ENERGY-OPTIMAL EXCESS OXIDIZER RATIO AND ACTIVATION EFFECTS IN COAL GASIFICATION

This work applies equilibrium thermodynamic modeling to analyze the energetic performance of coal gasification as a function of the excess oxidizer ratio α under air and oxygen conditions. The analysis treats α as a continuous control parameter and examines the combined behavior of equilibrium temperature, volumetric calorific value of the synthesis gas, and specific gas yield. The results reveal a consistent three-stage thermodynamic structure in the response of these parameters to changes in α, including a distinct transition region characterized by simultaneous changes in slope and curvature. The energetic maximum of the synthesis gas is shown to be a well-defined characteristic point embedded within this transition region, where the increase in gas yield and temperature no longer compensates for the decline in volumetric calorific value. For oxygen gasification, the maximum energetic output occurs at α ≈ 0.33, while air gasification reaches its optimum at α ≈ 0.36. Additional calculations with small iron additions demonstrate that minor changes in fuel composition can influence equilibrium redistribution of reaction products without shifting the location of the energetic optimum. The study shows that an integrated energetic criterion provides a consistent basis for interpreting gasification behavior and for understanding the thermodynamic factors governing the position of the energetic maximum.