The present invention relates generally to spray nozzles, and more particularly to air atomizing spray nozzles of the type that generate a spray pattern in which liquid droplets are distributed uniformly throughout the spray pattern, and which finds particular, but not exclusive, utility in apparatus for the continuous casting of steel slabs, ingots, billets or the like. Such nozzles are often called "full cone spray nozzles" and are distinct from nozzles which generate hollow cone shaped patterns in which the liquid droplets discharge in an annular pattern with a central air core.
In both full cone and hollow cone spray nozzles, it is known to assist liquid atomization by directing pressurized air streams to engage the discharging liquid spray. This can be accomplished by converging the pressurized liquid and air streams within the body of the nozzle prior to discharge of the liquid stream. In hollow cone spray nozzles, it is also known to direct a pressurized air stream into impingement with the discharge liquid at a point external to the discharge orifice of the nozzle. Such external atomization is less frequently employed with full cone spray nozzles, because of an inability to effectively atomize the full cone spray pattern. The present invention addresses this difficulty and provides a full cone spray nozzle assembly that directs pressurized air to coact with a centrally located jet of liquid downstream of, and thus external to, the liquid orifice.
The present invention also provides a full cone spray nozzle that will discharge a substantially uniform pattern of fine droplets even if there is a dislocation or interruption in the supply of pressurized air. Such a disruption could result from a compressor failure, a valve blockage, a break in the supply line, or an electrical power outage. Because the distribution of coolant emanating from the nozzle assembly will remain substantially uniform under these circumstances, problems that might occur in a casting when coolant is applied in excessive amounts on some areas, and sparse amounts or none on adjacent areas, are essentially eliminated.
The following patents disclose various nozzle arrangements in which a liquid stream is atomized by pressurized air: U.S. Pat. No. 4,645,127 to Emory et al., and assigned to Spraying Systems Co. of Wheaton, Ill.; U.S. Pat. No. 4,386,739 to Kwok; U.S. Pat. No. 4,236,674 to Dixon; and West German patent 27 02 191.