Induction Heating of DRI for Uniform HBI Briquetting
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Solution Overview
Problem
Conventional direct reduced iron (DRI) production processes face challenges in achieving uniform temperature control and material properties due to temperature imbalances and inefficiencies in the briquetting process, leading to issues such as fine particles, chips, and non-uniform briquette quality, which are exacerbated by the use of hydrogen and natural gas combinations.
Innovation Solution
The implementation of induction heating in the feed channels to adjust the temperature of DRI and recycled fines before briquetting, allowing independent control of the material temperature and ensuring uniformity, thereby decoupling the reactor temperature from the briquetting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural gas is injected below the reduction zone to cool the material and add carbon, then the material temperature decreases and carbon content increases, but the temperature becomes too low for proper briquetting and the process complexity increases
Solution Approach 1:
The process is divided into separate functional zones: the reduction zone for carbon addition and the induction heating zone for temperature control. This segmentation allows independent optimization of carbon content and temperature, resolving the contradiction between adding carbon (which cools material) and maintaining briquetting temperature.
Solution Approach 2:
Induction heating serves as an intermediary mechanism between the reduction zone and briquetting press. It compensates for the cooling effect of natural gas injection by providing external heat, thereby maintaining the required temperature for briquetting while allowing adequate carbon content to be added.
2Temperature
If oxygen is injected to increase the bed temperature, then the temperature increases, but the temperature control becomes difficult and clustering of material occurs
Solution Approach 1:
The mechanical/chemical heating method (oxygen injection) is replaced with induction heating, an electromagnetic field-based method. Induction heating provides precise, controllable, and uniform heating without the risk of localized overheating or material clustering, thereby improving temperature control stability.
3Temperature
If the reactor temperature is increased to raise the feed material temperature, then the material temperature increases, but the energy consumption increases and the reduction process efficiency decreases
Solution Approach 1:
The temperature control function is extracted from the reduction reactor and placed in a separate induction heating system. This allows the reactor to operate at optimal reduction temperatures while the induction heating system independently adjusts the feed material temperature, avoiding unnecessary energy consumption in the reduction zone.
4Temperature
If complex flow sheet with hydrogen separation via PSA or VSA is used to limit temperature drop, then the temperature control improves, but the device complexity and cost increase significantly
Solution Approach 1:
Instead of investing in expensive and complex hydrogen separation equipment (PSA/VSA units), the patent uses a simpler, more economical induction heating system to achieve temperature control. The induction heating approach is less complex and more cost-effective while achieving the same temperature stability goal.
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 enhances briquette density and strength, reduces the occurrence of chips and fines, enables the use of lower-grade ores, and allows for additional carbon addition, resulting in improved product quality and cost savings.
Implementation Method 1
heating the direct reduced iron material in a feed channel to a target temperature with an induction heating device
Data Source
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AI summary
1. The Invention pertains to a Process for the manufacturing of hot briquetted iron (HBI) from direct reduced iron (DRI) wherein iron ore is direct reduced in a reactor by a reducing gas consisting of natural gas and/or hydrogen and/or carbon monoxide under elevated temperatures and discharging the direct reduced iron to at least one briquetting device where briquettes are pressed from the direct reduced iron characterized in that the direct reduced iron is after leaving the reactor and before briquetting is heated to a target briquetting temperature.