Computationally Inexpensive CFD Approach for the Combustion of Sewage Sludge Powder, Including the Consideration of Water Content and Limestone Additive Variations

Benjamin Ortner (), Christian Schmidberger, Hannes Gerhardter, René Prieler, Hartmuth Schröttner and Christoph Hochenauer
Additional contact information
Benjamin Ortner: Institute of Thermal Engineering, Faculty of Mechanical Engineering and Economic Sciences, Graz University of Technology, Inffeldgasse 25B, 8010 Graz, Austria
Christian Schmidberger: Institute of Combustion and Power Plant Technology, Faculty 4-Energy-, Process- and Bio-Engineering, University of Stuttgart, Pfaffenwaldring 23, 70569 Stuttgart, Germany
Hannes Gerhardter: Institute of Thermal Engineering, Faculty of Mechanical Engineering and Economic Sciences, Graz University of Technology, Inffeldgasse 25B, 8010 Graz, Austria
René Prieler: Institute of Thermal Engineering, Faculty of Mechanical Engineering and Economic Sciences, Graz University of Technology, Inffeldgasse 25B, 8010 Graz, Austria
Hartmuth Schröttner: Austrian Centre for Electron Microscopy and Nanoanalysis, Steyrergasse 17, 8010 Graz, Austria
Christoph Hochenauer: Institute of Thermal Engineering, Faculty of Mechanical Engineering and Economic Sciences, Graz University of Technology, Inffeldgasse 25B, 8010 Graz, Austria

Energies, 2023, vol. 16, issue 4, 1-25

Abstract: As a result of growing interest in the thermal treatment of sewage sludge with methods such as combustion, gasification or pyrolysis, and also in processes that aim to recover precious components such as phosphorus from this waste, a growing demand has been observed for Computational Fluid Dynamics (CFD) models that provide solutions rapidly and accurately for efficient application in research and development. This study was carried out to develop a computationally inexpensive modelling approach for the combustion of pulverized sewage sludge in entrained flow furnaces. Sewage sludge is a very volatile-rich fuel. Therefore, the Steady Diffusion Flamelet model (SFM), in combination with a validated skeletal reaction mechanism, was applied to consider the pulverized firing of sewage sludge. It was possible to represent the complex composition of volatiles emitted from the sludge particles by releasing surrogate fuels. In addition, the influence of limestone additive (calcination reaction) and varying water content (water–gas shift reaction) was investigated experimentally and modelled via CFD. The simulation results confirm that the surrogate fuel approach is valid and can be used to describe pulverized sewage sludge effectively. The temperature and species concentration results, including the influence of the additive and different levels of water content, were confirmed by experimental data, which is usually hard to obtain due to the tendency of PSS to form agglomerates in entrained flow combustion furnaces. The model yields plausible and experimentally validated results for the combustion of sewage sludge powder across a wide range of operating conditions.

Keywords: sewage sludge combustion; flamelet modelling; entrained flow furnace (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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