Biomass Pellet Processing Without Post-Drying Hammermilling
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Solution Overview
Problem
Existing biomass pellet production processes face inefficiencies due to variable raw material size distribution, high energy consumption, tool wear, and the need to recycle fines, with dry hammermilling causing additional energy costs and fire risks.
Innovation Solution
A method and apparatus that perform all necessary size reduction and screening before the drying stage, eliminating dry hammermilling, using multiple screening and sizing stages to ensure uniform biomass pieces enter the dryer, followed by pelletizing to form pellets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry hammermilling is used to reduce particle size after drying, then size reduction is achieved, but energy consumption increases and tool wear increases
Solution Approach 1:
The patent performs all size reduction operations (green hammermilling and screening) before the drying stage, eliminating the need for subsequent dry hammermilling. This preliminary action ensures particles are sized while still moist and pliable, avoiding the high energy costs and tool wear associated with dry grinding.
Solution Approach 2:
The patent changes the moisture content parameter from high (before drying) to low (after drying), but crucially maintains size reduction operations during the high moisture phase. This parameter change exploits the physical property that wet material is softer and easier to size, reducing energy requirements compared to dry grinding.
2Manufacturing precision
If dry hammermilling is used after drying, then size reduction is achieved, but fire risk increases
Solution Approach 1:
The patent performs all size reduction operations before the drying stage when material is still moist. By completing grinding and screening while material contains moisture, the patent eliminates the fire hazard associated with dry pulverization, as moisture acts as a natural fire suppressant.
3Adaptability or versatility
If variable size distribution enters the dryer, then processing flexibility is maintained, but drying uniformity decreases
Solution Approach 1:
The patent implements screening and size reduction operations before drying to create a more uniform particle size distribution. This preliminary sizing ensures that all particles entering the dryer have similar dimensions and surface area-to-volume ratios, enabling uniform moisture removal throughout the batch.
Solution Approach 2:
The patent creates homogeneity in particle size before drying through pre-screening and green hammermilling. By ensuring particles are of similar size before the drying process begins, the patent achieves uniform drying characteristics across all material in the dryer.
4Manufacturing precision
If multiple sizing stages are implemented, then particle size control improves, but process complexity increases
Solution Approach 1:
The patent combines screening and size reduction operations into integrated stages before drying. By merging these operations and performing them sequentially before the drying stage, the patent achieves precise particle size control without requiring multiple separate sizing units after drying, thus reducing overall process complexity.
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
Reduces energy consumption, minimizes fire risks, simplifies plant configuration, and lowers maintenance costs by ensuring homogeneous drying and eliminating the need for dry hammermilling, while improving pellet quality and reducing waste.
Implementation Method 1
driving off moisture from the biomass in a drying stage
Data Source
AI summary
A method and apparatus are provided for producing biomass pellets. Biomass pieces are received in a sizing stage and the biomass pieces are processed in the sizing stage to reduce their average size. Moisture is driven off moisture from the biomass in a drying stage. The biomass is compressed to form pellets in a pelletizing stage. After the drying stage, there is no further active reduction in the average size of the biomass pieces.