Paper pulp suspension

NMR imaging techniques were applied to the measurements of velocity field in opaque systems such as tomato juice and paper pulp suspensions [58-60]. In both cases, the particle concentrations are sufficiently high that widely applied techniques such as hot film and laser Doppler anemometry could not be used. The velocity profile for a 6 % tomato juice slurry clearly showed a power-law behavior [58, 59]. Row NMR images for a 0.5 % wood pulp suspension provided direct visual of three basic types of shear flow plug flow, mixed flow and turbulent flow as mean flow rate was increased. Detailed analysis of flow NMR image is able to reveal the complex interaction between the microstructure of suspensions and the flow [60]. 

In order to carry this concept of fluidfoil impellers at a uniform velocity of discharge further, the A312 Impeller (Fig. 4) was developed and is used primarily in paper pulp suspensions. Carrying it further is the A320 Impeller (Fig. 5). The A320 has been studied particularly in the transitional area of traditional Reynolds numbers. This is shown in Fig. 6. This figure shows its performance and Reynolds numbers between 10 and 1,000. 

By varying the impeller blade dimensions variations in power per unit volume were made at a constant impeller speed. At low power per unit volumes there was a linear increase in k a which correlated with P/V with an exponent of 0.9 to 1.2. yond the breakpoint the exponent relating the P/V dependence was 0.53. In both regions the k,a dependend on the superficial gas velocity to the 0.3 power. Tnese results are similar to those reported earlier by Blakebrough and Sambamurthy (1966) and Hamer and Blakebrough (1963) obtained in smaller scale vessels also using paper pulp suspensions. Other references on the aeration of viscous non-Newtonian fermentation broth are Banks (1977) and Blanch and Bhavaraju (1976). 

Pseudoplastic fluids are the most commonly encountered non-Newtonian fluids. Examples are polymeric solutions, some polymer melts, and suspensions of paper pulps. In simple shear flow, the constitutive relation for such fluids is... 

Paper may be colored by dyeing the fibers in a water suspension by batch or continuous methods. The classic process is by batch dyeing in the beater, pulper, or stock chest. Continuous dyeing of the fibers in a water suspension is adaptive to modem paper machine processes with high production speeds in modem mills. Solutions of dyestuffs can be metered into the high density or low density pulp suspensions in continuous operation. 

Filter Aids are porous powders added in small quantities to a soln or suspension to be filtered, in order to increase the efficiency of filtration. They are useful when handling suspensions of finely divided solids or of colloidal materials. The aid should not be much. heavier than die liquids to be filtered, so that it will not settle immediately but will remain in suspension for a while. Kieselguhr and paper pulp are the most widely used filter aids. Others are sawdust, charcoal, Fuller s earth, magnesia, salt, gypsum and some activated charcoals. The charcoals act as decolorizers at the same time... 

Since n is less than unity, the apparent viscosity decreases with the deformation rate. Examples of such materials are some polymeric solutions or melts such as rubbers, cellulose acetate and napalm suspensions such as paints, mayonnaise, paper pulp, or detergent slurries and dilute suspensions of inert solids. Pseudoplastic properties of wallpaper paste account for good spreading and adhesion, and those of printing inks prevent their running at low speeds yet allow them to spread easily in high speed machines. 

Hypochlorite. Sodium hypochlorite, [CAS 7681-52-9], NaOCl, commonly in solution by (1) electrolysis of sodium chloride solution under proper conditions. (2) reaction of calcium hypochlorite suspension in water and sodium carbonate solution, and then filtering. Used (1) as a bleaching agent fa textiles and paper pulp. (2) as a disinfectant, especially fa water. (3) as an oxidizing reagent. 

The work described in this paper uses gamma rays to generate free radicals in situ in a pulp suspension. It is hoped that this proximity of radicals and chromophoric moieties in lignin will lead to enhanced bleaching and a better understanding of the bleaching and yellowing processes of TMP. 

Because the first method is not always very satisfactory from the aesthetic standpoint and because of the limitations of the second, conservators have sought to expand their repertoire with alternative procedures. One possibility which has attracted recent interest is the use of a suspension of paper fibers to fill losses in a way that is analogous to the manufacture of paper. The paper pulp to be used for repairing an art work, for instance, can be obtained by the maceration of handmade rag-fiber paper in an ordinary food blender. 

Sample Solution Fill a 100-mL porcelain crucible halffull of ashless filter paper pulp. Place 2 g of the finished catalyst, in droplet or flake form and accurately weighed, on top of the paper pulp. Transfer the crucible to a muffle furnace set at room temperature, and slowly raise the temperature to 650° so that the stearine melts into the paper, and the organic mass bums and chars slowly. Continue heating at 650° for 2 h or until the carbon is burned off. Cool, add 20 mL of hydrochloric acid, quantitatively transfer the solution or suspension into a 400-mL beaker, and carefully evaporate to dryness on a steam bath. Cool, add 20 mL of hydrochloric acid, warm to aid dissolution (catalysts containing silica will not dissolve completely), transfer into a 500-mL volumetric flask, dilute to volume with water, and mix. Allow any solids to settle, pipet a clear, 50-mL aliquot into a 400-mL beaker, and dilute to 250 mL with water. (If there is suspended matter in the volumetric flask, filter a portion through a dry, medium-speed filter paper into a dry receiver, and pipet from the receiver.)... 

A reduction in the volume of water needed at the paper machine is almost impossible because paper formation will be disturbed if the consistency of the pulp suspension becomes too high. Currently, the stock suspension (i.e., pulp and additives) in the head box of a paper machine contains 97%-99.9% water. The constraint of maintaining pulp suspension consistency means a reduction in water intake has to be realized by reusing the process water. Due to the different purposes and applications in which water is used, the water quality demands vary considerably. Membrane processes can be chosen to produce a specific water quality and are attractive alternatives to facilitate the reuse of water, either alone or combined with biological processes or other chemical and physical processes. In addition, membrane processes are an efficient way to recover raw materials, e.g., coating pigments, from effluents. 

The present thermochemical model describes the acid-base, ion exchange and solubility cbaracteristics of a homogeneous pulp suspension. The important feature of the thermodynamic multiphase approach is that it provides the possibility to incorporate specific interactions of practically unlimited number of constituents into the system. Due to its general thermodynamic basis, the multiphase method can be applied both in the fibre line processes in pulp production and in the wet end chemistry of paper-making. 

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