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Potential energy improvements in a multiple-effect evaporation system: Case studies of heat recovery
Store Enso Pulp & Paper Asia AB, Karlstad Res Ctr, POB 9090, SE-65009 Karlstad, Sweden..
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).ORCID iD: 0000-0002-5864-4576
2016 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 4, p. 583-591Article in journal (Refereed) Published
Abstract [en]

The primary objective of this study was to quantify the amount of excess energy that is present in the evaporation system of an integrated pulp and paper-board mill and to analyze a number of energy recovery cases. These focus on improving the energy efficiency in the evaporation plant and are mainly based on the process data of performance tests from the full-scale production site. A computer script was developed in order to analyze the process streams and can be used to construct the Grand Composite Curve (GCC) of the evaporation system. In addition, the study identified seasonal variations in the potential excess of energy (higher in warmer weather and lower, or even non-existent, in colder) and suggestions are made as to how this energy may be used in a thermodynamically optimal way. In the case studies, the thermodynamically optimal method of recovering heat involved a combination of sensible heat and flash evaporation, indicating the maximum reduction in steam consumption. For the case of only utilizing sensible heat outside the evaporator system to pre-heat one of the liquor flows, the results indicated a lower reduction in steam but also a lower capital cost.

Place, publisher, year, edition, pages
Mittuniversitetet , 2016. Vol. 31, no 4, p. 583-591
Keywords [en]
Black liquor, Evaporation, Multiple effect evaporator, Energy efficiency, Heat recovery, Kraft mill, Paper mill
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-62602ISI: 000389905200006OAI: oai:DiVA.org:kau-62602DiVA, id: diva2:1130477
Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2020-05-04Bibliographically approved
In thesis
1. Process modelling based on data from an evaporation and a CTMP process: Analysis of energy efficiency and process variability
Open this publication in new window or tab >>Process modelling based on data from an evaporation and a CTMP process: Analysis of energy efficiency and process variability
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The manufacture of pulp and paper is an energy intensive process configured of several unit processes that shape a network of flows of wood chips, chemical pulp, mechanical pulp, paperboard, steam and other important components. Improved energy efficiency supports sustainability of the process and the products. With the purpose of monitoring and controlling, information from multiple process and quality variables is continuously collected in the process data system. This data may be of time-varying nature and the variability might potentially span from seasonal to time-wise shorter variations and there are in some cases a need for predicting certain properties.

By applying models based on process data there is a potential to increase the knowledge of the process characteristics, investigate the applicability of predictive models and identify optimization opportunities. Based on data from an evaporation and a CTMP plant, process models have been developed with the aim of improving the energy efficiency and studying process variability.  

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2018. p. 56
Series
Karlstad University Studies, ISSN 1403-8099 ; 2018:7
Keywords
CTMP, process modelling, evaporation, energy efficiency
National Category
Chemical Process Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-65785 (URN)978-91-7063-836-7 (ISBN)978-91-7063-931-9 (ISBN)
Presentation
2018-03-21, Fryxellsalen, Karlstad, 10:15 (Swedish)
Opponent
Supervisors
Note

Artikel 3 ingick i licentiatuppsatsen som manuskript med titeln: "Time series analysis of refining conditions and estimated pulp properties in a CTMP-process with aspect of potential dynamic modelling applicability"

Available from: 2018-04-12 Created: 2018-02-02 Last updated: 2019-07-02Bibliographically approved
2. Process modelling in pulp and paper manufacture: Application studies with aspects of energy efficiency and product quality
Open this publication in new window or tab >>Process modelling in pulp and paper manufacture: Application studies with aspects of energy efficiency and product quality
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The manufacture of pulp and paper is an energy intensive process configured of several unit processes that shape a network of flows of wood chips, chemical pulp, mechanical pulp, board and other important components. Improved energy efficiency supports sustainability of the process and the products. With the purpose of monitoring and controlling, information from multiple process and quality variables is continuously collected in the process data system. The data may contain information about underlying patterns and variability, and using statistical and multivariate data analysis can create valuable insights into how reduced variations and predictions of certain properties can be accomplished.

This thesis investigates the application of mathematical models for processes and products. These models can be used to increase the knowledge of the process characteristics and for quality predictions, to support process optimization and improved product quality.

Based on process data from a board machine including the stock preparation process, an evaporation system and a CTMP plant, process models have been developed with the aims of quality predictions, improved energy efficiency and reduced process variability. 

Abstract [en]

The manufacture of pulp and paper is an energy intensive process configured of several unit processes that shape a network of flows of wood chips, chemical pulp, mechanical pulp, board and other important components. Improved energy efficiency supports sustainability of the process and the products. With the purpose of monitoring and controlling, information from multiple process and quality variables is continuously collected in the process data system. The data may contain information about underlying patterns and variability, and using statistical and multivariate data analysis can create valuable insights into how reduced variations and predictions of certain properties can be accomplished.

This thesis investigates the application of mathematical models for processes and products. These models can be used to increase the knowledge of the process characteristics and for quality predictions, to support process optimization and improved product quality.

Based on process data from a board machine including the stock preparation process, an evaporation system and a CTMP plant, process models have been developed with the aims of quality predictions, improved energy efficiency and reduced process variability. 

Through application of modelling and simulation techniques a range of models were developed in several case studies. These techniques included both mechanistic and statistical models and were demonstrated using Pinch to study energy recovery in the evaporation plant, time series and multiple linear regression modelling for predictions in the CTMP process, flowsheet modelling of stock preparation dynamics and neural networks for board quality predictions. The process models that were developed in the case studies demonstrated how these methods can be applied to predict important properties, study systematic variations and improve the energy efficiency by describing the opportunities and limitations associated with these techniques.

Place, publisher, year, edition, pages
Karlstads universitet, 2020
Series
Karlstad University Studies, ISSN 1403-8099 ; 2020:19
Keywords
CTMP, freeness, process modelling, board machine, multiple effect evaporator
National Category
Chemical Process Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-77369 (URN)978-91-7867-113-7 (ISBN)978-91-7867-118-2 (ISBN)
Public defence
2020-09-04, 1B 364, Frödingsalen, Universitetsgatan 2, Karlstad, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2020-08-14 Created: 2020-05-04 Last updated: 2020-09-07Bibliographically approved

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Ekbåge, DanielNilsson, Lars

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