Electric Arc Furnace Hydrogen Injection Using Recovered Mill Gas
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Solution Overview
Problem
Existing electric arc furnaces in steel mills face inefficiencies in using carbon as a reducing agent, leading to high carbon dioxide emissions and inefficient use of space and energy, while hydrogen production and storage are costly and require extensive infrastructure.
Innovation Solution
Capture metallurgical gases from steel mill facilities to produce hydrogen through a water-gas shift reaction, and inject the hydrogen into the electric arc furnace as a reducing agent to replace carbon, reducing carbon dioxide emissions and optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If carbon is used as a reducing agent in electric arc furnaces, then the reduction process can be maintained, but carbon dioxide emissions increase significantly
Solution Approach 1:
The patent changes the chemical parameter of the reducing agent from carbon-based (coke, coal) to hydrogen-based. By injecting hydrogen gas into the electric arc furnace, the reduction reaction changes from C + FeO → CO + Fe to H2 + FeO → H2O + Fe, eliminating CO2 emissions while maintaining iron reduction efficiency. The hydrogen is produced on-site from water electrolysis or steam reforming, and its injection rate is controlled to optimize the reduction process.
Solution Approach 2:
The patent substitutes the traditional carbon-based reduction mechanism with a hydrogen-based reduction mechanism. Instead of using solid carbon (coke) that requires high-temperature combustion and produces CO2, the system uses gaseous hydrogen that reacts more efficiently and produces only water vapor. This substitution is enabled by installing hydrogen injection devices (lances, nozzles) that deliver hydrogen directly to the reaction zone.
2Reliability
If hydrogen production facilities are completely separated from high-temperature areas, then safety is improved, but space and energy utilization become inefficient
Solution Approach 1:
The patent merges the hydrogen production facility with the electric arc furnace operation by locating the electrolyzer or reformer in close proximity to the furnace. The hot metallurgical gases from the furnace are directly fed to the hydrogen production unit, creating a synergistic arrangement where waste heat drives hydrogen production. This integration eliminates the need for complete separation while maintaining safety through proper engineering controls.
Solution Approach 2:
The patent uses hot metallurgical gases as an intermediary medium to transfer energy from the high-temperature furnace area to the hydrogen production facility. These gases, which would otherwise be waste heat, serve as the heating medium for water electrolysis or steam reforming, efficiently coupling the two processes while allowing physical separation of equipment.
3Ease of manufacture
If steam reforming of natural gas is used for hydrogen production, then hydrogen can be produced economically, but fossil fuel dependency and CO2 emissions increase
Solution Approach 1:
The patent changes the feedstock parameter for hydrogen production from fossil fuels (natural gas) to alternative sources such as water (electrolysis) or biomass. By using water electrolysis, the reaction H2O → H2 + 1/2O2 produces hydrogen without any carbon emissions. Alternatively, biomass gasification or alcohol reforming can be used, changing the chemical composition of the feedstock to eliminate fossil carbon.
Solution Approach 2:
The patent converts the previously harmful waste heat from electric arc furnaces into a useful resource for hydrogen production. The hot gases that were previously discarded are now used to drive the endothermic reactions of steam reforming or electrolysis, turning a waste product into the driving force for clean hydrogen generation.
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
Significantly reduces carbon dioxide emissions and enhances energy efficiency by using hydrogen as a reducing agent in electric arc furnaces, allowing for sustainable and economical steel production.
Implementation Method 1
transforming the carbon monoxide and the water comprised in said metallurgical gas into hydrogen and carbon dioxide according to a water-gas shift reaction
Implementation Method 2
a highly concentrated heat, released from the electric arc formed between the electrodes and the molten material
Implementation Method 3
exploiting a heating principle based on the Joule effect from the electrical current developed by the electrodes inside a slag with high electrical resistance
Data Source
AI summary
The disclosure discloses a method of operating an electric arc furnace, the method comprising capturing, from at least one facility of a steel mill, a heated metallurgical gas comprising water and carbon monoxide; conducting, by a reactor supply line, said metallurgical gas to a reactor; transforming, by a treatment of said metallurgical gas within said reactor, the carbon monoxide and water into hydrogen and carbon dioxide according to a water-gas shift reaction; and subsequently separating said hydrogen by a separation device. The method is characterized in that it further comprises providing an iron-bearing material, which comprises iron mainly in the form of iron oxide, to the electric arc furnace; at least partially melting the iron-bearing material to obtain a molten bath; conducting, by a furnace supply line, said hydrogen to the electric arc furnace, which is arranged downstream of the furnace supply line; and injecting, by a plurality of hydrogen injection devices, said hydrogen into said electric arc furnace, such that said hydrogen reacts as a reducing agent for reducing iron oxide in the molten bath during a smelting operation of the electric arc furnace.