Abstract: The invention describes a process for the conversion of aqueous suspensions of lignocellulosic solids comprising a solids content of between 1 and 20% of dry material, said process comprising a step a) for compression of said suspension so as to separate the liquid phase present in and between the solids from the compressed solid phase and a step b) for extraction of at least the liquid phase, said liquid phase then being homogenized by heat and/or chemical treatments and reinjected on to the compressed solid phase.

Abstract: The first invention aims to provide a method for preparing stiffer bulky pulp at a freeness level comparable to that obtained by mechanical treatments to improve the bulkiness of product paper by searching for a method capable of adjusting freeness while suppressing damage to pulp fibers and internal fibrillation in a process for producing pulp. The second invention aims to strip contaminants deposited on pulp fibers and/or inorganic particles to reduce adhesion of the contaminants and decrease microorganisms in a treatment of process water containing long pulp fiber fractions used in a process for producing pulp and paper, thereby clarifying process water and thus preparing high-quality pulp and paper.

Abstract: A circular utilization method in pulping and papermaking processes with straw Primary pulp is obtained by digesting straw raw material according to the ammonium sulfite method. Concentrated black liquor is extruded from the primary pulp; paper pulp and diluted black liquor. The concentrated black liquor and the diluted black liquor are mixed, and a contaminated condensate is obtained. A residual concentrate or the concentrated black liquor is used for preparing a fertilizer. The contaminated condensate is mixed with one or more of the waste material obtained from stock preparation, a crop byproduct or organic waste, and substrate or fertilizer is obtained by fermenting the nitrogen source of the contaminated condensate or ammonium sulfite, or using the contaminated condensate for desulfurizing flue gas. Ammonia and flue gas are reacted to obtain the ammonium sulfite as a digestion agent; and water from recycling is used in corresponding phases of the pulping process.

Abstract: The invention describes a process for the conversion of aqueous suspensions of lignocellulosic solids comprising a solids content of between 1 and 20% of dry material, said process comprising a step a) for compression of said suspension so as to separate the liquid phase present in and between the solids from the compressed solid phase and a step b) for extraction of at least the liquid phase, said liquid phase then being homogenised by heat and/or chemical treatments and reinjected on to the compressed solid phase.

Abstract: The invention describes a process for the conversion of aqueous solutions of lignocellulosic solids comprising a solids content of between 1 and 20% of dry material, said process comprising a step a) for compression of said solution so as to separate the liquid phase present in and between the solids from the compressed solid phase and a step b) for extraction of at least the liquid phase, said liquid phase then being homogenised by heat and/or chemical treatments and reinjected on to the compressed solid phase.

Abstract: Provided is a process for manufacturing shaped cellulose materials from lignocellulose where a dissolving grade pulp is manufactured and dissolved in an aqueous alkaline or acidic solvent system forming a solution suitable for shaping new cellulose structures including fibers, films and cellulose derivatives. At least a part of the spent cellulose dissolving or cellulose shaping chemicals are recovered in one or more unit operations in a pulp mill chemical recovery cycle.

Abstract: The invention relates to a process for producing a dissolving pulp from a cellulosic starting material using the kraft process, comprising the step of cooking the starting material with a cooking liquor. The process according to the invention characterized in that the starting material is exposed to a steam treatment prior to cooking and that the pulp obtained by cooking is subjected to cold caustic extraction (CCE) in the course of further processing.

Abstract: A method for heating a chip slurry in a pulping system including an impregnation vessel and a chemical digesting vessel, the method including: impregnating chips in the impregnation vessel with a liquor; transporting the chips from the impregnation vessel to an upper elevation of the digester vessel; extracting liquor from a lower elevation of the digester vessel, wherein the extracted liquor has a temperature substantially higher than a temperature of the chips being transported to the upper elevation of the digester vessel, and adding extracted liquor from the lower elevation of the digester vessel to the chips being transported from the impregnation vessel to the digester vessel.

Abstract: A system for collecting ligno-cellulosic biomass over a large area to enable the commercial refining of biomass from 2,500 to in excess of 50,000 tons of biomass per day to produce ethanol or other products. The biomass is collected at a series of collection points and then transported through a network of conduit “loops” interconnecting each of the collection points and the central refining plant. The water used to transport the biomass, as a slurry, is recovered and sequentially recycled in the same pipeline system to push the biomass slurry around the system in a “loop.” The outgoing and return legs of each loop optionally are located adjacent each other.

Abstract: A system for collecting ligno-cellulosic biomass over a large area to enable the commercial refining of biomass from 2,500 to in excess of 50,000 tons of biomass per day to produce ethanol or other products. The biomass is collected at a series of collection points and then transported through a network of conduit “loops” interconnecting each of the collection points and the central refining plant. The water used to transport the biomass, as a slurry, is recovered and sequentially recycled in the same pipeline system to push the biomass slurry around the system in a “loop”.

Abstract: The method is for influencing the flow from a strainer construction in a continuous digester. In order to avoid clogging of the withdrawal compartment in the strainer construction, an additive that counteracts precipitation processes is added directly to the withdrawal compartment while the cooking fluid is withdrawn from the withdrawal compartment. The addition of chemicals can take place at the same time as the withdrawn cooking fluid is withdrawn from the digester and the strainer construction, or while the withdrawn cooking fluid is fully or partially re-circulated back to the withdrawal compartment.

Abstract: In a method for monitoring the functionality of a temperature sensor that can deliver an electrical signal as a function of the measured temperature and is disposed, in particular, in the cooling water circuit of an internal combustion engine, the persistence of the temperature sensor in the high signal range is made possible by a method encompassing the following steps: Characterizing the sensor as possibly faulty if the sensor indicates, upon engine shutdown, at least a maximum value of the cooling fluid temperature; determining a first gradient of the cooling fluid temperature, measured by the possibly faulty sensor, up to a first point in time after engine shutdown, and characterizing the sensor as fault-free if the gradient exceeds a minimum value; determining a second gradient of the cooling fluid temperature, measured by the possibly faulty sensor, between the point in time and a point in time after engine shutdown, and characterizing the sensor as fault-free if the second gradient exceeds a minimum va

Abstract: Systems and methods for purifying wood pulp by caustic-borate extraction. The systems and method include a method for recovering both the caustic and borate compounds from the resultant hemicaustic effluent, so that they may be recycled and re-used. Efficient recovery of these components is enabled by a nanofiltration system that has one or more alkali-resistant nanofiltration membranes.

Abstract: A method for converting a vapor phase continuous digester to a hydraulic digester including the steps of: operating the vapor phase digester in a vapor phase mode wherein a chip slurry enters the vessel of the digester through a lower chip inlet port, moves up through a top separator, discharges from an upper chip discharge chute of the separator to an upper vapor region of the vessel and falls to a liquor filled region of the vessel; ceasing the flow of the chip slurry to the separator; establishing a chip slurry flow path to an upper portion of top separator, and filling the vessel with liquor and chips such that the chip discharge chute is immersed in liquor.

Abstract: An air conditioning system for use in an over-the-road or off road vehicle is provided that allows operation during both engine on and engine off conditions. The system utilizes a variable speed, motor driven compressor controlled by an intelligent power generation management controller. This controller selects from one of the available sources of power on the vehicle to drive the compressor, and modulates the compressor speed and capacity based on operational parameters and source availability and depletion. The controller may also operate a coolant or air heater to provide heating to the interior compartments.

Abstract: A method for heating a chip slurry in a pulping system including an impregnation vessel and a chemical digesting vessel, the method including: impregnating chips in the impregnation vessel with a liquor; transporting the chips from the impregnation vessel to an upper elevation of the digester vessel; extracting liquor from a lower elevation of the digester vessel, wherein the extracted liquor has a temperature substantially higher than a temperature of the chips being transported to the upper elevation of the digester vessel, and adding extracted liquor from the lower elevation of the digester vessel to the chips being transported from the impregnation vessel to the digester vessel.

Abstract: The method is for pre-treatment of chips that are fed to a sulphate cooking process. Through acidification of the chips in an acidic treatment fluid with a subsequent draining of free treatment fluid before subsequent steaming or wet-steaming, a high concentration of free hydrogen ions is established within the chip pieces. When the chips are subsequently formed into slurry with preferably a sulphide-rich alkali cooking fluid, H2S is formed locally in the chip pieces which gives a yield-increasing effect in the subsequent cooking step of 1-3%.

Abstract: A process for removing silica from nonwood plant materials involving both chemical and mechanical action is described. The silica-rich epidermal cells are liberated mechanically by a pre-pulping and low-consistency refining step and subsequently removed from the pulp via the filtrate of a thickening step. Amorphous silica is liberated chemically by using an alkaline dilution source in the pulper, then removed from the pulp via the filtrate of a thickening step and a dewatering step. The silica is then removed from the filtrate by adjusting the pH, followed by a separation step. The desilicated fibrous material may then be chemically or mechanically pulped and bleached using known processes. The silica removed from the nonwood plant material may then be used as a feedstock for other applications.

Abstract: The method is for cooking of cellulose pulp in which the raw material, preferably in the form of chips, undergoes a successive elevation of temperature towards the cooking temperature while the chips are first impregnated with an impregnation liquor followed by cooking in a cooking liquor that is preferably alkali. Through the addition of pre-evaporated black liquor, either as early as the impregnation stage or during the subsequent cooking stage, an improved delignification process is achieved in which the pulp obtains improved properties, primarily with respect to strength/viscosity for a given degree of delignification, and also with respect to yield. The method can be used both for continuous cooking and for batch cooking of cellulose pulp.

Abstract: A process for high temperature peroxide bleaching of pulp in which pulp is retained at high temperature and pressure to increase bleaching activity but in which the pulp is cooled prior to discharge from the pressure vessel below the flash point thereby resulting in lower energy, nonviolent discharge. Through the use of a heat exchanger, the cooling of the pulp can be performed using recycled filtrate containing residual peroxide, which encourages further bleaching during atmospheric retention. The heat exchanger is also used to heat a water stream, which can be used earlier in the pulping process, resulting in cost savings because energy within the system is retained to a greater degree.

Abstract: Separation of dissolved and colloidal high molecular weight organic by-products from liquors or filtrates in a cellulosic pulping process to improve the overall efficiency of the process.

Abstract: The process is for continuously cooking chemical pulp in a digester system consisting of at least one vessel for impregnating and cooking comprising an inlet into which a mixture of chips and process liquid is fed. The chips are impregnated at a predetermined impregnation temperature, Timp, and cooked at a predetermined cooking temperature, Tcook, after which dissolved pulp is fed out at the outlet of the digester system. The process liquid which is continually extracted is retained outside the digester system during a dwell time, t, of at least 30 min, without any heating above 140°, and thereafter returned to the digester system to a position which is substantially at the same level as the extraction, or downstream thereof, and thereby constitute part of the process liquid in the subsequent treatment zone. The process results in improved tear strength, beatability, bleachability and reduced color reversion, and increased yield across the digester.

Abstract: Xylooligosaccharide is produced from a lignocellulose pulp by enzyme-treating a lignocellulose pulp with hemicellulase, filtering the resultant reaction mixture to separate a liquid fraction from the enzyme-treated pulp, subjecting the separated liquid fraction to a permeation treatment through a separation membrane to separate a non-permeated fraction containing xylooligosaccharide-lignin complex with an increased concentration from a permeated fraction, collecting the non-permeated fraction, and separating and recovering xylooligosaccharide from the collected non-permeated fraction.

Abstract: Lignocellulose pulp is bleached by bleaching a pulp in aqueous alkali solution with oxygen and treating the pulp with a hemicellulase, while a liquid fraction delivered from the enzyme treatment step is separated from the hemicellulase treated reaction mixture, and subjected to a penetration treatment through a separation membrane, for example, reverse osmosis membrane, to separate a permeated fraction from a non-permeated fraction; the permeated fraction is fed to the alkali-oxygen bleaching (oxygen delignification) step and is used as a liquid medium of the bleaching system.

Abstract: Alkenyl succinic anhydride (ASA) size emulsions are prepared using a grafted cationic acrylamide starch co-polymer as an emulsification agent. The ASA size emulsions of the present invention exhibit significantly greater stability compared to presently available ASA size emulsions. The grafted starch co-polymer also is a more efficient emulsification agent for ASA size, permitting the use of less emulsification agent, thereby saving cost.

Abstract: Separation of dissolved and colloidal high molecular weight organic by-products from liquors or filtrates in a cellulosic pulping process through a filtration media to improve the overall efficiency of the process.

Abstract: A method in bleaching of pulp is described, in which the pulp is subjected to a peroxide bleaching step, whereupon the pulp is washed and the washing liquid from the washing is separated from the pulp in the form of a filtrate. The method is characterised in that the filtrate is treated with an aluminium compound, such as aluminium sulphate or polyaluminium sulphate, for precipitation of interfering substances, such as oxygen-demanding organic material and metals, that the precipitated material is removed from the filtrate, that the aluminium content of the filtrate after precipitation of interfering substances is adjusted to at most 20 ppm, and that the filtrate is then recirculated to the peroxide bleaching step. By the method, a reduced consumption of hydrogen peroxide in the peroxide bleaching step is achieved.

Abstract: A sub-condenser 4 is disposed in a within-vehicle-compartment air passage P1, so that the sub-condenser is permitted to receive heat from a heater core 21.

Abstract: The method described herein will produce depolymerized lignins substantially free from sodium compounds. Black liquor supplied from a pulping process is utilized for providing a mixture of depolymerized lignins dispersed and dissolved in a solution containing sodium hydroxide. The mixture is then separated to form depolymerized lignins and a solution containing sodium hydroxide. Following separation, the depolymerized lignins are then extracted with water to produce an extractate containing sodium compounds. The extracted depolymerized lignins, containing sodium compounds, are then reacted with an acid to form sodium salts to form a slurry. The slurry containing sodium salts is, by means of a salt splitting method, separated from the extracted depolymerized lignins to produce substantially sodium free depolymerized lignins.

Abstract: The invention relates to a process for continuous cooking of wood chips at elevated pressure and temperature in a vertical digester (1) for production of chemically dissolved pulp.

Abstract: A method of cooking pulp in an alkaline batch process (using one or more batch digesters) improves pulp bleachability. The wood material is supplied to the digester; the cellulosic material is pre-treated in the digester with a first liquor, the first liquor is displaced by a second liquor, the displaced first liquor is led to a further treatment, the cellulose material is treated with the second liquor, and the cooked pulp is removed from the digester. The second liquor is displaced as two consecutive parts, i.e. as strong black liquor and weak black liquor, and after cooling in a heat exchanger the strong black liquor thus obtained is fed into the digester as the first liquor in a subsequent batch (in the same, or a different, batch digester).

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

Abstract: A method in connection with the pretreatment of comminuted fibrous material intended for chemical cellulose pulp production. The fibrous material is fed through a low pressure system that has a gas phase part followed by a liquid phase part. The liquid phase part includes a low pressure circulation where a circulating liquid is withdrawn from the fibrous material and recirculated back to the fibrous material in an upstream position. The fibrous material is sluiced into a high pressure system that has a liquid phase transfer part operatively connected to a digester. A hot process liquid and/or the circulating liquid are evaporatively cooled by being allowed to flash within the low pressure system.

Abstract: In the production of chemical pulp, such as kraft pulp, it is possible to reduce the amount of ancillary equipment, and/or the size of the continuous digester vessel, while achieving enhanced uniformity of treatment by avoiding “hang ups”. Instead of providing vertical counter-current flow of liquid and comminuted cellulosic fibrous material being treated in the lower half of the digester, the counter-current flow may be a cross flow, that is substantially horizontal (e.g. radial) while the flow of the chip column is vertical. Regardless of the configuration of the digester vessel, a single pump may be utilized for all of the recirculations, or only a few pumps for all of the recirculations.

Abstract: The present invention relates to a process for continuously guiding a liquid when digesting pulp in a digester, wherein liquid used in a process step can circulate between containers or tanks arranged at the inflow and outflow side of the digester and when this particular process step has been reached, the digester is connected into the circulation between the containers or tanks associated with the process step.

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

Abstract: Calcium carbonate scaling is inhibited in a multi-stage alkaline waste liquor evaporation plant in a chemical cellulose pulp mill having a bleaching plant. Calcium-containing effluent from the bleaching plant is treated together with alkaline waste liquor in the evaporation plant. A portion of the alkaline waste liquor of the evaporation plant is supplied to the bleaching effluent to increase the carbonate content of the effluent. Then the bleaching effluent is heated to 110-160° C. by direct contact with a heating medium (e.g. steam, or secondary vapor) and maintained in a retention tank for a period of about 1-20 minutes to reduce the amount of dissolved calcium in the effluent. Finally the heat-treated bleaching effluent is evaporated with the alkaline waste liquor in the evaporation plant, with minimized scaling.

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

Abstract: A method for impregnation and chemical digestion of lignocellulosic material and recovery of pulping liquors. A spent impregnating or cooking liquor is withdrawn and sulphurous compounds are recovered therefrom in a partial oxidation reactor. These sulphurous compounds are converted into hot liquid elemental sulphur which thereafter is mixed with a hot sulphide containing liquor to provide a polysulphide liquor with a concentration greater than 10 g/l and which is essentially free from thiosulphate. This polysulphide liquor is used for carbohydrate stabilising impregnation and/or for cooking at a relatively low temperature.

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

Abstract: The present invention relates to a digester and a method for continuously cooking kraft pulp in a single-vessel system (1), preferably a single-vessel hydraulic digester, with chips (2) being fed in at a first end (3) of the digester (1), white liquor (4) being added at at least one position at or near the said first end (3), the chips being impregnated in a cocurrent impregnation zone (5), the chips being cooked in a cooking zone (6) downstream of the impregnation zone, hot black liquor (7) being extracted from at least one extraction strainer section (8), and cooked pulp being discharged (9) at the other end of the digester, and hot black liquor (7) being added (11), (12) to the said impregnation zone (5), and the extract (13) from the first strainer section (14), which is arranged downstream of the position of addition (11a) of the said hot black liquor (7), being largely removed from the digester.

Abstract: The present invention relates to a method for continuous cooking of kraft pulp in a single-vessel system (1), preferably a single-vessel hydraulic digester, with chips being conveyed from a high-pressure feeder (2) in a transfer line (2A, 4A) to a first end (3) of the digester (1), the chips being impregnated, in a liquid containing black liquor, in a concurrent impregnation zone (5), the chips being cooked in a cooking zone (6) subsequent to the impregnation zone, hot black liquor (7) being extracted from at least one extraction screen section (8), and cooked pulp being discharged (9) at the other end of the digester. The chips are, when they leave the high-pressure feeder (2), included in a first liquid, which first liquid is in the main separated from the chips in a liquid exchanger (4) installed in the transfer line (2A, 4A) and is replaced by a second liquid which contains black liquor.

Abstract: Digester systems for producing paper pulp from comminuted cellulosic fibrous material take into account the level of dissolved organic materials (DOM), such as lignin, hemi-cellulose, and cellulose, maintaining the DOM level at about 100 g/l throughout the cook (particularly kraft cook). In order to make sure there is sufficient liquid to slurry the material in the feed system of a two vessel system, some liquid is withdrawn from the circulation conduits between the digester and impregnation vessel, cooled, and fed to the feed system. In a vapor phase digester, the level of liquid at the top of the digester is more precisely controlled by circulating some of the withdrawn liquid from a circulatory loop of the digester to the level tank associated with the feed system. An in-line drainer may be provided in the feed system between a make-up liquor pump and a liquid inlet conduit leading to the top of an impregnation vessel.

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

Abstract: The present invention relates to a method of processing white liquor obtained from the causticization stage of a pulp mill. According to the method, the white liquor, which principally contains sodium hydroxide (6) and sodium sulfide, is oxidized into polysulfide liquor (3), whereby the sodium sulfide is oxidized most advantageously with the help of a catalyst and an oxidizer such as air substantially into sodium polysulfide (7) and sodium thiosulfate. The method according to the invention is characterized in that the sodium hydroxide (6) contained in the white liquor is separated from the white liquor prior to the oxidizing step or from the polysulfide liquor (3) after the oxidizing step either entirely or partly by means of a diffusion dialysis process (4). The invention is further characterized in that the sodium hydroxide (6) separated from the white liquor is returned to the chemical circulation of the pulp mill.

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

Abstract: The present invention relates to a method for continuous cooking of kraft pulp in a single-vessel system (1), preferably a single-vessel hydraulic digester, with chips being conveyed from a high-pressure feeder (2) in a transfer line (2A, 4A) to a first end (3) of the digester (1), the chips being impregnated, in a liquid containing black liquor, in a concurrent impregnation zone (5), the chips being cooked in a cooking zone (6) subsequent to the impregnation zone, hot black liquor (7) being extracted from at least one extraction screen section (8), and cooked pulp being discharged (9) at the other end of the digester. The chips are, when they leave the high-pressure feeder (2), included in a first liquid, which first liquid is in the main separated from the chips in a liquid exchanger (4) installed in the transfer line (2A, 4A) and is replaced by a second liquid which contains black liquor.

Abstract: A sensor for deposit build-up in plant, for example a paper-making installation, comprising a probe mounted with respect to a mounting body and including at least one strain gauge for measuring the flexural strain in a flexurally deformable body strained by imbalance in the probe in response to the combined mass of the probe and the deposit build-up thereon. The process of the invention envisages using the resulting signal for controlling the application of a deposit-controlling composition. An optional further sensor enables detection of the nature of the deposition whose quantity is sensed by the strain gauge.

Abstract: A method of recycling sodium-based salts used for digesting wood in a digester during the manufacture of pulp and paper. The method comprises collecting a black liquor from the digester, concentrating the black liquor, and adding a salt to the black liquor in an amount sufficient to reduce the viscosity thereof. Preferred salts are thiocyanate salts. The black liquor is then oxidized to produce a green liquor and a causticizer added to the green liquor to produce a white liquor containing the sodium-based salts to be recycled. The white liquor is then returned to the digester.

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. After being impregnated with a first cooking liquor (e.g. white liquor) having low effective alkali, the first liquor is extracted from the pulp, and it is impregnated with a second cooking liquor having an effective alkali concentration of at least 25 g/l and cooked at cooking temperature (e.g. 140.degree.-190.degree. C.) to produce a spent second cooking liquor having a residual effective alkali concentration of at least about 15 g/l, which is then extracted from the pulp. The spent second liquor may be used to preheat incoming white liquor, and then flashed and used as the first liquor. The pH of the first liquor is typically less than about 13.0, and the residual pH of the spent second liquor is about 13.0 or more.