Jet Mill Nozzle Geometry and Pressure Control for Particle Size
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Solution Overview
Problem
Current methods for producing extremely fine particles using jet mills are not optimized for energetically efficient operation, limiting the effectiveness and efficiency of the process.
Innovation Solution
The method involves using a fluid bed jet mill with multiple grinding jet inlets arranged concentrically, a dynamic air classifier with a classifying rotor or wheel designed for constant flow area, and a fine material outlet chamber with cross-sectional expansion, optimizing the operation with compressed gases and temperature control to enhance particle decomposition and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional jet mill methods are used for producing extremely fine particles, then particle production is achieved, but energy efficiency is not optimized
Solution Approach 1:
The patent optimizes operating parameters including gas pressure (0.5-2.0 bar), gas flow rate (10-50 L/min), and nozzle geometry to achieve maximum energy efficiency. The relative jet length a/dnozzle is specifically controlled within 10-30 to optimize the interaction between grinding jets and particles, thereby improving energy utilization while maintaining high particle production effectiveness
Solution Approach 2:
The patent employs dynamic adjustment of operating conditions during the grinding process. The gas supply and nozzle configuration can be adapted based on material properties and desired particle size, allowing the system to operate at optimal energy efficiency points while maintaining high productivity across different production scenarios
2Manufacturing precision
If multiple grinding jet inlets are arranged concentrically, then particle decomposition is enhanced, but device complexity increases
Solution Approach 1:
The grinding system is divided into multiple independent jet inlets arranged concentrically, with each inlet capable of receiving grinding media and generating grinding jets. This segmentation allows enhanced particle decomposition through multiple simultaneous impact zones while maintaining a relatively simple overall structure that follows conventional jet mill design patterns
Solution Approach 2:
The concentrically arranged grinding jet inlets serve multiple functions: they create overlapping jet patterns for enhanced particle decomposition, provide adjustable grinding intensity through individual flow control, and maintain a compact configuration that minimizes device complexity. The same structural framework supports both simple single-jet and complex multi-jet operations
3Productivity
If a classifying wheel with constant flow area is used, then separation capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The classifying wheel is designed with a constant flow area configuration that maintains consistent separation performance across different operating conditions. The blade geometry and spacing are optimized to create uniform flow channels, improving separation capability while the design tolerances are set to accommodate standard manufacturing capabilities without requiring excessive precision
4Productivity
If the fine material outlet chamber has cross-sectional expansion, then particle collection is enhanced, but device complexity increases
Solution Approach 1:
The fine material outlet chamber incorporates cross-sectional expansion with smooth curved transitions that guide particles efficiently into the collection zone. The expanding geometry follows streamlined contours that minimize turbulence and maximize particle collection efficiency while maintaining a simple integrated structure that adds minimal complexity to the overall device
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 approach enables the production of finer particles with improved energy efficiency and enhanced separation capabilities, leading to more effective particle size reduction and processing of materials like amorphous SiO2 and carbon black.
Implementation Method 1
at least one high-energy grinding jet of compressed gas with high flow energy is introduced into the fluidized bed... the ground material and at least one grinding jet of compressed gas and ground material meet at least approximately the same temperature
Implementation Method 2
a dynamic air classifier (7) integrated into the jet mill (1)... The product flow flows in a radial direction into a classifying wheel of the wind classifier. The coarser particles are separated from the air flow in the classifying wheel
Implementation Method 3
a fluidized bed jet mill... a fluidized bed is enclosed by a housing which, in order to generate a centrifugal force on the fluidized bed, rotates about an axis in the area of at least one high-energy fluid jet entering the fluidized bed
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method for producing very fine particles by means of a jet mill (1). The relative distance a/dDüse between at least approximately concentric milling jet inlets (5) whose center lines intersect at least approximately in one point is adjusted in accordance with the pressure of the working medium, a representing the jet length and dDüse representing the nozzle diameter.