Abstract: The present invention provides a method which, in the process of manufacturing recycled pulp fibers from a mixture of pulp fibers and a high water-absorption polymer, enables efficient manufacturing of the recycled pulp fibers while properly removing the high water-absorption polymer from the pulp fibers.

Abstract: This disclosure relates to methods of making novel dissolving wood pulps by processes comprising acid prehydrolysis, pulping, and a multi-stage bleaching process comprising oxidation with a catalyst and peroxide under acidic conditions, as well as to products made therefrom having a combination of medium-purity, low viscosity, and improved reactivity, filterability, and/or clogging that can be used as a substitute for traditional high-purity dissolving pulps in a wide variety of applications.

Abstract: An integrated mercaptan extraction and/or sweetening and thermal oxidation and flue gas treatment process for a wide variety of sulfur, naphthenic, phenolic/cresylic contaminated waste streams is described. It provides comprehensive treatment for the safe disposal of sulfidic, naphthenic, phenolic/cresylic spent caustic streams, disulfide streams, spent air streams, spent mixed amine and caustic streams (also known as COS solvent streams) from sulfur treating processes. It allows the use of regenerated spent caustic in the sulfur oxide removal section of the thermal oxidation system reducing the need for fresh NaOH. It may also contain an integrated make-up water system. The integration allows the use of the liquefied petroleum gas or other hydrocarbon feeds to the respective extraction or sweetening process to offset external fuel gas requirements for the thermal oxidation system and for the push/pull system of the spent caustic surge drum and optional hydrocarbon surge drum.

Abstract: In one embodiment, a carbon dioxide capturing system includes an absorber configured to include a first contact portion that brings a combustion exhaust gas containing carbon dioxide into contact with an absorbing liquid containing an amine compound, cause the absorbing liquid to absorb at least a portion of the carbon dioxide in the combustion exhaust gas at the first contact portion, and release the combustion exhaust gas. The system further includes a washing apparatus configured to include a second contact portion that brings the combustion exhaust gas released from the first contact portion of the absorber into contact with a washing liquid, and configured such that the combustion exhaust gas and the washing liquid are individually fed to an upstream side of the second contact portion.

Abstract: Integrated exhaust gas systems, methods, and processes are disclosed that includes pretreatment, treatment and post-treatment processes arranged in a variety of reaction environments to address varied application requirements and end product requirements is described in this disclosure. In addition, a contemplated ballast water treatment system—that can be used in combination with the integrated exhaust gas systems can treat seawater and return it to storage within the vessel or send treated water back to the sea. This system can be sized to treat the seawater as it is leaving the ship without prior treatment, while the seawater is aboard or treat the seawater that is within the ship and add any additional treatment to the water, as the seawater leaves the ship. This system is not involved with pumping the seawater into the ship or filtering the water prior to storage as ballast water.

Abstract: The present invention relates to a method for processing grass or hay as paper pulp having the steps of pre-reducing the grass or hay with a bale breaker and/or a shredder to an average fiber length between 500 mm and 10 mm, preferably between 120 mm and 10 mm, removing impurities and foreign or extraneous substances by means of a cyclone; reducing and fibrillating the grass or hay in a fiber mill, fraying the grass or hay; and screening and/or sifting the grass or hay by means of a circulating-air separator and/or a cyclone screener.

Abstract: The present invention proposes a polycarboxylate ether-based additive having the general formula (I) for use as flow modifier in suspensions. The present invention further proposes a method for obtainment of such additive, wherein the method comprises the sequential steps of esterification of polyethylene glycol (PEG) with maleic anhydride (MA) and thus obtainment of a chemical product (PEGMA); and free radical polymerization in a mixture comprising acrylic acid (AA), 2-acrylamido-2 methylpropanesulfonic acid (AMPS) and PEGMA as reactants, further comprising water and an initiator, initial pH value of said mixture is within the range between 7.5 and 8.5, and any free oxygen is removed from the mixture throughout the free radical polymerization.

Abstract: The method and apparatus are for obtaining strong white liquor and lime mud with low residual alkali content from causticized liquor. The first filter (FWL) receives causticized liquor from causticizing vessels (CT1-CT2-CT3) and is designed as pressurized two stage disc filter with 2 separate vat parts. In the first vat part non-diluted white liquor is obtained as a filtrate from the causticized liquor. The first lime mud cake accumulated on the filter discs in the first vat part is scraped off and diluted before being fed to the second vat part. In the second vat part weak liquor is obtained as a filtrate from the re-slurried first lime mud cake. The second lime mud cake accumulated on the filter discs in the second vat part is washed before being scraped off and diluted before being fed to subsequent lime mud handling.

Abstract: Pressurized fluidized furnace equipment includes a fluidized bed furnace (1) that pressurizes combustion air (B) and combusts a material to be treated (A) while fluidizing the same; an air preheater (3) that exchanges heat between a combustion exhaust gas (C) discharged from the fluidized bed furnace (1) and the combustion air (B); a dust collector (4) that removes dust from the combustion exhaust gas (C); and first and second superchargers (5, 6) to which the combustion exhaust gas (C), having undergone the heat exchange in the air preheater (3) and the dust removal in the dust collector (4), is supplied to generate compressed air (D, E). The first compressed air (D) generated in the first supercharger (5) is supplied as the combustion air (B) to the fluidized bed furnace (1) by way of the air preheater (3), and the second compressed air (E) generated in the second supercharger (6) is made to have a higher pressure than that of the first compressed air (D).

Abstract: Integrated exhaust gas systems, methods, and processes are disclosed that includes pretreatment, treatment and post-treatment processes arranged in a variety of reaction environments to address varied application requirements and end product requirements is described in this disclosure. In addition, a contemplated ballast water treatment system—that can be used in combination with the integrated exhaust gas systems can treat seawater and return it to storage within the vessel or send treated water back to the sea. This system can be sized to treat the seawater as it is leaving the ship without prior treatment, while the seawater is aboard or treat the seawater that is within the ship and add any additional treatment to the water, as the seawater leaves the ship. This system is not involved with pumping the seawater into the ship or filtering the water prior to storage as ballast water.

Abstract: An apparatus for producing formate from carbon dioxide includes a reactor (115) that is configured to receive carbon dioxide from a separation device (109) and a first reagent to form a formate and a bicarbonate material. The bicarbonate material is sent to a regeneration device (123) that also receives a second reagent from a source of the second reagent to form the first reagent and a carbonate material. The first reagent is recycled back to the reactor (115). The carbonate material can be stored in a storage device (131) for subsequent sale or other use and/or sent to a process device (109) of a plant for processing flue gas to remove one or more acid gas elements from the flue gas by using the carbonate material received from the regeneration device (123). A method for producing formate from carbon dioxide can include use of the apparatus.

Abstract: The invention relates to a method and equipment for treatment of black liquor at a pulp mill in order to recover chemicals and energy contained therein. In the invention, the black liquor is pyrolyzed in a pyrolysis reactor (4), the formed gaseous components are forwarded for utilization and the solids are mixed with water, whereby the formed solids are returned to a lime burning kiln (1) and the sodium-hydroxide-containing liquid is returned to the pulp cooking process.

Abstract: A method for emptying a furnace floor from smelt in a black liquor recovery boiler when the black liquor recovery boiler is being shut down. The emptying can be started while smelt is still flowing in smelt spouts. The floor is emptied by sucking smelt from the furnace with a smelt eductor. A device for removing smelt and wash water from a furnace of a black liquor recovery boiler by means of suction. Negative pressure is generated in the device by conducting pressurized gas into a suction pipe of an eductor so that preheated pressurized gas is discharged in the discharge direction of smelt and wash water.

Abstract: The invention relates to a method and apparatus for processing the black liquor of a pulp mill to recover the chemicals and energy therein. In the invention, the black liquor is pyrolyzed in a pyrolysis reactor (6), formed gaseous components are lead for utilization, sand is returned to a fluidized-bed boiler, and solid matter is mixed with water, whereby a soda-water solution is returned to the pulping process and solid carbon to the fluidized-bed boiler (1).

Abstract: A method to disrupt a smelt flow including: arranging a shatter jet nozzle assembly to direct a jet of disrupting fluid against the smelt flowing from a recovery boiler to a dissolving tank; supplying the disrupting fluid to the shatter jet nozzle assembly from a first source of disrupting fluid to form the jet directed against the smelt flow while a second source does not provide disrupting fluid to the shatter jet nozzle, and supplying the disrupting fluid from both the first source and the second source flow to the shatter jet nozzle assembly to form the jet of disrupting fluid directed against the smelt flow.

Abstract: Methods and apparatus for maintaining sulfur concentration in the chemical recovery cycle of a Kraft pulping process. A portion of the recovery boiler ash is dissolved, treated to remove solids, and combined with an acid to provide a solution. The recovery boiler ash may be dissolved directly in the acid. The acid may be effluent from a chlorine dioxide generator. The resulting solution is maintained in a fully dissolved state and subjected to an acid separation step to provide a sodium sulfate enriched phase, which may be used to maintain sulfur concentration in the Kraft pulping process, and a sulfuric acid phase. Chlorine ions can be separated with the sulfuric acid phase. The sulfuric acid phase can be recycled to the chlorine dioxide generator.

Abstract: An apparatus for cleaning and cooling a liquor nozzle, the nozzle including at least a liquor tube for feeding liquor and chemicals into a furnace of a recovery boiler. The apparatus includes an outer casing tube, which defines a space whereto conduits are provided for introducing water and steam to generate an emulsion or a conduit for introducing emulsion generated by the water and steam and the surface of which is provided with openings, such as pores or holes, for discharging the emulsion formed by water and steam through the outer casing.

Abstract: A wet oxidation process is used to control the concentration of reduced sulfur compounds from a viscose process. The wet oxidation process oxidizes the reduced sulfur compounds to convert such reduced sulfur compounds to an alkali sulfate and/or thiosulfate species. The alkali sulfate stream is recycled to the viscose process. Oxidation is performed under elevated temperature and pressure conditions such that the offgas has an oxygen concentration of between about 2% to 18% and the alkali sulfate stream has a pH of about 2 to 10.

Abstract: An enclosure for a smelt spout of a chemical recovery boiler comprises a skirt having a central region through which smelt flowing from the smelt spout falls into a dissolving tank. The central region is defined by a wall and has a trough disposed around its perimeter. The trough is supplied with a fluid that overflows the trough and flows downward across the wall toward the dissolving tank to clean and cool the skirt. The trough may have a depth substantially equal to the height of the skirt, and the fluid may include at least one of: water, weak wash, and green liquor. Water may be periodically supplied to the trough in lieu of the fluid to clean the trough. A nozzle system is configures to direct at least one shatter jet onto the smelt flowing from the smelt spout to break it up into smaller particles.

Abstract: Method and apparatus for reducing the amount of sludges produced in a pulp and/or paper mill. The sludge produced in a pulp and/or paper mill as a result of waste water treatment is conveyed to solid fuel and the produced fuel-sludge mixture is burned in a power boiler. The solid fuel is heated before sludge is mixed therein.

Abstract: In the process for producing kraft pulp, performing a potassium ion removal step of flowing an aqueous solution containing ashes recovered from a combustion exhaust gas generated in a black solution combustion step by a dust collector through a packed bed filled with a sodium-type cation exchange organic resin to adsorb and remove potassium ions contained in the aqueous solution; and a regeneration step of treating the cation exchange organic resin used in the potassium ion removal step with a solution consisting essentially of aqueous sodium hydroxide to regenerate the cation exchange resin, where a fraction recovered from the potassium ion removal step which is rich in sodium sulfate and sodium carbonate is recycled to the black solution concentrating step, and a sodium hydroxide effluent recovered from the regeneration step is recycled to a bleaching step and used in a bleaching process.

Abstract: The present invention relates to a method in connection with smelt removal form a recovery boiler, whereby the smelt is removed from the boiler via a smelt spout surrounded outside the boiler by a hood and a dispersion medium, preferably steam, is fed into the smelt flow falling from the smelt spout for shattering the smelt flow. An essential characteristic is that at least one wall of the hood is washed with liquid so that the liquid first flows downwards on the outer surface of the hood wall and is led into the interior of the hood via at least one trough-like member arranged on the outer surface of the wall and openings in the wall so that the liquid further flows downwards on the inner surface of the wall. The invention also relates to an arrangement for washing the hood and the feeding device for the dispersion medium.

Abstract: Method for treatment of spent liquor at a pulp mill, in which method at least a part of the spent liquor flow arriving from the evaporation plant is taken to a pyrolysis reactor, wherein it is pyrolysed at a temperature of 300-800° C. in order to separate evaporable compounds from the coke remaining in a solid state. The pyrolysis products, which are gases or liquids, may be used as fuel or they may be processed further. The coke resulting from the pyrolysis is burnt in a soda recovery boiler or in a gasification reactor to regenerate cooking chemicals. The method is suitable for recovery of chemicals and energy both in sulphate and sulphite processes and also in cooking methods based on organic solvents.

Abstract: A method for burning chlorine-containing liquors in a chemical recovery boiler at a pulp mill, wherein the recovery boiler includes spent liquor sprayers for feeding spent liquor and a number of combustion air levels including: increasing a combustion temperature in the recovery boiler in a burning zone where a chlorine-containing liquor or a chlorine-containing effluent is burned; while burning the liquor or effluent, volatilizing the chlorine in the liquor or effluent to produce chloride-containing salts in flue gases in the boiler, and removing the chloride-containing salts from the flue gases.

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 (44) for the production of pulp and paper (28), recycling of cooking chemicals (3, 29), combustion of biomass (30, 37) and generation of heat and electric energy (27, 40) comprising a pulp and paper mill (28), in that the part of the process which is recycling cooking chemicals is adjusted from combustion (29) to gasification (3) to generate synthesis gas (14); and that biomass is added (33, 39) in an amount sufficient for compensating of the decrease in heat and electricity generation as a consequence of the generation of synthesis gas (14).

Abstract: The improved process is achieved by introducing depuration of green liquor and lime before causticization and two special causticization steps in causticization procedure of conventional chemical recovery processes. It not only avoids the generation of waste residue (lime mud) from the beginning and saves the re-burning and filling land of lime mud, but also can directly produce a series of precipitated calcium carbonate products with various particle sizes by regulating process conditions while alkali is recovered. The CaCO3 products include CaCO3 wherein ?50% of CaCO3 has a particle size below 2 ?m, CaCO3 wherein ?90% of CaCO3 have a particle size below 2 ?m, and a superfine CaCO3 having an average particle size <1 ?m. The CaCO3 obtained by this process can be directly used for papermaking and other industrial applications.

Abstract: An austenitic Ni—Cr—Fe alloy is provided as an exterior tube material for improved cracking and corrosion resistance of composite tubes used to construct the lower furnace section of kraft recovery boilers. The alloy consists of essentially, on a weight-% basis, 25-35 Cr, 5-15 Fe and 50-70 Ni, with other minor alloying elements and impurities such as are normally present in commercial alloys. This compositional range includes, as a preferred composition, the range corresponding to the commercial alloy 690 (UNS N06690).

Abstract: The invention relates to a process for producing pulp from a fibre-based raw material using, as the cooking reagent, a solvent mixture which is based on organic acids and also contains furfural. The method is applicable to herbaceous plants, in particular.

Abstract: The present invention relates to a new and environmentally sound process for the manufacturing of a chemical pulp from lignocellulosic material with an integrated recovery system for recovery of pulping chemicals. The process is carried out in several stages involving a pre-treatment stage followed by one or more delignification stages using an alkaline buffer solution comprising alkali metaborate and sodium carbonate as major components. The alkaline components of the pulping liquor are recovered from a chemicals recovery furnace and at least a portion of the alkali is recycled and used for delignification without any prior reactions with lime or calcium compounds for generation of alkali hydroxide. A quinone based delignification catalyst may be added to be present during delignification.

Abstract: The invention relates to a process for producing pulp from a fibre-based raw material using, as the cooking reagent, a solvent mixture which is based on organic acids and also contains furfural. The method is applicable to herbaceous plants, in particular.

Abstract: A method of recovery of alkaline sulphite pulping chemicals and for production of steam is disclosed. The method comprises gasification of evaporated spent cooking liquor at conditions resulting in a hydrogen sulphide containing gas and a solid residue. The gas is combusted in a steam boiler, where the hydrogen sulphide is converted into sulphur dioxide and steam is produced. The solid residue is recovered in a leaching process, preferably a two-stage leaching process, where process-foreign substances are removed and the rest of the contents is divided into substantially pure sodium carbonate and a mixture of sodium carbonate, sodium sulphate and sodium sulphide. The substantially pure sodium carbonate is used for absorption of sulphur dioxide from the steam boiler.

Abstract: Methods of increasing the throughput of recovery boilers equipped with at least three levels of injection of air with oxygen enrichment of the air in at least one air level. In one method, a black liquor recovery boiler has three levels of air injection, and oxygen enrichment is applied to at least the secondary and the tertiary air injection levels. In another method, a black liquor recovery boiler has four levels of air injection, and oxygen enrichment is applied to one or more of the tertiary or quaternary air injection levels. In another method, a black liquor boiler has three levels of air injection, with oxygen enrichment applied to at least two air injection levels. After combustion, the oxygen concentration in the resultant flue gas is sensed. The oxygen injection is then adjusted in order to maintain the sensed oxygen concentration at the previously selected oxygen set point.

Abstract: A method to remove sulfides and other volatile contaminants from liquor vapor condensate in a pulp manufacturing process, where the mentioned liquor vapor condensate is fed into a stripper, which is part of a closed loop system including the stripper, a regenerative thermal oxidization process (RTO) and a SO2 scrubber, in which loop a gas is circulated, preferably air, and such components formed or stripped off, in this loop whereafter the circulating gas is stripped off sulfides and other volatile components from the liquor vapor condensate, whereafter the gas stream is fed into a RTO process, where the stripped off contaminants are combusted are under formation of SO2 and thereafter the SO2 enriched gas is led to a SO2 scrubber, where preferably alkali is used as absorption medium, and thereafter the circulating gas is returned back into the stripper.

Abstract: The invention includes a treatment apparatus for treating fibrous cellulosic raw material suitable for use in a paper making plant comprising extracting means for extracting contrary material from the raw material, crushing means for crushing the raw material to remove nodes therefrom and splitting means for splitting the crushed raw material lengthways. A co-rotating twin screw conveyor is used to pulp the crushed material, the conveyor being divided up into a plurality of zones, means for inserting treatment materials into a least one zone and means for controlling the temperature and/or pressure of all of the zones. The black liquor effluent produced in the pulping process is treated in an apparatus comprising an evaporator for concentrating the liquor to 30-70% solids, a processing vessel for treating the concentrated liquor at a temperature of between 300-600° C., and a closed conveyor for transporting the concentrated liquor from the evaporator to the processing vessel in excess of 90° C.

Abstract: A substantially sulfur free process for the manufacturing of a chemical pulp with an integrated recovery system for recovery of pulping chemicals is carried out on in several stages involving physical and chemical treatment of lignocellulosic material in order to increase accessibility of the lignocellulosic material to reactions with an oxygen-based delignification agent. Spent cellulose liquor comprising lignin components and spent chemical reagents is fully or partially oxidized in a gas generator wherein a stream of hot raw gas and a stream of alkaline chemicals and chemical reagents is formed for subsequent recycle and reuse in the pulp manufacturing process.

Abstract: The present invention relates to a method and an arrangement for use in connection with the combustion of black liquor. In the method the black liquor is concentrated in a multi-effect evaporation plant in order to obtain black liquor at a suitable dry-solids content for combustion and to generate vapor. The concentrated black liquor is taken to be combusted in a recovery boiler, into which combustion air is fed at several levels for the combustion process. It is a characteristic feature of the invention that the air fed to at least one air level is preheated by using vapor generated in the concentration of the black liquor as heat source.

Abstract: This invention refers to a method for producing pulp in an alkaline digesting process comprising the following steps: charging lignocellulosic material to a digester system; pre-treating said lignocellulosic material with an impregnation liquor and subsequently with a hotter liquor containing black liquor, simultaneously displacing spent liquor; heating and cooking said lignocellulosic material to produce cooked lignocellulosic material and cooking liquor; displacing a portion of said cooking liquor at cooking temperature from said digester to a first section by supplying a washing liquid; further displacing a second portion of displaced liquor from said digester system to at least a second section by supplying further washing liquid until the temperature of said second portion of displaced liquor drops to a temperature of at least about the boiling point of said cooking liquor at atmospheric pressure, said second portion of displaced liquor having a dry solids content substantially lower than the initial dry

Abstract: A process (44) for the production of pulp and paper (28), recycling of cooking chemicals (3, 29), combustion of biomass (30, 37) and generation of heat and electric energy (27, 40) comprising a pulp and paper mill (28), in that the part of the process which is recycling cooking chemicals is adjusted from combustion (29) to gasification (3) to generate synthesis gas (14); and that biomass is added (33, 39) in an amount sufficient for compensating of the decrease in heat and electricity generation as a consequence of the generation of synthesis gas (14).

Abstract: The invention relates to a process for treating bleaching liquors from pulping processes based on organic acids. The process is characterized in that inorganic acid such as nitric acid, phosphoric acid and/or sulphuric acid, is added into a bleaching liquor obtained from the bleaching or a stage closely associated with bleaching, whereby organic acids contained in the bleaching liquor are released into the bleaching liquor. The organic acids are then separated from the bleaching liquor and recycled to the cooking stage to be used as cooking chemicals. The nitrogen-, phosphor- and/or sulphur-containing product thereby produced, from which organic acids have been separated, is recovered to be used as a fertilizer or as raw material for a fertilizer.

Abstract: Described is a process for concentrating weak black liquor to form strong black liquor, said process comprising: a) preconcentrating said weak black liquor; b) heating said preconcentrated weak black liquor in a heating zone under sufficient pressure to prevent said preconcentrated weak black liquor from boiling in said heating zone; c) passing said preconcentrated weak black liquor, having at least one volatile component, into an evaporation zone through one or more orifices; d) applying pressure in said evaporation zone that is lower than the vapor pressure of said preconcentrated weak black liquor as it is passed into said evaporation zone, which allows for flash evaporation of at least a portion of said at least one volatile component of said preconcentrated weak black liquor from said preconcentrated weak black liquor to form strong black liquor; e) adjusting heat in said heating zone.

Abstract: The present invention relates to an arrangement for introducing black liquor into a furnace of a recovery boiler, said arrangement comprising an elongated tube having an interior surface and an exterior surface, through which tube the black liquor being fed into the furnace is supplied, whereby the black liquor is taken into contact with said interior surface prior to being sprayed into the furnace. The interior surface of said elongated tube is provided with heat transfer elements and surfaces, such as fins or grooves. The heat transfer element or surface increases the heat conductivity between the tube and the black liquor above the conductivity achieved with a normal tube passage.

Abstract: The invention relates to a process for producing cellulose and a fertilizer by-product by using a closed cycle of cooking chemicals and process waters. In the process of the invention, the pulp is bleached by at least partly using potassium hydroxide as a bleaching chemical. Thus, a bleach concentrate rich in potassium is obtained from the bleach filtrate, which bleach concentrate is combined with ashes obtained from the burning of lignin and other organic matter recovered from pulp production as a by-product, in order to be used as a potash fertilizer. The bleach-concentrate can also be used as a potash fertilizer as such. The invention also relates to a potash fertilizer obtained this way.

Abstract: Arrangement for understoichiometric gasification of spent liquor from chemical pulp production, comprising an upper reactor part (2), which upper reactor part is provided with a burner (5) for the spent liquor and with an internally clad reactor jacket (4), and lower separating part (8) for separating a phase of solid and/or molten material, formed on gasification, from a phase of combustible gaseous material. According to the invention, at least the upper reactor part (2), with its clad reactor jacket, is surrounded by an outer vessel (1), with a gap (13) being present between the reactor jacket (4) and the outer vessel (1). Connected to the said gap (13) there are one or more inlets (14) and at least one outlet (21) for a coolant medium.

Abstract: The invention refers to a method for black liquor gasification in recovery boilers, of the type having a lower portion, referred to as a lower furnace and an upper portion, referred to as an upper furnace, black liquor sprayers for introduction of black liquor provided in the boiler above the lower furnace, and a number of combustion air levels, whereby the invention incorporates adding oxygen enriched air to the combustion air or directly into the lower furnace at at least one air level underneath the liquor sprayers for the purpose of creating the best possible reducing conditions in the lower furnace, redistributing from the lower furnace combustion air not needed therein following the addition of oxygen enriched air, thereby significantly reducing upward gas velocity underneath the black liquor sprayers, and introducing the redistributed combustion air in the upper furnace, thereby creating the reducing conditions and a controlled temperature in the lower furnace for emission control.

Abstract: The process according to the present invention relates to the treatment of wastewater discharged from a bleach plant and more particularly treatment of bleach plant alkaline wash filtrate from treatment-steps and/or delignification/bleaching-steps of pulp. Further improvements of known processes are needed for solving the problems associated with the recovery of alkaline filtrates into the chemical recovery system. According to the process of the present invention, alkaline wash filtrate from treatment-steps and/or delignification/bleaching-steps of pulp is treated in a process by the following steps: i) treating at least a part of the alkaline filtrate in order to produce an alkaline concentrate enriched in high molecular weight dissolved organic compounds and a stream depleted in organic compounds, where the share of the alkaline concentrate to the total amount of the alkaline filtrate corresponds to a volume reduction factor (VRP) in the range of from about 2.0 up to about 7.

Abstract: A process for de-watering lime mud in a Krafft pulping process is described. The process includes an improvement which comprises adding an effective water-removal rate enhancing amount of an alkyleneamine to the lime mud prior to filtration. The preferred alkyleneamine is ethyleneamine, that is, an amine having at least one —(CR2-CR2-NH—)— unit wherein each R is independently is H or an alkyl (straight-chain, branched, or cyclic) group of from about 1 to about 10 carbon atoms. Ethyleneamines include ethylenediamine, diethylenetriamine, triethylenediamine, triethylenetetramine, tetraethylenepentamine, piperazine, aminoethylpiperazine, and ethyleneamine mixtures such as mixtures of ethyleneamine oligomers having an average molecular weight of about 200-500.

Abstract: A method is provided for the use of borates in the recausticization of alkali-containing liquors such as those produced in the chemical and semi-chemical pulping of wood and in the oxidation and bleaching of wood pulp. Sodium hydroxide is regenerated from sodium carbonate-containing smelts in such pulp processes by autocausticization through the addition of limited amounts of borate. Autocausticization may be carried out at boron to carbonate molar ratios below 2:1 and at sodium to boron molar ratios exceeding 3:1, resulting in high reaction efficiency. Partial autocausticization using borate may also be combined with conventional lime recausticization for the regeneration of sodium hydroxide from sodium carbonate-containing smelts.

Abstract: The invention relates to a process for producing cellulose and a fertilizer by-product by using a closed cycle of cooking chemicals and process waters. In the process of the invention, the pulp is bleached by at least partly using potassium hydroxide as a bleaching chemical. Thus, a bleach concentrate rich in potassium is obtained from the bleach filtrate, which bleach concentrate is combined with ashes obtained from the burning of lignin and other organic matter recovered from pulp production as a by-product, in order to be used as a potash fertilizer. The bleach concentrate can also be used as a potash fertilizer as such. The invention also relates to a potash fertilizer obtained this way.

Abstract: The invention refers to a method for black liquor gasification in recovery boilers, of the type having a lower portion, referred to as a lower furnace and an upper portion, referred to as an upper furnace, black liquor sprayers for introduction of black liquor provided in the boiler above the lower furnace, and a number of combustion air levels, whereby the invention incorporates adding oxygen enriched air to the combustion air or directly into the lower furnace at at least one air level underneath the liquor sprayers for the purpose of creating the best possible reducing conditions in the lower furnace, redistributing from the lower furnace combustion air not needed therein following said addition of oxygen enriched air, thereby significantly reducing upward gas velocity underneath the black liquor sprayers, and introducing said redistributed combustion air in the upper furnace, thereby creating the reducing conditions and a controlled temperature in the lower furnace for emission control.