Low NOx burner for liquid and gaseous fuels

A low-NOx burner for liquid and gaseous fuels, of the type in which the combustion air is split into two streams. The primary air stream, fed through a plurality of windows (12), crosses at the outlet a series of oriented blades (15) which impart vorticity to it. The secondary air stream, fed through a series of windows (19), crosses a series of oriented blades (22) axially movable for varying the degree with respect to the inlet windows (19) . The windows (12, 19) for the primary and secondary air inlet have movable dampers (13, 20) for continuously adjusting the inlet section. This particular structure of the burner, particularly suitable for low/medium capacity installations, allows for a stage combustion typical of more complex geometry burners to be carried out, with a cost saving with equal capacity and pollutant emissions.