Method and apparatus for melting metal
An apparatus for melting a metal load includes a furnace having a melting chamber with a hearth and a molten metal outlet. The apparatus further includes non-regenerative burners that are operative to fire into the melting chamber, and regenerative burners that also are operative to fire into the melting chamber. The method includes the steps of firing non-regenerative burners into the chamber to provide heat for melting the load, and also firing regenerative burners into the chamber to provide heat for melting the load.
1. An apparatus comprising:
a furnace having a melting chamber with a hearth and a molten metal outlet;
a plurality of non-regenerative burners, which do not have regenerative beds, that are operative to fire into the melting chamber; and
a plurality of regenerative burners, which have regenerative beds, that also are operative to fire into the melting chamber.
2. An apparatus as defined in claim 1 further comprising a reactant supply and control system including a controller that is configured to fire the burners in differing modes including a mode in which reactant streams of fuel are prevented from flowing to the regenerative burners while the non-regenerative burners are being fired.
3. An apparatus as defined in claim 1 further comprising a reactant supply and control system including a controller that is configured to fire the burners in differing modes including a mode in which regenerative burners and non-regenerative burners are fired simultaneously.
4. An apparatus as defined in claim 1 further comprising a reactant supply and control system including a controller that is configured to fire the burners in differing modes including a first mode in which only non-regenerative burners are fired, a second mode in which non-regenerative burners and regenerative burners are fired simultaneously, and a third mode in which only regenerative burners are fired.
5. An apparatus as defined in claim 4 wherein the controller is configured to provide the first mode early in an initial melting phase, to provide the second mode later in the initial melting phase, and to provide the third mode in a final melting phase following the initial melting phase.
6. An apparatus comprising:
a furnace having a melting chamber with a hearth and a molten metal outlet;
a plurality of non-regenerative burners, which do not have regenerative beds, that are operative to fire into the melting chamber;
a plurality of regenerative burners, which have regenerative beds, that also are operative to fire into the melting chamber; and
a reactant supply and control system including a controller that is configured to fire the burners in differing modes including a) a direct-fired mode in which regenerative burners are fired without exhaust cycles while non-regenerative burners also are being fired, and b) a hybrid mode in which at least two regenerative burners are fired with alternating exhaust cycles while a non-regenerative burner also is being fired.
7. An apparatus as defined in claim 6 wherein the controller is configured to change the number of non-regenerative burners that are fired in the hybrid mode.
8. An apparatus as defined in claim 7 wherein the controller is configured to decrease the number of non-regenerative burners that are fired in the hybrid mode.
9. An apparatus as defined in claim 6 wherein the controller is configured to change the number of cycled regenerative burners during the hybrid mode.
10. An apparatus as defined in claim 9 wherein the controller is configured to increase the number of cycled regenerative burners during the hybrid mode.
11. An apparatus as defined in claim 6 wherein the controller is configured to provide the direct firing mode early in an initial melting phase, and to provide the hybrid mode later in the initial melting phase.
12. An apparatus as defined in claim 11 wherein the differing modes further include a fully regenerative mode in which no non-regenerative burners are fired, and regenerative burners are fired in pairs with alternating exhaust cycles.
13. An apparatus as defined in claim 12 wherein the controller is configured to provide the fully regenerative mode in a final melting phase following the initial melting phase.
14. An apparatus as defined in claim 1 wherein the non-regenerative burners are arranged in opposed pairs to fire into the melting chamber in opposite directions.
15. An apparatus as defined in claim 1 wherein the regenerative and non-regenerative burners have alternating positions in an array extending along a wall of the melting chamber.
16. An apparatus as defined in claim 15 wherein the melting chamber has a circular configuration with a cylindrical side wall, and the array of regenerative and non-regenerative burners extends around the side wall.
17. An apparatus as defined in claim 6 wherein the non-regenerative burners are arranged in opposed pairs to fire into the melting chamber in opposite directions.
18. An apparatus as defined in claim 6 wherein the regenerative and non-regenerative burners have alternating positions in an array extending along a wall of the melting chamber.
19. An apparatus as defined in claim 18 wherein the melting chamber has a circular configuration with a cylindrical side wall, and the array of regenerative and non-regenerative burners extends around the side wall.