Determining the thickness of sludge on the heat exchanger tube inside an anaerobic digester

¹ Faculty of Management and Computer Modelling, Kielce University of Technology, al.Tysiąclecia P.P. 7, 25-314 Kielce, Poland
² Faculty of Civil and Environmental Engineering, Bialystok University of Technology, ul.Wiejska 45E, 15-351 Białystok, Poland

^* Corresponding author: hozej@tu.kielce.pl

Published online: 28 June 2019

Abstract

The paper presents a simplified method of determining the thickness of sludge on the walls of the heat exchanger piping in a biogas plant digester. The evaluation of the thickness of a sludge layer is based on the biogas plant operation parameters, including the inlet and outlet temperature of the heat exchanger, mass flow and the geometric characteristics of the heat exchanger and physical parameters of the substrate working inside a fermentation chamber. Measurement of the thickness of the sludge layer on the walls of a heat exchanger is only possible at the time of general cleaning of a digester, which necessitates switching off the biogas plant operation. The paper compares the results of predictions with experimental data of the work of a biogas plant digester located in north-eastern Poland, in Ryboły. The presentation of the obtained numerical results is supplemented by the uncertainty analysis. The significance of undertaking such research lies in its applicational aspects, as during the operation of a biogas plant sludge accumulates on the walls of a digester, which provides additional thermal resistance and reduces the thermal efficiency of the heat exchanger.