Mixed Polymer Waste Extrusion With Alkali Salts for Pyrolysis
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Solution Overview
Problem
Current recycling technologies struggle to efficiently process multi-layer flexible packaging film containing heteroatom-containing polymers like PET and PA due to the formation of hazardous degradation products during pyrolysis, leading to equipment damage and low recycling rates, with commercial plants often requiring mechanical sorting and limited acceptance of high PET/PA content.
Innovation Solution
A method involving the use of an extruder with alkali or alkaline earth metal salts to degrade heteroatom-containing polymers in mixed polymer waste, followed by a melt filter and degassing unit to remove degradation products, producing a more homogeneous hydrocarbon product suitable for pyrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical sorting is used to remove heteroatom-containing polymers before pyrolysis, then the quality of hydrocarbon product is improved, but the device complexity and processing time increase
Solution Approach 1:
The patent applies preliminary action by adding alkaline agents to the mixed polymer waste before pyrolysis to pre-neutralize heteroatom-containing polymers. This pre-treatment converts potentially harmful heteroatoms into stable salts that will not form hazardous degradation products during pyrolysis, eliminating the need for complex mechanical sorting equipment while maintaining product quality
Solution Approach 2:
The patent converts the harmful effect of heteroatom-containing polymers into a beneficial outcome by using alkaline agents to transform them into stable salts. The heteroatoms (Cl, S, N, etc.) that would normally form hazardous degradation products are converted into stable salt forms that can be easily removed, turning a problematic component into a manageable byproduct
2Object-generated harmful factors
If alkaline agents are added to degrade heteroatom-containing polymers, then hazardous by-products are reduced, but the loss of substance increases due to salt formation
Solution Approach 1:
The patent converts the harmful heteroatom-containing polymers into beneficial stable salts through alkaline treatment. Instead of losing valuable material, the heteroatoms are transformed into stable forms that can be easily separated, and the resulting salts can potentially be recovered or disposed of more easily than hazardous degradation products
Solution Approach 2:
The patent changes the chemical state of heteroatom-containing polymers by adding alkaline agents, transforming them from a hazardous form into a stable salt form. This parameter change (chemical composition and stability) allows for easier separation and reduces the environmental impact while minimizing actual material loss
3Productivity
If high PET/PA content is processed through pyrolysis, then recycling rate is improved, but equipment damage and product quality deteriorate
Solution Approach 1:
The patent applies preliminary action by treating mixed polymer waste with alkaline agents before pyrolysis. This pre-treatment neutralizes heteroatom-containing polymers (PET, PA) and converts them into stable salts, preventing them from causing equipment damage during pyrolysis. This allows high PET/PA content waste to be processed safely, improving recycling rates while protecting equipment
Solution Approach 2:
The patent applies preliminary anti-action by using alkaline agents to counteract the harmful effects of heteroatom-containing polymers before they can cause damage during pyrolysis. The alkaline treatment pre-neutralizes corrosive substances, preventing equipment corrosion and degradation that would otherwise occur when processing high PET/PA content waste
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 process effectively degrades heteroatom-containing polymers, reducing hazardous by-products and improving the quality of the hydrocarbon product, allowing for higher PET/PA content recycling without mechanical separation, and enhancing pyrolysis efficiency.
Implementation Method 1
adding chemicals, preferably alkali metal salt and/or alkali earth metal salt, to said mixed polymer waste to degrade said polymer comprising heteroatoms
Implementation Method 2
a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product
Implementation Method 3
a degassing unit for receiving the hydrocarbon product from the melt filter and removing volatile degradation products from said hydrocarbon product
Implementation Method 4
a pyrolysis unit for receiving the hydrocarbon product from the degassing unit and pyrolysing said hydrocarbon product
Data Source
AI summary
The present invention relates to a method for producing a hydrocarbon product from mixed polymer waste, preferably plastic waste and/or post consumer plastic waste, wherein said mixed polymer waste comprises 50-99.5 wt % polyolefins and 0.5-50 wt % polymer comprising heteroatoms, based on the total weight of the mixed polymer waste, comprising: (i) feeding said mixed polymer waste into an extruder, preferably a single screw extruder; (ii) adding chemicals, preferably alkali metal salt and/or alkali earth metal salt, to said mixed polymer waste to degrade said polymer comprising heteroatoms; (iii) removing degradation products derived from said polymer comprising heteroatoms from said hydrocarbon product; and (iv) collecting the hydrocarbon product. The method and system of the present invention may be used as a pre-treatment in recycling mixed polymer waste to produce a hydrocarbon product ideally suited for pyrolysis.