Congratulations to Lena Hensch on the defence of her diploma thesis

We would like to congratulate Ms Lena Hensch on the successful defence of her diploma thesis on "Creation of a mathematical model to determine nitrous oxide and nitrogen oxide emissions during thermal sewage sludge treatment in fluidised bed furnaces".  The thesis was supervised by Dr Daniel Bernhardt and was rated as excellent by the reviewers with a grade of 1.0.

In this research project, a mathematical model was developed to analyse the emissions of nitrous oxide (N2O) and nitrogen oxides (NOx) during the thermal treatment of sewage sludge in fluidised bed furnaces. The starting point for the model development was an existing model, which was extended to meet the specific requirements. In addition, selected primary measures for reducing nitrous oxide were integrated into the model.

Five reaction mechanisms were researched for the detailed modelling of sewage sludge incineration and in particular the formation of N2O and NOx. The preferred variant for the calculation model was determined by comparing these mechanisms. The evaluation of the predicted emissions and the validation of the model were carried out using measurement data from a real industrial-scale sewage sludge plant.

None of the mechanisms researched was able to model both N2O and NOx in accordance with the measured values. Therefore, a mechanism was derived from two selected variants that modelled the qualitative and quantitative trends of N2O and NOx formation in acceptable agreement with the measured values.

Finally, using the identified suitable reaction mechanism, demonstrative simulations were carried out to estimate the potential of selected primary measures to reduce N2O and NOx emissions. An increase in temperature through the combustion of an additional fuel in the free space, air staging and a combination of both measures were analysed.

We are delighted to welcome Mrs Hensch to the EVT team from mid-February. She will remain true to her subject and continue her research activities in the High Temperature Process Engineering research area headed by Dr Daniel Bernhardt. From now on, Mrs Hensch will be involved in a project of the current RefoPlan 22 research contract of the Federal Environment Agency entitled "Determination of still existing climate protection potentials in thermal sewage sludge treatment".