Rotary Classifier Blades with Tilted Surfaces for Particle Separation

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Solution Overview

Problem

Conventional rotary classifiers for vertical mills face challenges in efficiently separating fine and coarse particles, as blades with small tilt angles can eliminate fine particles and those with large tilt angles allow coarse particles to pass, leading to suboptimal classification efficiency.

Innovation Solution

The rotary classifier features a frame with blades having tilted surfaces at acute angles and concave portions between the outer and inner ends, allowing coarse particles to be eliminated while fine particles pass through, enhancing classification efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If rotary blades with a small tilt angle are used, then coarse particles can be eliminated, but fine particles may also be eliminated

Engineering Contradiction:

Improveparticle size classification precisionVSAvoidloss of fine particles

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The rotary blade is divided into multiple sections along its width, with each section having a different tilt angle. The first section (near the outer end) has a smaller tilt angle to eliminate coarse particles, while the second section (near the inner end) has a larger tilt angle to allow fine particles to pass. This segmentation allows simultaneous achievement of coarse particle elimination and fine particle preservation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the rotary blade are given different local properties (tilt angles) to perform different functions. The outer region has a smaller tilt angle optimized for coarse particle removal, while the inner region has a larger tilt angle optimized for fine particle separation. This local quality variation resolves the contradiction between eliminating coarse particles and preserving fine particles.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If rotary blades with a large tilt angle are used, then fine particles can be allowed to pass, but coarse particles may also pass

Engineering Contradiction:

Improveparticle size classification precisionVSAvoidpassage of coarse particles

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The rotary blade is segmented into multiple sections with different tilt angles. The first section has a smaller tilt angle to prevent coarse particles from passing, while the second section has a larger tilt angle to allow fine particles to pass. This segmentation simultaneously achieves both requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the rotary blade have different local tilt angle properties. The section near the outer end has a smaller tilt angle to block coarse particles, while the section near the inner end has a larger tilt angle to facilitate fine particle passage. This local quality differentiation resolves the contradiction.

Inventive Principle:

Principle #3Local quality

3Productivity

If conventional rotary blades with uniform tilt angle are used, then the structure is simple, but classification efficiency is insufficient

Engineering Contradiction:

Improveclassification efficiencyVSAvoidblade structure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The rotary blade is divided into multiple sections along its width, with each section having a different tilt angle. This segmentation improves classification efficiency by enabling different sections to handle different particle size ranges, while the overall structure remains relatively simple and manufacturable.

Inventive Principle:

Principle #1Segmentation

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 configuration effectively separates particles by size, allowing nearly 100% of particles with diameters of 75 μm or less to pass while eliminating over 90% of particles with diameters of 150 μm or more, significantly improving classification efficiency compared to conventional designs.

Implementation Method 1

raw coal is supplied on the mill table from a coal feed pipe, the fed raw coal is dispersed on the whole surface due to centrifugal force to form a coal layer

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

coarse particles having high ability to fly in a straight line are eliminated to the outside after colliding against the tilted surface, while fine particles having low ability to fly in a straight line enter inside after colliding against the tilted surface

Methodology Applied

Scientific EffectInertial separation: Inertia

Data Source

PatentUS10124373B2Rotary classifier and vertical mill

Publication Date: 2018.11.13 MITSUBISHI HEAVY IND LTD

AI summary

In a rotary classifier and a vertical mill, a rotary separator (33) is configured such that plural rotary blades (43) are fixed to an outer circumference portion at predetermined intervals in a circumferential direction between an upper support frame (41) and a lower support frame (42), which have a disk-like shape, wherein a tilted surface (52), which tilts at an acute angle relative to a tangent line (T) to a rotation locus (G1) on an outer circumference side and includes a concave portion (51) formed between an outer end (43a) and an inner end (43b), is formed on a front surface of each of the rotary blades (43) in a rotating direction.