lab 8 baen 365

Introduction Conveyor systems are used to move material from one place to another. Some common conveyors types are auger, belt, bulk or mass flow, flight, bucket, and pneumatic. Of these common conveying systems this lab looked at auger, bucket, and belt conveying systems. An auger or screw conveying system uses a large helical shaped screw to move material through a rotary action. An auger is simple in size, low cost, available for horizontal, vertical and inclined applications but requires a larger torque and power to operate. A belt conveyor uses a belt to move material that is powered by a motor. Belt conveyors can be used for long lengths and require low horsepower to operate, o perate, however they are limited in the angle that it can operate. A bucket conveyor uses buckets to move material usually to a higher location. Bucket conveyors are efficient and high capacity, however they are expensive and hard to erect. In this lab an auger conveyor conveyor system was measured at different angles angles and the capacity and power required was calculated and compared. This lab also explored t he belt and bucket conveyor in a pure theoretical manner. Objective The objective of this lab is to measure capacity and power requirement of auger conveyor and determine the effect of auger angle on the capacity and power requirement. Also to design a belt conveyor and bucket conveyor based on given parameters. Methods and Materials Using a 4-inch auger setup with plastic pellets (bulk density=36lb/ft3) the power, weight, and speed were recorded at 15, 25, 35, and 45 degrees from the horizontal. The auger system was set to 15 degrees using an inclinometer and a trash can was place at the open end of the auger to collect the pellets. Using a stopwatch the auger system was timed for 30 seconds and turned on during which the speed was read using a tachometer. The power was read off a meter for which one revolution is 1.8 watt-hours and the finial weight of the loaded trash can was weighed using a scale. To determine the capacity at each angle dimensionless dimensionless analysis was used to convert the given information by the following steps: 1. Energy =(1.8 watt-hour /revolutions)*(Revolutions) 2. Knowing power =energy/ time where time= 30sec = 0.00833hr 3. Converted power to hp by unit conversion or 1hp=745.7W 4. Pellet weight = total weight – trash can weight 5. Pellet weight/ time= lb/hr= mass flow rate r ate 6. Capacity was then equally to volume/time which was found by dividing the mass flow rate by the density. After finding the capacity and power at each angle a graph of angle versus capacity and power was made to show the t he relationship. Using the equation given by the graph in excels the capacity and power

at zero degrees was found. By taking the ratio of t he capacity at each angle to the capacity at zero degree the capacity and power multipliers were found at each angle. To determine the capacity and power requirements at different speeds equation 1 and 2 was used respectively. Capacity at RPM= multiplier * capacity at angle (bu/hr)

(1)

Power at RPM= multiplier * power at angle (hp/10’)

(2)

To design a belt conveyor system the required capacity was first converted into cubic feet per min form bushel per hour. The using data given in table 8.1 of Agriculture Process Engineering book by Silas Henderson different belt width were guessed and the max capacity was calculated by multiplying the max speed at that width by the cross sectional area of 20 degree surcharge. The closest valve to the required capacity was chosen as the belt t o be use in the design. The operating speed (OS) was calculated by equation 3. OS= (required capacity (cfm)/max capacity (cfm) * max speed (fpm)

(3)

The total horse power was found by taking the belt horsepower plus the horsepower to lift the material plus the material horsepower. Form Agriculture Process Engineering book by Silas Henderson the equation for each of the respective horsepower were as follows: HPbelt = BS (A+BL) (4) Where, BS=belt speed (fpm) L=length (ft) A and B are constant found form the book. Hplift= (L*1.015*TPH)/1000 Hpmaterial=TPH (0.48+0.00302*L)/L

(5) (6)

Where, TPH=capacity (ton/hr) L=length (ft)

To design the screw conveyor the following equations from of Agriculture Process Engineering book were used to determine horse power.

Hp=Q*L*p*F/33000 (7) Where, Q=capacity (cfm) L=Length (ft) p=density (lb/ft3) F=material factor (from table 8.4) Using the table 8.3 in of Agriculture Process Engineering book and guess and check the screw diameter was found. To find the operating speed equation 3 was used and table 6.11 in grain drying, handling and storage handbook was used to size the motor. To design the bucket elevator charts form page 210 of Agriculture Process Engineering book were used to determine the model number and the horsepower requirement and head shaft diameter. The calculation can be seen in appendix A for bucket and belt conveyor systems. Results and Discussion Table 1: calculated values Angle (degre e)

Revs

Energy (Wh)

Power (W)

15 25 35 45 15(dry)

1.4 1.41 1.51 1.57 0.66

2.52 2.54 2.72 2.83 1.19

0.406 0.408 0.437 0.455 0.191

Weight (lb)

Mass flow rate(lb/ft^ 3)

Capacity (bu/hr)

Capacity multiplier

Power multiplier

69.84 58.92 53.42 38.96

8380.8 7070.4 6410.4 4675.2

187.14 157.88 143.14 104.39

0.82 0.70 0.63 0.46

1.09 1.09 1.17 1.22 0.51

Power for moving pellets 0.53 0.53 0.56 0.58

Table 2: corrected book values book values

correct book values to lab rpm

angle

bu/hr

power hp/10'

rpm

relative rpm

capacity multiplier

25

500

0.9

306

34

0.3872

0.35

193.6

0.315

35

480

0.9

300

33

0.38

0.34

182.4

0.309

45

450

1

306

34

0.3872

0.35

174.24

0.35

book value is for 4" auger at 900 rpm

hp multiplier

bu/hr

power hp/10'

200.00 180.00

y = -2.6297x + 227.03 R² = 0.9728

160.00 140.00     )    r     h     /    u     b     (    y    t    i    c    a    p    a    C

120.00 100.00 80.00 60.00 40.00 20.00 0.00 0

10

20

30

40

50

Angle(degree)

Figure 1: Relationship between capacity and angle. 0.460 0.450     )    r     h     /    u     b     (    y    t    i    c    a    p    a    C

0.440 0.430 0.420 y = 0.0018x + 0.3735 R² = 0.9268

0.410 0.400 0.390 0

10

20

30

40

50

Angle(degree)

Figure 2: Relationship between power and angle. As the angle increase the capacity goes down (figure 1) and as the angle increase the power consumption goes up (figure 2). This makes senses because the larger the angle get the further form the horizontal the auger gets and more gravitational force act on pulling the grain down thereby requiring more power to push the grain up. The computed capacity and power multipliers are the correction factor for the auger as it deviated from the horizontal (table 1). It takes approximately half of the total power required to move the pellets up the auger. When compare the calculated capacity and power to

the book values there is a big error in the difference. These corrected numbers were in reference to table 2-2 and 2-3 in the grain drying, handling and storage handbook. Designing the belt conveyor 300 ft long that conveys 25,000 bu/hr of corn at a idler angle of 20 degree and 20 degree surcharge a belt size of 36 inches can be used with a operating speed of 646 fpm and a total of 15 horsepower would be required. If the conveyor was at a 15 degree incline then only the total horse power would change to 53.2 hp and the rest of the design would remain the same because the horsepower require to lift the material comes into play when going against gravity. The design of the screw conveyor would need a screw diameter of 20 inches and a operating speed of  33.44 rpm. The total horsepower requirement of the system is 2.53 and can be accomplished by either a 3 hp electric motor or 5 hp gasoline motor. The design of the bucket conveyor requires a Thompson Conveyor BE516-7S with a head shaft diameter of 4 7/16 and a total horsepower requirement of 48.33 hp. (note all calculation are shown in appendix A) Summary Conveyor systems are used to move material from one place to another. This lab analyzed what happens to a auger conveyor as the angle is increased in terms of the capacity and power. The lab also designed a belt and bucket conveyor form given information. This lab showed that as the angle increase the capacity goes down (figure 1) and as the angle increase the power consumption goes up (figure 2).

References 1. Grain Drying, Handling and Storage Handbook, 2nd ed; Iowa State University, Ames, Iowa, 1987. 2. Henderson, Silas. Agriculture Process Engineering. Wiley and Sons, 1955.

Appendix A

Amin Momin BAEN 365 Lab 8 Conveyors April 3, 2012