Dilute Phase Conveying:
Dilute phase is a suspension flows wherein the material to be conveyed is introduced into a moving air stream inside a pipeline. For the material to remain in suspension there is a minimum conveying velocity which varies for different materials. The quantity of material that is fed into an air stream is also dependent on material characteristics like bulk density, particle size, sieve analysis, frequency distribution etc. Generally, the material to air ratio varies between 3 to 10 kg of material to kg. of air. Conveying velocities are in the range of 18 to 28 m/sec depending on the product characteristics.
The dilute phase conveying system uses low-pressure air at pressures less than one bar in case of pressure conveying and (-) 5000 mm in case of vacuum convening, which is generated by positive displacement type roots blowers or by centrifugal blowers.
Dilute Phase Pressure Conveying System:
Pressure conveying systems are generally used where the feeding point is one and there are multiple discharge points. In this system the prime mover is located at the start of the conveying line and product is fed to the system through either rotary valve or ventury eductor or pressure vessel.