Axial Jet Mill Internal Structure for Fine Particle Grinding
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Solution Overview
Problem
Conventional axial jet mills are inefficient in achieving fine particle sizes required for modern pharmaceutical and biopharmaceutical products, as larger diameter mills fail to produce fine particles due to insufficient kinetic energy at the nozzles, while smaller diameter mills are less efficient in processing large volumes.
Innovation Solution
The jet mill design features a housing with an annular raceway and nozzles that project high-velocity gas jets inward, an internal structure to confine particles close to the nozzles, and a raceway for circulating gas and particles, enhancing collisions and size reduction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If larger diameter axial jet mills are used, then processing capacity is improved, but particle size reduction efficiency deteriorates
Solution Approach 1:
The housing is divided into a grinding chamber and a separation chamber by an internal structure. The grinding chamber contains the annular raceway where particle size reduction occurs, while the separation chamber collects comminuted particles. This segmentation allows the grinding zone to be optimized for fine particle production while maintaining overall processing capacity.
Solution Approach 2:
The internal structure creates a localized grinding zone within the annular raceway where particles are confined close to the nozzles. This local concentration of particles in the high kinetic energy zone ensures fine particle size reduction occurs efficiently in this specific region, while the rest of the housing can accommodate larger volumes for higher throughput.
2Manufacturing precision
If smaller diameter axial jet mills are used, then particle size reduction efficiency is improved, but processing capacity deteriorates
Solution Approach 1:
The invention transitions from a conventional single-chamber axial jet mill to a two-chamber design with distinct grinding and separation zones. This dimensional reorganization allows the grinding chamber to be optimized for fine particle production while the separation chamber accommodates the volume needed for high throughput, effectively decoupling particle size reduction efficiency from processing capacity.
3Speed
If particles move rapidly inward to locations remote from nozzles, then circulation efficiency is improved, but kinetic energy availability deteriorates
Solution Approach 1:
The internal structure acts as an intermediary that confines particles within the annular raceway close to the nozzles. By preventing particles from moving rapidly inward to remote locations, the internal structure ensures particles remain in the high kinetic energy zone where gas streams can effectively comminute them, while still maintaining circulation through the controlled raceway path.
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 achieves fine particle distributions at higher throughput rates, surpassing the limitations of conventional axial jet mills by maintaining particles in proximity to high kinetic energy zones, enabling efficient grinding and micronization.
Implementation Method 1
The nozzles are disposed around the perimeter of the outer wall, and project jets of gas at high velocity inward through the outer wall
Implementation Method 2
The jets of gas hurl particles circulating in the raceway against one another, and also against the wall of the internal structure
Implementation Method 3
The internal structure limits inward movement of particles of solid material toward the central axis, and thereby increases the concentration of the particles of solid material in close proximity to the nozzles, where the kinetic energy of the gas streams is at its maximum
Data Source
AI summary
In an axial jet mill, an internal structure having a cylindrical outer surface is positioned within a housing to establish a raceway for the circulating movement of gas and solid material while maintaining the gas and solid material in close proximity to the outlets of gas nozzles distributed around the perimeter of the raceway. Solid material enters the jet mill though a bottom wall of the housing and passes into the raceway though gaps between the bottom of the internal structure and a bottom wall of the housing. Particles and gas exit the jet mill though a central outlet in the housing located above the internal structure.