Implementation and economic analysis of MILD combustion in a lab-scale boiler

Document Type : Original Article

Authors

1 Energy Systems Division, Mechanical and Energy Engineering Department, Shahid Beheshti University

2 Optimization of Energy Systems Lab., Mechanical and Energy Engineering Department, Shahid Beheshti University.

3 Head of Energy Systems Division, Mechanical and Energy Engineering Department, Shahid Beheshti University

Abstract

Implementation and economic analysis of MILD combustion in a
lab-scale boiler
 
Ghasem Khabbazian1, Javad Aminian2* and Ramin Haghighi Khoshkhou3
1- PhD student, Department of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran
2- Assistant Professor, Department of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran
3- Associate Professor, Department of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran
*Corresponding author
 (Received: 2018.11.28, Received in revised form: 2019.1.20, Accepted: 2019.2.5)
 
In this paper design and implementation of a MILD combustion system in a 100 kW boiler was investigated from technical and economic viewpoints. The main objective of this study is determination of the factors affecting the stability of the combustion regimes in a typical domestic utility boiler, leading in simultaneous thermal efficiency enhancement and emission reduction. In particular, the so-called MILD combustion was established in a conventional boiler equipped with an ordinary premixed burner without requiring to replace with expensive modern burners. In the experiments, the qualitative and quantitative features of MILD regime such as uniform temperature distribution in the combustion chamber, volumetric and weakened flame, increased efficiency and decreased NOx emissions were achieved. The results showed a 10% fuel saving as well as 13% reduction in NOx. In addition, the economic evaluation of presented method to establish MILD combustion was performed using the net present value and payback period measures. The analysis results suggest that investment in the MILD system retrofitting plan is cost-effective and economically attractive in similar cases.
 
 
 
 

Keywords

References

  1. J. A. Wünning and J. G. Wünning, "Flameless oxidation to reduce thermal NO-formation," Progress in Energy Combustion Science, 23, 1997, pp. 81-94.
  2. H. Tsuji, A. K. Gupta, T. Hasegawa, M. Katsuki, K. Kishimoto and M. Morita, High temperature air combustion: From Energy Conservation to Pollution Reduction, CRC Press, Flurida, 2002.
  3. [3] A. Cavaliere and M. deJoanon, "Mild combustion," Progress in Energy and Combustion Science, 30, 2004, pp. 329–366.
  4. [4] P. Li, J. Mi, B. B. Dally, R. A. Craig and F. Wang, "Premixed moderate or intense low-oxygen dilution (MILD) combustion from a single jet burner in a laboratory-scale furnace," Energy & Fuels, 25, 2011, pp. 2782–2793.
  5. A. Milani and J. Wünning, "What is flameless combustion?," IRIF online combustion handbook, http://www.handbook.ifrf.net/, Accessed 25/02/2018.
  6. [6] Y. Tu, K. Su, H. Liu, Z. Wang, Y. Xie, C. Zheng and W. Li, "MILD combustion of natural gas using low preheating temperature air in an industrial furnace," Fuel Processing Technology, 156, 2017, pp.72–81.
  7. J. G. Wünning and A. Milani, Flameless burners, In: C. E. Baukal, editor, Handbook of industrial combustion testing, Taylor and Francis Group, Flurida, 2011.
  8. J. Bond, Sources of ignition, Butterworth-Heinemann Ltd, Oxfoord, Oxfoord, 1991.
  9. F. Norman, Influence of process conditions on the auto-ignition temperature of gas mixtures, PhD Thesis, Mechanical Engineering Department, Leuven University, 2008.
  10. A. Mardani, S. Tabejamaat and M. Ghamari, "Numerical study of influence of molecular diffusion in the Mild combustion regime," Combustion Theory and Modelling, 14, NO. 5, 2010, pp. 747-774.
  11. A. Mardani, S. Tabejamaat and S. Hassanpour, "Numerical study of CO and CO2 formation in CH4/H2 blended flame under MILD condition,"Combustion and flame, 160, NO. 9, 2013, pp. 1636-1649.
  12. A. Mardani and S. Tabejamaat, "Effect of hydrogen on hydrogen–methane turbulent non-premixed flame under MILD condition," International Journal of Hydrogen Energy, 35, NO. 20, 2010, pp. 11324-11331.
  13. A. Mardani and S. Tabejamaat, "NOx formation in h2-ch4 blended flame under MILD conditions," Combustion Science and Technology, 184, NO. 7-8, 2012, pp. 995-1010.
  14. B. Kashir, S. Tabejamaat and M. Baig mohammadi, "Experimental study on propane/oxygen and natural gas/oxygen laminar diffusion flames in diluting and preheating conditions," Thermal Science, 16, NO. 4, 2012, pp. 1043-1053.
  15. S. Orsino, R. Weber  and U. Bollettini, "Numerical simulation of combustion of natural gas with high temperature air," Combustion Science and Technology,170, 2001, pp. 1-34.
  16. B. B. Dally, A. N. Karpetis and R. S. Barlow, "Structure of turbulent non-premixed jet flames in a diluted hot coflow," Proceedings of the Combustion Institute, 29, 2002, pp.1147-1154.
  17. A. Cavigiolo, M. A. Galbiati, A. Effuggi, D. Gelosa and R. Rota, "MILD combustion in a laboratory-scale apparatus," Combustion Science and Technology, 175, 2003, pp. 1347-1367.
  18. G. G. Szegö, B. B. Dally and G. J. Nathan, "Operational characteristics of a parallel jet MILD combustion burner system," Combustion and Flame, 156, 2009, pp. 429-438.
  19. A. S. Veríssimo, A. M. A. Rocha, P. J. Coelho and M. Costa, "Experimental and numerical investigation of the influence of the air preheating temperature on the performance of a small-scale Mild combustor," Combustion Science and Technology, 187, 2015, pp. 1724-1741.
  20. A. Rebola, M. Costa and P. J. Coelho, "Experimental evaluation of the performance of a flameless combustor," Applied Thermal Engineering, 50, 2013, pp. 805-815.
  21. WS Co., http://www.flox.com/en/prod/REKUMAT.html, Accessed 12/02/2018.
  22. NIPPON steel and SUMITOMO metal group, https://www.eng.nssmc.com/english/whatwedo/steelplants/rolling/ regenerative_burner_type_reheating_furnace/, Accessed 21/01/2018.
  23. Mcchi-Sofinter group, https://www.macchiboiler.it/en/research-development/burners/, Accessed 08/01/2018.
  24. M. Krarti, Energy audit of building systems: an engineering approach, 2nd edition, CRC press, Flurida, 2011.
  25. National Iranian Gas Company, http://www.nigc.ir, Accessed 21/01/2018
  26. M. Mörtberg, W. Blasiak and A. K. Gupta, "Combustion of normal and low calorific fuels in high temperature and oxygen deficient environment," Combustion Science and Technology, 178, 2006, pp. 1345–1372.
  27. İ. B. Özdemir and N. Peter, "Characteristics of the reaction zone in a combustion operating at MILD combustion," Experiments in Fluids, 30, 2001, pp. 683–95.
  28. Z. Zhang, X. Li, L. Zhang, C. Luo, Z. Mao, Y. Xu, J. Liu, G. Liu and C. Zheng, "Numerical investigation of the effects of different injection parameters on Damköhler number in the natural gas MILD combustion," Fuel, 237, 2019, pp. 60–70.
  29. S. R. Turns, An introduction to combustion: concepts and applications, 2nd edition, McGraw Hill, Singapore, 2000.
  30. B. Yu, S. Kum, C. Lee and S. Lee, "Effects of exhaust gas recirculation on the thermal efficiency and combustion characteristics for premixed combustion system," Energy, 49, 2013, pp. 375-383.
  31. B. Yu, S. Kum, C. Lee and S. Lee, "Study on the combustion characteristics of a premixed combustion system with exhaust gas recirculation," Energy, 61, 2013, pp. 345-353.

 

 

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History

  • Receive Date: 28 November 2018
  • Revise Date: 20 January 2019
  • Accept Date: 05 February 2019

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