Pulse Combustion Drying

Abstract

Pulse combustors provide an advantageous superposition of unsteady gas flow and high-intensity sound waves. Such a combination not only accelerates drying rates because of increased heat and mass transfer but also allows processing of liquids, pastes, and agglomerated solids in a dispersed state due to aerodynamic impact on the high-intensity sound wave. Over the last decades, applications of pulse combustion dryers have been exploited continuously, and different pulse combustion dryers have been designed and fabricated. In pilot tests and technical reports on these dryers, short drying time, high energy efficiency, and product quality are generally reported, which show that pulse combustion drying is regarded as a technology of the future in convective drying. This chapter attempts to introduce the basic knowledge and state of the art about this emerging technology and summarizes recent studies about pulse combustion drying and equipment design. Following a concise description of pulse combustion and pulse combustor, the basic types of pulse combustion dryers are presented, including spray dryers, fluidized bed dryers, impinging dryers, and dryers of special design. The existing commercial applications and pilot tests are described, and their potential applications are identified.