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COPYRIGHT KURT ROSENTRATER IOWA STATE UNIVERSITY DISTILLERS GRAINS TECHNOLOGY COUNCIL ASSOCIATE PROFESSOR FACILITY DESIGN MAXIMIZING EFFICIENCY AND THROUGHPUT
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KURT ROSENTRATERIOWA STATE UNIVERSITY
DISTILLERS GRAINS
TECHNOLOGY COUNCIL
ASSOCIATE PROFESSOR
FACILITY DESIGN
MAXIMIZING EFFICIENCY AND THROUGHPUT
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TODAY’S TOPICS
• Facility goals
• Overview of facilities
• Historical perspectives
• Efficiencies in design, construction, & operations
• Recap from 2018
• Receiving
• Loadout
• Conveyors
• Final thoughts
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FACILITY GOALS
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FACILITY GOALS• Existing facilities upgraded/expanded each year• New facilities constructed each year• Continual need to service grain, feed, food, biofuels
industries
• Design data, information & procedures are critical• Substantial focus on farm-scale
• Commercial-scale scientific knowledge needs more• Anecdotal
• Proprietary
• Official standards
• Cost reductions
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FACILITY GOALS
• Overarching goals for grain storage facilities
• Protect grain
• Weather, insects, rodents, birds, mold
• Maintain quality after harvest
• Storage cannot improve upon quality
• But: poor storage can result in reduction in quality (deterioration)
• Repository for local grain supplies
• Storage for processing operations
• Shipping point to end-use destinations via
• Trucks, rail cars, ships
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OVERVIEW OF FACILITIES
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OVERVIEW OF FACILITIES
• Modern facilities have much greater
• Storage capacities
• Equipment capacities
• Yearly throughputs
• Dust control systems
• Safety measures
• Automations & controls
• Efficiencies
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OVERVIEW OF FACILITIES
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OVERVIEW OF FACILITIES
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OVERVIEW OF FACILITIES
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OVERVIEW OF FACILITIES
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OVERVIEW OF FACILITIES
• Regardless of type, arrangement, or size
• Proper selection, sizing, and location are essential to successful grain storage
• All components must work together
• Only as strong as the weakest link
• Only as fast as your slowest operation
• Want an efficient, cost-effective operation
• Commercial facilities
• Typically handle more than 20,000 bu/hr
• Can store from several thousand, up to several million, bushels at one time
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FACILITY OVERVIEW
• Many common components and systems
• Primary components
• Receiving
• Distribution
• Storage
• Reclaim
• Loadout
• All facilities utilize these components
• Many of these can drive design choices
Receiving
Distribution
Storage
Reclaim
Loadout
Incoming Grain
Outgoing Grain
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FACILITY OVERVIEW
• Many common components and systems
• Secondary components
• Cleaning
• Aeration
• Drying
• Dust control
• Sampling
• Instrumentation and controls
• Not all facilities utilize these components to the same degree
• Don’t drive the design choices
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FACILITY OVERVIEW
Receiving
Distribution
Storage
Reclaim
Loadout
Incoming Grain
Outgoing Grain
Large Grains Elevator
Reclaim
Receiving
Loadout
Storage
Distribution
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FACILITY OVERVIEW
Receiving
Loadout
Storage
Reclaim
Distribution
Small Grains Elevator
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FACILITY OVERVIEW
• Many types, arrangements, and sizes are available for commercial operations
• Choices depend on
• Individual client needs and requirements / opinions
• Operational flexibility
• Future expansion
• Creativity and imagination
• Cost
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HISTORICAL PERSPECTIVES
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HISTORICAL PERSPECTIVES
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HISTORICAL PERSPECTIVES
• The Young Mill-Wright and Miller’s Guide
• Oliver Evans, 1795
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EFFICIENCIES IN DESIGN, CONSTRUCTION & OPERATIONS
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RECAP FROM 2018
• Receiving systems
• Distribution systems
• Storage systems
• Reclaim systems
• Loadout systems
Specifically timing
studies & throughput
This year:- More specifics about design
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RECEIVING SYSTEMS• Purpose
• Introduce incoming grain into the storage facility• Transfer grain to distribution system
• Grain typically delivered with wagons or trucks (rail cars)
• Design considerations• Maximize throughput; minimize wait (esp. harvest)
• Hopper volume: up to 1200 bu or more
• Capacity: ~ 20,000 bu/hr• Orifices, gates, spouts, conveyors
• Valley angle: > angle of repose • Limiting factor, not side slopes
• Want to minimize height of hoppers• Minimize costs ….bucket elevator height & boot pit depth
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RECEIVING SYSTEMS
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RECEIVING SYSTEMS
q
b
a
a
b
c
tan b = h/b
cot b = b/h
b = h*cot b
tan a = h/a
cot a = a/h
a = h*cot a
tan q = h/c
cot q = c/h
c = h*cot q
a2 + b2 = c2
(h/tan a)2 + (h/tan b)2 = (h/tan q)2
h
(tan q)2 = (tan a)2 * (tan b)2
(tan a)2 + (tan b)2
q = tan-1 (tan a)2 * (tan b)2
(tan a)2 + (tan b)2
1/2
* Note: h does not matter
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RECEIVING SYSTEMS
• Valley angles:
• http://bulksolidsflow.com.a
u/free_programs/valley_an
gles/valley_angles.html50
40
5040
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RECEIVING SYSTEMS
• Valley angles:
• http://bulksolidsflow.com.a
u/free_programs/valley_an
gles/valley_angles.html50
40
2070
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RECEIVING SYSTEMS
• Capacities:
V = L * w * h V = h/3 * (B1 + B2 + (B1 * B2)1/2)
http://www.mathinary.com/pyramid__frustum_the_volume_of_a_frustum_of_a_pyramid.jsp
L
w
h
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RECEIVING SYSTEMS• 2 most common types = gravity vs. mechanical
• Tradeoffs
• Gravity hopper only
• Deeper pit, or
• Higher receiving floor (ramp/earth work), and
• Taller bucket elevator
• Hopper + conveyor
• Shallower pit
• Potential carryover/cleanout issues
• Maintenance
• Potential grain damage
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RECEIVING SYSTEMSGravity Mechanical
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RECEIVING SYSTEMS
Mechanical: Above ground vs. underground
Gravity
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RECEIVING SYSTEMS
Tower:
12” x 0.23” x 6.5” = $50/ft
4 columns x 1ft x $50/ft = $200 / 1 ft height
Boot Pit:
10 ft x 10 ft x 1 ft thick
= 44 ft3 / 1 ft depth
Concrete = $3.7 / ft3
$163 / 1 ft depth
10 ft x 10 ft x 0.5 ft thick
= 21 ft3 / 1 ft depth
Concrete = $3.7 / ft3
$78 / 1 ft depth
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LOADOUT SYSTEMS• Purpose
• Transfer grain to shipping containers
• Typically rail cars (sometimes trucks)
• Design considerations
• Equipment sized for speed and labor efficiency
• Typically ≥ reclaim rate (≥ 50,000 bu/hr)
• 110-car unit trains in < 15 hr
• Typical equipment used
• Overhead surge bins within support structures vs. mechanical fill
• Can be system bottleneck
• Bulk weigh scales
• Spouting
• 3 common options
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LOADOUT SYSTEMS• 3 common types
Mechanical Overhead surge Mechanical
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LOADOUT SYSTEMS
Gravity Mechanical
Mechanical
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LOADOUT SYSTEMS
• Example: 80,000 bph
• Upper garner = 1400 ft3 (143%)
• 1125 bu
• Scale hopper = 980 ft3
• 788 bu
• Lower garner = 1200 ft3 (122%)
• 964 bu
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LOADOUT SYSTEMS
• Mechanical loadout
• 60,000 bph
• Use shipping bin as upper garner
• 14,000 bu / 60,000 bph = 14 min
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LOADOUT SYSTEMS• Use upper annex bin as upper garner
• 172,000 bu / 60,000 bph = 2.9 hr
• Still have to mechanically lift
• 60,000 bph x 12.5 hr = 726,000 bu
• Bucket elevator size = ?
• 20,000 bph x 12.5 hr = 250,000 bu
• 40,000 bph x 12.5 hr = 500,000 bu
• 50,000 bph x 12.5 hr = 625,000 bu
• 55,000 bph x 12.5 hr = 687,000 bu
• 60,000 bph x 12.5 hr = 750,000 bu
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LOADOUT SYSTEMS
• Use upper annex bin as upper garner
• 320,000 bu / 60,000 bph = 5.3 hr
• Still have to mechanically lift
• 9.7 hr x 60,000 bph = 580,000 bu
• Bucket elevator size = ?
• 40,000 bph x 9.7 hr = 388,000 bu
• 50,000 bph x 9.7 hr = 485,000 bu
• 60,000 bph x 9.7 hr = 582,000 bu
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CONVEYORS
• Bucket elevators
• Drag conveyors
• Belt conveyors
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Bucket Elevator Calculations
• For engineers, 2 key calculations include:
• Capacity – determines how much grain you can move/transport
• Power required – determines how big a motor you need
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Bucket Elevator Calculations• Capacity
• Q is the volumetric capacity of the bucket elevator (bu/h),
• Cc is the capacity of each cup (in3/cup),
• Cf is the fill of each cup (%, expressed as a decimal),
• Cs is the linear spacing of cups per unit length of belt (number of cups/ft),
• Cr is the number of cup rows across the width of the belt,
• V is the linear belt speed (ft/min),
• C1 is a conversion factor of 60 (min/h),
• C2 is a conversion factor of 2150.42 (in3/bu)
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2
1rsfc
C
CVCCCCQ
=
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Bucket Elevator Calculations• Power
• P is the power required to drive the elevator shaft (hp),
• Q is the volumetric capacity of the elevator (bu/h),
• Tw is the grain test weight (lb/bu),
• H is the total vertical distance between the head and tail shafts of the elevator (ft),
• Sf is an empirical service factor of 1.1(-),
• C1 is a conversion factor of 33,000 (ft.lb/min/hp),
• C2 is a conversion factor of 60 (min/h),
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.75 to 0.95)
• An additional 10% is added to empirically account for friction losses within the elevator
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121
fw
RCC
SHTQP
=Potential energy
(mgh / time)
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Bucket Elevator Calculations• Power
• P is the power required to drive the elevator shaft (hp),
• Q is the volumetric capacity of the elevator (ft3/h),
• BD is the bulk density of the grain (lb/ft3),
• H is the total vertical distance between the head and tail shafts of the elevator (ft),
• C1 is a conversion factor of 33,000 (ft.lb/min/hp),
• C2 is a conversion factor of 60 (min/h),
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.75 to 0.95)
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121 R
1
2490
Q
CC
HBDQ1.1P
+
=
Potential energy Friction
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Bucket Elevator Calculations
• Power
• P is the power required to drive the elevator shaft (hp),
• Q is the volumetric capacity of the elevator (bu/h),
• H is the total vertical distance between the head and tail shafts of the
elevator (ft),
• Da is an additional distance of 5 ft, which empirically accounts for frictional
losses within the elevator
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( ) 000036.0DHQP a += (simplified)
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Drag Conveyor Calculations
• Capacity:
• Q is the volumetric throughput (bu/min) of the conveyor,
• V is the linear chain speed (ft/min),
• h is the height of the grain mass at a given cross section inside the
conveyor (ft),
• is a function of the height of the flighting/paddles used,
• w is the width of the conveyor (ft),
• C1 is a conversion factor of 0.8036 (bu/ft3)
1CwhVQ =
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Drag Conveyor Calculations• Power required: [book’s approach] – theoretical
• P is the power required to drive the conveyor (hp),
• L is the conveyor length, from head shaft to tail shaft (ft),
• Wc is the weight of the chain and flighting per unit length of conveyor (lb/ft),
• Fc is the coefficient of kinetic friction between the chain and flights and the conveyor floor (-),
• q is the slope of the conveyor relative to a horizontal plane (o),
• Wm is the weight of the grain per unit length of conveyor (lb/ft),
• Fm is the coefficient of kinetic friction between the grain and the conveyor floor (-),
• h is the average depth of the grain in the conveyor (ft),
• V is the linear chain speed (ft/min),
• C1 is a conversion factor of 33,000 (ft.lb/min/hp),
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.85 to 0.95)
( ) ( ) ( )( ) V
RC
h044.0sincosFWsincosFWsincosFWL1.1P
11
2
ccmmcc
+q−q+q+q+q+q=
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Drag Conveyor Calculations• Power required: [industry approach]
• (for horizontal use with soybeans, this equation has been empirically adapted to a simpler form)
• P is the power required to drive the conveyor (hp),
• Q is the volumetric capacity of the conveyor (bu/h),
• L is the length of the conveyor (ft)
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.85 to 0.95)
1*56000 R
LQP
=
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Drag Conveyor Calculations• Power required: [industry approach]
• (for horizontal use with corn or small grains, this equation has been empirically adapted to a simpler form)
• P is the power required to drive the conveyor (hp),
• Q is the volumetric capacity of the conveyor (bu/h),
• L is the length of the conveyor (ft)
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.85 to 0.95)
1*75000 R
LQP
=
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Drag Conveyor Calculations• Power required: [industry approach]
• If the conveyor is at an incline, then previous empirical equations must be modified to account for the change in potential energy in the system.
• This is accomplished by increasing them by adding an additional power requirement
• Pa is the additional power required due to the conveyor’s incline (hp),
• Q is the volumetric capacity of the conveyor (bu/h),
• H is the change in elevation from the conveyor’s tail shaft to head shaft (ft)
30000
HQPa
=
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Belt Conveyor Calculations
• Capacity (bu/h or bu/min):
• How would you calculate this?
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Angle of Surcharge
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Belt Conveyor Calculations
• Capacity:
• Q is the volumetric throughput (bu/min) of the conveyor,
• V is the linear belt speed (ft/min),
• A is the cross-sectional area of grain on the belt (which will assume the shape of a combination of trapezoidal area with a circular segment area on top [ft2]),
• Circular area depends on surcharge/slump (grain & moisture)
• C1 is a conversion factor of 0.8036 (bu/ft3)
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1CAVQ =
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Belt Conveyors
CEMA
https://www.cemanet.org
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Belt Conveyor Calculations• Power required:
• P is the power required to drive the conveyor head shaft (hp), THIS IS THE MOTOR SIZE
• L is the conveyor length, defined from head pulley shaft to tail pulley shaft (ft),
• Kt is the temperature correction factor, which is related to belt thermal expansion and flexibility (-),
• Kx is the frictional resistance factor that accounts for the interaction between the belt and the idlers (lb/ft),
• Ky is the factor that accounts for the resistance of the grain load to flexure as it passes over the idlers (-),
• Wm is weight of the grain per unit length of belt (lb/ft),
• Wb is the weight of the belt per unit length (lb/ft),
• H is the change in vertical height from the tail shaft to the head shaft (ft),
• Tp is the tension force resulting from the belt’s resistance to bending around the head and tail pulleys (lb),
• Tam is the tension force resulting from the force necessary to accelerate grain as it is fed onto the belt (lb),
• Tac is the tension force resulting from conveyor accessories such as plows, trippers, and belt cleaning devices (lb),
• V is the linear belt speed (ft/min),
• C1 is a conversion factor of 33,000 (ft.lb/min/hp),
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.75 to 0.95)
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( ) ( ) V
RC
TTTHKLWW015.0WKKKLP
11
acampymbbyxt
++++++=
Te = effective tension, lb
P = (Te x V) / (C1 x R1)
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Belt Conveyor Calculations
• Power required:
• P is the power required to drive the conveyor (hp), MOTOR SIZE
• L is the conveyor length, defined from head pulley shaft to tail pulley shaft (ft),
• Wm is weight of the grain per unit length of belt (lb/ft),
• Wb is the weight of the belt per unit length (lb/ft),
• H is the change in vertical height from the tail shaft to the head shaft (ft),
• V is the linear belt speed (ft/min),
• C1 is a conversion factor of 33,000 (ft.lb/min/hp),
• R1 is the efficiency of the motor speed reducer (which typically ranges from 0.75 to 0.95)
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( ) ( ) V
RC
225HL035.0W58.0W05.0W00068.0LP
11
mbm
++++=
(simplified)
Te = effective tension, lb
P = (Te x V) / (C1 x R1)
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FINAL THOUGHTS
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FINAL THOUGHTS
• Make sure everyone reads the blueprints CORRECTLY
• Contractors
• Subcontractors
• Equipment vendors
• Field staff
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FINAL THOUGHTS
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FINAL THOUGHTS
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FINAL THOUGHTS
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FACILITY DESIGN
• Dynamic process
• 5 main stages
Flow Diagram
Bin Layout/Arrangement Bin Sizes/Capacities
Facility Layout
Process Design
Primary Systems
Secondary Systems
Client Req. Building Codes Standards
Structural Design
Final Design
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FINAL THOUGHTS
• Brief overview of design & operation considerations
• Each commercial facility is unique
• Many styles, layouts, and options
• Many common features and equipment
• Ultimately, design and operation based on client’s preferences
• Detailed knowledge of design processes is extremely important
• Hopefully these thoughts will be useful
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THANK YOU!
Questions?
