Abstract: A slurry dispensing system is disclosed. A peristaltic pump may direct a flow of slurry out of a horizontal mixer to a slurry dispenser. This slurry dispenser may be operated on a programmed manner by a controller to dispense slurry into a container. Both a bypass valve and a dispensing valve of the slurry dispenser may be opened/closed on a programmed basis by the controller to deliver slurry to a container, such as a glass column. Slurry may be intermittently directed into a metering chamber of the slurry dispenser, while the remainder of the slurry being directed into the slurry dispenser may be recirculated back to the horizontal mixer.

Abstract: The method is for pre-treatment of chips that are fed to a sulphate cooking process. Through acidification of the chips in an acidic treatment fluid with a subsequent draining of free treatment fluid before subsequent steaming or wet-steaming, a high concentration of free hydrogen ions is established within the chip pieces. When the chips are subsequently formed into slurry with preferably a sulphide-rich alkali cooking fluid, H2S is formed locally in the chip pieces which gives a yield-increasing effect in the subsequent cooking step of 1-3%.

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 is directed towards the method of processing of fibrous mass by a chemical agent and the set up needed for the conducting of the process. Fibrous mass is mixed with a gas transfer agent in the mixing cell and goes to the flow-type tube cell which is shaped like a spiral with the 1:18-1:60 ratio between tube and loop diameters. The chemical agent is transferred immediately to the reactor throughout the jets attached to the reactor lengthwise. The process is carried out in a turbulent regime of motion of the reaction mixture with the velocity of 1-50 m/s. The current invention allows to reach the higher effective processing of fibrous mass, to reduce the consumption of the chemical agent and to increase the quality of the processed material. It can be utilized in paper and pulp industry for the processing of cellulose using a bleaching agent.

Abstract: Methods for discharging spent cooking liquors from a batch digester containing cooked lignocellulose-containing material in spent cooking liquor are disclosed, including supplying a first portion of washing liquid to the digester to displace a first portion of the spent cooking liquor at a temperature and dry solids content which substantially corresponds to the temperature and dry solids content of the spent cooking liquor at the end of the batch digestion, supplying a second portion of washing liquid to the digester to displace a second portion of the spent cooking liquor having a temperature and dry solids content substantially lower than that of the spent cooking liquor in the digester, and maintaining the first and second portions of spent cooking liquor separate from each other. Methods of producing kraft pulp in batch digesting processes using this method are also disclosed.

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 the continuous digestion of cellulosic fiber material is described wherein the material is impregnated with liquid in a closed system comprising a concurrent flow zone and a countercurrent flow zone, the liquid in the concurrent flow zone including black liquor and possibly white liquor and the liquid in the countercurrent flow zone including white liquor. Liquid is withdrawn from the impregnation system at a point located between the concurrent flow zone and the countercurrent flow zone. Besides white liquor a predetermined amount of black liquor is added to the countercurrent flow zone in order to obtain a high liquid to wood ratio in the inlet of the digester.

Abstract: In an atmospheric diffuser for the treatment of paper pulp (thickening, bleaching, and/or washing) the flow of backflushing liquid is controlled so as to maximize the effective treatment of the pulp. The pulp passes upwardly in a vessel. A number of annular screen assemblies are provided, with at least one screen associated with each screen assembly. The lower screen includes a barrier wall with a passage in the barrier wall adjacent the bottom end of the screen. Liquid which flows through the screen must flow to the passage in order to be withdrawn from the vessel, as the screen is slowly moved upwardly. When the screen is rapidly moved downwardly to cause backflushing, the backflushing liquid at the top end of the screen is liquid that recently passed through the screen at that point, so the pulp at that point --which is the cleanest along the length of the screen--has a minimal chance of being contaminated.

Abstract: A process for the continuous digestion of cellulosic fiber material is described wherein the material is impregnated with liquid in a closed system comprising a concurrent flow zone and a countercurrent flow zone, the liquid in the concurrent flow zone including black liquor and possibly white liquor and the liquid in the countercurrent flow zone including white liquor. Liquid is withdrawn from the impregnation system at a point located between the concurrent flow zone and the countercurrent flow zone. Besides white liquor a predetermined amount of black liquor is added to the countercurrent flow zone in order to obtain a high liquid to wood ratio in the inlet of the digester.

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 multi-stage wood chip cooking process performed in a single digester in a batch type operation. The wood chips to be cooked are introduced into the digester and soaked with a warm black liquor to remove most of the air from the digester and the chips. This warm black liquor is thereafter displaced from the digester with a mixture of a first stage hot black liquor and hot white liquor, the proportionate amount of hot white liquor being relatively high. The temperature of the digester contents is then raised to a cooking temperature for a predetermined amount of time. The original cooking liquor is then displaced with a mixture of a second hot black liquor and hot white liquor, the proportiionate amount of hot white liquor in this second cooking liquor being less than in the first. Again, the temperature of the digester is raised to a cooking temperature and the cooking is carried out for a shorter period of time than in the first cooking stage.

Abstract: For bleaching cellulose pulp or a fraction thereof, e.g. reject pulp, the cellulose pulp or fraction, having a concentration of 0.5-10%, preferably 3-6%, is introduced into a screw press comprising at least a first (47) and a second (48) dewatering zone, is dewatered in the first zone to a concentration of 20-40%, whereupon a liquor of bleach chemicals is introduced centrally into the pulp which, during continued treatment, is dewatered in the second zone to a discharge pulp concentration of 15-50, preferably 15-30%, the liquid pressed out of the second zone, together with fresh bleach chemicals, being returned to the pulp in the screw press as liquor of bleach chemicals.

Abstract: A recovery method for settled black liquor in ponds and lagoons is disclosed so that ponds and lagoons which can no longer be pumped to recovery evaporators and furnaces are reconstituted by augering the settled black liquor and passing the augered material through filters, partical micronization chambers and static mixers.

Abstract: A method and apparatus for selectively withdrawing liquor from digester cooking screens for controlling the temperature in continuous digesters. First and second pairs of screens, with cooperating headers, are provided, and first and second outlets spaced circumferentially around the digester are associated with each header. Each header provides a circumferential cavity free of dividing members. Within each pair of screens withdrawal is practiced so that each header is rested during each ultimate withdrawal step, and the side from which the liquor is drawn each successive withdrawal step that the same header is used is alternated. In practicing the invention, header blockage caused by deposited debris and scale is minimized and increased uniformity and improved product quality result.

Abstract: A method and apparatus for liberating the latent properties of a mechanical pulp is disclosed. The method is a laboratory technique for sample preparation for further pulp testing. "Latency" is released by recirculating pulp from a pool thereof through a centrifugal pump at a rate of at least four times per minute for the period required to release all the latent properties of the pulp sample ("Latency"). This depending on the rate of circulation may be completed in as little as one minute.

Abstract: A process for producing alkali pulp by using a single, cylindrical pressurized reaction vessel having therein a liquor-inpregnating zone, a cooking zone, a washing zone, and a diluting zone in that order, and having a motor-driven scraping or agitating device and a pulp discharging outlet in the end portion of the diluting zone. Alkaline aqueous medium containing dissolved oxygen therein is introduced into the diluting zone. A part of the introduced alkaline aqueous medium countercurrently contacts cooked cellulosic materials transferred from the washing zone to the diluting zone to proceed with oxygen-alkali delignification, and is finally discharged out of the vessel from the end portion of the cooking zone.

Abstract: A method for removing residual oxygen from an aqueous slurry of pulp that has been oxygen-bleached is disclosed. The slurry, usually containing no more than 3 weight percent fiber, is agitated by a radial-flow impeller, which imparts a substantially radial flow to the slurry. If the residual oxygen is not removed, it may degas at an inopportune moment during later processing (for example, washing) and carry some of the wood fibers to the surface of the slurry, thereby forming a foamy mat, which hinders further processing.

Abstract: A process for the manufacture of paper pulp from waste paper in which the waste paper is comminuted in water in a pulper, pre-cleaned for removal of coarse foreign contaminants, dewatered, kneaded at high concentration, diluted, after-cleaned for removal of finer or coherent soft foreign contaminants and adjusted to a concentration suitable for paper-making, the water respectively used for dilution and obtained during dewatering being circulated in two separate circuits upstream and downstream respectively of the kneading apparatus.