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Process modelling based on data from an evaporation and a CTMP process: Analysis of energy efficiency and process variability
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
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 [en]
CTMP, process modelling, evaporation, energy efficiency
National Category
Chemical Process Engineering
Research subject
Environmental and Energy Systems
Identifiers
URN: urn:nbn:se:kau:diva-65785ISBN: 978-91-7063-836-7 (print)ISBN: 978-91-7063-931-9 (electronic)OAI: oai:DiVA.org:kau-65785DiVA, id: diva2:1179715
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
List of papers
1. Potential energy improvements in a multiple-effect evaporation system: Case studies of heat recovery
Open this publication in new window or tab >>Potential energy improvements in a multiple-effect evaporation system: Case studies of heat recovery
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
Keywords
Black liquor, Evaporation, Multiple effect evaporator, Energy efficiency, Heat recovery, Kraft mill, Paper mill
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-62602 (URN)000389905200006 ()
Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2019-07-11Bibliographically approved
2. Trial measurements in a CTMP-process to perform time-series analysis of refining conditions and estimated pulp properties
Open this publication in new window or tab >>Trial measurements in a CTMP-process to perform time-series analysis of refining conditions and estimated pulp properties
2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kau:diva-65786 (URN)
Conference
10th Fundamental Mechanical Pulp Research Seminar
Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2018-02-02Bibliographically approved
3. Time series analysis of refining conditions and estimated pulp properties in a chemi-thermomechanical pulp process
Open this publication in new window or tab >>Time series analysis of refining conditions and estimated pulp properties in a chemi-thermomechanical pulp process
2019 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 3, p. 5451-5466Article in journal (Refereed) Published
Abstract [en]

Frequently sampled process data from a conical disc refiner and infrequently sampled pulp data from a full scale chemi-thermomechanical pulp (CTMP) mill were evaluated to study autocovariance with aspects of potential dynamic modelling applicability. Two trial measurements with an online pulp analyzer at decreased sampling intervals were performed. For variability analysis, time-series containing up to one day of operational data were used. At the chip refiner, the clearest significant autocovariance was identified for the specific electricity consumption, based on the longer sequences. Most of the estimated pulp properties indicated low or non-significant autocovariance, limiting applicability of a specific dynamic model. A mill trial was conducted to investigate the impact from an increase in the conical disc gap on the specific electricity consumption and the resulting freeness. The response time from the gap change in the refiner to measured change in freeness was estimated at 19 min, which was approximately the hydraulic residence time in the latency chest. The relevance of this study lies in applicability of mill-data-driven modelling to capture the dynamics of a specific refining process. Through mill trials the sampling speed of pulp properties was more than doubled to gain insights into short term systematic variations by applying time-series-analysis.

Place, publisher, year, edition, pages
North Carolina State University, 2019
Keywords
Chemi-thermomechanical pulp (CTMP); Freeness; Dynamic modelling; conical disc refiner; Specific electricity consumption; Energy efficiency; Autocovariance
National Category
Paper, Pulp and Fiber Technology
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-65734 (URN)10.15376/biores.14.3.5451-5466 (DOI)000473204700036 ()
Funder
Knowledge Foundation
Note

Artikeln ingick som manuskript i Ekbåges licentiatuppsats (2018) Process modelling based on data from an evaporation and a CTMP process

Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2019-08-06Bibliographically approved

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