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Level Control of Flotation Tanks at LKAB: Control Design and Robustness Analysis
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
1990 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesisAlternative title
Nivåreglering av flotationstankar på LKAB : Reglerdesign och robusthetsanalys (Swedish)
Abstract [en]

Flotation is one part of LKAB's refining process where minerals are separated from iron ore in cascade connected tanks. A good level control in the flotation tanks is vital to get a high recovery of the iron. Nominal and robust performance of different level controllers are compared in the study. Robust performance is analyzed for uncertainties in valve contants and for hysteresis in the valves. The results show that LQG control give better nominal performance than PI control. The robust performance is worse for the LQG controller than the PI controller for modelled uncertainties in valve contants. The robustness analysis shows also that LQG control is less sensitive to hysteresis in the valves compared to PI control. Thus, type of uncertainty affects different control strategies differently. 

Abstract [sv]

Flotation är en del av LKAB:s förädlingsprocess där mineraler separeras från järnmalmen i seriekopplade tankar. En god nivåhållning i flotationstankarna är viktigt för att erhålla ett högt järnutbyte. Olika reglerstrategiers nominella och robusta prestanda jämförs i studien. Robust prestanda undersöks vid osäkerhet i ventilkonstanter och hysteres i ventiler. Resultaten visar att LQG-reglering ger bättre nominell prestanda än PI-reglering. Den robusta prestandan vid osäkerhet i ventilkonstanter är sämre för LQG-reglering jämfört med PI-reglering. Robusthetsanalysen visar även att LQG-regulatorn är mindre känslig för hysteres i ventiler än PI-regulatorn. Typen av osäkerhet inverkar sålunda olika på olika reglerstrategier.

Place, publisher, year, edition, pages
1990. , 74 p.
UPTEC F, ISSN 1401-5757 ; 16003
Keyword [en]
Control Theory, Flotation, Level Control
Keyword [sv]
Reglerteknik, Flotation, Nivåreglering
National Category
Information Systems
URN: urn:nbn:se:uu:diva-279807OAI: oai:DiVA.org:uu-279807DiVA: diva2:908969
Educational program
Master Programme in Engineering Physics
Available from: 2016-03-04 Created: 2016-03-03 Last updated: 2016-03-04Bibliographically approved

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