Validation and Optimization of an Equilibrium Model of a Hot-Lime-Softening Treatment System
Publication: Journal of Environmental Engineering
Volume 137, Issue 3
Abstract
This paper describes the development and validation of an equilibrium model of an industrial hot-lime-softening boiler-water-treatment unit for a large-scale nickel processing facility in which approximately 6.6 ML per hour of water is processed. In the industrial process, multiple water sources of varying quality are combined before the softening treatment, which makes control and optimization of the softening unit complicated and has brought about the necessity of a robust numerical model of water treatment. In this paper, the numerical thermodynamic and adsorption relations describing the softening treatment process are presented. Lime, magnesia, and soda ash additions are modeled. Emphasis has been placed on calcium, magnesium, and silica treatments as these are of most relevance to the industry. Jar tests described in this paper are used to determine adsorption relations, estimate statistical uncertainties, validate the model performance, and optimize the model parameters. Parameter estimations for equilibrium constants are undertaken and provide insights into the range of model validity and interactions between additions and softened water quality. Further jar testing is utilized to evaluate the effectiveness of using the model to numerically derive optimal chemical additions.
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Acknowledgments
The writers would like to thank B.H.P. Billiton and Q.N.I. Yabulu for their valuable input and financial and material support for this work.
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 137 • Issue 3 • March 2011
Pages: 205 - 212
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Sep 17, 2009
Accepted: Aug 16, 2010
Published online: Aug 18, 2010
Published in print: Mar 1, 2011
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