Multiple Hearth Furnace Pyrolysis to Reduce Micropore Blocking
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Solution Overview
Problem
Existing pyrolysis processes for producing recovered carbon black from rubber granulate are inefficient, leading to high residence times and undesirable properties due to the presence of impurities and micropore blocking during the pyrolysis process.
Innovation Solution
The use of a multiple hearth furnace (MHF) for pyrolyzing rubber granulate at temperatures between 360°C to 950°C in the absence of oxygen, with a configuration that includes multiple hearths, a rotating central shaft, and rabble arms to facilitate radial material transfer, resulting in a more efficient pyrolysis process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional pyrolysis processes are used to produce recovered carbon black from rubber granulate, then the process can proceed with simple equipment, but the residence time is high and the micropore blocking occurs leading to undesirable properties
Solution Approach 1:
The pyrolysis process is divided into multiple discrete heating zones (hearths) arranged vertically. Each hearth operates at a different temperature stage, allowing the rubber granulate to progress through sequential heating phases. This segmentation enables controlled thermal processing that reduces residence time while preventing micropore blocking by gradually decomposing the rubber matrix.
Solution Approach 2:
The multiple hearth furnace implements dynamic material transfer between hearths using rabble arms that actively move and redistribute the rubber granulate. This dynamic movement ensures uniform heating across all particles, prevents localized overheating that could cause micropore blocking, and optimizes the residence time distribution throughout the pyrolysis process.
2Productivity
If traditional pyrolysis processes are used, then the equipment configuration is simple, but the pyrolysis efficiency is low
Solution Approach 1:
The pyrolysis process transitions from a horizontal or single-chamber configuration to a vertical multi-level hearth structure. This dimensional change allows simultaneous processing of material at multiple temperature stages within a compact footprint, significantly improving pyrolysis efficiency while the modular hearth design keeps the equipment configuration manageable.
Solution Approach 2:
The multiple hearth furnace establishes continuous material flow through the pyrolysis process, with rubber granulate continuously fed from the top and progressively moved through heated hearths to the bottom. This continuous operation eliminates idle time between batches and maintains constant thermal processing, thereby improving productivity without requiring overly complex batch-to-batch transfer mechanisms.
3Temperature
If low temperature pyrolysis is used, then the equipment requirements are less stringent, but the pyrolysis process is inefficient and produces undesirable carbon black properties
Solution Approach 1:
Different hearths in the multiple hearth furnace are maintained at different temperature levels, creating a temperature gradient from top to bottom. The upper hearths operate at lower temperatures for initial decomposition, while lower hearths operate at higher temperatures for complete carbon black formation. This local quality variation allows efficient pyrolysis at elevated temperatures without requiring the entire system to operate at high temperature, thus maintaining equipment feasibility.
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 method reduces residence time and enhances the cumulative pore volume of the recovered carbon black, improving its microporosity and reducing micropore blocking, thereby enhancing its application in rubber matrices.
Implementation Method 1
pyrolysis of rubber granulate at a temperature of 360 °C to 950 °C and in the absence of oxygen
Data Source
Figure 1
AI summary
The present invention relates to a method for the pyrolysis of a rubber granulate, such as a tire rubber granulate, in a multiple hearth furnace.