In Situ Butanol Removal via Stripping and Absorption
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Solution Overview
Problem
Current butanol fermentation processes face challenges in maintaining butanol concentrations below the tolerance level of microorganisms, leading to reduced productivity and economic inefficiencies, especially when high sugar loadings are used, as simple distillation can damage microorganisms.
Innovation Solution
A two-stage In situ Product Removal (ISPR) process involving stripping and absorption, where an inert gas is used to remove butanol from the fermentation broth, which is then absorbed by an organic liquid with lower vapor pressure, allowing for continuous recycling of microorganisms and maintaining butanol concentrations below toxic levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If simple distillation is used to remove butanol from fermentation broth, then butanol concentration can be reduced, but microorganisms are damaged by the temperature in the distillation column
Solution Approach 1:
The patent changes the operating parameters from high-temperature distillation to low-temperature stripping followed by absorption. The stripping process operates at temperatures compatible with microorganism survival, and the absorption process occurs at ambient or controlled temperatures, thereby removing butanol without damaging microorganisms
Solution Approach 2:
The patent introduces an absorbent as an intermediary substance to transfer butanol from the fermentation broth. The absorbent selectively absorbs butanol from the stripped gas stream, enabling indirect removal that protects microorganisms from direct exposure to harsh separation conditions
2Productivity
If high sugar loadings are used in fermentation, then productivity and economics are improved, but butanol titer reaches tolerance level causing production rate to fall
Solution Approach 1:
The patent implements continuous removal of butanol during the fermentation process through integrated stripping and absorption. This continuous action maintains butanol concentration below the tolerance level throughout fermentation, allowing high sugar loadings to be utilized without hitting the production rate limitation
Solution Approach 2:
The patent extracts butanol from the fermentation broth using a two-stage process: first stripping butanol from the liquid phase into the gas phase, then absorbing it into an absorbent. This extraction prevents butanol accumulation to toxic levels, enabling sustained high-rate production
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process enables efficient butanol fermentation by maintaining butanol concentrations below toxic levels, allowing for high sugar loadings and minimizing microorganism and sugar loss, thereby enhancing process economics and microorganism viability.
Implementation Method 1
feeding the removed fermentation broth into a stripping section of an apparatus in which said stripping section is in gaseous communication, but not liquid communication, with an associated absorption section
Implementation Method 2
continuously feeding into the absorption section of step (d) an organic liquid absorbent having a lower vapor pressure than that of butanol and an ability to absorb butanol
Data Source
AI summary
The present invention relates to a two stage process to control the butanol concentration from fermentation broth.