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  • 1.
    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.

  • 2.
    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)
  • 3.
    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.

  • 4.
    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)
  • 5.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Beyond averages – some aspects of how to describe a heterogeneous material, mechanical pulp, on particle level2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    For a more profound understanding of how a process works, it is essential to have a relevant description of the material being processed. With this description, it will be easier to evaluate and control processes to produce more uniform products with the right properties. The focus of this thesis is on how to describe mechanical pulps in ways that reflect its character.

    Mechanical pulps are made from wood, a highly heterogeneous material. Common practice within the pulping industry and academy is to describe mechanical pulps and its wide variety of particles in terms of averages. The energy efficiency of the mechanical pulping process is usually calculated without taking into account the characteristics of the wood fed to the process. The main objective of the thesis is to explore ways to make more detailed descriptions of mechanical pulps. A second objective is to propose useful ways to visualise these descriptions.

    The studies were carried out in full-scale mill operations for TMP of publication grades and CTMP for board grades with Norwegian spruce as raw material. The particles in the pulps were analysed in an optical particle analyser for several properties such as length, curl, wall thickness, diameter,and external fibrillation for 10,000 to 60,000 particles per sample to cover their wide property variation. The data was analysed by factor analysis, a method to reduce the multidimensional data space, and also compared with data simulations.

    Several examples were identified where averages based on wide and skewed distributions may hide useful information and therefore result in misleading conclusions regarding the fibrous material and process performance. A method was developed to calculate the distribution of a common bonding factor, BIND (bonding indicator) for individual particles. This factor is calculated from external fibrillation, wall thickness and diameter measured in an optical particle analyser. Distributions of BIND is one way to characterize and visualise the heterogeneity of mechanical pulp. A characteristic BIND-distribution is set in the primary refiner stage, depending on both wood and process conditions and remains mostly intact through the process.

    It was demonstrated that both BIND-distributions and 4D maps of the measured property distributions could be used to assess the tails of the distributions (extreme values), energy efficiency, and fractionation efficiency in a new way. It was even possible to get a measure for energy efficiency for a primary stage refiner, since a method was developed where the wood raw material was evaluated in the same way as the pulp discharged from the refiner.

    It was demonstrated that the average length-length-weighted fibre length, commonly referred to as the average weight-weighted fibre length, is a relevant way to express the amount of long fibres, i.e. “length factor”. The commonly used average length-weighted fibre length may lead to erroneous conclusions. Through data simulations of curl and fibre length on particle level it was found that today’s analysers may underestimate the true length of the particles, especially if they are prone to be curled. As a result, theranking of pulps may be altered.

    It was concluded that although there is an ISO standard, or long-time used property, it does not necessarily imply that it is a relevant method. Misleading conclusions may be drawn based on current methods; here, modifications of these methods are suggested.

    The main contribution of this study is the finding that that a highly heterogeneous material such as mechanical pulps could be described in new ways through visualisation of data in 4D maps. These maps reveal casualconnections and more pertinent questions may be raised in thecommunication along the chain product-pulp-wood.

    Going beyond averages may reveal discrepancies in the process and material that were previously unknown, and lead to a more profound understanding. It seems that the mechanical pulping process can be even further simplified than previously expected. It has been concluded that to operate the process more efficiently, and for make products with just the right quality, the main focus should be on the raw material and the primary refiner stage from a heterogeneity point of view.

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  • 6.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, R.
    StoraEnso Paper Kvarnsveden Mill.
    Hill, J.
    QualTech, India.
    Eriksson, K.
    CIT Industriell Energi.
    Mörseburg, K.
    PFI.
    Ferritsius, J.
    StoraEnso, Finland.
    Untaught experiences regarding common practice and standards for sampling, characterization, control, and Design of TMP and CTMP operations2016In: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, p. 12-17Conference paper (Refereed)
  • 7.
    Ferritsius, Olof
    et al.
    STORA Corporate Research.
    Ferritsius, Rita
    STORA Corporate Research.
    Improved quality control and process design in production of mechanical pulp by use of factor analysis1997In: Proceedings International Mechanical Pulping Conference, 1997, p. 111-125Conference paper (Refereed)
    Abstract [en]

    In 1963, Forgacs showed that at least two quality variables are needed in order to characterize the quality of mechanical pulps. Later, Strand came to asimilar conclusion by introducing two independent common factors through the use of factor analysis. Both Forgacs and Strand showed that handsheet properties can be predicted from these two factors. This paper shows how STORA, on the basis of Strand’s approach, examines the two independent common factors directly, instead of examining a large amount of conventional measured pulp and handsheet properties. The factors are called F1, fibrebonding, and F2, long fibre influence. The independent factors are controlled to a great extent by independent process parameters; F1 correlates more strongly to specific energy than does freeness while F2 is mainly controlled by conditions in the defibration stage. In order to produce a uniform pulp quality, F1 and F2 should be kept inside a specified quality window. Since July 1995 a quality window in terms of F1 and F2 has been used at STORA Kvarnsveden TMP plant and thus has given a more stable pulp quality. The quality window gives a rapid overview of the status of the quality. Another advantage of applying F1 and F2 is that not only refiners, but also screens and cleaners can be evaluated in terms of the same quality variables. New parameters for evaluation of screens and cleaners are suggested. By examining all process stages from chip refiner, screen room to final pulp we can get a quality map in terms of F1 and F2. From this map it is quite obvious how the pulp quality is influenced by chip refiner stage and rejects refining. The F1/F2-map can simplify the work to find reasons for producing off-spec pulp and also mee tone big challenge: to produce a product of more uniform quality. To attain more uniform quality we have to think and speak daily in terms of factors like F1 and F2.

  • 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.
    Ferritsius, Johanna
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlöf, Mats
    Capisco.
    Heterogeneity2019In: Heterogeneity, 2019Conference paper (Other academic)
    Abstract [en]

    Heterogeneity may be a most proper word to describe paper and board. Wood, the raw material to produce mechanical pulps, is almost as heterogeneous a material as the products. Looking in a microscope at a mechanical pulp it is obvious that it consists of a huge amount of small particles, which vary very much in several aspects: length, curl, width, wall thickness, fibrillation etc. In spite of that, we (scientists, mill employees, suppliers, consultants, researchers) commonly describe a pulp in terms of collective properties such as averages of fibre dimensions, hand sheet properties, dewatering ability etc. In other words: we describe mechanical pulp as a continuum. This may be more common than we believe. A review of the variables used in the more than 5,000 graphs in the preprints of the 23 International Mechanical Pulping Conferences (IMPC) between 1973 and 2018 showed that 97% of the variables described mechanical pulp as a continuum. Hence, only 3% of the variables reflected the heterogeneous nature of mechanical pulps.   Many authors point out the benefits of describing the character of a material by as few and as independent properties as possible. In 1957, Steenberg stated: “Any valuable theory must be supposed to include a number of independent factors”. However, within the mechanical pulping area it is common practise to evaluate the character of pulp with respect to a wide range of more or less correlated measured pulp and fibre properties. In the review of the last 23 IMPCs we found that more than 96% of the variables examined in the articles where of that kind. In our efforts to describe a mechanical pulp with respect to its highly heterogeneous nature we have among others been inspired by Forgacs who worked with independent common factors in order to characterize mechanical pulps. He presented a paper in 1963 where he states that at least two independent factors are needed to describe a mechanical pulp. They reflect shape and length of the particles. Also Strand has inspired us with his work in the 80’s where he used factor analysis on a huge database to derive two independent common factors reflecting “bonding” (Factor 1) and “fibre length” (Factor 2). Examining a few independent common factors instead of several conventionally measured properties, which are more or less correlated, makes it easier to get an overview of the status of the processed material. Therefore, it is a little surprising that independent common factors constitute only 4% of the variables presented at the IMPCs since 1973. Strands approach was tested in a long-term evaluation in two mills. It was possible to produce a paper product more uniform in quality, compared to common practise. However, none of the above-mentioned independent factors reflects the heterogeneity of the pulp.   Paper and pulp makers commonly agree that, within certain limits, uniformity is the most important characteristic of both the pulp and the paper. If we know how to perform uniformly, we may also be able to move into other operating areas (or volumes) in a controlled way. However, there is no common agreement on how to define "uniformity". Papermakers are still to a great extent specifying their demands on the pulp in terms of dewatering ability and average length-weighted fibre length although the correlation to product quality is vague and weak and varies over time. Almost since the advent of mechanical pulping processes, the operators have for process control had readings of dewatering ability of a pad consisting of billions of particles expressed as mL of water and average length-weighted fibre length of the pulp, which are far from being independent factors. Variations in any of these two properties may depend on variations in a combination of several more underlying factors. Therefore, it is hard to know what actions the operators should take to avoid running off spec. So far, the main development in the concept with dewatering and length to assist the operators have been firstly, to get time trends of these variables on a DCS screen instead of on a piece of paper in the control room, and secondly to get the readings more frequently with on-line analysers. During the same period, there have been an immense development of refiner concepts, fractionation, process design, modelling, use of raw material, fibre characterization, and new products.   By putting more attention to reality and describing mechanical pulp as a heterogeneous material, which the mechanical pulps truly are, we hope to be able to get a more profound understanding how wood particles are developed along the process all the way to product. We also hope to give the operators in the mechanical pulping plant a more realistic description of the material they are supposed to deliver to the paper and board makers in order to facilitate their possibilities to produce a more uniform product quality at minimum cost.  The aim of our presentation is to share some of our insights and reflections how to describe the heterogeneous nature of mechanical pulps to the mill operators.

    We have applied factor analysis on particle level based on measurements in an optical analyser of fibre diameter, fibre wall thickness, fibre length, and fibre fibrillation. Examples will be presented of how the raw material and the process have set characteristic fingerprints in terms of the distribution of an independent common bonding factor on particle level. It is fascinating to see how much that may be hidden behind averages, c.f. Rosling et al. (2018) who warn against comparing averages, which often obstruct a more profound understanding of a subject.   In our presentation, we intend also to discuss how a description of the heterogeneity of the material may be used to get measures of energy efficiency of the process, separation efficiency of fractionation equipment, and how to link fibre characteristics to properties of products. Some reflections will also be shared on what we think is further required to get a more realistic description of the heterogeneous material we call mechanical pulp. Reference:  Rosling H., Rosling Rönnlund A., Rosling O., (2018), ”Factfulness”, Natur & Kultur,  ISBN 978-91-27-14994-6

  • 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.
    Hill, Jan
    QualTech AB.
    Ferritsius, Johanna
    Some insights regarding standards and common practice2015Conference paper (Refereed)
  • 10.
    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.

  • 11.
    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.

  • 12.
    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).

  • 13.
    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.
    Rundlöf, Mats
    Capisco.
    Ferritsius, Johanna
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Daniel, G
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Heterogeneity of mechanical pulp particles - variations and correlations beyond averagesManuscript (preprint) (Other academic)
  • 14.
    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. Stora Enso Kvarnsveden.
    Rundlöf, Mats
    Capisco.
    Reyier Österling, Sofia
    Dalarna University.
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Heterogeneity of Thermomechanical and Chemi-thermomechanical Pulps described with distributions of an independent common bonding factor on particle level2022In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 17, no 1, p. 763-784Article in journal (Refereed)
    Abstract [en]

    Particles in mechanical pulp show a wide variety but are commonly described using averages and/or collective properties. The authors suggest using distributions of a common bonding factor, BIND (Bonding INDicator), for each particle. The BIND-distribution is based on factor analysis of particle diameter, wall thickness, and external fibrillation of several mechanical pulps measured in an optical analyser. A characteristic BIND-distribution is set in the primary refiner, depending on both wood and process conditions, and remains almost intact along the process. Double-disc refiners gave flatter distributions and lower amounts of fibres with extreme values than single-disc refiners. More refining increased the differences between fibres with low and high BIND. Hence, it is more difficult to develop fibres with lower BIND. Examples are given of how BIND-distributions may be used to assess energy efficiency, fractionation efficiency, and influence of raw material. Mill scale operations were studied for printing-grade thermomechanical pulp (TMP), and board-grade chemi-thermomechanical pulp (CTMP), both from spruce.

  • 15.
    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.

  • 16.
    Ferritsius, Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Persson, Johan
    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.
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Opportunities and challenges in describing the heterogeneity of fibres2022In: Proceedings of the International Mechanical Pulping Conference, 2022, p. 28-33Conference paper (Other academic)
    Abstract [en]

    Particles in mechanical pulp are a heterogeneous popu-lation, but commonly described using averages based on wide and skewed distributions. It was found that these aver-ages may lead to erroneous conclusions regarding the char-acter of the material and also how the material has been de-veloped along the process. This study is based on measure-ments of individual particle dimensions (length, curl, and ex-ternal fibrillation) in mill operation of CTMP and TMP as detected in an optical analyser.

  • 17.
    Ferritsius, Olof
    et al.
    Stora Enso Research, SE-791 80 Falun, Sweden.
    Rautio, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics. Stora Enso Research, SE-791 80 Falun, Sweden.
    Differences on fibre level between GW and TMP for magazine grades2007In: International Mechanical Pulping Conference 2007, TAPPI, TAPPI Press, 2007, Vol. 1, p. 87-96Conference paper (Refereed)
    Abstract [en]

    In paper making, surface properties are of major importance for the printability of the final paper. It is therefore essential to identify the fundamental fibre properties causing surface problems in order to be able to improve the final paper. It is well known that the amount of intact fibres is higher in TMP than in GW. It is also believed that thick-walled intact fibres, especially large-diameter fibres, are negative for surface properties. When TMP and GW for magazine grades are analyzed with respect to fibre dimensions by scanning electron microscopy (SEM) images of fibre cross-sections, far more thick-walled fibres are found in TMP than in GW. It is therefore probably more important in quality control to focus on thick-walled fibres for TMP than for GW. On the other hand the amount of shives is considerably higher for GW than for TMP and such material is also negative for the surface properties. Both shives and fibre dimensions have been analyzed using cross sectional SEM images of Bauer McNett >50 fractions in a study including screening, cleaning and reject refining of a GW pulp for magazine paper. The same analysis was also conducted for a number of different final GW pulps and one TMP used for magazine paper. Slotted screens are commonly used today for successfully separating large shives, but are not capable of removing smaller shives. It is obvious that most of the shives measured in a Somerville laboratory screen (0,15mm slots) will be separated in the slotted screens. However, measuring shives in cross sections shows that only a small amount of the shives is separated in the screens. Even if the pulp has been treated in both screens and cleaners, approximately one third of the shives still remain. This indicates how difficult it is to get rid of shives in the screen room, and therefore it is critical to minimize the amount of shives in the grinding process. Despite the fact that Somerville shive measurements indicated no significant difference between different commercial mechanical pulps for magazine paper (GW and TMP), major differences in shives measured in cross sections of the fibres were found. The amount of shives was higher compared to the amount of large thick-walled fibres for most GW pulps, but for TMP it was the opposite in this comparison. It is therefore probably important to focus on reduction of shives in GW pulping and on reduction of thick-walled fibres for TMP. In mechanical pulping it is important to manufacture a pulp with as low an amount of shives as possible, especially if the screen room only has screens.

  • 18.
    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. 

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    fulltext
  • 19.
    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. 

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    fulltext
  • 20.
    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.

  • 21.
    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.

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    IMP_fibers_Ferritsius
  • 22.
    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.

  • 23.
    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)
  • 24.
    Ferritsius, Rita
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Stora Enso Paper Kvarnsveden Mill, Borlänge.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Holmen Paper, Norrköping.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlöf, Mats
    Daniel, Geoffrey
    Mörseburg, Kathrin
    Fernando, Dinesh
    Development of fibre properties in mill scale high- And low consistency refining of thermomechanical pulp (Part 1)2020In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 35, no 4, p. 589-599Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate changes in fibre properties with high (HC)- and low consistency (LC) refining of TMP and determine how these contribute to tensile index. Two process configurations, one with only HC refining and another with HC refining followed by LC refining were evaluated in three TMP mainline processes in two mills using Norway spruce. An increase in tensile index for a given applied specific energy was similar for all LC refiners in the three lines, despite differences in the fibre property profiles of the feed pulps. Compared with only HC refined pulps at a given tensile index, HC+LC refined pulps had greater fibre wall thickness, similar fibre length, strain at break and freeness, but lower light scattering coefficient, fibre curl and external fibrillation. The degree of internal fibrillation, determined by Simons' stain measurements, was similar for both configurations at a given tensile index. The results indicate that the increase in tensile index in LC refining is largely influenced by a decrease in fibre curl and in HC refining by peeling of the fibre walls. Compared at a given tensile index, the shive content (Somerville mass fraction) was similar for both HC+LC and HC refining. 

  • 25.
    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)
  • 26.
    Johansson, O.
    et al.
    InovoCell, Inc., Brookfield, United States.
    Fernando, D.
    SLU, Uppsala.
    Fenitsius, R.
    Stora Enso AB, Borlänge.
    Daniel, G.
    SLU, Uppsala.
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Advancements in optical analysis yields new insight to mechanical pulping processes in an efficient and inexpensive way2016In: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, p. 267-276Conference paper (Refereed)
    Abstract [en]

    Operating costs, pulp quality, and loss of markets continue to dominate the concern of mechanical pulp producers. The search for process improvements, new products, and cost reductions requires significant amount of pulp testing to find out how improvements or new products can be achieved. Unfortunately, the required testing comes at a significant cost due to the time consuming and labor intensive preparation of each sample. For example, a detailed analysis which requires fractionation, hot disintegration, hand sheets, etc. may cost in excess of a thousand dollars. Thus, for an in-depth study where one compares different processes or operating conditions, the cost is significant. At the IMPC conference in Helsinki 2010, 2014 Fernando & Daniel showed how a modern variation of Simon staining can be used to gain information about the fiber wall conditions. This idea has now been expanded further by combining traditional fiber morphology measurements with the information gained from the measurement of color and intensities. In this paper, we will demonstrate a new approach to evaluate mechanical pulps using a special optical analyzer with the ability to process images in color or image intensities. The additional information gained from the color of the images is discussed. For the study, we have been comparing results from three modem commercial installations. The results from these trials are discussed using traditional testing methods in an earlier paper by Ferritsius et al., (2016). We will continue the discussion and show how these pulp samples were analyzed with a new optical device involving minimal sample preparations.

  • 27.
    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.

  • 28.
    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.

  • 29.
    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.

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    fulltext
  • 30.
    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.

  • 31.
    Lindström, Stefan B
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Persson, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Ferritsius, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Multivariate lognormal mixture for pulp particle characterization2024In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 31, no 3, p. 1843-1854Article in journal (Refereed)
    Abstract [en]

    We present a method for pulp particle characterization based on a truncated lognormal mixture (TLM) model, as motivated by size statistics of organisms. We use an optical fiber analyzer to measure the length–width distribution of kraft-cooked roundwood or sawmill sources, of chemi-thermomechanical pulp (CTMP) samples from roundwood or sawmill sources, and the same CTMP samples after kraft post-processing. Our results show that bimodal TLMs capture salient features of the investigated pulp particle distributions, by decomposition into a large-particle and a small-particle fraction. However, we find that fibers from sawmill sources, which have not undergone mechanical treatment, cannot be described by TLM, likely due to non-random sampling. Within the confines of our dataset, the TLM characterization predicts laboratory sheet properties more effectively than conventional averaging methods for pulp particle size distributions. The TLM characterization is intended as a tool for controlling the pulp production process towards higher product quality, uniformity, and energy efficiency, pending further mill trials for validation. 

  • 32.
    Reyier, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics. Stora Enso Kvarnsveden, SE-781 91 Borlänge, Sweden.
    Ferritsius, Olof
    Stora Enso Falun Research Center, S Mariegatan 18, SE-791 80 Falun, Sweden.
    Shagaev, O
    Noss AB, Box 20, SE-60102, Norrköping, Sweden.
    Ways to measure the bonding ability distribution of fibers in mechanical pulps2007In: International Mechanical Pulping Conference 2007, TAPPI, TAPPI Press, 2007, Vol. 1, p. 97-111Conference paper (Refereed)
    Abstract [en]

    In this paper, experiences are reported from our work of developing a method for characterizing fibers with respect to their distribution in fiber bonding ability. As a first step to develop a method, fibers from two commercial TMPs have been fractionated in a four stage hydrocyclone system. The feed pulp was separated into five streams. The fiber bonding ability of R16, P16/R30 and P30/R50 Bauer McNett fractions collected from each stream were analyzed. Five different ways of evaluating fiber bonding ability showed that the fibers were separated in the hydrocyclones according to bonding ability. It was found that both fibrillation and collapse resistance index (CRI) of the fibers are required in order to well predict tensile strength of handsheets made from fiber fractions. CRI was calculated from optical measurements of cell wall thickness and fiber width. We also propose how to describe the distribution in fiber bonding ability for mechanical pulps. A method to calculate fracture toughness of handsheets based on acoustic emission is also illustrated. A more rapid method for characterizing fibers in mechanical pulps with respect to their bonding ability distribution needs to be developed in the future.

  • 33.
    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.

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    Reyier_fiber_dimensions
  • 34.
    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.

  • 35.
    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.

  • 36.
    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)
  • 37.
    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. Stora Enso.
    Energy efficiency in mechanical pulping-definitions and considerations2021In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 36, no 3, p. 425-434, article id 0013Article in journal (Refereed)
    Abstract [en]

    Production of mechanical pulps requires high specific electrical energy compared to many other attrition processes. In Scandinavia, the lowest specific refining energy for production of thermomechanical pulp is around 1800 kWh/t for newsprint quality, which is roughly 60 times higher than for crushing of stone to a similar size distribution. The high specific energy demand for refining has naturally motivated large efforts in the search for improved efficiency. It is always practical to be able to quantify improvements in efficiency for comparison of process designs and of different machine types. However, there is no commonly accepted definition of efficiency for mechanical pulping processes. In published work within mechanical pulping, energy efficiency has been presented in different ways. In this paper, we discuss definitions of energy efficiency and aspects that ought to be considered when energy efficiency is presented. Although focus of this work is on energy efficiency for refiner processes, the principles can be applied to other types of mechanical pulping processes such as stone groundwood. 

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