Rotary Drum Torrefaction with Internal Fluid Conduit
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Solution Overview
Problem
Current torrefaction technologies are inadequate for efficiently processing biomass, as they lack effective methods for promoting the movement and heat transfer within the torrefaction process, leading to suboptimal energy content in the torrefied biomass and inefficient utilization of off-gas as an energy source.
Innovation Solution
A rotary drum system with a sealed inlet and outlet, a pitched rotation axis, and a fluid conduit along its inner surface to carry heated thermal fluid, which promotes the movement of biomass and ensures continuous heat supply, enhancing the torrefaction process and product discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rotary drum system with internal flights is used to promote biomass movement, then the heat transfer efficiency and torrefaction uniformity are improved, but the device complexity increases due to the need for sealed ports and rotating fluid conduits
Solution Approach 1:
The patent employs a rotary drum configuration where the drum rotates to continuously move biomass through the torrefaction zone. The rotation creates dynamic mixing and exposure of biomass to heated fluid, ensuring uniform torrefaction while maintaining continuous processing. The pitched axis enhances this dynamic movement by promoting gravity-driven progression of material through the drum.
Solution Approach 2:
The patent introduces a rotating fluid conduit as an intermediary component that carries heated fluid through the rotating drum while maintaining fluid-tight seals at the ports. This intermediary structure enables heat transfer to the moving biomass without compromising the sealed environment, thus achieving uniform torrefaction while managing the complexity of rotating seals.
2Productivity
If the drum axis is pitched to promote material movement under gravity, then the productivity and continuous discharge are improved, but the loss of thermal energy increases due to potential heat leaks at sealed ports
Solution Approach 1:
The pitched drum axis enables continuous movement of biomass through the torrefaction zone without interruption, maintaining constant productivity. The rotation ensures that material continuously progresses from the feed port through the heating zone to the discharge port, eliminating idle time and ensuring steady-state operation.
Solution Approach 2:
The rotating fluid conduit acts as an intermediary that maintains fluid-tight seals at the drum ports while allowing continuous rotation. This intermediary structure prevents thermal energy loss through the sealed ports, ensuring that the pitched configuration for continuous processing does not compromise thermal efficiency.
3Use of energy by moving object
If a fluid-carrying conduit is disposed along the inner surface of the drum to carry heated thermal fluid, then the heat supply efficiency is improved, but the device complexity increases due to the rotating seal requirements
Solution Approach 1:
The fluid-carrying conduit is nested along the inner surface of the rotating drum, following the drum's curvature. This nested configuration allows the conduit to rotate with the drum while maintaining close proximity to the biomass for efficient heat transfer. The conduit is positioned to maximize thermal contact with the moving material without interfering with the drum's rotation.
Solution Approach 2:
The rotating fluid conduit serves as an intermediary heat transfer medium that moves with the drum rotation. It carries heated thermal fluid along the inner drum surface, providing direct and efficient heat supply to the biomass as it passes by. The conduit's rotation with the drum ensures continuous heat transfer without requiring external moving parts or complex sealing mechanisms at multiple points.
4Productivity
If multiple discharge ports are provided on the drum shell for product removal, then the productivity is improved by continuous discharge, but the reliability decreases due to potential loss of sealed environment and thermal energy
Solution Approach 1:
The discharge ports are configured to enable continuous removal of torrefied biomass from the rotating drum. As the drum rotates, material is discharged through the ports in a continuous stream, maintaining steady productivity without interruption. The ports are positioned and sized to ensure smooth material flow while maintaining the sealed environment during rotation.
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 system achieves improved energy content in torrefied biomass and efficient utilization of off-gas as an energy source, allowing for a higher calorific value comparable to coal, while accommodating a wide range of biomass feedstocks and moisture contents.
Implementation Method 1
the rotation axis is pitched to promote movement of the contents through the length of the drum under the force of gravity
Implementation Method 2
The fluid conduit, heated by a thermal fluid carried within, provides heat to produce a continuous supply of torrefied biomass in the drum
Implementation Method 3
Torrefiction is a thermo-chemical treatment of biomass in the range of approximate 422-588.7 K (300-600 degrees Fahrenheit)... Torrefiction entails partially decomposing the biomass to form two components - a torrefied biomass (a solid) and off-gas
Data Source
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AI summary
A device includes a rotary drum and a fluid conduit. The rotary drum has a horizontal rotation axis and the drum has a sealed inlet end and a sealed outlet end. The drum is configured to receive biomass proximate the inlet end and has a discharge port proximate an outlet end. The fluid conduit is disposed along an inner surface of the drum. The fluid conduit is configured to carry heated fluid and has a coupling external to the drum.