Chemical Kinetics Simulation on Alkali Metal Migration Behaviors of High-Alkali Coal Under Oxy-Fuel Condition

This is the authors' abstract. We don't add key points for this paper.

Zhundong coal not only possesses abundant reserves but also exhibits numerous advantages, including high volatile matter content, low ash content, and exceptional ignition and burnout performance. However, the excessive content of alkali metals leads to serious issues such as ash deposition, slagging, and corrosion on heating surfaces. The volatile computational model was used to convert solid phase coal into gaseous phase matters to conduct chemical kinetics simulation on oxy-fuel combustion of high-alkali coal under air-staged conditions. The simulation results indicate that in an oxy-fuel atmosphere, the NaOH level is approximately 30% higher than in an air atmosphere, whereas the Na content in the former is roughly 30% lower than in the latter. The migration paths of sodium in the primary combustion zone and the burn-out zone are summarized. An oxidizing atmosphere significantly promotes the generation of Na2SO4 and K2SO4. The promoting effects of both the excess oxygen coefficient and oxygen concentration on Na2SO4 formation may be limited by the content of sulfur element. With the increase of chlorine content, NaCl content increases significantly while the contents of Na, NaOH and Na2SO4 decrease greatly. In the burn-out zone, an elevation of chlorine content significantly promotes the chlorination of sodium, while having no effect on the chlorination of potassium. The present work provides theoretical support for regulating alkali metal migration pathways to mitigate slagging and fouling issues in actual power plant.