| 1. |
- Björk, Elisabeth, et al.
(författare)
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Single-stage hydrocyclone fractionation of refined bleached softwood pulp
- 2017
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Ingår i: Paper Conference and Trade Show, PaperCon 2017: Renew, Rethink, Redefine the Future. - : TAPPI Press. ; , s. 878-905, s. 878-905
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Refined bleached chemical softwood was fractionated using a hydrocyclone in a fine and a coarse fraction. The trials were done at three inject concentrations, three coarse fraction volume ratios, and with pulps refined with two refining levels.A large difference in sheet properties between fine and coarse fraction was observed. Compared with the feed pulp, the relative change in the sheet properties increased more in the fine fractions than it decreased in the coarse fractions. Increased fines proportion had a positive effect on all properties up to a certain level when a further improvement could not be observed. Interestingly, the fine fractions of both refining levels reached the same absolute strength level, both for the tensile properties and z-strength. The fine fractions at the highest coarse fraction mass ratios contained more fines, and the mean fibre was shorter and narrower. This led to higher density but also a decrease of the stretch-at-break and z-strength values.When comparing these results with previous fractionation results for unrefined pulp, it was found that inject concentration did not have a large effect on thickening in the present study. As for the refined pulp, the tensile index increased with fines proportion for the unrefined pulp, however, only up to a certain fines proportion where a maximum values was reached. The increase was larger for the refined pulps which had higher fines proportion.
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| 2. |
- Björk, Elisabeth, et al.
(författare)
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Usage of Fines-enriched pulp to increase strength in CTMP
- 2017
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Ingår i: Paper Conference and Trade Show, PaperCon 2017. - : TAPPI Press. - 9781510847286 ; , s. 1607-1631
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Fines-enriched pulp (FE-pulp) was benchmarked against glue pulp as strength agent in eucalypt CTMP. FE-pulp was produced by combining high intensity multiple-pass refining with a fractionation in a microperforated screen basket. The fraction passing through the holes of the screen is the FE-pulp. The FE-pulp comprises of secondary fines, created in the refiner, and flexible, fibrillated highly-refined fibres or fibre fragments. Glue pulp is highly refined kraft pulp, commonly added as a strength agent in middle plies of board products, or between plies to increase the plybond. Equal amounts of FE-pulp and glue pulp were added to the original CTMP as well as to washed CTMP, where most of the CTMP-fines had been removed. The effects of the strength agents were evaluated using laboratory sheets. Both glue pulp and FE-pulp increased the strength of the CTMP sheets. The bulk of the sheets decreased however. When 5 % FE-pulp was added, the tensile index increased by more than 50 %, and the tensile energy absorption and z-strength increased by more than 100 %. FE-pulp proved to be twice as effective as glue pulp. The addition of 5 % FE-pulp resulted in the same relative strength increase as an addition of 10 % glue pulp. The washed CTMP lost all strength when the CTMP-fines content was reduced from 17 % to 3% through washing. The addition of 5 % FE-pulp restored the strength values, and at a higher bulk. The drainability in terms of CSF of that stock was much higher when compared to the original pulp.
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| 3. |
- Iselau, Frida, 1979, et al.
(författare)
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Towards a mechanism for surface hydrophobization of paper
- 2017
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Ingår i: Paper Conference and Trade Show, PaperCon 2017: Renew, Rethink, Redefine the Future. - 9781510847286 ; 1, s. 131-139
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Konferensbidrag (refereegranskat)abstract
- Surface hydrophobization of paper, also referred to as surface sizing, is often needed for printing and packaging purposes. Typically, hydrophobic nanoparticles in combination with starch are applied on the paper surface. In this study two types of hydrophobic nanoparticle suspensions, one cationic and one anionic, were investigated in order to gain deeper knowledge about the mechanism behind surface sizing. A study was performed where the interactions between the particles and anionic starch were investigated and this study revealed that on addition of starch the cationic particles formed aggregates while the anionic particles were unaffected. This aggregation behaviour was found to be beneficial for the surface sizing performance. The impact of salt was also investigated and it was found that by increasing the ionic strength with NaCl or with Na 2 SO 4 larger agglomerates were formed. The surface hydrophobization efficiency of such aggregates was found to be lower, however.
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| 5. |
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| 6. |
- Rahman, Moksadur, 1989-, et al.
(författare)
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An Approach For Feedforward Model Predictive Control For Pulp and Paper Applications : Challenges And The Way Forward
- 2017
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Ingår i: Paper Conference and Trade Show, PaperCon 2017. - : TAPPI Press. - 9781510847286 ; , s. 1441-1450
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Konferensbidrag (refereegranskat)abstract
- Due to the naturally varying feedstock, significant residence time, insufficient measurements and complex nature of the delignification process, producing pulp with consistent quality i.e. stable kappa number with sufficiently high yield is a challenging task that requires multi-variable process control. A wide variety of control structures, ranging from classical concepts like cascade control, feedforward, ratio control, and parallel control to more modern concepts like model-based predictive control, is used in pulp and paper industries all over the world. In this paper, a survey of model-based predictive control will be presented along with the control challenges that lie within the chemical pulping process. The potential of this control concept for overcoming the aforementioned technical challenges will also be discussed in the second part of the paper. Particular focus will be given on the use of near-infrared spectroscopy based soft-sensors coupled with dynamic process models as an enabler for feedforward model-based predictive control. Overall, the proposed control concept is expected to significantly improve process performance, in the presence of measurement noise and various complex chemical process uncertainties common in pulp and paper applications.
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