EP0261117B1 - Drehelement für eine siebvorrichtung mit einer profilierten kontur - Google Patents

Drehelement für eine siebvorrichtung mit einer profilierten kontur Download PDF

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Publication number
EP0261117B1
EP0261117B1 EP19860903389 EP86903389A EP0261117B1 EP 0261117 B1 EP0261117 B1 EP 0261117B1 EP 19860903389 EP19860903389 EP 19860903389 EP 86903389 A EP86903389 A EP 86903389A EP 0261117 B1 EP0261117 B1 EP 0261117B1
Authority
EP
European Patent Office
Prior art keywords
plane
screen
rotating element
rotor
vessel
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.)
Expired
Application number
EP19860903389
Other languages
English (en)
French (fr)
Other versions
EP0261117A1 (de
Inventor
Frey Frejborg
Harry Lampenius
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.)
Ahlstrom Corp
Original Assignee
Ahlstrom Corp
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
Priority claimed from US06/738,743 external-priority patent/US4676903A/en
Application filed by Ahlstrom Corp filed Critical Ahlstrom Corp
Priority to AT86903389T priority Critical patent/ATE62945T1/de
Publication of EP0261117A1 publication Critical patent/EP0261117A1/de
Application granted granted Critical
Publication of EP0261117B1 publication Critical patent/EP0261117B1/de
Expired legal-status Critical Current

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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
    • D21D5/16—Cylinders and plates for screens
    • 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
    • D21D5/023—Stationary screen-drums
    • D21D5/026—Stationary screen-drums with rotating cleaning foils

Definitions

  • the present invention relates to an apparatus for screening pulp and more specifically paper pulp.
  • This screening apparatus comprises a vessel, a cylindrical screen within the vessel, provided with grooves: a rotating element moving in the vicinity of the screen at a predetermined speed, the rotating element having a contour surface including a bottom plane and upper plane substantially parallel to the envelope surface of the screen; an inlet to the vessel for the inscreened pulp, and an outlet from the vessel for the screened pulp both in operative communication with the screen.
  • a cylindrical screen plate which has an inlet on one side for introducing the unscreened pulp, and an outlet in the opposite side for removing the reject portion. Means are provided for moving the unscreened pulp along one first direction of flow.
  • the screen plate has grooves in the side of the inlet recessed in the screen surface, the first direction of flow being essentially transverse to the grooves.
  • the grooves are formed of an upstream side plane, a downstream side plane and a bottom plane.
  • the bottom plane is essentially parallel to the envelope surface of the screen plate.
  • the grooves have perforations in the bottom plane.
  • the upstream side plane of the grooves is substantially perpendicular to the envelope surface and the down-stream side plane of the grooves forms an angle of 60°-5° against the envelope surface.
  • the angle between the downstream side plane of the grooves and envelope surface of the screen plate is about 30°. This configuration is called a "contour profile”.
  • pulp is produced by cooking wood which separates the wood into fibers. Due to the different properties of the wood even from the same tree, some of the fibers do not separate and are dispersed as fiber bundles usually called debris, shives or slivers which form the reject. There are also other impurities, such as bark, which must be removed.
  • the screen must separate the undesirable impurities and debris called the rejects from the accept portion. In order to avoid substantial losses of fibres which could be carried over together with the debris in the reject portion, it is necessary to remove the impurities efficiently and selectively.
  • U.S. Patent 3,363,759 and U.S. patent 4,318,805 describe drum rotors with a bumped surface which provides pulsations.
  • the bumps take the form of pins projecting from the rotor with enlarged heads, the heads providing the pulses while the pins offer little resistance to flow.
  • US-A-4,447,320 and US-A-4,200,537 describe rotors which carry blades or vanes moving in the vicinity of the screen which produce a large positive pulse.
  • Other patents describe other types of rotors, for instance US-A-3,726,401 uses a rotor with bumps or protruberances which produce about equal positive and negative pulses. According to this patent, any form of bumps may be used provided it produces the desired pulses, the bumps and the depressions between them creating positive screening and negative screen cleaning pressure pulses.
  • US-A-3,400,820 describes a rotary member made up of a plurality of separate segments joined together and forming a selected undulating pattern which produces about equal positive and negative pulses.
  • US-A-4,202,761 describes an apparatus for sorting fiber suspensions having a screen with holes and having a rotating element provided on the side of the screen with cleaning blades and clearing strips by which the fiber suspension moves downwardly in helical shaped paths within the annular space between the rotating element and the screen.
  • EP-A-0,182,688 in the screen thereof being provided grooves with an inclined side plane and an opposite side plane being provided perpendicularly to the circumference of the screen.
  • the rotating element on the side of the screen is provided with protrusions having an inclined side surface as well as an opposite side surface being perpendicular to the circumference of the rotating element.
  • the object of the present invention is to provide a rotating element which produces pulses which are more effective in keeping the screen from plugging, as compared with rotors which have a curved surface.
  • the rotating element having grooves formed therein by an inclined plane and a side plane between the bottom plane and the upper plane, the side plane being essentially perpendicular to the first plane on one side of the upper plane, and the inclined plane forming an angle between 30°-60° with the bottom plane on the other side of the upper plane.
  • the present invention provides a rotating element which increases the intensity of the pulses generated near the openings, either orifices or slots within the screen plate, for the purpose of creating the negative pulses which are necessary to backwash the screen, and to prevent plugging, thus increasing the flow of the fiber suspension through the openings of the screen. Furthermore a rotating element with very high frequency pulses in addition to sufficient amplitude shall be provided.
  • the rotating element produces sharp and steep negative pulses, thus resulting in high intensity and the power requirements are reduced.
  • the rotor permits to operate with smaller orifices in the screen thus improving the screening efficiency.
  • an accept portion of consistency as close as possible to the consistency of the pulp introduced at the inlet is obtained.
  • Blade type segments are provided to be used instead of a rotor in certain applications in which the continous surface of a rotor is not desirable, for instance when fractionation of the long fibers should be avoided and a larger inlet screening zone is preferable.
  • the rotating hydrofoils produce both negative and positive pulses.
  • the symbol O pressure designates the value of the pressure near the screen surface or the screening zone between the rotating foil and the screen cylinder.
  • the pressure has positive value, which is at maximum at the point A and when it is less than the reference point, the pressure has a negative value, the latter being at a maximum at the point B.
  • the rotating hydrofoils of Fig. 1 known in the art produce pulses illustrated in Fig. 2.
  • the leading surface or nose on the hydrofoil develops a positive pulse with the maximum value or amplitude just about at the minimum clearance point between the foil and the screen.
  • the positive pulse contributes to induce the flow in the screening zone through the apertures within the screen because the flow will always be from a higher pressure zone to a lower pressure zone.
  • a maximum negative pulse is developed due to the change in slope of the foil blade from its minimum clearance position. As shown in Figure 1, the angle of this slope for most foil blades would be a maximum of approximately 30° or even less.
  • the foils or lobe-shaped surfaces or protrusions of rotors and blade type segments known in the art have leading surfaces curved towards the screen cylinder until the minimum rotor clearance point is reached, followed by a trailing surface curving away from the screen. At the minimum rotor clearance point, the change in slope of the curved surface is O. Shortly after this point, the magnitude of the negative pulses starts to increase to a maximum negative value after which the pulses start decreasing again, thus repeating the cycle, as shown in Fig. 2.
  • the crux of the present invention resides in providing a rotor and blade type serpents with grooves, the grooves having a contour surface being formed of a first plane parallel to the envelope surface, an inclined plane, an upper plane and a side plane, the side plane being substantially perpendicular to the first plane and the inclined plane of the grooves forming a 30-60° angle against the first plane, the upper plane being parallel to the first plane. According to a preferred embodiment this angle is about 45°.
  • numeral 1 designates a bottom plane and numeral 2 designates an inclined plane.
  • numeral 3 designates an upper plane and numeral 4 designates a side plane perpendicular to the bottom plane.
  • Numeral 6 designates the envelope surface to the screen.
  • the same numerals 1, 2, 3 and 4 are used to designate the bottom plane, the inclined plane, the upper plane and the side plane which is perpendicular to the bottom plane.
  • the leading surface has a bottom plane 1 parallel to the envelope surface. It then slopes forming inclined plane 2 until it reaches the upper plane 3.
  • the length of the upper plane 3 should be between 0,635 cm (1/4 inches) and 7,62 cm (3 inches).
  • the groove comprises a side plane 4 perpendicular to the first plane 1.
  • the bottom plane 1 may vary from a length of 0 up to 7,62 cm (3 inches).
  • This feature of the side plane 4 being substantially perpendicular to the bottom plane is essential in order to produce pulses which are more effective in keeping the screen from plugging, as compared with rotors which have a curved surface.
  • Figure 4 illustrates the pulses from a rotating element having the contour profile according to the present invention.
  • a very sharp negative pulse is produced by the 90° angle in the rotor surface or in the blade type segments. This is due to the rapid change in the flow path of the fluid coupled with a Bernouilli effect caused by the increasing velocity of the fluid within the minimum rotor or blade type segment clearance point. This severe or rapid change in pulsation makes the rotor or the blade type segment more effective in back-flushing the screen cylinder 11.
  • the explanation for this effect is that the maximum velocity and acceleration of the fluid which goes through the apertures during back-flushing must be greater than with conventional pulse producing rotating elements because the change in pulses or amplitude with time is much greater with a contour surface (see Fig. 4a).
  • intensity of the pulses within the scope of the present invention is intended to mean the change of amplitude of the pulses per unit time. To state the matter in different words, the intensity is not merely the result of the amplitude but also depends on the fast and sharp change.
  • the intensity factor, IF is the ratio of the change of amplitude over the unit of time: ⁇ amplitude ⁇ time (Figs. 7 and 7a).
  • Figure 4 when compared with Figure 2 shows the superiority of the rotating element of the present invention with the contour surface with respect to conventional rotors or conventional blade type elements. Further, the slope and leading surfaces of the contour rotating elements produce positive pulses which help in inducing the flow of the fibrous suspension through the apertures within the screen.
  • the upper surface 3 is needed just ahead of the side plane 4 to cause the rapid change in pulsation.
  • Figure 5 illustrates the embodiment in which a large screening zone with a substantial open area is desirable to allow inlet stock to enter the full screening zone, thus minimizing the concentration of the long fibers in the reject and minimizing the consistency of the reject, so that more long fibers are in the accept.
  • blade type segments are used with a contour surface.
  • the contour surface of the rotating element, a rotor or blade type segments according to the present invention provides high frequency pulsations. For instance, with a rotating speed of 600, it is possible to achieve a pulsation frequency of 200 Hz and even higher.
  • the high frequency is advantageous because there is less tendency for the fibers to plug the openings and due to the fact that the pulses also exhibit sufficient amplitude, back-flushing occurs.
  • the higher frequency permits the screen to handle stock of higher concentration.
  • FIG. 7a shows the superiority in intensity factor achieved by the rotating element according to the present invention as compared with a conventional rotating element.
  • Figure 8 the pulse profile of a conventional hydrofoil is shown in broken line and the pulse profile of a rotor with the contour surface according to the present invention is shown in solid line.
  • the rotor as shown in Fig. 3 and the blade type segment shown in Fig. 5 may be used with conventional screen plates and also in conjunction with the screen plate having a contour profile according to US-A-4 529 520 as shown in Fig. 6.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)

Claims (6)

1. Siebvorrichtung für Pulpe bestehend aus;
einem Behälter; und einem zylindrischen Sieb (10) innerhalb des Behälters, welches Sieb mit Rillen versehen ist;
einem rotierenden Element (7), das sich mit einer vorherbestimmten Geschwindigkeit in der Nähe des Siebs (10) bewegt, welches rotierende Element eine konturierte Oberfläche hat, die eine Grundfläche (1) und eine obere Fläche (3) umfaßt, die im wesentlichen parallel zur Mantelfläche des Siebs (10) sind;
einem Eintritt in den Behälter für ungesiebte Pulpe, und einem Austritt aus dem Behälter für gesiebte Pulpe, die beide betriebsmäßig mit dem Sieb (10) verbunden sind, dadurch gekennzeichnet, daß das rotierende Element (7) Rillen hat, die darin durch eine geneigte Fläche (2) und eine Seitenfläche (4) zwischen der Grundfläche (1) und der oberen Fläche (3) gebildet sind, welche Seitenfläche (4) im wesentlichen senkrecht zur ersten Fläche (1) auf der einen Seite der oberen Fläche (3) ist und die geneigte Fläche (2) einen Winkel zwischen 30° und 60° mit der Grundfläche (1) auf der anderen Seite der oberen Fläche (3) bildet.
2. Vorrichtung gemäß Anspruch 1, worin das genannte rotierende Element (7) ein Läufer ist.
3. Vorrichtung gemäß Anspruch 1, worin das genannte rotierende Element (7) aus blattförmigen Segmenten (9) besteht.
4. Vorrichtung gemäß Anspruch 1, worin der Winkel zwischen der genannten geneigten Fläche (2) und der genannten Grundfläche (1) rund 45° ist.
5. Vorrichtung gemäß Anspruch 1, worin die genannte Grundfläche (1) von 0 bis 7,62 cm (0 bis 3 Zoll) Länge ist.
6. Siebvorrichtung gemäß Anspruch 2, worin der genannte Läufer sich über die Siebfläche erstreckt.
EP19860903389 1985-05-29 1986-05-19 Drehelement für eine siebvorrichtung mit einer profilierten kontur Expired EP0261117B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86903389T ATE62945T1 (de) 1985-05-29 1986-05-19 Drehelement fuer eine siebvorrichtung mit einer profilierten kontur.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/738,743 US4676903A (en) 1983-01-26 1985-05-29 Screening apparatus
US738743 1985-05-29

Publications (2)

Publication Number Publication Date
EP0261117A1 EP0261117A1 (de) 1988-03-30
EP0261117B1 true EP0261117B1 (de) 1991-04-24

Family

ID=24969298

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860903389 Expired EP0261117B1 (de) 1985-05-29 1986-05-19 Drehelement für eine siebvorrichtung mit einer profilierten kontur

Country Status (7)

Country Link
EP (1) EP0261117B1 (de)
JP (1) JPS62503109A (de)
BR (1) BR8607123A (de)
CA (1) CA1275973C (de)
DE (1) DE261117T1 (de)
FI (1) FI77481C (de)
WO (1) WO1986007105A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018006809A1 (zh) * 2016-07-05 2018-01-11 李�昊 一种筛选疏解机

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BR8807561A (pt) * 1987-06-11 1990-04-17 Ahlstroem Oy Aparelho de peneiramento de polpa
KR890701835A (ko) * 1987-06-26 1989-12-21 스벤 웨스터홀름, 카제 헨릭슨 펄프 스크리닝 장치 및 펄프 현탁액의 스크리닝 방법
DE58907372D1 (de) * 1988-03-07 1994-05-11 Escher Wyss Gmbh Druck-Knotenfänger-Sortierapparat.
JPH0880405A (ja) * 1994-09-14 1996-03-26 Shinko Kk 濾過装置
JP4514009B2 (ja) * 2001-03-28 2010-07-28 株式会社Ｉｈｉ機械システム スクリーン装置
WO2007094967A1 (en) * 2006-02-16 2007-08-23 Kadant Black Clawson Inc. Pulb screen foil and method of use
DE102011007280A1 (de) 2011-04-13 2012-10-18 Krones Aktiengesellschaft Behälterbehandlungsmaschine und Verfahren zur Behälterbehandlung
DE102011079078A1 (de) 2011-07-13 2013-01-17 Krones Ag Einsternzuführung für Behandlungsmaschinen
WO2013175078A1 (en) * 2012-05-25 2013-11-28 Aikawa Fiber Technologies Oy A rotor element and a rotor for a screening apparatus
CN106381746B (zh) * 2016-11-18 2019-05-31 广西大学 一种压力筛转子旋翼

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2712749A1 (de) * 1977-03-23 1979-02-08 Finckh Maschf Sortierer zum sichten von fasersuspensionen
DE2712715B2 (de) * 1977-03-23 1979-05-23 Hermann Finckh Maschinenfabrik Gmbh & Co, 7417 Pfullingen Sortierer für Fasersuspensionen
FR2572950B1 (fr) * 1984-11-12 1987-01-23 Lamort E & M Perfectionnements aux tamis pour epurateurs et a leur mode de fabrication

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018006809A1 (zh) * 2016-07-05 2018-01-11 李�昊 一种筛选疏解机

Also Published As

Publication number Publication date
BR8607123A (pt) 1988-02-23
FI853373A0 (fi) 1985-09-03
DE261117T1 (de) 1989-07-13
WO1986007105A1 (en) 1986-12-04
FI853373L (fi) 1986-11-30
JPS62503109A (ja) 1987-12-10
FI77481C (fi) 1989-03-10
FI77481B (fi) 1988-11-30
EP0261117A1 (de) 1988-03-30
CA1275973C (en) 1990-11-06

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