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WO1996032203A1 - Appareil de criblage des copeaux de bois a lames a bord superieur non lineaire - Google Patents

Appareil de criblage des copeaux de bois a lames a bord superieur non lineaire Download PDF

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Publication number
WO1996032203A1
WO1996032203A1 PCT/US1996/006064 US9606064W WO9632203A1 WO 1996032203 A1 WO1996032203 A1 WO 1996032203A1 US 9606064 W US9606064 W US 9606064W WO 9632203 A1 WO9632203 A1 WO 9632203A1
Authority
WO
WIPO (PCT)
Prior art keywords
blades
improvement
nonlinear
top edges
chips
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/US1996/006064
Other languages
English (en)
Inventor
Gevan R. Marrs
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.)
Weyerhaeuser Co
Original Assignee
Weyerhaeuser Co
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 Weyerhaeuser Co filed Critical Weyerhaeuser Co
Priority to AU56347/96A priority Critical patent/AU5634796A/en
Priority to EP96913295A priority patent/EP0820354A1/fr
Publication of WO1996032203A1 publication Critical patent/WO1996032203A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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
    • D21D5/04—Flat screens
    • D21D5/043—Vibrating screens
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
    • B07B1/12—Apparatus having only parallel elements
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/02—Pretreatment of the raw materials by chemical or physical means
    • D21B1/023—Cleaning wood chips or other raw materials

Definitions

  • This invention relates generally to sorting wood chips prior to a pulping operation where an incoming flow of chips has a portion with chips of acceptable thickness and a portion of unacceptable thickness. More particularly it relates to a wood chip sorting device where elongated spaced apart reciprocating blades allow chips of an acceptable thickness to pass therebetween while the overthick chips are conveyed atop the blades to the outfeed end.
  • Chip sorting machines utilizing elongated parallel blades or bars that reciprocate are well known and are presently used in chip sizing and sorting operations throughout the world. It is known that the digesting stage of wood pulp manufacture is particularly sensitive to the thickness parameter of incoming chips. For that reason chip "screening" is an important process step upstream of the pulp mill. For example, for typical North American softwood species, it has been determined that wood chip process overall economics are most favorable when the thickness falls within a range of from 7-9 mm. In the recent past both disk screens and bar screens have been utilized by industry to sort incoming chips according to thickness. Disk screens have been installed but tend to be relatively difficult to maintain and are expensive. Blade or bar screens have become more popular in the past few years.
  • Blade screens are designed to provide a high capacity (chips by weight or unit volume per hour per unit area of screen surface) processing system while reducing the number of acceptable chips remaining within the unacceptable portion flowing past the outfeed end.
  • An example of the important considerations can be reviewed by referring to U.S. Patent 5,368,168 in the name of Marrs et al., which disclosure is incorporated herein by reference.
  • This patent discloses a staggered height feature for the bars or blades whereby chips are tipped up by the action of the bars so the thickness dimension tends to be presented more effectively to the openings between the bars. Such enhanced tipping causes more chips with an acceptable thickness to fall between bars thereby increasing screening efficiency.
  • Another U.S. Patent, No. 5,305,891 also discloses a similar screening system for sizing and sorting wood chips.
  • two sets of interleaved bars are driven at 200-250 rpm and have the bars in at least one of the sets at variable heights, i.e. non-coplaner. All of the top edges on each of the bars are, however, linear and parallel with on another. It is further stated that the individual bars should be one- half inch in thickness and one and one-half to three inches in height from top to bottom. During operation bar displacement on the order of 1 " is preferred.
  • a set of elongated reciprocating screening blades should function to cause, as quickly as possible, as many of the chips to be tipped so as to present the thickness dimension to slots between blades while simultaneously motivating the overthick chips atop the blades toward the outfeed end.
  • tipping of chips can be effectuated by blades having a staggered height thereby allowing larger relative displacements between adjacent blades than vertical reciprocation alone provides.
  • the invention is a wood chip screening system having parallel spaced apart blades or bars which are mounted for reciprocating motion in a vertical and horizontal plane with the improvement comprising a portion of the elongated top edges of the blades having a nonlinear configuration.
  • Fig. 1 is a perspective view of a blade screen apparatus in a commercial environment.
  • Fig. 2 is a perspective view of a portion of the blade screen of the present invention, showing a particular nonlinear blade configuration.
  • Figs. 3-7 illustrate alternative nonlinear configurations for the top edges in a blade screen of the present invention.
  • Fig. 1 illustrates a typical bar or blade screen apparatus for sorting wood chips.
  • the screen apparatus referred to generally at 10 is positioned on a base support assembly 12 which in Fig. 1 supports the screen apparatus 10.
  • the screen apparatus could be positioned at various angles, either inclining downwardly or upwardly in the direction of the outfeed end, or it could be flat.
  • the screen itself will be approximately ten feet long, with a selected width. In commercial embodiments, the widths typically will be 6V-., 8V_ or 10 feet.
  • the screen apparatus will typically include two sets of interleaved blades, with each set being driven separately but such that the blades in one set have a selected spatial relationship with the blades in the other set.
  • An example of such a screen with two sets of interleaved blades is shown in U.S. Patent Nos. 5,117,983 to Marrs and 5,368,168 to Marrs et al., assigned to the same assignee as the present invention, the contents of which are hereby incorporated by reference.
  • one set of blades is supported at the respective ends thereof by end support assemblies 14 and 16, while the other set of blades is supported by end support assemblies 19 and 20.
  • the end support assemblies shown in Fig. 1 are adapted specifically to maintain each individual blade under tension. Such a system is necessary, for instance, where the elements are relatively thin and would otherwise twist or bend significantly in operation.
  • Such a tension type bar screen and its supporting elements are shown in more detail in U.S. Patent No. 5,284,251 to Marrs, assigned to the same assignee as the present invention, the contents of which are hereby incorporated by reference.
  • the two sets of interleaved blades in the apparatus of Figure 1 are driven by a drive mechanism 22, which is positioned near the infeed end 24 of the screen apparatus.
  • the drive mechanism 22 operates from a motor via gears, drive shaft and eccentrics to flange elements which connect to the support frames in which the respective two sets of blades are mounted.
  • the driving action is also transmitted to the outfeed end of the support frames by means of a belt assembly and pulley arrangement shown generally at 26.
  • the two sets of interleaved blades are operated at a relatively high speed, within the range of 200-350 rpm, with the movement of one set of blades being approximately 180° behind the blades in the other set.
  • Wood chips from a loaded hopper or other container are loaded onto screen 10 at infeed end 24, shown diagrammatically in Fig. 1.
  • the wood chips are bounced around by the action of the interleaved screens, with the individual chips being tipped up so that their thickness dimension is presented to the openings between the blades.
  • Those chips having a thickness dimension less than the opening size between adjacent blades will fall through the screen to a conveyor 32 which moves those acceptable size chips to a predetermined location for storage or processing into pulp or other use.
  • Those chips which have a thickness dimension larger than the screen openings or which for some reason where not tipped properly so as to present their thickness dimension to the openings eventually move off the outfeed end 28 of the screen to another conveyor 34 which moves those chips to another station for further size processing, such as to an apparatus known as a chip slicer, or similar device, which reduces the thickness of the chips.
  • the chips from the chip slicer are then typically added directly to the acceptable chip flow but could be returned to the screen. The above process continues as long as chips are loaded onto the screen.
  • the invention described in the '168 patent is designed to significantly improve bar screen loading capacity, particularly for those screens which use relatively thin blades.
  • the invention includes two sets of interleaved blades, similar to a conventional bar screen. In the '168 patent description, however, selected ones of the blades/bars in each set are higher than the remainder of the blades, i.e., the blades present a "staggered" appearance over at least a portion, if not all, of their length.
  • the present invention incorporating a nonlinear configuration for the top edges of the blades, has been found to increase capacity even further, thus allowing a smaller overall size for the screening apparatus.
  • the present invention can be incorporated into a staggered height blade screen or into one which does not utilize any height differential.
  • Each set of blades has a plurality of spaced apart individual thin blades, indicated at 40 and 42 respectively in each sent, where each set is mounted in the typical reciprocatable frame.
  • each set is mounted in the typical reciprocatable frame.
  • blades 40 and 42 have nonlinear top edges.
  • a preferred configuration is a cyclic, smooth repeating pattern such as a "sinusoidal wave" having peaks and valleys with sloping edges therebetween.
  • the blades are substantially in lateral alignment where the peaks of adjacent blades are aligned In the other set with blades 42 they, too, are substantially in lateral alignment; however, the peaks in this set are longitudinally spaced from the peaks in the first set. It has been determined that a satisfactory amplitude ("peak to valley") for the wave like nonlinear pattern is 1.0 inch, which can vary with satisfactory results from 0.50"-2.0". A satisfactory frequency (linear distance between repeating cyclic patterns) can be four cycles/foot of blade length with an acceptable range being from one cycle to about six cycles per foot on blade length. It is also possible to utilize a non-uniform pattern, i.e.
  • the chip agitation can be altered according to the relative proportion of the chip feed that remains on the screen surface at a particular location down the length of the screen.
  • the linear top edges could have staggered heights as disclosed in the '168 patent.
  • the blades 40, 42 within their respective sets could have their peaks and valleys offset longitudinally so each nonlinear pattern would begin at a different point in the cycle.
  • the other set of blades which would likewise have offset peaks and valleys
  • a very large number of relatively large vertical difference in heights of adjacent blades result in many locations on the screening surface.
  • these locations change, causing not only the desired "tipping" action due to the cycling height differences between adjacent and near adjacent blades but the nonlinear configuration results in a certain "uphill down-hill” agitation beneath the mat of chips.
  • Such an action will induce differences in the length-wise flow rate for adjacent portions of the chip mat.
  • This action has the effect of upsetting the chip mat coherence which leads directly to a higher level of chip thickness exposure to the blade openings and passage of acceptable chips therethrough over a shorter overall length of screening apparatus.
  • FIG. 3 illustrates a "sinusoidal-like" pattern but one with a variable frequency and amplitude.
  • the blade sets with such a pattern would have their peaks and valleys offset in order to produce vertical displacements between adjacent blades larger than the amplitude of reciprocation of the screen apparatus; for example, for a 1.0" difference in height (peak to valley) and with a 1.0" vertical height of reciprocation gives a maximum 2.0" relative displacement at extremes of travel.
  • Alternatives could hold one or the other characteristic constant while varying the other.
  • Fig. 4 illustrates a triangular shaped wave pattern where again the blades in each blade set would be offset. Similar variations would be workable alternate embodiments.
  • Fig. 5 illustrates a rectangular tooth configuration
  • Fig. 6 illustrates a saw tooth configuration
  • Fig. 7 illustrates a trapezoidal configuration; all having the workable alternates, either varying frequency, amplitude or both. All such alternative patterns, where a large relative height difference occurs frequently throughout reciprocation over at least a portion of the length of at least some of the laterally spaced apart blades in the blade sets will accomplish the desired result.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Combined Means For Separation Of Solids (AREA)
  • Preliminary Treatment Of Fibers (AREA)
  • Paper (AREA)

Abstract

Appareil de criblage des copeaux de bois comprenant une extrémité d'alimentation et une extrémité de décharge et entre elles de longues lames fines (40, 42) à mouvement alternatif. Les lames (40, 42) sont séparées par des intervalles permettant le passage des copeaux de l'épaisseur acceptable voulue. L'amélioration porte sur le bord supérieur des lames (40, 42) d'une configuration non linéaire.
PCT/US1996/006064 1995-04-12 1996-03-25 Appareil de criblage des copeaux de bois a lames a bord superieur non lineaire Ceased WO1996032203A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU56347/96A AU5634796A (en) 1995-04-12 1996-03-25 Wood chip screening apparatus with blades having nonlinear top edges
EP96913295A EP0820354A1 (fr) 1995-04-12 1996-03-25 Appareil de criblage des copeaux de bois a lames a bord superieur non lineaire

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US42219095A 1995-04-12 1995-04-12
US08/422,190 1995-04-12

Publications (1)

Publication Number Publication Date
WO1996032203A1 true WO1996032203A1 (fr) 1996-10-17

Family

ID=23673767

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/006064 Ceased WO1996032203A1 (fr) 1995-04-12 1996-03-25 Appareil de criblage des copeaux de bois a lames a bord superieur non lineaire

Country Status (4)

Country Link
EP (1) EP0820354A1 (fr)
AU (1) AU5634796A (fr)
CA (1) CA2215845A1 (fr)
WO (1) WO1996032203A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2376220A1 (es) * 2010-06-16 2012-03-12 Tecnoligra, S.L. Máquina desramadora para instalaciones de limpieza de frutos arbóreos.
KR20210023554A (ko) * 2019-08-23 2021-03-04 한국지질자원연구원 기류 형성 망 및 이를 포함하는 비중 선별 장치

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3064812A (en) * 1956-07-28 1962-11-20 Wehner Albert Pervious surface
SU1058639A1 (ru) * 1982-04-15 1983-12-07 Калининский Ордена Трудового Красного Знамени Политехнический Институт Устройство дл сепарации сыпучего материала
WO1986006659A1 (fr) * 1985-05-03 1986-11-20 Hein, Lehmann Ag Procede et dispositif de criblage de materiaux fragmentes
US4660726A (en) * 1983-06-15 1987-04-28 Rudolf Woode Bar screen
WO1991001816A1 (fr) * 1989-08-07 1991-02-21 Weyerhaeuser Company Ecran a barre ayant une action alternative
US5368168A (en) * 1993-04-26 1994-11-29 Weyerhaeuser Co. Bar screen with bars of staggered height

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3064812A (en) * 1956-07-28 1962-11-20 Wehner Albert Pervious surface
SU1058639A1 (ru) * 1982-04-15 1983-12-07 Калининский Ордена Трудового Красного Знамени Политехнический Институт Устройство дл сепарации сыпучего материала
US4660726A (en) * 1983-06-15 1987-04-28 Rudolf Woode Bar screen
WO1986006659A1 (fr) * 1985-05-03 1986-11-20 Hein, Lehmann Ag Procede et dispositif de criblage de materiaux fragmentes
WO1991001816A1 (fr) * 1989-08-07 1991-02-21 Weyerhaeuser Company Ecran a barre ayant une action alternative
US5117983A (en) * 1989-08-07 1992-06-02 Weyerhaeuser Company Bar screen having a reciprocating action
US5368168A (en) * 1993-04-26 1994-11-29 Weyerhaeuser Co. Bar screen with bars of staggered height

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SOVIET INVENTIONS ILLUSTRATED Section PQ Week 8432, 19 September 1984 Derwent World Patents Index; Class P43, AN 84-199752, XP002009250 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2376220A1 (es) * 2010-06-16 2012-03-12 Tecnoligra, S.L. Máquina desramadora para instalaciones de limpieza de frutos arbóreos.
KR20210023554A (ko) * 2019-08-23 2021-03-04 한국지질자원연구원 기류 형성 망 및 이를 포함하는 비중 선별 장치
KR102301930B1 (ko) * 2019-08-23 2021-09-15 한국지질자원연구원 기류 형성 망 및 이를 포함하는 비중 선별 장치

Also Published As

Publication number Publication date
EP0820354A1 (fr) 1998-01-28
CA2215845A1 (fr) 1996-10-17
AU5634796A (en) 1996-10-30

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