Oxygen enrichment combustion of digestion gases: micro flames due to exhaust heat recirculation and safety control based on international safety standards

• Project/Area Number: 15K05821
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Nagaoka University of Technology
• Principal Investigator: Kadowaki Satoshi 長岡技術科学大学, 技術経営研究科, 教授 (20185888)
• Co-Investigator(Kenkyū-buntansha): 勝身 俊之 長岡技術科学大学, 工学研究科, 准教授 (60601416)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2016: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2015: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 熱工学 / マイクロ火炎 / 消火ガス / 酸素富化 / 国際安全規格 / 消化ガス

Outline of Final Research Achievements

Oxygen enrichment combustion of digestion gases in micro counterflow burners was investigated. Diffusion flames in the gap of burners were treated, and the flame thickness which depended on the distance between burners, inner diameter of burner tubes, flow rate of gases and digestion gas component was measured. It was shown that the flame thickness decreased monotonically as the gap distance decreased and that diffusion flames became thinner when the methane concentration in digestion gas became lower. Increased flame thickness was observed at large gas flow rate, and diffusion flames were found in smaller burner distance at larger inner diameter. The flame thickness decreased as the flame stretch became stronger, i.e. the thickness varied inversely with the square root of stretch rate. In addition, the normalized flame thickness depended only on the flame stretch rate.

Academic Significance and Societal Importance of the Research Achievements

地球環境に配慮した低炭素社会を構築し，持続可能な社会を実現する上で，未利用となっている多量の消化ガスに注目が集まっている．低カロリーである消化ガスの利用では，酸化剤に酸素を富化して燃焼させる酸素富化燃焼が有効である．これに加えて，排熱再循環を利用するエクセルギー保持燃焼を適用することにより，消化ガスのエネルギーを高効率で取り出すことができる．本研究では，消化ガスの酸素富化燃焼を取り扱い，現象のメカニズムを精査し，多くの知見を得ている．これらの知見は，消化ガスの有効利用に直接繋がるものであり，低炭素社会の構築に貢献する．そして，持続可能な社会を実現する手法の一つとなっている．

Research Products

• [Journal Article] Oxygen combustion of CH₄-CO₂ mixture in a small-scale counterflow burner (2018)
  • Author(s): Kadowaki, S., Kohatsu, K., Uehara, K., Katsumi, T., Thwe Thwe Aung, and Suzuki, M.
  • Journal Title: Journal of Thermal Science and Technology Volume: 13 Issue: 2 Pages: JTST0021-JTST0021
  • DOI: 10.1299/jtst.2018jtst0021
  • NAID: 130007418219
  • ISSN: 1880-5566
  • Peer Reviewed / Open Access
• [Journal Article] Micro counterflow diffusion flames: Oxy-fuel combustion of methane (2016)
  • Author(s): Satoshi KADOWAKI, Ryutaro NUMATA, Yusuke HASHIMOTO, Toshiyuki KATSUMI
  • Journal Title: Mechanical Engineering Letters Volume: 2 Issue: 0 Pages: 16-00170-16-00170
  • DOI: 10.1299/mel.16-00170
  • NAID: 130005138484
  • ISSN: 2189-5236
  • Peer Reviewed / Open Access
• [Presentation] Micro methane-oxygen counterflow diffusion flames: effects of gravity on flame structures (2017)
  • Author(s): Kadowaki, S.
  • Organizer: The 17th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications
  • Int'l Joint Research
• [Presentation] MICRO BIOGAS-OXYGEN DIFFUSION FLAMES IN COUNTERFLOW BURNERS (2016)
  • Author(s): S. Kadowaki, R. Numata, Y. Hashimoto, and T. Katsumi
  • Organizer: First Pacific Rim Thermal Engineering Conference
  • Place of Presentation: 米国
  • Year and Date: 2016-03-13
  • Int'l Joint Research