Atomization and Drying Characteristics of Sewage Sludge inside a Helmholtz Pulse Combustor

Abstract

Sewage sludge of pasty consistency was atomized and dried directly using a high-temperature, highly turbulent gas flow in the tailpipe generated by a Helmholtz gas-fired pulse combustor (PC). Parametric studies were carried out to investigate the effect of drying pipe length and sludge feed tube size on the PC sludge drying process. Experimental results showed that the pulsating gas stream can disperse the sludge into small particles with a narrow size distribution between 0.01 and 4 mm and the granular sludge was dried rapidly due to the increased particle surface area and the high temperature of the drying medium. PC drying of sewage sludge was compared to convective- and microwave-drying processes. The application potential of the PC sludge-drying process is discussed based on the experimental results.