Faculty Profiles - NORINAGA Koyo

Nickel/Zirconia-Catalyzed CO2 Methanation in Differential and Integral Fixed-Bed Reactors: Experimental and Computational Fluid Dynamics Studies Reviewed Open Access

Shimada, T; Nakamura, M; Fukumoto, K; Ibrahim, M; Wasnik, CG; Machida, H; Norinaga, K

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH Vol. 64 ( 3 ) page： 1473 - 1487 2025.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Industrial and Engineering Chemistry Research

Isothermal conditions and a chemical-kinetics-limited rate should be maintained when measuring the reaction rates of gases on solid catalysts. However, in highly exothermic reactions─such as the Sabatier reaction─temperature variations within the catalyst bed make it challenging to achieve isothermality. In this study, temperature changes in a Ni/ZrO<inf>2</inf> catalyst bed were minimized using α-Al<inf>2</inf>O<inf>3</inf> diluent and high gas hourly space velocities (GHSVs) to achieve low feed gas conversion (differential conditions: 0.9 MPa; 523-873 K; GHSV = 7600-30,000 L/h/g cat). The temperature profile within the catalyst bed was obtained by coupling a previously reported kinetic model with three-dimensional computational fluid dynamics (CFD) simulations. Experiments were also conducted under integral conditions at low GHSVs, resulting in high conversion rates and heat release. CFD simulations accurately reproduced the experimental feed gas conversion and temperature, suggesting that the CFD-simulation-guided kinetic parameters appropriately predicted the methanation characteristics at practically relevant high conversion rates.

DOI： 10.1021/acs.iecr.4c03789

CFD simulation of crude oil fouling from laboratory- to industrial-scale heat exchangers using a weak coupling approach Reviewed

Fukumoto, K; Zhang, W; Choi, C; Tang, F; Machida, H; Norinaga, K

APPLIED THERMAL ENGINEERING Vol. 258 2025.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Thermal Engineering

Crude oil fouling is described as an accumulation of unwanted materials such as asphaltene and metallic salt on a heat transfer surface in a pre-heat train of the crude distillation unit in oil refineries, causing an economic loss of 1–1.2 billion U.S. dollars per year in 2019. Computational fluid dynamics is one of the useful simulation tools for numerical research on this topic. However, crude oil fouling is a long-term phenomenon; therefore, the time scale is longer than general computational fluid dynamics problems. The fouling layer in oil refineries grows over several months to several years despite the small pipe diameter of several or several tens of millimetres. For this reason, it is not easy to satisfy the Courant–Friedrichs–Lewy condition. To overcome this problem, we developed a new algorithm based on a weak coupling approach, validated this scheme, and exhibited the application of this technology. In the new algorithm, momentum and pressure fields and enthalpy and mass fraction fields are solved separately. The algorithm was implemented as FoulingFOAM, a crude oil fouling simulator based on OpenFOAM v2006. Then, the solver was first validated with the lab-scale measurements, showing good agreement with the experimental data. Next, industrial-scale data in the two refineries were simulated for validation. It was possible to predict the peak fouling resistance against time. Finally, for both lab- and industrial-scale simulations, the predictions of our numerical tool showed that fouling resistance increased with higher wall temperature, lower crude oil velocity, and higher concentration of fouling species, which were identical to previous measurements. Hence, we concluded that the weak coupling approach is promising for investigating crude oil fouling problems.

DOI： 10.1016/j.applthermaleng.2024.124614

Advanced CO2 Methanation Process Optimization and Techno-Economic Assessment with Flue Gas CO2 Capture from Automotive Shredder Residue

Wasnik Chopendra G., Nakamura Maki, Machida Hiroshi, Ito Junji, Shiratori Kazuyuki, Norinaga Koyo

The Proceedings of the National Symposium on Power and Energy Systems Vol. 2025.29 ( 0 ) page： B243 2025

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

Valorizing Automobile Shredder Residue (ASR) for carbon-neutral methane synthesis integrates thermochemical conversion, Combined Heat and Power (CHP) cogeneration, CO2 capture, and catalytic methanation with renewable H2. Simulations show Case I (chemically absorbed CO2 methanation) outperforms Case II (direct methanation), producing 4,800 vs. 2,720 tons/year at 46.5% efficiency. By 2050, Case I’s methane cost is projected at $1,241/ton, proving ASR-derived CO2 methanation economically viable.

DOI： 10.1299/jsmepes.2025.29.b243

1-07　Techno-Economic Analysis on Synthesis of Tetrahydrofurfuryl Alcohol by Furfural Hydrogenation Reviewed

UEHARA Yusuke, LI Qiao, RAO Thuppati Upender, MACHIDA Hiroshi, NORINAGA Koyo

Proceedings of Conference on Coal Science Vol. 61 ( 0 ) page： 14 - 15 2024.10

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

Efficient conversion of biomass-derived furfural into high value-added chemicals such as tetrahydrofurfuryl alcohol (THFA) by hydrogenation has received much attention in terms of post-fossil fuel and energy saving. While many researchers have put their efforts on developing cost-effective catalysts for furfural hydrogeneration, only little investigations have been reported on its techno-economic analysis as well as process optimization. This study aims to design an energy saving process model of furfural hydrogeneration for THFA synthesis coupled with thermal recovery system consisting of organic Rankine cycle and heat pump, and to evaluate energy efficiency and economics of the proposed process through Aspen simulation, based on our previous experimental data with Ni1Cu1-Al1 catalyst.

DOI： 10.20550/jiesekitanronbun.61.0_14

1-03　Conversion of carbon dioxide to ethylene by electrolytic reduction using perovskite catalysts Reviewed

Suchada SIRISOMBOONCHAI, Norinaga KOYO

Proceedings of Conference on Coal Science Vol. 61 ( 0 ) page： 6 - 7 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

The electrochemical CO2 reduction reaction (eCO2RR) offers a sustainable method for reducing greenhouse gas emissions by converting CO2 into valuable chemicals and fuels without requiring extreme conditions. Electrocatalysts play a significant role in this process by producing carbon-based products such as ethylene, etc. Perovskite oxides have emerged as promising electrocatalysts due to their high ionic/electronic structure, stability, ability to vary elements, and the alkaline earth effect, which enhances the *CO2 - intermediate. Specifically, Ca is the A-site in coordination with the Cu-site, providing Ca2CuO3 with strong basic strength and exceptional CO2 adsorption capabilities. The Ca2CuO3 catalyst demonstrates significant efficiency in converting CO2 to C2H4, exceeding FEC2H4 50% at 100 mA/cm2. This research represents an attractive advancement in realizing the conversion of CO2 to C2H4.

DOI： 10.20550/jiesekitanronbun.61.0_6

Design and Optimization of Large-Scale Green Liquid Hydrogen Production Integrated with Heat Recovery and Absorption Precooling Reviewed

Li, Q; Machida, H; Norinaga, K

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH Vol. 63 ( 44 ) page： 19063 - 19075 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Industrial and Engineering Chemistry Research

Liquid hydrogen (LH<inf>2</inf>) presents a viable solution for energy storage and transportation, particularly when produced by using renewable electricity. In this study, the energy efficiency of large-scale PEM water electrolysis for hydrogen production was investigated to be 59.74%, with the levelized electricity cost of hydrogen of 57.48 kWh/kg. To recover the waste heat from the PEM electrolyzer, two heat integration approaches have been proposed: the organic Rankine cycle (ORC) and the absorption refrigeration cycle (ARC). The ORC converted waste heat into electricity, while the ARC generated cold energy to precool the refrigerant, alongside electricity generation, both of which reduced energy consumption in the hydrogen liquefaction process. Subsequently, the process parameters were optimized through Matlab with the Mesh Adaptive Direct Search algorithm aimed at minimizing the specific energy consumption (SEC) of hydrogen liquefaction integrated with ORC or ARC, resulting in SECs of 6.76 and 6.61 kWh/kg LH<inf>2</inf>, with 21.33% and 22.87% reductions compared with the liquefaction process without heat recovery, respectively. The corresponding exergy efficiencies were 56.96% and 57.16% for the liquid hydrogen production process, with 86.69% and 87.73% for the hydrogen liquefaction process, respectively.

DOI： 10.1021/acs.iecr.4c02383

P-4-5　Investigation of numerical conditions for heat transfer in a CO2 sublimation tank Reviewed

YAMAGUCHI Hiroyasu, UEHARA Yusuke, MACHIDA Hiroshi, NORINAGA Koyo, SAITO Yasuhiro

Proceedings of the Annual Conference of The Japan Institute of Energy Vol. 33 ( 0 ) page： 244 - 245 2024.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

Numerical simulations for cooling of CO2 gas around a cold plate in a laboratory-scale sublimation tank were performed to investigate the effect of the heat flux from the plate and the initial temperatures of the CO2 gas on the temperature distribution. The results showed that the heat flux of the plate had a minimal impact on the temperature distribution in the tank. The effect of the heat of sublimation of CO2 on the temperature distribution in the tank would be significantly large.

DOI： 10.20550/jietaikaiyoushi.33.0_244

6-2-4　Development of Atomically Dispersed Ni Catalyst on N-doped Carbonized Lignin for Highly Efficient Electrochemical CO2 Reduction Reviewed

Park Gi-Dong, Suchada Sirisomboonchai, Norinaga Koyo

Proceedings of the Annual Conference of The Japan Institute of Energy Vol. 33 ( 0 ) page： 166 - 167 2024.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

The Ni single-atom catalysts (SACs) on N-doped carbon are promising electrocatalyst for the electrochemical CO2 reduction (CO2R), owing to their unique electrocatalytic properties. However, conventional methods to fabricate SACs are not environmentally friendly. To overcome it, we utilized lignin for preparing Ni SAC, which is derived from biomass. Furthermore, the coordination number of Ni−NxC sites was regulated to investigate the effects of change in geometrical/electronic nature on catalytic behaviors. The Ni SAC on lignin-derived N-doped carbon performed an CO Faradaic efficiency of 98.2 % at −0.9 V vs. RHE, in H-type cell configuration. Along with experimental results, DFTbased theoretical calculations elucidated the reasons for the enhanced CO2R performance, depending on the different coordination environments of Ni−NxC sites.

DOI： 10.20550/jietaikaiyoushi.33.0_166

6-2-2　Study on methane synthesis process using treated gas from automobile shredder dust as feedstock Reviewed

Nakamura Maki, Li Qiao, Chopendra G. Wasnik, Norinaga Koyo

Proceedings of the Annual Conference of The Japan Institute of Energy Vol. 33 ( 0 ) page： 162 - 163 2024.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

This study proposes a rational process aimed at carbon recycling to effectively recycle carbon dioxide (CO2) emitted from automobile shredder residue (ASR). The methods investigated include direct methane synthesis from ASR process gas and methane synthesis from CO2 recovered by chemical absorption using a gas engine cogeneration system. By optimizing the type and operating conditions of these reactors, it was found that the methane synthesis cost can be reduced by using CO2 recovered through chemical absorption in the methane synthesis process.

DOI： 10.20550/jietaikaiyoushi.33.0_162

6-2-3　Development Of CO2 Methanation Catalysts Supported On CeO2 And SiC At Elevated Temperatures Reviewed

Chopendra G. Wasnik, Nakamura Maki, Shimada Taiki, Machida Hiroshi, Norinaga Koyo

Proceedings of the Annual Conference of The Japan Institute of Energy Vol. 33 ( 0 ) page： 164 - 165 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

The increasing concentration of CO2 in the atmosphere is a major environmental concern, and effective utilization of CO2 is crucial. In this context, efficient circulation and utilization of CO2 are paramount. The methanation process emerges as a critical strategy for effective CO2 utilization. The methanation is an exothermic reaction. Therefore, catalysts that uphold high activity and methane selectivity over a wide temperature range are in significant demand. This study investigated 2Ni-2Co/SiC and 2Ni-2Co/CeO2 bimetallic catalysts, using only 20 mg of the sample. The experiments were carried out in a fixed-bed tubular reactor at a steady GHSV of 12,000 h-1. The results showed that the catalyst 2Ni-2Co/SiC showed 77% conversion of CO2 with an 88% CH4 selectivity, while 2Ni-2Co/CeO2 demonstrated 76% CO2 conversion and 83% selectivity for CH4 at 500°C. These bimetallic catalysts have high activity for Ni and Ru, with resistance to Co and Mn carbon deposition, and can withstand high temperatures up to 500°C without losing activity, selectivity, and thermal stability. The catalysts were characterized through multiple tests, to unveil their physicochemical properties. The Co and Mn have effectively restrained the Ni and Ru agglomeration, optimized metal dispersion, and enhanced catalytic activity even in high-temperature environments.

DOI： 10.20550/jietaikaiyoushi.33.0_164

LNG Oxy-Fuel Power and Green Methanol Poly Generation Systems Associated with CO2 Condensation Capture: Techno-Economic Environmental Assessment Reviewed

Discussion Reviewed

NODA Reiji, NORINAGA Koyo, FUSHIMI Chihiro, ENOMOTO Hiroshi, HOSOKAI Sou, OTA Tomohisa

Nihon Enerugii Gakkai Kikanshi Enermix Vol. 103 ( 4 ) page： 422 - 431 2024.7

Li, Q; Machida, H; Feng, ZM; Norinaga, K

ENERGY & FUELS Vol. 38 ( 14 ) page： 13089 - 13103 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Energy and Fuels

To achieve energy-environment synergy and sustainability, this study proposes a poly generation system that integrates the energy release process of liquefied natural gas (LNG) oxy-fuel power generation with the energy storage process of green methanol synthesis from renewable energy. In this system, oxygen, the byproduct of water hydrolysis to hydrogen, can support LNG oxy-fuel power generation; while the cold energy released during LNG regasification can serve as a cold source for carbon capture, the captured CO<inf>2</inf> can be utilized as the carbon source for methanol synthesis, thus realizing cleaner methanol production and an efficient power generation process with near-zero carbon emission. Following the process design, the parameters were optimized with minimum levelized production cost of methanol and electricity as the objective function through Matlab using the “MADS” algorithm, resulting in 683.79 $/tonne and 68.05 $/MW h, respectively, with overall exergy efficiency of 50.28%. Notably, as green methanol synthesis requires additional CO<inf>2</inf>, a reduction of 2272.59 kg/h can be achieved. The study concludes that the novel poly generation process is superior in exergy efficiency and CO<inf>2</inf> capture and utilization but inferior in high production costs.

DOI： 10.1021/acs.energyfuels.4c01250

Environmental-friendly extraction of di(2-ethylhexyl) phthalate from poly (vinyl chloride) using liquefied dimethyl ether Reviewed

Wang, T; Kanda, H; Kusumi, K; Mei, L; Zhang, LJ; Machida, H; Norinaga, K; Yamamoto, T; Sekikawa, H; Yasui, K; Zhu, L

WASTE MANAGEMENT Vol. 183 page： 21 - 31 2024.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Waste Management

Poly(vinyl chloride) (PVC) is one of the most widely used plastics. However, a major challenge in recycling PVC is that there is no economical method to separate and remove its toxic phthalate plasticizers. This research made a breakthrough by extracting PVC with liquefied dimethyl ether (DME) and successfully separating the plasticizer components. Nearly all (97.1 %) of the di(2-ethylhexyl) phthalate plasticizer was extracted within 30 min by passing liquefied DME (285 g) through PVC at 25 °C. The compatibility of PVC with organic solvents, including liquefied DME, was derived theoretically from their Hansen solubility parameters (HSP), and actual dissolution experiments were conducted to determine the optimal PVC solvents. A liquefied DME mixture was used to dissolve PVC, and the extract was diluted with ethanol to precipitate the dissolved PVC. We demonstrated that liquefied DME is a promising method for producing high quality recycled products and that the process retains the fundamental properties of plasticizers and PVC without inducing degradation or depolymerization. Because of its low boiling point, DME can be easily separated from the solute after extraction, allowing for efficient reuse of the solvent, extracted plasticizer, and PVC. DME does not require heat and produces little harmful wastewater, which significantly reduces the energy consumption of the plasticizer additive separation process.

DOI： 10.1016/j.wasman.2024.04.050

Energy optimization of a non-aqueous solvent CO2 absorption system with pressure swing regeneration Reviewed

PubMed

Chairunnisaa; Zhou, YX; Wu, YT; You, C; Thu, K; Miyazaki, T; Uehara, Y; Machida, H; Norinaga, K

INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL Vol. 135 2024.6

Language：English Publishing type：Research paper (scientific journal) Publisher：International Journal of Greenhouse Gas Control

This study focuses on optimizing the energy requirement in the post-combustion CO<inf>2</inf> capture system using pressure swing regeneration through a model-based design (MBD). The simulation results highlight the significant impact of CO<inf>2</inf> recovery, inlet gas and liquid flow rate, and CO<inf>2</inf> concentration in the flue gas on the overall energy demand of the system. Moreover, an investigation into the de-sublimation chamber was undertaken, revealing a relationship between dry ice formation and the heat transfer between the LNG stream and CO<inf>2</inf> in the heat exchanger. The parametric analysis study reveals that the sensible heat of the lean solvent is significantly influenced by the CO<inf>2</inf> concentration in the liquid, consequently affecting the overall system energy. According to the results, the utilization of cold energy from LNG could save 80 % of the total energy requirement. The optimization results found the best working condition, which consumes energy of 0.190 GJ/ton CO<inf>2</inf>, 31 % lower than the basic scenario.

DOI： 10.1016/j.ijggc.2024.104154

High-Throughput CO2 Solubility Measurement in Miscible and Liquid-Liquid Phase Separation Types of Amine Solvent Using Headspace Gas Chromatography Reviewed

Tran, KVB; Yanase, K; Rao, TU; Hirayama, M; Norinaga, K; Machida, H

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH Vol. 63 ( 13 ) page： 5823 - 5832 2024.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Industrial and Engineering Chemistry Research

CO<inf>2</inf> solubility is one of the key factors in evaluating not only the efficiency of the absorbent but also the energy consumption of the CO<inf>2</inf> capture process from flue gas. In this study, a system namely headspace gas chromatography (HS-GC), which is a combination of gas chromatography (GC-3200, GL Sciences) and a headspace autosampler (Turbomatrix HS16, PerkinElmer), was developed to measure the CO<inf>2</inf> solubility of amine solutions. The equilibrium time and calibration curve of this system were checked and compared with those of the literature data. The developed system showed high reproducibility with reference CO<inf>2</inf> solubility data of benchmark amine solutions. Distinct from conventional measurement methods of CO<inf>2</inf> solubility, high-throughput CO<inf>2</inf> solubility measurement by HS-GC shows its advantages such as a small amount sample requirement, rapid achievement of equilibration time, automation of sample exchange, and high reproducibility, which is superior in the amine solvent screening phase. Moreover, this system can evaluate new types of CO<inf>2</inf> capture solvents, including the phase separation solvent. By acquiring continuous data, the inflection point in the solubility curve indicated by phase separation was observed. The absorption heat estimated from those CO<inf>2</inf> solubility curves measured by this system also agrees well with the experimental data.

DOI： 10.1021/acs.iecr.3c03314

Design and Optimization for Sustainable Synthesis of Tetrahydrofurfuryl Alcohol by Furfural Hydrogenation: Kinetic and Techno-economic Investigations Reviewed

Li Q., Rao T.U., Uehara Y., Machida H., Huo Z., Norinaga K.

ACS Sustainable Resource Management Vol. 1 ( 2 ) page： 316 - 327 2024.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Sustainable Resource Management

To address energy challenges, we propose synthesizing tetrahydrofurfuryl alcohol from biomass-derived furfural and hydrogen produced through electrolysis. Building upon prior research [Energy Convers. Manage.2022 2022, 265, 115736], the kinetic parameters of the developed catalysts for two-step reactions including furfural hydrogenation to furfuryl alcohol and tetrahydrofurfuryl alcohol were investigated, in which the activation energies were E<inf>a1</inf>= 29.35 and E<inf>a2</inf>= 38.97 kJ/mol, respectively. Subsequently, we designed the complete production process, including hydrogen generation, furfural hydrogenation, and tetrahydrofurfuryl alcohol purification. To enhance economic efficiency by minimizing energy consumption, the organic Rankine cycle-coupled heat pump was integrated into the process. Following the process design, the parameters were optimized with minimum levelized production cost of tetrahydrofurfuryl alcohol as the objective function by Matlab using the “MADS” algorithm, which resulted in 1855.85 $/tonne with 76.62 % overall energy efficiency. Finally, sensitivity analyses were performed to determine the cost factors affecting the economic indicators. This work provides a sustainable and profitable process route for producing high-quality chemicals from biomass, particularly in the context of potential future fossil energy crises.

DOI： 10.1021/acssusresmgt.3c00084

Design and optimization of the flexible poly- generation process for methanol and formic acid from CO2 hydrogenation under uncertain product prices Reviewed

Li, Q; Machida, H; Ren, XS; Feng, ZM; Norinaga, K

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY Vol. 54 page： 635 - 651 2024.2

Language：English Publishing type：Research paper (scientific journal) Publisher：International Journal of Hydrogen Energy

During the design of the carbon capture and hydrogen storage process, a static CO<inf>2</inf> hydrogenation poly-generation process for methanol and formic acid synthesis was developed, thereby reducing recycling flow and feedstock losses in the single methanol synthesis process and increasing product diversity. Additionally, a novel flexible poly-generation process was proposed as the product prices fluctuated with the market environment throughout the plant's life cycle. For the static poly-generation process, a mixed integer nonlinear programming model was established, followed by the Mesh Adaptive Direct Search algorithm to determine the optimal parameter design. For flexible processes, with the unscented transform tool, a two-stage optimization strategy is proposed for obtaining optimal design and operating parameters that are computationally tractable. With an input CO<inf>2</inf> flow rate of 200 kmol/h, the results show (1) the static process with an optimal Return On Investment of 13.05%, a fixed investment cost of $ 34.14 × 106, and an annual net profit of 4.46 × 106 $/year; and (2) the flexible process, in which the flexibility indices of the methanol and formic acid production units are 1.088 and 1.194, respectively, resulting the fixed investment cost increase to $ 39.19 × 106, an increase of 14.79%. Accordingly, the annual net profit increased by 8.97% to 4.86 × 106 $/year, while the Return On Investment decreased by 4.67%–12.44%. For investment decision-makers, the flexible poly-generation process can achieve higher profits and reduce potential market risks when they have adequate financing.

DOI： 10.1016/j.ijhydene.2023.01.205

Regulation of temperature distribution in fixed bed reactor for CO2 methanation through "CHESS" monolith structure catalyst Reviewed

researchmap

Zhang, W; Lin, YX; Zhang, YM; Li, TL; Li, JZ; Chen, ZW; Norinaga, K

APPLIED THERMAL ENGINEERING Vol. 236 2024.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Thermal Engineering

CO<inf>2</inf> methanation suffers from the problem of temperature runaway phenomenon due to its exothermic nature. To mitigate this issue, optimizing catalyst structure becomes crucial. This work established numerical models to investigate the CO<inf>2</inf> methanation reaction and heat/mass transfer process in the reactor with porous pellet and monolithic catalysts. Results show that the reactor with porous pellets has the lowest carbon conversion per unit pressure drop due to its large total pressure drop. In contrast, the reactor with monolith exhibits a much larger carbon conversion per unit pressure drop but a smaller absolute carbon conversion. Based on this, an improved “CHESS” monolith structure was proposed and improved, which not only maintains a high absolute carbon conversion (62.6 %) but also enhances the heat transfer process in CO<inf>2</inf> methanation. Moreover, compared with the reactor with porous pellets, the maximum temperature in the improved “CHESS” monolith was decreased by around 11.09 %.

DOI： 10.1016/j.applthermaleng.2023.121826

1-02　Tar and soot formation characteristics of various coals in a two-stage entrained flow coal gasifier revealed by detailed chemical kinetic modeling

LI Tailin, NAKAMURA Maiki, UEHARA Yusuke, MACHIDA Hiroshi, NORINAGA Koyo

Proceedings of Conference on Coal Science Vol. 60 ( 0 ) page： 4 - 5 2023.10

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

Substituting air with either CO2 or H2O in the gasifying agents presents a viable strategy for promptly integrating a carbon-neutral energy vector into coal gasification technology, concurrently mitigating harmful particulate matter emissions. However, fully understanding the evolution of tar in the practical gasifier has proven to be challenging owing to complex mixture of the scale of reactors. This study presents a detailed kinetic investigation of tar and soot formations from the gas-phase reactions in the reductor of a two-stage entrained flow coal gasifier under oxy-fuel (O2/CO2, O2/H2O) atmospheres. The effects of temperature and coal types were studied. The results show that benzene, followed by naphthalene and phenanthrene, serves as the primary tar products. Higher temperature promotes tar reduction, especially under O2/H2O condition. Moreover, soot yield under the O2/H2O condition is less than that under the O2/CO2 condition owing to weaker hydrogen abstraction acetylene addition route. Soot yield decreases with the temperature rises. This work provides valuable insights and guidance for the reduction of tar and soot in the two-stage entrained flow coal gasifier under oxy-fuel atmospheres.

DOI： 10.20550/jiesekitanronbun.60.0_4