US3034650A - Method and apparatus for screening pulp - Google Patents

Method and apparatus for screening pulp Download PDF

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Publication number
US3034650A
US3034650A US824732A US82473259A US3034650A US 3034650 A US3034650 A US 3034650A US 824732 A US824732 A US 824732A US 82473259 A US82473259 A US 82473259A US 3034650 A US3034650 A US 3034650A
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Prior art keywords
pulp
screen
screening
rejects
diaphragm
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Expired - Lifetime
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US824732A
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English (en)
Inventor
Henry F Szepan
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Individual
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Individual
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Priority to US824732A priority Critical patent/US3034650A/en
Priority to SE8239/59A priority patent/SE300176B/xx
Application granted granted Critical
Publication of US3034650A publication Critical patent/US3034650A/en
Anticipated expiration legal-status Critical
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    • 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
    • D21D5/06—Rotary screen-drums

Definitions

  • the present invention differs from the foregoing in that it is adaptable throughout the pulp screening range from a knotter, handling the coarsest pulp to the finest classification of acceptable fibre. Emphasis cannot be too great on the fact that the behaviour of pulp screens is the least predictable of all operations in the paper making process, which still remains after centuries, more an art than a science.
  • An object of this invention is to provide a pulp screen which, in its fundamental design will accomplish at a single pass, both primary and secondary screening.
  • FIGURE 1 is a front elevation vertically sectioned
  • FIGURE 2 is a plan view of the rotor shown in FIG- URE 1;
  • FIGURE 3 is a section on the line 3-3 of FIGURE 2.
  • the Rich-Luthi application improved on the Bowen patent by providing a volute entryway for the pulp, plus a pitched blade stator to direct the incoming pulp in the same rotational direction as that of the rotor.
  • the rot-or blades are pitched to feed the pulp 3,li34,650 Patented May 15, 1962 7 toward the rejects end and are sloped relative to the radii to provide in combination, increased centrifugal force on the stock plus a cavitation efiect which serves to clean the screen.
  • the central or median baffle ofiers a dividing line or plane between primary and secondary screening.
  • the present invention improves upon the foregoing by reversing the pitch of the rotor blades on the trailing side of the baffle and by moving the baffle from its heretofore median position to a plane nearer the rejects outlet.
  • This provides a longer period of primary screening with increased retention period in the secondary phase.
  • the result is to permit greater inlet consistency and greater rejects consistency, the latter being due to the longer retention in the secondary phase so that less dilution water is necessary.
  • capacity is increased with minimum volume of over-run.
  • FIGURE 1 there is shown a screen casing 10 in which is mounted a fixed screen 12.
  • the casing 10 has a volute inlet 14 as disclosed in the Rich- Luthi application aforesaid. Adjacent the volute inlet 14- is a stator 16 for converting the inlet velocity head to a swirling action.
  • a shaft 18 penetrates the casing 10 through stuffing boxes 20 and bearings 22. Acceptable stock passes through the screen 12 and emerges through an outlet in casting 24. Rejected stock emerges through an outlet 26. Dilution water is supplied through a shower pipe 27.
  • a diaphragm 2.8 is keyed to the shaft 18 and carries rotor blades 34 which receive additional support from rings 32.
  • rotor blades 34 On at least two diametrically opposed rotor blades 30 are afiixed paddles or agitators 34 which serve to clear the entrance of the rejects outlet 26.
  • diaphragm 28 and the rings 32 are each made in two parts which are bolted together, diaphragm 28 as shown at 36 and the rings 32 as shown at 38.
  • each blade 30 has a r versally helicoidally pitched portion 39'.
  • the diaphragm 28 instead of being at the median point of the rotor is approximately three fourths of the Way from the inlet to the rejects outlet.
  • the reverse pitch portions 30 are cantilevers not supported by a ring 32.
  • the number of blades and the speed of rotation depend on the nature of the stock and the size and number of the perforations in the screen 12.
  • the perforations are between 716 inch and /2 inch in diameter.
  • ten blades with a negative pitch of 30 degrees of the portions 30 was found to give optimum performance at 350 rpm.
  • a method of screening pulp comprising: advancing a pulp slurry along a helicoidal path within a cylindrical screen; constricting the path at a predetermined plane; reopening the path and simultaneously diluting the slurry, and, during such dilution, retarding the aXial progress of the slurry.
  • Apparatus for screening pulp comprising: a horizontal, cylindrical screen; a rotor inside said screen; a diaphragm on said rotor; blades attached to said diaphragm, said blades heing pitched in opposite directions on opposite sides of said diaphragm.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
US824732A 1959-07-02 1959-07-02 Method and apparatus for screening pulp Expired - Lifetime US3034650A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US824732A US3034650A (en) 1959-07-02 1959-07-02 Method and apparatus for screening pulp
SE8239/59A SE300176B (enrdf_load_stackoverflow) 1959-07-02 1959-09-05

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US824732A US3034650A (en) 1959-07-02 1959-07-02 Method and apparatus for screening pulp

Publications (1)

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US3034650A true US3034650A (en) 1962-05-15

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US824732A Expired - Lifetime US3034650A (en) 1959-07-02 1959-07-02 Method and apparatus for screening pulp

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US (1) US3034650A (enrdf_load_stackoverflow)
SE (1) SE300176B (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4238324A (en) * 1978-11-21 1980-12-09 J. M. Voith Gmbh Apparatus for separating impurities from fiber suspensions
US4374728A (en) * 1981-07-29 1983-02-22 Gauld W Thomas Apparatus for screening fibrous stock
US4680108A (en) * 1985-03-04 1987-07-14 Kamyr Ab Screening device
US5679250A (en) * 1993-02-10 1997-10-21 Sunds Defibrator Industries Aktiebolag Pressurized screen arrangement
EP1130156A3 (de) * 2000-03-04 2003-11-05 Verwaltungs Lohse GmbH & Co. KG Vorrichtung zum Abtrennen von Störstoffen aus faserhaltigem Gut
WO2014084788A1 (en) 2012-11-28 2014-06-05 Metso Paper Sweden Ab Screening apparatus, rotor, wing package and method for manufacture

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2380321A (en) * 1941-10-03 1945-07-10 Henry G Lykken Pulverizing and classifying apparatus
US2752828A (en) * 1951-09-11 1956-07-03 Waterous Ltd Screen for paper stock
US2835173A (en) * 1955-03-03 1958-05-20 Black Clawson Co Paper machinery
US2845848A (en) * 1956-01-23 1958-08-05 North Carolina Pulp Company Apparatus for screening pulp
US2908390A (en) * 1958-01-28 1959-10-13 John P Rich Apparatus for screening pulp

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2380321A (en) * 1941-10-03 1945-07-10 Henry G Lykken Pulverizing and classifying apparatus
US2752828A (en) * 1951-09-11 1956-07-03 Waterous Ltd Screen for paper stock
US2835173A (en) * 1955-03-03 1958-05-20 Black Clawson Co Paper machinery
US2845848A (en) * 1956-01-23 1958-08-05 North Carolina Pulp Company Apparatus for screening pulp
US2908390A (en) * 1958-01-28 1959-10-13 John P Rich Apparatus for screening pulp

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4238324A (en) * 1978-11-21 1980-12-09 J. M. Voith Gmbh Apparatus for separating impurities from fiber suspensions
US4374728A (en) * 1981-07-29 1983-02-22 Gauld W Thomas Apparatus for screening fibrous stock
US4680108A (en) * 1985-03-04 1987-07-14 Kamyr Ab Screening device
US5679250A (en) * 1993-02-10 1997-10-21 Sunds Defibrator Industries Aktiebolag Pressurized screen arrangement
EP1130156A3 (de) * 2000-03-04 2003-11-05 Verwaltungs Lohse GmbH & Co. KG Vorrichtung zum Abtrennen von Störstoffen aus faserhaltigem Gut
WO2014084788A1 (en) 2012-11-28 2014-06-05 Metso Paper Sweden Ab Screening apparatus, rotor, wing package and method for manufacture
CN104769181A (zh) * 2012-11-28 2015-07-08 维美德公司 筛选设备、转子、翼型封装和制造方法
EP2925927A4 (en) * 2012-11-28 2016-07-06 Valmet Oy SIEVE APPARATUS, ROTOR, WING ASSEMBLY, AND METHOD FOR MANUFACTURING
US9410286B2 (en) 2012-11-28 2016-08-09 Valnet AB Screening apparatus, rotor, wing package and method for manufacture
CN104769181B (zh) * 2012-11-28 2016-08-24 维美德公司 筛选设备、转子、翼型封装和制造方法

Also Published As

Publication number Publication date
SE300176B (enrdf_load_stackoverflow) 1968-04-08

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