Counter-Rotating Shear Granulator for Binder Dispersion
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Solution Overview
Problem
Mixer-granulators face challenges in uniformly dispersing binders, especially high-viscosity ones, and controlling granule size distribution due to limitations in shear field design and over-consolidation, which affects the uniformity and quality of granulated products.
Innovation Solution
The shear-gap granulator system features counter-rotating shafts with impeller assemblies creating an extensional shear field in the gap between them, allowing for uniform binder dispersion and control over granule size distribution, with a modular design for scalability and easy cleaning, and a binder delivery system capable of handling viscous binders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional mixer-granulators use high-speed rotating blades to mix fine powder with liquid binder, then mixing speed and granulation efficiency are improved, but uniform binder dispersion is difficult to achieve especially with high-viscosity binders
Solution Approach 1:
The patent changes the fundamental mixing parameter from high-speed rotation to low-speed counter-rotating motion with high shear rate in the gap. This parameter transformation enables effective dispersion of high-viscosity binders without sacrificing granulation efficiency, as the intense localized shear in the narrow gap between counter-rotating elements overcomes binder viscosity while the overall low speed prevents over-mixing
Solution Approach 2:
The invention creates a localized high-shear zone in the gap between counter-rotating mixing elements where binder dispersion occurs most effectively. This local quality approach concentrates the mixing action precisely where needed - at the interface between powder and binder - rather than applying uniform mixing throughout the entire vessel, thereby achieving superior dispersion uniformity
2Manufacturing precision
If traditional mixer-granulators apply strong cutting and compression forces to break up granules, then granule size control is improved, but over-consolidation occurs affecting product uniformity
Solution Approach 1:
The patent transforms the mixing parameters from high speed with strong compression to low speed with high shear rate. This parameter change allows granule breakage to occur through shear forces in the gap rather than compression, achieving size distribution control without over-consolidation and maintaining product uniformity
Solution Approach 2:
The invention replaces the traditional mechanical compression and high-speed cutting action with a low-speed high-shear mechanism. The shear-dominated force system in the gap between counter-rotating elements substitutes for the compression-based breakage mechanism, preventing over-consolidation while maintaining effective granule size control
3Device complexity
If mixer-granulators use single shaft impeller design, then device simplicity is maintained, but binder dispersion uniformity and granule size control are insufficient
Solution Approach 1:
The patent divides the single impeller system into two counter-rotating elements, creating segmented mixing zones. This segmentation allows different functional regions - the high-shear gap for binder dispersion and the bulk zone for gentle mixing - thereby improving granule size distribution uniformity while maintaining relatively simple device structure
Solution Approach 2:
The invention introduces asymmetric counter-rotating motion between the two mixing elements, creating a dynamic shear field that enhances binder dispersion. This asymmetric rotation pattern generates more effective fluidization and mixing action compared to symmetric single-shaft designs, improving granule size control without excessive complexity
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 design effectively disperses binders of varying viscosities, ensuring uniform granule size and shape distribution, preventing over-consolidation, and enabling efficient processing of both batch and continuous operations.
Implementation Method 1
The extensional shear field in the gap is effective in uniformly dispersing the binder, enabling control over the granule size distribution
Implementation Method 2
fine powders can be first added to the mixer and mechanically fluidized by the impellers
Implementation Method 3
These systems use a combination of cutting and compression forces to effectively mix fine powder with binders and reduce the size of granules that have grown too large
Implementation Method 4
The material is fed into the machine and subjected to the compression forces between counter-rotating rollers
Data Source
AI summary
A mixing assembly includes a mixing basin, first and second pluralities of mixing paddles, and at least one motor. The mixing basin includes first and second parallel shafts extending therethrough. Each of the first and second pluralities of mixing paddles are positioned in an interior of the mixing basin. Each paddle of the first plurality of mixing paddles is coupled with the first shaft and configured to rotate about a first axis and each paddle of the second plurality of mixing paddles is coupled with the second shaft and configured to counter-rotate about a second axis. The counter-rotating mixing paddles are spaced apart to define a shear gap therebetween, and the motor is operable to drive the counter-rotation of the mixing paddles.