Abstract: A method of splitting hollow cellulosic fibers employs the steps of wetting the fibers, feeding the wet fibers to a gaseous flow, and conducting the gaseous flow carrying the fibers through a venturi tube, the pressure drop in the venturi tube throat bringing a pressure difference between liquid inside the fibers and gas outside of the fibers and causing the fibers to split in their longitudinal direction, to open the lumen inside the fibers.

Abstract: Methods for processing pulp in an apparatus for washing and dewatering pulp and a system for controlling this apparatus are provided. The apparatus includes a pair of rotatable press rolls installed in vats and including a press nip therebetween, an inlet for feeding the pulp to the press nip, with one of the press rolls being movable in relation to the other and in which the processing of the pulp is determined by the number of variable operating parameters. The method includes utilizing the distance between the press rolls as a variable operating parameter, setting a desired value for a specific control parameter, measuring the specific control parameter, and adjusting at least two of the variable operating parameters during operation to maintain the difference between the desired value and the measured value of the specific control parameter below a predetermined difference. Systems for controlling this apparatus are also disclosed.

Abstract: A system and method for optimizing a process for refining lignocellulosic granular matter such as wood chips use a predictive model including a simulation model based on relations involving a plurality of matter properties characterizing the matter such as moisture content, density, light reflection or granular matter size, refining process operating parameters such as transfer screw speed, dilution flow, hydraulic pressure, plate gaps, or retention delays, at least one output controlled to a target such as primary motor load or pulp freeness, and at least one uncontrolled output such as specific energy consumption, energy split, long fibers, fines and shives. An adaptor is fed with measured values of matter properties and measured values of controlled and uncontrolled outputs, to adapt the simulation model accordingly. An optimizer generates a value of the target according to a predetermined condition on a predicted uncontrolled output parameter and to one or more process constraints.

Abstract: A method of and an apparatus for controlling the height of a material column in a vessel upstream of a pump, in which method material is conveyed into an upper portion of the vessel, electrical signals are provided on the basis of the presence of material at predetermined measuring levels of the vessel by using a first sensor set disposed at a first measuring level at the upper portion of the vessel and a second sensor set disposed at a second measuring level at the lower portion of the vessel, and material is extracted at a controlled flow speed from a lower portion of the vessel by the pump, wherein the provided electrical signals are used to infer weighting factors of measuring level presence functions, and the flow speed is controlled on the basis of the weighting factors of the measuring level presence functions.

Abstract: The system is for the reception and transport of dry lime mud from a continuously operating pressurized filter in a causticization process. A tube valve is used as an outlet from the pressurized process. The tube valve has a minimum length that is twice a diameter of the tube. A column of lime mud can be held within it as a pressure lock. The column of lime mud can be caused to descend through the tube valve by controlling a difference in pressure between an inner surface and an outer surface of the tube such that the diameter of the tube expands essentially uniformly along its length by 5-10% or by at least 4-6 millimeters.

Abstract: Apparatus and methods for controlling the flow of a pulp suspension from a container in which the pulp is processed or stored are disclosed. The container is pressurized to a first pressure and includes an outlet for the pulp suspension, a pump includes an inlet and an outlet, and the pump inlet is connected to the container. The pulp suspension is fed from the inlet to the outlet of the pump and provides a controlled decrease in pressure to which the pulp suspension is subjected in the pump during such transport, and the flow from the container is controlled by adjusting this controlled decrease in pressure.

Abstract: Apparatus and methods for controlling the flow of a pulp suspension from a container in which the pulp is processed or stored are disclosed. The container is pressurized to a first pressure and includes an outlet for the pulp suspension, a pump includes an inlet and an outlet, and the pump inlet is connected to the container. The pulp suspension is fed from the inlet to the outlet of the pump and provides a controlled decrease in pressure to which the pulp suspension is subjected in the pump during such transport, and the flow from the container is controlled by adjusting this controlled decrease in pressure.

Abstract: The arrangement and method are for the steam pre-treatment of chips during the production of cellulose pulp to avoid the blow-through of gases in the steam pre-treatment vessel. This prevents foul-smelling gases from being released into the atmosphere. Spreader nozzles for the injection of cooling fluid are arranged in the gas phase of the steam pre-treatment vessel. In the event of the risk for blow-through of steam, cooling that is proportional to the risk is activated. It is possible to avoid the emission of gases from the chip bin when interruptions in the process occur, whereby the release of odours into the surroundings can be minimised.

Abstract: The present invention is a rapid method of determining the concentration of the major components in a chemical stream. The present invention is also a simple, low cost, device of determining the in-situ concentration of the major components in a chemical stream. In particular, the present invention provides a useful method for simultaneously determining the concentrations of sodium hydroxide, sodium sulfide and sodium carbonate in aqueous kraft pulping liquors through use of an attenuated total reflectance (ATR) tunnel flow cell or optical probe capable of producing a ultraviolet absorbency spectrum over a wavelength of 190 to 300 nm. In addition, the present invention eliminates the need for manual sampling and dilution previously required to generate analyzable samples.

Abstract: A system for feeding fibres from a fibre separation step at a first pressure to a drying step at a second, lower pressure, the system comprising a sluice feeder (3) provided between the fibre separation step and the drying step. At least an outlet (14) of the sluice feeder (3) is enclosed by a housing (4) for pressurization by means of a pressure medium in the housing (4) to a pressure that essentially corresponds to the first pressure in the sluice feeder (3). The fed out fibre from the sluice feeder (3) to the housing (4) are removable by means of the pressure medium in the housing (4) via a control valve (20), which regulates the pressure in the housing (4), to the drying step at the second, lower pressure. The pressurization in the housing (4) prevents steam to escape from the sluice feeder (3).

Abstract: Method for enabling the paper pulp production process to be controlled in such a way that the hexenuronic acid content in the pulp can be minimized and the color reversion of the pulp and/or the pulp products thereby minimized. The method is based on measurements of the optical properties of a fiber containing substance or process stream in the wavelength region 232±5 nm and another wavelength interval. A significant value for the current hexenuronic acid content is formed by correcting the intensity in the spectrum around 232 nm by the corresponding optical quantity at the other wavelength interval. The content of the hexenuronic acid content that is determined by the analysis is then used for controlling conditions in the process stage.

Abstract: The method is for controlling the cooking temperature in a continuous vapour phase digester for chip-shaped cellulose material. A high pressure is established in the vapour phase largely by means of steam, without risk of attaining excessively high temperatures in the cooking. A temperature-controlled supply of cooking liquor in close proximity to the surface of the liquor level is introduced to obtain a protective liquor surface with a temperature lower than the vapour phase. A lower initial cooking temperature is obtained in the cooking zone, which ensures that the exothermic cooking process does not lead to the attainment of temperatures detrimental to the pulp quality.

Abstract: This invention provides a process for treating chemical woodpulp, or chemical cellulose including cotton linter, including the step of applying an electron processing technology (EPT) step to chemical woodpulp, or chemical cellulose, as the case may be, on an in-line basis to provide control of pulp viscosity or degree of polymerisation (DP). The invention also provides a method of process control in treating the aforementioned woodpulp or cellulose, including the step of using radiation dose-viscosity relationship curve for applying an EPT step on an in-line basis. The in-line EPT step may, in one form of the invention, replace and hence eliminate a chemical DP reduction step.

Abstract: A system for feeding fibres from a fibre separation step at a first pressure to a drying step at a second, lower pressure, the system comprising a sluice feeder (3) provided between the fibre separation step and the drying step. At least an outlet (14) of the sluice feeder (3) is enclosed by a housing (4) for pressurization by means of a pressure medium in the housing (4) to a pressure that essentially corresponds to the first pressure in the sluice feeder (3). The fed out fibre from the sluice feeder (3) to the housing (4) are removable by means of the pressure medium in the housing (4) via a control valve (20), which regulates the pressure in the housing (4), to the drying step at the second, lower pressure. The pressurization in the housing (4) prevents steam to escape from the sluice feeder (3).

Abstract: A method of processing papermaking fiber includes characterizing the initial color of the pulp and the color of the pulp after treatment with a phloroglucinol stain. The color response of the pulp to the stain has been found to be a better indicator of processing needs for secondary pulps in particular and in any event is selective for untreated groundwood as opposed to conventional groundwood identification methods. The color difference is used to target a suitable product for the pulp, to aid in bleaching/deinking strategy or to enable optimization of fiber blending for particular products. In a preferred embodiment the process includes determining changes in CIE L*, a*, b* and brightness values before and after staining of the pulp.

Abstract: An apparatus and process for solvent pulping of cellulose-containing biomass utilizes at least one steaming vessel, a plug screw feeder or compression screw device, at least one super-atmospheric impregnation vessel, a solvent delignification reactor capable of operating at a pressure of 350 psig or more, and a solvent containing line for introducing solvent-containing liquor at the plug screw feeder outlet or compression screw device outlet. The process and system can also include at least one series connected pressure diffuser and optionally a retention tube downstream of each pressure diffuser to provide sufficient retention time to substantially preclude re-deposition of lignin on the cellulose fibers of the biomass, a blow tank connected to the last of the pressure diffusers and retention tubes, and vessels for multistage alcohol washing.

Abstract: Method for enabling the paper pulp production process to be controlled in such a way that the hexenuronic acid content in the pulp can be minimized and the colour reversion of the pulp and/or the pulp products thereby minimized. The method is based on measurements of the optical properties of a fibre-containing substance or process stream in the wave length region 232±5 nm and another wavelength interval. A significant value for the current hexenuronic acid content is formed by correcting the intensity in the spectrum around 232 by the corresponding optical quantity at the other wavelength interval. The content of the hexenuronic acid content which is determined by the analysis is then used for controlling conditions in the process stage.

Abstract: A system and method for improved filtrate addition in a continuous digester is disclosed. The system comprises a blow dilution header/nozzle assembly located in the blow dilution zone of the digester. The header/nozzle assembly comprises (i) a plurality of nozzles for introducing and distributing filtrate into the blow dilution zone, and (ii) a plurality of measurement and control devices for monitoring and controlling filtrate flow through the plurality of nozzles. The method comprises (a) introducing and distributing filtrate through a plurality of nozzles of a blow dilution header/nozzle assembly in the blow dilution zone of the continuous digester; and (b) measuring and controlling the filtrate flow through each nozzle of the plurality of nozzles.

Abstract: A method for controlling the quality of pulp. Pulp produced by mechanical defibering of wood is screened to provide at least two fractions, of which the accept that has passed the screening phase is carried forward for use and the reject that has not passed the screening is removed from the screening phase. The consistency of the reject that is to be removed from the screening is measured and the consistency value thus obtained is used for controlling the defibrator to adjust the quality of the accept.

Abstract: A process for peroxide bleaching of pulp using magnesium oxide or magnesium hydroxide as a substitute for caustic soda wherein the pulp is bleached in the presence of hydrogen peroxide characterized in that the concentration of ion present in the magnesium oxide or magnesium hydroxide and the pulp is maintained less than 20 ppm and/or the concentration of manganese is maintained less than 10 ppm.

Abstract: An on-line pulp digester control system. More particularly, this invention pertains to a control system which employs real time measurements from ion mobility spectrometry to automatically rapidly and continuously determine the physical and chemical characteristics of wood chip feedstock being fed into a pulp digester and thereby maximize process efficiencies, minimize chemical and energy consumption and improve product uniformity.

Abstract: In a tall oil refining operating plant, a warm water loop is disclosed for cooling the tall oil heads fraction extracted from the crude tall oil, rather than the conventional use of cold water. This avoids condensation and the subsequent solidification of athraquinone pulping aid remaining in the crude tall oil; thus, avoiding fouling of the cooling towers. The temperature of the warm-water is controlled automatically by tempering the cold water entering the warm water “cooling” loop, while removing excessively warm water from said loop to the cooling tower system, as needed.

Abstract: In the production of de-inked pulp, measuring devices are used to register spectral and/or physical characteristic values of a starting material. These values are then fed to a neural network, by means of which correction variables are obtained for a regulating or controlling device which in provided. According to the invention, the measuring device is used to evaluate at least the starting materials of the production of pulp and/or paper. The evaluation of the characteristics of the raw material used in the production of pulp and paper is thereby possible.

Abstract: In a method for the carrying out of a flotation, bleach and/or dispersion process serving for the manufacture of fiber or paper while using one or more method stages in which process steps defined by pre-settable chemical and physical routines are carried out and process optimizations are made in dependence on measured values and characteristic values formed therefrom, optionally while using state models, at least the measured values of at least one method stage, which relevantly affect the target values of the respective end product of the method, are detected online and/or the characteristic values determined from the measured values of at least one method stage are evaluated online and used directly or indirectly for the control or optimization of at least one process, with characteristic values being formed in dependence on the starting materials or raw materials and/or on the chemicals, auxiliary materials, energies and/or materials and emissions to be disposed of, which are added in at least one method

Abstract: Kraft pulp of increased strength and bleachability may be produced with decreased consumption of effective alkali, and at a lower H factor, by keeping the dissolved organic material (DOM) concentration low substantially through the entire kraft cook, including by extracting high DOM liquid from at least one part of a continuous digester and replacing it with much lower level DOM liquid. Existing pulp mills having two-vessel hydraulic, one-vessel hydraulic, or other systems may be retrofit to provide for extractions and additions of low DOM dilution liquor (including substantially DOM-free white liquor). Also, commercial size batch digesters (8 tons per day of pulp or more) can be operated with low DOM liquor to produce increased strength pulp. Using dilution with low DOM liquor also results in reduced H factor and effective alkali consumption, and increased bleachability.

Abstract: A new and improved way of continuously cooking fiber material, wherein temperatures and alkaline levels are controlled to be maintained within specific levels in different zones of the digesting process in order to optimize chemical consumption and heat-economy and at the same time achieve very good pulp properties. The digesting process includes a top separator that separates the transport liquid from the fiber material and permits the fiber material to be exposed to the cooking liquid.

Abstract: Kraft pulp of increased strength and bleachability may be produced with decreased consumption of effective alkali, and at a lower H factor, by keeping the dissolved organic material (DOM) concentration low substantially through the entire kraft cook, including by extracting high DOM liquid from at least one part of a continuous digester and replacing it with much lower level DOM liquid. Existing pulp mills having two-vessel hydraulic, one-vessel hydraulic, or other systems may be retrofit to provide for extractions and additions of low DOM dilution liquor (including substantially DOM-free white liquor). Also, commercial size batch digesters (8 tons per day of pulp or more) can be operated with low DOM liquor to produce increased strength pulp. Using dilution with low DOM liquor also results in reduced H factor and effective alkali consumption, and increased bleachability.

Abstract: Methods of controlling oxygen delignification processes are disclosed including providing chemicals for a first oxygen delignification step, conducting the first oxygen delignification step with the chemicals, conducting a second oxygen delignification step at a predetermined temperature to produce a delignified pulp, measuring the final kappa number of the delignified pulp subsequent to the second oxygen delignification step, adjusting the chemicals provided for the first oxygen delignification step based upon the difference between the actual kappa number reduction and the desired kappa number reduction for the pulp, and adjusting the predetermined temperature based on the chemicals provided to the first oxygen delignification step in order to provide the delignified pulp at a final pH of from about 10.5 to about 11.5.

Abstract: Kraft pulp of increased strength and bleachability may be produced with decreased consumption of effective alkali, and at a lower H factor, by keeping the dissolved organic material (DOM) concentration low substantially through the entire kraft cook, including by extracting high DOM liquid from at least one part of a continuous digester and replacing it wit much lower level DOM liquid. Existing pulp mills having two-vessel hydraulic, one-vessel hydraulic, or other systems may be retrofit to provide for extractions and additions of low DOM dilution liquor (including substantially DOM-free white liquor). Also, commercial size batch digesters (8 tons per day of pulp or more) can be operated with low DOM liquor to produce increased strength pulp. Using dilution with low DOM liquor also results in reduced H factor and effective alkali consumption, and increased bleachability.

Abstract: A method and apparatus for controlling a multi-step screening apparatus (1) controls other accept, reject and dilution flows in relation to the flow measured in the accept channel (7a) of the first screening step (3a). Thus a simpler control unit (9) can be used and accept of higher quality can be obtained than before. The apparatus has a control unit (9) aranged to measure the flows of all accept, reject and dilution water channels (7a-7c, 5a, 5b, 11a, 11b) and to adjust the flow of the other channels on the basis of the flow of the accept channel of the first step.

Abstract: The present invention relates to a method for safely carrying out pressurized peroxide bleaching of pulp, at a consistency exceeding 8%, preferably 10-16%, in a bleaching vessel (1), designed for at least 0.5 MPa overpressure, preferably 0.7 MPa overpressure, with the pulp being fed to the vessel (1) by means of a pump (2), preferably a pump having fluidizing elements and venting, and with the pulp which is being fed to the vessel having a temperature exceeding 90.degree. C., preferably exceeding 100.degree. C., more preferably exceeding 105.degree. C., and with the pulp being bleached with peroxide in a quantity exceeding 5 kg/BDMT, preferably in association with a bleaching stage which bleaches the pulp to a brightness exceeding 75% ISO, characterized in that if plugging and/or power failure occur(s) measures are taken, essentially without using mechanical safety valves, which prevent the pressure in the said bleaching vessel, or an affiliated part, from being allowed to exceed a certain set point.

Abstract: The present invention relates to a digester for continuous cooking under raised pressure and temperature of fibre material in a vertical digester (1), where input of fibre material and cooking liquid takes place at the top of the digester, withdrawal of spent cooking liquor is carried out from at least one digester screening arrangement (1D) between the top and the bottom of the digester, and fibre material is fed out from the bottom (1C) of the digester, wherein the digester (1) is fitted with an additional digester screening arrangement (2) located at less than about 1.5 meters above the lowest screening arrangement (1B) of the digester so that the temperature in all the participatory cooking zones in the digester can be kept at essentially the same temperature level.

Abstract: An automated system and method for measuring the residence time of wood pulp as it moves through various stages of processing in a pulp mill. A tracer compound comprising a neutral salt of a halogen is introduced into a first location in the path of the pulp slurry; at a second location an automated detector detects the concentration of tracer compound over a time period; a controller relays a voltage signal from the detector to a processor which uses a calibration curve to integrate tracer concentration over time and thereby derive pulp residence, between the first and second locations.

Abstract: Methods for discharging spent cooking liquors from a batch digester containing cooked lignocellulose-containing material in spent cooking liquor are disclosed, including supplying a first portion of washing liquid to the digester to displace a first portion of the spent cooking liquor at a temperature and dry solids content which substantially corresponds to the temperature and dry solids content of the spent cooking liquor at the end of the batch digestion, supplying a second portion of washing liquid to the digester to displace a second portion of the spent cooking liquor having a temperature and dry solids content substantially lower than that of the spent cooking liquor in the digester, and maintaining the first and second portions of spent cooking liquor separate from each other. Methods of producing kraft pulp in batch digesting processes using this method are also disclosed.

Abstract: A mill for the processing and production of wood pulp is contained substantially entirely within a single, integral structure that defines a unitarily-covered space substantially bounding and enclosing the mill. The mill includes a main control room or station for overall monitoring and control of pulp processing operations in the mill, the main control station being disposed substantially centrally within the covered space, and a plurality of processing stations at which various pulp processing operations take place in a generally sequential manner or order.

Abstract: A process and apparatus for controlling and/or regulating a solids-liquid separation process, such as in a dewatering or drying device includes at least two photodetectors, each associated with a light source, a detector to detect light of the associated light source reflected from the surface of the solids-liquid mass, a controller generating an output signal as a function of the detected light and converting and processing the output signals of the photodetectors into correcting variables for controlling and/or regulating at least one process parameter of the separation process. At least one of the photodetectors is associated with at least one second photodetector for detecting light reflected into the photodetector at an angle, preferably an angle of 30.degree. to the main direction of reflection. The output signals of the photodetectors are advantageously processed into correcting variables for the step-wise adjustment of the at least one process parameter to optimize the separation process.

Abstract: In an apparatus and method for controlling the position of a rotor in a truncated conical feeder for feeding a feed comprising a lignocellulose material and an alkaline cooking liquor to a pulping digester; the position of the rotor in the feeder is detected by a rotor position detector; and a signal indicating the detected position is input to a control device; the rotor is moved at a distance of 0.03 to 0.4 mm every 0.3 to 4 days by driving an electric motor and moving a shaft of the rotor in response to a signal, when the rotor is moved a predetermined distance, and the rotor-moving motor is stopped by a signal input from the control device.

Abstract: The invention relates to a method of determining the concentration of sulfide and optionally also of polysulfide in liquors and solutions of smelt deriving from the sulfate process. According to the method, the concentrations are determined by measuring the light absorption of the liquor or the solution in the ultra-violet range. According to one preferred embodiment, the method is applied to determine the degree of reduction in sulfate liquor and smelt derived from burning liquor, wherein the concentrations of sulfate, thiosulfate and optionally sulfite and/or carbonate are determined by measuring the light absorption of the liquor or the solution in the infrared range, whereafter the degree of reduction is calculated from the measuring data obtained.

Abstract: A method and apparatus supply ozone containing gas under superatmospheric pressure to an ozone delignification device. The speed of a water ring compressor is controlled so that it compresses as much ozone gas per unit time at desired superatmospheric pressure as the ozone delignification unit utilizes, with essentially no excess. The ozone containing gas is fed from the water ring compressor through a separator buffer tank which levels out pressure pulses and separates cooling water from compressed ozone gas prior to the gas entering the ozone delignification unit. The gas passes through a control valve controlled by a mass flowmeter which senses the amount of cellulose pulp fed to the ozone delignification unit. The speed control of the compressor may be provided by a differential pressure controller connected across the control valve.

Abstract: A formation control method and apparatus in which an image is emitted from a light source and transmitted through a predetermined area of paper an captured by a camera to be displayed as transmitted light image on a display of an image processing computing element, the transmitted light image displayed on the display being image-analyzed to obtain formation factor for quantification of the formation, J/W ratio and the like being optimized by fuzzy control using membership functions based on said formation factor so as to improve the formation.

Abstract: A flat bed, Fourdrinier-type, countercurrent washer for cellulosic pulp incorporates a pressing section at the downstream end thereof which includes the couch roll and additional rolls that carry out multiple mechanical pressing operations on the pulp after it has been subjected to multiple stages of displacement washing without mechanical treatment. As a result, where such washers without mechanical pressing deliver pulp of a consistency of the order of 15% solids, this washer increases the pulp consistency to as high as 40% while correspondingly increasing the effectiveness of the washing operation as a whole.

Abstract: A method is disclosed for controlling a desired chemical dosage to a stream of cellulosic pulp heated by the addition of steam wherein the pulp flow rate is determined indirectly by measuring the pulp temperature after steam addition and calculating the pulp flow rate by heat balance. Changes in pulp flow rate are reflected by changes in pulp temperature at known steam addition rates, and the chemical flow rate is adjusted accordingly to maintain constant chemical dosage. The method is particularly useful in controlling oxygen dosage in oxygen delignification and bleaching processes.

Abstract: A direct monitoring and control method is provided for on-line measurement of effective alkali, carbonate, sulfate and thiosulfate concentrations in process liquors for the production of kraft pulp. The control method eliminates frequent sampling, and the need for frequent equipment maintenance. The method includes the steps of withdrawing samples of a liquor from the kraft manufacturing process, subjecting the samples to infrared spectrophotometry at predetermined wave numbers to produce peak-absorbance measurements relative to a background spectrum of water, determining peak absorbance for different alkali concentrations, correlating relationships between the peak-absorbance measurements of samples with the peak absorbance for different alkali concentrations to determine optimum effective alkali in the samples, and controlling at least one process parameter to obtain effective alkali of the liquor.

Abstract: To decrease the sulfur emissions of a sulfate cellulose mill, black liquor is heated before the last effect of the evaporation at a temperature higher than the cooking temperature of the sulfate cook and the sulfidity of white liquor is adjusted by adjusting the temperature and/or retention time of the heat treatment so that a predetermined amount of sulfur compounds are separated from the gaseous black liquor. Preferably, the sulfur containing gas is thereafter divided into different fractions and separately combusted.

Abstract: A fluid is continously processed by being fed to the top of a hydraulic downdraft tube (15) which forms a downdraft column which is of a height such that the pressure at the bottom thereof will approximately be at the pressure necessary to dissolve sufficient oxygen in water to control the surgical oxidation of lignite in paper pulp in concert with proper retention time and predetermined temperature high and low limits. The fluid is conducted to the bottom of the tube (15) and treated in a variable depth reaction zone (25) in which turbulence is introduced with an injected mixture of reactant and non-reactant gases. The result is that lignite in the pulp will be bleached releasing a controlled proportion of heat to the fluid which enhances the reaction. The treated fluid is fed into an updraft annulus (26) wherein the reaction is selectively restrained by variable depth cooling device (21) and the non-reacting gas is allowed to expand inducing controlled updraft velocities.

Abstract: In a flat bed, Fourdrinier-type, countercurrent washer for pulp, the opportunities for the development of foam are minimized by "wet" operation of the washer so that the pulp mat remains essentially full of liquid as it passes from each washing zone to the next. Special provision is also made for compensating for drainage at too slow a rate in one washing zone by bypassing some of the flow of washing liquid to that zone so that it is delivered to the zone upstream therefrom. An additional feature is the provision of controls over the flow of drained liquid from one or more of the receptacles therefor so that any solid particles floating on the top of that liquid in the receptacle are delivered to the countercurrent flow which ultimately reaches the evaporator.

Abstract: Extended delignification of kraft pulp in a pressure diffuser allows a pulp mill with a digester (e.g. continuous digester) to increase its production capacity without building a new line, or to decrease its demand in its bleach plant, or to increase the strength of softwood pulp it produces. Comminuted cellulosic fibrous material is kraft cooked to produce kraft pulp having a blow temperature over about 300.degree. F. The pulp is diffusion treated in the first stage of a pressure diffuser to replace the water around the pulp with delignifying liquor. The liquor has a dissolved lignin concentration of less than 12% (optimally less than about 4%), has an effective alkali concentration of at least 2 gm/l (preferably 8-55 gm/l), and a temperature of at least about 300.degree. F. Treating the pulp with the delignifying liquor significantly reduces the K-number (e.g. on the order of about 5). After extended delignification, the pulp is washed in subsequent stages of the pressure diffuser.

Abstract: A procedure for determining the composition of a wood chip mix dispensed in alkaline delignifying processes, particularly in sulphate and soda/anthraquinone cooking, with the aid of the monomeric compounds produced in connection with the cooking and dissolved in the waste liquor. As taught by the procedure, a cooking liquor sample is taken in the cooking process, this sample being chromatographically analyzed. On the basis of the content proportions of certain compounds analyzed by substance groups, the composition of the dispensed wood chip mix is determined, and at the same time information is gained for optimating the conditions applied in the cooking process.

Abstract: In a pulp washing system where there is substantially constant average weight of pulp mat (on a dry pulp basis), washing uniformity is improved by controlling the weight per unit area of liquid alone or liquid and pulp combined in the pulp mat across its width to obtain a substantially constant distribution of selected property in the pulp mat across its width. This is accomplished by steps comprising determining the property in a plurality of selected locations across the width of the pulp mat and also the average value of the property across the width and controlling dilution liquid input into the headbox in response to the determination to produce of substantially constant distribution of the property across the width of the mat.

Abstract: A procedure for monitoring alkaline delignification, in particular kraft cooking, of wood or other cellulosic material with the aid of the mutually relative concentrations of the monomeric lignin hydration products which are formed in connection therewith and are dissolved in the spent liquor. According to the procedure, a sufficient number of representative spent liquor samples is taken during the cooking process which are analyzed by gas chromatography. On the basis of the concentration proportions of certain compounds which have been analyzed, that time period is determined in each instance which is required to reach the desired degree of delignification.