DIRECT FLAME BURNER UNIT FOR FURNACES FOR THE THERMO-CHEMICAL TREATMENT OF STEEL STRIPS IN CONTINUOUS HOT-DIP GALVANIZING PLANTS

摘要

Direct flame furnace burner unit (100) for furnaces (200) for the thermo-chemical treatment of steel strips in continuous hot-dip galvanizing plants, comprising a burner provided with: - a combustion head (11) provided with a combustion chamber (12) having an outlet opening (13) of the combustion flame; - a body (14) to which the combustion head (11) is fixed and which comprises: a first chamber (16) which is in communication with the combustion chamber (12) and which is provided with at least one inlet opening (17) connectable to a supply source (SA1) of a pre- heated comburent, a first lance (18) for the injection of a fuel into the combustion chamber (12) and which has an inlet end which is connectable to a first supply source of a fuel (SG1) and an outlet end in communication with the combustion chamber (12), a mixing chamber (19) provided with at least a first inlet opening (20) which is connectable to a supply source of a not pre-heated comburent (SA2), with at least a second inlet opening (21) which is connectable to a second supply source of a fuel (SG2) and with at least an outlet opening of the mixture formed therein; at least a second lance (23) for the injection of the mixture into the combustion chamber (12) and having an inlet end in communication with the outlet opening of the mixing chamber (19) and an outlet end in communication with the combustion chamber (12); wherein the burner is alternatively and selectively operable in two distinct operating modes: a diffusive flame combustion mode, with lambda ranging between 0.9 and 0.98, wherein the combustion chamber (12) is fed only through the first chamber (16) and the first lance (18) respectively with the preheated comburent and with the fuel, and a premixed flame combustion mode, with lambda ranging between 1 and 1.25, wherein the combustion chamber (12) is fed only by means of the second lance (23) with the mixture formed inside the mixing chamber (19).