Method for burner and burner device

A method for increasing efficiency when heating an industrial furnace using a burner device comprising a first channel (3) for fuel, a second channel (4) for a first oxidant, the second channel (4) for the first oxidant being i) separate from the first channel (3) for the fuel, and ii) outside of the channel (3) for the fuel, an outlet (9) for flue gases, a control device (10), and a heat buffer (7), the method comprising the steps of:

• supplying the fuel through the first channel;
• alternatingly leading the first oxidant and the flue gases, in a gas flow direction toward the burner device, through the heat buffer and from the heat buffer through the second channel to the burner device;
• and
• supplying a second oxidant, comprised of at least 80 percentages by weight oxygen, via a separate lancing device to the burner device through the second channel, the second oxidant being supplied at a velocity which is at least sonic velocity, so that an ejector effect is created downstream of the heat buffer in relation to the gas flow direction towards the burner device, such that a flow of preheated oxidant is increased, and
• wherein the lancing of the second oxidant is supplied in the first channel for the first oxidant but not in the channel for the fuel.