Parallel flow burner has a central liquid fuel-atomizing nozzle, which is disclosed. Its inner member defines a steam chamber and is surrounded by a shell that defines a liquid fuel compartment. A conduit extends from the steam chamber forming a steam core flow. A first passage feeds liquid fuel about the steam core flow to form an annular liquid fuel stream thereabout. A second passage forms an outer steam low, which envelops the annular liquid fuel flow. The burner further includes ducts to form a first combustion airflow co-axially about the nozzle, a second combustion airflow which surrounds the first flow, and a third combustion airflow which envelops the second flow generally protects the furnace wall from coming into contact with the flame generated by the burner.