Multilayer Plastic Separation Using Superheated Vapor
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Solution Overview
Problem
Current methods for recycling multilayer plastics are energy-intensive, require toxic chemicals, and utilize abrasive substances, leading to resource inefficiencies and environmental concerns.
Innovation Solution
A method involving a system with a vessel and mechanical separation unit that uses superheated vapor to weaken the adhesive between layers, followed by mechanical separation and sorting, eliminating the need for high-temperature heating and chemical treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional recycling methods heat multilayer plastic fragments to temperatures above 80°C to weaken the adhesive, then the adhesive bond is weakened and layers can be separated, but energy consumption increases significantly
Solution Approach 1:
The invention changes the parameters of the separation process by using pressurized water at temperatures between 40-90°C and pressures up to 200 bar, instead of conventional heating to above 80°C. This parameter change allows effective adhesive weakening through a different mechanism (pressurized water penetration and hydrolysis) that consumes less energy while achieving reliable layer separation.
Solution Approach 2:
The invention replaces the thermal-mechanical system (heating to weaken adhesive) with a hydraulic-chemical system (pressurized water injection for hydrolysis and penetration). This substitution eliminates the need for high-temperature heating equipment and reduces energy consumption while maintaining effective adhesive bond weakening.
2Reliability
If conventional methods use chemical compositions to dissolve adhesive or plastic layers, then separation is achieved, but toxic chemicals requiring special treatment and disposal are introduced
Solution Approach 1:
The invention extracts and eliminates the harmful chemical dissolution step from the conventional process. Instead of using chemical compositions to dissolve adhesive or plastic layers, the method uses pressurized water for physical penetration and hydrolysis, which is environmentally benign and requires no special treatment or disposal.
Solution Approach 2:
The invention uses pressurized water as an intermediary substance that performs the separation function without introducing toxicity. Water acts as a safe mediator that penetrates the adhesive layer, facilitates hydrolysis, and enables layer separation without the harmful effects associated with chemical solvents.
3Reliability
If conventional recycling processes use abrasive substances for physical separation of layers, then layers can be mechanically separated, but special handling and disposal methods are required
Solution Approach 1:
The invention performs preliminary action by using pressurized water to weaken and penetrate the adhesive bond before mechanical separation is attempted. This pre-treatment softens the adhesive and reduces the strength of the bond between layers, making subsequent mechanical separation easier and eliminating the need for aggressive abrasive substances.
Solution Approach 2:
The invention replaces the abrasive mechanical separation system with a hydraulic pre-treatment system followed by gentle mechanical separation. The pressurized water injection system substitutes for abrasive substances by chemically weakening the adhesive through hydrolysis, allowing layers to be separated without harsh abrasives.
4Reliability
If conventional methods use multiple substances including chemical compositions used only once, then separation can be achieved, but resource consumption and waste generation increase
Solution Approach 1:
The invention implements recovery and reuse of the pressurized water medium throughout the process. Water is injected, penetrates the adhesive, facilitates separation, and then the same water is recovered and reused for subsequent batches. This eliminates the need for disposable chemical compositions and significantly reduces substance consumption and waste generation.
Solution Approach 2:
The pressurized water system serves multiple functions throughout the process: heating, penetrating, hydrolyzing, and cleaning. The water essentially serves itself by circulating through the system, performing multiple separation cycles, and requiring minimal external input beyond the initial pressurization and heating, thereby reducing overall resource consumption.
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 reduces energy consumption, eliminates the use of toxic chemicals, and enhances resource efficiency by promoting simultaneous high-pressure and temperature conditions for effective layer separation without subsequent drying stages.
Implementation Method 1
pressurising the vessel with preheated vapour generated in a boiler and introduced into the vessel until the interior of the vessel reaches a pressure of between 1 bar and 12 bar, and a temperature between 100° C. and 191.12° C.
Implementation Method 2
a mechanical recompression machine connected to the discharge tank
Data Source
AI summary
A system and method are for separating the layers of multilayer plastics, the fragments of multilayer plastic being carried into a receptacle (1) pressurized for 10 to 60 seconds. The receptacle is pressurized using overheated vapor generated in a boiler and introduced into the receptacle until reaching a pressure between 1 and 12 bar and a temperature between 100 and 191.12° C. The fragments are then carried to a discharge tank at a relative pressure between −0.7 and 0.1 bar and at a temperature between 15 and 25° C. for between 1 and 5 minutes. The multilayer fragments are later transferred to a mechanical separation unit where the fragments are separated into fragments of single-layer plastic and, lastly, to a mechanical sorting unit where the fragments are sorted by material.