PET Recycling via Re-crystallization and Drying
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Solution Overview
Problem
Current methods for recycling polyethylene terephthalate (PET) plastics face challenges due to their high melting temperature and hydroscopic nature, which complicates blending with other plastics and affects the extrusion process in building materials, particularly in concrete applications.
Innovation Solution
A system and method involving a heated water bath to re-crystallize PET plastics at 212 degrees Fahrenheit, followed by chipping and drying using a centrifuge or desiccant dryer to remove moisture, facilitating separate processing and preparation for extrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If PET plastic is processed at its high melting temperature, then the plastic can be extruded, but it cannot be blended with other plastics and requires separate processing
Solution Approach 1:
The invention segments the recycling process into distinct stages: collection, washing, drying, and extrusion. By separating these operations and optimizing each independently, the system handles PET's high melting point requirement without preventing future blending opportunities, as the plastic is processed in controlled batches rather than continuous mixed streams
Solution Approach 2:
The invention changes the processing parameters by using precise temperature control during extrusion and maintaining low moisture content through extended drying. These parameter adjustments allow PET to be processed at its required high temperature while preparing it for potential future blending applications
2Reliability
If PET plastic is dried thoroughly to remove moisture, then extrusion quality improves, but processing time and energy consumption increase
Solution Approach 1:
The invention performs preliminary washing and initial drying stages before extrusion, removing the bulk of moisture beforehand. This preliminary action reduces the moisture content significantly prior to the extrusion process, thereby reducing the additional drying time required immediately before extrusion while still achieving the necessary low moisture levels for quality extrusion
Solution Approach 2:
The invention implements continuous drying operation running parallel to other preparation steps. The dryer operates continuously to maintain low moisture levels in the PET flakes throughout the preparation process, rather than performing batch drying immediately before extrusion. This continuous action ensures quality while optimizing the overall processing timeline
3Manufacturing precision
If PET plastic is processed separately from other plastics, then processing quality is maintained, but productivity and resource utilization decrease
Solution Approach 1:
The invention designs a multi-functional processing system where the same equipment (washing machine, dryer, extruder) can handle PET plastic with optimized parameters while potentially accommodating other plastic types with different settings. The system's universality allows separate high-quality PET processing while maintaining the capability for blended processing when appropriate, thereby improving overall resource utilization without sacrificing PET processing quality
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
Enables efficient recycling and preparation of PET plastics for extrusion by overcoming the high melting temperature and hydroscopic issues, ensuring effective processing and reducing moisture content for improved extrusion outcomes.
Implementation Method 1
heating a quantity of source plastic to a temperature above the re-crystalizing temperature of the source plastic for form a re-crystalized plastic
Implementation Method 2
heating a quantity of source plastic to a temperature above the re-crystalizing temperature of the source plastic
Implementation Method 3
The dryer may comprise a centrifuge
Implementation Method 4
The dryer may comprise a desiccant dryer
Data Source
AI summary
A system and method for preparing recyclable plastic for extrusion wherein the system comprises a vessel operable to receive a quantity of a raw plastic containing a liquid at or above 212 degrees Fahrenheit to re-crystalize the plastic, a chipper to chip the re-crystalized plastic after removal from the vessel after a predetermined period of time and a dryer to remove the liquid from the chipped re-crystalized plastic. The method comprises heating a quantity of source plastic to a temperature above the re-crystalizing temperature of the source plastic for form a re-crystalized plastic and chipping the re-crystalized plastic