The IFRF provides an externally air-staged burner (EASB) for testing NOx reduction strategies in pulverized coal flames. Performance characteristics of the EASB have been studied in detail at the IFRF. A fuel-rich primary zone is established in the flame by splitting the combustion air into three separate streams. The secondary combustion air is swirled using an IFRF moveable block swirl generator to establish a stabilizing internal recirculation zone. The remaining tertiary combustion air is delivered into the char burnout zone where combustion is completed.