Abstract: The subject matter of the present invention is a device for purifying lightly laden water containing particles and/or fatty matter and/or microorganisms in suspension. The device of the invention is a filter comprising a grid (1) on which is placed a filter element (3) consisting of at least one sheet based on fibers and filled with organic and/or inorganic powders. The invention finds its application in all the industries which consume water and especially the crude oil processing industries and the chemical, papermaking and agri-foodstuffs industries.

Abstract: The intensity of explosions as a result of hot (750-820 degrees C.) smelt from a pulp mill recovery boiler impacting cool (70-100 degrees C.) liquid in a dissolving tank is minimized by more effectively disrupting the flow of smelt from a spout free end tip into the tank. First and second nozzles which issue jets of disrupting fluid (such as steam or green liquor) are positioned on opposite sides of the center line of the spout, and are positioned and spaced from the spout tip and each other so that the jet emanating from at least one of the nozzles always intersects the flow of smelt from the spout even though the smelt flow path varies during normal operation of the recovery boiler.

Abstract: A chip feeding system for a continuous digester provides for a greater rate of delivery of chip slurry to the digester, and is much less expensive than conventional chip feeding systems, typically being only 40-50% of the height of the conventional system. An atmospheric vessel may be connected at the bottom thereof to a slurry pump which pumps the chip slurry to a conventional high pressure feeder. A recirculation loop for returning liquid from the feeder to the vessel may include an atmospheric level tank, and a liquid cooler. The vessel may have one dimensional convergence and side relief, and instead of a conventional cylindrical chip bin, the chip bin may have a hopper having two transitions with one dimensional convergence and side relief. The chip bin also may be at atmospheric pressure so that no low pressure feeder between the bin and vessel is necessary.

Abstract: The present invention relates to a filled paper for gas filtration, with a high adsorption and absorption capacity. This paper, consisting of cellulose fibers, is filled with organic and/or inorganic powders adapted in quantity and in quality to the gas to be treated.It finds its application in the petroleum, chemical, agri-foodstuffs and papermaking industries, in apartment buildings and in office and hospital buildings.

Abstract: A pressure screen comprises an outer housing with a pulp inlet, and accepts and rejects outlets and an advantageous mount of a stationary screen drum (screen cylinder) in the housing. The screen drum is secured at an upper end flange with bolts to an intermediate ring and supported via the intermediate ring by the housing. A rotating rotor is disposed inside the screen drum. The bottom end of the screen drum is provided with at least one groove with at least one primarily flexible material ring disposed in the groove. Cooperating substantially conical surfaces are provided in the bottom of the screen drum and a bottom intermediate ring, in which the groove is formed.

Abstract: A method of treating wood chips allows chemical pulp (e. g. kraft pulp) to be produced having enhanced fiber strength properties. In a first zone or stage the chips are cool impregnated (e. g. a temperature of about 60-120.degree. C.) with a first alkali-containing liquid (25-35 g/l expressed as NaOH). In the top of a continuous digester in a second zone or stage the chips are then treated with a second alkali-containing liquid having an alkali concentration at least 5 g/l less than the first liquid (e. g. 10-20 g/l) and a temperature of between about 120-160.degree. C. (e. g. 130-150.degree. C.). An extraction typically takes place to effect the change in treatment zones. After the second zone the chips are cooked at about 140-180.degree. C. (e. g. 150-170.degree. C.), and higher than in the second zone.

Abstract: In a foam laid process for producing a non-woven web of fibrous material (such as of synthetic or cellulose fibers) substantially fiber free foam is introduced at various locations in or adjacent to a headbox to get improved results. By introducing pure foam into the foam-fiber mixture near (e.g. just before) where the foam-fiber mixture is introduced into the headbox a more uniform basis weight profile of the non-woven web produced may be provided (e.g. a basis weight variation of about 0.5% or less). By introducing another stream of substantially fiber free foam into the headbox at a surface remote from the foraminous element, to flow along the surface (typically parallel to the flow of the foam fiber mixture), it is possible to minimize shear of fibers in the headbox so that the fibers do not become unidirectional, in the direction of movement of the foraminous element, and keep the surface clean. The surface is typically a roof surface of an inclined headbox.

Abstract: A method and apparatus thickens lime mud with a disc filter in such a way that the precoat layer on the filter surfaces of the disc filter can be cleaned. Beneath the scrapers for scraping a dry layer of lime sludge from the precoat layers on the disc filter wires surfaces one or more high pressure nozzles, and optionally a low pressure nozzle, are provided for directing jets of liquid at the precoat layer and wire surface. One high pressure nozzle may remove the precoat layer while another cleans the wire surface, and the nozzles may be reciprocated (with respect to the shaft for rotating the disc filters in a trough). The high pressure jets provide liquid at a pressure of about 30-100 bar, while the low pressure jet pressure is between 2-30 bar and may be utilized continuously, or arrested when the high pressure jets are operable.

Abstract: A method and apparatus to clean a filter drum used for thickening lime mud. The drum is rotated about a horizontal axis in a first direction so that the circumferential surface of the drum moves into contact with lime mud in a vat and a precoat layer formed on the drum, as well as an external layer of lime mud which forms a thickened lime mud cake when a vacuum is applied to the drum withdrawing liquid from the lime mud. The thickened external layer of lime mud cake is scraped from the drum at a second side of the vat, and at a first opposite side of the vat a first jet of liquid is directed onto the drum surface (e.g. at a pressure of about 30-100 bar) to remove a strip of the precoat layer, a third jet of liquid cleans the drum after removal of the precoat layer, and a second jet of liquid is directed onto the drum with sufficient intensity (e.g. a pressure of about 2-20 bar) to remove, by spreading and partially detaching, a strip from the thickened lime mud cake.

Abstract: Rejects from a conventional first set of cleaners from a system feeding recycled cellulosic fiber slurry to a paper machine or rejects from the paper machine approach system cleaners are fractionated to produce a first, fine fraction, stream and a second, coarse fraction, stream containing most of the fiber and larger solids. The second stream is acted upon by a disperser, deflaker, or like mechanical agitating device, to disrupt the fiber flocs and reduce the size of solids to produce a third stream containing few or no fiber flocs and no large particles. The third stream may be diluted and cleaned in a second set of cleaners, and then is returned to the first set of cleaners (e.g. to the inlet of the first stage or between the first and second stages). Ink, and other fine undesirable particles may be removed from the first stream via flotation or cleaning, and the cleaned stream may also be returned to the first set of cleaners if desired.

Abstract: A cellulose pulp continuous digester (e.g. for producing kraft pulp) is operated so that it has the advantages of a hydraulic digester yet has a gas-filled zone over the liquid level. A slurry of chips and cooking liquor is introduced into the top of the digester vessel through an inverted top separator. A liquid level is established below the inverted top separator, and a chips level is established below the inverted top separator (above or below the liquid level). A gas-filled zone above the liquid level includes compressed gas, and is at a temperature of less than 160 (preferably less than 120).degree.C. and at a pressure of between 50-200 (preferably 80-150) psig. The chips are heated by recirculating and heating liquid using a recirculation loop below the chips level, and a countercurrent flow zone is preferably provided.

Abstract: The present invention relates to a method of improving the operation of a boiler plant in a chemical pulp mill. At least part of the black liquor flow of the chemical pulp mill is divided into several batches being substantially in a solid form, which are mechanically turned into substantially equal-sized pieces for deeding into the recovery boiler and for combustion taking place therein. Waste liquor batches may be stored prior to the combustion. The invention also relates to a system for carrying out the method.

Abstract: Pumping of medium consistency cellulose pulp is effected from stand pipes or like small sized pulp vessels to which pulp is normally discharged from storage towers, treatment towers, washers, filters, presses, thickeners, or the like, particularly pumping of high temperature pulps from said stand pipes. A pump inlet is attached to a discharge opening of a stand pipe, pressurizing cellulose pulp in said stand pipe by closing the stand pipe off from the atmosphere, maintaining a superatmospheric pressure in the stand pipe, allowing the cellulose pulp to flow into the pump through the pump inlet, and pumping the cellulose pulp further using the pump.

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

Abstract: 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: A mold release liner for a heated pressure mold for making products such as printed circuit boards is made utilizing two or more wet-laid fiber layers of cellulose or cellulose derivative fibers (such as wood, cotton, cellulose acetate, or rayon fibers, or mixtures of these). The first layer has a sufficiently low density so that it acts as a cushion and absorbs deformation when used as a release liner in the mold (typically it has a thickness of between 8-250 mils, most desirably 40-90 mils, and a basis weight of about 25-350 pounds per ream, most desirably 130-160 pounds per ream). A second layer is of much higher density than the first layer and readily releases from the molds, for example comprising condenser tissue or a similar product, having a thickness of between 0.5-10 mils and a basis weight of 4-50 pounds per ream of 500 sheets. The first and second layers are in face-to-face engagement with each other, and may be adhesively laminated together with sheet, spray, liquid, or powder adhesive.

Abstract: A centrifugal and vacuum pump combination in which the impeller of a centrifugal pump is disposed on the same shaft as a rotor of the vacuum pump, with a gas outlet extending between the centrifugal and vacuum pumps, is operated by positively controlling the flow of gas passing through the gas outlet duct, for example by changing the effective cross-sectional flow area of the outlet duct. The fluent material handled by the pump is preferably a cellulose fiber slurry having a solids consistency of between about 6-15%. The control can be effected automatically in response to solids consistency, inlet pressure, and/or gas content of the slurry being pump. The vacuum pump housing includes an eccentric inner wall, and operation of the pump may be primarily controlled by moving the vacuum pump housing.

Abstract: A falling film evaporator includes a shell with a number of heat transfer elements within the shell. Each heat transfer element has two opposed essentially rectangular plates joined together along upright sides and along seams substantially parallel to the upright sides. The seams form with each other, and the upright sides, a number of vertical flow channels through which steam (heating fluid) flows in the interior of the heat transfer elements to evaporate evaporable liquid flowing downwardly in a film over the outer surfaces of the heat transfer plates.

Abstract: Volatile compounds, such as methanol, are separated from secondary condensates formed in multi-effect evaporation of waste liquor, such as black liquor, from cellulose pulp processes. The condensable secondary vapor is condensed into first and second condensate flows, the first of which, smaller in volume, contains the majority of the volatile compounds condensed in the evaporating effect. The first condensate flows from one or more first evaporation effects, and/or condensers of the evaporation plant, are directed for cleaning into a first steam stripping column. At least some of the second flows are directed to a second steam stripping column to be recovered as very clean condensate, cleaner than the condensate flow from the first stripping column and typically have a methanol concentration of less than 25 ppm, preferably about 10 ppm or less.

Abstract: A method and apparatus for fibrous suspensions in the wood processing industry and more specifically to a so-called drum cylinder, the basic construction of which comprises a vessel, into which suspension being thickened is supplied and a wire-surface cylinder rotating in the vessel. The drum filter is characterized in that the closure member of the drum filter has a channel for leading gas from the filtrate tubes through the compartments of the distribution chamber to the outside of the closing member. The method is characterized in that the operation phase of the filter cylinder is divided into five separate stages. In the first stage, when the cylinder descends on to the vessel, air and the initial filtrate are discharged from the filtrate components and the formation of the pulp web on the wire surface begins. In the second stage, filtrate is discharged with vacuum and the formation of the pulp web continues.