Study On The Moisture Distribution And Drying Process Of MSW Components

Incineration becomes the main method for Municipal Solid Waste (MSW) in many developed countries, because it could be able to better realize the reducing of volume, harmless and turning to resources. In many cities of our country, the moisture content of MSW is very high while the calorific value is low, which causes a lot of difficulties to incinerate, the combustion conditions can be improved if MSW was dehydrated before incineration. Four kinds of typical MSW including waste paper, textile, pericarp and wood were researched in this thesis. Bound water content and moisture distribution characteristics of those four components were measured and the drying behaviors of those components were studied under low temperature. The main research contents are as followed:The bound water content of four components of municipal solid waste was measured based on three methods:drying test, thermogravimetric differential thermal analysis (TG-DTA) test and thermogravimetric differential scanning calorimetry (TG-DSC) test, the continuous moisture distribution was constructed by the last two methods. The differences in moisture distributions of different samples were compared, as well as the advantages and disadvantages of these three measuring methods.Drying characteristics of four components were obtained under40～80℃, influences on drying process of drying temperature, ventilation rate, sample size were analyzed. Experimental results showed that the drying rate increased with increasing temperature and ventilation rate, but the added value reduced gradually, sample size also affected the drying process.Thin layer drying models such as Newton, Herderson and Pabis, Page, Modified Page were used to describe the drying process of four typical components. The accuracy of the fitting results obtained from these four thin layer drying models were tested and verified, Modified Page model was found to show better predictions than others.The kinetics parameters of the drying process of four components were gained, based on the Fick’s second law, the effective moisture diffusion coefficient varies from6.51×10-8m2·s-1to23.84×10-8m2·s-1, In addition, the temperature dependence of the effective diffusivity coefficient is expressed by Arrhenius type relationship. The activation energy of the four components varied from10.75kJ·mol-1to32.16kJ·mol-1...