Batch Reactor Pyrolysis for Waste Plastic Dechlorination
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Solution Overview
Problem
Existing pyrolysis methods of waste plastics face challenges such as impurity removal, equipment corrosion, reaction abnormality, and uneven melting of waste plastics, leading to inefficient chlorine removal and increased pressure fluctuations in reactors.
Innovation Solution
A step-wise temperature rise control operation is applied in a batch reactor, where waste plastics are heated in stages to separate the dechlorination reaction and pyrolysis reaction, ensuring uniform melting and efficient chlorine removal without additives or neutralizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If waste plastics are heated rapidly in a batch reactor, then pyrolysis reaction speed increases, but chlorine removal efficiency decreases and organic Cl recombination increases
Solution Approach 1:
The heating process is divided into three distinct temperature stages: first heating to melt waste plastics (50-150°C), then heating to remove chlorine (150-300°C), and finally heating to perform pyrolysis (300-600°C). This segmentation allows dechlorination and pyrolysis reactions to occur separately, preventing organic Cl recombination while maintaining high productivity.
Solution Approach 2:
The dechlorination reaction is performed as a preliminary step before pyrolysis. By removing chlorine at intermediate temperatures (150-300°C) before reaching pyrolysis temperatures, the harmful recombination of dissociated chlorine with pyrolysis oil is prevented, resulting in lower final chlorine content.
2Use of energy by moving object
If temperature is raised uniformly throughout the reactor, then heating efficiency increases, but waste plastics melt unevenly and gas outlet blockage occurs
Solution Approach 1:
Different regions of the reactor are heated to different temperatures according to the progress of waste plastics. The reactor implements localized temperature control where the front section reaches higher temperatures for pyrolysis while the rear section maintains lower temperatures for melting and dechlorination, ensuring uniform melting and preventing blockage.
Solution Approach 2:
The reactor temperature distribution is dynamically adjusted during the heating process. As waste plastics progress through the reactor, the temperature profile changes to match the reaction stage: initial melting zone, intermediate dechlorination zone, and final pyrolysis zone, ensuring reliable operation throughout.
3Loss of time
If dechlorination and pyrolysis reactions are performed simultaneously, then process time decreases, but chlorine removal efficiency decreases due to organic Cl recombination
Solution Approach 1:
The reaction process is segmented into distinct temperature zones within the same reactor: a dechlorination zone at 150-300°C and a pyrolysis zone at 300-600°C. Waste plastics pass through these zones sequentially, allowing dechlorination to complete before pyrolysis begins, preventing recombination while maintaining continuous flow and reasonable process time.
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 method effectively controls the dechlorination and pyrolysis reactions, increasing chlorine removal efficiency, preventing reactor blockages, and stabilizing pressure fluctuations, resulting in a higher-quality pyrolysis oil with reduced chlorine content.
Implementation Method 1
inputting waste plastics to a batch reactor and heating to thereby produce a waste plastic melt at a first temperature
Implementation Method 2
heating the waste plastic melt to thereby remove chlorine from the melt at a second temperature
Implementation Method 3
heating the waste plastic melt from which chlorine has been removed to thereby produce a pyrolysate at a third temperature
Data Source
AI summary
Provided is a pyrolysis method of waste plastics including the steps of inputting waste plastics to a batch reactor and performing heating to produce a waste plastic melt at a first temperature; heating the waste plastic melt to remove chlorine from the melt at a second temperature; and heating the waste plastic melt from which chlorine has been removed to produce a pyrolysate at a third temperature. The batch reactor is sequentially heated in a direction from a raw material inlet to a reaction product outlet so that the temperature is raised from the first temperature to the third temperature.