Conical Bioreactor for Hydrogen Dissolution and Safety
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Solution Overview
Problem
Current bioreactors are unsuitable for large-scale aerobic fermentation of microbial protein production from molecular hydrogen due to the explosive risks associated with the combination of hydrogen and oxygen, low hydrogen dissolution rates, and biomass sedimentation issues, which limit process efficiency and scalability.
Innovation Solution
A bioreactor design featuring a conical intermediate part and circular flow of fermentation broth to enhance hydrogen dissolution, combined with a gas switch system to prevent simultaneous hydrogen and oxygen inlet, minimizing explosive risks and optimizing gas distribution for efficient microbial protein production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If molecular hydrogen and molecular oxygen are supplied simultaneously to the bioreactor, then microbial protein production is enhanced, but explosive risks increase significantly
Solution Approach 1:
The bioreactor is divided into distinct functional zones: an upper reaction zone where microbial protein production occurs, and a lower gas mixing zone where hydrogen and oxygen are mixed before controlled introduction. This spatial segmentation allows the harmful explosive mixture to be contained and controlled in a specific region while the productive fermentation occurs in a separate safe zone.
Solution Approach 2:
A gas switch system acts as an intermediary control mechanism between the hydrogen and oxygen supply lines and the bioreactor. This intermediary device prevents direct simultaneous introduction of both gases, allowing controlled alternation or proportional mixing while eliminating the risk of uncontrolled explosive mixture formation.
2Productivity
If high quantities of hydrogen are supplied to enhance microbial protein production, then process efficiency is improved, but hydrogen dissolution becomes the limiting factor
Solution Approach 1:
The bioreactor introduces a circulation dimension by incorporating a pump that continuously circulates the fermentation broth from the bottom to the top and back. This creates multiple passes through the gas-liquid interface, effectively increasing the contact time and surface area for hydrogen dissolution without increasing the reactor volume or hydrogen supply quantity.
Solution Approach 2:
The gas switch system implements periodic action by alternately introducing hydrogen and oxygen or controlling their proportional mixing in cycles. This periodic gas supply pattern prevents gas accumulation, maintains optimal partial pressures, and enhances dissolution rates by creating dynamic gas-liquid interfaces rather than static conditions.
3Ease of operation
If conventional stirred tank reactors are used for hydrogen-based fermentation, then operation is simplified, but hydrogen escape and contamination risks increase
Solution Approach 1:
The bioreactor replaces static conventional stirred tank design with dynamic gas switching and broth circulation systems. The pump continuously moves broth through the reactor, and the gas switch dynamically adjusts gas introduction patterns. These dynamic elements actively control hydrogen dissolution and prevent escape without requiring complex mechanical stirring apparatus.
4Productivity
If biomass accumulates at the hydrogen inlet, then microbial growth is enhanced, but gas distribution is blocked and process efficiency decreases
Solution Approach 1:
The design extracts the gas distribution function from the reactor inlet region by implementing a separate lower gas mixing zone. Biomass that accumulates in the upper reaction zone does not block the gas distribution system, as gases are introduced and mixed in a dedicated lower region before broth circulation carries them through the reaction zone. This separation of functions prevents biomass from interfering with gas distribution.
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
The bioreactor achieves high hydrogen dissolution rates, reducing hydrogen escape to less than 5% and enabling efficient production of high-quality single cell protein with up to 70% protein content, while minimizing contamination and allowing continuous operation, thus enhancing process safety and efficiency.
Implementation Method 1
hydrogen dissolution is the limiting factor in fermentations to obtain microbial protein, and achieving higher hydrogen dissolution would enhance process efficiency and scale
Implementation Method 2
achieving higher hydrogen dissolution would enhance process efficiency and scale. It is however difficult to achieve a high enough transfer rate of hydrogen from the gaseous phase to the culture medium
Implementation Method 3
The combination of molecular oxygen and molecular hydrogen generally creates a highly explosive mixture. Common bioreactors are not suitable for such use, due to the high explosive risks.
Data Source
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AI summary
The invention pertains to a bioreactor for aerobic hydrogenotrophic fermentation. The bioreactor of the invention has a first gas inlet located at the bottom part of the reactor, and is adapted to provide flow of the reactor contents which effectively slows the rising of the hydrogen bubbles. The bioreactor further features a conical shape, configured to provide decreasing flow of the reactor contents at lower height. The invention further pertains to a method for the production of biomass, using the described reactor.