Vacuum Vaporization Absorption for Butanol Recovery
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Solution Overview
Problem
Current industrial fermentation processes face challenges in efficiently removing butanol from fermentation broths without exceeding the butanol tolerance threshold of microorganisms, leading to economic inefficiencies due to limited sugar loadings and high cooling costs, especially when processing low-pressure vapor streams containing butanol and CO2.
Innovation Solution
The method involves partially vaporizing a fermentation liquid feed under vacuum conditions to produce a vapor stream enriched in butanol, which is then contacted with an absorption liquid, such as monoethanolamine or ethylene glycol, to absorb the butanol and CO2, allowing for regeneration of the absorption liquid and recovery of the butanol, thereby maintaining butanol levels below the tolerance threshold and reducing cooling costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If butanol is removed from fermentation broth by conventional vacuum vaporization, then butanol recovery is achieved, but high cooling costs are incurred due to the need to condense large volumes of vapor stream
Solution Approach 1:
The patent introduces an absorption liquid as an intermediary substance that selectively absorbs butanol from the vapor stream. This mediator enables butanol recovery without requiring complete condensation of the vapor stream, thereby reducing the cooling energy required. The absorption liquid transfers butanol from the gas phase to liquid phase through mass transfer, bypassing the need for energy-intensive condensation of the entire vapor stream.
Solution Approach 2:
The patent changes the physical parameters of the system by operating the absorption process at elevated temperatures (above the dew point of the vapor stream). This parameter change allows butanol to be absorbed in the liquid phase at temperatures where it would normally condense, enabling energy-efficient separation without requiring the vapor stream to be cooled to its dew point for condensation.
2Productivity
If sugar loading is increased to improve productivity, then fermentation efficiency increases, but butanol tolerance threshold is exceeded causing production rate to fall
Solution Approach 1:
The patent applies preliminary action by removing butanol from the fermentation broth during the fermentation process itself, before the butanol concentration reaches the tolerance threshold that would inhibit further production. This continuous or periodic removal during fermentation allows high sugar loadings to be used without exceeding the microorganism's butanol tolerance, thereby maintaining high productivity throughout the fermentation process.
Solution Approach 2:
The system implements feedback control where butanol removal is adjusted based on the butanol concentration in the fermentation broth. When butanol approaches the tolerance threshold, removal is intensified; when concentration is lower, removal is reduced. This feedback mechanism allows optimal sugar loading to be maintained while preventing butanol accumulation that would inhibit production.
3Temperature
If vapor stream is compressed to higher pressure to enable condensation, then condensation can be performed against cooling water, but significant compression costs are incurred due to low vapor density
Solution Approach 1:
The absorption liquid serves as a mediator that enables butanol separation at the original low pressure of the vapor stream. By introducing this intermediary substance, the system avoids the need for compression to increase vapor density for condensation. The absorption process occurs directly at the vacuum or low pressure conditions, eliminating the energy-intensive compression step while still achieving effective butanol recovery.
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 effectively recovers butanol while maintaining optimal fermentation conditions, reducing the need for high cooling costs and minimizing the impact on microorganism productivity, and allows for efficient regeneration of the absorption liquid, thus enhancing the economic viability of the fermentation process.
Implementation Method 1
a fermentation liquid feed comprising water and a product alcohol and optionally CO2 is at least partially vaporized such that a vapor stream is produced
Implementation Method 2
Process to remove product alcohol from a fermentation by vaporization under vacuum
Implementation Method 3
the vapor stream containing the product alcohol is contacted with an absorption liquid under suitable conditions wherein an amount of the product alcohol is absorbed
Data Source
AI summary
A fermentation liquid feed including water and a product alcohol and optionally CO2 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 CO2. 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.