Main Article Content



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.

Article Details

How to Cite
SARBASSOV, Yerbol et al. HYDRODYNAMIC EXPERIMENTS ON A SMALL-SCALE CIRCULATING FLUIDISED BED REACTOR AT ELEVATED OPERATING PRESSURE, AND UNDER AN O2/CO2 ENVIRONMENT. Thermal Science, [S.l.], mar. 2017. ISSN 2334-7163. Available at: <http://thermal-science.tech/journal/index.php/thsci/article/view/2207>. Date accessed: 14 dec. 2017. doi: https://doi.org/10.2298/TSCI150921068S.
Received 2017-03-06
Accepted 2017-03-13
Published 2017-03-13


[1] IEA, Key World Energy Statistics, 2012
[2] Basu, P., Combustion of coal in circulating fluidized-bed boilers: a review, Chem. Eng. Sci., 54 (1999), 22, pp. 5547–5557
[3] Beer, J.M., High efficiency electric power generation: The environmental role, Prog. Energy Combust. Sci., 33 (2007), pp. 107–134
[4] Grace, J.R., Avidan, A.A., Knowlton, T.M., Ed, Circulating Fluidized Beds, Blackie Academic & Professional., London, UK, 1997
[5] Nowak, W., Clean coal fluidized-bed technology in Poland, Appl. Energy., 74 (2003), pp. 405– 413
[6] Anthony, E.J., Oxyfuel CFBC: status and anticipated development, Greenh. Gases Sci. Technol., 3 (2013), pp. 116–123
[7] 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
[8] Lupion, M., et al., 30 MWth CIUDEN Oxy-CFB Boiler - First Experiences, Energy Procedia, 37 (2013), pp. 6179–6188
[9] 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
[10] 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
[11] 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
[12] 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
[13] 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
[14] 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
[15] MacNeil, S., Basu, P., Effect of pressure on char combustion in a pressurized circulating fluidized bed boiler, Fuel., 77 (1998), 4, pp. 269–275
[16] Stubington, J.F., Wang, A.L.T., Unburnt carbon elutration from pressurised fluidised combustion of Australian black coals, Fuel., 79 (2000), pp. 1155–1160
[17] Hong, J., et al., Analysis of oxy-fuel combustion power cycle utilizing a pressurized coal combustor, Energy., 34 (2009), 9, pp. 1332–1340
[18] 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
[19] 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
[20] 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
[21] 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
[22] Llop, M.F., et al., Expansion of gas–solid fluidized beds at pressure and high temperature, Powder Technol.,107 (2000), pp. 212–225
[23] 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
[24] 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
[25] Olowson, P.A., Almstedt, A.E., Influence of pressure on the minimum fluidization velocity, Chem. Eng. Sci., 46 (1991), 2, pp. 637–640
[26] 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
[27] 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
[28] Carsky, M., Hartman, M., The bubble frequency in a fluidized bed at elevated pressure, Powder Technol., 61 (1990), pp. 251–254
[29] Sidorenko, I., Rhodes, M.J., Influence of pressure on fluidization properties, Powder Technol., 141 (2004), pp. 137–154
[30] Richtberg, M., et al., Characterization of the flow patterns in a pressurized circulating fluidized bed, Powder Technol., 155 (2005), pp. 145–152
[31] Marzocchella, A., Salatino, P., Fluidization of solids with CO2 at pressures from ambient to supercritical, AIChE J., 46 (2000), 5, pp. 901–910
[32] Cao, J., et al., Simulation and experimental studies on fluidization properties in a pressurized jetting fluidized bed, Powder Technol., 183 (2008), pp. 127–132
[33] 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
[34] 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
[35] Kunii, D., Levenspiel, O., Fluidization Engineering, 2nd ed, Butterworth Heinemann., London, UK, 1991
[36] 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
[37] Sanchez-Delgado, S., et al., On the minimum fluidization velocity in 2D fluidized beds, Powder Technol., 207 (2011), pp. 145-153.
[38] Chew, J.W., et al., Reverse core-annular flow of Geldart Group B particles in risers, Powder Technol., 221 (2012), pp. 1–12
[39] 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
[40] Mahmoudi, S., et al., Solids flow diagram of a CFB riser using Geldart B-type powders, Particuology., 10 (2012), pp. 51–61
[41] 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
[42] 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