Abstract: In the continuous cooking of comminuted cellulosic fibrous material (e.g. wood chips) to produce paper pulp, the material is subjected to a minimum of mechanical action, especially under high temperature and pressure conditions, so as to increase the quality of the pulp. Also, even for large digesters the uniformity of treatment is enhanced, and scaling may be reduced while energy efficiency is increased. Material is fed without significant steaming to a feeder screw within a perforated cylinder mounted at the bottom of an impregnation vessel. The material flows upwardly in the impregnation vessel, with screens adjacent the top of the vessel thickening the slurry before it is discharged into the top of a continuous digester. The discharge from the impregnation vessel to the continuous digester is made with a minimum of mechanical action on the pulp. The impregnation vessel may be disposed within, and concentric with, the digester, or it may located exteriorly of the digester and supply more than one digester.

Abstract: In the continuous cooking of comminuted cellulosic fibrous material (e.g. wood chips) to produce paper pulp, the material passes upwardly in an impregnation vessel which is within and concentric with a continuous digester and open at the top to digester pressure. At the top of the impregnation vessel, a solids/liquid separator (a screw within a screen cylinder) is provided. Separated liquid is returned in a conduit adjacent the exterior of the impregnation vessel, and open at the top to digester pressure, and passes out the bottom of the digester. The impregnation vessel is welded to the bottom of the digester, and the bottom of the digester is generally hemi-spherical, and substantially devoid of packings.

Abstract: In a continuous digester for paper pulp (comminuted cellulosic material), abrupt variations in high pressure steam flow are minimized. First and second vertically spaced annular screens are provided in a vertical vessel. Each has an annular header associated with it and first and second circumferentially spaced liquid outlets associated with each header. The first outlet for the first screen is generally vertically in line with the first outlet for the second screen, and the second outlet of the first screen is generally vertically in line with the second outlet of the second screen. Simultaneous withdrawal of liquid from the first outlet of the first screen and the second outlet of the second screen takes place, and then is terminated, and then simultaneous withdrawal of liquid from the second outlet of the first screen and the first outlet of the second screen takes place, and then is terminated. This withdrawal sequence is repeated continously.

Abstract: A method and apparatus provide for the continuous digestion of comminuted cellulosic fibrous material (e.g. wood chips) to produce paper pulp, with increased sulfidity. When black liquor is withdrawn from the continuous digester, instead of merely passing it to a pair of flash tanks and then to recovery, the concentrated liquor from a first flash tank is fed to a vessel in which the comminuted material is slurried with a liquid. Since the black liquor remains in intimate contact with the chips for a significant period of time, the lignin in the chips is partly sulfonized. Ultimately the black liquor is replaced with white liquor or the like, and the separated out black liquor is circulated to recovery or disposal. A high pressure feeder and a solids/liquid separator are utilized.

Abstract: A pumping system is capable of handling a paper pulp suspension of medium consistency (e.g. about 8-15% solids consistency) utilizing a conventional centrifugal pump. A conventional pump system capable of handling 3-8% consistency pulp may be retrofit to handle 8-15% consistency pulp. A tube with vanes, and having an open end, extends through the inlet to the pump so that there is a small clearance between the vanes and the inlet, and so that the open end is adjacent but spaced from the hub of the pump impeller. A gas passage extends from the hollow interior of the tube to an area remote from the pump. The tube is rotated in a direction of rotation opposite to the direction of rotation of the pump impeller, and at a speed sufficient to fluidize pulp of about 8-15% consistency, and to force the pulp toward the pump. Gas which collects at the pump impeller is withdrawn through the tube and a gas passage in a shaft connected to the tube, and for that purpose a vacuum pump may be utilized.

Abstract: The screens of a pulp treating vessel, such as a paper pulp thickener, or diffuser, are back flushed in a simple yet effective manner. The screens are mounted to a supporting conduit within a vertical vessel, and a cylinder is connected at one open end to the conduit, and the other open end is disposed within the pulp inside the vessel. A piston is mounted within the cylinder and relative movement between the piston and cylinder is effected periodically in order to force liquid from within the cylinder into the conduit and out the screens, backflushing the screens and preventing clogging. Since no additional volume of liquid is added to the vessel during backflushing, no surge occurs in the vessel. Conventional accumulators, on/off valves, and the like can be eliminated while--in the case of diffusion washing--efficiency can be increased as much as 20-30% and capacity increased as much as about 15%.

Abstract: A pressure diffuser for paper pulp includes a vertical pressurizable liquid-tight vessel having a pulp inlet at the bottom and a pulp outlet at the top. One or more ring shaped screen elements providing first and second concentric screen surfaces, are vertically mounted within the vessel. A number of radially extending header arms mount the screen elements for movement in the vessel and in fluid communication with it. A first linear actuator effects reciprocation of the arms. A cylinder, open at both ends, is affixed to the arms and extends both above and below them, and a piston is disposed within the cylinder, below the arms. A second linear actuator is operatively connected to the piston to effect reciprocation of the piston in the cylinder. A guiding conduit surrounds the open end of the cylinder above the arms and guides reciprocation of the cylinder and transports liquid from the arms to an effluent outlet.

Abstract: The screens of a pulp treating vessel, such as a paper pulp thickener, or diffuser, are back flushed in a simple yet effective manner. The screens are mounted to a supporting conduit within a vertical vessel, and a cylinder is connected at one open end to the conduit, and the other open end is disposed within the pulp inside the vessel. A piston is mounted within the cylinder and relative movement between the piston and cylinder is effected periodically in order to force liquid from within the cylinder into the conduit and out the screens, backflushing the screens and preventing clogging. Since no additional volume of liquid is added to the vessel during backflushing, no surge occurs in the vessel. Conventional accumulators, on/off valves, and the like can be eliminated while--in the case of diffusion washing--efficiency can be increased as much as 20-30%, and capacity increased as much as about 15%.

Abstract: A method and apparatus for continuously treating cellulosic chips to prevent degredation of the chips as a result of mechanical action exerted on the chips by a scraper. A false bottom is provided in a vessel with the scraper mounted for rotation about a vertical axis just above the false bottom, a large central opening being provided in the false bottom. The scraper removes chips from the vessel through the false bottom opening to a bottom portion of the vessel. The temperature within the vessel at the area of the scraper is maintained at a first temperature that is low enough so that loss of strength of the chips material does not result from mechanical action exerted on the chips by the scraper. Liquid is introduced into the vessel bottom portion at a second temperature that is approximately at the cooking temperature for effecting digestion of the chips, and substantially higher than the first temperature.

Abstract: A vessel is provided for holding and discharging loose bulk material, such as cellulosic chips. The vessel includes a cylinder main body with a conical discharge extending downwardly from the body. Chips are fed into the top and discharge from the bottom, with a vibrating discharge structure disposed interiorally of the bottom. In order to prevent hang-up of the chips which might block the outlet a number of prismatic elements are provided attached to the interior side walls of the vessel which terminate generally at the bottom of the main vessel body. The prismatic elements provide void volumes in the loose bulk material flowing downwardly from the inlet to the outlet, so that as the material is being funnelled down for discharge it can fill the void volumes and will not hang-up and block the bulk material outlet.

Abstract: In vertical vessels, particularly continuous pulp digesters, fibrous material suspended in liquid passes downwardly past screens through which treatment liquid is withdrawn. The screens are reciprocated vertically up and down utilizing a piston and cylinder assembly, operatively connected by a two-way valve to a source of fluid under pressure or a vent. The piston and screen are connected by a universal joint, and the screen is positively guided during movement. The piston is vertically above the screen and the screen moves downwardly under pressure from the pump, and returns upwardly, under the influence of interior digester pressure, during normal digester operation.

Abstract: A method for diffusion washing and/or thickening paper pulp having a consistency of 6 to 15%. A number of withdrawal screens and fluid introducing structures are provided supported by spider arms which comprise conduits for introduction of liquid into and withdrawal of liquid from an elongated upright hollow vessel in which the assembly is disposed. The conduit means, with attached screen structures, is reciprocated up and down by a single linear actuator located preferably above the vessel and within the cross-sectional area thereof so that the wall of the vessel need not be penetrated by the conduits. The screens and fluid introducing structures remain stationary with respect to each other during reciprocation. A number of wiper blades, which may be operated by a single linear actuator, are provided at the top of the vessel for moving upwardly flowing pulp into withdrawal conduits surrounding the vessel periphery.

Abstract: A diffusion washer and/or thickener assembly is provided that is greatly simplified. A number of withdrawal screens and fluid introducing structures are provided supported by spider arms which comprise conduits for introduction of liquid into and withdrawal of liquid from an elongated upright hollow vessel in which the assembly is disposed. The conduit means, with attached screen structures, is reciprocated up and down by a single linear actuator located preferably above the vessel and within the cross-sectional area thereof so that the wall of the vessel need not be penetrated by the conduits. The screens and fluid introducing structures remain stationary with respect to each other during reciprocation. A number of wiper blades, which may be operated by a single linear actuator, are provided at the top of the vessel for moving upwardly flowing pulp into withdrawal conduits surrounding the vessel periphery.

Abstract: A high-pressure transfer device, utilizable with wood chips or particulate material, includes low-pressure inlet and outlet ports, with low-pressure shoes associated therewith, and high-pressure inlet and outlet ports with high-pressure shoes associated therewith. A rotor containing a plurality of diametrically through-going pockets operatively communicates with the ports. The low-pressure ports, and shoes, are quadrate in cross-section, and retainers are provided surrounding the low-pressure shoes for guiding radial movement thereof. The retainers include end portions which engage side walls of the high-pressure shoes for guiding radial movement thereof. Biasing means bias the shoes into operative association with the rotor to maintain effective sealing between the rotor and housing, unaffected by radial deflection of the housing.

Abstract: A vertical container holds and treats particulate material, such as comminuted cellulosic fibrous material like wood chips. The container includes a vertical interior wall, an open top, and a discharge outlet at the bottom. A top interior wall structure directs particulate material to a first false bottom concentric with it. The first false bottom is mounted for oscillation with respect to the vertical container and discharges particulate material through a discharge opening in the generally conical bottom thereof into a second false bottom structure. The second false bottom structure also includes a generally conical bottom with a discharge opening, and is also mounted for oscillation with respect to the container. Steam is preferably introduced into the second false bottom to effect steaming of the particulate material within it, and the container is held at super-atmospheric pressure.

Abstract: A method and apparatus for continuously treating cellulosic chips to prevent degredation of the chips as a result of mechanical action exerted on the chips by a scraper. A false bottom is provided in a vessel with the scraper mounted for rotation about a vertical axis just above the false bottom, a large central opening being provided in the false bottom. The scraper removes chips from the vessel through the false bottom opening to a bottom portion of the vessel. The temperature within the vessel at the area of the scraper is maintained at a first temperature that is low enough so that loss of strength of the chips material does not result from mechanical action exerted on the chips by the scraper. Liquid is introduced into the vessel bottom portion at a second temperature that is approximately at the cooking temperature for effecting digestion of the chips, and substantially higher than the first temperature.

Abstract: A high-pressure transfer device and method of utilization thereof are provided which allow flexing of the transfer device housing, and significant wear of the relatively rotatable components, without leakage. The transfer device includes a rotor having at least five diametrically through-going pockets, and enclosed by a housing having an exterior periphery and four ports disposed around the exterior periphery for registry with inlets to and outlets from the pockets. An interior screen is provided in each rotor pocket, and the rotor is cylindrical. Sealing structures are disposed between the rotor and housing around the external periphery of the rotor and interior periphery of the housing, the sealing structures maintaining effective sealing despite any relative movement between the housing and rotor, such as radial deflection of the housing. The sealing structures preferably comprise removable sealing shoes of a less wear-resistant material than the rotor.

Abstract: A simplified diffusion washer or the like is provided. Withdrawal screens and fluid introducing structures are mounted by support arms and a central conduit. The central conduit, with attached screens and the like, is reciprocated up and down by a single linear actuator located below the vessel. Withdrawn liquid is taken out the bottom of the vessel, while treatment liquid is introduced through the top or bottom.

Abstract: A diffusion washer and/or thickener assembly is provided that is greatly simplified. A number of withdrawal screens and fluid introducing structures are provided supported by spider arms which comprise conduits for introduction of liquid into and withdrawal of liquid from an elongated upright hollow vessel in which the assembly is disposed. The conduit means, with attached screen structures, is reciprocated up and down by a single linear actuator located preferably above the vessel and within the cross-sectional area thereof so that the wall of the vessel need not be penetrated by the conduits. The screens and fluid introducing structures remain stationary with respect to each other during reciprocation. A number of wiper blades, which may be operated by a single linear actuator, are provided at the top of the vessel for moving upwardly flowing pulp into withdrawal conduits surrounding the vessel periphery.

Abstract: A high transfer pressure device, and method, especially adapted for continuously conveying hard particulate material such as coal; and a screen specifically for use in such conveying. The high pressure transfer device includes a pocketed rotor containing a pair of diametrically through-going pockets perpendicular to each other, a housing enclosing the rotor and having four ports spaced around the periphery thereof, and a screen operatively associated with the rotor or the ports for screening out particles above a predetermined size that are conveyed in liquid passed through the device. Preferably the screen is associated with one of the ports of the housing and fluid injection nozzles are associated with the screen for injecting liquid under pressure toward the screen to effect dislodgement of any particles that may be lodged in the screen and thereby prevent damage to the screen. The operation of the fluid injection nozzles is timed to the rotation of the rotor.