Post-combustion capture of CO₂ at an integrated steel mill: Part I: Technical concept analysis

In this study different possibilities for applying post-combustion capture at an integrated steel mill in order to reduce carbon dioxide emissions were studied. Implications of different amounts of CO₂ captured, different solvents for post-combustion capture and different heat supply options for solvent regeneration to the energy balance and greenhouse gas emissions of the steel mill are compared to that of the base case for the steel mill. The case study is based on Ruukki Metals Ltd.'s Raahe steel mill that is situated on the coast of the Gulf of Bothnia. It is the largest integrated steel mill in the Nordic countries producing hot rolled steel plates and coils. It is also the largest CO₂ point source in Finland emitting approximately 4Mt/year. Carbon capture processes were modelled using Aspen Plus process modelling software and results were used to estimate the potential for reducing CO₂ emissions at an integrated steel mill from a plant operator's point of view. Different heat integration options and heat utilization scenarios were investigated. The heat available for solvent regeneration varied between these heat utilization scenarios and thus partial capture of CO₂ was investigated with the CO₂ amount captured depending on the heat available for solvent regeneration in the different case studies. The results of the study show a significant CO₂ reduction potential using CCS. Approximately 50-75% of the emissions from the site could be captured using post-combustion capture. Capturing a larger amount of emissions would be technically less feasible due to the large number of small stacks around the large, integrated steel mill site.