Carbon Dioxide Capture in the Iron and Steel Industry: Thermodynamic Analysis, Process Simulation, and Life Cycle Assessment

The iron and steel sector is one of the dominant drivers behind economic and social progress, but it is also very energy-intensive and hard-to-abate, making it a major cause of global warming. Improving energy efficiency, introducing hydrogen for direct reduction, and utilising CCS technologies are the three most viable options for reducing CO2 emissions from steel mills. This investigation deals with a life cycle comparison of three different carbon capture processes, the inventory data of which have been obtained using process simulation based on rigorous phase and chemical equilibrium equations. In-silico models for the absorption of carbon dioxide employing MDEA, membranes, or sodium hydroxide to produce sodium bicarbonate have been developed and compared from a life cycle viewpoint. The research findings showed a variable amount of CO2 removal in the three cases, where membranes achieved the best performance (95 % CO2 removal). Since NaOH absorption produces a valuable by-product (sodium bicarbonate, which is commonly produced by Solvay process), the other two technologies were modified to integrate the utilisation of CO2 for the synthesis of sodium bicarbonate with NaOH rather than transporting and storing the carbon dioxide. As a result, this production pathway for sodium bicarbonate generates lower environmental burdens than traditional Solvay process. The environmental performances of the alternatives are nearly equal, even though the environmental impacts associated with capturing the CO2 and subsequently reacting with NaOH are always slightly higher than those involved with reacting directly during absorption. Among the evaluated alternatives, the direct conversion to sodium bicarbonate appears to be the most promising approach for converting CO2 emissions in the steel sector

STEPWISE Project: Sorption-Enhanced Water-Gas Shift Technology to Reduce Carbon Footprint in the Iron and Steel Industry

ndustrial processes contribute significantly to global carbon dioxide emissions, with iron and steel manufacturing alone responsible for 6% of the total figure. The STEPWISE project, funded through the European Horizon 2020 (H2020) Low Carbon Energy (LCE) programme under grant agreement number 640769, is looking at reducing CO 2 emissions in the iron and steel making industries. At the heart of this project is the ECN technology called sorption-enhanced water-gas shift (SEWGS), which is a solid sorption technology for CO 2 capture from fuel gases such as blast furnace gas (BFG). This technology combines water-gas shift (WGS) in the WGS section with CO 2 /H 2 separation steps in the SEWGS section. Scaling up of the SEWGS technology for CO 2 capture from BFG and demonstrating it in an industrially relevant environment are the key objectives of the STEPWISE project, which are achieved by international collaboration between the project partners towards design, construction and operation of a pilot plant at Swerea Mefos, Luleå, Sweden, next to the SSAB steel manufacturing site

Techno-Economic Evaluations of Copper-Based Chemical Looping Air Separation System for Oxy-Combustion and Gasification Power Plants with Carbon Capture

Energy and economic penalties for CO2 capture are the main challenges in front of the carbon capture technologies. Chemical Looping Air Separation (CLAS) represents a potential solution for energy and cost-efficient oxygen production in comparison to the cryogenic method. This work is assessing the key techno-economic performances of a CLAS system using copper oxide as oxygen carrier integrated in coal and lignite-based oxy-combustion and gasification power plants. For comparison, similar combustion and gasification power plants using cryogenic air separation with and without carbon capture were considered as benchmark cases. The assessments were focused on large scale power plants with 350⁻500 MW net electricity output and 90% CO2 capture rate. As the results show, the utilization of CLAS system in coal and lignite-based oxy-combustion and gasification power plants is improving the key techno-economic indicators e.g., increasing the energy efficiency by about 5⁻10%, reduction of specific capital investments by about 12⁻18%, lower cost of electricity by about 8⁻11% as well as lower CO2 avoidance cost by about 17⁻27%. The highest techno-economic improvements being noticed for oxy-combustion cases since these plants are using more oxygen than gasification plants

Life Cycle Assessment for supercritical pulverized coal power plants with post-combustion carbon capture and storage

Environmental and technical aspects of four supercritical (SC) pulverized-coal processes with post-combustion carbon capture and storage (CCS) are evaluated in the present work. The post-combustion CCS technologies (e.g. MDEA, aqueous ammonia and Calcium Looping (CaL) are compared to the benchmark case represented by the SC pulverized coal without CCS). Some important key performance indicators (e.g. net electrical power, energy conversion efficiency, carbon capture rate, specific CO2 emissions, SPECCA) are calculated based on process modeling and simulation data. The focus of the present work lies in the environmental evaluation, using the Life Cycle Analysis (LCA) methodology, of the processes considered. The system boundaries include: i) power production from coal coupled to energy efficient CCS technologies based on post-combustion capture; ii) upstream processes such as extraction and processing of coal, limestone, solvents used post-combustion CCS, as well as power plant, coal mine, CO2 pipelines construction and commissioning and iii) downstream processes: CO2 compression, transport and storage (for the CCS case) as well as power plant, CCS units, coal mine and CO2 pipelines decommissioning. GaBi6 software was used to perform a “cradle-to-grave” LCA study, to calculate and compare different impact categories, according to CML 2001 impact assessment method. All results are reported to one MWh of net energy produced in the power plant. Discussions about the most significant environmental impact categories are reported leading to the conclusions that the introduction of the CCS technologies decreases the global warming potential (GWP) indicator, but all the other environmental categories increase with respect to the benchmark case. There is also a competition between the aqueous ammonia adsorption and CaL for some impact categories (other than GWP). The implementation of these new CCS technologies is more favorable than the traditional amine-based CO2 capture

Critical Assessment of Membrane Technology Integration in a Coal-Fired Power Plant

Despite the many technologies for CO2 capture (e.g., chemical or physical absorption or adsorption), researchers are looking to develop other technologies that can reduce CAPEX and OPEX costs as well as the energy requirements associated with their integration into thermal power plants. The aim of this paper was to analyze the technical and economic integration of spiral wound membranes in a coal-fired power plant with an installed capacity of 330 MW (the case of the Rovinari power plant—in Romania). The study modeled energy processes using CHEMCAD version 8.1 software and polymer membranes developed in the CO2 Hybrid research project. Thus, different configurations such as a single membrane step with and without the use of a vacuum pump and two membrane steps placed in series were analyzed. In all cases, a compressor placed before the membrane system was considered. The use of two serialized stages allows for both high efficiency (minimum 90%) and CO2 purity of a minimum of 95%. However, the overall plant efficiency decreased from 45.78 to 23.96% and the LCOE increased from 75.6 to 170 €/kWh. The energy consumption required to capture 1 kg of CO2 is 2.46 MJel and 4.52 MJth

Dynamic Modeling of CO₂ Absorption Process Using Hollow-Fiber Membrane Contactor in MEA Solution

In this work, a comprehensive mathematical model was developed in order to evaluate the CO2 capture process in a microporous polypropylene hollow-fiber membrane countercurrent contactor, using monoethanolamine (MEA) as the chemical solvent. In terms of CO2 chemical absorption, the developed model showed excellent agreement with the experimental data published in the literature for a wide range of operating conditions (R2 > 0.96), 1–2.7 L/min gas flow rates and 10–30 L/h liquid flow rates. Based on developed model, the effects of the gas flow rate, aqueous liquid absorbents’ flow rate and also inlet CO2 concentration on the removal efficiency of CO2 were determined. The % removal of CO2 increased while increasing the MEA solution flow rate; 81% of CO2 was removed at the high flow rate. The CO2 removal efficiency decreased while increasing the gas flow rate, and the residence time in the hollow-fiber membrane contactors increased when the gas flow rate was lower, reaching 97% at a gas flow rate of 1 L‧min−1. However, the effect was more pronounced while operating at high gas flow rates. Additionally, the influence of momentous operational parameters such as the number of fibers and module length on the CO2 separation efficiency was evaluated. On this basis, the developed model was also used to evaluate CO2 capture process in hollow-fiber membrane contactors in a flexible operation scenario (with variation in operating conditions) in order to predict the process parameters (liquid and gaseous flows, composition of the streams, mass transfer area, mass transfer coefficient, etc.)

Techno-Economic and Environmental Evaluations of Decarbonized Fossil-Intensive Industrial Processes by Reactive Absorption & Adsorption CO2 Capture Systems

Decarbonization of energy-intensive systems (e.g., heat and power generation, iron, and steel production, petrochemical processes, cement production, etc.) is an important task for the development of a low carbon economy. In this respect, carbon capture technologies will play an important role in the decarbonization of fossil-based industrial processes. The most significant techno-economic and environmental performance indicators of various fossil-based industrial applications decarbonized by two reactive gas-liquid (chemical scrubbing) and gas-solid CO2 capture systems are calculated, compared, and discussed in the present work. As decarbonization technologies, the gas-liquid chemical absorption and more innovative calcium looping systems were employed. The integrated assessment uses various elements, e.g., conceptual design of decarbonized plants, computer-aided tools for process design and integration, evaluation of main plant performance indexes based on industrial and simulation results, etc. The overall decarbonization rate for various assessed applications (e.g., power generation, steel, and cement production, chemicals) was set to 90% in line with the current state of the art in the field. Similar non-carbon capture plants are also assessed to quantify the various penalties imposed by decarbonization (e.g., increasing energy consumption, reducing efficiency, economic impact, etc.). The integrated evaluations exhibit that the integration of decarbonization technologies (especially chemical looping systems) into key energy-intensive industrial processes have significant advantages for cutting the carbon footprint (60–90% specific CO2 emission reduction), improving the energy conversion yields and reducing CO2 capture penalties

Life Cycle Assessment of Natural Gas-based Chemical Looping for Hydrogen Production

AbstractHydrogen production from natural gas, combined with advanced CO2 capture technologies, such as iron-based chemical looping (CL), is considered in the present work. The processes are compared to the conventional base case, i.e. hydrogen production via natural gas steam reforming (SR) without CO2 capture. The processes are simulated using commercial software (ChemCAD) and evaluated from a technical point of view considering important key performance indicators such as hydrogen thermal output, net electric power, carbon capture rate and specific CO2 emissions. The environmental evaluation is performed using Life Cycle Analysis (LCA) with the following system boundaries considered: i) hydrogen production from natural gas coupled to CO2 capture technologies based on CL, ii) upstream processes such as: extraction and processing of natural gas, ilmenite and catalyst production and iii) downstream processes such as: H2 and CO2 compression, transport and storage. The LCA assessment was carried out using the GaBi6 software. Different environmental impact categories, following here the CML 2001 impact assessment method, were calculated and used to determine the most suitable technology. Sensitivity analyses of the CO2 compression, transport and storage stages were performed in order to examine their effect on the environmental impact categories

Innovative Concepts for Hydrogen Production Processes Based on Coal Gasification with CO2 Capture

This paper investigates the technical aspects of innovative hydrogen production concepts based on coal gasification with CO2 capture. More specifically, it focuses on the technical evaluation and the assessment of performance of a number of plant configurations based on standard entrained flow gasification processes (dry feed and slurry feed types) producing hydrogen at pipeline pressure, which incorporate improvements for increasing hydrogen purity and pressure. Also, different CO2 capture methods (physical vs. chemical solvents) are assessed. The dry feed type of entrained flow gasifier is currently considered to be the most efficient means of producing hydrogen from coal. The main shortcomings are relatively low hydrogen purity due to the need of using nitrogen as a transport gas for the coal and a pressure limitation of this type of design. The purity issue can be solved by using captured CO2 or syngas to transport the coal in the gasifier. The pressure limitation can be overcome by using in-plant compression of the raw syngas. Simulations, made in ChemCAD, show that these changes can be made without compromising the plant efficiency; on the contrary, the efficiency slightly increases because of the better thermal integration of the plant.JRC.F.7-Cleaner energie