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: 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 procedure and apparatus for locating faults in the machine elements of a paper machine and in their functioning, wherein variations in the paper characteristics are continuously observed, the periodicity of the variations is recorded and the periodicity of the variations in the paper characteristics is compared with the periodicity in the functioning of the paper machine's machine elements. The apparatus comprises observation members (1-11) for observing the variations occurring in the paper characteristics; synchronizing pick-ups (43-53) disposed on machine elements (13-22) of the paper machine for observing the periodicity of the functioning of said machine elements; a recording means (40) for recording the periodicity of the variations in paper characteristics and the periodicity in the functioning of the machine elements; and a data processing unit (41) for comparing the periodicity of the variations in paper characteristics and that in the functioning of the machine elements.

Abstract: A drainage tester evaluates the reaction pattern of one or more reactions in a paper pulp furnish to predict behavior of the pulp on a paper line. The tester includes a mixing container in which an additive is mixed with the slurry under conditions that prolong the reactions in the container such that they take longer than the same reactions on a paper line. The mixer can also mimic the kinetic conditions (such as mixing by turbulence or passive diffusion) under which the additive is mixed with the furnish on the paper line. A test container has a screen bottom that separates furnish solid from slurry water by developing a pressure differential across the screen. An intermediate container is positioned between the mixing container and test container to provide a constant hydrostatic head on furnish transferred to the test container.

Abstract: A method and apparatus are provided for analyzing the elemental constituents of fluid streams in the cellulose pulp industry, such as liquid with dissolved solids for treatment of cellulose pulp or from the treatment of cellulose pulp, or liquid slurries including comminuted cellulose material. Continuous on-line elemental analyses are made of one or more such fluid streams, and at least the partial elemental make-up (either material, or of elements added for marking) of the streams determined. Then one or more processes for acting on the fluid streams are controlled to optimize the processes as a result of the analyses made. The invention is particularly useful in the continuous on-line analysis of black liquor utilizing prompt gamma neutron activation analysis, and controlling the operation of an evaporator or recovery boiler.

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: A control system for a countercurrent pulp washing process in which the pulp is formed as a pulp mat on at least one moving filter surface and the mat is supplied with rinse water to replace water in the pulp mat thereby reducing the soda loss in the mat before it is removed from the filter surface. The process is characterized by at least one predictable process variable including dissolved solids retained in the pulp mat. The system comprises a trainable neural network having a plurality of input neurons having input values applied thereto and output neurons for providing output values and means for training the neural network to provide predicted values for the predictable process variables.

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 method and appartus for measuring lignin concentration in an undiluted sample of wood pulp or black liquor comprises a light emitting arrangement for emitting an excitation light through optical fiber bundles into a probe which has a sensing end facing the sample. The excitation light causes the lignin concentration to produce fluorescent emission light which is then conveyed through the probe to analyzing equipment which measures the intensity of the emission light. Measures are taken to maximize the emission light intensity which is due to lignin concentration and distinguish it from background and interfering light. The fluorescent light intensity is found to drop off in a predictable manner with increased lignin concentration.

Abstract: A method and apparatus for measuring lignin concentration in a sample of wood pulp or black liquor comprises a light emitting arrangement for emitting an excitation light through optical fiber bundles into a probe which has an undiluted sensing end facing the sample. The excitation light causes the lignin concentration to produce fluorescent emission light which is then conveyed through the probe to analyzing equipment which measures the intensity of the emission light. Measures aThis invention was made with Government support under Contract Number DOE: DE-FC05-90CE40905 awarded by the Department of Energy (DOE). The Government has certain rights in this invention.

Abstract: A method for regulating the sodium carbonate concentration of a green liquor in the dissolving tank of the Kraft recovery process by measuring the conductivity of the green liquor from the dissolving tank, measuring the conductivity and flow rate of a weak wash solution being added to the green liquor in the dissolving tank, using these measurements to determine the sodium carbonate concentration of the green liquor in the dissolving tank, and adjusting the volume of the weak wash solution being added to the dissolving tank in response to changes in the concentration of sodium carbonate in the green liquor so as to maintain the concentration of sodium carbonate in the green liquor at a predetermined, preferably constant, level.

Abstract: A process and an apparatus capable of removing and/or transforming lignin or its degradation products present in material containing lignocellulose. In the present process, a redox potential is set between 200 and 500 mV by the addition to an acid aqueous solution, which contains lignitic raw materials, of oxidizing agents and/or reducing agents and/or salts and/or phenolic compounds. The lignin degrading reaction and its attendant simultaneous bleaching effect is initiated by the addition of enzymes, microorganisms, animal or plant cells. Continuous stirring allows the reaction to be maintained for several hours at a value that fluctuates about a constant redox potential value, and a constant temperature.

Abstract: A method for measuring extremely low concentrations of non-aqueous constituents or chemicals in a water/matrix, including differentiating between pulp fines and extremely low concentrations of individual chemicals in a water/cellulose matrix such as occur in papermaking. The water/matrix is exposed to the near-infrared spectrum from 1000 to 2500 nm to produce a recorded voltage that is directly proportional to the absorption by the non-aqueous constituent. The amount non-aqueous constituent is determined from stored voltage values of incremental additions of the non-aqueous constituent.

Abstract: In a method and apparatus for making a dry sheet-like sample of solid particles from a suspension, a part of the suspension is sampled by a sampling unit as it flows through a pipe or while it is retained in a storage tank, then the sampled suspension is stirred by supplying a compressed air and then dewatered by filtration with vacuum, thereby forming a wet sheet-like intermediate sample of solid particles deposited on a filter. Subsequently, the filter and the intermediate sample deposited thereon are conveyed by an overturning conveyor unit to a drying station while being turned upside down, thereafter intermediate sample is removed from the filter by a sample removing unit, and finally, the wet sheet-like intermediate sample is dried with heat and pressure whereby a dry sheet-like final sample is obtained.

Abstract: A method for regulating the feed and/or combustion conditions of concentrated waste liquors of varying chemnical and physical properties, for their burning in a soda recovery unit, by determining the maximum expansion upon heating of a dry matter particle of the liquor to be fed into the soda recovery unit, and by regulating the feed and/or combustion conditions on the basis of the expansion thus determined. The measure used for the expansion is the ratio of the lignin present in the concentrated liquor to any one or several of the acids present in the concentrated liquor, such as aliphatic acids.

Abstract: An improved method for causticizing the green liquor formed in a kraft paper plant by contacting the green liquor with lime to thereby form white liquor followed by clarifying the white liquor by removing the lime mud therefrom in a clarifier is disclosed wherein the improvement lies in removing the lime mud from the clarifier at a predetermined rate.

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: A method and an apparatus for the automatic determination of the dry pulp content, the infiltration capacity and the wire retention of a pulp suspension. In the method the automatically or manually taken pulp suspension sample is brought to the sample container (2) of the determination equipment (1) located in the immediate neighborhood of the production or the operation process. According to the invention the quantity of the sample in the sample container is measured by weighing, the sample is in case of need attenuated into the processing consistency range, a part of the sample is led to the filter (4), is filtrated in the filter with and/or without a filtering paper, the sample cake obtained is transferred to the desiccator (8) and dried with the desiccator, the dried sample cake is weighed and the test results are written out with the output equipment (11).

Abstract: A system and process for continuously determining the strength of paper sheet material during manufacture includes a plurality of sensors for detecting proxies related to properties such as the strength of individual fibers, length distribution of fibers, quantity of fibers, distribution of fibers, orientation of fibers, number of bonds between fibers, and bond strength of fibers. For a given papermaking machine and paper type, multiple regression analysis is used to determine correlations between the measured proxies and laboratory tests of paper strength. Then, during operation of a papermaking machine, changes in the proxy measures are used to indicate paper strength and to adjust operation of the papermaking machine based upon changes in the strength of sheet material being produced.

Abstract: Coarse wood residues, slivers and shives present in groundwood pulp as obtained in grinders are removed by passing a uniform flow of the pulp suspension containing coarse wood residues and shives from the grinder to a conical crushing and beating refiner having two treatment zones with a stationary part and a rotary part for reducing all wood material present in the suspension to free fibers, while measuring and controlling the freeness of the pulp within selected limits by controlling both the power input to the grinder and the power input to the conical crushing and beating refiner, and the degree of beating of the pulp, obtaining groundwood pulp having a low shives content and superior strength properties, at a low energy consumption.

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 method and apparatus for controlling the delignification process by monitoring and minimizing variations in the Kappa Number and the digester residual chemical concentration. A parameter representative of the H factor for the delignification process and a measurement of the initial chemical concentration are utilized to produce signals representative of the actual Kappa Number and the residual acid concentration in the digester. The expected perturbations in Kappa Number and the residual chemical concentration are compared with target values for same to produce estimated errors due to mismatch which are compared with actual measured errors for these parameters to produce compensated control errors for same.

Abstract: A system and method to continuously determine the pulp consistency in the discharge blowline (112) of a continuous pulp digester (100) having a gamma gauge (116) disposed adjacent to the blowline (112) for continuous measurement of the intensity of gamma radiation attenuated by the pulp slurry passing through the blowline (112), a density gauge (118) disposed adjacent to a cold blow liquor line (102) for continuous measurement of the density of the cold blow liquor in the cold blow line (102) independent of variations in the gamma radiation mass-attenuation coefficient of the cold blow liquor in the cold blow liquor line (102), a gamma gauge (120) disposed adjacent to the cold blow liquor line (102) for measuring the intensity of gamma radiation attenuated by the cold blow liquor passing through the cold blow liquor line (102) and a computer (122) for receiving signals output from the first gamma gauge (116), the density gauge (118) and the second gamma gauge (120) indicative of intensity of gamma radiation a

Abstract: A method for measuring the chemical content of bleaching liquor within the cellulose pulp industry, in which a sample of the bleaching liquor is brought together with one or more reagents, of which at least one is chemiluminescent so as to result in the emission of light, and the intensity of the light is determined as a measurement of the chemical content.

Abstract: An inert gas such as helium is employed as a tracer gas in a pulp and paper mill to determine the utilization of oxygen by an aqueous cellulosic pulp particularly, as well as other parameters, in an oxygen delignification or extraction in which oxygen is dissolved in the pulp and reacted to solubilize lignins and reduce the requirement for chlorine-based bleaching chemicals.

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.

Abstract: A procedure for controlling cellulose digestion by measuring activity of chemicals essentially influencing the cellulose digestion and which are present in a cellulose digester. Feeding of chemicals to be added into the cellulose digester is controlled on the basis of the measurement results. The measurement is carried out by placing, in the cellulose digester, one or several measuring electrodes and reference electrodes, and a current-supplying counterelectrode. Current is supplied to the thus-established circuit from a current source, in a manner such that the voltage across the measuring electrode and the reference electrode, in other words the electrochemical potential of the measuring electrode, is substantially constant. The current intensity corresponding to such potential is directly proportional to activity of the chemicals in the cellulose digester. A method for measuring the cellulose digestive activity is also provided in accordance with the present invention.

Abstract: A method of controlling an alkaline pulping process, sulphate pulping in particular. The concentration of the dissolved components as well as the concentration of the recidual cooking chemical are measured. The measurements are carried out by means of an analyzer positioned outside of the cooking process in a separate liquid flow. The measuring devices are per se known detectors. The cooking process is observed and the necessary corrections are made on the basis of the measuring results.

Abstract: In continuous pulping processes for cellulosic fiberous material pulp, a changeover from deciduous wood raw material to coniferous wood raw material without interruption of the production process, and with a minimum waste of pulp, is provided. The pulp mixture during changeover, having a consistency of about 8-15% is fed to a screen in which the pulp is separated into two pulp fractions depending upon fiber length. A fiber length analyzer is placed in the pulp stream between a treatment or storage vessel and the screen, and controls the rejects line from the screen to determine the amount of pulp passing out the screen rejects conduit. The screen may be directly in a production line from a continuous digester, refiner, or like device for producing the pulp, or it may be connected to a storage vessel to which pulp from a digester or the like has been fed.

Abstract: The invention relates to a method of regulating, for the purpose of burning soda-ash in a recovery boiler furnace, the feeding-in or combustion conditions of concentrated spent liquors of varying chemical and physical properties by measuring some physical property of a liquor fed into the recovery boiler furnace and by regulating the feeding-in and combustion conditions directly on the basis of the thus measured physical properties. According to the invention, the maximum swelling, upon heating, of a dry-matter particle of the liquor fed into the recovery boiler furnace is measured. On the basis of this measurement the temperature, pH value, or injection pressure of the liquor fed into the furnace, or the height of the injection point or the direction of injection, or the feeding of air into the furnace is adjusted directly on the basis of the maximum swelling measurement.

Abstract: A method of rapid determination of the concentrations of the total sulphur dioxide and the lignosulphonate present in sulphite pulping process liquors. The lignosulphonates are separated from compounds which form the total sulphur dioxide by means of an ion exclusion column, whereby the filling material of the column consists of a cation exchange resin. The concentration measurements of the sulphur dioxide and the lignosulphonate are carried out from the liquor flow coming out from the separation column by means of UV-method at the wave length of 280 nm. The invention also relates to a method of controlling the sulphite pulping process by determining the total sulphite dioxide concentration in the pulping liquor.

Abstract: Method and apparatus for controlling the reactivity of lime produced in a lime cycle process that includes the steps of forming burnt lime in a kiln, washing and filtering of lime sludge, and causticizing of green liquor, which lime cycle process steps are carried out under variable operating conditions. At least one mechanical property of the burnt lime is measured, and at least one operating condition of the time cycle process is adjusted, based on the measured mechanical property of the burnt lime, so as to thereby control the reactivity of lime produced in the lime cycle process.

Abstract: A method and apparatus for producing uniform pulp yields, wherein at least a refiner is controlled in accordance with the UV absorbance of the lignin dissolved in the digester cooking liquor, thereby to produce for a given quantity of wood chips a uniform pulp yield. A backflow control valve is automatically adjusted to maintain uniform flow of a sample of the digester cooking liquor through a UV analyzer, and a flushing arrangement is provided for flushing out contaminates such as sulphur dioxide from the system. Preferably the refiner is of the two-stage type, the first stage being automatically adjusted as a function of the UV absorbance of the digester cooking liquor, and the second stage being automatically adjusted as a function of the freeness of the output fiber slurry. Also, one or more of the cooking parameters is controlled by the UV analyzer to control the fiber yield.

Abstract: Method of peroxide bleaching of mechanical, thermomechanical and chemi-mechanical pulp wherein the peroxide bleaching is controlled by addition of a known amount of bleaching chemicals in the first stage which amount is allowed to react under defined conditions whereafter the brightness of the pulp after this first stage is used for control of a subsequent stage. In the first stage fresh chemicals, chemicals recirculated from a subsequent bleaching stage or a mixture of these is used. Hydrogen peroxide is the preferred bleaching agent but other peroxides can also be used.

Abstract: Wash water input into a pulp washing system is controlled in response to measurements on a stream of output constituents of reduced transverse dimension compared to the transverse dimension of the washed pulp mat discharge stream from the pulp washing system. The measurements are conducted simultaneously across the entire width of the reduced dimension stream on all the washed pulp and water leaving the pulp washing system. The measurements are readily carried out using apparatus including means below said reduced dimension stream.

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 method for controlling the alkaline delignification processes, especially the sulphate process of wood or other materials containing cellulose by the interdepending concentrations of the hydroxymonocarboxylic acids which are formed in the process and dissolved into the waste liquor. According to the method a sufficient number of representative waste liquor samples are taken during the process and the acids present in the samples are analyzed by gas chromatography. Thus, the required time interval for achieving the desired cooking stage can be determined by using the interdepending ratios of the concentrations of certain acids.

Abstract: A method of controlling sulphite pulping or hydrolytic processes by means of a rapid furfural analyzer. Furfural and 5-hydroxymethylfurfural are separated from the other UV-absorbing compounds of a process liquor sample. The concentration measurements are carried out by menas of an UV-method. The obtained measuring results are utilized for on-line controlling of the process in question.

Abstract: A method for controlling an oxygen-bleaching process of lignocellulosic pulp to a desired degree of delignification.The pulp is passed at a substantially constant temperature into a bleaching reactor wherein the pulp has a substantially constant level at its outlet. The hydrostatic pressure is measured and the quantity of oxygen fed into the reactor is adjusted to reach a desired degree of delignification.

Abstract: Pulp washing efficiency at any given dilution factor and production rate is maximized by controlling washing surface speed in response to determination of total mass of product stream in weight per unit area on the surface and simultaneously controlling the rate of dilution liquid introduction in response to sensing of feed level in the container feeding the surface, thereby to obtain a substantially constant level of pulp in the feed and in the pulp mat formed on the washing surface which is to undergo washing and a substantially constant weight of pulp mat (on a dry pulp basis) per unit area on the washing surface.

Abstract: Apparatus is disclosed for continuously measuring the conductivity of the liquor in a pulp mat on a pulp washer. The apparatus comprises a probe which rests on and squeezes washing liquor from the pulp mat. Two modifications of the probe are disclosed, one fixed and one rotatable. In each case, the probe comprises a pair of electrodes separated from one another by non-conducting material. The electrodes are arranged on the probes to be submerged within the washing liquor squeezed from the mat. The electrodes are connected to an energy source, and when current is applied to one electrode, the current flows through the liquor to the other electrode to complete an electrical circuit. The measurement of the current flow or the resistance to current flow is directly related to the conductivity of the liquor and can be correlated with the soda loss in the pulp washing step.

Abstract: A method and suitable apparatus for periodically analyzing pulp stock, including wood pulp and water, in a pulp digester, to determine the amount of cooking to which the pulp has been subjected. The method includes taking a sample of the pulp stock from the digester, diluting the sample to a predetermined range of consistency, and determining the exact consistency of the sample. Next, the sample is transferred to a reaction chamber. A reagent is then added to the sample and allowed to react with the sample at a predetermined temperature. The light absorbance of the reagent during the reaction is continuously monitored during the reaction. After the light absorbance has clearly passed a peak, the value of the peak is combined with the consistency of the sample, previously determined, to arrive at the amount of cooking to which the sample had been subjected prior to the test, from a known relationship thereof to the light absorbance of the reagent and the consistency of the sample.

Abstract: In a contaminant detector for processing paper pulp including sticky contaminants, a pulp sample is diluted to less than 0.5% consistency and passed through a concentrator from a plurality of classified samples having heavy and light particles. The inclined classified samples are again diluted to less than 0.5% consistency and passed as thin sample flow through an open channel having a light transmitting base. The flow is back lighted and a photodetector includes a linear array of sensitive elements aligned to receive the transmitted light. The sensitive elements aligned with particle creates a signal proportional to the width. By rapid sequential activation of the elements, a digital data stream is created which is processed by a microprocessor to determine the particle size and produce a plurality of contaminant relative signals related to different classified size ranges, such as heavy, medium and small contaminant particles.

Abstract: A method and suitable apparatus for periodically analyzing pulp stock, including wood pulp and water, in a pulp digester, which may or may not be part of a paper machine, to determine the amount of cooking to which the pulp has been subjected. The method includes diluting a sample of the pulp stock from the digester, diluting the sample to a predetermined range of consistency, and determining the exact consistency of the sample. Consistency can be determined by any suitable commercially available apparatus. Next, substantially all the water is removed from the sample. A reagent, preferably a 14 percent solution of nitric acid in water, is then added to the sample and allowed to react with the sample for a predetermined time interval at a predetermined temperature. The light absorbance of the reagent during and after the reaction is determined by the amount of cooking to which the pulp has been subjected and the consistency of the sample.

Abstract: A method is described for controlling the cooking degree of pulp during pulp digestion and for analyzing cooking chemical composition and -concentration before and during cooking operation. The method is based on the continuous or discontinuous monitoring of the IR spectroscopical behavior of the cooking liquor. Evaluated IR-spectal data of cooking liquor samples are correlated with analytical data of the cooking liquor on the one hand and the resulting pulp on the other hand by means of adequate mathematical/statistical methods. A feedback of analytical data is performed to improve the statistical relevance of the method. The invention provides a method for cooking control which is much more accurate and faster than existing control methods.

Abstract: Control of pulp and water flow rates out of a bleaching tower in a multistage pulp bleaching process wherein each stage comprises a bleaching tower and a washing drum, comprises the steps of (a) measuring total weight of pulp composition per square meter on at least one washing drum and from such measurement and the speed of rotation and area of the washing drum surface and the consistency of pulp composition, determining the total weight per unit time of pulp and of water coming out of the bleaching tower previous to said washing drum, and (b) controlling the rate of pulp and water flow out of said previous tower based on the determination of the total weight per unit time of pulp and of water as determined in step (a), and (c) controlling the amount of bleaching chemical flow to the pulp going to any following stage to match the pulp flow rate as determined from the measurement of step (a) and the percentage of bleaching chemicals to be applied.

Abstract: A method and apparatus for monitoring and controlling the operation of a counter-current pulp washing system. The dilution factor, soda loss, wash liquor ratio and displacement ratio of the washing system are determined on-line. The value of either the soda loss or of dilution factor is continuously maintained within a preselected range and changes in the value of the other variable are monitored to provide an indication of whether the washing system is operating optimally. Based on the on-line determination of displacement ratio and wash liquor ratio, the efficiency of the washers is monitored, the cause of any decrease in efficiency is identified and the appropriate control action is applied to adjust the operating parameters of the washers to compensate for changed washing conditions or changed processing conditions.

Abstract: A method for rapid determination of the contents of lignin, monosaccharides and organic acids in the process solutions of sulfite pulping. Accordingly, any non-ionized compounds that disturbs the measurement of these concentrations are separated from the lignin material by an ion-exclusion technique. The measurements of concentrations are carried out by means of the UV-method, refractive-index method, and/or by means of the polarimetric method. The method of the present invention is usable for the controlling of sulfite cooking or other pulping or by-product production processes as well as for the characterization of the spent liquor.

Abstract: A device and method for measuring and controlling the extent of oxidation of kraft white and black liquors and also flue-gas scrubber circulating liquors is provided, comprising two dissimilar metal electrodes whose potential difference on immersion in the kraft liquor is proportional to the sulphide ion concentration and to the concentration of other oxidizable components in the liquor.