Ash Behaviors in Pulverized Coal Combustion with Highly Preheated Air

Abstract

Particle size and composition distributions of ash particles in both reacting coal and depositing layer are analyzed, using CCSEM (Computer Controlled Scanning Microscope), to study behaviors of ash particles included in the reacting coal and deposition phenomena. For the behaviors of ash particles in the reacting coal, fraction of the coarse particles gradually increases due to coagulation, so that the composition of the coarse particles also changes during evolution and combustion processes of volatile matter. For structure of the deposit layer, on the other hand, fine particles of size less than 3μm mainly consist of the initial layer for three types of coal, and the thickness was about 30μm. Growth behavior of the deposit at the stagnation depended on the coal type. The deposition phenomena take place due to preference of both particle size and composition.