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J-FOR Vol 2 - No 2, 2012 - Résumés d'articles techniques

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J-FOR-Vol2No2-smallCes résumés d'articles techniques ont paru dans la publication J-FOR Vol 2 - No2, 2012.
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Ultrasound-Assisted Hydrogen Peroxide Bleaching of a Softwood Thermomechanical Pulp

Eric Loranger, Marie Cantagrel, Céline Leduc, Claude Daneault

This research has evaluated the impact of ultrasound irradiation on the bleaching of TMP with hydrogen peroxide. More precisely, the influences of irradiation power, ultrasound frequency, and reaction time on pulp brightness have been examined. The results indicated that high brightness could be achieved with a dominant ultrasonic mechanical effect generated at low power (500 W) and low frequency (68 kHz) along with a relatively short bleaching time of 30 min. The reverse results occurred when higher power (e.g., 1000 W), higher frequency (e.g., 170 kHz), and longer reaction time (e.g., 90 min) were used because the chemical effect, which promotes cellulose and lignin degradation, became dominant under these conditions. Statistical analysis showed that up to 74.4% of the brightness response was accounted for by ultrasonic frequency, ultrasonic power, and reaction time with 95% confidence.

The fate of vanadium after being burned with petroleum coke in lime kilns

Xiaofei Fan, Honghi Tran, Chris Dietel

Petroleum coke (petcoke) has been burned at a number of kraft pulp mills in the southern United States as a partial substitute for natural gas and fuel oil in lime kilns. Because of the high vanadium (V) content of the petcoke, there has been some concern about the impact of V compounds on kiln and chemical recovery operations. A laboratory study has been performed to examine the fate of V in lime kilns and the chemical recovery cycle. The results suggest that V introduced with petcoke can react quickly with lime in the kiln to form calcium vanadates, mostly 3CaO•V2O5. In the slaker and causticizers, calcium vanadates react with Na2CO3 in the green liquor to form sodium vanadate (NaVO3) and lime mud (CaCO3). Because of its high solubility, NaVO3 dissolves in the liquor circulating around the chemical recovery system. As with water-soluble chloride (Cl) and potassium (K), V accumulates in the liquor cycle, reaching a steady-state concentration that is linearly proportional to the rate of V input with petcoke and the rate of mill soda loss. For a typical kraft mill where petcoke with 1500 ppm V is burned in the lime kiln at a 50% substitution rate, the steady-state V concentrations are approximately 100 ppm in white liquor and 230 ppm in as-fired black liquor dry solids. V does not accumulate in lime mud if the mud is well washed and dewatered.

The use of paper mill biotreatment residue as furnish or as a bonding agent in the manufacture of fibre-based boards

Adil Zerhouni,Talat Mahmood Ahmed Koubaa

Using paper mill effluent treatment residues as furnish or as a bonding agent for manufacturing fibre-based boards is one of the potential reuse alternatives for this material. However, thorough characterization of the material is a major requirement to develop this alternative. Key characteristics of primary sludge (PS) and secondary sludge (SS) from three pulping processes (TMP, CTMP, and Kraft) were assessed. Standard handsheets were made with PS and SS mixed in three proportions, dried at four temperature levels, and tested for various properties. It was found that morphological and chemical properties varied with the pulping process and sludge type. PS had longer fibre and lower fines content than SS. Also, PS was higher in carbohydrates while SS exhibited higher lignin content. Handsheets made from TMP sludge showed the highest specific bond strength (SBS) as compared to those made with Kraft and CTMP sludge. SBS increased with SS content and drying temperature. Therefore, incorporating SS would likely improve the internal bond strength of the produced fibreboard.

Development of pilot tissue machine at FPInnovations

Jimmy Jong,Francis Fournier,Stephan Larivière

FPInnovations' pilot paper machine running at commercial speeds was redesigned to add a tissue and towel production capability. The target tissue configuration is based on a twin-wire machine with C-wrap around a forming roll. The stock system can handle two different furnishes. A versatile multi-layer headbox, equipped with dilution and edge flow control, can provide even CD flow distribution. The tissue web is transferred from the former by a press felt to a press roll, a Yankee cylinder section, and a creping blade unit. A conveyor system transfers the fully-dried creped tissue to a dry-end reel. A series of pilot trials have demonstrated that the pilot machine produces high-quality tissue or towel which achieves the required tensile strength, stretch, bulk, softness, and absorbency properties. The machine can be used for various research and product development projects such as furnish optimization, equipment performance assessment, and evaluation of wet-dry strength chemistry, enzymes, fabrics, creping, and Yankee coatings.

Benchmarking paper machine influence on linting and piling

Joseph Aspler,Jimmy Jong,Tony Manfred

A wide range of Canadian newsprint machines were surveyed for their linting propensity using the long-established FPInnovations Lint Test (formerly the Paprican Lint Test) for image area linting and the newly developed LP (Linting and Piling) Test for non-image area linting. Results showed that although overall linting performance has been improved, there are significant differences among paper machines. A closer examination of paper machine configuration showed that linting is affected strongly by the former type, as well as by the degree of consolidation in the press section. This was especially evident for cases where similar pulp furnish is supplied to very different machines in the same mill.

Adding a biomass-fired cogeneration power plant to a natural gas processing plant

Derek McCann

Natural gas processing plants typically consume natural gas to generate steam for mechanical power and process heating use. In western Canada, these plants remove hydrogen sulphide and carbon dioxide and extract hydrocarbon liquids from the incoming raw natural gas. These plants are sometimes located remotely in Forest Management Areas. Such locations are key to the concept of installing a biomass power plant at a natural gas processing plant. Harvesting of local wood waste to supply this boiler could be economically viable.
A high-pressure biomass-fired power boiler and a back-pressure steam turbine generator would replace the duty of the natural gas-fired power boilers in the gas processing plant. The back-pressure steam turbine would exhaust into the existing steam system. Internal natural gas consumption used for steam generation would be eliminated, imported power would be reduced, and there would be a net reduction in greenhouse gas emissions.





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