Periodic Reporting for period 2 - DISIPO (Decarbonisation of carbon-intensive industries (Iron and Steel Industries) through Power to gas and Oxy-fuel combustion)
Berichtszeitraum: 2022-07-01 bis 2023-06-30
Iron and Steel industry is one of the biggest CO2 emitters, accounting for the 7-9% of the global emissions. The current main steel manufacturing routes are (1) blast furnace combined with basic oxygen furnaces (BF-BOF) and (2) electric arc furnace route (EAF). The former, with production share above 70%, is based on the reduction of iron ores with coke in a blast furnace at temperatures beyond 2000 °C. The EAF route, which almost cover the remaining 30% of the world steel production, uses ferrous scrap as raw material (up to 70%). Since the global steel demand cannot be covered through recycled scrap, the BF-BOF route will maintain its dominance in the market. Besides, blast furnaces will only phased-out at relining, which typically takes places every 20-35 years, or up to 40 years for newly commissioned plants. Thus, at least 20% of today’s blast furnaces will still be in operation by year 2050. Therefore, innovative methods for CO2 reduction in blast furnaces must be developed.
One such method is top gas recycling (TGR), which consist on the recycling of the exhaust gas of the blast furnace back into the process, which acts as reducing agent to diminish the coke consumption. A carbon capture stage is usually included before recycling the top gas. The CO2 reduction achieved by this method is limited to 15% because of the presence of N2 in the recirculated gas. TGR evolved to the possibility of combining it with oxygen blast furnaces (OBF). Oxygen blast furnaces use pure oxygen instead of air to burn coke, reducing the amount of fossil fuel required and resulting in higher energy efficiency. The decrease in CO2 emissions is 10% – 40% with respect to BF. Since CO2 is rejected from the recycled top gas via a capture stage during recycling, a non-negligible amount of highly-concentrated CO2 gas is available for underground storage. An alternative option to take advantage of the captured CO2 is to combine OBF with Power to Gas (PtG). PtG technology consumes renewable electricity to produce H2 via water electrolysis, which is then combined with the CO2 emissions of the ironmaking process to obtain synthetic natural gas (SNG). This synthetic fuel is used in the blast furnace to keep carbon in a closed loop. The combination of OBF with PtG may reduce emissions around 45% with respect to air-blown blast furnaces.
One such method is top gas recycling (TGR), which consist on the recycling of the exhaust gas of the blast furnace back into the process, which acts as reducing agent to diminish the coke consumption. A carbon capture stage is usually included before recycling the top gas. The CO2 reduction achieved by this method is limited to 15% because of the presence of N2 in the recirculated gas. TGR evolved to the possibility of combining it with oxygen blast furnaces (OBF). Oxygen blast furnaces use pure oxygen instead of air to burn coke, reducing the amount of fossil fuel required and resulting in higher energy efficiency. The decrease in CO2 emissions is 10% – 40% with respect to BF. Since CO2 is rejected from the recycled top gas via a capture stage during recycling, a non-negligible amount of highly-concentrated CO2 gas is available for underground storage. An alternative option to take advantage of the captured CO2 is to combine OBF with Power to Gas (PtG). PtG technology consumes renewable electricity to produce H2 via water electrolysis, which is then combined with the CO2 emissions of the ironmaking process to obtain synthetic natural gas (SNG). This synthetic fuel is used in the blast furnace to keep carbon in a closed loop. The combination of OBF with PtG may reduce emissions around 45% with respect to air-blown blast furnaces.
The outputs from the DISIPO project are 9 open-access research articles, 3 conference contributions, 3 press releases, and 2 participations in radio live emissions. Moreover, a logo for the project was created and a webpage was launched (https://mbailera.es/research/disipo/).
The researcher was trained by Prof. Nakagaki (Waseda University) on simulating a blast furnace for ironmaking. The researcher was able to replicate the original Aspen Plus simulation of the Prof. Nakagaki’s research group. After this, Prof. Nakagaki provided the researcher with their original simulation and confidential operation data for a final comparison of minor details. The researcher adapted the base case simulation to O2-enriched atmospheres and, ultimately, to oxy-fuel regime. To do so, the researcher had to learn the Rist operating line methodology. The researcher revised all the original work of Rist (written between 1963 and 1967) and elaborated a revised version of the methodology. This was published as a research article in Open Research Europe. This revised Rist methodology was implemented in the Aspen Plus simulation to properly determine the operating conditions of the blast furnace when operating with O2-enriched atmospheres and when integrating Power to Gas.
Additionally, the Rist model was extended, comprising the generalization of the original Rist methodology in order to add new features to the methodology. These features were considered to be necessary to evaluate the new PtG integration proposals. The new features added the possibility of considering: (i) injections of gases at any part of the blast furnace (instead of only at the tuyeres), and (ii) injections of gases that are partially oxidized before entering the blast furnace. This new methodology, called as “extended operating line” was accepted for publication in ISIJ international.
Once the model was elaborated, the researcher analyzed and compared many different integrations for the iron and steel industry, comprising top gas recycling, oxygen blast furnaces, power to gas, and biomass resource. The best configuration provided 58% CO2 reduction, with an specific energy consumption of 9.8 MJ/kgCO2. Furthermore, the novel proposal provided more energy in the form of BFG, for downstream processes than the conventional air-blown blast furnaces.
The researcher was in contact with JFE Steel (second largest Japanese steel manufacturer) through members of Prof. Nakagaki’s research group, what allowed to validate the simulations. Moreover, the researcher visited the JFE steel Chiba steelmaking plant (located on the east coastal industrial zone of Tokyo) on 21st June 2022, and he also visited the Voestalpine steelmaking plant in Linz, Austria on 5th September 2022. These insights helped the researcher to establish reasonable scenarios for the implementation of the PtG technology, in terms of proper operating conditions, end-use of the synthetic natural gas, space limitations, etc.
The researcher was trained by Prof. Nakagaki (Waseda University) on simulating a blast furnace for ironmaking. The researcher was able to replicate the original Aspen Plus simulation of the Prof. Nakagaki’s research group. After this, Prof. Nakagaki provided the researcher with their original simulation and confidential operation data for a final comparison of minor details. The researcher adapted the base case simulation to O2-enriched atmospheres and, ultimately, to oxy-fuel regime. To do so, the researcher had to learn the Rist operating line methodology. The researcher revised all the original work of Rist (written between 1963 and 1967) and elaborated a revised version of the methodology. This was published as a research article in Open Research Europe. This revised Rist methodology was implemented in the Aspen Plus simulation to properly determine the operating conditions of the blast furnace when operating with O2-enriched atmospheres and when integrating Power to Gas.
Additionally, the Rist model was extended, comprising the generalization of the original Rist methodology in order to add new features to the methodology. These features were considered to be necessary to evaluate the new PtG integration proposals. The new features added the possibility of considering: (i) injections of gases at any part of the blast furnace (instead of only at the tuyeres), and (ii) injections of gases that are partially oxidized before entering the blast furnace. This new methodology, called as “extended operating line” was accepted for publication in ISIJ international.
Once the model was elaborated, the researcher analyzed and compared many different integrations for the iron and steel industry, comprising top gas recycling, oxygen blast furnaces, power to gas, and biomass resource. The best configuration provided 58% CO2 reduction, with an specific energy consumption of 9.8 MJ/kgCO2. Furthermore, the novel proposal provided more energy in the form of BFG, for downstream processes than the conventional air-blown blast furnaces.
The researcher was in contact with JFE Steel (second largest Japanese steel manufacturer) through members of Prof. Nakagaki’s research group, what allowed to validate the simulations. Moreover, the researcher visited the JFE steel Chiba steelmaking plant (located on the east coastal industrial zone of Tokyo) on 21st June 2022, and he also visited the Voestalpine steelmaking plant in Linz, Austria on 5th September 2022. These insights helped the researcher to establish reasonable scenarios for the implementation of the PtG technology, in terms of proper operating conditions, end-use of the synthetic natural gas, space limitations, etc.
DISIPO project went beyond the state of the art in several aspects. First, a new generalized operating line model was developed during the project. This methodology allows for studying oxygen blast furnaces using their characteristic operating line, including variable molar flows along the blast furnace (i.e. injections of gases at any part of the blast furnace), and non-continuous oxidation profiles (i.e. injections of gases that are partially oxidized before entering the blast furnace). This new model was adopted as a standard by the Prof. Nakagaki’s Laboratory for their internal research and collaborations with industry, thus representing a huge impact from the socio-economic point of view. This model has been used also by the University of Zaragoza, in Spain, for ongoing projects in the topic of Iron and Steel. This has also a direct impact in the collaborations and funding of the Energy and CO2 research group of the University of Zaragoza, which was recently awarded with a new research project on the topic.
Secondly, new process flow diagrams of Power to Gas integration have been proposed and studied. Only a few studies concerning Power to Gas and ironmaking could be found in literature before DISIPO project, so the results of DISIPO project help to increase the knowledge in the technology. It is of special interest the novel proposal combining biomass resource, power to gas, and oxygen blast furnaces, which provided the best results to date.
Lastly, the direct collaboration with real steel plants (JFE Steel, and Voestalpine) allowed for realistic studies on the application of Power to Gas to the different processes of ironmaking. Moreover, the operating strategies, sizing of the equipment, and economic analyses are adapted to real industrial scenarios and data. These results are new in literature. There are no studies with such implications. This represents a step forward of the state of the art, and a real impact in the transfer of knowledge between research and industries. It also helps increasing the interest of real industries on the process, showing realistic results of what Power to Gas can offer.
Secondly, new process flow diagrams of Power to Gas integration have been proposed and studied. Only a few studies concerning Power to Gas and ironmaking could be found in literature before DISIPO project, so the results of DISIPO project help to increase the knowledge in the technology. It is of special interest the novel proposal combining biomass resource, power to gas, and oxygen blast furnaces, which provided the best results to date.
Lastly, the direct collaboration with real steel plants (JFE Steel, and Voestalpine) allowed for realistic studies on the application of Power to Gas to the different processes of ironmaking. Moreover, the operating strategies, sizing of the equipment, and economic analyses are adapted to real industrial scenarios and data. These results are new in literature. There are no studies with such implications. This represents a step forward of the state of the art, and a real impact in the transfer of knowledge between research and industries. It also helps increasing the interest of real industries on the process, showing realistic results of what Power to Gas can offer.