Abstract: The invention relates to an apparatus and method for measuring the properties of fiber pulp. The apparatus used in the method comprises a batching vessel (1) for measuring the volume and temperature of the sample; a filtering chamber (3, 5) by means of which the sample is filtered on a wire (4) by means of a pressure difference, and an air flow is produced through the pulp cake formed during the filtration. The apparatus has, next to the filtering chamber (3, 5), a raisable vertical central shaft (8), which can be rotated in steps, and holders for transferring the wire (4) together with the pulp cake to positions around the central shaft (8) for the functions, and for returning the wire (4) into the filtering chamber.

Abstract: A method and apparatus for making paper by refining fibrous stock. The stock is passed through an adjustable refining means and a sample of the refined stock is analyzed using a fibre fineness distribution analyzer to produce, over a range of fibre widths, counts of the number of fibres in the sample which have a selected fibre width. Fibre width is plotted against fibre count at intervals of 1 .mu.m over the range of from 7 .mu.m to 64 .mu.m to obtain a fibre fineness distribution curve. The fibre fineness distribution curve is compared with a reference fibre fineness distribution curve obtained by the prior analysis of stock known to have produced paper of desired quality. The refining means is then adjusted to produce a stock the analysis of which produces a distribution curve substantially the same as the reference curve.

Abstract: A method of determining the properties of fiber pulp by separating a batch of a predetermined volume, by measuring its temperature, and by filtering water from it by means of a pressure difference. In accordance with the present invention, substantially all the water is filtered off from the pulp mixture, an air flow is produced through the filtered pulp cake by means of a pressure difference, the resisting effect of the pulp cake on the flow of air is measured, and the pulp cake is weighed, whereafter the properties of the pulp are calculated on the basis of the measurements, from mathematical models developed for this purpose.

Abstract: A radiation sensor provides on-line measurement of web MD/CD fiber orientation ratio, formation indexes of multiple spatial frequencies, and optical density as it relates to basis weight. A light source illuminates one side of a substrate to be measured. The radiation passing through the substrate is detected by a pair of detectors having fields of view along narrow strips which are perpendicular to each other. The combined field of view is scanned in a repetitive pattern traversing an area on the substrate to be analyzed. The detector outputs are processed to provide fiber orientation ratio, formation, and basis weight measurements.

Abstract: Immediate and accurate control of a pulp refiner is provided so as to control the degree of refining in the production of mechanical pulp, such as RMP, TMP, and CTMP. The mechanical pulp discharged from a refiner is fluidized by a fluidizing centrifugal pump, the fluidizing action instantaneously removing the pulp latent properties. A sample of the latency-removed pulp is then subjected to a pulp freeness measurement, and that freeness measurement is supplied to a computer. The computer utilizes the freeness measurement, as well as other measurements such as pulp consistency and flow rate measurements, and dilution flow measurements, and in response to the inputs control refiner parameters to ensure that the freeness of the mechanical pulp being produced is within the desired range. The refiner parameters controlled can be the hydraulic plate loading (refining pressure), and/or the tonnage of fiber supplied to the refiner.

Abstract: A method and apparatus is provided for measuring the present and ongoing performance of paper pulp brown stock washers. Black liquor carryover within a washer mat past wash liquor application showers is quantified by determination of and correlation with the mat liquor specific conductivity.

Abstract: The drainage quality of a pulp furnish slurry on a paper machine forming wire is predicted by the drainage tester of this invention by accounting for the effect of drainage through the paper sheet as it forms. The tester can distinguish between fast draining mechanical pulps and slower draining chemical pulps as well as predict the effects various additives will have on drainage. The apparatus includes a screen which separates furnish fibers from the slurry white water in response to a constant volume vacuum pump. Pressure differential as a function of time is recorded producing for any given furnish three distinctive points of inflection on the curve, including a first point of inflection which correlates with the wet line on a paper machine forming wire, second point of inflection which correlates with the dry line on the former and a third point of inflection which correlates with the maximum practicable removal of water from said pad by the typical former vacuum systems.

Abstract: An electro-optical meter for indicating consistency of a liquid slurry, employs a light source and a detector of backscattered radiation. The light is caused to scan the slurry while holding the light intensity and the peak-to-peak value of the detected signal constant. The distribution of backscattered light is measured and the minimum to maximum intensity of backscattered light is controlled.

Abstract: A standpipe is connected into a fiber processing system such as a pressurized stock line of a paper making system, containing refined stock, or unrefined pulp, at operating consistencies. Automatic controls cycle a measurement chamber, in the standpipe, through intake measure and exhaust. An imperforate plate mounted across the measurement chamber has at least one hole of predetermined cross dimension, or diameter, substantially equal to the relative length of fiber desired. Automatic timing establishes a set intake time for slurry, or suspension, to pass through the hole and contact lower and/or upper liquid level sensors, or other level indicators, in the chamber. Instantaneous, periodic read out is provided to indicate "too short", "too long" or "correct length" with each cycle. Differential pressure, across the hole, or orifice during measure, as well as approach velocity, is appropriately controlled.

Abstract: A method is described for monitoring and determining the degree of completion, pulp yield, and residual lignin content in a pulping or delignification reaction. The system provides an on-line, real time, closed loop process control system for the reaction of a known quantity of wood in process liquor. The desired pulp yield is achieved by sampling the liquor during the reaction; determining the total organic carbon content of the sampled liquor; and calculating the degree of completion of the reaction and pulp yield from the process liquor total organic carbon content determination using an appropriate mathematical model. The mathematical model is based upon conservation of carbon mass in the wood or pulp and liquor during the reaction, and includes a conservation of mass equation in which the total organic carbon in the sampled liquor substantially equals the total carbon in the starting quantity of wood or pulp less the total carbon in pulp wood residue at the time of sampling the liquor.

Abstract: In the causticization part of the sulphate process the conductivity of the green liquor and the white liquor is measured, and the specific gravity of the green liquor is measured to determine the TTA-value (total titratable alkaline). The measuring values are registered on-line in a data processor calculating the required change of the supply of quicklime or green liquor to the slaker and/or the required change of the TTA-value of the green liquor for the control of the properties of the white liquor.The measurings carried out provide the basis of a control of the properties or composition of the white liquor, whereby the causticization process forming part of the sulphate process is simplified and made more efficient. The drawbacks associated with an insufficient control, e.g. calcification and the consequent poorer filtratability of the white liquor as well as a too high content of calcium in the white liquor, cause calcification of filters, pipes, pumps, and digesters etc.

Abstract: In the formation of a paper web from stock fed to a Foudrinier wire, the Zeta Potential is an important parameter. A measure of Zeta potential is made by measuring the streaming potential developed in a vertically-arranged cell having a horizontal mesh therein on the underside of which a pad of fibres and fines is formed by pumping stock into the lower part of the cell. Electrodes located in the cell above and below the pad are used to obtain a measure of streaming potential at a given pressure differential across the pad. A pressure transducer is mounted in the lower part of the cell. Corrections are made for temperature and conductivity by sensors in the stock feed path to the cell. A microprocessor control and measuring circuit is disclosed which sequences valves for controlling the flow of stock and flushing fluid to the cell and which measures the relevant parameters.

Abstract: Methods of measuring the crill content of pulp suspensions are disclosed. The methods include passing a first light radiation, preferably ultraviolet light, having a wavelength comparable to the particle diameter of the crill, through the pulp suspension, passing a second light radiation having a wavelength longer than the first wavelength but shorter than the mean pulp diameter through the pulp suspension, collecting both light radiations after they have transilluminated the pulp suspension, and measuring absorbencies for both of these collected light radiations so that the crill content can be determined therefrom.

Abstract: In the cycle for production of pulp by the Kraft process, the active alkali concentration range in black liquor is monitored and adjusted. In recognition of the effect of the proportion of the active alkali to the other contents of the black liquor on a dry solids basis, active alkali is adjusted to control various performances of the evaporators and combustion within the recovery furnace.

Abstract: The specific surface distribution of a pulp may be obtained by fractionating the pulp in a hydrocyclone means into an overflow and an underflow fraction and measuring the specific surface of each of the fractions and the amount of each of the fractions and based on a cumulative normal distribution relationship of cumulative weight fraction as a percent of feed to specific surface, determining the specific surface distribution for said pulp.Also disclosed is a method and apparatus for determining the specific surface of a pulp sample by measuring the light scattering characteristics to obtain a turbidity measurement of the pulp sample, measuring the consistency of the sample and determining the specific surface of said pulp based on the relationship of specific surface to the turbidity measurement for the measured consistency of the pulp.

Abstract: A method of treating medium consistency paper pulp or the like with a treament gas, such as oxygen, is provided to achieve uniform treatment results. The treatment gas is added to the pulp in finely distributed small bubbles, and the density of the suspension is measured at at least one moment, or the average density is measured during at least one time period. The temperature and the pressure of the suspension corresponding to the density measurements are determined, and the rest gas content of the substance is calculated at the actual moments or time periods based upon the measurements in the preceding steps. The gas consumption is then calculated as the difference between the quantity of gas added, and the residual gas quantity, or between two residual gas quantities. The gas addition step is controlled based upon the calculated consumption to obtain substantially uniform treatment results.

Abstract: A pulp sampling device for combining pulp and water to form a pulp suspension and circulating the suspension until an exact volume of a sample of the suspension has attained a targeted meter reading of consistency and concentration which volume of pulp can be used for Kappa number determination or like tests.

Abstract: Apparatus for inspecting pulp or similar material arranged to flow in a sheet 10 past an inspection station, comprising a row of photosensitive devices 14 arranged to receive light reflected from or transmitted through the material, circuit means 30 receiving the output signals from the photosensitive devices and providing a defect signal when an inclusion in the pulp passes the inspection station, and integrating circuitry 32 adapted to integrate the defect signal with respect to time thereby to measure the total equivalent black area of the sheet 10. To allow for integration over a long travel of the sheet, the integrating circuitry includes an integrator 32, and a pulse generator 34 adapted to receive the output of the integrator and to generate an output pulse when the result of the integration reaches a predetermined magnitude. The integrator is reset to zero on the occurrence of each said pulse, and a counter 36 is arranged to count the pulses generated by the pulse generator.

Abstract: A continuous process for wet oxidation of aqueous liquor containing combustible matter using oxygen or oxygen enriched gas. An inert diluent gas is injected into the aqueous liquor or reactor off-gas such that oxygen in the gas phase is diluted by the sum of generated water vapor, produced carbon dioxide and injected inert gas to a concentration less than required for spontaneous combustion at every location in the system having surfaces not continually exposed to a continuous liquid water phase.

Abstract: A method and apparatus for liberating the latent properties of a mechanical pulp is disclosed. The method is a laboratory technique for sample preparation for further pulp testing. "Latency" is released by recirculating pulp from a pool thereof through a centrifugal pump at a rate of at least four times per minute for the period required to release all the latent properties of the pulp sample ("Latency"). This depending on the rate of circulation may be completed in as little as one minute.

Abstract: A method is provided for controlling the supply of delignifying and/or bleaching chemicals in the continuous delignification and/or bleaching of lignocellulosic material such as wood and pulp in a through flow delignification and/or bleaching stage which commprises admixing the lignocellulosic material with delignifying and/or bleaching chemicals and flowing the lignocellulosic material under delignifying and/or bleaching conditions through the stage while controlling the addition of the delignifying and/or bleaching chemicals according to the ratio of the quantity of delignifying and/or bleaching chemicals consumed to the quantity of delignifying and/or bleaching chemicals originally charged, referred to hereinafter as relative consumption, the time and the temperature in a manner to maintain substantially constant the relative consumption of delignifying and/or bleaching chemicals at a predetermined time by the lignocellulosic material during flow through the stage.

Abstract: A method and a device for determining the lignin content in pulp by measuring the temperature increase on chlorination of a pulp sample with well-defined moisture content. The pulp sample is dewatered by pressing and simultaneously being blown through by a gas having low oxidization activity, subsequent to which the maximum temperature increase is registered when the pulp sample is blown through by chlorine gas.

Abstract: A method and an apparatus for determining the fibre length distribution by weight of a pulp and a method and apparatus for determining absolute consistency are disclosed.The fibre length distribution is obtained by dividing the flow of a pulp sample into two separate flows, fractionating each of the flows by a screen into a retained and a through fraction, the screens being of different mesh sizes, measuring the amounts of each of a selected one of said retained or through fractions and determining, based on the cumulative normal distribution relationship of cumulative retained fraction in % of feed to fibre length, the fibre length distribution of the pulp sample.

Abstract: Methods and apparatus for determining the particle size distribution with respect to selected fraction classes in the direction of flow of a medium are provided in accordance with the teachings of the present invention. A plurality of measuring configurations are employed to pass light through the medium to be measured and to detect the light transmitted therethrough. Each measuring configuration exhibits different resolution with respect to one another and particle size distribution for selected fraction classes is determined as a function of measuring signals derived by each of the plurality of measuring configurations from the transmitted light detected during a run of the medium and sensitivity coefficients of the measuring signals. The sensitivity coefficients employed are dependent upon the associated measuring configuration and fraction class. Thus rather than counting particles per se a measure of the concentration in each fraction class is obtained.

Abstract: The specific surface distribution of a pulp may be obtained by fractionating the pulp in a hydrocyclone means into an overflow and an underflow fraction and measuring the specific surface of each of the fractions and the amount of each of the fractions and based on a cumulative normal distribution relationship of cumulative weight fraction as a percent of feed to specific surface, determining the specific surface distribution for said pulp.Also disclosed is a method and apparatus for determining the specific surface of a pulp sample by measuring the light scattering characteristics to obtain a turbidity measurement of the pulp sample, measuring the consistency of the sample and determining the specific surface of said pulp based on the relationship of specific surface to the turbidity measurement for the measured consistency of the pulp.

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 is provided for continuously washing fibrous suspensions in aqueous suspending liquors containing dissolved impurities to remove such impurities by exchanging aqueous suspending liquid substantially free from such impurities for the aqueous suspending liquor, which comprises washing fibrous material of the suspension in aqueous suspending liquid substantially free from dissolved impurities; and forming a washed fibrous suspension in such liquid; withdrawing aqueous suspending liquor containing dissolved impurities; diluting the washed fibrous suspension by adding aqueous suspending liquid substantially free from dissolved impurities; measuring the volume amount of such diluting aqueous suspending liquid added; measuring the volume amount of diluted washed fibrous suspension; and then adjusting the volume amount of wash liquid added to maintain substantially constant the difference between the amount of wash liquid added and the liquid content of the undiluted washed fibrous suspension.

Abstract: A method and apparatus are disclosed for obtaining an indication of fibre flexibility by spraying a pulp sample of preselected average fibre length against the bottom of a horizontal screen having a negative pressure thereabove whereby a selected pressure drop is applied across the screen and the pulp sample is divided into a retained and a passed fraction. The flexibility index is obtained by a ratio indicative of the fibre mass in the passed fraction or retained fraction to the fibre mass in the feed.

Abstract: A process for continuously monitoring and controlling a continuous process for digestion of cellulose utilizing a computer which is programmed to determine (1) the mass of wood being fed to the digester from measurements of the density of the wood slurry feed, the density of the liquid and the total flow of slurry, (2) the mass of wood being withdrawn from the digester from measurements of the density of the pulp slurry, the density of the liquor and the total flow of slurry, (3) the correct amount of fresh digester liquor to be added concurrently with the wood feed and (4) amount of water wash and makeup digester liquor to be fed to the reactor. The computer can also be programmed to control the temperature in the reaction zone of the digester.

Abstract: Process is provided for controlling the degree of causticization of white liquor in its preparation from green liquor by the addition of calcium oxide, which comprises determining the sodium carbonate concentration of green liquor fed to the causticization; determining the sodium carbonate concentration of white liquor resulting from the causticization; and controlling the degree of causticization within a predetermined range while taking both sodium carbonate concentrations into account, so as to maintain the degree of causticization of the white liquor within the range despite variations in sodium carbonate concentration of the green liquor and variations in calcium oxide content of the calcium oxide added for causticization.

Abstract: A sample of mineral fibers is dispersed in a liquid and viscosity of the dispersion is measured. The viscosity value provides a rapid measure of the length of the fibers. The measurement is sufficiently rapid that adjustments can be made to operating conditions during a production run to ensure the production of fibers of uniform length characteristics.

Abstract: A pulping digester contains a liquid digesting medium and wood chips dispersed in the medium. The level of the wood chips in the digester is normally below the top of the digester. As chips and digesting medium are fed to the digester and as pulp and digesting medium are withdrawn from the digester, the chip level will vary dependent upon the net addition of chips and withdrawal of pulp. The variable location of the chip level, or chip height, is determined by positioning a temperature sensing means in the upper portion of the digester above the normally desired chip level. The temperature sensed by the sensing means is displayed to and monitored by the digester operator. As the chip level rises toward the temperature sensor, the sensed temperature will fall until the chip level rises above the location of the temperature sensor, after which the sensed temerature will rapidly increase as the chip level continues to rise above the location of the sensing means.

Abstract: Relative shive incidence in a production flow line of paper pulp is continuously sampled and measured by means of a continuous flow, fiber induction device located within the production line to extract a diluted sample of fiber flow therein. The diluted sample is directed through a windowed conduit section for photodetection of particles therein. Particle caused pulses are discriminated by amplitude relative to a reference scale to distinguish shive particles from acceptable fiber particles. Two pulse trains are developed simultaneously: one pulse train for shive pulses and the other pulse train for particle flow including shives. Both pulse trains are rate determined by counting the number of pulses in a fixed interim of time identical to both. The two pulse rates are then combined to develop a dimensionless ratio of shive incidence or percentage within the total fiber stream.

Abstract: A method and apparatus for the delignification of cellulosic fiber material to minimize the amount of reject material in the final pulp produced. The fiber material is digested, washed, oxygen delignified, and passed through a screening stage to provide a main pulp stream, and a reject stream from the separation stage. The flow and consistency of the separated reject material is determined, the reject material is refined, and sufficient chemical is added to the separated reject material, based upon the flow and consistency thereof, so that subsequent delignification of the reject material may be effected. This may be accomplished either by passing the reject material through a separate oxygen delignification stage and then returning it to the main pulp stream, or adding caustic to it and soaking it in a soak tank for predetermined period of time, and then returning it to the main pulp stream before the oxygen delignification stage therein.

Abstract: A method of controlling the amount of a liquid shower flow introduced onto a slurry mat such as a pulp mat which is undergoing incomplete liquid separation on a vacuum filter drum. The flow rate of the liquid being discharged with the slurry mat is determined by a capacitance measurement which is taken after the slurry mat has passed to a point on the filter means where liquid separation no longer occurs. The shower flow is controlled by a correlation of the flow rate of the liquid in the slurry mat with the rate of slurry mat transfer from the vacuum filter drum and the necessary liquid shower flow as expressed by a dilution factor.The present control system may be combined with secondary apparatus to measure the flow rate and thickness of the total slurry mat in order to determine by correlation the slurry mat consistency, the rate of solid material production from the slurry mat and the amount of air contained in the slurry mat.

Abstract: In a process for delignifying wood pulp with oxygen, a pulp slurry and oxygen are introduced into an elongated reactor having a plurality of gravitational fall zones at which oxygen is dissolved in the liquid phase of the slurry. The length of the reactor is sufficient to provide the residence time required for delignification reactions. Alkali is added in controlled quantities along the reactor length in response to sensed slurry pH to maintain a predetermined slurry pH throughout the reactor. The oxygen treated slurry discharged from the reactor is separated into pulp and hot recycle liquor, the latter being utilized to effect thermal, chemical and water economies.

Abstract: A direct-steamed laboratory minidigester and a method of operating it are disclosed. This unit may be used to predict process parameters, e.g., yield and Kappa number, for operation of commercial direct-steamed digesters. Runs may be made rapidly and with small quantities of wood and chemicals. A plurality of units may be operated in parallel to generate replicate data points for statistical analyses or operated simultaneously, each under different conditions, to screen process variables, e.g., chemical charge, wood furnish, pressure, temperature, steam rate, and cooking time.

Abstract: A method is provided for controlling the addition of active chemical for delignifying and/or bleaching cellulose pulp suspended in an aqueous liquor containing at least one chemical reactive with such active chemical, which comprises determining the amount of active chemical consumed by the chemical reactive with the active chemical in the liquor; adding the active chemical to the cellulose pulp suspension; and then after a predetermined time interval determining the amount of active chemical consumed by the chemical and cellulose pulp reactive with the active chemical in the liquor; from these determinations determining the amount of active chemical consumed by the pulp; and then carrying out the delignification and/or bleaching with an amount of active chemical adjusted according to the amount of active chemical consumed by the pulp.

Abstract: A process for continuously digesting cellulosic fibrous material wherein the degree of delignification of the cellulosic fibrous material in the digestion zone is continuously determined and monitored by determining the exothermic heat of the delignification reaction taking place in the digester. The exothermic heat of the delignification reaction is determined by measurements of the temperature rise occurring in the delignification zone and the heat capacity of the cellulosic material and digesting liquor.

Abstract: An improved process for continuously monitoring and controlling a continuous process for digestion of cellulose utilizing a computer which is programmed to determined (1) the mass of wood being fed to the digester from measurements of the density of the wood slurry feed, the density of the liquid and the total flow of slurry, (2) the mass of wood being withdrawn from the digester from measurements of the density of the pulp slurry, the density of the liquor and the total flow of slurry, (3) the correct amount of fresh digester liquor to be added concurrently with the wood feed and (4) amount of water wash and makeup digester liquor to be fed to the reactor. The computer can also be programmed to control the temperature in the reaction zone of the digester.

Abstract: A control system and a process is disclosed for a continuous wood chip downflow digestion system. The system maintains chip level in the top of the digester and maintains a consistency in the ratio of chips to liquor in the blowline thus allowing the system to run without constant operator attention. The system comprises a means for measuring the level of chips at the top of the digester and producing a level index over a predetermined time. This level index is compared with a preset level index and an error signal produced which operates a speed control means within preset limits for a rotating scraper feeding into the blowline. There is also provided a means for measuring the feed rate of chips to the digester, and a summating means for adding a predetermined ratio setpoint for the feed rate of chips against a flow in the blowline, to an integral of the error signal above or below a preset range to produce a summated ratio.

Abstract: A process and apparatus are provided for controlling the supply of aqueous suspending liquid in continuously washing fibrous suspensions in aqueous suspending liquors containing dissolved impurities, to remove such impurities by exchanging aqueous suspending liquors substantially free from such impurities for the aqueous suspending liquor, which comprises washing fibrous material of the suspension in aqueous suspending liquid substantially free from dissolved impurities, and forming a washed fibrous suspension in such liquid; withdrawing aqueous suspending liquor containing dissolved impurities; diluting the washed fibrous suspension by adding aqueous suspending liquid substantially free from dissolved impurities; determining the amount of dissolved impurities remaining with the fibrous suspension after the washing has been completed by measuring (1) the volumetric flow rate of the washed suspension; (2) the liquid content of the washed suspension; and (3) the content of dissolved impurities in the suspending

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: Wood pulp is bleached with chlorine dioxide gas. The gas is obtained by feeding a chlorine dioxide solution to a stripper. Shredded or fluffed pulp is exposed to a controlled amount of chlorine dioxide gas for a time period sufficient to obtain the required pulp brightness. The amount of unused chlorine dioxide gas is continuously monitored. The controlled amount of chlorine dioxide gas fed to the bleaching system is automatically adjusted by controlling the amount of chlorine dioxide solution fed to the stripper in response to changes in the amount of unused chlorine doxide gas leaving the bleaching system. Unreacted gases are recycled back to the stripper in response to the concentration of chlorine dioxide gas conducted from the stripper to the reaction area.

Abstract: A method of preventing a physical explosion caused by the contact of water with a molten material such as molten smelt and molten metal by the addition of a porous, high surface area powder which is coated with an anti-wetting agent. The material sinks through the water layer to the interface between the water and the molten material carrying air or gas bubbles with it. The invention is particularly applicable to smelt-water explosion in kraft chemical recovery furnaces.

Abstract: An improved process for gas-phase bleaching of cellulose pulp at high pulp consistency including in series a gas zone space beneath said gas zone for a column of fibrous material, a mixing zone and a dilution zone, wherein a hub body is located centrally at the bottom of the tower and provided with driving means for rotation of the shaft bearing the hub body, and the torque required for rotating the hub body is continuously measured. The rate of dilution liquid is varied inversely with variation in torque thereby maintaining substantially constant the consistency of the diluted fibrous material as withdrawn from the bottom of the tower. The height of the pulp column is measured and kept constant by controlling the withdrawal of diluted fibrous material.

Abstract: A technique for controlling the amount of dissolved material in a slurry liquid stream containing dispersed particulate solids which is being continuously processed in a zone of countercurrent particulate solids separation and washing. Flow rates and conductivity measurements are made on streams entering such zone which are then used to estimate the amount of dissolved material in a starting slurry liquid. Preferably, conductivity measurements are made with electrodeless conductivity measuring probes. The technique is well adapted for use in a brown stock washing system employing a plurality of counterflow washers. The technique can be used for measurement of the quantity of gas in an agitated process stream in such a zone.

Abstract: A process for accurately controlling the intrinsic viscosity of sulfite pulp at the termination of a digestion operation comprising predetermining the duration of digestion time required to obtain a given pulp intrinsic viscosity for a range of initial weight ratios of combined SO.sub.2 to wood, determining during the digestion operation the initial weight ratio of combined SO.sub.2 to wood by measuring the rate of change of absorbance in the digestion cooking liquor and terminating the digestion operation at a time corresponding to the predetermined time required to obtain the given pulp intrinsic viscosity at the aforesaid combined SO.sub.2 to wood ratio.

Abstract: A method and apparatus for filling a treatment vessel with a fiber material -- liquid mixture. A conventional feeder rotor, having a number of pockets extending therethrough, has each pocket thereof sequentially filled with chips-liquid mixture in a first position from a pretreatment vessel. A portion of the liquid is withdrawn from the pocket, and the pocket rotates to a second position wherein the chips-liquid mixture in the pocket is discharged into a digester by a liquid flow. The pocket then rotates to a third position wherein the liquid in the pocket is discharged by admitting a gas, such as steam, under pressure into the pocket (and the pocket simultaneously filled with gas), and then to a fourth position wherein the gas is allowed to expand and be transported to a pretreatment vessel while the pocket is filled with cooking liquor, and thereby is ready to begin another cycle.

Abstract: In a method for examining pulp for the presence of shives therein a suspension of the pulp is passed through a measuring duct with transparent walls and at least one beam of light having a wavelength within the intra-red range from 750 to 950 nm is directed through the measuring duct perpendicularly to the direction of flow of the pulp suspension therein. The intensity of the light beam after its passage through the measuring duct is measured by means of a photo detector and the output signal of the photo detector is analyzed with respect to amplitude variations therein. The measurement is independent and insensitive to the type of pulp.