APS Rotary and Spray Dryer Analysis, Instrumentation and Controls

  • Dryer Shower Pattern:

    • Our computerized model simulates an operation for a given set of data.
    • To our knowledge, no other simulator exists for showering action.
    • The shower pattern affects both the amount of dust blown out to the dust collection system, and the amount of drying accomplished. For a given Dryer diameter and feed rate, the shape, size, and number of lifters determines both the shower pattern and the fillage pattern of both the lifters and any excess bed’s kiln action. APS’s no-nonsense model of the actual motion takes into account the
      • gas flow rate through the dryer, its diameter and slope.
      • number, size, and shape of lifters.
      • the feed’s coefficient of friction, its density and its shape factor.
      • the inertia of the material as it leaves the lifters’ lips (RPM).
      • frictional resistance of the gas on the particles which determines where the lifters’ discharge will strike the bed or other lifters, and its time of fall.
      • The simulator prints a report on %fillage, bed action due to high fillage, dust loss, and a picture of the shower pattern.
      • The effect of modifying lifter number, shape or size is determined numerically, by changing the data into this C++ program. No other such simulator is known to us. It contains "stop-action" visualization.

    Heat Transfer Model For Dryers:

    • It has been used to size new dryers and to improve the fuel consumption and production rate of both Dryers and Rotary kilns that contain lifters. A printed Numerical report gives a detailed Heat Balance, Mass Balance and other Operational Information such as fillage, fuel consumption, exit gas flows and exit gas Temperatures (including saturation temperatures). Some of this information is used in "A."

    Dryer Instrumentation and Controls:

    • These have been considered mathematically, for correlation with empirical data. Bone dry product operations are easiest, requiring some instrumentation but almost no control devices except for a set firing and exit gas temperature. But control at elevated product-moisture levels are more involved, especially if the dust collection system involves a bag house, since it is sensitive to low exit gas temperatures and consequent moisture condensation problems. Electrostatic units work with condensation.