Optical Sorting of Polyolefin Plastic Waste for Pyrolysis Feedstock
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Solution Overview
Problem
Current methods for recycling plastic waste, such as pyrolysis, are inefficient due to contamination and non-uniform composition of the plastic waste, which affects the purity of the obtained fractions.
Innovation Solution
A method involving the use of an optical separator to further sort plastic waste before shredding and washing, removing minority fractions and ensuring a uniform composition, with particles smaller than 30 mm being screened out to facilitate effective separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If plastic waste is sorted using conventional methods without optical separation, then the process is simpler and faster, but the composition uniformity and purity of plastic waste are insufficient
Solution Approach 1:
The patent replaces conventional mechanical sorting methods with an optical sorting system that uses sensors to detect and identify different plastic materials. This optical detection system enables precise classification of plastic waste by material type, achieving uniform composition and high purity levels while maintaining operational efficiency.
Solution Approach 2:
The patent introduces an optical sensor system as an intermediary between the plastic waste stream and the sorting mechanism. These sensors detect material properties and trigger targeted sorting actions, enabling precise separation of different plastic types without requiring complex manual sorting processes.
2Quantity of substance
If small particles less than 30 mm are included in plastic waste, then the material quantity is maximized, but the optical separator cannot effectively recognize and separate them
Solution Approach 1:
The patent performs preliminary sizing of plastic waste particles before they enter the optical sorting system. By pre-processing the waste stream to ensure particles meet minimum size thresholds, the system guarantees that all materials presented to the optical sensors are large enough for accurate detection and effective separation, thereby maintaining both quantity and detection precision.
3Quantity of substance
If plastic waste contains contaminants and minority fractions, then the input material volume is larger, but the pyrolysis efficiency and fraction purity are reduced
Solution Approach 1:
The patent extracts and removes contaminants and minority fraction materials from the plastic waste stream through optical detection and targeted sorting mechanisms. By identifying and separating non-target materials before pyrolysis, the system ensures that only pure, uniform plastic materials enter the pyrolysis process, maximizing efficiency and fraction purity while maintaining optimal input volumes.
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 method results in plastic waste that is predominantly composed of polyolefin or polystyrene, allowing for efficient pyrolysis and the production of high-quality purified fractions.
Implementation Method 1
further sorting said plastic waste with an optical separator
Implementation Method 2
said plastic waste is screened before said optical separator, wherein particles smaller than 30 mm are removed from said plastic waste
Implementation Method 3
said plastic waste is reduced in a first shredder
Implementation Method 4
washing said reduced plastic waste; wherein said washed reduced plastic waste is formed into an agglomerate
Implementation Method 5
The plastic waste is converted by pyrolysis into purified fractions
Data Source
Figure 1
AI summary
The present invention relates to a method for the pretreatment of plastic waste comprising the steps of supplying plastic waste, wherein the plastic waste comprises at least 80% polyolefin films or at least 80% polystyrene, reducing the plastic waste in a first shredder, washing the reduced plastic waste, producing agglomerate from the reduced plastic waste, storing the agglomerate in a silo, wherein before reducing the plastic waste in the first shredder, particles smaller than 30 mm are screened from the plastic waste, after which the waste that is not polyolefin or polystyrene is removed from the plastic waste with the aid of optical separation. The invention also relates to a device for pretreatment of plastic waste and an agglomerate.