Abstracts

» Abstracts of Some Interesting Articles

¤ Sillanpaa, Mervi K. …et. al. : Real Wash Loss Compounds In Peroxide Bleaching of Softwood Kraft Pulp, APPITA Journal, September (2003), 56; 5, Page No. 397-400

Abstract : The effects of different chemical compounds on the bleaching performance of softwood kraft pulp in the peroxide stage were investigated in the laboratory. The aim of this study was to find out the real' wash loss compound or compounds that affect the quality of pulp (brightness, viscosity, Kappa number) in the preceding peroxide stage. Different compounds, occurring in wash liquors and bleaching filtrates, were added to the pulp suspension before bleaching experiments. These studied compounds were formic acid, acetic acid, methanol, glycolic acid, glucose, lignin, lactic acid and succinic acid. Results indicated that lignin and glucose had an impact on the bleaching response, decreasing brightness and increasing Kappa number. Other tested compounds, such as organic acids, had no effect on the bleaching response although these components can significantly contribute to COD in the filtrates. Instead of measuring COD, as is current practice, it would be better to measure lignin concentrations in the liquid part of the pulp suspension to estimate the actual wash loss at the end of ECF bleaching.

¤ Bristow, Ray : Induction Motors and their Controllers as part of Energy Reduction Strategies within the Pulp & Paper Industry, Paper Tech-nology, September (2003), 44; 7, Page No. 25-35

Abstract : By any measure, the pulp and paper industry is an intensive user of energy. Although most of the energy consumed is in the form of a heat, a considerable amount is used to provide rotating mechanical power to the drive shafts of pumps, fans, rolls and many other items on a modern papermaking line. Almost without exception, this mechanical energy is derived from electricity which is converted into rotating mechanical energy at its paint of use. By far the most frequently used device in the conversion process is the polyphase induction motor. In the paper industry, oversized, or under-loaded, motors are rife-they are largely selected by the OEM to meet the functional requirement of the specification and without regard to subsequent operating costs. In the long term, this is very expensive to a paper mill because the cost of energy for outweighs the capital cost of a motor - even in co-generation schemes. Some 90-95% of the cost of ownership of operating a motor for 10 years is the cost of the electrical energy needed to run it. Indeed the cost of energy used by a motor running continuously at full power, equals the capital cost the motor - of any size - within 20 to 40 days.

¤ He, Jihong … Et. Al.: A New Approach for Quantitative Analysis of Paper Structure at the Fibre Level, APPITA Journal, September (2003), 56; 5, Page No. 366-370

Abstract : This paper describes and demonstrates a new method for measuring fibre cross-sectional dimensions, fibre collapse, fibre orientation and relative fibre positions in sheets of paper embedded in resin. Confocal laser scanning microscopy (CLSM) is used to acquire images of paper cross-sections in a manner that avoids artifacts from sample preparation. The measurements of fibre dimensions are validated by comparing the results measured in paper with those measured on freely dried fibres on glass slides. The measurement of fibre orientation is validated by comparing the measured results with a theoretical average value of orientation in a random sheet. A new term, 'fibre fill factor, is define and measured with the new technique. The utility of the fill factor for describing the degree of collapse of individual fibres in a sheet is discussed.

¤ Pelach, M. Angels …et. al : The Use of Cationic Surfactants to Enhance the Deinking of Coated Fine Papers, APPITA Journal, September (2003), 56; 5, Page No. 351-354

Abstract : A deinking process is based on two fundamental operations: defibering and deinking. Defibering depends on added chemicals and shear stress applied to a wastepaper suspension. The defibering operation and the added chemicals control ink removal. In this study disintegration stock concentration, rotor speed and disintegration time are used to optimise defibering to a Somerville index

Geng, X., Li Kalichang ., Irina A., Hataeva,: Effects of two cellobiohydrolases, CbhA and CelK from Clostridium thermocellum on deinking of recycled Mixed Office Paper, Progress in Paper Recycling (May 2003) 12;3