Solid Fuel Composition from Mixed Waste via Vacuum Drying and Plastic Melting
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Solution Overview
Problem
Current Waste-to-Energy processes face inefficiencies when using municipal solid waste or agricultural waste due to high water content, low density, and variability in composition, limiting the effective operation of pyrolysis or gasification chambers, and require significant investment in specialized equipment.
Innovation Solution
A method to produce a solid fuel composition from mixed solid waste by heating a mixture with at least 5% plastics to separate moisture and volatile compounds, melting plastics to distribute them throughout the mixture, and extruding the mixture to create a dense, uniform, low-moisture fuel suitable for pyrolysis or gasification without forming syngas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pyrolysis or gasification is used to process municipal solid waste, then energy can be liberated from the waste stream, but the process is limited by high water content, low density, and variable composition of the waste
Solution Approach 1:
The patent applies preliminary action by pre-drying the municipal solid waste to reduce moisture content to below 10% before pyrolysis or gasification. This preliminary drying step prepares the waste to meet the density and moisture requirements for efficient thermal processing, thereby resolving the contradiction between energy liberation and process reliability.
Solution Approach 2:
The patent changes physical parameters of the waste by compressing it to achieve a density of at least 30 lb/ft³ and reducing moisture content to below 10%. These parameter changes transform the waste into a form suitable for reliable pyrolysis or gasification, resolving the efficiency limitations caused by the waste's initial poor physical properties.
2Stability of the object's composition
If pelletizers are used to uniform the size of solid waste, then the waste becomes more uniform in size, but the waste still retains variation in composition and fails to achieve high density and low moisture
Solution Approach 1:
The patent applies preliminary drying to reduce moisture content to below 10% before size reduction and mixing. This preliminary moisture removal ensures that subsequent processing steps work with material that has already achieved the low moisture content required for high-density fuel, thereby achieving both size uniformity and composition consistency.
Solution Approach 2:
The patent creates a composite fuel product by mixing pre-dried municipal solid waste with binder materials. This composite approach allows the final fuel to achieve consistent composition and high density (at least 30 lb/ft³) by combining materials with complementary properties, resolving the limitation of pelletizing alone.
3Productivity
If advanced gasification mechanisms are used to overcome feedstock inconsistency, then pyrolysis efficiency improves, but significant investment in specialized equipment is required
Solution Approach 1:
The patent applies preliminary action by pre-drying waste to below 10% moisture and pre-compressing to at least 30 lb/ft³ density before pyrolysis. This preparation ensures that conventional pyrolysis equipment can process the waste efficiently without requiring advanced gasification mechanisms, thereby achieving high productivity without increased device complexity.
Solution Approach 2:
The patent changes the physical parameters of the waste (moisture content to below 10%, density to at least 30 lb/ft³) to make it suitable for efficient processing in conventional pyrolysis equipment. This parameter modification eliminates the need for expensive specialized equipment while maintaining high pyrolysis efficiency.
4Use of energy by moving object
If solid waste is incinerated to liberate energy, then the energy of the solid waste stream is released, but the process does not provide the efficiency of pyrolysis or gasification
Solution Approach 1:
The patent applies preliminary drying to reduce moisture content to below 10% before energy conversion. This preliminary action removes excess water that would otherwise consume energy during incineration without contributing to energy release, thereby enabling more efficient energy liberation through subsequent pyrolysis or gasification.
Solution Approach 2:
The patent changes the moisture content parameter to below 10% and density to at least 30 lb/ft³, transforming the waste into a form that enables efficient pyrolysis or gasification. These parameter changes allow the system to capture more energy from the waste stream while minimizing energy losses associated with water evaporation and incomplete combustion.
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 transforms variable solid waste into a high-density, low-moisture, energy-rich fuel that can efficiently operate pyrolysis or gasification methods without additional capital investment, reducing emissions and enabling prolonged storage and transportation without biodegradation.
Implementation Method 1
heating a solid waste mixture that includes at least 5% wt. mixed plastics within a process vessel to a temperature no greater than 110° C. to separate the solid waste mixture into a dried solid waste mixture and vaporized compounds
Implementation Method 2
removing the vaporized compounds from the process vessel by reducing the pressure within the process vessel to less than about 50 torr using a vacuum system
Implementation Method 3
heating and mixing the dried solid waste mixture to a maximum temperature of at least 160° C. to form a heated solid waste mixture comprising melted plastics
Implementation Method 4
extruding the heated solid waste mixture from the process vessel to create a dense, uniform, low-moisture fuel
Data Source
AI summary
Systems and methods of producing a solid fuel composition are disclosed. In particular, systems and methods for producing a solid fuel composition by heating and mixing a solid waste mixture below atmospheric pressure to a maximum temperature sufficient to melt the mixed plastics within the solid waste mixture is disclosed.