Biomass Direct Reduced Iron Batch Oven
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Solution Overview
Problem
Current methods for producing direct reduced iron (DRI) from iron ore, such as using hydrogen and blast furnaces, face challenges like high electricity demand, hydrogen storage issues, and inefficiency with high-gangue ore types, while integrating biomass into existing coal-based processes is inefficient due to the different nature of biomass.
Innovation Solution
A process and apparatus using multiple static batch ovens to heat and reduce iron ore-biomass briquettes at 700-1100°C for 10-100 hours, achieving 80-99% metallization with low energy importation by utilizing biomass energy efficiently and sharing fuel gas between ovens to optimize thermal efficiency and reduce operating costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If hydrogen is used to produce DRI in a blast furnace alternative process, then CO2 emissions are reduced, but electricity demand increases significantly (3000-4000 kWh/t) and hydrogen storage becomes a technical challenge
Solution Approach 1:
The biomass provides its own energy for the reduction process through combustion, eliminating the need for external electricity input. The system is self-sufficient by using the fuel (biomass) to generate the heat required for its own processing, thereby avoiding high electricity demands while maintaining low CO2 emissions
Solution Approach 2:
The invention changes the energy input parameter from electrical energy (high demand) to chemical energy from biomass combustion (self-sufficient). This parameter change transforms the energy source and delivery mechanism, allowing DRI production without requiring 3000-4000 kWh/t of electricity
2Adaptability or versatility
If biomass is inserted into existing coal-based processes like blast furnaces, then renewable energy utilization increases, but process efficiency decreases due to the different nature of biomass compared to coal
Solution Approach 1:
Instead of forcing biomass into coal-based processes (the conventional approach), the invention inverts the approach by designing a dedicated biomass-based direct reduction process. The process is specifically tailored to biomass characteristics, using biomass combustion to generate heat and biomass-derived reducing gases for reduction, thereby achieving both renewable energy utilization and high process efficiency
Solution Approach 2:
The invention changes the fundamental process parameters from coal-based high-temperature blast furnace conditions to biomass-based controlled atmosphere direct reduction conditions. This includes lower operating temperatures, different residence times, and biomass-specific combustion and reduction zones, optimizing the process for biomass rather than adapting biomass to coal processes
3Loss of energy
If extended heating times (10-100 hours) are used in batch ovens for ore-biomass reduction, then thermal efficiency and metallisation (80-99%) improve, but production cycle time increases
Solution Approach 1:
The extended batch cycle is segmented into distinct functional zones within the oven: a combustion zone where biomass burns to generate heat, a preheating zone where ore-biomass briquettes are heated, and a reduction zone where metallisation occurs. This spatial segmentation allows different processes to occur simultaneously in different parts of the system, maximizing thermal efficiency without indefinitely extending the overall cycle time
Solution Approach 2:
The batch oven process maintains continuous useful action through staggered batch cycling and heat recovery. While one batch is in the reduction phase, another batch can be prepared or heated, ensuring that the oven and associated equipment are continuously productive. Heat from combustion zones is continuously transferred to reduction zones, maintaining high thermal efficiency throughout the extended cycle
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 allows for extended heating times, higher thermal efficiency, and lower operating costs by capturing biomass energy effectively, producing high metallization DRI with reduced need for imported power, and can produce molten metal like pig iron or steel efficiently.
Implementation Method 1
heating a batch of iron ore and biomass in a batch oven in a temperature range of 700-1100° C.
Implementation Method 2
utilizing biomass energy efficiently
Implementation Method 3
reducing iron ore and forming a solid DRI product having a metallisation of 80-99%
Data Source
AI summary
A process and an apparatus for producing direct reduced iron (“DRI”) from iron ore and biomass are disclosed. The process includes heating a batch of iron ore and biomass in a batch oven (3) and reducing iron ore and forming a solid DRI product having a metallisation of 80-99% and generating an offgas. The process includes discharging the solid product at the end of the batch cycle and discharging offgas during the course of the batch cycle. The process operates the batch oven in a temperature range of 700-1100#C in a batch cycle time of 10-100 hours.