De 20 största massabruken i Sverige släpper tillsammans ut ungefär 20 miljoner ton CO2 per år. Dessa utsläpp har biogent ursprung och anses därför vara klimatneutrala. Massa- och pappersindustrin är därmed en lämplig kandidat för implementeringen av BECCS (eng. Bioenergy with Carbon Capture and Storage) och har en betydande potential att nå de, av den svenska regeringen, uppsatta klimatmålen som säger att Sverige inte ska några nettoutsläpp av växthusgaser till atmosfären senast år 2045. I detta examensarbete simulerades kemiska absorptions- och desorptionsprocesser med MEA som lösningsmedel genom att tillämpa den hastighetsbaserade metoden i en rigorös modell i Aspen Plus. Stripper- och absorptionsmodellerna validerades innan standardprocessen modifierades till en konfiguration som möjliggör värmeintegration av koldioxidinfångningens överskottsvärme med, exempelvis, ett sulfatmassabruk. Avskiljningsgraden och laddning hos den mättade lösningen användes som prestandaindikatorer för att validera absorptionskolonnerna. Återkokarens energiåtgång och laddning hos den omättade lösningen användes somprestandaindikatorer för att validera stripperkolonnerna. Samtliga kolonner dimensionerades för att erhålla 90 vikt% avskiljningsgrad. Olika flödeshastigheter av lösningsmedlet testades för att säkerställa effektivt nyttjande av packningen i absorptions- och stripperkolonnerna. Lämpliga temperaturnivåer för värmeintegration, inom och utanför, koldioxidinfångningen erhölls genom att utvärdera olika varianter av en stripper-overhead-kompression konfiguration. Utvärderingen av den modifierade MEA processen tog hänsyn till potentialen för ångbesparing och energieffektivisering. Resultat från simuleringarna tyder på att den modifierade strippern skulle kunna ge besparingar på upp emot 11 % i ånganvändning. Energibesparingar i samma storleksordning kunde även erhållas genom värmeintegration mellan koldioxidinfångningen och en särskild process i ett referensbruk. Implementering av BECCS-konceptet på det här sättet skulle därmed kunna bli ett mer attraktivt alternativ för den svenska massa- och pappersindustrin att bekämpa klimatförändringarna. / The 20 largest pulp mills in Sweden emit around 20 million tonnes of CO2 per year. These emissions are considered carbon-neutral since they originate from biogenic sources. The pulp and paper industry is therefore a good candidate for the application of BECCS (Bioenergy with Carbon Capture and Storage) and has the potential to play a significant role for reaching the long-term mitigation target set by the Swedish government that Sweden should be climate-neutral by year 2045. In this thesis, a MEA-based chemical absorption and desorption process was rigorously modelled in Aspen Plus using the rate-based method. Validation of the absorber and stripper model was conducted before the standard process was modified to a configuration that enables heat integration of a significant amount of excess heat from the capture process in, for example, a Kraft pulp mill. CO2 removal rate and rich solvent loading were used as performance indicators to validate the absorber columns. The reboiler duty and lean solvent loading served as performance indicators in the stripper validation. The columns were dimensioned considering 90 wt% capture rate. Efficient use of the entire packing in the absorber and stripper columns was ensured by testing different solvent flow rates. Suitable temperature levels for heat integration, within and across the capture plant, were obtained through an assessment of different versions of a stripper overhead compression configuration. The evaluation of the modified MEA processes took into account the steam conservation potential and energy efficiency potential. The simulation results indicate that the modified stripper may lead to savings of up to 11% in steam consumption. Heat integration between the capture plant and a specific process in a reference Kraft pulp mill resulted in energy savings of the same order of magnitude. Thereby, making the BECCS concept a more attractive solution for the Swedish pulp and paper industry to mitigate climate change.

There is growing demand for a more efficient use of polymers that originate from renewable feedstocks due to the depleting supply of fossil fuels, based on economic and environmental reasons. As a result, lignin has attracted renewed interest as a resource for various bioproducts. Lignin is a natural biopolymer with a high carbon content and is composed of aromatic moieties, with a high level of polar functionalities. This makes it a unique precursor for certain high-value applications, such as in biofuels, bioplastics, composite materials, carbon fibers and activated carbons and as a source of phenolic monomers and fine chemicals. Industrial lignins are formed as byproducts of pulping processes (such as kraft, sulfite or alkaline pulping) or result from the biorefining process, where carbohydrates are used for sugar production. Lignin’s intrinsic structure is significantly modified during the processing of lignocellulose, resulting in the formation of more diverse, condensed and less reactive raw materials. Since molecular mass and polydispersity are the most important parameters affecting the chemical reactivity and thermal properties of lignin, additional process steps to improve the quality of crude technical lignins, including kraft lignin, are needed. Solvent extraction is a potentially useful technique for further improving the polydispersity of technical lignins. This work summarizes the impact of solvent fractionation on the chemical structure, antioxidant activity, heating value, and thermal and sorption properties of industrial hardwood and softwood kraft lignins. The purpose was to understand the correlation between certain structural features in the lignin fractions and their properties to select the appropriate solvent combinations for specific applications of lignin raw materials. Four common industrial solvents, namely, ethyl acetate, ethanol, methanol and acetone, in various combinations were used to separate both spruce and eucalyptus kraft lignins into fractions with lower polydispersities. Gel-permeation chromatography analysis was used to evaluate the efficiency of the chosen solvent combination for lignin fractionation. The composition and structure of the lignin material were characterized by elemental analysis, analytical pyrolysis (Py-GC/MS/FID) and 31P NMR spectroscopy. The thermal properties of the lignin samples were studied by thermogravimetric analysis. Proximate analysis data (ash, volatile components, organic matter and fixed carbon) were obtained through the direct measurement of weight changes during the analysis, while the high heating values (in MJ/kg) were calculated according to equations suggested in the literature. The sorption properties of fractionated kraft lignins were studied with respect to methylene blue dye. Additionally, lignin fractions with different molecular weights (and therefore various chemical structures) that were isolated from both softwood and hardwood kraft lignins were incorporated into a tunicate cellulose nanofiber (CNF)-starch mixture to prepare 100% bio-based composite films. The aim was to investigate the correlation between lignin diversity and film performance. The transmittance, density and thermal properties of the films were investigated, as were their mechanical properties, including the tensile stress and Young’s modulus. This part of the study addressed the importance of lignin diversity on composite film performance, which could be helpful for tailoring lignin applications in bio-based composite materials based on the material’s specific requirements.

It is in the nature of the human species to find solutions of complex technical problems and always strive for improvements. The development of new materials is not an exception. One of the many man-made materials is carbon fibre (CF). Its excellent mechanical properties and low density have made it attractive as the reinforcing agent in lightweight composites. However, the high price of CF originating from expensive production is currently limiting CF from wider utilisation, e.g. in the automotive sector.   The dominating raw material used in CF production is petroleum-based polyacrylonitrile (PAN). The usage of fossil-based precursors and the high price of CF explain the strong driving force of finding cheaper and renewable alternatives. Lignin and cellulose are renewable macromolecules available in high quantities. The high carbon content of lignin is an excellent property, while its structural heterogeneity yields in CF with poor mechanical properties. In contrast, cellulose has a beneficial molecular orientation, while its low carbon content gives a low processing yield and thus elevates processing costs.   This work shows that several challenges associated with CF processing of each macromolecule can be mastered by co-processing. Dry-jet wet spun precursor fibres (PFs) made of blends of softwood kraft lignin and kraft pulps were converted into CF. The corresponding CFs demonstrated significant improvement in processing yield with negligible loss in mechanical properties relative to cellulose-derived CFs. Unfractionated softwood kraft lignin and paper grade kraft pulp performed as good as more expensive retentate lignins and dissolving grade kraft pulp, which is beneficial from an economic point of view.   The stabilisation stage is considered the most time-consuming step in CF manufacturing. Here it was shown that the PFs could be oxidatively stabilised in less than 2 h or instantly carbonised without any fibre fusion, suggesting a time-efficient processing route. It was demonstrated that PF impregnation with ammonium dihydrogen phosphate significantly improves the yield but at the expense of mechanical properties.   A reduction in fibre diameter was beneficial for the mechanical properties of the CFs made from unfractionated softwood kraft lignin and paper grade kraft pulp. Short oxidative stabilisation (&lt;2 h) of thin PFs ultimately provided CFs with tensile modulus and strength of 76 GPa and 1070 MPa, respectively. Considering the high yield (39 wt%), short stabilisation time and promising mechanical properties, the concept of preparing CF from lignin:cellulose blends is a very promising route. / Det ligger i människans natur att hitta lösningar på komplexa tekniska problem, samt att alltid sträva efter förbättringar. Utvecklingen av nya material är inget undantag. Ett av flera material utvecklade av människan är kolfiber. Dess utmärkta mekaniska egenskaper samt låga densitet har gjort det attraktivt som förstärkningsmaterial i lättviktskompositer. Det höga priset på kolfiber, vilket härstammar ur en kostsam framställningsprocess, har förhindrat en mer utbredd användning i exempelvis bilindustrin.   Det dominerande råmaterialet för kolfiberframställning är petroleumbaserad polyacrylonitril (PAN). Användandet av fossila råvaror och det höga priset på kolfiber förklarar den starka drivkraften att hitta billigare och förnyelsebara alternativ. Lignin och cellulosa är förnyelsebara makromolekyler som finns tillgängliga i stora kvantiteter. Det höga kolinnehållet i lignin gör det mycket attraktivt som råvara för kolfiberframställning, men dess heterogena struktur ger en kolfiber med otillräckliga mekaniska egenskaper. Däremot har cellulosa en molekylär orientering som är önskvärd vid framställning av kolfiber, men dess låga kolinehåll ger ett lågt processutbyte som i sin tur bidrar till höga produktionskostnader.             Det här arbetet visar att många av de problem som uppstår med kolfiber från respektive råvara kan kringgås genom att utgå från blandningar av desamma. Prekursorfibrer från blandningar av kraftlignin och kraftmassa från barrved tillverkade med luftgapsspinning konverterades till kolfiber. Utbytet för kolfibrerna som framställdes var mycket högre än vid framställning från endast cellulosa. Ofraktionerat barrvedslignin och kraftmassa av papperskvalitet presterade lika bra som de dyrare retentatligninen och dissolvingmassan, vilket är fördelaktigt ur ett ekonomiskt perspektiv.   Stabilisering är det mest tidskrävande processteget i kolfibertillverkning. I det här arbetet visades det att prekursorfibrerna kunde stabiliseras på kortare än två timmar, eller direktkarboniseras utan någon sammansmältning av fibrerna. Detta indikerar att en tidseffektiv produktion kan vara möjligt. Impregnering av prekursorfibrerna med ammoniumdivätefosfat ökade utbytet avsevärt, men med lägre mekaniska egenskaper som bieffekt.           Kolfibrernas mekaniska egenskaper ökade vid en diameterreduktion. En kort oxidativ stabilisering under två timmar i kombination med tunna prekursorfibrer gav kolfiber med en elasticitetsmodul på 76 GPa och dragstyrka på 1070 MPa. Att göra kolfiber från blandningar av lignin och cellulosa är ett lovande koncept om det höga utbytet (39%), den korta stabiliseringstiden samt de lovande mekaniska egenskaperna tas i beaktande. / <p>QC 20190226</p>

The aim of this thesis is to explore how theoretical studies on handicrafts may be rewarding and usefull for a craftsman. The aim is also to explore how quality is defined within crafts and to explore different aesthetic qualities that can be achieved within the craft of cabinetmaking. In addition, the aim is also to broaden the view on how skillfullnes may be expressed within the craft of cabinetmaking. The work begins with theoretical studies of two craft philosophers - David Pye and Soetsu Yanagi. Then, their ideas are applied practically through the making of two pieces of furniture. Aesthetic expressions characterized by randomness, imperfection and irregularity is specially sought after. The conclusions of the thesis shows that theoretical studies may be benefiting and rewarding for a craftsman. / Syftet med detta arbete är att visa hur teoretiska studier om hantverk är utvecklande och användbara för en praktiserande hantverkare. Syftet är också att undersöka vad som definierar gott hantverk samt att undersöka vilka olika estetiska kvalitéer som kan åstadkommas inom snickerihantverket. Dessutom vill arbetet bredda synen på hur skicklighet och förståelse för materialet trä kan uttryckas. Arbetet inleds med teoretiska studier av två hantverksfilosofer - David Pye och Soetsu Yanagi. Därefter tillämpas deras idéer praktiskt genom tillverkningen av två möbler. Särskilt fokus läggs på att åstadkomma estetiska uttryck som präglas av slump, imperfektion och irregularitet. Slutsatserna visar att ett teoretiska studier kan bredda en praktiserande hantverkares syn på vad som är möjligt att åstadkomma inom snickerihantverket samt att materialet trä tillåter en bredd av uttryck.

Food packaging should ensure the safety and quality of food, minimize spoilage and provide an easy way of storing and handling it. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. Using both experimental data and computer modelling, this thesis explains some aspects of how the structure of barrier coatings influences the mass transport of oxygen with the aim of obtaining essential knowledge that can be used to optimize the performance of barriers. Barrier coatings are produced from polyvinyl alcohol and kaolin blends that are coated onto a polymeric support. The chemical and physical structures of these barriers were characterized according to their influence on permeability in various climates. At a low concentration of kaolin, the crystallinity of polyvinyl alcohol decreased; in the thinner films, the kaolin particles were orientated in the basal plane of the barrier coating. The experimental results indicated a complex interplay between the polymer and the filler with respect to permeability. A computer model for permeability incorporating theories for the filled polymeric layer to include the polymer crystallinity, addition of filler, filler aspect ratio and surrounding moisture was developed. The model shows that mass transport was affected by the aspect ratio of the clay in combination with the clay concentration, as well as the polymer crystallinity. The combined model agreed with the experiments, showing that it is possible to combine different theories into one model that can be used to predict the mass transport. Four barrier coatings: polyethylene, ethylene vinyl alcohol + kaolin, latex + kaolin and starch were evaluated using the parameters of greenhouse gas emissions and product costs. After the production of the barrier material, the coating process and the end-of-life handling scenarios were analysed, it emerged that starch had the lowest environmental impact and latex + kaolin had the highest. / Food packaging is required to secure the safety and quality of food, as well as minimize spoilage and simplify handling. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. This thesis focuses on the mass transport of oxygen in order to gain deeper knowledge of, and thereby optimise, the performance of barrier coatings. This experimental study, together with computer modelling, characterized the structure of barrier materials with respect to the mass transport process. The performance of the barriers was evaluated based on the parameters of environmental impact and product costs. As the long-term aim is to use non-petroleum-based barrier coatings for packaging, these should be evaluated by assessing the properties of the material in question, its functionality and its environmental impact to provide more insight into which materials are desirable as well as to develop technology. The results from this study indicate that several parameters (the orientation, concentration and aspect ratio of the clay and the polymer crystallinity) influence the properties of a barrier. Using this knowledge, researchers and food packaging engineers can work toward improving and customising renewable barriers. / VIPP

Converting wood into paper is a complex process involving many different stages, one of which is pulping. Pulping involves liberating the wood fibres from each other, which can be done either chemically or mechanically. This thesis focuses on the most common chemical pulping method, the kraft cooking process, and especially on a recently developed improvement of the impregnation phase, which is the first part of a kraft cook. Extended impregnation kraft cooking (EIC) technique is demonstrated to be an improvement of the kraft pulping process and provides a way to utilize softwood to a higher degree, at higher pulp yield. We demonstrate that it is possible to produce softwood (Picea abies) kraft pulp using a new cooking technique, resulting in a pulp that can be defibrated without inline refining at as high lignin content as 8% on wood, measured as kappa numbers above 90. Lignin is the wood constituent that holds the wood fibres together in the wood matrix. The new cooking technique uses the differences in reaction rate between the diffusion and consumption of hydroxide ions; it is used to ensure a homogenous impregnation of wood chips at lower impregnation temperatures and longer impregnation times than are generally used in the industry. The applied cooking temperatures are also substantially lower than those used in conventional kraft pulping systems, promoting uniform delignification. This results in a narrower kappa number distribution than in lab-cooked conventional kraft pulp. High-kappa-number pulps were investigated for pulp sheet properties such as tensile strength, tensile stiffness, and compression strength. It was demonstrated that an EIC pulp of kappa number 95 has strength properties comparable to those of a conventional pulp of kappa number 82. Comparing the effects of starch multilayers on conventional and EIC pulps reveals similar effects. The use of the starch multilayer treatment increased the tensile index and decreased the tensile stiffness and short-span compression test (SCT) indices. The EIC technique has also been used to produce a series of bleachable-grade pulps. The results indicate the possibility of increasing the lignin content of the pulp entering the oxygen delignification stage, since the reject content of gently defibered pulp is lower than 0.1% at kappa number 49. In this thesis, we recommend that wood chips be impregnated for 2 h at 110 °C to neutralize acidic compounds in the wood and impregnate the chips with cooking chemicals, and that the ensuing cook be performed at 135–140 °C, depending on the target kappa number. We also recommend increasing the available amounts of cooking chemicals in the impregnation stage by using a higher liquor-to-wood ratio and keeping the alkali profile fairly high in the ensuing cook. This concept will reduce the amount of reject material, increase the pulping uniformity, and increase the selectivity towards lignin degradation in the kraft cook. / Omvandling av ved till papper är en komplicerad process som består av många olika steg där ett är massaframställningen (eng. pulping). Massaframställning medför att vedfibrerna frigörs från varandra på kemisk eller mekanisk väg. Denna avhandling fokuserar på den vanligaste kemiska metoden, sulfatkokning och speciellt den nyligen utvecklade förbättringen av impregnerings fasen, som är den första delen av ett sulfatkok. Här visas att Extended Impregnation kraft Cooking (EIC) innebär en förbättring av sulfatkokningen och ett sätt att uppnå högre vedutnyttjande vid högre utbyte för barrved. Vi visar att det är möjligt att producera barrvedsmassa med en ny kokningsprincip som resulterar i en massa som är defibrerbar utan inline-raffinering vid så högt lignin innehåll som 8% (på ved), mätt som kappatal över 90. Lignin är den vedkomponent som håller ihop vedfibrerna i vedmatrisen. Kokningsprincipen utnyttjar skillnaderna i reaktionshastighet mellan diffusion och konsumtion av hydroxidjoner och nyttjas till att skapa en homogen impregnering av vedflisen vid lägre impregneringstemperatur och under längre tid än vad som vanligen används i industrin. De använda koktemperaturerna är också betydligt lägre än vid konventionell sulfatkokning vilket gynnar jämn delignifiering. Detta resulterar i en smalare kappatalsfördelning jämfört med laboratoriekokade konventionella massor. Massor med höga kappatal undersöktes med avseende på egenskaper hos handark, såsom dragstyrka, dragstyvhet och kompressionsstyrka Det visades att handark från EIC massa vid kappatal 95 hade jämförbara styrkeegenskaper med konventionell massa vid kappatal 82. Vid jämförelse av effekten av stärkelse multilager på konventionella och EIC massor avslöjar liknande effekter. Användningen av stärkelsemultilager ökade dragindex och minskade dragstyvhets- och kompressions index (SCT, short-compression test). Kokprincipen har även använts för att ta fram en serie blekbara massor. Resultaten visar på möjligheten att öka lignininnehållet i massan in till i syrgasdelignifierings-steget eftersom spetinnehållet för milt defibrerad massa var lägre än 0,1% vid kappatal 49. I den här avhandlingen rekommenderar vi att vedflis impregneras i 2 timmar vid 110 °C för att neutralisera sura komponenter i veden och impregnera flisen med kokkemikalier, samt att utföra det efterföljande koket vid 135–140 °C beroende på önskat kappatal. Vi rekommenderar även att öka den tillgängliga mängden kokkemikalier i impregneringssteget genom att använda högre vätske-ved förhållande och att hålla alkali profilen relativt hög i det efterföljande koket. Detta koncept reducerar spetmängden, ger jämnare kokning och ökar selektiviteten för nedbrytning av lignin i sulfatkoket. / QC 20120216