Bioreactor Impeller Design for Dissolved Oxygen Uniformity
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Solution Overview
Problem
Conventional bioreactors exhibit a concentration gradient in dissolved oxygen levels across the vertical direction of a culture tank, leading to suboptimal culture environments due to uneven oxygen transfer rates, which can hinder cell growth and productivity.
Innovation Solution
The bioreactor design incorporates multiple impellers arranged in stages with increasing outside diameters and blade numbers or notched structures to enhance the mass transfer capacity coefficient (K L a) from the bottom to the top, ensuring a more uniform oxygen dissolving rate per unit volume, thereby reducing the difference in dissolved oxygen concentrations across the tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sparger is installed at the bottom of the culture tank, then the structure is simple and aeration control is easy, but the dissolved oxygen concentration becomes uneven in the vertical direction
Solution Approach 1:
The culture tank is divided into multiple vertical sections, each equipped with its own sparger. This segmentation allows independent control of oxygen supply in different zones, addressing the dissolved oxygen concentration gradient that occurs with a single bottom sparger.
Solution Approach 2:
Different spargers are positioned at specific vertical locations (e.g., bottom, middle, upper sections) to provide localized oxygen supplementation where needed. This creates non-uniform oxygen distribution patterns that compensate for the natural depletion gradient, maintaining more uniform dissolved oxygen levels throughout the tank.
2Stability of the object's composition
If multiple spargers are installed at different vertical positions to prevent dissolved oxygen concentration decrease, then the dissolved oxygen concentration uniformity is improved, but the structure becomes complicated and aeration control becomes complex
Solution Approach 1:
Multiple spargers are integrated into a unified aeration control system with centralized control logic. The spargers work cooperatively as a single system rather than independent units, simplifying control by managing them collectively through one control unit that coordinates their operation based on overall dissolved oxygen requirements.
Solution Approach 2:
The multi-position sparger system serves multiple functions: it provides oxygen supplementation at different vertical zones, compensates for oxygen depletion gradients, and maintains uniform dissolved oxygen distribution throughout the culture tank. This multi-functional design justifies the increased structural complexity by delivering comprehensive oxygen management.
3Stability of the object's composition
If multiple spargers are installed at different vertical positions to maintain dissolved oxygen concentration, then the dissolved oxygen concentration uniformity is improved, but the aeration control complexity increases
Solution Approach 1:
The aeration control system incorporates feedback mechanisms that automatically adjust sparger operation based on measured dissolved oxygen levels. The system self-regulates by sensing oxygen concentration variations and modulating sparger activity accordingly, reducing the need for manual intervention and simplifying operational control despite the multi-sparger configuration.
Solution Approach 2:
Dissolved oxygen sensors provide real-time feedback to the control unit, which then adjusts the operation of multiple spargers to maintain target oxygen levels. This closed-loop control system coordinates the complex multi-sparger setup by using oxygen concentration measurements to guide aeration adjustments, making the system easier to operate.
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 configuration achieves a more uniform distribution of dissolved oxygen concentrations, enhancing cell growth rates and productivity by maintaining a consistent oxygen environment throughout the culture tank, while simplifying aeration control and reducing operational complexity.
Implementation Method 1
oxygen gas in bubbles dissolves into a liquid and becomes dissolved oxygen
Implementation Method 2
providing agitation to the tank using an impeller
Implementation Method 3
microorganisms absorb the dissolved oxygen at a constant uptake rate
Data Source
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AI summary
The present invention achieves a smaller difference between a dissolved oxygen concentration in an upper part of a culture tank and a dissolved oxygen concentration in a lower part of the culture tank. The present invention comprises: a culture tank; a sparger means arranged in a lower part of the culture tank; and multiple impellers being arranged in multiple stages in a vertical direction of the culture tank and having a larger mass transfer capacity coefficient KLa per unit number of revolutions in an upper stage than in a lower stage.