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Potlatch Brainerd Wet End Training 3

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Potlatch Brainerd Wet End Training 3

  1. 1. 01/30/15 Copyright © 2001 Bill Frawley Potlatch Brainerd Wet End Training March 2001 By Bill Frawley
  2. 2. 01/30/15 Copyright © 2001 Bill Frawley Introduction  Understanding the paper forming process, equipment and chemistry  Bill Frawley and Joe Osfar Training Consultants
  3. 3. 01/30/15 Copyright © 2001 Bill Frawley Topics of Discussion  Looking at machine as relates to fiber mat formation.  How each area impacts fiber mat  Entry zone  Forming zone  Dewatering zone  Consolidation zone  Pressing
  4. 4. 01/30/15 Copyright © 2001 Bill Frawley How The Fiber Mat Develops
  5. 5. 01/30/15 Copyright © 2001 Bill Frawley The Five Zones of the Forming Table  Entry Phase  Forming Zone  Dewatering Zone  Transition Zone  Consolidation Zone
  6. 6. 01/30/15 Copyright © 2001 Bill Frawley # 5 PM Table Zones
  7. 7. 01/30/15 Copyright © 2001 Bill Frawley 1 Entry Phase  Headbox  Slice and Jet  Pressure Forming Vs Velocity Forming  Impingement point  Forming board  Structuring of filtering mat
  8. 8. 01/30/15 Copyright © 2001 Bill Frawley Headbox Approach System  Approach system  Fan pump  Attenuator  Tube bundle
  9. 9. 01/30/15 Copyright © 2001 Bill Frawley Headbox Components  Headbox Components  Diffuser block  Distributor rolls (holy rolls)  Nozzle  Slice
  10. 10. 01/30/15 Copyright © 2001 Bill Frawley Rectifier Roll  Agitates dilute stock so flocks can not form in headbox  Velocity through center of hole greater than outside do to boundary effect  Designed for fixed flow range
  11. 11. 01/30/15 Copyright © 2001 Bill Frawley Rectifier Roll Pattern in Sheet  If roll capacity is exceeded streaks will flow through nozzle  Forming board will set pattern in filtering mat
  12. 12. 01/30/15 Copyright © 2001 Bill Frawley Flow From a Vertical Slice
  13. 13. 01/30/15 Copyright © 2001 Bill Frawley Jet Angle ß, Degrees
  14. 14. 01/30/15 Copyright © 2001 Bill Frawley Contraction Coefficient
  15. 15. 01/30/15 Copyright © 2001 Bill Frawley Defect In Slice Lip
  16. 16. 01/30/15 Copyright © 2001 Bill Frawley Rush Drag
  17. 17. 01/30/15 Copyright © 2001 Bill Frawley Rushing the Jet  Jet velocity greater than wire speed  CD fiber orientation  Sheet has less MD strength.
  18. 18. 01/30/15 Copyright © 2001 Bill Frawley Dragging the Jet  Jet velocity less than wire speed  MD fiber orientation  Sheet has more MD strength.
  19. 19. 01/30/15 Copyright © 2001 Bill Frawley Pressure Vs Velocity Forming  Pressure Forming  Rapid development of fiber mat  Low first pass retention  Sheet sealing  Tissue applications
  20. 20. 01/30/15 Copyright © 2001 Bill Frawley Velocity Vs Pressure Forming  Velocity Forming  Better filtering mat  Carry lower consistency in to forming zone  Higher first pass retention  Flat grades
  21. 21. 01/30/15 Copyright © 2001 Bill Frawley How The Filtering Mat Develops  Filtering mat developed on the forming board
  22. 22. 01/30/15 Copyright © 2001 Bill Frawley Sheet Consistency Development  Formation is over when stock consistency reaches 1.2 – 1.4%  Excessive activity past this point will degrade sheet properties!
  23. 23. 01/30/15 Copyright © 2001 Bill Frawley 2 Forming Zone  Breast Roll Shake  How foils & table rolls work  Harmonics 1. Machine speed 2. Foil spacing 3. Box spacing  Amplitude - Function of angle  All over when stock reaches 1.2- 1.4% consistency Sheet set point
  24. 24. 01/30/15 Copyright © 2001 Bill Frawley How The Forming Zone Develops Fiber Mat  Forming zone works fibers & fillers in upper part of suspension
  25. 25. 01/30/15 Copyright © 2001 Bill Frawley Table Rolls  High activity at low speeds  Positive and negative pressure  Ever increasing nip  Work up to 1200 fpm  Higher maintenance
  26. 26. 01/30/15 Copyright © 2001 Bill Frawley When Table Rolls Go Bad
  27. 27. 01/30/15 Copyright © 2001 Bill Frawley How Different Foils Work
  28. 28. 01/30/15 Copyright © 2001 Bill Frawley How Foils Work  Nose: Skives water off bottom of wire  Flat: Seals fabric so vacuum can happen  Angle: Creates gravity vacuum
  29. 29. 01/30/15 Copyright © 2001 Bill Frawley  Nose:  Skives water off bottom of wire  Creates speed bump  If the nose is too sharp fibers will staple over and cause streaks (like a rock in a river) Foil Nose
  30. 30. 01/30/15 Copyright © 2001 Bill Frawley Foil Flat  Flat seals fabric to bottom of wire so vacuum can happen  This can tell us how foils is wearing or aligned  Wear should be from nose back  If wear starts on back of flat t-slot is wrong or tilted
  31. 31. 01/30/15 Copyright © 2001 Bill Frawley Foil Angle  Foils won’t work under 400 FPM  Angle draws water through filtering mat as nip moves away from wire  Vacuum brakes when water can’t fill nip  Wire is pulled down with water  When vacuum brakes, wire snaps back causing activity
  32. 32. 01/30/15 Copyright © 2001 Bill Frawley Harmonics  Speed ÷ Spacing ÷ 5 = CPS  1500 fpm ÷ 5 = 300 ÷ 5 = 60 CPS  Sweet spot for formation is around 80 Cycles per second  If activity stops for an instant flocculation will occur
  33. 33. 01/30/15 Copyright © 2001 Bill Frawley Foil Box Spacing  Box spacing has to be set to the blade spacing of the proceeding box  Example: Foils are spaced 5” center to center the next box has to set 5” 10” or 15” from the tip of the last foil to the tip of the first foil on the next box
  34. 34. 01/30/15 Copyright © 2001 Bill Frawley 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 5.75 6.00 ft/min in /sec 500.00 100.00 33.33 30.77 28.57 26.67 25.00 23.53 22.22 21.05 20.00 19.05 18.18 17.39 16.67 600.00 120.00 40.00 36.92 34.29 32.00 30.00 28.24 26.67 25.26 24.00 22.86 21.82 20.87 20.00 700.00 140.00 46.67 43.08 40.00 37.33 35.00 32.94 31.11 29.47 28.00 26.67 25.45 24.35 23.33 800.00 160.00 53.33 49.23 45.71 42.67 40.00 37.65 35.56 33.68 32.00 30.48 29.09 27.83 26.67 900.00 180.00 60.00 55.38 51.43 48.00 45.00 42.35 40.00 37.89 36.00 34.29 32.73 31.30 30.00 1000.00 200.00 66.67 61.54 57.14 53.33 50.00 47.06 44.44 42.11 40.00 38.10 36.36 34.78 33.33 1100.00 220.00 73.33 67.69 62.86 58.67 55.00 51.76 48.89 46.32 44.00 41.90 40.00 38.26 36.67 1200.00 240.00 80.00 73.85 68.57 64.00 60.00 56.47 53.33 50.53 48.00 45.71 43.64 41.74 40.00 1300.00 260.00 86.67 80.00 74.29 69.33 65.00 61.18 57.78 54.74 52.00 49.52 47.27 45.22 43.33 1400.00 280.00 93.33 86.15 80.00 74.67 70.00 65.88 62.22 58.95 56.00 53.33 50.91 48.70 46.67 1500.00 300.00 100.00 92.31 85.71 80.00 75.00 70.59 66.67 63.16 60.00 57.14 54.55 52.17 50.00 1600.00 320.00 106.67 98.46 91.43 85.33 80.00 75.29 71.11 67.37 64.00 60.95 58.18 55.65 53.33 1700.00 340.00 113.33 104.62 97.14 90.67 85.00 80.00 75.56 71.58 68.00 64.76 61.82 59.13 56.67 1800.00 360.00 120.00 110.77 102.86 96.00 90.00 84.71 80.00 75.79 72.00 68.57 65.45 62.61 60.00 1900.00 380.00 126.67 116.92 108.57 101.33 95.00 89.41 84.44 80.00 76.00 72.38 69.09 66.09 63.33 2000.00 400.00 133.33 123.08 114.29 106.67 100.00 94.12 88.89 84.21 80.00 76.19 72.73 69.57 66.67 2100.00 420.00 140.00 129.23 120.00 112.00 105.00 98.82 93.33 88.42 84.00 80.00 76.36 73.04 70.00 2200.00 440.00 146.67 135.38 125.71 117.33 110.00 103.53 97.78 92.63 88.00 83.81 80.00 76.52 73.33 2300.00 460.00 153.33 141.54 131.43 122.67 115.00 108.24 102.22 96.84 92.00 87.62 83.64 80.00 76.67 2400.00 480.00 160.00 147.69 137.14 128.00 120.00 112.94 106.67 101.05 96.00 91.43 87.27 83.48 80.00 2500.00 500.00 166.67 153.85 142.86 133.33 125.00 117.65 111.11 105.26 100.00 95.24 90.91 86.96 83.33 2600.00 520.00 173.33 160.00 148.57 138.67 130.00 122.35 115.56 109.47 104.00 99.05 94.55 90.43 86.67 2700.00 540.00 180.00 166.15 154.29 144.00 135.00 127.06 120.00 113.68 108.00 102.86 98.18 93.91 90.00 Foil Frequency Chart
  35. 35. 01/30/15 Copyright © 2001 Bill Frawley Foil Amplitude  Function of wire speed and foil angle  Lower angle lower pulse  Higher angle higher pulse  4-5 Degree foils maximum  Turbulence making foils
  36. 36. 01/30/15 Copyright © 2001 Bill Frawley Activity Rating Chart 1. Flat Clam 2. Calm 3. Ripples 4. Small Waves 5. Small Waves 6. Wave action 7. Micro turbulence 8. Micro turbulence 9. Necking 10. Stock Jump
  37. 37. 01/30/15 Copyright © 2001 Bill Frawley Calm to Small Waves  No shear in stock suspension  Flocculation  Mat can get so dense that it will retard drainage
  38. 38. 01/30/15 Copyright © 2001 Bill Frawley Wave Action  Shear starts to begin  Fibers in upper suspension move  Filtering mat stays open  Formation can improve
  39. 39. 01/30/15 Copyright © 2001 Bill Frawley Micro Turbulence  Shear occurs  Flock size is significantly smaller and more uniform  Fibers in upper suspension move  Filtering mat stays open  Formation improves
  40. 40. 01/30/15 Copyright © 2001 Bill Frawley Good Micro Turbulence
  41. 41. 01/30/15 Copyright © 2001 Bill Frawley Stock Jump  Filtering mat is destroyed  Retention drops  Droplets can rain on your parade (rings in sheet)  Chunks of filtering mat could cause large flocks
  42. 42. 01/30/15 Copyright © 2001 Bill Frawley Dewatering Zone  Gravity Foils  Vacuum Foils  Top Wire Units
  43. 43. 01/30/15 Copyright © 2001 Bill Frawley Thickening The Stock  Add a little flour and stir over low heat
  44. 44. 01/30/15 Copyright © 2001 Bill Frawley Thickening The Stock  Keep mat open  Remove water  Graduate low vacuum levels to prevent sheet sealing  Finish top side of sheet  Consistency levels form 1.4 – 13%
  45. 45. 01/30/15 Copyright © 2001 Bill Frawley Gravity Foils  In the dewatering zone angles should be a compromise between water removal and stock activity  Need to keep mat open for drainage  Need to carry harmonic activity to last gravity unit
  46. 46. 01/30/15 Copyright © 2001 Bill Frawley Activity on Gravity Foils
  47. 47. 01/30/15 Copyright © 2001 Bill Frawley Low Vacuum Foils  Low vacuum foils are need to remove water when the filtering mat has thickened to a point where gravity foils become inefficient  Control consistency coming in to top wire unit 1.8 – 2.1%
  48. 48. 01/30/15 Copyright © 2001 Bill Frawley Low Vacuum Foils  Vacuum measured in inches of water  Blower supplies negative pressure  Water on top of fiber mat creates air tight seal  Open area = dwell time  Ramp up vacuum  To much vacuum to soon will seal sheet
  49. 49. 01/30/15 Copyright © 2001 Bill Frawley Controlling Low Vacuum Foils  Ramp vacuum  Drop leg seals bottom and determines how much vacuum is possible  It is better to use narrow 0º blades and adjust t-bar spacing for open area (less drag)
  50. 50. 01/30/15 Copyright © 2001 Bill Frawley B E L B O N D
  51. 51. 01/30/15 Copyright © 2001 Bill Frawley Bel Bond Advantages  Fiber mat is sandwiched between two forming fabrics  Dewaters up  Finishes top of sheet  Structures mat uniformly  Less two sidedness  Increases consistency of sheet from 2 – 11%
  52. 52. 01/30/15 Copyright © 2001 Bill Frawley Bel Bond Lead-in Detail
  53. 53. 01/30/15 Copyright © 2001 Bill Frawley Lead-in Box  Four adjustments for controlling H2O 1. Height of roll 2. Raise or lower trailing edge of lead- in box 3. Raise or lower vacuum of lead-in box 4. Raise or lower vacuum of lovac box
  54. 54. 01/30/15 Copyright © 2001 Bill Frawley Impingement Point of Two Wires  Water is forced up through top wire on lead-in box  Water is vacuumed down in to lead-in box up to 25” H2O vacuum  Curvature of lead-in box helps force water up  Adjusting height of trailing edge of lead-in box has affect on formation  Lead-in roll has biggest impact on dewatering
  55. 55. 01/30/15 Copyright © 2001 Bill Frawley Curved Inverted Vacuum Box
  56. 56. 01/30/15 Copyright © 2001 Bill Frawley Auto Slice  Vacuums free water and air from inside of top wire 20-25” H2O vac  Roof is adjustable by hand  Setting is determined by closing roof until slice rejects some water then opened back up a smidge so all water is removed  Roof regulates only amount of air removed NOT amount of water
  57. 57. 01/30/15 Copyright © 2001 Bill Frawley 1st Vacuum Chamber  15 two inch ceramic blade vacuum zone under auto slice box  Vacuum level shifts to 3 – 5” Hg  Connected to a vacuum pump  Water is move up channel to a weir
  58. 58. 01/30/15 Copyright © 2001 Bill Frawley 2nd Vacuum Chamber  14 two inch ceramic blade vacuum zone under auto slice box  Vacuum level shifts to 4 – 6” Hg  Connected to a vacuum pump  Water is move up channel to a weir
  59. 59. 01/30/15 Copyright © 2001 Bill Frawley Transfer Box  Transfer box keep the sheet on the bottom wire  Wires separate on curved surface  Begins sheet consolidation zone  8 slots pulling 4-6 inches of mercury
  60. 60. 01/30/15 Copyright © 2001 Bill Frawley Suction Boxes  Ramp up vacuum from 4-10” of mercury  Boxes have adjustable deckles  Dries sheet from about 12-17% consistency  Vacuum supplied by Nash vacuum pump
  61. 61. 01/30/15 Copyright © 2001 Bill Frawley Suction Couch Roll
  62. 62. 01/30/15 Copyright © 2001 Bill Frawley Function of Suction Couch Roll  End of consolidation zone  Dries sheet to 18-22%  Helps drive forming fabric  At speeds over 1200 FPM water never penetrates shell  Liquid ring seal  Highest vacuum element on machine
  63. 63. 01/30/15 Copyright © 2001 Bill Frawley Forming Section Review  Stock delivery system  Forming zone  Dewatering zone  Top wire unit  High Vacuum  Couch  Sheet development
  64. 64. 01/30/15 Copyright © 2001 Bill Frawley Press Section
  65. 65. 01/30/15 Copyright © 2001 Bill Frawley Press Section Functions  To remove water by squeezing or wringing sheet against a felt  Felts act like a sponge  Pressing make sheet denser  Press nips squeeze sheet and felt or just sheet to remove water or to smooth sheet  Overloading can crush and mark
  66. 66. 01/30/15 Copyright © 2001 Bill Frawley 4 Phases of Press Roll Nip
  67. 67. 01/30/15 Copyright © 2001 Bill Frawley 4 Phases of Press Roll Nip  Phase 1: Felt and sheet compresses sheet becomes saturated  Phase 2: Water is squeezed from sheet to felt  Phase 3: Felt expands faster pulling more water from sheet  Phase 4: Sheet rewets as it partially expands
  68. 68. 01/30/15 Copyright © 2001 Bill Frawley PLI Vs PSI  Pli is used measure force of mating rolls  Pli is the number used for press loading  Psi is used when discussing force of nip on sheet or felt & sheet
  69. 69. 01/30/15 Copyright © 2001 Bill Frawley Why Press are Crowned  Crown is needed to  Even out pressure under nip loading  Compensate for Sag & deflection
  70. 70. 01/30/15 Copyright © 2001 Bill Frawley Press Loading  1st Press 450 PLI  2nd Press 600 PLI  Smoothing 450-500 PLI  Excessive pressure will crush or shadow mark sheet
  71. 71. 01/30/15 Copyright © 2001 Bill Frawley Combi-Roll  The Combi roll is a pickup & suction first press roll in one  Low vacuum area lifts sheet off wire and holds it on the felt until the high vacuum zone under first press nip  Low vac area doesn’t remove water  High vac holds water in felt until sheet can get away
  72. 72. 01/30/15 Copyright © 2001 Bill Frawley Combi-Roll Operation  Vacuum must be off to move into wire  Low vacuum is set about 8” Hg  Low vac zone doesn't remove water  High vacuum is set at 20” Hg And holds water in felt until sheet is clear of nip  Box alignment critical  1st press loaded to 450 Pli
  73. 73. 01/30/15 Copyright © 2001 Bill Frawley Suction Felt Roll  Acts like an anti-blow box  Sucks sheet tight to felt to prevent flutter entering 2nd press  Doesn't remove water from sheet only air  Stabilizes sheet after open draw from pickup felt
  74. 74. 01/30/15 Copyright © 2001 Bill Frawley 2nd Press  2nd press uses a venta- nip grooved bottom roll  Grooves in rubber cover act like tread on your car tires  Water is squeezed from sheet through felt and in to voids of grooves  Too much pressure can cause shadow marking and crush sheet
  75. 75. 01/30/15 Copyright © 2001 Bill Frawley Smoothing Press  Smoothing press as it’s name says smoothes the sheet for better drying  No water is removed so nip load has to be lower that 2nd press  Both rolls are hard
  76. 76. 01/30/15 Copyright © 2001 Bill Frawley Press Roll Showers  Showers in suction rolls are invisible  Venta-nip shower keeps grooves clean and open
  77. 77. 01/30/15 Copyright © 2001 Bill Frawley Press Felts  Act as a blotter or sponge  Absorb water +  dirt, fines, pitch ash, minerals… at nip  Cleaned with showers & chemicals (batch wash)  Dried on uhle boxes  Trade line needs to run square  Change when filled and worn
  78. 78. 01/30/15 Copyright © 2001 Bill Frawley Press Section Felt Showers Each felt has  Batch chemical and flushing shower  High pressure cleaning shower  Uhle box lube shower
  79. 79. 01/30/15 Copyright © 2001 Bill Frawley Uhle Boxes  Shop-vac for felts  4 milliseconds dwell minimum to dry and clean  Be careful of edges outside sheet they will dry out first  Adjust deckles to sheet width  Vacuum will start around 10” Hg when felt is new and increase to 15-17” when felt is filled
  80. 80. 01/30/15 Copyright © 2001 Bill Frawley Press Section Review  To remove water by squeezing sheet against an a felt  Felts act like a sponge  Uhle boxes & showers clean and dry felts  Pressing make sheet denser  Press nips squeeze sheet and felt or just sheet to remove water or to smooth sheet  Overloading can crush and mark
  81. 81. 01/30/15 Copyright © 2001 Bill Frawley Thank You, Any Questions?

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