Torrefaction System for Mixed Waste to Solid Fuel
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Solution Overview
Problem
Current waste management methods, such as Waste-to-Energy and recycling, face challenges like high operational costs, batch-to-batch inconsistencies, heterogeneity in waste streams, low feedstock density, and inefficient polymer separation, making them economically prohibitive for effective waste disposal and recycling.
Innovation Solution
A system and method for torrefaction of waste materials, involving a multi-stage shredding process, heating and compaction unit, and reactor system to convert mixed biogenic and plastic waste into a solid fuel, utilizing a series of shredders, an auger-based heating and compaction unit, and a reactor system to achieve efficient processing and conversion of waste into torrefied products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Waste-to-Energy approach is used to address waste disposal, then waste disposal capability is improved, but operational costs and gas cleanup costs increase to economically prohibitive levels
Solution Approach 1:
The patent changes the thermal processing parameters by using torrefiction at 280-500°C in an oxygen-starved environment rather than complete combustion, and controls the heating rate and residence time to optimize energy efficiency and reduce cleanup costs while maintaining waste disposal capability
Solution Approach 2:
The patent creates an oxygen-starved or inert atmosphere in the reactor during torrefiction processing, which prevents complete combustion and reduces the formation of harmful emissions, thereby lowering gas cleanup costs while still achieving waste disposal and energy recovery
2Productivity
If recycling is mandated to achieve high recycling rates, then recycling rate is improved, but costs increase to economically prohibitive levels due to batch inconsistencies, heterogeneity, and inefficient separation
Solution Approach 1:
The patent changes the processing approach by using thermal torrefiction parameters (temperature, time, atmosphere) that homogenize heterogeneous waste materials, converting mixed waste into a consistent solid fuel product that can be efficiently utilized without expensive separation processes
Solution Approach 2:
The patent creates a composite torrefied solid fuel product from heterogeneous waste streams (biogenic and plastic materials), combining different waste types into a unified fuel source that eliminates the need for expensive polymer separation while achieving high recycling rates
3Ease of operation
If low density feedstock is processed, then material handling is simplified, but bridging and conveying issues increase due to low feedstock density
Solution Approach 1:
The patent applies preliminary action by shredding and pre-processing the low-density waste feedstock into smaller, more uniform particles before torrefiction, which prevents bridging and conveying issues during processing while maintaining the advantages of handling low-density material
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 torrefaction process enhances waste processing efficiency, reduces operational costs, and produces a solid fuel that can be used in boilers and kilns, while also allowing for the upgrading of torrefied materials into transportation fuels and chemicals, addressing the limitations of existing waste management methods.
Implementation Method 1
Torrefaction is a process of heating the feedstock at temperatures usually ranging from 280 to 500° C. either in the absence of oxygen or in an oxygen-starved environment. Torrefaction converts the waste feedstock mainly into a solid fraction.
Implementation Method 2
a heating and compaction unit comprising an auger and a heating portion configured to compact and heat the third reduced size material
Data Source
AI summary
A system for torrefaction of waste material comprising biogenic material and plastic material may comprise a material pre-processing system, a heating and compaction unit, a reactor system comprising a reaction portion and an extrusion portion, and a cutting unit adjacent an outlet of the reactor system. A method for operating a system for torrefaction of waste material comprising biogenic and plastic material may comprise processing the waste material to generate waste material having an aspect ratio between 0.8:1 and 1.2:1 and a largest dimension of less than 4 millimeters (mm); compressing and heating the pre-processed waste material in the heating and compaction unit; heating the compacted waste material in the reactor system to a temperature of 280° C.-500° C.; extruding material from the reactor system; and cutting the extruded material into pellets.