CA2186328C - Blade for a screening apparatus - Google Patents
Blade for a screening apparatus Download PDFInfo
- Publication number
- CA2186328C CA2186328C CA002186328A CA2186328A CA2186328C CA 2186328 C CA2186328 C CA 2186328C CA 002186328 A CA002186328 A CA 002186328A CA 2186328 A CA2186328 A CA 2186328A CA 2186328 C CA2186328 C CA 2186328C
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- CA
- Canada
- Prior art keywords
- blade
- blade assembly
- zone section
- base body
- assembly
- 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 - Fee Related
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Classifications
-
- 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
- B07B1/18—Drum screens
- B07B1/20—Stationary drums with moving interior agitators
-
- 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
Abstract
A blade for a screening apparatus, especially for fiber suspensions during pulping, has an outer contour profile adjacent a facing screen wall to form in fluid flow direction a suction zone section of increasing width of the blade and a pressure zone section of decreasing width of the blade, whereby the length of the suction zone section and the length of the pressure zone section together form the overall length of the blade, and whereby the outer contour profile exhibits a continuous configuration also in a transition area between the suction zone section and pressure zone section.
Description
BACKGROUND OF THE INVENTION
7 The present invention refers to a blade for a screening apparatus, 8 especially for fiber suspensions during pulping.
European Pat. No. EP-A-O 275 921 describes a blade for a screen with 11 drum-like base body. The blade includes in the meridian section a steadily 12 increasing cross section in direction of rotation and terminates in a steep edge.
13 Joined to the steep edge in direction of rotation is a prolongation which has a 14 cross section decreasing in direction of rotation and exhibits a flute. The area of increasing cross section forms a suction zone in conjunction with a screen wall 16 that surrounds the drum-shaped base body, and the area of decreasing cross 17 section forms a pressure zone in conjunction with the screen wall. The 18 contoured outer surface of the blade exhibits a steep edge at the transition 19 between the area of increasing cross section and the area of decreasing cross section, resulting in a sudden directional change that can cause a pressing of 21 impurities in the area of the pressure zone through the perforations of the screen 22 wall so that the screening quality is adversely affected. The profile of the blade 1 conducts the material stream directly towards the perforations which are thus 2 subject to a considerable hydraulic load, risking a slight shift of the screen. The 3 provision of a flute and the sudden directional change cause strong pulsation 4 which results in swirling in the material stream, and may lead especially at increasing material density to fiber accumulations at the blade. This may lead to 6 malfunction of the screen, especially when the screening surface becomes 7 plugged. The sharp edge between the increasing cross sectional area and the 8 decreasing cross sectional area leads to a relatively high flow residence in the 9 material stream through the blade so that this conventional screening apparatus has to run at relatively high speeds, resulting in a relatively high energy 11 consumption during operation.
13 U.S. Pat. No. 4,676,903 discloses a screening apparatus for screening 14 and purification of pulp, and includes a rotor which has a contoured surface with grooves which are formed by a first plane parallel to the envelope surface, an 16 inclined plane, an upper plane and a side plane, with the side plane extending 17 essentially perpendicular to the first plane. This profile of the groove also results 18 in the formation of a steep edge between the pressure zone and the suction 19 zone during rotating rotor. This conventional screening apparatus thus has basically the same drawbacks as the screening apparatus according to 21 European Pat. No. 0 275 921. Fiber bundles and slivers may form on the 22 protruding areas as a result of the steep edges, leading to malfunction of the 1 screening apparatus and/or to a decreasing efficiency of the screening 2 operation. Further disclosed in this patent is a blade, often referred to as 3 hydrofoil, which is so constructed that a maximum pressure pulse is gener-4 ated by the leading surface of the blade at the narrowest clearance point towards the screening basket. This patent desires to generate and to sustain 6 over a long period very high frequency pulses. This, however, creates 7 undesired pressure pulsations.
8 The publication "Weekly Gazette for Paper Manufacturing, No. 17, 9 1988, Pages 733-737 discloses an article by D. Egelhof, entitled "The 1o Vertical sifter pulsating arms - bases, development, results", setting forth 11 that optimization of the blade profile can produce an attenuation of the 12 pressure oscillations emanating from a vertical sifter. This publication fails 13 to present particulars and only refers to the arrangement of the blades at the 14 rotor to effect a reduction of the pressure oscillations.
German Pat. No. 28 30 386 C2 and International patent specifica-16 tion W090/05807 describe screening apparatuses which include a rotor 17 carrying on its outer circumference cleaning and screening elements in 18 protruding disposition. This protruding attachment also results in formation 19 of fiber bundles and slivers as well as dead zones and shives because the cleaning elements exert an adverse effect upon the area of the material 21 stream. The annular gap .,.
1 between the screen wall and the rotor is narrowed by the jutting height of the 2 cleaning elements and engagement elements. When exhibiting only a slight 3 clearance between the apex of the cleaning element and the screen wall 4 surface, the material being treated may be subject to a significant thickening at this greatly constricted annular gap. This results to malfunction of the screening 6 apparatus. If, on the other hand, the rotor is positioned at a greater clearance 7 from the screen wall, then, the rotor speed must be raised so that the energy 8 consumption of the screening apparatus is increased.
SUMMARY OF THE INVENTION
12 It is an object of the present invention to provide an improved blade for a 13 screening apparatus, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an 16 improved blade for use in a screening apparatus, to keep the screen free from 17 impurities, to prevent thickening effects and pulsations while effecting a 18 sufficient fluidization of the material been screened mainly through creation of 19 turbulences.
21 It is yet another object of the present invention to provide an improved 22 blade for a screening apparatus, which is particularly suitable for fiber õ,.
zi863*213 1 suspensions during pulping and accomplishes an efficient and high-quality 2 screening operation in a cost-efficient manner.
4 These objects and others which will become apparent hereinafter are attained in accordance with the present invention by providing a blade exhibiting 6 a screen-proximal outer contour profile which in conjunction with the screen wall 7 forms in material flow direction a suction zone section of increasing blade width 8 and a pressure zone section of decreasing blade width, with the length of the 9 suction zone section and the length of the pressure zone section defining the overall length of the blade, whereby the screen-proximal outer contour profile of 11 the blade is smooth and continuos also in a transition area between the area of 12 increasing width and the area of decreasing width of the blade.
14 The blade according to the present invention thus exhibits at the screen-proximal outer contour a profile without edges, interruptions or flutes and 16 thus has a smooth configuration from the zone of increasing width to the zone 17 with decreasing width, including the transition area. Thus, the area of the 18 pressure zone section is characterized by a steady pressure increase so that a 19 careful material transport towards the perforations of the screen wall is effected.
This prevents impurities from surging in the pressure zone section through the 21 perforations of the screen wall so that the screening quality is enhanced.
At the 22 same time, turbulences required to free and clean the perforations and a 1 sufficient fluidization of the material being screened are created as a 2 consequence of the changing blade width in the suction zone section.
Further, 3 pulsation and ensuing beating are eliminated by the steady and continuous 4 contour profile in the suction zone section so as to attain a more efficient material flow for increasing the efficiency of the screening operation. The outer 6 contour profile of the blade also reduces its inherent flow resistance in the area 7 of the material flow so that the screening operation can be executed more 8 efficiently and the screening apparatus can be operated in energy-saving 9 fashion since the speed of the rotor can be reduced while yet achieving the same productivity and thus operate at enhanced current consumption.
12 A screening apparatus equipped with a blade according to the present 13 invention is particularly suitable for effecting a screening in the high consistency 14 zone as well as a screening for use with rather coarse impurities because of the significantly improved screening quality. The reduction of the pulsations as a 16 result of the continuous and steady outer contour profile prevents the risk of 17 damages and disturbances during subsequent processing steps, and the strain 18 upon the screen walls, which are typically formed by screen baskets, can be 19 reduced.
21 According to a feature of the present invention, the geometry of the blade 22 has been shown particularly suitable when being constructed as follows:
21863 :8 1 - the pressure zone section of the blade has a length which is about 0.1-0.45 2 times the overall length of the blade, preferably about 0.3 times the overall 3 length;
- the blade in the pressure zone section has a radius of curvature of about 0.3-6 0.6 times the overall length of the blade, preferably 0.4-0.5 times the overall 7 length;
9 - the leading end of the blade in the suction zone section is defined by a radius of curvature which is in the order of 3-25 mm, preferably 6-20 mm.
12 In the area of the suction zone section, the performance of the blade can 13 be optimized when satisfying the following profile characteristics:
- the blade is defined in the suction zone section by a radius of curvature of 16 about 0.8-1.5 times the overall length of the blade, preferably 0.9-1.4 of the 17 overall length;
19 - the trailing end of the blade is preferably defined by a radius of curvature in the order of 1-5 mm, preferably 1.5-3 mm.
21863,28 1 Further parameters to be considered include the overall length of the 2 blade in relation to the inside screen diameter as well as the greatest blade 3 width. The overall length in relation to the inside screen diameter is 4 approximately in the order of 0.05-0.3 times the inside screen diameter, preferably from 0.08-0.2 times the inside screen diameter. The greatest blade 6 width is about 0.15-0.35 times the overall length of the blade, preferably 0.2-0.27 7 times the overall length.
9 When constructing the blade and in particular the outer contour profile of the blade that is adjacent to the screen by observing the indicated ranges for the 11 parameters, pressure pulsations can be eliminated and current consumption can 12 be reduced because the width of the blade and the leading blade radius in the 13 area of the pressure zone section result in a highly siender configuration of the 14 blade.
16 With regard to the entrance area of the pulp, the blade according to the 17 present invention results in a careful advance of the pulp towards the 18 perforations of the screen wall. As a result of the steady pressure increase in the 19 area of the pressure zone, a pressing of impurities through the perforations can be avoided so that a separation of impurities is effected. Moreover, this section 21 is also dimensioned of suitable length to prevent thickening effects.
1 The outer contour profile of the blade according to the present invention 2 also imparts the suction zone section with a sufficient length to ensure a reliable 3 cleaning of the perforations in the screen wall. A suction zone section of too 4 short a length would result in a premature breakdown of the stream and causes swirling that adversely affects the cleaning action.
7 The careful material flow towards the screen wall optimizes the interaction 8 with the screen wall even in those situations in which the screen wall is e.g. of 9 contoured configuration so that a higher throughput is effected. Moreover, the rotor speed can be reduced, thereby diminishing the energy consumption.
12 Preferably, the smallest distance between the outer contour profile of the 13 blade and the adjacent screen wall is in the range of about 0.5-10 mm, 14 preferably 1.5-6 mm. This minimum clearance is substantially smaller than in conventional constructions of such screens so that high-quality screening results 16 can be accomplished without experiencing any matfunction. Moreover, the rotor 17 speed can be reduced because the blade positively effects the area of the 18 material flow with respect to cleaning and material conduction as a consequence 19 of the reduced distance.
21 The screen-distant side of the blade which in case of a freely protruding 22 blade also effects the performance of the screening apparatus, may also be so 1 constructed as to essentially correspond to the configuration of the 2 screen-proximate outer contour profile of the blade. This results in a symmetric 3 configuration of the blade. On the other hand, the profile of the screen-distant 4 side of the blade may however also deviate from the profile of the screen-proximate side. For example, the screen-distant side may be constructed 6 as a straight or flat section.
8 In particular, the blade is of a shape enhancing flow dynamics so as to be 9 enable to reduce the inherent flow resistance of the blade and to further reduce the energy consumption. Also interfering streams in the area of the material flow 11 can be suppressed in order to enhance the material flow on the cleaning side as 12 well as of the material supply side.
14 If necessary, the blade may be constructed of multiple parts. Whether the blade is constructed in form of a singular part or multiple parts depends 16 essentially on the size of the blade as well as on its function and arrangement, 17 e.g. upon a base body.
19 Preferably, the section of increasing blade width and the section of decreasing blade width may point in material flow direction or in opposition 21 thereto. Thus, the blade according to the present invention positively affects the 1 material flow regardless of the direction of relative movement between the 2 screen wall and the blade.
4 The disposition of the blade or several blades may vary. For example, the blade may be secured directly onto the outer circumference of a base body, 6 such as for example a rotor, preferably a rotor of essentially cylindrical or conical 7 configuration, or may be an integral part of the base body, or may also be 8 secured to the base body via a support arm. When the blade is placed and 9 secured to the outer circumference of the base body, the connection can be effected through welding or soldering or may be screwed thereon. When being 11 placed and secured directly upon the outer circumference of the rotor, no 12 protruding components are created so that dead zones, slivers, shives, or like 13 rejects are avoided. This improves the operational safety of a screening 14 apparatus when equipped with a blade according to the present invention.
The elimination of protruding components results also in a reduction of the inherent 16 flow resistance of the assembly in the area of the material stream so as to 17 experience not only a more efficient operation of the screening apparatus but 18 also an energy-saving operation.
According to another feature of the present invention, the blade can be 21 secured to the base body via spacers such as shims or the like, by which the 22 distance between the screen-nearest point of the outer blade contour and the 1 screen wall can be modified and varied. In this manner, a fine-tuning to the 2 respective screening task can be effected.
4 Moreover, the blade can be arranged at an inclination relative to the generatrix of the base body. Thus, transitional areas between individual 6 screening steps can be realized.
8 The performance of the blade can be further improved by orienting the 9 blade upon the base body in relation to the tangent at an angle which may range up to 100, or preferably up to 4 .
12 According to another embodiment of the present invention, the screening 13 apparatus may comprise a plurality of such blades which are arranged in various 14 axial planes of the base body in offset disposition in circumferential direction.
This results in a blade assembly for a screening apparatus by which the action 16 of the blades can be best suited to the screening tasks as assigned to the 17 respective screening planes, without encountering any relevant mutual 18 influence.
Thus, the blade according to the present invention can be so configured 21 and constructed for use with a screening apparatus for fiber suspensions, in 22 particular for pulping, in an optimum manner as to exhibit an outer contour Ir1C3U3w8 1 profile that enhances the flow dynamics, without formation of sharp edges.
This 2 reduces the inherent flow resistance and accomplishes a significant energy 3 saving. Moreover, through the section of steadily increasing blade width and the 4 section of steadily decreasing blade width, with both sections being smoothly connected to one another, a suction zone is formed, on the one hand, in 6 conjunction with the facing screen wall that generates a sufficient suction to 7 create an effective cleaning of the screen, and a pressure zone is formed, on the 8 other hand, which enables a careful material transport towards the perforations 9 of the screen wall without experiencing a sudden pressure increase. This considerably improves the screening quality.
14 The above and other objects, features and advantages of the present invention will now be described in more detail with reference to the 16 accompanying drawing in which:
18 FIG.1 is a fragmentary, schematic top view of a screening 19 apparatus using a blade according to the present invention;
21 FIG. 2 is a fragmentary, schematic top view of a screening 22 apparatus using a plurality of blades according to the present invention;
and ~18 630948 1 FIG. 3 is a fragmentary, schematic top view of a screening 2 apparatus for use with a modified blade assembly according to the present 3 invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
7 Throughout all the Figures, the same or corresponding elements are 8 generally indicated by the same reference numerals.
Turning now to the drawing, and in particular to FIG. 1, there is shown a 11 fragmentary, schematic top view of a screening apparatus intended for 12 screening a material stream, e.g. a fiber suspension, and equipped with a blade 13 or hydrofoil 5 according to the present invention. The screening apparatus 14 includes a screen, generally designated by reference numeral 2, and shown, for ease of illustration, only by way of a section of a screen wall 2a. The screen 2 is 16 formed with generally vertically oriented individual perforations 3 which extend 17 through the screen wall 2a transversely to the flow direction of the material 18 stream, as indicated by arrow A.
It will be appreciated by persons skilled in the art that the screening 21 apparatus has more mechanical apparatus which does not appear in the 22 foregoing Figures. For example, the screening apparatus typically includes a 1 vessel for accommodating the screen, a rotor, such as e.g. rotor 1 schematically 2 shown in FIG. 2, for carrying the blade 5 that advances the fiber suspension 3 towards the screen perforations 3. However, this apparatus, like other necessary 4 apparatus, is not part of the invention, and apart from the rotor 1 has been omitted from the Figures.
7 The screen 2 is defined by an inner diameter designated by reference 8 character Di. The blade 5 can be secured in a manner as best suited for various 9 tasks and different rotor types. As the present invention is concerned primarily with the relative movement between the screen wall 2a and the outer contour 11 profile of the blade 5, the following description is primarily directed towards the 12 interaction between the screen wall 2a and the blade 5, on the one hand, and 13 the material flow in direction of arrow A, on the other hand. It will be understood 14 by persons skilled in the art that the material flow direction can certainly be reversed in order to attain the desired effects of freeing the perforations 3 of 16 impurities, prevention of pulsations and effecting a sufficient fluidization of 17 material being screened.
19 The blade 5 exhibits adjacent to the screen wall 2a an outer contour profile 6 which is so configured as to interact with the screen wall 2a to form in 21 material flow direction A a suction zone section C of increasing blade width and 22 a pressure zone section D of decreasing blade width, whereby the suction zone Z '18fi3~8 1 is designated by reference character P- and the pressure zone is designated by 2 reference character P+. The blade 5 is defined by an overall blade length Fl 3 which equals the sum of the length L1 of the pressure zone section D and the 4 length L2 of the suction zone section C. In relation to the inside screen diameter Di of the screen 2, the overall blade Fl is approximately 0.05-0.3 x Di, 6 preferably 0.08-0.2 x Di. The length L1 of the pressure zone section D is 7 approximately 0.1-0.45 x Fl, preferably 0.3 x Fl. The greatest blade width is 8 designated by reference character Fb and is measured between the 9 screen-distant side of the blade 5 and the apex of the outer contour profile 6 of the blade 5. The greatest blade width Fb is for example in a range of 0.15-0.35 x 11 Fl, especially from 0.2-0.27 x Fl. In the pressure zone section D, the outer 12 contour profile 6 of the blade 5 is preferably formed by a circular section at a 13 radius R2 which is approximately in a range of 0.3-0.6 x Fl, preferably 0.4-0.5 x 14 Fl. The leading end of the blade 5 is preferably formed by a directly following circular section at a radius R3, or phases out at the radius R3 which is in a 16 range approximately of 3-25 mm, especially 6-20 mm.
18 The outer contour profile 6 of the blade 5 in the suction zone section C is 19 formed preferably by a circular section at a radius R1 which is in the order of 0.8-1.5 x Fl, especially 0.9-1.4 x Fl . At the entrance into the suction zone P- the 21 trailing end of the outer contour profile 6 is formed by a circular section at a 22 radius R4 which is in the range of 1-5 mm, preferably in a range of 1.5-3 mm.
1 The smallest distance between the screen wall 2a and the outer contour 2 profile 6 is designated by reference character s which is in a range of 3 0.5-10 mm, preferably from about 1.5 to about 6 mm.
As schematically illustrated in FIG. 1, the screen-distant side of the 6 blade 5 extends approximately perpendicular to a not shown center axis of the 7 screening apparatus. As further shown schematically in FIG. 1, the 8 screen-distant side of the blade 5 may however also extend at an angle FW in a 9 range of up to 100, preferably up to 4 . At such disposition, the blade 5 extends in relation to the tangent upon a base body 1 which may be e.g. a rotor base 11 body 1, as shown in FIG. 2.
13 The blade 5 interacts with the perforations 3 of the screen 2 regardless of 14 the configuration of the perforations 3. In the area of the suction zone P-(suction zone section C), turbulences are generated in zone of the perforations 3 for 16 freeing and cleaning of the perforations 3 as well as for advancing the material 17 stream through the perforations 3. The increasing width of the blade 5 in the 18 suction zone section C effects a careful material transport to the nearest 19 perforation 3 in direction of the material flow. Starting from the point of greatest width of the blade 5, a steady pressure build-up is effected in the pressure zone 21 section D so as to force the material through the perforations 3 in an efficient 22 manner in the pressure zone P+.
1 As a consequence of the steady pressure build-up created by the outer 2 contour profile 6 of the blade 5 in the area of the pressure zone P+ up to the 3 smallest distance s, the screening quality is improved because impurities are 4 prevented from being pressed through the perforations 3 as a result of a sudden pressure increase. The performance of the blade 5 according to the present 6 invention is more efficient as the particular configuration of the outer contour 7 profile 6 enhances the flow dynamics so that the energy consumption of the 8 overall screening apparatus is reduced. Also, the inherent flow resistance of the 9 blade 5 is thereby reduced and dead zones, shives, slivers or like rejects which adversely effect the efficiency of the screening apparatus or may even lead to 11 malfunction and plugging of the perforations 3. As the suction zone section C
12 and the pressure zone section D are joined together without interruption by a 13 smooth transition, pulsation is reduced that previously subjected the screen 2 to 14 considerable stress, especially alternating loads. Thus, the blade 5 according to the invention results in a highly efficient screening operation to achieve 16 high-quality results as well as in an energy-saving, reliable operation of the 17 screening apparatus.
19 Turning now to FIG. 2, there is shown a fragmentary, schematic top view of a preferred embodiment of a screen 2 using a plurality of blades 5 according 21 to the present invention. The screening apparatus includes a rotor with a rotor 22 base body 1 which rotates clockwise in correspondence to the material flow 1 direction as indicated by arrow A. The rotor base body 1 may be of substantially 2 cylindrical or conical or truncated cone shaped configuration and is surrounded 3 by the screen 2 forming the screen wall 2a with perforations 3, such as 4 openings, slots or the like. The geometry of the perforations 3 may be selected in any suitable manner, for example as shown in U.S. Pat. No. 5,073,254 which 6 illustrates screen openings leading into groove-shaped recesses extending 7 essentially transversely to the flow direction of a fiber suspension. The recesses 8 are of arcuated configuration and define a downstream flank and an upstream 9 flank, with the downstream flank having a sharper curvature than the upstream flank. Both flanks are connected smoothly and continuously by an arched 11 transition.
13 As shown in FIG. 1, the rotor base body 1 has an outer circumference 4 14 for supporting several blades 5 spaced from each other in circumferential direction and secured to the rotor base body 1 e.g. through welding or soldering.
16 Persons skilled in the art will understand that it is certainly within the scope of 17 the present invention to secure the blades 5 on the rotor base body 1 in a 18 different manner, e.g. through a screwed connection or via support arms 7 for 19 mounting the blades 5 to the rotor base body 1, as shown for example in FIG. 3.
It is also possible to provide in addition spacers, such as shims or the like, to 21 secure the blade 5 to the rotor base body 1 in order to modify the smallest ~186328 1 distance s between the screen wall 2a and the outer contour profile 6 of the 2 blade 5, if necessary.
4 Although not shown in detail, the screening apparatus may also be so constructed that the rotor base body 1 with the attached blades 5 is stationary, 6 while the screen 2 rotates about a common center axis of the screen 2 and the 7 base body 1. Moreover, the blades 5 may be arranged on different axial planes 8 of the base body 1. For example, each blade 5 may be inclined in relation to the 9 generatrix of the base body 1. Preferably, the blades 5 are arranged in offset relationship towards each other in different axial planes of the base body 1.
12 As described above, a substantially similar effect and same advantages 13 are attained when reversing the direction of rotating of the rotor base body 1 or 14 upon reversal of the material flow direction to effect a relative movement between the blades 5 and the screen 2 in opposite direction of arrow A.
17 While the invention has been illustrated and described as embodied in a 18 blade for a screening apparatus, it is not intended to be limited to the details 19 shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
22 What is claimed as new and desired to be protected by Letters Patent is 23 set forth in the appended claims:
7 The present invention refers to a blade for a screening apparatus, 8 especially for fiber suspensions during pulping.
European Pat. No. EP-A-O 275 921 describes a blade for a screen with 11 drum-like base body. The blade includes in the meridian section a steadily 12 increasing cross section in direction of rotation and terminates in a steep edge.
13 Joined to the steep edge in direction of rotation is a prolongation which has a 14 cross section decreasing in direction of rotation and exhibits a flute. The area of increasing cross section forms a suction zone in conjunction with a screen wall 16 that surrounds the drum-shaped base body, and the area of decreasing cross 17 section forms a pressure zone in conjunction with the screen wall. The 18 contoured outer surface of the blade exhibits a steep edge at the transition 19 between the area of increasing cross section and the area of decreasing cross section, resulting in a sudden directional change that can cause a pressing of 21 impurities in the area of the pressure zone through the perforations of the screen 22 wall so that the screening quality is adversely affected. The profile of the blade 1 conducts the material stream directly towards the perforations which are thus 2 subject to a considerable hydraulic load, risking a slight shift of the screen. The 3 provision of a flute and the sudden directional change cause strong pulsation 4 which results in swirling in the material stream, and may lead especially at increasing material density to fiber accumulations at the blade. This may lead to 6 malfunction of the screen, especially when the screening surface becomes 7 plugged. The sharp edge between the increasing cross sectional area and the 8 decreasing cross sectional area leads to a relatively high flow residence in the 9 material stream through the blade so that this conventional screening apparatus has to run at relatively high speeds, resulting in a relatively high energy 11 consumption during operation.
13 U.S. Pat. No. 4,676,903 discloses a screening apparatus for screening 14 and purification of pulp, and includes a rotor which has a contoured surface with grooves which are formed by a first plane parallel to the envelope surface, an 16 inclined plane, an upper plane and a side plane, with the side plane extending 17 essentially perpendicular to the first plane. This profile of the groove also results 18 in the formation of a steep edge between the pressure zone and the suction 19 zone during rotating rotor. This conventional screening apparatus thus has basically the same drawbacks as the screening apparatus according to 21 European Pat. No. 0 275 921. Fiber bundles and slivers may form on the 22 protruding areas as a result of the steep edges, leading to malfunction of the 1 screening apparatus and/or to a decreasing efficiency of the screening 2 operation. Further disclosed in this patent is a blade, often referred to as 3 hydrofoil, which is so constructed that a maximum pressure pulse is gener-4 ated by the leading surface of the blade at the narrowest clearance point towards the screening basket. This patent desires to generate and to sustain 6 over a long period very high frequency pulses. This, however, creates 7 undesired pressure pulsations.
8 The publication "Weekly Gazette for Paper Manufacturing, No. 17, 9 1988, Pages 733-737 discloses an article by D. Egelhof, entitled "The 1o Vertical sifter pulsating arms - bases, development, results", setting forth 11 that optimization of the blade profile can produce an attenuation of the 12 pressure oscillations emanating from a vertical sifter. This publication fails 13 to present particulars and only refers to the arrangement of the blades at the 14 rotor to effect a reduction of the pressure oscillations.
German Pat. No. 28 30 386 C2 and International patent specifica-16 tion W090/05807 describe screening apparatuses which include a rotor 17 carrying on its outer circumference cleaning and screening elements in 18 protruding disposition. This protruding attachment also results in formation 19 of fiber bundles and slivers as well as dead zones and shives because the cleaning elements exert an adverse effect upon the area of the material 21 stream. The annular gap .,.
1 between the screen wall and the rotor is narrowed by the jutting height of the 2 cleaning elements and engagement elements. When exhibiting only a slight 3 clearance between the apex of the cleaning element and the screen wall 4 surface, the material being treated may be subject to a significant thickening at this greatly constricted annular gap. This results to malfunction of the screening 6 apparatus. If, on the other hand, the rotor is positioned at a greater clearance 7 from the screen wall, then, the rotor speed must be raised so that the energy 8 consumption of the screening apparatus is increased.
SUMMARY OF THE INVENTION
12 It is an object of the present invention to provide an improved blade for a 13 screening apparatus, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an 16 improved blade for use in a screening apparatus, to keep the screen free from 17 impurities, to prevent thickening effects and pulsations while effecting a 18 sufficient fluidization of the material been screened mainly through creation of 19 turbulences.
21 It is yet another object of the present invention to provide an improved 22 blade for a screening apparatus, which is particularly suitable for fiber õ,.
zi863*213 1 suspensions during pulping and accomplishes an efficient and high-quality 2 screening operation in a cost-efficient manner.
4 These objects and others which will become apparent hereinafter are attained in accordance with the present invention by providing a blade exhibiting 6 a screen-proximal outer contour profile which in conjunction with the screen wall 7 forms in material flow direction a suction zone section of increasing blade width 8 and a pressure zone section of decreasing blade width, with the length of the 9 suction zone section and the length of the pressure zone section defining the overall length of the blade, whereby the screen-proximal outer contour profile of 11 the blade is smooth and continuos also in a transition area between the area of 12 increasing width and the area of decreasing width of the blade.
14 The blade according to the present invention thus exhibits at the screen-proximal outer contour a profile without edges, interruptions or flutes and 16 thus has a smooth configuration from the zone of increasing width to the zone 17 with decreasing width, including the transition area. Thus, the area of the 18 pressure zone section is characterized by a steady pressure increase so that a 19 careful material transport towards the perforations of the screen wall is effected.
This prevents impurities from surging in the pressure zone section through the 21 perforations of the screen wall so that the screening quality is enhanced.
At the 22 same time, turbulences required to free and clean the perforations and a 1 sufficient fluidization of the material being screened are created as a 2 consequence of the changing blade width in the suction zone section.
Further, 3 pulsation and ensuing beating are eliminated by the steady and continuous 4 contour profile in the suction zone section so as to attain a more efficient material flow for increasing the efficiency of the screening operation. The outer 6 contour profile of the blade also reduces its inherent flow resistance in the area 7 of the material flow so that the screening operation can be executed more 8 efficiently and the screening apparatus can be operated in energy-saving 9 fashion since the speed of the rotor can be reduced while yet achieving the same productivity and thus operate at enhanced current consumption.
12 A screening apparatus equipped with a blade according to the present 13 invention is particularly suitable for effecting a screening in the high consistency 14 zone as well as a screening for use with rather coarse impurities because of the significantly improved screening quality. The reduction of the pulsations as a 16 result of the continuous and steady outer contour profile prevents the risk of 17 damages and disturbances during subsequent processing steps, and the strain 18 upon the screen walls, which are typically formed by screen baskets, can be 19 reduced.
21 According to a feature of the present invention, the geometry of the blade 22 has been shown particularly suitable when being constructed as follows:
21863 :8 1 - the pressure zone section of the blade has a length which is about 0.1-0.45 2 times the overall length of the blade, preferably about 0.3 times the overall 3 length;
- the blade in the pressure zone section has a radius of curvature of about 0.3-6 0.6 times the overall length of the blade, preferably 0.4-0.5 times the overall 7 length;
9 - the leading end of the blade in the suction zone section is defined by a radius of curvature which is in the order of 3-25 mm, preferably 6-20 mm.
12 In the area of the suction zone section, the performance of the blade can 13 be optimized when satisfying the following profile characteristics:
- the blade is defined in the suction zone section by a radius of curvature of 16 about 0.8-1.5 times the overall length of the blade, preferably 0.9-1.4 of the 17 overall length;
19 - the trailing end of the blade is preferably defined by a radius of curvature in the order of 1-5 mm, preferably 1.5-3 mm.
21863,28 1 Further parameters to be considered include the overall length of the 2 blade in relation to the inside screen diameter as well as the greatest blade 3 width. The overall length in relation to the inside screen diameter is 4 approximately in the order of 0.05-0.3 times the inside screen diameter, preferably from 0.08-0.2 times the inside screen diameter. The greatest blade 6 width is about 0.15-0.35 times the overall length of the blade, preferably 0.2-0.27 7 times the overall length.
9 When constructing the blade and in particular the outer contour profile of the blade that is adjacent to the screen by observing the indicated ranges for the 11 parameters, pressure pulsations can be eliminated and current consumption can 12 be reduced because the width of the blade and the leading blade radius in the 13 area of the pressure zone section result in a highly siender configuration of the 14 blade.
16 With regard to the entrance area of the pulp, the blade according to the 17 present invention results in a careful advance of the pulp towards the 18 perforations of the screen wall. As a result of the steady pressure increase in the 19 area of the pressure zone, a pressing of impurities through the perforations can be avoided so that a separation of impurities is effected. Moreover, this section 21 is also dimensioned of suitable length to prevent thickening effects.
1 The outer contour profile of the blade according to the present invention 2 also imparts the suction zone section with a sufficient length to ensure a reliable 3 cleaning of the perforations in the screen wall. A suction zone section of too 4 short a length would result in a premature breakdown of the stream and causes swirling that adversely affects the cleaning action.
7 The careful material flow towards the screen wall optimizes the interaction 8 with the screen wall even in those situations in which the screen wall is e.g. of 9 contoured configuration so that a higher throughput is effected. Moreover, the rotor speed can be reduced, thereby diminishing the energy consumption.
12 Preferably, the smallest distance between the outer contour profile of the 13 blade and the adjacent screen wall is in the range of about 0.5-10 mm, 14 preferably 1.5-6 mm. This minimum clearance is substantially smaller than in conventional constructions of such screens so that high-quality screening results 16 can be accomplished without experiencing any matfunction. Moreover, the rotor 17 speed can be reduced because the blade positively effects the area of the 18 material flow with respect to cleaning and material conduction as a consequence 19 of the reduced distance.
21 The screen-distant side of the blade which in case of a freely protruding 22 blade also effects the performance of the screening apparatus, may also be so 1 constructed as to essentially correspond to the configuration of the 2 screen-proximate outer contour profile of the blade. This results in a symmetric 3 configuration of the blade. On the other hand, the profile of the screen-distant 4 side of the blade may however also deviate from the profile of the screen-proximate side. For example, the screen-distant side may be constructed 6 as a straight or flat section.
8 In particular, the blade is of a shape enhancing flow dynamics so as to be 9 enable to reduce the inherent flow resistance of the blade and to further reduce the energy consumption. Also interfering streams in the area of the material flow 11 can be suppressed in order to enhance the material flow on the cleaning side as 12 well as of the material supply side.
14 If necessary, the blade may be constructed of multiple parts. Whether the blade is constructed in form of a singular part or multiple parts depends 16 essentially on the size of the blade as well as on its function and arrangement, 17 e.g. upon a base body.
19 Preferably, the section of increasing blade width and the section of decreasing blade width may point in material flow direction or in opposition 21 thereto. Thus, the blade according to the present invention positively affects the 1 material flow regardless of the direction of relative movement between the 2 screen wall and the blade.
4 The disposition of the blade or several blades may vary. For example, the blade may be secured directly onto the outer circumference of a base body, 6 such as for example a rotor, preferably a rotor of essentially cylindrical or conical 7 configuration, or may be an integral part of the base body, or may also be 8 secured to the base body via a support arm. When the blade is placed and 9 secured to the outer circumference of the base body, the connection can be effected through welding or soldering or may be screwed thereon. When being 11 placed and secured directly upon the outer circumference of the rotor, no 12 protruding components are created so that dead zones, slivers, shives, or like 13 rejects are avoided. This improves the operational safety of a screening 14 apparatus when equipped with a blade according to the present invention.
The elimination of protruding components results also in a reduction of the inherent 16 flow resistance of the assembly in the area of the material stream so as to 17 experience not only a more efficient operation of the screening apparatus but 18 also an energy-saving operation.
According to another feature of the present invention, the blade can be 21 secured to the base body via spacers such as shims or the like, by which the 22 distance between the screen-nearest point of the outer blade contour and the 1 screen wall can be modified and varied. In this manner, a fine-tuning to the 2 respective screening task can be effected.
4 Moreover, the blade can be arranged at an inclination relative to the generatrix of the base body. Thus, transitional areas between individual 6 screening steps can be realized.
8 The performance of the blade can be further improved by orienting the 9 blade upon the base body in relation to the tangent at an angle which may range up to 100, or preferably up to 4 .
12 According to another embodiment of the present invention, the screening 13 apparatus may comprise a plurality of such blades which are arranged in various 14 axial planes of the base body in offset disposition in circumferential direction.
This results in a blade assembly for a screening apparatus by which the action 16 of the blades can be best suited to the screening tasks as assigned to the 17 respective screening planes, without encountering any relevant mutual 18 influence.
Thus, the blade according to the present invention can be so configured 21 and constructed for use with a screening apparatus for fiber suspensions, in 22 particular for pulping, in an optimum manner as to exhibit an outer contour Ir1C3U3w8 1 profile that enhances the flow dynamics, without formation of sharp edges.
This 2 reduces the inherent flow resistance and accomplishes a significant energy 3 saving. Moreover, through the section of steadily increasing blade width and the 4 section of steadily decreasing blade width, with both sections being smoothly connected to one another, a suction zone is formed, on the one hand, in 6 conjunction with the facing screen wall that generates a sufficient suction to 7 create an effective cleaning of the screen, and a pressure zone is formed, on the 8 other hand, which enables a careful material transport towards the perforations 9 of the screen wall without experiencing a sudden pressure increase. This considerably improves the screening quality.
14 The above and other objects, features and advantages of the present invention will now be described in more detail with reference to the 16 accompanying drawing in which:
18 FIG.1 is a fragmentary, schematic top view of a screening 19 apparatus using a blade according to the present invention;
21 FIG. 2 is a fragmentary, schematic top view of a screening 22 apparatus using a plurality of blades according to the present invention;
and ~18 630948 1 FIG. 3 is a fragmentary, schematic top view of a screening 2 apparatus for use with a modified blade assembly according to the present 3 invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
7 Throughout all the Figures, the same or corresponding elements are 8 generally indicated by the same reference numerals.
Turning now to the drawing, and in particular to FIG. 1, there is shown a 11 fragmentary, schematic top view of a screening apparatus intended for 12 screening a material stream, e.g. a fiber suspension, and equipped with a blade 13 or hydrofoil 5 according to the present invention. The screening apparatus 14 includes a screen, generally designated by reference numeral 2, and shown, for ease of illustration, only by way of a section of a screen wall 2a. The screen 2 is 16 formed with generally vertically oriented individual perforations 3 which extend 17 through the screen wall 2a transversely to the flow direction of the material 18 stream, as indicated by arrow A.
It will be appreciated by persons skilled in the art that the screening 21 apparatus has more mechanical apparatus which does not appear in the 22 foregoing Figures. For example, the screening apparatus typically includes a 1 vessel for accommodating the screen, a rotor, such as e.g. rotor 1 schematically 2 shown in FIG. 2, for carrying the blade 5 that advances the fiber suspension 3 towards the screen perforations 3. However, this apparatus, like other necessary 4 apparatus, is not part of the invention, and apart from the rotor 1 has been omitted from the Figures.
7 The screen 2 is defined by an inner diameter designated by reference 8 character Di. The blade 5 can be secured in a manner as best suited for various 9 tasks and different rotor types. As the present invention is concerned primarily with the relative movement between the screen wall 2a and the outer contour 11 profile of the blade 5, the following description is primarily directed towards the 12 interaction between the screen wall 2a and the blade 5, on the one hand, and 13 the material flow in direction of arrow A, on the other hand. It will be understood 14 by persons skilled in the art that the material flow direction can certainly be reversed in order to attain the desired effects of freeing the perforations 3 of 16 impurities, prevention of pulsations and effecting a sufficient fluidization of 17 material being screened.
19 The blade 5 exhibits adjacent to the screen wall 2a an outer contour profile 6 which is so configured as to interact with the screen wall 2a to form in 21 material flow direction A a suction zone section C of increasing blade width and 22 a pressure zone section D of decreasing blade width, whereby the suction zone Z '18fi3~8 1 is designated by reference character P- and the pressure zone is designated by 2 reference character P+. The blade 5 is defined by an overall blade length Fl 3 which equals the sum of the length L1 of the pressure zone section D and the 4 length L2 of the suction zone section C. In relation to the inside screen diameter Di of the screen 2, the overall blade Fl is approximately 0.05-0.3 x Di, 6 preferably 0.08-0.2 x Di. The length L1 of the pressure zone section D is 7 approximately 0.1-0.45 x Fl, preferably 0.3 x Fl. The greatest blade width is 8 designated by reference character Fb and is measured between the 9 screen-distant side of the blade 5 and the apex of the outer contour profile 6 of the blade 5. The greatest blade width Fb is for example in a range of 0.15-0.35 x 11 Fl, especially from 0.2-0.27 x Fl. In the pressure zone section D, the outer 12 contour profile 6 of the blade 5 is preferably formed by a circular section at a 13 radius R2 which is approximately in a range of 0.3-0.6 x Fl, preferably 0.4-0.5 x 14 Fl. The leading end of the blade 5 is preferably formed by a directly following circular section at a radius R3, or phases out at the radius R3 which is in a 16 range approximately of 3-25 mm, especially 6-20 mm.
18 The outer contour profile 6 of the blade 5 in the suction zone section C is 19 formed preferably by a circular section at a radius R1 which is in the order of 0.8-1.5 x Fl, especially 0.9-1.4 x Fl . At the entrance into the suction zone P- the 21 trailing end of the outer contour profile 6 is formed by a circular section at a 22 radius R4 which is in the range of 1-5 mm, preferably in a range of 1.5-3 mm.
1 The smallest distance between the screen wall 2a and the outer contour 2 profile 6 is designated by reference character s which is in a range of 3 0.5-10 mm, preferably from about 1.5 to about 6 mm.
As schematically illustrated in FIG. 1, the screen-distant side of the 6 blade 5 extends approximately perpendicular to a not shown center axis of the 7 screening apparatus. As further shown schematically in FIG. 1, the 8 screen-distant side of the blade 5 may however also extend at an angle FW in a 9 range of up to 100, preferably up to 4 . At such disposition, the blade 5 extends in relation to the tangent upon a base body 1 which may be e.g. a rotor base 11 body 1, as shown in FIG. 2.
13 The blade 5 interacts with the perforations 3 of the screen 2 regardless of 14 the configuration of the perforations 3. In the area of the suction zone P-(suction zone section C), turbulences are generated in zone of the perforations 3 for 16 freeing and cleaning of the perforations 3 as well as for advancing the material 17 stream through the perforations 3. The increasing width of the blade 5 in the 18 suction zone section C effects a careful material transport to the nearest 19 perforation 3 in direction of the material flow. Starting from the point of greatest width of the blade 5, a steady pressure build-up is effected in the pressure zone 21 section D so as to force the material through the perforations 3 in an efficient 22 manner in the pressure zone P+.
1 As a consequence of the steady pressure build-up created by the outer 2 contour profile 6 of the blade 5 in the area of the pressure zone P+ up to the 3 smallest distance s, the screening quality is improved because impurities are 4 prevented from being pressed through the perforations 3 as a result of a sudden pressure increase. The performance of the blade 5 according to the present 6 invention is more efficient as the particular configuration of the outer contour 7 profile 6 enhances the flow dynamics so that the energy consumption of the 8 overall screening apparatus is reduced. Also, the inherent flow resistance of the 9 blade 5 is thereby reduced and dead zones, shives, slivers or like rejects which adversely effect the efficiency of the screening apparatus or may even lead to 11 malfunction and plugging of the perforations 3. As the suction zone section C
12 and the pressure zone section D are joined together without interruption by a 13 smooth transition, pulsation is reduced that previously subjected the screen 2 to 14 considerable stress, especially alternating loads. Thus, the blade 5 according to the invention results in a highly efficient screening operation to achieve 16 high-quality results as well as in an energy-saving, reliable operation of the 17 screening apparatus.
19 Turning now to FIG. 2, there is shown a fragmentary, schematic top view of a preferred embodiment of a screen 2 using a plurality of blades 5 according 21 to the present invention. The screening apparatus includes a rotor with a rotor 22 base body 1 which rotates clockwise in correspondence to the material flow 1 direction as indicated by arrow A. The rotor base body 1 may be of substantially 2 cylindrical or conical or truncated cone shaped configuration and is surrounded 3 by the screen 2 forming the screen wall 2a with perforations 3, such as 4 openings, slots or the like. The geometry of the perforations 3 may be selected in any suitable manner, for example as shown in U.S. Pat. No. 5,073,254 which 6 illustrates screen openings leading into groove-shaped recesses extending 7 essentially transversely to the flow direction of a fiber suspension. The recesses 8 are of arcuated configuration and define a downstream flank and an upstream 9 flank, with the downstream flank having a sharper curvature than the upstream flank. Both flanks are connected smoothly and continuously by an arched 11 transition.
13 As shown in FIG. 1, the rotor base body 1 has an outer circumference 4 14 for supporting several blades 5 spaced from each other in circumferential direction and secured to the rotor base body 1 e.g. through welding or soldering.
16 Persons skilled in the art will understand that it is certainly within the scope of 17 the present invention to secure the blades 5 on the rotor base body 1 in a 18 different manner, e.g. through a screwed connection or via support arms 7 for 19 mounting the blades 5 to the rotor base body 1, as shown for example in FIG. 3.
It is also possible to provide in addition spacers, such as shims or the like, to 21 secure the blade 5 to the rotor base body 1 in order to modify the smallest ~186328 1 distance s between the screen wall 2a and the outer contour profile 6 of the 2 blade 5, if necessary.
4 Although not shown in detail, the screening apparatus may also be so constructed that the rotor base body 1 with the attached blades 5 is stationary, 6 while the screen 2 rotates about a common center axis of the screen 2 and the 7 base body 1. Moreover, the blades 5 may be arranged on different axial planes 8 of the base body 1. For example, each blade 5 may be inclined in relation to the 9 generatrix of the base body 1. Preferably, the blades 5 are arranged in offset relationship towards each other in different axial planes of the base body 1.
12 As described above, a substantially similar effect and same advantages 13 are attained when reversing the direction of rotating of the rotor base body 1 or 14 upon reversal of the material flow direction to effect a relative movement between the blades 5 and the screen 2 in opposite direction of arrow A.
17 While the invention has been illustrated and described as embodied in a 18 blade for a screening apparatus, it is not intended to be limited to the details 19 shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
22 What is claimed as new and desired to be protected by Letters Patent is 23 set forth in the appended claims:
Claims (35)
1. A blade assembly for a screening apparatus for fiber suspensions during pulping, comprising a blade exhibiting an outer contour profile for cooperation with an adjacent screen wall to form in material flow direction a suction zone section of increasing width of the blade and a pressure zone section of decreasing width of the blade, with the suction zone section having a length and the pressure zone section having a length which together form an overall length of the blade, said outer contour profile of the blade exhibiting a continuous configuration also in a transition area between the suction zone section and pressure zone section, wherein the length of the blade in the pressure zone section is about 0.1 to 0.45 times the overall length of the blade, the suction zone section is defined by a radius which is about 0.8 to 1.5 times the overall length of the blade, the blade having a maximum width in the range of about 0.15 to 0.35 times the overall length of the blade.
2. The blade assembly of claim 1 wherein the length of the blade in the pressure zone section is about 0.3 times the overall length of the blade.
3. The blade assembly of claim 1 or 2 wherein the radius of the suction zone section is about 0.9 to 1.4 times the overall length of the blade.
4. The blade assembly of any one of claims 1 to 3, wherein the maximum width is in the range of about 0.2 to 0.27 times the overall length of the blade.
5. The blade assembly of any one of claims 1 to 4 wherein the pressure zone section is defined by a radius which is about 0.3 to 0.6 times the overall length of the blade.
6. The blade assembly of claim 5 wherein the pressure zone section is defined by a radius which is about 0.4 to 0.5 times the overall length of the blade.
7. The blade assembly of any one of claims 1 to 6 wherein the overall length of the blade is defined in relation to an inner diameter of the screen wall approximately in the order of 0.05 to 0.3 times the inner diameter of the screen wall.
8. The blade assembly of claim 7 wherein the overall length of the blade is defined in relation to the inner diameter of the screen wall approximately in the order of 0.08 to 0.2 times the inner diameter of the screen wall.
9. The blade assembly of any one of claims 1 to 8 wherein the pressure zone section has a leading end defined by a radius in the order of 3 to 25 mm.
10. The blade assembly of claim 9 wherein the radius of the leading end is in the range of about 6 to 20 mm.
11. The blade assembly of any one of claims 1 to 10 wherein the suction zone section has a trailing end defined by a radius in the order of 1 to 5 mm.
12. The blade assembly of claim 11 wherein the trailing end is in the range of about 1.5 lo 3 mm.
13. The blade assembly of any one of claims 1 to 12 wherein the outer contour profile of the blade defines with the adjacent screen wall a smallest distance in the range of about 0.5 to 10 mm.
14. The blade assembly of claim 13 wherein the smallest distance between the outer contour profile of the blade and the adjacent screen wall is in the range of about 1.5 to 6 mm.
15. The blade assembly of any one of claims 1 to 14 wherein the blade has a screen-proximate side and screen-distal side which are of corresponding configuration.
16. The blade assembly of any one of claims 1 to 14 wherein the blade has a screen-proximate side and screen-distal side which are of different configuration.
17. The blade assembly of any one of claims 1 to 16 wherein the outer contour profile is of a shape enhancing flow dynamics.
18. The blade assembly of any one of claims 1 to 17 wherein the blade is constructed of several parts.
19. The blade assembly of any one of claims 1 to 18 wherein the suction zone section and the pressure zone section are directed in fluid flow direction.
20. The blade assembly of any one of claims 1 to 18 wherein the suction zone section and the pressure zone section are directed in opposition to the fluid flow direction.
21. The blade assembly of any one of claims 1 to 20, further comprising a base body having an outer surface for support of the blade.
22. The blade assembly of claim 21 wherein the blade forms an integral part of the base body.
23. The blade assembly of claim 21 or 22 wherein the base body is a rotor base body.
24. The blade assembly of claim 23 wherein the rotor base body is of cylindrical configuration.
25. The blade assembly of claim 23 wherein the rotor base body is of conical configuration.
26. The blade assembly of any one of claims 21 to 23 wherein the base body defines a generatrix, said blade being in inclined disposition to the generatrix.
27. The blade assembly of any one of claims 21 to 26 wherein the blade is positioned in relation to a tangent upon the base body at an angle of up to 10°.
28. The blade assembly of claim 27 wherein the blade is positioned in relation to the tangent upon the base body at an angle of up to 4°.
29. The blade assembly of any one of claims 21 to 28 wherein the blade is placed and secured directly upon the outer surface of the base body.
30. The blade assembly of claim 21 wherein the blade is welded onto the base body.
31. The blade assembly of claim 21 wherein the blade is soldered onto the base body.
32. The blade assembly of any one of claims 21 to 28 wherein the blade is secured to the base body by a support arm.
33. The blade assembly of any one of claims 21 to 29 wherein the blade is secured to the base body by a threaded connection.
34. The blade assembly of claim 13, further comprising a spacer for modifying the smallest distance between the outer contour profile of the blade and the adjacent screen wall.
35. The blade assembly of claim 21 including a plurality of such blades positioned in different base body planes at offset disposition in circumferential direction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE29515338U DE29515338U1 (en) | 1995-09-25 | 1995-09-25 | Wings for sorting devices |
| DE29515338.5 | 1995-09-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2186328A1 CA2186328A1 (en) | 1997-03-26 |
| CA2186328C true CA2186328C (en) | 2008-02-12 |
Family
ID=8013433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002186328A Expired - Fee Related CA2186328C (en) | 1995-09-25 | 1996-09-24 | Blade for a screening apparatus |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0764736B1 (en) |
| AT (1) | ATE214114T1 (en) |
| CA (1) | CA2186328C (en) |
| DE (2) | DE29515338U1 (en) |
| ES (1) | ES2173233T3 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE29515338U1 (en) * | 1995-09-25 | 1995-11-23 | Fiedler Heinrich Gmbh | Wings for sorting devices |
| FI102980B (en) * | 1997-05-21 | 1999-03-31 | Valmet Corp | Wings arrangement for sorting device for fiber pulp |
| FI4401U1 (en) † | 1999-11-29 | 2000-04-27 | Ahlstrom Machinery Oy | Arrangement for sorting of pulp |
| FI118478B (en) * | 2006-02-10 | 2007-11-30 | Metso Paper Inc | Separator wing and sorter to sort the pulp |
| FI120978B (en) * | 2007-03-30 | 2010-05-31 | Advanced Fiber Tech Aft Trust | Rotor element for a screen device and rotor |
| FI120913B (en) | 2007-09-28 | 2010-04-30 | Andritz Oy | Device for sorting of pulp |
| FI121672B (en) | 2008-10-15 | 2011-02-28 | Advanced Fiber Tech Aft Trust | A method for manufacturing a rotor of a screening apparatus and a rotor |
| DE102009014810A1 (en) | 2009-03-25 | 2010-09-30 | Andritz Fiedler Gmbh | Flank for sorting devices, particularly for fiber suspensions in paper pulp, has outer contour facing sieve wall, where outer surface of flank has limiting edge till flank end |
| FI128147B (en) | 2012-05-25 | 2019-11-15 | Aikawa Fiber Tech Trust | A rotor element and a rotor for a screening apparatus |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE495284C (en) * | 1925-05-23 | 1930-04-04 | Samuel Milne | Method and device for sifting paper stock and like |
| US2835173A (en) * | 1955-03-03 | 1958-05-20 | Black Clawson Co | Paper machinery |
| DE1250726B (en) * | 1963-05-17 | 1967-09-21 | Canadian Ingersoll-Rand Company Limited, Montreal, Quebec (Kana da), Bird Machine Company, South Walpole, Mass (V St A) | Cleaning device for drum screens |
| DE1761853A1 (en) * | 1968-07-15 | 1971-09-02 | Feldmuehle Ag | Process for the production of flat nonwovens |
| DE2830386C2 (en) * | 1978-07-11 | 1982-09-02 | Hermann Finckh, Maschinenfabrik GmbH & Co, 7417 Pfullingen | Process for sorting fiber suspensions and pressure sorters for carrying out the process |
| DE3010952A1 (en) * | 1980-03-21 | 1981-10-08 | J.M. Voith Gmbh, 7920 Heidenheim | DISC SORTER FOR CLEANING FIBER SUSPENSIONS |
| DE3607457A1 (en) * | 1986-03-07 | 1987-09-10 | Voith Gmbh J M | SORTING SCREEN |
| DE4000248A1 (en) * | 1990-01-06 | 1991-07-11 | Emil Holz | ROTOR FOR PRESSURE SORTER FOR SORTING FIBER SUSPENSIONS |
| US5072834A (en) * | 1990-11-19 | 1991-12-17 | The Black Clawson Company | Screening apparatus for paper making stock |
| US5282579A (en) * | 1993-01-25 | 1994-02-01 | Poser Kimberly J | Apparatus for adjusting the gap of a size reduction machine |
| JP3065202B2 (en) * | 1993-10-20 | 2000-07-17 | 石川島播磨重工業株式会社 | Waste Paper Pulp Sorting Method and Apparatus |
| DE29515338U1 (en) * | 1995-09-25 | 1995-11-23 | Fiedler Heinrich Gmbh | Wings for sorting devices |
-
1995
- 1995-09-25 DE DE29515338U patent/DE29515338U1/en not_active Expired - Lifetime
-
1996
- 1996-09-24 EP EP96115317A patent/EP0764736B1/en not_active Expired - Lifetime
- 1996-09-24 DE DE59608825T patent/DE59608825D1/en not_active Expired - Lifetime
- 1996-09-24 ES ES96115317T patent/ES2173233T3/en not_active Expired - Lifetime
- 1996-09-24 AT AT96115317T patent/ATE214114T1/en active
- 1996-09-24 CA CA002186328A patent/CA2186328C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0764736A3 (en) | 1997-07-02 |
| CA2186328A1 (en) | 1997-03-26 |
| ES2173233T3 (en) | 2002-10-16 |
| DE59608825D1 (en) | 2002-04-11 |
| EP0764736A2 (en) | 1997-03-26 |
| DE29515338U1 (en) | 1995-11-23 |
| EP0764736B1 (en) | 2002-03-06 |
| ATE214114T1 (en) | 2002-03-15 |
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Legal Events
| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |