Ch. 8 and 9 POM Notes
Ch. 8 and 9 POM Notes GRSC150
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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 http://www.youtube.com/watch?v=9XcftG-pt2E&feature=related 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 http://www.gwmfg.com/tb_HSdrive.htm 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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