A. Dilute Phase pressure conveying systems:
Dilute phase pneumatic conveying system 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.
B. Dense Phase Pressure Conveying Systems :
Dense phase pneumatic conveying is a widely known as plug flow systems which is non-suspension flow. The product is filled in a pressure vessel, which is then pressurized with the air or gas to be used for conveying. Once a pre-set pressure is reached inside the vessel, the bottom discharge valve opens and the material is conveyed to the destination. The material to air ratios is higher in dense phase conveying in the range of 20 to 100 kg / kg. of air Dense phase conveying uses compressed air and requires an air compressor. Dense phase conveying is used for high capacity and long distance conveying. Dense phase conveying employs the pressure vessel with valves and instrumentation which is controlled through PLC based control panel.