Development of fibre properties in mill scale high- and low consistency refining of thermomechanical pulp (Part 1)

2020 ◽  
Vol 35 (4) ◽  
pp. 589-599
Author(s):  
Rita Ferritsius ◽  
Christer Sandberg ◽  
Olof Ferritsius ◽  
Mats Rundlöf ◽  
Geoffrey Daniel ◽  
...  
Keyword(s):  
Light Scattering ◽  
Norway Spruce ◽  
Specific Energy ◽  
Mass Fraction ◽  
Fibre Length ◽  
Thermomechanical Pulp ◽  
Fibre Property ◽  
Fibre Properties ◽  
Tensile Index ◽  
Lower Light

AbstractThe aim of this study was to evaluate changes in fibre properties with high (HC)- and low consistency (LC) refining of TMP and determine how these contribute to tensile index. Two process configurations, one with only HC refining and another with HC refining followed by LC refining were evaluated in three TMP mainline processes in two mills using Norway spruce. An increase in tensile index for a given applied specific energy was similar for all LC refiners in the three lines, despite differences in the fibre property profiles of the feed pulps. Compared with only HC refined pulps at a given tensile index, HC+LC refined pulps had greater fibre wall thickness, similar fibre length, strain at break and freeness, but lower light scattering coefficient, fibre curl and external fibrillation. The degree of internal fibrillation, determined by Simons’ stain measurements, was similar for both configurations at a given tensile index. The results indicate that the increase in tensile index in LC refining is largely influenced by a decrease in fibre curl and in HC refining by peeling of the fibre walls. Compared at a given tensile index, the shive content (Somerville mass fraction) was similar for both HC+LC and HC refining.

scholarly journals TMP properties and refining conditions in a CD82 chip refiner. Part I: Step changes of process variables, description of the tests

2018 ◽  
Vol 33 (1) ◽  
pp. 69-81
Author(s):  
Rita Ferritsius ◽  
Olof Ferritsius ◽  
Jan Hill ◽  
Anders Karlström ◽  
Karin Eriksson
Keyword(s):  
Specific Energy Consumption ◽  
Fibre Length ◽  
Thermomechanical Pulp ◽  
Process Variables ◽  
Negative Effects ◽  
Entropy Model ◽  
Tensile Index ◽  
Pulp Consistency ◽  
Pulp Properties ◽  
Flat Zone

Abstract The study explores how changes in process variables, residence time and pulp consistency in refining influence the pulp properties. The equipment utilized in this study was a conical disc chip refiner (RGP82CD) producing thermomechanical pulp (TMP). The focus was on the ratio between tensile index and specific energy consumption. Pulp properties were measured for composite pulp samples taken from the refiner blow line. Residence times and pulp consistencies were estimated by use of the extended entropy model. This showed that the CD-refiner, with the flat and conical refining zone, has a process performance similar to that of a two-stage refiner set-up, and that the consistency in both refining zones is of high importance. Comparing different periods revealed that even if the values of measured blow line consistency are similar, significant differences in the estimated consistency in the flat zone can prevail. Therefore, only monitoring blow line consistency is not enough. Specifically, it was found that the pulp consistency after the flat zone could be very high, considerably higher than in the blow line, and this could have negative effects on tensile index and fibre length.

Wood-density variation of Norway spruce in relation to nutrient optimization and fibre dimensions

2002 ◽  
Vol 32 (2) ◽  
pp. 185-194 ◽  
Author(s):  
Harri Mäkinen ◽  
Pekka Saranpää ◽  
Sune Linder
Keyword(s):  
Cell Wall ◽  
Norway Spruce ◽  
Wood Density ◽  
Wall Thickness ◽  
Annual Ring ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Cell Wall Thickness ◽  
Fibre Properties ◽  
The Absolute

The effect of fertilization on wood density, fibre length, fibre diameter, lumen diameter, proportion of cell wall area, and cell wall thickness of Norway spruce (Picea abies (L.) Karst.) were studied in a nutrient optimization experiment in northern Sweden. On the fertilized plots, all essential macronutrients and micronutrients were supplied in irrigation water every second day during the growing season. After 12 years' treatment, data were collected from 24 trees (40 years old) on the fertilized and control plots. Fertilization increased radial growth more than threefold, especially earlywood width, and decreased wood density by over 20% at 1.3 and 4 m height. The decrease in wood density was closely related to the proportion of latewood. The absolute wood density also decreased across the whole annual ring but proportionately more in latewood than in earlywood. A close relationship was found between the wood density and fibre properties, especially with the proportion of cell wall in a cross section of each annual ring, as well as with fibre and lumen width. The absolute cell wall thickness was clearly less related to wood density. However, rather large variations were found between individual trees in the relationship between wood density and fibre properties.

scholarly journals Low consistency refining of mechanical pulp — system design

TAPPI Journal ◽  
2017 ◽  
Vol 16 (7) ◽  
pp. 419-429 ◽  
Author(s):  
CHRISTER SANDBERG ◽  
JAN-ERIK BERG ◽  
PER ENGSTRAND
Keyword(s):  
Energy Efficiency ◽  
Specific Energy ◽  
Energy Efficient ◽  
Fiber Length ◽  
Specific Energy Consumption ◽  
Main Line ◽  
Thermomechanical Pulp ◽  
Line Production ◽  
Tensile Index ◽  
Printing Papers

Many mechanical pulping mills use low consistency (LC) refining for energy efficient fiber development. In this study, energy efficiency and pulp quality were evaluated for six processes, of which four included LC refining. We studied two different types of chip refiners – single disc (SD) and double disc (DD) – with LC refining in the main and reject lines. All process combinations have been used in the Holmen Paper Braviken mill, Sweden, to make thermomechanical pulp for printing papers. LC refining was more energy efficient than high consistency (HC) refining at certain tensile index increases in all evaluated combinations. LC refining in the main line had somewhat higher energy efficiency than did LC refining in the reject line. The type of chip refiner (DD or SD) did not affect the efficiency or pulp property development in LC refining. The process with a combination of DD chip refining and LC refining had the highest energy efficiency (tensile index at certain specific energy consumption). All processes with LC refining produced pulp with somewhat lower light scattering and fiber length than did the corresponding system with only HC refining. Thus, for printing papers, the best combination was LC refining with DD chip refining. LC refiners seem to have a narrow range in specific energy for maximum energy efficiency and a good balance between tensile index increase and fiber length reduction. Much higher specific energy was applied on reject pulp. However, the reject share was only around 30%. The LC refining specific energy, based on main line production, was around 80 kWh/air-dried metric ton (a.d. metric ton), whereas up to 180 kWh/a.d. metric ton was applied in main line.

Differences in wood decay by Heterobasidion parviporum in cloned Norway spruce (Picea abies)

2009 ◽  
Vol 39 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Y. Puentes Rodriguez ◽  
A. Zubizarreta Gerendiain ◽  
A. Pappinen ◽  
H. Peltola ◽  
P. Pulkkinen
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Wood Density ◽  
Fibre Length ◽  
Wood Decay ◽  
Wood Properties ◽  
Average Growth ◽  
Fibre Properties ◽  
The Difference ◽  
Average Wood

In forest breeding, growth has been used as the main selection trait in Norway spruce (Picea abies L. Karst.), whereas wood properties or resistance to pathogens have been taken as secondary traits. We aimed to investigate, in laboratory conditions, the rate of wood decay caused by Heterobasidion parviporum (Fr.) Niemelä & Korhonen (strains 5 and 7) in 20 Norway spruce clones. We also studied if, on average, growth, wood density, and fibre properties differed in the most and least decayed clones as well as from pith to bark. After 6 months of incubation, strain 7 effected significantly higher wood decay than strain 5 (mean 16.9% and 1.7%, respectively). The difference between the five most decayed and five least decayed clones by strain 7 was also statistically significant (P < 0.05). Moreover, regardless of clone or strain, the wood decay was highest near the pith and lowest near the bark, which is the opposite for wood density and fibre length and width. However, neither wood density nor fibre properties explained, statistically, the differences in average wood decay and decay from pith to bark. On the other hand, we could identify clones that simultaneously provided high wood quantity and relatively high wood density and low decay rate.

Fibre properties of Norway spruce of different growth rates grown under birch shelterwoods of two densities

2000 ◽  
Vol 30 (3) ◽  
pp. 487-494 ◽  
Author(s):  
Göran Bergqvist ◽  
Urban Bergsten ◽  
Bo Ahlqvist
Keyword(s):  
Growth Rate ◽  
Norway Spruce ◽  
Kraft Pulp ◽  
Coniferous Forest ◽  
Fibre Length ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Strong Negative Correlation ◽  
Fibre Properties ◽  
The Difference

The effects of birch shelterwood density (0, 300, and 600 trees/ha) and growth rate on fibre and pulp properties of Norway spruce (Picea abies (L.) Karst.) understorey (growing at 1500 trees/ha) were evaluated for a trial in the boreal coniferous forest, 58 years after establishment of the stand and 21 years after establishment of the trial. Microdensitometry was used to record variations in wood density, whereas fibre properties and kraft pulp strength properties were measured on laboratory-made batches of unbleached kraft pulp. The main conclusion of the investigation is that a birch shelterwood has only a minor influence on the wood and fibre properties of sheltered Norway spruce and that the resulting consequences for kraft pulping are moderate. Length-weighted mean fibre length was significantly affected only by growth rate. It was 1.75 mm, or 6-13% lower, for trees showing a low growth rate than for all other trees. Tensile index was already high before refining, 85-95 Nm g-1, and the increase due to beating was similar for all shelterwood densities and growth rate classes. At 2000 beating revolutions, there was a strong negative correlation between tear index and the proportion of fibres shorter than 0.20 mm. The volume of wood required to produce 1 t of kraft pulp was almost identical, 5.4 ± 0.1 m3 t-1, for sheltered and unsheltered spruce. Norway spruce growing without shelter produced more pulp per hectare in all fibre length classes, but the difference was greatest, 56-59% compared with sheltered spruce, for the longest fibres (i.e., longer than 3 mm).

Differences in fibre properties in cloned Norway spruce (Picea abies)

2008 ◽  
Vol 38 (5) ◽  
pp. 1071-1082 ◽  
Author(s):  
A. Zubizarreta Gerendiain ◽  
H. Peltola ◽  
P. Pulkkinen ◽  
R. Jaatinen ◽  
A. Pappinen
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Wood Density ◽  
Growth Traits ◽  
Fibre Length ◽  
Stem Volume ◽  
Fibre Properties ◽  
Phenotypic Correlations ◽  
Fibre Width ◽  
Selection For

In forest breeding programmes, growth has typically been used as a selection trait of prime importance in Norway spruce ( Picea abies (L.) Karst.), whereas less attention has been given to the wood and fibre characteristics. In the above context, we investigated phenotypic relationships between different fibre properties and growth and wood density traits in 20 cloned Norway spruce based on a clonal trial established in the 1970s in southeastern Finland. We found that fibre width showed, on average (2.9%), the lowest phenotypic variation followed by fibre wall thickness (3.4%), coarseness (5.5%), and fibre length (8.1%). All of the phenotypic correlations between the fibre properties were also positive (p < 0.05), ranging from moderate to strong, suggesting that selection for one trait could simultaneously affect the other traits. The phenotypic correlations, on average, were quite weak but positive between growth and fibre properties and slightly negative or weak positive between wood density and different fibre properties (p < 0.05). Individually, some of the clones showed negative correlation between growth traits and fibre length. As a result, selection for fibre properties alone could also reduce overall stem volume (or stem mass) and would not directly indicate wood density traits and vice versa.

scholarly journals Fibre development in an intensified mechanical pulping process

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Christer Sandberg
Keyword(s):  
Production Process ◽  
Size Distribution ◽  
Specific Energy ◽  
Microscopic Level ◽  
Mechanical Pulp ◽  
Fibre Properties ◽  
Conventional Process ◽  
Fibre Development ◽  
Printing Paper ◽  
High Consistency

Abstract Mechanical pulp for printing paper can be produced with a process that involve much less equipment and that require much lower specific energy compared to conventional processes. Even though common evaluation methods, e.g. handsheet testing, have shown that the pulp quality is similar for the simplified and the conventional processes, it is not known how fibre properties, at the microscopic level, is developed with the simplified process. In this mill scale study, the fibre properties attained with an “intensified” mechanical pulping process, consisting of single stage high consistency double disc refining followed by two stage low consistency refining and no reject treatment was investigated. The simplified process was compared to a process with a reject system. The simplified process rendered fibres with higher degree of fibrillation, higher share of axial splits, lower fibre wall thickness but slightly lower length than the conventional process. The fibrillar fines size distribution of the two processes was different. The conventional process generated more of small fibrillar fines which probably explains the higher tensile index at given density for that process. The results show that it is possible to simplify the production process for mechanical pulp and reduce the specific energy with over 700 kWh/adt.

MICROFIBRIL ANGLE OF THE S1 CELL WALL LAYER OF NORWAY SPRUCE COMPRESSION WOOD TRACHEIDS

IAWA Journal ◽  
2004 ◽  
Vol 25 (4) ◽  
pp. 415-423 ◽  
Author(s):  
Jonas Brändström
Keyword(s):  
Norway Spruce ◽  
Compression Wood ◽  
Microfibril Angle ◽  
Soft Rot ◽  
Wall Layer ◽  
Thermomechanical Pulp ◽  
Ultrastructural Organization ◽  
Normal Wood ◽  
Cell Wall Layer ◽  
Fracture Characteristics

The ultrastructural organization of the outer layer of the secondary wall (i.e. S1 layer) of Norway spruce (Picea abies (L.) Karst.) compression wood tracheids was investigated with emphasis on the microfibril angle. Light microscopy was used to study the orientation of soft rot cavities (viz. microfibril angle) in compression wood tracheids from macerated soft rot degraded wood blocks. In addition, surface and fracture characteristics of compression wood tracheids selected from a thermomechanical pulp were investigated using scanning electron microscopy (SEM). Results showed that the orientation of soft rot cavities varied little between tracheids and the angles were also consistent along the length of individual tracheids. The average S1 microfibril angle in two selected annual rings was 90.0° ± 2.7° and 88.9° ± 2.4° respectively. SEM observations of the compression wood tracheids from the pulp showed distinct fractures between S1 and S2 or within S1 and these fractures were oriented perpendicular to the tracheid axis. It was concluded that the microfibril angle of the S1 layer of compression wood tracheids is higher and less variable than normal wood tracheids. This is considered an adaptation for restraining the compressive forces that act on leaning conifer stems or branches.

scholarly journals Morphological, mechanical, and optical properties of cypress papers

Holzforschung ◽  
2014 ◽  
Vol 68 (8) ◽  
pp. 867-874 ◽  
Author(s):  
Ofélia Anjos ◽  
António J. A. Santos ◽  
Rogério Simões ◽  
Helena Pereira
Keyword(s):  
Light Scattering ◽  
Energy Demand ◽  
Mechanical Performance ◽  
Fibre Length ◽  
Kraft Pulping ◽  
Cupressus Lusitanica ◽  
Tear Index ◽  
Length Width ◽  
Pulp Properties ◽  
Pine Species

Abstract The pulping properties of cypress species are not known and the present paper aims to filling this gap. Namely, Cupressus lusitanica Mill., C. sempervirens L. and C. arizonica Greene have been submitted to kraft pulping and the pulp properties are compared with those of Pinus pinaster Aiton. and P. sylvestris Watereri as references. Schopper Riegler degree, density, Bekk’s smoothness, tensile index, tear index, burst index, stretch, dry zero-span strength, wet zero-span strength, brightness, opacity and light scattering coefficient have been tested. The pulp yields and delignification degrees of cypress woods were lower than those of the pine references. Fibre length, width and coarseness were statistically different between pines and cypress species and C. sempervirens pulps have corresponding data close to those of pine species. Cypress pulps can be refined much faster than pine pulps. The papers sheets of cypress fibres have, in general, lower mechanical performance than those of pine fibres. Papers from C. arizonica and C. lusitanica are similar and C. sempervirens has intermediate properties being between the other cypress and pine species. However, cypress fibres are relatively short, flexible and collapsible and can be refined with low energy demand, and thus could be incorporated into papers resulting in products with better light scattering and smoothness.

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