Burner for operating a heat generator

A burner useful for operating a heat generator comprising:

• a swirl generator having an upstream end, a downstream end, and defining a flow axis between the upstream and downstream ends, the swirl generator conducting a combustion-air flow therethrough at least partially downstream;
• means for injecting at least one fuel into the combustion-air flow;
• a mixing section positioned downstream of the swirl generator and including a upstream part and a mixing tube downstream of the upstream part, the upstream part including at least one transition passage passing the swirl generator flow into the mixing tube, the mixing tube including a downstream part;
• an annular pilot-burner system arranged around the mixing tube downstream part, the pilot-burner system comprising at least a first annular chamber, a second annular chamber, and a third annular chamber, wherein said second chamber is positioned at least in part concentrically around said first annular chamber, and at least a part of said third annular chamber is positioned downstream and adjacent said first and second annular chambers;
• wherein the pilot-burner system includes a downstream wall adjacent to the third annular chamber, the downstream wall comprising a heat shield plate;
• wherein the pilot-burner system includes a plate having axially oriented perforations, the second annular chamber being divided from the third annular chamber by the plate, the plate causing air flow entering the second annular chamber to form jets of air to provide impingement cooling for the heat shield when air flows through the second annular chamber;
• wherein the pilot-burner system includes at least one throughflow opening fluidly communicating the first annular chamber with the third annular, the at least one throughflow opening causing a gaseous fuel flow entering the first annular chamber to flow into the third annular chamber and form an air/fuel mixture with the air when air flows through the second annular chamber and fuel flows through the first annular chamber;
• wherein the heat shield plate includes at least one circumferentially arranged opening which causes the air/fuel mixture to flow from the third annular chamber downstream and to burn as pilot flames when air flows through the second annular chamber, fuel flows through the first annular chamber, and the air/fuel mixture is ignited.