Journal of ILASS-Korea (한국분무공학회지)

Institute for Liquid Atomization and Spray Systems-Korea (한국분무공학회)
권호 표지
DOI QR코드

DOI QR Code

Establishing the Models for Optimized Design of Water Injection in Boilers with Waste-heat-recovery System

가습연소 폐열회수 보일러의 물분사 설계모델 구축에 관한 연구

  • Received : 2021.06.07
  • Accepted : 2021.06.16
  • Published : 2021.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

Keywords

Acknowledgement

본 논문은 2020년도 산업통상자원부 및 산업기술평가관리원(KEIT) 연구비 지원에 의한 연구임(과제번호: 20010957)

References

  1. C. E. Lee, B. J. Yu, D. H. Kim and S. H. Jang, "Analysis of the thermodynamic performance of a waste heat recovery boiler with additional water spray onto combustion air stream", Applied Thermal Engineering, Vol. 135, 2018, pp. 197~205. https://doi.org/10.1016/j.applthermaleng.2017.11.060
  2. C. E. Lee and D. H. Kim, "Heat recovery boilers with water spray. Part I: Thermodynamic analysis validation and boiler practicality", Thermal Science and Engineering Progress, Vol. 18, 2020, pp. 100491. https://doi.org/10.1016/j.tsep.2020.100491
  3. D. H. Kim, T. J. Park, C. E. Lee, "Heat recovery boilers with water spray: Part II: Parametric analysis and optimization of design specifications", Thermal Science and Engineering Progress, Vol. 19, 2020, pp. 100643. https://doi.org/10.1016/j.tsep.2020.100643
  4. D. G. Pugh, P. J. Bowen, R. Marsh, A.P. Crayfond, J. Runyon, S. Morris, A. Valera-Medina and A. Giles "Dissociative influence of H2O vapour/spray on lean blow off and NOx reduction of heavily carbonaceous syngas swirling flames", Combustion and Flame, Vol. 177, 2017, pp. 37~48. https://doi.org/10.1016/j.combustflame.2016.11.010
  5. J. Kuck, "Efficiency of vapour-pump-equipped condensing boilers", Applied Thermal Engineering, Vol. 16, 1996, pp. 233~244. https://doi.org/10.1016/1359-4311(95)00067-4
  6. M. J. Moran, H. N. Shapiro, D. D. Boettner and M. B. Bailey, "Principles of Engineering Thermodynamics", Global Edition, Wiley, 2018.
  7. S. M. Frolov, F. S. Frolov and B. Basara, "Simple model of transient drop vaporization", Journal of Russian Laser Reasearch Volume, Vol. 27, 2006, pp. 562~574. https://doi.org/10.1007/s10946-006-0035-7
  8. A. H. Lefevre and V. G. McDonell, "Atomization and Sprays"Taylor & Francis Group, LLC., 2017.
  9. O. E. Ruiz and W. Z. Black, "Evaporation of water doplets placed on a heated horizontal surface", Journal of Heat Transfer, Vol. 124, 2002, pp. 854~863. https://doi.org/10.1115/1.1494092