Low-Ash Biomass Pellet Process via Acetic Acid Extraction
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Solution Overview
Problem
Biomass combustion faces challenges due to high moisture content, irregular shapes, and high ash content, which reduce boiler efficiency and increase environmental emissions, and there is a need for processes to produce low-ash biomass for improved combustion and potential recovery of co-products like fermentable sugars and lignin.
Innovation Solution
A process involving the use of steam and/or hot water with acetic acid to extract soluble ash and hemicellulosic oligomers from cellulosic biomass, followed by hydrolysis to produce fermentable sugars, and subsequent drying to create low-ash biomass, which can be pelletized for efficient combustion, while also recovering lignin and other co-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If biomass is used for combustion, then renewable energy production is achieved, but high ash content reduces boiler efficiency and increases emissions
Solution Approach 1:
The patent applies extraction by treating biomass with aqueous acetic acid to dissolve and remove ash-containing components (calcium, potassium, sodium salts) from the biomass matrix. This separates the harmful ash components from the combustible organic material, allowing energy production while reducing emissions.
Solution Approach 2:
The patent changes the chemical environment by using acetic acid solution to alter the solubility of ash components. The acid treatment transforms insoluble ash into soluble forms that can be washed away, changing the physical-chemical parameters of the biomass to achieve lower ash content.
2Ease of operation
If biomass has high moisture content, then it is easier to store and handle, but boiler efficiency decreases due to energy loss for evaporation
Solution Approach 1:
The patent uses the biomass itself as the energy source for drying. The organic material in the biomass provides the necessary heat through controlled decomposition or combustion to evaporate moisture, eliminating the need for external energy inputs while preparing the biomass for efficient combustion.
3Ease of manufacture
If irregularly shaped biomass is fed to boiler, then material handling is simpler, but combustion efficiency decreases and material bridges or lodges in silos
Solution Approach 1:
The patent applies segmentation by breaking down irregular biomass into smaller, more uniform particles or pellets. This division of the original material into standardized segments improves flow characteristics, prevents bridging in silos, and enhances combustion efficiency while maintaining ease of handling through mechanized processing.
4Object-generated harmful factors
If acetic acid extraction is performed to remove ash, then low-ash biomass is produced, but process complexity increases
Solution Approach 1:
The patent applies multi-functionality by using acetic acid extraction to simultaneously achieve multiple objectives: removing ash components, recovering valuable minerals for fertilizer production, and preparing biomass for combustion. This consolidates multiple process functions into a single integrated operation, reducing overall system complexity.
Solution Approach 2:
The patent recovers valuable components (minerals, nutrients) from the extraction process that would otherwise be discarded with the ash. By transforming waste ash into recoverable resources for fertilizer production, the process complexity is justified by creating additional value streams and reducing environmental impact.
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 process results in low-ash biomass with higher energy density and lower inorganic emissions, suitable for co-firing with coal, and reduces the need for expensive environmental controls, enhancing boiler efficiency and producing fermentable sugars and potential fertilizers.
Implementation Method 1
treating the feedstock with the extraction solution under effective extraction conditions to produce an extract liquor containing soluble ash, hemicellulosic oligomers
Implementation Method 2
providing an extraction solution comprising steam and/or hot water, and starting acetic acid; treating the feedstock with the extraction solution
Implementation Method 3
hydrolyzing the hemicellulosic oligomers contained in the extract liquor, under effective hydrolysis conditions, to produce fermentable hemicellulosic sugars
Implementation Method 4
removing a vapor stream comprising water and vaporized acetic acid from the extract liquor in at least one evaporation stage
Implementation Method 5
removing a vapor stream comprising water and vaporized acetic acid from the extract liquor in at least one evaporation stage at a pH of 4.8 or less
Implementation Method 6
drying the dewatered solids to produce the low-ash biomass
Data Source
AI summary
This invention provides processes and apparatus to convert biomass, including wood and agricultural residues, into low-ash biomass pellets for combustion, alone or in combination with another solid fuel. Some embodiments provide processes for producing low-ash biomass from cellulosic biomass, comprising providing an aqueous extraction solution with acetic acid; extracting the feedstock to produce an extract liquor containing soluble ash, hemicellulosic oligomers, acetic acid, dissolved lignin, and cellulose-rich solids; dewatering and drying the cellulose-rich, lignin-rich solids to produce a low-ash biomass; hydrolyzing the hemicellulosic oligomers to produce hemicellulosic sugars, wherein additional acetic acid is generated; removing a vapor stream comprising vaporized acetic acid from the extract; and recycling the vapor or its condensate to provide some starting acetic acid for the extraction solution. The disclosed processes can produce clean power from biomass. Co-products may include fermentable sugars, fermentation products such as ethanol, fertilizers, and lignin.