| 1. |
- Sandberg, Christer, et al.
(författare)
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Effects of chip pretreatment and feeding segments on specific energy and pulp quality in TMP production
- 2018
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 33:3, s. 448-459
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Tidskriftsartikel (refereegranskat)abstract
- Increased wood softening and refining intensity have earlier been utilized to improve refining efficiency in mechanical pulping. We have evaluated a combination of increased softening by low dose sulphite chip pretreatment and increased intensity by feeding segment design in a TMP line for production of high quality printing papers. Norway spruce wood chips were preheated, compressed in an Impressafiner and impregnated with water or sodium sulphite solutions (Na2SO3 charges 3.6 and 7.2 kg/t). Chips were refined in two parallel 68" double disc refiners using two different refining conditions: standard bidirectional segments at normal production rate (9 t/h) and feeding segments at increased production rate (11.1-12.1 t/h). The feeding segments enabled a 30 % increase in production rate. Refining with feeding segments at 12.1 t/h production rate combined with chip pretreatment with 3.6 kg/t sodium sulphite reduced the specific energy 360 kWh/t (19 %) compared to refining with standard segments and no pretreatment. Pulp properties were similar for the two configurations. The combination of feeding segments and chip pretreatment with water reduced the specific energy 180 kWh/t (9 %). Implementation of most of the technology presented has reduced the electrical energy use for the mill by approximately 80 GWh/year.
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| 2. |
- Ander, Paul, et al.
(författare)
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Sub-project 10: CRUW Mechanical Pulping Enzyme treatment of chips for energy reduction in TMP
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to evaluate the possibilities of using enzymes for pre-treating softwood chips as a means of lowering the energy demand in mechanical pulping, impregnation and refining trials were performed using a set of different enzymes. The enzymes tested pectinase, xylanase and mannanase gave increased sugar release in the impregnation trials indicating that most of the sugar released occurred in the first 60 minutes and that activities thereafter seemed to level off. Refining trials using a small Wing refiner showed that for chips treated for 60 minutes with pectinase, xylanase and mannanase no energy savings to a given freeness level was observed. The property development was similar to that of reference pulps in the case of pectinase and xylanase while for chips treated with mannanase a less favourable development of the tensile index was noted. For chips treated for two hours, using xylanase or pectinase, energy savings could be observed for pectinase treated chips down to a freeness level of 200 CSF. However when refined further, the properties approached those of the reference pulp. Considering the much higher enzymatic activity reached when the initial fibre material was further disintegrated it is assumed that the possibilities for enzymes to attack desired structures of the intact fibre wall may have been too few even in the case of Impressafiner treated material.
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| 3. |
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| 4. |
- Hafrén, Jonas, et al.
(författare)
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Optical properties of thermomechanical pulp (TMP) obtained from sulfite-pretreated Norway spruce with focus on two-photon spectral imaging (TPSI)
- 2012
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 66:7, s. 817-824
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Tidskriftsartikel (refereegranskat)abstract
- Chips of Norway spruce have been impregnated with Na2SO3 and refined at two specific energy consumptions levels at full mill scale. The optical properties of thermomechanical pulps (TMPs) obtained were analyzed in terms of brightness, light scattering, opacity, and autofluorescence by spectral imaging. Even at low sulfite dosage (0.24% sulfite by dry weight) light absorption was reduced, and the brightness was elevated, and a clear dose-response effect was observed. Two-photon spectral imaging (TPSI) showed that sulfonation, impregnation, and refining affect the fluorescence properties differently. Compared to native wood, both processed wood chips and pulp fibers revealed blue-shifted fluorescence maxima, a characteristic of shortened conjugated systems. Two subpopulations of fibers with different optical properties were observed, and the fluorescence of one fiber population was red shifted.
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| 5. |
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| 6. |
- Nelsson, Erik, 1983-
(författare)
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Improved energy efficiency in mill scale production of mechanical pulp by increased wood softening and refining intensity
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the electric energy efficiency of single stage double disc refining for production of printing grade mechanical pulp from Norway spruce wood chips. The thesis is based on the hypothesis, that more energy efficiency refining can be attained by balanced increases of wood softening and refining intensity. Five mill scale trials were performed where wood softening and refining intensity was varied by applying or changing the following process parameters and variables:Chip pretreatment/impregnation with waterLow dosages of sodium sulfite (Na2SO3) added to impregnationTemperature and retention time in the atmospheric preheater binRefining temperature (housing pressure)Feeding segment design combined with increased production rateBy combining suitable increases in wood softening and refining intensity, it was possible to reduce the specific electric energy consumption in refining by 15% (~290 kWh per bone dry ton (bdt)) while preserving important pulp properties within ±5%, compared to the standard double disc refining process. This was done by combining chip impregnation, using an addition of 0.36% (on bone dry basis) sodium sulfite, with a new feeding segment design which enabled 25% higher production rate.When using the new feeding segment design at an increased production rate at unchanged wood softening, it led to reduced fiber length and increased sheet light scattering coefficient at certain tensile index, compared with the standard segment design at normal production rate. This is consistent with the effects normally seen when the refining intensity is increasing. The specific electric energy consumption was 8% lower at a tensile index of 43.5 Nm/g (on Rapid Köthen laboratory sheets) compared to refining at lower intensity using the standard segment design at normal production rate.Mechanical chip pretreatment with subsequent water impregnation showed a reduction in specific electric energy consumption of 6% (~120 kWh/bdt). When chip impregnation was applied in a later trial with a milder chip compression, it led to increased wood softening seen as better preserved fiber length and reduced light scattering coefficient. This resulted in a reduction in tensile index at certain specific electric energy consumption when applied with the standard refining condition but to an increase in tensile index when applied with refining at higher intensity using the feeding segment design at higher production rate.An addition of 1.2% sodium sulfite during impregnation led to a sulfonate content of pulps of ~0.28% (as Na2SO3 equivalents, including post sulfonation) and an average increase in tensile index of about 8.3 Nm/g, when compared to unsulfonated pulps at certain specific electric energy consumption. The increase in tensile index correlated with increased delamination and internal fibrillation of fibers (measured by Simon’s staining), which indicate that the increase in tensile index for sulfonated pulps was a result of improved fiber flexibility and collapsibility. The reduction in disc gap at certain specific electric energy consumption in refining due to an increased wood softening after sulfonation may explain the increase in delamination and internal fibrillation for sulfonated pulps. The smaller disc gap probably led to a more intense refining, i.e. loading at higher deformation rates due to a higher degree of deformation in bar crossings.Different temperatures (80 vs. 97°C) and retention times (6 vs. 9 min.) in the atmospheric preheater bin were studied. This showed that the lower temperature and shorter retention time was beneficial for the tensile strength and light scattering of pulp when applying low dosage sodium sulfite pretreatment. This was most likely a result of too high degree of wood softening prior to defibration in the breaker bar zone when combining low dosage sodium sulfite pretreatment with the higher preheating bin temperature at longer retention time.Different refining temperatures (4.6 and 6.4 bar(g) refiner housing pressure) were evaluated both without and with low additions (0.6% and 1.2%) of sodium sulfite. Raising the refining temperature increased tensile index by 3.2 Nm/g and the addition of 1.2% sodium sulfite by 8.6 Nm/g. The combined increase (~12 Nm/g) was similar to the effect of increasing the specific electric energy consumption by 380 kWh/bdt, when comparing pulps at equal tensile index. However, the pulps produced with increased refining temperature and sodium sulfite addition had lower light scattering coefficient at certain tensile index. The combination of increased refining temperature and addition of 0.6% sodium sulfite was interesting and resulted in pulp with higher tensile index, light scattering coefficient and brightness together with lower shives content at certain specific electric energy consumption, compared with pulp produced at the lower refining temperature without addition of sodium sulfite.Finally, an implementation of the technology presented here is discussed in relation to the Braviken mill (Holmen Paper AB, Norrköping, Sweden) concerning reduction in electric energy consumption and steam recovery. The technology has potential to reduce the electrical energy use by ~100 GWh/year at the Braviken paper mill, where this study was performed.
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| 7. |
- Nelsson, Erik, 1983-, et al.
(författare)
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Improved energy efficiency in thermomechanical pulping through co-optimixation of intensity by segment design and wood softening by sulfonation
- 2014
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Ingår i: International mechanical pulping conference IMPC 2014. - : PI.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A mill scale trial was performed where chips were mechanically pretreated and impregnated with sodium sulfite (<7.2 g/kg). Pretreated chips were refined in two parallel double disc refiners (RGP68DD) using two different conditions: Turbine™ segment at higher production rate (higher intensity) and Low Shive™ segment at normal production rate (lower intensity). By combining the Turbine segments with chip pretreatment using a sodium sulphite charge of 3.6 g/kg it was possible to reduce the specific energy consumption by 15%, while maintaining pulp properties, compared with the lower intensity refining without pretreatment.
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| 8. |
- Nelsson, Erik, et al.
(författare)
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Low dosage sulfite pretreatment at different refining temperatures in mill scale TMP production
- 2017
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 32:1, s. 59-69
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Tidskriftsartikel (refereegranskat)abstract
- The effects of low dosage sodium sulfite ( Na2SO3) pretreatment (0, 0.6 and 1.2% on bone dry wood, pH 9) at two different refining temperatures (4.6 and 6.4 bar(g) refiner housing pressure) were evaluated for production of thermomechanical pulp with a double disc refiner in mill scale using Norway spruce wood at Braviken paper mill (Holmen Paper AB, Sweden). The sulfonate content of the pulps was not affected by the different refining temperatures and was 0.29% (as Na2SO3 equivalents) for the highest sulfite addition.Tensile index at constant SEC was increased by 3.2 Nm/g when the refining temperature was increased, and by 8.6 Nm/g when 1.2% sodium sulfite was added. The effects were additive and led to an increase in tensile index of similar to 12 Nm/g at constant SEC when combined and would enable a reduction in SEC of 380 kWh/bdt (similar to 20%) to similar tensile index. The degree of delamination and internal fibrillation of the fibers was increased by both increased refining temperature and sulfite addition.Pulp brightness was slightly reduced (<= 0.4% ISO) by increased refining temperature and increased (2-3% ISO), when sodium sulfite was added. Spectra of reflectance factors (360-740 nm) were used to study the optical properties of produced pulps.
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| 9. |
- Nelsson, Erik, 1983-, et al.
(författare)
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Low dosage sulfite pretreatment in a modern TMP-line
- 2015
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 30:4, s. 591-598
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Tidskriftsartikel (refereegranskat)abstract
- The effects of low dosage sulfite pretreatment combined with modern high consistency double disc refining were evaluated for production of thermomechanical pulp in a mill scale trial using Norway spruce wood at the Braviken paper mill (Holmen Paper AB, Sweden). Spruce wood chips were mechanically pretreated in an Impressafiner before impregnation with different dosages (0-1.2%) of sodium sulfite (Na2SO3) at pH 9. Approximately 23% of the added sulfite was converted to sulfonate groups in pulp, resulting in a sulfonate content of 0-0.28% (as Na2SO3). The low dosage sulfite addition increased tensile index, elongation, density, brightness and decreased shive content, light scattering and light absorption coefficients when compared at equal specific energy consumption (SEC). The increase in tensile index was proportional to dosage of sulfite. Further analyses showed that low dosage sulfite addition did not affect the distribution of the Bauer-McNett fractions nor the fibre length for pulps refined with equal SEC. However, the low dosage sulfite addition increased fibre delamination/internal fibrillation (D/IF). With the addition of 1.2% Na2SO3, it was possible to produce pulp with a tensile index of 47 Nm/g using ~320 kWh/bdt (~15%) lower refining energy, compared with pulps produced without sulfite addition.
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| 10. |
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| 11. |
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| 12. |
- Nelsson, Erik, 1983-, et al.
(författare)
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Pressurised compressive chip pre-treatment of Norway spruce with a mill scale Impressafiner
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:1, s. 056-062
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Tidskriftsartikel (refereegranskat)abstract
- Mill scale trials were performed to evaluate pressurised compressive chip pre-treatment with the Impressafiner installed in one of the thermomechanical pulp lines at Braviken paper mill (Holmen Paper AB). The aim of the study was to determine if earlier reported effects of the Impressafiner pre-treatment on spruce chips from pilot scale trials (i.e. energy reduction and extractives removal) could also be attained with the mill scale Impressafiner.The mill scale Impressafiner pre-treatment resulted in partial disintegration of chips into a material consisting of fragmented chips with cracks running along the longitudinal fibre axis. Splits or evidence for weaknesses were observed between the primary and secondary fibre walls of pre-treated chips. An increase in water uptake for pre-treated chips was also observed. The extractive content was reduced by up to 24% for pulps produced with pre-treated chips compared to pulps from untreated chips. Pulp produced from pre-treated chips had higher tensile- and tear indices, elongation and light scattering and lower freeness compared to pulps from untreated chips produced with the same total specific energy consumption. The total specific energy needed to reach a tensile index of 47 Nm/g was reduced by 120 kWh/bone dry ton (6%) with Impressafiner pre-treatment. A smaller refiner plate gap was needed to reach the same specific energy consumption for pre-treated chips compared to untreated chips.
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| 13. |
- Nelsson, Erik, 1983-
(författare)
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Reduction of refining energy during mechanical pulping : using pressurised chip compression and sulphite pre-treatment
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The effects of pressurised compressive chip pre-treatment and low dosage sulphite pre-treatment were evaluated for production of thermomechanical pulp in mill scale trials using Norway spruce (Picea abies) at the Braviken paper mill (Holmen Paper AB, Sweden). The general aim of the study was to improve the energy efficiency during the production of mechanical pulps suitable for news and improved news grade papers. The pressurised compressive chip pre-treatment performed in an Impressafiner, resulted in a reduced acetone extractive content for first stage blow line pulp by up to 24%. Furthermore, pulp produced from mechanically pre-treated chips had higher tensile- and tear indices, elongation and light scattering and lower freeness compared to pulps from untreated chips produced with equal total specific energy consumption. The total specific energy consumption was reduced by 120 kWh/bone dry ton (6%) at equal tensile index, when pulps were produced together with the Impressafiner pre-treatment. Sulphite pre-treatment increased tensile index, elongation, density and brightness and reduced light scattering and shive content compared to pulps produced with only mechanical pre-treatment at equal specific energy consumption. The increase in tensile index and reduction in light scattering followed linear relations to the dosage of sodium sulphite in the measured dosage range (0-1.2% Na2SO3). The addition of ~1.2% sodium sulphite gave a sulphur content in pulp of ~0.67% (as Na2SO3) and reduced the specific energy consumption by 210-320 kWh/bdt (12-15%) when compared at equal tensile index. However, light scattering was not retained for this energy reduction. Further analyses showed that sulphite pre-treatment did not significantly affect the distribution of the Bauer-McNett fractions or the fibre length for pulps refined with equal specific energy consumption but did increase fibre delamination/internal fibrillation as measured by Fernando and Daniel’s (2010) version of Simons’ staining. The specific energy consumption for pulps produced with sulphite pre-treatment (1.2% Na2SO3) and double disc refining were 650 kWh/bdt (30%) lower than for pulps produced in a two stage single disc refiner line (no pre-treatment), when compared at a similar tensile index and light scattering coefficient.
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| 14. |
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| 15. |
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| 16. |
- Schjölberg, Ingrid, et al.
(författare)
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IEA-HIA Task 23 Small Scale Reformers for On-site Hydrogen Supply
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of Task 23 Small Scale Reformers for On-site Hydrogen Supply has been to provide a basis for harmonization of technology for on-site hydrogen production from hydrocarbon s– fossil and renewable. The four sub-objectives were to: • Develop a basis for harmonized capacities for the on-site hydrogen reformer unit • Identify and examine issues related to the promotion of widespread use of on-site hydrogen reformer units • Develop a global market guide for the use of on-site hydrogen reformers • Describe the technology link to renewable sources An exclusive network of worldwide suppliers of reformers as well as gas companies and research institutes has contributed to the work. In total 10 countries from 15 companies and institutes have participated in the discussion and evaluation of technology for harmonization of on-site production units enabling more optimal use of feedstock. The ambition has been to contribute to reduced production costs, improved system performance and mass production of on-site reformer units. Task 23 has been successful in creating a platform for discussion and novel collaborations, supplying knowledge and experience on the use of reformers for on-site hydrogen production. On-site hydrogen supply is an important stepping-stone towards the development of a hydrogen infrastructure and a more environmental friendly transport sector. This is seen in the development of hydrogen infrastructures in Europe, US and in Japan where all the demonstration projects have included service stations with on-site production units. Current infrastructure development is mainly part of demonstration projects, and experiences show that hydrogen from on-site production is competitive compared to many other alternatives. Task 23 has contributed development of a basis for safe and harmonized technology and a global market guide for on-site reforming. There is a need to continue this work and ensure a more unbiased verification of on-site production technologies (reforming and electrolysis). Such work can only be performed under an impartial global organisation as IEA-HIA. A continued strong industrial engagement in the work performed under the IEA-HIA is essential to ensure that industrial (real) data are supplied to future analysis, and to ensure global industry support in development of the hydrogen society. There is a strong motivation among the industrial partners of Task 23 to bring forward a new task on small scale production of hydrogen. The network will enable interaction across technology and market segments to support harmonisation of on-site supply technology. The new task will be an industry driven task and empowering the IEA-HIA with research results, industrial support, data and market expertise.
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| 17. |
- Steding Ehrenborg, Katarina, et al.
(författare)
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Diastolic Filling in Patients After Heart Transplantation Is Impaired Due to an Altered Geometrical Relationship Between the Left Atrium and Ventricle
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Ingår i: Journal of the American Heart Association. - 2047-9980.
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe geometrical relationship between atrial and ventricular short‐axis cross‐sectional area determines the hydraulic forces acting on intracardiac blood. This is important for diastolic filling. In patients undergoing heart transplantation (HTx), the left atrium is often enlarged as a result of the standard surgical technique. We hypothesized that diastolic filling in HTx patients is affected by the surgery altering the geometrical relationship between atrium and ventricle.Methods and ResultsThis retrospective, cross‐sectional study included 25 HTx patients (median age, 52 [range, 25–70] years), 15 patients with heart failure with reduced ejection fraction (median age, 63 [range, 52–75] years), 15 patients with heart failure with preserved ejection fraction (median age, 74 [range, 56–82] years), and 15 healthy controls (median age, 64 [range, 58–67] years) who underwent cardiac magnetic resonance imaging. Left ventricular, atrial, and total heart volumes (THV) were obtained. Atrioventricular area difference at end diastole and end systole was calculated as the largest ventricular short‐axis area minus the largest atrial short‐axis area. Left atrial minimum volume normalized for THV (LAmin/THV) was larger in HTx patients (median, 0.13 [range, 0.07–0.19]) compared with controls (median, 0.05 [range, 0.03–0.08], P <0.001), whereas left ventricular volume normalized for THV (left ventricular end‐diastolic volume/THV) was similar between HTx and controls (median, 0.19 [range, 0.12–0.24] and median, 0.22 [range, 0.20–0.25], respectively). At end diastole, when atrioventricular area difference reached its largest positive value in controls, 11 HTx patients (44%) had a negative atrioventricular area difference, indicating impaired diastolic filling.ConclusionsDiastolic filling is impaired in HTx patients due to an altered geometrical relationship between the left atrium and ventricle. When performing cardiac transplantation, a surgical technique that creates a smaller left atrium may improve diastolic filling by aiding hydraulic forces.
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