Anaerobic Fermentation Column Reactor for Biofuel Separation
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Solution Overview
Problem
Current biological processes for producing biofuels like lipids and hydrocarbons face challenges in scalability, cost, and efficiency, particularly in separating the products from fermentation broths without external electron acceptors like oxygen, leading to inefficient carbon dioxide and gas production, and requiring complex separation techniques.
Innovation Solution
A continuous anaerobic fermentation process using micro-organisms in a column reactor with upward flowing aqueous medium, where fermentation gas is separated prior to product separation, promoting coalescence using SLL separation techniques like gravity settling, flotation, or hydrocyclones, and tilted plate separators, to enhance the recovery of lipids or hydrocarbons as a separate liquid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional stirred fermentors with centrifugal separation are used, then product separation is achieved, but capital investment and energy costs are high
Solution Approach 1:
The fermentation process is segmented into distinct zones within the column reactor: an anaerobic fermentation zone at the bottom and an aerobic oxidation zone at the top. This segmentation allows simultaneous product formation and gas separation, eliminating the need for separate centrifugal separation equipment and reducing capital investment while maintaining high productivity.
Solution Approach 2:
The column reactor performs multiple functions simultaneously: it serves as both the fermentation vessel and the gas-liquid separation device. The upward flow of aqueous medium through the packed bed enables both substrate delivery to microorganisms and efficient gas removal, consolidating what would traditionally require separate equipment into a single integrated system.
2Ease of manufacture
If anaerobic fermentation without external electron acceptor is used, then fuel purification costs are reduced, but fermentation gas production requires complex mixing devices
Solution Approach 1:
The system uses the fermentation gas produced during anaerobic fermentation as the driving force for its own circulation and separation. The gas generated by microorganisms naturally flows upward through the packed bed, carrying aqueous medium and product droplets to the oxidation zone, eliminating the need for external mixing devices or mechanical agitation systems.
Solution Approach 2:
The process utilizes pneumatic principles where fermentation gas flow drives the circulation of aqueous medium through the column reactor. The gas-liquid flow dynamics naturally achieve mixing and mass transfer functions that would otherwise require mechanical devices, simplifying the overall system architecture.
3Productivity
If fermentation gas is produced in substantial amounts, then turbulent mixing is achieved without separate mixing devices, but gas-liquid separation becomes more difficult
Solution Approach 1:
The reactor is divided into anaerobic and aerobic zones, with the aerobic zone specifically designed for gas-liquid separation. The packed bed structure in the oxidation zone provides large surface area for gas absorption and liquid redistribution, efficiently separating fermentation gas from the aqueous medium without requiring additional separation equipment.
Solution Approach 2:
The process transitions from horizontal mixing in a stirred tank to vertical countercurrent flow in a column reactor. The upward flow of liquid and downward flow of gas create efficient mass transfer and separation in the vertical dimension, utilizing the packed bed structure to achieve both mixing and separation functions simultaneously.
4Ease of manufacture
If upflow packed bed column reactor is used, then investment costs are reduced, but product coalescence and separation require optimized conditions
Solution Approach 1:
The process optimizes several parameters to achieve effective product separation: controlling the upward flow rate of aqueous medium, adjusting the packed bed height and particle size, and regulating the gas flow rate. These parameter changes create optimal conditions for droplet coalescence and phase separation in the oxidation zone without requiring complex or expensive equipment.
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 a cost-effective, integrated bioreactor system for direct production of biofuels from renewable sources, reducing investment and operational costs by minimizing surplus cell mass and using inexpensive reactor materials, while achieving high yields and efficient separation of biofuels without the need for separate mixing devices or expensive equipment.
Implementation Method 1
separating the product from each other under conditions that coalescence of the product is promoted, wherein the fermentation gas is at least partly separated from the aqueous medium prior to separating the product from the aqueous phase wherein SLL (i.e. solid-liquid-liquid) separation techniques are used for promoting the coalescence of the product droplets
Implementation Method 2
SLL separation techniques including gravity settling, flotation or a combination thereof
Data Source
Figure 1~2
Figure 3
AI summary
The present invention is directed to a process for the continuous biological production of lipids, hydrocarbons, hydrocarbon like material or mixtures thereof by conversion of a suitable substrate using micro-organisms, in which process the said substrate is continuously, anaerobically fermented to produce lipids, hydrocarbons, hydrocarbon like material or mixtures thereof and fermentation gas, in the presence of, optionally supported, micro-organisms in an aqueous medium in a column type reactor, in which reactor at least part of the aqueous medium flows in upward direction, and recovering the lipids, hydrocarbon or hydrocarbon like material by separating the fermentation gas, the micro-organisms, the lipids, hydrocarbon or hydrocarbon like material from each other under conditions that coalescence of the hydrocarbon material or hydrocarbon like material is promoted.