Method of reducing the nox-emissions during combustion of nitrogen-containing fuels

A method for the reduction of the NO.sub.x -emission during the combustion of nitrogen-containing fuels via a plurality of burner units each including a primary burner and being arranged preferably vertically in a wall of a closed combustion chamber, the method including the step of supplying fuel and combustion air in stages to the burner flames via supply lines, which are separated from each other and open into the wall in a substantially vertical arrangement, the improvement in combination therewith comprises with a number of said primary burners one arranged above the other the steps of:

• feeding coal dust along with its carrier gas, and a stream of mantle air, to the primary burner and generating a primary flame zone having a strong internal back flow region and burning the coal dust under fuel-rich conditions,
• feeding reduction fuel in the form of coal dust, along with its carrier gas, into the combustion chamber and generating a secondary flame zone in the vicinity of the primary flame zone and being operated under more-fuel-rich conditions than the primary flame zone,
• and feeding stage air into the combustion chamber and generating a final combustion zone in the vicinity of the secondary flame zone and being operated under fuel lean conditions.