THERMAL SCIENCE

International Scientific Journal

IMPROVING DESIGN AND OPERATING PARAMETERS OF THE RECUPERATOR FOR WASTE HEAT RECOVERY FROM ROTARY KILNS

ABSTRACT
Depending on their applications, heat losses from the shells of rotary kilns account for 3-25% of the total heat input. Over the hottest zone of the kiln shell, an annular duct with a variable diameter is formed. Two air streams entering the annulus at both ends flow to a common extraction point to receive the thermal power equal to the ambient heat loss of the bare kiln. The design does not require airtightness, utilizes the entire heat loss, and by the variation of the air-flow can be used over the kilns with variable operating parameters (±20% heat loss), which show similar surface temperature patterns. The main disadvantage of the design is the approaching of the surfaces of the kiln and the recuperator at the outlet of preheated air. This means that for a given heat loss and a surface temperature pattern, the rotational eccentricity of the kiln shell is the most influencing parameter that defines the air preheating temperature and the efficiency of the recuperator. To solve the problem, four redesigns with: double annuluses, the usage of radiation fins, air addition, and a combination of two basic designs are analyzed by the use of analytical and CFD models. From the listed redesigns: first could be used only to prevent overheating, second has a modest positive effect, third should be applied in combination with fourth.
KEYWORDS
PAPER SUBMITTED: 2021-04-10
PAPER REVISED: 2021-07-12
PAPER ACCEPTED: 2021-07-14
PUBLISHED ONLINE: 2021-07-31
DOI REFERENCE: https://doi.org/10.2298/TSCI210410239S
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2022, VOLUME 26, ISSUE Issue 1, PAGES [717 - 734]
REFERENCES
  1. Karamarković, V., et al., Recuperator for waste heat recovery from rotary kilns, Appl. Therm. Eng, 54 (2013), pp. 470-480
  2. Vijayan, S.N., Sendhilkumar , S., Industrial Applications of Rotary Kiln in Various Sectors - A Review, Int. J. Eng. Innov. Res. 3 (2014), pp. 342-345
  3. Golewski, G.L., Energy savings associated with the use of fly ash and nanoadditives in the cement composition, Energies 2020, 13(9), 2184, pp. 1-20
  4. U.S.G. Survey, National Minerals Information Center, (n.d.). www.usgs.gov/centers/nmic/mineral-commodity-summaries
  5. Caputo, A.C., et al., Performance modeling of radiant heat recovery exchangers for rotary kilns, Appl. Therm. Eng. 31 (2011), pp. 2578-2589
  6. Chakrabati, B., Investigations on heat loss through the kilne shell in magnesite dead burning process: a case study., Appl. Therm. Eng. 22 (2002) , pp. 1339-1345
  7. Sadighi Sepehr, A.A., Mansoor, S., Rotary cement kiln coating estimator: Integrated modelling of kiln with shell temperature measurement, Can. Jouranl Chem. Eng. 89 (2011) 116-125
  8. Engin, T., Ari, V., Energy auditing and recovery for dry type cement rotary kiln systems - a case study, Energy Convers. Manag. 46 (2005) , pp. 551-562
  9. Kabir, G., et al., Energy audit and conservation opportunities for pyroprocessing unit of a typical dry process cement plant, Energy. 35 (2010) , pp. 1237-1243
  10. Luo, Q., et al., A Thermoelectric Waste-Heat-Recovery System for Portland Cement Rotary Kilns, J. Electron. Mater. 44 (2015) , pp. 1750-1762
  11. Mirhosseini, M., et al., Power optimization and economic evaluation of thermoelectric waste heat recovery system around a rotary cement kiln, J. Clean. Prod. 232 (2019) , pp. 1321-1334
  12. Mittal, A., Rakshit, D., Energy audit and waste heat recovery from kiln hot shell surface of a cement plant, Therm. Sci. Eng. Prog. 19 (2020) 100599
  13. Du, W.J., et al., Experiments on novel heat recovery systems on rotary kilns, Appl. Therm. Eng. 139 (2018) , pp. 535-541
  14. Yin, Q., et al., Optimization design and economic analyses of heat recovery exchangers on rotary kilns, Appl. Energy. 180 (2016), pp. 743-756
  15. Yin, Q., et al., Design requirements and performance optimization of waste heat recovery systems for rotary kilns, Int. J. Heat Mass Transf. 93 (2016) , pp. 1-8
  16. Akram, N., et al., Improved waste heat recovery through surface of kiln using phase change material, Therm. Sci. 22 (2018), pp. 1089-1098
  17. Zheng, K., et al., Rotary kiln cylinder deformation measurement and feature extraction based on EMD method, Eng. Lett. 23 (2015), pp. 283-291
  18. Mirzakhani, M.A., et al., Energy benchmarking of cement industry, based on Process Integration concepts, Energy. 130 (2017), pp. 382-391
  19. Churchill W, C.H., Correlating equations for laminar and turbulent free convection from a horizontal cylinder, Int. J. Heat Mass Transf. 18 (1975), pp. 1049-1053
  20. Werner Kast, H.K., Heat Transfer by Free Convection: External Flows, in: VDI Heat Atlas, 2nd ed., Springer, Heidelberg, 2010: pp. 667-672
  21. Kabelac, D., Vortmeyer, S., Radiation of Surfaces, in: VDI Heat Atlas, Heidelberg, 2010: pp. 947-959
  22. Faculty of Mechanical Engineering in Kraljevo, The impact of the usage of enriched air for combustion on kiln production. (in Serbian), 2012
  23. Gnielinski, V., Forced Convection, in: VDI Heat Atlas, 2nd ed., Heidelberg, 2010: pp. 691-699
  24. Gnielinski, V., New equations for heat and mass transfer in turbulent pipe and channel flow, Int. J. Chem. Eng. 16 (1976), pp. 359-368
  25. Janna, S.W., Engineering Heat Transfer 3rd Edition, 2009
  26. Vormeyer, K.S., Dieter, View Factors, in: VDI Heat Atlas, Heidelberg, 2010: pp. 961-978
  27. Knežević, D. S., et al., Radiant recuperator modeling and design, Therm. Sci. 21 (2017), pp. 1119-1134
  28. Kleiber, M., Joh, R., Calculation Methods for Thermopysical Properties, in: VDI Heat Atlas, 2nd ed., Springer, Heidelberg, Germany, 2010: pp. 121-152
  29. Kleiber, M., Joh, R., Properties of Selected Importanat Pure Substances, in: VDI Heat Atlas, 2nd ed., Heidelberg, Germany, 2010: pp. 153-299
  30. Kleiber, M., Joh, R., Properties of Pure Fluid Substances, in: VDI Heat Atlas, 2nd ed., Heidelberg, Germany, 2010: pp. 301-417
  31. Sofialidis, D., Boundary Conditions & Solver Settings, (2013) 61. events.prace-ri.eu/event/156/contributions/6/attachments/65/89/Fluent-Intro_14.5_L02_BoundaryConditionsSolverSettings.pdf
  32. Moffat, R.J., Describing the uncertainties in experimental results, Exp. Therm. Fluid Sci. 1 (1988), pp. 3-17
  33. E. ToolBox, Velocity Classification of Ventilation Ducts, (2003). www.engineeringtoolbox.com/velocities-ventilation-ducts-d_211.html

© 2022 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence