Development of a Heated Air Drying Unit for Food Waste

Abstract

In Korea, the daily waste production in 2015(excluding specified waste) was 404,812 tons, ofwhich household waste accounted for 12.7%(51,247 tons/day). Total household food andvegetable waste amounted to 1,120 tons/day; of this, 70% of was ultimately used as feed orfertilizer and 30% was buried. In this study, a drying unit was developed to enable theproduction of solid refuse fuel using high-moisture food waste, and its performance wasexamined through an experiment. Thus, a laboratory pyrolysis system with a drying capacity of500 kg/hr was manufactured. Food wastes were collected from a company cafeteria and fromChangwon City and used for experiment. The drying characteristics of the food waste wereexamined depending on the input temperature of the drying air. The results of the food wastedrying experiment showed that the total required drying time was approximately 20 hours, andthe drying speed was approximately 2.90 %/hr. The drying time was five hours longer than theresearch target value(15 hours per batch). However, the time was approximately 16 hours whenthe preheating and cooling times required for the input and output were excluded, which wasclose to the research target value. The drying time did not show a large difference dependingon the temperature of the input drying air. Drying time was 21 hours at 155℃, and thus dryingoperation would be possible without the use of high-temperature air(more than 200℃) whenwaste heat is utilized in the future. It is thought that rather than the temperature of the inputair, it is the contact area between the input air and the food waste that has a significant effecton reducing the drying time.