Method for generating combustion by means of a burner assembly and burner assembly therefore

A method of generating combustion by means of a burner assembly comprising a refractory block, a fuel supply system and an oxidant supply system including an inner oxidant supply and an outer oxidant supply, the oxidant being supplied comprising first and second oxidants, wherein:

• multiple fuel passageways extend along a first plane through the refractory block from a fuel inlet port to a fuel outlet port,
• multiple oxidant passageways extend through the refractory block from an oxidant inlet port to an oxidant outlet port,
• each of the oxidant passageways comprising an upstream portion extending from said oxygen inlet port along a plane,
• each of the oxidant passageways comprising a downstream portion terminating at said oxygen outlet port and extending along a second plane that intersects said first plane along a line beyond said outlet ports,
• said upstream portions are angled to respective ones of said downstream portions so as to form a bend in each of said oxidant passageways,
• said inner oxidant supply comprising multiple straight oxidant lances each one of which is concentrically disposed within a respective one of said upstream portions and extends to a point in between a respective one of said bends and said oxidant outlet port,
• said oxidant lances fluidly communicating with a source of a first oxidant,
• said outer oxidant supply comprising multiple spaces each of which is defined by an outer surfaces of a respective one of said oxidant lances and an inner surface of a respective one of said oxidant passageways,
• said spaces fluidly communicate with a source of a second oxidant, the method comprising the steps of:
• (a) selectively supplying the lances with a first oxidant, said first oxidant containing at least 70% vol. of oxygen;
• (b) selectively supplying the spaces with a second oxidant, said second oxidant being air;
• (c) melting a charge in a furnace using the burner assembly with heat from the combustion of oxidant and the fuel;
• and
• (d) varying the ratio between said first and second oxidants being supplied to the lances and spaces, respectively, said step of varying the ratio comprising:
• supplying oxidant to the lances and spaces at the start of a melting phase such that at least 50% of the oxidant is supplied as the first oxidant to said lances for combustion with the fuel downstream of the burner assembly and not the second oxidant,
• at the end of the melting phase, a ratio between a flow of the second oxidant through the outer oxidant supply and a flow of the first oxidant through the inner oxidant supply is increased;
• and
• during a fining phase following the melting phase, the burner assembly is operated so that more than 50% vol. of the oxidant supplied by the burner assembly is second oxidant provided by the outer oxidant supply.