Impeller-Surround Insert for Low-Volume Stirred Tank Mixing
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Solution Overview
Problem
Existing mixers and bioreactors have fixed turndown ratios, leading to unsuitable minimum working volumes for lower fluid volumes, necessitating additional biological materials and equipment, which increases operating costs.
Innovation Solution
A modular apparatus and method for a stirred tank mixer/bioreactor that includes a body with an interior portion to receive and partially surround the impeller, allowing fluid exit through a side opening and drain, enabling adjustable minimum working volume by addition or removal of the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large stirred tank is used to accommodate maximum working volume, then the maximum production capacity is improved, but the minimum working volume becomes too large for processing lower volumes, reducing operational flexibility
Solution Approach 1:
The stirred tank is divided into two main segments: a removable body portion containing the impeller and a fixed base portion. This segmentation allows the body to be removed when processing small volumes, effectively reducing the minimum working volume, while the base portion remains to maintain maximum capacity when needed. The system thus adapts between large and small volume operations using a single tank.
2Adaptability or versatility
If the minimum working volume is reduced to allow lower fluid volumes, then operational flexibility is improved, but the mixing effectiveness may deteriorate due to insufficient submersion of the impeller
Solution Approach 1:
The system dynamically adjusts the impeller submersion depth by removing the body portion when processing small volumes. This ensures that the impeller is always properly submerged relative to the actual fluid volume being processed, maintaining mixing effectiveness across the entire operating range from minimal to maximum volumes.
3Device complexity
If a fixed turndown ratio is maintained in existing reactors, then device simplicity is preserved, but additional reactors or larger facilities are required, increasing operating costs
Solution Approach 1:
The stirred tank is designed as a universal vessel that can handle both large and small volume operations within a single device. The removable body configuration enables the same tank to function effectively across a wide range of volumes, eliminating the need for multiple specialized reactors and reducing overall equipment requirements.
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 apparatus allows for flexible adjustment of the minimum working volume, reducing operational costs by minimizing the need for extra materials and equipment, while maintaining effective mixing performance.
Implementation Method 1
An impeller assembly that includes a rotating impeller having one or more blades is disposed within the bag and is used to stir or mix the fluid
Implementation Method 2
The stirred tank includes a drain configured to remove the bag and/or fluid from the tank
Data Source
AI summary
An apparatus for reducing a minimum working volume of a stirred tank includes a body having upper and lower surfaces, and an exterior profile shaped to closely fit within an interior of the stirred tank. The body including an interior portion extending through the body from the upper surface to the lower surface, the interior portion configured to receive and partially surround an impeller within the stirred tank, while allowing rotation of the impeller to agitate a fluid in the vessel when in use. The body further including an opening in a side surface of the body, the opening extending into the interior portion and configured to facilitate removal of fluid from the vessel when the stirred tank is in use, and to be removed from the stirred tank via a drain.