Waste Plastic Thermolysis for High-Purity Hydrocarbon Production
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Solution Overview
Problem
Existing methods for converting waste plastics into high-value hydrocarbon products often result in secondary degradation reactions and impurities, limiting product purity and flexibility, and are energy-intensive and costly due to inefficient catalyst use and impurity removal processes.
Innovation Solution
A continuous thermolysis process involving two-stage separation and a specific sequence of hydrogenation and hydrodesulphurization steps, combined with catalytic dewaxing and bleaching, ensures precise fraction separation and high purity, reduces energy costs, and allows for the use of less active and cheaper catalysts, while absorbers with bleaching clay ensure reproducible oil properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage cracking process is used to convert waste plastics, then the process is simpler and more direct, but secondary degradation reactions occur and product purity is limited
Solution Approach 1:
The cracking process is divided into two distinct stages: a first cracking reactor operating at higher temperature (380-500°C) for initial depolymerization, followed by a second cracking reactor operating at lower temperature (260-300°C) for refinement. This segmentation allows each stage to perform a specific function, preventing secondary degradation reactions and achieving high product purity while maintaining reasonable process complexity
Solution Approach 2:
A heat exchanger is introduced as an intermediary device between the two cracking reactors. This heat exchanger cools the effluent from the first reactor before it enters the second reactor, acting as a mediator that controls the thermal conditions and prevents excessive temperature that would cause degradation. This intermediary component enables precise temperature control to achieve high purity products
2Productivity
If high-activity catalysts are used to improve cracking efficiency, then the cracking rate increases, but catalyst cost and consumption increase
Solution Approach 1:
The catalytic cracking process is segmented into two stages with different catalyst requirements. The first reactor uses a catalyst for initial depolymerization, while the second reactor uses a different catalyst optimized for refinement at lower temperatures. This segmentation allows each catalyst to operate in its optimal range, improving overall cracking efficiency while reducing the need for high-activity (and expensive) catalysts throughout the entire process
Solution Approach 2:
The process changes the operating temperature parameter between the two reactors - the first operates at 380-500°C and the second at 260-300°C. This parameter change allows the use of less active, cheaper catalysts in the second reactor where lower temperatures are sufficient for the refinement stage, thereby reducing catalyst consumption and cost while maintaining high productivity
3Manufacturing precision
If extensive impurity removal processes are used to achieve high product purity, then product quality improves, but energy consumption and processing cost increase
Solution Approach 1:
The first cracking reactor performs preliminary depolymerization of waste plastics into smaller hydrocarbon chains, breaking down the complex polymeric structure before the second stage. This preliminary action simplifies the material that enters the second reactor, reducing the energy required for further processing and impurity removal, while still achieving high final product purity
Solution Approach 2:
The process converts the harmful effect of high temperature (which causes secondary degradation) into a benefit by using it only in the first reactor for efficient depolymerization, then cooling the effluent before the second reactor. This converts the potential harm of thermal degradation into a beneficial two-stage temperature control strategy that reduces energy consumption for impurity removal while maintaining high purity
4Device complexity
If a simple single-reactor system is used, then the system is less complex and cheaper, but flexibility in product range and purity control is limited
Solution Approach 1:
The system is segmented into two independent but connected cracking reactors, each capable of operating within specific temperature ranges and using different catalysts. This segmentation provides flexibility to adjust each reactor's parameters independently, allowing control over the range and purity of products produced, while keeping each individual reactor unit relatively simple and cost-effective
Solution Approach 2:
The system introduces dynamic control through the heat exchanger that can adjust the cooling of effluent between the two reactors. This dynamic element allows flexible control over the temperature and conditions entering the second reactor, enabling adaptation to different product requirements and purity levels while maintaining a relatively simple overall system architecture
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 enables the production of high-purity, high-value hydrocarbon products with broad application potential, reducing catalyst consumption and energy costs, and ensuring consistent oil quality, suitable for industries like cosmetics and pharmaceuticals.
Implementation Method 1
in temperature of 380 - 500 °C polymeric chains' cracking and producing light hydrocarbons takes place
Implementation Method 2
from which vapor-liquid mixture is transported to separator from which the liquid phase is returned into cracking reactor and gaseous phase is conducted to water-cooled condenser
Implementation Method 3
gaseous phase is conducted to water-cooled condenser followed by cracking gas tank
Implementation Method 4
The liquid phase is separated on gasoline fraction conducted into tank and diesel oil conducted into tank in distillation column
Implementation Method 5
hydrogenation of the feedstock in hydrogenation reactor
Implementation Method 6
hydrodesulphurization in hydrodesulphurization reactor
Implementation Method 7
absorbers with bleaching clay ensure reproducible oil properties
Data Source
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AI summary
The subject of the invention is a method of production high-value hydrocarbon products from waste plastics and an apparatus for method of production high-value hydrocarbon products from waste plastics and an apparatus for the method. The method of obtaining in an inert gas atmosphere in which wastes are fed to the extruder and melted then depolymerized in thermolysis reactor and the depolymerization products vapors are conducted to preliminary separation unit in which preliminary separation takes place, according to invention is characterized in that obtained fractions are hydrorefined and then conducted to the secondary separation unit and additional finishing operations unit. Apparatus according to the invention is characterized in that after preliminary separation unit (3) hydrorefining system (4) is situated and then secondary separation unit (5) and finishing operation unit (6) are situated.