Char particle fragmentation and its effect on unburned carbon during pulverized coal combustion. Quarterly report, July 1, 1995--September 30, 1995

Abstract

This project is intended to satisfy, in part, PETC`s research efforts to understand the chemical and physical processes that govern coal combustion. The work is pertinent to the char oxidation phase of coal combustion and focuses on how the fragmentation of coal char particles affects overall mass loss rates and how char fragmentation phenomena influence coal conversion efficiency. The knowledge and information obtained allows the development of engineering models that can be used to predict accurately char particle temperatures and total mass loss rates during pulverized coal combustion. In particular, the work provides insight into causes of unburned carbon in the ash of coal-fired utility boilers and furnaces. The information reported is for the period July I to September 30, 1995, although the actual work was performed over an extended period of time, from July 1, 1995 to August 1996. During this period, activities were undertaken in Task 3, char fragmentation studies, and Task 4, fragmentation modeling. Partially reacted chars were extracted from the laminar flow reactor at selected residence times and analyzed to determine extents of mass loss and particle size distributions and the particle population balance model was modified to take into account density variations for each sizemore » class of particles considered in the model.« less