Spring
2014
Mechanical Conveyor
Belt
By: Emily Brown
ET 494 Senior Design II
Instructor: Dr. Cris Koutsougeras
Advisor: Dr. Junkun Ma
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Mechanical Engineering
Southeastern Louisiana University
Spring 2014
Table of Contents
Abstract ............................................................................................................................................................................. 3
Purpose .............................................................................................................................................................................. 4
Methodology.................................................................................................................................................................... 5
Safety .................................................................................................................................................................................. 6
Material.............................................................................................................................................................................. 8
Conveyor 1 .................................................................................................................................................................... 10
Feed Requirements ..................................................................................................................................................... 11
Control Sequence ....................................................................................................................................................... 13
Frame ............................................................................................................................................................................. 14
Belt Selection................................................................................................................................................................ 17
Idler and Pulley............................................................................................................................................................. 20
Tension .......................................................................................................................................................................... 22
Drive............................................................................................................................................................................... 22
Motor ........................................................................................................................................................................ 23
Gear ........................................................................................................................................................................... 24
Coupling.................................................................................................................................................................... 24
Conveyor 2 .................................................................................................................................................................... 29
Feed Requirements ..................................................................................................................................................... 30
Preliminary Visual Logic ............................................................................................................................................. 31
Rough Frame Sketch................................................................................................................................................... 32
Belt Selection................................................................................................................................................................ 33
Idler and Pulley............................................................................................................................................................. 35
Tension .......................................................................................................................................................................... 36
Drive............................................................................................................................................................................... 37
Motor ........................................................................................................................................................................ 37
Gear ........................................................................................................................................................................... 39
Coupling.................................................................................................................................................................... 39
Actuator Selection ...................................................................................................................................................... 43
Excel Data ..................................................................................................................................................................... 46
References ..................................................................................................................................................................... 49
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Abstract
The aspects of this project consist of designing and aiding in the construction of two
conveyor belt systems which will be implemented into a biomass plant dealing specifically with
wood pellets. The both conveyor belts will consist of a drive powered by an electric motor,
the frame, and the belt itself. The belt feeder belt, which is designed first, will be receiving input
from the storage pile and delivering output to the boiler. The second belt will convey pellets
from the mill to storage and will have the capability of changing elevation with the respect to a
pivot point. Another notable portion of this analysis involves regulation of the pellets that will
be disposed of in the boiler at a given time. A depiction of the entire system is shown in Figure
1.
Figure 1
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Purpose
In order to correctly assimilate a conveyor belt system into a biomass plant certain design
factors have to be considered. Therefore, to understand the functionality of the system, a
preliminary control sequence (a broad overview) was developed to show dependent and
independent tasks. After the objectification of these tasks, assessments of the requirements of
each individual component were made. The sole purpose is to analyze the requirements,
design the structure, the driving mechanism, belt selection, sensing/monitoring system, as well
as elevation and overall frame movement. Considering the environment of fine particles that
will be present throughout, extra precaution will need to be taken in the form a self-cleaning
system as well as explosion proof equipment. Figure 2 shows Conveyor 1 which feeds the
boiler and conveyor 2 which conveys pellets from the mill to the storage.
Figure 2
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Methodology
Conveyor 1 (Feeds boiler)

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




Research conveyor belt types and applications
Research safety requirements
Develop a general function layout using Visual Logics
Rough frame design
Optimal frame dimensions based on boiler/steam turbine intake
Strength analysis (force and moment balance, bending stress, etc.) *
Motor selection
Design drive based on boiler/steam turbine intake rate
Determine necessary gear ratio (motor : drive – torque increase and speed reduction)
Belt selection
Placement of idlers on the frame (tension uptake)
Pellet regulation device- either before or after the conveyor
Conveyor 2 (from mill to storage)












Develop a general function layout using Visual Logics
Rough frame design
Optimal frame dimensions based on pellet mill output
Strength analysis (force and moment balance, bending stress, etc.)
Motor selection
Design drive based on pellet feed rate
Determine necessary gear ratio (motor : drive – torque increase and speed reduction)
Belt selection
Placement of idlers on the frame (tension uptake)
Add finer details to Visual Logic
Elevation sensor for changing conveyor height with respect to storage pile height
Actuator selection
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Safety Requirements
The environment in which the conveyor is located is considered extremely dangerous because
of the involvement of heat, dust, and moving parts. Standards have been set by organizations
such as ANSI, CEMA, and OSHA.
OSHA
OSHA subpart: Helicopters, Hoists, Elevators, and Conveyors briefly covers areas that need
attention such as breaking, warning signals, remote operation, Emergency stop switches, and
procedures such as LOTO. The following information and standards were taken from the
OSHA website:
Part Number:
Part Title:
Subpart:
Subpart Title:
Standard Number:
Title:

1926
Safety and Health Regulations for Construction
N
Helicopters, Hoists, Elevators, and Conveyors
1926.555
Conveyors.
1926.555(a)(1)
Means for stopping the motor or engine shall be provided at the operator's station.
Conveyor systems shall be equipped with an audible warning signal to be sounded
immediately before starting up the conveyor.

1926.555(a)(2)
If the operator's station is at a remote point, similar provisions for stopping the motor or
engine shall be provided at the motor or engine location.

1926.555(a)(3)
Emergency stop switches shall be arranged so that the conveyor cannot be started again
until the actuating stop switch has been reset to running or "on" position.

1926.555(a)(7)
Conveyors shall be locked out or otherwise rendered inoperable, and tagged out with a
"Do Not Operate" tag during repairs and when operation is hazardous to employees
performing maintenance work.
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ANSI
ANSI B20.1-1957, Safety Code for Conveyors, Cableways, and Related Equipment provides
further details on required safety parameters and are paraphrased below from lawresource.org.

605 Backstops and Brakes:
a- Guards should be in place to prevent potentially dangerous access
b- Mechanically released brakes should be designed so that if the power source is
interrupted and brakes are off, the descent of the load occurs at a controlled speed.
In the case of electrically released breaks, the breaks do not activate until the power
is applied to the motor or automatically in the scenario of power supply failure.

606 Overload Protection:
Protection of electric motors, conveyor, and mechanical drive and the presence of an
overload device designed to shut off electric power or disconnect conveyor or drive parts
quickly.

609 Guards:
Conveyors near workstations should have guards.

610 Interlocking Devices:
Mechanical and Electrical devices on the conveyor system should be provided with an
automatic stop in the case of feed blockage in bin, chute, hopper, etc.
CEMA
CEMA handbook for Belt Conveyors for Bulk Materials briefly makes note of the fact that labels
are required near all moving parts. These labels can be obtained from CEMA Label Placement
Guideline BH-1 which is intended solely for bulk material handling conveyors.
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Conveyed Material
Material Class Description –E45TVY
The material being considered for the extreme case is pine wood. Wood particles in the
extreme case can be categorized as stringy, irregular, fibrous, or sluggishly flowing. The Material
Classification Code System Table uses various descriptions related to the following categories:
Size, Flowability Angle of Repose, Abrasiveness, and Miscellaneous to classify materials. The
code E45TVY was derived using this table based on the irregular size, sluggish material flow due
to material interlocking and matting, an angle of repose greater than 40 degrees, generally
nonabrasive characteristic, mildly corrosive, very fluffy and light characteristics, and the
explosive dust environment.
Using the Table of Flowability, it was determined that the angle of surcharge will at max be 30degrees and the angle of repose will be greater than 40-degrees. These angles will give a
general depiction of the average cross sectional area of the load. Given such a high angle of
repose and the average material density (38lb/ft^3), the material will have a tendency to flow
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downward on an incline therefore it is noted that the maximum allowable inclined angle is 30
degrees.
A summary of the material characteristics is shown below in Excel Table 1.
Size
Flowability Angle of repose
Abrasiveness
Miscellaneous
Irregular- stringy, interlocking, mats together
Sluggish-Angle of Repose > 40
Nonabrasive
Very Dusty
Contains Explosive Dust
Interlocks or Matts
Excel Table 1: Material Characteristics
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E
4
5
L
N
V
Conveyor 1
Pellet Trajectory
Pellets in moved from storage travel through a regulation gate or filter which prevents
oversized pellets from going through, this method helps to reduce irregularities in load sizes.
After the pellets pass through the loading chute, they travel the span of the conveyor. Upon
leaving the exit chute, the pellets are fed to boiler and ultimately fuel is derived from the use of
heat energy (i.e. steam).
Deliverables Conveyor 1
**This is a tentative Representation
Task:
Completion Date:
Actual Start Actual End
Control Sequence
Throughout
10/5/2013
Research Safety
10/12/2013
10/12/2013 10/12/2013
Boiler & Mill Req.
10/23/2013
10/23/2013 10/23/2013
General Frame Design
10/25/2013
10/21/2013 10/21/2013
Research Standards
Throughout
10/25/2013
Research Suppliers
Throughout
10/26/2013
Order CEMA Handbook
When received
11/12/2013 11/19/2013
Belt Selection
11/17/2013
11/15/2013 11/17/2013
Drive Calculations
11/19/2013
11/17/2013 11/19/2013
Motor Selection
11/19/2013
11/17/2013 11/19/2013
Worm Gear Selection
11/22/2013
11/19/2103 11/22/2013
Compile Calculations
11/26/2013
11/26/2013 11/26/2013
Select Coupling
12/1/2013
11/22/2013
12/3/2013
Gear and Drum Connection
12/3/2013
12/2/2013
12/3/2013
Final Frame Schematic
12/3/2013
12/3/2013
12/3/2013
Note: Completion date denotes a projected time
Excel Table 2: Conveyor 1 Deliverables
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Conveyor Requirements: Boiler/Steam Turbine
After meeting with Mr. Byron and Mr. Dawson at Southeastern Louisiana University’s
Sustainability Center, the starting point of this project consisted of a brief introduction to the
desired capabilities of the conveyor system as a whole. As figure 2 illustrates, the job of
Conveyor 1 is to displace pellets from the storage to the boiler. In the case of design, the only
customer specified constraint of this conveyor is the feed rate to the Boiler/Steam Turbine;
specified as System 3 (Table 1). Using the available data in Table 2, the wood type with the
lowest BTU value per cord (pine) is considered as the most extreme case. A greater capacity of
this type will be needed to obtain the optimal MMBTu/hr rating allotted by the Boiler/Steam
Turbine.
Table 1: Boiler/Steam Turbine Characteristics
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Table2: adapted from - ttp://umaine.edu/publications/7216e/
With the required feed rate of the boiler and the minimum heat value of pine wood, a
preliminary calculation of maximum capacity over unit of time was conducted to get a general
idea of what type of loading is necessary. The calculations are depicted below.
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Control Sequence
The control sequence using Alerton Visual Logic for the project in its entirety is still being
developed but the derived information thus far includes the sequences below:
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Frame Design
Rough Sketch:
To begin the developmental phase of the frame design, a rough sketch was made (shown in
Figure 1). This sketch allowed for the identification of variables that need to be designed or
determined through calculation. Some of these include: belt length, incline angle, drum
placement, idler placement, drive placement, input, output, and cleaning equipment.
Figure 1: Rough Sketch
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Final Schematic for Conveyor 1:
Using various parameters both specified and designed throughout the project (including various
maintenance clearances) the schematic shown below was developed:
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Belt Selection
A variety of details were necessary for the dimensions of the belt. All of the information was
obtained from either tables or calculations that were specified within the CEMA Belt
Conveyors for Bulk Materials.
Belt speed and Belt width
Using the material characteristics, one can determine the recommended maximum belt speeds
using Table 4.2. The cons of choosing a higher belt speed ultimately lead to reduced life of the
belt. For simplification purposes the belt speed of 600 fpm was chosen with the range of Belt
Width 24-30 in.
The next unknown variable in this case is the belt width. For the ease of design in the allotted
time frame, a flat belt will be selected, which means that the belt has a trough angle of 0
degrees.
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Belt width Selection:
The available data of the capacity which was calculated as 2,440 lb/min can be converted to a
usable variable of capacity in tons per hour which is 73.2 tph. Using this data, an equivalent
Q100 rating (capacity at 100fpm) of 770 tph at an angle of surcharge of 30 degrees allows the
selection of the belt width of 24 in which is an overdesign for the purpose of safety. The
method of selection is shown in Table 4.7.
After the belt width is determined, the edge distance in accordance to Table 4.3 is determined
to be 2.22 in.
Also determined with the belt width is the skirt board width found in Table 4.10. The
functionality of the skirt board is to retain sediment such as dust or debris.
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** In the place of these skirt boards, corrugated sidewalls will be used as a cleaning mechanism.
Belt Covers
The belt will be used in an environment that will require fire/ flame resistance. This factor
limits the belt cover material selection to SBR, nitrite, polychloroprene (neoprene) and PVC
which are routinely used in similar applications. These types of covers will prevent spreading of
a fire if one does happen to occur in this potentially flammable environment.
RMA Grade 2 belting was selected because of its good quality in the applications of heavy duty
service. Using table 7.5, which is specific from RMA Grade 2, a minimum carry thickness
(between 1/16 to 1/8 in) is chosen.
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Again using a material property a minimum pulley cover thickness is selected.
Belt connection:
Belts are sold in sectional lengths; therefore a method of connection needs to be chosen. The
two choices that were presented in the handbook were vulcanized or mechanically fastened.
For this specific purpose, vulcanized splices were chosen because of the following advantages
highlighted by CEMA:
1. It has the highest practical strength.
2. Long service life.
3. Cleanliness
The cons that were noted included: costly, replacement can be time consuming, and they are
generally more complex than mechanical fasteners. Again considering the environment, this
seemed to be the correct choice based on the required safety measures.
Idlers and Pulleys
For the purpose of tension uptake, idlers are implemented. The factors that need to be
considered when selecting idlers are primarily: the number of idlers required on the return and
uptake side, the diameters, and the placement. Since the belt is flat, all return and carrying
idlers will be flat also.
Spacing:
Distance between idlers on both loading and return side.
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Belt Load:
Determining the belt load requires the bulk density of the material which is specified as
38lbf/ft^3 and the belt width.
Since the belt load (belt weight plus load weight) is less than 475 lbf at a belt width of 24in
which is specified in Table 5.35 CEMA C idler with a diameter of 4in was selected.
Table 5.1 gives a general outlook on the Classification and the size of potential idlers.
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Pulley
The most common type of pulley is the standard steel pulley which will be utilized at the drive
end for the sake of simplicity. To discourage belt misalignment these pulleys are usually
crowned at permissible dimensions which are defined by CEMA B105.1. On the dead shaft,
which is located at the loading end, a spiral wing pulley will be used to help keep the belt
aligned. The handbook used only provides minute detail about the drums; however, given that
standard pulley diameters are 8, 10, 12, 14, 16, 18, 20, 24, 30, 36, 42, 48, 54, and 60 inches, the
diameter of 8 inches is selected for the both the drive and the dead shaft due to the small scale
size of the conveyor.
Tension
Conveyor systems are divided into three cases when it comes to strength analysis, specifically
tension. For the purpose of this project the Basic Conveyor case was used. This type of
conveyor is defined by CEMA as:




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



A single flight of less than 800 ft in length
A single free flowing load point
Inclined or horizontal but without curves
A belt with a fabric carcass
Flat or equal roll troughing idlers
A single drive
Unidirectional or reversing up to 500 fpm
A single gravity or fixed take up
A maximum belt tension of 12,000 lbf
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Thus far all of these basic qualifications have been met by the obtained data. It should be noted
that a conservative approach was used to the calculation of tension due to the short time
frame.
Drive
The values derived in the portion were compiled into a table located at the end of this section.
Necessary parameters for the drive portion involving the pulley as well as the motor include:
power, rpm, and torque. Equation 2 is used to determine the unknown values.
Equation 2:
Equation 3:
𝑇𝑜𝑟𝑞𝑢𝑒 (𝑙𝑏𝑓 ∗ 𝑖𝑛) = 63,000
𝑛(𝑟𝑝𝑚) =
𝑉∗60
2𝜋𝑟
𝑃𝑜𝑤𝑒𝑟 (𝐻𝑝)
𝑛(𝑟𝑝𝑚)
where V= belt speed
Motor:
Assuming that the power calculated for the pulley is equal to the power provided by the motor
a 3 phase AC explosion proof motor was selected.
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Drive
Power conveyor (hp)
Pulley Speed (rpm)
Conveyor Torque (lbf*ft)
Power motor (hp)
Motor Speed (rpm)
Gear ratio
Excel Table 3: Drive
7.638870707
147.13
28.55555556
10
1180
8.020118263
To ensure that the motor and the gear ratio selected equals or surpasses the torque required
to drive the belt, it was necessary to back track through calculations which is shown in the
table below. Given the fact that no motor is 100% efficient, power loss was accounted for when
conducting the calculation.
Reverse Calculation
Full load efficiency
Motor Power (hp)
Actual power (hp)
Rpm Motor
Rated torque (lbf*ft)
Gear ratio
Pulley Torque (lb*ft)
RPM Pulley
Pulley Power (hp)
0.895
10
8.95
1180
39.81991525
8
318.559322
147.5
8.95
Excel Table 4: Reversed Drive Data
The results of this calculation and the section of a gear ratio of 8:1 show that the motor speed
of 1180 is reduced to about 147.5 rpm and the motor torque was increased at the pulley from
approximately 40 lbf*ft to 319 lbf*ft which was greater than the previously calculated and
surpasses requirements.
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Gear
The major reasons for selecting a worm gear are because of the high efficiency and the compact
design. Common worm and worm gear materials which have been selected for this application
include, steel to bronze respectively. With the calculated gear ratio of 8:1 a worm and worm
gear were selected.
Worm gear (steel - bronze)
Pitch Diameter (in)
6
Double Threaded Gear ratio (min)
10:1 to 20:1
Quad Threaded Gear ratio (min)
4:1 to 10:1
Excel Table 5: adapted from data fromhttp://www.bostongear.com/products/open/chart-worm.htm
Coupling Selection: (1010GC02 Double Engagement)
To correctly select the appropriate coupling to connect the worm gear to the motor shaft an
online manual supplied by Power Drive is used. The necessary parameters (as specified by the
technical manual) and their corresponding values have been arranged into an Excel table which
is shown below
Coupling Selection Data
Motor horsepower
Running rpm
Application or type of equipment
Motor Shaft Diameter(in)
Worm Gear Shaft Diameter (in)
Gap Between Shafts
Note
10
1180
Conveyor
0.62 Found in Motor Schematic
0.75 Found Using 8:1 Ratio (6in/8)
0.25 Assumed
Excel Table 6: Coupling Selection
The following schematic is used to determine the motor shaft diameter for the above Excel
Table.
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**Images adapted from Baldor Explosion Proof Motors technical Manual
1. Motor Torque
Now that the specified values are known and organized, the first step is to determine the
system torque which was calculated in the previous Drive section to be about 534 lb-in.
2. Service Factor
Next, the service factor for the conveyor application was determined to be 1.25 considering
that the conveyor is essentially a bucket conveyor.
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Table adapted from powerdrive.com
3. Coupling Rating
After the S.F. (service factor) is determined the minimum required coupling rating can be
calculated by multiplying the service factor by the torque:
𝑀𝑖𝑛𝑖𝑚𝑢𝑚 𝐶𝑜𝑢𝑝𝑙𝑖𝑛𝑔 𝑅𝑎𝑡𝑖𝑛𝑔 = 667.5 𝑙𝑏 ∙ 𝑖𝑛
4. Design Hp
To determine the design horsepower, the actual power is multiplied by the service factor
yielding:
𝐷𝑒𝑠𝑖𝑔𝑛 𝐻𝑜𝑟𝑠𝑒𝑝𝑜𝑤𝑒𝑟 = 15ℎ𝑝
5. Type
Using the shaft diameters of the worm and the motor, rated torque of the coupling, and
allowable speed, type 1010GC02 was selected from the table below
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Table adapted from powerdrive.com
Figure adapted from powerdrive.com
6. Size
Size is selected by using the motor speed; in this case 1180rpm which is not located on the
chart but rather it is in between the two speeds of 1450 and 1170. The exact value is not
necessary because the purpose is to confirm or deny the selection of the coupling is correct in
the previous step. Using the maximum coupling rating of 232 and 187 one can determine that
the selection of 1010G is suitable because the rated hp of the selection (15hp) is much less than
these values.
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Table adapted from powerdrive.com
Worm Gear to Drive Shaft Mounting:
For optimal performance and safety reason, a method of connection of the worm gear to the
drive pulley of the conveyor needs to be determined. In a high dust environment, it is standard
to provide a cover/guard on all moving parts. This factor means that housing should be
integrated into the connection method.
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Conveyor 2
Design Purpose:
Conveyor 2 serves the purposed of relaying pellets from the pellet mill to storage. The
auxiliary devices that will be incorporated within this conveyor that were not incorporated
within the design of Conveyor 1 include elevation change and the implementation of a sensor.
The capability of changing elevation will be a function of pellet height in storage and a method
of determining pellet height is through use of a sensor. The deliverables are outlined below
Time Line Conveyor 2 (Pellet Mill to Storage)
**This is a tentative Representation
Task:
Completion Date:
Actual Start
Actual End
Rough Frame
1/28/2014
1/25/2014 1/28/2014
Preliminary Visual Logic
1/28/2014
1/26/2014
2/1/2014
Belt Selection
2/11/2014
2/2/2014 2/10/2014
Pulley Calculations
2/18/2014
2/15/2014 2/15/2014
Drive (Gear Ratio)
2/25/2014
2/24/2014 2/25/2014
Motor Selection
3/4/2014
2/24/2014 3/10/2014
Gear Selection
3/4/2014
3/10/2014 3/10/2014
Coupling Selection
3/11/2014
3/10/2014 3/10/2014
Gear and Drum Connection
3/11/2014
3/10/2014 3/11/2014
Actuator Selection
3/18/2014
3/17/2014 3/18/2014
Strength Analysis
4/6/2014
3/30/2014
Final Frame Schematic
4/11/2014
Final Visual Logic
4/28/2014
Note: Completion date denotes a projected time
Excel Table 7: Conveyor 2 Deliverables
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Conveyor Feed Requirements: Pelt Mill
The loading requirement is determined by the selected pellet mill. The electric pellet mill
shown in figure below, has a 30HP motor and an output of 1,323-1,764lbs/hour , this mean that
the material is pushed through the die holes at this rate. Using maximum and minimum
capacity ratings, a ton per hour value is calculated as specified by the CEMA Handbook.
Figure adapted from gardenheat.com
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Visual Logic
Feedback is a favorable attribute to have in any system; without feedback it becomes more
difficult and, at times, impossible to monitor all components of a system for parameters like
temperature, speed, elevation, tension, or any other types of output or input that is of great
importance to safety as well as efficiency. An overview of the input and output are summarized
in order to produce a visual logic layout.
Speed Control for monitoring load
DDC should check speed continuously. If speed is greater than or equal to upper limit, torque
is too low. If speed is less than or equal to lower limit, then torque is too high. If either of
these conditions is false, continue to loop and record torque range. If either of these
conditions is true, alert user.
Elevation Control
Check current position via sensor. If pellet pile position is equal to initial height (4ft) (range:
3.5-4ft), time range, check elevation again, if pellet position is still greater than within range,
increase elevation by 2ft. Set position as new initial position. If pellet pile position is equal to
initial height (6 ft) (range: 5.5ft -6ft), time range, check elevation again, if pellet position is still
within range, increase elevation by 2ft. Set position as new initial position. If pellet pile position
equal to initial height (8 ft) (range: 7.5-8ft), time range, check elevation again, if pellet position is
still within range, sound alert and stop conveyor. When signal received from user, decrease
elevation to 4ft (reset). Else, continue.
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Initial Frame Design
With the basic information provided, a rough sketch of the frame is done to provide an
illustration of the pellet trajectory and to determine other necessary factors that may need to
be considered in the design of this conveyor.
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Belt Selection
The first step in determining the specific characteristics of the belt that will be used in conveyor
2 is to consider the material that will be transported. The same material will be transported in
the both conveyor 1 and conveyor 2, the same material characteristics will apply to conveyor 2.
Using Table 4.2 a range of recommended belt speeds are shown, an adaptation of this table is
show in the Excel Table 7.
Belt Characteristics (Table 4.2)
Grain or Other free flowing, nonabrasive material
Belt Speeds
(fpm)
Belt Width
(in)
400
600
800
Excel Table 7: Recommended Speed
18
24-30
36-42
In order to select the appropriate width and speed the capacity at 100 fpm is calculated and
Table 4.7. The maximum value is considered for extreme loading conditions and the belt speed
of 400fpm is assumed for the conversion of capacity at 100fpm.
Capacity
Max
Capacity (lb/hr)
Capacity (tph)
Capacity (ft^3/hr)
Capacity (Q100 @ 400fpm)
Min
1764
1323
0.882
0.6615
55.70526 41.77895
13.92632 10.44474
Excel Table 8: Calculating Capacity
Using the maximum Q100 of 13.92632 ft3/hr and the corresponding values in Table 4.7 the
information in the excel sheet is obtained.
Table 4.7: Flat Belt Standard Edge
Distance
Surcharge
30
Max Q100 (ft^3/hr)
763
Cross Sectional Area(ft^2)
0.127
Belt Width (in)
18
Excel Table 9: Area of Material
The maximum Q100 value listed on the table (763 ft3/hr) greatly surpasses the maximum
calculated Q100 specific for the conveyor load, which means that the cross sectional area
specified in Table 4.7 will also be greater than the actual cross sectional area (denoted in Excel
Table 9).
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Belt Load Cross Sectional Area in ft^2
Area of Trapezoid
Area of Circular Segment
From Equations on Page 61
Total Area
Total Area based on Design
Excel Table 10: Cross Sectional Area
Value
0
8.364642
0.058088
0.001289
Although these values are much greater they will suffice for the design constraints given that
the values are the lowest specified values for a surcharge angle of 30 degrees. Along with the
selection of recommended belt speed and belt width, is the selection of standard edge distance
(Table 4.3) as well as standard skirt board width (Table 4.10). Given that the belt width is
determined to be 18 in, the corresponding standard edge distance and standard skirt board
width are 1.89 in and 12 in, respectively. After these values were chosen, the next factor to
consider is belt cover. The environment of conveyor 2 is the same as conveyor 1; therefor, the
same type of belt cover will be used. Belt cover material selection is limited to SBR, nitrite,
polychloroprene (neoprene) and PVC. These types of covers are ideal in a potentially
flammable environment.
RMA Belt Grade
The performance capabilities of RMA belt grade 2 (Table 7.4) make it an appropriate candidate
for conveyor 2. Table 7.5 and 7.6 yield values of minimum carry thickness and minimum belt
cover thickness, both of these values amount to a total thickness range of 3/32in to 5/32in.
As a method of connection, a vulcanized spliced is recommended because of its cleanliness and
high rated strength.
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Idlers and Pulleys
Idlers
Idlers will be used for tension uptake to avoid excessive belt sagging. Table 5.19 shows
suggested idler spacing which is dependent upon belt width (18in) and the bulk density of the
material (38 lbf/ft3). The suggested idler spacing is every 5.5 ft and the return idlers are every
10ft.
The idler diameter is determined by the belt weight per length, in this case it is for a multiple
ply belt (Table 5.22). Given the bulk density of 38 lbf/ft3 and the belt width, the average belt
weight is approximately 3.5 lbf/ft.
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Next, using Table 5.1 the C4 CEMA standard idler with a diameter of 4in is selected.
CEMA Idler Classification
Roll Diameter
Belt Width
Classification (in)
(in)
B4
4 18 through 48
B5
5 18 through 48
C4
4 18 through 60
C5
5 18 through 60
**Adapted from table 5.1
***Cema B & C load rating based on minimum
of L10 of 30,000 hours at 500rpm
Excel Table 11: Idler Class
Pulley
The dead shaft and the drive shaft pulley will both be standard steel pulleys are assumed to be
the minimum available size of 8in in diameter. A crown in both pulleys can be used as an
alignment mechanism. As mentioned previously in the design of conveyor 1, there is very little
information available for selecting an appropriate pulley.
Tension
The equation denoted is used for basic conveyor tension calculations, which neglects energy
losses. Excel Table 12 was constructed using the effective tension equation at various heights
and elevation angles.
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Effect Tension (Basic Method)
Elevation Angle
Weight of Material (lbf/ft)
0.0735
Degrees
Radians
Weight of Belt (lbf/ft)
3.5 Table 5.22
Carry Length (ft)
18
Max Height (ft)
8
30
0.523599
Mid Height (ft)
6
22
0.383972
Min Height (ft)
4
14.5
0.253073
Effect Tension (lb)
5.68092
Min Height Effective Tension
5.38692
Load Based Tension (max H) (lbf*ft) 113.1004
Load Based Tension (mid H)
152.6295
Load Based Tension (low H)
228.3569
Excel Table 12: Tension
Drive
The drive design will consist of a DC motor, gear reduction to increase torque and reduce
speed, and a coupling device. Pulley speed is calculated using the equation: 𝑃𝑢𝑙𝑙𝑒𝑦 𝑟𝑝𝑚 =
where V equals belt speed.
Pulley speed (rpm)
Pulley Radius (in)
Belt speed (FPM)
Pulley speed (rpm)
𝑉
2𝜋𝑟
4
400
191.0828
Excel Table 13: Pulley Speed
Using pulley radius and the effective tension values for torque and power were calculated.
Pulley
Torque max (lbf*ft)
Torque min (lbf*ft)
Power Max (hp)
Power Min (hp)
76.11896
37.70012
2.767962
1.370913
Excel Table 14: Pulley Power and Torque
Motor
The classification of wood debris as Class III Fibers (easily ignitable), requires that an explosion
proof motor be used. Assuming that the power calculated for the pulley is equal to the power
provided by the motor a 3 phase AC explosion proof motor was selected using the tension
results.
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Motor Characteristics
Power (hp)
3 Actual Power
Torque (lb*ft)
9.06 Actual Torque
Speed (rpm)
1755 Actual Speed
Full Load Efficiency (%)
89.5
Efficiency
0.895
2.685
8.1087
1570.725
Excel Table 15: Motor Characteristics
Using the pulley rotational speed, torque, and calculated power values along with the values of
motor power, speed, and rated torque a gear ratio of approximately 9:1 is appropriate for a
speed reduction and a torque increase.
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Drive Calculations
Pulley Torque lbf*ft
76.11896
Pulley speed (rpm)
191.0828
Pulley Power (hp)
2.767962
Motor Power (hp)
3
Motor speed (rpm)
1755
Motor Torque (lb*ft)
9.06
Gear Ratio
9.1845 Speed decrease
8.401652 Torque Increase
Excel Table 16: Drive Calculations
To verify that the motor will be able meet the design expectations, a recalculation using only
the variables of the motor and the gear ratio are used to calculate the output at the pulley. The
torque output will be greater than necessary but the values will suffice.
Reversed Calculations
Motor Power (hp)
3
Actual Power
2.685
Motor Speed (rpm)
1755
Motor Torque
9.06
Gear Ratio
Pulley Torque
Pulley Speed
Pulley Power
9.1845
83.21157
191.0828
3.025875
Excel Table 17: Reversed Drive Calculations
Gear Selection
Due to the compact nature of the overall conveyor design and the familiarity with the gear
type, a compact worm gear is selected for the drive design. The worm gear also has the
unique capability of being classified as a right angle drive, which means that the gear and the
worm are perpendicular to one another (shown in figure). Efficiency ranges from 50-90% and
depends on the gear ratio and the material types.
BostonGears.com provided a specification sheet that helped with the selection of the
appropriate sized worm and worm gear. The selection is presented in an excel table.
40| P a g e
Worm Gear
Diametral Pitch (in)
8
Worm Material
Steel
Worm Gear Material
Cast Iron
Double thread Ratios
10:1 to 30:1
Excel Table 18: Worm Gear Calculations
Coupling Selection: (1010GC02 Double Engagement)
To correctly select the appropriate coupling an online manual supplied by Power Drive is used.
The necessary parameters (as specified by the technical manual) and their corresponding values
have been arranged into an Excel table which is shown below
Coupling Selection
System Torque (lb*in)
108.72
Motor power (hp)
3
Running Speed (rpm)
1755
Application Type
Conveyor
Motor Shaft Diameter (in)
1.12 10:1 Gear ratio
Worm Gear Shaft Diameter
0.8
Gap between shafts (in)
0.25 assumed
Excel Table 19: Coupling
The following schematic is used to determine the motor shaft diameter for the above Excel
Table.
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**Images adapted from Baldor Explosion Proof Motors technical Manual
1. Motor Torque
Now that the specified values are known and organized, the first step is to determine the
system torque which was calculated in the previous Drive section to be about 108.72lb-in.
2. Service Factor
Next, the service factor for the conveyor application was determined to be 1.25 considering
that the conveyor is essentially a bucket conveyor.
Table adapted from powerdrive.com
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3. Coupling Rating
After the S.F. (service factor) is determined the minimum required coupling rating can be
calculated by multiplying the service factor by the torque:
𝑀𝑖𝑛𝑖𝑚𝑢𝑚 𝐶𝑜𝑢𝑝𝑙𝑖𝑛𝑔 𝑅𝑎𝑡𝑖𝑛𝑔 = 135.9 𝑙𝑏 ∙ 𝑖𝑛
4. Design Power (Hp)
To determine the design horsepower, the actual power is multiplied by the service factor
yielding:
𝐷𝑒𝑠𝑖𝑔𝑛 𝐻𝑜𝑟𝑠𝑒𝑝𝑜𝑤𝑒𝑟 = 3.75ℎ𝑝
5. Type
Using the shaft diameters of the worm and the motor, rated torque of the coupling, and
allowable speed, type 1010GC02 was selected from the table below
Table adapted from powerdrive.com
Figure adapted from powerdrive.com
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6. Size
Size is selected by using the motor speed; in this case 1755rpm which is not located on the
chart but rather it is in between the two speeds of 1750 and 1800. The exact value is not
necessary because the purpose is to confirm or deny the selection of the coupling is correct in
the previous step. Using the maximum coupling rating of 280 and 288 one can determine that
the selection of 1010G is suitable because the rated hp of the selection (3.75hp) is much less
than these values.
Table adapted from powerdrive.com
Worm Gear to Drive Shaft Mounting:
For optimal performance and safety reason, a method of connection of the worm gear to the
drive pulley of the conveyor needs to be determined. In a high dust environment, it is standard
to provide a cover/guard on all moving parts. This factor means that housing should be
integrated into the connection method. The worm gear will be bolted onto the shaft.
Actuator
The main characteristic that separates the conveyor relaying pellets to storage from the
conveyor relaying pellets to the boiler is the ability to change elevation with respect to the
increasing or decreasing height of pellets in the storage area. Research was conducted on
various types of linear hydraulic, pneumatic, and electromechanical actuators to determine the
appropriate fit. The following conclusions were reached:


Although hydraulic actuators are very precise and are used in high force applications,
they may present problems in control difficulty. Also addressed is the possibility of
leaking hydraulic fluid and the need for a constantly running compressor.
In the case of a pneumatic actuator, a compressor is also required. A favorable
attribute is the quick response time. Due to the compressibility of air and the resulting
low load capability, the pneumatic actuator will not be a likely candidate.
44| P a g e

Electromechanical are cause less waste in the form of emissions (no air or fluid) and are
more reliable because of ease of control. One pitfall of electromechanical actuators is
the initial cost.
Due to the more favorable attributes an electromechanical linear actuator is selected based on
the maximum load that will be lifted. I contacted a Duff-Norton supplier who sent a linear
actuator technical manual. The figures below show the possible choices based on a capacity.
There is a rather small load of approximately 127 lbs with just the material and the belt weight.
The motor alone weighs 137 lbs, yielding a net value of 264lbs. Once the strength analysis of
the frame is completed a better assessment of the total weight will be made. For intents and
purposes, the range of actuators considered will be in the capacity range of 500lbs.
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Because of the larger retraction length, MPD6905-18 is selected. To find where the actuator
should be placed to achieve a height range of 8ft similar triangles are used. A brief explanation
is shown below:
Actuator placement on the frame
Conveyor height (ft)
Conveyor carry length (ft)
Conveyor length (ft)
Actuator Retract length (ft)
cos 30
Retract Position (hypotenuse) (ft)
x position (ft)
8
16
13.86
2.1875
0.866
4.375
3.78875
Excel Table 20: Drive Calculations
26.25
16 ∗ cos(30) ∗ ( 12 )
∴𝑥=
8 ∗ cos(30)
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Excel Data Conveyor 1
Parameters of the Conveyor:
Know Values:
Angel of incline(degrees)-(radians)
Inclined length (ft)
Horizontal length (ft)
Capacity (lb/min)
Bulk density (lbf/ft^3)
Total Belt length (ft)
Carry Length (ft)
Drop height(ft)
Drum Diameter (in)-(ft)
Center of belt (in)
Chart 1
Calculated values
Height of conveyor (ft)
Total horizontal (ft)
Capacity (tph)
Capacity (ft^3/hr)
Gravity (ft/min^2)
30
10
3
2440
38
26
13
1.5
8
12
8.660254038
8
73.2
4623.157895
115920
Conversion
0.523598776
0.666666667
Chart 2 **Data obtained from the values in Chart 1
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Summary of Collected Data from CEMA: Belt Conveyors for Bulk Materials:
Table Values
Angle of repose (degrees)
Angle of surcharge (degrees)
D.F (Capacity design factor)
Recommended Belt Speed (fpm)
Belt width-Using Q100 (inches)
Skirt board width (in)
Idler class
Idler Spacing @ BW= 24in (ft)
Average Belt weight (lbf/ft)
Skirt board Friction Factor (Cs)
Pulley face width (in)
Distance between Discharge Chute (in)
Return belt Clearance (in)
Minimum Carry Thickness (in)
Minimum Pulley Cover thickness (in)
Belt Grade
Cross sectional Area (ft^2) @surch 30
Capacity at 100fpm @ surch 30 (ft^3/hr)
Edge Distance (in)
Idler Load Rating
Idler Selection
Idler Diameter of Class C4 (in)
Idler weight (lbf)
Chart 3
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40
30
1.2
600
24
16
B4-D6
5
4.5
0.009
26
29
0.5
0.0625
0.03125
RMA Grade
2
0.241
1444
2.22
475
CEMA C
4
15.2
Table
Number
Table 4.7
Table 4.7
Page 55
Table 4.2
Table 4.7
Table 4.10
Table 5.1
Table 5.19
Table 5.22
Table 6.40
Table 7.32
Table 7.32
Table 7.32
Table 7.5
Table 7.6
Table 7.4
Table 4.7
Table 4.7
Table 4.3
Table 5.35
Table 5.35
Table 5.1
Table 5.42
Conversion
Units
0.698131701 radians
0.523598776 radians
2 ft
1.333333333 ft
Calculated values
Capacity at 100fpm
Belt load cross sectional area (ft^2)
Material Weight (lbf/ft)
Effective Tension (lbf)
Initial Material Velocity
Frequency Factor
Transfer (belt speed) fpm
Pulley rpm
power (lbf*rpm)
Total Load (vertical comp)(lbf)
Tension Based on Load (lbf)
Pulley Torque (lbf*ft)
Horizontal Load (lbf)
Note:
770.5263158 Q100
0.107017544 A
4.066666667
42.01303309
589.711794 Vo
0.043333333 Minutes to make one round
600
147.13
4201.378889
7.638870707 Hp
74.18950959 concentrated load (incline)
42.83333333
28.55555556 Tension*drum radius
25.7 concentrated load (horizontal)
Chart 4 **Values obtained using the values in Chart 3
Maintenance dimensions
pulley replacement (in)
idler replacement primary side (in)
idler replacement secondary side (in)
clearance under conveyor (in)
Skirt Board replacement height (in)
Skirt Board Adjustment (in)
Belt repair area (in)
Chart 5: Frame design
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Table 2.25-31
36
54
12
24
9
6
72
References
BACtalk Product Line. N.p., n.d. Web. 01 Dec. 2013.
Baldor Electric Company, a Leader in Energy Efficient Electric Motors, linear Motors and
Adjustable Speed Drives Industry. N.p., n.d. Web. 1 Dec. 2013.
<http://www.baldor.com/default.asp>.
Baldor. "Product Overview: EM7142T-C." Baldor Electric Company, a Leader in Energy Efficient
Electric Motors,linear Motors and Adjustable Speed Drives Industry. N.p., n.d. Web. 04 Mar. 2014.
*Belt Conveyors for Bulk Materials. 6th ed. Naples, FL: CEMA, 2007. Print.*
Marek, James. "Choosing Between Electromechanical and Fluid Power Linear." Thomson
Industries, Inc. N.p., n.d. Web.
<http://www.thomsonlinear.com/downloads/articles/Choosing_Between_Electromechanical_and_Fluid_
Power_taen.pdf>.
"Welcome to Boston Gear." Welcome to Boston Gear. N.p., n.d. Web. 27 Nov. 2013.
<http://bostongear.com/products/open/worms.html>.
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