprises a condenser that condenses desorbed vapor from the molecular sieve beds to produce condensed liquid, wherein the condensed liquid is fed into a beer column feed. 
   
   
       5 . A scalable purification system according to  claim 4 , wherein the regenerator further comprises an energy recovery unit that recovers energy from the purified dehydrated ethanol vapor and reuses the energy in vaporizing the aqueous solution. 
   
   
       6 . A scalable purification system according to  claim 1 , further comprising a stripper column or batch still that vaporizes ethanol from an aqueous solution of ethanol. 
   
   
       7 . A scalable purification system according to  claim 1  wherein the plurality of molecule sieve beds includes at least three beds in series. 
   
   
       8 . A scalable purification system according to  claim 1  wherein the plurality of molecular sieve beds includes at least one bed with varying cross-sectional diameter along the length of the bed.