An apparatus for combustion of a liquid fuel, such as an atomizer or burner, and an associated method using the apparatus for combusting an atomized liquid fuel. The apparatus for combustion has an outer conduit, an inner conduit and a spray tip. The spray tip has a mixing chamber for receiving a liquid fuel and an atomizing gas, and an orifice for discharging the liquid fuel and atomizing gas mixture as an atomized liquid fuel. The inner conduit has external fins where at least some of the external fins contact the inner surface of the spray tip.