Abstract: The continuous digester is for producing chemical pulp to a process for operating this digester and to a feedback system for the cooking liquid. By means of implementing cooking zones 1st, 2nd, 3rd, 4th and 5th down through the digester, that have a successively decreasing liquid-to-wood ratio, it is possible to obtain a more uniform alkali profile during the cooking. The alkali is kept high at the beginning by means of a high liquid-to-wood ratio, typically over 6:1, which exceeds conventional liquid-to-wood ratios, which are normally around 3.5-5.0:1.

Abstract: The invention concerns a method for feeding chips into a chip bin or corresponding, the chips in said method being forced to move substantially horizontally as a plug filling the cross-section of the transfer space. The chip plug is formed and maintained at a part of the length of the transfer space with chips forced batchwise to the transfer motion.

Abstract: The invention relates to a feed arrangement for feeding chips to chip bins (1) in the production of cellulose pulp in continuous digesters (16), in which the chip bin is constituted by a treatment vessel having a top and a bottom, in which the chips are fed into the top (13) of the treatment vessel and fed out via the bottom of the treatment vessel using suitable lock members (10, 11). Distribution devices (4a, 4b) for the addition of steam are disposed in the treatment vessel so as to heat the chips to a level above 80° C., preferably around 100° C., when the chips are fed out via the bottom of the treatment vessel. By virtue of the fact that the chips are fed into the treatment vessel via at least one liquid lock (30) and the treatment vessel is otherwise sealed off, the quantity of driven-off gases from the chip bin is reduced to a minimum, at the same time as an effective utilization of available energy is obtained.

Abstract: A system for feeding fibres from a fibre separation step at a first pressure to a drying step at a second, lower pressure, the system comprising a sluice feeder (3) provided between the fibre separation step and the drying step. At least an outlet (14) of the sluice feeder (3) is enclosed by a housing (4) for pressurization by means of a pressure medium in the housing (4) to a pressure that essentially corresponds to the first pressure in the sluice feeder (3). The fed out fibre from the sluice feeder (3) to the housing (4) are removable by means of the pressure medium in the housing (4) via a control valve (20), which regulates the pressure in the housing (4), to the drying step at the second, lower pressure. The pressurization in the housing (4) prevents steam to escape from the sluice feeder (3).

Abstract: A continuous digester is disclosed for producing chemical cellulose pulp from cellulose chips, comprising: a continuous digester vessel having a lower section filled with the cellulose chips and an upper gas filled section; an inverted separator at least partially in said upper section which introduces chips and liquid into said digester vessel and separates some of the liquid from the chips, wherein said separator includes a drive shaft connected to a conveyor, and a liquid discharge port proximate to the drive shaft and arranged proximate to a chip discharge of the separator.

Abstract: A chip bin for a digester has an upper part through which chips fall freely from an inlet and a lower part within which the chips remain until they are fed to a digester. Steam orifices strike falling chips with steam and disperses the chips over the interior of the chip bin. Further steam heats the chips and drives out non-condensable gas. The lower part of the chip bin is conical. Steam jets aimed down the conical walls propel the chips to an outlet at the bottom and prevent bridging.

Abstract: An apparatus for carboxylating wood pulp which utilizes the wood pulp bleach plant and the method of carboxylating the pulp which takes place in the bleach plant.

Abstract: A method and apparatus for treating pulp being fed into a blow tank or a storage tank. A preferred embodiment is that the pulp is discharged from a batch digester (10) and fed either to the upper or lower part of a blow tank (20), depending on the consistency of the pulp being discharged from the digester.

Abstract: 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 a single vane slurry pump in series with a centrifugal slurry pump both of which are 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.

Abstract: Containers for collecting and discharging particulate lignocellulosic material are disclosed, including a cylindrical upper portion, a lower portion tapering towards a bottom elongated space, an exit pipe below the bottom, a pair of parallel screws mounted on parallel shafts in the elongated space in a common horizontal plane for feeding the particulate lignocellulosic material towards the exit pipe, a pair of distributors disposed on the parallel screws above the exit pipe comprising radial discs, and a pump below the exit pipe for transporting the particulate lignocellulosic material to a subsequent step.

Abstract: A continuous digester for producing chemical cellulose pulp from cellulose chips including: a digester vessel with an upper section attached to a top separator and said vessel at least partially filled with the cellulose chips and a liquor; a top separator at least partially in said upper section having a lower chip inlet port, a chip conveyor, a screen adjacent the conveyor, an upper chip discharge chute, and a liquor outlet facing a side of the screen opposite to the conveyor, and a chip inlet conduit extending into the vessel and having a first operational mode in fluid communication with the chip inlet port and a second operational mode in which the chip inlet conduit discharges directly into the vessel.

Abstract: The invention relates to a continuous digester for producing chemical pulp, to a process for operating this digester and to a feedback system for the cooking liquid. By means of implementing cooking zones 1st, 2nd, 3rd, 4th and 5th down through the digester, having a successively decreasing liquid-to-wood ratio, it is possible to obtain a more uniform alkali profile during the cooking. The alkali which is totally available is kept high at the beginning by means of a high liquid-to-wood ratio, typically well over 6:1, which well exceeds conventional liquid-to-wood ratios, which are normally around 3.5-5.0:1. In combination with digester liquid from subsequent cooking zones being fed back to the top of the digester, the alkali concentration can be kept low at the beginning of the cooking, typically within 20-35 g/l when cooking softwood. This is achieved with essentially all the alkali, i.e. more than 80%, being added at the beginning of the cooking.

Abstract: A system for feeding fibres from a fibre separation step at a first pressure to a drying step at a second, lower pressure, the system comprising a sluice feeder (3) provided between the fibre separation step and the drying step. At least an outlet (14) of the sluice feeder (3) is enclosed by a housing (4) for pressurization by means of a pressure medium in the housing (4) to a pressure that essentially corresponds to the first pressure in the sluice feeder (3). The fed out fibre from the sluice feeder (3) to the housing (4) are removable by means of the pressure medium in the housing (4) via a control valve (20), which regulates the pressure in the housing (4), to the drying step at the second, lower pressure. The pressurization in the housing (4) prevents steam to escape from the sluice feeder (3).

Abstract: A method for producing chemical pulp from cellulosic material by means of alkaline cooking, including cooking the material to pulp at cooking temperature in a digester, reducing the temperature at the end of the cook, substantially relieving the overpressure in the digester and then discharging the pulp from the digester by means of pumping. The method is characterized in that the pulp is cooled to essentially 85° C. to 70° C. before pumping cooked material as a fluid suspension from the digester, and that the temperature of the cooked material is maintained in the same temperature range and at a pH level being between 10 and 13, between the digester and a first delignification/bleaching stage, thus avoiding mechanical damage of cellulosic material.

Abstract: An apparatus and process for solvent pulping of cellulose-containing biomass utilizes at least one steaming vessel, a plug screw feeder or compression screw device, at least one super-atmospheric impregnation vessel, a solvent delignification reactor capable of operating at a pressure of 350 psig or more, and a solvent containing line for introducing solvent-containing liquor at the plug screw feeder outlet or compression screw device outlet. The process and system can also include at least one series connected pressure diffuser and optionally a retention tube downstream of each pressure diffuser to provide sufficient retention time to substantially preclude re-deposition of lignin on the cellulose fibers of the biomass, a blow tank connected to the last of the pressure diffusers and retention tubes, and vessels for multistage alcohol washing.

Abstract: The present invention relates to an arrangement in connection with bleaching pulp having a consistency of 7-20%, preferably 8-16%, said arrangement comprising a bleaching tower having at least one inlet opening and at least one outlet opening for pulp, a transfer line comprising a feed line operatively connected to the inlet of the tower and a discharge line operatively connected to the outlet of the tower, and at least one pump arranged in the feed line. The arrangement further comprises at least two propeller or turbine type devices for increasing the pressure of the pulp flowing in the transfer line.

Abstract: A top separator assembly for a digester is disclosed comprising: a rotatable shaft for the top separator; a packing for the shaft; and a sealing ring operatively mounted to the shaft and having a nominal clearance with the pack box, said sealing ring mounted so that up lifting of said shaft provides a substantially fluid tight seal between said pack box and a side of said ring (in the digester) opposite the pack box.

Abstract: A method is disclosed for extracting liquor from a cellulose slurry for a continuous digester comprising the steps of: providing the cellulose slurry of liquor and chips of cellulose fiber material to a separator; extracting a first stream of liquor from the separator; extracting a second stream of liquor from the separator, where the second stream has an effective alkali (EA) concentration greater than the EA concentration of the first steam; outputting the first stream from the separator and outputting the second stream from the separator separately from the second stream, and outputting a condensed slurry from the separator to a digester vessel.

Abstract: A continuous pulp digester having an elongate horizontally aligned pressure vessel through which the wood chips and digesting fluid flow in a forward direction. In a first and second embodiments within the pressure vessel there is an inner container defining an elongate chamber or passageway having a square cross sectional configuration. In a third embodiment the digesting chamber is cylindrical. At locations along the digester, there are several pair of liquid flow inlets and liquid flow outlets which enable filtrate from a pulp washer and a digesting agent to be moved into and across the digesting chamber to flow out the flow outlets. These are recirculated in a net upstream flow pattern toward the outlet end of the digester, and discharged as black liquor at different locations in the digester.

Abstract: The flow of a liquid slurry of comminuted cellulosic fibrous material (e.g. wood chips) in a vertical vessel is made more uniform by providing a plurality of vertically spaced sets of either substantially continuous or discontinuous protrusions which extend inwardly from the internal surface of the vessel a maximum distance of between about 2-12 inches. A preferred vessel is a continuous or batch digester. The protrusions may have an arcuate, rectangular, isosceles or scalene triangular, right triangular, or trapezoidal cross-section, and may be spaced from each other vertically between about 1-12 feet, and have a height of between about 1-3 feet. Discontinuous protrusions have a preferred arcuate spacing of between 1-10 feet.

Abstract: 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 a single vane slurry pump in series with a centrifugal slurry pump both of which are 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.

Abstract: A continuous digester is disclosed for producing chemical cellulose pulp from cellulose chips, comprising: a continuous digester vessel having a lower section filled with the cellulose chips and an upper gas filled section; an inverted separator at least partially in said upper section which introduces chips and liquid into said digester vessel and separates some of the liquid from the chips, wherein said separator includes a drive shaft connected to a conveyor, and a liquid discharge port proximate to the drive shaft and arranged proximate to a chip discharge of the separator.

Abstract: A top separator assembly for a digester is disclosed comprising: a rotatable shaft for the top separator; a packing for the shaft; and a sealing ring operatively mounted to the shaft and having a nominal clearance with the pack box, said sealing ring mounted so that up lifting of said shaft provides a substantially fluid tight seal between said pack box and a side of said ring (in the digester) opposite the pack box.

Abstract: Systems, methods, and vessels for reducing the stagnation and non-uniform flow or treatment of solid materials and slurries in vessels. The non-uniform flow or treatment that may characterize the storage or treatment of solid materials in process industries is minimized or eliminated by the introduction of liquid to the bottom heads of the vessels, in particular, the introduction of liquids in regions in the bottom heads where friction and compression cause stagnation in the flow of material. The liquid may be introduced by means of one or more nozzles, for example, one or more evenly-spaced nozzles, and the flow of liquid to each nozzle may be individually controlled. Though the systems, methods, and vessels disclosed may be used in the processing of cellulose materials, aspects of the present invention may be used in any process or materials handling industry application where solid materials or slurries are handled in vessels.

Abstract: Processes and systems are provided for cooking wood chips containing knots in a digester to produce a chemical pulp. Specifically, a low pressure slurry of comminuted cellulosic fibrous material is formed in a vessel operating at essentially atmospheric pressure by mixing therein a liquid and the comminuted cellulosic fibrous material. The low pressure slurry is thereafter supplied to a low pressure inlet of a high pressure transfer device while liquid is removed from the slurry through a low pressure outlet thereof. A high pressure liquid is supplied to the transfer device (e.g., via a slurry pump) so as to form a high pressure slurry of the comminuted cellulosic material which is then discharged from a high pressure outlet of the transfer device. Knots are removed via a knot separator from a slurry of uncooked knot-containing cellulosic material at essentially atmospheric pressure.

Abstract: Processes and systems are provided for cooking wood chips containing knots in a digester to produce a chemical pulp. Specifically, a low pressure slurry of comminuted cellulosic fibrous material is formed in a vessel operating at essentially atmospheric pressure by mixing therein a liquid and the comminuted cellulosic fibrous material. The low pressure slurry is thereafter supplied to a low pressure inlet of a high pressure transfer device while liquid is removed from the slurry through a low pressure outlet thereof. A high pressure liquid is supplied to the transfer device (e.g., via a slurry pump) so as to form a high pressure slurry of the comminuted cellulosic material which is then discharged from a high pressure outlet of the transfer device. Knots are removed via a knot separator from a slurry of undercooked knot-containing cellulosic material at essentially atmospheric pressure.

Abstract: Chemical pulp is produced from a slurry of comminuted cellulosic fibrous material using a beneficial additive such as AQ, or polysulfide. In the first treatment zone the effective alkali concentration and temperature conditions are such so that substantially no alkali degradation of the cellulose occurs, but so that the material is effectively impregnated with the additive. Then the material is treated with an alkaline cooking liquor, at cooking temperature, to produce a chemical cellulose pulp with higher yield or strength than if the low temperature, low alkali, additive pretreatment was not practiced. Typical alkali and temperature conditions in the first zone are less than 10 g/l expressed as NaOH; and between about 80-130° C., e.g. about 80-110° C. The first zone is preferably a feed system (which may include a separate impregnation vessel) for a continuous digester, while cooking is in a continuous digester.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A top separator assembly for a digester is disclosed comprising: a rotatable shaft for the top separator; a packing for the shaft; and a sealing ring operatively mounted to the shaft and having a nominal clearance with the pack box, said sealing ring mounted so that up lifting of said shaft provides a substantially fluid tight seal between said pack box and a side of said ring (in the digester) opposite the pack box.

Abstract: A pre-treatment device for wood chips for pulping comprises a tube through which the wood chips fall into a digester. Steam is injected into the tube through rings of nozzles, which are angled circumferentially to impart a rotary and turbulent motion to the falling chips. Some nozzles are angled downwardly to encourage the chips to flow freely through the tube, some are horizontal to encourage a longer dwell time near the nozzles. Digesting liquor is also sprayed onto the chips from spray nozzles after the first ring of steam nozzles. The heat and steam expel air and other non-condensable gases and volatiles from the chips, allowing them to absorb the liquor. At the bottom of the tube, the chips are propelled down and outwards by jets of higher-pressure steam, spreading and packing them into the digester.

Abstract: 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.

Abstract: A pre-treatment device for wood chips for pulping comprises a tube through which the wood chips fall into a digester. Steam is injected into the tube through rings of nozzles, which are angled circumferentially to impart a rotary and turbulent motion to the falling chips. Some nozzles are angled downwardly to encourage the chips to flow freely through the tube, some are horizontal to encourage a longer dwell time near the nozzles. Digesting liquor is also sprayed onto the chips from spray nozzles after the first ring of steam nozzles. The heat and steam expel air and other non-condensable gases and volatiles from the chips, allowing them to absorb the liquor. At the bottom of the tube, the chips are propelled down and outwards by jets of higher-pressure steam, spreading and packing them into the digester.

Abstract: Disclosed is a pressure vessel comprising a pressurized chamber; an overflow chute having an inlet open to an upper level of the chamber, a chute passage extending from the upper level to a lower level, and a chute discharge; wherein the chute passage has a bend to defect a flow in the chute passage before the flow exits the discharge.

Abstract: A revolver valve includes a housing with a cylindrical inner chamber, and a pair of end caps respectively attached to each end of the housing. One of the end caps includes an inlet opening and the other end cap includes an outlet opening. A cylindrical rotor body is rotatably disposed within the inner chamber of the housing. The rotor body includes a pair of end faces respectively positioned closely adjacent to the end caps, and a plurality of longitudinally extending cylinders extending between the end faces. Each cylinder is positioned generally concentrically about an axis of rotation of the rotor body, whereby the plurality of cylinders are sequentially disposed in communication with the inlet opening and the outlet opening during rotation of the rotor body within the inner chamber during use. The revolver valve is preferably used in a fiber stock preparation system in conjunction with a fiber loading apparatus having a pressurized vessel.

Abstract: A drainer for a feed system for a cellulose digester has a substantially open and hollow inlet (devoid of a spiral flow imparter or a like flow restriction) and a substantially annular screen within an elongated housing having a flow direction between the housing inlet and outlet. The screen is slotted and the slots are at an angle &agr; between 5-90° with respect to the flow direction, so as to minimize passage of cellulose material through the slots, or clogging of the slots.

Abstract: A pulper in a stock preparation system includes a housing with a fiber inlet, at least one water inlet, at least one outlet and an inner chamber. A plurality of rotatable augers extend into the inner chamber.

Abstract: A feed system for a cellulose pulp treating vessel (such as a continuous digester) is not limited by the required L/W ratio of the pump feeding a wood chip slurry to a high pressure transfer device, the feed system may be kept at a low temperature to minimize flashing of liquid into steam, and a return conduit from the treatment vessel to the transfer device high pressure inlet may be eliminated. Some of the liquid is removed from the slurry just before the low pressure inlet to the transfer device, and/or just after the high pressure outlet, to reduce the L/W ratio of the slurry by at least 0.25, e.g. from 3.0:1 to 2.25:1 just before the low pressure inlet, and from, 7.0:1 to 5.0:1 substantially immediately after the high pressure outlet.

Abstract: A feed system for a cellulose pulp treating vessel (such as a continuous digester) is not limited by the required L/W ratio of the pump feeding a wood chip slurry to a high pressure transfer device, the feed system may be kept at a low temperature to minimize flashing of liquid into steam, and a return conduit from the treatment vessel to the transfer device high pressure inlet may be eliminated. Some of the liquid is removed from the slurry just before the low pressure inlet to the transfer device, and/or just after the high pressure outlet, to reduce the L/W ratio of the slurry by at least 0.25, e.g. from 3.0:1 to 2.25:1 just before the low pressure inlet, and from 7.0:1 to 5.0:1 substantially immediately after the high pressure outlet.

Abstract: 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.

Abstract: A pipe attachment comprises a pipe elbow that is tightly attached to a stand pipe so that the diameter of the stand pipe is greater than the diameter of the pipe elbow.

Abstract: A top separator assembly for a digester is disclosed comprising: a rotatable shaft for the top separator; a packing for the shaft; and a sealing ring operatively mounted to the shaft and having a nominal clearance with the pack box, said sealing ring mounted so that up lifting of said shaft provides a substantially fluid tight seal between said pack box and a side of said ring (in the digester) opposite the pack box.

Abstract: The flow of a liquid slurry of comminuted cellulosic fibrous material (e.g. wood chips) in a vertical vessel is made more uniform by providing a plurality of vertically spaced sets of either substantially continuous or discontinuous protrusions which extend inwardly from the internal surface of the vessel a maximum distance of between about 2-12 inches. A preferred vessel is a continuous or batch digester. The protrusions may have an arcuate, rectangular, isosceles or scalene triangular, right triangular, or trapezoidal cross-section, and may be spaced from each other vertically between about 1-12 feet, and have a height of between about 1-3 feet. Discontinuous protrusions have a preferred arcuate spacing of between 1-10 feet.

Abstract: 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.

Abstract: 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.

Abstract: The flow of a liquid slurry of comminuted cellulosic fibrous material (e.g. wood chips) in a vertical vessel is made more uniform by providing a plurality of vertically spaced sets of either substantially continuous or discontinuous protrusions which extend inwardly from the internal surface of the vessel a maximum distance of between about 2-12 inches. A preferred vessel is a continuous or batch digester. The protrusions may have an arcuate, rectangular, isosceles or scalene triangular, right triangular, or trapezoidal cross-section, and may be spaced from each other vertically between about 1-12 feet, and have a height of between about 1-3 feet. Discontinuous protrusions have a preferred arcuate spacing of between 1-10 feet.