Air Supported Belt Conveyor -  Training

Details courtesy of Aeroconveyor

TRAINING OF PERSONNEL DIRECTLY INVOLVED WITH OPERATING THE AEROCONVEYOR ON SITE.

DEFINITION:

The aeroconveyor is an air-supported belt conveyor for bulk material. The main difference between the aeroconveyor and the conventional conveyor is the film of air under the belt, which is substituted for the idlers and rollers that carry the belt for conventional conveyors.

With this small change many different advantages are highlighted with the aeroconveyor as opposed to the conventional conveyor and personnel and operators have to appreciate these innovative concepts in order to successfully run the aeroconveyors on their plants.

EXPLANATION - THE AEROCONVEYOR PRINCIPLE

The aeroconveyor is much like a conventional idler-supported conveyor and conveys bulk materials in much the same manner. A continuous belt is driven around a head and tail pulley using the normal drive arrangement of motor and gearbox, however, with one major difference. A rolled steel trough with a plenum or air chamber is used as the support of the belt and a film of air, introduced between the belt and trough section, replaces the normal idler supports.

DIAGRAM - TYPICAL AEROCONVEYOR AND COMPARISONS

Natural air, is supplied by means of a centrifugal low-pressure blower fan, (no compressed air), which is fed into the plenum chamber and discharges via holes positioned along the length of the trough. An air film is thus created, supporting the belt off the steel trough and providing a smooth ride for the product.

When the fan comes into operation and stable pressure conditions are reached, the drive motor will commence to operate. A pressure switch, installed and correctly set ensures that the drive motor does not operate prior to the correct air pressure having been achieved.

The metal trough and plenum section has a multi-functional purpose. It provides the air supply conduit along the length of the belt and also manufactured as a beam member, enables large spans between supports. When stationary and prior to the fan becoming operative, the aeroconveyor's fully laden belt is completely supported by the structural steel trough sections.

During the process of being conveyed, the material remains motionless relative to the belt. The material lies perfectly undisturbed on the belt eliminating the natural friction losses. Segregation does not occur with air-supported belt conveyors. The undisturbed situation also means that increased capacities are possible and there is an elimination of spillage and dusting.

One of the features of the air-supported belt conveyor is its quiet running.

The conveyor is manufactured in compact 12 metre sections and is easily transportable. Walkways if required are only necessary on one side of the conveyor since troughing idlers are eliminated on the carrying-side and the only maintenance is on the return idlers every 3,0 metres.

One of the most remarkable attributes of the air-supported belt conveyor is its ability for total enclosure. Owing to its shape, the Aeroconveyor can easily be enclosed to ensure that wind and elements effects on the belt are eliminated on both the carrying and return lengths of the belt. This aspect ensures that the product is protected from the elements and the elements or environment from the product, in the case of dusty, toxic or hazardous material being conveyed. A reduction in dust pollution or in some cases the elimination of hazardous gases into the atmosphere means that the aeroconveyor is completely environmentally friendly. 

SUITABILITY:

Aeroconveyors are suitable for conveying a uniquely wide range of materials - from soft powdery substances, chemicals and foodstuffs to the heavier materials such as kimberlite, ore, coal, rock and other minerals and ores.

SECURITY:

The ability to be easily and securely enclosed has made the aeroconveyor an obvious choice for any security of product industry. The plants can opt for this system as product can be transported for long distances without risk of theft. (There is total enclosure).

Aeroconveyors has provided plants with various width belt aeroconveyors running products at tonnage's and speeds conventional belt conveyors are unable to sustain over long periods without stoppages for maintenance and breakage's.

The unique aspect of the aeroconveyor is that the air providing the lubricant necessary to support the belt and product comes from the outside of the trough structure. Since no idlers or rollers are required on the carrying-side, personnel, unauthorised or otherwise are not required to access the enclosed conveyor for any reason whatsoever.

OPERATION:

Operation of the Aeroconveyor on the plant can be automatic, requiring only the maintenance to be carried out.

MAINTENANCE:

The aeroconveyor has proven to be a low maintenance system due to the nature of the design and requires no additional attention other than to general engineering practices and good housekeeping.

A visual inspection can be done almost on a daily or periodical basis just to see the movement of the belting, usually at the gravity take-up positions and listen for any foreign noises to warn of possible bearing failures.

• Tension: Screw take-up adjustments should be checked daily after commissioning until belt stretch has been achieved approximately 5 days, thereafter check periodically to ensure belt tension is sufficient to prevent slipping on drive pulley.
  

• Monthly:

1. Check oil levels in gearbox.

2. Inspect and adjust skirting.

3. Check belt cleaning device and ensure scrapers are operating on the belt.

4. Check inlets of fans for foreign materials.

• Yearly: Perform basic maintenance to

1. Gearbox.

2. Plummer block bearings.

3. Chute linings.

4. Belting for wear.

GENERAL

The aeroconveyor system has proved to be a very low maintenance cost system due to the nature of the aeroconveyor - there are, however, certain points to watch for to ensure continued trouble free operation.

Remember no system is safe against abuse or lack of attention. 

• Check for proper belt tension. It should be tight enough to prevent slippage between the belt and the drive pulley under full load.

• Check for damaged or frayed belts that could cause interference or jam-ups.

• Look for shredded belt droppings.

• Listen for excessive noises at bearings at motors or at blowers.

• Manually check all mechanical controls and see that they operate freely.

• Check for air leakage at joints along the length of the conveyor.

• Check for excessive spillage of material, this could indicate that a belt problem or belt cleaner problem.

• Check motors and gearboxes for oil leaks. 

• Check expansion points are hand tight only

Note: Personal working in the areas of the conveyors should report any and all obvious or suspected excessive wear or malfunction to the maintenance department. 

CAUTION: Equipment should never be repaired while a conveyor is running.

ONE MONTH/TWO MONTH FREQUENCY

Check drives with equipment shut down.

• Shut off, disconnect and remove guards.

• Check oil levels.

• Lubricate - see detail lub. instructions.

• Check belt tensions on vee drives and conveyors.

• Check set screws, pulleys and bearings.

• Check loose bolts and nuts due to possible cause of vibration.

• Check drive pulley for wear.

• Check trough roller idlers in transition sections and flat return idlers.
  a) for material build-up
  b) free rotation

• Check belt splice while stationary.

• Check expansion points are hand tight only.

Check conveyor while equipment is operating.

• Check belt tracking and tension.

• Check pulleys for foreign matter/material

• Listen for excessive noise

• Check belt splice - running

• Check for air leaks

• Ensure inlet for air blowers are functioning and clean

• Check safety devices

• Check air pressure readings

• Observe product flow while equipment is running

• Make sure guards are properly aligned

• Check chutes for blocking or flooding

• Check belt cleaning equipment operation

• Check covers are secured

With new installations a certain amount of "tuning" may be required before peak running operations are obtained and maintenance becomes one of the most important functions.

On an established plant, maintenance is already firmly in place. This document is to be used as a guide together with the policy of the company. 

ONE YEAR FREQUENCY

i. Structure 

• Check paint work and repair

• Check for signs of rust and repair

• Check in areas of high frequency vibration

ii. Perform basic Maintenance on drives, plus

• Change oil as per recommendations

• Grease all bearings

• Check for oil leaks

• Replace filters

iii. Clean and lubricate conveyor components.

• Clean trough sections and ensure air holes are open

• Check for wear in trough sections

• Replace roller trough idlers at head and tail sections 

• Check belt cleaning devices

• Check and clean return idlers

• Check for build-up of material in Plenum Chamber

iv. Electrics

• Check setting and operation of pressure switches

• Check setting and operation of current overload relay

v. Belt cleaning devices

These must only be fitted with the consent of the company, as they may effect the operation of the system.

Maintenance must be carried out on a very regular basis as per the manufactures requirements and brochures, as they do have a visible impact on the environment of the workplace and the product.

vi. Lubrication requirements

As per supplier's recommendation for: -

• Motors

• Gearboxes

• Fans

• Bearings

• Idlers

APPENDIX

With relation to not being able to visibly see if there is any deterioration or product under the conveyor belt or product blocking the small holes in the centre of the trough below the belt, and apart from the fact that most of the maintenance requirement is just visibly looking and listening, we would like to suggest, that a minimum monthly record of the amperage be kept of the motors for each blower fan and conveyor drive motor for all the aeroconveyors.

These figures should reflect when taken i.e. loaded or empty.

The reason for this data is that the engineer can see at a glance when the motors are drawing more amps. which would indicate greater loads being imposed, possibly due to holes being blocked and the belt only sliding or belting is catching or other belt or scraper problems, which can create greater loads.

The amp detail will assist personnel to be aware of possible approaching problems. 

A further assistance would be to install a inch nipple and a pressure gauge attached to the plenum chamber indicating the average range pressure between two points. The unit can also be connected through the drive motor. This method will also help in anticipating an approaching problem that may at some stage happen in the totally enclosed maintenance free aeroconveyor. However this system is very susceptible to abuse by personnel adjusting the ranges unnecessarily and for this reason is not totally recommended.