Abstract: Chemical cellulose pulp is made from sawdust utilizing a static down-flow retention vessel. By adding steam and cooking liquor to a flow of sawdust a heated slurry, at a cooking temperature of about 250-350° F., is produced. The heated slurry is, at superatmospheric pressure, moved downwardly in the static down-flow retention vessel while cooking temperature is maintained, for a time period of about 0.5-6 (preferably 1 to 3) hours, the slurry having a consistency of about 5-30%. At superatmospheric pressure, without significant reduction in pressure from the retention vessel, the slurry is cooled to well below cooking temperature by diffusing cooling liquid through it, as in a conventional pressure diffuser. The discharge from the retention vessel is preferably substantially solely gravity action (e.g. using a discharge with single convergence and side relief).

Abstract: In a method and apparatus for treating pulp, a peroxide treatment of chemical pulp, i.e., both sulphite pulp and kraft pulp, is used to quickly reduce the Kappa number of the pulp. The method involves treating a chemical pulp with at least hydrogen peroxide or its equivalent, the kappa number of which chemical pulp has been brought to a level below 20 by either at least cooking or cooking and delignifying. The pulp is treated in a fast alkaline or neutral peroxide stage (Pk) (e.g. a small reactor having a volume of, or proportional to, less than about 90 cubic meters for 1500 tons per day pulp treatment) to reduce the kappa number by 1-10 units, and preferably by 3-7 kappa units, in which treatment the reaction time is less than 10 minutes, and is preferably less than 5 minutes. The pulp is then transferred substantially without intermediate washing of any type to a bleaching tower, and then bleached further in an acidic bleaching step (e.g. a D or Z step) in the bleaching tower.

Abstract: The combination of low residence time (R) with high saturation pre-heat temperature/pressure (T) followed by high speed disc refining (S), is utilized in both primary and secondary refining stages. This use of the RTS process in both primary and secondary refining stages, can be accomplished in one embodiment, where the primary refining is performed in a first disc refiner and the secondary refining is performed in a distinct second disc refiner. In a particularly cost-effective second embodiment the primary and secondary refining are performed within a single refining machine having distinct primary and secondary refining zones which are fluidly connected in series.

Abstract: Paper and absorbent products having reduced pitch content and enhanced properties, including increased tensile index, tear index, burst index, Scott Bond, smoothness, and stiffness. Further, pulps of the invention, although having slightly reduced brightness, are more responsive to bleach chemicals thereby permitting the use of less chemicals to achieve a specific brightness. The products are produced by a process that includes extracting wood particulates with a solvent for naturally-occurring volatile organic compounds and pitch. The extracted wood particulates are then pulped and formed into paper and absorbent products with enhanced properties. Due to the extraction of volatile organic compounds, the pulping and paperforming stages of the process are substantially free of emissions of volatile organic compounds that occur naturally in wood. Moreover, the extraction of pitch reduces or eliminates pitch fouling of equipment and permits the production of paper products of enhanced qualities.

Abstract: A method and apparatus for bleaching medium consistency pulp with ozone using at least 2 fluidizing mixers to mix ozone and carrier gas into the pulp. The method is particularly applicable when the volume of the bleaching gas is larger than the volume used in conventional ozone bleaching, e.g. 2 m3/adt.

Abstract: Controlling the velocity of a jet of foamed furnish leaving the slice of a pressurized headbox of a paper or a tissue making machine by measuring the density and pressure of a flow of foamed furnish provided by a pump to estimate an atmospheric pressure air content, measuring the pressure of the foamed furnish in the headbox, using the estimated atmospheric pressure air content and the measured pressure in the headbox to estimate the current velocity of said jet of foamed furnish, comparing the estimated current velocity with a target velocity and controlling the pump to move the estimated and target velocities closer to each other. An alternate embodiment controls jet velocity on the basis of comparing estimated and target headbox pressures.

Abstract: A method is provided for improving causticizing efficiency in the conventional lime recausticization portion of an alkaline pulping process. Such processes are commonly used in the pulping and bleaching of wood and non-wood cellulose fiber materials. The method of this invention comprises reacting an aqueous solution of sodium carbonate with lime to produce sodium hydroxide (causticization) in the presence of borate in order to improve the causticization reaction efficiency. Borate is added in an amount sufficient to provide a boron to sodium (B/Na) molar ratio in the range of between about 0.001:1 and 0.4:1, and preferably in the range of between about 0.01:1 and 0.3:1, which results in an increased causticization efficiency of up to 8% over the reaction efficiency obtained in the absence of borate.

Abstract: A process for production of chemical fibrous pulp for making paper, paperboard and other fibrous products from herbaceous plants, such as kenaf. Pulp from the herbaceous plant is made by a process which involves densification of pieces of all or part of the plants; i.e., both the core and the stalk or just the core portion, into cubes or pellets having a density ranging from about 15 to about 70 lbs/ft3, preferably from about 25 to about 50 lbs/ft3, which are then chemically digested to produce a fibrous pulp. The densified cubes or pellets may be digested alone or together with conventional wood chips. A principal advantage of the invention is that the densified cubes or pellets exhibit significantly better yield and strength after treatment by conventional chemical pulping methods as compared with the undensified material, enabling more efficient and economical use of this material to supplement limited supplies of conventional hardwood and softwood pulp sources.

Abstract: A process for producing fibrous materials for the manufacture of cellulose, paper or wood materials by using at least one dicarboxylic acid dialkyl ester and/or a copolymer of polyester-polyether and/or fatty acid polyol monopolyester, dipolyester, tripolyester and or higher polyester. Fibrous materials with an improved quality and higher yield are thus produced.

Abstract: An aqueous alkaline slurry of cellulose pulp is bleached with oxygen or peroxide by using a compound represented by general formula (1), (2) or (3) as a bleaching assistant: R1—O—[(C2H4O)m/(AO)n]—H  (1) R2—O—[(C2H4O)m/(AO)p]—(AO)q—H  (2) (R3)t—X—[(C2H4O)m/(AO)p]—(AO)r—H  (3) where R1 stands for a branched alkyl group having 6 to 12 carbon atoms, m stands for an average added mol number of 4 to 15, A stands for a propylene, butylene or phenylethylene group, n stands for an average added mol number of 0 to 4, the addition shown in [ ] is in a random or block form, R2 stands for a linear or branched alkyl group having 6 to 12 carbon atoms, p stands for an average added mol number of 0 to 3.9, q stands for an average added mol number of 0.

Abstract: A method for the preparation of cellulosic pulp capable of being defibrated (fluffed) for the manufacture of an absorbent material intended to be incorporated as a component in absorbent products. A stock of cellulosic fibres in aqueous suspension is pH-adjusted to 4<pH<8, that at least any water-soluble, non-polymeric aluminium salt is added to the stock, said salt in aqueous solutions at said pH forming at least any hydrocomplex with aluminium of the type Al(OH)nx, where n is a number between 1 and 3, and x is o, + or 2+, that said salt in aqueous solution is caused to act on the cellulosic fibres in said suspension at said pH during a period of time of at least 2 min, and that the fibre pulp thereafter is formed to a web, which is dewatered and dried. The invention also relates to the prepared cellulose pulp as such and to its use in absorbent products.

Abstract: A unit (4) consumes hydrogen peroxide at a predetermined concentration C1 and at a rate variable from 0 to D1. The apparatus (1) generates hydrogen peroxide at a concentration C2>C1 and at a rate variable between two values D2 and D3. The generated hydrogen peroxide is fed to a buffer (2) from which a variable flow is drawn, optionally diluted (at 3) and fed to the consumer unit (4). The system is useful for delivering hydrogen peroxide to paper pulp bleaching units.

Abstract: The present invention relates to a process for producing pulp which is cooked under alkaline conditions and which is bleached without using chlorine-containing bleaching chemicals, in which process used cooking chemicals are recovered in a first recovery installation and used bleaching chemicals are recovered in a second recovery installation. The used cooking and bleaching chemicals can be regenerated and reused.

Abstract: A method and a device for measuring the content of chemicals used in connection with bleaching of preferably cellulose fibers in a pulp, suspension for the purpose of providing a better and more uniform product quality and preventing overdosage of the bleaching chemical used. According to the invention a measurement sample is derived from a predetermined volume of the pulp suspension after or during the bleaching. Further, a catalyst in the shape of the enzyme catalase is added to the sample, which is agitated so that the bleaching chemical is decomposed and oxygen gas is generated, which oxygen gas pushes out a certain sample volume for the measurement sample, which sample volume is directly or indirectly converted, e.g. via a simple algorithm, to a value representing the content of the bleaching chemical used.

Abstract: Provided is a method of treating chemical paper pulp having the steps of: adjusting the pH of the pulp to be between 1 and 6; treating the pulp with ozone to reduce the kappa number of the pulp; treating the pulp with a chelating agent after the ozone treating step without any intervening washing step between the ozone treating step and the chelating agent treating step; adjusting the pH of the pulp by adding alkali together with or after the addition of chelating agent to a pH exceeding 3; washing the pulp; and bleaching the pulp with peroxide.

Abstract: Chemical cellulose pulp is made from sawdust utilizing a static down-flow retention vessel. By adding steam and cooking liquor to a flow of sawdust a heated slurry, at a cooking temperature of about 250-350° F., is produced. The heated slurry is, at superatmospheric pressure, moved downwardly in the static down-flow retention vessel while cooking temperature is maintained, for a time period of about 0.5-6 (preferably 1 to 3) hours, the slurry having a consistency of about 5-30%. At superatmospheric pressure, without significant reduction in pressure from the retention vessel, the slurry is cooled to well below cooking temperature by diffusing cooling liquid through it, as in a conventional pressure diffuser. The discharge from the retention vessel is preferably substantially solely gravity action (e.g. using a discharge with single convergence and side relief).

Abstract: A single stage method delignification process for pulps, preferably sulphite pulps. The improvement to conventional oxygen delignification process comprises in situ addition of a reducing agent substantially non-reactive with oxygen. The end result is a pulp having enhanced strength properties and higher viscosity. Sodium borohydride is the preferred reducing agent, and MgO is the preferred alkali source. Similar results can be obtained with a two-stage oxygen delignification wherein the pulp is treated with the reducing agent in the first stage, and then washed and pressed conventionnally before proceeding with the oxygen delignification in a second stage.

Abstract: Methods for oxygen delignification of a pulp are disclosed, including initially delignifying the pulp at a delignification temperature of less than 90° C., adding oxygen to the pulp so that the oxygen is present during the initial delignification step, and further delignifying the pulp at a delignification temperature of greater than 90° C., the difference between the two delignification temperatures being less than about 20° C., and the pressure being greater in the initial delignification step. The method also includes adding alkali solely to the initial delignification step in order to obtain high alkalinity therein.

Abstract: A method of inhibiting the autooxidation of fatty acids in a paper product made from pulp fiber is accomplished by adding to the pulp fiber between about 1 mole/metric ton and about 25 moles/metric ton, preferably between about 2 moles/metric ton and about 10 moles/metric ton of an oxidizing halogen.

Abstract: A method for conditioning an ozone gas recycle stream in an ozone pulp bleaching process. The method includes the steps of providing an oxygen containing feed gas to an ozone generator; generating ozone from said feed gas to produce an ozone rich oxygen gas; bleaching pulp with said ozone rich gas, thereby producing an exhaust gas containing contaminants including carbon dioxide and entrained pulp fibers; removing at least some of said contaminants by at least removing entrained pulp fibers from the exhaust gas to produce a recycle gas; directing said recycle gas into the ozone generator to provide at least a portion of said oxygen containing feed gas; and removing carbon dioxide during said contaminant removal step in an amount sufficient to a level of about 6 wt. wt. % to thus allow operation of the ozone generator at or approaching full capacity.