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UNDERSTANDING HOW AIR SLIDE CONVEYOR SYSTEMS WORK

 

Friday, July 30, 2021


When you are involved in the transfers of bulk powder and grains, understanding how airslide conveyor systems work will be of help as it is the 'best-fit' solution for many industrial circumstances.

Airslides provide some of the most efficient and practical methods of conveying bulk powder material. With some low pressure air, an aeration bed and a small incline (gravity), we can convey hundreds of tonnes of products over long distances.

Airslides are used extensively in many industries, including mining. They convey homogenous dry powder, including minerals, for use in cement, lime and fly ash. The food industry uses airslides for flour, and many powders in the chemical industry are ideally suited to airslides.

Airslides have no moving parts. They are, therefore, often a far better solution than screw conveyors, drag chains and belt conveyors.

Understanding how air slide conveyor systems work

Understanding how air slide conveyor systems work

Knowing the basic airslide conveyor system features

Some of the basic structural features of an air slide conveyor system include:

  • Section width and height of the aeration bed dictates the conveying rate
  • Turning boxes (pots) are used to divert flow from one direction to another.
  • Aeration cloth is generally woven permeable polyester
  • Inspection ports provide access to visually inspect inside the airslide section.

Several point of how air works with the airslide conveyor system include:

  • Fan or blower provides aeration air through the aeration cloth
  • Weir plates, used to adjust the aeration bed depth
  • Air control valves used to adjust the amount of aeration air being used
  • Dust collection vents remove the spent air expended from the product during conveying

Typical example of airslide conveyor system

A typical airslide installation in a cement depot will convey cement (bulk powder) some distance from a silo discharge. Ultimately, it discharges cement into a tanker via a loading chute.

Example of an airslide conveyor system

Example of an airslide conveyor system

Pneuvay airslides include perforated metal support sheet

Pneuvay airslides, unlike those from other suppliers, install a perforated metal support sheet under the aeration cloth. This provides stability and less movement of the fabric while conveying. This will extend the life of the cloth.

How does an airslide system work?

On a permanent equilibrium the angle of repose of bulk materials naturally achieves a constant slope from the horizontal plane. This is shown in the figure below.

Angle of repose of bulk powders

Angle of repose of bulk powders

To properly allow the transported material to flow, it was necessary to draw conveyor systems with a slope greater than the angle of repose of the material. These, however, have caused more complications, resulting in the invention of fluidised conveying systems. These are also known as airslide conveyor systems or air gravity conveyors.

How to make the airslide system work?

Airslide conveyor systems use a technique that maintains the aerated condition of the bulk material. This is illustrated and explained in this video below.

How fluidisation of powder works

This is implemented from the time it is introduced into the upper end of the channel to the point where it is unloaded.

How is this possible?

The airslide is a metal box divided into two parts:

  • Upper part, where the fluidised powder material is located
  • Lower part, where the air is at a pressure between 0.5 to 5.0 psa

A porous fabric membrane is located between the two parts of the housing.

Cross section of airslide conveyor system

Cross section of airslide conveyor system

The air thus passes through a false bottom or membrane made of a suitable porous material (polyester). This membrane extends over the entire length of the airslide, as shown below:

Material flow inside an airslide conveyor system

Material flow inside an airslide conveyor system

Operating principle behind the airslide system

The principle of operation behind an airslide system is driven by the fluidising air. After passage through the bed of material sliding over the membrane, the substance flows over the bed of material and is discharged through a suitable filtration unit.

Since the material is maintained by means of the regular air flow, it flows freely down the slope, even when the inclination angle is relatively small.

The amount of air used is kept to the minimum necessary to reduce the interparticle force and the frictional forces between particles and surfaces of the inner channels, sufficient to allow the flow of material.

How are the dimensions of an airslide system calculated?

An airslide conveyor system dimensions include:

  • Width
  • Angle of inclination
  • Length

These are straightforward to calculate.

Width

The width of an airslide system is calculated based on the capacity and the material density of the powder transported

Length

The length of the airslide system does not have any specific limitation.

Angle of inclination

The angle of inclination may vary depending on the type of material being conveyed. It is based on the principle that the more fluid the material is, the less the airslide needs to be inclined.

Airslide conveyor systems: the preferred choice of industry

The airslide conveyor system is the preferred choice for many industries because of its:

  • Reliable
  • Durability
  • Economical

This makes it an ideal choice for transporting bulk powders applications such as:

  • In-plant conveying that feed to storage or processes
  • Loadout from bulk silos to trucks, rail cars or barges
  • Storage silo and bin withdrawal
  • Distribution from bucket elevators to storage silos
  • Gathered under baghouses or precipitators

How to find the perfect airslide system for your company’s needs?

The design and installation of airslide conveyor systems can be complicated. Meticulous and exact calculations are required. For this you need a pneumatic conveying company with years of experience that can deliver the results you wanted.

Below are some of the airslide conveyor system projects we have completed through the years.

Queensland Alumina

A complete airslide AS500 package was required for the Queensland Alumina Ltd project. All components were manufactured in Melbourne. Read more this QAL airslide conveyor project.

Queensland Alumina airslide conveyor system project

Queensland Alumina airslide conveyor system project

Blue Circle Southern Cement

Pneuvay supplied Blue Circle Southern Cement (BCSC) a complete set of AS400 and AS300 airslides for their Waurn Ponds Cement Mill. This provided the company with more efficient power consumption. Read more about the BCSC airslide conveyor project.

Blue Circle Southern Cement airslide conveyor system project

Blue Circle Southern Cement airslide conveyor system project

Looking to get an airslide conveyor system?

Do you need help conveying bulk materials like cement, asphalt and grains with airslide conveyor systems? We design, manufacture and install airslide conveyor systems to fit any situation. Talk to us and send us a message today.


 
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