WO1993025752A1 - Epuration de pate a papier - Google Patents

Epuration de pate a papier Download PDF

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Publication number
WO1993025752A1
WO1993025752A1 PCT/SE1993/000384 SE9300384W WO9325752A1 WO 1993025752 A1 WO1993025752 A1 WO 1993025752A1 SE 9300384 W SE9300384 W SE 9300384W WO 9325752 A1 WO9325752 A1 WO 9325752A1
Authority
WO
WIPO (PCT)
Prior art keywords
screening
controlling
pulp
concentration
meter
Prior art date
Application number
PCT/SE1993/000384
Other languages
English (en)
Inventor
Börje FREDRIKSSON
Göran Olsson
Original Assignee
Sunds Defibrator Industries Aktiebolag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sunds Defibrator Industries Aktiebolag filed Critical Sunds Defibrator Industries Aktiebolag
Priority to AU40309/93A priority Critical patent/AU4030993A/en
Publication of WO1993025752A1 publication Critical patent/WO1993025752A1/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp

Definitions

  • This invention relates to the screening of cellulose-cont ⁇ aining pulp suspensions and, more precisely, to a method of controlling the screening process.
  • the object of the screening process is the fractionation of pulp suspensions or the separation of impurities in the form of coarse material, shives and the like from the pulp suspension.
  • the efficiency of the screening therefore, could be defined as the capacity of the screen to fraction ⁇ ate or separate impurities.
  • factors have to be taken into consideration when deem ⁇ ing the efficiency of the screening.
  • Such factors are, for example, the energy utilization and the energy costs for the screen and screening process, the capital investment utilization depending on installation costs and space re ⁇ quirement, the capacity, i.e. the flow and reliability of the screen and screening process, and the ability of low reject output and great flow variation, which is a pre ⁇ requisite for a flexible system.
  • a decrease in concentration implies an increase in the hydraulic load on the screening member, i.e. the flow rate through the apertures in the screening member increases. At concentrations below about 0.5% the capacity is unacceptably low.
  • An increase in the concentration implies an increase in the required energy intensity for breaking up the fiber network into individual fibers and render it flowing, so-called fluidization, which is a prerequisite for the screening process.
  • the necessary energy intensity supplied to the rotating members of the screen starts increasing at about 1.5% and increases rapidly above 3%- The concentration, thus, restricts an effective utilization of the screen. At too high a concentration the screening member gets clogged.
  • Optimum efficiency in a screening process is obtained when a suitable balance is maintained between the strength of the fiber network, depending on the pulp concentration and type and quality of the pulp, and the energy supply, which is determined substantially by the speed of the screen rotor. It can be difficult to maintain this balance, because the strength of the fiber network cannot be measured in a simple way. Tnis balance is especially critical at screening with high pulp concentration, 3% > boc ⁇ .use in this pulp con ⁇ centration range even small variations ' in the pulp con ⁇ centration bring about relatively great changes in the strength of the fiber network.
  • the aforesaid problems are solved by continuously measuring the reject concen ⁇ tration and using it for controlling the ingoing pulp concentration and/or the energy supply to the screening process.
  • the reject concentration being a measure of the thickening in the screen
  • this concentration can be used for adjust ⁇ ing the pulp concentration before 'the screen, for example by controlling the dilution water supply, so that the efficiency and work concentration of the screen are maxim ⁇ ized.
  • the reject concentration can adjust the energy supply for the same reason, preferably by controlling the speed of the screen rotor. In this case, the energy demand of the screen at highest possible screening efficiency is minimized.
  • the method according to the invention results in savings in the energy consumption and in a more efficient utiliz ⁇ ation of the screening arrangement.
  • the number of steps in a multi-step screening process can be reduced with maintained screening result.
  • Investment costs and space requirements are thereby reduced.
  • both the capacity and the flexibility of the screen ⁇ ing process are improved.
  • a supply line 2 for ingoing pulp suspension, an outlet line 3 for the accept fraction and an outlet line 4- for the reject fraction are connected to a screening device 1, which preferably is a pressurized screen.
  • the screening device 1 can be of conventional design, comprising a stationary screening member, and a separate rotor element with some form of pulsating member is rotatable in the screening device.
  • the screening member can be a rotatable screening cylinder.
  • a meter 5 is provided for measuring the material concen ⁇ tration in the reject line 4-.
  • Said meter 5 can be of conventional design, for example a shearing force meter or optical concentration meter.
  • a signal 6 is sent for controlling a valve 9 in a supply line 8 for dilution water.
  • This line 8 is connected to the pulp supply line 2 before the screening device 1.
  • the meter 5 can send a signal 7 for controlling the speed of the rotor of the screening device 1.
  • the pulp concentration preferably is controlled in such a way, that the reject concentration is maintained subst ⁇ antially constant at a predetermined value, for example in the range 4.8-5-2%, when the ingoing pulp concentration is about 3-2% and the accept concentration about 3%-
  • the ingoing pulp concentration may require adjustment within 3-0-3. % > which can be achieved simply by controlling the supply of dilution water from the line 8 with the valve 9-
  • a speed adjustment within - 5-10% may be required.
  • speeds within the range 4-00-600 rpm for example, an adjustment by - 30 rpm can be required. This can be achieved with a conventional control equipment.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)

Abstract

Procédé de régulation du processus d'épuration de suspensions de pâte à papier contenant de la cellulose dans un dispositif d'épuration (1), consistant à diviser la suspension de pâte (2) d'entrée en une fraction acceptée (3) et en une fraction réjetée (4) par l'intermédiaire d'un épurateur. La concentration de matières dans la fraction réjectée (4) est continuellement mesurée par un compteur (5) et convertie en un signal (6, 7), qui est utilisé pour réguler la concentration de la pâte d'entrée et/ou l'alimentation en courant du processus d'épuration.
PCT/SE1993/000384 1992-06-05 1993-04-30 Epuration de pate a papier WO1993025752A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU40309/93A AU4030993A (en) 1992-06-05 1993-04-30 Screening of pulp

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9201735-9 1992-06-05
SE9201735A SE470315B (sv) 1992-06-05 1992-06-05 Sätt att styra silningsprocessen vid silning av cellulosahaltiga massasuspensioner

Publications (1)

Publication Number Publication Date
WO1993025752A1 true WO1993025752A1 (fr) 1993-12-23

Family

ID=20386419

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1993/000384 WO1993025752A1 (fr) 1992-06-05 1993-04-30 Epuration de pate a papier

Country Status (3)

Country Link
AU (1) AU4030993A (fr)
SE (1) SE470315B (fr)
WO (1) WO1993025752A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997032078A1 (fr) * 1996-02-29 1997-09-04 Alfa Laval Ab Processus et appareil permettant de gerer la purification et la production de fibres a partir d'une suspension de fibres
WO1998050624A1 (fr) * 1997-05-06 1998-11-12 Valmet Corporation Procede et dispositif pour commander un dispositif de classage a etages multiples
WO2001059206A1 (fr) * 2000-02-11 2001-08-16 Metso Paper Inc Procede de controle de qualite de la pate de bois
EP1262594A1 (fr) * 2001-05-29 2002-12-04 Voith Paper Patent GmbH Procédé de séparation de certaines matières d' une suspension aqueuse de matières fibreuses
EP1318229A1 (fr) * 2001-12-10 2003-06-11 Voith Paper Patent GmbH Procédé pour la régulation de systèmes de triage et système de triage pour l'application du procédé
US7077930B2 (en) * 2001-03-09 2006-07-18 Metso Paper Inc. Method for controlling screening by measuring flow amount consistency of the pulp
WO2011064458A3 (fr) * 2009-11-30 2011-07-28 Andritz Oy Procédé et agencement permettant de commander une salle de classage

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1102107A (en) * 1966-01-18 1968-02-07 Ingersoll Rand Canada Screening apparatus control
US4042503A (en) * 1973-12-10 1977-08-16 Beloit Corporation Classifier and process for recycled fiber separation
WO1983001969A1 (fr) * 1981-11-24 1983-06-09 Nils Anders Lennart Wikdahl Procede permettant d'empecher l'obturation d'un dispositif de filtration
WO1983002470A1 (fr) * 1982-01-08 1983-07-21 Nils Anders Lennart Wikdahl Procede et appareil de filtration de suspensions de fibres

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1102107A (en) * 1966-01-18 1968-02-07 Ingersoll Rand Canada Screening apparatus control
US4042503A (en) * 1973-12-10 1977-08-16 Beloit Corporation Classifier and process for recycled fiber separation
WO1983001969A1 (fr) * 1981-11-24 1983-06-09 Nils Anders Lennart Wikdahl Procede permettant d'empecher l'obturation d'un dispositif de filtration
WO1983002470A1 (fr) * 1982-01-08 1983-07-21 Nils Anders Lennart Wikdahl Procede et appareil de filtration de suspensions de fibres

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997032078A1 (fr) * 1996-02-29 1997-09-04 Alfa Laval Ab Processus et appareil permettant de gerer la purification et la production de fibres a partir d'une suspension de fibres
WO1998050624A1 (fr) * 1997-05-06 1998-11-12 Valmet Corporation Procede et dispositif pour commander un dispositif de classage a etages multiples
WO2001059206A1 (fr) * 2000-02-11 2001-08-16 Metso Paper Inc Procede de controle de qualite de la pate de bois
US6846381B2 (en) 2000-02-11 2005-01-25 Metso Paper, Inc. Method for controlling quality of pulp
US7077930B2 (en) * 2001-03-09 2006-07-18 Metso Paper Inc. Method for controlling screening by measuring flow amount consistency of the pulp
EP1262594A1 (fr) * 2001-05-29 2002-12-04 Voith Paper Patent GmbH Procédé de séparation de certaines matières d' une suspension aqueuse de matières fibreuses
EP1318229A1 (fr) * 2001-12-10 2003-06-11 Voith Paper Patent GmbH Procédé pour la régulation de systèmes de triage et système de triage pour l'application du procédé
US7083049B2 (en) 2001-12-10 2006-08-01 Voith Paper Patent Gmbh Method of regulating sorting systems and a sorting system suitable for carrying out this method
EP1767690A3 (fr) * 2001-12-10 2007-10-24 Voith Patent GmbH Procédé pour la régulation de systèmes de triage et système de triage pour l'application du procédé
WO2011064458A3 (fr) * 2009-11-30 2011-07-28 Andritz Oy Procédé et agencement permettant de commander une salle de classage

Also Published As

Publication number Publication date
SE470315B (sv) 1994-01-17
SE9201735D0 (sv) 1992-06-05
SE9201735L (sv) 1993-12-06
AU4030993A (en) 1994-01-04

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