| 1. |
- Engstrand, Per, 1955-
(författare)
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Energy efficient mechanical pulping – summary of the Scandinavian industry initiative research work 2011 - 2015
- 2016
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Ingår i: 2016 International Mechanical Pulping Conference, Jacksonville, Florida, USA September 28-30, 2016. - Georgia 30092 USA : TAPPI Press. - 9781510830738 ; , s. 288-303
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Konferensbidrag (refereegranskat)abstract
- A research program funded by the Swedish Energy Agency, the Swedish Knowledge Foundation and the Research Council of Norway was initiated by the companies; Holmen, Norske Skog, SCA and Stora Enso during 2008 with the objective to demonstrate techniques to reduce electrical energy demand by 50% for production of TMP and CTMP within a 10-year period starting 2011, while retaining similar final product characteristics of printing paper and paperboard. A gap analysis was performed to summarize different options to reach the goal at similar final product quality properties. The gap analysis indicated that some different approaches based on earlier research work both in pilot and demonstration scale together with improved process and product quality control should make it possible to reach the very tough goal. The very thorough benchmarking study was performed during 2012 including 16 TMP and CTMP-lines in Norway and Sweden showed the best production lines had the following electrical energy demands to certain final product properties; 900 kWh/t for CTMP optimized for paperboard, 1800 kWh/t for TMP optimized for newsprint and 2800 kWh/t for TMP optimized for SC-paper. The best results reached in industrial demonstration tests until 2015 showed potential to reduce the energy demand from 900 to 700 kWh/t for paperboard CTMP, from 1800 to 1400 kWh/t for newsprint TMP and from 2800 to 2400 for SC-paper TMP. In addition the results from other research within the program in the form of pilot and demonstration trials indicates that it could be possible to reach the goal of 50% reduced energy demand within a 10-year period provided that the industry and the research funds will continue to finance a continuation of the research program.
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| 2. |
- Eriksson, K., et al.
(författare)
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Benefits from improved stability in process conditions and pulp properties-a double disc refiner case study
- 2016
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Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016. - : TAPPI Press. - 9781510830738 ; , s. 317-327
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Konferensbidrag (refereegranskat)abstract
- The purpose of this case study was to explore the potential for reduced energy consumption by improved process control. The application was HC post-refining of TMP in double-disc refiners. Based on data from both continuous production and from step-response tests, a thorough analysis of process performance was conducted. It was found that a significant proportion of the process disturbances, as reflected in the refiner motor load, could be successfully dampened through stabilizing measures on the basic control level. The remaining disturbances was found to be generated inside the refiner itself. In order for these disturbances to be dampened, measurements that can characterize the conditions inside the refining zone are necessary. Given the present design and instrumentation of the process, dynamic modelling of refiner motor load was performed and for fiber properties, muhivariate modeling methods were used to derive expressions for the independent variables Fl and F2. Taken together, evaluation of the models gave directions on how to further improve the process stability and indicated a potential for reduced energy consumption.
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| 3. |
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| 4. |
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| 5. |
- Johansson, O., et al.
(författare)
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Advancements in optical analysis yields new insight to mechanical pulping processes in an efficient and inexpensive way
- 2016
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Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016. - : TAPPI Press. - 9781510830738 ; , s. 267-276
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Konferensbidrag (refereegranskat)abstract
- Operating costs, pulp quality, and loss of markets continue to dominate the concern of mechanical pulp producers. The search for process improvements, new products, and cost reductions requires significant amount of pulp testing to find out how improvements or new products can be achieved. Unfortunately, the required testing comes at a significant cost due to the time consuming and labor intensive preparation of each sample. For example, a detailed analysis which requires fractionation, hot disintegration, hand sheets, etc. may cost in excess of a thousand dollars. Thus, for an in-depth study where one compares different processes or operating conditions, the cost is significant. At the IMPC conference in Helsinki 2010, 2014 Fernando & Daniel showed how a modern variation of Simon staining can be used to gain information about the fiber wall conditions. This idea has now been expanded further by combining traditional fiber morphology measurements with the information gained from the measurement of color and intensities. In this paper, we will demonstrate a new approach to evaluate mechanical pulps using a special optical analyzer with the ability to process images in color or image intensities. The additional information gained from the color of the images is discussed. For the study, we have been comparing results from three modem commercial installations. The results from these trials are discussed using traditional testing methods in an earlier paper by Ferritsius et al., (2016). We will continue the discussion and show how these pulp samples were analyzed with a new optical device involving minimal sample preparations.
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| 6. |
- Karlström, Anders, 1958, et al.
(författare)
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Refining Efficiency for Future CTMP and TMP systems Co-optimizing Fundamental Wood Material Knowledge with a Soft Sensor Control Approach
- 2016
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Ingår i: International Mechanical Pulp conference. - : TAPPI Press. - 9781510830738 ; , s. 304-316
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Konferensbidrag (refereegranskat)abstract
- Internal variables in (C)TMP-refining processes (e.g. temperature, consistency, fiber residence time, backward flowing steam and forces acting upon the chips and pulp) are defined as physical states obtained in different parts of the refining zones. In short, they differ from the traditional external variables (e.g. dilution water feed rate, load and gap distance) which are not available as distributed variables from refining zone measurements. The internal variables are the backbone of physical models and such models can be used for on-line implementation of soft sensors and advanced process control. Of special interest are the temperature and consistency profiles together with fiber residence time, which are the internal variables in focus of (in) this study. Moreover, they are directly linked to pulp and handsheet property development. To illustrate the capability to use a modeling strategy, two examples are given; one where it is shown how to reach a 40% reduction in specific energy in a CD82-refiner using a new control strategy without violating the pulp properties studied and one example where the consistency can be controlled individually in two parallel Twin refining zones. Hence, the article comprises both temperature and consistency control to reach optimal process conditions. We believe that increased fundamental understanding of the role of the spatially dependent viscosity in refining in general will be a key factor to find ways to further improve energy efficiency of refining.
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| 7. |
- Moilanen, C., et al.
(författare)
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Modelling and simulation of radial spruce compression to optimize energy efficiency in mechanical pulping
- 2016
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Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016. - : TAPPI Press. - 9781510830738 ; , s. 18-35
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Konferensbidrag (refereegranskat)abstract
- Energy efficiency of mechanical pulping is rather low. One possibility to facilitate design of more energy efficient defibration is to model and simulate wood compression. This paper presents an effort to model the behavior of Norwegian spruce in radial compression at defibration circumstances. To identify strain rate dependent properties, compression tests were conducted at both quasi-static conditions and at high strain rate. All tests were done at relevant moisture content and up to defibration zone temperatures and strain rates. Additionally the tests were performed both on native wood and on pre-fatigued wood to include behavior dependency of fatigue. The compression tests were monitored on fiber level to separately model behavior of early- and latewood. The chosen continuum model structure for earlywood and latewood was Voight-Kelvin to enable explicit viscous behavior conditioned by strain rate in parallel to the elastic behavior. The presented model is the first wood compression behavior model individually for earlywood and latewood that is based on wood experiments at industrial defibration circumstances. The influences of temperature and pre-fatigue rise are both softening as expected, The utilization of the compression model was demonstrated in an initial multilayered wood compression simulation.
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| 8. |
- Nelsson, E., et al.
(författare)
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Mill scale production of TMP with double disk refining-The effects of a mild sulfonation, atmospheric preheating and refining temperatures
- 2016
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Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016. - : TAPPI Press. - 9781510830738 ; , s. 249-259
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Konferensbidrag (refereegranskat)abstract
- The aim of this work was to study the effects of a mild dosage of sodium sulfite in chip impregnation at diffen temperatures during atmospheric preheating and during refining for production of TMP for printing papers usi high intensity double disk refining. Two trials were performed in the 800 bdt/day double disc line at I Braviken paper mill (Holmen Paper AB, Sweden) using Norway spruce chips. During the trials, chips w( impregnated in an Impressafiner where chips were preheated at 1.8 bar(g) for a few seconds and th compressed before impregnation. During impregnation, sodium sulfite was added to chips at pH 9 in dosages 0.6 or 1.2%. Reference pulps without addition of sulfite were also produced. In the first trial, the effect different temperatures and retention times (80°C for 6 minutes vs. 96°C for 9 minutes) in the atmosphe preheating bin following impregnation was evaluated both with and without the addition of 1.2% sodium sulf In the second trial, the effect of different refining temperatures (refiner house pressures of 4.6 or 6.4 bar(g), 1 or 167°C) was evaluated with different additions of sodium sulfite (0.0, 0.6 or 1,2%) during impregnation. The results from the two trials showed that the increase in refiner house pressure increased the tensile index pulps both with and without addition of sodium sulfite, when compared at certain SEC. However, the increase preheater bin temperature and retention time did not increase the tensile index of pulps but rather led to a sm reduction in tensile index when combined with an addition of 1.2% sodium sulfite. The two different methc used to increase the temperature in the system led to different effects in the disc gap at certain SEC. The disc j temperature was increased by both methods but disc gap was only reduced at certain SEC when the refini temperature was increased by increasing the refiner housing pressure. The difference in the effect on the disc j may hold the answer to the different effects seen in tensile index.
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| 9. |
- Osong, Sinke H., et al.
(författare)
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Processing of nanocellulose and applications relating to CTMP-based paperboard and foams
- 2016
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Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016. - : TAPPI Press. - 9781510830738 ; , s. 87-93
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Konferensbidrag (refereegranskat)abstract
- Although remarkable success has been made in the production of nanocellulose through several processing methods, it still remain a challenge to reduce the overall energy consumption, to use green chemistry and sustainable approach in order to make it feasible for industrial production of this novel nanomaterial. Herein, we have developed a new eco-friendly and sustainable approach to produce nanocellulose using organic acid combined with high-shear homogenisation, made hydrophobisation of nanocellulose and cross-linked the modified nanocellulosic material. Also, TEMPO-mediated oxidised nanocellulose was produced in order to compare the processing route with that of mild organic acid hydrolysis. Freeze-dried 3D structure of TEMPO-derived nanocellulose foam materials made fi-om bleached sulphite pulp and CTMP, respectively. Further, there is growing interest in using nanocellulose or microfibrillated cellulose (MFC) as an alternative paper sfrength additive in papermaking, and in using chemi-thermomechanical pulp (CTMP) with high freeness in producing CTMP-based paperboard with high bulk properties. To achieve greater strength improvement results, particularly for packaging paperboards, different proportions of cationic starch (CS) or MFC can be used to significantly improve the z-strength, with only a slight increase in sheet density. Research in this area is exploring CS or MFC as potential strength additives in CTMP-based paperboard, which is interesting from an industrial perspective. The mean grammage of the CTMP handsheets produced was approximately 150 g m~, and it was found that blending CTMP with CS or MFC yielded handsheets with significantly improved z-strength, tensile index, burst index and other strength properties at similar sheet densities.
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| 10. |
- Pettersson, Gunilla, et al.
(författare)
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Strong paper from spruce CTMP
- 2016
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Ingår i: International Mechanical Pulping Conference 2016, IMPC 2016. - : TAPPI Press. - 9781510830738 ; , s. 229-233
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Konferensbidrag (refereegranskat)abstract
- This study was carried out on sheets from spruce CTMP fibers, which are surface treated with a mix of cationic starch and CMC and blended with 20% bleach softwood chemical pulp fibers before handsheets were prepared in a Rapid Kothen sheet former, where the sheets were dried to 40-55% d.c. The sheets were pressed in a hot press nip in a pilot machine with adjustable pressure and heat. Both low and high nip pressure were used in combination with two different nip temperatures, 80 °C and 100 °C, to achieve sheets in a broad range of densities. The results show that remarkable improvements are possible, both in terms of tensile index (up to 85 kNm/kg) and compression strength, SCT, (up to 38kNm/kg) on the CTMP-based sheets under optimal conditions at papermaking, i.e. consolidate the sheet structure in a press nip at evaluated temperatures. It is evident from the current study that there is an as of yet unexploited potential in modifying the conditions of papermaking from spruce CTMP furnishes, which can be utilized for the manufacturing of papers with high requirements on strength and stiffness, e.g. packaging papers.
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| 11. |
- Sandberg, Christer, 1962-, et al.
(författare)
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System Aspects on Low Consistency Refining of Mechanical Pulp
- 2016
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Ingår i: TAPPI 2016 International Mechanical Pulping Conference (IMPC). - : TAPPI Press. - 9781510830738 ; , s. 485-495
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Konferensbidrag (refereegranskat)abstract
- Several combinations of high consistency (HC) and low consistency (LC) refiners were evaluated both in main line and reject line for production of pulp for printing papers. HC-LC processes were compared with processes with only HC refining. Processes with two different types of chip refiners were studied – single disc (SD) and double disc (DD). All process combinations were evaluated during continuous production in the Holmen Paper Braviken mill, Sweden. The purpose of this work was to evaluate energy efficiency and pulp quality for the processes.LC refining was more energy efficient than HC refining for certain tensile index increase in all evaluated combinations. The highest energy efficiency was attained when LC refining was utilized in main line, but the difference was small compared to application on reject. Much higher specific energy was applied on reject pulp, but since the reject share was only around 30%, the LC refining specific energy, based on main line production, was around 80 kWh/air dry ton (adt) whereas up to 180 kWh/adt was applied in main line.The combination of DD chip refining and LC refining had the highest energy efficiency (tensile index at certain specific energy consumption) and produced pulp with somewhat lower fibre length but higher light scattering and lower shives content compared to a line with only SD HC refining. Thus, for printing papers it seems beneficial to combine LC refining with high intensity HC chip refining. All processes with LC refining had lower light scattering and fibre length compared to the corresponding system with only HC refining.
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| 12. |
- Schachtl, M., et al.
(författare)
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Experiences with "dithionite Based Additives (DBA) in (C)TMP" in lab, pilot and mill scale : Synergies between high brightness, less specific energy consumption and development of pulp properties
- 2016
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Ingår i: International Mechanical Pulping Conference 2016 (IMPC 2016). - : TAPPI Press. - 9781510830738 ; , s. 59-69
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this paper is to report about our experiences with treating softwood mechanical pulp (MP) with DBA directly injected into the gap of high consistency (HC) refiners used as chemical reactors to improve the competitiveness and the ecological footprint of (C)TMP based products. After the description of the main factors and pros and cons of conventional oxidative and reductive bleaching of sofhvood MP the basic principles of the treatment of MP with DBA in the (C)TMP refiner are outlined. By means of exemplary results of trials in lab, pilot and mill scale as well as of productions the main advantages of "DBA in (C)TMP" are illustrated: efficient brightness gain, reduction of anionic trash, high wood yield, reduction of hard chelating agents, saving of refining energy and increase of strength properties. Using the example of Norske Skog Skogn it is demonstrated how the system works in practice in the production of high bright and standard newsprint made from normal and lower quality wood. Finally it is pointed out that to a certain extent DBAs can be tailored to the needs of the respective mill.
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