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Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro
ISIJ International, 55(2), p.348 - 358, 2015/02
Times Cited Count：8 Percentile：39.68(Metallurgy & Metallurgical Engineering)Reducing coking coal consumption and CO
emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Both the effects on saving of the coking coal and reduction of CO emissions were greater in the RWGS system. It was the reason of the result that excess H which was not consumed in the RWGS reaction was used as reducing agent in the BF as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO emissions more efficiently by comparing CO emissions reduction per unit heat of HTGR.
emission reduction of active carbon recycling energy system for ironmaking by modeling with Aspen PlusSuzuki, Katsuki*; Hayashi, Kentaro*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji
ISIJ International, 55(2), p.340 - 347, 2015/02
Times Cited Count：19 Percentile：64.17(Metallurgy & Metallurgical Engineering)Use of the Active Carbon Recycling Energy System in ironmaking (iACRES) has been proposed for reducing CO emissions. To evaluate the performance of iACRES quantitatively, a process flow diagram of a blast furnace model with iACRES was developed using Aspen Plus, a chemical process simulator. CO emission reduction and exergy analysis were performed by using mass and energy balance obtained from simulation results. The following CO reduction methods were evaluated as iACRES: solid oxide electrolysis cells (SOEC) with CO capture and separation (CCS), SOEC without CCS, and a reverse water-gas shift reactor powered by a high-temperature gas-cooled reactor. iACRES enabled CO emission reduction by 3-11% by recycling CO and H, whereas effective exergy ratio decreased by 1-7%.
Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro
Tanso Junkan Seitetsu Kenkyukai Saika Hokokusho; Tanso Junkan Seitetsu No Tenkai, p.42 - 62, 2015/02
Reducing coking coal consumption and CO emissions by application of HTGRs (high temperature gas-cooled reactors) to iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Coking coal consumption was reduced from a conventional BF (blast furnace) steelmaking system by 4.3% in the SOEC system and 10.3% in the RWGS system. CO emissions were decreased by 3.4% in the SOEC system and 8.2% in the RWGS system. Remaining H from the RWGS reactor was used as reducing agent in the BF in the RWGS system. This was the reason of the larger reduction of coking coal consumption and CO emissions. Electricity generation for SOEC occupied most of HTGR heat usage in the SOEC system. H production in the IS process used most of the HTGR heat in the RWGS system. Optimization of the SOEC temperature for the SOEC system and higher H production thermal efficiency in the IS process for the RWGS system will be useful for more efficient heat utilization. One typical-sized BF required 0.5 HTGRs and 2 HTGRs for in the SOEC system and RWGS system, respectively. CO emissions reduction per unit heat input was larger in the SOEC system. Recycling H to the RWGS will be useful for smaller emissions per unit heat in the RWGS system.
Hayashi, Kentaro*; Suzuki, Katsuki*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji
Tanso Junkan Seitetsu Kenkyukai Saika Hokokusho; Tanso Junkan Seitetsu No Tenkai, p.27 - 41, 2015/02
Applying Active Carbon Recycling Energy System to ironmaking (iACRES) process is a promising technology to reduce coal usage and CO emissions. To evaluate performance of iACRES quantitatively, a process flow diagram of the blast furnace model with iACRES was developed using Aspen Plus. CO emission reduction and exergy analysis was predicted by using mass and energy balance obtained from the simulation results. The followings were investigated as iACRES: solid oxide electrolysis cells (SOEC) with CO capture and separation (CCS), SOEC without CCS, and a reverse water-gas shift reactor as the a CO reduction reactor powered by a high-temperature gas-cooled reactor. iACRES could provide CO emission reductions of 3-11% by recycling CO and H, whereas the effective exergy ratio decreased by 1-7%.
reductionNakagaki, Takao*; Kasahara, Seiji; Inagaki, Yoshiyuki; Ogawa, Masuro
no journal, ,
CO emissions from steelmaking is expected to be reduced by substituting some part of coke with CO recycled from waste CO using CO-free heat source. Considering application to this carbon recycling steelmaking, a CO reduction system comprising of a high temperature gas cooled reactor (HTGR) and a solid oxide electrolysis cell (SOEC) was simulated and important process specifications for high efficiency CO reduction was clarified. Larger heat input to the SOEC with smaller temperature difference at heat exchangers from the HTGR to the SOEC was effective for higher efficiency. Steelmaking scale using the CO reduction system with a HTGR of 600 MW thermal output was 1.16
10
t/y. A few HTGRs were needed for application to a conventional blast furnace steelmaking plants, which produce steel of a few million ton per year.
Hayashi, Kentaro*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro
no journal, ,
Process evaluation of use of high temperature gas-cooled reactors (HTGRs) to the ironmaking system based on active carbon recycling energy system (iACRES), where CO is recycled by reduction of CO from blast furnaces (BFs), was carried out by heat and material flow analysis. The investigated CO recovery methods were CO electrolysis and CO reduction in reverse water gas shift reaction (RWGS) using H made in the IS process. HTGR number per BF was large in the CO reduction process because more H than stoichiometric amonut was required to keep RWGS equilibrium. More CO reduction per unit ironmaking amount was expected in the CO reduction process because H not used in RWGS was consumed by iron ore reduction in the BF. However, CO reduction per HTGR was larger in the CO eelctrolysis method.
Hayashi, Kentaro*; Suzuki, Katsuki*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji
no journal, ,
Evaluation of active carbon recycling energy system for ironmaking process by modeling with Aspen Plus was carried out by CO emission and exergy consumption. The investigated CO recovery methods were CO electrolysis and CO reduction in reverse water gas shift reaction (RWGS) using H made in the HTGR-IS process. More H than stoichiometric amonut was required to keep RWGS equilibrium and H not used in RWGS was consumed by iron ore reduction in the BF. Though CO decrease was more in CO reduction process, exergy consumption was larger. CO decrease was larger in higher BFG circulation ratio and CO reduction ratio due to more carbon recycle. Exergy consumption was large in the higher reduction ratio because of more electricity consumption.
