Burner with alternate modes for flexible operation

Combustion apparatus comprising:

• a first burner comprising
• a first central conduit having a central axis and terminating in a first central outlet which opens into a first downstream space;
• a first annular conduit surrounding the first central conduit, the first annular conduit and the first central conduit being separated by an annular wall, wherein the first annular conduit terminates in an outlet which opens into said first downstream space, wherein the first annular conduit comprises a nozzle plate across the outlet of the first annular conduit, wherein the nozzle plate comprises a plurality of orifices that extend through the nozzle plate from within the first annular conduit to the first downstream space;
• wherein the first central conduit and the first annular conduit are each connected to a source of a first reactant through mechanism with which the flow of the first reactant from the source thereof into the first central conduit and the flow of the first reactant from the source thereof into the first annular conduit can be controlled;
• and
• a second annular conduit surrounding the first annular conduit and terminating in a second annular outlet which opens into said first downstream space, wherein the second annular conduit is connected to a source of a second reactant through mechanism with which the flow of the second reactant from the source thereof into the second annular conduit can be controlled;
• and
• a second burner comprising
• a second central conduit having a central axis and terminating in a second central outlet which opens into a second downstream space;
• a third annular conduit surrounding the second central conduit, the third annular conduit and the second central conduit being separated by an annular wall, wherein the third annular conduit terminates in an outlet which opens into said second downstream space, wherein the third annular conduit comprises a nozzle plate across the outlet of the third annular conduit, wherein the nozzle plate comprises a plurality of orifices that extend through the nozzle plate from within the third annular conduit to the second downstream space;
• wherein the second central conduit and the third annular conduit are connected to a source of said first reactant through mechanism with which the flow of the first reactant from the source thereof into the second central conduit and the flow of the first reactant from the source thereof into the third annular conduit can be controlled;
• and
• a fourth annular conduit surrounding the third annular conduit and terminating in a fourth annular outlet which opens into said second downstream space, wherein the fourth annular conduit is connected to a source of said second reactant through mechanism with which the flow of the second reactant from the source thereof into the fourth annular conduit can be controlled;
• wherein the central axis of the first central conduit is above the central axis of the second central conduit;
• wherein one of the first and second reactants comprises fuel and the other of the first and second reactants is oxidant that comprises oxygen.

A method of combustion in a furnace, comprising:

• providing combustion apparatus that comprises
• a plurality of first burners comprising
• a first central conduit having a central axis and terminating in a first central outlet which opens into a first downstream space;
• a first annular conduit surrounding the first central conduit, the first annular conduit and the first central conduit being separated by an annular wall, wherein the first annular conduit terminates in an outlet which opens into said first downstream space, wherein the first annular conduit comprises a nozzle plate across the outlet of the first annular conduit, wherein the nozzle plate comprises a plurality of orifices that extend through the nozzle plate from within the first annular conduit to the first downstream space;
• wherein the first central conduit and the first annular conduit are each connected to a source of a first reactant through mechanism with which the flow of the first reactant from the source thereof into the first central conduit and the flow of the first reactant from the source thereof into the first annular conduit can be controlled;
• and
• a second annular conduit surrounding the first annular conduit and terminating in a second annular outlet which opens into said first downstream space, wherein the second annular conduit is connected to a source of a second reactant through mechanism with which the flow of the second reactant from the source thereof into the second annular conduit can be controlled;
• and
• a plurality of second burners comprising
• a second central conduit having a central axis and terminating in a second central outlet which opens into a second downstream space;
• a third annular conduit surrounding the second central conduit, the third annular conduit and the second central conduit being separated by an annular wall, wherein the third annular conduit terminates in an outlet which opens into said second downstream space, wherein the third annular conduit comprises a nozzle plate across the outlet of the third annular conduit, wherein the nozzle plate comprises a plurality of orifices that extend through the nozzle plate from within the third annular conduit to the second downstream space;
• wherein the second central conduit and the third annular conduit are connected to a source of said first reactant through mechanism with which the flow of the first reactant from the source thereof into the second central conduit and the flow of the first reactant from the source thereof into the third annular conduit can be controlled;
• and
• a fourth annular conduit surrounding the third annular conduit and terminating in a fourth annular outlet which opens into said second downstream space, wherein the fourth annular conduit is connected to a source of said second reactant through mechanism with which the flow of the second reactant from the source thereof into the fourth annular conduit can be controlled;
• wherein the central axes of all of said first burners are above the central axes of all of said second burners;
• wherein one of the first and second reactants comprises fuel and the other of the first and second reactants is oxidant that comprises oxygen;
• feeding fuel from the first central outlets and from the first annular conduit nozzle plates of each of said first burners into a first downstream space within said furnace;
• feeding oxidant from the second annular outlets of each of said first burners into said first downstream space, and
• combusting said fuel fed from the first central outlets and from the first annular conduit nozzle plates with said oxidant fed from the second annular outlets, to create a mixture of products of said combustion which pass into said first downstream space;
• while
• feeding fuel from the second central outlets and from the third annular conduit nozzle plates of each of said second burners into a second downstream space within said furnace;
• feeding oxidant from the fourth annular outlets of each of said second burners into said second downstream space, and
• combusting said fuel fed from the second central outlets and from the third annular conduit nozzle plates with said oxidant fed from the fourth annular outlets, to create a mixture of products of said combustion which pass into said second downstream space.