Abstract: A method for the fractionation of lignocellulosic materials into reactive chemical feedstock in a batch or semi continuous process by the stepwise treatment with aqueous aliphatic alcohols in the presence of sulfur dioxide or acid. Lignocellulosic material is fractionated in a fashion that cellulose is removed as pulp, or converted to esterified cellulose, cooking chemicals are reused, lignin is separated in the forms of reactive native lignin and reactive lignosulfonates and hemicelluloses are converted into fermentable sugars, while fermentation inhibitors are removed. In an integrated vapor compression stripper and evaporator system, aliphatic alcohol is removed from a liquid stream and the resulting stream is concentrated for further processing.

Abstract: A method for the fractionation of lignocellulosic materials into reactive chemical feedstock in a batch or semi continuous process by the stepwise treatment with aqueous aliphatic alcohols in the presence of sulfur dioxide or acid. Lignocellulosic material is fractionated in a fashion that cellulose is removed as pulp, or converted to esterified cellulose, cooking chemicals are reused, lignin is separated in the forms of reactive native lignin and reactive lignosulfonates and hemicelluloses are converted into fermentable sugars, while fermentation inhibitors are removed. In an integrated vapor compression stripper and evaporator system, aliphatic alcohol is removed from a liquid stream and the resulting stream is concentrated for further processing.

Abstract: A method of treating cellulose pulp mill condensates having an MeOH content using an evaporator and a steam stripper having a reboiler, comprising: (a) Collecting a feed liquor stream having at least 50% of the pulp mill MeOH. (b) Feeding the feed liquor stream to the evaporator having at least two heating element sections separated on a motive steam side. (c) Evaporating the liquor in the evaporator to produce a vapor containing at least 40% of the at least 50% of the pulp mill MeOH. (d) Compressing the vapor from (c) to increase the vapor pressure. (e) Using the vapor from (d) as condensing heating media in (c) for the evaporation in a first heating element section of the evaporator and venting a portion of the vapor through the first heating element section. (f) Compressing the vented vapor from the heating elements of the evaporator from (e) to increase the vapor pressure to be used as heating media in the reboiler.

Abstract: Effluents are minimized from a cellulose pulp mill having a recovery boiler by concentrating liquid effluents from the bleach plant and/or liquid spills from process streams, incinerating the concentrated effluents in the recovery boiler, removing particles present in the flue gases from the recovery boiler to produce an ash including salts containing potassium and chloride, and sulfur compounds, and removing the potassium and chloride from the ash while returning the sulfur containing compounds to the recovery loop, so as to balance the sulfur, chloride and potassium levels in the mill. The sulfur is typically returned directly to a stream of black liquor just before entry into the recovery boiler. Green liquor is produced from the melt, which preferably is treated to remove metals from it prior to caustization (e.g. by sedimentation and/or filtration), and prior to green liquor crystallization to produce sodium hydroxide.

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: 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: A pulp mill has zero or minimum liquid discharges. The large amounts of liquid that must be processed to achieve this result are handled utilizing a multiple effect evaporator provided with heat from a steam exhaust of a condensing type steam turbine. Super heated steam from the recovery and bark boilers is fed to the turbine to generate electricity for the production of bleaching chemical and other uses in the mill. Three or four steam exhausts having different composite temperature and pressure values are taken from the turbine and used where most suitable in the pulp mill. For evaporation of bleach plant effluent the steam taken from the turbine preferably has a pressure of about 1-3 psia and a temperature of about 120.degree.-140 .degree. F, and has no significant adverse affect on power generation.

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: Paper pulp (e.g. kraft pulp) is produced utilizing at least two different supplies of cooking liquor, one having low sulfide content, and the other high sulfide content. The high sulfide content supply is typically used to impregnate the pulp or otherwise treat it first, while the second supply is used in other cooking stages (e.g. a digester), whether co-current or countercurrent. The different sulfur content liquors are obtained by heat treating (under pressure) black liquor to drive off sulfur compounds, and absorbing them into white liquor to produce a high sulfide stream. The low sulfide stream is made by conventional treatment of the black liquor after heat treating and evaporation. Utilizing multiple sulfide content supplies results in an optimum viscosity/kappa ratio and/or pulp strength properties for the pulp produced.

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: Apparatus and method for evaporating a liquid includes a casing; a plurality of vertically extending plate-type heating elements within the casing, each heat element having an outer surface and an inner surface and a vertical edge, the heat elements being spaced and forming an open channel along the vertical edge between adjacent elements; a distributor above the heating elements for distributing the liquid over the elements; an inlet connected to the heating elements for introducing a heating medium and for generating vapor from the liquid; and a wall-like device mounted within the casing facing the spaces between the heating elements for collecting and guiding the vapor generated in the evaporator. Preferably, the wall-like element includes a droplet separating device formed by vertically elongated spaced elements having a substantially U-shaped cross-section with inwardly pointing vertical edges.

Abstract: A falling film evaporator includes a chamber having a top and bottom tube plate; a plurality of vertical tubes each having an interior and exterior surface and extending through the chamber and being supported by the top and bottom tube plates; an inlet at the chamber for feeding heating medium into the chamber; a distributor above the tubes for feeding liquid to be evaporated into the tubes and for causing the liquid to be distributed as a falling film along the interior surface of the tubes so as to evaporate the liquid and generate vapor as the liquid passes in heat exchanging relationship with a heating medium present at the exterior surface of the tubes; a vapor space defined by a circumferential wall below the tubes; a plurality of vertically elongated spaced elements having a substantially U-shaped cross-section with inwardly pointing vertical edges for receiving the evaporated liquid and the vapor, the elements being arranged in a circumferential wall below the tubes within the vapor space spaced from

Abstract: A method and apparatus for deaerating a suspension of solids in a liquid such as, for instance, papermaking stock. The suspension is flashed in a vacuum tank connected to a condenser. The vapor released when the suspension is flash cooled in the tank is condensed into an absorption liquid having a higher temperature but a lower vapor pressure than that of the released vapor on a heat exchange surface of the condenser. The flash cooled suspension is used as the cooling medium in the condenser. The diluted absorption liquid is regenerated in an evaporator and recirculated to the condenser. The vapor released in the evaporator can be condensed to heat the suspension further or for other suitable heating purposes.

Abstract: A method of drying black liquor to a dry solids content of about 100% in which water is evaporated from the black liquor by direct heat exchange contact with hot smelt from a recovery furnace in which the dried black liquor is burned.

Abstract: Wet air preferably from a liquid ring pump is dehumidified by the use of a desiccant liquid absorber. The heat released by condensation of water vapor in the absorption liquid will be taken up by the air. The air is further heated by water vapor produced by regenerating the absorption liquid. According to a preferred embodiment of the invention, the source of the wet air is a suction box in the forming section, couch roll or pick-up roll of a paper machine and the hot air is used as pocket ventilation air in the dryer section of the paper machine.

Abstract: A method and system for cooling pulp discharged from a batch type digester and recovering heat from it. A stream of pulp together with spent cooking liquor is discharged from a batch digester to a diffuser and passed through the diffuser at substantially the same pressure as that of the digester. The pulp stream is caused to flow between screens and hot spent cooking liquor is displaced with cooler liquor flowing across the pulp stream thereby lowering the temperature of the pulp stream. The displayed cooking liquor and the pulp is withdrawn from the diffuser.

Abstract: Process for the evaporative concentration of liquids. Vaporization is carried out by indirect heat exchange with a heating fluid in an evaporator. The vapor produced in the evaporator is thereafter condensed in a condenser by indirect heat exchange with a cooling liquid which is mainly composed of the liquid to be concentrated or the liquid which has already been concentrated in the evaporator. The vapor pressure over the cooling liquid in the condenser may be lowered by causing gas to flow in contact with the cooling liquid.

Abstract: A process and apparatus for the gasification of partially dried fuel with hot gas which has been heated by bringing it into contact with an inert hot heat carrier. The fuel gases generated during the gasification process are further combusted and utilized for heating the inert heat carrier. The process and apparatus can be combined with a process and apparatus for generating steam from wet fuel wherein water is evaporated from the wet fuel by bringing the fuel into direct contact with superheated steam. The steam is superheated by bringing it into contact with a second hot heat carrier. The second heat carrier is heated by bringing it into direct contact with the fuel gas produced by combusting the fuel gas from the gasification process.

Abstract: A method for recovering turpentine and heat in a TMP process in which woodchips are heated in a preheater and the vent vapors from the preheater are passed to the condensing vapor zone of an evaporator condenser-reboiler having a condensing vapor zone and a boiling liquid zone. A major portion of the vent vapors are condensed so as to produce a turpentine-lean condensate and turpentine-rich vapor phase. The turpentine-rich vapor phase is withdrawn from the evaporator and passed to a turpentine condenser where it is cooled by indirect heat exchange contact with a cooling liquid to produce a condensate containing immiscible turpentine and aqueous phases. The turpentine and the aqueous phases are separated.

Abstract: In a method and apparatus for drying a particulate material, for instance bark, the material is disposed as an annular bed (11) on a perforated disc (10). The bed is moved along the disc by being rotated about its axis by pushing members (12). A surface layer of moist material is continuously deposited on the upper surface of the bed in an area extending over the entire width of the bed, while at the same time a corresponding surface layer of dried material is continuously removed from the lower surface of the bed in a substantially corresponding area (17), so that the bed thickness is substantially maintained uniform over the entire area of the bed. A uniform moisture content is imparted to a drying medium which is passed through the support disc and the bed, the medium is preferably saturated with moisture before leaving the bed.