Abstract: The invention relates to a process of increasing the solids content of black liquor at its recovery in a sulfate pulping process. According to the invention, the liquor is first heated at a pressure which is so high that no boiling occurs at the heating temperature, after which the liquor is led to a tank where its pressure is released to a value below the saturation pressure of steam at the relative temperature of the liquor such that water is evaporated. The liquor thus concentrated can be led to the liquor combustion in the recovery process.

Abstract: A multi-stage wood chip cooking process performed in a single digester in a batch type operation. The wood chips to be cooked are introduced into the digester and soaked with a warm black liquor to remove most of the air from the digester and the chips. This warm black liquor is thereafter displaced from the digester with a mixture of a first stage hot black liquor and hot white liquor, the proportionate amount of hot white liquor being relatively high. The temperature of the digester contents is then raised to a cooking temperature for a predetermined amount of time. The original cooking liquor is then displaced with a mixture of a second hot black liquor and hot white liquor, the proportiionate amount of hot white liquor in this second cooking liquor being less than in the first. Again, the temperature of the digester is raised to a cooking temperature and the cooking is carried out for a shorter period of time than in the first cooking stage.

Abstract: This material which has a hemi-cellulose content of less tha 2%, a benzopyrene content of less than 2 ug/kg and a calorific value which is about 20% greater than that of the starting material is obtained by isothermal treatment between 220.degree. C. and 280.degree. C. for a period of thirty minutes using crossed flows of treated material and of oxygen-free hot gases in an oven including stirring means (6,9) and a gas generator (1) with the gas being circulated by a fan (3).

Abstract: Process for recovering chemicals and energy from cellulose waste liquors preferably black kraft liquor obtained in a paper pulp sulphate process, comprising the following, three distinct and separate steps: In the first step the concentrated black liquor is gasified in a pressurized gasification reactor by so called flash-pyrolysis at 700.degree. to 1300.degree. C., normally 800.degree.-900.degree. C., whereby an energy rich gas is produced, and in which the inorganic chemicals of the black liquor are contained in the form of molten suspended droplets, mainly comprising sodium carbonate and sodium sulphide. In the second step the gas from the gasification reactor is rapidly cooled through direct contact with water, and with green liquor, which is formed when the molten droplets and the hydrogen sulphide are dissolved in the quench liquid. The cooled gas subsequently passes through a scrubber.

Abstract: The invention relates to a method for evaporation of spent liquor by heat from a blow condenser where blow steam from a pulp cooker is condensed in a direct condenser connected with a hot water accumulator. Spent liquor heated indirectly by hot water from the accumulator is brought to expand and released expansion vapor is used as a heat medium in a following evaporation stage. The apparatus comprises a heat exchanger, at least one flash tank and at least one evaporation unit, the heat exchanger being disposed to receive hot water from the upper part of the accumulator and to return it to its lower part and thus heat the spent liquor, and the flash tank being disposed to receive spent liquor heated in the heat exchanger and to release liquor vapor and spent liquor to the evaporation unit.

Abstract: Calcium containing sulphate spent liquor is deactivated by means of heating. Spent liquor is heated by means of direct condensing in a flash-steam-system. Liquor vapors generated during expansion of the already deactivated spent liquor are used for heating the spent liquor. Spent liquor is led to a retention tank through n+1 in series connected direct condensers (DK I-DK V) and from the retention tank through n in series connected flash tanks (FT I-FT IV) disposed counter-currently to the direct condensers. In the last one of the direct condensers (DK V) the liquor is heated by means of externally supplied steam; in all others (DK I-DK IV) by means of expansion vapor.

Abstract: A partially-oxidized spent pulping liquor is produced which is added to unoxidized strong spent pulping liquor prior, during, or subsequent to concentration to form a novel partially-oxidized, concentrated, high total solids spent pulping liquor. This novel, partially-oxidized, concentrated spent liquor is capable of being combusted in a spent liquor recovery furnace without the addition of auxiliary heating fuel with a resultant increase in the effective capacity of that furnace.

Abstract: A method and system for efficient heat recovery during the production of mechanical pulp treats the process steam inherently produced during the production of mechanical pulp to maximize the energy content of clean steam produced. Comminuted cellulosic material is refined in one or more refiners, and the mixture of mechanical pulp and process steam from the refiner is separated into process steam and pulp flows by a cyclone. The process steam is passed to a scrubber, and then to an inlet of a reboiler (steam transformer) which produces clean steam and discharged flow-through process steam. The conduit between the cyclone and the scrubber is open so that the pressure of the process steam before it enters the reboiler is not significantly affected; a buffer may be provided in the conduit, however, to damp process steam pressure variations.

Abstract: A method for acid-catalyzed hydrolytic splitting of cellulose to give a high yield in sugar with a minimal expenditure in energy, in particular, with the smallest possible charge of live steam. Admission of steam is performed in a plurality of successive, discrete reaction stages having in each case defined temperature and pressure values in such a manner that the temperature rises from one stage to the next while the reaction time decreases and a rapid expansion takes place subsequently to the last reaction stage. A high pressure poured bed reactor is used for performing this method.

Abstract: A method for the treatment of a suspension, such as pulp, with one or more treatment liquids in a manner that maximizes treatment efficiency and minimizes heat loss. The pulp flows in a flow path confined to a given web thickness, and has first and second opposite sides. Treatment liquid is added to the first side of the flow path at spaced predetermined points along its length. Liquid displaced by the treatment liquid is withdrawn from the second side of the flow path at substantially the predetermined points. The displaced liquid at the first predetermined point along the flow path consists essentially of original suspension liquid, while the liquid fraction of the pulp past the last predetermined point of the flow path is composed mainly of treatment liquid added at the last predetermined point. Treatment can be accomplished at super-atmospheric pressure and at a temperature above 100.degree. C. The web thickness is between about 50-500 mm.

Abstract: In the production of mechanical pulp, a refiner (defibrator) is driven by a steam turnine. The steam supply for the turbine comprises process steam generated in the refiner during the refining action, which steam is preferably passed through a reboiler. Some make-up energy is necessary to provide all of the power for driving the refiner, the make-up energy being preferably provided by clean steam from an accessory source introduced to the turbine by a steam ejector. A portion of the process steam, and the steam discharge from the turbine, can be used for presteaming the chips (comminuted cellulosic fibrous material) before introduction into the refiner. Any condensate from the turbine may be fed to the reboiler. Reduction gears are provided between the turbine and the refiner drive shaft so that the refiner is driven at optimum rpm for the particular material being treated.

Abstract: In the production of mechanical pulp a refiner (defibrator) is driven by a steam turbine. The steam supply for the turbine comprises process steam generated in the refiner during the refiner action, which steam is passed through a reboiler and then superheated, in a superheater or economizer, before being supplied to the turbine. A boiler comprises a secondary source of steam and that steam too is introduced to the steam turbine, either directly or after passage through another turbine which powers an electric generator. The off-gases from the boiler may drive a gas turbine. All the components may be mounted on a train, and the gas turbine may power the locomotive for the train. The gas turbine can also power an air compressor providing compressed combustion air to the boiler.

Abstract: The present invention seeks to provide a method in which the soda lye obtained as a result of cellulose cooking process and unslaked lime are used for producing white liquor which can be re-used in the cooking process. In this method, the heat released by the slaking of lime with soda lye is recovered by a high pressure slaking process wherein the heat is transferred, either to the steam separating from the lye, which steam is then led to the desired application, or to some other medium to be heated. The present invention is characterized in that the soda lye to be causticized is divided into two parts, one of which is used for the slaking of lime by adding to it all the unslaked lime needed for the causticizing process, and that, following slaking, the two volumes are brought together for the actual causticizing reaction involving the total amount of lye needed. The present invention provides the advantage that the amount of lye needed is smaller, and so the temperature can be increased.

Abstract: Pulping liquor, which has been pre-concentrated to at least 50 weight percent solids, is dried in a fluidized bed dryer to produce a solid in particulate form. In the fluidized bed dryer, pre-formed particulates are fluidized by a gaseous medium substantially of superheated, unsaturated steam, and additional heat is supplied to the fluidized bed by higher pressure saturated steam passing through heat-exchange tubing within the fluidized bed region. Pulping liquor is introduced into the fluidized bed where the superheated steam vaporizes a substantial portion of its water content. The fluidizing steam becomes substantially saturated during its passage through the region of the fluidized bed, and a substantial portion of this substantially saturated steam is used upstream to pre-concentrate the pulping liquor.

Abstract: A process for continuous digestion of wood chips which are passed through a heating zone, a digesting zone and a cooling zone in contact with cooking liquor is disclosed. In this process the wood chips are fed into and the liquid phase removed from the input end of the heating zone in such relative quantities that their heat-capacity flows are of approximately the same order of magnitude.

Abstract: The process described is a novel use of two complementary processes, the first of which provides the product to be converted into energy by the second process, related in such a way that the two combined provides an alternative to conventional fuels at a significant economical advantage. Specifically, the burning of sulfur with air or oxygen produces sulfur dioxide which can be combined with water to form sulfuric acid and by electrolysis, the sulfuric acid and water is converted to hydrogen gas. Hydrogen gas is burned as has been the sulfur, each producing thermal energy which is used to produce steam. The steam produced by burning the two fuels, sulfur and hydrogen gas, is used in the pulp mill in exactly the same manner as has been steam produced by burning fuels such as natural gas, fuel oil, coal and wood.

Abstract: The invention relates to a process for the washing of pulp with a maximum recovery of energy, the pulp after digestion being washed in a plurality of successive washing steps at a pressure above atmospheric in at least one of the steps and washing filtrate from a following step or fresh water being used as diluting and washing liquid in a given step. The outgoing washing filtrate from a washing step should be heat exchanged against incoming diluting and washing liquid to the subsequent step and a part of the filtrate (21) from the second step should be heat exchanged against washing filtrate (10) from the first step and then be combined with cooking liquor (23) for the digestion of the pulp. As diluting and washing liquids in the last two steps (4, 5), fresh water is used, which has also been heat exchanged against outgoing washing filtrate (54, 10) from the last and the first washing step.

Abstract: A method for utilizing hot spent liquor, produced in a digester as the result of cooking a mass of cellulosic material with cooking liquor, is displaced from the top of the digester by pumping under pressure a displacing liquid into the base of the digester. The hot liquor so displaced is collected in an accumulator, and used to preheat another mass of cellulosic material as a preliminary to cooking of this other mass of material.

Abstract: Apparatus and method for reclaiming heat from batch digesting operations including two fluid-to-fluid exchangers fluidically interconnected to allow the passage of an inert fluid between the heat exchangers. The inert fluid passes through the inaccessible regions of the heat exchangers promoting the exchange of heat between spent digester cooking fluid and fresh digester cooling fluid without scaling, clogging or blocking the inaccessible regions of the heat exchanger.

Abstract: In a pressurized materials processing system, separation of solid particulates from a gaseous process fluid is beneficially accomplished by use of a swept orifice discharger comprised of a cylindrical housing that is closed at one end and open at the other end. The housing contains an impeller within its interior and has a selected, presized orifice in its cylindrical side wall. In operation, the solid material and gaseous fluid are received in the swept orifice discharger housing and the solid material is continuously centrifugally urged toward the housing side wall so that it separates from the gaseous process fluid and collects on the housing side wall.

Abstract: A process is provided for inexpensively producing high yield mechanical cellulose pulp having good paper properties, which comprises preheating particulate lignocellulosic material; defibrating the preheated material under a superatmospheric steam pressure within the range from about 2 to about 4.5 bar above atmospheric pressure in a disc refiner under conditions such that steam is generated during the defibration; continuing the defibration until a cellulose pulp is obtained having a freeness within the range from about 300 to about 700 ml CSF; flash drying the defibrated cellulose pulp while maintaining a superatmospheric steam pressure within the said range during the drying; withdrawing steam generated during the defibration and passing it in indirect heat exchange with steam utilized in the flash drying, so as to utilize in the drying at least 30% of the heat content thereof; and then removing and baling the flash-dried cellulose pulp.

Abstract: A steam generator assembly, particularly for use in connection with the mechanical preparation of pulp, for generating pure steam required in a subsequent process, such as drying of proper in a paper machine, by utilizing the condensation heat of contaminated steam coming from a preceding process, such as a grinding process, includes a steam converter and electrical boiler arranged in a common housing to form a unified structure. The steam converter utilizes the condensation heat of the contaminated steam to generate pure steam from water supplied to the converter. The electric boiler is connected in parallel to the steam converter and includes electrodes adapted to generate steam when moistened by water supplied to the boiler from a separate water container in the housing. Selective control of the supply of water to the electric boiler and the extent to which the electrodes are moistened regulates the amount of pure steam generated by the electric boiler.

Abstract: Operation of a multiple solids fluidized-bed black liquor combustor employing only combustion residue solids as both fine and coarse bed solids is disclosed. Under normal operating conditions, a solids distribution of fine particle sizes and coarse particle sizes with a minimal population of intermediate particle sizes is maintained. Heat and chemical values are readily recovered from the black liquor and the necessity for separation of the combustion residue salts from inert fluidized-bed solids is avoided.

Abstract: Procedure for preparing thermomechanical pulp from wood chips, wherein the chip flow is conducted from a storage reservoir under normal pressure through a first lock feeder into a pressurized steaming chamber, where the chips stay for a few minutes and are heated to an optimum temperature of 100.degree. to 125.degree. C., and from the steaming chamber through a second lock feeder to a feed means which supplies the chips into an enclosed hot refiner. In the procedure the steam discharging from the throat of the refiner against the chip flow is utilized for heating the chips in the steaming chamber, and the steam separated from the mechanical pulp is led off for use elsewhere.

Abstract: A method and system for recovering heat in a pulp digesting process is disclosed. The method includes the steps of blowing a pulp and liquid mixture from a digester to a container such as a blow tank or blow cyclone; transferring flash vapor above a predetermined pressure, which is above atmospheric pressure, from the blow tank to a pressure accumulator; transferring flash vapor below the predetermined pressure from the blow tank to an atmospheric accumulator; and mixing the flash vapor with a processing liquid in the pressure accumulator.

Abstract: A process is provided for heating up wood chips in one or more stages at progressively higher temperatures prior to steaming and pulping in an economical manner at a considerable cost saving; heating the chips in at least a first preheating stage directly with moisture-saturated hot air, optionally admixed with inert gas, having a temperature within the range from about 55.degree. to about 99.degree. C., preferably from 70.degree. to 90.degree. C., having been brought to that temperature in a heat exchanger with hot water or air heaters with waste gases, such as gases drawn at different levels from an evaporator, for example, a Lockman pre-evaporator column.

Abstract: A recovery system for residual liquor from a pulp mill, utilizing a fluidized bed to burn the organic material in the residual liquor and generate heat which may be recovered. Heat preferably from the flue gases is used to dry residual liquor sprayed to pellets extracted from the bed, thereby to provide pellets coated with dried residual liquor. The so coated and dried pellets are then reinjected into the bed and the organic material in the dried residual liquor is burned to generate the heat recovered from the bed.If the residual liquor is from a kraft mill sulfur compounds are in the form of sulfate and must be reduced to sulfide and a reducing stage will also be provided either in the reducing zone in existing conventional kraft system (if capacity is available) or in a separate reducing zone and some of the pellets from the bed may be directed to the reducing zone together with some of the pellets coated with dried residual liquor.

Abstract: A method and apparatus in defibration of wood chips or similar vegetable material for conveying in steam pulp produced in a refiner (2) to a separator (7) for separating steam and pulp. The separator is bounded against the atmosphere and is kept pressurized by steam, while a limited amount of excess steam is led off. A flow of steam liberated from the pulp is taken from the separator and given an increased pressure for utilization in extracting pulp from the refiner. The steam flow is hereby led through the refiner and further to the separator, whereby the pulp is transferred to the separator by the steam which thus circulates to a considerable extent, said steam having been given the higher pressure either in the refiner itself, by means of pressure increasing means (19) therein, or upstream of the refiner in a separate pressure increasing means (11).

Abstract: High heat recovery and minimized oxygen requirement for oxidation of sulfur compounds in black liquor is obtained by integrating the oxidation into the multiple effect evaporation system of the pulp mill recovery sequence. The oxidation step is carried out at an intermediate stage in the multiple effect concentration of weak black liquor in counterflow to the external heat input, and the thus oxidized liquor is then further concentrated by flow through the remaining effects of the system co-currently with the direction of heat flow.

Abstract: At start-up, a bed of pellets derived from pulp mill residual liquor is fluidized by feeding preheated air to the bed to initially raise the temperature of the bed to a temperature at which a particulate ligno-cellulosic auxiliary solid fuel may be completely consumed (800.degree.-850.degree. F.

Abstract: An integrated system, process and apparatus are provided for the efficient and effective recovery of spent pulping liquors, particularly kraft black liquor, whereby in an initial stage concentrated spent liquor is subjected to combustion in a reactor equipped with a plurality of particulate materials, at least one of which is of finer particle size than the other, preferably subjecting a portion of said particulate materials to at least one further treatment in a fluidized bed unit, and treating the inorganic solid combustion products in a reducing atmosphere.

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 versatile process and apparatus is presented for producing, in high yields, many different grades of pulp from a single wood specie or for pulping any specie or type of woody material, and for storage and recycling of the by-product liquid and gaseous materials. The process of this invention is virtually pollution free, and the reactant chemicals are recoverable from the by-products. In the alternative, the by-products themselves have a commercial value which may forestall recovery of the reactants. The lignin constituent extracted from the pulp is usable as a resin binder, a wood rehardening agent, or a glue.

Abstract: High recovery of useful energy from the heat of reaction in the oxidation of black liquor is obtained by integrating the oxidation into the multiple effect evaporation system of the pulp mill recovery sequence. The heat of reaction is thereby recovered as flash steam, which when combined with the vapors from an appropriate evaporator body enables recovery of its energy through further evaporation. The oxidation reaction may be carried out on the liquor leaving the second effect of the evaporation sequence for maximum energy recovery, or in accordance with an alternative embodiment, the reaction is carried out between the first effect and the flash tank with preferable addition of a second flash tank in series with the first.

Abstract: Lignocellulose is pulped batchwise by introducing it and the white liquor in predetermined quantity, together with a variable quantity of black liquor, into a continuously steam pressurized digester. When the cooking cycle has been completed, the pulp product is withdrawn. The time intervals of feed material introduction and pulp product withdrawal are correlated to insure that all of the lignocellulose charged to the digester is cooked uniformly, as by withdrawing the pulp product over a time interval which is substantially equal to the feed time. For economy and efficiency of operation, the digester preferably is operated in conjunction with one or more companion digesters to which it is connected. The first digester then is blown while a second digester is charged, making possible transfer of hot pressurized black liquor from the former to the latter.

Abstract: A method of recovering the thermal energy contained in the pressurized steam utilized during the production of thermomechanical pulp. The steam is applied to the primary side of a heat exchanger with water supplied to the secondary side in order to produce hot water. The water is vaporized to produce clean steam. The clean steam is then utilized to at least a first steam group of the drying sections of a paper manufacturing machine without increasing the pressure of the clean steam.

Abstract: A method of making fiberboard using a substantially closed white water system. One or more layers of separately prepared surface pulp is applied to a layer of base pulp at the wet sheet forming stage. Lignocellulose chips in a pressure-sealed defibrating zone under generation of steam. The steam is separated at the discharge end of the defibrating zone under atmospheric pressure. The atmospheric steam is utilized to presteam the raw chips. The presteamed chips are thereafter dewatered to a moisture content coordinated to the energy demand of the defibrating treatment and the desired generation of steam prior to entering the defibrating zone. The water removed at the dewatering stage is collected for use in preparing the surface layer pulp suspension. A small portion of the base pulp to be used for the surface layer pulp is diverted to a refiner and diluted with water.

Abstract: A process is provided for preparing groundwood pulp from debarked pulpwood logs, which comprises grinding the logs under a superatmospheric pressure of a gas selected from the group consisting of steam, air, and steam and air, while continuously supplying thereto water comprising spent bleaching liquor at a temperature of at least 70.degree. C. and forming a pulp suspension in the resulting aqueous liquor; centrifugally separating steam from the pulp suspension and using the separated hot steam to heat spent bleaching liquor supplied for the grinding; thickening the pulp suspension to a concentration within the range from about 5 to about 40% and supplying water separated therefrom to the grinding; diluting the pulp suspension to a concentration within the range from about 0.5 to about 4.

Abstract: A process is provided for preparing groundwood pulp from debarked pulpwood logs which comprises grinding the logs under a superatmospheric pressure of a gas selected from the group consisting of steam, air and steam and air, while continuously supplying thereto process white water and water separated in thickening groundwood pulp suspension at a temperature within the range from about 75.degree. to about 100.degree. C.

Abstract: A device for evacuating blow-back steam in a pulp refining apparatus in which lignocellulosic pulp stock is ground in an environment of superatmospheric steam in a grinding space defined between a pair of grinding members which rotate relatively to one another in a closed housing having a feed-in opening into which the pulp stock is advanced by means of a feed screw which rotates within a feed-in passage. A jacket having a perforate wall is arranged about the feed-in passage for receiving the blow-back steam separated from the pulp stock, and which steam is evacuated therefrom through a conduit connected to the jacket. The feed screw rotates in close proximity to the perforate wall to maintain it free of pulp stock particles.

Abstract: Cooked pulp at an elevated temperature and pressure is discharged from a plurality of batch digesters sequentially into a first blow tank. The first blow tank is maintained at a substantially constant pressure which is less than the pressure in the digester and greater than atmospheric. Pressurized steam is released from the first blow tank into a dirty steam system as pulp is discharged into a second blow tank at a substantially constant rate in a non-interrupted flow stream. The pressure in the second blow tank is maintained at about atmospheric pressure. A blow line refiner is interposed between the first and second blow tanks.

Abstract: A method of recovering heat as well as fractions containing volatile alcohols and sulphur compounds from black liquor obtained from pulping. In a vapor generator, water is, by means of vapor, liberated at a high temperature and under a high pressure from the expansion of black liquor removed from a digester, indirectly vaporized into low-pressure vapor, which is used for vapor treatment of chips before their introduction into the digester. The condensate produced in the vapor generator is, under pressure control, passed into a condenser device, which is operated at a pressure that is lower than the pressure in the black liquor escaping from the digester, preferably at the atmospheric pressure. The condensate fraction formed in the condenser device as well as the uncondensed gas fraction are cooled by means of indirect cooling and the volatile alcohols and sulphur compounds are recovered from these fractions.

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: 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.

Abstract: Gaseous reaction apparatus wherein a portion of the supplied gas is discharged from the reaction vessel at a location below the upper level of a therein contained columnar mass of material wherein the gas is discharged into a receiving chamber extending along the outer periphery of the vessel and open to the lower portion of the vessel through an unrestricted opening being free from screens and filters, and such discharged portion of the gas, with or without cooling, is recirculated back into the upper inlet end of the vessel, thereby controlling the temperature in the vessel by removing or redistributing heat therein. Such apparatus is particularly useful in the gas phase treatment of fibrous material such as the bleaching or delignification of lignin-containing cellulose pulp.