Pneumatic conveying "Dense Phase"

The Dense Phase pneumatic conveying system is used for conveying of dry bulk materials as powders and granules by using a high positive pressure and a slow velocity.

This way of conveying is mainly used for abrasive, fragile, and/or explosive products.

Product transfer takes place in successive batches and plugs.

Each conveying cycle includes the following stages:

• Filling stage during which the filling valve is open as well as the vent valve. The product fills the vessel (tank) and displaces the air which is inside the tank.
• The high level control device issues a closing signal to the feed valve and the vent valve.
• The outlet pinch valve (if fitted) remains closed.
• The compressed air inlet valve opens and the compressed air enters in the vessel.
• The product mixes with the air and starts to fluidize.
• When the pressure in the vessel reaches the level required for conveying, the outlet valve opens and the product is pushed forward into the conveying pipeline. The product moves in successive plugs until the vessel and the pipeline are empty.
• A single pressure switch controls the pressure in the vessel and as soon as the pre-set limit of the cycle end has been reached, it stops the air compressed supply. The residual air allows purging the circuit until the pressure differential has been dispersed.

A principal advantages of this method are :

• Particularly suitable for ATEX installations,
• It preserves the original appearance of the product,
• Low power consomption