Change search
Link to record
Permanent link

Direct link
BETA
Stenlund, Benny
Publications (4 of 4) Show all publications
Stenlund, B. & Medvedev, A. (2002). Level control of cascade coupled flotation tanks (ed.). Paper presented at IFAC Workshop on Future Trends in Automation of the Mineral and Metal Processing (MM 2000), Finland, 22-24 August 2000. Elsevier IFAC Publications / IFAC Proceedings series, 33(22), 185-190
Open this publication in new window or tab >>Level control of cascade coupled flotation tanks
2002 (English)In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 33, no 22, p. 185-190Article in journal (Refereed) Published
Abstract [en]

At the Boliden's concentrator in Aitik, bulk flotation constitutes an important part of the process for extracting valuable minerals from the ore. A series of flotation cells consists of five tanks connected in cascade with control valves between the tanks and a slowly varying flow of mineral slurry into the first tank. This paper deals with a comparative study of control strategies for level control in a flotation series in Aitik. The aim is to show the potential performance improvements taking into account couplings between the process state variables. Two control strategies are considered; a decoupling controller and a linear quadratic (LQ) optimal multivariable controller. Experiments with both structures show a significant enhancement of the level control performance as compared to the original SISO design

National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-63548 (URN)10.1016/S1474-6670(17)36989-6 (DOI)
Conference
IFAC Workshop on Future Trends in Automation of the Mineral and Metal Processing (MM 2000), Finland, 22-24 August 2000
Note

Validerad; 2002; 20080602 (cira)

Available from: 2017-05-26 Created: 2017-05-26 Last updated: 2017-11-29Bibliographically approved
Stenlund, B. & Medvedev, A. (2002). Level control of cascade coupled flotation tanks (ed.). Control Engineering Practice, 10(4), 443-448
Open this publication in new window or tab >>Level control of cascade coupled flotation tanks
2002 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 10, no 4, p. 443-448Article in journal (Refereed) Published
Abstract [en]

At the Boliden's concentrator in Aitik, bulk flotation constitutes an important part of the process for extracting valuable minerals from the ore. A series of flotation cells consists of five tanks connected in cascade with control valves between the tanks and a slowly varying flow of mineral slurry into the first tank. This paper deals with a comparative study of control strategies for level control in a flotation series in Aitik. The aim is to show the potential performance improvements taking into account couplings between the process state variables. Two control strategies are considered; a decoupling controller and a linear quadratic (LQ) optimal multivariable controller. Experiments with both structures show a significant enhancement of the level control performance as compared to the original SISO design

National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-13961 (URN)10.1016/S0967-0661(01)00103-4 (DOI)000174767100008 ()2-s2.0-0036531920 (Scopus ID)d47681a0-30ab-11dd-9729-000ea68e967b (Local ID)d47681a0-30ab-11dd-9729-000ea68e967b (Archive number)d47681a0-30ab-11dd-9729-000ea68e967b (OAI)
Note

Validerad; 2002; 20080602 (cira)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Stenlund, B. (2002). Model-based control and monitoring of the flotation process (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Model-based control and monitoring of the flotation process
2002 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In the mineral processing industry, flotation constitutes the most important technique for extraction of the valuable minerals from the ore. This process involves both chemical and physical parts, the theory of which are not yet completely understood. Recently, extensive research has been performed to increase the efficiency of the flotation stage, bearing in mind the potential for increased profit this would imply for the plant. Typically, a flotation control system is built in a hierarchical manner, where a supervisory system is generating set points to local basic loop controllers. It is then assumed that these local control loops are working perfectly well, an assumption which is very often violated. The reason for this can to a great extent be found in the complex nature of the flotation process with strong nonlinearities, strong interactions between process states, mechanical problems etc. The commonly used control strategy, with distributed PI or PID controllers, generally performs badly under such circumstances, regardless of how they are tuned. In this thesis, the control of pulp levels in a flotation bank consisting of cascade coupled flotation cells is considered. The existing PI-based SISO strategy is replaced by multivariable controllers showing a significant increase in performance. A related problem is the functional status of the control valves between the tanks, which strongly affects the control performance actually achieved. Therefore, as a second part of this project, a method to supervise a linearized valve model is proposed. Control performance, in terms of the deviation of the estimated parameters from the nominal ones, is discussed for one of the proposed multivariable control strategies. The other subject discussed in the thesis is the area of recursive estimation. A new method to avoid windup in case of poor process excitation is suggested. The proposed algorithm is computationally simple and, in comparison to many other algorithms proposed in the literature, intuitive to tune since one directly decides the accuracy of the parameter estimates. The last property is highly desirable in \eg fault diagnosis, where one often wants to keep a constant false alarm rate (FAR).

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2002. p. 95
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2002:32
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-26418 (URN)e2809300-c426-11db-9ea3-000ea68e967b (Local ID)e2809300-c426-11db-9ea3-000ea68e967b (Archive number)e2809300-c426-11db-9ea3-000ea68e967b (OAI)
Note

Godkänd; 2002; 20070224 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-24Bibliographically approved
Stenlund, B. (2001). Supervision of Control Valves in a Series of Cascade Coupled Flotation Tanks. Paper presented at 4th IFAC Workshop on On-Line Fault Detection and Supervision in the Chemical Process Industries 2001, Jejudo Island, Korea, 7-8 June 2001. Elsevier IFAC Publications / IFAC Proceedings series, 34(27), 57-62
Open this publication in new window or tab >>Supervision of Control Valves in a Series of Cascade Coupled Flotation Tanks
2001 (English)In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 34, no 27, p. 57-62Article in journal (Refereed) Published
Abstract [en]

In this paper an algorithm for supervision of control valves in a series of cascade coupled flotation tanks is presented. The benefit of such an algorithm is that it enables monitoring of the plant control system performance and detection of malfunctions in the control valves at an early stage.

National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-63470 (URN)10.1016/S1474-6670(17)33568-1 (DOI)
Conference
4th IFAC Workshop on On-Line Fault Detection and Supervision in the Chemical Process Industries 2001, Jejudo Island, Korea, 7-8 June 2001
Available from: 2017-05-22 Created: 2017-05-22 Last updated: 2019-05-06Bibliographically approved
Organisations

Search in DiVA

Show all publications