Pneumatic Conveying
Pneumatic conveying is one of the most popular methods for moving solids in the chemical and processing industries. The process of pneumatic conveying involves the moving of solids suspended in or forced by a gas stream through horizontal and/or vertical pipes. Pneumatic conveying can be used for particles ranging from fine powders to pellets and large bulk densities. Pneumatic conveying systems are capable of handling a wide range of dry bulk materials from silica sand to sugar.
The four most common types of pneumatic conveying systems are dilute phase vacuum operation, dilute phase pressure operation, dilute phase pressure-vacuum operation, and dense phase pressure operation. Vacuum systems allow multiple product inlets through the use of simple diverter valves. Vacuum systems are more sensitive to changes in distance than pressure systems due to their maximum pressure differential; dilute phase pressure systems can easily achieve higher pressure differentials. Pressure-vacuum operation, which utilizes both methods, is useful for some conveying setups, like the unloading of a standard railcar. Since the cars cannot be pressurized, air is pulled from the outside, through the car to a filter, and the solids are forwarded to the destination by a blower. The choice between dilute and dense phase operation typically depends on the solids' properties. The lower velocity bulk phase operation, for example, is popular for highly abrasive products or for those prone to degradation.