Liquefied Waste Plastic Purification via Aqueous Phase Recycling
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Solution Overview
Problem
Current methods for purifying liquefied waste plastics (LWP) to make them suitable for refinery processing face challenges such as high consumption of hydrogen, generation of large amounts of contaminated water, and inefficient removal of impurities like chlorine, which are detrimental to downstream processes and environmentally harmful.
Innovation Solution
A method involving heat treatment of LWP with an aqueous solution containing alkali metal hydroxide and/or alkaline earth metal hydroxide, followed by phase separation and recycling of the aqueous phase, which includes filtration to produce an organics-depleted stream that can be reused in the process, reducing waste water and metal hydroxide consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LWP is treated with large amounts of aqueous medium for purification, then impurity removal efficiency is improved, but large amounts of contaminated water are generated requiring disposal
Solution Approach 1:
The invention recycles the aqueous phase from phase separation back to the heat treatment step, recovering the alkali metal hydroxide and water for continued use in impurity removal, thereby minimizing contaminated water disposal
Solution Approach 2:
The aqueous phase is fed back into the heat treatment process creating a closed-loop system where purification byproducts are reused, maintaining high impurity removal efficiency while reducing waste generation
2Manufacturing precision
If common solvent extraction is used for LWP purification, then fouling components are reduced, but significant amounts of contaminated extraction material are produced requiring work-up or disposal
Solution Approach 1:
The aqueous phase containing extracted impurities is recycled back to the heat treatment process rather than disposed of, converting waste extraction material into a useful reagent for continued purification
Solution Approach 2:
The system uses its own byproduct (contaminated aqueous phase) as a resource for continued operation, where the aqueous phase serves dual purposes as both extraction medium and impurity carrier to downstream treatment
3Manufacturing precision
If hydroprocessing is used for LWP upgrading, then LWP is converted to suitable feedstock, but large amounts of hydrogen from fossil sources are consumed reducing sustainability
Solution Approach 1:
The invention converts the typically harmful aqueous waste phase into a beneficial resource by recycling it as the heat treatment medium, eliminating the need for hydrogen-intensive hydroprocessing while achieving equivalent purification
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 enhances the sustainability of the purification process by reducing fresh water and metal hydroxide consumption, improving impurity removal efficiency, and minimizing environmental impact by effectively recycling and reusing process streams.
Implementation Method 1
subjecting a liquefied waste plastic-based feedstock to heat treatment (HT processing) in an aqueous solution comprising alkali metal hydroxide and/or alkaline earth metal hydroxide
Implementation Method 2
The purification of liquefied waste plastics (LWP) to yield more valuable (pure) substances
Implementation Method 3
subjecting said heat treated effluent to phase separation to isolate at least an oil phase comprising treated LWP and an aqueous phase comprising contaminated material
Data Source
Figure 1
AI summary
The invention relates to a method for processing of liquefied waste plastics (LWP). The method comprising the steps of subjecting a liquefied waste plastic-based feedstock to heat treatment (HT processing) in an aqueous solution comprising alkali metal hydroxide and/or alkaline earth metal hydroxide to form a heat treated effluent, transferring the heat treated effluent to a separator, subjecting said heat treated effluent to phase separation to isolate at least an oil phase comprising treated LWP and an aqueous phase comprising contaminated material, and recycling at least a part of the aqueous phase back to the HT processing step.