Particle Size & Pelleting
60
Factors that Influence Corn Particle Size and its Impact on Pellet Quality Charles Stark Feed Science Program Department of Poultry Science North Carolina State University
Transcript of Particle Size & Pelleting
Factors that Influence Corn Particle Size and its Impact on Pellet Quality
Charles StarkFeed Science ProgramDepartment of Poultry ScienceNorth Carolina State University
Benefits to Particle Size Reduction
1. To increase improve feed digestion2. To improve the binding ability between
particles3. To improve the mixing efficiency of ingredients
in a compounded feed4. To increase particle homogeneity and prevent
ingredient separation
Effect of Particle on Finishing Pig Performance
F/G = microns x .000415175 + 3.066333 (r=.61; P<.01)
Goodband et al. 2003
Effect of Particle on Poultry Performance
Poultry diets have shown a mixed improvement in feed efficiency when particle size was reducedLitter vs. Cage StudiesPellets vs. Meal Feed FormThe effect of particle size on broiler performance
has been thought to be mediated through gizzard function
Factors That Affect Corn Particle Size
Grain Production System Genetics Moisture Growing Season Growing Conditions Drying Conditions Storage Conditions
Feed Manufacturing Grain Cleaning Grinding Equipment Hammermill Screen Size Tip Speed Screen Opening Air Systems
Roller Mill Corrugations Roll Differentials Gap Settings
Effect of Protein & Temperature on Pellet Quality
95
96
97
98
99
100
CP 15% CP 20% CP 25%
PDI,%
70 C 85 C
222 microns
Stark, 1994
95
96
97
98
99
100
CP 15% CP 20% CP 25%
PDI,%
70 C 85 C
561 microns
Determine the Economics of Grinding
Energy required to grind a given quantity of grain Production rate per horsepower hour Maintenance cost Labor Daily adjustments Roll and hammer changes
Screens, Hammers, Rolls Particle size Costs increase as particle size decreases
Source: Anderson
Effect of Screen Size on Efficiency
259310
368
454R² = 0.9844
0
100
200
300
400
500
#4 #6 #12 #24
lbs/hp
*hr
Hammermill Screen
Hammermill Screen Linear (Hammermill Screen)
Optimize the Grinding Process
Develop particle size specifications:NutritionistVeterinarianProduction specialist
Grinding process should produce a uniform particle size Particle size distribution should be predictableGrinding equipment should produce a sufficient amount
to meet the down-stream feed manufacturing process
PARTICLE SIZE ANALYSIS
Particle Size Definition
Particle size measurement was previously termed fine, small, medium, large, coarse, etc
The official method for particle size measures the geometric mean diameter (Dgw) and the standard deviation (Sgw)
Particle Size Analysis - Methods
ANSI/ASAE Method S319.4“Method of determining and expressing fineness of feed
materials by sieving”Sieving agents (optional)Sieve agitatorsDispersing agents
US Sieve Micron Size4 47606 3360 8 2380
12 1680 16 1190 20 840 30 590 40 420 50 297 70 210 100 149 140 105 200 74 270 53 Pan 37
Method of Determining and Expressing Fineness of Feed Materials by Sieving
ASAE S319.4 Procedure: Split the sample with a divider 100 ± 5 gram sample Place sieves in Ro-tap Run for 10 minutes Measure material on each sieve
ASAE
Particle Size AnalysisStep #2 Weigh 100 g
Step #3 Rotap 10 min Step #4 Record Weight on Sieve
Step #1 Split Sample
Optional Methods
Sieve Agitator Dispersing Agent
Sieve Agitators
Plastic Brushes RubberBalls
Particle Size ResultsDgw = 924 umSgw = 2.15Sample range (68%)
431- 1983 umUpper:
924 x 2.15 = 1983Lower:
924 / 2.15 = 431
Particle Size Results of Hammermill Corn
0100200300400500600700800900
1000
#6/#6 #12/#12 #24/#24
Microns None
AgitatorAgent
Particle Size Results of Roller Mill Corn
0
200
400
600
800
1000
1200
1400
1600
1800
15/0 25/15 35/30
Microns None
AgitatorAgent
Effect of Agitator and Dispersing Agent on Particle Size Analysis
0
100
200
300
400
500
600
700
800
Corn Wheat Sorghum
Microns
None Agitator Agent Agitator + Agent
GRINDING EQUIPMENT
Hammermill
Single Grinding Chamber Double Grinding Chamber
Hammermill Grinding Chamber & Particle Velocity
Source: Anderson
Factors Affecting Hammermill Efficiency Air system 1 – 1.25 CFM/sq in total screen
Total screen area 12-16 In2/HP
Open screen areaGreater than 4 In2/HP
Screen conditionNew screen = sharp edge
Hammer pattern2-2.5 HP/hammer
Hammer condition
Screen Selection
Source: Anderson
Screen Selection
Source: Anderson
Hammermill Air Assist System
H A M M E R M IL L
H A M M E R M IL L P L E N U M
F L A R E T R O U G H A U G E R
A IR L O C K
WARNING
!
!!
CARTER DAYSINCE 1881
ROTA
TING
MA
CHIN
ERY
INSID
E
!C
AUTI
ON
S T Y L E II F IL T E R
NAM
EPLATE
Effect of Screen Size and Hammer Tip Speed on Particle Size
Hammermill Capacity
C x O x HP = Capacity in Tons/hr2,000
C = Constant – Corn = 35 to 40O = Screen opening in 64th inchHP = Horsepower
Example: Corn ground through a 1/8 screen35 x 8 x 400 = 56 TPH
2,000
Source: Anderson
Conditioning and Pelleting
Factors Influencing Pellet Quality
25%*
15%**
20%*/**5%**
15%**
20%**
Formulation Conditioning Particle SizeCooling Die Specification Throughput
Modified Behnke, 1994
*Nutritionist, **Feed Mill
Effect of Process Factors on Pellet DurabilityProcess Factor % PDI
Control 70
Increase temperature 5oC 75.1
Increase temperature 10oC 79.4
Reduce fat by 0.5% 75.0
Add 1.5% calcium lignosulfonate 82.5
Decrease production rate by 20% 71.3
Add 10% wheat 75.4
Source: Dr. T.S. Winowiski
Conditioning Goals
Time Increasing the conditioning time will increase the
penetration of moisture and heat into the particles
Conditioning Time
Conditioning TargetsMoisture & TemperatureTarget 16 -18% moistureTarget 180 – 200 F temperature1% moisture increase per 25 F temperatureExamples: Winter 40 F to 190 F 150 F delta = 6% moisture 12% to 18%
Summer 90 F to 190 F 100 F delta = 4% moisture 12% to 16%
Nutrient Content of Corn Varieties
14.1
3.7
7.4
10.7
4.6
9.0
13.0
7.5 7.5
10.6
8.2 8.2
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
Moisture Crude Fat Crude Protein
NormalWaxyHOCHOWC
Zarate, et al 2004
Effect of Corn Variety and Fat Addition on Pellet Quality
14
40
62 65
35
6067
74
0
10
20
30
40
50
60
70
80
90
100
Finisher Withdrawal
PDI,
% NormalWaxyHOCHOWC
0
1
2
3
4
5
Finisher Withdrawal
Add
ed F
at,%
Zarate, et al 2004Die: 11/64 x 1.75, No 8 sieve
Effect of Corn Source on Throughput and Efficiency
1550
1600
1650
1700
1750
1800
1850
1900
1950
2000
Production Rate
lbs/
hr
Truck Corn Rail Corn
110
115
120
125
130
135
140
145
150
155
Pellet Mill Efficiency
lbs/
hp*h
r
Truck Corn Rail Corn
Conditioning - Truck Corn -181ºF, Rail Corn – 176ºF
Effect of Reduced Corn on Pellet Quality
0102030405060708090
100
Grower, PDI Finisher, PDI Grower, MPDI Finisher, MPDI
PDI,
%
Control-25%-50%-75%-100%
Grower Diet 65% Corn, Finisher Diet 68% Corn
Die: 5/32 x 1 ¼, CT: 180 F
Effect of Fat Type on Pellet Quality
50556065707580859095
100
Poultry Fat Soy Oil Choice WhiteGrease
Tallow
PDI,
%
Control 1.50% 3.00% 6.00%
Fat x Level interaction (P<.05)
Stark, 1994
Starch Gelatinization and Pelleting Maltose Equivalent, mg/g
Cond. Temperature
Meal Cond. Meal Cool Pellet Durabilitya, %
70° F 29.9 31.7 66.3 69.5
149° F 30.2 30.0 55.5 90.6
172° F 31.2 27.7 46.1 93.8
Gelatinization can occur due to swelling (water and heat) or mechanical disruption of the crystalline region of the starch granule
Skoch et al., 1981
SEM of the Pellet Surface
Courtesy: Ferket
Effect of Moisture on Electrical Consumption
5.21
5.25
5.19
5.14
5.09
5
5.1
5.2
5.3
12.2 13.1 14 14.7 15.1
kWh/
ton
Mash Moisture, %
Effect of Moisture on Pellet Quality
77.680.0
83.9
87.6 88.6
75
80
85
90
95
100
12.2 13.1 14 14.7 15.1
PDI,
%
Mash Moisture, %
Effect of Ingredients and Conditioner Setting on Pellet Quality
0102030405060708090
100
PDI,%
StandardParallel
Briggs et al., 1999
Effect of Protein and Temperature on Pellet Quality
95
96
97
98
99
100
CP 15% CP 20% CP 25%
PDI,%
70 C 85 C
Linear effect protein (P<.08)Temperature (P<.05)561 microns
Stark, 1994
Effect of Temperature on Pellet Quality
4651
5562
0
10
20
30
40
50
60
70
80
90
100
PDI,
%
85C (185) 88C (190) 91C (195) 93C (200)
Stark et al 2009
Pelleting Study
Factorial Design (3 x 3)Throughput kg/hr 500 (1100 lbs) 1000 (2200 lbs) 1500 (3300 lbs)
Die Thickness 29 mm (1 1/8) 35 mm (1 ⅜) 44 mm (1 ¾)
Measurements PDI, Pellet Mill Efficiency
Effect of Die Thickness on Pellet Mill Efficiency and Pellet Quality
98 9690
0
20
40
60
80
100
120
Die Thickness
kg/h
p*hr
29 35 44
32 35
60
0102030405060708090
100
Die Thickness
Pelle
t Dur
abili
ty In
dex
(PD
I), %
29 35 44
Linear (P<0.01)Linear (P<0.01)
Stark, 2009
Linear (P<0.01)
Effect of Throughput on Pellet Mill Efficiency and Pellet Quality
73
97
112
0
20
40
60
80
100
120
Througput
kg/h
p*hr
500 1000 1500
Linear (P<0.01)
55
41
30
0102030405060708090
100
Througput
Pelle
t Dur
abili
ty In
dex
(PD
I), %
500 1000 1500
Linear (P<0.01)
Stark, 2009
Fixed hp
Linear (P<0.01)
Effect of Die Thickness and Throughput on Pellet Mill Pellet Quality
0
1
2
3
4
5
6
7
ProductionRate
Energy
MTo
n -k
wh/
MT
0
20
40
60
80
100
PDI MPDIPe
llets
,%23% CP-Thick- Slow 23% CP-Thin-Fast
19% CP-Thick- Slow 19% CP-Thin-Fast
Buchanan et al, 2010
ac b
da
c bd
Effect of Die Thickness and Throughput on Pellet Mill Pellet Quality
01234567
Prod Rate Energy
Met
ric T
on/h
r -kw
h/M
T
0
20
40
60
80
100
PDI MPDI
Pelle
ts,%
23% CP-Thick- Slow 23% CP-Thin-Fast
19% CP-Thick- Slow 19% CP-Thin-Fast
b
d
Buchanan et al, 20010
ac d
b ac
3/16 x 1.5, 3/16 x 1.75, 180°F
Effect of Temperature and Steam Pressure on Pellet Quality
0
0.2
0.4
0.6
0.8
1
Production Rate
Met
ric T
on/h
r
70
75
80
85
90
95
100
PDI MPDI
PDI,%
LP(20)LT(180) LP(20)HT(200)HP(80)LT(180) HP(80)HT(200)
PSI p<0.03Temp p<0.01
Cutlip et al, 2008
PSI p<0.08Temp p<0.01
Die: 3/16 x 1 3/4
Effect of Temperature and Steam Pressure on Nutrients
02468
1012141618
Hot Pellet Moisture Starch Gelatinization Protein Denaturation23% CP-Thick- Slow 23% CP-Thin-Fast19% CP-Thick- Slow2 19% CP-Thin-Fast
a
b b
ab
Buchanan et al, 20010
Automation System Reports
Pellet Motor Horsepower Data
0
2
4
6
8
10
12
14
16
18
1 11 21 31 41 51 61 71 81 91 101
111
121
131
141
151
161
171
181
191
201
211
221
231
241
251
261
271
281
291
301
311
Pellet Motor Horsepower Data
0
5
10
15
20
25
hp
SD = 0.61
SD = 0.98
Conclusions
High conditioning temperature > 185Mash Moisture > 16%Small particle size, less than 400 micronsProduction rate will affect pellet quality
Questions
NC State Feed Mill Education Unit
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