CFD model for the combustion of sewage sludge powder

This upload is supplement to the publication:

"Computationally Inexpensive CFD Approach for the Combustion of Sewage Powder, Including the Consideration of Water Content and Limestone Additive Variations" [1]

Abstract from the publication: 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. 

HOW TO USE THE ANSYS FLUENT MODEL

1) Read .cas.h5 file in FLUENT

2) Read the examplary pre-tabulated chemistry data (PDF_example) or create your own data using heptane42.che [2] and change boundary conditions accordingly

3) Run the calculation to obtain the solution data

Three meshes and the biot-number UDF are provided.

The settings file can be used to transfer settings to another case fast.

[1] B. Ortner et al. Computationally Inexpensive CFD Approach for the Combustion of Sewage Powder, Including the Consideration of Water Content and Limestone Additive Variations

Energies 2023, 16(4), 1798

[2] M. Bui-Pham, K.S. Comparison between Experimental Measurements and Numerical Calculations of the Structure of Heptane-Air 757

Diffusion Flames. Combustion Science and Technology 1991, 74, 293–310.