Protein Mixing with a 10-Inch Impeller Under Shear Limits
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Solution Overview
Problem
Therapeutic products containing proteins are susceptible to shear stresses during ultrafiltration/diafiltration processes, requiring impeller changes that cause significant downtime and safety concerns when switching product lines.
Innovation Solution
A method using a 10-inch blade diameter impeller to mix liquid compositions, maintaining maximum shear stress below 125,000 s−1, with power/flow number ratios less than 1, and operating at less than 250 rpm to achieve homogeneous mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a larger impeller (10 inch blade diameter) is used to achieve homogeneous mixing, then mixing homogeneity is improved, but shear stress on the protein product increases and may damage the product structure
Solution Approach 1:
The patent changes the operational parameters of the impeller system by specifying a maximum shear stress threshold (125,000 s⁻¹) and corresponding rpm limits (less than 250 rpm) for the 10-inch impeller. This allows the system to operate with a larger impeller for better mixing while controlling the shear stress through parameter optimization rather than changing the impeller size itself.
2Object-affected harmful factors
If the impeller size is changed to accommodate different product susceptibility to shear stress, then product safety is improved, but manufacturing downtime increases due to impeller changes, cleaning, and testing
Solution Approach 1:
The patent establishes a universal operating protocol that allows a single 10-inch impeller to safely mix multiple different protein products by controlling rpm based on product-specific shear stress thresholds. This eliminates the need to physically change impellers for different products, as the same impeller can be used universally with adjusted operational parameters.
Solution Approach 2:
The patent introduces dynamic adjustment of impeller speed based on the specific product being mixed. Rather than using a fixed impeller size for all products, the system dynamically adapts the rpm setting according to each product's shear stress susceptibility, allowing flexible accommodation of different products without physical reconfiguration.
3Ease of operation
If user entry protocols are avoided by using a fixed impeller configuration, then safety is improved, but adaptability to different products decreases
Solution Approach 1:
The patent maintains a fixed physical impeller configuration (10-inch diameter) for safety while achieving adaptability through parameter changes in operational speed. The system can accommodate different products by adjusting the rpm parameter according to each product's mixing requirements and shear stress tolerance, eliminating the need for user entry without sacrificing versatility.
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 method provides a more homogeneous mixture with reduced shear stress, lower power consumption, and improved safety by avoiding impeller changes, while maintaining product quality.
Implementation Method 1
Therapeutic products containing proteins are susceptible to shear stresses, which can damage the protein structure of the product
Implementation Method 2
operating the impeller can include maintaining a volume average turbulence kinetic energy (TKE) of at least 0.005 m2/s2
Data Source
AI summary
Methods for mixing fluids including etanercept include providing a tank having an impeller with a 10 inch blade diameter disposed therein, filling a tank with a liquid composition comprising etanercept and one or more buffers to a level within the tank to cover the impeller, and operating the impeller to mix the liquid composition to a homogeneous state while maintaining a maximum shear stress imparted on the mixture of fluids at 125,000 s−1 or below.