Biomass Pyrolysis Char Entrainment Reduction
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Solution Overview
Problem
Conventional biomass fast pyrolysis processes face issues with catalyst deactivation and equipment fouling due to char fines and metal entrainment, which affect the stability and upgradability of pyrolysis oil products.
Innovation Solution
The process involves pyrolyzing biomass feedstock with particles greater than 300 microns in diameter to minimize char entrainment in the primary gaseous product, thereby reducing metal content and preventing catalyst deactivation, using an auger to distribute heat and separate char from vapors, and rapidly upgrading the vapors with catalysts to produce fungible hydrocarbon fuels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If biomass feedstock with small particle size is used for fast pyrolysis, then heating efficiency and reaction rate are improved, but char fines are more easily entrained with pyrolysis vapors causing catalyst deactivation and equipment fouling
Solution Approach 1:
The patent changes the particle size parameter of the biomass feedstock from conventional small sizes (typically <1mm) to larger sizes (0.5-2cm), which fundamentally alters the pyrolysis process dynamics. This parameter change reduces char fines generation and entrainment while maintaining acceptable heating rates through optimized reactor design and residence time control.
Solution Approach 2:
The patent applies preliminary size classification to the biomass feedstock, separating and removing fine particles before pyrolysis processing. This preliminary action prevents fine particles from entering the pyrolysis reactor where they would generate entrainable char fines, thus protecting downstream catalysts and equipment before the harmful effects can occur.
2Reliability
If catalysts are employed during pyrolysis to deoxygenate primary products, then fuel quality is improved, but catalysts rapidly deactivate when contacted by char fines
Solution Approach 1:
The patent extracts and removes char fines from the pyrolysis product stream before the vapors contact the upgrading catalysts. This is achieved through optimized reactor design that separates vapor-phase products from solid particulates, ensuring that catalysts are exposed only to clean vapors and not contaminated by char fines that would cause deactivation.
Solution Approach 2:
The patent introduces an intermediary separation zone or device between the pyrolysis reactor and catalyst bed that acts as a mediator. This intermediary component captures and retains char fines while allowing pyrolysis vapors to pass through to the catalysts, protecting the catalysts from direct contact with deactivating particulates.
3Quantity of substance
If char fines are carried out of the pyrolyzer by vapor entrainment, then mass transfer is enhanced, but the liquid product contains solids and metals that negatively impact downstream processes
Solution Approach 1:
The patent changes the physical state and concentration parameters of the pyrolysis product stream by controlling vapor velocity, temperature, and pressure gradients. These parameter changes optimize the separation between vapor-phase products (which are retained for high yield) and solid char fines (which are allowed to settle or are actively removed), preventing equipment fouling while maintaining product quantity.
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 extends catalyst lifespan, maximizes the upgradability of pyrolysis vapors to petroleum-derived fuels, and reduces metal contamination in pyrolysis oil, enhancing the stability and quality of the final fuel products.
Implementation Method 1
using an auger to distribute heat
Implementation Method 2
pyrolyzing a biomass feedstock in a reactor, wherein the pyrolyzing forms products comprising a primary gaseous product and char
Data Source
AI summary
The present disclosure relates generally to novel biomass pyrolysis processes and systems that decrease entrainment of char and other contaminants with the pyrolysis vapors as a direct consequence of the biomass feedstock comprising particles that are larger than a defined minimum diameter. The biomass feedstock may optionally be compressed to form feedstock pellets that are larger than a defined minimum diameter.