Fluidized-Bed Combustion of Biomass with Elevated Alkali Content: A Comparative Study between Two Alternative Bed Materials

Authors: P. Ninduangdee, V. I. Kuprianov

Abstract:

Palm kernel shell is an important bioenergy resource in Thailand. However, due to elevated alkali content in biomass ash, this oil palm residue shows high tendency to bed agglomeration in a fluidized-bed combustion system using conventional bed material (silica sand). In this study, palm kernel shell was burned in the conical fluidized-bed combustor (FBC) using alumina and dolomite as alternative bed materials to prevent bed agglomeration. For each bed material, the combustion tests were performed at 45kg/h fuel feed rate with excess air within 20–80%. Experimental results revealed rather weak effects of the bed material type but substantial influence of excess air on the behavior of temperature, O2, CO, CxHy, and NO inside the reactor, as well as on the combustion efficiency and major gaseous emissions of the conical FBC. The optimal level of excess air ensuring high combustion efficiency (about 98.5%) and acceptable level of the emissions was found to be about 40% when using alumina and 60% with dolomite. By using these alternative bed materials, bed agglomeration can be prevented when burning the shell in the proposed conical FBC. However, both bed materials exhibited significant changes in their morphological, physical and chemical properties in the course of the time.

Keywords: Palm kernel shell, fluidized-bed combustion, alternative bed materials, combustion and emission performance, bed agglomeration prevention.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1092048

References:

[1] Office of Agricultural Economics. Agricultural production in Thailand. http://www.oae.go.th/download/prcai/farmcrop/palm52-54.pdf.
[2] Department of Alternative Energy Development and Efficiency. Thailand Alternative Energy Situation 2012. http://www.dede.go.th
[3] J. Werther, M. Saenger, E.U. Hartge, T. Ogada, and Z. Siagi, "Combustion of agricultural residues”, Progress in Energy and Combustion Science, vol. 26, pp. 1–27, 2000.
[4] W. Permchart and V.I. Kouprianov, "Emission performance and combustion efficiency of a conical fluidized-bed combustor firing various biomass fuels”, Bioresource Technology, vol. 92, pp. 83–91, 2004.
[5] A.A. Khan, W. de Jong, P.J. Jansens, and H.Spliethoff, "Biomass combustion in fluidized bed boilers: Potential problems and remedies”, Fuel Processing Technology, vol. 90, pp. 21–50, 2009.
[6] M. Öhman, A. Nordin, B.J. Skrifvars, R. Backman, and M. Hupa, "Bed agglomeration characteristics during fluidized bed combustion of biomass fuels”, Energy & Fuels, vol. 14, pp. 169–178, 2000.
[7] W. Lin, K. Dam-Johanse, and F. Frandsen, "Agglomeration in bio-fuel fired fluidized bed combustors”, Chemical Engineering Journal, vol. 96, pp. 171–185, 2003.
[8] P. Chaivatamaset, P. Sricharoon, and S. Tia, "Bed agglomeration characteristics of palm shell and corncob combustion in fluidized bed,” Applied Thermal Engineering, vol. 31, pp. 2916–2927, 2011.
[9] P. Chaivatamaset, P. Sricharoon, S. Tia, and B. Bilitewski, "A prediction of defluidization time in biomass fired fluidized bed combustion”, Applied Thermal Engineering, vol. 50, pp. 722–731, 2013.
[10] V.I. Kuprianov and P. Arromdee, "Combustion of peanut and tamarind shell in a conical fluidized-bed combustor: A comparative study”, Bioresource Technology, vol. 140, pp. 199–210, 2013.
[11] L.M.J. Fernández, C.R. Escalada, L.J.M. Murillo, and G.J.E. Carrasco, "Combustion in bubbling fluidised bed with bed material of limestone to reduce the biomass ash agglomeration and sintering”, Fuel, vol. 85, pp. 2081–2092, 2006.
[12] V.I. Kouprianov and W. Permchart, "Emission from a conical FBC fired with a biomass fuel”, Applied Energy, vol. 74, pp. 383–392, 2003.
[13] P. Basu, K.F. Cen, L. Jestin, Boilers and Burners, Springer, New York, 2000.
[14] S. Turns, An Introduction to Combustion, McGraw-Hill, Boston, 2006.
[15] Pollution Control Department, Ministry of Natural Resources and Environment of Thailand. Air Pollution Standards for Industrial Sources. http://www.pcd.go.th/info_serv/reg_std_airsnd03.html.
[16] P. Ninduangdee and V. I. Kuprianov, "Study on burning oil palm kernel shell in a conical fluidized-bed combustor using alumina as the bed material”, Journal of the Taiwan Institute of Chemical Engineers, vol. 44, pp. 1045–1053, 2013.
[17] S. Konsomboon, S. Pipatmanomai, T. Madhiyanon, and S. Tia, "Effect of kaolin addition on ash characteristics of palm empty fruit bunch (EFB) upon combustion”, Applied Energy, vol. 88, pp. 298–305, 2011.