Spillback lances have gained a proven record of efficiency and reliability through long years of satisfactory service, and are widely used in a number of industrial processes like cement manufacturing, refuse incineration and cooling blast furnace gas in iron mills. A spillback lance works on the principle of pressure atomization, with the liquid being atomized as the only fluid going through the nozzle. Spillback lances can produce fine sprays over a wide capacity range with little changes in other spray characteristics, like droplet sizes, by means of an infinitely variable capacity adjustment with a 1:10 ratio.
The spray pattern is a hollow cone, with a typical spray angle of 90°. To obtain the wide range of capacity values the spillback nozzle is provided with a return line, whereby a part of the liquid sent by the pump to the lance can bypass the nozzle and go back to the liquid tank without being atomized through the nozzle orifice. When the spillback line is closed, and no liquid can bypass, maximum nozzle capacity is available. With the spillback line open, adjusting the flow through the line by means of a valve, one will determine the pressure value inside the nozzle whirl chamber and therefore the quantity of liquid being atomized. Spillback lances can therefore offer a flexible response to changes in the requirements of the cooling process.