Fuel staging methods for low NOx tangential fired boiler operation

A tangential fired boiler comprising:

• a circumferential wall defining a combustion zone, said circumferential wall being generally rectangular when viewed along a generally horizontal cross-section and having a diagonal;
• a fireball disposed within the combustion zone, said fireball rotating about an imaginary axis when viewed along a generally horizontal cross-section;
• a corner member disposed proximate to at least one corner of said combustion zone, said corner member being angled with respect to a normal of the diagonal and downstream relative to a direction of rotation of said fireball;
• a plurality of fuel inlets disposed along said corner member, said plurality of fuel inlets injecting fuel into the combustion zone;
• a plurality of air inlets disposed along said corner member, said plurality of air inlets injecting air into the combustion zone;
• and
• wherein at least some of said plurality of fuel inlets inject fuel in a direction which is angled between about 15 degrees and about 25 degrees with respect to a normal, when viewed along a generally horizontal cross-section, of said corner member and upstream relative to a direction of rotation of said fireball.