The combustion behavior and gaseous emissions of wheat dust pellet at various operating parameters such as air temperature, pellet size, and air velocity are evaluated to achieve a better combustion performance. The results showed that as air temperature and air velocity increase as well as pellet size decreases, ignition time, char time, time to reach maximum temperature decreases and total combustion rate increases. It was concluded from the results that, a hexagonal pellet is the best shape for combustion under the investigated conditions and parameters due to its lowest ignition temperature, lowest surface temperature, shortest ignition time, and longest time required for combustion. CO2 content reaches its maximum value at air temperature 4000C for all pellets. The maximum CO concentration occurs at the highest diameter of the pellet. The combustion efficiency ranged between 99% to 100%. The wheat dust pellet has a medium slagging tendency (slagging index=0.72) and a relatively high fouling inclination (fouling index=1.88). The activation energy of a wheat dust pellet and a binder is 102.05 and 109.62kJmol-1, respectively, using TG data and kinetics model. The ignition time, the maximum combustion rate time and the burnt temperature of epoxy 1092 are lower than that of the pellet.
wheat dust pellets, combustion and gaseous emission characteristics, internal ignition temperature, experimental correlations, ash analysis
 Saxena SC, Jotshi CK. (1994). Fluidized-bed incineration of waste materials. Prog Energy Combust Sci 20: 281-324. https://doi.org/10.1016/0360-1285(94)90012-4
 Biswas AK. (2014). Effect of pelletizing conditions on combustion behaviour of single wood pellet. Appl Energy 119: 79-84. https://doi.org/10.1016/j.apenergy.2013.12.070
 Kung H. (1972). A mathematical model of wood pyrolysis. Combustion and Flame 18: 185-195. https://doi.org/10.1016/S0010-2180(72)80134-2
 Saastamoinen J, Richard J. (1996). Simultaneous drying and pyrolysis of solid fuel particles. Comb. Flame 106: 288-300. https://doi.org/10.1016/0010-2180(96)00001-6
 Saastamoinen J, Taipale R, Horttanainen M, Sarkomaa P. (2000). Propagation of the ignition front in beds of wood particles. Combust Flame 214-226. https://doi.org/10.1016/S0010-2180(00)00144-9
 Ronnback M, Axell M, Gustavsson L. (2000). Combustion processes in a biomass fuel bed- experimental results. Progress in Thermochemical Biomass Conversion. 17-22. https://doi.org/10.1002/9780470694954.ch59
 Fleckl T, Obernberger I, Jager H. (2000). Combustion diagnostics at a biomass-fired grate furnace using FT-IR absorption spectroscopy for hot gas measurements. In: Proceedings of the 5th International Conference of Industrial. Portugal.
 Tissari J, Hytonen K, Lyyranen J, Jokiniemi J. (2007). A novel field measurement method for determining fine particle and gas emissions from residential wood combustion. Atmos Environ 41: 8330-8344. https://doi.org/10.1016/j.atmosenv.2007.06.018
 Boman C, Israelsson S, Öhman M, Sweden L. (2008). Combustion properties and environmental performance during small scale combustion of pelletized hardwood raw material of aspen. In: Proceedings of World Bioenergy, Jonkoping, Sweden, pp. 27–29.
 Kuo JT, Hsi CL. (2005). Pyrolysis and ignition of single wooden spheres heated in high temperature streams of air. Combust Flame 142: 401–412. https://doi.org/10.1016/j.combustflame. 2005.04.002.
 Kraiem N, Jeguirim M, Limousy L, Lajili S, Dorge L, Michelin R. (2014). Mpregnation of olive mill wastewater on dry biomasses: Impact on chemical properties and combustion performances. Energy 78: 479-489. https://doi.org/10.1016/j.energy.2014.10.035
 Khodaei H, Al-Abdeli YM, Guzzomi F, Yeoh GH. (2015). Overview of processes and considerations in the modelling of fixed-bed biomass combustion. Energy 88: 946-972. https://doi.org/10.1016/j.energy.2015.05.099
 El-Sayed SA, Khairy M. (2015). Effect of heating rate on the chemical kinetics of different biomass pyrolysis materials. Biofuels 6: 157-170. https://doi.org/10.1080/17597269.2015.1065590
 Nimmo W, Daood SS, Gibbs BM. (2010). The effect of O2 enrichment on NOx formation in biomass co-fired pulverized coal combustion. Fuel 89: 2945–2952. https://doi.org/10.1016/j.fuel.2009.12.004
 Lajili M, Jeguirim M. (2014). Physico-chemical properties and thermal degradation characteristics of agropellets from olive mill by-products/sawdust blends. Fuel processing Technology 126: 215-221. https://doi.org/10.1016/j.fuproc.2014.05.007
 Munir S, Daood SS, Nimmo W, Cunliffe AM, Gibbs BM. (2009). Thermal analysis and devolatilization kinetics of cotton stalk, sugar cane bagasse and shea meal under nitrogen and air atmosphere. Bioresource Technology 100: 1413–1418. https://doi.org/10.1016/j.biortech.2008.07.065
 Fleckl T, Obernberger I, Jager H. (2000). Combustion diagnostics at a biomass-fired grate furnace using FT-IR absorption spectroscopy for hot gas measurements. In: Proceedings of the 5th International Conference of Industrial Furnaces and Boilers. Portugal.
 Tissari J, Hytonen K, Lyyr€anen J, Jokiniemi J. (2007). A novel field measurement method for determining fine particle and gas emissions from residential wood combustion. Atmos Environ 41: 8330-8344. https://doi.org/10.1016/j.atmosenv.2007.06.018
 Wiinikka H, Gebart R. (2005). The influence of fuel type on particle emissions in combustion of biomass pellets. Combust Sci Technol 17741-63. https://doi.org/10.1080/00102200590917257
 Bovy P. (2008). Effect of air preheating in moving grate furnaces: Modeling convective drying and experimental investigation of spontaneous ignition. PhD thesis. Eindhoven University of Technology, the Netherlands.
 Pronobis M. (2005). Evaluation of the influence of biomass co-combustion on boiler furnace slagging by means of fusibility correlations. Biomass Bioenergy 28: 375–383. https://doi.org/10.1016/j.biombioe.2004.11.003
 Song JH. (2013). Study on air preheater corrosion problem of CFB biomass directed-fired boiler in Zhanjiang biomass power plant.Appl Mech Mater 9291-294. https://doi.org/10.4028/www.scientific.net/AMM.291-294.294
 Amir MK, et. al. (2014). Corrosion prevention in boilers by using energy auditc on- sideration. Appl. Mech. Mater 7–10. https://doi.org/10.4028/www.scientific.net/AMM.532.307
 Niu S, Han K, Lu C. Release of sulfur dioxide and nitric oxide and characteristic of coal combustion under the effect of calcium based organic compounds. Chem. Eng. J. 168 (2011) 255–261. https://doi.org/10.1016/j.cej.2010.10.082
 Li X, Ma B, Xu L, Hu Z, Wang X. Thermogravimetric analysis of the co-combustion of the blends with high ash coal and waste tyres. Thermochimica Acta 441(2006) 79–83. https://doi.org/10.1016/j.tca.2005.11.044
 Gong X, Guo Z, Wang Z. Reactivity of pulverized coals during combustion catalyzed by CeO2 and Fe2O3. Combust. Flame 157(2010): 351–356. https://doi.org/10.1016/j.combustflame. 2009.06.025
 Arranz J.I. , Miranda M.T., Montero I., Seplveda F.J., Rojas (2015) Characterization and combustion behavior of commercial and experimental wood pellets in South West Europe Fuel 142 199–207. https://doi.org/10.1016/j.fuel.2014.10.059
 Luo SY, Xiao B, Hu ZQ, Liu SM, Guan YW (2009). Experimental study on oxygen-enriched combustion of biomass micro fuel. Energy 34:1880–1884. https://doi.org/10.1016/j.biombioe.2004.11.003
 Coats, A.W., Redfern, J.P., (1964). Kinetic parameters from thermogravimetric data. Nature 201:68–69. https://doi.org/10.1038/201068a0
 Ahn H.K., Sauer T.J., Richard T.L., T.D. Glanville. Determination of thermal properties of composting bulking materials. Bioresource Technology 100: 3974–3981. https://doi.org/10.1016/j.biortech.2008.11.056
 Ranz WE, Marshall WR. (1952). Evaporation from drops Chem. Eng. Prog. 48: 173–180. University of Wisconsin, Madison, WI.
 Orang N, Tran H. (2014). Effect of feedstock moisture content on biomass boiler operation. master thesis. Chemical Engineering and Applied Chemistry University of Toronto 12.
 Kaewklum R, Kuprianov VI, permchart W. (2007). Influence of fuel moisture and excess air on formation and reduction of CO and NOx in a fluidized-bed combustor fired with Thai Rice Husk. Asian J. Energy Environ 8: 547- 555.
 Wang Q, Zhao W, Liu H, Jia C, Xu H. (2012). Reactivity and Kinetic analysis of biomass during combustion. Energy Procedia 17: 869–875. https://doi.org/10.1016/j.egypro.2012.02.181
 Ghetti P., L. Ricca, L. Angelini, (1996). Thermal analysis of biomass and corresponding pyrolysis products. Fuel 75: 565-573. https://doi.org/10.1016/0016-2361(95)00296-0
 Kumar A, Wang L, Jones YA, Dzenis DD, Hanna MA. (2008). Thermogravimetric characterization of corn Stover as gasification and pyrolysis feedstock. Biomass Bioenergy 32: 460-467. https://doi.org/10.1016/j.biombioe.2007.11.004
 Khatami R, Stivers C, Joshi K, Levendis Y, Sarofim A (2012). Combustion behavior of single particles from three different coal ranks and from sugar cane bagasse in O2/N2 and O2/CO2 atmospheres. Combust Flame 159: 1253-1271. https://doi.org/10.1016/j.combustflame.2011.09.009
 Riaza J, Khatami R, Levendis YA, Álvarez L, Gil MV, Pevida C. (2014). Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions. Combust Flame 161: 1096-1108. https://doi.org/10.1016/j.combustflame.2013.10.004
 Zhou K, Lin Q, Hu H, Hu H, Song L. (2016). The ignition characteristics and combustion processes of the single coal slime particle under different hot coflow conditions in N2/O2 atmosphere. Energy 163: 173-184. https://doi.org/10.1016/j.energy.2016.02.038
 Ponzio A, Senthoorselvan S, Yang W, Blasiak W, Eriksson O. (2008). Ignition of single coal particles in high-temperature oxidizers with various oxygen concentrations. Fuel 87: 974-987. https://doi.org/10.1016/j.fuel.2007.06.027
 Kijo-Kleczkowska A, S´roda K, Kosowska-Golachowska M, Musiał T, Wolski K. (2016). Combustion of pelleted sewage sludge with reference to coal and biomass. Fuel 170: 141–160. https://doi.org/10.1016/j.fuel.2015.12.026
 Lu H, Ip E, Scott J, Foster P, Vickers M, Baxter LL. (2010). Effects of particle shape and size on devolatilization of biomass particle. Fuel 89: 1156-1168. https://doi.org/10.1016/j.fuel.2008.10.023
 Li J, Manosh C, Paul A, Paul L, Younger A, Ian Watson A, Mamdud Hossain B, Stephen Welch C. (2015). Characterization of biomass combustion at high temperatures based on an upgraded single particle model. Applied Energy 156: 749–755. https://doi.org/10.1016/j.apenergy.2015.04.027
 Ponzio A, Yang W, Blasiak W. (2007). Combustion of solid fuels under the conditions of high temperature and various oxygen concentrations. International Conference on Power Engineering 23-27. https://doi.org/10.1007/978-3-540-76694-0_162
 Williams A, Backreedy R, Habib R, Jones JM. Pourkashanian M. (2002). Modeling coal combustion: the current position, Fuel 81: 605-618. https://doi.org/10.1016/S0016-2361(01)00158-2
 Zheng G, Kozin´ski JA. (2000). Thermal events occurring during the combustion of biomass residue. Fuel 79: 181–192. https://doi.org/10.1016/S0016-2361(99)00130-1
 Abuelnuor AAA, Wahid MA, Seyed Ehsan Hosseini A, Saat A, Khalid M, Saqr B, Hani H, Sait C, Osman M. (2014). Characteristics of biomass in flameless combustion: A review. Renewable and Sustainable Energy Reviews 33: 363–370. https://doi.org/10.1016/j.rser.2014.01.079
 Juan F, Pérez A, Melgar A, Benjumea PN. (2012). Effect of operating and design parameters on the gasification/combustion process of waste biomass in fixed bed downdraft reactors: An experimental study. Fuel 96: 487–496. https://doi.org/10.1016/j.fuel.2012.01.064
 Yang Y, Ryu C, Khor A, Yates N, Sharifi V, Swithenbank J. (2005). Effect of fuel properties on biomass combustion. Part II. Modelling approach didentification of the controlling factors. Fuel 84: 2116-2130. https://doi.org/10.1016/j.fuel.2005.04.023
 Bhuiyan AA, Naser J. (2014). Effect of recycled ratio on heat transfer performance of coal combustion in a 0. 5 MW th combustion test facility. 19th Aust. Fluid Mech. Conf., Melbourne.
 Bhuiyan AA, Naser J. (2015). Numerical modelling of oxy fuel combustion, the effect of radiative and convective heat transfer and burnout. Fuel 139: 268-284.
 Ryu C, Yang YB, Khor A, Yates NE, Sharifi VN, Swithenbank J. (2006). Effect of fuel properties on biomass combustion: part I. Experiments fuel type, equivalence ratio and particle size. Fuel 85: 1039-1046. https://doi.org/10.1016/j.fuel.2005.09.019
 Yang YB, Yamauchi H, Nasserzadeh V, Swithenbank J. (2003). Effects of fuel devolatilisation on the combustion of wood chips and incineration of simulated municipal solid wastes in a packed bed. Fuel 82: 22-05. https://doi.org/10.1016/S0016-2361(03)00145-5
 Babrauskas VJ. (2002). Ignition of wood; A review of the state of the art. Fire Protection Eng. 12: 163–189. https://doi.org/10.1177/10423910260620482
 Carslaw HS, Jaeger JC. (1959). Conduction of Heat in Solids, second ed., Oxford Univ. Press, London, p.75.
 Herman D. (1981). The rate of pyrolysis of densified ponderosa pine. Masters Thesis in Chemical Engineering at Colorado School of Mines, Golden, CO.
 Olsson M. (2006). Wheat dust and peat for fuel pellets – organic compounds from combustion. Biomass Bioenergy 30: 555–564. https://doi.org/10.1016/j.biombioe.2006.01.005
 Kallis KX, Giacomo A. Susini P, Oakey JE. (2013). A comparison between Miscanthus and bioethanol waste pellets and their performance in a downdraft gasifier. Applied Energy 101: 333–340. https://doi.org/10.1016/j.apenergy.2012.01.037