Vid TCF-blekning av pappersmassa är väteperoxid en av huvudkemikalierna. I dagsläget är det svårt att styra blekstegen. Operatörerna måste ta hänsyn till produktionstakt, blekbarheten på massan varierar och fördröjning i trender. PO-bleksteget på Södra Cell Värö har en ungefärlig uppehållstid på 4 timmar och det är först efter så lång tid som man kan se hur en förändring verkligen slår igenom. Överblekning kostar väldigt mycket i kemikalieåtgång och det är därför efterfrågat ett sätt att kunna styra och optimera peroxidblekningssteget. Ett delsteg för detta var att simulera steget experimentellt och från dessa data ta fram en matematisk modell som förutsäger ljusheten. Massa togs ut från fabriken och blektes på labb under kontrollerade förhållanden med satsningar liknande verkliga i fabriken. De parametrar som studerades på labb var temperatur, väteperoxidsats och alkalisats då de påverkar ljusheten mest. En modell för ljushetsökning anpassades sedan till framtagna blekdata. Ekvationer för förbrukning av väteperoxid och hydroxidjoner togs också fram från analyser på blekfiltraten. Med ingående parametrar som startkoncentrationer av kemikalier, temperatur och massakoncentration förutsäger modellen ljusheten väl vid verifiering jämfört med fabrik och verifieringsblekning på labb. Modellen ligger något högre jämfört med fabrik men det var förväntat då förhållanden på labb ger ett renare system. För de parametrar som studerats anpassade sig modellen bra till förändringar och vid verifiering på labb syntes att modellen även svarade med en korrekt ljushet vid förändring i massakoncentration och ingående ljushet i steget. / During TCF-bleaching of pulp, hydrogen peroxide is one of the main chemicals. Today it is difficult to control the bleaching stages. The process operators must consider the production rate, changes in the bleach ability of the pulp and delays of trends in the control system. The PO-bleaching stage at Södra Cell Värö has approximately a retention time of four(4) hours and it is first after that, a result of a change in the process can be seen. Overbleaching is expensive due to high chemical need and therefore it is requested to find a way to control and optimize the peroxide bleaching stage. One way to do this was too simulate the stage experimentally and from those kinetic data accomplish a mathematical model that predicts the brightness increase of the pulp. Pulp from the mill was bleached at the laboratory under controlled conditions and with charges similar to what are used in the plant. The parameters that were studied at lab were temperature, hydrogen peroxide charge and alkali charge as they affect the brightness mostly. A model for brightness increase was adjusted to the achieved bleaching data. Equations for consumption of hydrogen peroxide and hydroxide anions were also developed from analyses of the bleaching filtrates.  From the start parameters, as concentration of the chemicals, temperature and pulp concentration, the model predicts the brightness well according to verification of data from mill and verification bleaching at laboratory. The value from the model is somewhat higher compared to that of the plant but that was expected due to the fact that the conditions at lab give a cleaner system. For those parameters that were studied, the model did adjust well to changes made and according to the verification at lab it was seen that the model also worked for changes in pulp concentration and different brightness at the beginning of the stage.

The aim is to investigate models that predicts the potential of pulp and evaluate the relevance of the zero-span tensile index within these. Two chemical pulps made from softwood and eucalyptus were refined in a Voith-beater with different energy input in order to study the change of fiber morphology signals and other pulp and paper properties. Chemical, THP pulp from Södra Värö is also used as an initial analysis for morphological connections to Zero-span tensile index. The L&W Fiber Tester Plus is used in order to study the pulps fiber morphology and Pulmac 2000 for zero span. Handsheets are made for mechanical tests such as tensile properties, ZD-strength and optical properties. Many of the given signals change according to clear patterns with increasing refining energy. Using least square methods, formulas describing the development with high adaptation could be formulated. Many of the measured aspects changes over already known patterns. These are then applied in the models. Three possible models is tested: linear regression, Shear-Lag and Page. Of the three, only the two first ones where able to produce reliable models, whereas the third required data that was difficult to acquire at the same time as the adaptation was very low. The only model that use exclusively morphology data is linear regression.

The present study investigates the thermochemical conversion of spruce wood and its extracted components by thermogravimetric analysis. The extracted components are two pulps, three xylan-lignin samples and one lignin sample; they were produced by the kraft cooking method with different cooking times. The study involves characterization of the biomass through proximate analysis and pyrolysis. A qualitative comparison between the thermal behaviours of the extracted components and wood is also performed. The study showed that the thermal behaviour of the biomass was highly influenced by the content of cellulose and lignin in the samples. Compounds rich in cellulose produced large quantities of volatiles and had a higher rate of pyrolysis compared to compounds rich in lignin, which produced more char and had a slower rate of pyrolysis. It was also shown that, the amount of char is not solely depending on the amount of the lignin; the structure of the compound also plays a role. On the other hand, the original wood sample showed some deviations regarding the trends in volatile and char production and these deviations were attributed to component interactions. Both cellulose and lignin rich compounds had an increase in thermal stability with increasing cooking time. For the pulps the increase in thermal stability is believed to be caused by increase in crystallinity, while for the lignin rich samples is believed to be caused by the increase in lignin content and structural changes in the compounds. The results also show that although changes are introduced in the cooking process, the extracted component still retain properties exhibited by the source biomass.

The corrugated board is considered as the second most used packaging material and the world’s environmentally acceptable solution for packaging, with wide range of applications. After the manufacturing process, the corrugated board is cut into sheets and stored in a stack until optimum moisture content has been reached in order to avoid undesired properties. However, due to complex and various structures, it is difficult to estimate the appropriate time so to achieve the acceptable moisture level of the corrugated board stack. So a homogenized model of the stack has to be created which will have the same average properties as the real stack. In order to achieve this goal the behavior of a smaller part of the stack, the unit cell, is investigated. In the second step a homogenized model is created with the average transport of mass and heat. At the end, the unit cell is scaled up. In this master thesis, only the first and the second steps were simulated. This was achieved by creating a 3-D mathematical model using finite element method and simulating its properties in COMSOL Multiphysics®. Four mathematical models were used in the description of the 3-D model: the heat transfer, the moisture transfer, the vapour concentration and the gas pressure. Moreover, by applying the gradient in one direction in each case, the behavior of the detailed unit cell was investigated. Finally different simplified geometries were created and investigated so to approach a homogenized model which described better the average properties of the detailed model. By comparing the results of the models, it was concluded that the homogenized models 2 and 3 approached the values of the second detailed model but only inside of the unit cell. However, the deviation was not negligible and further investigation is required in order to find a new homogenized method.

Abstract Purpose Changing processes and an organization quickly and successfully is a challenging task. Thus, standardization of the process of making changes as well can be useful to reach the goal of increased performance. Many different aspects can be considered when investigating the critical factors that lead to a successful change. Assessing whether these critical factors can be utilized to formulate standards is, therefore, an interesting topic to delve deeper into. Thus, the purpose is “Explore how change management processes in the pulp and paper industry can be standardized, and how the change management process can be improved.” and the research questions (RQ):  RQ1. What are the critical factors of the change management processes in the pulp and paper industry?  RQ2. How can standardization of change management processes be achieved in the pulp and paper industry? Method This is a qualitative study where information has been gathered through a literature review and a multiple case study. The empirical data was primary data gathered through interviews. Theoretical information was gathered based on keywords selected through brainstorming sessions and found in articles. A data analysis model was used when analysing the empirical data.  Findings Six critical factors were found as an answer to RQ1. These six critical factors for pulp and paper industries were found within broader studies on change management factors as well. Standardization of change management processes on a general level was deemed possible. However, when investigating detailed levels of change management processes there are indications that it is possible to some degree, but it is more difficult to transfer a standardized process between different types of changes. Future Research More research can be beneficial in change management on more detailed levels and how standards can be transferred between types of change, and if this is only applicable to pulp and paper industries or to 24-hour continuous production processes. The conceptual maturity model presented in this report could be explored further and has the potential to be modified further to fit the needs of different organizations and industries. The conceptual guideline that was presented in the report needs to be tested and verified. Limitations This project has excluded international factories from its studied area. This project also scopes in toward the pulp and paper industry as its focus and did not analyse if its result is applicable to other industries or not. Additionally, this project did not verify if the implementation of the resulting guidelines yields a positive or negative outcome, further study is required.

One of the major cost factors in mechanical pulp production is the electrical energy input. Much of the research in this field has therefore been devoted to an understanding of the mechanisms in the refining process and, consequently, to find ways of reducing the electrical energy consumption. Shear and compression are probably the main types of fibre deformation occurring in refiners for collapsing and fibrillating the fibres into a suitable pulp. In current refiners, the repeated mechanical action of the bars on the fibres consumes large amounts of energy in a treatment of mechanical fibres that is almost random. Fundamental studies of the deformation of wood have indicated that a combination of shearing and compression forces is highly beneficial in terms of fibre deformation with a low energy demand. Pure compression is able to permanently deform the fibre but requires a substantial amount of work, while pure shearing, although being much less energy demanding, does not lead to any permanent deformations. A more suitable application of the shear and compression forces on the wood fibres during the refining process could be a way to develop fibres at a lower energy demand. These ideas have been studied in this work trying to find new ways of saving energy in the mechanical pulping process. The first paper in this thesis discusses the way of producing wood shavings and the introduction of shear/compression deformations in these, as well as the potential benefits of using them instead of wood chips as raw material for TMP production. With the shaving process, high deformations in the wood cells were achieved by the shear and compression forces. This led to energy savings of about 25% at a given tensile index, when compared to traditional chips. The quality of the pulp produced from wood shavings was found to be better than that of the pulp produced from wood chips, when it came to strength properties (except for tear index) and optical properties at comparable energy levels. Another way of reducing energy consumption in refining involving a limited shear combined with compression forces for the mechanical treatment of both wood chips and coarse fibres was also studied. This work shows that such a kind of treatment resulted in a high degree of fibre collapse at low energy demands. The thick-walled transition fibres could even be permanently deformed. Furthermore, refining trials, utilising shear and compression pre-treated chips, showed that the strength properties, except for tear index, along with the optical properties of a TMP could be improved and the electrical energy consumed could be reduced by approx. 100 kWh/tonne, when compared to untreated chips. The results from the pilot trials described in this work could be used as a starting point for further implementation in the industry, in order to identify the most efficient way of producing mechanical pulp with a lower consumption of electrical energy. / QC 20101119

Due to environmental concerns and to the limited amount of fossil fuel in the world theinterest in using renewable material has been and will continue to be on the rise. With theincreasing demand for renewable materials such as bio-based fibers, the research aroundnatural fibers is intensifying. Abaca (Musa Texitilis Nee) is a plant endemic to the Philippineswhich is claimed to contain the strongest natural fiber in the world 1. However, no thoroughresearch on performing tensile strength test on single abaca fibers/cells has been found. Byperforming tensile strength test on the single abaca fibers and relate this will provide freshdata about the single abaca fiber strength that can be compared with other natural fibers.This can later be a reference tool in order to find the optimal fiber for the product to be made. The purpose of this study is to develop a methodology for performing tensile strength testson single abaca fibers with the major objective to relate the tensile strength and E-modulusof the fibers with their microfibrillar angle (MFA). The research was done by using Abaca(grade S2) from Camarines Sur (Philippines) that was chemically disintegrated in order toobtain single fibers. The single fibers were mounted to a custom made paper frame for thetensile strength test performed by an Instron 5944. The MFA of each fiber was also retrievedusing an optical microscope with a polarized filter. The research showed an indication of aninversely proportional relation between MFA and tensile strength of the fibers. According tothe results, the E-modulus of the single abaca fiber was almost constant, independently onthe MFA of the fiber. / The purpose of this study is to do a broad map out of the abaca industry in the Philippines. Furthermore, the study aims to provide an overview of the abaca industry as a tool for finding ways to optimize the fiber production and to find suggestions on how to make a bigger share of the profit from the abaca products to stay by the farmers in the Philippines. The objectives are therefore also focused on describing the way the abaca plant is cultivated, harvested, processed, and further distributed from the farms. Also, the objectives are to describe the abaca supply and demand situation along with identifying challenges for abaca production. Today the outmoded abaca production in the Philippines is experiencing a productivity loss which makes the farmers' incomes unnecessarily low. Important factors that, by this study, have been identified affecting the low productivity and profit are lack of proper farming management, distribution and unoptimized usage of the fibers. A big share of the abaca fibers produced is also being exported. This means that the raw fibers are being made into high-value products abroad and hence the profit to be made is dislocated further from the farmers with low means of improving their standard of living. The study has been performed by doing a literature study complemented with interviews and visits to abaca farmers and other stakeholders within the abaca industry.

Syftet med denna studie är att undersöka inverkan av förbehandlingar på ljushetsstabiliteten av Northern Bleached Softwood Kraft (NBSK) som har blekts enligt (OO) (OP) D/Dn (PO) bleksekvensen. Effekten av förbehandling med xylanas (X), mild sur (A), DTPA (Q) samt ett kombinerad DTPA- & xylanassteg (Q+X) har studerats.  Resultaten indikerar att Q+X förbehandlingen var mest effektiv i minskningen av skadliga metalljoner i massan. Den Q+X förbehandlade massan hade dessutom lägst kappa och högst ljushetsvärde bland förbehandlingarna. Kemisk sammansättningsanalys av de förbehandlade massorna visar vidare att den Q+X förbehandlingen ledde till den högsta minskningen av såväl xylan som lignin. Det milda A förbehandlingen var inte effektivt för att avlägsna alla viktiga skadliga metalljoner och visade ingen effekt på reduktionen av xylan eller lignin. Den X behandlade massan visade ingen förmåga att ta bort metaller och är därför ofördelaktigt.  Q och Q+X förbehandlade massaströmmar har blekts vidare för att studera effekterna av dessa förbehandlingar på den slutliga massakvaliteten samt för att jämföra ett konventionellt klordioxidsteg (D) och en nästan neutral pH klordioxidsteg (Dn). Resultaten bekräftar att Dn-steget ledder till en reducerad grad av AOX.  Ljusheten direkt efter klordioxidsteget är vidare högre för de Dn-behandlade massorna, men processen är begränsad med avseende på ljushetsstabilitet, vilket är en viktig nackdel.  Q+X (OP) D (PO) blekningssekvensen visade den högsta ljushetsstabilitet, medan den Q+X (OP) Dn (PO) blekningssekvensen visade ingen förbättring jämfört med Q (OP) Dn (OP) blekningssekvensen. Slutsatsen är att den enzymatisk medförda kvalitetsförbättringen inte räcker för att kompensera för bristerna i ett Dn-steg. / This is a study on Northern Bleached Softwood Kraft (NBSK) and the (OO) (OP) D/Dn (PO) bleaching sequence. The effects of a xylanase (X), mild acidic (A), DTPA (Q), and a combined DTPA & xylanase (Q+X) pre-treatments have been studied. The results indicate that the Q+X pre-treatment most effectively reduced the presence of harmful metal ions in the pulp. The Q+X pre-treated pulp furthermore yielded the lowest kappa number and highest brightness values among the pre-treatments tested. Chemical analysis of this pulp also shows the highest reduction in xylans and lignin. The mild A stage was ineffective in removing all harmful metal ions and showed no effect on the reduction of xylans or lignin. The X stage cannot meanwhile remove metals and is thus disadvantageous. Subsequently, the Q+X pre-treated pulp as well as a Q-treated pulp stream were further bleached to study the effects of these pre-treatments on the final pulp quality as well as to compare these streams of pulp bleached using a conventional chlorine dioxide stage (D) and a near neutral pH chlorine dioxide (Dn) stage. The results confirmed that the Dn stage causes a reduced degree of AOX in the effluent. Furthermore, the brightness directly after the chlorine dioxide stage is higher for the Dn-treated pulps but the process is limited in brightness stability which is a significant drawback. The Q+X (OP) D (PO) bleaching sequence showed the highest brightness stability while the Q+X (OP) Dn (PO) bleaching sequence displayed no improvement over the Q (OP) Dn (OP) bleaching sequence. The conclusion can be made that the enzymatic boost in bleaching is not enough to compensate for the shortcomings of a Dn stage.

Munksunds pappersbruk är ett integrerat massa- och pappersbruk som består av två fiberlinjer, en barr- och en lövlinje där båda kokarna är kontinuerliga med efterföljande tvättsteg. En kartering av COD (eng. Chemical Oxygen Demand) och natrium utfördes för båda linjerna för att utvärdera tvätteffektiviteten. COD anger hur mycket syre som krävs för att bryta ned det kvarvarande organiska materialet och natrium används som en indikator på tvättförlusten av kokkemikalierna. Karteringen utfördes genom att analysera in- och utgående flöden vid varje tvättsteg, exklusive kokarna. En förenklad metod användes, där tre flöden analyserades och den fjärde beräknades genom flödes- och massbalanser. Modellen som användes för att beskriva tvätteffektiviteten för respektive utrustning var tvättutbytet Y, som erhölls genom en massbalans. Studien visade att halten COD och Natrium minskar mest från början för respektive linje och når ett gränsvärde runt 8,2 kg COD/adt och 6,6 kg Na/adt för barrlinjen, respektive 8,5 kg COD/adt och 4,8 kg Na/adt för lövlinjen, där ytterligare substans inte kan tvättas bort. Båda linjerna tvättar likvärt med avseende på COD, men lövlinjen tvättar bättre med avseende på natrium. I det sista tvättsteget hade båda fiberlinjerna eliminerat 98% av den inkommande COD-mängden med massan från kokarna. Vidare hade barrlinjen eliminerat 86% och lövlinjen 93% med avseende på natrium i det sista tvättsteget. Utvärderingen av de olika tvättutrustningarna visade att DD-filtret i lövlinjen var effektivast både med avseende på COD och natrium, följt av PO-pressen. På barrlinjen var filter 1 mest effektivt med avseende på COD och natrium. / A mapping of COD (Chemical oxygen demand) and sodium will be done to evaluate the different washing steps. COD describe the amount of oxygen needed to dissolve the organic matter left in the pulp and sodium is used as an indicator of the washing loss of the cooking chemicals. The in- and outgoing streams of the washing steps was analyzed to examine the efficiency. A simplified method was applied where three streams were analyzed and the fourth was calculated through flow-and mass balances. The model used to describe the wash efficiency in this study was the wash yield, which can be obtained by mass balances. The study showed that the content of COD and sodium decreased most in the beginning and reaches a limit value of 8,2 kg COD/adt and 6,6 kg Na/adt in the softwood pulp line and 8,5 kg COD/adt and 4,8 kg Na/adt in the soft wood pulp line, where no more content could be removed. Both pulp lines washed efficient with aspect of COD, but the hardwood pulp line washed more efficient in the aspect of natrium compared to the softwood pulp line. In the last washing step, both pulp lines had removed 98% of the ingoing COD from the digester. With aspect to natrium the softwood pulp line had removed 86% and the hardwood pulp line 93% in the last washing step. The evaluation of the different washing equipment showed that the DD-filter in the hardwood pulp line was the most efficient with aspect of both COD and Sodium, followed by the PO-press. In the softwood pulp line, filter 2 was the most efficient regarding both COD and Sodium. The flow- and mass balances turned out to be complicated at some of the washing steps, especially around the Q1-press in the hardwood pulp line and press 1-3 and filter 2 in the softwood pulp line. The reason for this could be that different functional chemicals are added before the Q1-press, which was not considered in this study, additional causes could be unidentified flows that affect the balances. The study was limited to only analyze three streams and calculate the fourth, an analyze of all the streams would give a more accurate result. However, the study provides a good overview of the wash efficiency in the pulp mill.

Paper is used in a wide range of applications, each of which has specific requirements on mechanical and surface properties. The role of paper strength on paper performance is still not well understood. This work addresses the mechanical properties of paper by utilizing fiber network simulation and consists of two parts.In the first part, we use a three-dimensional model of a network of fibers to describe the fracture process of paper accounting for nonlinearities at the fiber level (material model and geometry) and bond failures. A stress-strain curve of paper in tensile loading is described with the help of the network of dry fibers; the parameters that dominate the shape of this curve are discussed. The evolution of network damage is simulated, the results of which are compared with digital speckle photography experiments on laboratory sheets. It is concluded that the original strain inhomogeneities due to the structure are transferred to the local bond failure dynamics. The effects of different conventional and unconventional bond parameters are analyzed. It has been shown that the number of bonds in paper is important and that the changes in bond strength influence paper mechanical properties significantly.In the second part, we proposed a constitutive model for a fiber suitable for cyclic loading applications. We based the development of the available literature data and on the detailed finite-element model of pulp fibers. The model provided insights into the effects of various parameters on the mechanical response of the pulp fibers. The study showed that the change in the microfibril orientation upon axial straining is mainly a geometrical effect and is independent of material properties of the fiber as long as the deformations are elastic. Plastic strains accelerate the change in microfibril orientation. The results also showed that the elastic modulus of the fiber has a non-linear dependency on a microfibril angle,with elastic modulus being more sensitive to the change of microfibril angle around small initial values of microfibril angles. These effects were incorporated into a non-linear isotropic hardening plasticity model for beams and tested in a fiber network in cycling loading application model, using the model we estimated the level of strains that fiber segments accumulate at the failure point in a fiber network.The main goal of this work is to create a tool that would act as a bridge between microscopic characterization of fiber and fiber bonds and the mechanical properties that are important in the papermaking industry. The results of this work provide a fundamental insight on mechanics of paper constituents in tensile as well as cyclic loading. This would eventually lead to a rational choice of raw materials in paper manufacturing and thus utilizing the environment in a balanced way. / <p>QC 20130605</p>