Premix burner and method of operation

A premix burner, suitable for forming at least one stable flame front in a combustion chamber, comprising means for supplying fuel and air to said premix burner, and means for mixing fuel and air to form a fuel/air mixture for subsequent combustion in the combustion chamber, said burner comprising

• a premix burner casing, having an upstream end and a downstream end thus defining a flow direction, said burner casing having a the form of a tube which is open at the upstream end and being in fluid communication with the combustion chamber at its downstream end via a transition contour, for flowing air therethrough;
• a burner lance being formed as an inner tube, and projection into the interior of the premix burner casing on the premix burner casing upstream end, thus forming an annular flow duct with the burner casing, the burner lance having:
• an upstrem end, a downstream end, and an inner tube wall, forming an inner flow passage enclosed by said tube wall;
• at least one first fuel supply unit being provided on the inner tube wall to supply fuel into the inner flow passage, and at least one second fuel supply unit being provided on the outer wall of the burner lance to supply fuel into the annular flow duct.