Kinetic Study of Pure Oxygen Combustion of Coke Blended with Calcium Oxide

Abstract

ABSTRACT In order to elucidate the mechanism of CaO on pure oxygen combustion of coke, non-isothermal TGA technique was use to test coke blended CaO samples of varying C/Ca molar ratios (CMCa-2, CMCa-3, and CMCa-4). The characteristic combustion temperatures at varying β were measured. The representative CMCa-2 and CMCa-4 were tested by TG-MS to determine the effect of CaO on coke combustion. Kinetics parameters for the blended samples across various reaction phases were determined using the improved Coats-Redfern method. The results showed that in the pure oxygen atmosphere, the combustion characteristic temperature rise with the increase of β. The material transformations during different reaction stages proceeded as follows: coke combustion generated CO2, CO2 combined with CaO to generate CaCO3, and finally CaCO3 decomposed to release CO2. The E values of three reaction stages were as follows: the highest E was observed in stage 3, ranging from 128.05–151.18 kJ·mol−1, the lowest E in stage 2 was below 46 kJ·mol−1, and the E in stage 1 laid between 99.35–128.71 kJ·mol−1. The C/Ca molar ratio was proportional to the kinetic parameters of the blended sample.