| 论文简介 |
The overall impact of CO 2 on the coal char combustion is complicated due to the interplay between the CO 2 thermal effect and chemical effect (including the gasification endothermicity, and its direct additional carbon consumption). To assess the impact of these factors on the carbon consumption process, we conduct a quantitative study on the separate physicochemical effects of CO 2 through experimental and kinetic research. Two oxygen concentrations (15% and 21% O 2 ), representing industrial boiler and air combustion environments, were selected. The experiment research on its thermal effect (evaluated by carbon conversion ratios) is performed at 1773 K in a high-temperature drop tube furnace. The chemical effect of CO 2 is predicted for a 100 mu m coal char particle using a self-developed char burning kinetics model. Results indicate that the carbon conversion ratios show a V-type distribution with higher CO 2 concentrations, as a result of its complex physicochemical effects, with minimal carbon conversion points around the CO 2 concentrations of 5-10 vol.%. The thermal effect initially increases with higher CO 2 concentrations from 0 to 10 vol.%, but it declines with a further increase in CO 2 concentrations, while the endothermicity effect of the gasification reaction increases with higher CO 2 concentrations. The relative contribution of the endothermicity effect on the char consumption is 20.4% in the 21%O 2 /10CO 2 /N 2 environment, lower than the thermal effect (29.9%), but it continuously increases and becomes the most influential inhibitory factor at higher CO 2 concentrations. The strongest suppression effect of CO 2 corresponds to the CO 2 concentrations of 10 vol.%. (c) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved. |
(创新港)
