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

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.

• P. Ninduangdee
• V. I. Kuprianov

• Palm kernel shell
• fluidized-bed combustion
• alternative bed materials
• combustion and emission performance
• bed agglomeration prevention.

[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.