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WO1983001969A1 - Procede permettant d'empecher l'obturation d'un dispositif de filtration - Google Patents

Procede permettant d'empecher l'obturation d'un dispositif de filtration Download PDF

Info

Publication number
WO1983001969A1
WO1983001969A1 PCT/SE1982/000366 SE8200366W WO8301969A1 WO 1983001969 A1 WO1983001969 A1 WO 1983001969A1 SE 8200366 W SE8200366 W SE 8200366W WO 8301969 A1 WO8301969 A1 WO 8301969A1
Authority
WO
WIPO (PCT)
Prior art keywords
valve
reject
screen
screening
conduit
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/SE1982/000366
Other languages
English (en)
Inventor
Nils Anders Lennart Wikdahl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to FI832665A priority Critical patent/FI832665A7/fi
Priority to BR8207990A priority patent/BR8207990A/pt
Priority to AU91223/82A priority patent/AU9122382A/en
Publication of WO1983001969A1 publication Critical patent/WO1983001969A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00—Other accessories for paper-making machines
    • D21G9/0009—Paper-making control systems
    • D21G9/0018—Paper-making control systems controlling the stock preparation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D37/00—Processes of filtration
    • B01D37/04—Controlling the filtration
    • B01D37/043—Controlling the filtration by flow measuring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D37/00—Processes of filtration
    • B01D37/04—Controlling the filtration
    • B01D37/046—Controlling the filtration by pressure measuring
    • 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

  • the present invention relates to a method of preventi clogging a screening means in a screen, and/or blocking up a reject valve located in a reject conduit in screening a f bre suspension, a flow of accept being withdrawn through an accept conduit, and the pressure drop across the screening means being sensed for controlling tapping off a reject by means of the valve in the reject conduit.
  • Screens of different implementation are used in pulp paper mills for cleaning suspensions of cellulose fibres.
  • the screening su faces are either stationary or rotating.
  • the screens are equipp with foils, which are given a relative speed in relation to the screen surface and during screening have the task of de- structively affecting the fibre network formed on the screen surface, thereby preventing complete clogging of the holes o slits in the screening means.
  • a tendency to slamming-up can often, but not always, be prevented by increasing the relati rate of revolutions between the screening means surface and foil- A substantial increase of this revolutional rate can lead to the desired cleaning, although to the price of in ⁇ creased costs for the required power consumption.
  • SE-B 304 677 discloses a screening machine comprising valve in the screen reject conduit.
  • Said conduit has a regul ting means designed to be positioned in a predetermined best possible regulating position, an actuating means for opening the valve to a position essentially more open than said best regulating position without disturbing the setting of said regulating means, and a sensor responding to a predetermined smallest flow rate in said reject conduit to open the valve said actuating means from said best regulating position, sai sensor being designed not to open said valve from said best regulating position in response to variations in the flow ra through said reject conduit which variations are insufficien for reducing the flow rate to said smallest value, and said sensor is acting to return said valve to said best regulatin position when the flow rate has increased to a value essen- tially above said smallest value.
  • One object of the present invention is to prevent hole or slits in a screening means from clogging.
  • Another object of the present invention is to prevent blockage in the valve in the screen reject conduit.
  • the flow through the accept conduit can be constricted by a valve therein.
  • This constric tion may take place when the reject valve is in its second position and preferably simultaneously with opening the reje valve. It is particularly preferred that opening the reject valve is done rapidly, i.e. it is instantaneous.
  • Figure 1 schematically illustrates a screen controlled in accordance with the invention
  • Figure 2 schematically illustrates the degree of separ tion for two different impurities as a function of the rejec rate.
  • the screen S in Figure 1 may be a screen with stationa screening means and rotating foils, e.g. as described in the Swedish Patent Specification No. 343 621.
  • the fibre suspension which is to be screened is taken through a conduit 1 to a screen S.
  • a portion of this suspen ⁇ sion i.e. the main portion in nearly all applications, pass through the holes or slits in a screening means 4 and leaves the screen S through a conduit 2 as accept.
  • the remaining po tion of the incoming suspension, which does not pass through the openings of the screening means 4, is tapped off through a conduit 3 as reject.
  • the flow rate through the conduits 2 and 3 is regulated by means of valves 5 and 6, respectively.
  • the pressure drop across the screen S is sensed by a pressure sensing means PG.
  • a signal proportional to the pressure drop is fed to a control device MP.
  • the control device MP controls the setting of the valves 5 and 6 in response to the signal from the pressure sensing device PG and the programming of a microprocessor in the control device MP by means of two valve actuating means 7 and 8, respectively.
  • a flow meter can be provided in the reject conduit 3.
  • a sig- nal proportional to the sensed reject flow rate is led to a control device FC being designed to keep the reject flow rate constant.
  • a signal proportional to the deviation i fed to the actuating means 8 changing the valve opening towar the predetermined flow rate value.
  • This flow control device F is only able to open the valve 6 to a predetermined greatest - opening, far from being completely open.
  • the control device FC is only able to change the valve opening in a narrow range It is desired to achieve purification of the fibre sus- pension by means of screening.
  • the impurities ar concentrated in the lesser of the two flows leaving the screen, i.e. in the reject flow, while the other larger flow is impoverished of impurities.
  • the reject Apart from a larger content of impurities the reject thus also contains prime fibres. It is quite natural to strive to keep the content of fibres in the reject as low as possible.
  • This purification or separation is a function of the reject rate, i.e. the ratio between the re ⁇ ject flow rate and the feed flow rate, apart from parameters depending on the screen and screening means used, i.e. its hole diameter and total orifice area.
  • Figure 2 schematically illustrated the relative separation of impurities of two dif ⁇ ferent kinds as a function of the reject rate.
  • the reject rate must exceed a given minimum value in order to achieve an acceptable purification of the suspension without fibre loss being unacceptedly great.
  • the reject rate is usually 10 — 25 per cent by volume, preferably 10 - 15 per cent by volume.
  • the fibre content is approximately twice as great as in the feed or inject. This means that for a reject rate of about 10 - 15 per cent by volume there is a fibre los of about 20 - 30 per cent.
  • Tapping the reject usually takes place continuously, an is then preferably a constant proportion of the inject. In certain applications periodical tapping of the reject is possible. Usually the reject is withdrawn continuously.
  • valve 6 controlling the re-ject rate is heavily constricted, i.e. the low-through in the valve has small cross-sectional area.
  • Valves are often de signed so that for a small degree of opening they have a larg ratio between the cross-sectional circumference and area in the low-through portion of the valve. This results in that the risk of clogging .increases for heavy constriction of the valve. In turn, this means that when the flow- hrough area in the reject valve is kept constant, there is occurring a cer ⁇ tain amount of clogging in it. This is sensed by the pressure sensing means as a pressure increase across the screening means. If this clogging is not cleared, it will finally lead to complete stoppage.
  • clogging of the screening means openings and/or blocking up of the screen re ject valve is monitored by measuring the pressure drop acros the screen.
  • a signal varying in response to this pressure dr is applied to the controlling means MP including a micro- processor.
  • the controlling means actuates the valve 6 via an actuating means 8, the valve then being broug into a second, pr'eferably entirely open position.
  • the pressu drop across the screening means 4 thus falls, the reject flo will be greater and entrain with it a possible collection of fibres in the valve opening, and the load on the screening means will be less.
  • the moving foils can now more easily re ⁇ move possible clogging.
  • the clearing effect in question can, if necessary, be amplified by the valve 5 also being actuated when the valve 6 is in or is being brought into its open position.
  • This actua- tion provides a suitable constriction of the accept flow.
  • the valve 5 is preferably caused to return to its earlier positio simultaneously as the valve 6 assumes its first position.
  • the return of the valve 6 and possible the valve 5 to their first positions is con- trolled by the pressure drop across the screening means.
  • This return i.e. the duration of the clearing proce"ss, can also b controlled so that it takes place after a given predetermined time.
  • the microprocessor of the controlling mean can be programmed so that, independent of the sensed pressure drop, it gives a signal after a given number of seconds, e.g. 5 seconds, said signal actuating the valves 5 and 6 via actua ting means 7 and 8, respectively, so that these return to their first positions.
  • microprocessor also to be programmed such that the stated clearing is carried out periodically and independent of the pressure drop across the screen S.
  • valves 5 and 6 should be implemented such that the ratio between the cross-sectional area of the flow-through and its periphery is as large as possible.
  • pre ⁇ ferred valves are ball and ball sector valves.
  • valves 5 and 6, particularly the valve 6, should have a structure such that rapid regulation can take place thereby increasing the clearing effect.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

Dans la filtration d'une suspension de fibres, une ligne d'acceptation et une ligne de rejet sont dérivées, le soutirage du rejet étant commandé par une vanne (6). Selon l'invention, la chute de pression sur le dispositif de filtration est mesurée, et lorsque cette chute est supérieure à une première valeur prédéterminée, la soupape (6) s'ouvre d'une première vers une seconde position et lorsque la chute de pression tombe en-dessous d'une seconde valeur prédéterminée ou lorsqu'un laps de temps prédéterminé s'est écoulé la soupape revient à sa position antérieure à l'ouverture. Dans la seconde position, la soupape de rejet (6) est de préférence complètement ouverte. L'écoulement d'acceptation peut éventuellement être étranglé lorsque la soupape de rejet se trouve dans la seconde position.
PCT/SE1982/000366 1981-11-24 1982-11-04 Procede permettant d'empecher l'obturation d'un dispositif de filtration Ceased WO1983001969A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
FI832665A FI832665A7 (fi) 1981-11-24 1982-11-04 Menetelmä seulontavälineen tukkeutumisen estämiseksi.
BR8207990A BR8207990A (pt) 1981-11-24 1982-11-04 Processo de impedir o entupimento de um dispositivo peneirador
AU91223/82A AU9122382A (en) 1981-11-24 1982-11-04 Method of preventing clogging a screening means

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8106985A SE8106985L (sv) 1981-11-24 1981-11-24 Sett att forhindra igensettning av ett silorgan vid silning av en fibersuspension
SE8106985-8811124 1981-11-24

Publications (1)

Publication Number Publication Date
WO1983001969A1 true WO1983001969A1 (fr) 1983-06-09

Family

ID=20345107

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1982/000366 Ceased WO1983001969A1 (fr) 1981-11-24 1982-11-04 Procede permettant d'empecher l'obturation d'un dispositif de filtration

Country Status (10)

Country Link
EP (1) EP0096041A1 (fr)
BR (1) BR8207990A (fr)
DD (1) DD204964A5 (fr)
FI (1) FI832665A7 (fr)
GR (1) GR77031B (fr)
IT (1) IT1153071B (fr)
PL (1) PL239164A1 (fr)
PT (1) PT75840B (fr)
SE (1) SE8106985L (fr)
WO (1) WO1983001969A1 (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0281320A3 (fr) * 1987-02-27 1989-05-17 Filtration Limited Méthode pour la filtration de fluides
WO1993025752A1 (fr) * 1992-06-05 1993-12-23 Sunds Defibrator Industries Aktiebolag Epuration de pate a papier
WO2000043590A1 (fr) * 1999-01-25 2000-07-27 J & L Fiber Services, Inc. Systeme et procede de controle pour dispositif de traitement de fibres
US6314381B1 (en) 2000-03-08 2001-11-06 J & L Fiber Services, Inc Refiner measurement system and method
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
US6502774B1 (en) 2000-03-08 2003-01-07 J + L Fiber Services, Inc. Refiner disk sensor and sensor refiner disk
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
US6938843B2 (en) 2001-03-06 2005-09-06 J & L Fiber Services, Inc. Refiner control method and system
US7104480B2 (en) 2004-03-23 2006-09-12 J&L Fiber Services, Inc. Refiner sensor and coupling arrangement
WO2011064458A2 (fr) 2009-11-30 2011-06-03 Andritz Oy Procédé et agencement permettant de commander une salle de classage
US20170021368A1 (en) * 2015-07-24 2017-01-26 Jason D Lalli Filtration System Utilizing Actuated Flow Control Valve
CN113950551A (zh) * 2019-06-14 2022-01-18 福伊特专利有限公司 确定制造纤维料幅的机器的抽吸辊子的污染的方法和装置

Citations (3)

* 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
GB1183426A (en) * 1967-04-15 1970-03-04 K Seven Kk Improvements in or relating to a Strainer
FR2353675A1 (fr) * 1976-06-03 1977-12-30 Tampella Oy Ab Procede et appareil pour le classement d'une suspension

Patent Citations (3)

* 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
GB1183426A (en) * 1967-04-15 1970-03-04 K Seven Kk Improvements in or relating to a Strainer
FR2353675A1 (fr) * 1976-06-03 1977-12-30 Tampella Oy Ab Procede et appareil pour le classement d'une suspension

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0281320A3 (fr) * 1987-02-27 1989-05-17 Filtration Limited Méthode pour la filtration de fluides
WO1993025752A1 (fr) * 1992-06-05 1993-12-23 Sunds Defibrator Industries Aktiebolag Epuration de pate a papier
US6324490B1 (en) 1999-01-25 2001-11-27 J&L Fiber Services, Inc. Monitoring system and method for a fiber processing apparatus
WO2000043590A1 (fr) * 1999-01-25 2000-07-27 J & L Fiber Services, Inc. Systeme et procede de controle pour dispositif de traitement de fibres
US6892973B2 (en) 2000-03-08 2005-05-17 J&L Fiber Services, Inc. Refiner disk sensor and sensor refiner disk
US6502774B1 (en) 2000-03-08 2003-01-07 J + L Fiber Services, Inc. Refiner disk sensor and sensor refiner disk
US6314381B1 (en) 2000-03-08 2001-11-06 J & L Fiber Services, Inc Refiner measurement system and method
US6938843B2 (en) 2001-03-06 2005-09-06 J & L Fiber Services, Inc. Refiner control method and system
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
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
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
US7104480B2 (en) 2004-03-23 2006-09-12 J&L Fiber Services, Inc. Refiner sensor and coupling arrangement
WO2011064458A2 (fr) 2009-11-30 2011-06-03 Andritz Oy Procédé et agencement permettant de commander une salle de classage
US20170021368A1 (en) * 2015-07-24 2017-01-26 Jason D Lalli Filtration System Utilizing Actuated Flow Control Valve
WO2017019309A1 (fr) * 2015-07-24 2017-02-02 Lalli Jason D Système de filtration utilisant une soupape de régulation de débit actionnée
US10610873B2 (en) 2015-07-24 2020-04-07 Jason D Lalli Filtration system utilizing actuated flow control valve
CN113950551A (zh) * 2019-06-14 2022-01-18 福伊特专利有限公司 确定制造纤维料幅的机器的抽吸辊子的污染的方法和装置

Also Published As

Publication number Publication date
SE8106985L (sv) 1983-05-25
PL239164A1 (en) 1983-07-18
IT1153071B (it) 1987-01-14
IT8224316A1 (it) 1984-05-18
BR8207990A (pt) 1983-10-04
IT8224316A0 (it) 1982-11-18
FI832665A0 (fi) 1983-07-22
EP0096041A1 (fr) 1983-12-21
PT75840B (en) 1985-12-09
DD204964A5 (de) 1983-12-14
GR77031B (fr) 1984-09-04
FI832665L (fi) 1983-07-22
PT75840A (en) 1982-12-01
FI832665A7 (fi) 1983-07-22

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