Resistance Characteristics of Surface Aerators
This article has a reply.
VIEW THE REPLYThis article has a reply.
VIEW THE REPLYPublication: Journal of Hydraulic Engineering
Volume 135, Issue 1
Abstract
The resistance characteristics in terms of power consumption, interpreted in terms of Power number , of unbaffled surface aeration systems consisting of flat bladed impellers, were studied in two shapes of surface aerations tanks: square and circular. Experiments were conducted in three different sizes in each of the geometrically similar unbaffled square and circular surface aerators. Results have shown that the cannot be simulated singularly either with Reynolds number or with Froude number as there are scale effects; hence there appears to be a need for incorporating the effects of both and . It is found that is uniquely related to a parameter , which is defined as a parameter governing the theoretical power per unit volume for both shapes of aeration tanks; however, such relationships are different for both shapes of aerators. Interestingly values are always higher in square surface aerators than in circular surface aerators, which suggests that the circular surface aerators require less power input than the square surface aerators. The usefulness of such correlations was demonstrated in estimating the power requirement while achieving a required oxygen transfer coefficient in surface aerators.
Get full access to this article
View all available purchase options and get full access to this article.
References
American National Standards Institute/National Electrical Manufacturers Institute (ANSI/NEMA). (1978). “Motors and generators.” IEE standard MGI-1978, New York.
Asai, T., and Kono, T. (1982). “Estimation of oxygen absorption coefficient and power consumption in a stirred tank fermentor.” J. Ferment. Technol., 60, 265–268.
Ascanio, G., Castro, B., and Galindo, E. (2004). “Measurement of power consumption in stirred vessels—A review.” Chem. Eng. Res. Des., 82(A9), 1282–290.
Brown, D. E. (1997). “The measurement of fermentor power input.” Chem. Ind., 16, 684–688.
Cook, A. L., and Carr, C. C. (1947). Elements of electrical engineering, 5th Ed., Wiley, New York.
Green, S. J. (1953). “Agitation in process design.” Trans. Inst. Chem. Eng., 31, 327–343.
Grisafi, F., Brucato, A., and Rizzuti, L. (1994). “Solid liquid mass transfer coefficients in mixing tanks: Influence of sidewall roughness.” Inst. Chem. Eng. Symp. Ser., 136, 571–578.
Hemarajani, R. R., and Tatterson, G. B. (2004). Handbook of industrial mixing: Science and practice, Wiley, New York, 345–361.
Henze, M., and Harremoes, P. (1983). “Anaerobic treatment of wastewater in fixed film reactors: a literature review.” Water Sci. Technol., 15, 1–101.
Houcine, L., Plasari, E., and David, R. (2000). “Effects of the stirred tank’s design on power consumption and mixing time in liquid phase.” Chem. Eng. Technol., 23(7), 605–613.
Horvath, I. (1984). Modeling in the technology of wastewater treatment, Peragmon, New York.
Hsieh, C.-C. (1991). “Estimating volatilization rates and gas/liquid mass transfer coefficients in aeration systems.” Ph.D. thesis, Univ. of California, Los Angeles, Calif.
Johnson, A. I., and Huang, C.-J. (1956). “Mass transfer studies in an agitated vessel.” AIChE J., 2, 412–419.
Johnstone, R. E., and Thring, M. W. (1957). Pilot plants models and scale-up methods in chemical engineering, McGraw-Hill, New York.
King, R. L., Hiller, R. A., and Tatterson, G. B. (1988). “Power consumption in a mixer.” AIChE J., 34, 506–509.
Maise, G. (1970). “Scaling methods for surface aerators.” J. Sanit. Engrg. Div., 96(5), 1079–1083.
Metcalf & Eddy. (2004). Waste water engineering: treatment disposal and reuse, Tata McGraw-Hill, New Delhi, India.
Mietzner, A. B., and Pigford, R. L. (1958). Scale-up in practice, R. Fleming, ed., Reinhold, New York.
Nagata, S. (1975). Mixing principles and applications, Wiley, New York.
Nienow, A. W., Hunt, G., and Buckland, B. C. (1994). “A fluid dynamics study of retrofitting of large agitated bioreactors: Turbulent flow.” Biotechnol. Bioeng., 44, 1177–1185.
Nienow, A. W., and Ulbrecht, J. J. (1985). Mixing of liquids by mechanical agitation, J. J. Ulbrecht and G. K. Patterson, eds., Chap. 6, Gordon and Breach, New York, 203–237.
Oosterhuis, N. M. G., and Kossen, N. W. F. (1981). “Power input measurements in a production scale bioreactor.” Biotechnol. Lett., 3, 645–650.
Perry, R. H., Green, D. W., and Malony, J. O., eds. (1984). Perry’s chemical engineers’ handbook, 6th Ed., McGraw-Hill, New York.
Rao, A. R. K. (1999). “Prediction of reaeration rates in square, stirred tanks.” J. Environ. Eng., 125(3), 215–233.
Rao, A. R. K., Bharathi Laxmi, B. V., and Narasiah, K. S. (2004). “Simulation of oxygen transfer rates in circular aeration tanks.” Water Qual. Res. J. Canada, 39(3), 237–244.
Richardson, D. V. (1982). Rotating electric machinery and transformer technology, 2nd Ed., Prentice-Hall, Reston, Va.
Rushton, J. H. (1952). “Applications of fluid mechanics and similitude to scale-up problems—Part 1.” Chem. Eng. Prog., 48 33–38.
Rushton, J. H., Costich, E. W., and Everett, H. J. (1950). “Power characteristics of mixing impellers.” Chem. Eng. Prog., 9, 395–450.
Saravanan, K., Mundale, V. D., Patwardhan, A. W., and Joshi, J. B. (1996). “Power consumption in gas-inducing-type mechanically agitated contactors.” Ind. Eng. Chem. Res., 35(5), 1583–1602.
Udaya Simha, L., Sarma, K. V. N., and Rao, A. R. K. (1991). “Effect of geometrical parameters for overall Oxygen transfer coefficient.” Proc., Symp. on Environmental Hydraulics, University of Honking, Hong Kong, 1577–1581.
Uhl, V. W., and Gray, J. B. (1966). Mixing: Theory and practice, Academic, New York.
Weinstein, B., and Treybal, R. B. (1973). “Liquid-liquid contacting in unbaffled, agitated vessels.” AIChE J., 19(2), 304–312.
Wesner, G. M. (1977). “Energy conservation in municipal wastewater treatment.” U.S. EPA Rep. No. PB81-165391, Washington, D.C.
Information & Authors
Information
Published In
Copyright
© 2009 ASCE.
History
Received: Nov 14, 2005
Accepted: Jul 1, 2008
Published online: Jan 1, 2009
Published in print: Jan 2009
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.