Single stage and two-stage sodium sulfite cooking were carried out on either spruce, pine or pure pine heartwood chips to investigate the influence of several process parameters on the initial phase of such a cook down to about 60 % pulp yield. The cooking experiments were carried out in the laboratory with either a lab-prepared or a mill-prepared cooking acid and the temperature and time were varied. The influences of dissolved organic and inorganic components in the cooking liquor on the final pulp composition and on the extent of side reactions were investigated. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. A better understanding of the delignification mechanisms during bisulfite and acid sulfite cooking was obtained by analyzing the lignin carbohydrate complexes (LCC) present in the pulp when different cooking conditions were used. It was found that using a mill-prepared cooking acid beneficial effect with respect to side reactions, extractives removal and higher stability in pH during the cook were observed compared to a lab-prepared cooking acid. However, no significant difference in degrees of delignification or carbohydrate degradation was seen.  The cellulose yield was not affected in the initial phase of the cook however; temperature had an influence on the rates of both delignification and hemicellulose removal. It was also found that the  corresponding activation energies increased in the order:  xylan, glucomannan, lignin and cellulose. The cooking temperature could thus be used to control the cook to a given carbohydrate composition in the final pulp. Lignin condensation reactions were observed during acid sulfite cooking, especially at higher temperatures. The LCC studies indicated the existence of covalent bonds between lignin and hemicellulose components with respect to xylan and glucomannan. LCC in native wood showed the presence of phenyl glycosides, ϒ-esters and α-ethers; whereas the α-ethers  were affected during sulfite pulping. The existence of covalent bonds between lignin and wood polysaccharides might be the rate-limiting factor in sulfite pulping. / The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of sodium based single stage bisulfite, acid sulfite and two-stage sulfite cooking of either 100 % spruce, 100 % pine or 100 % pine heartwood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate. LCC (Lignin carbohydrates complexes) studies were carried out to investigate the influence of different cooking conditions on lignin carbohydrate linkages.

No description available.

The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of single stage sodium bisulfite cooking of either 100 % spruce or 100 % pine wood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate and sulfate. / Single stage sodium bisulfite cooking was carried out on either spruce or pine wood chips to investigate the influence of several process parameters in the initial phase of such a cook i.e. between 100 % and 60 % pulp yield. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and time in the initial stage were varied. The influence of dissolved organics and inorganics components in the cooking liquor on the final pulp properties and side reactions were investigated. The impact of temperature and time on the pulp components were analyzed with respect to carbohydrates, lignin, extractives and thiosulfate. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. It was found that if using a mill prepared cooking acid, this had a beneficial effect with respect to side reactions, better extractives removal and higher pH stability during the cook, compared to a corresponding cook with a lab prepared cooking acid. Cooking with mill prepared and lab prepared cooking acids showed the same behaviour with respect to delignification and carbohydrate degradation, but the lab acid experiments resulted in a higher thiosulfate formation during the cook. The cellulose yield was not affected at all during the initial phase of the sulfite cook verifying earlier results by other researchers. The temperature had an influence on both the delignification rate and the rate of hemicelluloses removal.  The corresponding activation energies were found to increase in the following order; cellulose, xylan, glucomannan and lignin. / <p>Artikel 1: "The Initial Phase of Sodium Bisulfite Pulping of Spruce: Part 1" ingick i avhandlingen som manuskript. Nu publicerad.</p>

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Pulp and paper mills are being placed under increasing pressure to maximise the use of the biomass being processed for pulp, and move towards integrated biorefineries (IFBRs), where a diverse range of products can be produced and not just pulp exclusively. Extracting hemicelluloses prior to the pulping process could increase the profitability of the mills as the hemicelluloses could be used to produce a number of additional products. Hemicelluloses are a plant polysaccharides with the most abundant hemicellulose in hardwoods being xylan, with xylose being the primary monosaccharide constituent of xylan. The majority of pulps produced in the Southern Hemisphere are done with hardwoods as feedstock, typically with the Kraft process. The attraction of the concept of extracting hemicellulose prior to pulping is further augmented by the fact that hemicellulose is underutilised in the Kraft process. In the Kraft process the hemicellulose is dissolved during pulping and burned along with lignin for the production of energy, however, hemicellulose has about half the heating value when compared to that of lignin. The main objective of this study was to find a pre-extraction method that is effective in releasing xylan from Eucalyptus grandis, the most important hardwood feedstock used for pulping in the Southern Hemisphere. The method also needs to be practical in terms of integrating it into the Kraft process and should have a minimal effect on pulp yield and subsequent paper qualities. Xylan extractions from E. grandis as feedstock were carried out with white liquor, green liquor and NaOH. Green liquor is the dissolved smelt originating from the recovery boiler in the Kraft process and consists mainly sodium carbonate and sodium sulphide. White liquor’s principal components include sodium hydroxide and sodium sulphide and is used in the digesters during the pulping stage of the Kraft process. NaOH is a make up chemical used in the Kraft process. These chemicals were chosen since they are all already present within the Kraft process. The suitability of these chemicals as xylan extraction methods is further bolstered by the fact that their alkalinity may actually reduce chemical usage in pulping. This provides scope for integration of hemicellulose extraction into Kraft pulping without implementing major changes to the existing industrial process. Moreover, alkali chemicals for pre-extraction allow for minimal effect on resulting pulp and paper. In terms of the extracted product, the alkaline conditions provided by these chemicals create conditions that are suitable for a high degree of polymerisation of hemicelluloses. Xylan pre-extracted chips from selected extraction conditions were subjected to varying pulping conditions, to replicate pulp yields and properties obtained with untreated E. grandis chips when using conventional pulping. Handsheets were also produced from the pulps produced under the highest pulp yield conditions, and these were tested for pulp quality properties. Furthermore, mass balances were performed to gauge the impact that hemicellulose pre-extraction would have using green liquor, white liquor and NaOH on the sodium and sulphur balances of the mill. From the extractions performed, the highest fraction of xylan recovered was 15.15% w/w utilising 2M NaOH, at 120°C for 90 minutes extraction time. This was followed by white liquor extraction at 13.27% w/w utilising 20% AA at 140°C for 90 minutes. Green liquor extraction produced the lowest xylan recovery at 7.83% w/w with 2% TTA and 160°C with an h-factor of 800. The residues from selected extraction conditions were utilised for these pulping optimisation experiments. Selected extraction conditions used for further pulping included 2% TTA and 160°C for green liquor, 20% AA and 120°C and 140°C extraction temperature for white liquor, as well as 2M concentration and 120°C for NaOH. The highest yielding pulping conditions were achieved with a 35% reduction in pulping chemicals and 45 minutes pulping time in combination with green liquor pre-extraction, while for pulping combined with white liquor pre-extraction a 50% reduction in chemicals and 30 minute pulping time was preferred. For pulping subsequent to NaOH pre-extraction a 75% reduction in the NaOH dosage and a 45 minute pulp time was preferred. All pulp steps were performed at 170°C. Unbeaten handsheets produced from the selected pulping conditions for white liquor and green liquor extracted chips showed similar physical properties (burst, tear, tensile indices) when compared to the control (pulps from non-extracted chips). However the greater quantity of xylan removed from cellulose fibres with NaOH extraction, resulted in pulps with lower xylan contents, which affected the burst and tear indices of the handsheets formed from these pulps. An increase in tear, while a reduction in the burst index, was observed for the pulp produced from NaOH extracted chips. It was concluded that although white liquor and NaOH extraction allows for greater xylan recovery, the large chemical expenditure associated with these methods will impose significant cost impacts on the existing Kraft process. From mass balances performed, green liquor xylan extraction due to its lower alkalinity, will be more forgiving in terms of additional make up chemical costs. It also allowed for minimum effect on both the pulp and paper quality, thus making it the most practical of the pre-extraction methods. However, whether the additional make chemicals required for the green liquor extraction method will be justified by the quantity of xylan extracted will only be answered by a thorough economic assessment, which was not in the scope of this project. / AFRIKAANSE OPSOMMING: Pulp- en papiermeule word onder toenemende druk geplaas om die gebruik van die biomassa wat vir pulp verwerk word, te maksimaliseer, en om te beweeg na geïntegreerde bioraffinaderye, waar ʼn groot verskeidenheid produkte vervaardig kan word, en nie slegs uitsluitlik pulp nie. Die ekstraksie van hemisellulose voor die verpulpingsproses kan die winsgewendheid van die meule verhoog, aangesien die hemisellulose gebruik kan word vir die vervaardiging van verskeie bykomende produkte. Hemisellulose is ʼn plantpolisakkaried, met xilaan as die hemisellulose wat die oorvloedigste in hardehout gevind word, en met xilose as die primêre monosakkaried-bestanddeel van xilaan. Die meerderheid van die pulp wat in die Suidelike Halfrond geproduseer word, word met hardehout as voerstof gedoen, tipies met behulp van die Kraft-proses. Die aanloklikheid van die konsep om hemisellulose voor verpulping te win, word verder versterk deur die feit dat hemisellulose in die Kraft-proses onderbenut word. In die Kraft-proses word die hemisellulose tydens verpulping opgelos en saam met lignien verbrand vir die opwekking van energie, maar hemisellulose het egter ongeveer die helfte van die verhittingswaarde van dié van lignien. Die vernaamste doelstelling van hierdie studie was om ʼn pre-ekstraksiemetode te vind wat xilaan doeltreffend van Eucalyptus grandis, die belangrikste hardhout-voerstof wat in die Suidelike Halfrond vir verpulping gebruik word, kan vrystel. Die metode moet ook prakties wees met betrekking tot integrering met die Kraft-proses, en dit moet ʼn minimale uitwerking op pulpopbrengs en gevolglike papiergehalte hê. Xilaan-ekstraksie uit E. grandis as voerstof is uitgevoer met wit loog, groen loog en NaOH. Hierdie chemikalieë is gekies omdat hulle reeds in die Kraft-proses teenwoordig is. Die geskiktheid van hierdie chemikalieë as xilaan-ekstraksiemetodes is verder ondersteun deur die feit dat hul alkaliniteit moontlik chemiese verbruik in verpulping kan verlaag, wat ruimte vir die integrasie van hemisellulose-ekstraksie in Kraft-verpulping laat sonder om grootskaalse veranderinge aan bestaande nywerheidsprosesse te implementeer. Alkali-chemikalieë vir preekstraksie lei boonop tot ʼn minimale uitwerking op resultante pulp en papier, terwyl die alkalitoestande, met betrekking tot die geëkstraheerde produk, toestande skep wat geskik is vir ʼn hoë mate van polimerisasie van hemisellulose. Uit die ekstraksies wat uitgevoer is, is die hoogste fraksie xilaan gewin deur die gebruik van NaOH teen 15.15% w/w met 2M NaOH, teen 120 °C vir 90 minute ekstraksietyd. Dit is gevolg deur witloog-ekstraksie teen 13.27% w/w met die gebruik van 20% AA teen 140 °C vir 90 minute. Groenloog-ekstraksie het die laagste xilaan-winning teen 7.83% w/w met 2% TTA en 160°C met ʼn h-faktor van 800 voortgebring. Houtspaanders wat aan xilaan-pre-ekstraksie met groen loog onderwerp is, het pulp met kappanommers en opbrengste soortgelyk aan dié van nie-geëkstraheerde spaanders voortgebring toe die chemiese lading met 35% verlaag is, in verhouding tot dít wat vir niegeëkstraheerde spaanders gebruik is. Xilaan-pre-geëkstraheerde spaanders met wit loog het ʼn 50%-vermindering in verpulpingschemikalieë gelewer in verhouding tot houtspaanders wat aan konvensionele verpulping onderwerp is. Die chemiese reduksie van groen loog was minder as dié van wit loog weens die laer alkalilading wat tydens hemisellulose-ekstraksie voor verpulping gebruik is. Vir witloog-ekstraksie kon pulpopbrengste gehandhaaf word, alhoewel pregeëkstraheerde spaanders met wit loog ʼn neiging getoon het om pulp met laer kappanommers voort te bring. Alhoewel pulp wat uit houtspaanders gemaak is wat aan NaOH-ekstraksie onderwerp is, gelei het tot ʼn 75%-vermindering van NaOH gebruik in verhouding tot dié van konvensionele verpulping, is verwag dat geen NaOH benodig sou word nie, aangesien die houtspaanders reeds tydens xilaan-ekstraksie aan 2M NaOH blootgestel is. Voorts, in die literatuur is verpulping uitgevoer ná 2M NaOH-ekstraksie sonder dat die toevoeging van NaOH tydens verpulping nodig was [61]. Handvelle is vervaardig uit die pulp wat in die hoogste pulpopbrengs-toestande vervaardig is, en dit is vir pulpgehalte-eienskappe getoets. Die verpulpingstoestande met die hoogste opbrengs is bereik met ʼn 35%-vermindering van verpulpingschemikalieë en 45 minute verpulpingstyd in kombinasie met groenloog-pre-ekstraksie, terwyl vir verpulping met witloogpre- ekstraksie ʼn 50%-vermindering van chemikalieë en 30 minute verpulpingstyd verkies is. Vir verpulping ná NaOH-pre-ekstraksie is ʼn 75%-vermindering van die NaOH-dosis en 45 minute verpulpingstyd verkies. Alle verpulpingstappe is teen 170°C uitgevoer. Ongeklopte handvelle vervaardig uit die gekose verpulpingstoestande vir witloog- en groenloog- geëkstraheerde spaanders het soortgelyke fisiese eienskappe getoon (bars-, skeuren trek-indeks) in vergelyking met die kontrole (pulp uit nie-geëkstraheerde spaanders). Die grootste hoeveelheid xilaan is egter uit sellulose vesel met NaOH-ekstraksie verkry, wat gelei het tot pulp met laer xilaaninhoud, wat die bars- en skeur-indeks van die handvelle wat uit hierdie pulp vervaardig is, beïnvloed het. ʼn Toename in die skeur-indeks, met ʼn afname in die bars-indeks, is waargeneem vir die pulp wat uit NaOH-geëkstraheerde spaanders vervaardig is. Die gevolgtrekking is gemaak dat alhoewel witloog- en NaOH-ekstraksie groter xilaanwinning moontlik maak, die groot chemiese uitgawe geassosieer met hierdie metode ʼn aanmerklike koste-impak vir die bestaande Kraft-proses inhou. Groenloog-xilaanekstraksie sal, weens die laer alkaliniteit, meer geskik wees met betrekking tot die koste van bykomende aanvullende chemikalieë. Dit hou ook ʼn kleiner uitwerking op die pulp- en papiergehalte in, wat dit dus die praktieste van die pre-ekstraksiemetodes maak. Of die bykomende chemikalieë nodig vir die witloog- en NaOH-ekstraksies egter geregverdig kan word deur die hoeveelheid xilaan wat gewin is, kan slegs deur ʼn deeglike ekonomiese assessering beantwoord word, wat nie binne die omvang van hierdie projek geval het nie.

SAPPI SAICCOR is a pulp and paper mill situated in Umkomaas, 50 kms south of the port of Durban in South Africa. It was the first company to produce high grade dissolving pulp from the Eucalyptus tree and is currently the world's largest manufacturer of chemical cellulose. SAICCOR is one of the few pulp and paper mills that produces its dissolving pulp by the acid sulphite process using both calcium and magnesium as bases in the form of calcium bisulphite and magnesium bisulphite. Four streams of effluent are produced during their process, namely, the calcium spent liquor, the magnesium pulp condensate and two streams from the bleaching stages. An acid hydrolysis of the effluent streams yielded a range of organic compounds such as lignans and lignin - type precursors as well as a triterpenoid. Column chromatography and thin layer chromatography, using various ratios of hexane, dichloromethane, ethyl acetate and methanol, were carried out in isolating and purifying the compounds. The structures of these compounds were determined using NMR spectroscopic and mass spectrometric techniques. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

An experiment was designed to test the hypothesis that each softwood pulp is unique and requires a specific, well defined mechanical treatment to derive its maximum strength potential. Three bleached softwood Kraft pulps and respective wood samples were sourced from both the Northern and Southern Hemispheres. The raw fibre characteristics of P. patula (Southern Hemisphere), P. menziesii (Northern Hemisphere) and P. mariana (Northern Hemisphere) were measured and compared. The raw pulp sheets were refined at different energies and intensities under controlled laboratory conditions using a 12” single disc pilot refiner. Results were assessed to determine the raw fibre characteristics, optimum refining conditions and the relative refined strength potential for each of the three samples. Results from anatomy measurements on the three wood samples differed significantly. P. patula exhibited a relatively high proportion of springwood growth in the early growing years. As the P. patula aged and formed mature wood there was a significant increase in the frequency of latewood formation. This was characterized by an abrupt and significant increase in the wall thickness, beyond that of the two Northern softwood samples. When the cell wall thickness increased, the lumen width and fibre diameter of the P. patula decreased significantly, yielding extremely coarse, stiff fibres. The Northern P .mariana and P. menziesii samples were characterized by a relatively consistent transition between high and low densities from the pith to the bark of the tree. The Southern P. patula had a unique density trend with an increasing frequency of high density peaks indicative of an increased latewood formation from the pith to the bark. The slower growing Northern P. menziesii and P. mariana samples did not have as clear a differentiation in fibre characteristics between juvenile and mature wood formation. The Northern samples did however contain a significantly higher proportion of juvenile latewood growth than the P. patula. However, the difference in fibre characteristics between earlywood and latewood formation was not as significant as that noted with the Southern P. patula Fibre morphology measurements on the unrefined bleached Kraft pulps also revealed significant differences between the three samples. The average MORFI LAB01 results on the P. patula defined fibres with a high coarseness and relatively low number of fibres per gram of pulp. The extremely coarse latewood fibres formed during mature wood growth being the most likely source. However, P. patula was also characterized with a high fibre flexibility and large lumen, characteristics consistent with earlywood fibres. The Pulmac Z-Span 3000 was used to define the individual fibre strength, when due consideration was given to the number of fibres per gram, the corrected Pulmac results suggested P. patula had the strongest fibres. When refined, using a standard disc refining programme, P. patula exhibited a fast freeness development. Conventional thinking would suggest that this was an indication of a weaker fibre. However, this species had a robust morphology compared to the Northern Hemisphere woods. The theory developed in this dissertation suggests that the effect of coarseness and the concomitant number of fibres per gram plays a significant role. These two parameters are not included in the “traditional” refining calculations. The applied refining load and intensity was calculated on the flow of the pulp passing through the refiner. The calculation did not consider the actual number of fibres present in that specific volume. The implication is that when a fixed refining load is applied to a pulp with coarse fibres there may be a higher effective load on those fewer fibres (resulting in fibre cutting and fines generation). In this case, the Northern samples have a comparatively low coarseness and more fibres per gram with each receiving a smaller portion of the total load and intensity. In terms of refined pulp properties, P. patula developed a relatively high bulk and tear index consistent with coarse, rigid fibres. The Northern P. mariana and P. menziesii samples produced a pulp with good tensile properties, consistent with a greater number of finer, collapsible fibres with a higher relative bonding area. P. patula fibres were extremely heterogeneous in nature containing the smallest relative lumen width during latewood formation and the largest lumen width during earlywood growth. As a result, P. patula contains extremes of both fine and coarse fibres in the same blend. It may be more beneficial for this species than the others to improve both the tear and tensile properties through fibre fractionation with appropriate development of the separate accepts and rejects streams. In terms of fibre development, low intensity refining parameters maximized the tensile strength of the Southern P. patula. The Northern P. mariana and P. menziesii samples had a greater number of fibres per gram of pulp requiring both a higher refining energy and intensity to develop the pulp to its maximum potential. To develop optimum tear results, high intensity refining, with a relatively low specific energy provided optimum results for all 3 samples. Results confirmed that there were significant differences in the fibre morphology both between the three different species and between the two Hemispheres. There was strong evidence that the fibre characteristics dictate the manner in which a fibre responds to refining which in turn determines the relative contribution to specific refined pulp properties. It may be possible to use fibre characteristics to determine the appropriate refining parameters for optimal fibre development which will enhance the value of the end product. To derive the maximum strength potential from P. patula pulp samples, it is recommended that further studies investigate Hydracyclone fractionation and the concomitant benefits of refining the separate streams. Furthermore, a separate study on fibre morphology and refining characteristics of the same species grown in both the Northern and Southern Hemisphere would provide valuable insight. / Thesis (M.Sc.Eng)-University of KwaZulu-Natal, Durban, 2009.

The chemistry of the batch cooking process at Sappi Saiccor, relating to both the pulp and liquor, was investigated with the aim of using kinetic expressions to develop an improved process control model. The mill produces dissolving pulps using the acid sulphite method. Three process reactions were identified as important: cellulose hydrolysis, delignification and hemicellulose dissolution. Of these, cellulose hydrolysis is the most important since the primary aim is to achieve a targeted cellulose degree of polymerisation (DP) or viscosity (DP is commonly expressed in terms of this measurement). This is directly determined by the rate of this reaction during the cook, and the acidity of the cooking liquor was found to be the key factor. As existing equipment was not suitable for obtaining the data required to perform a kinetic analysis, a pilot plant was constructed. A commercially available probe was used for the first time to measure pH directly. The measured acidity is not directly equivalent to hydrogen ion activity at these temperatures and pressures; however, since the conditions of each cook are similar the errors incurred were found to be constant from cook to cook. The probe was found to be prone to drift due to ageing and this was accounted for by using an 'on line' calibration based on a liquor analysis. The kinetics of the cellulose hydrolysis reaction were determined using the on-line measurement of acidity and the concept of degradation increase (DI) which relates the reduction in DP value to the rate at which the polymeric chains are split. Delignification and hemicellulose dissolution were examined, since it is beneficial to maximise these reactions to reduce the quantities of chemicals consumed during the bleaching process. A model for controlling cooks to a set target cellulose DP value within a set time was developed based on the reaction kinetics. This was capable of predicting cooking conditions required with sufficient accuracy to control the cellulose DP value to within ±6 cp SNIA on the viscosity scale. / Thesis (M.Sc.Eng.)-University of Natal, 1992.

Kraft pulping, also known as sulphate pulping is a complex process where the wood components are liberated from each other facilitated by chemical reactions. During the pulping process some dissolved and degraded compounds end up together with the spent cooking chemicals in the black liquor. In kraft pulping of hardwood, the black liquor contains substantial amounts of dissolved hemicellulose, especially xylan due to the wood composition. The xylan content is of high value due to its ability to re-deposit by adsorption on cellulose fibres and its tendency to increase pulp strength and yield. In this work, the possibility of introducing xylan rich, hardwood black liquor from the hardwood digester into the softwood digester at the process of SCA – Munksund was studied. The objective was to investigate if hardwood black liquor addition in a softwood cook can increase the yield and pulp strength. The theoretical feasibility of altering the process was investigated by a literature review and a brief process investigation. During the study a total of eight lab cooks were conducted to obtain information on how hardwood black liquor addition changes the pulp quality of regular softwood cooks. The wood chips, white liquor and hardwood black liquor used were collected at Munksund and the process conditions in the lab cooks were chosen to simulate the actual process in the Munksund mill. In addition to the cooking, chemical and physical evaluation on pulps, cooking liquors and wood chips were performed. The theoretical evaluation indicates that the process in Munksund is well suited for introducing the hardwood black liquor in to the softwood digester. The chemical analysis of the black liquors show a xylan content that is approximately four times higher in the hardwood black liquor compared to the softwood black liquor. In the kappa number range of approximately 80-90, a total yield increase of 0.4%-units was obtained for two cooks with hardwood black liquor addition compared to their corresponding reference cooks. A carbohydrate analysis showed a higher xylan content in the pulp cooked with addition of hardwood black liquor compared to the corresponding reference pulp. One pulp with hardwood black liquor addition and its corresponding reference cook were refined in an Escher Wyss lab mill. The pulp with hardwood black liquor addition exhibits an increase or retained strength for all strength evaluation tests made on handmade pulp sheets. Strength increases of approximately 5% were obtained for tensile index and ISO-Z strength for a pulp with hardwood black liquor addition.   The results conducted in this study shows that it can be possible to slightly increase both the yield and some pulp strength parameters when adding hardwood black liquor in to the softwood cook in lab scale. It is also shown that the increase in the total yield most likely depends on xylan adsorption on the cellulose fibres. The calculated increased revenue for this process change could be over 400 000 Euro per year.

Submitted in the fulfillment of the requirements for the degree of Master of Technology, Durban University of Technology, Durban, South Africa, 2011. / The main objective of this study was to evaluate the feasibility of conversion of crude tall oil and tall oil fatty acids into biodiesel. During the Kraft pulping process, Crude Tall Oil originates as tall oil soap, which is separated from recovered black liquor. The soap is then converted to Crude Tall Oil by acidulation with sulphuric acid. The Crude Tall Oil is then fractionated by distillation to produce tall oil fatty acids (TOFA), rosin and pitch. There were a number of conversional methods that were considered but proved to be inappropriate. A base-catalyzed method was inappropriate with due to the high free fatty acid content on the feedstock, and the acid-base catalyzed method was inappropriate due to the long reaction times and large excess of methanol required. An enzyme based conversion method was also found to be inappropriate because of the high price attached to the purchasing of the enzymes and the stability of the enzyme. A procedure of choice was the supercritical methanol treatment, due to the fact that it requires no separate catalyst. A procedure was developed for both the feedstocks (i.e. crude tall oil and tall oil fatty acids) using the supercritical methanol treatment. In supercritical methanol treatment, feedstock and methanol were charged to a reactor and were subjected to temperatures and pressures beyond the critical point of methanol (Tc = 240 °C, Pc = 35 bar). The maximum biodiesel yield obtained from Crude tall oil was 66% and was 81% for the tall oil fatty acids that was produced in a single stage process. The temperature and methanol to feedstock ratio effects was also found to yield a maximum biodiesel yield at 325°C and 40:1 respectively. A 20 minutes reaction time was found to be appropriate for the maximum yield of biodiesel. The final biodiesel produced was also evaluated against a commercial biodiesel product and its parameters measured. The biodiesel resulting from the tall oil fatty acid yielded parameters that were acceptable according to ASTM D6751 specifications for biodiesel. The biodiesel produced from the crude tall oil did not meet the ASTM D6751 specification, and this was mostly attributed to the presence of unsaponifiables which hindered the conversion of oil into biodiesel. / M

The electrical energy consumption in thermomechanical pulping (TMP) is very high, in the range of 2 – 3 MWh/adt depending on process solution and on the product quality specifications for the paper product. Both pulpwood and energy prices have increased rapidly for some time. Due to this, the main focus of the research and development is on ways to reduce the electrical energy consumption in wood chip refining. As a step towards a more energy and cost ‐ effective refining process, Holmen Paper AB has invested in a new mechanical pulping process at its Braviken mill. In this case the primary refining stage consists of high consistency (HC) double disc refiners ‐ RGP68DD (machines with two counter rotating discs). Earlier studies on the refining conditions, such as intensity and temperature, have indicated that it should be possible to improve the energy efficiency in double disc refining while maintaining the functional pulp properties such as tensile index. The main goal of this project was to improve the energy efficiency in double disc chip refining with 150 kWh/adt to corresponding pulp properties as measured on pulp samples after refiner. In order to further improve the basic understanding of what happens to the wood fibre material when changing the process conditions, the morphological and ultrastructural changes of fibres were also studied. This part of the research work was performed in cooperation with the research program; Collaborative Research on the Ultrastructure of Wood Fibres (CRUW). This licentiate project is a part of a large development project where different techniques to improve the energy efficiency has been evaluated by means of mill scale trials at the Holmen Paper Braviken Mill. The high consistency double disc chip refining part of the project was financed by The Swedish Knowledge Foundation, Metso Paper and Holmen Paper, in cooperation with FSCN (Fiber Science &amp; Communication Network) at Mid Sweden University. The trials were made on one of the TMP lines at the Holmen Paper Braviken mill with Norway spruce as raw material. The influence of increased specific      refining energy on pulp properties were studied at different refining temperatures, refining intensity, pulp consistency and production rate. Results from these trials were later validated by means of long term trials. Intensity models and simulations for intensity changes by new segment design were made by Juha‐ Pekka Huhtanen from Tampere University of Technology, Finland. The results show that the specific energy consumption to same tensile index can be improved by means of increasing the refining pressure/temperature. The energy efficiency was improved by 80     ‐150 kWh/adt depending on load and the inlet‐ and housing pressure. The largest relative specific energy efficiency improvement was reached at low specific energy consumption levels. Similar fibre surface ultrastructure characteristics are gained by pulps with high pressure/temperature and low specific energy consumption compared to low pressure/temperature and high specific energy consumption pulps. High pressure/temperature and high specific energy consumption resulted in significantly increase in the delamination/internal fibrillation of pulp fibres. The surface ultrastructure of these fibres exhibited exposed S2 layer with long ribbontype fibrillation compared to pulps produced with lower temperature and lower specific energy consumption. When the refiner was operated at high pressure, the tensile index was preserved over the whole plate life. The specific light scattering coefficient increased with increasing pressure/temperature. A reason for this could be increased intensity caused by decreased plate gap. Increased intensity by means of refiner segment design changes resulted in large specific light scattering coefficient increase at similar tensile index, lower shives content, lower average fibre length and lower CSF at same specific energy consumption. The fresh steam consumption was reduced by the increased refiner ressure/temperature. / Den höga elenergiförbrukningen vid produktion av mekanisk massa har ställtkrav på mer forskning för att elenergieffektivisera raffineringsprocessen. Som ettsteg mot en mer energi‐ och kostnadseffektiv raffineringsprocess, har HolmenPaper AB investerat i en ny tillverkning av termomekanisk (TMP) massa vidBravikens pappersbruk. Dubbeldiskraffinörerna i den nya massalinjens primäraraffineringssteget studerades i detta projekt. Det finns goda indikationer på att enminskning av energiförbrukningen är möjlig genom att studerar och optimeraraffineringparametrar såsom intensitet och temperatur. Projektets huvudmål varatt energieffektivisera det primära dubbeldiskraffineringssteget med 150 kWh/adttill motsvarande massaegenskaper, så som dragstyrka, mätt på massa efterraffinör. Tillfälle gavs också till att studera morfologiska förändringar på fibrer föratt ytterligare förstå hur massa och fibrerna påverkas av dubbeldiskraffinering ochförändringar i raffineringssystemet.Detta licentiatprojekt är en del av ett större projekt där olika tekniker för attförbättra energieffektiviteten har utvärderats i industriell skala på Holmen PaperBravikens pappersbruk. Licentiatprojektet är finansierat av KK‐stiftelsen, MetsoPaper och Holmen Paper, i samarbete med Mittuniversitetet.Fullskaleförsök gjordes på en av TMP linjerna vid Bravikens pappersbruk, därgran används som råvara. Studien utfördes på dubbeldiskraffinörerna i detprimära raffineringssteget. Malkurvor, med ökande specifik raffineringsenergi,gjordes vid olika raffineringstemperaturer, intensitet, massakoncentration ochproduktion. Resultat som erhållits från malkurvorna bekräftades med längrestudier på raffinörerna. Intensitetsmodeller och simuleringar utfördes av Juha‐Pekka Huhtanen från Tampere University of Technology.De erhållna resultaten visar på att energiförbrukningen till ett visst dragindexkan minskas genom att öka raffineringstrycket/temperaturen. Medraffineringstryck menas inlopp och hustryck i raffinören. Energibesparingen är iintervallet 80‐150 kWh/adt. Den största förbättringen kan uppnås vid lågaenergiinsatser. Massor producerade med högt tryck och temperatur och lägrespecifik energiförbrukning uppvisar liknande ultrastrukturella ytegenskaper sommassor producerade med lågt tryck och temperatur och hög specifik energi. Högttryck och temperaturer med hög specifik energiinsats gav en signifikant förbättringav delaminering/intern fibrillering av massafibrer. Dessa fibrer uppvisadebildningar av långa band‐liknande fibriller från fibrernas S2 skikt, i jämförelse medmassor tillverkade med lägre tryck och temperatur och lägre specifik energi.5Om raffineringen genomförs vid högt tryck/temperatur bevaras dragindexunder hela segmentlivslängden.Den specifika ljusspridningskoefficienten påverkades positivt av ökat tryck ochtemperatur. En orsak till detta kan vara högre intensitet som orsakas av minskadmalspalt.Ökad intensitet genom förändrad segmentdesign leder till stora ökningar i denspecifika ljusspridningskoefficienten. Samtidigt uppnås samma dragindex, lägrespethalt, lägre genomsnittlig fiberlängd och CSF vid samma specifikaenergiförbrukning.Förbrukningen av färskångan sänktes vid tillämning av högre tryck ochtemperatur i raffinören.