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  • 51.
    Enberg, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Rundlöf, Mats
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Paulsson, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Oyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    The influence of process waters on optical properties during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, nr 2, s. 344-355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To evaluate the causes behind the formation of colour in mill systems, the effect of different process waters on the optical properties of hydrogen-peroxide bleached Norway spruce mechanical pulp during storage was studied. The influence of process water type, temperature, time, pulp consistency and pH was evaluated over the visible range of wavelengths. The darkening was more pronounced when pulp was stored in process waters compared to in distilled water. Increased temperature and prolonged storage times increased the darkening as expected, whereas a higher storage consistency gave less darkening than a lower storage consistency (15% compared to 5%). The pH value that gave the lowest brightness reduction and a minimum in Delta k(460) was found to be 5.5-6.0. Storage of pulp in white water from the paper machine resulted in a broad shoulder in the k spectra indicating colour formation related to the particles in this water. Part of this shoulder in absorption spectra was related to added dyes, but the increase in absorption with time is likely to be caused by some other colour formation. The colour measured as a*, b* showed that the storage changed the colour of the pulp towards red and yellow, and initially more towards red.

  • 52.
    Enberg, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Norske Skog Saugbrugs AS, NO-1756 Halden, Norway .
    Rundlöf, Mats
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Capisco Science and Art, SE-602 34 Norrköping, Sweden.
    Paulsson, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. AkzoNobel Pulp and Performance Chemicals, SE-445 80 Bohus, Sweden.
    Johnsen, Ingvild A.
    Paper and Fibre Institute, NO-7491 Trondheim, Norway .
    Axelsson, Patrik
    Norske Skog Saugbrugs AS, NO-1756 Halden, Norway .
    The influence of process conditions during pulp storage on the optical properties of Norway spruce mechanical pulps2013Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, nr 2, s. 203-210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this work was to study the influence of process conditions (time, pH, temperature and consistency) on the optical properties of mechanical pulps during storage in a clean system as a reference for further work. Laboratory storage trials were performed with unbleached and hydrogen-peroxide bleached well-washed Norway spruce pulps. In general, the pulp darkened during storage due to an increase in light absorption, especially at shorter wavelengths. After long storage times, the light absorption coefficient, k had increased also at longer wavelengths. No specific peaks were seen in Delta k-spectra. The increase in light absorption was most rapid initially, during the first four hours, for all pulps when stored at high temperature (80 degrees C), and then proceeded more slowly. The corresponding change in colour, measured as a* and b*, was shifted towards red and somewhat towards yellow, and over longer periods of storage, the shift towards yellow became greater. Time and temperature were found to have the largest impact. The effects were similar regardless of the starting pH (4.3-9.7) and pulp consistency (5%-25%). The hydrogen-peroxide bleached pulps were more sensitive to storage compared to the unbleached pulp at temperatures above 50 degrees C. At storage times of up to four hours, the unbleached pulp showed no loss of brightness at either of the storage temperatures. A slightly less bleached pulp darkened more than a highly bleached pulp at all wavelengths. The only difference measured between the two pulps was that the less bleached pulp had a higher content of iron. This higher iron content may be at least part of the reason for the more extensive darkening.

  • 53.
    Engberg, Birgitta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Logenius, Louise
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Mechanical properties of sulphonated wood in relation to wing refiner properties2014Ingår i: International Mechanical Pulping Conference, IMPC 2014, Espoo: Paper Engineers' Association (PI) , 2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    To reach maximum effect of different pretreatments we need to know how wood properties can be changed and how this can be related to both refining conditions and pulp characteristics. To understand how the material properties were affected, sulphonated wood samples were tested using several new testing techniques. The data was correlated to pulp properties of batch refined chips to learn more how the initial defibration mechanisms and pulp properties were affected by the pretreatments.

  • 54.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Energy efficient mechanical pulping – summary of the Scandinavian industry initiative research work 2011 - 20152016Ingår i: 2016 International Mechanical Pulping Conference, Jacksonville, Florida, USA  September 28-30, 2016: SESSION 11: INDUSTRY INITIATIVE FOR ENERGY REDUCTION / [ed] Robert Lanouette, Georgia 30092 USA: TAPPI Press, 2016, s. 288-303Konferensbidrag (Refereegranskat)
    Abstract [en]

    A research program funded by the Swedish Energy Agency, the Swedish Knowledge Foundation and the Research Council of Norway was initiated by the companies; Holmen, Norske Skog, SCA and Stora Enso during 2008 with the objective to demonstrate techniques to reduce electrical energy demand by 50% for production of TMP and CTMP within a 10-year period starting 2011, while retaining similar final product characteristics of printing paper and paperboard. A gap analysis was performed to summarize different options to reach the goal at similar final product quality properties. The gap analysis indicated that some different approaches based on earlier research work both in pilot and demonstration scale together with improved process and product quality control should make it possible to reach the very tough goal. The very thorough benchmarking study was performed during 2012 including 16 TMP and CTMP-lines in Norway and Sweden showed the best production lines had the following electrical energy demands to certain final product properties; 900 kWh/t for CTMP optimized for paperboard, 1800 kWh/t for TMP optimized for newsprint and 2800 kWh/t for TMP optimized for SC-paper. The best results reached in industrial demonstration tests until 2015 showed potential to reduce the energy demand from 900 to 700 kWh/t for paperboard CTMP, from 1800 to 1400 kWh/t for newsprint TMP and from 2800 to 2400 for SC-paper TMP. In addition the results from other research within the program in the form of pilot and demonstration trials indicates that it could be possible to reach the goal of 50% reduced energy demand within a 10-year period provided that the industry and the research funds will continue to finance a continuation of the research program. 

  • 55.
    Engstrand, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Carlberg, T.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hellström, Lisbeth M.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Gradin, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kvalitetsteknik, maskinteknik och matematik.
    Gregersen, Øyvind Weiby
    NTNU - Norges teknisk-naturvitenskapelige universitet.
    Method for producing and processing wood chips [Förfarande för framställning av flis]2011Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    This patent application describes a method to produce wood chips with the intention of reducing the energy consumption in the subsequent process steps for pulp production. With the present method wood chipping is done in a wood chipper where the chipping tool (3) has an angle γ (4) within the interval of 75° to 105° between the fibre direction of the log and the side of the tool which faces the chip (2). Angles in this interval will cause an axially directed compression of the chip which will cause a cracking of the wood during chipping.

  • 56.
    Engstrand, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Gradin, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hellström, Lisbeth
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Carlberg, Torbjörn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Sandström, Peter
    SCA Reseach.
    Liden, Joar
    SCA Ortviken.
    Söderberg, Mats
    SCA Research.
    Mats, Egnell
    Andritz Iggesund Tools.
    Improved refining energy efficiency in thermo-mechanical pulping by means of collimated wood chipping – from solid mechanics to full scale evaluation2016Ingår i: PaperWeek Canada 2016 Conference February 1 to 5, 2016, Montreal: Technical Track Program / [ed] Greg Hay, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    The wood chipping process was never optimized with regard to high yield pulping processes as thermomechanical pulping (TMP) and chemithermomechanical pulping (CTMP). It is generally believed that wood chips for pulping should be produced in such a way that the degree of damage is minimized and that the chip dimensional distribution should be as narrow as possible. Since the TMP and CTMP processes were developed in the 60-ies and 70-ies, compression screw as well as roll nip equipment have been developed to pretreat wood chips as a way to reduce refining energy consumption to given fiber and pulp properties and also in order to improve impregnation. The general conclusions are that a combination of shear and compression in the tangential or radial direction of the wood initiates cracks that later in the refiner will enhance and optimize fiber separation and also fiber property development. The idea with the collimated chipping technology is to utilize the wood chipper as a tool, combining cutting of wood logs to wood chips with a pretreatment of the chips by creating cracks that would enhance fiber separation, fiber surface development as well as chip-impregnation. In this case the compression is performed in the wood fiber direction, in which direction wood actually is weakest when it comes to compression induced cracking. The maximization of the amount of cracks in wood-chips is performed by optimizing the knife angle (or spout angle) in the chipper, to what we call collimated chipping (according to a patent owned by CCT AB). This presentation describes a theoretical background and two demonstration scale studies performed by SCA Forest Products at their Ortviken mill. One conclusion drawn, based on two-month test period with three weeks of collimated chipping, was that specific refining energy reduction was around 100 kWh/adt of the 1400 kWh/adt used in primary stage double disc refining. Most probably the potential is higher if the whole system is optimized. Tests were performed at constant production rate and energy was reduced by reducing power to constant freeness, leading to similar tensile and light scattering levels. The deliberately increased forces created in the wood chipper by means of an optimized (increased) edge angle caused more problems with knife holder equipment than normally, as well as increased vibrations. These problems will have to be solved for future long-term implementation of the technique.

  • 57.
    Engstrand, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Hammar, Lars Åke
    Innventia (STFI).
    Htun, Myat
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Pettersson, Rune
    STFI.
    Method of reducing the energy consumption at the refining of cellulose containing material [Sätt att reducera energikonsumtionen vid raffinering av cellulosahaltigt material]1987Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.

  • 58.
    Engstrand, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hammar, Lars Åke
    Innventia (STFI).
    Sjögren, Birger
    STFI (Innventia).
    Svensson, Börje
    Innventia (STFI).
    Htun, Myat
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    A method of producing cellulosic pulp1991Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Mechanical and chemimechanical cellulose pulp, particularly paper pulp, is produced at a low energy input by disintegrating and beating wood material in one or more stages. Acccording to the invention, a substance capable of forming complexes with polyvalent metal ions, particularly calcium ions, so-called complexing agent, is added to the wood material prior to the beating process in order to replace said calcium or other polyvalent metal ions with sodium ions, therewith a further reduction in the energy input is obtained.

  • 59.
    Engstrand, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Karlström, Anders
    Chalmers.
    System for continuously measuring pressure and temperature in the beating zones of refiners [System för att kontinuerligt mäta tryck och temperatur i malzonen hos raffinörer]1996Patent (Övrig (populärvetenskap, debatt, mm))
  • 60.
    Engstrand, Per O.
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engberg, Birgitta A.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Filling the Gap - Final Report2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Executive Summary

    As energy prices continue to rise long-term it is very important to come up with suggestions toefficiency-improving solutions based on modifications of the existing refining technology withoutlarge investments. There are several suggestions to relatively large modifications of processsolutions, in design of refiner plate patterns, chip pre-treatment and chip feed strategies to existingrefiners, but these suggestions are often expensive and difficult to implement as the knowledge ofthe mechanisms prevalent in the refiner gap is still insufficient.

    To help solving this problem FSCN and CIT initiated the research project “Filling the Gap” togetherwith the companies Dametric, Holmen, Metso Paper, Norske Skog, Pöyry, SCA and Stora Enso cofinancedby the Swedish authorities Vinnova and the Swedish Energy Agency. The research projectwas designed with the intension to show how to improve the electric energy efficiency of chiprefining by means of utilizing fundamental knowledge of wood material properties relevant for chiprefining in relation to refining hypotheses and in combination with output variables from new andimproved refining zone measurement methods as; exact gap distance, temperature-, force- and fibrematerial radial distributions combined with the traditional out/in-put variables normally used. Thepotential of the above mentioned ideas as well as the specific goal of this project was to show how toreach 25% efficiency improvement in existing refiners and at the same time reduce refiner causedstops by >50% and plate wear also by >50%.

    The data produced within the project was utilized in two ways:

    1. To optimize refining conditions in a static way, i.e. optimization of conditions to maximizeenergy efficiency to reach the functional fibre properties aimed for.

    2. To maximize process stability and minimize quality variations at the functional fibreproperties aimed for.

    The general conclusion from the project is that we can show that there are great opportunities toimprove electric energy efficiency in refining according to the goal by means of using the abovementioned measurement techniques. More specifically the full-scale trials performed during theperiod 2010 – beginning of 2013 showed the possibility to improve the electric energy efficiency by25% at similar functional properties of the pulp, i.e. a reduction in electricity consumption by 20%. Inorder to implement similar strategies in other TMP or CTMP lines it will just as in this case benecessary to use the same measurement system and evaluation techniques together with verythorough and statistically well controlled pulp/fibre evaluation techniques. It would of course beinteresting to implement the same techniques on as many other production lines as possible withinthe participating companies, but it must be emphasized that the procedure is very demanding. Eachproduction line needs to perform a corresponding detailed process analysis as the one performed inthe mill case study of this research project. Furthermore it would also be necessary to utilize therefiner gap measurement techniques, especially the combination of temperature profile and gapdistance measurements, in a modern but still simple process control system making it easier for theoperator to continuously run the process in a more energy efficient mode. Implementation of thetechniques evaluated in pilot scale within this research project, i.e. fibre distribution and force3distribution measurements, would of course have potential to further improve the process efficiencyas well as improve the fibre property level.

  • 61.
    Engstrand, Per O.
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Björkqvist, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Johansson, Lars
    PFI.
    Johansson, Örjan
    Luleå Tekniska Universitet.
    Daniel, Geoffrey
    Sveriges Lantbruks Universitet.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Karlström, Anders
    Chalmers.
    Karlsson, Anette
    SCA Forest Products AB, Ortviken.
    Sandberg, Christer
    Holmen Paper, Braviken.
    Mekmassainitiativet för energieffektivitet, e2mp-i2015Rapport (Övrigt vetenskapligt)
    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.

  • 62.
    Engstrand, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Pettersson, Rune
    STFI.
    Htun, Myat
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hammar, Lars Åke
    Innventia (STFI).
    Svensson, Börje
    Innventia (STFI).
    Method of making mechanical and chemi-mechanical papermaking pulp [Framställning av mekanisk och kemimekanisk massa i två steg]1989Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The invention relates to a method of manufacturing mechanical and chemi-mechanical papermaking pulp with low energy input by disintegrating and beating wood material in at least two steps. According to the invention, the material is coarse-disintegrated in a first step at a concentration exceeding 20 %, acid groups in the wood material are neutralized, the material is diluted to a concentration of 1-10 % and beaten in one or several steps.

  • 63.
    Eriksson, Alexander
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Tryckfall över värmeväxlare: En empirisk och teoretisk jämförelse av tryckfall över värmeväxlare2018Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Examensarbetet är utfört på uppdrag av Scandymet AB. Huvudsyftet med arbetet är att undersöka om deras kalkylprogram överdimensionerar tryckfallet vid produktionen av värmeväxlare. Scandymets värmeväxlare används ofta i tuffa industrimiljöer och har höga krav på effektivitet för uppvärmning eller nedkylning, samt att materialet är korrosionsbeständig. För att utföra denna undersökning konstruerades en flödesrigg som hanterar uppvärmning och cirkulation av varmvatten. Till flödesriggen konstruerades även en datalogger, som via en Arduino Uno samlar in information från temperatur- och tryckgivare.  Scandymet har tillverkat fyra olika modeller av värmeväxlare som undersöktes med olika hastigheter på värmebäraren. Ett Exceldokument behandlar informationen på minneskortet och beräknar det laborativa tryckfallet för varje testomgång. Det laborativa resultatet jämförs därefter med företagets kalkylark som kontroll beräknas teoretiskt i ett separat Exceldokument. Sammanställningen resulterar i att kalkylarket överdimensionerar tryckfallet med 26–53% beroende på modell av värmeväxlare och hastighet. För att utreda överdimensioneringen analyseras kalkylarket, där det visade sig att faktorerna för tryckstötmotståndet ζ och rörfriktionskoefficienten λ har antagits vara betydligt högre än vad empiriska data visar.

  • 64.
    Eriksson, K.
    et al.
    CIT Industriell EnergI.
    Ferritsius, J.
    Uppsala University, Uppsala.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. 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 assessment2016Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, s. 1-11Konferensbidrag (Refereegranskat)
  • 65.
    Eriksson, K.
    et al.
    Chalmers Science Park, Göteborg.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Stora Enso Paper, Kvamsveden Mill.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hill, J.
    QualTech, Tyringe.
    Benefits from improved stability in process conditions and pulp properties-a double disc refiner case study2016Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, s. 317-327Konferensbidrag (Refereegranskat)
    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.

  • 66.
    Eriksson, K.
    et al.
    CIT (Chalmers industriteknik).
    Karlström, A.
    CTH (Chalmers tekniska högskola).
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. StoraEnso.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hill, Jan
    QualTech AB.
    Recent advances in modelling and control of TMP refining processes2015Konferensbidrag (Refereegranskat)
  • 67.
    Eriksson, Martin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Livcykelkostnad för ventilationssystem: En jämförelse mellan konventionell och hög luftomsättning för ökad kognitiv förmåga2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I detta examensarbete har två ventilationssystem konstruerats och jämförts gällande dimensionering, investerings- och livscykelkostnader. Alternativ A har utformats för konventionell luftomsättning medan alternativ B har utformats för att hantera en relativt hög luftomsättning. Idén till jämförelsen kom från ny forskning som har visat på att en relativt hög luftomsättning och resulterande lägre koldioxidhalt kan ha stor inverkan på den kognitiva förmågan hos individerna inom systemet. Utformning och dimensionering av systemen har gjorts med hjälp av programvarorna MagiCAD och Pro Unit. Arbetet har visat på tydliga skillnader i dimensioneringen av respektive system. Alternativ B kräver mer utrymme än alternativ A. I vissa delar av systemet är det till och med tveksamt om alternativ B är praktiskt möjligt att installera på grund av sitt behov av större kanaldimensioner. När det gäller investeringskostnad så har det under detta arbete visat sig att alternativ A är ungefär 30 % billigare än alternativ B om projektering, rivning av befintligt system, installation och material tas i beaktande. Detta var en oväntat liten prisskillnad i förhållande till den förväntade, men eftersom vissa delar av ventilationssystemet inte är inkluderade i konstruktionerna, som till exempel kanaler för ute- och avluft samt motoriserade spjäll för variabelt flödesbehov kan skillnaden i den slutgiltiga investeringskostnaden visa sig bli större i framtiden för alternativ B. Jämförelsen mellan livscykelkostnad för alternativen är central i detta arbete. En modell för att beräkna livscykelkostnader för respektive system har skapats i Excel. Livscykelskostnadsmodellen visar att alternativ B kan vara mer ekonomiskt fördelaktigt redan vid små tilläggskostnader för minskad kognitiv förmåga för alternativ A. Avslutningsvis så pekar detta examensarbete på att mer forskning behövs angående hur luftomsättning i ventilationssystem påverkar kognitiv förmåga hos individer inom systemet samt vilka konsekvenser och möjligheter detta kan innebära.

  • 68.
    Fagerlund-Edfeldt, Amelie
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Naturally occurring phenols with antioxidant, antifungal and anti-browsing activity2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 69.
    Fagerlund-Edfeldt, Amelie
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edman, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Jonsson, Bengt Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Effect of Debarking Water from Norway Spruce (Picea abies) on the Growth of Five Species of Wood-Decaying Fungi2014Ingår i: Zeitschrift für Naturforschung C - A Journal of Biosciences, ISSN 0939-5075, E-ISSN 1865-7125, Vol. 9-10, nr 69c, s. 418-424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Norway spruce (Picea abies) debarking water is an aqueous extract obtained as waste from the debarking of logs at paper mills. The debarking water contains a mixture of natural compounds that can exhibit diverse biological activities, potentially including fungicidal activity on some species of wood-decaying fungi. Thus, we investigated the growth rates of such fungi on agar plates to which debarking water extracts had been added. The experiment included five wood-decaying fungi, viz. Gloeophyllum sepiarium, Oligoporus lateritius, Ischnoderma benzoinum, Junghuhnia luteoalba, and Phlebia sp. Growth reduction was observed for all species at the highest tested concentrations of freeze-dried and ethanol-extracted debarking water, the ethyl acetate-soluble fraction and the diethyl ether-soluble fraction. However, the magnitude of the effect varied between different species and strains of individual species. The brown-rot fungi G. sepiarium and O. lateritius were generally the most sensitive species, with the growth of all tested strains being completely inhibited by the ethyl acetate-soluble fraction. These results indicate that development of antifungal wood-protecting agents from debarking water could potentially be a way to make use of a low-value industrial waste.

  • 70.
    Faria, Gregorio Couto
    et al.
    Stanford University, Instituto de Física de São Carlos (IFSC).
    Duong, Duc Trong
    Stanford University.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Rivnay, Jonathan
    École Nationale Supérieure des Mines de Saint Étienne.
    Malliaras, George
    École Nationale Supérieure des Mines de Saint Étienne.
    Owens, Roisin
    École Nationale Supérieure des Mines de Saint Étienne.
    Salleo, Alberto
    Stanford University.
    Modeling Transient Drain Current Response in Biofunctionalized Organic Electrochemical Transistors2015Konferensbidrag (Övrigt vetenskapligt)
  • 71.
    Ferritsius, Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    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 operations2016Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, s. 12-17Konferensbidrag (Refereegranskat)
  • 72.
    Ferritsius, Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. StoraEnso.
    Hill, Jan
    QualTech AB.
    Ferritsius, Johanna
    Some insights regarding standards and common practice2015Konferensbidrag (Refereegranskat)
  • 73.
    Ferritsius, Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. 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 index2017Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 1, s. 45-53Artikel i tidskrift (Refereegranskat)
    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.

  • 74.
    Ferritsius, Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    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 shift2018Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, nr 3, s. 468-481Artikel i tidskrift (Refereegranskat)
    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.

  • 75.
    Ferritsius, Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. StoraEnso Paper Kvarnsveden Mill.
    Rundlöf, Mats
    Capisco.
    Engberg, Birgitta A.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    The Independent State of Fibres in Relation to the Mechanical Pulping World2018Ingår i: IMPC 2018, Trondheim, Norway, 2018Konferensbidrag (Refereegranskat)
    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).

  • 76.
    Ferritsius, Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Mörseburg, K.
    PFI, Trondheim, Norway.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Stora Enso Kvamsveden Mill, Sweden.
    Bat of CTMP and TMP plants with respect to quality development and energy efficiency2014Ingår i: International Mechanical Pulping Conference, IMPC 2014, Paper Engineers' Association (PI) , 2014Konferensbidrag (Refereegranskat)
    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.

  • 77.
    Ferritsius, Rita
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. StoraEnso Kvarnsveden, Borlänge.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    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 tests2018Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, nr 1, s. 69-81Artikel i tidskrift (Refereegranskat)
    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. 

  • 78.
    Ferritsius, Rita
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. StoraEnso Kvarnsveden, Borlänge.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    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 tests2018Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, nr 1, s. 82-94Artikel i tidskrift (Refereegranskat)
    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. 

  • 79.
    Ferritsius, Rita
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Stora Enso Kvarnsveden Mill, Sweden.
    Hill, J.
    QualTech AB, Tyringe, Sweden.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Karlstrom, A.
    Chalmers University of Technology, Sweden .
    On energy efficiency in chip refining2014Ingår i: International Mechanical Pulping Conference, IMPC 2014, Paper Engineers' Association (PI) , 2014Konferensbidrag (Refereegranskat)
    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.

  • 80.
    Ferritsius, Rita
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Stora Enso Kvarnsveden Mill, Borlänge, Sweden .
    Sandberg, Christer
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Holmen Paper, Norrköping, Sweden .
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    LC-refining of mechanical pulps and its influence on fiber curl and handsheet strength properties2014Ingår i: International Mechanical Pulping Conference, IMPC 2014, 2014Konferensbidrag (Refereegranskat)
    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.

  • 81.
    Ferritsius, Rita
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Stora Enso Paper Kvarnsveden Mill.
    Sandberg, Christer
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Holmen Paper.
    Ferritsius, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    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 Refining2016Ingår i: TAPPI conference proceedings, TAPPI Press, 2016Konferensbidrag (Refereegranskat)
  • 82.
    Fiskari, Juha
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Valmet AB.
    Ferritsius, Rita
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Stora Enso Paper, Kvarnsvedens Mill.
    Osong, Sinke H.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Persson, Anders
    Valmet AB.
    Höglund, Tomas
    Valmet AB.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Deep Eutectic Solvent Treatment to Low-Energy TMP to Produce Fibers for Papermaking2018Ingår i: IMPC 2018, Trondheim, Norway, 2018Konferensbidrag (Refereegranskat)
    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.

  • 83.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Htun, Myat
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    On the relationship between charged groups, chemical environment and delamination during refining.2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Improved understanding regarding how to optimise the degree of swelling in the wood fibre wall may be a way to reduce the energy demand in the refining process. The forces necessary to achieve fibrillation (internal as well as external) are greatly influenced by the swelling properties of the fibre wall. The degree and position of swelling is also the main cause to where in the wood matrix the fibre separation will take place. Refining of wood chips in different state of swelling will result in mechanical pulp fibres with different optical and mechanical properties.

     

    The typical parameters that influence the wood fibres’ ability to swell are temperature, pH, ionic form, amount of charged groups and ionic strength. Water retention value is one way to measure the pulp´s capacity to retain water after centrifugation and is strongly correlated to the swelling ability of wood fibres.

     

    A blowline-sample of Norway spruce thermomechanical pulp (TMP) taken out directly after the chip-refining step was used as reference material for this study. The sample was treated with sodium sulphite under different conditions to introduce a range of very low to very high degrees of sulphonic acid groups in the cell walls. In a similar way alkaline hydrogen peroxide was used to introduce a range of very low to very high degrees of carboxylic acid groups. Each sample was then ion-exchanged into proton, sodium, calcium and aluminium form.

     

    The effect of the amount of sulphonic and carboxylic acid groups in combination with the effect of counter ion, on the swelling capacity of mechanical pulp fibres was investigated. In addition, all samples were measured in a temperature interval between 25°C and 95°C to monitor changes in the softening temperature due to lignin structure modifications.

  • 84.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Htun, Myat
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    ON THE RELATIONSHIP BETWEEN WOOD FIBRE WALL SWELLING, CHARGED GROUPS, AND DELAMINATION DURING REFINING2013Ingår i: J-FOR-JOURNAL OF SCIENCE & TECHNOLOGY FOR FOREST PRODUCTS AND PROCESSES, ISSN 1927-6311, Vol. 3, nr 4, s. 30-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of sulphonic and carboxylic acid groups in combination with the effect of counter ion form, on the swelling capacity of mechanical pulp fibres was studied by means of water retention value (WRV) measured in the temperature range from 25 to 95oC. Mechanical pulp fibres (TMP) were treated with hydrogen peroxide and/or sodium sulphite during conditions resembling those used in chemimechanical and bleaching processes commonly used in the industry. In conventional chemimechanical processes sulphite treatment is used before refining while peroxide treatment can be utilized both before and after refining. In this study we did however also use sulphite after peroxide treatment. When subjecting sodium sulphite treated pulps to a subsequent hydrogen peroxide step, all pulps show a decrease in sulphonic acid groups, which could be owed to dissolution of highly charged lignin. Pulps treated with a high hydrogen peroxide charge (4%), showed a loss in carboxylic acid groups during subsequent treatment with sodium sulphite. This loss is probably due to dissolution of highly charged fibre material such as demethylated pectins. Both increased degree of sulphonation and carboxylation of the lignin reduces the softening temperature by means of reducing the degree of cross-linking in the lignin matrix. This softening probably improves the compressibility of the fibre pads in the sample holders of the WRV centrifuge, which would counteract an otherwise expected increasing WRV-value due to increased swelling potential. This makes it difficult to see clear trends in WRV as a function of increase in degree of sulphonation and carboxylation. When changing counter ion form from proton or calcium form to sodium form there is however always a clear increase in WRV in the range from 20 to 30%.

  • 85.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Htun, Myat
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    On the relationship between wood fibre wall swelling, charged groups, and delamination during refining2013Ingår i: Journal of Science & Technology for Forest Products and Processes, ISSN 1927-6311, E-ISSN 1927-632X, Vol. 3, nr 4, s. 30-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of sulphonic and carboxylic acid groups in combination with the effect of counter-ion form on the swelling capacity of mechanical pulp fibres was studied by means of water retention value (WRV) measured in the temperature range from 25oC to 95oC. Mechanical pulp fibres (TMP) were treated with hydrogen peroxide, sodium sulphite, or both under conditions resembling those used in chemi-thermomechanical and bleaching processes commonly used in the industry. In conventional chemi-thermo-mechanical processes, sulphite treatment is used before refining, whereas peroxide treatment can be used both before and after refining. However, in this study, sulphite was also used after peroxide treatment. When sodium sulphite-treated pulps are subjected to a subsequent hydrogen peroxide step, all pulps show a decrease in sulphonic acid groups, which can be attributed to dissolution of highly charged lignin. Pulps treated with a high hydrogen peroxide charge (4%) show a loss in carboxylic acid groups during subsequent treatment with sodium sulphite. This loss is probably due to dissolution of highly charged fibre material such as demethylated pectins. Both the increased degree of sulphonation and carboxylation of lignin reduce the softening temperature reducing the degree of cross-linking in the lignin matrix. This softening probably improves the compressibility of the fibre pads in the sample holders of the WRV centrifuge, which would counteract the otherwise expected increase in WRV due to increased swelling potential. This phenomenon makes it difficult to see clear trends in WRV as a function of increasing degrees of sulphonation and carboxylation. When changing the counter-ion form from proton or calcium form to sodium form, there is, however, always a clear increase in WRV in the range from 20% to 30%.

  • 86.
    Forsberg, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Paper-based supercapacitors2015Konferensbidrag (Övrigt vetenskapligt)
  • 87.
    Forsberg, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Kumar, Vinay
    Åbo Akademi University.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Maristiina, Nurmi
    Åbo Akademi University.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Martti, Toivakka
    Åbo Akademi University.
    Effect of calendering and coating formulations on conductivity in paper-based electrodes2016Konferensbidrag (Refereegranskat)
  • 88.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Engholm, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Photodetector of multilayer exfoliated MoS2 deposited on polyimide films2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We fabricated a photodetector based on multilayer molybdenum disulfide (MoS2) by micromechanical cleavage of a molybdenite crystal using a polyimide film. We deposited 40 nm of gold by vacuum sputtering and copper tape was used for the contacts.  Without any surface treatment, we achieved high responsivity at different incident optical power. The calculated responsivity was 23 mA/W of incident optical power in the range between 400 and 800 nm. For the responsivity measurement it was estimated that MoS2 have a bandgap of 1.6 eV, which lies between monolayer and multilayer films. The thickness of the MoS2 thin film was determined by Raman spectroscopy evaluating the difference between the in plane  and out of plane  Raman modes. The measurement of IV curves indicated Ohmic contacts in respect to the Au regardless of the incident optical power. Our device fabrication was much simpler than previous reported devices and can be used to test the light absorption and luminescence capabilities of exfoliated MoS2.

  • 89.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Maslik, Jan
    Tomas Bata University.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Toivakka, Martti
    Åbo Akademi University.
    Koppolu, Rajesh
    Åbo Akademi University.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Printability of functional inkjet inks onto commercial inkjet substrates and a taylor made pigmented coated paper2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Printed electronics are of increasing interest. The substrates used have primarily been plastics although the interest for cellulose-based substrates is increasing due to the environmental aspect as well as cost. The requirements of substrates for electronically active inks differs from graphical inks and therefore we have investigated a custom-made pigment based coated paper and compared it to commercial photo-papers and a coated PE film.

    Our goal with the study of different substrates was to select the most suitable substrate to print water based 2D materials inkjet inks for flexible electronics.

    The discovery of graphene, a layered material achieved from the exfoliation of graphite, has resulted in the study of other materials with similar properties to cover areas where graphene could not be used due to the absence of a bandgap in the material. For example in thin film transistors (TFT) a semiconductor layer is essential to enable turn on and off the device. This semiconductor layer can be achieved using various materials but particular interest have been dedicated to abundant and cheap 2D materials such as the transition metal dichalcogenide (TMD) molybdenum disulfide (MoS2). To date, most of the dispersions based on TMDs use organic solvents or water solutions of surfactants. Previously we focus on the study of environmental friendly inks produced by liquid phase exfoliation (LPE) of MoS2 in water using cellulose stabilizers such as ethyl cellulose (EC), cellulose nanofibrils (CNF) and nanofibrilcellulose (NFC). We have study various aspects of the ink fabrication includi  ng pH range, the source of MoS2, nanosheets thickness, particle size distribution,  ink stabilizers, ink concentration, viscosity and surface tension. These inks have very low concentration requiring a number of printing passes to cover the substrate. Therefore the substrate selection is crucial as a large amount of solvent is to be absorb by the substrate. Our goal was to use such an ink to print electrodes of MoS2 into a paper substrate after substrate selection.

    Commercial photo papers, a commercial coated PE film and a tailor made multilayer pigment coated paper substrate were used for the substrate selection analysis.  We print the substrates using a DIMATIX inkjet printer with a 10 pL printing head using the distillated water waveform supplied by the printer manufacturer. The voltage used was 23V and 4 nozzles were used for the print outs. The inkjet ink used was the organic PEDOT:PSS. We printed lines ranging from 1 pixel to 20 pixels with 1, 2 and 3 printing passes. The printing quality was evaluated through measurements of the waviness of the printed lines measured after imaging the printed samples with a SEM microscope. The line width measurement was done using the software from the SEM.

    We also evaluated the structure of the coatings using SEM and topography measurements. The ink penetration through the substrates was evaluated using Raman Spectroscopy. For the pigmented coated sample we measured 4% of ink penetration through the substrate for the 1pxl printed line printed once onto the paper.  Cross-section SEM images of the printed lines were made to visualize the ink penetration into the substrate.

    Regarding the electrical conductivity of the printed samples, the differences in resistivity varying the width of the printed lines and the number of printed passes were evaluated. The resistivity of the printed electrodes was evaluated using the 2-points probe method. Before the resistivity measurements, the printed substrates were heated at 50°C and 100°C for 30 minutes in an oven.

    We choose the PEDOT:PSS ink because it is a low price ink compared to metal nanoparticles inks for printed electronics. The print outs had low resistivity at a few printing passes with no need for sintering at high temperatures. The MoS2 ink has a very high resistance at a few printing passes due to lower coverage of the substrate therefore for this ink these measurements were not possible to be made. The main pigment composition of the paper coatings of the substrates was evaluated using FT-IR and EDX, these data plus the coating structure evaluated by SEM was related to the print quality.

    The best in test papers were used to print MoS2 electrodes. After the printing tests, another step for the optimization of the MoS2 ink properties shall be carried out in future studies for better print quality. We also evaluated the surface energy of the substrates through contact angle measurements to match the surface tension of the PEDOT:PSS ink and later the MoS2 ink. Although the pigmented coated printing substrate did not show better results than the commercial photo papers and PE foil in terms of line quality, it shows the lowest resistivity and sufficient results for low cost recyclable electronics, which do not require high conductivity. Nevertheless, the substrate was very thin and it could even be used in magazines as traditional lightweight coated papers (LWC) are used but with the additional of a printed electronic feature.

  • 90.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Green materials for inkjet printing of 2D materials and transparent electronics2018Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 91.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Liquid Exfoliation of Layered Materials in Water for Inkjet Printing2016Ingår i: Printing for Fabrication 2016: Materials, Applications, and Processes, USA: Curran Associates, Inc., 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    MoS2 is a layered material which is abundant and non-toxic and has been increasingly studied during the last few years as a semiconducting alternative to graphene. While most studies have been performed on single MoS2 nanosheets, for example to demonstrate high-performance electronic transistors, more work is needed to explore the use of MoS2 in printed electronics. The importance of using MoS2 as a printed electronic material could be understood by considering the several orders higher electron mobility in MoS2, even in several nanometer thick layers, compared to the organic and other materials used today. In the few studies performed so far on printing MoS2, the developed dispersions used mainly organic solvents that might be detrimental for the environment. Here, we show an environmentally friendly liquid-based exfoliation method in water where the solution was stabilized by sodium dodecyl sulfate (SDS) surfactant. The dispersions consisted of very thin MoS2 nanosheets with average lateral size of about 150 nm, surface tension of 28 mN m-1 and a shelf life of a year. Although both the concentration and viscosity was less than optimal, we were able to inkjet print the MoS2 solution on paper and on PET films, using multiple printing passes. By tuning the concentration/viscosity, this approach might lead to an environmentally friendly MoS2 ink suitable for printed electronics.

  • 92.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Liquid Exfoliation of Layered Materials in Water for Inkjet Printing2016Ingår i: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 60, nr 4, s. 1-7, artikel-id 040405Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    MoS2 is a layered material which is abundant and non-toxic and has been increasingly studied during the last few years as a semiconducting alternative to graphene. While most studies have been performed on single MoS2 nanosheets, for example to demonstrate high-performance electronic transistors, more work is needed to explore the use of MoS2 in printed electronics. The importance of using MoS2 as a printed electronic material could be understood by considering the several orders higher electron mobility in MoS2, even in several nanometer thick layers, compared to the organic and other materials used today. In the few studies performed so far on printing MoS2, the developed dispersions used mainly organic solvents that might be detrimental for the environment. Here, we show an environmentally friendly liquid-based exfoliation method in water where the solution was stabilized by sodium dodecyl sulfate (SDS) surfactant. The dispersions consisted of very thin MoS2 nanosheets with average lateral size of about 150 nm, surface tension of 28 mN m(-1), and a shelf life of a year. Although both the concentration and viscosity was less than optimal, we were able to inkjet print the MoS2 solution on paper and on PET films, using multiple printing passes. By tuning the concentration/viscosity, this approach might lead to an environmentally friendly MoS2 ink suitable for printed electronics.

  • 93.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Joakim, Bäckström
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andersson, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Exfoliated MoS2 in Water without Additives2016Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 4, artikel-id 0154522Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants andother funtionalization agents. Pure water should be an ideal solvent, however, it is generallybelieved, based on solubility theories that stable dispersions of water could not be achievedand systematic studies are lacking. Here we describe the use of water as a solvent and thestabilization process involved therein. We introduce an exfoliation method of molybdenumdisulfide (MoS2) in pure water at high concentration (i.e., 0.14±0.01 g L−1). This was achieved by thinning the bulk MoS2by mechanical exfoliation between sand papers and dis-persing it by liquid exfoliation through probe sonication in water. We observed thin MoS2nanosheets in water characterized by TEM, AFM and SEM images. The dimensions of thenanosheets were around 200 nm, the same range obtained in organic solvents. Electropho-retic mobility measurements indicated that electrical charges may be responsible for the sta-bilization of the dispersions. A probability decay equation was proposed to compare thestability of these dispersions with the ones reported in the literature. Water can be used as asolvent to disperse nanosheets and although the stability of the dispersions may not be ashigh as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable.

  • 94.
    Gradin, Per
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Berg, Jan-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Nyström, Staffan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Measuring Tangential Forces in a Pulp Refiner: A Novel Approach2016Ingår i: Experimental techniques (Westport, Conn.), ISSN 0732-8818, E-ISSN 1747-1567, Vol. 40, nr 2, s. 789-793Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To get some insight into the processes that are active during the refining of wood, the tangential force distribution in the plate gap is of interest. Over the years several designs of force sensors have been developed for this purpose. One drawback with these designs is that each sensormeasures forces over quite a small area such that in order to cover the whole disc with a reasonably good resolution, many sensors have to be used. Also, there are problems to protect the active parts of the sensors from the harsh environment in the plate gap. In this paper a different concept is presented, in that the sensor is continuous and consists of a hollow radial bar equipped with strain gages on the inside. The force sensor was calibrated before mounting by loading it with a known load in the tangential direction and in different positions while measuring the strains in the points where the gages are located. This makes it possible to determine the so-called influence (or Green) functions. Knowing these it is possible to determine the tangential force distribution from strain values measured during operation of the refiner. Guidelines for doing this are presented together with a detailed description of the load sensor and some experimental results.

  • 95.
    Große, Christine
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informationssystem och -teknologi.
    Olausson, Pär M.
    Mittuniversitetet, Fakulteten för humanvetenskap, Avdelningen för samhällsvetenskap.
    Danielsson, Erna
    Mittuniversitetet, Fakulteten för humanvetenskap, Avdelningen för samhällsvetenskap.
    Larsson, Aron
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informationssystem och -teknologi.
    Wallman Lundåsen, Susanne
    Mittuniversitetet, Fakulteten för humanvetenskap, Avdelningen för samhällsvetenskap.
    Björkqvist, Olof
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Nyhlén, Jon
    Mittuniversitetet, Fakulteten för humanvetenskap, Avdelningen för samhällsvetenskap.
    Collaboration and Decision-making in Response Planning for Power Shortages: The Swedish Policy2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Electricity is a key resource for the majority of societal functions and constitutes an important sector in the critical infrastructure of modern societies. Disturbances in power supply can have cascading effects on interdependent public sectors and ordinary citizens. However, it seems nearly impossible to completely prevent the occurrence of power shortages. Strategies to address temporary power losses are therefore essential. This paper aims to increase the understanding of national policies to manage the early consequences of power outages. Therefore, we critically review the Swedish national policy called Styrel as part of Swedish Crisis Management System. In the scientific literature, there are few examples similar to Styrel for handling emergencies in the electricity system. Particularly, we seek to discover related risks and benefits, conditions and constraints, as well as effects for specific stakeholders. We argue that the approach cannot yet be considered as fully developed. Three areas requiring improvement are identified. First, the scope and terms of the process must be specified. Second, (better) quality management seems necessary. Third, people responsible for identifying and prioritizing power consumers critical to local society need better decision aid. Improvements could facilitate risk-communication and collaboration among actors as well as decision-making and organisational learning.

  • 96.
    Gyldenstrand, Tom
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Fjärrvärme till tvättprocesser: En undersökning av möjligheten att ersätta en oljeångpanna med fjärrvärme och spetsenergi2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta arbete har utförts i uppdrag av Sundsvall Energi AB med syftet att undersöka möjligheterna för Berendsen Textilservice att utöka sin användning av fjärrvärme. Berendsen har ett tvätteri i Sundsvall och använder idag fjärrvärme för uppvärmning och tappvatten. Arbetet undersöker om det går att förse tvättmaskinerna med varmvatten uppvärmt av fjärrvärme, samt möjligheten att eftervärma luft till produktionslokalerna med fjärrvärme. Idag förses tvättmaskiner, ventilation och torktumlare med ånga från en oljeångpanna. Beslut har tagits för att konvertera torktumlarna till gasdrift. Denna undersökning skall fungera som beslutsunderlag för Berendsens eventuellt fortsatta satsning på fjärrvärme. Undersökningen ska svara på ifall fjärrvärme klarar av att förse tvättmaskinerna med tillräckligt varmt vatten och ifall det går att nå lönsamhet i ett sådant byte. Fjärrvärmen klarar av att förse tvättmaskinerna med minst 60°C vatten året runt. Detta innebär att majoriteten av tvättarna kan förses med tillräckligt varmt vatten direkt från fjärrvärme. 7 % av all tvätt kräver dock 75°C vatten. För att klara av 75°C tvättar och för att motverka temperaturfall under tvätt så rekommenderas en elångpanna för spetsenergi. Denna elångpanna är av mindre dimension än dagens oljeångpanna eftersom den bara förser tvättmaskiner med spetsånga och inte torktumlare eller ventilation. En del tvätt har problematik med äggviteämnen vilket innebär att fläckar fälls ut om ingående temperatur är för hög. Dessa tvättar förses med 37°C vatten och får därefter höjas succesivt med ånga från elångpannan. Fjärrvärmen klarar även av att förse ventilationsaggregatet med hetvatten. Dagens ångbatteri för eftervärmning av luften måste bytas till ett nytt anpassat för hetvatten. Eftersom aggregatet är av äldre modell och inte har någon värmeåtervinning rekommenderas ett nytt aggregat. Detta skulle leda till ett mindre värmebatteri för fjärrvärme, mindre värmeväxlare till hetvattenkretsen, ett lägre energibehov och mindre el till fläktarna. En investering i ett nytt aggregat är dock inte medräknat i denna rapport. Driftkostnaderna efter byte till fjärrvärme och elångpanna uppskattas bli ca 174 000 kr/år lägre än idag. Total investering för byte till fjärrvärme och elångpanna uppskattas grovt bli ca 1,3 miljoner. Detta ger en återbetalningstid på ca 7 år, vilket ses acceptabelt tack vare mervärden som minskade luftföroreningar och positiv publicitet. Minskade kostnader för underhåll och service är inte beaktade i denna undersökning. Med dessa medräknade skulle återbetalningstiden kunna bli ännu kortare. 

  • 97.
    Göransson, Kristina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Internal Tar/CH4 Reforming in Biomass Dual Fluidised Bed Gasifiers towards Fuel Synthesis2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Production of high-quality syngas from biomass gasification in a dual fluidised bed gasifier (DFBG) has made a significant progress in R&D and Technology demonstration. An S&M scale bio-automotive fuel plant close to the feedstock resources is preferable as biomass feedstock is widely sparse and has relatively low density, low heating value and high moisture content. This requires simple, reliable and cost-effective production of clean and good syngas. Indirect DFBGs, with steam as the gasification agent, produce a syngas of high content H2 and CO with 12-20 MJ/mn3 heating value. The Mid Sweden University (MIUN) gasifier, built for research on synthetic fuel production, is a dual fluidised bed gasifier. Reforming of tars and CH4 (except for methanation application) in the syngas is a major challenge for commercialization of biomass fluidised-bed gasification technology towards automotive fuel production. A good syngas from DFBGs can be obtained by optimised design and operation of the gasifier, by the use of active catalytic bed material and internal reforming. This thesis presents a series of experimental tests with different operation parameters, reforming of tar and CH4 with catalytic bed material and reforming of tar and CH4 with catalytic internal reformer.

     

    The first test was carried out to evaluate the optimal operation and performance of the MIUN gasifier. The test provides basic information for temperature control in the combustor and the gasifier by the bed material circulation rate.

     

     After proven operation and performance of the MIUN gasifier, an experimental study on in-bed material catalytic reforming of tar/CH4 is performed to evaluate the catalytic effects of the olivine and Fe-impregnated olivine (10%wtFe/olivine Catalyst) bed materials, with reference to non-catalytic silica sand operated in the mode of dual fluidised beds (DFB). A comparative experimental test is then carried out with the same operation condition and bed-materials but when the gasifier was operated in the mode of single bubbling fluidised bed (BFB). The behaviour of catalytic and non-catalytic bed materials differs when they are used in the DFB and the BFB. Fe/olivine and olivine in the BFB mode give lower tar and CH4 content together with higher H2+CO concentration, and higher H2/CO ratio, compared to DFB mode. It is hard to show a clear advantage of Fe/olivine over olivine regarding tar/CH4 catalytic reforming. 

     

    In order to significantly reduce the tar/CH4 contents, an internal reformer, referred to as the FreeRef reformer, is developed for in-situ catalytic reforming of tar and CH4 using Ni-catalyst in an environment of good gas-solids contact at high temperature.  A study on the internal reformer filled with and without Ni-catalytic pellets was carried out by evaluation of the syngas composition and tar/CH4 content. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H2 content together with lower CH4 and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases from 25 g/m3 down to 5 g/m3 and the CH4 content from 11% down below 6% in the syngas.

     

    The MIUN gasifier has a unique design suitable for in-bed tar/CH4 catalytic reforming and continuously internal regeneration of the reactive bed material. The novel design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas composition. 

     

  • 98.
    Göransson, Kristina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Söderlind, Ulf
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Zhang, Wennan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    An experimental study on catalytic bed materials in a biomass dual fluidised bed gasifier2015Ingår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 81, s. 251-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A study on in-bed material catalytic reforming of tar/CH4 has been performed in the 150 kW allothermal gasifier at Mid Sweden University (MIUN). The major challenge in biomass fluidised-bed gasification to produce high-quality syngas, is the reforming of tars and CH4. The MIUN gasifier has a unique design suitable for in-bed tar/CH4 catalytic reforming and continuously internal regeneration of the reactive bed material. This paper evaluates the catalytic effects of olivine and Fe-impregnated olivine (10%wtFe/olivine Catalyst) with reference to silica sand in the MIUN dual fluidised bed (DFB) gasifier. Furthermore, a comparative experimental test is carried out with the same operation condition and bed-materials when the gasifier is operated in the mode of single bubbling fluidised bed (BFB), in order to detect the internal regeneration of the catalytic bed materials in the DFB operation. The behaviour of catalytic and non-catalytic bed materials differs when they are used in the DFB and the BFB. Fe/olivine and olivine in the BFB mode give lower tar and CH4 content together with higher H-2 + CO concentration, and higher H-2/CO ratio, compared to DFB mode. It is hard to show a clear advantage of Fe/olivine over olivine regarding tar/CH4 catalytic reforming. (C) 2015 Elsevier Ltd. All rights reserved.

  • 99.
    Göransson, Kristina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Söderlind, Ulf
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Henschel, Till
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Zhang, Wennan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Internal tar/CH4 reforming in a biomass dual fluidised bed gasifier2014Ingår i: Proceeding of 4th International Symposium on Gasification and its Applications, 2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    An internal reformer is developed for in-situ catalytic reforming of tar and methane (CH4) in allothermal gasifiers. The study has been performed in the 150 kW dual fluidised bed (DFB) biomass gasifier at Mid Sweden University (MIUN). The MIUN gasifier is built for research on synthetic fuel production. Reduction of tars and CH4 (except for methanation application) in the syngas is a major challenge for commercialization of biomass fluidised-bed gasification technology towards automotive fuel production. The MIUN gasifier has a unique design with an internal reformer, where intensive contact of gas and catalytic solids improves the reforming reactions. This paper presents a study on the internal reformer operated with and without Ni-catalytic pellets, by evaluation of the syngas composition and tar/CH4 content. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H2 content together with lower CH4 and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases down to 5 g/m3 and the CH4 content down below 6% in the syngas. The novel design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas quality

  • 100.
    Göransson, Kristina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Söderlind, Ulf
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Henschel, Till
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Zhang, Wennan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Internal tar/CHreforming in a biomass dual fluidised bed gasifier.2015Ingår i: Biomass Conversion and Biorefinery, ISSN 2190-6815, Vol. 5, s. 355-366Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An internal reformer is developed for in situ catalyticreforming of tar and methane (CH4) in allothermal gasifiers.The study has been performed in the 150 kW dual fluidised bed (DFB) biomass gasifier at Mid Sweden University(MIUN). The MIUN gasifier is built for research onsynthetic fuel production. Reduction of tars and CH4 (exceptfor methanation application) in the syngas is a major challengefor commercialization of biomass fluidised-bed gasificationtechnology towards automotive fuel production. The MIUN gasifier has a unique design with an internal reformer, where intensive contact of gas and catalytic solids improves the reforming reactions. This paper presents an initial study on the internal reformer operated with and without Ni-catalytic pellets, by evaluation of the syngas composition and tar/CH4 content. A novel application of Ni-catalyst in DFB gasifiers is proposed and studied in this work. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H2 content together with lower CH4 and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases down to 5 g/m3 and the CH4 content down below 6 % in the syngas. The tar content can be decreased further to lower levels, with increased gas contact to the specific surface area of the catalyst and increased catalyst surface-to-volume ratio. The new design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas quality.

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