Patents Assigned to Ahlstrom
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Publication number: 20020017370Abstract: The strength properties of chemical cellulose pulp (particularly kraft pulp) are improved by substituting a cold impregnation soak for conventional impregnation procedures. After steaming, wood chips are soaked in an alkaline liquid at a temperature of about 80-110° C. (preferably 80-100° C., or 90-105° C.) for between one-half-72 hours (typically about 2-4 hours) at a pressure of about 0-15 bar (preferably about 1-5 bar), to dissolve at least about 8% of the wood (preferably about 10-20%) and at least about 15% of the lignin. The alkaline liquid used preferably contains sulfide (e.g. black liquor, green liquor, white liquor, or mixtures thereof), but almost any alkaline liquid having an alkali concentration of about 1.0 mole of NaOH/liter or less (typically about 0.75 m/l or less) is suitable. The wood chips are then raised to a cooking temperature of about 145-180° C. and cooked to produce the cellulose chemical pulp.Type: ApplicationFiled: October 15, 2001Publication date: February 14, 2002Applicant: Andritz-Ahlstrom Inc.Inventors: Kaj O. Henricson, Aki Hannu Vilpponen, Hannu Olavi Ramark, Auvo Kimmo Kettunen, C. Bertil Stromberg
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Patent number: 6346167Abstract: 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.Type: GrantFiled: January 19, 2001Date of Patent: February 12, 2002Assignee: Andritz-Ahlstrom Inc.Inventors: Bruno S. Marcoccia, J. Robert Prough, Richard O. Laakso, Joseph R. Phillips, Rolf C. Ryham, Jan T. Richardsen, R. Fred Chasse
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Patent number: 6346166Abstract: By the utilization of a jet ejector (such as a thermocompresser) in a cellulose chemical pulp mill, it is possible to effectively increase the utilization of steam. The volume of steam from a flash tank which flashes black liquor from a pulp digester may be increased (e.g. at least about 10%), while the volume and temperature of the liquor discharged from the flash tank are decreased and its concentration increased, by operatively connecting the jet ejector to the steam discharge from a flash tank. The jet ejector is supplied with higher pressure steam from another source which can result in a low pressure or partial vacuum condition in the flash tank. The flash tank may be a single flash tank or one of a series of flash tanks, and an ejector can be associated with at least another flash tank in the series.Type: GrantFiled: June 6, 2000Date of Patent: February 12, 2002Assignee: Andritz-Ahlstrom Inc.Inventors: Auvo K. Kettunen, Matti Lautala
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Patent number: 6344112Abstract: A screen used in the production of cellulose pulp may be mounted in a digester to minimize traditional screen problems (including clogging) without introducing new problems. The screen comprises a screen plate having a plurality of slots formed in it with an inclination angle, which is 30-60° with respect to the bottom edge of the screen plate. The screen plate may comprise a plurality of parallel screen bars side-by-side, or an integral metal plate with slots formed in it. The slots have a width between 1-5 (e.g. 2-4) millimeters and a spacing between them of 3-9 millimeters.Type: GrantFiled: October 20, 1999Date of Patent: February 5, 2002Assignee: Andritz-Ahlstrom Inc.Inventor: Lasse Hernesniemi
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Patent number: 6340805Abstract: The present invention relates to a method of manufacturing a wire screen product which is especially suitable for screening fiber suspensions of the wood processing industry. It is a characteristic feature of the method according to the invention of manufacturing a wire screen product including screen wires disposed crosswire in relation to a support arranagement that includes at least one support wire, the screen wires and support wire being secured to each other such that, at the first stage, the screen wire is welded by a button spot weld to the support arrangement and, at the second stage, the screen wire is welded at another point to the same support structure.Type: GrantFiled: May 28, 1998Date of Patent: January 22, 2002Assignee: Andritz-Ahlstrom OyInventor: Risto Ljokkoi
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Patent number: 6336573Abstract: A bin or hopper, preferably with one-dimensional convergence, has a slot outlet at its bottom for discharging bulk solid particulate material (such as coal, wood chips, sugar, plastic pellets, etc.) to a screw in a trough. The screw has varying flight diameter, shaft diameter, and average pitch along its length to a discharge so as to provide substantially uniform material flow velocity distribution along the slot outlet. One or more flow rate adjusters may regulate flow of material being transported by the screw. Each flow adjuster may be a vertical plate with a substantially straight-across bottom curved about a substantially horizontal axis, or with a bottom two-dimensional curvature.Type: GrantFiled: November 8, 2000Date of Patent: January 8, 2002Assignee: Andritz-Ahlstrom Inc.Inventor: Jerry R. Johanson
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Patent number: 6336993Abstract: A system and method for feeding a slurry of comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester also treat the material to remove metals before digestion. During pumping of the slurry with at least first and second series connected pumps, at or upstream of at least one of the pumps chemicals (acids and/or chelating agents) which dissolve the metals in the material are added, and preferably some of the liquid is removed so as to purge at least about 10% (e.g. about 20-80%) of the metals in the material. The metal removal preferably takes place substantially immediately before alkaline digestion.Type: GrantFiled: May 11, 2000Date of Patent: January 8, 2002Assignee: Andritz-Ahlstrom Inc.Inventor: C. Bertil Stromberg
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Patent number: 6332542Abstract: Dense, tramp material, is efficiently separated in a comminuted cellulosic fibrous material feed system, for example in a chemical cellulose digester feed system, in a simple but effective matter. By merely utilizing a generally vertical conduit and a slurry flow within it (which may be augmented by high speed liquid introduction), that is caused to turn in a radiused path, centrifugal force allows separation of the tramp material into a cavity beneath the radius transition without requiring any mechanical element to engage the slurry. Appropriate purges, baffles, and discharge mechanisms may be provided. Alternatively, a tramp material separator may be built into an otherwise conventional metering screw in a digester feed system, or one or more centrifugal separators can be provided downstream of the slurry pump in a chip slurry transport system or digester feed system.Type: GrantFiled: May 17, 2001Date of Patent: December 25, 2001Assignee: Andritz-Ahlstrom Inc.Inventors: Vic L. Bilodeau, R. Fred Chasse, James R. Prough, C. Bertil Stromberg, Craig A. Walley
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Publication number: 20010050130Abstract: A printed circuit board is made from at least one non-woven sheet or web layer comprising at least 50% by weight acrylic fibers, with any balance substantially electrically non-conductive fibers, filler, and binder. The sheet or web is preferably made by the foam process, and may contain 60-80% straight polyacrylonitrile fibers and 40-20% fibrillated (pulp) ones. The web or sheet is preferably compressed by thermal calendering so that it has a density of about 0.1-1 grams per cubic centimeter; and the web or sheet may have a basis weight of between about 20-120 grams per square meter. The web or sheet may also have a 1-40% of substantially electrically non-conductive organic or inorganic binder, or may be substantially binder free.Type: ApplicationFiled: January 8, 2001Publication date: December 13, 2001Applicant: Ahlstrom Glassfibre Oy.Inventors: Kay Rokman, Rod Komlenic, Kelly Rennels, Hakan Sabel
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Publication number: 20010047853Abstract: In a cellulose pulp handling vessel having a first diameter material storing or treating portion above a second diameter discharge which is at least 20% less than the first diameter, reduced compression of the material and reduced power requirements of an agitator (if used), compared to prior art constructions are provided. A first transition, preferably a substantially smooth interior surface substantially frusto-conical transition, is provided between the first and second diameters. A second single-convergent transition may be provided above the first transition. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. If desired, the transition may be moved, such as with a vibrator or oscillator. The invention is particularly suitable for pulp digesters and impregnation vessels.Type: ApplicationFiled: July 9, 2001Publication date: December 6, 2001Applicant: Andritz-Ahlstrom Inc.Inventors: J. Robert Prough, Jerry R. Johanson
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Publication number: 20010047854Abstract: In a cellulose pulp handling vessel having a first diameter material storing or treating portion above a second diameter discharge which is at least 20% less than the first diameter, reduced compression of the material and reduced power requirements of an agitator (if used), compared to prior art constructions are provided. A first transition, preferably a substantially smooth interior surface substantially frusto-conical transition, is provided between the first and second diameters. A second single-convergent transition may be provided above the first transition. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. If desired, the transition may be moved, such as with a vibrator or oscillator. The invention is particularly suitable for pulp digesters and impregnation vessels.Type: ApplicationFiled: July 9, 2001Publication date: December 6, 2001Applicant: Andritz-Ahlstrom Inc.Inventors: J. Robert Prough, Jerry R. Johanson
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Patent number: 6325888Abstract: Chemical cellulose pulp is made from sawdust utilizing a static down-flow retention vessel. By adding steam and cooking liquor to a flow of sawdust a heated slurry, at a cooking temperature of about 250-350° F., is produced. The heated slurry is, at superatmospheric pressure, moved downwardly in the static down-flow retention vessel while cooking temperature is maintained, for a time period of about 0.5-6 (preferably 1 to 3) hours, the slurry having a consistency of about 5-30%. At superatmospheric pressure, without significant reduction in pressure from the retention vessel, the slurry is cooled to well below cooking temperature by diffusing cooling liquid through it, as in a conventional pressure diffuser. The discharge from the retention vessel is preferably substantially solely gravity action (e.g. using a discharge with single convergence and side relief).Type: GrantFiled: August 31, 1995Date of Patent: December 4, 2001Assignee: Andritz-Ahlstrom Inc.Inventors: Jay J. Miele, Marco Marois, R. Fred Chasse, J. Wayne Chamblee, John D. Weston, J. Robert Prough
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Patent number: 6325890Abstract: A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using one or more slurry pumps located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge. A return line from the top of the digester may, but need not necessarily, be operatively connected to the one or more pumps and if connected to the pumps, the liquid in the return line may be cooled to a temperature at which it will not flash during handling. Recirculation loops may be established associated with one or all of the slurry pumps to facilitate startup.Type: GrantFiled: May 11, 2000Date of Patent: December 4, 2001Assignee: Andritz-Ahlstrom Inc.Inventors: J. Robert Prough, C. Bertil Stromberg, Tim S. Pease
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Patent number: 6315128Abstract: Dense, tramp material, is efficiently separated in a comminuted cellulosic fibrous material feed system, for example in a chemical cellulose digester feed system, in a simple but effective matter. By merely utilizing a generally vertical conduit and a slurry flow within it (which may be augmented by high speed liquid introduction), that is caused to turn in a radiused path, centrifugal force allows separation of the tramp material into a cavity beneath the radius transition without requiring any mechanical element to engage the slurry. Appropriate purges, baffles, and discharge mechanisms may be provided. Alternatively, a tramp material separator may be built into an otherwise conventional metering screw in a digester feed system, or one or more centrifugal separators can be provided downstream of the slurry pump in a chip slurry transport system or digester feed system.Type: GrantFiled: November 12, 1999Date of Patent: November 13, 2001Assignee: Andritz-Ahlstrom Inc.Inventor: C. Bertil Stromberg
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Publication number: 20010036613Abstract: The present invention relates to a cooler (2) for a rotary drum kiln (1). The cooler comprises two cylindrical housings disposed one inside the other (6, 7), surrounding the kiln and rotating with it, which housings are mounted at the discharge end of the kiln concentrically with the kiln and between which housings an annular space (8) is formed. The housings are attached to each other by means of longitudinal radial partition walls (16), and the inner cylindrical housing (6) is attached at its ends to the kiln. The annular space (8) has a feeding inlet (11) communicating with the kiln for leading the hot material from the kiln into the cooler and a discharge outlet for discharging the cooled material. The material to be cooled flows counter-currently in relation to the cooling gas flow.Type: ApplicationFiled: March 30, 2001Publication date: November 1, 2001Applicant: ANDRITZ-AHLSTROM OYInventor: Arto Ahvenainen
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Patent number: 6306252Abstract: Steam (preferably clean steam) having less noncondensible gases than steam produced by conventional black liquor flashing is produced from hot black liquor from a digester of a pulp mill. A heat exchanger is utilized and the hot black liquor is passed through the heat exchanger in heat exchange contact with an evaporable liquid, preferably clean water. After the water is heated in the heat exchanger it is flashed in at least one flash tank where the heat exchanger is a liquid-to-liquid heat exchanger. The heat exchanger may alternatively include an evaporator (such as a falling film evaporator) in which case the black liquor is passed through an inductor before it enters the evaporator. Alternatively, the heat exchanger may be one or more boilers, such as kettle boilers, in which case the black liquor preferably passes through a cooler after the boilers. Heat energy and turpentine recovery are also maximized.Type: GrantFiled: April 10, 1995Date of Patent: October 23, 2001Assignee: Andritz-Ahlstrom Inc.Inventor: Rolf C. Ryham
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Patent number: 6306253Abstract: In the treatment of cellulose pulp in connection with bleaching, the pulp is first cooked and, if necessary, oxygen delignified in order to reduce the Kappa number below 24, preferably below 14, and after that the pulp is treated in an acid stage at a pH of 2-5 and at a temperature range of 75-130° C. in order to reduce the Kappa number by 2-9 units. To prevent essential weakening of the strength properties of the pulp in the acid stage treatment tower, the retention time, t min, is 30 to 300 minutes and the treatment temperature, T° C. is Tmin<T<Tmax, in which T min = 10517 24 + ln ⁡ ( 2 ⁢ t ) - 273 and Tmax=Tmin+23° C.Type: GrantFiled: April 14, 1998Date of Patent: October 23, 2001Assignee: Andritz-Ahlstrom OyInventor: Kaj O. Henricson
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Publication number: 20010025694Abstract: In the feeding of a slurry of comminuted cellulosic fibrous material to a digester (continuous or batch) in the production of chemical pulp, one of the tanks used in the feed system (which preferably includes a high pressure feeder) may be eliminated without consequent loss of its function by providing a single tank with the combined functions of controlling the level of liquid in a slurrying conduit which supplies slurry to a slurry pump, and storing and substantially continuously supplying liquid to a make-up liquid pump connected to the digester. The single tank preferably surrounds the slurrying conduit and is substantially concentric, and in liquid communication, with it. A gap of 3-48 inches may be provided between the bottom of the conduit and a connection to the slurry pump. A screen or strainer may be provided in the gap, which is substantially surrounded by the tank.Type: ApplicationFiled: June 4, 2001Publication date: October 4, 2001Applicant: Andritz-Ahlstrom Inc.Inventors: Auvo K. Kettunen, Richard O. Laakso, C. Bertil Stromberg, J. Robert Prough, Jay J. Miele
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Publication number: 20010023748Abstract: In the production of chemical pulp, such as kraft pulp, it is possible to reduce the amount of ancillary equipment, and/or the size of the continuous digester vessel, while achieving enhanced uniformity of treatment by avoiding “hang ups”. Instead of providing vertical counter-current flow of liquid and comminuted cellulosic fibrous material being treated in the lower half of the digester, the counter-current flow may be a cross flow, that is substantially horizontal (e.g. radial) while the flow of the chip column is vertical. Regardless of the configuration of the digester vessel, a single pump may be utilized for all of the recirculations, or only a few pumps for all of the recirculations.Type: ApplicationFiled: May 31, 2001Publication date: September 27, 2001Applicant: Andritz-Ahlstrom Inc.Inventors: Bruno S. Marcoccia, C. Bertil Stromberg, Brian F. Greenwood
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Publication number: 20010022283Abstract: Dense, tramp material, is efficiently separated in a comminuted cellulosic fibrous material feed system, for example in a chemical cellulose digester feed system, in a simple but effective matter. By merely utilizing a generally vertical conduit and a slurry flow within it (which may be augmented by high speed liquid introduction), that is caused to turn in a radiused path, centrifugal force allows separation of the tramp material into a cavity beneath the radius transition without requiring any mechanical element to engage the slurry. Appropriate purges, baffles, and discharge mechanisms may be provided. Alternatively, a tramp material separator may be built into an otherwise conventional metering screw in a digester feed system, or one or more centrifugal separators can be provided downstream of the slurry pump in a chip slurry transport system or digester feed system.Type: ApplicationFiled: May 17, 2001Publication date: September 20, 2001Applicant: Andritz-Ahlstrom Inc.Inventors: Vic L. Bilodeau, R. Fred Chasse, James R. Prough, C. Bertil Stromberg, Craig A. Walley