NUMERICAL ANALYSIS OF THE SIZE AND SHAPE OF NEW YORK CITY MUNICIPAL SOLID WASTE (NYCMSW) AND RESIDUES FOR COMBUSTION CHAMBER DESIGN

摘要

The size and shape of New York City municipal solid waste (NYCMSW) and combustion residues (ashes) are numerically analyzed in order to investigate the size reduction of particles on the grate of a waste-to-energy (WTE) combustion chamber. It is also necessary for designing a new combustion chamber, due to the heterogeneous MSW particles. About 360 MSW particles for this study were sampled in the black bags collected in residential areas at five boroughs of New York City. Also about 210 ash particles from a WTE combustion chamber were sampled. Length, breadth, perimeter and area of each MSW and ash particle are measured by means of image analysis that is more accurate than sieve analysis. Based on the image analysis, the particle size distributions (PSiD) and particle shape distributions (PShD) of MSW and residues were created. The mean size of NYCMSW was found to be 12.8cm and standard deviation of the MSW PSiD to be 6.4. Also mean size and standard deviation of the ash PSiD to be 2.4cm and 0.5889, respectively. Also Three types of shape factors (aspect ratio, roundness and sphericity) are used for creating 3 PShDs (aspect-ratio distributions, roundness distributions and sphericity distributions). Based on the similarity of the particle shapes quantified as these shape factors, the particles of MSW and residues are divided into 9 clusters by means of cluster analysis. This cluster analysis showed categorized characteristics of particle shapes that can be used for predicting surface areas of particles and mobility of particles in MSW bed on the traveling grate, both of which are major parameters for simulating combustion process in WTE systems.