Displacement washing of kraft pulp cooked from a blend of hardwoods

2010 ◽  
Vol 64 (2) ◽  
Author(s):  
František Potůček ◽  
Jozef Miklík
Keyword(s):  
Kraft Pulp ◽  
Fibre Length ◽  
Morphological Characteristics ◽  
Mathematical Treatment ◽  
Alkali Lignin ◽  
Axial Dispersion Coefficient ◽  
Softwood Pulp ◽  
Washing Process ◽  
Displacement Washing ◽  
Hardwood Pulp

AbstractThe aim of this work was to investigate the displacement washing of kraft pulp manufactured from a blend of hardwoods. The experiments were carried out in a laboratory washing cell. In order to characterise the pulp fibres, the degree of freeness, kappa number, fibre length, as well as the specific volume and specific surface of swollen fibres were determined. The displacement washing process was described by displacement washing curves recorded for alkali lignin as a tracer. Mathematical treatment of the washing curves, obtained as a response to the step input signal, gave the Péclet number characterising the displacement of alkali lignin from the pulp pad. For detailed description of the displacement washing process, further parameters, such as the traditional wash yield, axial dispersion coefficient as well as the mean residence time and the space time were also evaluated. The results obtained for hardwood pulp were compared with those for softwood pulp published earlier. With respect to different chemical composition and morphological characteristics affecting both concentration of alkali lignin in mother liquor and physical properties of pulp pad, the displacement washing efficiency of hardwood pulp was found to be unambiguously greater in comparison with softwood pulp.

scholarly journals DISPLACEMENT WASHING OF KRAFT PULP WITH VARIOUS CONSISTENCY

2020 ◽  
Vol 54 (9-10) ◽  
pp. 943-952
Author(s):  
FRANTIŠEK POTUCEK ◽  
MOSTAFIZUR RAHMAN ◽  
JOZEF MIKLÍK
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Kraft Pulp ◽  
Black Liquor ◽  
Morphological Properties ◽  
Alkali Lignin ◽  
Pulp Fibre ◽  
Washing Efficiency ◽  
Displacement Washing

The paper deals with the displacement washing of kraft softwood and hardwood pulps with various consistency of the pulp fibre bed. The results obtained revealed differences between the two types of kraft pulp with various morphological properties of fibres. The washing efficiency decreased with decreasing Péclet number for both kraft pulps, but, due to lower longitudinal dispersion of the wash liquid, greater washing efficiency was achieved for the short-fibred hardwood pulp. On the other hand, the long-fibred softwood pulp exhibited lower hydraulic resistance of the pulp fibre bed. The change in pulp consistency and, similarly, the volumetric mass transfer coefficient, characterising the rate of leaching of alkali lignin from pulp fibres, did not have a significant effect on the washing efficiency. However, the mass transfer coefficient decreased with increasing specific resistance of the pulp bed. With increasing bed consistency of both softwood and hardwood pulps, as the amount of black liquor in the inter-fibre pores decreased, the difference between the space time, characterising the holding time of wash liquid, and the mean residence time of alkali lignin increased.

scholarly journals Biocatalysis of Industrial Kraft Pulps: Similarities and Differences between Hardwood and Softwood Pulps in Hydrolysis by Enzyme Complex of Penicillium verruculosum

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 536 ◽  
Author(s):  
Andrey S. Aksenov ◽  
Irina V. Tyshkunova ◽  
Daria N. Poshina ◽  
Anastasia A. Guryanova ◽  
Dmitry G. Chukhchin ◽  
...  
Keyword(s):  
Kraft Pulp ◽  
High Efficiency ◽  
Lignin Content ◽  
Enzyme Complex ◽  
Kraft Pulps ◽  
Penicillium Verruculosum ◽  
Pulp Mills ◽  
Fiber Morphology ◽  
Softwood Pulp ◽  
Hardwood Pulp

Kraft pulp enzymatic hydrolysis is a promising method of woody biomass bioconversion. The influence of composition and structure of kraft fibers on their hydrolysis efficiency was evaluated while using four substrates, unbleached hardwood pulp (UHP), unbleached softwood pulp (USP), bleached hardwood pulp (BHP), and bleached softwood pulp (BSP). Hydrolysis was carried out with Penicillium verruculosum enzyme complex at a dosage of 10 filter paper units (FPU)/g pulp. The changes in fiber morphology and structure were visualized while using optical and electron microscopy. Fiber cutting and swelling and quick xylan destruction were the main processes at the beginning of hydrolysis. The negative effect of lignin content was more pronounced for USP. Drying decreased the sugar yield of dissolved hydrolysis products for all kraft pulps. Fiber morphology, different xylan and mannan content, and hemicelluloses localization in kraft fibers deeply affected the hydrolyzability of bleached pulps. The introduction of additional xylobiase, mannanase, and cellobiohydrolase activities to enzyme mixture will further improve the hydrolysis of bleached pulps. A high efficiency of never-dried bleached pulp bioconversion was shown. At 10% substrate concentration, hydrolysates with more than 50 g/L sugar concentration were obtained. The bioconversion of never-dried BHP and BSP could be integrated into working kraft pulp mills.

From biorefineries to bioproducts: conversion of pretreated pulp from biorefining streams to lignocellulose nanofibers

TAPPI Journal ◽  
2019 ◽  
Vol 18 (4) ◽  
pp. 233-241
Author(s):  
CHENGGUI SUN ◽  
RICHARD CHANDRA ◽  
YAMAN BOLUK
Keyword(s):  
Energy Consumption ◽  
Enzymatic Hydrolysis ◽  
Rheological Behavior ◽  
Material Basis ◽  
Softwood Pulp ◽  
Energy Consumptions ◽  
Hardwood Pulp ◽  
The Stability ◽  
Lignocellulose Nanofibers

This study investigates the use of pretreatment and enzymatic hydrolysis side streams and conversion to lignocellulose nanofibers. We used a steam-exploded and partial enzymatic hydrolyzed hardwood pulp and an organosolv pretreated softwood pulp to prepare lignocellulose nanofibers (LCNF) via microfluidization. The energies applied on fibrillation were estimated to examine the energy consumption levels of LCNF production. The energy consumptions of the fibrillation processes of the hardwood LCNF production and the softwood LCNF production were about 7040-14080 kWh/ton and 4640 kWh/ton on a dry material basis, respectively. The morphology and dimension of developed hardwood and softwood LCNFs and the stability and rheological behavior of their suspensions were investigated and are discussed.

scholarly journals Alkali Extraction of Kraft Pulp Fibers: Influence on Fiber and Fluff Pulp Properties

2012 ◽  
Vol 7 (2) ◽  
pp. 155892501200700 ◽  
Author(s):  
Kristoffer Lund ◽  
Karin Sjöström ◽  
Harald Brelid
Keyword(s):  
Kraft Pulp ◽  
Pulp Fibers ◽  
Fiber Network ◽  
Alkali Extraction ◽  
Flexible Fiber ◽  
Softwood Pulp ◽  
Softwood Kraft Pulp ◽  
Patent Literature ◽  
Network Strength ◽  
Birch Kraft Pulp

The importance of hemicelluloses for the papermaking properties of pulp fibers is well documented. In the patent literature, it can be seen that there is also an interest in this type of modification of pulp fibers for use in absorption products. In this study, a Scandinavian softwood kraft pulp and a birch kraft pulp were alkali extracted at 3 different concentrations of NaOH (2%, 4% and 8% NaOH in the suspension). The alkali extraction removed a large part of the hemicelluloses from the pulp fibers and decreased the content of the charged groups. After extraction, the pulps were dried in the form of sheets (approx. 600 g/m2). The alkali extracted pulp fibers exhibited a greater decrease in swelling when re-wetted than untreated pulp. A significant increase in the curl index after extraction with 4% and 8% NaOH was also noted. The tensile strength index of the formed sheets increased at the lowest concentration of NaOH and, at the higher concentrations, a decrease was observed. The pulp sheets were dry defibrated at different defibration intensities and the performance of the resulting pulps in fluff pulp applications was studied. The air-laid fiber networks of softwood pulp fibers showed higher network strength than the networks of birch pulps. The birch pulp extracted at the highest alkali level tended to give the highest network strength. The results from the network strength tests also indicated that the increased curl of the fibers from the softwood pulp extracted at the highest alkali level rendered a more flexible fiber network. In water absorption tests, the alkali treated softwood fibers tended to give networks with a somewhat enhanced water holding capacity under pressure.

Xylanase prebleaching of fractions of Douglas-fir kraft pulp of different fibre length

1996 ◽  
Vol 46 (4) ◽  
pp. 319-326
Author(s):  
S. D. Mansfield ◽  
K. K. Y. Wong ◽  
E. de Jong ◽  
J. N. Saddler
Keyword(s):  
Kraft Pulp ◽  
Fibre Length ◽  
Douglas Fir

scholarly journals Canadian pulp fibre morphology: Superiority and considerations for end use potential

2009 ◽  
Vol 85 (3) ◽  
pp. 401-408 ◽  
Author(s):  
Paul Watson ◽  
Michael Bradley
Keyword(s):  
Kraft Pulp ◽  
Research Effort ◽  
Fibre Length ◽  
Fibre Strength ◽  
Technical Vision ◽  
Softwood Kraft Pulp ◽  
Physical Attributes ◽  
Morphological Differences ◽  
End Use ◽  
Fibre Morphology

Four physical attributes of fibres confer the end use potential of a pulp, namely fibre length, fibre coarseness, fibre strength and uniformity. Long, slender, fine fibred pulps, which are low in thick-walled summerwood content, provide superior reinforcement strength. The natural species endowment that Canada enjoys can, when accompanied by superior operational performance and technical vision, result in significant advantages for strategically focused companies and their customers. Factor and multivariate analysis of more than 60 industrial pulp samples confirm that on the basis of fundamental morphological differences, Canadian pulps exhibit clear superiority. Canadian northern bleached softwood kraft pulp is the undoubted industry leader, yet unrealized potential still exists, and additional research effort is required, to maintain this market position. Key words: kraft pulp, softwood, fibre morphology, intrinsic properties, length, coarseness, fibre strength, tensile strength, biogeoclimatic zone, factor analysis, reinforcement, premium reinforcement pulp, PRP, refining

Kraft Pulping of Young Trembling Aspen from Manitoba

1973 ◽  
Vol 3 (3) ◽  
pp. 359-366 ◽  
Author(s):  
I. E. Bella ◽  
K. Hunt
Keyword(s):  
Specific Gravity ◽  
Kraft Pulp ◽  
Gravity Data ◽  
Tree Height ◽  
Kraft Pulping ◽  
Trembling Aspen ◽  
Softwood Pulp ◽  
Breaking Length ◽  
Pulp Strength

The unscreened kraft pulp yields at permanganate No. 14 for 7-, 13-, and 22-year-old trembling aspen (Populustremuloides Michx.) trees from Manitoba for effective alkali applications of 14% were 56.2, 55.7, and 54.8% (o.d. wood), respectively. Specific gravity data for green and ovendry wood are presented, but no relationship with tree height could be established. Pulp strength values from the 7-, 13-, and 22-year-old aspen were, respectively, 60, 67, and 65 for tear factor; 67, 71, and 72 for burst factor; and 10.1, 10.4, and 10.7 (km) for breaking length, respectively. These data indicate that trees of any of the three ages will make a kraft pulp comparable in yield and strength to commercial hardwood–softwood pulp.

scholarly journals EFFECT OF CHITOSAN ADDITION DURING PAPER-MAKING ON AGEING STABILITY OF DOCUMENT PAPER

2021 ◽  
Vol 55 (9-10) ◽  
pp. 1083-1094
Author(s):  
DIMITRINA TODOROVA ◽  
◽  
VESKA LASHEVA ◽  
Keyword(s):  
Chitosan Solution ◽  
Thermal Ageing ◽  
Paper Strength ◽  
Aluminium Sulphate ◽  
Paper Properties ◽  
Hygroscopic Properties ◽  
Complex Evaluation ◽  
Softwood Pulp ◽  
Negative Effect ◽  
Hardwood Pulp

The aim of the present work has been to study the influence of chitosan addition into the composition of paper intended for documents on its ageing stability, with a view of enhancing the resistance of paper strength and optical properties over time. The chitosan solution was added during the formation of the paper sheets in various amounts: 0.2%, 1% and 2% o.d.f. Paper samples of different fibrous compositions were prepared from bleached sulphate softwood pulp (BSWP) and bleached sulphate hardwood pulp (BHWP) in the following ratios: 50% BSWP:50% BHWP, 80% BSWP:20% BHWP, 100% BSWP and 100% BHWP. Then, paper samples were subjected to accelerated thermal ageing for 24 hours at 105 °C. It was found that the use of chitosan as additive in the composition of bleached cellulose paper samples led to improved strength and hygroscopic properties. The study showed that chitosan could be used in the production of kraft document papers comprising aluminium sulphate, as the presence of aluminium sulphate had no negative effect on the action of the biopolymer. Regarding the complex evaluation of the properties of the obtained papers, it could be summarized that, for the studied fibrous compositions, the optimum amount of the additive was 1% chitosan for a fibrous composition of 50% bleached softwood pulp and 50% bleached hardwood cellulose. Therefore, preparing document paper with the addition of chitosan is a convenient procedure to enhance a number of paper properties, even after the ageing process.

scholarly journals Papermaking Using Willow (Salix dasiclados) as a Hardwood Source – A Handsheet and Pilot Paper Machine Study

2019 ◽  
pp. 1-16 ◽  
Author(s):  
Klaus Dölle
Keyword(s):  
Kraft Pulp ◽  
Paper Machine ◽  
Paper Production ◽  
Pulp Fibre ◽  
Recycled Pulp ◽  
Tear Index ◽  
Pulp Fibres ◽  
Hardwood Pulp ◽  
Recycled Fibres

This laboratory handsheet and Fourdrinier pilot paper machine study examine the suitability of willow as a commercial hardwood pulp replacement including utilizing recycled pulp for paper production. The hand sheet study contains 16 different and the pilot paper machine study eight different furnish mixtures. For both studies, the base sheet consists of a 40% softwood and 60% hardwood commercial pulp mixture, followed by replacing the hardwood with bleached willow Kraft pulp. Deinked pulp, as recycled fibres, at 5% increments up to 100% for the handsheet study and at 10%, 20%, 30%, 50%, 70% and 90% for the pilot paper machine study is added to the base pulp mixture. Both the handsheet and the FPPM study revealed that willow Kraft pulp can replace commercial hardwood pulp fibres.  Basis weight, calliper and stiffness as related properties showed comparable results for the handsheet study. Willow Kraft fibres tend to be bulkier and denser than the used hardwood fibres. Tensile and tear index show comparable properties for the handsheet and pilot paper machine study, except for the 50%, 70% and 90% DIP containing paper sheets. Porosity values for the hansheet study showed lower results than the base sheet, whereas the FPPM study showed higher results except for the 70% and 90% DIP containing handsheet. Comparable results are shown for opacity. Brightness levels were significantly lower due to the lower brightness of the manufactured willow Kraft and deinked pulp fibre furnish. Despite the opportunity of replacing commercial hardwood with willow, more research needed to optimize willow into pulp fibres and preparation of the fibres for papermaking.

Ozone-enhanced bleaching of softwood kraft pulp

TAPPI Journal ◽  
2010 ◽  
Vol 9 (8) ◽  
pp. 16-23 ◽  
Author(s):  
JEAN-CHRISTOPHE HOSTACHY
Keyword(s):  
Capital Investment ◽  
Kraft Pulp ◽  
Operating Cost ◽  
Pulp Mill ◽  
Economic Benefits ◽  
Variable Cost ◽  
Pulp Mills ◽  
Pulp Bleaching ◽  
Softwood Kraft Pulp ◽  
Hardwood Pulp

By using ozone in their bleaching processes, many hardwood pulp mills in various parts of the world have improved product quality and their environmental and process performance, and reduced operating costs to increase competitiveness. The challenge for softwood pulp is to rethink the use of ozone according to their specific requirements. This paper summarizes results obtained using ozone bleaching on softwood (Pinus radiata) kraft pulp, for which the brightening ability of limited ozone dosages can enhance the economic benefits without impairing pulp quality. This work evaluated the chemical justification to use ozone at the end of the bleaching sequence and the effect on pulp quality, and considered the practical consequences of this new option. Special attention was given to the economic and technical aspects, including investment cost, variable cost, and process implementation. Ozone was shown to be the ideal complement of chlorine dioxide for final pulp bleaching. Both chemicals can easily be combined at the end of the bleaching sequence. Taking into account pulp mill capacity, capital investment, and total operating cost, the financial savings were calculated to be in the range of EUR 5 million (USD 6 million) per year, with a payback period of about 1.5 years.

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