Miller Magazine Issue 107 / November 2018

51 MILLER / NOVEMBER 2018 COVER STORY Pneumatic conveyors are generally used for transferring substances in granular/powder structure by means of the air stream moving in a transmission line or transferring unit loads in private carriers. The common working principle of pneu- matic conveyor machines is transferring the kinetic energy of the air stream. Since air is a clean energy source and the sys- tem works in a completely enclosed environment, material losses and environmental pollution are minimized, and trans- fer operation is generally performed with zero loss. When a facility’s requirements demand high process rates for flour/ grain (i.e. in the tens of thousands of pounds per hour), the method of choice is typically Dilute Phase Pnuematic Con- veying. In this instance, outdoor storage silos transferring to indoor batching points are quite common. The bulk materi- al is generally delivered via PD Pnuematic Truck or Railcar. Whether Truck or Railcar, the hoppers are pressurized to a certain PSI and then the material is systematically released into the transfer system by the operator. More sophisticated systems can offer unloading and trans- fer without requiring an operator to be constantly managing the process, but generally speaking operator controls the unload sequence. Just like the larger Silo applications, the material is metered into the transfer tubing via a rotary air- lock which allows the material to enter the conveying stream without the loss of the conveying pressure and air. Technology and continuous improvements have altered the equipment for delivery of wheat/grain/flour. In milling industry, sys- tems used in the removal of wheat -as a raw material- and flour -as a final product- from one point to another within the fac- tory are generally divided into two groups as mechanical and pneumatical handling systems. While mechanical systems are especially preferred for removal of heavy and high-volume products, pneumatical systems stand out in the handling of lighter products with small particle sizes. Experts state that both systems have advantages and disadvantages and it is not possible to prefer one against the other. PNEUMATIC & AIR CONVEYING SYSTEMS IN PLANTS