Multi-Story Furnace Cooling Zone for Torrefied Material
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Solution Overview
Problem
Existing thermal treatment processes for carbon-containing material flows, particularly in multiple-hearth furnaces, face challenges in achieving rapid and effective cooling while preventing self-ignition and smoldering hotspots, due to the mixing of exhaust gases during the cooling phase.
Innovation Solution
A multi-level furnace design with separate upper and lower process spaces for heat treatment and cooling, respectively, where the cooling zone uses a liquid coolant like water to create an inert atmosphere and features rabble arms for even distribution, ensuring efficient cooling and preventing self-ignition, with additional cooling gas supply and a separate cooling device for further cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling gas is fed to the bottom deck and flows through decks above in countercurrent to the material, then cooling of the torrefied material is achieved, but exhaust gases from different zones mix and create safety risks including self-ignition and smoldering hotspots
Solution Approach 1:
The furnace is divided into gas-tight separated zones (drying zone, torrefaction zone, cooling zone) with independent atmospheric control. Each zone has its own gas supply and exhaust system, preventing mixing of hot torrefaction gases with cooling zone gases, thereby eliminating the risk of self-ignition while maintaining effective cooling
Solution Approach 2:
The cooling zone is supplied with inert gas (nitrogen or carbon dioxide) to create an oxygen-deficient atmosphere that prevents combustion. This inert atmosphere ensures that even if hot torrefied material is present, self-ignition and smoldering cannot occur, while cooling effectiveness is maintained through controlled gas flow
2Temperature
If water is supplied to cool the torrefied material, then rapid cooling and inert atmosphere creation are achieved, but water distribution uniformity must be ensured to prevent localized overheating
Solution Approach 1:
A water distribution system with nozzles connected to the rotating shaft is employed to spray water uniformly across the torrefied material on each deck. The hydraulic system ensures consistent water flow rate and distribution pattern, achieving rapid cooling without localized overheating or water deficiency zones
Solution Approach 2:
Water is pre-distributed through the rotating shaft nozzles before the material completes its traversal across the cooling deck. This preliminary cooling action ensures that the entire material surface is exposed to cooling water early in the cooling process, preventing localized overheating and ensuring uniform temperature reduction
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 approach enables rapid and effective cooling of torrefied materials, preventing self-ignition and smoldering hotspots, while maintaining product quality and reducing cooling costs through efficient evaporation of the coolant and strategic use of inert and ambient air.
Implementation Method 1
an extremely effective cooling effect is achieved by the evaporation of the coolant applied to the material flow in the cooling zone
Implementation Method 2
an extremely effective cooling effect is achieved by the evaporation of the coolant applied to the material flow
Implementation Method 3
a cooling gas is fed to the bottom deck, which is then fed to the decks above flows through it in countercurrent to the material
Data Source
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AI summary
The system according to the invention for the thermal treatment of a material flow, preferably a material flow containing carbon, comprises a multiple-story furnace having at least one upper and one lower process chamber, which are isolated from each other in regard to gas flow and which each comprise at least two stories arranged one above the other, wherein the at least one upper process chamber is designed for the heat treatment of the material flow at elevated temperatures and the lower process chamber is designed as a cooling zone, wherein the cooling zone has means for feeding liquid coolants, e.g., an injection of water, for cooling and creating an inert atmosphere.