liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
Kappa Control with Online Analyzer Using Samples from the Digester's Mid-phase
Linköping University, Department of Electrical Engineering.
2004 (Swedish)Independent thesis Basic level (professional degree)Student thesis
Abstract [en]

In the pulp industry, digesters are used to disolve lignin in wood chips. The concentration of lignin is measured and is called the Kappa number. In this thesis, the question of whether an online Kappa sensor, taking samples from the mid-phase of the digester, is useful or not is analyzed. For the samples to be useful, there has to be a relationship between the measured Kappa at the mid- phase and the measured Kappa in the blowpipe at the bottom of the digester. An ARX model of the lower part of the digester has been estimated. Despite a lot of noise, it seems that it might be possible to use the mid-phase samples and for this model predict the blowpipe flow Kappa signal. It is concluded that the mid-phase samples should be further improved to be more useful. The mid-phase samples have also been used in another ARX model, this time to LP-filter these values without time loss.

Another important issue has been to examine if the existing controller is good or not. In order to be able to compare it with other controllers, a simulator has been created in MATLAB - Simulink. Test results from this simulator show that the existing controller's use of the mid-phase Kappa samples improves its performance. For a simplified digester model, the existing controller has also been compared with an MPC controller. This test shows that the MPC controller is significantly better. Hence, the conclusion in this thesis is that it might be interesting to study MPC further using a more advanced model.

Place, publisher, year, edition, pages
Institutionen för systemteknik , 2004. , 78 p.
LiTH-ISY-Ex, 3469
Keyword [en]
Reglerteknik, Kappa Control, Digester Control, Mid-phase Measurement, Online Kappa Analyzer, System Identification, Model Predictive Control
Keyword [sv]
National Category
Control Engineering
URN: urn:nbn:se:liu:diva-2209OAI: diva2:19539
Available from: 2004-03-02 Created: 2004-03-02

Open Access in DiVA

fulltext(683 kB)766 downloads
File information
File name FULLTEXT01.pdfFile size 683 kBChecksum SHA-1
Type fulltextMimetype application/pdf

By organisation
Department of Electrical Engineering
Control Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 766 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 373 hits
ReferencesLink to record
Permanent link

Direct link