Waste Plastic Cracking Process With Dechlorination and Viscosity Reduction
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Solution Overview
Problem
Existing recycling technologies face challenges in efficiently processing waste plastics due to issues such as the formation of chlorinated hydrocarbons from polyvinyl chloride, slow heat transfer leading to excessive cracking, and low density resulting in inefficient processing scales.
Innovation Solution
A method and system for fluidized cracking of waste plastics involving liquefaction, viscosity reduction, and cracking reactions, including dechlorination and regeneration processes, to produce low molecular weight products and remove impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional heating methods are used for waste plastics, then heating can be applied, but heat transfer is very slow causing excessive cracking of external part while internal part remains solid
Solution Approach 1:
The patent employs microwave heating to induce phase transitions and thermal effects within the waste plastic material. Microwave energy penetrates the material and causes molecular vibration and rotation, generating heat throughout the bulk rather than from the surface, thereby achieving uniform heating and preventing the external-overheating-internal-underheating problem of conventional methods
Solution Approach 2:
The patent replaces traditional conductive/convective heating mechanisms with electromagnetic field-based microwave heating. This substitution enables volumetric heating through dielectric loss and ionic conduction, dramatically improving heat transfer rate and eliminating the slow, surface-to-core heat penetration limitation of mechanical heating systems
2Ease of manufacture
If waste plastics with high molecular weight and solid state are processed, then the material can be handled, but heat transfer inside the plastic is very slow leading to high pyrolysis coking rate and high gas yield
Solution Approach 1:
The patent utilizes microwave-induced phase transitions to rapidly transform the physical state of waste plastics during processing. The microwave energy causes rapid heating that facilitates transition from solid to molten state, enabling efficient mixing, heat transfer, and subsequent pyrolysis reactions while maintaining material handleability throughout the process
Solution Approach 2:
The patent employs periodic or pulsed microwave heating regimes to process the waste plastic material. This periodic energy input allows controlled heating cycles that prevent overheating while ensuring thorough processing, thereby improving productivity by optimizing the balance between heating efficiency and reaction control
3Adaptability or versatility
If polyvinyl chloride is present in waste plastics, then the material can be processed, but it decomposes into HCl which reacts with double bonds to form chlorinated hydrocarbons
Solution Approach 1:
The patent converts the harmful HCl decomposition product from polyvinyl chloride into a beneficial byproduct. By controlling the pyrolysis conditions and using appropriate catalysts, the HCl is transformed into chlorine gas that can be captured and utilized, or converted into valuable chlorinated compounds, thereby turning a harmful factor into a resource
Solution Approach 2:
The patent introduces catalysts or additives as intermediaries to mediate the decomposition of polyvinyl chloride. These intermediaries facilitate controlled dechlorination reactions that prevent uncontrolled HCl formation and subsequent harmful reactions, while enabling the extraction of chlorine in a controlled manner for productive use
4Quantity of substance
If waste plastics with low density are processed, then the material can be fed, but the rate at which waste plastics enter the reaction device is low resulting in small processing scale
Solution Approach 1:
The patent employs pneumatic or hydraulic conveying systems to transport low-density waste plastic materials into the reaction device. By using fluidized bed technology or pneumatic conveying, the system can handle light, low-density materials efficiently, maintaining high feed rates and enabling large-scale processing that overcomes the limitations of gravity-based feeding systems
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 method enables effective utilization of waste plastics, increasing gasoline production, reducing coke generation, and facilitating large-scale, continuous recycling with improved processing efficiency and reduced costs.
Implementation Method 1
S1. the waste plastic to be treated is sent to a liquefaction unit for waste plastics for liquefaction treatment to produce a liquefied waste plastic
Implementation Method 2
S2. the liquefied waste plastic is sent to a viscosity reduction unit for waste plastics for a viscosity reduction treatment to produce a viscosity-reduced liquefied waste plastic oil
Implementation Method 3
S3. the viscosity-reduced liquefied waste plastic oil is sent to a contact-cracking reaction unit, and contacted with a contact agent in a fluidized state to perform a cracking reaction
Implementation Method 4
the spent contact agent is sent to a regeneration unit, and the spent contact agent is regenerated in the presence of oxygen gas to produce a regenerated contact agent and a regeneration flue gas
Data Source
AI summary
A plastic processing method includes the following steps: S1. the plastic to be treated is sent to a liquefaction unit for liquefaction treatment to produce a liquefied material; S2. subjecting the liquefied material to heat treatment in a viscosity reduction unit to reduce its viscosity to produce a viscosity-reduced liquefied material; S3. the viscosity-reduced liquefied material is sent to a cracking reaction unit for cracking reaction to produce a reaction product; S4. the reaction product is sent to a separation unit for separation treatment. The system for carrying out the plastic processing method has a liquefaction unit, a viscosity reduction unit, a cracking reaction unit, and a separation unit.