Assessment of Thermal Treatment for Windrow Drying Process of Refused-Derived Fuel (Rdf): A Case Study

Abstract

This study revealed the details of the heat and mass transfer mechanisms that take place during the drying process of RDF, assisted with a turning machine. The experiments were carried out in an industrial scale open air drying facility. The experimental results showed that the main factors affecting the performance of the drying technology are the turning efficiency, ambient conditions, and bio-heating efficiency. The drying time for decreasing the moisture content of RDF from 30.5% to 16% was 6 hours, at winter weather conditions, with a turning machine moving over the row with a speed of 5m/min. The linear speed of the turning machine must be higher than 3m/ min to avoid the evacuation of RDF in front of the turning drum. Although the drying process requires 6 hours of turning machine operation, this time must be distributed over 4 days to benefit from the bio-heating process. The study showed the effect of this heating process on the temperature distribution of RDF during the drying process. The bio-heating energy was 22.3 kWh/ton (wet product). The volumetric mass transfer coefficients increased about seven-fold during the drying process. These coefficients were 0.04, 0.017, and 0.24 kg/m 3 at moisture contents, 30%, 20%, and 15%, respectively. The rate of water evaporation was 21.6 kg/ton(wp) per running hour of the machine. When the moisture content becomes less than 24%, the turning machine-assisted windrow drying becomes more efficient. The data introduced are helpful for enhancing the drying process in bad weather conditions, and this will be our future work.