Pulp Consistency Research Articles

アルカリ‐ジオキサンパルプ化 ＩＩ オゾン及び過酸化水素による漂白

Alkali-dioxane pulps prepared from oak wood were bleached in two stages with ozone and hydrogen peroxide, and the influence of bleaching conditions on pulp properties was studied. The results are summarized as follows.1) The pulps showed reasonable properties after ozone bleaching under the conditions of 50 % of pulp consistency and pH 2. The sheet strengths of ozone bleached pulp decreased rapidly over 3% ozone consumption.2) The optimum brightness and viscosity were obtained after peroxide bleaching under following conditions : hydrogen peroxide 2%, pulp consistency 20%, temperature 70°C, time 2 hr, pH 11.3) In comparison with CEDED bleached kraft pulp, alkali-dioxane pulp bleached with ozone and hydrogen peroxide had better brightness stability and beatability, while its sheet strengths were somewhat inferior.

Pulp consistency measurement and control system

The consistency measurement of the pulp is not completely solved problem in pulp and paper industry. Pulp is not a newtonian fluid and thus several different problems exist. For example flow and temperature variations of the pulp disturb most measuring systems. Moreover the quality of the pulp and the range of the pulp consistency measurement have an effect to the linearity of the measuring devices.Pulp diluting is usually a control problem of a zero capacity process. There is a dead time between the supplying point of the diluting water and the measurement point of the consistency. Thus the exact and stable control of the consistency is quite a difficult task with traditional analog devices.An industrial compensated measurement and control system for pulp consistency is presented, where the effects of temperature, flow and mass quality variations are compensated. The control strategy is based on the feedforward control and on the Dahlin algorithm. Moreover an advanced system, where the consistency is estimated with a Kalman filter, is described.

Effect of Beating Condition on Shrinkage during Drying

In general, beating can be classified to two groups which are called “wet beating” and “free beating”. This report deals with the effect of beating conditions on shrinkage of the sheets during drying. Hardwood and softwood bleached sulfate pulps were beaten with a Niagara beater under various conditions of temperature, pulp consistency and load during beating Handsheets made from beaten furnishes were compared with each other in regard to sheet shrinkage during drying and dimensional stability of the sheet. These results obtained are summerized as follows : 1) When handsheets were prepared from unbeaten or slightly beaten pulps, shrinkage of the sheets from hardwood pulp was smaller than that from softwood pulp. As beating was greatly exceeded, shrinkage of the sheets from hardwood pulp increased more evidently than that from softwood pulp.2) As compared with the sheets made from wet beaten pulps, the sheets from freely beaten pulps shrank more greatly during drying, but showed less stress during its shrinking.3) Shrinkage during drying was affected greatly by length of the fiber which composed the sheets. That is, sheets composed of comparablly long fibers showed larger shrinking stress but less shrinkage during drying.4) Pulps beaten freely were shorter in length of fiber than wet beaten pulps of comparable C. S. F. so the sheets made from freely beaten pulps were more unstable in dimensional stabilitythan those from wet beaten pulps. With regard to light scattering coefficient and another physical properties, the difference between the sheets dried with restriction to shrink and those without it was more evident in freely beaten pulp.

過酢酸気相標白したＢＳＰの強度特性について

In order to elucidate the mechanical properties of bleached sulfite pulp, NUSP and LUSP were bleached with peracetic acid (PA) in vapor phase under the following conditions : Chemicals addition on pulp, 10 to 32% ; DAISERU stabilizer addition on pulp, 0.018% ; pulp consistency, 33% ; temperature, 90°C ; pH 4 ; bleaching time, 60 min for NUSP and 30 min for LUSP. Viscosity of BSP thus obtained was 4 to 16 cp, and the brightness was 86 to 94% GE. Comparison between the sheet strengths and pentosan content or viscosity of BSP prepared under above conditions was also carried out. The results are summarized as follows : 1. NUSP and LUSP were more easily bleached than NUKP or LUK1 by PA-bleaching in vapor phase. Brightness of both SP, bleached with PA in vapor phase, was 5 to 8% GE higher than that of multistage-bleached SP at the equal pulp viscosity. 2. The decrease in tensile strengh, burst factor, tear factor and folding end. of linter pulp during PA- or multistage-bleaching was attributed to decrease viscosity of the pulp in a cupri ethylenediamine solution. On the other hand, sheet strengths of PA- or multistage-beached NSP and LSP at the equal freeness increased proportionally with increasing pentosan content in the bleached pulps, except folding end. of multistage-bleached NSP sheet. 3. The ellution pattern of gel filtration of hemicellulose, isolated from NSP with 5% KOH solution, was found to unchange hardly during multistage- or PA-bleaching in vapor phase. Whereas hemicellulose in LSP was partially degraded to lower molecular part during both bleaching. The lower molecular content of hemicellose in the PA-bleached LSP was more than that in the multistage-bleached pulp. 4. Tensile strength and burst factor of PA- or multistage-bleached pulp increased proportionally with increasing sheet density of each bleached pulp at the equal f reeness. The sheet strengths of PA- or multistage bleached KP were stronger than that of BSP at the equal sheet density. From the facts described above, it is assumed that the decrease of DP of polysaccharides in BSP is reduced the sheet strengths of the BP, and also, that the strengths are greater affected by the amounts of pentosan and lower molecular part of hemicellulose in the pulps.

Methodes Optiques Appliquees Au Controle En Continu De La Consistance Et Du Degre D'Engraissement Des Pates A Papier

The optical methods for the control of pulp consistency and refining examined in this paper are based on simple as well as on multiple diffusion of light. A theoretical study according to these two concepts leads to a design of the apparatus whose characteristics are described later on. The analysis of particle diffraction permits the control of refining and the visualization of the fibrous suspension. Turbidimeters are based on transmitted flux measurement and reflectometers on multiple diffusion reflection flux measurement. Instructions are given about the apparatus choice and location. Some examples show the sensitiveness and standardization of those optical sensors as well as the influence on the measurement of consistency variables such as refining degree, fiber composition and coloration. The authors give results of tests carried out on an industrial scale with a diffuse reflection optical sensor used to control consistency in the head circuits of a papermachine, on thickened pulp, in the headbox and in white waters. There exist very good relations between the consistency optical signal in the headbox and the basis weight of paper measured with a β-gauge at the end of the machine. Other examples are given forthe control of the consistency profile in the vat of a board-machine cylinder mould as well as for the control of consistency in nonwovens manufacture. Les méthodes optiques de contrôle de la concentration et du raffinage des pates à pâpier examinées dans cette étude sont basées sur la diffusion simple ainsi que la diffusion multiple de la lumière. Une étude théorique suivant ces deux principes permet de définir les appareils dont on présente ensuite les caractéristiques. L'analyse de la diffraction des particules permet le contrôle du raffinage ainsi que la visualisation de la suspension; les turbidimètres sont basés sur la mesure du flux transmis et les réflectomètres sur la mesure du flux rétrodiffusé en diffusion multiple. Des recommandations sont données pour le choix des appareils et leur emplacement. Des exemples montrent la sensibilité et l'étalonnage de ces capteurs optiques ainsi que l'influence sur la mesure de la concentration de paramètres tels que le degré de raffinage, la composition fibreuse et la coloration. On présente les résultats d'essais sur des circuits industriels avec un capteur optique à rétrofiffusion utilisé pour contrôler la concentration dans les circuits de tête d'une machine à papier; sur la pâte épaisse, en caisse de tète et dans les eaux blanches; d'excellentes corrélations existent entre le signal optique de conentration dans la caisse de tete ainsi que le grammage du papier mesuré avec une jauge β en bout de machine. D'autres exemples sont donnés pour le contrôle du profil de la concentration dans la cuve d'une forme ronde d'une machine à carton ainsi que pour le contrôle de la concentration dans la fabrication des tissus non tisses.

Measurement of Pulp Consistency by Ultrasonic Attenuation

Measurement of the attenuation of acoustic waves is suggested as a method for deducing the consistency of thin suspensions of papermaking fibres. Results obtained by a pulse method in the frequency range 1 to 6 MHz show that attenuation increases linearly with consistency. The measurements are in the range 0 to 2.5 wt. %, a range wh ich is not adequately covered by other methods of consistency measurement. The specific attenuation varies between samples. Values of the order of 20 dB/wt.% metre at 1 MHz are reported, increasing roughly as the square of frequency. The effects of temperature, wetness, additives, and entrained air are discussed.

The Automatic Recording Regulator which measures the Brightness of Pulp Suspension

The apparatus so far developed tend to have a defect not to give a true brightness of pulp in suspension because of the influence of the changes in the pulp consistency, the rate of flow and the variation of freeness in the beating processes etc. Thus, these apparatuses seem to be little useful.In this report, the principle and structure of the new successful apparatus which is capable of measuring a true brightness of pulp, the influences mentioned above beeing eliminated, is described, and also the experimental results obtained by using this apparatus, are given.It is characterized by employing not only the reflectance of light from the pulp suspension, but also the compensation light.It is devised so as to determine a true brightness without beeing influenced by changes as in consistency and so forth, since the compensation light is established so that both the amount of light transmission of the compensation light and of the reflected light from the light source are subject to changes and simultaneously the sum of them become constant, when-ever changes occur in the consistency of pulp.It is also devised so as to give in variable accuracy by employing the optical automatic balancing method which excludes such factors as the variation of voltage of the lamp of light source, the deterioration of luminous intensity and the change in the sensitivity of the receiving and amplification parts.The sensitivity of the apparatus is in a range of ±0.1% in the terms of the brightness of pulp, and the change caused by the elapsed time is within 0.1%.The total accuray is less than ±0.1% as converted to the brightness obtained by the Hunter Reflectometer, under the best condition.This apparatus is set in a certain position after the addition of a bleaching agent, and is much effective for regulating the amount of bleaching agents in the bleaching sequences.

Effect on the Concentration of Alkaline Solution in the Hot Alkaline Refining

The hot alkaline refining of prechlorinated sulphite pulp was studied with the various concentrations of alkaline solutions. The results are as follows : 1) If an equal amount of sodium hydroxide based on moisture-free pulp is used in the treatments, higher refining effect is obtained with increase in pulp consistency.2) The refining reaction scarcely goes on, when the concentration of sodium hydroxide solution is reduced to 0.05% or less on the course of hot alkaline treatment.3) A certain correlation seems to exist between the yield and the alpha cellulose content of refined pulp, and the amount of dissolving from pulp is a function of the amount of alkali consumed in the treatment. Therefore, the highest alpha cellulose content of pulp, expected within a range of adopted conditions, may be determined by the amount of sodium hydroxide based on moisture-free pulp using in the hot alkaline refining.4) The velocity of refining reaction during the hot alkaline treatment is influenced by the amount of remained pulp and the concentration of alkaline solution.5) The higher the concentration of alkaline solution adopted, the quicker the reaction takes place, and the velocity does not reduce to the corresponding level, even if the alkali concentration falls down on the course of refining. This is due to the fact that the structure of cellulose fiber is loosened by the higher alkaline solution at the beginning of treatment.

EFFECT OF SODIUM ALGINATE AND C. M. C. ON THE DEFLOCCULATION OF FIBER SUSPENSION AND UNIFORMITY OF FORMATION OF THE RESULTANT PAPER (I)

In order to investigate systematically the effect of sodium alginate and C. M. C. as the paper making mucilage the degree of deflocculation of the fiber suspension was measured statically by means of “the time of the flocculation method, ” at the constant pulp consistency of 0.1% and in varying concentration of these additives having various degrees of polymerization and etherification.The results obtained are as follows.(1) When additives are used in the same concentration range those giving higher viscosity to the solution are found to have more great deflocculating effect on fiber suspension.(2) When additives of the same degree of etherification, but different in their degree of polymerization, are used in the same viscosity range those of the higher degree of polymerization are found to be more effective in deflocculating the fiber suspension.(3) When additives of the same degree of polymerization, but different in their degree of etherification, are used in the same viscosity range those of the lower degree of etherification are found to be more effective.

ON THE CAPACITY OF PULP PUMP

Making use of diagram on capacity of pulp pump, the writer has explained the relations between pulp consistency, pump efficiency, delivery capacity and power required.