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  • 1.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlöf, Mats
    Capisco AB.
    Paulsson, Magnus
    Decrease in strengthalong a process line for SC paper2019In: Fundamental Mechanical Pulp Research Seminar, FMPRS2019, Norrköping, SwedenArranged by Mid Sweden University in cooperatrion with Holmen AB, Valmet AB, AF AB and Treesearch., 2019Conference paper (Refereed)
  • 2.
    Engstrand, Per O.
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Björkqvist, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Johansson, Lars
    PFI.
    Johansson, Örjan
    Luleå Tekniska Universitet.
    Daniel, Geoffrey
    Sveriges Lantbruks Universitet.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Karlström, Anders
    Chalmers.
    Karlsson, Anette
    SCA Forest Products AB, Ortviken.
    Sandberg, Christer
    Holmen Paper, Braviken.
    Mekmassainitiativet för energieffektivitet, e2mp-i2015Report (Other academic)
    Abstract [sv]

    Projektet har drivits som ett program för finansiering av forskning som ska utveckla ochdemonstrera tekniker som reducerar elenergiförbrukningen med 50% vid tillverkning avTMP och CTMP med bibehållna slutproduktegenskaper hos tryckpapper och kartong.Programmet är en del av skogsindustrins initiativ att under en tioårsperiod tillsammansmed svenska och norska finansiärer investera minst 200 Mkr för att nå detta radikalaeffektiviseringsmål. Ett uttalat mål för industriinitiativet är också att befästaforskningsnoderna vid FSCN i Sundsvall och PFI i Trondheim.

    Parallellt med Energimyndighetens finansiering, 30 Mkr, har Norges Forskningsråd satsat25 MNOK (2010‐14) i industriinitiativet, KK‐stiftelsen 36 MSEK (2011‐17) ochMittuniversitetet har finansierat12 MSEK. Industrins totala satsning kommer att överstiga100 MSEK redan vid utgången av 2017.

    Resultat från benchmarkingstudien BAT2012 av industrins modernaste TMP‐ och CTMPlinjersamt från demonstrationsskaleprojekt visas i rapporten. Projekten baseras delvis pågrundläggande forskningsprojekt genomförda inom FSCN´s KK‐stiftelse‐finansieradeforskningsprofil och projektet ”Filling the Gap” 31676‐, ISSN 1650‐5387 2014:57. Resultaten visar följande reduktionsnivåer; 28% TMP för news (Braviken), 14% TMP för SC(Kvarnsveden) och 21% CTMP för kartong (Skoghall).

    Utöver demoprojekten finns ytterligare tydliga potentialer beskrivna i övriga delprojekt:

    Processintensifiering och processmodifiering > 15%

    Processtabilitet via avancerad processanalys och reglering > 15%

    Kombinera effektivaste processavsnitt från benchmarking ca 25%Detta gör det troligt att det kommer att gå att i fullskaliga demonstrationsförsök validera50% elenergireduktion inom de tre produktområdena, förutsatt att fortsattforskningsfinansiering finns tillgänglig. Tre av de idéer till avknoppningsprojekt somframkommit under projektets gång har redan erhållit beslut om finansiering frånEnergimyndigheten 2015. Ytterligare projektförslag baserade på den här redovisadeforskningen kommer att ingå i ansökningar under 2016. Utöver energireduktion i själva TMP‐ och CTMP‐processerna har forskare vid FSCN lagt forskningsgrunden för hur manska kunna tillverka mycket starka förpackningsmaterial från dessa massatyper på ettenergieffektivt sätt. Även inom detta område kommer en ansökning omuppskalningsprojekt att skickas in.

  • 3.
    Eriksson, K.
    et al.
    CIT Industriell EnergI.
    Ferritsius, J.
    Uppsala University, Uppsala.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso, Finland.
    Hill, J.
    QualTech, India.
    Karlstrorrp, A.
    Chalmers University of Technology.
    Merseburg, K.
    Paper and Fibre Research Institute, Norway.
    Proper pulp sampling pre-requisite to any pulp property assessment2016In: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, p. 1-11Conference paper (Refereed)
  • 4.
    Eriksson, K.
    et al.
    Chalmers Science Park, Göteborg.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Paper, Kvamsveden Mill.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hill, J.
    QualTech, Tyringe.
    Benefits from improved stability in process conditions and pulp properties-a double disc refiner case study2016In: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, p. 317-327Conference paper (Refereed)
    Abstract [en]

    The purpose of this case study was to explore the potential for reduced energy consumption by improved process control. The application was HC post-refining of TMP in double-disc refiners. Based on data from both continuous production and from step-response tests, a thorough analysis of process performance was conducted. It was found that a significant proportion of the process disturbances, as reflected in the refiner motor load, could be successfully dampened through stabilizing measures on the basic control level. The remaining disturbances was found to be generated inside the refiner itself. In order for these disturbances to be dampened, measurements that can characterize the conditions inside the refining zone are necessary. Given the present design and instrumentation of the process, dynamic modelling of refiner motor load was performed and for fiber properties, muhivariate modeling methods were used to derive expressions for the independent variables Fl and F2. Taken together, evaluation of the models gave directions on how to further improve the process stability and indicated a potential for reduced energy consumption.

  • 5.
    Eriksson, K.
    et al.
    CIT (Chalmers industriteknik).
    Karlström, A.
    CTH (Chalmers tekniska högskola).
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hill, Jan
    QualTech AB.
    Recent advances in modelling and control of TMP refining processes2015Conference paper (Refereed)
  • 6.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso.
    Hill, Jan
    QualTech AB.
    Ferritsius, Johanna
    Some insights regarding standards and common practice2015Conference paper (Refereed)
  • 7.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso Kvarnsveden.
    Hill, Jan
    QualTech AB, Tyringe.
    Karlström, Anders
    Chalmers University of Technology, Göteborg.
    Ferritsius, Johanna
    StoraEnso Kvarnsveden.
    Eriksson, Karin
    CIT Industriell Energi, Göteborg.
    Process considerations and its demands on TMP property measurements - A study on tensile index2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 1, p. 45-53Article in journal (Refereed)
    Abstract [en]

    As a vital component in the strive towards improved energy efficiency in the operation of TMP refining processes, this work highlights the importance of well- designed procedures when collecting and analysing pulp properties with respect to process conditions. Process data and pulp from a CD82 chip refiner have been used to show that tensile index has strong covariance with fibre residence time calculated by the extended entropy model. A combination of theoretical and practical analysis methods has shown that, in order to assure representative, reliable results, pulp sampling procedures should comprise composite pulp samples collected during a sampling period of about three minutes. In addition, at least four subsequently collected composite pulp samples should be included in the analysis to effectively dampen effects from fast process variations as well as from slow process drift. An in-depth study on tensile index measurements clarifies that 40-60 strips should be used in the case we studied regardless if machine made paper or handsheets are considered.

  • 8.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlof, Mats
    Capisco Sci & Art, Norrköping.
    Average fibre length as a measure of the amount of long fibres in mechanical pulps - ranking of pulps may shift2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 3, p. 468-481Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the applicability of different ways of calculating the average fibre length based on length measurements of individual particles of mechanical pulps. We have found that the commonly used average length-weighted fibre length, which is based on the assumption that coarseness is constant for all particles, as well as the arithmetic average, may lead to erroneous conclusions in real life as well as in simulations when used as a measure of the amount of long fibres. The average length-length-weighted fibre length or a weighting close to that, which to a larger extent suppresses the influence of shorter particles, is a relevant parameter of the "length" factor, i. e. amount of long fibres. Our findings are based on three studies: refining of different assortments of wood raw material in a mill; data from LC refining in mill of TMP, including Bauer McNett fractionation; mixing of pulps with different fibre length distributions. If the acceptable average fibre length for different products can be lowered, the possibility of reducing the specific energy input in refining will increase. Therefore, we need a reliable and appropriate way to assess the "length" factor.

  • 9.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso Paper Kvarnsveden Mill.
    Rundlöf, Mats
    Capisco.
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    The Independent State of Fibres in Relation to the Mechanical Pulping World2018In: IMPC 2018, Trondheim, Norway, 2018Conference paper (Refereed)
    Abstract [en]

    Paper and wood are highly inhomogeneous materials. When describing the mechanical pulp itself, we allcommonly ignore that it is an inhomogeneous material. We have realized that just a very small fraction of stifffibres are enough to impair the printability of the product. In this paper we share some of our reflections andattempts how to describe the inhomogeneous nature of mechanical pulps. A method denoted BIN is underdevelopment based on independent common factors and paying attention to the inhomogeneity of the material.The method may give the possibility to describe the nature of TMP/CTMP/SGW in a more relevant way comparedto todays practice. Hence the paper and board makers may be able to deliver more uniform products at “goodenough” level at lower costs. We have realized that because a method or opinion is well spread (sometimes usedby almost everybody) it does not necessarily mean that it is relevant. A couple of myths have been reflected uponand in our opinion they remain just myths. By putting more attention to reality and describing mechanical pulp asan inhomogeneous material we hope to be able to rid ourselves and the mechanical pulping community of someother myths circulating (some still to be discovered).

  • 10.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Mörseburg, K.
    PFI, Trondheim, Norway.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Kvamsveden Mill, Sweden.
    Bat of CTMP and TMP plants with respect to quality development and energy efficiency2014In: International Mechanical Pulping Conference, IMPC 2014, Paper Engineers' Association (PI) , 2014Conference paper (Refereed)
    Abstract [en]

    Sixteen TMP/CTMP lines aimed for publication and board grades have been compared for energy efficiency with respect to pulp quality development. The pulp property profile and the process design differed substantially, even for similar product grades. A given level of a specific pulp property was reached over a wide range in specific energy. The most energy efficient lines operated at the highest production rates and with high relative speed of the refiner discs. With respect to the final pulp quality there was no obvious influence of how the screen room was equipped. It was possible to develop the fibers in a proper way just by refining of the whole pulp stream.

  • 11.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso Kvarnsveden, Borlänge.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hill, J.
    QualTech AB, Tyringe.
    Karlström, A.
    Chalmers University of Technology, Gothenburg.
    Eriksson, K.
    CIT Industrial Energy, Gothenburg.
    TMP properties and refining conditions in a CD82 chip refiner. Part I: Step changes of process variables, description of the tests2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 1, p. 69-81Article in journal (Refereed)
    Abstract [en]

    The study explores how changes in process variables, residence time and pulp consistency in refining influence the pulp properties. The equipment utilized in this study was a conical disc chip refiner (RGP82CD) producing thermomechanical pulp (TMP). The focus was on the ratio between tensile index and specific energy consumption. Pulp properties were measured for composite pulp samples taken from the refiner blow line. Residence times and pulp consistencies were estimated by use of the extended entropy model. This showed that the CD-refiner, with the flat and conical refining zone, has a process performance similar to that of a two-stage refiner set-up, and that the consistency in both refining zones is of high importance. Comparing different periods revealed that even if the values of measured blow line consistency are similar, significant differences in the estimated consistency in the flat zone can prevail. Therefore, only monitoring blow line consistency is not enough. Specifically, it was found that the pulp consistency after the flat zone could be very high, considerably higher than in the blow line, and this could have negative effects on tensile index and fibre length. 

  • 12.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso Kvarnsveden, Borlänge.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hill, Jan
    QualTech AB, Tyringe.
    Karlström, Anders
    Chalmers University of Technology, Gothenburg.
    Eriksson, Karin
    CIT Industriell Energi, Gothenburg.
    TMP properties and refiner conditions in a CD82 chip refiner at different operation points. Part II: Comparison of the five tests2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 1, p. 82-94Article in journal (Refereed)
    Abstract [en]

    This paper is part two of a study on a CD 82 TMP chip refiner where relations between changes in the process conditions and changes in the properties of the produced pulp are investigated. Focus is on the ratio between tensile index and specific energy consumption when results from five tests are compared. Pulp properties were measured for composite pulp samples taken from the refiner blow line. Residence times and pulp consistencies were estimated by use of the extended entropy model. Clearly, an increase in specific energy does not necessarily implicate an increase in strength properties of the pulp produced. It is of high importance to have access to information about the refining zone conditions when searching for an optimal operation point in terms of the ratio between tensile index and specific energy. In these tests, this ratio had a maximum at about 55 % measured blow line consistency. Unfavourable operating conditions were identified at high pulp consistencies, especially after the FZ, where pulp consistencies well above 70 % were observed. The estimated residence time for each refining zone responded differently when applying changes in production rate, plate gaps and dilution water flow rates. In conclusion, the results associated with estimated pulp consistencies where easier to interpret compared with results for residence times, implying that additional tests are required for the latter variable. In addition to tensile index, pulp properties like freeness, Somerville shives and light scattering coefficient were included in the analysis. 

  • 13.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Kvarnsveden Mill, Sweden.
    Hill, J.
    QualTech AB, Tyringe, Sweden.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Karlstrom, A.
    Chalmers University of Technology, Sweden .
    On energy efficiency in chip refining2014In: International Mechanical Pulping Conference, IMPC 2014, Paper Engineers' Association (PI) , 2014Conference paper (Refereed)
    Abstract [en]

    The quality of TMP has been investigated for a CD82 chip refiner both with respect to normal variations and as a result of step changes of production rate, dilution water feed rates and plate gaps. A given level of tensile index was reached over a wide range in specific energy input. The energy efficiency with respect to tensile index decreased if the pulp consistency in the blow line exceeded 55 %. The extended entropy model applied on the refiner showed that the calculated pulp consistency after the flat zone could be extremely high, leading to lower energy efficiency. This was not possible to detect by the measured values for the pulp consistency in the blow line. The short time variations in tensile index correlated more strongly with the model based total residence time in the two refining zones than with the motor load.

  • 14.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Reyier Österling, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Development of TMP fibers in LC- and HC-refining2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 5, p. 860-871Article in journal (Refereed)
    Abstract [en]

    Low consistency (LC) refining and high consistency refining (HC) has been studied in a TMP mill. When strength properties were increased, the development of fiber properties was different in LC- and HC-refining. Fiber curl decreased in LC-refining but increased in HC-refining. LC-refining decreased fiber curl and increased tensile index simultaneously in this study. It is therefore likely that the decreased fiber curl contributes to the increase of tensile index in LC-refining. Furthermore, fiber wall thickness decreased and external fibrillation increased in HC-refining, while these properties were only slightly influenced in the LC-refining. Fibrillation was found to decrease in most cases for LC-refining while fiber wall thickness index increased slightly but consistently, which might indicate a less dense structure of the fiber wall or its surface layers. Double-disc HC-refining with the same energy input as in a conical single-disc refiner resulted in fibers of higher external fibrillation, lower fiber wall thickness and higher fiber curl at a given fiber length. The results indicate that analyzing individual fiber dimensions could be a better tool for understanding how fibers develop in different kinds of refining than analyzing conventional handsheet properties.

  • 15.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Kvarnsveden Mill, Borlänge, Sweden .
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Holmen Paper, Norrköping, Sweden .
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    LC-refining of mechanical pulps and its influence on fiber curl and handsheet strength properties2014In: International Mechanical Pulping Conference, IMPC 2014, 2014Conference paper (Refereed)
    Abstract [en]

    The effect on fiber and sheet properties has been compared for two different low consistency (LC) refiners in two TMP mills. One of the LC-refiners (CF 82) was running as second stage in the main line and the other (TF58) was running as second stage in the reject line. The development of fiber and strength properties was very similar for the two cases. Both disintegration in the laboratory and LC- refining decreased the fiber curl and increased the tensile index in a similar way. The effects of disintegration and LC-refining were additive.

  • 16.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Paper Kvarnsveden Mill.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Holmen Paper.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlöf, Mats
    Capisco, Norrköping.
    Daniel, Geoffrey
    SLU, Dept. of Forest Products/Wood Science, Uppsala.
    Mörseburg, Kathrin
    Paper and Fibre Research Institute (PFI), Trondheim Norway.
    Fernando, Dinesh
    SLU, Dept. of Forest Products/Wood Science, Uppsala.
    Development of Fiber Properties in Full Scale HC and LC Refining2016In: TAPPI conference proceedings, TAPPI Press, 2016Conference paper (Refereed)
  • 17.
    Fiskari, Juha
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Valmet AB.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Paper, Kvarnsvedens Mill.
    Osong, Sinke H.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Persson, Anders
    Valmet AB.
    Höglund, Tomas
    Valmet AB.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Deep Eutectic Solvent Treatment to Low-Energy TMP to Produce Fibers for Papermaking2018In: IMPC 2018, Trondheim, Norway, 2018Conference paper (Refereed)
    Abstract [en]

    The aim of this research was to gain a better understanding on whether a novel process based on low-energy thermo-mechanical pulp (TMP) process followed by a chemical treatment with deep eutectic solvents (DESs) could produce fibers suitable for papermaking. In full scale production, these fibers could be produced at a much lower capital and operational costs, especially when utilizing existing TMP plants which are under the threat to be shut down or have already been shut down due to a decreasing demand for newsprint and other wood-containing papers.The efficiency of several DES treatments under various temperatures and times were evaluated by carrying out experiments in standard Teflon-lined autoclaves. A few tests were also performed in a unique nonstandard flow extractor. Pulp samples were characterized for their cellulose, hemicellulose and lignin contents. Moreover, tensile index was measured both before and after pulp refining. Depending on the solvent, the response of mechanical pulp varied, especially in terms of hemicellulose dissolution. Lactic acid, oxalic acid and urea, all in combination with choline chloride ([Ch]Cl) as the hydrogen bond acceptor, dissolved about 50% of the lignin of the low-energy TMP fibers under the tested conditions. The mixture of malic acid and [Ch]Cl was less effective in lignin dissolution. The mixture of urea and [Ch]Cl exhibited only a minor loss in hemicellulose content, when compared to the other tested DESs. Although 50% of the lignin was dissolved with minor loss in hemicellulose no improvement in tensile strength was observed, as it was rather the opposite. Another benefit with the mixture of urea and [Ch]Cl was that this DES did not appear to be corrosive to stainless steel. All other tested DESs—which were also quite acidic—were observed to be corrosive. Moreover, this DES-related corrosion was found to intensify at elevated temperatures.When chips were used as starting material with otherwise the same conditions almost no lignin was dissolved. This suggests that low-energy mechanical pulp is likely to be a good starting material for extracting lignin using DESs.

  • 18.
    Hill, Jan
    et al.
    QualTech AB.
    Karlström, A.
    CTH.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pulp property development – inside the gap perspective2015Conference paper (Refereed)
  • 19.
    Karlström, A.
    et al.
    Chalmers University of Technology, Göteborg, Sweden .
    Hill, J.
    QualTech AB, Tyringe, Sweden.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Kvarnsveden, Borlänge, Sweden.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Can we increase the proportion of electrical energy into fibre development in existing HC-refiners?2014In: International Mechanical Pulping Conference, IMPC 2014, Paper Engineers' Association (PI) , 2014Conference paper (Refereed)
    Abstract [en]

    Currently some 5 % of the electrical energy input in high consistency refining can be attributed to fibre development work. The rest is related to thermo- dynatnical steam generation. Can this unfavourable relation between fibre development and heat generation eventually be improved? A pre-requisite to consistent improvement is a stable process, controlled to targets deduced from profound process evaluations. This statement is elaborated based on two case studies and extensive refiner modelling. It is indicated that a well designed process including its basic process control can with proper refiner control reach energy reductions in excess of 20 %. Proper selections of process targets aligned with choice of segments can further increase the energy reduction in existing lines. These drastic energy reductions will demand concurrent observations and process modelling based on spatial measurements in the refining zone rather than slow, inadequate feedback control from pulp property measurements downstream. This will furthermore stress the need for more advanced control schemes if the full potential is to be captured. Additionally this approach will be a key element in the development of novel process approaches with even larger potential of energy reduction.

  • 20.
    Karlström, Anders
    et al.
    Chalmers University of Technology, Göteborg.
    Hill, Jan
    QualTech AB, Tyringe.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pulp property development Part III: Fiber residence time and consistency profile impact on specific energy and pulp properties2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 2, p. 300-307Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the pulp properties obtained from ThermoMechanical Pulp (TMP) CD refiners. Undersampled pulp variables are expanded into an oversampled set of process data, which makes it possible to analyze pulp properties in a dynamic time frame. It is shown that, in order to gain deeper insight into the defibration/fibrillation at a specific energy input, one needs to know the fiber residence time and the consistency profile. Moreover, the fiber residence time in the flat zone (FZ) and conical zone (CD) are intertwined with the consistency out from FZ and CD. Together with an external variable (production), these internal variables are essential for predicting the pulp properties. It is also shown that internal process conditions from different test series can be manipulated in the operating window using a low-frequency gain description obtained from an ARX model. The same mapping procedure can be applied to pulp and handsheet properties (in this paper represented by the tensile index), and this opens for implementation of new optimization routines to find more energy efficient operating points while maintaining prespecified pulp quality.

  • 21.
    Karlström, Anders
    et al.
    Chalmers University of Technology, Göteborg, Sweden.
    Hill, Jan
    QualTech AB, Tyringe, Sweden.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pulp property development Part I: Interlacing under-sampled pulp properties and TMP process data using piece-wise linear functions2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 4, p. 599-608Article in journal (Refereed)
    Abstract [en]

    Thermo-Mechanical Pulp (TMP) refiners served in this work as an example of how to combine oversampled and undersampled variables on a common timeframe for further analysis.To get more information from the refining process, temperature measurement arrays in the refining zones were studied alongside process measurements such as motor load, production rates, plate gaps, dilution waters, pulp properties and manually measured blow-line consistency.The undersampled data set consisted of 63 laboratory samples obtained at a Swedish TMP mill, which were tested for tensile index, mean fiber length and Somerville shives content. The pulp samples were obtained at five different periods during three months to cover a large dynamic operating window.The data set was expanded using a piece-wise linear approach. The measurements inside the refining zone were shown to be important variables when interlacing the undersampled pulp properties with the oversampled process data set, consisting of 350 000 samples.Use of an extended entropy model provided a palette of information about the process conditions inside the refining zone. Particularly, the residence time and the consistency in the refining zones were essential for the pulp property development, as a link between the refining segment pattern used and the current state of refiner operation.

  • 22.
    Karlström, Anders
    et al.
    Chalmers University of Technology, Göteborg.
    Hill, Jan
    QualTech AB, Tyringe.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pulp property development Part II: Process non-linearities and their influence on pulp property development2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 2, p. 287-299Article in journal (Refereed)
    Abstract [en]

    It is shown in this paper that knowledge of the spatially measured temperatures inside the refining zone in TMP refiners is essential in describing non-linear dynamics of high consistency refining. By expanding the pulp and handsheet properties using piece-wise linear functions into the time domain, an auto-regressive model can be applied to verify that the tempera-ture and the consistency profiles, in combination with the motor load and production rate, are key input candidates when modeling changes in different pulp properties. The model accuracy is analyzed using process information captured at different time and operating conditions. It is also shown that it is more complex to estimate and validate the tensile index than the mean fiber length and Somerville shives content, especially close to refiner operating limits where a shift in the process gain may occur. This type of switched dynamics in tensile index estimation at a specific consistency is related to non-linear behaviors where the fiber pad distribution most likely undergoes a local collapse.

  • 23.
    Reyier Österling, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    The influence of fiber dimensions on mechanical pulp long fiber tensile index and density2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 5, p. 844-859Article in journal (Refereed)
    Abstract [en]

    This study discusses how fiber dimensions affect the tensile index and density of long fiber laboratory sheets. Five commercial mechanical pulps (three TMP grades, one SGW and one CTMP) were fractionated into five streams in a hydrocyclone pilot plant. Fiber dimensions and fibrillation were analyzed of the P16/R30 and P30/R50 fractions and compared to the sheet properties. For comparison, samples were also analyzed by SEM cross-sectional image analysis and in a MorFi Lab optical analyzer. Fibrillation index showed a high positive influence on long fiber tensile index and density, whereas fiber wall thickness, fiber width, and collapse resistance index a negative. Fiber width showed the vaguest correlation to long fiber tensile index and density of the analyzed fiber properties, but this increased when combined with fiber wall thickness into collapse resistance index, CRI. The correlations between fiber properties and sheet properties were on different levels for the different mechanical pulping processes, but a combination of collapse resistance index and fibrillation index into the novel factor BIN, Bonding ability INfluence, gave one linear relation of high correlation to long fiber tensile index for all pulps, except the SGW P30/R50 fraction, which showed the same linear correlation on a slightly lower level. BIN should be a useful tool in characterizing mechanical pulp fibers.

  • 24.
    Reyier Österling, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Printing & Reading R&D, Borlänge, Sweden.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Kvarnsveden Mill, Borlänge, Sweden.
    Johansson, C-A
    Stora Enso Printing & Reading R&D, Borlänge, Sweden.
    Stångmyr, J
    Stora Enso Kvarnsveden Mill, Borlänge, Sweden.
    Weighted averages and distributions of fibre characteristics of mechanical pulps – Part II: Distributions of measured and predicted fibre characteristics by using raw data from an optical fibre analyser2016In: Appita journal, ISSN 1038-6807, Vol. 69, no 1, p. 64-73Article in journal (Refereed)
    Abstract [en]

    Characterisation of fibres in mechanical pulps is important for process evaluation and control, and necessary to be able to optimise the refining process with respect to the total electric energy consumption. There are large variations of cross-sectional fibre characteristics in the wood raw material which influence the properties of the product. Despite this, it is common to evaluate the fibre characteristics as averages instead of distributions. This study shows that the raw data from a FiberLab analyser can be used to make distributions of measured and predicted fibre characteristics. The factor BIN (Bonding ability /Nfluence), which correlates to long fibre tensile index, includes both the external fibrillation and wall thickness of each fibre. Distributions of BIN, fibrillation and wall thickness which take the Characteristics of each fibre into Consideration have higher resolution than histograms. These distributions weighted by length and wall volume with maintained resolution revealed more information about the pulps than average values.

  • 25.
    Reyier Österling, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Stångmyr, J.
    Stora Enso Kvarnsveden Mill, Borlange, Sweden.
    Weighted averages and distributions of fibre characteristics of mechanical pulps Part I: Various methods of weighting data from an optical analyser can give averages that rank pulps differently2015In: Appita journal, ISSN 1038-6807, Vol. 68, no 4, p. 357-368Article in journal (Refereed)
    Abstract [en]

    To improve the operation and energy efficiency of mechanical pulping processes, the effect of each stage of the process on the fibres should be carefully evaluated. Fibre-data from an optical analyser were used to predict tensile index by calculating BIN (Bonding ability /Nfluence). Wall volume weighted averages of wall thickness index and fibrillation index gave the most accurate predictions of the tensile index of laboratory sheets made from long fibre fractions of various mechanical pulps. Fibre width index, when used as a single factor, reduced the accuracy of the model. The ranking of some samples changed when fibre width was wall volume weighted compared to arithmetic. When fibre width was combined with wall thickness to give a collapse resistance index, no rankings changed. Weighted averages based on squared fibre length (length(2)) showed poor correlation to wall volume weighted averages for cross-sectional fibre dimensions, and resulted in different levels of correlation to long fibre tensile index for the five evaluated pulps.

  • 26.
    Sandberg, Christer
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Holmen Paper.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. StoraEnso.
    Energy efficiency in mechanical pulping2017Conference paper (Refereed)
1 - 26 of 26
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