Abstract: The burner of the present invention has a throat section which is in communication with a fire tube located downstream from the throat section. Nozzle means are provided for introducing a fuel in the throat section in a downstream direction toward the fire tube. Very importantly, means are provided for forming a swirling combustion air stream substantially along the side walls of the throat and fire tube thereby reducing the static pressure along the axis of the burner. Also very importantly, means are provided for introducing a gas stream to the throat and downstream of the nozzle means in a swirling direction opposite to that of the swirling combustion air stream.