Preliminary Investigation on Combustion Characteristics of Rice Husk in FBC

The experimental results on combustion of rice husk in a conical fluidized bed combustor (referred to as the conical FBC) using silica sand as the bed material are presented in this paper. The effects of excess combustion air and combustor loading as well as the sand bed height on the combustion pattern in FBC were investigated. Temperatures and gas concentrations (CO and NO) along over the combustor height as well as in the flue gas downstream from the ash collecting cyclone were measured. The results showed that the axial temperature profiles in FBC were explicitly affected by the combustor loading whereas the excess air and bed height were found to have minor influences on the temperature pattern. Meanwhile, the combustor loading and the excess air significantly affected the axial CO and NO concentration profiles; however, these profiles were almost independent of the bed height. The combustion and thermal efficiencies for this FBC were quantified for different operating conditions.

Authors:

• W. Permchart
• S. Tanatvanit

Keywords:

• Temperature
• Combustor loading
• Excess air
• Bed height.

References:

[1] Department of Alternative Energy Development and Energy
Conservation (DEDE), Thailand Energy Situation 2008 Report, Ministry
of Energy, Bangkok, Thailand, 2008, 57p.
[2] W. Permchart, and V.I. Kouprianov, "Design and Experimental Study of
A Conical Fluidized Bed Firing Sawdust", in 2002 Proc. of the 1st
International Conference on Sustainable Energy Technologies, pp. 1/28
- 6/28.
[3] W. Permchart, and V.I. Kouprianov, "Fluidization Characteristics of A
Conical Sand Bed", in 2004 Proc. of the 15th International Symposium
on Transport Phenomena, pp.461 - 466.
[4] R. Kaewklum, V.I. Kuprianov and W. Permchart, "Effects of Fuel
Moisture on Combustion Efficiency and Emission Performance of A
Fluidized-bed Combustor Firing Rice Husk", in 2005 Proc. of the 6th
International Conference on Mechanical Engineering, pp. TH-17/1 -
17/7.
[5] S. Suwanyuen, T. Chayawatana, Y. Surachpakorn, C. Tangsathikulchai,
and S. Tia, "Combustion of Rice Hull in A Fluidised Bed Furnace",
ASEAN Journal on Science & Technology for Development, Vol. 9 (2),
1992, pp. 107-115.
[6] V.I. Kouprianov, T. Utistham and B. Suttisonk, "Kinetic Model for
Estimation of CO Emission in the Conical Fluidized Bed Combustor
Firing Sawdust" in 1997 Proc. of the Regional Symposium on Chemical
Engineering.
[7] H. Liu and B.M. Gibbs, "Modelling of NO and N2O emissions from
biomass-fired circulating fluidized bed combustion", Fuel, Vol. 81,
2002, pp. 271-280.
[8] S.C. Bhattacharya, S. Narendra and Z. Alikhani, "Some Aspects of
Fluidized Bed Combustion of Paddy Husk", Applied Energy, Vol. 16,
1984, pp. 307-316.
[9] B.D. Grubor, S.N. Oka, M.S. Ilic, D.V. Dakic and B.T. Arsic, "Biomass
FBC combustion-bed agglomeration problems" in 1995 Proc. of the 13th
International Conference on Fluidized Bed Combustion, pp. 515-522.
[10] F. Winter, C. Wartha and H. Hofbeuer, "NO and N2O Formation during
the Combustion of Wood, Straw, Malt Waste and Peat", Bioresource
Technology, Vol. 70, 1999, pp. 39-49.
[11] J. Werther, M. Saenger, E.-U. Hartge, T. Ogada and Z. Siagi,
"Combustion of Agricultural Residues", Progress in Energy and
Combustion Science, Vol. 26 (1), 2000, pp. 1-27.
[12] B. Leckner and M. Karlsson, "Gaseous Emission from Circulating
Fluidized Bed Combustion of Wood", Biomass & Bioenergy, Vol. 4,
1993, pp. 379-389.
[13] P. Basu, K.F. Cen and L. Jestin, Boilers and Burners, Springer, New
York, 2000.