Effect of CaO on drying characteristics of municipal solid waste

The drying of municipal solid waste in the Refuse Derived Fuel (RDF) production process was supposed and the effect of CaO addition on the drying characteristics was experimentally examined. A mixture of pulp (water soluble pulp), plastic (polyvinyl chloride powder), protein (soybean protein powder) and water (2.0 kg/kg-dry solid) was used as the model refuse. Model flue gas, which was air including CO2, was used as the drying gas. The CaO content and operational conditions were varied, and the changes in weight and temperature with time were measured. A hard layer on the drying side of sample is formed due to the protein denaturation. With increasing CaO content, this layer becomes thinner and more cracks generate. As a result, the drying time is shorter. When the drying gas temperature is relatively high, the drying rate in the case with CaO is higher than that: in the case without: CaO. The reaction between CO2 in the drying gas and Ca (OH)(2) in the waste has a significant influence on the drying rate. To obtain the higher drying rate, more uniform addition of CaO is required.