연구홍보포털

논문 초록 (Abstract)

We investigated the evaporative drying by immersion in hot oil (EDIHO) method for drying sludge. This involved heating oil to a temperature higher than that needed for moisture to be evaporated from the sludg e by turbulent heat and mass transfer. We fry-dried sewage and leather plant sludge for 10 min in each of four different oils (waste engine , waste cooking, refined waste, and B-C heavy) and three different temperatures (140 degrees C, 150 degrees C, and 160 degrees C). Drying efficiency was found to be greater for higher temperatures. How ever, giving consideration to energy efficiency we suggest that the o ptimal temperature for fry-drying sludge is 150 degrees C. At 150 degr ees C, the water content of sewage sludge reduced from 78.9% to betwee n 1.5% (with waste cooking oil) and 3.8% (with waste engine oil). The reduction in water content for leather plant sludge fry-dried at 150 degrees C was from 81.6% to between 1% (with waste cooking oi l) and 6.5% (with refined waste oil). The duration of the constant r ate-drying period was also influenced by the type of oil used: refined w aste oil > waste engine oil > B-C heavy oil > waste cooking oil. The dur ation at 150 degrees C with waste cooking oil was 3 min for sewage slu dge and 2 min for leather plant sludge. It is likely that the drying characteristics of oil are influenced by its thermal prope rties, including its specific heat, and molecular weight. (C) 201 0 Elsevier B.V. All rights reserved.