Abstract: A system and method for rapidly determining the pulp kappa number through direct measurement of the potassium permanganate concentration in a pulp-permanganate solution using spectrophotometry. Specifically, the present invention uses strong acidification to carry out the pulp-permanganate oxidation reaction in the pulp-permanganate solution to prevent the precipitation of manganese dioxide (MnO2). Consequently, spectral interference from the precipitated MnO2 is eliminated and the oxidation reaction becomes dominant. The spectral intensity of the oxidation reaction is then analyzed to determine the pulp kappa number.

Abstract: This invention describes a new method to measure kappa number or lignin content of kraft pulps based on the voltammetric measurement of catalytic reactions involving lignin and redox mediators. This method comprises measuring the rate of regeneration of a lignin redox catalyst in the presence of pulp following its oxidation at a voltammetric electrode. The intensity of the catalytic current generated at the electrode surface is shown to be proportional to the amount of lignin present in a pulp. Within pulp types (softwood, hardwood or oxygen delignified) linear relationships can be obtained between the intensities of the generated current and a range of kappa numbers. The redox characteristics and concentration of the mediator, and the voltage sweep rate of the voltammetric procedure, are among parameters that can be tuned to obtained linear relationships with kappa number of various pulps.

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: This invention relates to a novel on-line pulp digester control system. More particularly, this invention pertains to a novel 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: The invention relates to a fluorescence microscopy technique for measuring physical and chemical properties of individual fiber-like particles. Fluorescence intensity per unit length is shown to be proportional to the fiber coarseness. In addition, other fiber properties such as fiber length, width and wall thickness can be obtained from fluorescence images, and lignin content from fluorescence spectra. The present invention will provide a process for determining the uniformity of pulp samples in terms of the physical and chemical properties of the individual fiber-like particles, particularly wood pulp fibers.

Abstract: The object of the invention is a sampling apparatus in a continuous industrial process for taking a sample of the substance to be monitored. The sampling apparatus is located on the wall of the pulp tank and it includes a sample chamber, which is equipped with a cover, and a filter. The sample chamber includes a closing device, by means of which the connection from the pulp tank to the sample chamber can be closed, as a result of which the filter remains in the sample chamber in the space between the cover and the closing device. The filter can be pulled out of the sample chamber for cleaning after the cover of the sample chamber has been opened. Another object of the invention is a sampling method and a cleaning method for the sampling apparatus presented.

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: The object of the invention is a sampling apparatus in a continuous industrial process for taking a sample of the substance to be monitored. The sampling apparatus is located on the wall of the pulp tank and it includes a sample chamber, which is equipped with a cover, and a filter. The sample chamber includes a closing device, by means of which the connection from the pulp tank to the sample chamber can be closed, as a result of which the filter remains in the sample chamber in the space between the cover and the closing device. The filter can be pulled out of the sample chamber for cleaning after the cover of the sample chamber has been opened. Another object of the invention is a sampling method and a cleaning method for the sampling apparatus presented.

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: A method for determining the concentration of hydrogen ion, organic anionic species and anionic species selected from the group consisting of OH−, CO3═, HS−, ClO3−, SO4═, S2O3═, polysulphide and peroxide in an aqueous sample solution, said method comprising subjecting said solution to near infrared radiation at a wavelength region of wave numbers selected from about 7,000 to 14,000 cm−1 through a solution path length of at least 3 mm to obtain spectral data for said solution; obtaining comparative spectral data for said anionic species at known concentrations in aqueous solutions; and correlating by multivariate calibration the relationships between said spectral data of said sample solution and said comparative spectral data to determine said concentration of said anionic species in said sample solution.

Abstract: A method and a device for measuring the content of chemicals used in connection with bleaching of preferably cellulose fibers in a pulp, suspension for the purpose of providing a better and more uniform product quality and preventing overdosage of the bleaching chemical used. According to the invention a measurement sample is derived from a predetermined volume of the pulp suspension after or during the bleaching. Further, a catalyst in the shape of the enzyme catalase is added to the sample, which is agitated so that the bleaching chemical is decomposed and oxygen gas is generated, which oxygen gas pushes out a certain sample volume for the measurement sample, which sample volume is directly or indirectly converted, e.g. via a simple algorithm, to a value representing the content of the bleaching chemical used.

Abstract: Process and measurement device for quantitatively detecting constituents of a pulp/fluid mixture for paper and/or cardboard production. The device includes at least one radiation source for irradiating the mixture in a number of definite, different wavelength ranges. The device also includes at least one sensor for measuring the intensity of radiation that has been influenced by the mixture, and at least one set of measurement electronics. Each sensor detects only one of the definite, different wavelength ranges of the radiation at a particular time. The process includes irradiating the mixture with at least one radiation source, the irradiation occurring in a number of definite, different wavelength ranges; and measuring the intensity of radiation that has been influenced by the mixture by at least one sensor. Each sensor detects only one of the definite, different wavelength ranges of the radiation at a particular time.

Abstract: The invention relates to a method of washing a fiber pulp mixture, in which method the fiber pulp mixture is fed between two filter wires running in the same direction. There is a convergent dewatering space in the direction of travel of the wires, where water is removed from the pulp. According to the idea of the invention, the thickness of the pulp layer being fed between the wires is adjusted during operation, since the ash and fines content of the washed fiber pulp is essentially dependent on the basis weight of the fiber web being washed. In a preferred embodiment of the invention, the height of the slice at the output end of the dewatering space is adjusted. The essential idea of another preferred embodiment of the invention is that the speed of the wires is adjusted. The invention also relates to an arrangement comprising means for adjusting the thickness of the pulp layer being fed between the wires, i.e. the basis weight of the fiber web being washed.

Abstract: The object of the invention is a sampling apparatus in a continuous industrial process for taking a sample (16) of the substance to be monitored (11). The sampling apparatus is located on the wall (11) of the pulp tank and it includes a sample chamber (14), which is equipped with a cover (13), and a filter (15). The sample chamber includes a closing device (18, 24), by means of which the connection from the pulp tank to the sample chamber can be closed, as a result of which the filter remains in the sample chamber in the space between the cover and the closing device. The filter can be pulled out of the sample chamber for cleaning after the cover of the sample chamber has been opened. Another object of the invention is a sampling method and a cleaning method for the sampling apparatus presented.

Abstract: A rapid method is provided for the on-line spectroscopic determination of lignin content and/or kappa number in wood pulps. Unlike currently available commercial instrumentation, the method enables one to measure lignin content independently of species variations and pulp consistency.

Abstract: The present invention relates to a device and method for measuring the bleach requirement and bleachability of pulp in a pulp mill. The invention enables pulp mill operators to better control bleach plants. In one aspect, the invention comprises a system and method for rapid bleaching of the pulp, and measuring the rapid bleached brightness and lignin content of the pulp. In another aspect, the invention comprises an optical system for use in practicing embodiments of this invention.

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: Methods of bleaching cellulose pulp using chlorine dioxide and ozone in one and the same single stage of a bleaching sequence having a plurality of stages are presented. In its broadest embodiment the method comprises controlling a ratio of chlorine dioxide to ozone within a single stage of a first bleaching sequence in a range effective to achieve strength characteristics of a final paper elaborated from the first bleaching sequence at least as great as strength characteristics when compared to a control bleaching sequence, the control bleaching sequence being the same in all respects as the first bleaching sequence except not employing ozone in a stage, and for essentially the same final brightness of pulp elaborated from the first and the control bleaching sequence. Cellulose pulps made using the methods of the invention are also described.

Abstract: A method for controlling the addition of bleaching/delignifying reagents to obtain a substantially constant percentage of pulp delignification across the first bleaching stage. The present method allows substantial improvements in bleached pulp quality through proper addition of the bleaching/delignifying reagent flow rate. The efficiency of the bleaching/delignifying reagent is therefore greatly improved. Further, reduction of pulp off-grades, equipment corrosion and effluent loading are additional beneficial effects resulting from the present method.

Abstract: On-line measurements of an amount of dissolved solids in a liquid sample are determined by using both conductivity and UV measurements. More particularly, an amount of dissolved solids in a pulp and paper mill process water or effluent is determined by irradiating at least a portion of a liquid sample with ultraviolet light and subsequently measuring an absorption of the light by the liquid sample. Furthermore the conductivity of the liquid sample is measured and subsequently a computation is from a first relationship between the measured absorption of the first wavelength by the liquid sample and the measured conductivity of the liquid sample using a suitably programmed processor.

Abstract: A method of controlling the pressure of a vertical continuous comminuted cellulosic fibrous material (wood chip) digester is provided using a pressure-control extraction in a zone relatively insensitive to changes in the flow rate of liquid introduction or removal. The method comprises controlling the pressure in the digester primarily (or substantially exclusively) by varying the flow rate of liquor extracted from the pressure-control extraction to maintain the pressure in the digester at a desired superatmospheric level while avoiding non-uniform, unstable material movement in the counter-current washing zone; and introducing dilution liquid into the digester at the at least one recirculation-dilution loop. The pressure-control extraction is preferably substantially the upper extraction in the digester. Substantially except during excessive over pressure and under pressure conditions the extraction flow from the main extraction is maintained substantially constant.

Abstract: A method for use in a batch digesting process is provided which includes the removal of a portion of the hot cooking liquor from the digester prior to the cook creating a liquid-vapor interface in the digester followed by the removal or purging of the vapors disposed above the liquid-vapor interface and the reduction of the pressure in the digester to about the saturation pressure of the hot cooking liquor. The inclusion of these steps in the process helps to eliminate a coating on the pulp fibers which has been found to inhibit the bleachability and runability of the fibers. Accordingly, an apparatus and method for the batch digesting of pulp fibers is provided which provides pulp fibers having improved bleachability and runability characteristics.

Abstract: A method for washing pulp in a multistage pulp washing operation involves controlling operating conditions so as to maximize the efficiency of the operation particularly in response to determination of the percent consistency off the discharge side of each drum washer. The major variables that are useful to control are vat dilution flow, drum speed, vat level set point, drainage aids or defoamers, press roll pressures, vacuum break position, and temperature of the last stage showers.

Abstract: An authenticatable paper product is prepared by adding to a papermaking furnish fibers treated with from about 50-200 lb/ton of a fluorescent whitening agent (FWA). The paper made from the papermaking furnish will include fluorescent cellulosic fibers in an amount ranging from between 0.1-4.0 lb/ton to achieve FWA concentrations within the range of 1-20 ppm.

Abstract: A process and device for continuously measuring the quantity of particles spended in a liquid, which exist in at least two different physical states, such as detached or attached within the paper pulp. A separation assembly separates the particles into divisions depending on their size, and the separation assembly is continuously fed with liquid via an input pipe. A measuring and processing assembly has two channels or ducts coming from the separation assembly and are provided with translucent windows. A measurement and capture unit illuminates the windows, and at least two cameras located opposite each of the respective windows are synchronized with the illumination unit to capture, at regular intervals, an image of the windows. A system for digitizing the captured images and processing them to determine the quantity of particles for each physical states is forwarded to an output unit in a digital or analog form.

Abstract: A method that solves the problem of suppressing disturbing effects of transition and alkaline earth metal compounds during bleaching of chemically digested lignocellulosic pulp in a sequence with oxygen bleaching prior to oxidative stages with introduction of for instance ozone, superoxides, hydrogen peroxide and peroxy acids. The conditions during the oxygen bleaching are chosen so that the properties of these metal compounds are changed and the compounds removed from the pulp during the oxygen bleaching under such conditions that the attack on the cellulose is small and the fluctuations of the pulp quality due to fluctuating amounts of these metal compounds decrease markedly.

Abstract: A method and apparatus act on a sample liquid of a pulp and paper industry process water, such as a pulp slurry or white water. The sample is acted upon in an apparatus including sample flow chamber, a filtrate flow chamber, and a filter connecting the sample flow chamber with the filtrate flow chamber. A flow sample liquid, including solid substances such as fibers and filler materials (as well as dissolved and colloidal substances) is introduced through an inlet into the sample flow chamber. A main flow of the sample liquid is discharged through an outlet. A flow of filtrate is passed through a filter from the sample flow chamber into the filter flow chamber, thereby separating a predetermined fraction of solid substance from a minor portion of the introduced flow of sample liquid, in the filter. The minor portion of sample liquid corresponds to less than 1%, typically less than 0.1%, of the total introduced flow of sample liquid.

Abstract: A method of determining the filler content of paper, wherein the paper stock is examined prior to delivering the stock to the de-watering section of the paper machine, and wherein the volume concentration of particles in the stock that have a size which is greater than the characteristic size of the filler is determined at varying mechanical working of the pulp, and the amount of filler retained in the paper is predicted from the result of at least two such determinations.

Abstract: The present invention provides a method of monitoring a papermaking system and unit operations contained therein to optimize the overall papermaking process. The method comprises employing a fluorescent tracer that is selectively carried through the entire papermaking system or in a specific unit operation and is sufficiently inert and sufficiently stable under the environmental and chemical conditions of the system from its addition point to the sampling point. A sample is withdrawn from the papermaking environment (either via `grab` or on-line side stream sampling) and the withdrawn sample subjected to analysis. The analysis comprises comparing the tracer concentration to a standard to determine the concentration of tracer in the sample and/or determining the time of first appearance of said tracer from addition point to the sampling point and/or subsequent decay of said tracer concentration at the sampling point.

Abstract: In a paper-making machine, a method of determining a volumetric percentage of air in a fiber suspension for delivery to a headbox. The fiber suspension is transported through a fluid conduit. A sound transmitter and a target receiver are positioned relative to the fluid conduit. A sound is transmitted through the fiber suspension from the sound transmitter to the target receiver. A speed of the transmitted sound from the sound transmitter to the target receiver is established. The volumetric percentage of air in the fiber suspension is determined, dependent upon the established speed of sound.

Abstract: The sulfide ion concentration and sulfidity of kraft cooking liquor during kraft cooking of cellulose pulp is selectively increased. After treatment in a first treatment zone in which impregnation or kraft cooking takes place using a kraft cooking liquor having a first sulfide ion concentration and sulfidity, black liquor is extracted from the material, liquid is withdrawn from the material and dilution liquid is added to the withdrawn liquid and the withdrawn liquid with dilution liquid is reintroduced. In a second treatment zone after the first zone a second kraft cooking liquor is introduced having a second sulfide ion concentration and sulfidity greater than the first sulfide ion concentration and sulfidity (typically by about 20-50%), including by manipulating controlling the flow rate of extraction and the flow rates of withdrawal of liquid and addition of dilution liquid.

Abstract: Chemical (typically kraft) pulp having enhanced intrinsic fiber strength and bleachability compared to pulp produced using conventional or modified kraft cooking is produced by using high alkali and/or pH cooking, preferably by adding the vast majority of cooking liquor (such as kraft white liquor) after the first removal of liquid from the digester so that the effective alkali concentration is high near the end of the cook. That is during at least the last minute (preferably at least the last 15 minutes and most preferably at least the last 30 minutes) before the cook is terminated the effective alkali concentration is between 15-50 g/l, more preferably between about 18-40 g/l, and most preferably between about 20-35 g/l.

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: A process control method for adjusting chemical application in response to the pulp brightness and/or lignin content is realized by utilizing a coupled control feedforward, feedback or combination feedforward/feedback control system, wherein brightness measurements are made between successive lignin content measurements and adjustments made to the chemical application in response to a comparison value.

Abstract: The pH of a material containing lignin is determined by directing an ultraviolet light at the material. One of the characteristics of lignin is giving off a fluorescence in response to an ultraviolet light. A monochrometer is used to observe the fluorescence and produces a signal of the intensity of the fluorescent light at varying wavelengths. This signal is displayed on a display means such as a computer screen. Calibration occurs before the pH measurement of the material occurs. The calibration data along with information from the signal is used to calculate the pH of the material. No contact with the material is required in determining the pH of the material.

Abstract: A method and installation for bleaching a lignocellulosic pulp with ozone, while recovering an oxygen-rich gas which may be recycled or re-used. Bleaching of the pulp with ozone is preferably carried out under conditions in which ingress of air is prevented. In a multi-step bleaching process, an oxygen-rich vent gas typically containing at least 90%, by weight, of oxygen may be recovered from a second contactor for potential use in different oxygen-consuming operations in a pulp mill.

Abstract: A sampling device for a batch or continuous pulp digester for reduction of pulp sampling errors such as during a digester "blow" and for improving a pulping process based on the obtained samples.

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 rapid method is provided for the on-line determination of sodium sulfide concentration and/or percent sulfidity in green liquors or smelt solutions used for the production of either kraft or sulfite pulp. The method eliminates manual sampling, and the need for frequent equipment maintenance.

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 method and apparatus are described for continuously sampling a process stream, or reservoir of aqueous cellulosic pulp and detecting oversize contaminants in the sampled stream. This serves the overall objective of estimating the level of contamination in the process stream or reservoir during a given period of production; the method may include the following stages: 1) a continuous sample stream is drawn from the process or main stream, 2) the stream is passed through a centrifugal device which divides the sampled stream according to density, 3) the stream with the higher level of contaminants from the centrifugal device is passed to a screen which isolates the contaminants, and 4) the contaminants are flushed from the screen so that they can be quantified; these measurements are used to assess the purity of the material being produced. One useful application of this invention is to assess the presence of trace amounts of plastic contaminants in the production of the cellulosic pulp.

Abstract: An apparatus for detecting and determining the average value of the foreign materials contained in pulp suspension includes a pulp suspension introducing passage connected to a separating device including a primary chamber and a secondary chamber separated by a screen, the pulp components in the pulp suspension passage pass through the primary chamber, screen, and secondary chamber; a circulation passage connected between the primary chamber's inlet and outlet for circulating the pulp suspension containing the foreign materials in the primary chamber therethrough; and a device for detecting and determining the average value of the foreign materials contained in the circulated pulp suspension, the detecting device being located in the circulation passage.

Abstract: The invention concerns a method and apparatus for real-time measurement of refiner mechanical pulp quality index such as freeness. According to the method, refiner mechanical pulp transported in a steam-phase carrier is illuminated with electromagnetic radiation, and the change in the radiation spectrum caused by refiner mechanical pulp is detected. According to the method, the change in the radiation spectrum caused by refiner mechanical pulp is measured at a minimum number of four wavelength bands and the measured intensities are computationally processed to obtain the desired index of quality.

Abstract: Lignin concentrations from wood pulp samples are measured by applying an excitation light at a selected wavelength to the samples in order to cause the lignin to emit fluorescence. A spectral distribution of the fluorescence emission is then determined. The lignin concentration is then calculated based on the spectral distribution signal. The spectral distribution is quantified by either a wavelength centroid method or a band ratio method.

Abstract: The method solves the problem of delignifying technical cellulose pulp in a selective manner which will result in very low residual contents of lignin in the pulp and a correspondingly high quantity of lignin dissolved in spent liquors, which are recovered in the chemical recovery system of the pulp mill. The method comprises activating liquid-containing lignocellulosic material in the presence of nitrate with a gas that contains nitrogen dioxide, followed by the alkaline delignification of the lignocellulosic material, and measuring the acidity of the liquid accompanying the material on at least one occasion during the activation. The method is characterized in that the acidity of the liquid is measured subsequent to bringing the time derivative of the nitrate concentration of the liquid, expressed as millimols per liter of liquid per minute, to a level beneath +0.

Abstract: A method for controlling the gas recycle loop of an ozone bleaching process wherein an ozone generator produces an ozone containing gas from an oxygen containing feed gas and delivers the ozone containing gas to an ozone reactor at a variable flow rate responsive to reactor ozone demand. Pulp is bleached with the ozone containing gas, thereby producing an exhaust gas having a flow rate that varies in response to the flow rate of the ozone containing gas delivered to the ozone reactor. The exhaust gas is then recovered and its flow rate is modified within the recycle loop so that an amount equivalent to reactor ozone demand is returned to the ozone generators. The oxygen content of the oxygen containing feed gas is monitored at or near the inlet of the ozone generator and an amount of fresh oxygen is supplied to the oxygen containing feed gas to obtain a predetermined level of oxygen therein.

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 sampling device for a batch or continuous pulp digester for reduction of pulp sampling errors such as during a digester "blow" and for improving a pulping process based on the obtained samples.