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Ch. 8 and 9 POM Notes

by: Nichole Knopp

Ch. 8 and 9 POM Notes GRSC150

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Nichole Knopp

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These go further in detail about sifters. and roller mills.
Principles of Milling
Churchill, Frances Maria
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This 39 page Bundle was uploaded by Nichole Knopp on Monday March 28, 2016. The Bundle belongs to GRSC150 at Kansas State University taught by Churchill, Frances Maria in Fall 2015. Since its upload, it has received 21 views. For similar materials see Principles of Milling in Science at Kansas State University.

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Date Created: 03/28/16
Break  Release  vs.  Break  Extrac▯on   Interna▯onal  Grains  Program   Kansas  State  University   Break  Release  &  Extrac▯on:     Student  Learning  Objec▯ves   Know how to Caluclate Break Release Know the difference between break release and extraction The  Milling  Systems   Break System Mi Purification System d R d e •  opens  the  wheat  kernel  and  gouges  out   s large  chunks  of  endosperm     i R d •  releases  “sizings”  material   d  u •  compound  par▯cles  (bran  anu   e endosperm)     c break  system •  suitable  for  purifica▯on     i •  releases  clean  middlings  (puren   endosperm)  to  middlings  reduc▯on   system    The break system can impact all of the milling systems - It determines the balance for the entire mill. 1 THE PRIMARY BREAK SYSTEM GENERATES: SIZINGS STOCKREAK STOCK 1 MIDDS STOCK 3 MIDDS STOCK 5 Break  Release   Se▯ng  a  break  passage   roller  mill  to  allow  a   specific  amount  of  stock   to  go  on  through  to  the   sizings  &  purifica▯on   system.     -­‐-­‐-­‐The  release  is  measured  by   calcula▯ng  the  percentage  of   ground  stock  that  passes  through   a  par▯cular  size  screen.         6 2 Break  Release  Purpose  and  Intended  Results   •  Purpose:   to balance the milling system –  _________________________________________________    by   releasing  material  with  a  uniform stpar▯cle  size  to  properly  set  up▯  the   sizings  and  purifica▯on  system  (which  in  turns  sets  up  1 •  Intended  Results:   repeatable –  grinding  passage.  ________  distribu▯on  of  products  from  each   –  establish  mill  balance  with  new  or  changing  wheat  mixes.   –  provide  a  common  point  of  understanding  between  mill  opera▯ves   opera▯ng  the  same  mill  on  different  shi▯s.   Break  Release  &  Load  Distribu▯on   Break  release:   •  determines  the  distribu▯on  of  par▯cles   throughout  the  remainder  of  the  mill  flow.   (what is going to go where)      ________________________________   •  establishes  the  ______  and  __________   load and quality characteris▯cs  of  stock  throughout  the  mill.   A  break  release  schedule  is  determined  by   miller  preference,  equipment  alloca▯on  and   wheat  characteris▯cs.   How  to  Measure  Break  Release   3 Before  and  A▯er  Grinding   We assume 100% recovery of products 785.3 grams 785.3 grams 10 Si▯  Using  a  Common  Sieve  Size   SSBC- Stainless Steel Bolting Cloth Each mill will may have their own preference for the sieve size used in the break release test. In our lab we will use a 20SSBC-1041µ sieve. 11 Break  Release  Calcula▯on   Step  1:  Weigh  the  overs   using  a  lab  scale   Step  2:  calculate  the   weight  passing  through   the  screen  by  subtrac▯on   Step  3:  calculate  the  break   release  using  the  equa▯on   grams through 20SSBC ×100 =% Break Release grams milled 12 € 4 Example:  Break  Release  Calcula▯on   1.  Weigh  the  overs  of  the  20SSBC  =  502.6g     2.  Caculate  the  grams  that  went  through  the  20SSBC  by  Subtrac▯on.      785.3g  -­‐  502.6g  =  282.7g     3.  Convert  the  grams  through  20SSBC;  to  percent  through  20SSBC.      282.7g  ÷  785.3g  =  .359     .359  ×  100  =  35.9%     1BK  Break  Release  =  35.9%     13 Break  Release  Defined   •  Se▯ng  a  break  passage  roller  mill  to  allow  a   specific  amount  of  stock  to  go  on  through   to  the  sizings  &  purifica▯on  system.       – The  release  is  measured  by  calcula▯ng  the   percentage  of  ground  stock  that  passes   through  a  par▯cular  size  screen.       •  Typically,  we  will  describe  it  based  upon  the   grinding  opera▯on  that  supplied  the   sample.       – Example:  (First  Break  Release  was  set  at  32%)   Break  Extrac▯on  Defined   Break Release: set up the mill, based on amount of the material based on particular passage •  Extrac▯on  is  the  percent  of  the  original  wheat   to  the  mill  extracted  from  the  kernel  at  a   par▯cular  grinding  opera▯on.     nd Break Extraction: milling efficiency, based on amount •  Example:    If  the  2  Break  extrac▯on  was  23%   started with (wheat to 1 break) then  the  stock  “removed  from  the  break   system  at  second  break  was  23%  of  the  wheat   that  entered  the  mill  at  first  break.   5 650.0 g From First Break 1000.0  grams  total   2 nd Break Release wheat  milled   650.0 − 422.5 = 227.5 227.5 ÷ 650.0 × 100 = 35.0 % Break Release 12.7  g   422.5  g  89.3  g   14.6  g  10.9  g  35.0 % of the first break stock was released into the mill at second break. 16 650.0 g From First 1000.0  grams  total   2 nd Break Extraction wheat  milled   650.0 − 422.5 = 227.5 227.5 ÷ 1000.0 × 100 = 22.75 % Break 12.7  g   Extraction 422.5  g  89.3  g   14.6  g  10.9  g  22.75 % of the total wheat milled enters into the mill after second break. 17 6 the main components of a free-swinging sifter Student  Learning  Objec▯ves:     Si▯ers  and  Sieves  –  what  you  needhow a free-swinging sifter works what the "throw" of a sifter is and how it can be changed the parts of a sieve determine the hand of a sieve how relationship between % open area and thread size how to read a basic sifter flow the differences btwn a NOVA sieve and a "standard" sieve 1 Si▯ers  and  Sieves   Objec▯ve  of  Sieving     •    To  separate  material  based   on  differences  in  par▯cle  size.       •  batch     •  con▯nuous   Sieving  Mo▯on   •  Gyratory-­‐  move  in  a  circular  fashion  with  the  throw  equal  to  the  diameter  of   the  circular  path  traveled.    Key  measures  include  the  throw  and  the  RPM   (revolu▯ons  per  min).                 Ex.  Free  Swinging  Si▯er   •  Reciproca▯ng-­‐move  back  and  forth  in  a  straight  line  or  stroke.    Key  measures   include  stroke  length  and  frequency  (strokes  per  min).                  Ex.  Old  Style  Purifier     •  Combina▯on-­‐  combines  gyratory  and  reciproca▯ng  mo▯on.                  Ex.  Millerator   •  Centrifugal-­‐cylindrical  shaped  screen  rotates  while  stock  tumbles  inside  its   surface     •  Vibratory-­‐  Reciproca▯ng  with  a  slight  ver▯cal  component  of  force               Ex.  New  Style  Purifier     2 Si▯ing  Ac▯on   Reciprocating Gyratory Centrifugal Gyro-reciprocating Vibratory Types of Sifters Types  of  Si▯ers:  Centrifugal/Vibratory   3 Free  Swinging  Si▯er   Si▯er  Components:  Si▯er  Sec▯on   •  The  si▯er  is  made  up  of   mul▯ple  si▯er  sec▯ons.   •  Each  sec▯on  is  si▯ing  a   different  product.   •  The  sieve  stack  in  each   sec▯on  is  designed   specifically  for  the   product  being  si▯ed   This 8-Section sifter has 4 sections on each side.   Si▯er  Components:  Sieve  Stack   •  All of the sieves in a sifter stack”er make up the “sieve •  The flow of material through the sieve stack is called the sifter flow Sieve Stack 4 Main  Components  of  a  Si▯er   Sifter Reeds Sifter Drive Motor Counterbalance Sifter Socks Sifter Knees Pneumatic Press Top Sifter Door Sifter Socks Sifter Knees Si▯er  Components:     Si▯er  Reeds   •  fiberglass  or  wood  (Hickory)   •  flexible  enough  to  accommodate  the  si▯er   mo▯on   •  strong  enough  to  hold  the  weight  of  the   si▯er   •  a▯ached  to  the  ceiling   5 Si▯er  Components:  Si▯er  Outlet   •  all  of  the  separated   products  flow  out   through  a  specific   discharge  without  being   mixed.   Si▯er  Components:  Drive  Motor   •  rides  with  the  si▯er.   •  drive  pulley  size   determines  the  speed  of   the  si▯er.     Si▯er  Components:  Counterbalance   6 Si▯er  Components:  Counterbalance   •  responsible  for  the  throw   of  the  si▯er.   •  The  heavy  lead  weights   spin  around  the  center   sha▯.   •  The  unbalanced  mo▯on   causes  the  si▯er  to  move   in  a  circle.   Counterbalance  Mo▯on   At start-up the weight is At full speed the weight extends closer to the center of gravity further from the center of gravity Centrifugal  Force  Acts  on  the  Center  Point   M 1 Sifter Mass r = Throw M r1 1 r 2 2 1 2 M 2 M 1 Sifter Mass Full Speed r1= Throw of Sifter M 2 Counterbalance Mass r2= counterbalance distance from shaft (radius Start-up of rotation) 7 Si▯er  Components:  Sieve  Stack   •  All of the sieves in a sifter together make up the “sieve stack” Sieve Stack •  The flow of material through the sieve stack is called the sifter flow What’s  Inside  the  Si▯er?           •  a stack of sieves covered with a woven mesh material called bolting cloth. •  metal (i.e. stainless steel) •  nylon •  size of the bolting cloth opening determines the sizes of overs & throughs •  The screen sizes in a sifter generally get smaller from top to bottom. Si▯er  “Overs"   •  Large  par▯cles    that   won’t  fit  through  the   bol▯ng  cloth’s   openings  which  travel   over  the  bol▯ng  cloth.   8 Si▯er  “Throughs"   •  Material  that  is  small   enough  to  pass  through   the  openings  in  the   bol▯ng  cloth  .   •  The  throughs  from  each   screen  in  this  si▯ing  step   are  combined  in  the   through  channel  and  are   passed  to  the  next  step  of   si▯ing.   Si▯er  Pan   9 Looking  down  the  Thru  Channel   Possible  Outlets   3 7 2 6 8 4 5 1 Door 10 Sieve  Parts   Thrus Side Channel Head Blank Side Channel S Overs Throat/Tail Screen Backwire Nails Pan Thrus Determina▯on  of  Sieve  Hand   Alternative #1 With the head next to your belt buckle, the side the thrus come out is the hand of the sieve. Alternative #2 With the thrus next to your belt buckle, the side the overs come out on is the hand of the sieve. 11 Right  Hand  Sieve   Right Hand RH Le▯  Hand  Sieve   Left Hand LH No  Hand  Sieve   No Hand NH 12 ¼  Turn  Outside  Tail  Out   No Hand No Pan 1/4 Turn Outside Tail Out NHNP¼TOTO Straight  Flow  Sieve   No Hand No Pan Outside Tail Out NHNPOTO ¼  Turn  Inside  Tail  Out   No Hand No Pan ¼ Turn Inside Tail Out NHNP¼TITO 13 Side  Channel  Block   Left Hand Side Channel Block LHSCB Side  Channel  Block  Above  Nails   Left Hand Side Channel Block Above Nails LHSCBAN Side  Channel  Block  Under  Nails   Left Hand Side Channel Block Under Nails LHSCBUN 14 Si▯er  Surface   The number of square feet of sifter surface used for sifting, sometimes expressed as a square feet per daily hundredweight capacity. (Square Meters per ton of wheat). Example  of  Si▯ing  Improvements   •  Glued  Tray  Style  vs.  Stapled  Sieve  Cloth   •  Backwire-­‐less  Sieve   •  Nova  Sieves®   •  Wildcat  Sieve  ®     •  Full  Cloth  Sieves,  Double  Discharge  Sieve   Frames  vs.  Channeled  Sieves   15 NOVA Sieve • Screen Cleaners Screen & Pan Cleaner • • Backwire • Pan Cleaner Pan • Pan • Pan Cleaner Retainers • Advantages  of  Pneuma▯c  Stretching  &  Gluing   on  Clothing   •  Sanitary  a▯achment-­‐eliminates  product  and  contaminant   harborages   •  Clothing  can  be  installed  consistently  with  uniform  tension   •  Skill  level  required  for  replacing  clothing  is  less  cri▯cal   •  Improved  si▯ing  performance  due  to  high  clothing  tension   •  Prolonged  clothing  life   •  Improved  screen  cleaner  performance   Inspec▯on  &  Maintenance  checklist   Si▯er  Maintenance       ü  Tailings & Interpret Results ü  Condition of connecting sleeves ü  Condition of gaskets ü  Screen condition ü  Screen cleaner condition ü  Sieve frame condition ü  Lubrication & drive condition ü tightness of bolts, including sifter reeds 16 Si▯er  Mesh   •  The  sieves  in  a  si▯er  are  covered  in  a  woven  mesh  material   called  bol▯ng  cloth.    The  bol▯ng  cloth  could  be  made  of   stainless  steel,  nylon,  or  polyester.     How  Bol▯ng  Cloth  is  Named   •  Bol▯ng  cloth  has  several  different  naming   conven▯ons  based  on  the  material  type  and  size   of  the  bol▯ng  cloth.   •  The  informa▯on  you  need  to  know  about  your   bol▯ng  cloth   – Material  Type  (wire  mesh,  stainless  steel,  nylon   polyester)   – Openings  per  inch  (in  one  dimension,  length  or  width,   or  both)   – Opening  size  in  microns   17 Warp  and  We▯   •  Bol▯ng  cloth  is  woven  in   a  tex▯le  mill  just  like  all   other  types  of  fabric.   •  The  long  ver▯cal   threads  are  the  Warp   threads.   •  The  We▯  threads  are   woven  horizontally  over   and  under  the  warp   threads.   Wire   • Wire  (W)  sieve  cloth  today  includes  Stainless   Steel  Bol▯ng  Cloth  (SS,  SSBC),  Stainless  Steel  Mill   Wire  (SS,  SSMW)  and  Tinned  Mill  Screen  (TMS).   •   Wire  products  such  as  Tu▯ex  (TT)  and  Durloy   (D)  may  also  be  iden▯fied.         • Wires  are  designated  by  the  number  of   openings  per  inch  and  construc▯on  material  i.e   18  TMS   Synthe▯c   • Synthe▯c  bol▯ng  cloths  are  made  with   monofilaments  of  Nylon  (N)  or  Polyester   (PE).   • Synthe▯c  bol▯ng  cloth  is  usually  referred   to  by  the  micron  size  of  its  aperture  opening   and  the  material,  i.e.  132  N  or  132  PE.         18 Mesh  Counters   A linen mesh counter is a small magnifying glass, with a known viewing area and length, used to count the number of openings per linear inch in a bolting cloth. A transparent mesh counter is a transparent film that can be placed on very fine bolting cloth to determine mesh count. Read XX bolting cloth direct, synthetics read mesh per inch in both x and y direction. Linen  Mesh  Counter   ½” Transparent  Mesh  Counter   XX  Bol▯ng  Cloth   Scale   Scale     19 Weave  Pa▯erns   Special  weave  pa▯erns  may  be  chosen  to  enhance  the  si▯ing   ac▯on  of  the  sieve.  The  double  weave  pa▯ern  increases  fric▯on   across  the  sieve  surface,  but  decreases  %  open  area.   Openings  Per  Inch   Stainless  steel  bol▯ng  cloth  and  other  wire  mesh  is  named  by   the  number  of  openings  per  linear  inch.     18SSBC  has  18  openings  per  inch   1.0  inch   Opening  Size  in  Microns   We  are  mostly  concerned  about  the  size  of  par▯cle  that  will  pass   through  the  mesh  opening,  so  it’s  a  good  prac▯ce  to  just  describe   mesh  in  microns  opening   PA  10XX-­‐   132  microns   20 Thread  diameter  vs  %  open  area   •  Increasing  the  thread  diameter   will  increase  the  durability  and   strength  of  the  bol▯ng  cloth   (longer  life).   •  If  the  openings  per  inch  remain   constant,  increasing  the  thread   diameter  will  decrease  the   aperture(opening).   •  More  si▯er  surface  is  taken  up   by  threads,  which  decreases   the  %  open  area.   Thread  Diameter  vs  %  Open  Area   1.0”   3-­‐mesh  per  inch   3-­‐mesh  per  inch   Effects of Wire/Thread Diameter 8  Mesh  0.072  Wire   8  Mesh  0.063  Wire 8  Mesh  0.041  Wire   8  Mesh  0.035  Wire   8  Mesh  0.032  Wire 8  Mesh  0.028  Wire   21 Media  Selec▯on  Issues   18  SSBC   18  TMS   •  18  openings  per  in•  18  openings  per  inch   •  0.009”  wire  diameter •  0.015”  wire  diameter   •  70.2%  open  area   •  53.4%  open  area   •  1190  m  opening   •  1030  m  opening   – Shorter  screen  life – Longer  screen  life   – Greater  Capacity   – Less  Capacity   – Larger  throughs   – Smaller  throughs   Stainless Steel Bolting Cloth- (SSBC) Wire mesh •  Stainless steel wire mesh is used for coarse (scalping) sieves or when sifting abrasive materials •  It is common to find SSBC in the top sieves of the break system in a flour mill. Grit Gauze (GG) Coarse Granular Material PA-GG Polyamide Grit gauze is used for the coarse sieves • good abrasive qualities • long lifetime • high efficiency 22 Milling  Forte-­‐  (MF)  fine  granular  material  and  flour   •  Milling  forte  cloth  is  a  medium            strength  cloth  used  for  flour              si▯ing.     •  It  has  a  good  combina▯on              of  durability  and  si▯ing              efficiency.   PA-­‐Leno  Weave  Bol▯ng  Cloth     •  Leno  weave  bol▯ng  cloth   has  an  alterna▯ng  double   weave  pa▯ern  in  the  warp   threads.     •  The  double  weave   increases  fric▯on  on  the   sieve  surface  allowing  for   be▯er  flour  recovery.     Sieving efficiency vs. cloth wear life PA-XX - N Normal Quality PA-MF Milling Forte PA-XXX Heavy Duty i E Wear Life 23 Sieve Cloth Overview Mesh Screens opening Fabrics Coarse >900 µm Wire Mesh Medium >900 - 300 µm Polyamide Grit gauze Polyamide Fine 300 - 90 µm Flour sieves A choice between efficiency and durability Comparison of the fabric families - Normal quality Milling fortHeavy duty Specification PA-XX-N PA-MF PA-XXX/HD Mesh opening 132 132 132 Thread diameter 60-2x50-60 70 80 Open Area 43% 43% 39% Capacity Lifetime Purifier screens PET-GG Grit Gauze The rough fabric surface makes the product remain on the sieve longer. This leads to better separation. • little affect from humidity • resistant to temperature changes • keeps constant tension. 24 Centrifugal sifter PA-HD ( ASTM ) Heavy Duty PA-HD ( ASTM ) fabrics assure good sieving efficiency and a long lifetime Summary of sifting fabrics Area of Main Fabric family Machine Sifters Centrifug. Purifier use benefit sifter Coarse sifterAbrasive PA-GG X X - covers qualities PA-XXX Durum and Long lifetime - - - hard wheat flour PA-MF Medium hardGood lifetime X - - wheat flouand efficiency PA-XX-N Soft wheat, High - - - biscuit and efficiency rye flour Filter and brStrongest PA-HD - X - duster fabric (ASTM and XXX) products Purifier coveConstant PET-GG - - X tension   25 Step  1   Step  2   Step  3   26 Step  4   Step  5   Step  6   27 Step  7   Step  8   28 Gluing  Sieve  Cloth   29 Place  the  Clothing  in  the  Stretcher   Rule of Work: Size of Fabric = Frame Size Plus 3-1/2” 30 Apply  the  Tension   A. With the tension meter in place, open the valve B. Adjust tension to proper specified limits Apply  the  Adhesive   Spread  out  the  Adhesive   31 Apply  the  Ac▯vator   Cut  away  the  excess  material   Check  Your  Work   32 33


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