Abstract: A method and system for determining trace oversize contaminant particles in a paper-making pulp employs a screen assembly having a screen housing with a screen mounted therein, and ports for introduction of aqueous pulp and rinsing and flushing fluids, and for withdrawal of screened aqueous pulp, the screen housing has no port designated for the sole purpose of removing accumulated contaminant particles from the screen housing; instead the port employed for introduction of aqueous pulp and which may also be employed for introduction of rinsing fluid to the housing, is employed as the flushing port for removal of contaminant particles.

Abstract: A novel method for the production of light-stable and process-stable lignocellulosic materials, in particular, the production of mechanical wood pulps with much improved light and process stability is described, as well as the resulting pulps of improved light and process stability and papers containing such pulps. The novel method involves the reaction of lignocellulosic materials such as bleached chemithermomechanical pulps (BCTMP) with (a) a water-soluble, fibre-reactive yellowing inhibitor possessing two or more secondary amino or ammonium (—NHR? or —HN+HR?), tertiary amino or ammonium (—NR?R? or —HN+R?R?), and/or quaternary ammonium (—N+R?R?R??) functional groups in an aqueous medium, or (b) a water-soluble, fibre-reactive hindered amine light stabilizer possessing said amino or ammonium functional groups in an alkaline peroxide bleaching medium or in an aqueous medium with a subsequent bleaching of the materials in an alkaline peroxide bleaching medium.

Abstract: Oxidized white liquor is heat treated to increase the concentration of polysulphide measured at 285 or 286 nm (PSUV) or measured at 416 nm (PSVIS) and the PSUV/PSGR or PSVIS/PSGR ratio, whereby the content of active polysulphide in the total polysulphide is increased which active polysulphide can be exploited to increase pulp yield in Kraft pulping.

Abstract: This invention provides a novel, rapid method and device for determining the relative phase retardation of different layers of a multi-layered specimen, which is related to the thicknesses of its layers and walls, and the orientations of its optical axes. An intact wood pulp fibre is a typical multi-layered birefringent specimen. This new method is based on the change of polarization of polarized light that passes through a specimen composed of birefringent layers with different optical axis orientations, such as directions of cellulosic microfibrils oriented differently in various layers of wood fibres. In particular, a novel solution is found to relate the emerging light intensity from an intact wood fibre to the incident light intensity, the wavelength of the light, and the relative phase retardations of various layers and orientations of their cellulosic microfibrils, such as fibril angle, in a circularly polarized light system.

Abstract: A method for the bleaching and brightness stabilization of lignocellulosic materials is described. The method involves the treatment of lignocellulosic materials, in particular, (a) wood pulps such as thermomechanical pulps (TMP) and chemithermomechanical pulps (CTMP), and (b) papers made from wood pulps, with a water-soluble phosphine or a phosphonium compound preferably containing at least one phosphorus hydroxyalkyl bond/linkage, for example a phosphorus hydroxymethyl bond/linkage (P—CH2OH). One example of such a water-soluble phosphine is the commercially available, tris(hydroxymethyl)phosphine (THP), P(CH2OH)3. One example of such a phosphonium compound is the commercially available, tetrakis(hydroxymethyl)phosphonium chloride (THPC), [P(CH2OH)4]Cl.

Abstract: A method is proposed for improving pulp quality at high production rates on conical disc refiners. It permits a reduction in refining intensity by enabling fibre residence time to increase by increasing consistency, while avoiding the problem of plate plugging normally associated with high discharge consistency. In practice, inlet consistency is increased by the in-feed dilution, flat zone dilution or both, but without allowing the discharge consistency to rise. Instead, the discharge consistency is controlled at a fixed optimum value by the addition of dilution water within the conical zone. The result is that residence time is increased, and refining intensity decreased, by raising the consistency in the inner region of the refining zone, while avoiding the plate plugging caused by excessive consistency in the outer region of the refining zone.

Abstract: An austenitic Ni—Cr—Fe alloy is provided as an exterior tube material for improved cracking and corrosion resistance of composite tubes used to construct the lower furnace section of kraft recovery boilers. The alloy consists of essentially, on a weight-% basis, 25-35 Cr, 5-15 Fe and 50-70 Ni, with other minor alloying elements and impurities such as are normally present in commercial alloys. This compositional range includes, as a preferred composition, the range corresponding to the commercial alloy 690 (UNS N06690).