BUCKET ELEVATOR
Design Description
A bucket elevator, also called a grain leg, is a mechanism for hauling bulk
materials vertically. It consists of buckets to contain the material, a belt to carry the
buckets and transmit the pull, and a means to drive the belt. A bucket elevator can
elevate a variety of bulk materials from light to heavy and from fine to large lumps.
Design Selection
Bucket elevators are one of the most popular systems in use today for
elevating bulk materials. Their inherent simplicity makes them a popular choice for
handling bulk materials and in processing applications. Advantages of using bucket
elevator include large conveying capacity, high hoisting height, smooth
transportation of goods, less maintenance, stable and reliable running, long service
life, low driving power, and wide range of lifting.
Data and Assumptions
1. Feed bulk density is 253 kg/m3
2. Assumed height: 5.9 (from tank height) + 1 (from ground to tank bottom) +
0.5 (bucket clearance) = 7.4 or 7.5 m height
Design Considerations
1. 2/3 of the bucket is to be occupied by the raw materials
2. A scale of 150 tons/hr, 50 lbm/ft3 and is directly proportional.
Design Requirements
1. Capacity
2. Load Weight
3. Belt speed
4. Pulley diameter
5. Power requirement
Design Calculations
1. Capacity
253k kg gmm3
×2.2 lbslbs1kg kg
×( 1mm3.2808 ft ft )
3
=15.7617lbm lbmft ft3
Using correlation from Unit Operations by Brown:
75.5tons tonshr r
=50lbm lbmft ft3
75.5tons tons /hr50 lbm lbm/ ft ft3
= capacity capacity
15.7617 lbm lbm / ft ft3
capacity=23.8002tons tons /hr r
From Table 21-8 Bucket Elevator Specifications (Perry’s Chemical Engineers’
Handbook), the calculated capacity is 27 tons/hr.
For 27 tons/hr,
Capacity=(27 tonstons /hr r )(2000 lbm/ ton lbmton
)( 1kg kg2.205 lbm
lbm)= 24,489.79592
kg/hr
Also from table 21-8, with capacity of 27 tons/hr, bucket dimension is 203 x 127 x
140 and a spacing of 356 all in mm
2. Load Weight
2/3 (bucket volume) (density) ¿ 23
(203 x127 x 140 )mmmm3 ¿
= 0.6088 kg/bucket
For bucket per seconds:
Load weight x capacity = bucket/sec
Load24,489.79592kgkghr
(1bucket bucket /0.6088 kgkg )=40,226.34021 bucket bucketh r r
=11.17
bucketsec
bucket
h r≈12buckets/ sec
3. Belt speed
For speeds:
no .of buckets x spacingbuckets x spacing=12bucketsbuckets /sec(356
mmbucket
mm
bucket)(
1mm1000mmmm
¿)=4.272m /s ¿
4. Pulley diameter
D D=2v2
g=2x 4.272
2
9.81=3.7207m
5. Power requirement
Height x Buckets/hr x factor of 0.0000379 (in SI units)
( 7.5mmbucket bucket )x x24 ,489.79592 kg kghrr
x 0.0000379=6.96 ≈7 hp
SPECIFICATIONS
BUCKET ELEVATOR
Identification
Item: Bucket elevator
Number of required Units: 1
Materials handled: Rice Bran
Materials of Construction: Style AARB buckets available in malleable iron
Design Data
PARAMETERS Proposed Design Existing Design
Capacity
Height/ elevation
Bucket speed
Size of bucket
Bucket spacing
Power requirement
2 7 tons/hr.
7.5 m
4.272 m/s
203 x 127 x 140
356 mm
7 hp
614 ft3/hr
7.5 m
5 m/s
203 x 127 x 140
400 mm
7 hp
Source: http://www.screwconveyor.com/SCC_Catalog_201
DESIGN CONFIGURATIONS
Recommended
