Master’s thesis ”Estimation of Urea Dosage in an SCR Unit”, was completed


M. Sc. (Chemical Engineering) Ludvig Sandell’s Master’s thesis ”Estimation of Urea Dosage in an SCR Unit”, was completed at the Åbo Akademi University in the autumn of 2021. The thesis is part of the Clean Propulsion Technologies project’s WP2 ’Virtual sensors and control.

Sandell is born and raised in Kokkola. He studied chemical engineering at the Åbo Akademi University (ÅAU) and graduated with his M.Sc. last September with a major in process and systems engineering. In his thesis, Sandell developed a physics-based dynamic model of the urea dosing system in an SCR, as well as a nonlinear state estimator to replace a noisy flow rate sensor in the system.

“I found building a model of a real-life process from scratch to be interesting. I also enjoyed learning about state estimation and Kalman filters in more depth” Sandell says.

According to Sandell, hysteresis and other nonideal behaviors found in control valves proved very difficult to model accurately. Further research would be needed in this area to improve the usability of the model and estimator in real-life applications.

Sandell hopes that the results have been of use in the next stage of the Clean Propulsion Technologies project involving the application of model predictive control on the SCR system. Sandell’s supervisor University Lecturer Jari Böling (ÅAU) commented that extending the theory of unknown input estimation to nonlinear systems was interesting from a broader research perspective.

Since mid-November Sandell has been employed by Academic Work, working at Metso Outotec in Espoo. “I work with dynamic modelling and simulation of hydrometallurgical processes. The experience I gained working on my thesis has come in handy in my new job, and it was also a major contributor to me getting it”, says Sandell.