Rotating Drum Separator for Moist Bottom Ash
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Solution Overview
Problem
Existing separation apparatuses are inefficient in separating particles with modest size differences, particularly in moist particle streams like bottom ash from waste incineration plants, leading to incomplete separation of fractions with particles sized 0-2 mm and 2-15 mm, where metals are often aggregated and difficult to recover due to moisture content.
Innovation Solution
The separation apparatus employs a rotatable drum with radially extending plates to break up moist particles, combined with a high-speed conveyor in the receiving area for the second fraction, moving at least 2 m/s, and an inclined position to prevent re-sticking of particles, along with air flow and a collision plate to enhance separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotatable drum with radially extending plates is used to accelerate and break up moist particles, then particle separation is achieved, but particles of different fractions still mix in the receiving areas due to incomplete separation
Solution Approach 1:
The receiving area is divided into multiple sub-areas (first receiving area for first fraction, second receiving area for second fraction) with separate conveyors for each fraction, enabling independent control and discharge of separated particles to improve separation precision
Solution Approach 2:
Different conveyors are assigned to different receiving areas based on local requirements - the first conveyor handles the first fraction while the second conveyor handles the second fraction, allowing optimized discharge for each fraction type
2Productivity
If moist particles are accelerated by drum plates, then particle breakup occurs, but moisture causes particles to stick together and reduces separation effectiveness
Solution Approach 1:
The harmful moisture adhesion effect is counteracted by extracting particles from the moist environment through rapid discharge via conveyors, removing them from the sticking condition before they can re-aggregate
Solution Approach 2:
Particles are rapidly conveyed and discharged through the receiving areas at high speed, minimizing the time they spend in conditions where moisture could cause re-sticking, thus skipping the harmful adhesion phase
3Manufacturing precision
If particles are collected in receiving areas, then separation is completed, but particles may re-stick and reduce separation quality
Solution Approach 1:
Conveyors are positioned and configured to discharge particles before they have time to re-stick in the receiving areas, performing the removal action preliminarily to prevent the harmful re-aggregation effect
Solution Approach 2:
Particles are rapidly moved through the receiving areas by conveyors, skipping the time period where moisture-induced sticking could occur, thus maintaining fraction purity
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 into distinct fractions, achieving high recovery rates of metals, with the second fraction (2-15 mm) being recovered at 96.5% and the first fraction (0-2 mm) at 50.5%, demonstrating improved separation efficiency and metal recovery from bottom ash.
Implementation Method 1
accelerating the moist particles in the particle-stream by the plates of the rotor impinging on said particles during their falling to the rotating drum. This results in a breakup of the particles of the first fraction from the particles of the second fraction
Implementation Method 2
said first conveyor is caused to move during use at a speed of at least 2 m/s, and said second conveyor is caused to move during use at a speed of at least 2 m/s
Data Source
AI summary
The invention relates to a separation-apparatus for separating from a particle-stream at least a first fraction with particles of a first group of dimensions, and a second fraction with particles of a second group of dimensions, comprising an infeed-device for the particle-stream, a rotatable drum having at its circumference plates, each plate having a radially extending hitting surface for the particles, at least a first receiving area proximal to the drum for receipt therein of particles of the first fraction, and at least a second receiving area distant from the drum for receipt therein of particles of the second fraction, wherein the apparatus has a housing so as to protect the particles from outside weather-conditions, allowing that the particles of the particle-stream to be processed by said apparatus have dimensions in the range 0-15 mm.