Analysis of Drying Characteristics and Cost of High-Capacity Vacuum-Drying Food Waste Disposal System Using Steam

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Online ISSN 2234-1862 Print ISSN 1738-1266

ORIGINAL ARTICLE

Analysis of Drying Characteristics and Cost of High-Capacity Vacuum-Drying Food Waste Disposal System Using Steam Dae Bin Song 1 & Ki Hyeon Lim 2 & Dae Hong Jung 2 & Jong Hyun Yoon 2 Received: 13 March 2020 / Revised: 25 May 2020 / Accepted: 27 May 2020 # The Korean Society for Agricultural Machinery 2020

Abstract Purpose This study was conducted to develop a high-capacity vacuum-drying food waste disposal system that uses steam and to identify its drying characteristics and cost through an experiment. Methods A drying system with a drying capacity of 10,000 kg/h was fabricated that used the steam generated by a boiler as a drying heat source. Its performance was verified, and the drying cost was analyzed through a drying experiment in which water and mixtures (sawdust, flour, and water) were used as experimental materials. Results The results of the drying experiment showed that the input steam temperature was 193.2 °C, and that the average drying speeds were 19.65%/h for water and 3.89%/h for the mixtures. The drying speed increased as the drying progressed, and it reached a moisture content of 20% (wb) or less after drying without a drying delay caused by moisture condensation. The drying energy rate that represents the ratio of the drying energy consumption to the input energy was as high as 88.90% for water and 99.23% for the mixtures, on average. The total drying time was 5.5 h for water and 18.5 h for the mixtures on average, which were significantly shorter compared with that of the hot-air drying method. Conclusions The drying speed, water content after drying, drying energy rate, and total drying time were significantly improved compared with those of the case of converting steam to hot air when the boiler steam was directly used as a drying heat source for the disposal of large-volume food waste with high water content. The drying cost was also not significantly different from that of the methods that use electricity or gas as a heat source, indicating that the developed system can be used for the disposal of large volumes of food waste. Keywords Drying characteristics . Drying speed . Drying energy rate . Food waste . Drying cost

Introduction In 2005, the direct landfilling of organic waste, such as food waste, was banned due to odor and landfill leachate. From 2005 to 2018, the average daily generation of food waste was 14,385 tons. This was almost similar to the average daily generation of 15,305 tons between 2000 and 2005 before the ban, indicating that food waste generation was not significantly reduced (Me·Keco 2000, 2018).

* Dae Bin Song [email protected] 1

Department of Bio-Industrial Machinery Engineering, Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea

2

NDT Engineering Co., Ltd., Changwon 51343, Korea

Food waste is mainly used for animal feed and compost. Feeding pigs with food waste was completely banned in the aftermath of the African swine fever that emerged in 2019. Hence, the