Turbine Classifier Radial Rejects Removal Roller Mill
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Solution Overview
Problem
Existing roller mill systems are inefficient in separating fine particles from undesirable materials like grit and sand, leading to a high percentage of waste discharge, as they lack effective classification based on particle density and size, resulting in reduced output and operational issues.
Innovation Solution
A roller mill system incorporating a turbine classifier with a side discharge port and a rejects capture and discharge system, including a collection trough, pressure control line, and backflow control damper, which separates particles by density and size, expelling undesirable materials radially outward and allowing fine particles to recirculate for further grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a prior art classifier is used to separate particles, then coarse particles are rejected from the air stream, but the separation efficiency is low and a high percentage of fine particles are lost with the rejects
Solution Approach 1:
The classifier is divided into multiple radial zones with different blade configurations. The inner radius blades have a first configuration optimized for capturing coarse particles, while the outer radius blades have a second configuration optimized for preserving fine particles. This segmentation allows differential treatment of particles based on their radial position and size, improving separation efficiency while minimizing fine particle loss.
Solution Approach 2:
Different portions of the classifier perform different functions based on their local characteristics. The inner radius blades are designed with specific geometry and spacing to effectively reject coarse particles, while the outer radius blades are designed with different geometry to allow fine particles to pass through. This local differentiation of quality and function resolves the contradiction between separation efficiency and fine particle preservation.
2Manufacturing precision
If the classifier rejects all coarse particles, then the fine particles are effectively separated, but a high percentage of waste material is discharged reducing output
Solution Approach 1:
The classifier blades are designed with variable parameters including different radii, angles, and spacing configurations. The inner radius blades have parameters optimized for coarse particle rejection, while outer radius blades have parameters optimized for fine particle passage. By changing these parameters radially, the system achieves precise size classification while maintaining high productivity through selective rather than blanket rejection.
3Reliability
If a bottom discharge port is added for grit removal, then undesirable materials are effectively removed, but the device complexity increases
Solution Approach 1:
A bottom discharge port is extracted from the classifier structure to specifically remove grit and sand that settle at the bottom during operation. This extracted component provides dedicated grit removal functionality without requiring modification of the main classification mechanism, achieving reliable grit removal while adding minimal complexity through a single, simple discharge opening.
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 system achieves a discharge mixture with 40 to 60 weight percent undesirable materials, effectively removing grit and sand, while ensuring 74 to 98 percent of small particles are less than 44 microns in size, significantly improving the efficiency and output of the milling process.
Implementation Method 1
A stream of particles to be classified is introduced into the turbine classifier and particles are separated by density with undesirable materials being expelled radially outward and fine particles passing through to be recirculated to the grinding zone.
Data Source
AI summary
A roller mill system includes a vessel having an inlet, an outlet, a grinding zone and a classifier zone. The grinding zone includes a grinding assembly configured for grinding the material into fine particles. The grinding zone also includes a rejects capture and discharge system that includes one or more discharge conduits for conveying rejects away from the vessel. The rejects capture and discharge system includes: 1) a collection trough located under the grinding assembly and in communication with one of the discharge conduits, for discharging rejects from the grinding zone; and/or 2) a turbine classifier mounted in the classifier zone. The turbine classifier is rotatable about a central axis. Another outlet is formed in a side wall of the classifier zone. The turbine classifier is configured to expel the rejects radially outward therefrom, through the side wall outlet and into another one of the discharge conduits.