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Holmvall M.,SCA RandD Center | Uesaka T.,Mid Sweden University | Drolet F.,FPInnovations Paprican | Lindstrom S.B.,KTH Royal Institute of Technology
Journal of Fluids and Structures | Year: 2011

The transfer of a microscopic fluid droplet from a flat surface to a deformable stochastic fibre network is investigated. Fibre networks are generated with different levels of surface roughness, and a two-dimensional, two-phase fluid-structure model is used to simulate the fluid transfer. In simulations, the Navier-Stokes equations and the Cahn-Hilliard phase-field equations are coupled to explicitly include contact line dynamics and free surface dynamics. The compressing fibre network is modelled as moving immersed boundaries. The simulations show that the amount of transferred fluid is approximately proportional to the contact area between the fluid and the fibre network. However, areas where the fluid bridges and never actually makes contact with the substrate must be subtracted. © 2011 Elsevier Ltd.

Shallhorn P.,FPInnovations Paprican | Gurnagul N.,FPInnovations Paprican
BioResources | Year: 2010

We have developed a semi-empirical model to relate the tensile energy absorption (TEA) of paper sheets formed from high-consistency refined pulp to pulp properties, including water retention value (WRV), fibre length, and fibre curl. TEA is shown to be related to the normalized stretch (ratio of stretch to tensile strength) and the tensile strength of the pulp. Normalized stretch appears to be a function of fibre curl, whereas tensile strength for a given pulp is a function of the fibre length, fibre curl, and WRV. The manner in which these three pulp properties develop in a given refining operation determines the development of TEA.

Xu Q.,Shandong Institute of Light Industry | Xu Q.,University of New Brunswick | Qin M.,Shandong Institute of Light Industry | Ni Y.,University of New Brunswick | And 3 more authors.
Canadian Journal of Forest Research | Year: 2011

The predictions of properties for wood disc average are seldom reported, and they are important for sorting out logs based on their quality. The minimum near infrared (NIR) spectra required to predict wood disc average properties would also be of critical importance. In this study, calibration and prediction models for wood disc average properties were developed using NIR spectral data for balsam fir (Abies balsamea (L.) Mill.) and black spruce (Picea mariana (Mill.) B.S.P.) samples collected from 14 different sites across Newfoundland, Canada. The calibration was done against area-weighted average wood properties determined by SilviScan. NIR spectra were collected in 18 mm increments from the radial-longitudinal face of green and oven-dried samples. Results showed that using NIR spectra from three spots per wood strip was sufficient for the modeling and prediction for density and module of elasticity (MOE). The coefficients of determination ranged from 0.76 (MOE of green wood samples) to 0.88 (density of oven-dried wood samples). However, the microfibril angle (MFA) cannot be well predicted from either green wood or oven-dried wood NIR spectra. Our results further showed that the NIR spectra collected from oven-dried wood samples gave better calibration and prediction than those collected from green wood samples.

Keiser J.R.,Oak Ridge National Laboratory | Kish J.R.,McMaster University | Singbeil D.L.,FPInnovations Paprican
NACE - International Corrosion Conference Series | Year: 2010

With the trend towards increasing the energy efficiency of black liquor recovery boilers in North America, there is a need to utilize superheater tubes with increased corrosion resistance that will permit operation at higher temperatures and pressures. In an effort to identify alloys with improved corrosion resistance under more harsh operating conditions, a field exposure was conducted that involved the insertion of an air-cooled probe, containing six candidate alloys, into the superheater section of an operating recovery boiler. A metallographic examination, complete with corrosion scale characterization using electron microprobe spectroscopy, was conducted after a 1,000 hour exposure period. Based on the results, a ranking of alloys based on corrosion performance was obtained.

Mahmood T.,FPInnovations Paprican
Journal of Environmental Engineering | Year: 2010

Studies undertaken at two aerated stabilization basins (ASBs) treating industrial effluents showed that the benthal solids characteristics varied substantially with location in three dimensions. The top 15-30 cm layer of the deposited solids was found to be the most active biodegradation zone with relatively little activity in the deeper layers. Ammonia and phosphate were present in high concentrations throughout the benthal solids and thus are not believed to limit biological growth and its associated benthal solids degradation kinetics. The nutrient concentrations were particularly higher in the downstream cells than those in the upstream cells. Implementing a suitable strategy to recycle these nutrients could result in minimized discharge and cost savings when treating nutrient-deficient industrial wastewaters. Dewatering properties of the benthal solids also substantially varied from one cell of an ASB to another. The selection and dose optimization of the dewatering polymers should therefore be completed separately for individual cells (or major zones) within an ASB system. Insights provided in this paper could be instrumental in proposing remedies to enhance in situ degradation of benthal solids and to better design and operate ASBs treating industrial effluents. © 2010 ASCE.

Zhang H.,Tianjin University of Science and Technology | Zhang H.,University of New Brunswick | Yuan Z.,FPInnovations Paprican | Ni Y.,University of New Brunswick
Holzforschung | Year: 2011

High-yield pulp (HYP) has found wide applications in many paper grades. Usually, the strength properties of HYP must be improved and its freeness fine-tuned before sending it for paper machining, by means of refining at a low consistency, which requires energy. In this study, the possibility of avoiding refining of HYP was investigated by adding low percentages of refined and bleached wheat straw pulp (BWSP) to a HYP-containing mixture. The results show that the strength properties of a HYP and a hardwood kraft (HWKP) mixture can be improved with approximately 10% refined BWSP. In this manner, refining energy of 20 kWh t-1 is needed, and the pulp quality is improved to a similar level to that obtained from the same pulp mixture refined with an energy input of 70 kWh t-1. This approach also works for 100% HYP. The practical implication is that only a small percentage of refined BWSP is needed to improve the strength property of a HYP or HYP/HWKP mixtures, so that less refining energy is required in the low-consistency refining process. © 2011 by Walter de Gruyter Berlin New York.

Gelinas V.,FPInnovations Paprican | Vidal D.,FPInnovations Paprican
Powder Technology | Year: 2010

We have developed a direct imaging method for measuring particle shape distributions. It consists of a series of advanced automated algorithms that analyze 3D Atomic Force Microscopy (AFM) images of diluted pigment suspensions deposited onto glass cover slips. The method was applied to determine particle shape distributions of 10 different clay pigments from Brazil and Georgia, US. We found that the aspect ratio varies significantly and monotonically with particle diameter. The method gives generally lower average aspect ratios than those mentioned in previously published data, but still ranks pigments similarly. It was determined that Georgia clays generally have higher aspect ratios and broader shape distributions than Brazilian clays. This new direct automated AFM image analysis approach will be useful in pigment shape characterization and will provide important data for predicting coated paper performance. © 2010 Elsevier B.V.

Sithole B.,FPInnovations Paprican | Shirin S.,FPInnovations Paprican | Zhang X.,FPInnovations Paprican | Zhang X.,Washington State University | And 3 more authors.
BioResources | Year: 2010

Three methods for improved deresination of sulphite pulps were evaluated, namely, alkaline washing, enzyme treatment, and pulp fractionation. Alkaline washing appears to come at a high cost, because caustic is expensive and affects cellulose chain length, as indicated by lower viscosity of the pulps. Thus this is not a viable option for pulps that are sensitive to changes in viscosity. Enzyme treatment did not completely degrade the glycerides under the mill conditions used. Fibre fractionation studies showed that the fines fractions contained 8 to 13 times more residual lipophilic extractives than the whole pulps. Removing this fraction, which represents only a small percentage of the whole pulp, could reduce by about a half the amount of lipophilic extractives in the remaining pulp. Thus pulp fractionation appears to be a viable option to achieve further deresination of sulphite pulps.

Sithole B.,FPInnovations Paprican | Shirin S.,FPInnovations Paprican | Ambayec B.,FPInnovations Paprican
Journal of Wood Chemistry and Technology | Year: 2010

One of the major requirements of sulphite pulps, particularly those used in the manufacture of dissolving grades, is that their extractives content must not exceed certain levels, as specified by the customer. Since these levels are generally very low, the accuracy and reproducibility of extractives measurements can be poor, which in turn can lead to disagreements between pulp suppliers and their customers. In an effort to improve the reliability of extractives measurements, we have evaluated several methods for the determination of lipophilic extractives in sulphite pulps, using Soxhlet and Soxtec solvent extraction and various modes of drying the extracts including hot plate, infrared lamp, and freeze drying. Analysis of the extracts by size exclusion chromatography showed that a significant portion of the extracts was polymerized during the production process. Lipophilic extractives from ammonium sulphite pulps contain more polymerized matter than the extractives from the magnesium process.

Allen L.H.,FPInnovations Paprican | Gagne A.,FPInnovations Paprican
Tappi Journal | Year: 2011

The mountain pine beetle epidemic in British Columbia is leaving behind vast stands of dead pine trees to be harvested. Several years after death, when the needles have fallen off, the trees are referred to as graystage. The trees' natural defense system when attacked is to pitch out the beetles by producing large amounts of canal resin to flood the beetles' bore holes; hence, changes in wood resin (extractives) will accompany beetle attack. Increased extractives concentration has been shown in the final bleached pulp in a kraft mill pulping a large proportion of gray-stage pine wood killed by the mountain pine beetle. Similar to the wood extractives content in gray-stage pine chips, pulp extractives in gray-stage mill pulps are variable and can occasionally be high (e.g., >0.05%), likely because of the composition of the extractives in the incoming chips. Although this usually does not cause pitch problems in the pulp mill and its customer paper mills, kraft mills that sell gray-stage pulp to extractives-sensitive customers should check extractives content before shipment to make sure it is not unacceptably high.

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