(478h) Ammonia-Assisted CO2 Capture and Conversion: A Process Design and Modeling Approach for CO2 Utilization in Steelmaking

In response to the imperative of achieving carbon neutrality, the steelmaking industry has intensified its focus on CO2 capture and utilization technologies. This study explores the integration of ammonia-based CO2 capture and conversion within coke oven operations, leveraging attached carbon and CO2 reactions. Through comprehensive process modeling and economic evaluation, we assess the feasibility of commercial-scale implementation. Our findings indicate that this integrated approach not only enhances energy efficiency but also holds promise as a sustainable solution for CO2 utilization in the steel industry.

Introduction: The release of carbon dioxide (CO₂), a greenhouse gas in to the atmosphere is inevitable in high industrialized economy, because a major source of CO₂ comes from the combustion of fossil fuels in the steelmaking plant. To utilize CO₂ in the steel plant, CO₂ is converted into carbon monoxide (CO) by reacting attached carbon inside the coke oven. [1] (Fig 1.) The produced CO gas is transported to a power plant and recycled as fuel. A capture process is required to inject high purity CO₂ into the coke oven and convert it to CO. The POSCO Holdings completed the development of a coke oven CO₂ injection and CO conversion process with a scale of 1,875 Nm3/hr. It developed a 10-ton-per-day CO₂ capture process using ammonia water, which is inexpensive and has low renewable energy, instead of expensive amine-based absorbents. [2] (Fig 2.)

Methodology: This study employed the selective capture of CO2 from the 85,000 Nm3/hr Blast Furnace Gas (BFG) emitted from blast furnaces using ammonia water, followed by supplying the rich CO2 gas from the capture process to coke ovens (Fig. 3). Through the utilization of demo-scale operating data of the coke oven CO2 injection process and ammonia-based CO2 chemical adsorption process, a scale-up design plan and economic feasibility were evaluated using ASPEN process modeling and simulation. The reactions outlined in Table 1 were incorporated throughout the entire process, including all streams and unit operations.

Conclusion: The conversion of captured CO2 into CO not only increases the gas heating value from coke ovens but also facilitates savings in fossil fuel consumption. Simulation-based economic evaluation suggests that ammonia-based CO2 capture and CO conversion technology within coke ovens demonstrate energy efficiency and hold promise for CO2 utilization within the steelmaking industry.

Acknowledgments

This work was supported by the *The demonstration of CO₂ injection/conversion technology using Coke Ovenof the Korea Institute of Energy Technology Evaluation and Planning(KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20214810100010)

References

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