Hydrodynamic and combustion behavior of low grade coals in the riser of a circulating fluidized bed combustor
This study is conducted for understanding the fluidization behavior in a CFB combustor for low ranked coals. A lab-scale cold CFB test rig was built at the NFCIET Multan for understanding the fluidization behaviour. Influence of fluidizing air on the fluidization behavior was observed. It was found that voidage along the riser height is affected by riser geometry. The combustion behavior of low grade coals from Thar coal was also explored in a CFB Combustor. The influence of the fluidizing air on the combustion erformance was examined and their effect on emissions was established. The temperature in the riser of the CFB rose quickly to around 900°C. This rise in temperature has caused an increase in the amount of exhaust gasses which has their influence on the suspension density. From this study, a firsthand experience of combustion behavior of low grade Pakistani coals was documented.
Yan, A.; Zhu, J.X.; Flow properties in the entrance and exit regions of a high flux circulating fluidized riser. Powder Technology 131 (3) 256-263 (2003).
Chen, G.; Andries, J.; Spliethoff, H.; Biomass conversion into fuel gas using circulating fluidised bed technology, the concept improvement and modeling discussions. Renewable Energy 28 (6) 985-994 (2003).
Minchener, A.J.; Coal gasification for advanced power generation, Fuel 84 (17) 2222-2235 (2005).
Mastellone, M.L.; Arena, U.; The effect of particle size and density on solids distribution along the riser of a circulating fluidized bed. Chemical Engineering Science 54 (22) 5383-5391 (1999).
Kunii, D.; Livenspiel, O.; Fluidization Engineering, Butterworth-Heinemann Series. MA. (1991).
Sterneus, J.; Johnson, F.; Leckner, B.; Gas mixing in circulating fluidized bed risers. Chemical Engineering Science 55 (1) 129-148 (2000).
Jaworski, A.J.; Dyakowski, T.; Investigations of flow instabilities within the dense pneumatic conveying system. Powder Technology 125 (3) 279-291(2002).
Pei, C.K.; The status of Malaysian coal industry, Proceedings of the Asia Pacific Mining and Quarrying (APMQ). Kuala Lumpur Malaysia 123-139 (2000).
Vuthaluru, H.B.; Thermal behavior of coal/biomass blends during co-pyrolysis. Fuel Processing Technology 85: 141–155 (2003).
Kok, M.V.; Pokol, G.; Keskin, C.; Madarasz, J.; Bagci, S.; Combustion characteristics of lignite and oil shale samples by thermal analysis technique. Journal of Thermal Analysis and Calorimetry 76: 247-254 (2004).
Monazam, E.R.; Shadle, L.J.; A transient method for characterizing flow regimes in a circulating fluid bed. Powder Technology 139 (1) (2004) 89-97 (2004).
Xu, G.; Necessary parameters for specifying the hydrodynamics of circulating fluidized bed risers – a review and reiteration, Powder Technology 137 (2) 63-76 (2003).
Davidson, J.F.; Circulating Fluidized bed hydrodynamics. Powder Technology 113 (3) 249-260 (2000).
Contractor, R.; Dry, R.J.; White, C.; Mao, Q. M.; Konstantinidis, S.; Potter, O.E.; Circulating fluidized beds-diameter, solid hold up axial gas mixing and contact efficiency. Powder Technology 111 (1) 132-144 (2000).
Mandal, S.; Acharjee, D.K; Gupta, P.S.; Distribution of Axial Voidage in the riser of a Circulating Bed. Indian Journal of Chemical Technology. Jan. 2 (1995).
Weinstein, H.; Chen, L.; Kostazos, A.; The Radial Pressure Gradient in a Fluidized Beds Risers. Fluidization and Fluid-Particle Systems AIChE Annual Meeting (1995).
Van der Ham, A. G. J.; Prins, W.; van Swaaij, W. P. M.; Hydrodynamics of a Pilot¬ Plant Scale Regularly Packed Circulating Fluidized Bed. Fluid-Particle Processes: Fundamentals and Applications. AIChE Symposium Series (1993).
Yerushalmi, J.; An Overview of Commercial Circulating Fluidized Bed Boilers. Circulating Fluidized Bed Technology II (1985).
Zheng, G.; Kozinski, J.A.; Thermal events occurring during the combustion of biomass residue. Fuel 79: 181-192 (2000).
Vamvuka, D.; Kakaras, E.; Grammel, P.; Pyrolysis characteristics and kinetics of biomass residuals mixtures with lignite. Fuel 82: 1949-1960 (2003).
Boiko, E.A.; Research on kinetics of the thermal processing of brown coals of various oxidative ageing degree using the non-isothermal methods. Thermochimica Acta 348: 97-104 (2000).
Park, J.Y., The clustered dense phase model for group A fluidization, Dense phase hydrodynamics, Chemical Engineering Science 58 (1) 193-202 (2003).
Muschelknautz, E.; Special design of short entrance ducts to recirculating cyclones. Proc. 5th Int. Conf. Circ. Fl. Bed, preprint volume, Eq 6, 1 –6 (1996).
Biagini, E.; Lippi, F.; Petarca, L.; Devolatilization rate of biomasses and coal –biomass blends: a experimental investigation. Fuel 81: 1041-1050 (2002).
Zhao, C.; Sun, X.; Chen, L.; Investigation on co-combustion characteristics of paper mill waste and coal in circulating fluidized bed. Proceedings of the 18th International conference on Fluidized Bed Combustion. May 22-25. Toronto. Ontario,.Canada (2005).
Hiltunen, M.; Kilpinen, P.; Hupa, M.; Lee, Y.Y.; N2O emission from CFB boiler: experimental result and chemical interpretation. Proceedings of the 11th International Conference on FBC, Montreal, Canada (1991).
- There are currently no refbacks.
ISSN (Print): 2070-9900 ISSN (Online): 2411-6319