Spray Dryer Uses Electrostatic Technology for Efficient Microencapsulation

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Fluid Air’s PolarDry Electrostatic Spray Dryer offers low-temperature microencapsulation and agglomeration in one step.

The new, patent-pending PolarDry Electrostatic Spray Dryer from Fluid Air, a division of Spraying Systems Co., uses electrostatic technology, rather than heated drying gas, for microencapsulation. This technology eliminates the intense heat of traditional spray drying and is more efficient at encapsulating the active ingredient. The system also allows agglomeration during the drying step, eliminating the need for secondary agglomeration operations. 

The spray dryer’s electrostatic technology drives water to the shell and active to the core, lowering the evaporation temperature and eliminating active ingredient loss and degradation, thus creating a longer shelf life, higher bulk density, and superior morphology. Inlet drying temperatures remain low (from ambient to 80 °C).

In addition, the patent-pending Pulse Width Modulation (PWM) feature can control the electrostatic charge applied to the feed on an intermittent basis to agglomerate particulates as they are being dried. By controlling the voltage applied to the spray droplet as it is being atomized, some particles form an outer shell readily while others develop their shell gradually, resulting in a wet or tacky particle. As these two types of particles colloid, they bond and form an agglomerated particle. The finished product flows more freely and has larger particles and fewer fines compared to traditional agglomerated product.


The machines incorporate a patent-pending collection and particle-separation plenum that can be configured for batch or continuous processing. The systems are currently available in four scales: the feasibility scale (Model 001) with a once-through design for the laboratory, an R&D scale (Model 004), a pilot scale (Model 032), and a production scale (Model 050). The R&D scale is a semi-portable unit with a recirculating gas-handling system and a nominal evaporation rate of 4 kg/h; this unit uses the same nozzle as the larger-scale units for ease of scale-up. The pilot-scale unit has a nominal evaporation rate of 30 kg/h, and the largest unit has a rate of 50 kg/h.

Source: Fluid Air