Abstract: A method of cooking cellulose material and effectively preserving the heat and terpentine content of the cooking liquor is disclosed. The cooking liquor is allowed to expand and the expansion steam (blow steam) is conveyed into a bed of cellulose material in a storage container (3', 3) to heat and impregnate the cellulose material before cooking. A heated zone is maintained in the bed of material below the surface of the bed by regulating the flow of expansion steam into the container. Uncondensed, evil-smelling and poisonous gases are at the same time prevented from flowing out into the atmosphere. These gases are drawn off from the storage container for destruction.

Abstract: A process for making a refiner mechanical pulp from wood chips which comprises:(a) Comminuting the wood chips largely by splitting along the wood grain;(b) Wetting said particles with a solution of a sulphite salt of an alkali metal to add an amount of said alkali metal salt within the range of 1% to 10% of the oven dry weight of said particles, said solution having a pH within the range of 7 to 12.5;(c) Steam heating the sulphite salt solution bearing particles to a temperature within the range between 80.degree. C. and 165.degree. C. and holding them within that temperature range for a period of 0.5 to 80 minutes;(d) Passing the particles, after said period of heating, through a disc refiner to produce refiner mechanical pulp.

Abstract: Disclosed is a process for producing stone groundwood pump from wood chips, by compressing a wood chip mass into an apparent volume corresponding to 70% or less, preferably, from 40 to 60%, of the original apparent volume of the wood chip mass and by grinding the compressed wood chip mass, under pressure, with a stone grinder. The wood chips may be treated, before the grinding step, with both or either one of steam and a treating agent, such as sodium monosulfite, sodium disulfite and sodium bicarbonate.

Abstract: A process is provided for the chemical refining of cellulose pulp which comprises, in sequence, the steps of:(1) impregnating the cellulose pulp with refining chemicals in an amount selected to effect chemical modification of the pulp;(2) adjusting the pulp consistency to within the range from about 30 to about 70%; and(3) passing the pulp in turbulent flow through an elongated reaction zone from one end to another end thereof in a gaseous atmosphere consisting essentially of steam and preferably containing less than 1% by volume of oxygen at a superatmospheric pressure within the range from about 5 to about 400 kPa and a temperature within the range from about 100 to about 150.degree. C. at which the chemical modification proceeds without a mechanical working sufficient to change the degree of beating of the pulp by more than about 2.degree.

Abstract: A method for continuously digesting cellulosic fiber material so that the digested pulp has a very low quantity of reject material (i.e. one to two percent) compared to the prior art. Fiber material is continuously fed into a standing vessel downwardly through the vessel steam phase to establish a fiber level, digesting liquid being added to the vessel to maintain a liquid level therein, and the digested pulp being withdrawn from the bottom of the vessel. Spreading of the downwardly flowing fiber material in the steam phase substantially evenly over the vessel cross-section is effected and the downwardly flowing fiber material is heated by introducing a major portion of the steam to be introduced into the steam phase at a first vertical position about 0.0 to 100 cm. above the higher of the fiber and liquid levels in the vessel.Some of the steam may be added at a second vertical level, or at a third vertical level.

Abstract: Process and apparatus are provided for the preparation of improved high-yield cellulose pulps, such as semichemical, chemimechanical, thermomechanical, and mechanical pulps, which comprises mechanically defibrating a mixture of particulate lignocellulosic materials which have been partially pulped and softened to different extents. Part of the raw lignocellulosic material is particulate form is washed, moistened with steam, impregnated with pulping chemicals and pulped to a yield of from about 65 to about 92%. Another part is treated in similar manner but either not pulped at all or, if pulped, pulped to a lesser extent. The two parts are mixed without intermediate washing, after which the mixture is subjected to a vapor phase pulping by heating to a temperature within the range from about 90 to about 200.degree. C. under pressure to obtain softening of the lignin, and delignification, after which the resulting product is mechanically defibrated to form cellulose pulp.

Abstract: A process and apparatus for automatically maintaining the moisture content in a continuously conveyed batch of porous materials is described. The porous material is continuously fed through a treatment tank, wherein it is contacted with a liquid to be absorbed therein. The moisture content of the material is continuously monitored as a direct function of the combined weight of the material and the treatment tank to generate correction signals. The correction signals are utilized to vary the dwell times (up or down) of the porous material in the treatment tank. By varying the dwell times the porous material is contacted by the treating liquid for either larger or shorter periods until the weight of the tank and material therein returns to the weight desired. Thus, the moisture content of the porous material is continuously adjusted to a substantially constant value.

Abstract: Lignocellulose material is mechanically compacted and subjected to sudden pressure increase by exposure to saturated steam in a digestor vessel in the absence of added chemical reagents to obtain a cooked material which is then mechanically compacted while under said saturated steam pressure. Small portions of the cooked and mechanically compacted material are thereafter subjected to rapid reduction in pressure down to atmospheric pressure and then recovered in a condition of enhanced digestibility by ruminants.

Abstract: A pulp mill bleach plant operation having a low effluent volume, a low consumption of water, energy and chemicals, and yet provides efficient bleaching, caustic extraction and washing is described. Water conservation is practised by controlling the use of wash water in the bleach plant, controlling the design and operation of washers, deckers and other mechanical devices used in the bleach plant and controlling the inflow of water with chemicals. An aqueous polluting effluent-free pulp mill water utilization system is also described.

Abstract: Solvent pulping of wood chips or other fibrous plant material is effected using an aqueous solution of a lower aliphatic alcohol in a plurality of batch extraction vessels. The charge in each vessel is heated rapidly to pulping temperature by recirculation of a primary extraction liquor having a relatively high dissolved solids content, and thereafter the charge is subjected to a series of once-through extractions or washes with successively cleaner liquors, including a final extraction or wash with fresh liquor. The extraction liquor from one extraction stage in one vessel is used in another extraction stage in another vessel. Upon completion of the extraction, the liquor is drained from the vessel, the vessel is depressurized to a solvent condenser, and the remaining solvent is steam stripped from the charge and recovered. The used extraction liquor is treated in an alcohol recovery system by flash vaporization, condensation of the solvent vapors, and vacuum stripping of the residual liquor with steam.

Abstract: A method and apparatus for presteaming of wood chips and the like. The chips are treated in a vertical presteaming vessel with steam under low pressure, and removal of the air from the chips is facilitated by maintaining the presteaming vessel substantially at or near atmospheric pressure. An exhaust fan, controlled by a pressure probe in the presteaming vessel, may be provided for maintaining the pressure in the vessel. The amount of air that can enter the vessel through the chips inlet is minimized by an inclined rotating screw assembly with a partial flight which elevates the packs and chips to form an isolation seal at the chips inlet into the vessel.

Abstract: Raw fibrous material is preheated in a preheater in the presence of steam under a pressure greater than atmospheric pressure and then continuously introduced into a disc refiner, without prior defibration, whereby steam is generated in said disc refiner. The generated steam is continuously conducted away from said disc refiner as subsequent fibrous material is continuously being introduced into the disc refiner in order to obtain a pressure in the disc refiner which is greater than atmospheric pressure but less than the pressure in said preheater.

Abstract: A stream of disintegrated fibrous cellulosic pulp material and steam under pressure is subjected to an instantaneous pressure reduction as said stream and steam pass through a throttling nozzle, in a throttling zone, wherein a liquid solution of a bleaching agent is admixed with said stream and which stream, admixed with bleaching agent, is then passed into an expansion zone ahead of the throttling nozzle resulting in a uniform dispersion of the bleaching agent into the fibers in the stream of fibrous cellulosic pulp material.

Abstract: Lignocellulose fiber containing chips, preheated with steam liberated from a previous chip defibration, are dewatered and then defibrated in an atmosphere of saturated steam and in the presence of backwater and suspended in backwater to form a pulp suspension whereafter wet sheets are formed from the pulp suspension, water is mechanically removed from the wet sheets and recycled as backwater to be supplied simultaneously, with dewatered chips, to the defibration step and to form a new pulp suspension and said wet sheets are dried.