Mixing Impeller Power Monitoring for Fluid Density and Viscosity
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Solution Overview
Problem
Biopharmaceutical manufacturing requires a method to determine the density and viscosity of mixed components without additional instrumentation or sampling, especially in closed systems where contamination risks are high and traditional methods are not feasible.
Innovation Solution
A method involving the rotation of a mixing impeller at varying speeds to detect turbulent flow and calculate density and viscosity using power measurements and established relationships between Reynolds and Power numbers, without the need for additional instrumentation or sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mixing monitoring methods are used, then additional instrumentation or sampling is required, but this increases device complexity and contamination risk
Solution Approach 1:
The mixing impeller serves dual functions: it performs mixing while simultaneously measuring power consumption to determine fluid density and viscosity. The existing impeller system monitors its own performance parameters without requiring separate measurement devices, enabling the mixed components to essentially measure themselves through the impeller's power consumption characteristics at different rotation speeds.
Solution Approach 2:
The mixing impeller is designed to perform multiple functions: it provides mechanical mixing action while also serving as a measurement device for determining fluid density and viscosity through power consumption monitoring. This multi-functional approach eliminates the need for separate instrumentation and reduces overall system complexity.
2Measurement precision
If sampling methods are used to determine density and viscosity, then additional instrumentation is avoided, but contamination risk increases
Solution Approach 1:
The system performs self-measurement by monitoring the power consumption of the mixing impeller itself. No external sampling or additional instrumentation penetrates the closed system, eliminating contamination pathways while obtaining accurate density and viscosity data through the impeller's inherent operational characteristics.
Solution Approach 2:
The invention replaces mechanical sampling methods with a field-based measurement approach. Instead of physically extracting samples or inserting measurement probes into the mixture, the system uses power consumption monitoring and fluid dynamics calculations to determine density and viscosity, thereby maintaining system closure and preventing contamination.
3Object-affected harmful factors
If closed mixing systems are used, then contamination risk is reduced, but measurement of density and viscosity becomes more difficult
Solution Approach 1:
The invention replaces intrusive mechanical measurement methods with a non-intrusive power consumption monitoring approach. By measuring the electrical power required to rotate the impeller at controlled speeds and applying fluid dynamics relationships, the system determines density and viscosity while maintaining complete system closure and avoiding contamination risks.
Solution Approach 2:
The system varies the rotation speed parameter of the mixing impeller to obtain multiple power consumption measurements. By measuring power at different speeds and applying the relationship between power, speed, and fluid properties, the system calculates density and viscosity without requiring physical access to the mixture or breaking system closure.
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
Enables the determination of density and viscosity in a simple and cost-effective manner, ensuring accurate monitoring of flow behavior in biopharmaceutical mixing processes without exposing sensitive materials to contamination risks.
Implementation Method 1
detecting whether the difference between the first and second quantities is within a specified range to determine whether the flow of the components in the mixing vessel is a turbulent flow
Implementation Method 2
determining the density ρ of the mixed components based on at least one speed N i for which the flow is determined to be turbulent by the following formula: wherein ρ is the density, P i is the power required to turn the mixing impeller at the speed N i , N P,constant is the Power number for a used mixing system configuration
Implementation Method 3
determining the Power number N P,variable for at least one detected speed N j at which the flow is determined to be non-turbulent by the following formula: wherein P j is the power required to rotate the mixing impeller at the speed N j
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The present invention relates to a method of monitoring a flow behaviour of mixed components, comprising: rotating a mixing impeller at a first speed N1 in a mixing vessel accommodating the components to be mixed; determining a first quantity (formula I) at the first speed N1, wherein N1 is the speed at which the mixing impeller rotates and P1 is the power required to rotate the mixing impeller at the first speed N1; decreasing the speed of the mixing impeller to a speed N2; determining a second quantity (formula II) at the second speed N2, wherein N2 is the speed at which the mixing impeller rotates and P2 is the power required to rotate the mixing impeller at the second speed N2; comparing the first quantity (formula I) and the second quantity (formula II) and detecting whether the difference between the first and second quantities is within a specified range to determine whether the flow of the components in the mixing vessel is a turbulent flow; determining the density ρ of the mixed components based on at least one speed Ni for which the flow is determined to be turbulent by the formula (III) wherein ρ is the density, Pi is the power required to turn the mixing impeller at the speed Ni, NP,constant is the Power number for a used mixing system configuration, Ni is the speed at which the mixing impeller rotates and D is the diameter of the mixing impeller; further decreasing the speed of the mixing impeller; determining the Power number NP,variable for at least one detected speed Nj at which the flow is determined to be non-turbulent by the formula (IV) wherein Pj is the power required to rotate the mixing impeller at the speed Nj, ρ is the density previously determined based on NP,constant, Nj is the speed at which the mixing impeller rotates, and D is the diameter of the mixing impeller; and determining the dynamic viscosity μ of the mixed components by the formula (V) wherein ρ is the calculated density, Nj is the speed at which the mixing impeller rotates, D is the diameter of the mixing impeller, Pj is the power required to rotate the mixing impeller at the speed Nj and xT corresponds to a specified relationship between the Reynolds number for the used mixing system configuration and the determined Power number NP,variable. Further, the present invention relates to methods for detecting settled solids at a mixing impeller.