Multi-shelf Furnace Thermal Oil Radiant Heating
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Solution Overview
Problem
Current multiple hearth furnaces for low-temperature biomass torrefaction are inefficient due to high thermal inertia, high capital and operating expenses, and environmental impact, making them poorly suited for low-temperature heat treatment processes below 350°C.
Innovation Solution
A modified multiple hearth furnace design featuring a mechanically-welded assembly, external insulation, flat metal soles, and thermal oil radiant tubes instead of fossil fuel burners, with a stainless steel construction to reduce refractory material and thermal inertia, and utilize pyrolysis gases as a fuel source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional multi-hearth furnaces with refractory material and fossil fuel burners are used, then high temperature processing capability is achieved, but thermal inertia increases and operating costs rise
Solution Approach 1:
The patent changes the material parameters of the hearths from refractory bricks to metallic materials (stainless steel or aluminum), fundamentally altering the thermal properties. This substitution reduces thermal inertia while maintaining the ability to reach processing temperatures, directly resolving the contradiction between temperature capability and energy consumption.
Solution Approach 2:
The patent employs replaceable metallic hearth panels that can be quickly changed and regenerated externally. Instead of using expensive, long-lived refractory materials that require complex replacement procedures, the system uses simpler, cheaper metallic panels that can be rapidly swapped, reducing both initial investment and operational costs.
2Temperature
If refractory material is used in multi-hearth furnaces, then high temperature resistance is achieved, but capital expenses and device complexity increase
Solution Approach 1:
The patent transforms the hearth material from refractory bricks to metallic panels, changing the fundamental material parameter. This substitution enables standard manufacturing techniques and reduces material costs while maintaining sufficient temperature resistance for the application, directly addressing the capital expense issue.
Solution Approach 2:
The hearth structure is divided into separate, modular metallic panels that can be independently manufactured and assembled. This segmentation allows for simplified production, easier maintenance, and reduced overall system complexity compared to traditional monolithic refractory constructions.
3Temperature
If fossil fuel burners are used for heating, then high temperature is achieved, but environmental impact and operating expenses increase
Solution Approach 1:
The patent implements a self-service heating system where the furnace uses its own processed material as fuel. The combustor burns a portion of the dried biomass to generate heat, eliminating the need for external fossil fuel sources and reducing environmental impact while maintaining operating temperature.
Solution Approach 2:
The system converts what would be waste material (excess dried biomass) into a useful fuel source for heating. This transforms a potential disposal problem into an energy source, eliminating harmful fossil fuel emissions while providing the necessary heat for processing.
4Strength
If traditional hearth designs are used, then structural strength is achieved, but maintenance difficulty and operating complexity increase
Solution Approach 1:
The hearth is constructed from modular metallic panels that can be independently removed and replaced. This segmentation allows for easy maintenance and repair without requiring complex disassembly procedures, directly improving ease of repair while maintaining structural integrity through proper panel design and assembly.
Solution Approach 2:
The patent employs simple, replaceable metallic hearth panels instead of complex, long-lived refractory structures. These panels are designed to be economically replaceable and easy to maintain, reducing operating complexity and maintenance difficulty while providing sufficient structural strength for the application.
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
This design reduces capital and operating expenses by 40-50%, minimizes environmental impact, and maintains operational efficiency with reduced thermal inertia, while allowing for easier maintenance and energy efficiency through the use of stainless steel and thermal oil heating.
Implementation Method 1
a heating device for the material to be heat-treated... the heating device comprises a radiant heat exchanger in the form of a flat heat exchange structure having thermal fluid channels
Implementation Method 2
a radiant heat exchanger in the form of a flat heat exchange structure having thermal fluid channels, attached to the face of each hearth
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The invention relates to a multi-shelf furnace (1) for heat treatment at a temperature not exceeding 350°C, characterized in that the shelves (2) are made up of flat discs fixed to the outer shell (3), in that the stirring arms (5) are fixed to all-welded modules (14) constituting the central shaft (4), in that the stirring tines (15) are welded to their respective stirring arm (5), all these elements being made from metal sheet or plate, and in that the heating device comprises a heat-transfer-fluid radiant heat exchanger (17, 27) which is secured to the face of each shelf (2) not in contact with the substance to be treated.