Abstract: A combustion chamber is provided that has a vertically oriented body with an inner surface defining an inner combustion area. A burner is disposed adjacent one end of the body so that the flame of the burner when lit will extend into the combustion area. A first annular insert is disposed in the combustion area and generally surrounds the flame of the burner. The annular insert defines a first secondary gas introduction zone for introducing secondary gases into the combustion area so that the secondary gases can be oxidized by the burner flame. The insert has an inner surface presenting at least one opening for allowing fluid communication between the introduction zone and the combustion area. A second annular insert is disposed in the combustion area below the first insert. The second insert defines a secondary gas extraction zone and a second secondary gas introduction zone located below the extraction zone. The gas extraction zone and second secondary gas introduction zone are separated by a divider plate.

Abstract: A method of oxygen delignification of medium consistency pulp slurry, which includes the steps of providing a pulp slurry of from approximately ten percent to sixteen percent consistency, at a temperature of from approximately 170-240.degree. F., preferably from 190 to 220.degree. F., thoroughly impregnating the slurry with oxygen gas, and with alkali to bring the slurry to a pH of at least 11, more preferably 12, introducing the slurry to oxygen gas in a high shear mixer, for agitating mixing therein, reacting the slurry in a first pressurized reactor for between 5 to 10 minutes, returning the pH of the slurry to at least 11, more preferably 12, with a residual alkali concentration of at least 1.25 gpl, thoroughly impregnating the slurry with H.sub.2 O.sub.2 and oxygen gas, and reacting the slurry in a second reactor for between 30 to 180 minutes.

Abstract: A rider roller assembly includes a beam being translationally moveable substantially vertically relative to a paper web roll being wound. A rider roller in the assembly includes a plurality of rider roll wheels which are mounted to the beam and are individually pivotable so as to engage the wound roll along a nip line. A plurality of supporting arms are articulately linked with the beam for supporting and individually pivoting the rider roll wheels on a swiveling axis in relation to the beam. The individual rider roll wheels are individually loaded against the paper web roll. Double-acting piston/cylinder units are connected to the rider roll wheels for lifting or compensating the rider roll wheels.

Abstract: A mixture of air, paper stock made from recycled paper, foaming agents and surfactants are injected into a pressurized container. The container has a stock inlet at an end opposite a stock outlet, and three outlets arranged along the top of the container between the stock inlet and the stock outlet. The first top outlet nearest the stock inlet is separated from the second and third outlets by a baffle, and the second and third outlets are separated from the stock outlet by a baffle. Each outlet has a valve which controls flow from that outlet. By adjusting the outlet valves, foam and waste ink is vented from the first and second outlets from the stock inlet, while stock is vented from the third outlet which is closest to the stock outlet. The stock passing through the third outlet is recycled through the container.

Abstract: A modular screening apparatus has four parallel shafts arranged in a single plane mounted to each module. The shafts extend between the sides of the machine frame and are driven by a motor and timing belts which connect the shafts directly or indirectly to the drive motor. Each shaft supports three beater bars which are equally spaced about the axis of the shaft. A screen bed defined by a perforated polyurethane plastic sheet overlies the plane containing the driven shafts. The sheet serves as a screen which is clamped at its upstream edge, the downstream end extending over a fixed bar and vertically downwardly, to suspend a weight. The sides of the screen abut adjustable side plates which are mounted to the machine frame and define the boundaries of the screen bed. The beater bars rotate on the shafts to strike the underside of the screen.

Abstract: A papermaking refiner has two stationary disks mounted to the support structure of a fixed housing. A rotating disk is mounted on a shaft which extends through the housing. The support structure allows stock to circulate on both sides of the disk support structure, thus balancing fluid pressures on both sides of the fixed disk and preventing thermal gradients for reduced deflection of the disks. The incoming stock is centrifugally accelerated in a shroud which separates and traps tramp metal or the like before the stock passes to the refiner disks. The shroud has passageways which allow the rotating fluid to enter a reservoir which surrounds the drive shaft and feeds the gaps between the rotor and the stationary plates.

Abstract: A papermaking machine including a forming section for forming a paper web, a press section for pressing water from the paper web, and a dryer for drying the paper web is disclosed. The dryer includes a wet end for drying the paper web to at least about 60 percent solids and a dry end for further drying the paper web. The dry end includes at least one series of alternating dryer cylinders and vacuum rolls. A dryer felt transports the paper web as the dryer felt travels about each dryer cylinder and each vacuum roll of the series. In one disclosed embodiment, at least one of the vacuum rolls receives a vacuum of at least about one inch water column (1.5 kilo-pascals, "kPa") to restrain the web as it dries. A method for manufacturing a paper web while restraining it by using the dryer apparatus described above is also disclosed.

Abstract: A papermaking machine has a heated Extended Nip press following the pressing section. High temperature pressing raises the exit solids out of the press to 55 to 65 percent. The web then enters a high intensity dryer section where the web is pressed onto a dryer roll in intimate contact with the roll where it is dried up to approximately 90 percent solids. A coating on the dryer roll and the Extended Nip backing roll is composed of ceramic, metal and a fluorocarbon to allow the web to be separated from the backing roll and the dryer roll with ease. The dryer roll is internally heated by steam or preferably gas to between 200.degree. F. and 500.degree. F. An aircap positioned over the web on the dryer blows hot air at a temperature of 200-500.degree. F. at a velocity of 15,000 to 30,000 feet per minute onto the web.

Abstract: An extended nip press apparatus is disclosed for pressing a web of paper. The apparatus includes a press which defines a concave surface. A backing roll cooperates with the concave surface for defining therebetween an extended nip pressing section. A looped bearing blanket slidably cooperates with the concave surface, the blanket being disposed between the press shoe and the backing roll for supporting guiding the web through the pressing section. An electromagnetic unit drivingly cooperates with the shoe, the arrangement being such that when the electromagnetic is energized, the shoe is electromagnetically urged near the backing roll for pressing the web. The electromagnetic includes plurality of electromagnetic units disposed in a cross-machine direction so that each unit when energized exerts a force on the shoe for urging the shoe towards the backing roll. A control arrangement controls the force exerted by each unit.

Abstract: A foil blade for use in dewatering devices found in a web forming section of a papermaking machine is described. The improved foil blade according to the present invention is easily installed into and removed from such dewatering devices. The improved foil blade of the present invention is rigidly mounted within the same dewatering devices such that the foil blade does not rotate or change geometry during a papermaking process as a wire or fabric having a stock mixture thereon travels over the foil blade. The improvement resides in providing a loaded clamping assembly for the foil blade. In one embodiment, according to the present invention, the loaded clamping assembly comprises a pneumatic load air tube to rigidly secure the foil blade to a dewatering device in a web-forming section of a papermaking machine. The foil blade being firmly clamped in position by way of the loaded air tube, cannot rotate or change geometry during operation.

Abstract: Fiber-containing stock is fed into a hydrocyclone with a wall structure which generates quasi-laminar flow within the hydrocyclone housing. A piezoelectric oscillator introduces ultrasonic waves into the quasi-laminar flow to achieve high volume separation of heavyweight particles from the acceptable fibers with improved differentiation.

Abstract: A dryer section in a papermaking machine has two reversing rolls to form a pocket between each pair of dryers in a dryer tier. The first reversing roll is a vacuum roll and the second reversing roll is a grooved roll. A blow box is disposed between the two rolls, the blow box provides suction for the grooved roll and provides vacuum which restrains a web on the dryer fabric as it travels between the first and the second rolls. The blow box also provides a supply of make-up air which extends in a cross machine direction along the pocket formed by the two reversing rolls. The blow box also supports a pivoting foil which is positioned against the dryer fabric as it moves from a first dryer, towards the first reversing roll. The foil defines a region of low pressure which restrains the web as it travels between the first dryer and the first reversing roll.

Abstract: A control system for a repulping apparatus having a vat containing a pulp and water slurry and a rotatable blade for mixing the pulp and water to form the slurry. A feed apparatus moves the pulp into the vat and a feed indicator senses the entry of the pulp into the vat and produces an entry signal indicative of the pulp entering the vat. A controller responsive to the pulp entry signal calculates the volume of water to be added to the vat and the water flow rate to provide a predetermined consistency in the slurry and produces a signal representative of the calculated volume of water. A water volume control receives and is responsive to the calculated water volume signal to control the admitting of water into the vat. The controller also produces a signal representative of the calculated rate of flow. A flow control is responsive to the calculated water volume signal and to the calculated rate of flow signal to admit water into the vat at the calculated rate of flow.

Abstract: A headbox is provided which provides an improved uniformity in the velocity profile of the stock solution across the slice opening. As a result, improved fiber alignment is provided across the width of the entire slice opening and mis-alignment of the fibers towards the outer edges of the slice opening is avoided. The headbox includes an improved nozzle design with pondsides that are not parallel to one another but which are angled inwardly as they extend from the tube bank to the slice opening. Further, several columns of outer tubes of the tube bank may also be angled inwardly as they extend from the header to the nozzle section. The center tubes would be disposed in a parallel relationship to one another. A sealing arrangement is provided between the roof of the nozzle section and the pondside which permits the incorporation of a double knuckle for extending and retracting the roof to adjust the L/b ratio.

Abstract: A method and apparatus for applying a uniform coating to a moving paper web by utilizing a coating applicator with regional cross-machine zones from which coating quality or excess coating can be monitored and analyzed. As the coating conditions vary between regional zones, upstream liquid coating flow parameters can be varied for a particular region to render uniform coating profiles across the entire machine-direction of the web.

Abstract: A method and apparatus is disclosed for effecting, in a preferred embodiment, a double-sided web splice for paper webs produced in the papermaking process. A trailing portion of a first paper web is held and cross-cut over a support beam which is selectively moved into, and out of, supporting position beneath. The leading portion of a second paper web is brought into position over the support beam where the second paper web is also held and cross-cut. Carriages containing first and second tape means traverse the trailing and leading edges of the webs. On one carriage is mounted a plow-like web lifting and separating apparatus for contacting the leading and trailing edges of the webs and forming a splice bed between the temporarily lifted and separated web edges. A first tape means is mounted to the carriage to extend an adhesive tape in the web bed, the tape having a non-adhesive side supported on the beam.

Abstract: A de-trashing unit has a rotor fabricated from steel blank. The rotor has two swept blades with blunt leading edges and relieved trailing edges. The rotor is driven to rotate over a trash screen with holes of between one-quarter and one-half inch in diameter. The blade is positioned with a clearance between the blade and the screen of between 0.005 and 0.010 inches. The relieved portions of the blades face the screen while the trailing edges of the blade are tapered between 18 and 30 degrees away from the screen surface. The blade taper creates a strong negative pressure pulse which keeps the screen clear. Holes drilled through the relieved portion of the blade allow circulation through the blade into the region of low pressure generated by the relieved portions passing over the screen. The circulation created by the holes creates microturbulence which keeps a water and paper fiber slurry fluidized.

Abstract: Paper fiber suspended in black liquor is washed in a rotating drum divided into a plurality of adjacent sectors. The fiber is formed into a mat on the drum, and the drum is rotated so the sectors progress through a first wash and a second wash of progressively cleaner wash fluid. Each sector has two distinct drainage systems. One drainage system drains the first wash water after it has passed through the mat, and is then blocked while that sector passes through the second wash. The cleaner second wash fluid is thus kept separate from the more contaminated first wash fluid, and is recirculated to be used in subsequent cycles as first wash fluid.

Abstract: A doughnut or puck-shaped spacer has a centrally positioned square hole. A pie-shaped cutaway portion of the spacer allows the spacer to be elastically deformed mounting on a square rod. The rod and spacers join together the bars of a bar screen rack. Bars making up a screen bed are approximately one-quarter inch thick and cantilevered sections of the screening bars benefit from being joined together to control the spacing of the bars and to add rigidity to each rack of bars which makes up the bar screen rack. For ease of assembly, canted slots receive a square rod. The spacers are readily positioned between legs on the square rod. The individual bars are then joined by tightening a nut at the threaded end of the rod, clamping the bars in spaced parallel relation.

Abstract: A headbox employs flow control valves which modulate the flow of stock through each tube of a tube bank, to give greater control over the cross machine direction flow of stock to the forming section of a papermaking machine. In one approach the flow through the tubes making up the tube bank is controlled by rotating cylindrical valve members which extend into portions of the tubes making up the tube bank. The valve members have channels which align with the tubes when the valve is fully opened. Rotation of the control member obstructs the tubes in the column until the desired level of flow from that column of tubes is obtained. In a second approach, pinch valves are created by constructing part of the tube from an elastic material and using air pressure, a cam or a twisting action to reduce the flow through the elastic section thus creating an adjustable valve. A third method employs guillotine valves which selectively block the flow of stock through a column of tubes.