ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Comparison of Single Coal Char Particle Combustion at Different Conditions

K. Holíková, R. Žajdlík, J. Markoš, and Ľ. Jelemenský

Department of Chemical and Biochemical Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-812 37 Bratislava

E-mail: jozef.markos@stuba.sk

Abstract: Comparison of single coal char particle combustion at different operation modes is presented. Experiments were carried out applying a thermogravimetric method. During combustion of a single particle, time dependences of temperature inside the particle, around the particle, and the mass of particle were measured together with the internal porous structure of particles at different degrees of burnout. Obtained experimental results have shown that the mechanism of combustion is strongly dependent on the combustion conditions, especially on the initial temperature and oxygen content in the inlet gas. At temperatures below 500^oC, the limiting factor was the oxygen concentration. Combustion using the inlet concentration of oxygen below 5 vol. % was governed by the reaction-diffusion mechanism. If the content of oxygen in the inlet gas exceeded 5 vol. %, combustion proceeded according to the shell progressive mechanism. At temperatures above 500^oC, the shell progressive mechanism of coal particle combustion was supposed, independently of the oxygen concentration.
The problems related to mathematical modelling of the combustion of the single char particle under condition of reaction-diffusion mechanism are discussed.

Full paper in Portable Document Format: 596aa413.pdf

Chemical Papers 59 (6a) 413–420 (2005)