Waste Plastic Conversion Using Tyre-Derived Aromatic Solvents
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Solution Overview
Problem
Current processes for converting used tires and waste plastics into liquid hydrocarbon fractions face challenges such as high temperature requirements, excessive polyaromatic structure formation, and the need for aromatic solvents, which complicate refining and increase energy consumption, especially in small-scale, decentralized facilities.
Innovation Solution
A process that uses liquid aromatic compounds from tire decomposition as solvents for plastic decomposition, maintaining temperatures below 450°C to minimize polyaromatic formation and maximize carbon black production, and recycles intermediate hydrocarbon cuts to enhance solvent efficiency and reduce energy needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature (300-900°C) is used to decompose used tyres, then decomposition efficiency is improved, but polyaromatic structure formation increases and energy consumption increases
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperature (300-900°C) to a lower range (200-400°C) and introduces a solvent system to enable decomposition at these milder conditions. This parameter change reduces polyaromatic formation while maintaining decomposition efficiency through the solvent-mediated reaction pathway.
Solution Approach 2:
The patent introduces an intermediary solvent system (aromatic solvents like toluene or xylene, or aliphatic solvents like hexane) that mediates the decomposition reaction. This intermediary enables the reaction to proceed at lower temperatures by solvating reactants and stabilizing transition states, thereby reducing harmful polyaromatic formation.
2Productivity
If high temperature (above 500°C) is used for cracking reactions, then cracking efficiency is improved, but gas production increases and liquid product yield decreases
Solution Approach 1:
The patent changes the temperature parameter from high temperature (above 500°C) to a lower range (200-400°C) and uses a solvent system to achieve cracking at these milder conditions. This parameter change shifts the product distribution toward liquid hydrocarbons while maintaining cracking efficiency through solvent-mediated reaction pathways.
Solution Approach 2:
The patent utilizes the liquid phase environment created by the solvent system to conduct cracking reactions. This phase transition from gas-solid to liquid-phase reactions enables better heat transfer and reaction control, increasing liquid product yield while maintaining cracking efficiency.
3Ease of operation
If aromatic solvents are used for plastic decomposition, then dissolution efficiency is improved, but refining complexity increases
Solution Approach 1:
The patent recycles the aromatic solvent from the reaction mixture through distillation or other separation techniques. The recovered solvent is then reused in subsequent batches, reducing the need for continuous fresh solvent input and simplifying the overall refining process by eliminating the need for complete solvent removal and replacement.
Solution Approach 2:
The patent optimizes the solvent-to-plastic ratio and temperature parameters to achieve efficient dissolution while facilitating easier solvent removal. By controlling these parameters, the patent reduces refining complexity through optimized phase behavior and reduced solvent residue in the final product.
4Speed
If high temperature conditions are maintained, then reaction rate is improved, but coke formation on carbon black increases
Solution Approach 1:
The patent changes the temperature parameter from high temperature to a lower range (200-400°C) and uses a solvent system to maintain adequate reaction rates at these milder conditions. This parameter change reduces coke formation on carbon black while preserving reaction speed through solvent-mediated reaction pathways.
Solution Approach 2:
The solvent acts as an intermediary that enables reactions to proceed at lower temperatures by solvating reactants and stabilizing transition states. This intermediary effect maintains reaction rates while reducing thermal stress that would otherwise lead to coke formation on carbon black particles.
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 gas production, limits polyaromatic formation, and increases the yield of high-quality liquid hydrocarbon fractions, facilitating easier refining and reducing energy consumption, making the process more economically viable for small-scale facilities.
Implementation Method 1
a solid feedstock based on used tyres is sent into a reaction zone in the presence of a liquid solvent comprising aromatic compounds to at least partly dissolve said solid feedstock
Implementation Method 2
thermally decompose at a temperature of less than or equal to 425° C. said at least partially dissolved solid feedstock so as to obtain at least carbon black and a first hydrocarbon-based liquid fraction
Implementation Method 3
a molten plastic feedstock is sent together with at least a portion of the first hydrocarbon-based liquid fraction into a conversion zone to at least partly dissolve said molten plastic feedstock
Implementation Method 4
thermally decompose at a temperature of less than or equal to 450° C. said partially dissolved plastic feedstock so as to obtain at least partly a second hydrocarbon-based liquid fraction
Implementation Method 5
the first hydrocarbon-based liquid fraction obtained from step a) is optionally at least partly sent to a distillation zone to obtain at least one intermediate hydrocarbon cut whose initial boiling point is between 250 and 325° C. and whose final boiling point is between 350 and 450° C.
Data Source
AI summary
The invention relates to a process for converting a plastic feedstock and for converting used tyres to obtain carbon black, comprising the following steps:a) a solid feedstock (100) based on used tyres is sent into a reaction zone (10) in the presence of a liquid solvent (340) comprising aromatic compounds to at least partly dissolve said solid feedstock and to thermally decompose said dissolved solid feedstock so as to obtain carbon black (160) and a first hydrocarbon-based liquid fraction (120);b) a molten plastic feedstock (200) is sent together with at least a portion of the first hydrocarbon-based liquid fraction (120) obtained on conclusion of step a) into a conversion zone (20) to dissolve said molten plastic feedstock (200) and to thermally decompose said dissolved plastic feedstock so as to obtain a second hydrocarbon-based liquid fraction (230).