Burner and combustion furnace

A burner comprising:

• a first nozzle having a tubular shape about a burner axis and including
• a main fuel outlet that discharges a fuel-air mixture containing main fuel and primary combustion air and
• a flame holding plate located around the main fuel outlet;
• a second nozzle located coaxially with the first nozzle and including a secondary air outlet that emits secondary combustion air at an outer peripheral side of the main fuel outlet;
• and
• auxiliary fuel injection nozzles extending along an outer surface of the first nozzle in parallel with the burner axis, wherein:
• the auxiliary fuel injection nozzles include
• auxiliary fuel outlets lined up along an outer peripheral edge of the flame holding plate or
• auxiliary fuel outlets located inside the outer peripheral edge of the flame holding plate and outside an inner peripheral edge of the flame holding plate;
• and
• the auxiliary fuel outlets discharge gas fuel as auxiliary fuel toward a boundary between flow of the fuel-air mixture discharged from the main fuel outlet and flow of the secondary combustion air discharged from the secondary air outlet.