The Method of Calculations of the （的方法计算的）.pdf

Archives of Hydro-Engineering and Environmental Mechanics Vol. 51 (2004), No. 4, pp. 371–385 The Method of Calculations of the Sedimentation Efficiency in Tanks with Lamella Packets Włodzimierz P. Kowalski AGH – University of Science and Technology, Cracow, Poland, Faculty of Mechanical Engineering and Robotics, al. Mickiewicza 30, 30-059 Kraków, e-mail: wkowalsk@agh.edu.pl (Received May 12, 2004; revised July 02, 2004) Abstract The paper outlines a method to determine the sedimentation efficiency in modernized tanks with incorporated lamella packets. The method takes into account the prop- erties of the suspension (density, viscosity, solid phase distribution) and tank design parameters – flow intensity and settling surface. Several types of grain size distribu- tions are considered: the log-normal distribution and generalised gamma distribution. The sedimentation efficiency is investigated in relation to the ratio of tank filling with lamella packets. The lamella ring width in a round Dorr clarifier is taken as an example. The analysis is performed by way of computer simulations. The ap- plied calculation procedure was extensively verified in laboratory tests, pilot tests and industrial-scale tests (Kowalski 2000) and the obtained results were regarded as satis- factory. The error involved in calculations of the sedimentation efficiency is less than 0.05 when the efficiency value exceeds 0.8. Key words: sedimentation efficiency, lamella tank, traditional tank with lamella modules Nomenclature D – diameter of the round tank, d – equivalent particle size (diameter),