ABSTRACT
A pulse combustion spray dryer is identical to a conventional tall-form spray dryer in the drying chamber and all components downstream, including the ducting, cyclone, baghouse/scrubber, and exhaust fan. Upstream of the drying chamber, however, things are different. In a conventional spray dryer, atomization is accomplished by pressurizing the liquid feed in a high-pressure pump (at up to 3000 psi) and forcing it through a tiny nozzle (located at the top center of the dryer) to create a fan-shaped spray of tiny droplets. As drying air is introduced into the drying chamber, the warm air evaporates the water from the atomized droplets, leaving behind a dry powder after 15-30 s of residence time in the dryer. This atomization method tends to apply high mechanical shear forces on the liquid feed, which can shred the capsule wall of encapsulated particles.
