Abstract: A process for chlorine-free bleaching of chemical pulp in association with the production thereof, where a suspension of the pulp preferably has a concentration exceeding 8% of cellulose-containing fiber material and where the pulp entering into a bleaching line is preferably fed continuously through at least one bleaching vessel in the bleaching line, is treated with at least one acid for adjusting the pH to a value below 7, and with a chelating agent, and is subsequently bleached in at least one stage to a brightness exceeding 75% ISO, preferably exceeding 80%, with hydrogen peroxide or the corresponding quantity of another peroxide, employed in a quantity exceeding 5 kg/BDMT, where the peroxide bleaching takes place at elevated temperature and at a pressure in the bleaching vessel which exceeds 2 bar and where the cross-sectional area of the bleaching vessel exceeds 3 m.sup.2 and the area of the metal surface exposed towards the interior of the bleaching vessel is less than 4 V m.sup.

Abstract: A screen system for a digester for continuous cooking under raised pressure and temperature of fibre material in a vertical vessel, where input of fibre material and cooking liquid takes place at the top of the digester, withdrawal of spent cooking liquor is carried out from at least one digester screening arrangement (1D) between the top and the bottom of the digester, and fibre material is fed out from the bottom (1C) of the digester, wherein at least one of said screening arrangements (1, 2) has at least one screen element (2A) of which the main configuration is circular and which is assembled by means of welding, and which is fitted into the digester shell by means of welding.

Abstract: The invention relates to a diffuser, comprising a substantially cylindrical, vertical container, through which cellulose pulp is arranged to be transported, nozzle arms, for delivering a fluid, such as washing liquid, to the pulp, concentrically disposed screen surfaces and screen arms disposed on and connected to said screen surfaces for withdrawal of said fluid. The screen arms are provided, at their outer ends, with withdrawal pipes, directed substantially vertically downwards, which are slidably controlled and are connected in sealing arrangement to outlets for said fluid. The invention relates also to a stuffing box designed to receive a rod, preferably a pull rod for raising and lowering a screen pack having screen surfaces in a diffuser, said rod being guided in sealing arrangement and slidably through a fixture which is mounted in a bearing for free movement in a plane substantially perpendicular to said rod.

Abstract: An apparatus for mixing a first fluid into a second fluid that comprises a housing (1) having a flow chamber (39) for the second fluid, a flow restrictor member (6) in the flow chamber, and holes (18) for introducing the first fluid into at least one gap (15, 16) between the flow restrictor member and those walls (5, 10) of the flow chamber (39) facing towards the flow restrictor member. The flow restrictor member and flow chamber, in a plane transversely to the principal flow direction (31) of the second fluid, each has the shape of a wedge. Gaps (15, 16) are formed between each of those two sides of the flow restrictor member that converge in a wedge shape and those walls of the wedge-shaped chamber facing towards the flow restrictor member. The holes (18) for introducing the first fluid are disposed in the region of the gaps (15, 16).

Abstract: A method for washing a fibre suspension including the steps of feeding the suspension into an annular displacement space, supplying a fluid through a permeable outer surface of the space, rotating the space to establish a fibre layer between the fluid supplied through the permeable outer surface of the displacement space and a remaining part of the fibre suspension.

Abstract: A screening device for pulp production includes a cylindrical container for continuous flow-through of a fiber suspension and further includes an inlet to the container and an outlet for the fiber suspension, a moveable support member mounted in the container and which supports hollow screening members for vertical movement; a tubular enclosure open at opposite ends is mounted on the supporting member which enclosure has a moveable piston mounted therein, a hydraulic cylinder being connected to the piston to move the piston in a portion of the enclosure with the hydraulic drive mounted outside of said container with transmission members connected to said supporting member which will therefore absorb the reaction forces generated in moving the piston.

Abstract: A method of integrating bleaching and recovery in connection with the production of chemical pulp that has been digested and preferably delignified with oxygen gas using processes that retain the viscosity and strength, to kappa number less than 16 without the use of chemicals containing chlorine, and using a bleaching sequence including at least one step with sequestering agent and/or acid, and a peroxide step.

Abstract: A process for the continuous digestion of cellulosic fiber material, comprising impregnation with impregnating liquid consisting of at least one fresh digesting liquor, in a closed impregnating system and subsequent digestion with digesting liquid in a closed digester system, said impregnating liquid being supplied through a supply system, together with steamed fibre material, to an inlet end of the impregnating system, liquid being withdrawn from the impregnating system at a point (46) located at a predetermined distance from said inlet end.

Abstract: A process for recovering energy from a combustible gas generated by partial oxidation of cellulose waste liquor in a gas generator (A) operating in a temperature range of 600.degree.-1300.degree. C. and a pressure in the range of 1-100 bar, cooling and cleaning said combustible gas and using the gas as fuel in a recuperated gas turbine cycle (C, E), wherein water and/or steam is injected to humidify compressed air and/or combustible gas, increasing turbine motive fluid massflow and power output.

Abstract: A screening body for a pulp digester includes two, spaced apart ring supporting a plurality of axially extending screening bars each of which has a foot portion frictionally received in and welded to a correspondingly formed recess formed on the inner side of each of the ring segments; an apparatus for manufacturing a screening body is also provided and which includes a first assembly member which mounts a form for receiving the ring member segments in parallel relation and into which are inserted the screening bars with the foot portions fractionally received in complementary recesses formed on the inner side of each of the ring segments; a retaining member in the form of a second assembly device includes a cylindrical drum surface which is pressed against the screening bars of a partially assembled screening body section while a second and subsequent sections of the screening body are assembled.

Abstract: A screening body for a pulp digester includes two, spaced apart ring supporting a plurality of axially extending screening bars each of which has a foot portion frictionally received in and welded to a correspondingly formed recess formed on the inner side of each of the ring segments; an apparatus for manufacturing a screening body is also provided and which includes a first assembly member which mounts a form for receiving the ring member segments in parallel relation and into which are inserted the screening bars with the foot portions fractionally received in complementary recesses formed on the inner side of each of the ring segments; a retaining member in the form of a second assembly device includes a cylindrical drum surface which is pressed against the screening bars of a partially assembled screening body section while a second and subsequent sections of the screening body are assembled.

Abstract: A screen dram for the dewatering and/or washing of cellulose pulp, comprises a first cylinder (2) made from non-stainless material, which is rotatable about its axis (5); a cylindrical screen plate (6) arranged coaxially on the outside of the first cylinder, but at a distance from it, and between the screen plate and the first cylinder an annular chamber (7) which can receive liquid which has passed through the screen plate, which chamber contains passages (26) which extend in the axial direction towards one or both ends of the drum for the withdrawal of the screen liquid. The chamber (7) is lined with stainless steel (8) in the form of one or more cylindrical plate sections (8a, 8b . . . 8n). These, by virtue of shrink joints, can be joined to and bear in seal-tight arrangement against the cylindrical casing of the first cylinder. Preferably, the stainless steel contains at least 5% molybdenum.

Abstract: In a pulp digester for continuous cooking under raised pressure and temperature of fiber material in a vertical digester (1), input of fiber material and cooking liquid takes place at the top of the digester, withdrawal of spent cooking liquor is carried out from at least one digester screening arrangement (1D) between the top and the bottom of the digester, and fiber material is fed out from the bottom (1C) of the digester, and at least one screening arrangement (2) in the lower half of the digester, wherein at least one of said screening arrangements (1, 2) has at least one screen element (2A) of which the main configuration is of angular shape, preferably rectangular, most preferred square, having a screen face (3A) of which the total area is less than 1 m.sup.

Abstract: A device for treating a preferably cellulose-containing suspension, comprising a housing (1) on a stand (2).

Abstract: Apparatus for treating pulp with a treating liquid, comprising a vessel (1) with cylindrical wall (2), inner screening means (3) for withdrawing liquid from the pulp, and a plurality of distributing tubes (5) on the outside of the vessel for the supply of treating liquid into the vessel through a plurality of inlet connections (6). According to the invention each distributing tube (5) is formed of an annular section (20) and an opposing part (21) of the cylinder wall (2), the section being welded directly to the cylinder wall, and the section and the cylinder wall part enclosing between them a distributing channel (22). Furthermore, each inlet connection (6) is provided with an opening (23) extending through the cylinder wall part and connecting the distribution channel to the interior of the vessel.

Abstract: A process is disclosed for bleaching pulp without chlorine containing chemicals and for greatly reducing total washing filtrate discharge, comprising the steps of: 1) sending pulp that has been subjected to continuous digestion, oxygen-delignification and then washing, through a washing press; 2) treating, with agitation, the delignified washed pulp with sulfuric acid and a chelating agent; 3) washing the pulp in a washing apparatus; 4) bleaching with hydrogen peroxide in a reaction vessel; 5) washing the hydrogen peroxide bleached pulp; 6) adding sulfuric acid and ozone with mixing of the pulp; 7) reacting the pulp with ozone in a reaction vessel; and 8) washing the ozone reacted pulp, wherein the majority of liquid filtrate from the bleaching process that is waste not to be recycled is drawn off from the washing apparatus of step 3, the washings in step 3 and 5 have at least 85% efficiency, filtrate from washing step 5 is recirculated to the washing apparatus of step 3, and filtrate from the washing apparat