Process to remove product alcohol from a fermentation by vaporization under vacuum

Abstract

A fermentation liquid feed including water and a product alcohol and optionally CO 2 is at least partially vaporized such that a vapor stream is produced. The vapor stream is contacted with an absorption liquid under suitable conditions wherein an amount of the product alcohol is absorbed. The portion of the vapor stream that is absorbed can include an amount of each of the water, the product alcohol and optionally the CO 2 . The temperature at the onset of the absorption of the vapor stream into the absorption liquid can be greater than the temperature at the onset of condensation of the vapor stream in the absence of the absorption liquid. The product alcohol can be separated from the absorption liquid whereby the absorption liquid is regenerated. The absorption liquid can include a water soluble organic molecule such as an amine.

1 - 18 . (canceled) 
     
     
         19 . A method for maintaining the titer of product alcohol in a fermentation vessel below a preselected threshold, the method comprising:
 (a) removing from a fermentation vessel a fermentation liquid feed stream produced from a fermentation in the fermentation vessel, the fermentation liquid feed stream comprising product alcohol, water, and optionally CO 2 ;   (b) supplying the fermentation liquid feed stream to a flash tank or a distillation column;   (c) at least partially vaporizing under vacuum conditions the fermentation liquid feed stream in the flash tank or the distillation column to produce a vapor stream enriched in product alcohol and a bottoms stream depleted in product alcohol;   (d) optionally returning any portion of the bottoms stream to the fermentation vessel; and   (e) contacting the vapor stream with an absorption liquid under vacuum conditions; wherein at least a portion of the vapor stream is absorbed into the absorption liquid,   wherein heat of absorption generated by the contacting step (e) is used in the vaporizing step (c) at least partially vaporizing the fermentation liquid feed.   
     
     
         20 . The method of  claim 19 , wherein the flash tank is a single-stage flash tank or the distillation column is a multi-stage distillation column. 
     
     
         21 . The method of  claim 19 , wherein the temperature at the onset of the absorption of the vapor stream into the absorption liquid is greater than the temperature at the onset of condensation of the vapor stream in the absence of the absorption liquid. 
     
     
         22 . The method of  claim 19 , wherein step (e) further comprises optionally forming a residual vapor phase. 
     
     
         23 . The method of  claim 19 , wherein the product alcohol is butanol. 
     
     
         24 . The method of  claim 23 , wherein the product alcohol is isobutanol. 
     
     
         25 . The method of  claim 19 , wherein the absorption liquid is ethylene glycol, ethylene glycol monomethyl ether, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycols, polyethylene glycol ethers, polypropylene glycol ethers, or mixtures thereof. 
     
     
         26 . The method of  claim 19 , wherein the absorption liquid is monoethanolamine, methylaminopropylamine, piperazine, diethanolamine, triethanolamine, diethylethanolamine, diisopropylamine, aminoethoxyethanol, dimethylaminopropanol, methyldiethanolamine, or mixtures thereof. 
     
     
         27 . The method of  claim 19 , wherein the absorption liquid is 2-ethyl hexanol, isolauryl alcohol, isocetyl alcohol, oleyl alcohol, phenol, fatty acids, fatty esters, fatty alcohols, acids, alcohols, amides, amines, esters, ketones, carbonates, phosphates, salt solutions, or mixtures thereof. 
     
     
         28 . The method of  claim 19 , wherein the absorption liquid is potassium carbonate in ethylene glycol solution. 
     
     
         29 . The method of  claim 19 , wherein the fermentation liquid feed stream comprises CO 2 . 
     
     
         30 . The method of  claim 29 , further comprising, prior to the (c) vaporizing step, one or both of (i) gas stripping a portion of the CO 2  from the fermentation liquid feed and (ii) vaporizing a portion of the CO 2  from the fermentation liquid feed. 
     
     
         31 . The method of  claim 30 , wherein a portion of the CO 2  from the fermentation liquid feed is gas stripped from the fermentation liquid feed prior to the (c) vaporizing step, where the portion of the CO 2  is gas stripped by countercurrent contact of the fermentation liquid feed with a noncondensible gas. 
     
     
         32 . The method of  claim 29 , further comprising, prior to the (c) vaporizing step, gas stripping a substantial portion of the CO 2  and a portion of product alcohol from the fermentation liquid feed and vaporizing a portion of the CO 2  from the fermentation liquid feed. 
     
     
         33 . The method of  claim 19 , wherein the method is initiated concurrently with initiation of the fermentation producing the fermentation liquid feed stream. 
     
     
         34 . The method of  claim 19 , wherein the product alcohol is produced by a microorganism. 
     
     
         35 . The method of  claim 34 , wherein the microorganism is a recombinant microorganism. 
     
     
         36 . The method of  claim 35 , wherein the recombinant microorganism is engineered to express a biosynthetic pathway to produce the product alcohol. 
     
     
         37 . The method of  claim 34 , wherein the microorganism is bacteria, cyanobacteria, filamentous fungi, or yeast. 
     
     
         38 . The method of  claim 37 , wherein the microorganism is selected from the group consisting of  Clostridium, Zymomonas, Escherichia, Salmonella, Serratia, Erwinia, Shigella, Rhodococcus, Pseudomonas, Bacillus, Lactobacillus, Enterococcus, Pediococcus, Alcaligenes, Klebsiella, Paenibacillus, Arthrobacter, Corynebacterium, Brevibacterium, Pichia, Yarrowia, Candida, Hansenula, Kluyveromyces, Issatchenkia, Schizosaccharomyces , and  Saccharomyces.