mdh.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Process Modeling of Combustion and Digesters for On-line Applications
Mälardalen University, School of Business, Society and Engineering, Future Energy Center. (FEC/MERO)ORCID iD: 0000-0001-8191-4901
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of biomass has increased in recent years due to the efforts to reduce the high emissions of greenhouse gases, primarily carbon dioxide from combustion of fossil fuels. At the same time industrial processes have become more complex because of increased production rates and profitability requirements. A higher degree of automation is needed when the processes are too complex to be handled manually. There is a need to find modeling strategies that can automatically handle the challenges that the conversion of biomass in an industrial process entails, such as operational changes, decreasing component and overall system efficiency, drifting sensors, etc. The objective of this thesis is to develop a methodology for on-line applications in industrial processes. Dynamic process models have been developed for continuous digesters and boilers. Process models have been evaluated for their use in continuous industrial process. Applications that have been studied are monitoring and diagnostics, advanced control and decision support. The process models are designed for on-line simulations. The results shows that the use of mathematical simulation models can improve the use of both process data and process understanding, to achieve improved diagnostics, advanced control and process optimization. In the two examples of industrial processes covered in this thesis, we can see that similar types of models can be used for completely different types of processes, such as pulp digesters and boilers. It also demonstrates the ability to combine soft sensors and hard sensors with physical models to take the information to a higher level of utilization.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2015.
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 194
National Category
Energy Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-29462ISBN: 978-91-7485-244-8 (print)OAI: oai:DiVA.org:mdh-29462DiVA: diva2:868788
Public defence
2015-12-15, R2-025, Mälardalens högskola, Västerås, 08:15 (English)
Opponent
Supervisors
Available from: 2015-11-12 Created: 2015-11-11 Last updated: 2015-11-25Bibliographically approved
List of papers
1. Use of combined physical and statistical models for online applications in the pulp and paper industry
Open this publication in new window or tab >>Use of combined physical and statistical models for online applications in the pulp and paper industry
2009 (English)In: Mathematical and Computer Modelling of Dynamical Systems, Vol. 15, no 5, 425-434 p.Article in journal (Refereed) Published
Abstract [en]

This paper discusses the accuracy of different types of models. Statistical models are based on process data and/or observations from lab measurements. This class of models are called black box models. Physical models use physical relationships to describe a process. These are called white box models or first principle models. The third group is sometimes called grey box models, being a combination of black box and white box models. Here we discuss two examples of model types. One is a statistical model where an artificial neural network is used to predict NOx in the exhaust gases from a boiler at Mlarenergi AB in Vsters, Sweden. The second example is a grey box model of a continuous digester. The digester model includes mass balances, energy balances, chemical reactions and physical geometrical constraints to simulate the real digester. We also propose that a more sophisticated model is not required to increase the accuracy of the predicted measurements.

Keyword
statistical models; physical models; pulp digester
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-7590 (URN)10.1080/13873950903375403 (DOI)000274741800003 ()2-s2.0-75349089565 (Scopus ID)
Available from: 2009-11-29 Created: 2009-11-29 Last updated: 2015-11-12Bibliographically approved
2. New Methods for Adaptation to Degeneration in Process Models for Process Industries
Open this publication in new window or tab >>New Methods for Adaptation to Degeneration in Process Models for Process Industries
2009 (English)In: Chemical Product and Process Modeling, Vol. Vol. 4, no : Iss. 1, , Article 25.- p.Article in journal (Refereed) Published
Abstract [en]

The implementation of model-based control and diagnostics suffer strongly from the fact that models deteriorate as a function of process and sensor deterioration. Also, changes in the raw material (i.e. wood) may occur and often the process control is not addressing these variations in reality. It is thus vital for the model system to be robust in the sense that it is transparent and easy for the operator to maintain. Robustness is essential in many parts of the system, including measurement, process model validation, the ability of the model to adapt to changes in the process, optimization algorithms, and of course the model itself. In this paper, we first show three real-life applications of the utilization of models for diagnostics and control. Thereafter conditions for on-line adaptation of the models are discussed. The challenges when designing such a system are in achieving operator confidence, filtering of misleading measured data, adaptation of process parameters when the process parameters change, and combining validation of measurements and process models. These challenges are met by using a combination of physical and statistical models and methods based on them such as model predictive control (MPC) and parameter estimation. The model should be maintained by a qualified engineer who should be able to explain the system to the operator so that it is understood and confidence can be maintained.

Place, publisher, year, edition, pages
Berkley Electronic Press, 2009
Keyword
simulation, model based control, MPC, power boiler
National Category
Chemical Process Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-8011 (URN)10.2202/1934-2659.1127 (DOI)2-s2.0-77954559066 (Scopus ID)
Projects
Värmeforskproject on model based control of boiler
Available from: 2010-02-10 Created: 2010-02-10 Last updated: 2015-11-12Bibliographically approved
3. On-line simulation of continuous pulp digester
Open this publication in new window or tab >>On-line simulation of continuous pulp digester
2009 (English)In: TAPPSA JournalArticle in journal (Refereed) Published
Abstract [en]

Continuous cooking is the dominant process in the kraft pulping industry.  Our general knowledge and understanding of process conditions inside the digester is limited. Process control systems comprise of groups of measurements, which give information about conditions at the outer shell of the digester.  These measurements mostly tell about cooking liquor inflows and outflows, temperature and it is also possible to measure pressure or pressure difference at the screen section of the digester shell.  But ultimately process conditions inside the digester are based on measurements at the shell and intelligent approximations.

 

The aim of this paper is to describe more accurately the cooking conditions and phenomena inside the digester.  A model of a continuous digester was developed as an extension of the well known Purdue model [Bhartiya, 2003].  The model was adapted to simulate an industrial Lo-Solids pulp digester as well as an ITC digester.  The models were then used to do online predictions and these predictions were compared with the actual plant performance.

Keyword
modelling, simulation, on-line, pulp digester
National Category
Paper, Pulp and Fiber Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-8005 (URN)
Projects
KKS Use of statistical and physical models for on-line optimization
Available from: 2010-02-10 Created: 2010-02-10 Last updated: 2015-11-12Bibliographically approved
4. Dynamic simulation of fouling in a circulating fluidized biomass fired boiler
Open this publication in new window or tab >>Dynamic simulation of fouling in a circulating fluidized biomass fired boiler
2011 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 5, 1813-1824 p.Article in journal (Refereed) Published
Abstract [en]

A dynamic model is presented for a biomass-fired circulating fluidized bed boiler. The model is based on energy and mass balances for the components in the boiler and on a combustion model for the fluidized bed. The main purpose of the model is to simulate how deposits affect the boiler efficiency and performance. The model is verified against the municipal circulating fluidized bed boiler in Vasteras, Sweden, which produces 157 MW. The distribution of deposits on the surfaces in the boiler is well known from inspections. These observations are used as inputs to the model to simulate their effects on boiler performance. The heat exchanger most affected by fouling is Superheater 2, which is the first heat exchanger in the flue gas channel. Deposits typically reduce the heat transfer rate by half over a season despite soot blowing. This and other fouling scenarios are simulated and presented in this article. The simulations show that fouling on superheaters redistributes the heat transfer rate from the superheaters to Reheater 1 and partially redistributes turbine power from the high pressure turbine to the intermediate pressure turbine. If the boiler is running at maximum load, water injection to Reheater 1 has to increase to maintain temperatures below the permitted limit. The dynamic effects of fouling are small and the total efficiency of the boiler is only marginally affected. Fouling on evaporating surfaces has major dynamic effects and dramatically decreases the boiler efficiency. A decrease in fuel rate flow is needed to maintain temperatures in the fluidised bed and in the flue gas channel within acceptable limits.

National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-13209 (URN)10.1016/j.apenergy.2010.12.006 (DOI)000288360500038 ()2-s2.0-79551537174 (Scopus ID)
Available from: 2011-10-28 Created: 2011-10-28 Last updated: 2015-11-12Bibliographically approved
5. Use of modelica for “multi phase flow” in complex systems, with application for continuous pulp digesters
Open this publication in new window or tab >>Use of modelica for “multi phase flow” in complex systems, with application for continuous pulp digesters
2009 (English)In: Proceedings of APMMCT. Kleminski, Ukraine,  May 17-18, 2005., 2009Conference paper, (Refereed)
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-23763 (URN)
Conference
APMMCT. Kleminski, Ukraine, May 17-18, 2005.
Available from: 2013-12-19 Created: 2013-12-19 Last updated: 2015-11-12Bibliographically approved
6. Moisture content determination of biomass fuel supported by Bayesian network
Open this publication in new window or tab >>Moisture content determination of biomass fuel supported by Bayesian network
2006 (English)In: Proceedings of  IFAC conference at Bali, ASCC 2006. July 2006., 2006Conference paper, (Refereed)
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-23999 (URN)
Conference
IFAC conference at Bali, ASCC 2006. July 2006.
Available from: 2013-12-23 Created: 2013-12-23 Last updated: 2015-11-12Bibliographically approved
7. Applications of simulation models for diagnostics and model based control in pulp and paper and power plant applications
Open this publication in new window or tab >>Applications of simulation models for diagnostics and model based control in pulp and paper and power plant applications
2009 (English)Conference paper, (Refereed)
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-23765 (URN)
Conference
Mathmod 2009, February 4-7 in Vienna
Available from: 2013-12-19 Created: 2013-12-19 Last updated: 2015-11-12Bibliographically approved
8. Time based data reconciliation and decision support for a CFB boiler
Open this publication in new window or tab >>Time based data reconciliation and decision support for a CFB boiler
2009 (English)In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2009 / [ed] Yrjö Majanne, Tampere: Tampere University Press , 2009, 338-343 p.Conference paper, (Refereed)
Abstract [en]

This paper covers a method for operator decision support, where physical simulation models are used to connect different physical variables to each other. By comparing energy and material balances for a larger process area inconsistencies in single process parts and sensor measurements can be detected, by following the development between single measurements and values predicted from the simulations. This information then can be used as input to e.g. a BN, Bayesian Network, for decision support. The application has been for a CFB boiler at Mälarenergi AB. The simulators have been made in Modelica respectively a more advanced model in APROS.

Place, publisher, year, edition, pages
Tampere: Tampere University Press, 2009
Keyword
Dynamic data-reconciliation, sensor diagnostics, process performance monitoring, decision support
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Energy Engineering Control Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-8013 (URN)
Conference
IFAC Symposium on Power Plants and Power Systems Control, PP and PSC 2009; Tampere; Finland; 6 July 2009 through 8 July 2009
Available from: 2010-02-10 Created: 2010-02-10 Last updated: 2015-11-12Bibliographically approved
9. Fluidized bed combustion and gasification modeling and utilization of the models for diagnostics, control and decision support
Open this publication in new window or tab >>Fluidized bed combustion and gasification modeling and utilization of the models for diagnostics, control and decision support
2009 (English)In: Proceedings Mathmod 2009, February 4-7 in Vienna., 2009Conference paper, (Refereed)
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-24000 (URN)
Conference
Mathmod 2009, February 4-7 in Vienna.
Available from: 2013-12-23 Created: 2013-12-23 Last updated: 2015-11-12Bibliographically approved

Open Access in DiVA

fulltext(1390 kB)152 downloads
File information
File name FULLTEXT02.pdfFile size 1390 kBChecksum SHA-512
a15f2dbf2dc5fdd5c4393636d745ed4ba900086ee18130926ba3aadcf72159c5dc5c418cbcc872146dce00e9bd1e71243df9384156ac96629449b6187181e5b9
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Avelin, Anders
By organisation
Future Energy Center
Energy Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 152 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: 449 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf