Abstract: A combustion system comprises a combustion chamber and a flue gas duct located downstream of the combustion chamber to receive combustion products from the combustion chamber, the combustion chamber has a base and an enclosing wall connecting the base to the flue gas duct. The combustion chamber is provided with a plurality of combustion devices, the combustion devices being configured to deliver fuel and gas and/or air into the combustion chamber so as to generate a fireball within a combustion zone in the combustion chamber, the combustion devices further being configured such that the generated fireball rotates about an axis extending between the base and the flue duct. A secondary gas and/or air nozzle is provided in the base of the combustion chamber, at a location upstream of the combustion zone, the nozzle being for delivering gas and/or air into the combustion zone in a direction towards the flue duct.

Abstract: A burner nozzle for delivering fuel to a burner flame in a furnace includes an inner cylinder and an outer cylinder that are both hollow. The inner cylinder is at least partly disposed within the outer cylinder and axially aligned with it, and is movable in an axial direction relative to the outer cylinder. One end of the inner cylinder has at least one outward projection extending in a radial direction from the outer surface of the cylinder, this projection serving to decrease the free cross-sectional area between the inner cylinder and the outer cylinder at that end of the inner cylinder.