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Pressurised circulating fluidised bed (CFB) technology is a potentially promising development for clean coal technologies. The current work explores the hydrodynamics of a small-scale circulating fluidised bed at elevated operating pressures ranging from 0.10 to 0.25 MPa. The initial experiments were performed at atmospheric pressure with air and O2/CO2 environments as the fluidisation gas to simulate the hydrodynamics in a CFB. A comparison between the effects of air and O2/CO2 mixtures on the hydrodynamics was outlined in this paper for particles of 160 μm diameter. A small but distinct effect on axial voidage was observed due to the change in gas density in the dense zone of the bed at lower gas velocity, while only minimal differences were noticed at higher gas velocities. The hydrodynamic parameters such as pressure drop and axial voidage profile along the height were reported at two different bed inventories (0.5 and 0.75 kg) for three mean particle sizes of 160, 302 and 427 μm and three superficial gas velocities. It was observed that the operating pressure had a significant effect on the hydrodynamic parameters of bed pressure drop and axial bed voidage profiles. The effect of solids loading resulted in an exponential change in pressure drop profile at atmospheric pressure as well as at elevated pressure. The experimental results on hydrodynamic parameters are in reasonable agreement with published observations in the literature.
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 Basu, P., Combustion of coal in circulating fluidized-bed boilers: a review, Chem. Eng. Sci., 54 (1999), 22, pp. 5547–5557
 Beer, J.M., High efficiency electric power generation: The environmental role, Prog. Energy Combust. Sci., 33 (2007), pp. 107–134
 Grace, J.R., Avidan, A.A., Knowlton, T.M., Ed, Circulating Fluidized Beds, Blackie Academic & Professional., London, UK, 1997
 Nowak, W., Clean coal fluidized-bed technology in Poland, Appl. Energy., 74 (2003), pp. 405– 413
 Anthony, E.J., Oxyfuel CFBC: status and anticipated development, Greenh. Gases Sci. Technol., 3 (2013), pp. 116–123
 Tan, Y., et al., Experiences and results on a 0.8MWth oxy-fuel operation pilot-scale circulating fluidized bed, Appl. Energy., 92 (2012), pp. 343–347
 Lupion, M., et al., 30 MWth CIUDEN Oxy-CFB Boiler - First Experiences, Energy Procedia, 37 (2013), pp. 6179–6188
 Niksa, S., et al., Coal conversion submodels for design applications at elevated pressures. Part I. devolatilization and char oxidation, Prog. Energy Combust. Sci., 29 (2003), 5, pp. 425–477
 Huang, Y., et al., Influences of coal type on the performance of a pressurised fluidised bed combustion power plant, Fuel., 79 (2000), pp. 1595–1601
 Gupta, A.V.S.S.K.S., Nag, P.K., Bed-to-wall heat transfer behaviour in a pressurized circulating fluidized bed, Int. J. Heat Mass Transf., 45 (2002), pp. 3429–3436
 Wang., A.T.L., et al., Hydrodynamic performance of a novel design on pressurized fluidized bed combustor, J. Energy Resour. Technol., 128 (2006), pp. 111–117
 Li, J., et al., Minimum and terminal velocity in fluidization of coal gasification materials and and coal blending of gasification under pressure, Fuel., 110 (2013), pp. 153–161
 Duan, F., et al., Dependence of bituminous coal gasification on pressure in a turbulent circulating fluidized bed, Asia-Pacific J. Chem. Eng., 7 (2012), pp. 822–827
 MacNeil, S., Basu, P., Effect of pressure on char combustion in a pressurized circulating fluidized bed boiler, Fuel., 77 (1998), 4, pp. 269–275
 Stubington, J.F., Wang, A.L.T., Unburnt carbon elutration from pressurised fluidised combustion of Australian black coals, Fuel., 79 (2000), pp. 1155–1160
 Hong, J., et al., Analysis of oxy-fuel combustion power cycle utilizing a pressurized coal combustor, Energy., 34 (2009), 9, pp. 1332–1340
 Kalita, P., et al., Parametric study on the hydrodynamics and heat transfer along the riser of a pressurized circulating fluidized bed unit, Exp. Therm. Fluid Sci., 44 (2013), pp. 620–630
 Kalita, P., et al., Effect of biomass blending on hydrodynamics and heat transfer behavior in a pressurized circulating fluidized bed unit, Int. J. Heat Mass Transf., 60 (2013), pp. 531–541
 Komorowski, M., Nowak, W.,Vertical solids distribution under air/carbon dioxide fluidization conditions in a circulating fluidized bed, Proceedings, 14th International Conference on Fluidization -From Fundamentals to Products, Noordwijkerhout, The Netherlands, 2013
 Guedea, I., et al., Influence of O2/CO2 mixtures on the fluid-dynamics of an oxy-fired fluidized bed reactor, Chem. Eng. J., 178 (2011), pp. 129–137
 Llop, M.F., et al., Expansion of gas–solid fluidized beds at pressure and high temperature, Powder Technol.,107 (2000), pp. 212–225
 Barreto, G.F., et al., The effect of pressure on the flow of gas in fluidized beds of fine particles, Chem. Eng. Sci., 38 (1983), 12, pp. 1935–1945
 Wiman, J., Almstedt, A.E., Hydrodynamics, erosion and heat transfer in a pressurized fluidized: influence of pressure, fluidization velocity, particle size and tube bank geometry, Chem. Eng. Sci., 52 (1997), 16, pp. 2677–2695
 Olowson, P.A., Almstedt, A.E., Influence of pressure on the minimum fluidization velocity, Chem. Eng. Sci., 46 (1991), 2, pp. 637–640
 Olowson, P.A., Influence of pressure and fluidization velocity on the hydrodynamics of a fluidized bed containing horizontal tubes, Chem. Eng. Sci., 49 (1994), 15, pp. 2437–2446
 Olowson, P.A., Almstedt, A.E., Hydrodynamics of a bubbling fluidized bed: Influence of pressure and fluidization velocity in terms of of drag force, Chem. Eng. Sci., 47 (1992), 2, pp. 357–366
 Carsky, M., Hartman, M., The bubble frequency in a fluidized bed at elevated pressure, Powder Technol., 61 (1990), pp. 251–254
 Sidorenko, I., Rhodes, M.J., Influence of pressure on fluidization properties, Powder Technol., 141 (2004), pp. 137–154
 Richtberg, M., et al., Characterization of the flow patterns in a pressurized circulating fluidized bed, Powder Technol., 155 (2005), pp. 145–152
 Marzocchella, A., Salatino, P., Fluidization of solids with CO2 at pressures from ambient to supercritical, AIChE J., 46 (2000), 5, pp. 901–910
 Cao, J., et al., Simulation and experimental studies on fluidization properties in a pressurized jetting fluidized bed, Powder Technol., 183 (2008), pp. 127–132
 Borodulya, V.A., Heat transfer between a surface and a fluidized bed: consideration of pressure and temperature effects, Int. J. Heat Mass Transf., 34 (1991), 1, pp. 47–53
 Borodulya, V.A., et al., Heat transfer berween fluidized bed of large particles and horizontal tube bundles at high pressures, Int. J. Heat Mass Transf., 27 (1984), 8, pp. 1219–1225
 Kunii, D., Levenspiel, O., Fluidization Engineering, 2nd ed, Butterworth Heinemann., London, UK, 1991
 Czakiert, T., et al., Oxy-fuel circulating fluidized bed combustion in a small pilot-scale test rig, Fuel Process. Technol., 91 (2010),11, pp. 1617–1623
 Sanchez-Delgado, S., et al., On the minimum fluidization velocity in 2D fluidized beds, Powder Technol., 207 (2011), pp. 145-153.
 Chew, J.W., et al., Reverse core-annular flow of Geldart Group B particles in risers, Powder Technol., 221 (2012), pp. 1–12
 Das, M., et al., Axial voidage profiles and identification of flow regimes in the riser of a circulating fluidized bed, Chem. Eng. J., 145 (2008), 2, pp. 249–258
 Mahmoudi, S., et al., Solids flow diagram of a CFB riser using Geldart B-type powders, Particuology., 10 (2012), pp. 51–61
 Buhre, B.J.P., et al., Oxy-fuel combustion technology for coal-fired power generation, Prog. Energy Combust. Sci., 31 (2005), 4, pp. 283–307
 Yin, S., et al., Gas-solid flow behavior in a pressurized high-flux circulating fluidized bed riser, Chem. Eng. Commun., 201 (2014), pp. 352–366