Abstract:
A screen structure which is unusually effective at removing stickies from recyclable fiber but is tolerant of substantial swings in throughput which result in variations in the flow velocity through the screen—slot velocity. One example of the screen structure is created by forming a very large number of similarly shaped vanes then locking them into a ring structure to form a cylindrical screen basket but equivalent surface configurations can also be formed into sheet stock.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. patent application Ser. No. 13/348,692, filed Jan. 12, 2012, and published as U.S. Patent Application Publication No. 2012/0181237, on Jul. 19, 2012, which is based on U.S. Provisional Patent Application No. 61/461,117, filed Jan. 13, 2011, both of which are incorporated herein by reference in their respective entireties. 
    
    
     TECHNICAL FIELD 
     Recycling is fast becoming essential for almost every recyclable commodity, yet differences between prices for commodities obtained from nature and those obtained from waste often do not economically justify use of recyclable materials. In the case of fiber obtained from recycle streams of waste paper, it is often quite difficult to render the fiber equivalent in quality to fiber obtained from virgin pulp without incurring costs exceeding the price differential between virgin fiber and the recyclable fiber contained in readily available waste streams. 
     BACKGROUND 
     Achieving virgin equivalent quality from recycled paper is increasingly difficult as fiber from lower and lower grade sources is used. Curbside recycled paper is usually considered just about the lowest possible grade of paper being recycled today. One factor which seems to contribute to the difficulty of obtaining fiber having quality equivalent to virgin fiber from curbside recycled paper is the presence of large amounts of “stickies” and other contaminants in the paper; but industrial/commercial waste papers are also becoming increasingly contaminated, especially with troublesome adhesives. Stickies commonly result from pressure sensitive labels in the waste paper but can be created by other adhesives, plastic window envelopes and the like. During the papermaking process, stickies in the furnish cause problems both by precipitating out of the furnish onto machine parts as well as by remaining in the web where they contribute to dense spots of adhesive, ink, plastic, fiber and a host of other contaminants. Stickies are especially problematic when recycle fiber is being used for tissue products as, in bath and facial tissue, each ply of tissue may only have a thickness equivalent to perhaps seven to ten layers of fiber, so the dark dense spot resulting from a stickie which finds its way into the finished sheet detracts both from the aesthetic appearance of the sheet and its functional integrity. Stickies that deposit out on machine clothing interfere with the proper movement of water and/or air through the fabric, again potentially contributing to defects in the finished product. 
     As waste paper is converted into pulp which is usable in making tissue and towel products, it is subjected to many of the same processes used with virgin pulp. In fact many mills will use a combination of virgin and recycle pulp to “dial-in” quality. This can lead to difficulties in fiber processing as many of these procedures are relatively sensitive to throughput variations. An especially important process is “screening” in which pulp is fed through a “screen” to remove dirt and other contaminants. Virtually all of the pulp fed to a papermachine will pass through a series of screens, each configured to remove contaminants progressively smaller in size than the screen before. Each screen will typically also have some means for removing contaminants lodged on the screen so that the screen does not become blocked. The term “screen” is often used both to refer to the overall apparatus used for removing impurities from pulp and for the actual perforate structure which forms the heart of that apparatus. In this application, the aggregate of those structures that form the removable perforate structure are typically referred to as the screen basket. This application relates to the perforate screen structure and more particularly to the shape of the surface of the screen structure which contacts the fiber suspension from which impurities are to be removed. Typically, foils moving relative to the screen basket are used for this purpose. These foils are hypothesized to induce negative pressure pulses that clear debris off of the screen basket so that it can pass out of the screen through a reject line. 
     SUMMARY OF THE INVENTION 
     This invention relates to a screen structure which is unusually effective at removing stickies from recyclable fiber but is tolerant of substantial swings in throughput which result in variations in the flow velocity through the screen—slot velocity. 
     In modern screens, a great deal of attention is paid both to the hydrodynamics of the flow system as it passes over the screen structure but also to the stresses imposed on the screen as it is subjected to alternating pressure pulses which temporarily induce backflow through the openings in the screen which ideally remove debris which might otherwise occlude the screen and thereby reduce the screening systems capacity. There are two primary techniques used for constructing screens. In the first, a web structure, typically a sheet of stainless steel, has a variety of inter-cooperating grooves, channels, perforations and slits formed in both of its surfaces. The sheet is then rolled into a cylindrical shape and incorporated into the screen system. In the second, a plurality of vanes are formed, often each vane will have a quite complex shape possibly including tapers, grooves, lands, relieved regions and dressed away areas so that when the vanes are assembled into a cylindrical array, precisely shaped slits are formed through the resulting cylindrical shell formed by the multitude of vanes. 
     There are advantages to each method of construction; but, in screens formed by either technique, the goal is to precisely form a surface joined to slits in parallel in which the flow of water will efficiently conduct fibers through the slits while rejecting contaminants without occluding the surface of the screen. The present invention is thought to be most easily practiced by forming a very large number of similarly shaped vanes then locking them into a ring structure to form a cylindrical screen basket but equivalent surface configurations can also be formed into sheet stock although the manufacturing cost may be higher due to the difficulties involved in forming precise slits, channels, grooves and contours in the required size. 
     While large stickies are especially problematic when they find their way into the sheet and the effect of very small stickies in the sheet itself can be difficult to detect, it is not sufficient to remove only the larger stickies at the screens as the adhesives, particularly the pressure sensitive adhesives, tend to aggregate during the papermaking process and grow into larger stickies. Accordingly, one common way of measuring the effectiveness of screening is to separately measure the total area of stickies removed in several size ranges. We prefer to analyze stickies contents in terms of the stickies content by total area in the ranges of 0.001-0.04 mm 2 , 0.04-0.3 mm 2  and over 0.3 mm 2 . In addition, it is sometimes useful to aggregate the 0.04 to 0.3 mm 2  and over 0.3 mm 2  ranges into a single category of over 0.04 mm 2 . Typically, most well designed screens are reasonably effective for stickies over ˜0.3 mm 2  in area but will have more difficulty with stickies in the two smaller ranges of 0.001-0.04 mm 2  and 0.04-0.3 mm 2 . Further, it is generally thought that there is a tradeoff between designing screens to be effective on the smaller size ranges of stickies and the amount of fiber that can be effectively cleaned by that screen in a given period. We have found that the screens of the present invention have surprising effectiveness with smaller stickies removal coupled with the ability to process large quantities of fiber over a wide range of slot velocities. It is considered quite surprising that these screens could combine the ability to both remove large fractions of the smaller stickies and process large amounts of fiber over a wide range of slot velocities. Effective removal of large stickies is, however, the sine qua non of screen design. A screen design which is not extremely effective in removing large stickies can only be employed in special circumstances. 
     We have found that surprisingly effective removal of stickies from recyclable waste can be achieved by passing pulp derived from industrial, commercial and post-consumer waste through a metallic screen basket having an accepts contacting surface approximating that of a right circular cylinder having an axis “A”, a circumference “C” and a diameter “D”, said surface comprising a plurality of sequences of facets, each sequence comprising a generally circumferentially extending facet, an upstream generally diametrally extending facet adjacent thereto, and a downstream generally diametrally extending facet adjacent thereto, each said generally circumferential facet being generally parallel to the axis “A” of the cylinder and having a leading edge and a trailing edge, each said leading edge and trailing edge as well as each said upstream generally diametrally extending facet and each said downstream generally diametrally extending facet being generally parallel to the axis “A” of the cylinder, each said leading edge being located upon a cylindrical surface S 1 , and each said trailing edge being located upon a cylindrical surface S 2 , the diametral difference “δ” between the distance from the axis “A” of the cylindrical surface S 1  from the diametral distance from the axis “A” of the cylindrical surface S 2  being between about 0.4 mm to about 0.6 mm, the normal direction to the surface of each said generally circumferential facet in each sequence of facets having a component directed toward the adjacent trailing edge of an adjacent generally circumferential facet in an adjacent sequence of facets, the angle “α” between the normal to each said generally circumferential facet and the diametral direction of said right circular cylinder being between about 80° and 76°, the distance “t” from the leading edge to the trailing edge of each said generally circumferential facet being between about 2.3 mm and 2.5 mm, the upstream generally diametrally extending facet of each sequence adjoining the leading edge of a generally circumferential facet and the downstream generally diametrally extending facet of each sequence adjoining the trailing edge, the distance between the upstream generally diametrally extending facet of each sequence and the downstream generally diametrally extending facet of the next adjacent sequence “w” being between about 0.11 and 0.14 mm, a relieved channel leading from the accepts side to the rejects side of said screen being defined between the upstream generally diametrally extending facet of each sequence and the downstream generally diametrally extending facet of the next adjacent sequence. 
     In some embodiments, the screen basket is formed from at least one unitary metallic sheet, usually of stainless steel, each sheet having a plurality of trenches formed into its surfaces and a plurality of slits formed therethrough. 
     In other embodiments, a corrosion resistant hardened surface is disposed upon said screen basket; preferably said corrosion resistant hardened surface comprises a major proportion of chromium having hardness of at least about 65 on the Rockwell C scale in a thickness of at least 0.2 mils up to about 1.0 mils. 
     Still yet other features and advantages of the invention will become apparent from the following description and appended Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in detail below with reference to the drawings wherein like numerals designate similar parts and wherein: 
         FIG. 1  is a partially cut away perspective of a known construction of a screen basket which is suitable to be adapted for practice of the present invention by replacement of the vanes therein by vanes having the configuration described herein. 
         FIG. 2  is a schematic illustration of the geometry of the supply side of a screen basket constructed from a large number of vanes. 
         FIG. 3  is a schematic illustration of a foil in relation to several vanes of a screen basket. 
         FIG. 4  is a schematic illustration of the theorized flow pattern in the neighborhood of the slits in a screen basket of the present invention. 
         FIG. 5  illustrates the distribution of stickies by size in the supply streams used in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 6  illustrates the distribution of stickies by size in the accepts streams obtained in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 7  illustrates the Average Cleanliness Efficiencies obtained for the various size ranges of stickies obtained in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 8  illustrates the relationship between the Average Cleanliness Efficiencies obtained for the various size ranges of stickies and the slot widths of the screens used in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 9  illustrates the relationship between the Average Cleanliness Efficiencies obtained for the various size ranges of stickies and the profile heights of the screens used in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 10  illustrates the relationship between the Overall Average Cleanliness Efficiencies obtained and the slot width of the screens used in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 11  illustrates the correlation obtained between the Overall Average Cleanliness Efficiencies and the slot widths and profile heights of the screens used in experiments conducted to determine the effectiveness of several screen baskets. 
         FIG. 12  sets forth both the Area % of total stickies removed and the total mass flow of the accepts streams for each of the screens evaluated with profile height being indicated for each data point. 
         FIG. 13  sets forth both the Area % of total stickies removed and the total mass flow of the accepts streams for each of the screens evaluated with accepts tonnage being indicated for each data point. 
         FIG. 14  sets forth the Area % of total stickies removed in the size range of 0.001 to 0.04 mm 2  on a grid of the slot width and profile height for each of the screens evaluated. 
         FIG. 15  sets forth the Area % of total stickies removed in the size range of 0.04 to 0.3 mm 2  on a grid of the slot width and profile height for each of the screens evaluated. 
         FIG. 16  sets forth the Area % of total stickies removed in the size range of greater than 0.04 mm 2  on a grid of the slot width and profile height for each of the screens evaluated. 
         FIG. 17  sets forth the Area % of total stickies removed in the size range of greater than 0.3 mm 2  on a grid of the slot width and profile height for each of the screens evaluated. 
         FIG. 18  illustrates the wide variations in Cleanliness Efficiencies resulting for each of the several size ranges of stickies as slot velocity was varied for a screen basket with 0.19 mm slots and a profile height of 0.6 mm. 
         FIG. 19  illustrates the significant reductions in the variations in Cleanliness Efficiencies resulting for each of the several size ranges of stickies as slot velocity was varied for a screen basket with 0.14 mm slots and a profile height of 0.51 mm. 
         FIGS. 20-24  illustrate the performance of a variety of screen designs on various size ranges of stickies as slot velocity is varied. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is described below with reference to a preferred embodiment. Such discussion is for purposes of illustration only. Modifications to particular examples within the spirit and scope of the present invention, set forth in the appended claims, will be readily apparent to one of skill in the art. 
     Terminology used herein is given its ordinary meaning unless otherwise indicated. 
       FIG. 1  illustrates a screen basket  30  comprised of a very large number of longitudinally extending vanes  32  defining longitudinally extending slits  34  therebetween, vanes  32  being held between flanges  36  joined by longitudinally extending rods  38 . Vanes  32  are reinforced by circumferential ribs  40 . This overall method of construction is known from U.S. Pat. No. RE 38,738 E and is well suited to receive and retain vanes  32  as described herein. 
       FIG. 2  (with periodic reference to  FIGS. 1 and 3 ) illustrates the cross-section of several vanes  32  of the present invention. Each vane  32  has three facets: downstream generally diametrally extending facet  42 , generally circumferentially extending facet  44  and upstream generally diametrally extending facet  46 . Upstream generally diametrally extending facet  46  adjoins generally circumferentially extending facet  44  at leading edge  48  while downstream generally diametrally extending facet  42  adjoins generally circumferentially extending facet  44  at trailing edge  50  which preferably has a radius of curvature of about 0.6 mm. On each vane  32 , centerline             extends toward geometrical axis “A” of screen basket  30 . Leading edge  48  of each vane  32  lies upon imaginary cylindrical surface S 1  while each trailing edge  50  lies upon imaginary cylindrical surface S 2 , spaced a distance “δ” of between 0.4 mm and 0.6 mm from imaginary cylindrical surface S 1 , this distance being referred to as the profile height. Each generally circumferentially extending facet  44  has a thickness “t” of between about 2.3 and 2.5 mm and is inclined toward the upstream at an angle “α” of between about 76° and 80° its respective diametrally extending centerline          . Slit  52  having a width “w” of between about 0.11 mm and 0.145 mm is defined between upstream generally diametrally extending facet  46  of each vane  32  and downstream generally diametrally extending facet  42  of the next vane upstream therefrom. Together the downstream generally diametrally extending facet  42 , trailing edge  50 , generally circumferentially extending facet  44  and upstream generally diametrally extending facet  46  collectively define the supply contacting surface  54  of screen basket  30 .
       FIG. 3  illustrates foil  56  having leading edge  58  and trailing edge  60  defined thereupon. As leading edge  58  of foil  56  passes over each slit  52 , it is theorized that it introduces a negative pressure upon the slit it is passing over tending to clear the slit of stickies and other debris that may be deposited there, while the positive pressure resulting after trailing edge  60  of foil  56  passes over slit  52  tends to drag fiber therethrough while incidentally forcing stickies and other debris against rejects supply contacting surface  54  of screen basket  30  ( FIG. 1 ), there to remain until passage of a successive foil  56  induces negative pressure to dislodge stickies and debris. In conventional practice, the clearance between the supply contacting surface  54  and foil  56  is a small fraction of an inch or just a few millimeters. 
       FIG. 4  illustrates the hypothetical formation of vortices  62  as flow passes over trailing edge  50  of each vane  32 . Some have theorized that proper formation of vortices  62  helps to align fibers with slit  52  easing the passage of longer fibers through slit  52 . Others have hypothesized that proper formation of vortices ameliorates the formation of deposits between the slits of the screen. 
     Six different screen baskets having the general configuration illustrated in  FIG. 1  were evaluated with recycled fiber samples collected from industrial, commercial and post-consumer waste pulp recycling operations. The slot width and profile height for each of the screen baskets, as reported by the manufacturers, are set forth in Table 1. Upon microscopic inspection, it was determined that the geometry of the screen baskets varied considerably from that stated by the manufacturer in several cases. Table 1 compares the Actual Screen Basket Geometry to that reported by the manufacturers. 
     
       
         
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Reported Screen 
                 Actual Screen 
               
               
                   
                 Basket Specifications 
                 Basket Geometry 
               
             
          
           
               
                 Screen 
                 Slot 
                 Profile 
                 Slot 
                 Profile 
               
               
                 Basket Label 
                 Width, mm 
                 Height, mm 
                 Width, mm 
                 Height, mm 
               
               
                   
               
               
                 A 
                 0.10 
                 0.9 
                 0.11 
                 0.90 
               
               
                 V-1 
                 0.11 
                 0.7 
                 0.11 
                 0.70 
               
               
                 V-2 
                 0.12 
                 0.5 
                 0.13 
                 0.50 
               
               
                 V-3 
                 0.15 
                 0.7 
                 0.16 
                 0.67 
               
               
                 V-4 
                 0.15 
                 0.7 
                 0.14 
                 0.51 
               
               
                 V-5 
                 0.15 
                 0.7 
                 0.19 
                 0.62 
               
               
                   
               
             
          
         
       
     
     Over a period of several months, the screen baskets were evaluated with pulp samples having average stickies contents and size variations as set forth in Table 2. 
     
       
         
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                   
                 Supply Stickies (per 100 OD g basis) 
               
             
          
           
               
                   
                 0.001-0.04 
                   
                 0.04-0.3 
                   
               
               
                   
                 mm 2   
                 &gt;0.04 mm 2   
                 mm 2   
                 &gt;0.3 mm 2   
               
             
          
           
               
                   
                 Count 
                 Area 
                 Count 
                 Area 
                 Count 
                 Area 
                 Count 
                 Area 
               
               
                   
               
             
          
           
               
                 A 
                 3,571 
                 28.5 
                 1,859 
                 474.7 
                 1,494 
                 185.3 
                 365 
                 289.4 
               
               
                 V-1 
                 2,076 
                 16.9 
                 1,152 
                 305.6 
                 936 
                 117.3 
                 216 
                 188.3 
               
               
                 V-2 
                 4,674 
                 40.0 
                 2,830 
                 739.2 
                 2,262 
                 282.1 
                 568 
                 457.1 
               
               
                 V-3 
                 2,650 
                 43.2 
                 2,957 
                 680.2 
                 2,448 
                 305.5 
                 509 
                 374.7 
               
               
                 V-4 
                 3,805 
                 30.6 
                 1,997 
                 473.2 
                 1,672 
                 208.2 
                 325 
                 265.0 
               
               
                 V-5 
                 5,090 
                 20.5 
                 1,355 
                 381.5 
                 1,064 
                 135.5 
                 291 
                 246.0 
               
               
                   
               
             
          
         
       
     
     On a gross basis the results obtained are set forth in the two parts of Table 3. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
             
             
               
                 (part 1) 
               
             
          
           
               
                   
                   
                 Supply 
                 Accepts 
                 Rejects 
                 Mass Flow 
                   
               
             
          
           
               
                   
                 Reject 
                 % 
                 % 
                 % 
                   
                 % 
                 % 
                 % 
                   
                 % 
                 % 
                 % 
                 (ODSTPD) 
                 Production 
               
             
          
           
               
                   
                 Ratio 
                 TSS  
                 Ash 
                 Cons  
                 GPM 
                 TSS 
                 Ash 
                 Cons 
                 GPM 
                 TSS 
                 Ash 
                 Cons  
                 Accept 
                 Rejects 
                 Supply 
                 ODSTPD 
               
               
                   
               
               
                 A 
                 0.16 
                 1.10 
                  6.88 
                 1.02 
                 3,466 
                 0.99 
                 7.39 
                 0.94 
                 565 
                 1.51 
                 5.66 
                 1.40 
                 213 
                 50 
                 263 
                 373 
               
               
                 V-1 
                 0.14 
                 1.08 
                 86.95  
                 1.01 
                 3,527 
                 1.01 
                 7.42 
                 0.94  
                 494 
                 1.41 
                 5.67 
                 1.33 
                 214 
                 42 
                 256 
                 366 
               
               
                 V-2 
                 0.20 
                 1.17 
                  7.41 
                 1.09 
                 3,536 
                 1.10 
                 7.58 
                 1.02 
                 704 
                 1.51 
                 5.98  
                 1.42 
                 235 
                 64 
                 299 
                 393 
               
               
                 V-3 
                 0.14 
                 1.05 
                  5.82 
                 0.99  
                 3,665 
                 1.00 
                 6.07 
                 0.94 
                 512 
                 1.49 
                 4.64  
                 1.42 
                 220 
                 46 
                 266 
                 386 
               
               
                 V-4 
                 0.14 
                 1.09 
                  7.29  
                 1.01 
                 3,716 
                 1.03  
                 7.45 
                 0.95  
                 520 
                 1.45 
                 6.06  
                 1.36 
                 230 
                 45 
                 275 
                 393 
               
               
                 V-5 
                 0.14 
                 1.08 
                  7.39  
                 1.00 
                 3,574 
                 1.04  
                 7.52 
                 0.96  
                 501 
                 1.35 
                 6.26  
                 1.26 
                 224 
                 41 
                 265 
                 375 
               
               
                   
               
             
          
           
               
                 (part 2) 
               
             
          
           
               
                   
                 Thickening Factor 
                 Vol. Reject Rate, % 
                 OD Reject Rate, % 
                 Slot Vel. m/s 
               
               
                   
               
               
                 A 
                 1.36 
                 14.0 
                 19.0 
                 1.29 
               
               
                 V-1 
                 1.31 
                 12.3 
                 16.4 
                 1.38 
               
               
                 V-2 
                 1.29 
                 16.6 
                 21.5 
                 1.52 
               
               
                 V-3 
                 1.42 
                 12.3 
                 17.3 
                 1.58 
               
               
                 V-4 
                 1.33 
                 12.3 
                 16.5 
                 1.60 
               
               
                 V-5 
                 1.25 
                 12.3 
                 15.4 
                 1.54 
               
               
                   
               
             
          
         
       
     
     The accepts stream samples from the screen were evaluated for stickies content with average results as set forth in Table 4. 
     
       
         
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                   
                 Accepts Stickies (per 100 OD g basis) 
               
             
          
           
               
                   
                 0.001-0.04 
                   
                 0.04-0.3 
                   
               
               
                   
                 mm 2   
                 &gt;0.04 mm 2   
                 mm 2   
                 &gt;0.3 mm 2   
               
             
          
           
               
                   
                 Count 
                 Area 
                 Count 
                 Area 
                 Count 
                 Area 
                 Count 
                 Area 
               
               
                   
               
             
          
           
               
                 A 
                 1,973 
                 16.7 
                 969 
                 123.7 
                 927 
                 105.2 
                 42 
                 18.5 
               
               
                 V-1 
                 1,388 
                 10.2 
                 493 
                 59.1 
                 476 
                 52.2 
                 17 
                 6.8 
               
               
                 V-2 
                 1,734 
                 16.4 
                 896 
                 103.0 
                 876 
                 91.2 
                 20 
                 11.8 
               
               
                 V-3 
                 2,717 
                 24.9 
                 1,520 
                 172.0 
                 1,490 
                 160.5 
                 30 
                 11.5 
               
               
                 V-4 
                 1,537 
                 12.1 
                 632 
                 72.5 
                 619 
                 66.4 
                 12 
                 6.1 
               
               
                 V-5 
                 1,595 
                 13.0 
                 854 
                 120.6 
                 801 
                 98.1 
                 54 
                 22.5 
               
               
                   
               
             
          
         
       
     
     From these results, cleanliness efficiencies were obtained on both a number basis and an area basis as set forth in the three parts of Table 5. These results are also presented graphically in  FIGS. 5-10  while  FIG. 11  presents a correlation between slot width, profile height and average cleanliness efficiency. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
             
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
               
                   
               
             
             
               
                 (part 1) 
               
             
          
           
               
                   
                 Cleanliness Efficiency (Area) 
                 Cleanliness Efficiency (Count) 
               
             
          
           
               
                   
                 &gt;0.04 mm 2 , % 
                 0.04-0.3 mm 2 , % 
                 &gt;0.3 mm 2 , % 
                 &gt;0.04 mm 2 , % 
                 0.04-0.3 mm 2 , % 
                 &gt;0.3 mm 2 , % 
               
               
                   
               
               
                 A 
                 74.4 
                 40 
                 94 
                 49.1 
                 39 
                 89 
               
               
                 V-1 
                 81.6 
                 50 
                 96 
                 58.7 
                 50 
                 93 
               
               
                 V-2 
                 85.1 
                 59 
                 97 
                 66.8 
                 59 
                 96 
               
               
                 V-3 
                 75.0 
                 49 
                 97 
                 49.7 
                 41 
                 94 
               
               
                 V-4 
                 84.6 
                 67 
                 98 
                 68.2 
                 63 
                 96 
               
               
                 V-5 
                 68.5 
                 28 
                 91 
                 37.7 
                 25 
                 83 
               
               
                   
               
             
          
           
               
                 (part 2) 
               
               
                   
               
             
          
           
               
                   
                 Capacity 
                 Stickies 
                   
               
             
          
           
               
                   
                 Tons 
                 Tons 
                 Total 
                   
                   
               
               
                 Screen 
                 per 
                 per 
                 area of 
                 Area % 
                   
               
             
          
           
               
                   
                 Slot 
                 Profile 
                 day in 
                 day in 
                 Stickies 
                 Stickies 
                 Cleanliness 
               
               
                   
                 Width, 
                 Height, 
                 Accept 
                 Supply 
                 in 
                 Removal 
                 Efficiency (Area) 
               
             
          
           
               
                   
                 mm 
                 mm 
                 Stream 
                 Stream 
                 Supply 
                 Efficiency 
                 &gt;0.04 mm 2 , % 
                 0.04-0.3 mm 2 , % 
                 &gt;0.3 mm 2 , % 
               
               
                   
               
               
                 A-1 
                 0.11 
                 0.90 
                 213 
                 263 
                 688.6 
                 61.7 
                 74.4 
                 40 
                 94 
               
               
                 V-1 
                 0.11 
                 0.70 
                 214 
                 256 
                 439.7 
                 70.8 
                 81.6 
                 50 
                 96 
               
               
                 V-2 
                 0.13 
                 0.50 
                 235 
                 299 
                 1061.3 
                 79.0 
                 85.1 
                 59 
                 97 
               
               
                 V-3 
                 0.16 
                 0.67 
                 220 
                 266 
                 1028.9 
                 64.1 
                 75 
                 49 
                 97 
               
               
                 V-4 
                 0.14 
                 0.51 
                 230 
                 275 
                 712.0 
                 77.9 
                 84.6 
                 67 
                 98 
               
               
                 V-5 
                 0.19 
                 0.62 
                 224 
                 265 
                 537.4 
                 527 
                 68.5 
                 28 
                 91 
               
               
                   
               
             
          
         
       
     
       FIGS. 12-17  graphically present relationships between slot width, profile height and stickies removal with tonnage production being noted for each case. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 (part 3) 
               
             
          
           
               
                   
                 Stickies 
                   
                   
               
               
                 Screen 
                 Total area of 
                 Total area of 
                 Area % Stickies 
               
             
          
           
               
                   
                 Slot 
                 Profile 
                 Stickies in Supply 
                 Stickies in Accepts 
                 Removal Efficiency 
               
               
                   
                 Width, mm 
                 Height, mm 
                 0.001-0.04 mm 2   
                 0.001-0.04 mm 2   
                 0.001-0.04 mm 2   
               
               
                   
                   
               
             
          
           
               
                 A-1 
                 0.11 
                 0.90 
                 28.5 
                 16.7 
                 41.4% 
               
               
                 V-1 
                 0.11 
                 0.70 
                 16.9 
                 10.2 
                 39.6% 
               
               
                 V-2 
                 0.13 
                 0.50 
                 40.0 
                 16.4 
                     59% 
               
               
                 V-3 
                 0.16 
                 0.67 
                 43.2 
                 24.9 
                 42.4% 
               
               
                 V-4 
                 0.14 
                 0.51 
                 30.6 
                 12.1 
                 60.5% 
               
               
                 V-5 
                 0.19 
                 0.62 
                 20.5 
                 13.0 
                 36.6% 
               
               
                   
               
             
          
         
       
     
     As the demand on the fiber processing lines typically varies from time to time depending upon the paper machine needs, it is quite advantageous for a screen design to be able to provide a relatively consistent output over a range of throughputs. To demonstrate the ability of screen designs of the present invention to handle variations in throughputs, during the series of trials above, the performance of the screen was recorded as the slot velocity was varied. The following tables (Tables 6-11) record the Cleanliness Efficiencies of the several screen designs set forth over a range of slot velocities. 
     Example 1 
     Comparative 
     Table 6 describes the performance of a screen, not of the present invention, in the above-described evaluation.  FIG. 18  sets forth those results graphically. It can be appreciated that not only are the efficiencies rather low but that they vary widely as slot velocity is varied, making it quite difficult to reliably control the input to the papermaking process as demand for fiber is varied. (Throughout the Examples, where the last line of a table is separated from the lines above it by a heavy horizontal line, the values in that last line are averages of the figures above in that table.) 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Screen Basket V-5 - Slot Width 0.19 mm/Profile Height 0.62 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
             
          
           
               
                   
                 1.28 
                 67.3 
                 33.3 
                 91.7 
               
               
                   
                 1.27 
                 69.5 
                 35.3 
                 95.4 
               
               
                   
                 1.28 
                 68.7 
                 5.2 
                 95.1 
               
               
                   
                 1.29 
                 75.5 
                 24.1 
                 93.9 
               
               
                   
                 1.28 
                 74.6 
                 40.0 
                 90.2 
               
               
                   
                 1.28 
                 77.3 
                 38.7 
                 93.8 
               
               
                   
                 1.16 
                 76.5 
                 44.3 
                 93.3 
               
               
                   
                 1.16 
                 58.5 
                 16.4 
                 86.0 
               
               
                   
                 1.19 
                 43.6 
                 −5.0 
                 82.7 
               
               
                   
                 1.20 
                 69.1 
                 27.7 
                 91.5 
               
               
                   
                 1.20 
                 65.0 
                 25.6 
                 82.8 
               
               
                   
                 1.20 
                 51.9 
                 31.2 
                 65.7 
               
               
                   
                 1.16 
                 49.5 
                 23.0 
                 84.8 
               
               
                   
                 1.16 
                 70.3 
                 7.2 
                 95.5 
               
               
                   
                 1.18 
                 76.5 
                 45.2 
                 91.1 
               
               
                   
                 1.17 
                 66.0 
                 18.0 
                 88.0 
               
               
                   
                 1.17 
                 76.2 
                 27.0 
                 94.0 
               
               
                   
                 1.17 
                 72.1 
                 43.4 
                 93.2 
               
               
                   
                 1.15 
                 79.6 
                 33.4 
                 96.4 
               
               
                   
                 1.22 
                 58.9 
                 29.3 
                 80.6 
               
               
                   
                 1.16 
                 72.0 
                 −2.3 
                 95.4 
               
               
                   
                 1.16 
                 68.2 
                 13.8 
                 92.6 
               
               
                   
                 1.19 
                 75.1 
                 37.2 
                 91.8 
               
               
                   
                 1.19 
                 80.5 
                 43.3 
                 92.9 
               
               
                   
                 1.29 
                 71.1 
                 45.3 
                 97.1 
               
               
                   
                 1.28 
                 68.2 
                 33.9 
                 90.3 
               
               
                   
                 1.15 
                 62.1 
                 8.9 
                 92.9 
               
               
                   
                 1.16 
                 56.0 
                 16.7 
                 87.0 
               
               
                   
                 1.23 
                 47.9 
                 4.3 
                 81.2 
               
               
                   
                 1.22 
                 52.5 
                 7.4 
                 87.2 
               
               
                   
                 1.19 
                 68.6 
                 48.7 
                 90.8 
               
               
                   
                 1.20 
                 52.1 
                 32.5 
                 79.9 
               
               
                   
                 1.22 
                 79.3 
                 56.0 
                 93.3 
               
               
                   
                 1.22 
                 79.0 
                 45.7 
                 96.6 
               
               
                   
                 1.28 
                 83.8 
                 23.5 
                 98.4 
               
               
                   
                 1.29 
                 75.2 
                 44.9 
                 89.5 
               
               
                   
                 1.16 
                 62.3 
                 7.8 
                 96.2 
               
               
                   
                 1.16 
                 86.0 
                 42.9 
                 98.3 
               
               
                   
                 1.18 
                 78.0 
                 57.4 
                 92.7 
               
               
                   
                 1.17 
                 74.0 
                 19.8 
                 95.3 
               
               
                   
                 1.32 
                 78.3 
                 39.3 
                 95.1 
               
               
                   
                 1.33 
                 69.1 
                 46.2 
                 93.9 
               
               
                   
                 1.34 
                 66.7 
                 23.9 
                 91.5 
               
               
                   
                 1.35 
                 59.5 
                 9.7 
                 88.9 
               
               
                   
                 1.22 
                 68.5 
                 28.4 
                 90.8 
               
               
                   
                   
               
             
          
         
       
     
     Example 2 
     Table 7 sets forth results obtained with a screen which was found to be performing exceptionally well for unknown reasons. Upon close examination, it was determined that not only did it not match the specifications from the factory but it appeared that it had most likely worn considerably from its initial configuration. As the slot width was narrower than manufacturer&#39;s specification, it was considered apparent however that not all of the variation could be due to wear.  FIG. 19  presents the results obtained with this screen graphically. It can be appreciated that the average efficiencies are not only very high but the results remain quite consistent over a wide range of slot velocities. These results led the present inventors to determine whether the outstanding and unexplained performance of this screen could be duplicated by manufacturing a screen with the same slot width and profile height. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Screen Basket V-4 - Slot Width 0.14 mm/Profile Height 0.51 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
             
          
           
               
                   
                 1.74 
                 80.8 
                 56.8 
                 98.5 
               
               
                   
                 1.73 
                 80.5 
                 50.4 
                 98.7 
               
               
                   
                 1.75 
                 81.6 
                 50.8 
                 96.8 
               
               
                   
                 1.74 
                 94.6 
                 73.5 
                 99.0 
               
               
                   
                 1.75 
                 88.3 
                 68.3 
                 98.3 
               
               
                   
                 1.75 
                 90.9 
                 75.7 
                 95.3 
               
               
                   
                 1.58 
                 93.8 
                 83.2 
                 100.0 
               
               
                   
                 1.58 
                 85.6 
                 70.1 
                 99.0 
               
               
                   
                 1.61 
                 89.5 
                 76.4 
                 96.3 
               
               
                   
                 1.61 
                 92.6 
                 78.4 
                 99.5 
               
               
                   
                 1.60 
                 81.3 
                 42.7 
                 99.4 
               
               
                   
                 1.63 
                 82.9 
                 63.4 
                 100.0 
               
               
                   
                 1.58 
                 85.7 
                 63.8 
                 97.1 
               
               
                   
                 1.58 
                 88.7 
                 73.7 
                 96.9 
               
               
                   
                 1.68 
                 86.7 
                 71.8 
                 97.4 
               
               
                   
                 1.67 
                 89.5 
                 71.3 
                 99.7 
               
               
                   
                 1.85 
                 84.8 
                 78.4 
                 98.6 
               
               
                   
                 1.85 
                 86.2 
                 76.1 
                 99.4 
               
               
                   
                 1.86 
                 81.3 
                 71.6 
                 99.1 
               
               
                   
                 1.86 
                 81.8 
                 66.6 
                 97.0 
               
               
                   
                 1.67 
                 87.1 
                 69.3 
                 100.0 
               
               
                   
                 1.67 
                 82.2 
                 65.2 
                 99.4 
               
               
                   
                 1.67 
                 78.9 
                 67.7 
                 97.6 
               
               
                   
                 1.67 
                 83.5 
                 73.3 
                 95.7 
               
               
                   
                 2.04 
                 83.6 
                 68.9 
                 97.1 
               
               
                   
                 2.04 
                 50.0 
                 30.0 
                 79.8 
               
               
                   
                 2.03 
                 80.4 
                 66.6 
                 96.4 
               
               
                   
                 2.05 
                 87.7 
                 75.3 
                 98.6 
               
               
                   
                 1.58 
                 86.6 
                 65.1 
                 98.4 
               
               
                   
                 1.58 
                 86.6 
                 68.6 
                 98.6 
               
               
                   
                 1.58 
                 86.3 
                 73.0 
                 98.4 
               
               
                   
                 1.57 
                 85.7 
                 68.9 
                 99.0 
               
               
                   
                 1.72 
                 84.6 
                 67.3 
                 97.7 
               
               
                   
                   
               
             
          
         
       
     
     Example 3 
     Table 8 presents the results obtained with a screen of the present invention, V-2 which attempted to achieve the same slot width and profile as found in screen V-4. The results obtained are presented graphically in  FIG. 20 . From these results, it can be appreciated that screen V-2 largely replicates the benefits of screen V-4. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Screen Basket V-2 - Slot Width 0.13 mm/Profile Height 0.5 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
             
          
           
               
                   
                 1.34 
                 88.3 
                 65.6 
                 98.6 
               
               
                   
                 1.35 
                 84.1 
                 65.5 
                 99.4 
               
               
                   
                 1.38 
                 75.5 
                 35.1 
                 98.9 
               
               
                   
                 1.44 
                 80.2 
                 36.0 
                 100.0 
               
               
                   
                 1.35 
                 88.7 
                 57.9 
                 98.7 
               
               
                   
                 1.35 
                 91.7 
                 74.4 
                 98.4 
               
               
                   
                 1.45 
                 77.6 
                 40.2 
                 97.3 
               
               
                   
                 1.48 
                 86.0 
                 67.1 
                 99.2 
               
               
                   
                 1.42 
                 82.9 
                 57.8 
                 90.1 
               
               
                   
                 1.41 
                 85.1 
                 62.9 
                 92.6 
               
               
                   
                 1.40 
                 87.0 
                 71.3 
                 99.5 
               
               
                   
                 1.30 
                 89.9 
                 71.6 
                 98.5 
               
               
                   
                 1.44 
                 88.0 
                 61.6 
                 98.8 
               
               
                   
                 1.45 
                 91.0 
                 65.8 
                 100.0 
               
               
                   
                 1.44 
                 78.5 
                 46.4 
                 95.2 
               
               
                   
                 1.55 
                 88.8 
                 73.7 
                 97.9 
               
               
                   
                 1.35 
                 89.6 
                 62.3 
                 98.1 
               
               
                   
                 1.35 
                 79.5 
                 54.4 
                 92.0 
               
               
                   
                 1.40 
                 85.1 
                 59.4 
                 97.4 
               
               
                   
                   
               
             
          
         
       
     
     Example 4 
     Comparative 
     Table 9 sets forth the results obtained with another screen V-1, not of the invention, while those results are presented graphically in  FIG. 21 . While the results are somewhat consistent with slot velocity, it can be appreciated from  FIG. 21 , that the efficiency of Screen V-1 is far inferior to screens of the present invention. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Screen Basket V-1 - Slot Width 0.11 mm/Profile Height 0.7 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
             
          
           
               
                   
                 1.33 
                 80.5 
                 47.9 
                 96.6 
               
               
                   
                 1.33 
                 74.6 
                 37.1 
                 90.3 
               
               
                   
                 1.40 
                 73.4 
                 49.9 
                 92.2 
               
               
                   
                 1.41 
                 64.3 
                 36.6 
                 89.0 
               
               
                   
                 1.37 
                 91.0 
                 66.2 
                 100.0 
               
               
                   
                 1.38 
                 73.8 
                 45.9 
                 96.0 
               
               
                   
                 1.41 
                 85.5 
                 55.4 
                 97.1 
               
               
                   
                 1.41 
                 84.1 
                 55.0 
                 96.1 
               
               
                   
                 1.47 
                 88.7 
                 62.5 
                 96.9 
               
               
                   
                 1.47 
                 88.5 
                 52.8 
                 100.0 
               
               
                   
                 1.33 
                 92.5 
                 59.5 
                 100.0 
               
               
                   
                 1.33 
                 78.7 
                 30.1 
                 98.8 
               
               
                   
                 1.36 
                 80.4 
                 50.1 
                 96.1 
               
               
                   
                 1.34 
                 86.1 
                 52.9 
                 98.9 
               
               
                   
                 1.38 
                 81.6 
                 50.1 
                 96.3 
               
               
                   
                   
               
             
          
         
       
     
     Example 5 
     Comparative 
     Table 10 presents the results obtained on another screen, V-3 not of the invention, while those results are presented graphically in  FIG. 22 . While the results are somewhat consistent with slot velocity, it can be appreciated from  FIG. 22 , that the efficiency of Screen V-3 is inferior to screens of the present invention. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 Screen Basket V-3 - Slot Width 0.16 mm/Profile Height 0.67 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
             
          
           
               
                   
                 1.53 
                 79.1 
                 63.3 
                 96.0 
               
               
                   
                 1.52 
                 80.0 
                 47.1 
                 98.0 
               
               
                   
                 1.52 
                 74.0 
                 52.1 
                 93.9 
               
               
                   
                 1.53 
                 75.9 
                 56.4 
                 98.0 
               
               
                   
                 1.45 
                 82.3 
                 58.9 
                 96.9 
               
               
                   
                 1.45 
                 75.7 
                 52.6 
                 96.1 
               
               
                   
                 1.45 
                 72.2 
                 48.0 
                 95.5 
               
               
                   
                 1.45 
                 65.7 
                 41.2 
                 92.5 
               
               
                   
                 1.62 
                 75.8 
                 38.3 
                 97.8 
               
               
                   
                 1.62 
                 69.3 
                 40.2 
                 97.0 
               
               
                   
                 1.61 
                 78.8 
                 53.4 
                 95.9 
               
               
                   
                 1.61 
                 73.2 
                 48.6 
                 95.1 
               
               
                   
                 1.38 
                 75.5 
                 46.0 
                 97.3 
               
               
                   
                 1.39 
                 72.2 
                 41.6 
                 97.1 
               
               
                   
                 1.39 
                 73.2 
                 49.3 
                 96.1 
               
               
                   
                 1.39 
                 70.3 
                 40.0 
                 97.2 
               
               
                   
                 1.44 
                 75.2 
                 46.0 
                 98.8 
               
               
                   
                 1.43 
                 81.3 
                 52.6 
                 99.0 
               
               
                   
                 1.44 
                 74.8 
                 47.0 
                 98.5 
               
               
                   
                 1.43 
                 76.0 
                 53.3 
                 98.7 
               
               
                   
                 1.48 
                 75.0 
                 48.8 
                 96.8 
               
               
                   
                   
               
             
          
         
       
     
     Example 6 
     Comparative 
     Table 11 presents the results obtained on another screen, A-1 not of the invention, while those results are presented graphically in  FIG. 23 . It can be appreciated that the results are somewhat inconsistent with slot velocity. It can also be appreciated from  FIG. 23 , that the efficiency of Screen A-1 is quite low for this type of fiber. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Screen Basket A-1 - Slot Width 0.11 mm/Profile Height 0.9 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
             
          
           
               
                   
                 1.16 
                 80.4 
                 46.1 
                 97.3 
               
               
                   
                 1.15 
                 77.6 
                 39.0 
                 96.8 
               
               
                   
                 1.18 
                 63.8 
                 29.1 
                 82.9 
               
               
                   
                 1.19 
                 62.2 
                 32.0 
                 87.1 
               
               
                   
                 1.20 
                 78.7 
                 37.2 
                 96.4 
               
               
                   
                 1.20 
                 70.9 
                 32.2 
                 94.8 
               
               
                   
                 1.15 
                 65.7 
                 50.0 
                 88.2 
               
               
                   
                 1.15 
                 87.0 
                 54.9 
                 99.2 
               
               
                   
                 1.17 
                 83.3 
                 53.2 
                 95.4 
               
               
                   
                 1.17 
                 76.8 
                 51.0 
                 95.0 
               
               
                   
                 1.16 
                 75.3 
                 52.5 
                 96.1 
               
               
                   
                 1.16 
                 88.0 
                 64.6 
                 98.0 
               
               
                   
                 1.15 
                 84.6 
                 61.1 
                 98.7 
               
               
                   
                 1.22 
                 80.6 
                 45.6 
                 97.1 
               
               
                   
                 1.15 
                 84.2 
                 63.3 
                 98.2 
               
               
                   
                 1.15 
                 65.9 
                 41.3 
                 85.2 
               
               
                   
                 1.18 
                 83.0 
                 62.4 
                 93.9 
               
               
                   
                 1.18 
                 87.1 
                 53.7 
                 99.1 
               
               
                   
                 1.28 
                 73.8 
                 38.2 
                 95.4 
               
               
                   
                 1.27 
                 80.3 
                 56.2 
                 95.6 
               
               
                   
                 0.98 
                 86.7 
                 56.0 
                 100.0 
               
               
                   
                 0.98 
                 83.0 
                 65.7 
                 96.5 
               
               
                   
                 0.98 
                 81.2 
                 41.1 
                 97.1 
               
               
                   
                 0.98 
                 75.6 
                 33.2 
                 98.5 
               
               
                   
                 1.15 
                 83.8 
                 67.7 
                 97.7 
               
               
                   
                 1.15 
                 75.4 
                 44.4 
                 96.4 
               
               
                   
                 1.17 
                 84.3 
                 63.9 
                 98.7 
               
               
                   
                 1.18 
                 81.3 
                 42.7 
                 99.4 
               
               
                   
                 1.17 
                 74.9 
                 38.8 
                 98.8 
               
               
                   
                 1.18 
                 66.5 
                 38.1 
                 95.4 
               
               
                   
                 1.15 
                 67.9 
                 27.4 
                 92.9 
               
               
                   
                 1.16 
                 65.7 
                 20.0 
                 95.4 
               
               
                   
                 1.21 
                 64.3 
                 29.0 
                 93.1 
               
               
                   
                 1.21 
                 79.2 
                 45.2 
                 95.8 
               
               
                   
                 1.14 
                 73.1 
                 29.2 
                 94.1 
               
               
                   
                 1.15 
                 48.8 
                 15.6 
                 85.6 
               
               
                   
                 1.28 
                 74.4 
                 31.8 
                 95.4 
               
               
                   
                 1.26 
                 74.9 
                 42.0 
                 98.0 
               
               
                   
                 1.14 
                 68.4 
                 17.1 
                 93.1 
               
               
                   
                 1.15 
                 43.8 
                 −32.1 
                 77.4 
               
               
                   
                 1.24 
                 64.7 
                 26.9 
                 94.8 
               
               
                   
                 1.23 
                 68.1 
                 34.6 
                 95.9 
               
               
                   
                 1.27 
                 76.5 
                 40.4 
                 92.6 
               
               
                   
                 1.27 
                 81.7 
                 46.2 
                 96.6 
               
               
                   
                 1.22 
                 72.5 
                 43.5 
                 96.0 
               
               
                   
                 1.16 
                 76.1 
                 27.6 
                 96.4 
               
               
                   
                 1.14 
                 74.1 
                 22.4 
                 94.4 
               
               
                   
                 1.28 
                 83.0 
                 51.6 
                 97.1 
               
               
                   
                 1.28 
                 65.9 
                 27.0 
                 88.6 
               
               
                   
                 1.26 
                 73.8 
                 45.5 
                 91.1 
               
               
                   
                 1.15 
                 76.2 
                 35.1 
                 92.4 
               
               
                   
                 1.16 
                 55.6 
                 3.4 
                 81.7 
               
               
                   
                 1.17 
                 74.4 
                 40.1 
                 94.4 
               
               
                   
                   
               
             
          
         
       
     
     The results of the preceding Examples 1-6 can be summarized in the following set of Tables 12-17 which are graphically represented in  FIG. 24 . 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 12 
               
             
             
               
                   
               
               
                 Example 1 (Comparative) 
               
               
                 Averages from Table 6 
               
               
                 Screen Basket V-5 - Slot Width 0.19 mm/Profile Height 0.62 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
               
                   
                 1.22 
                 68.5 
                 28.4 
                 90.8 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 13 
               
             
             
               
                   
               
               
                 Example 2 
               
               
                 Averages from Table 7 
               
               
                 Screen Basket V-4 - Slot Width 0.14 mm/Profile Height 0.51 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
               
                   
                 1.72 
                 84.6 
                 67.3 
                 97.7 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 14 
               
             
             
               
                   
               
               
                 Example 3 
               
               
                 Averages from Table 8 
               
               
                 Screen Basket V-2 - Slot width 0.13 mm/Profile Height 0.5 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
               
                   
                 1.40 
                 85.1 
                 59.4 
                 97.4 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 15 
               
             
             
               
                   
               
               
                 Example 4 (Comparative) 
               
               
                 Averages from Table 9 
               
               
                 Screen Basket V-1 - Slot Width 0.11 mm/Profile Height 0.7 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
               
                   
                 1.38 
                 81.6 
                 50.1 
                 96.3 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 16 
               
             
             
               
                   
               
               
                 Example 5 (Comparative) 
               
               
                 Averages from Table 10 
               
               
                 Screen Basket V-3 - Slot Width 0.16 mm/Profile Height 0.67 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot Velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
               
                   
                 1.48 
                 75.0 
                 48.8 
                 96.8 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 17 
               
             
             
               
                   
               
               
                 Example 6 (Comparative) 
               
               
                 Averages from Table 11 
               
               
                 Screen Basket A-1 - Slot width 0.11 mm/Profile Height 0.9 mm 
               
             
          
           
               
                   
                   
                 Cleanliness Efficiencies (%) 
               
               
                   
                 Slot velocity 
                 Stickies Area Size Ranges 
               
             
          
           
               
                   
                 (m/s) 
                 &gt;0.04 mm 2   
                 0.04-0.3 mm 2   
                 &gt;0.3 mm 2   
               
               
                   
                   
               
               
                   
                 1.17 
                 74.4 
                 40.1 
                 94.4 
               
               
                   
                   
               
             
          
         
       
     
     It can be appreciated from Tables 12-17 and  FIG. 24  that the cleanliness efficiencies for stickies are quite sensitive to even small variations in slot width and profile height. 
     While the invention has been described in connection with several examples, modifications to those examples within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference, further description is deemed unnecessary.