Waste Plastic Cracking Dechlorination via Segmented Temperature Zones
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Solution Overview
Problem
Current waste plastic treatment methods, particularly chemical recycling, face challenges with high chlorine content in cracked products, leading to equipment corrosion, catalyst poisoning, and operational issues, necessitating effective dechlorination to reduce chlorine levels and improve product quality.
Innovation Solution
A multi-stage dechlorination process involving pre-treatment, two-stage cracking with temperature-controlled zones and a dechlorination agent, specifically using a continuous reactor with sequential pre-treatment and cracking units to manage chlorine content and prevent recombination of chlorine gases, ensuring efficient removal of HCl and organic chlorine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical recycling is used to treat waste plastic, then the quality of recycled plastics is improved and carbon emission is reduced, but the chlorine content in cracked products becomes high causing equipment corrosion and catalyst poisoning
Solution Approach 1:
The cracking process is divided into two distinct stages: first cracking at lower temperature (200-300°C) and second cracking at higher temperature (300-500°C). This segmentation allows controlled dechlorination in the first stage before the main cracking occurs in the second stage, reducing chlorine content in the final cracked products while maintaining high quality recycled plastics.
Solution Approach 2:
The first cracking stage serves as a preliminary dechlorination step before the main cracking process. By conducting low-temperature cracking first, chlorine is removed from the waste plastic in advance, preventing catalyst poisoning and equipment corrosion in subsequent processing stages while preserving the quality of the final recycled plastic products.
2Adaptability or versatility
If waste plastic containing chlorine is subjected to cracking process, then chemical recycling is achieved, but equipment corrosion and catalyst poisoning occur due to generated chlorinated hydrocarbons
Solution Approach 1:
The cracking process is divided into two distinct stages: first cracking at lower temperature (200-300°C) and second cracking at higher temperature (300-500°C). This segmentation allows controlled dechlorination in the first stage before the main cracking occurs in the second stage, reducing chlorine content in the final cracked products while maintaining high quality recycled plastics.
Solution Approach 2:
The first cracking stage serves as a preliminary dechlorination step before the main cracking process. By conducting low-temperature cracking first, chlorine is removed from the waste plastic in advance, preventing catalyst poisoning and equipment corrosion in subsequent processing stages while preserving the quality of the final recycled plastic products.
3Device complexity
If single-stage cracking is used for waste plastic treatment, then the process is simple, but the chlorine content in cracked products remains high and requires additional dechlorination steps
Solution Approach 1:
The cracking process is divided into two distinct stages: first cracking at lower temperature (200-300°C) and second cracking at higher temperature (300-500°C). This segmentation allows controlled dechlorination in the first stage before the main cracking occurs in the second stage, reducing chlorine content in the final cracked products while maintaining high quality recycled plastics.
Solution Approach 2:
The cracking process utilizes temperature as a key parameter to differentiate between the two stages. The first stage operates at lower temperature (200-300°C) favoring dechlorination reactions, while the second stage operates at higher temperature (300-500°C) for complete cracking. This parameter change enables effective chlorine removal without requiring complex additional dechlorination equipment.
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 effectively reduces chlorine content in cracked products, alleviating downstream processing burdens and enhancing the quality of recycled plastics, thereby improving the efficiency and stability of the waste plastic treatment process.
Implementation Method 1
inputting the waste plastic into the first pre-treatment unit for a first pre-treatment to remove impurity and grease on a surface of the waste plastic
Implementation Method 2
Cracking of waste plastics refers to that the waste plastics are used as raw materials and subjected to high-temperature pyrolysis or catalytic cracking
Implementation Method 3
The second cracking unit is loaded with a dechlorination agent... inputting a second material output from the first cracking unit into the second cracking unit for a second cracking treatment, to obtain a treated product
Data Source
AI summary
The present application provides a treatment method and device for a waste plastic. A first aspect of the present application provides a treatment method for a waste plastic, including: firstly subjecting the waste plastic to a first pre-treatment to remove impurity and grease on a surface of the waste plastic, then subjecting the waste plastics to a second pre-treatment to convert a solid waste plastic into one in flow state; and finally, subjecting the waste plastic in flow state to a first cracking treatment and a second cracking treatment in sequence. Through the method provided in the present application, while cracking the waste plastic, chlorine element in the waste plastic may be removed by a multi-stage adsorption, which reduces chlorine content in the cracked oil, reduces pressure and burden in subsequent refining, and meets the limitation of the chlorine content in cracked products in downstream processes.