Torrefied Biomass Pelletization via Self-Heating Fluidized Bed
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Solution Overview
Problem
Biomass, due to its high moisture and oxygen content, is a low-grade, high-cost fuel that cannot compete with fossil fuels for energy production, and existing torrefaction processes are inefficient and require external heat sources, making it difficult to handle and process effectively.
Innovation Solution
A torrefaction process using a fluid bed reactor with internal heat generation from biomass combustion, reducing moisture content, increasing heating value, and improving grindability and handling characteristics, while allowing the use of biomass in existing fossil fuel burning power plants with minimal modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If external heat sources are used for torrefaction, then the biomass can be processed, but the process becomes inefficient and costly
Solution Approach 1:
The biomass fuel bed serves itself by generating the heat required for torrefiction through controlled combustion of the biomass itself, eliminating the need for external heat sources. The system uses the fuel material to provide the thermal energy needed for its own processing.
Solution Approach 2:
The torrefiction process and combustion process are merged into a single integrated system where the biomass undergoes both torrefiction and controlled combustion in the same reactor, allowing heat generation and material processing to occur simultaneously.
2Use of energy by moving object
If biomass moisture content is high, then the fuel is easier to handle initially, but the heating value decreases and processing costs increase
Solution Approach 1:
The torrefiction process changes the moisture content parameter of the biomass from high (10-50%) to low (<10%), simultaneously improving heating value and handling characteristics. The controlled thermal processing transforms the physical and chemical properties of the biomass.
3Productivity
If biomass is torrefied to improve handling and energy density, then the fuel quality improves, but the processing time and temperature requirements increase
Solution Approach 1:
The torrefiction process operates continuously with biomass being fed into the reactor and processed material being removed continuously. The controlled combustion provides sustained heat generation throughout the process, maintaining optimal temperatures without interruption.
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 achieves a 55-65% mass recovery of salable torrefied biomass with 80-85% energy recovery, nearly complete sulfur removal, and reduced chlorine content, enhancing energy density and hydrophobicity, and allows for efficient handling and use in existing power plants.
Implementation Method 1
heat generated by the combustion of biomass and hot gases associated with biomass combustion provide the heat required to support the torrefiction/roasting process
Implementation Method 2
In this type of reactor, gas or liquid is passed through a granular solid material at high enough velocity to suspend the solid and cause it to behave as though it were a fluid
Implementation Method 3
heat generated by the combustion of biomass and hot gases associated with biomass combustion provide the heat required to support the torrefiction/roasting process
Data Source
AI summary
A process for torrefaction of biomass is provided in which biomass are passed into a fluidized bed or a non-fluidized bed reactor and heated to a predetermined temperature in an oxidizing environment. The dried biomass is then fed to a cooler where the temperature of the product is reduced to approximately 100 degrees Fahrenheit.