ByN.Saravanan, Grinding Technology Department,FLSmidth Pvt Ltd.,Chennai.

Purpose of bucket elevators

* Bucket elevators are used to lift bulk material from one height to another. They are a reliable and well-proven piece of equipment.

* Bucket elevators are an ideal solution for vertical transportation of bulk materials.

* Bucket elevators operate by using an endless belt or chain on which rectangular buckets are mounted. This belt or chain revolves between a top and bottom pulley and the buckets move with it.

* At the bottom, the buckets pick up product fed into the elevator boot and at the top the product is discharged as the bucket turns downward over head pulley.

* Along with each type of elevator, different styles of buckets have been developed which better suit the elevator or the materials to be handled.

Types of bucket elevators

Centrifugal discharge elevator (CE) : This is the most commonly used type with bucket mounted on belt or chain for

handling of free flowing or small particle. Continuous discharge elevators (CO) :

This type pf elevators are used for handling large lumps and material that cannot be handled by centrifugal discharge. The slow speed and gentle method of loading & discharging is the main feature.

Positive discharge elevators (PO) :

This is similar to centrifugal type except the bucket are end mounted with two strands of chain. Bucket speed is slower and suitable for light, aerated, sticky materials.

BELT BUCKET ELEVATOR INTRODUCION

Bucket elevator belts and conveyor belts have different requirements.

For elevator service, you need to calculate the strength of the belt needed to support the weight of the bucket and the material being conveyed.

In addition, you need to calculate the strength needed to handle the available horsepower.  This is easy to accomplish. Since the weight of the buckets is essentially the same on both sides of the leg, the weight of the material is the difference.

Standard Elevator Bucket Punching

The type, size, weight, capacity, spacing, and projection of the buckets are critical factors in determining the correct belt for carrying the load and holding the buckets. The number, size and location of the bolts are also important.

Important advantages of belt bucket over chain bucket elevators * Lower wear and tear

* Quiet operation

* Higher specific conveying capacity

* Lower power consumption

* Most suitable for handling cement, raw meal, coal etc

TECHNICAL SPECIFICATION

Equipment : Belt Bucket elevator

Material to be handled : Raw meal

Bulk density : 0.8 to 0.9 T/M3

Material Temperature : Max. 120 0 C

Capacity (Design) : 350 T/hr

C/C Distance : 68.570 Mtrs

Belt : Steel Chord Belt 1050 mm width

Belt strength : 2000 kp/cm

Belt speed : 1.66 m/sec.

Bucket size : 900*335*5

TECHNICAL SPECIFICATION

Belt size : 1050 mm W * 141.50 M lg.

Breaking Load : 185.800 KP

Working load : 15.500 KP

Belt strength : 2000 KP/CM

Safety factor : 12

Bucket quantity : 306

Distance between two buckets : 460 mm

Head and Tail pulley Dia : 1250 mm

Installed motor : 110 KW

Casing size : 1310 W *2450 Box 780

TECHNICAL SPECIFICATION

BOLT SIZE Torque

M 20 * 1.5 64 Nm/Bolt

M 24 * 2 1000 Nm/Bolt

M 30 * 2 2200 Nm/Bolt

DRIVES

Auxiliary drive : Geared motor- Greaves make GM 095, 5.5 KW, 56

output RPM with spiral Jaw coupling

Make : MARK AEC

Safety Device : Belt sway switch 220 V, 400 mA

Electronic speed regulator

Painting : 2 coats of primer after Sand blasting and 1 coat of

final finish synthetic enamel paint by spray painting.

Material of construction

Buckets : 5 mm thick plate – IS:2062

Head Casing : 10 mm thick plate - IS:2062

Boot Casing : 16 mm thick plate - IS:2062

Intermediate Casing : 5 mm thick plate - IS:2062

SPARE PARTS LIST

S.No Item Qty per assly

01 Buckets 306 Nos

02 Head shaft Bearing 2 Nos

03 Boot shaft Bearing 2 Nos

04 Belt 1 Length

05 Clamping device 1 Set

06 Bucket fixing bolt 2142 Nos

07 Tension Device Assly/ Bearing Bush 2 Nos

CONSTRUCTION DETAILS

* Head casing* Lower head section* Head shaft assembly* Boot casing* Boot shaft assembly* special steel chord belt* Belt guide rollers* Buckets* Safety devices* Intermediate casing* Main drive ( Bevel Helical Gear box & Fluid coupling )* Auxiliary drive* Maintenance platforms* Flanged inlet opening* Flanged dust collecting point at head casing

Erection

The following

* Storage at site

* Safety

* Preparation at site

* Workmanship

* Foundation checking

* Guide frames erection

* Fastening the side frame to the platform

* Drive unit tied into elevator casing

* Mounting of elevator belt

* Mounting the buckets

Operational procedure

The following check points should be reviewed before initial operation.

* Head and boot shafts must be parallel to each other and pulleys in line

* Casing plumb to within given tolerances

* All bolts joining sections properly tightened

* Reducer filled with oil to proper level

* Correct motor rotation

* Tighten all bucket moving bolts

* All lateral supports in place and secured

* Bearing lubrication

* Guards should be provided

* Inspection door should be closed

* Check for interlocking controls & safety controls

Initial operation

Particular attention should be directed to the following

* Loud or unusual noise

* Excess vibration

* Bearing overheating

* Drive unit overheating

MAJOR COMPONENTS MAINTENANCE CHECK LIST

S.No Item Check point Frequency

01 DRIVE UNITS

Motor

Gear Box

Coupling

Geared motor

Level switch

Lubricants, Heat-up

Lubricants, Heat-up

Alignment & Tightness of bolts

Lubricants, Heat-up

Electrical function

As per Manufactures

Manuals

MAJOR COMPONENTS MAINTENANCE CHECK LIST

S.No Item Check point Frequency

02 Head casing

Baffle plate

Pillow Block in Head Shaft Assembly

Shaft assembly

Wear out Position/

Fit out condition

Grease in bearing

General cleaning & Check for worn out of parts & replace if

Required.

Check for worn out parts

Monthly

Every 3 months

Every 2 years

Every 2 months

MAJOR COMPONENTS MAINTENANCE CHECK LIST

S.No Item Check point Frequency

03

Take up Tension in screw rods

Every 3 months

04

Inspection hole at boot casing

Material accumulation during break down

Foreign material in feed.

Weekly once

MAJOR COMPONENTS MAINTENANCE CHECK LIST

S.No Item Check point Frequency

05 STUFFING BOX

Inspection of packing for wear & tear

Tightness of glands screws

Monthly

06 BELT & BUCKETS

Tightness of Bolts & Nuts on Buckets

Inspection of belt for damage

Inspection of bolts & tightness & completeness

Deformed and damaged buckets to be replaced

First 100 hours of operation

Every 3 months

MAJOR COMPONENTS MAINTENANCE CHECK LIST

S.No Item Check point Frequency

07 Clamping Device

Tightness of bolts with torque wrench After 50 hours of operation

After another 2 weeks

After another 6 weeks

After another 3 months

LUBRICATION CHART

S.No Lubrication point

Lubricant Specification or make of lubricant

Qty Frequency Method of application

01 Antifriction bearings in Plummer block

Grease Servogem 2 of Indian oil

20 Gms

800 hours/ as and when required

By Grease Gun/ By hand

02 Motor Grease Servogem 3 20 Gms

Every year 10000 running hours

Grease Gun

03 Gear box Lubricating oil

Servomesh SP 320 of Indian oil

100 Ltrs

6 Months By pouring through oil plug

04 Fluid coupling Lubricating oil

As per Manufacture’s Manuals05 Geared motor Lubricating oil

Troubleshooting

Please see the “ Troubleshooting.doc “ file for various troubleshooting methods.

This file is given along with Belt bucket elevators presentation

OPERATION OF BELT BUCKET ELEVATORS

HEAD PULLEY & BOOT CAGE

Head pulley Boot cage

BELT BUCKET ELEVATOR’S DRIVE

INCHING DEVICE

This is normally a low speed geared motor. It permits low speed drive for inching and turning of large size and high speed bucket elevators in case of maintenance, inspection and test run

Jaw clutch

BELT & BUCKETS

TENSIONING DEVICE

BELTS & BELT JOINING METHODS

Bucket on belt attachment

Various types of Buckets joints

BUCKET SIZE & PUNCH STYLE

BUCKET SIZE & PUNCH STYLE

BUCKET SIZE & PUNCH STYLE

BUCKET SIZE & PUNCH STYLE

Advantages of Fluidomat Fluid Couplings:

Wear-free power transmission because of absence of mechanical connection between the input and output elements.

No-load start-up of motor irrespective of machine load. Motor peak torque utilized for machine acceleration.

Motor selection to operating HP rather than starting loads. Saving on energy cost and capital cost.

Simple control of maximum or limiting torque by easy variation of oil filling.

Added protection for motor and driven machine by limiting torque to a predetermined safe value.

Automatic unloading of prime mover in case of any sustained overload, by blowing-off of fusible plug on coupling, thus draining out oil.

Advantages of Fluidomat Fluid Couplings:* Automatic synchronization and load sharing in case of multi-motor drives

* Effective dampening of shocks, load fluctuations and torsional vibrations. Helpful in improving the drive duty conditions in machines subjected to shock loads, frequent load changes, startups and reversals.

* Smooth and controlled acceleration of driven machines. Important for machines such as conveyors, wire drawing and textile machines.

* Step less speed variation in wide range obtained in scoop type fluid couplings.

* Continuous clutching and declutching of large drives obtained from SC type couplings.

* Economy on machine and drive designs.

* Energy saving