Waste Sorting Sieve with Segmented Gas Streams for Contaminant Removal
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Solution Overview
Problem
Existing waste sorting technologies face challenges in effectively separating mixed waste materials, particularly in removing volatile contaminants like hydrocarbons from sand and soil, and in efficiently handling particles of varying sizes and surface areas, which affects the separation of different fractions.
Innovation Solution
The use of a stream of gas, specifically air, is employed to drive off volatile contaminants from sieved particles, with varying velocities of gas streams between screens to manage particle sizes and surface areas, ensuring that larger particles are not entrained in the gas stream and instead fall onto subsequent screens for further sorting, and a variable-speed fan system controls these velocities to optimize separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a gas stream is used to remove volatile contaminants from sieved particles, then contaminant removal efficiency is improved, but larger particles may be entrained in the gas stream instead of falling onto subsequent screens
Solution Approach 1:
The gas stream is divided into multiple segments with different velocities, where a first gas stream with lower velocity removes contaminants from finer particles, and a second gas stream with higher velocity handles coarser particles. This segmentation allows differential treatment of particles based on size, preventing larger particle entrainment while maintaining contaminant removal efficiency.
Solution Approach 2:
Different regions of the screening system are provided with gas streams of locally optimized velocities. The first gas stream region uses lower velocity appropriate for fine particles, while the second gas stream region uses higher velocity for coarser particles. This local quality adjustment ensures each region operates at optimal gas velocity for its specific particle size range.
2Ease of operation
If a single gas stream velocity is used between screens, then the system is simpler to operate, but it cannot effectively handle particles of varying sizes and surface areas
Solution Approach 1:
The system transitions from a static single-velocity gas stream to a dynamic multi-velocity gas stream system. The gas stream velocity is dynamically adjusted across different regions to match the specific requirements of particles in each region, allowing the system to adapt to varying particle sizes and surface areas while maintaining ease of operation through automated control.
Solution Approach 2:
The gas streaming system is designed to perform multiple functions simultaneously: removing volatile contaminants from fine particles using the first gas stream, and preventing entrainment of larger particles using the second gas stream. This multi-functionality allows a single system to handle the full range of particle sizes and surface areas encountered in waste materials.
3Manufacturing precision
If higher gas stream velocity is used to prevent particle entrainment, then particle separation accuracy is improved, but volatile contaminant removal efficiency decreases
Solution Approach 1:
The gas stream is segmented into two distinct streams with different velocities positioned at different locations between the screens. The first gas stream with lower velocity is optimized for contaminant removal from fine particles, while the second gas stream with higher velocity is optimized for preventing entrainment of coarser particles. This segmentation resolves the velocity conflict by applying appropriate velocity in each region.
Solution Approach 2:
The first gas stream acts as an intermediary between the particle separation process and the contaminant removal process. It provides a gentler gas flow that removes contaminants without causing particle entrainment, while the second gas stream provides the stronger flow needed to prevent entrainment of larger particles. Together, they mediate between the conflicting requirements of contaminant removal and particle separation accuracy.
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 efficient separation and classification of mixed waste materials by effectively removing contaminants and sorting particles based on size and surface area, improving the accuracy and efficiency of waste fractionation, including compacting lighter materials for better waste management.
Implementation Method 1
a stream of gas fed between screens can be used to drive off volatile contaminants from sieved particles
Implementation Method 2
a stream of air can be used to drive off organic - in particular hydrocarbon - contaminants from sieved particles of sand and/or soil
Implementation Method 3
larger particles are not entrained in the gas stream and instead fall onto subsequent screens for further sorting
Implementation Method 4
the lower its SSA and the greater the velocity of sideways gas stream it can withstand before it is fully entrained in that gas stream rather than falling under the action of gravity
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Apparatus for sorting mixed waste materials, comprising: a first sieve (210) screen having upper and lower surfaces (300, 310) and first sieve openings configured to allow only particles having a maximum dimension less than or equal to a first threshold dimension to pass therethrough; a second sieve screen (400) having upper and lower surfaces (410, 420) and second sieve openings configured to allow only particles having a maximum dimension less than or equal to a second threshold dimension to pass therethrough, the second threshold dimension being less than the first threshold dimension; and a third surface (500); wherein the apparatus is configured such that particles passing through the first screen (210) fall under gravity towards the upper surface (410) of the second screen (400) and particles passing through the second screen (400) fall under gravity towards the third surface (500); the apparatus being further configured to generate: a first gas stream (J) between the lower surface (310) of the first screen (210) and the upper surface (410) of the second screen (400) and configured to drive off volatile contaminants from particles passing through the first screen (210), the first gas stream having a respective first velocity; and a second gas stream (K) between the lower surface (420) of the second screen and the third surface (500) and configured to drive off volatile contaminants from particles passing through the second screen (400), the second gas stream (K) having a respective second velocity, less than the first velocity.