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PRESENTATION ON
STUDY ON conveyors
SUBMITTED BY :- Er. OM SURYAWANSHI
9302528033
Material handling Equipment
Material handling includes a number of operations that can be
executed either by hand (manual) or by mechanical means or
devices to convey material and to reduce the human drudgery.
1. Belt conveyor
2. Bucket elevator
3. Screw conveyor
4. Chain Conveyor
5. Pneumatic conveyor
Belt conveyors
A belt conveyor is an endless belt operating between two pulleys with its load supported on idlers. Generally, for grain conveying, belt speed of 2.5 to 2.8 m/s is recommended.
Capacity, m2/h = (area of cross section-m2)X(belt speed, m/min)X 6O
Belt conveyor idlers
1. The flat belt idlers are used for
granular materials having an angle of
repose of not less than 35°.
2. Troughing idlers with 20° trough is
used for conveying all kinds of bulk
materials.
3. Troughing idlers with 35° and 45°
trough angle is mainly used for
transportation of small particle light
weight materials like grain, cotton
seed etc
Idler Spacing
The space between the successive idlers should be
approximately equal to the width of belt. The spacing should not
exceed 1·2 metres.
Belt tension:-
The tension developed at the drive pulley in transmitting the
required power to move the loaded belt is known as effective
tension.
Effective tensoin, T =Power, KW/belt speed, m/s.
Bucket Elevator
The vertical lift of the elevator
may range between few metres to
more than 50 m. Capacities of
bucket elevators may vary
from 2 to 1000 t/hr
(1) spaced bucket elevators and
(2)continuous bucket elevators.
The spaced bucket elevators are further classified as,
(1) centrifugal discharge elevators,
(2) positive-discharge elevators,
(3) marine leg elevators and
(4) high-speed elevators.
The continuous bucket elevators are classified as
(1) super capacity bucket elevators and
(2) internal-discharge bucket elevators.
The product flow is discharged either by means of gravity or centrifugal force.
The spaced bucket centrifugal discharge type is most commonly used for elevating the grains.
1. low speed gravitational discharge 2. high speed centrifugal discharge
Elevator capacity, t/hr = capacity, m3x No. of bucket per m. of beltx belt speed, m/min.x 6O
Capacity, t/hr = Capacity, m3/hr x material density, kg/m3÷ 1000
The bucket elevator's capacity may be calculated by the following equation.
The bucket elevator's capacity mainly depends on
Bucket size
Conveying speed
Bucket design
Spacing
Way of loading and unloading
The characteristic of bulk material
The main parts of a bucket elevator are, (1) elevator head section, (2) elevator boot section, (3) elevator legs, (4) belts for bucket elevator and (5) buckets.
Elevator Belts The total stretch of the belt under maximum load should not exceed 1-2 % of the belt length
Buckets The top angle is generally taken as 80° while the bottom angle is between 20-30°.
Buckets
Elevator Belts
HP requirement
Hp = QHF/ 4562
where,
Q = capacity of bucket elevator, kg/min
H = lift of elevator, m
F = factor; 1.5 for elevators loaded on the up side and
1.2 for elevators loaded on the bottom side
The theoretical horsepower should be increased 10-15% to
provide for friction and power requirements for loading, power
transmission and drive losses.
Screw Conveyor
The screw conveyor consists of a tubular or U-shaped
trough in which a shaft with spiral screw revolves.
Screw conveyor details
The screw conveyor is generally used to move grains
horizontally. However, it can also be used at any angle up to 90°
from the horizontal, but the capacity correspondingly reduced as
per the inclination of conveyance.
The pitch of a standard screw which is the distance from the
centre of one thread to the centre of the next thread is equal to its
diameter.
Screw conveyor details
Capacity Q, m3/hr = 47.2 (D2 - d2) X P x n
where, D = screw diameter, m d = shaft diameter, m p = pitch, m n = rpm
Capacity of the screw conveyor can be given by the following equation :-
Horse power = QLWF/4560
where, Q = conveyor capacity, m3/hr L = conveyor length, m W = bulk material weight, kg/m3 F = material factor (for paddy 0.4)
Power requirement
Pneumatic Conveyor :-
The pneumatic conveyor moves
granular materials in a closed duct by
a high velocity air stream.
The pneumatic conveying system
needs a source of air blowing or
suction, means of feeding the
product into the conveyor,
For dispersion of bulk material, air
velocities in the range of 15-30 m/s is
necessary.
Chain Conveyor
A chain is a reliable machine component, which transmits
power by means of tensile forces, and is used primarily for
power transmission and conveyance systems.
Types of Chain conveyor
Cast iron chain
Cast steel chain
Forged chain
Steel chain
Plastic chain