Updated on 2023/10/01


ISOGAI, Hirotaka
Faculty of Science and Engineering, Environmental Research Institute
Job title
Junior Researcher(Assistant Professor)
Doctor of Engineering ( 2023.03 Waseda University )

Research Experience

  • 2023.04

    Waseda University   Environmental Research Institute   Junior Researcher

Education Background

  • 2020.04

    Waseda University   Graduate School of Creative Science and Engineering  

    Doctral course

  • 2018.04

    Waseda University   Graduate School of Creative Science and Engineering  

    Master course

  • 2014.04

    Waseda University   School of Creative Science and Engineering  

Professional Memberships

  • 2018.06

    The Society of Chemical Engineers, Japan

  • 2018.02

    The Japan Society of Mechanical Engineers

Research Areas

  • Environmental load reduction and remediation   CCS / Transport phenomena and unit operations

Research Interests

  • Chemical absorption

  • CO₂ capture

  • Gas absorption


  • 日本機械学会関東支部学生奨励賞

    2020.03   日本機械学会  

    Winner: 磯谷浩孝

  • Hatakeyama Award

    2018.03   The Japan Society of Mechanical Engineers  

    Winner: Hirotaka Isogai



  • Exploration of optimal operating conditions for a natural gas combined-cycle power plant integrated with post-combustion CO<inf>2</inf> capture using 2-amino-2-methyl-1-propanol/piperazine considering the propagation effect

    Hirotaka Isogai, Takao Nakagaki

    International Journal of Greenhouse Gas Control   122  2023.01

     View Summary

    Integrating post-combustion CO2 capture (PCC) into thermal power plants can reduce CO2 emissions but results in a significant decrease in net thermal efficiency. Optimizing PCC operating conditions, such as the ratio of the liquid flow rate to the gas flow rate (L/G) and stripper bottom temperature, reduces the net efficiency penalty. However, previous studies partially neglected the propagation effects of altered operating conditions on process performance, such as the effect of altered L/G and resultant change in fluid velocity on the heat transfer and pressure drop in the rich and lean solution heat exchanger. This study simulated amine-based PCC integrated into a natural gas combined cycle and explored optimal operating conditions comprehensively considering the propagation effects. The net efficiency penalty was minimized to 6.02%-pts. at a stripper bottom temperature of 130 °C and L/G of 0.82 for PCC operation with CO2 compression. Meanwhile, neglecting propagation effects of altered L/G led to underestimation of the efficiency penalty and erroneous determination of optimal operating conditions. The system evaluation methods suggested in this paper contribute to correctly optimizing PCC operating conditions and can be broadly applied to amine-based PCC studies employing novel amine solutions or process modifications.



  • Mechanistic analysis of post-combustion CO<inf>2</inf> capture performance during amine degradation

    Hirotaka Isogai, Takao Nakagaki

    International Journal of Greenhouse Gas Control   114  2022.02

     View Summary

    Degradation of amine is often regarded as a major problem for amine-based post-combustion CO2 capture. However, the observed regeneration energy in long-term pilot plant operations does not necessarily increase, regardless of the accumulation of degradation compounds. This paper provides a mechanistic explanation for this seemingly paradoxical behavior by focusing on the influence of heat stable salts and the CO2 loading range on solution properties. Post-combustion CO2 capture using degraded amine solution was simulated in Aspen Plus®, and the influence of heat stable salts on CO2 loading, solution properties, and regeneration energy were analyzed. Results indicate that the alteration of the operational CO2 loading range and the physical properties of heat stable salts themselves cause changes in solution properties that dictate overall energy consumption, such as viscosity, vapor liquid equilibrium, and specific heat capacity. These effects often offset each other to some extent, thereby obscuring the influence of individual factors on regeneration energy. These counteracting effects can largely explain the seemingly paradoxical behavior of post-combustion capture maintaining relatively low energy consumption even when amine degradation proceeds.



  • Cost estimation of CCS integration into thermal power plants in Japan

    Hirotaka Isogai, Corey Adam Myers, Takao Nakagaki


     View Summary

    Carbon capture and storage (CCS) is an important technical option to reduce CO2 emissions and chemical absorption by amine solutions is the most mature post-combustion carbon capture technology. Reducing costs is critical to accelerate large-scale deployment of CCS. Cost estimates of CCS vary markedly depending on the CO2 capture performance, CO2 transport method, characteristics of CO2 storage site, and the like. This study estimated the cost of CCS by amine-based CO2 capture integration into thermal power plants in Japan. The thermal power plant system with CO2 capture process was modeled on a process simulator, and CO2 capture cost was calculated based on the modelling results. The CCS chain feasible in Japan at this time is transportation by ship and injection onshore into subseafloor storage sites. Transport cost was estimated via bottom-up analysis of each transportation sub-process. Injection cost was based on the values reported by the Tomakomai demonstration project. In total, transport and storage costs were roughly equivalent to capture costs. Full chain CCS implementation is likely necessary to markedly reduce costs through learning-by-doing.


  • Updated e-NRTL model for high-concentration MEA aqueous solution by regressing thermodynamic experimental data at high temperatures

    Takao Nakagaki, Hirotaka Isogai, Hiroshi Sato, Jun Arakawa

    International Journal of Greenhouse Gas Control   82   117 - 126  2019.03

     View Summary

    Chemical absorption using amine solutions is a promising technology for post combustion CO2 Capture (PCC) from flue gas. Monoethanolamine (MEA) aqueous solution has been used in many projects as a benchmark solution and the experimental and analytical results are available in the literature for diverse operating conditions. Aspen Plus® is a widely used computational simulation software for design of PCC systems including operating conditions. Two example files of rate-based MEA models using electrolyte non-random two liquid (e-NRTL) methods are included in Aspen Plus. Basically, e-NRTL models can provide relatively accurate results by fitting parameters to experimental data within a limited temperature and concentration range. However, there are a non-negligible difference between experimental and calculation results, especially in regard to the vapor-liquid equilibrium (VLE) at high temperatures and high MEA concentrations. This paper updates the e-NRTL model for the solutions with 30 wt% and higher MEA by data regression of the specific heat capacity, the heat of CO2 absorption, and VLE experimental data obtained at high temperatures. Since these thermodynamic properties are mutually dependent and affected by internal model parameters such as activity coefficients, standard enthalpy change of formation of principal ions, all properties in the MEA-H2O-CO2 ternary system that are consistent with the MEA-H2O binary system were fitted by using a combination of the built-in data regression functionality and external spread-sheet software. The updated model more accurately simulates thermodynamic properties of high concentration MEA solutions at high temperatures.





  • Process simulation of post-combustion CO2 capture via chemical absorption

    Hirotaka Isogai  [Invited]

    Presentation date: 2023.09

  • Design of pressurized reaction calorimetry for CO₂ capture based on attribution analysis of measurement deviation

    Koki Saito, Hirotaka Isogai, Takao Nakagaki

    International Conference on Power Engineering 2023 

    Presentation date: 2023.05

  • CO₂ Absorption Rate of a 2-Amino-2-Methyl-1-Propanol/Piperazine Solution Containing Degradation Compounds during Post-combustion CO₂ Capture

    Hirotaka Isogai, Takumi Saito, Takao Nakagaki

    16th International Conference on Greenhouse Gas Control Technologies GHGT-16 

    Presentation date: 2022.10

  • アミン吸収液の劣化による液特性変化を考慮したCO₂分離回収の運転特性予測

    齊藤拓海, 磯谷 浩孝, 石原学美, 中垣 隆雄


    Presentation date: 2022.09

  • Cost estimation of CCS integration into thermal power plants in Japan

    Hirotaka Isogai, Corey Adam Myers, Takao Nakagaki

    International Conference on Power Engineering-2021 

    Presentation date: 2021.10

  • Cost estimation of CCS integration into NGCC in Japan

    Hirotaka Isogai, Corey Adam Myers, Takao Nakagaki

    IEAGHG 6th Post Combustion Capture Conference 

    Presentation date: 2021.10

  • 固液分離プロセスを適用したCO₂分離回収法における炭酸塩析出条件の実験的探索

    毛孟傑, 中垣隆雄, 磯谷浩孝, 松井瑛尚


    Presentation date: 2021.09

  • アミン吸収液の劣化による熱力学的特性変化を考慮したCO₂分離回収の運転特性予測

    河原塚康太, 中垣隆雄, 磯谷浩孝, 丁ヨウ


    Presentation date: 2021.09

  • 化学吸収法における液特性と操作条件のCO₂分離回収性能に与える影響評価

    磯谷浩孝, 中垣隆雄


    Presentation date: 2021.07

  • Cost analysis of CO₂ transportation in CCS deployed in Japan

    Hirotaka Isogai, Corey Adam Myers, Takao Nakagaki, Ken Myoi, Junichi Shimizu

    Japan Geoscience Union Meeting 2021 

    Presentation date: 2021.05

  • Holistic Approach to Understanding and Managing Amine Degradation during Post-combustion CO₂ Capture Operation

    Hirotaka Isogai, Takumi Endo, Kenji Takano, Takao Nakagaki

    15th International Conference on Greenhouse Gas Control Technologies GHGT-15 

    Presentation date: 2021.03

  • CO₂吸収塔脱炭酸ガスの微量アミン蒸気回収に向けた基礎データの実験的取得

    有川大悟, 長谷川大介, 中村浩太郎, 磯谷浩孝, 中垣隆雄, 村岡大悟, 藤田己思人, 北村英夫


    Presentation date: 2020.09

  • 化学吸収液のCO₂吸収速度計測のための濡れ壁塔の設計

    石原学美, 磯谷浩孝, 中垣隆雄


    Presentation date: 2020.03

  • 電解質NRTLモデルパラメータの修正によるCO₂分離回収の運転条件の探索範囲拡大

    磯谷浩孝, 尾関啓, 中垣隆雄, 荒川純, 崔原栄


    Presentation date: 2018.09

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