Abstract
In this work vertical dual-array tubular coil baffles arranged in groups of four, six or eight were investigated and the results compared with those from four planar baffles. The baffle coefficients for a single phase, along with the power consumption and gas hold-up in the gas-liquid phase of a system with the various baffle configurations for single and triple Rushton turbines are presented. Measurements were carried out using a dish-bottom vessel with an inner diameter of 0.29 m. Two ambient-temperature media were used as the liquid phase, namely, tap water and a 0.5 M Na2SO4 aqueous solution, representing coalescent and non-coalescent liquids, respectively. The results of the single-phase experiment revealed the coil baffles to have lower power numbers; when the baffle coefficient is ≥ 0.12, the mixing efficiency is the same as that for four planar baffles. The power consumption experiment using the gas-liquid phase showed that installing coil baffles prevented a large power draw in all types of media. In addition, the power draw characteristics are affected by the media. It was found that, because of the low KB number, flooding occurred more readily with coil baffles than with planar baffles. Gas-liquid dispersion experiments in an air-water system indicated that, at a low gas flow-rate, the gas hold-up values of the coil baffles were almost 60 % higher than those of the conventional four baffles. However, this phenomenon was not observed in the Na2SO4 aqueous solution because of the existence of dead zones in viscous liquids. Finally, all the data from the power consumption and gas hold-up experiments on the gas-liquid phase were correlated.
Similar content being viewed by others
References
Dunlap, I. R., & Rushton, J. H. (1953). Heat transfer coefficients in liquid mixing vertical tube baffles. Chemical Engineering Progress, Symposium Series, 49, 137–151.
Fujasova, M., Linek, V., & Moucha, T. (2007). Mass transfer correlations for multiple-impeller gas-liquid contactors. Analysis of the effect of axial dispersion in gas and liquid phases on ”local” kL a values measured by the dynamic pressure method in individual stages of the vessel. Chemical Engineering Science, 62, 1650–1669. DOI: 10.1016/j.ces.2006.12.003.
Karcz, J., Strek, F., Major, M., & Siciarz, R. (1998). An effect of the geometrical parameters of the tubular baffles on a power consumption in the agitated vessel. In Proceedings of the 13th International Congress CHISA, August 23–28 1998 (pp. 9). Prague, Czech Republic: The Institute of Chemical Process Fundamentals of the CAS.
Kern, Q. D. (1965). Process of heat transfer. New York, NY, USA: McGraw-Hill.
Major-Godlewska, M. (2003). Experimental studies of gas holdup and power consumption in an agitated vessel equipped with a vertical coil. Inzynieria i Aparatura Chemiczna, 42(5), 125–127. (in Polish)
Major-Godlewska, M., & Karcz, J. (2003). Gas hold-up and power consumption for gas-liquid system agitated in a stirred tank equipped with vertical coil. Chemical Papers, 57, 432–444.
Major-Godlewska, M., & Karcz, J. (2011). Process characteris-tics for a gas-liquid system agitated in a vessel equipped with a turbine impeller and tubular baffles. Chemical Papers, 65, 132–138. DOI: 10.2478/s11696-010-0080-0.
Major-Godlewska, M., & Karcz, J. (2012). Agitation of a gas-solid-liquid system in a vessel with high-speed impeller and vertical tubular coil. Chemical Papers, 66, 566–573. DOI: 10.2478/s11696-012-0148-0.
Man, K. L., Hughes, W., & Moody, G. W. (1991). The effect of rheology and baffle design on the power and heat transfer performance in stirred vessels using vertical tubular baffles. In Proceedings of the 7th European Conference on Mixing, September 18–20 1991 (part I, pp. 321–332). Brugge, Belgium: Royal Flemish Society of Engineers.
Nagata, S. (1975). Power consumption of mixing impellers, mixing principles and applications. Tokyo, Japan: Kodansha
Nocentini, M., Fajner, D., Pasquali, G., & Magelli, F. (1993). Gas-liquid mass transfer and holdup in vessels stirred with multiple Rushton turbines: Water and water-glycerol solutions. Industrial & Engineering Chemistry Research, 32, 19–26. DOI: 10.1021/ie00013a003.
Oldshue, J. Y., Hirschland, H. E., & Gretton, A. T. (1956). Theory of mixing. Chemical Engineering Progress, 52(11), 481.
Oldshue, J. Y. (1983). Fluid mixing technology. New York, NY, USA: McGraw-Hill.
Shen, C., Chen, J., Zhang, J., & Dai, G. (2005). Performance and design of baffles in mechanically agitated gas-liquid reactor. Journal of Chemical Engineering of Chinese Univer-sities, 19(2), 162–168. (in Chinese)
Vasconcelos, J. M. T., Orvalho, S. C. P., Rodrigues, A. M. A. F., & Alves, S. S. (2000). Effect of blade shape on the performance of six-bladed disk turbine impellers. Indus-trial & Engineering Chemistry Research, 39, 203–213. DOI: 10.1021/ie9904145.
Wan, X., & Takahashi, K. (2014). Effect of vertical inner coils on the bioreactor’s power consumption and masstransfer coefficients. In Proccedinds of International Symposium on Mixing in Industrial Processes VIII Conference, September 14–17 2014. Melbourne, Australia: Australasian Institute of Mining and Metallurgy
Weng, Z., Huang, Z., Chen, K., & Xu, S. (1984). Effect of baffles on agitation characteristics. Journal of Chemical Industry and Engineering (China), 3, 267–273 (in Chinese).
Xie, M. H., Xia, J. N., Zhou, Z., Chu, J., Zhuang, Y. P., & Zhang, S. L. (2014). Flow pattern, mixing, gas hold-up and mass transfer coefficient of triple-impeller configurations in stirred tank bioreactors. Industrial & Engineering Chemistry Research, 53, 5941–5953. DOI: 10.1021/ie400831s.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Wan, X., Takahata, Y. & Takahashi, K. Power consumption and gas—liquid dispersion in turbulently agitated vessels with vertical dual-array tubular coil baffles. Chem. Pap. 70, 445–453 (2016). https://doi.org/10.1515/chempap-2015-0221
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1515/chempap-2015-0221