Abstract: A chip bin for wood chips in a continuous digester system includes internal steaming that is controlled in response to both the interior temperature across the level of chips in the bin, and the level of chips in the bin, so as to substantially prevent cool, non-condensible gas-laden chips from accumulating at the top of the chip column in the bin, and to substantially prevent steam blow-through. The temperature probe used in the chip bin has a temperature sensing portion with a length of about ten to twenty feet instead of the conventional five foot length, and extends across the level of the chips to a position about five feet below the level of chips. Control of steam added to the bin is provided utilizing a controller which controls the position of one or more valves in one or more steam conduits, each valve having multiple open positions and a closed position.

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 apparatus for screening and thickening cellulose pulp keeps cleaner than conventional apparatus. Pulse members in accordance with the prior art are constructed so that when the capacity of the screening apparatus is increased, for example by using greater pressure differences or the cleanliness of the accept is increased by decreasing the size of the perforations or slots, a situation is created in which the screen cylinder tends to clog. The pulse member of the present screening apparatus subjects the screen cylinder or screen surface to a pulse cleaning action so that there is a minimal possibility to allow the pressure effect to "escape" past the area being cleaned. The higher the consistency of the fiber matting is or the worse the screen surface is clogged, the stronger the pulse cleaning of the screen surface.

Abstract: Particles in a fluidized bed reactor (e.g. a circulating fluidized bed reactor) are discharged from the reactor chamber and then cooled (heat is recovered from them) in a processing chamber. This is accomplished in a particularly advantageous way by discharging the particles from the reactor chamber at a first level (e.g. through a non-mechanical seal or a classifying wall) into a lifting chamber. Upwardly flowing gas in the lifting chamber entrains the particles and lifts them into the processing chamber. After processing, the particles in the processing chamber are returned to the reactor chamber at level higher than the first level, at which point the pressure in the processing chamber is higher than the pressure in the reactor chamber. The particles may be classified in the lifting chamber by utilizing fluidizing gas to transport solid particles smaller than a predetermined size to the processing chamber while discharging larger particles from the bottom of the lifting chamber.

Abstract: An apparatus for the discharge of a mass tower containing medium to high consistency pulp and operable without the need for further dilution includes a vessel for storing the pulp; a suction duct extending from a zone of moving pulp to a region outside of the tower; and a pump attached to the end of the suction duct for discharging the pulp.

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: The present invention relates to a mixing of gas into a medium. The method and apparatus in accordance with the present invention are especially applicable in the bleaching plants of the wood processing industry for mixing gaseous bleaching chemicals into pulp and to bleaching process of pulp, in which the mixing method and apparatus in accordance with the present invention are applied. An excellent application is mixing ozone-containing gas into a fiber suspension flowing in a pipe line and an ozone bleaching process. The previously known methods and apparatuses have not been able to mix satisfactorily large volumes of gas, about 50% of the total volume of the flow, into the medium flow.

Abstract: A fluidized bed reactor system includes a reaction chamber comprising a circulating (fast) fluidized bed, with a first grid for the introduction of fluidizing gas, and a bubbling (slow) fluidized bed having a second grid for introduction of fluidizing gas. The second grid is mounted below the first grid. First and second interconnections are provided between the circulating and bubbling beds. Particles flow from the circulating bed through the first interconnection to the bubbling bed, and vice versa for the second connection. The interconnections are positioned with respect to each other so that the pressure and density conditions within the beds are the sole mechanisms that provide the driving force to control the flow of particles from the circulating bed to the bubbling bed.

Abstract: A multi-stage centrifugal pump has a shorter shaft length compared to conventional multi-stage pump with the same number of impellers on the drive shaft (e.g. about 17-28% shorter length). The shorter length is obtained by utilizing first and second annular slide bearings. Adjacent at least one end (and preferably both) of a rotatable elongated shaft of the pump (which mounts the impellers) within a casing the first slide bearing is mounted to a stationary end structure while the second slide bearing is mounted to the shaft for rotation with it. A plurality of O-rings may be provided to mount the second slide bearing to the shaft. A sleeve with shoulder engaging opposite ends of the second slide bearing may be provided, and the slide bearings may have a clearance of about 0.04-0.1 mm between them, with a lubricant in the clearance. A labyrinth seal is typically provided in the most remote shoulder.

Abstract: A slurry of recycled cellulose fibers is deinked by introducing the slurry into the first end of a vortex, sparging gas radially inwardly into the slurry to cause gas bubbles to attach to contaminants and ink particles to form an aerated slurry, discharging the aerated slurry from near the second end of the vortex into a separation vessel, effecting separation of a foam of ink laden gas bubbles from the cellulose fiber slurry in the separation vessel, and removing from the separation vessel the foam with associated ink and contaminants in a first stream, and de-inked cellulose fiber slurry in a second stream. The separation vessel is typically a foam separating vessel with separation effected by flotation, and by discharging the foam. The slurry is introduced into the flotation vessel below the liquid level in it. The slurry typically has a consistency of about 0.5-2%, and the gas to slurry volume ratio during sparging may be 0.1-1 to 1.0 (e.g. 0.2-0.7 to 1, or 0.3-0.4 to 1).

Abstract: A method and apparatus are provided for operating a pressurized reactor system in order to precisely control the temperature within a pressure vessel in order to minimize condensation of corrosive materials from gases on the surfaces of the pressure vessel or contained circulating fluidized bed reactor, and to prevent the temperature of the components from reaching a detrimentally high level, while at the same time allowing quick heating of the pressure vessel interior volume during start-up. Superatmospheric pressure gas is introduced from the first conduit into the fluidized bed reactor and heat derived reactions such as combustion and gassification are maintained in the reactor. Gas is exhausted from the reactor and pressure vessel through a second conduit.

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: 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: Method of recovering energy from waste liquors from pulp processes, wherein the waste liquor is burned in a waste liquor recovery boiler and energy is recovered from the flue gases by producing saturated or partially superheated steam in the recovery boiler. According to the invention, a portion of the waste liquor is gasified in a gasifying reactor in order to produce combustion gas. The combustion gas is burned in a separate superheating boiler, in which the steam produced in the recovery boiler is superheated.

Abstract: Apparatus for cleaning high temperature, high pressure gases includes a pressure vessel, and a filtration unit within the pressure vessel. The filtration unit is adapted to communicate with a fluidized bed reactor gas outlet, and includes at least one dirty gas chamber housing a plurality of porous, ceramic filter tubes, and at least one clean gas chamber for receiving clean gas from the ceramic filter tubes. The dirty gas chamber includes a particle outlet for removing particles separated from the gas by the filter tubes. The porous ceramic filter tubes are horizontally oriented within the filtration unit or housing and mounted within water cooled walls of the housing. The fluidized bed reactor and associated cyclone separator may be located within the pressure vessel with the filtration unit, or located outside the pressure vessel and in communication with the filtration unit inside the pressure vessel.

Abstract: Either atmospheric or superatmospheric pressure high temperature gases, e.g. from a fluidized bed reactor, are filtered in an upright outer vessel having at least one upright inner vessel within it. The inner vessel has gas-impervious peripheral walls and divides the gas volume in the outer vessel into clean and dirty gas volumes. A number of monolithic ceramic filter elements are mounted in openings disposed in the peripheral walls of the inner vessel and allow clean gas to flow through the filter elements from the dirty gas volume to the clean gas volume. The peripheral wall includes cooling panels formed of cooling tubes, which can lower the temperature of the filter mounting structure significantly. The cooling tubes are normally protected by refractory material from direct contact with the gases so that only the mounting structures are cooled (i.e.

Abstract: The present invention relates to a method of treating various chlorine-containing materials such as wastes, biological sludges and even metal concentrates in a circulating fluidized bed reactor (1) or a grate furnace at a high temperature of over 830.degree. C. and of cooling the resultant process gases for minimizing the amount of polyhalogenated aromatic compounds in the process gases. The process gases are cooled to a temperature below 250.degree. C. at a cooling velocity exceeding 1000.degree. C. per second. Cooling is preferably effected in a circulating fluidized bed reactor (2).

Abstract: Waste gases are purified by adding reagent and/or absorbent which reacts with pollutants in the gases to the gases, and then introducing the gases into a wetting reactor for activating the reagent or absorbent contained in the gases. The gases are introduced into a drying zone of the reactor and then passed upwardly into a wetting zone. The reagent or absorbent which has reacted partly or completely with the pollutants is separated from the gas by a filter in the upper section of the reactor and particles are intermittently detached from the filter and fall downwardly into an ash layer in the bottom of the reactor. The ash layer is capable of homogenizing wet particles and water droplets which fall downwardly from the wetting zone, and typically is at least about 25 cm thick. A mechanical mixer/grinder may be provided in the ash layer for mixing the particles and droplets and grinding lumps in the ash layer into particles.

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: 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.