INTERACTIVE PROCESSES IN GASIFICATION AND COMBUSTION .2. ISOLATED CARBON, COAL AND POROUS CHAR PARTICLES

Most combustion systems use dense sprays of liquid fuels or pulverized fuel suspension for combustion. Thus the interactive processes between the drops/particles play a crucial role in the ignition and combustion behavior and pollutant formation and destruction. A comprehensive review is presented of the interactive transport processes in the gasification and combustion of a cloud of drops and solid particles. The review originally intended to be in two parts is now divided into three parts. Part I (Prog. Energy Combust. Sci., 18, 1992) is concerned with the interactive processes for arrays, streams and clouds of drops, Part II presents a review of isolated coal/char particles as an introductory material to interactive processes and finally Part III deals with the interactive processes for solid particle arrays, streams and clouds. While drops are totally gasifying, coal is a partially gasifying solid which yields char on gasification. As such there exists separate studies for the pyrolysis of coal and combustion of char particles. The kinetics modeling of pyrolysis, oxidation of volatiles and CO, carbon reactions, heterogeneous and homogeneous ignition and combustion of carbon and coal are reviewed. Because of strong analogy of the group ignition and combustion to porous char ignition and combustion, the literature on porous char combustion is also included. In order to maintain the continuity, new results are presented on the internal ignition of porous char particles using a Frank-Kamenetskii type of analysis. The ignition and combustion results of porous char are later used in Part III of the review which deals with group ignition and combustion of char clouds.