Vacuum Pyrolysis of Mixed Plastic and Biomass Waste
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Solution Overview
Problem
Current pyrolysis technologies are inefficient in processing mixed plastic and biomass waste, producing unstable and heterogeneous liquid fractions with high heteroatom content, and require large, costly facilities for stabilization, which are not scalable.
Innovation Solution
A non-oxidative vacuum thermal depolymerisation process involving sequential stages and devices for treating mixed polymeric materials, including low and high-temperature vacuum processes, additive incorporation, and multi-stage gas treatment, to produce high-quality liquid and solid products suitable for industrial use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional pyrolysis processes are used to treat mixed plastic and biomass waste, then liquid fractions are produced, but the liquid fractions are unstable and heterogeneous with high heteroatom content
Solution Approach 1:
The pyrolysis process is divided into multiple sequential stages (fast pyrolysis, slow pyrolysis, carbonization) with different temperature profiles and residence times. This segmentation allows progressive decomposition and stabilization of liquid products, reducing heterogeneity and improving composition stability while maintaining production quantity.
Solution Approach 2:
The patent applies preliminary drying and preheating stages before the main pyrolysis process. Raw mixed waste is dried to reduce moisture content and preheated to initiate decomposition. This preliminary action prepares the material for more efficient pyrolysis, improving liquid fraction stability by ensuring consistent feed conditions.
2Manufacturing precision
If large-scale stabilization facilities are built to process pyrolysis liquids, then product quality improves, but investment costs and facility size increase significantly
Solution Approach 1:
The pyrolysis system is designed to be self-sufficient by generating its own thermal energy through combustion of produced syngas. The process uses its own output (synthesis gas) to fuel the pyrolysis reactions, eliminating the need for external energy sources and reducing facility complexity while maintaining product quality.
Solution Approach 2:
The patent combines multiple functions into integrated reactor systems that perform drying, pyrolysis, and carbonization in a unified setup. The syngas cleaning system is integrated with the pyrolysis reactor, and thermal energy from syngas combustion is directly used to heat the pyrolysis process, reducing the number of separate facilities needed.
3Productivity
If high temperature pyrolysis (>750°C) is used, then cracking efficiency increases, but liquid product formation decreases and non-condensable gases increase
Solution Approach 1:
The patent employs periodic or sequential temperature variations through distinct process stages. Fast pyrolysis uses high temperature for short duration to maximize liquid yield, followed by slow pyrolysis at lower temperature for extended time to stabilize products. This periodic temperature action allows the system to achieve both high cracking efficiency and liquid product formation at different phases.
Solution Approach 2:
The system dynamically changes temperature parameters across different process stages and reactor zones. Temperature is optimized for each stage: high temperature for fast pyrolysis to generate liquids, then lower temperature for slow pyrolysis to stabilize them. This parameter change allows the system to achieve both high cracking efficiency and maintain liquid product yield.
4Productivity
If mixed polymeric materials are processed, then waste treatment efficiency improves, but product heterogeneity increases
Solution Approach 1:
The patent designs a universal pyrolysis system capable of processing diverse mixed polymeric materials (plastics, biomass, rubber, textiles) simultaneously. The multi-stage reactor configuration and flexible temperature control allow the system to handle various material compositions while producing relatively consistent liquid and carbon products, achieving both high waste treatment efficiency and acceptable product homogeneity.
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 process achieves stable, high-quality organic and aqueous fractions, reduces carbon footprint, and enables efficient recycling of mixed waste with low energy consumption and minimal pollutant emission, suitable for chemical and fuel industries.
Implementation Method 1
non-oxidative vacuum thermal depolymerisation process
Implementation Method 2
thermal depolymerisation process involving sequential stages and devices for treating mixed polymeric materials
Implementation Method 3
non-oxidative vacuum thermal depolymerisation process
Data Source
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AI summary
The present invention describes a non-oxidative thermal depolymerisation process under vacuum conditions comprising a series of devices and methods for transforming polymeric materials into functional carbons, an aqueous fraction, a heavy organic fraction and a light organic fraction by means of non-oxidative vacuum thermal depolymerisation of natural or synthetic polymeric materials and their mixtures.