Shear Plate Reaction Vessel for Liquid-Phase Polymer Pyrolysis
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Solution Overview
Problem
Current pyrolysis processes for recycling plastics are energy-intensive, inefficient, and produce carbon buildup, with existing mechanical and thermal energy inputs being economically unviable on a commercial scale, and mixing methods fail to effectively bring reactants into contact with catalyst surfaces.
Innovation Solution
A shear plate reactor design with rotating arms and shear plates close to the reactor wall generates high shear strain rates, improving heat transmission, mixing efficiency, and handling carbon by-products, using a heat exchange shell with molten salt circuits and solar concentrators for efficient energy supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional pyrolysis processes are used to recycle plastics, then plastic waste can be converted into useful products, but high energy consumption and carbon buildup occur
Solution Approach 1:
The patent changes the physical state parameter from vapor phase to liquid phase pyrolysis, operating at lower temperatures (300-450°C) compared to conventional vapor phase pyrolysis (430-550°C). This parameter change reduces energy consumption while maintaining effective plastic decomposition and product yield
Solution Approach 2:
The patent replaces thermal convection and turbulence (mechanical mixing in vapor phase) with mechanical shear mixing in liquid phase. The shear plate mixer creates intense mechanical agitation that ensures uniform catalyst- reactant contact without requiring high temperatures, thereby reducing energy consumption
2Loss of substance
If conventional pyrolysis processes are used to recycle plastics, then plastic waste can be converted into useful products, but carbon buildup interferes with heat exchange efficiency
Solution Approach 1:
The patent extracts carbon buildup from the heat exchange surface by incorporating a scraping mechanism that continuously removes deposited carbon from the reactor walls. This prevents carbon accumulation that would otherwise insulate the heat exchange surface and reduce thermal efficiency
Solution Approach 2:
The shear plate mixer's rotation creates self-cleaning action on the reactor walls through shear forces that prevent carbon adhesion. The mechanical agitation keeps the liquid phase reactants in constant motion, preventing carbon deposition and maintaining heat exchange efficiency without additional cleaning systems
3Reliability
If mechanical mixing is used in liquid phase pyrolysis, then reactants can be brought into contact with catalyst surfaces, but mixing efficiency is insufficient
Solution Approach 1:
The patent employs a dynamic shear plate mixing system where plates rotate at controlled speeds to create variable shear rates throughout the liquid phase reactor. This dynamic mixing mechanism ensures continuous and uniform contact between reactants and catalyst surfaces, improving reaction reliability and effectiveness
Solution Approach 2:
The shear plate mixer creates localized high-shear zones near the plates where intense mixing occurs, ensuring thorough catalyst-reactant contact in these regions. The design optimizes mixing intensity at specific locations within the reactor where it is most needed, improving overall mixing efficiency
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 design enables efficient pyrolysis of plastics with reduced energy consumption, effective mixing of reactants and catalysts, and manages carbon buildup, facilitating large-scale recycling with capacities of 100 tons/day and higher.
Implementation Method 1
a heat exchange shell surrounding the reactor barrel, the heat exchange shell connected to a heat exchange circuit and configured to flow a heat exchange fluid over an outer surface of the reactor barrel
Implementation Method 2
the spacing configured to generate a predetermined strain rate between the shear plate and the inner wall via Couette flow
Implementation Method 3
using a heat exchange shell with molten salt circuits and solar concentrators for efficient energy supply
Implementation Method 4
Chemical recycling uses a chemical reaction called 'pyrolysis' which includes cracking of chemical bonds of thermoplastic polymers to hydrocarbon gaseous and liquid products
Data Source
AI summary
An improved reactor vessel for processing (recycling and upcycling) of plastics includes a shear plate assembly disposed on a rotatable shaft concentrically disposed within a cylindrical reactor vessel. The shear plates are spaced from the vessel wall to generate a predetermined strain rate between the shear plate and the inner wall via Couette flow, enhancing efficiency of the reaction.