Biomass Pyrolysis Quenching for Low-Formaldehyde Liquid Products
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Solution Overview
Problem
Conventional biomass pyrolysis products contain high levels of formaldehyde, exceeding safety limits in workplace environments, posing health risks and necessitating the development of methods to reduce formaldehyde concentrations.
Innovation Solution
A method involving pyrolyzing biomass, condensing gaseous pyrolysis products with a nonaqueous coolant like dodecane, and separating a low-formaldehyde product to achieve a formaldehyde concentration of no more than 150 ppm, using a process that includes pyrolyzing biomass, condensing with a nonaqueous coolant, and separating the low-formaldehyde product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional biomass pyrolysis is used to produce liquid products, then valuable products are obtained, but formaldehyde concentration becomes excessively high exceeding safety limits
Solution Approach 1:
The patent extracts formaldehyde from the pyrolysis product stream through selective condensation. By controlling condensation temperature and using specific coolant systems, formaldehyde is separated from the liquid product, reducing its concentration from potentially hazardous levels (up to 1.9 wt.% in conventional processes) to below detection limits or safe threshold levels.
Solution Approach 2:
The patent changes physical parameters during the condensation process, specifically temperature and pressure conditions, to selectively condense formaldehyde while maintaining other product components in vapor phase. This parameter control enables selective removal of formaldehyde without compromising the valuable liquid products.
2Productivity
If higher cooling efficiency is used to condense more pyrolysis products, then product yield increases, but formaldehyde concentration in the product increases
Solution Approach 1:
The patent applies different cooling conditions to different portions of the pyrolysis product stream. The condensation system is designed with zones of varying temperature, allowing selective condensation of desired products in one zone while formaldehyde is removed in another zone through controlled cooling rates and temperature gradients.
Solution Approach 2:
The patent performs preliminary separation of formaldehyde through controlled condensation before final product collection. By removing formaldehyde early in the condensation process through specific temperature control, subsequent condensation steps can efficiently produce high-yield liquid products without incorporating excessive formaldehyde.
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
The method effectively reduces formaldehyde levels in pyrolysis products to safe concentrations, enabling their safe handling and utilization in various applications.
Implementation Method 1
contacting the gaseous pyrolysis products with a nonaqueous coolant, wherein the nonaqueous coolant is dodecane
Implementation Method 2
condensing a portion of the gaseous pyrolysis products to form the low-formaldehyde product
Implementation Method 3
pyrolyzing biomass, wherein the biomass comprises one or more sugars and/or one or more starches to form gaseous pyrolysis products
Implementation Method 4
pyrolyzing biomass... to form gaseous pyrolysis products
Data Source
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AI summary
Methods are provided to use water-free quench liquids to obtain pyroytic liquid products with reduced formaldehyde content. Products include liquids with improved hydroxyacetaldehyde content.