Elucidation of spray combustion of liquid ammonia and ammonia water at high temperatures and pressures

• Project/Area Number: 20H02078
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Tohoku University
• Principal Investigator: Kobayashi Hideaki 東北大学, 流体科学研究所, 教授 (30170343)
• Co-Investigator(Kenkyū-buntansha): 早川 晃弘 東北大学, 流体科学研究所, 准教授 (90709156)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥16,900,000 (Direct Cost: ¥13,000,000、Indirect Cost: ¥3,900,000); Fiscal Year 2022: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2021: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000); Fiscal Year 2020: ¥10,270,000 (Direct Cost: ¥7,900,000、Indirect Cost: ¥2,370,000)
• Keywords: アンモニア燃焼 / 噴霧燃焼 / 噴霧構造 / フラッシュ噴霧 / スワール燃焼器 / 層流燃焼速度 / アンモニア水 / 乱流燃焼 / 高圧燃焼 / 液体アンモニア燃焼 / アンモニア水溶液 / 液体アンモニア

Outline of Research at the Start

ガスタービン燃焼を想定した10 気圧、500 Kまでの高温高圧環境において、１）液体アンモニアならびにアンモニ水溶液を噴射させた場合の噴霧構造と噴霧粒径の計測、２）液体アンモニア噴霧火炎およびアンモニア水溶液噴霧火炎の安定限界測定、３）排出ガス中のNOxおよび未燃アンモニア濃度計測、４）OH-PLIF、NH-PLIF同時計測による高圧乱流アンモニア噴霧火炎、およびアンモニア水溶液噴霧火炎の火炎構造解明を行う。これらにより、燃料アンモニアのガスタービンへの応用に資する。

Outline of Final Research Achievements

When the premixture is preheated to 500 K, the laminar burning velocity of ammonia/air flame increases to 20 cm/s, but is reduced by nearly 50% with 30% mass-fraction ammonia water/air flame. Liquid ammonia spray does not widen the spray angle due to flashing spray formation. The ammonia water spray has characteristics intermediate between water and liquid ammonia spray and widens the spray angle. The features of liquid ammonia spray were reproduced by numerical analysis using OpenForm. Spraying liquid ammonia into an atmospheric pressure environment lowers the temperature on the central axis to about -55°C. The specific volume of the gas phase decreases, and thus the droplets are concentrated near the central axis. By preheating the suppled air to compensate for the lower temperature of ammonia spray, the liquid ammonia spray flame was successfully stabilized using a swirl burner.

Academic Significance and Societal Importance of the Research Achievements

気候変動問題への対応としてエネルギー分野の脱炭素化は不可欠であり、カーボンフリー燃料である水素の技術開発が進められているが、特に海外から大量に輸送するコスト問題が大きくなかなか普及しない。一方、アンモニアは水素と同じくカーボンフリー燃料であるが、輸送や貯蔵のコストが低く、その技術開発が急ピッチで進められている。特に利用技術において、アンモニアを液体のまま燃料として利用できれば、蒸発に要するエネルギーが不要で、ガスタービン発電では電力要求変動にも迅速に対応できる。そのため、液体アンモニア燃焼の研究開発が望まれており、本研究はその要求に応えるとともに、燃焼科学に進歩に資するものである。

Research Products

• [Journal Article] Effects of Water Vapor Dilution on the Laminar Burning Velocity and Markstein Length of Ammonia/Water Vapor/Air Premixed Laminar Flames (2022)
  • Author(s): M. Hayashi, A. Hayakawa, T. Kudo, H. Kobayashi
  • Journal Title: Energy and Fuels Volume: 36 Issue: 19 Pages: 12341-12349
  • DOI: 10.1021/acs.energyfuels.2c01749
  • Peer Reviewed
• [Journal Article] Flame stability and emissions characteristics of liquid ammonia spray co-fired with methane in a single stage swirl combustor (2021)
  • Author(s): E. C. Okafor, H. Yamashita, A. Hayakawa, K. D. K. A. Somarathne, T. Kudo, T. Tsujimura, M. Uchida, S. Ito, H. Kobayashi
  • Journal Title: Fuel Volume: 287 Pages: 119433-11943
  • DOI: 10.1016/j.fuel.2020.119433
  • Peer Reviewed / Open Access
• [Presentation] Study of the effects of injection temperature and nozzle geometry on liquid ammonia spray characteristics and flame stabilization (2022)
  • Author(s): S. Colson, H. Yamashita, T. Kudo, A. Hayakawa, H. Kobayashi
  • Organizer: 39th International Symposium on Combustion
  • Int'l Joint Research
• [Presentation] Study of the effects of spray shape on flame stability limits of liquid ammonia spray combustion (2022)
  • Author(s): H. Yamashita, K. Oku, S. Colson, K.D.K.A. Somarathne, E.C. Okafor, O. Kurata, T. Tsujimura, S. Ito, M. Uchida, T. Kudo, A. Hayakawa, H. Kobayashi
  • Organizer: 39th International Symposium on Combustion
  • Int'l Joint Research
• [Presentation] Emission Characteristics of Liquid Ammonia and Gaseous Ammonia Flames Co-fired with Gaseous Hydrogen in a Gas Turbine-like Combustor at Moderately High Pressure (2022)
  • Author(s): K.D.K.A. Somarathne, H. Yamashita, S. Colson, A. Hayakawa, T. Kudo, H. Kobayashi
  • Organizer: 19th International Conference on Flow Dynamics
  • Int'l Joint Research
• [Presentation] 旋回流燃焼器における液体アンモニア噴霧燃焼の保炎可能範囲にメタンおよび水素添加が与える影響 (2022)
  • Author(s): 山下 裕史, 奥 航平, S. Colson, K.D.K.A. Somarathne, E.C. Okafor, 倉田 修, 辻村 拓, 伊藤 慎太朗, 内田 正宏, 工藤 琢, 早川 晃弘, 小林 秀昭
  • Organizer: 第60回燃焼シンポジウム
• [Presentation] Ammonia Combustion for Gas Turbine Power Generation (2022)
  • Author(s): H. Kobayashi
  • Organizer: 19th International Conference on Flow Dynamics
  • Int'l Joint Research / Invited
• [Presentation] Liquid Ammonia Spray Combustion and Emission Characteristics with Gaseous Hydrogen/air Co-firing (2021)
  • Author(s): K. D. K. A. Somarathne, H. Yamashita, S. Colson, A. Hayakawa, E. C. Okafor, H. Kobayashi, T. Kudo
  • Organizer: 13th Asia-Pacific Conference on Combustion 2021
  • Int'l Joint Research
• [Presentation] Hydrogen and Ammonia Combustion - Japan’s Challenge and Technical Progress - (2021)
  • Author(s): H. Kobayashi
  • Organizer: The Australian Combustion Symposium 2021
  • Int'l Joint Research / Invited
• [Presentation] Stability and Emissions Characteristics of Liquid Ammonia Spray Combustion in a Swirling Flow (2021)
  • Author(s): H. Yamashita, E. C. Okafor, A. Hayakawa, T. Tsujimura, S. Ito, M. Uchida, T. Kudo, H. Kobayashi
  • Organizer: European Power to Ammonia Conference 2021
  • Int'l Joint Research
• [Presentation] Liquid Ammonia Spray Characteristics Using a Hollow Cone Nozzle at Various Ambient Pressures (2021)
  • Author(s): K.D.K.A. Somarathne, H. Yamashita, S. Colson, A. Hayakawa, H. Kobayashi
  • Organizer: Eighteenth International Conference on Flow Dynamics (ICFD 2021)
  • Int'l Joint Research
• [Presentation] SLIPIによる液体アンモニア噴霧構造の可視化 (2021)
  • Author(s): 山下 裕史, E.C. Okafor, S. Colson, K.D.K.A. Somarathne, 辻村 拓，伊藤 慎太朗，内田 正宏，工藤 琢，早川 晃弘，小林 秀昭
  • Organizer: 熱工学コンファレンス2021
• [Presentation] Investigation of the Combustion of Liquid Ammonia Spray in a Single Stage Swirl Combustor (2020)
  • Author(s): E. C. Okafor，Hirofumi Yamashita，Akihiro Hayakawa，K. D. K. A. Somarathne，T. Kudo，T. Tsujimura，M. Uchida，Shintaro Ito，H. Kobayashi
  • Organizer: 第58回燃焼シンポジウム
• [Presentation] Liquid Ammonia Spray Combustion in Two-Stage Gas Turbine Combustors (2020)
  • Author(s): E.C. Okafor , O. Kurata, H. Yamashita, T. Inoue, T. Tsujimura, N. Iki, A. Hayakawa, M. Uchida, S. Ito, H. Kobayashi
  • Organizer: The Twentieth International Conference on Flow Dynamics (ICFD2020)
  • Invited
• [Presentation] Stability and Emissions Characteristics of Liquid Ammonia Spray Flames Co-fired with Methane in a Swirling Flow (2020)
  • Author(s): H. Yamashita , E. C. Okafor, A. Hayakawa, T. Tsujimura, S. Ito, M. Uchida, T. Kudo, H. Kobayashi
  • Organizer: The Twentieth International Conference on Flow Dynamics (ICFD2020)