Biomass Fuel Pellet Composition for Grindable Coal-Fired Use
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Solution Overview
Problem
Existing fuel pellets made from biomass have lower heating value and poor handling characteristics, making them unsuitable for coal-fired furnaces and industrial boiler applications due to their low grindability and tendency to crumble.
Innovation Solution
The development of biomass-based fuel pellets comprising 5-15 wt.% thermoplastic polymeric material and at least 75 wt.% cellulosic material, formed by compression and extrusion, which infuses the polymeric material into cellulosic fibers, resulting in pellets with improved grindability and handling characteristics, similar to coal, and a heat value of at least 9,500 Btu/lb.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If biomass fuel pellets are made from cellulosic material alone, then they are environmentally friendly and renewable, but they have poor handling characteristics and low heating value
Solution Approach 1:
The patent combines cellulosic biomass material with thermoplastic polymeric material to create a composite fuel pellet. The thermoplastic component (5-20% of total weight) acts as a binder that improves pellet durability and handling characteristics while the majority cellulosic content (80-95% of total weight) maintains the renewable and environmentally friendly properties. This composite approach resolves the contradiction by integrating the advantages of both materials.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the fuel pellet by controlling the moisture content (5-15%), density (30-45 lb/ft³), and heating value (9,500-11,000 Btu/lb) through the addition of thermoplastic material and optimized compression processes. These parameter changes improve handling characteristics while maintaining environmental benefits.
2Use of energy by moving object
If biomass fuel pellets are made with higher density, then heating value increases, but grindability decreases
Solution Approach 1:
The patent optimizes the density parameter to a specific range (30-45 lb/ft³) that balances heating value and grindability. By controlling density within this range and adjusting moisture content to 5-15%, the patent achieves adequate heating value (9,500-11,000 Btu/lb) while maintaining acceptable grindability for pulverized coal-fired boilers.
Solution Approach 2:
The patent creates local quality variations within the pellet structure through the thermoplastic binder distribution, where the binder provides localized binding strength in critical areas while maintaining overall porosity and density characteristics that facilitate both high heating value and acceptable grindability.
3Reliability
If thermoplastic polymeric material is added to improve pellet durability, then handling characteristics improve, but the proportion of cellulosic material decreases
Solution Approach 1:
The patent creates a composite formulation where thermoplastic polymeric material (5-20% of total weight) serves as a binder to improve pellet durability and handling characteristics. The majority composition remains cellulosic biomass (80-95% of total weight), ensuring the fuel maintains its renewable and environmentally friendly properties while achieving the desired mechanical strength for commercial handling and transportation.
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 pellets exhibit enhanced grindability, durability, and handling properties, with a Hardgrove Grindability Index (HGI) of no more than 80 and a Pellet Durability Index (PDI) of at least 80, allowing them to be used as a suitable heat source in coal-fired systems while reducing fugitive dust emissions.
Implementation Method 1
this may be accomplished by extrusion of the feed mixture, typically at a temperature at which the thermoplastic polymeric material is in a molten state
Implementation Method 2
the biomass/polymer feedstock mixture is typically subjected to a pressure of no more than about 2,500 psi
Data Source
AI summary
A method of producing a biomass-based fuel pellet, such as a fuel pellet which includes thermoplastic polymeric material and a substantial amount of cellulosic material, e.g. cellulosic material derived from biomass source(s), is provided. The method commonly includes compressing a feed mixture to form a densified material, where the feed mixture includes about 5 to 15 wt. % of the thermoplastic polymeric material and at least about 75 wt. % cellulosic material. Many embodiments of the fuel pellets are suitable for use in a coal-fired furnace and/or in other industrial boiler applications.