A study on deviation of noncatalytic gas–solid reaction models due to heat effects and changing of solid structure

In this study a common type noncatalytic gas–solid reaction is modeled based on some well-known, previously presented mathematical models, including grain, modified grain and additive reaction times models. In order to approach more realistic models, the heat effects and the changing of solid structure effects are considered in the above named mathematical models. The governing equations are developed and solved numerically. Then, the predicted results are compared with available experimental data presented for some important industrial gas–solid reactions. The results reveal shortage of the simplifying assumptions of the referred models to predict solid conversion, as a result of neglecting heat effects and structural changes of solid reactant. In this study, for the first time, the process of the change in the different reaction controlling steps is considered during the reaction time. The results also show that the main rate-limiting resistances convert to each other during the reaction progress. It reveals that the undesirable heat and structural changing effects decrease with decreasing the particle diameter, increasing the convective heat transfer coefficient, and taking appropriate gas temperature. This study shows that considering heat effects and changing of solid structure improve the abilities of previous mathematical models to predict the behavior of noncatalytic gas–solid reactions.

Graphical abstractThe shortage of the simplifying assumptions of three well-known previously presented models for modeling of noncatalytic gas–solid reactions was examined considering heat effects and the effects of changing of solid structure. The results showed that considering these effects improves the abilities of the previous mathematical models.Figure optionsDownload full-size imageDownload as PowerPoint slide