Fluidized Pyrolysis Reactor Heating for Higher Monomer Yield
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Solution Overview
Problem
Existing methods for depolymerizing polymers into monomers suffer from low yield due to side reactions and contamination, particularly from indirect heating techniques that cause temperature hot spots and inefficient condensation processes.
Innovation Solution
A fluidized reactor system with a pyrolysis chamber and combustion chamber uses circulating bed material to transfer heat directly, maintaining uniform temperatures and controlling the circulation rate to prevent over-cracking, while utilizing fluidization gas to regulate temperature differences and minimize contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect heating techniques are used in pyrolysis reactors, then the reactor structure is simpler, but temperature hot spots occur causing side reactions and reducing monomer yield
Solution Approach 1:
The patent introduces a circulating bed material as an intermediary heat transfer medium between the combustion chamber and pyrolysis chamber. This bed material absorbs heat in the combustion zone and releases it uniformly in the pyrolysis zone, eliminating temperature hot spots while maintaining high monomer yield through controlled heat distribution.
2Ease of operation
If heated air is used to fluidise the pyrolysis reactor, then the fluidisation process is simpler, but charring of products occurs and combustion products are diluted reducing condensation efficiency
Solution Approach 1:
The patent extracts the heating function from the fluidisation gas and transfers it to the circulating bed material. This allows the use of inert fluidisation gas (nitrogen or carbon dioxide) instead of heated air, preventing charring and avoiding dilution with combustion products, thereby maintaining high condensation efficiency while preserving fluidisation ease.
3Temperature
If steam is used to fluidise and heat the pyrolysis reactor, then the temperature control is improved, but the product gas is significantly diluted requiring additional complex techniques for monomer recovery
Solution Approach 1:
The circulating bed material serves as an intermediary that provides the necessary heat for pyrolysis without becoming part of the product gas. This allows the use of inert fluidisation gas instead of steam, achieving good temperature control while avoiding product gas dilution and the need for complex recovery techniques.
4Temperature
If the circulation rate of bed material is increased to transfer more heat, then the pyrolysis temperature is maintained, but over-cracking occurs reducing monomer yield
Solution Approach 1:
The patent implements a feedback control mechanism where the circulation rate of bed material is adjusted based on temperature measurements in the pyrolysis chamber. This ensures optimal heat transfer maintains the required pyrolysis temperature while preventing excessive circulation that would cause over-cracking and reduce monomer yield.
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 increases the yield of monomers by preventing side reactions and reducing contaminants, achieving efficient depolymerization with improved product gas quality.
Implementation Method 1
upon circulating the bed material sufficient heat is transferred from the combustion chamber to the pyrolysis chamber to execute the pyrolysis process
Implementation Method 2
A fluidised reactor system comprising a pyrolysis chamber, a combustion chamber, and bed material that circulates from the combustion chamber to the pyrolysis chamber
Implementation Method 3
inputting a feedstock comprising 60% or more polymers by weight of the feedstock into the pyrolysis chamber and executing a pyrolysis process at a temperature in the range of from 450 to 650° C. in the bed material to obtain a depolymerised polymer product gas comprising the monomers
Data Source
AI summary
Method for depolymerising polymers into one or more monomers. A fluidised reactor system is provided comprising a pyrolysis chamber (2), a combustion chamber (12), and bed material that circulates from the combustion chamber (12) to the pyrolysis chamber (2) via a transport zone (30). A feedstock comprising 60% or more polymers by weight of the feedstock is inputted into the pyrolysis chamber (2) and a pyrolysis process is executed at a temperature in the range of from 450 to 650° C. in the bed material to provide a depolymerised polymer product gas comprising the monomers. Circulation of the bed material allows for sufficient heat to be transferred from the combustion chamber (12) to the pyrolysis chamber (2) to execute the pyrolysis process.