DRI Shaft Hydrogen Separation for Lower-CO2 Ironmaking
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Solution Overview
Problem
Existing direct reduced iron (DRI) manufacturing methods emit significant CO2 and require substantial fossil fuel consumption, necessitating a more environmentally friendly and efficient production process.
Innovation Solution
A method utilizing hydrogen extracted from coke oven gas and biogas, combined with CO2-neutral electricity, to produce a reducing gas for DRI production, adjusting the carbon content of DRI to 0.5-3 wt.% through a DRI shaft's transition section, and incorporating a hydrogen separation unit and mixer to optimize gas usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional blast furnace method is used to produce pig iron, then high production volume is achieved, but CO2 emissions increase significantly due to coke consumption
Solution Approach 1:
The invention changes the chemical composition parameters of the reducing gas from conventional coke-based CO to a mixture containing H2, CO, and CH4 derived from biogas and coke oven gas. This parameter change enables direct reduction of iron ore at lower temperatures without requiring coke, thereby maintaining high productivity while eliminating the primary source of CO2 emissions associated with coke combustion and iron ore reduction
Solution Approach 2:
The invention converts harmful waste gases (coke oven gas containing CO2 and biogas containing CH4) into beneficial reducing agents. By utilizing these waste gases as feedstock for producing the reducing gas mixture, the process transforms potential environmental hazards into valuable resources that drive the reduction reaction, thereby reducing overall CO2 emissions while maintaining production efficiency
2Productivity
If traditional direct reduction method using syngas from natural gas reforming is used, then iron oxide reduction is efficient, but CO2 emissions remain high due to fossil fuel consumption
Solution Approach 1:
The invention converts biogas (a renewable resource containing CH4) and coke oven gas (a waste product containing CO2 and other gases) into the reducing gas mixture. This substitution of fossil fuel-based natural gas with renewable and waste gas sources maintains the efficiency of iron oxide reduction while eliminating the CO2 emissions associated with fossil fuel consumption, as the carbon in these gases originates from biomass or industrial waste rather than depleting fossil reserves
Solution Approach 2:
The invention changes the source and composition parameters of the reducing gas from conventional natural gas reforming to a mixture derived from biogas and coke oven gas. This includes adjusting the proportions of H2, CO, and CH4 in the reducing gas to optimize reduction efficiency while using renewable and waste gas sources, thereby maintaining high productivity without the CO2 emissions penalty of fossil fuel-based syngas production
3Object-generated harmful factors
If hydrogen is extracted from coke oven gas for reduction, then CO2 emissions are reduced, but the remaining coke oven gas must be disposed of or reinjected
Solution Approach 1:
The invention merges two gas streams that would otherwise require separate handling: the hydrogen-enriched stream extracted from coke oven gas and the remaining coke oven gas stream. By combining these streams and reinjecting them together into the direct reduction shaft, the system eliminates the need for complex separate disposal or utilization systems for the remaining gas, thereby reducing overall system complexity while maintaining CO2 emissions reduction benefits
Solution Approach 2:
The reinjected gas mixture serves multiple functions simultaneously: it acts as a reducing agent for iron oxide, provides thermal energy through combustion, and handles the waste coke oven gas that would otherwise require separate disposal. This multi-functionality eliminates the need for dedicated waste gas treatment systems, thereby reducing device complexity while achieving CO2 emissions reduction
4Quantity of substance
If transition zone natural gas injection is used for carburization, then carbon content of DRI is increased, but CO2 emissions increase due to additional fossil fuel consumption
Solution Approach 1:
The invention changes the source and composition parameters of the gas injected into the transition zone from conventional natural gas to coke oven gas. This substitution maintains the carburization function by providing carbon-containing gases (CO, CH4) that can react with metallized iron to form Fe3C, thereby increasing the carbon content of DRI to the desired range, while eliminating the CO2 emissions associated with fossil fuel-based natural gas consumption
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
Manufactures DRI with reduced CO2 emissions and improved yield, utilizing renewable energy sources and waste gases, while maintaining high quality and combustion potential.
Implementation Method 1
hydrogen obtained by extraction from coke oven gas through a hydrogen separation unit
Implementation Method 2
Oxygen contained in ores and pellets is removed in stepwise reduction of iron oxides in counter-current reaction between gases and oxide
Implementation Method 3
reducing gas is entering the furnace from the bottom of reduction zone and flows counter-current from the charged oxidised iron
Implementation Method 4
Injection of natural gas in the transition zone is using sensible heat of the metallized product in the transition zone to promote hydrocarbon cracking and carbon deposition
Implementation Method 5
In this section carburization of the metallized product happens. Carburization is the process of increasing the carbon content of the metallized product inside the reduction furnace
Implementation Method 6
Injection of natural gas in the transition zone is using sensible heat of the metallized product in the transition zone to promote hydrocarbon cracking and carbon deposition
Implementation Method 7
Iron oxide ores and pellets containing around 30% by weight of Oxygen are charged to the top of a direct reduction shaft and are allowed to descend, by gravity, through a reducing gas
Data Source
Figure 1
AI summary
A method for manufacturing Direct Reduced Iron wherein iron ore is reduced in a DRI shaft by a reducing gas comprising hydrogen obtained by extraction from coke oven gas through a hydrogen separation unit, the remaining part of such coke oven gas being at least partly injected in the transition section of said DRI shaft to set the carbon amount of said Direct Reduced Iron from 0.5 to 3 wt.% and a DRI manufacturing equipment including a DRI shaft (1) and a hydrogen separation unit (5), wherein said hydrogen separation unit (5) inlet is connected to a coke oven gas supply (6) and includes a first outlet connected to the DRI shaft to inject hydrogen separated from said coke oven gas and a second outlet connected to the transition section of said DRI shaft (1) to inject at least part of the remaining part of such coke oven gas.