Abstract: Resonant tubes of a pulse combustor are immersed in a bed of solid particles in a reaction zone to provide indirect heat from the pulsating combustion gases to the solid particles of the bed. The bed is maintained in an agitated state by a gas or vapor flowing through the bed. Reactant materials are introduced into the agitated bed and undergo reaction at enhanced rates resulting from heat transfer coefficients at least about twice as high as those of steady flow combustors and an intense acoustic pressure level propagated from the pulsating combustor into the reaction zone. The apparatus is useful, for example, to steam reform heavy hydrocarbons and to gasify carbonaceous material, including biomass and black liquor to produce combustible gas at relatively low temperatures, with steam being utilized as the bed fluidizing medium. Black liquor gasification, utilizing sodium carbonate as bed solids, results in liquor energy and chemical content recovery without smelt production.

Abstract: A paper machine forming section with two wire forming units. One of the two forming units is a twin wire web forming unit having a headbox, two wire loops arranged in sandwich-like manner and a drainage element for each of the wire loops. The first web-forming unit has a first section including a curved suction drainage element or roll in the first lower wire loop; a second section with opposing drainage ledges, wherein the drainage ledges are stationary on the upper side and the drainage ledges are developed resiliently pressable on the bottom side; the drainage ledges of the upper and lower sides are arranged staggered with respect to each other in the direction of travel of the wire, and at least the ledges of the upper side are developed with suction; a third section which has at least one suction wire separating element on one side. The second web-forming unit is a hybrid former with a single wire.

Abstract: In a double wire former of a paper machine, a first continuous wire (1) is fed onto an at least partially curved guiding surface (4) so as to converge with a second wire (2), wherein the guiding surface (4) is movable in a form-locked manner relative to the wires. After the dewatering section described above, a further guiding surface (7) follows which, in advantageous embodiments, has an opposite sense of curvature and is fixedly located.

Abstract: A system for providing heated fluidized bed gasification of a residual waste liquor provides a bed of granular material and a source of liquor provided to the material bed. An injector is situated in the material bed and communicates with an air source, a fuel source and a steam source. Fuel and air are combusted in the injector and mixed with the steam which forms a combustion product and steam mixture which is in turn injected into the material bed. The combustion and mixing is separated from the bed material by being confined within the injector. The injector is a bubble cap having at least one hole or an injector made of a porous ceramic material.

Abstract: The present invention relates to an environmental-friendly process for reducing the content of chloride in a liquor inventory of a chemical pulp mill. According to the invention, in a recovery system for pulping chemicals containing sulphur and an alkali metal, precipitator dust formed in a recovery boiler is collected and withdrawn, dissolved in water and electrolyzed for production of chlorine or hydrochloric acid in the anolyte. Since the dust normally contains a large amount of sodium sulphate, sulphuric acid and sodium hydroxide can also be produced in the electrolysis. To reduce the content of impurities, before the electrolysis, the pH of the aqueous solution is adjusted to above about 10 to precipitate inorganic substances which are separated-off together with flocculated or undissolved substances.

Abstract: When producing green liquor for later manufacture of cooking liquor, it is endeavoured that the green liquor shall be readily clarified and/or readily filtered. This endeavour is achieved with the present invention, which relates to a method of producing green liquor in which waste liquor separated from cellulose pulp and derived from a cooking stage and possibly from one or more bleaching stages is worked up including known treatment stages such as evaporation, combustion, smelt dissolving and other green liquor preparation, and in which a calcium containing chemical is added to the waste liquor prior to combustion, or is added at the combustion of the waste liquor. The method is characterized in that carbon deriving from the smelt is caused to equal at most 0.

Abstract: The invention described in the specification relates to a process and apparatus for the reduction of adsorbable organic halide (AOX), chemical oxygen demand (COD) and color bodies from the filtrates generated in a chlorine compound-containing pulp bleaching sequence. The method involves vigorously and intensely mixing certain pulp bleaching filtrates in order to lower the AOX content of the filtrate and the use of a peroxy compound and a ferrous salt catalyst to treat a combined filtrate streams thereby significantly reducing the level of AOX, COD and color in the effluent leaving the pulp bleaching plant.

Abstract: A loading box adjustable in zones thereof for a former of a paper or board machine. The former comprises a twin-wire section including two wires placed one above the other and running in the same transfer direction. In the twin-wire section, a drain box is mounted at one side of the wires to remove water out of a fibrous pulp running between the wires. At the opposite side of the wires, a loading box is mounted and is provided with loading ribs arranged in the transverse direction in relation to the transfer direction and which extend across the web width. The loading ribs are loaded toward the bottom of the drain box in order to produce a desired compression in the fibrous pulp running between the wires. The loading box is provided with loading members arranged to produce a locally raising or lowering force applied to the loading ribs in the direction transverse to the transfer direction.

Abstract: The invention relates to a process for dividing up the sulphide content of green liquor into a sulphide-rich part and a sulphide-poor part by crystallizing out sodium carbonate (Na.sub.2 CO.sub.3). The crystallization of the sodium carbonate is effected by evaporating green liquor with a ratio of hydroxide ions [OH.sup.- ] and sulphide ions [HS.sup.- ] such that the liquor which is obtained after evaporation and separation of the solid phase has high sulphidity and an acceptably low content of carbonate ions [CO.sub.3.sup.2- ]. Prior to evaporation, the hydroxide ion content in the liquor is increased by adding quicklime (CaO). The solid phase (sodium carbonate and calcium carbonate) which has been separated off is diluted with water so that the sodium carbonate crystals go into solution and at the same time the solution is given a cation content which favours the causticization which is subsequently undertaken. The causticization is carried out in a conventional causticization plant.

Abstract: A paper machine forming section with two twin-wire sections for forming a multilayer paper web. Each twin wire web-forming unit consisting of a headbox, two wire loops arranged to define a common wire path for molding the web being formed in sandwich-like manner and drainage elements for each of the wire loops. The common wire path of each web-forming unit has a first section including a curved suction drainage element or roll in the first lower wire loop; a second section including opposing drainage ledges, wherein the drainage ledges are stationary on the upper side and the drainage ledges are developed resiliently pressable on the bottom side; the drainage ledges of the upper and lower sides are arranged staggered with respect to each other in the direction of travel of the wire, and at least the ledges of the upper side are developed with suction; and a third section which has at least one suction wire separating element on one side.

Abstract: The invention is related to a twin-wire web former in a paper machine having a covering wire and a carrying wire which form a twin-wire forming zone with one another. A discharge opening of a headbox feeds a pulp suspension jet into the forming gap defined between said wires. The forming gap is immediately followed immediately by a forming shoe provided with a curved guide deck. A draining unit or units is/are provided after the forming shoe, before the first forming roll. The draining unit/units comprise(s) a press/support unit which guides the wire placed in contact with it as a straight run. The draining unit or units further comprise(s) a draining equipment provided with suction and foil equipment and placed opposite to the press/support unit, which draining equipment removes a substantial amount of water out of the web.

Abstract: A hybrid former in a paper machine including a lower-wire loop in which there is an initial single-wire portion of a forming zone. In this initial portion, there are draining elements inside the lower-wire loop and thereafter wire-guide and draining elements. The former includes an upper-wire unit in which an upper wire is guided by guide rolls and by a breast roll onto a pulp layer formed on the single-wire portion of the lower wire. In a subsequent twin-wire portion following the single-wire portion, there is a draining and forming unit which includes at least one pressure-loaded press unit and at least one draining-chamber and support unit, which units are arranged inside opposite wire loops. In the units, there are sets of ribs which are pressure-loaded against each other.

Abstract: A method for recovering fiber useful for papermaking from an effluent stream includes a primary process for treating an effluent stream to separate usable fiber from contrary matter, and secondary operations, supplementing the primary process, to treat the contrary matter rejected by the primary process to recover usable fibers contained in the reject matter. In addition, the secondary processing steps separate the reject material into organic and inorganic fractions, which may be usable in other processes. The method of the invention does not require the addition of water as do conventional processes, simplifies handling, disposal, and reduces the costs of disposal.

Abstract: A twin-wire section with a first and a second endless wire, for forming a fiber material web of a fiber suspension, notably for forming a ply of a multiply paper or cardboard web, the ply being merged on a third wire with a further ply. In the twin-wire zone formed by the first and second wires, a dewatering box (touching the one wire) that features rigid slats is contained in the loop of the one wire, while in the loop of the other wire there are contained several backing slats which can be pushed flexibly on the other wire, while a loop of one of the two wires contains a forming roll which together with said wire forms a looping zone. The forming roll has a smooth, continuous roll shell. The wire which in the looping zone is outside separates from the web and the inner wire at a distance before the end of the looping zone.

Abstract: A twin wire former of a paper machine can perform dewatering gently and symmetrically on the front and back sides of the wet paper, thereby producing paper with good yield and excellent front/back similarity. The twin wire former includes the loops of two wires, and first, second and third dewaterers, having large radii of curvature and disposed inside one and the other of the loops of the wires sequentially alternately between a point where a raw material jet alights on the wires and a couch roll, and the wire-run over this section is diagonal. The first and third dewaterers are disposed inside the loop of the wire and the second dewaterer is disposed inside the loop of the wire. This second dewaterer is pivotable about a point in the vicinity of its rear end, and the couch roll is a solid roll. This couch roll, a transfer suction box and the third dewaterer are mounted on a swing arm and can be pivoted for wire installation.

Abstract: The invention relates to a twin-wire web former for a paper machine wherein a covering wire and a carrying wire form a twin-wire forming zone between them. A method for dewatering a web is also disclosed. In the invention, water is drained out of a web running through the twin-wire zone through both of the wires. After the twin-wire zone, the web is separated from the covering wire and is transferred on the carrying wire to a pick-up point. In hybrid formers, after an initial single-wire forming zone preceding the twin-wire zone, and in gap formers, after a curved forming zone placed directly after a forming gap, there is a forming shoe provided with a ribbed deck and arranged inside one of the wire loops. This forming shoe is followed by dewatering and web forming units which include forming ribs and are placed inside both of the wire loops. At least one of the dewatering and web forming units is loaded by means of a pressure-hose arrangement.

Abstract: A method for the recovery of chemical values from spent lignocellulosic pulping liquor salts to produce white liquor of different sulfidities. Preferably, the white liquor is in the form of separate liquid streams, each of which is of a sulfidity that is different from the sulfidity of others of the streams. The method also provides for developing a white liquor stream which is essentially free of sulfide values, but which contains sodium hydroxide. Further, the method provides for recovery of titanium values for recycling.

Abstract: A tissue web (W), which has improved formation and improved tensile properties but no appreciable deterioration of retention and layer purity, if applicable, in comparison with tissue webs produced in conventional twin wire tissue formers, may be formed in a roll type twin wire former by draining 90-99%, preferably 98-99%, of all drainable water from the slurry while on the forming roll (1), preferably a suction forming roll, the remaining 1-10%, preferably 1-2%, of the drainable water being sufficient to have a substantial amount of the papermaking fibers free in the slurry during an initial phase of a subsequent step, and, downstream of said forming roll (1), draining said remaining 1-10%, preferably 1-2%, from the slurry while vibrating the slurry sufficiently to create a micro-turbulence causing a small scale agitation of the fibers to prevent them from forming any appreciable fibrous web (W) on the two forming fabrics (3; 4) until the water remaining in the slurry is insufficient for allowing the fibers

Abstract: A twin-wire web former in a paper machine, having a single-wire initial portion, after which a twin-wire zone starts in the area of a ribbed deck of a first forming shoe placed inside one of the wire loops. After the first forming shoe, a pressure-loaded dewatering unit is arranged and which includes opposite sets of ribs and dewatering chambers. A first dewatering chamber in the dewatering unit is placed above the first forming shoe so as to remove water that drains from the area of the curved ribbed deck of the first forming shoe through its suction-deflector duct. The first dewatering chamber is followed by a second dewatering chamber, whose lower part is connected with a set of dewatering and guide ribs having gap spaces into which a drain duct of the second dewatering chamber opens. Against the set of dewatering and guide ribs, a set of loading ribs operates, which is placed inside the opposite wire loop and which operates by means of the medium pressure of loading hoses.

Abstract: A wire section of a machine for making a fiber web, with two continuous wires forming together a twin-wire zone. A dewatering element is pressable on the inside of the wire with at least one surface. The dewatering element features in the direction of travel of the fiber suspension, in interaction with the wires, two dewatering zones. The first dewatering zone is defined by an essentially flat surface, while a second dewatering zone is defined by a surface curving about an axis of curvature in the direction of travel of the fiber suspension. Coordinated with the dewatering element are at least two support axes on which support elements are arranged. Coordinated with the dewatering element is a pivot axis. The pivot axis is stationary as regards the tilting operation, and extends parallel to the separation plane between the first and second dewatering zones and parallel to the wire. The pivot axis is arranged in the area of the axis of curvature.

Abstract: A method, device, and arrangement in a paper machine for regulating the control of the transverse profile or profiles of properties of a paper web produced therein. Water is removed from the paper web under compression between two forming wires by making use of dewatering and/or forming ribs. The deflection of the dewatering and/or forming ribs in the transverse direction of the web is regulated thereby affecting the retention profile of the paper web in the cross direction. By regulating the deflection of the dewatering and/or forming ribs, the transverse fiber-orientation profile and/or the filler profile of the paper web is influenced through the control of the transverse retention profile of the web.

Abstract: Apparatus for a pulp and paper mill, and methods of acting on liquid effluents produced in the mill, which minimizes the discharge of polluting gaseous and liquid effluents to the environment. Liquid effluents from the bleach plant are concentrated (e.g. evaporated), incinerated (e.g. gasified), leached, crystallized (e.g. freeze crystallized) then washed, and then fed to the plant chemical recovery loop. White liquor produced from the recovery boiler melt is fully oxidized and used in place of caustic in the bleach plant. Essentially all sulfuric acid, sulfur dioxide, caustic, and chlorine dioxide necessary for the pulp mill is produced from mill liquid effluents and gas waste streams, on site at the pulp mill. Typical bleaching sequences that can be used are DE.sub.op D.sub.n D, or AZE.sub.o PZP.

Abstract: An improved black liquor recovery system for use in a kraft pulping mill is provided. Molten kraft smelt from a black liquor recovery boiler or recovery system is fed into a fluidized bed reactor where it is cooled and solidified to form solid kraft smelt particles. The solid kraft smelt particles are then fed into a dissolving tank containing an aqueous solution to form a green liquor. The green liquor, after clarification, is treated with lime to form a white liquor containing the regenerated pulping chemicals. Waste steam is an especially preferred fluidizing gas for use in the fluidized bed reactor. This process provides improved energy recovery and process productivity, reduction in gaseous sulfur-containing emissions, reduction in landfilled wastes, and improved safety as compared to a conventional kraft smelt treatment process.

Abstract: The invention relates to a twin-wire web former for a paper machine wherein a covering wire and a carrying wire form a twin-wire forming zone between them. A method for dewatering a web is also disclosed. In the invention, water is drained out of a web running through the twin-wire zone through both of the wires. After the twin-wire zone, the web is separated from the covering wire and is transferred on the carrying wire to a pick-up point. In hybrid formers, after an initial single-wire forming zone preceding the twin-wire zone, and in gap formers, after a curved forming zone placed directly after a forming gap, there is a forming shoe provided with a ribbed deck and arranged inside one of the wire loops. This forming shoe is followed by dewatering and web forming units which include forming ribs and are placed inside both of the wire loops. At least one of the dewatering and web forming units is loaded by means of a pressure-hose arrangement.

Abstract: A method for inhibiting the formation, deposition, and adherency of scale-forming salts, including calcium sulfite, in process waters. The method is particularly suited for use in pulp mill lime kiln flue gas scrubber systems and multi-effect evaporators. Additionally, the method is effective at high pH and high calcium sulfite saturation levels.

Abstract: In minimizing effluents from a cellulose pulp mill, liquid effluents from a bleach plant are concentrated, and then incinerated to produce a residue including sodium, sulfate, and sodium chloride. This residue is distilled with sulfuric acid to produce gaseous hydrogen chloride and remaining residue, the HCl being used in chloride dioxide production for the bleach plant, while the remaining residue is passed to the recovery loop (e.g. recovery boiler). Sulfur containing gases from the non-condensible gas system may be combusted to produce gaseous sulfur dioxide, which is then converted to sulfuric acid, to distill the residue. Where a non-chlorine bleach plant is provided, the liquid effluents may be concentrated in evaporators and then passed directly to the recovery boiler. The liquid streams in the mill are managed by a cascade principle to reserve the cleanest water for only those processes where it is needed while minimizing its use where it is not necessary.

Abstract: The sulphur content and/or the sulphur compound composition of a melt in a recovery boiler of a pulp mill is adjusted by bringing a gas into contact with the melt. The gas may be a gaseous sulphur compound or a reducing gas. Bringing the gas into contact with the melt increases the sodium sulphide content of the melt while decreasing the sodium carbonate content, so that the sulphidity of the melt increases. The sulphur-containing gas may be produced by pressure heat treatment of black liquor, so that the black liquor burned in the recovery boiler has a lower sulphur content and thereby reduces the boiler sulphur emissions, and boiler corrosion problems.

Abstract: The removal of bleaching chemical-consuming metals from treatment fluids in a cellulose pulp mill is facilitated by treating the pulp in an acidic or neutral stage to dissolve metals, washing or thickening the pulp to produce a filtrate containing dissolved metals, and then using an alkali liquid to adjust the pH of the filtrate to cause dissolved metals to precipitate. The alkali liquid is pretreated with carbon dioxide to reduce the sulfide content and increase the carbonate content thereof, preferred alkali liquids being green liquor and white liquor. The reduced-metal content filtrate is used in the bleach plant of the pulp mill, to make bleaching chemicals, as a wash liquid, etc. Treatment of the alkali liquid with carbon dioxide is typically practiced by scrubbing the liquor with carbon dioxide gas, for example, using a plate column scrubber or a stationary packing scrubber.

Abstract: In a chemicals recovery plant in a sulphate pulp mill, in order to provide green liquor with improved sedimentation and filtration properties, there is passed, from a flow (10) of slaked lime and green liquor between a lime slaker (9) and a causticizing tank (1 1), a partial flow (32, 35) to a soda dissolver (2) or to a container (26) for unclarified green liquor provided after the soda dissolver. For this purpose there is provided, in a line (10) between the lime slaker (9) and the causticizing tank (11), a branch line (32, 35) which passes to the soda dissolver (2) or to a container (26) for unclarified green liquor provided after the soda dissolver.

Abstract: The twin-wire former serves for the production of a web of paper or board. Two wire belts (endless wire loops 11 and 12) form a twin-wire zone with each other. Within the twin-wire zone, the one wire belt (12) travels over rigid ledges (28', 28) which are arranged spaced apart from each other on a water-removal box (18). Within the twin-wire zone, furthermore, the other wire belt (11) travels over several ledges (27) which lie opposite the rigid ledges (28), are supported by means of resilient elements (springs 24, pneumatic pressure cushions, or the like), and can be pressed with a selectable force against the other wire belt. Within one of the wire loops (for instance 11), bridging at least two of the ledges (27) present there, a closed wire support surface (9) is provided. A secondary headbox (10') can be arranged in front of the closed wire support surface (9).

Abstract: In a twin-wire former for the production of a paper web, two wire belts (11 and 12) together form a twin-wire zone which is divided into three sections (I, II and III). In the first section (I) the two wires (11, 12) travel over a curved forming shoe (16). They form there a wedge-shaped inlet slot (15) with which a headbox (10) is directly associated. In the second section (II), several resiliently supported strips (27) rest against the lower wire (11) and between each of said strips (27) a rigidly mounted strip (28) rests against the upper wire (12). In the third section (III) both wire belts (11, 12) pass over another curved forming shoe (23).

Abstract: A twin-wire former for a paper machine having two endless loop wires, a wire support frame and a head box. The web forming zone leading from the entrance slot, which is at the breast roll in one wire loop and the forming roll in the other wire loop, is inclined at an angle of 30.degree. to 50.degree. to the horizontal. The wire support frame has the shape of an inverted U with a front support arranged upstream of the head box, a rear support arranged downstream of the headbox and an upper beam which connects the upper ends of the front and rear supports to each other. A lower beam is located within the loop of the lower wire and extends to both of the forward and rearward sides of the rear support with one end extending into the U-shaped frame while the other end extends at least approximately up to the remote end of the loop of the lower wire. At least one water removal element of the upper wire is suspended from the upper beam. At least one water removal element of the lower wire rests on the lower beam.

Abstract: An adjustable twin-wire gap former is provided for forming a fiber web from an aqueous fiber suspension. The twin-wire gap former is arranged so that the first and second coacting, traveling, looped forming wires have juxtaposed sections, which define a forming zone and confine a paper web therebetween during its formation. A first means for providing suction is located adjacent the first wire fabric in the forming zone for draining water from the suspension and a second means for providing suction is located adjacent the second wire fabric in the forming zone. This second means for providing suction is movable toward and away from the second wire thus adjusting the geometry of the forming zone. Preferably a central operator controls the vacuum in the suction boxes and the pressure exerted by the boxes onto the forming fabric independently of each other.

Abstract: A method and reactor for thermally decomposing a carbonaceous raw material (6) to recover gas and, if applicable, solid or liquid chemicals, the raw material being fed into a chamber (2) for gasification under under-stoichiometric conditions, the gasification is carried out in a gasification zone (15) at a pressure from atmospheric pressure up to about 150 bar and at a temperature within the range 500.degree.-1600.degree. C. According to the invention a part of the thermal energy required to maintain the endothermic reactions in the gasification zone (15) is produced by combustion of a fuel (8) in a combustion zone (16) located close to and in gaseous contact with the gasification zone, the raw material and fuel being supplied through different nozzle channels (12 and 13, respectively). An oxygen-containing gas (17) is supplied in an amount sufficient to oxidize substantially all the fuel.

Abstract: To decrease the sulfur emissions of a sulfate pulp mill, and achieve other advantages, black liquor is heated at a temperature higher than the cooking temperature of the sulfate cook (e.g. between 190.degree. C.-350.degree. C.) and the sulfidity of white liquor produced from the black liquor is adjusted by adjusting the temperature and/or retention time of the heat treatment so that a predetermined amount of sulfur compounds are separated from the black liquor. Pressure heat treatment may occur prior to or after evaporation of the black liquor, or between evaporation stages. Preferably, the sulfur containing gas is thereafter divided into different fractions which are separately cornbusted.

Abstract: Method and device for controlling a wire in the forming gap of a twin-wire web former of a paper machine, which gap is defined between two opposite forming wires. A pulp suspension jet is fed out of the discharge opening of the headbox of the paper machine into the forming gap. The jet has a free flight distance before it meets the forming wires. In the area of the forming gap, a variable-crown or adjustable-crown breast roll is employed as the breast roll of at least one of the wires. The deflection of the mantle of this breast roll is regulated actively from inside the mantle of the breast roll. In this manner, the transverse tightness profile of the wire guided by the breast roll and/or possible instabilities of the wire is/are controlled in particular in the area of the forming gap.

Abstract: The wire end or forming section of a paper making machine is a twin wire section defined by two endless loop wire belts or wires between which fibrous suspension moves through the wire end. A supporting element, either in the form of a rotating cylinder or in the form of a support belt, has the wires passing over it in the twin wire zone. Pressure elements, in the form of strips, rods or even a shoe, are supported to apply pressure on the wire belts and directed toward the moving supporting surface. The pressure elements are placed along the twin wire path so that pressure free regions remain between neighboring pressure elements. The pressure elements are distributed over the entire width of the wire belts.

Abstract: The invention relates to a method and apparatus for use in the pulp industry for improving the safety of a spent liquor recovery boiler, such as a soda recovery boiler. The boiler comprises, for recovering chemical and energy, a furnace cooled by water tubes and connected to the water/steam circulation system of the boiler, the cooling of the bottom of the furnace being provided by a separate cooling circulation. The separately cooled lower section of the furnace is provided by separating the bottom or the bottom and part of the furnace walls from the boiler water circulation system. This separated section is supplied with a cooling fluid of its own which may be a gas (e.g. air or inert gas) or a liquid (e.g. molten zinc) which does not cause an explosion of it contacts the melt of the furnace.

Abstract: A wire or felt forming section of a paper-making machine has breast rollers for guiding a respective one of two forming wires. The two rollers are disposed with a pulp gap formed between the two rollers and the wires are disposed just downstream of a pulp suspension ejecting nozzle of a headbox. Each roller is supported against the respective taut forming wire by a hydrostatic bearing. The hydrostatic bearing has two circumferentially separated resiliency chambers provided in a combined region of resiliency disposed over an arc of the circumference of the roller. A sealing strip after the region of resiliency prevents fluid from contacting the wire.

Abstract: A suction roll for a paper machine in which a stationary suction shoe is arranged inside a revolving mantle loop and is connected to a source of negative pressure. The mantle loop is a substantially water-receiving and permeable fabric-sock loop that receives water and is, in a preferred embodiment, supported by means of guide members arranged inside the loop. The suction shoe is provided with a permeable guide deck against which the inner face of the fabric-sock loop glides.

Abstract: A papermaking apparatus that can form a paper web having a good fiber formation is disclosed. A plurality of vertically adjustable forming rolls are provided on the top surface of an endless felt couch between a lead-in roll and a couch roll, and stationary forming bars are provided on the bottom surface of a wire screen. The endless felt couch and the wire screen, between which paper stock is interposed, are caused to move by undulation to generate pulses, which in turn apply shear force onto the paper web to dewater the paper web while facilitating fiber dispersion on the paper web.

Abstract: The invention relates to a method of firing black liquor in recovery boilers where the intention is to obtain fumes having a low content of nitrogen oxides (NO.sub.x). A part of the combustion air is added as a last portion at a very high level so that a reducing atmosphere will exist in a very great part of the boiler for a long time period, e.g. at least 3-5 seconds.

Abstract: This invention relates to an alkaline scrubber for condensate stripper off-gases. In particular, this invention relates a process for selectively removing hydrogen sulfide and methyl mercaptan from a gas stream containing these compounds and methanol. Such gas streams are commonly generated during pulp and paper production.

Abstract: A method of recovering energy and chemicals from a spent liquor which, after thickening to a dry content of 50-90%, is fed into a reaction chamber (1) in which a plurality of temperature zones are maintained, said method comprising the steps of (a) converting the liquid phase in the spent liquor to a steam phase, (b) thermally decomposing the spent liquor to form gaseous organic substances and solid and/or molten organic and inorganic substances, (c) reducing and (d) oxidizing said substances produced during the thermal decomposition, oxygen or oxygen-containing gas being supplied to the reaction chamber (1) in a controlled amount in order to maintain the reactions, which comprise combustion of organic substances, and a bed of said solid and/or molten substances being formed in a lower temperature zone in the reaction chamber (1). According to the invention said steps are carried out during exposure to low frequency sound.

Abstract: Liquid effluent from a pulp mill bleach plant having at least one chlorine chemical bleach stage is evaporated and then used in chlorate manufacture. The bleach plant effluent produced by evaporation may be stored and then transported to an off-site chlorate production location, and/or may be subjected to a sodium chloride removal process (such as evaporative crystallization) and only sodium chloride transported to the off-site location. Chlorates produced off site can be returned to the mill (with acid and caustic that are optionally produced) for chlorine dioxide manufacture on site. The chloride-depleted stream from sodium chloride removal may be burned in the mill recovery boiler.

Abstract: A dewatering instrument of a twin-wire former allows the angles at which the wires are wrapped around the dewatering blades to be adjusted even during operation so that pulsating pressure applied to the paper stock may be set appropriately according to the prevailing paper making condition. The respective dewatering blades of the dewatering instrument are supported by two support bodies, the first one of which is fixed and pivotably supports the blade, and the second one of which is movable to pivot the blade about the first. For example, the second support body may be a flexible tube which is inflatable and deflatable. When the blade is pivoted, the attitude of the land of the blade is changed so that the wrap angles of the wires with respect to the land of the dewatering blade are adjusted.

Abstract: A multi-ply web forming apparatus is disclosed for forming a top ply on a base ply. The former includes a looped lower forming wire for receiving the base ply thereon and a top looped forming wire cooperating with and disposed above the lower wire for defining therebetween a generally horizontally disposed forming section having a first and a second end. A turning bar defines a curved surface for guiding the lower wire. A secondary headbox ejects stock towards and onto the base ply. A curved dewatering shoe is disposed beneath the lower wire such that a portion of water from the top ply is ejected through the top wire. A vacuum slot collects a portion of water upwardly away from the top wire. An inverted vacuum box is disposed downstream relative to the vacuum slot and a plurality of dewatering blades disposed between a curved face of the vacuum box and the top wire guide the top wire therepast.

Abstract: A black liquor gasification system intended for use as a replacement for a Tomlinson cycle, Chemical Recovery Unit, and which operates at a temperature below the ash melting temperature thereby removing the potential for smelt-water reactions and explosions. The subject black liquor gasification system is based on the use of a circulating fluidized bed operating at atmospheric pressure that produces dry, recoverable salts as well as low calorific gases to be used within the paper-making process.

Abstract: In general, the invention features method for regulating sulfur dioxide emissions from the recovery furnace of a Kraft paper mill.

Abstract: A two-wire web-forming section for a paper machine includes two wire loops, consisting of a first wire (1) and a second wire (2), water draining therethrough from a web (W) to be formed in two directions within a two-wire dewatering zone established by the wires. A breast roll (4) guiding first wire (1) is open and a constricted slice jet (S) comes into contact with first wire (1) within the contact area of open roll (4) and with second wire (2) downstream of breast roll (5) guiding it. The distance (1) of wire (1) lying on open breast roll (4) at the diverging point of the first wire and breast roll (4) from said second wire (2) lying straight between its own breast roll (5) and the guide element (6) guiding the wires together is less, preferably 1-4 mm less than the thickness of the constricted slice jet (S).