Premixed fuel/air burner

A premix fuel/oxidant burner with velocity and fuel/air ratio control comprising:

• a nozzle having a nozzle wall forming a Venturi mixer and a nozzle exit;
• means for separately introducing fuel and oxidant into said nozzle;
• a hollow body disposed inside said nozzle, said hollow body moveable in a longitudinal direction toward said nozzle exit;
• said hollow body having at least one orifice through a wall of said hollow body at an angle with respect to a longitudinal axis of said nozzle;
• a combustion chamber wall forming a combustion chamber downstream of said nozzle exit, said nozzle exit in communication with said combustion chamber;
• and
• a refractory sleeve disposed inside said combustion chamber forming an annular space between said refractory sleeve and said combustion chamber wall whereby flue gases resulting from the combustion of said premixed fuel and oxidant are recirculated from a downstream end of said combustion chamber through said annular space toward said nozzle exit.