Burner assembly comprising: - a burner unit having an inlet face and an outlet face, at least one passage of combustion agent (506, 507) between the inlet face and the outlet face and at least one fuel rod passage (500, 501) between the inlet face and the outlet face, the burner unit being such that m fuel rods can simultaneously be mounted in the burner unit through the at least one fuel rod passage (500, 501), with m > 1, - n rods of a first fuel (110, 111), with n > 1, each rod of a first fuel (110, 111) able to be mounted in the or in one of the fuel rod passages (500, 501) and to be removed from said fuel rod passage (500, 501) par the inlet face du burner unit, - a combustion agent supply device able to transport a flow of combustion agent to the burner unit for the injection thereof through the at least one combustion agent passage (506, 507) in a combustion zone located downstream of the outlet face, - a first fuel supply device able to transport a flow of a first fuel from a source of first fuel to the burner unit for the injection thereof into the combustion zone through one or several fuel passages (500, 501), the first fuel supply device comprising a first supply line, a first flow meter, a first distributor and n first flexible lines (120, 121) connecting the first distributor to the n rods of a first fuel (110, 111), i. the first supply line being able to transport the flow of the first fuel from the source of first fuel to the first distributor, ii. the first flow meter being able to regulate the flow rate of the flow of the first fuel from the source of first fuel to the first distributor, iii. the first distributor being able to distribute the flow of the first fuel into n subsidiary flows over the n first flexible lines, characterised in that: - the first fuel supply device comprises one or several valves (130, 131) making it possible to close and to open the n first flexible lines one by one in such a way that, when x of the n first flexible lines are closed by said one or several valves, with 1 ≤ x ≤ n-1, the first distributor distributes the flow of the first fuel over the n-x first flexible lines which are open for the injection thereof into the combustion zone by the rod or rods of a first fuel connected to said first open flexible lines. - a burner unit having an inlet face and an outlet face, at least one passage of combustion agent (506, 507) between the inlet face and the outlet face and at least one fuel rod passage (500, 501) between the inlet face and the outlet face, the burner unit being such that m fuel rods can simultaneously be mounted in the burner unit through the at least one fuel rod passage (500, 501), with m > 1, - n rods of a first fuel (110, 111), with n > 1, each rod of a first fuel (110, 111) able to be mounted in the or in one of the fuel rod passages (500, 501) and to be removed from said fuel rod passage (500, 501) par the inlet face du burner unit, - a combustion agent supply device able to transport a flow of combustion agent to the burner unit for the injection thereof through the at least one combustion agent passage (506, 507) in a combustion zone located downstream of the outlet face, - a first fuel supply device able to transport a flow of a first fuel from a source of first fuel to the burner unit for the injection thereof into the combustion zone through one or several fuel passages (500, 501), the first fuel supply device comprising a first supply line, a first flow meter, a first distributor and n first flexible lines (120, 121) connecting the first distributor to the n rods of a first fuel (110, 111), i. the first supply line being able to transport the flow of the first fuel from the source of first fuel to the first distributor, ii. the first flow meter being able to regulate the flow rate of the flow of the first fuel from the source of first fuel to the first distributor, iii. the first distributor being able to distribute the flow of the first fuel into n subsidiary flows over the n first flexible lines, i. the first supply line being able to transport the flow of the first fuel from the source of first fuel to the first distributor, ii. the first flow meter being able to regulate the flow rate of the flow of the first fuel from the source of first fuel to the first distributor, iii. the first distributor being able to distribute the flow of the first fuel into n subsidiary flows over the n first flexible lines, - the first fuel supply device comprises one or several valves (130, 131) making it possible to close and to open the n first flexible lines one by one in such a way that, when x of the n first flexible lines are closed by said one or several valves, with 1 ≤ x ≤ n-1, the first distributor distributes the flow of the first fuel over the n-x first flexible lines which are open for the injection thereof into the combustion zone by the rod or rods of a first fuel connected to said first open flexible lines.