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 - 27 . (canceled) 
     
     
         28 . A method for removing a product alcohol from a fermentation liquid, comprising:
 (a) at least partially vaporizing a fermentation liquid wherein a vapor stream is produced, the fermentation liquid and the vapor stream each comprising an amount of water, butanol, and optionally CO 2 ; and   (b) 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 to form an absorption liquid phase,   wherein the portion of the vapor stream that is absorbed includes an amount of each of the water and the butanol, and optionally CO 2 , and   wherein temperature at the onset of the absorption of the vapor stream into the absorption liquid is greater than temperature at the onset of condensation of the vapor stream in the absence of the absorption liquid.   
     
     
         29 . The method of  claim 28 , wherein the absorption liquid comprises a water soluble organic molecule with a boiling point at least about 30° C. greater than the boiling point of water at atmospheric pressure. 
     
     
         30 . The method of  claim 28 , wherein the organic molecule is an amine selected from the group consisting of monoethanolamine (MEA), 2-amino 2-methyl propanol (AMP), and methyldiethanolamine (MDEA). 
     
     
         31 . The method of  claim 28 , wherein the absorption liquid comprises ethylene glycol. 
     
     
         32 . The method of  claim 28 , wherein the (a) vaporizing comprises:
 (i) removing the fermentation liquid feed from a fermentation vessel;   (ii) supplying the fermentation liquid feed to a multi-stage distillation column at a flow rate;   (iii) distilling the fermentation liquid feed to produce the vapor stream enriched in butanol and a bottoms stream depleted in the product alcohol, wherein the distilling occurs under a pressure sufficiently below atmospheric to allow for the vapor stream to be produced at a temperature no greater than about 45° C.; and   (iv) optionally, returning any portion of the bottoms stream to the fermentation vessel, wherein the concentration of the product alcohol in the bottoms stream is not more than about 90% of the concentration of the product alcohol in the fermentation liquid feed.   
     
     
         33 . The method of  claim 32 , wherein the fermentation liquid comprises CO 2 , wherein the (a) vaporizing step further comprises, prior to the (ii) supplying step, of gas stripping a portion of the CO 2  from the fermentation liquid feed and vaporizing a portion of the CO 2  from the fermentation liquid feed. 
     
     
         34 . (canceled) 
     
     
         35 . 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 single stage flash tank or a multi-stage distillation column;   (c) at least partially vaporizing under vacuum conditions the fermentation liquid feed stream in the single stage flash tank or the multi-stage 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 the absorption liquid comprises a water soluble organic molecule different from the product alcohol. 
     
     
         36 . The method of  claim 35 , 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. 
     
     
         37 . The method of  claim 36 , wherein the concentration of product alcohol in the bottoms stream is less than about 90% of the concentration of product alcohol in the fermentation liquid feed stream. 
     
     
         38 . The method of  claim 37 , wherein the concentration of product alcohol in the bottoms stream is less than about 10% of the concentration of product alcohol in the fermentation liquid feed stream. 
     
     
         39 . The method of  claim 35 , wherein the organic molecule is an amine. 
     
     
         40 . The method of  claim 35 , wherein the organic molecule is ethylene glycol. 
     
     
         41 . The method of  claim 35 , wherein the concentration of product alcohol of the bottoms stream is less than about 2.5 g/L. 
     
     
         42 . The method of  claim 35 , wherein the fermentation liquid feed stream comprises CO 2 . 
     
     
         43 . The method of  claim 35 , wherein the method is initiated when the product alcohol in the fermentation vessel reaches about 10 g/L. 
     
     
         44 . The method of  claim 35 , wherein the method is initiated concurrently with initiation of the fermentation producing the fermentation liquid feed stream. 
     
     
         45 . The method of  claim 35 , further comprising:
 repeating steps (a)-(d) such that the product alcohol in the fermentation vessel is maintained at less than about 40 g/L during the fermentation in the fermentation vessel.   
     
     
         46 . A method of recovering a product alcohol from an absorption liquid phase and regenerating the absorption liquid phase, comprising:
 (a) pumping from an absorber an absorption liquid phase comprising an absorption liquid, water, product alcohol, and optionally CO 2 , to a higher pressure than a pressure in the absorber;   (b) optionally, heating the absorption liquid phase;   (c) feeding the absorption liquid phase to a multi-stage distillation column comprising a stripping section and optionally a rectification section;   (d) operating the distillation column under conditions such that a bottoms product comprising the absorption liquid and a vapor phase comprising a mixture of water, product alcohol, and optionally CO 2  are produced;   (e) recovering the bottoms product comprising the absorption liquid phase from the distillation column; and   (f) recovering the water, the product alcohol and optionally CO 2  from the vapor phase.   
     
     
         47 . The method of  claim 46 , further comprising:
 (g) causing to be separated the constituent parts of the vapor phase from (f) by condensation, distillation, decantation, or a combination thereof.   
     
     
         48 . The method of  claim 46 , further comprising:
 (g) at least partially condensing the vapor phase produced in step (d) to form a two liquid phase mixture;   (h) passing the liquid phase mixture to a decanter wherein the liquid phase mixture is separated into an aqueous phase and an organic phase   (i) passing at least portion of the aqueous phase to the rectification section of the distillation column of step (c);   (j) removing a liquid side stream from the rectification section of the distillation column and returning it to a vacuum flash vessel configured to receive a fermentation liquid feed stream comprising product alcohol, water, and optionally CO 2 ;   (k) passing at least a portion of the organic phase to a second distillation column comprising a stripping section;   (l) withdrawing a product alcohol from a bottom of the second distillation column;   (m) withdrawing vapors from a top of the second distillation column;   (n) causing the vapors from (m) to be cooled so that the vapors partially condense to form two liquid phases; and   (o) passing the liquid phases from (n) to a decanter.   
     
     
         49 - 52 . (canceled) 
     
     
         53 . The method of claim  52 , wherein said vapor streams are 10 to 100 parts by mass butanol to one part carbon dioxide. 
     
     
         54 . The method of  claim 46 , wherein the pressure of the vapor phase comprises 1 to 100 parts by mass butanol to one part carbon dioxide and the pressure is 1 to 30 psig. 
     
     
         55 . The method of  claim 54 , wherein said pressure is 0.9 to 1.2 atmospheres. 
     
     
         56 . A vapor stream of claim  52 . 
     
     
         57 . (canceled)