Application of the DMXTM CO2 Capture Process in Steel Industry

Pilot scale assessment of a novel phase-change solvent for energy efficient post -combustion CO2 capture

The proliferation of industrial-scale CO₂ capture technologies requires improvements in existing systems. Absorption/desorption capture processes that employ phase-change solvents (PCS) are promising for energy and cost reduction. Several PCSs have been investigated at bench scale, but very few have been tested in pilot-scale plants. The novel PCS mixture S₁N (N1- cyclohexylpropane-1,3-diamine)/DMCA (Dimethylcyclohexylamine) has previously exhibited desirable performance in equilibrium experiments, economic and sustainability studies. This work presents the pilot-scale evaluation of S₁N/DMCA for the first time, at two different concentrations and various liquid-to-gas ratios. Experimental evidence on key performance indicators is brought forward, including absorption efficiency, cyclic capacity, distance from equilibrium and regeneration energy in comparison to benchmark solvent MEA (monoethanolamine). S₁N/DMCA enables robust operation as it maintains a cyclic capacity of 0.63 mol/kg at different liquid-to-gas ratios, which is about two times higher than that of MEA. It achieves operating loadings close to equilibrium, reaching 1.6 mol/kg, and a regeneration energy of 2.3 GJ/tn CO₂, representing 45% reduction compared to MEA.

Carbon capture for decarbonisation of energy-intensive industries: a comparative review of techno-economic feasibility of solid looping cycles

Carbon capture and storage will play a crucial role in industrial decarbonisation. However, the current literature presents a large variability in the techno-economic feasibility of CO2 capture technologies. Consequently, reliable pathways for carbon capture deployment in energy-intensive industries are still missing. This work provides a comprehensive review of the state-of-the-art CO2 capture technologies for decarbonisation of the iron and steel, cement, petroleum refining, and pulp and paper industries. Amine scrubbing was shown to be the least feasible option, resulting in the average avoided CO2 cost of between $$62.7\;\mathrm{C}\!\!\!\!{\scriptstyle{{}^=}\,} \cdot {\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ for the pulp and paper and $$104.6\;\mathrm{C}\!\!\!\!{\scriptstyle{{}^=}\,} \cdot {\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ for the iron and steel industry. Its average equivalent energy requirement varied between 2.7 (iron and steel) and $$5.1\;\;{\rm{M}}{{\rm{J}}_{{\rm{th}}}} \cdot {\rm{kg}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ (cement). Retrofits of emerging calcium looping were shown to improve the overall viability of CO2 capture for industrial decarbonisation. Calcium looping was shown to result in the average avoided CO2 cost of between 32.7 (iron and steel) and $$42.9\;\mathrm{C}\!\!\!\!{\scriptstyle{{}^=}\,} \cdot {\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ (cement). Its average equivalent energy requirement varied between 2.0 (iron and steel) and $$3.7\;\;{\rm{M}}{{\rm{J}}_{{\rm{th}}}} \cdot {\rm{kg}}_{{\rm{C}}{{\rm{O}}_2}}^{\;\;\;\;\;\;\;\; - 1}$$ (pulp and paper). Such performance demonstrated the superiority of calcium looping for industrial decarbonisation. Further work should focus on standardising the techno-economic assessment of technologies for industrial decarbonisation.

Carbon Allocation in Multi-Product Steel Mills That Co‐process Biogenic and Fossil Feedstocks and Adopt Carbon Capture Utilization and Storage Technologies

This work investigates the effects of carbon allocation on the emission intensities of low-carbon products cogenerated in facilities that co‐process biogenic and fossil feedstocks and apply the carbon capture utilization and storage technology. Thus, these plants simultaneously sequester CO2 and synthesize fuels or chemicals. We consider an integrated steel mill that injects biomass into the blast furnace, captures CO2 for storage, and ferments CO into ethanol from the blast furnace gas. We examine two schemes to allocate the CO2 emissions avoided [due to the renewable feedstock share (biomass) and CO2 capture and storage (CCS)] to the products of steel, ethanol, and electricity (generated through the combustion of steel mill waste gases): 1) allocation by (carbon) mass, which represents actual carbon flows, and 2) a free-choice attribution that maximizes the renewable content allocated to electricity and ethanol. With respect to the chosen assumptions on process performance and heat integration, we find that allocation by mass favors steel and is unlikely to yield an ethanol product that fulfills the Renewable Energy Directive (RED) biofuel criterion (65% emission reduction relative to a fossil comparator), even when using renewable electricity and applying CCS to the blast furnace gas prior to CO conversion into ethanol and electricity. In contrast, attribution fulfills the criterion and yields bioethanol for electricity grid intensities <180 gCO2/kWhel without CCS and yields bioethanol for grid intensities up to 800 gCO2/kWhel with CCS. The overall emissions savings are up to 27 and 47% in the near-term and long-term future, respectively. The choice of the allocation scheme greatly affects the emissions intensities of cogenerated products. Thus, the set of valid allocation schemes determines the extent of flexibility that manufacturers have in producing low-carbon products, which is relevant for industries whose product target sectors that value emissions differently. We recommend that policymakers consider the emerging relevance of co‐processing in nonrefining facilities. Provided there is no double-accounting of emissions, policies should contain a reasonable degree of freedom in the allocation of emissions savings to low-carbon products, so as to promote the sale of these savings, thereby making investments in mitigation technologies more attractive to stakeholders.

Renewable Hydrogen Production Processes for the Off-Gas Valorization in Integrated Steelworks through Hydrogen Intensified Methane and Methanol Syntheses

Within integrated steelmaking industries significant research efforts are devoted to the efficient use of resources and the reduction of CO2 emissions. Integrated steelworks consume a considerable quantity of raw materials and produce a high amount of by-products, such as off-gases, currently used for the internal production of heat, steam or electricity. These off-gases can be further valorized as feedstock for methane and methanol syntheses, but their hydrogen content is often inadequate to reach high conversions in synthesis processes. The addition of hydrogen is fundamental and a suitable hydrogen production process must be selected to obtain advantages in process economy and sustainability. This paper presents a comparative analysis of different hydrogen production processes from renewable energy, namely polymer electrolyte membrane electrolysis, solid oxide electrolyze cell electrolysis, and biomass gasification. Aspen Plus® V11-based models were developed, and simulations were conducted for sensitivity analyses to acquire useful information related to the process behavior. Advantages and disadvantages for each considered process were highlighted. In addition, the integration of the analyzed hydrogen production methods with methane and methanol syntheses is analyzed through further Aspen Plus®-based simulations. The pros and cons of the different hydrogen production options coupled with methane and methanol syntheses included in steelmaking industries are analyzed.

Utilization of Steel-Making Dust in Drilling Fluids Formulations

Steelmaking is an energy-intensive process that generates considerable amounts of by-products and wastes, which often pose major environmental and economic challenges to the steel-making industry. One of these by-products is steel dust that is produced during the separation of impurities in the smelting and refining of metals in steel-making furnaces. In this study, electric arc furnace (EAF) dust has been evaluated as a potential, low-cost additive to increase the viscosity and weight of drilling muds. Currently, the cost of drilling operations typically accounts for 50 to 80% of the exploration costs and about 30 to 80% of the subsequent field development costs. Utilization of steelmaking waste in drilling fluids formulations is aimed to produce new and optimized water-based drilling formulations, which is expected to reduce the amount of bentonite and other viscosifier additives used in the drilling formulations. The results showed that in a typical water-based drilling fluid of 8.6 ppg (1030.51 kg/m3), the amount of standard drilling grade bentonite could be reduced by 30 wt.% with the addition of the proposed new additive to complete the required mud weight. The mixture proved to be stable with no phase separation.

Kinetics, Thermodynamics, and Mechanism of a Novel Biphasic Solvent for CO2 Capture from Flue Gas

The main issue related to the deployment of the amine-based absorption process for CO₂ capture from flue gas is its intensive energy penalty. Therefore, this study screened a novel biphasic solvent, comprising a primary amine e.g., triethylenetetramine (TETA) and a tertiary amine e.g., N, N-dimethylcyclohexylamine (DMCA), to reduce the energy consumption. The TETA-DMCA blend exhibited high cyclic capacity of CO₂ absorption, favorable phase separation behavior, and low regeneration heat. Kinetic analysis showed that the gas- and liquid-side mass transfer resistances were comparable in the lean solution of TETA-DMCA at 40 °C, whereas the liquid-side mass transfer resistance became dominant in the rich solution. The rate of CO₂ absorption into TETA-DMCA (4 M, 1:3) solution was comparable to 5 M benchmark monoethanolamine (MEA) solution. Based on a preliminary estimation, the regeneration heat with TETA-DMCA could be reduced by approximately 40% compared with that of MEA. ¹³C NMR analysis revealed that the CO₂ absorption into TETA-DMCA was initiated by the reaction between CO₂ and TETA via the zwitterion mechanism, and DMCA served as a CO₂ sinker to regenerate TETA, resulting in the transfer of DMCA from the upper to lower phase. The proposed TETA-DMCA solvent may be a suitable candidate for CO₂ capture.