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Operating charts for continuous sedimentation I: Control of steady states

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Abstract

The industrial process of continuous sedimentation of solid particles in a liquid takes place in a clarifier-thickener unit, which is a large tank with a feed inlet somewhere in the middle and outlets at the top and bottom. For half a century the constitutive assumption by Kynch has provided a platform from which steady-state mass-balance considerations have been used to obtain rules and graphical tools for prediction of steady-state situations, design and control. This is often referred to as the `solids-flux theory' containing such key words as the `operating line', `state point' and `limiting flux'. The basic assumptions of the solids-flux theory yield a nonlinear partial differential equation that models the entire process. Since unique physically relevant solutions can now be obtained, the knowledge of these is used to establish and extend the solids-flux theory. Detailed information on all steady-state solutions and the control of these by adjusting a volume flow is presented by means of operating charts. Most of these are concentration-flux diagrams with information on, for example, how to perform a control action to fulfil a certain control objective formulated in terms of the output variables in steady state.

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  1. School of Technology and Society, Malmö University, S-205 06, Malmö, Sweden

    Stefan Diehl

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Diehl, S. Operating charts for continuous sedimentation I: Control of steady states. Journal of Engineering Mathematics 41, 117–144 (2001). https://doi.org/10.1023/A:1011959425670

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