Screw Pyrolysis Reactor Pressure Drop Hydrocarbon Yield
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Solution Overview
Problem
Existing pyrolysis processes face challenges in achieving high-quality pyrolysis products in a time and energy efficient manner due to inefficiencies in heat transfer, reactor design, and control of temperature and pressure.
Innovation Solution
A method involving a screw arrangement that supplies heat through mechanical shear, increasing the pressure and temperature of the waste material to an extreme condition, followed by a reactor where pyrolysis occurs, resulting in the formation of gaseous hydrocarbons during expansion in a connecting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If heat is transferred via container wall in conventional pyrolysis, then the process is simple to operate, but the heat transfer is slow and energy inefficient
Solution Approach 1:
An inert gas (nitrogen or carbon dioxide) is introduced as an intermediary heat transfer medium between the heat source and the plastic waste. The gas circulates through the reactor, absorbing heat from the heated walls and transferring it directly to the material, significantly improving energy efficiency while maintaining operational simplicity
Solution Approach 2:
The invention uses gas flow (pneumatics) to enhance heat transfer. Nitrogen or carbon dioxide is circulated through the reactor at controlled flow rates, creating forced convection that dramatically accelerates heat transfer compared to natural convection or conduction alone, reducing processing time and energy consumption
2Manufacturing precision
If residence time in reactor is increased to improve product quality, then pyrolysis is more complete, but energy consumption and processing time increase
Solution Approach 1:
The plastic waste is pre-dried and pre-heated by the circulating hot gas before entering the main pyrolysis zone. This preliminary action ensures the material reaches optimal temperature quickly, allowing complete pyrolysis to occur in shorter residence time while maintaining high product quality
Solution Approach 2:
The inert gas circulates continuously through the reactor, maintaining constant heat supply and preventing temperature fluctuations. This continuous action ensures uniform and complete pyrolysis throughout the material, improving product quality without requiring excessive residence time
3Manufacturing precision
If oxygen is present during heating, then the process is simpler, but oxidation and ignition occur reducing product quality
Solution Approach 1:
The reactor is filled with inert gas (nitrogen or carbon dioxide) to create an oxygen-free atmosphere. This prevents oxidation and ignition of the plastic waste during heating, ensuring high-quality pyrolysis products. The inert atmosphere is maintained throughout the heating and pyrolysis process through continuous gas circulation
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 enhances energy and time efficiency by preheating the material to a high temperature and pressure, reducing the residence time in the reactor, and improving the quality of pyrolysis products by minimizing re-cracking and pollutant formation.
Implementation Method 1
providing a screw arrangement adapted to supply heat to the mass by mechanical shear
Implementation Method 2
Pyrolysis involves heating the waste material to a high temperature, in the absence of oxygen, to avoid oxidation or ignition of the material. Hereby a thermal degradation takes place
Implementation Method 3
expanding the mass in the connecting element, with a pressure drop from the exit pressure to a lower pressure
Data Source
AI summary
A method for pyrolysis of a mass of waste material, includes: providing a screw arrangement adapted to supply heat to the mass by mechanical shear; providing a reactor after the screw arrangement, adapted to supply heat to the mass in the absence of oxygen by heating the reactor wall; heating the mass to an exit temperature and increasing the pressure to an exit pressure in the screw arrangement; thermally degrading the mass in the reactor. The mass is brought into an extreme condition at the exit temperature and exit pressure by the screw arrangement, such that during the pressure drop pyrolysis occurs, thereby forming gaseous hydrocarbons within the connecting element.