STARTUP METHOD AND MECHANISM FOR A BURNER HAVING A PERFORATED FLAME HOLDER
According to an embodiment, a combustion system is provided, which includes a nozzle configured to emit a diverging fuel flow, a flame holder positioned in the path of the fuel flow and that includes a plurality of apertures extending therethrough, and a preheat mechanism configured to heat the flame to a temperature exceeding a startup temperature threshold.
1 . A burner, comprising:
a primary nozzle having a longitudinal axis and configured to emit a fuel flow;
a primary flame holder having first and second faces and a plurality of apertures extending through the flame holder from the first face to the second face, positioned with the first face toward the nozzle and intersecting the longitudinal axis of the nozzle; and
a preheat mechanism configured to preheat the primary flame holder.
2 . The burner of claim 1 , wherein the preheat mechanism includes an electrically resistive element.
3 . The burner of claim 2 , wherein the electrically resistive element is integral with the primary flame holder.
4 . The burner of claim 2 , wherein the electrically resistive element is coupled to one of the first and second faces of the primary flame holder.
5 . The burner of claim 2 , wherein the electrically resistive element is coupled to a lateral surface of the primary flame holder.
6 . The burner of claim 2 , wherein the electrically resistive element is interleaved through a number of the plurality of apertures of the primary flame holder.
7 . The burner of claim 2 , wherein the electrically resistive element is encapsulated by the primary flame holder.
8 . The burner of claim 2 , wherein the electrically resistive element is a component of a material of the primary flame holder.
9 . The burner of claim 1 , wherein the preheat mechanism includes an electrically inductive element.
10 . The burner of claim 9 , wherein the electrically inductive element is integral with the primary flame holder.
11 . The burner of claim 9 , wherein the electrically inductive element is coupled to one of the first and second faces of the primary flame holder.
12 . The burner of claim 9 , wherein the electrically inductive element is coupled to a lateral surface of the primary flame holder.
13 . The burner of claim 9 , wherein the electrically inductive element is interleaved through a number of the plurality of apertures of the primary flame holder.
14 . The burner of claim 9 , wherein the electrically inductive element is encapsulated by the primary flame holder.
15 . The burner of claim 9 , wherein the electrically inductive element is a component of a material of the primary flame holder.
16 . The burner of claim 1 , wherein the preheat mechanism includes a preheat nozzle configured to support a flame in a position between the primary nozzle and the first face of the primary flame holder.
17 . The burner of claim 11 , wherein the secondary flame holder has a toroid shape.
18 . The burner of claim 10 , wherein one of the first and second electrodes is integral with the primary flame holder.
19 . The burner of claim 10 , wherein one of the first and second electrodes is movable between an extended position and a retracted position.
20 . The burner of claim 9 , wherein the secondary flame holder is configured to introduce turbulence into the fuel flow emitted by the nozzle.
21 . The burner of claim 16 , wherein the primary nozzle is the preheat nozzle, and wherein the primary nozzle is movable between a preheat position and an operative position.
22 . The burner of claim 21 , wherein the preheat mechanism includes a mechanism configured to move the primary nozzle between the preheat position and the operative position.
23 . The burner of claim 16 , wherein the primary nozzle is the preheat nozzle, and wherein the primary flame holder is movable between a preheat position and an operative position.
24 . The burner of claim 16 , wherein the preheat nozzle is movable between a preheat position and an idle position.
25 . The burner of claim 1 , wherein the preheat mechanism includes an energizing mechanism configured to transmit an energy emission to impinge on a surface of the primary flame holder.
26 . The burner of claim 25 , wherein the energizing mechanism includes a laser emitter.
27 . The burner of claim 25 , wherein the energizing mechanism includes a microwave emitter.
28 . The burner of claim 1 , comprising a controller configured to switch the burner from a preheat condition to an operative condition.
29 . A method, comprising:
performing a burner startup procedure, including applying thermal energy to a primary flame holder;
terminating the burner startup procedure after a temperature of a portion of the primary flame holder is above a startup temperature threshold;
emitting a flow of fuel from a primary nozzle at an operational rate; and
supporting a flame within a plurality of apertures extending through the primary flame holder.
30 . The method of claim 29 , wherein the applying thermal energy includes generating heat by applying an electrical potential across an electrically resistive element, and applying the heat to the primary flame holder.
31 . The method of claim 30 , wherein the applying an electrical potential includes applying an electrical potential across an electrically resistive element that is integral with the primary flame holder.
32 . The method of claim 30 , wherein the applying an electrical potential includes applying an electrical potential across an electrically resistive element that is in physical contact with the primary flame holder.
33 . The method of claim 30 , wherein the applying an electrical potential includes applying an electrical potential across an electrically resistive element that is interleaved through a number of the plurality of apertures of the primary flame holder.
34 . The method of claim 30 , comprising:
maintaining the primary nozzle in an off condition until the temperature of the portion of the primary flame holder is substantially at the startup temperature threshold; and
performing the emitting a flow of fuel and the terminating the burner startup procedure substantially simultaneously.
35 . The method of claim 34 wherein the performing a burner startup procedure further includes holding the primary nozzle in a startup position and emitting a flow of fuel from the primary nozzle at a startup rate, the startup rate being sufficiently low as to enable a stable flame within the fuel flow, and wherein the terminating the burner startup procedure includes moving the primary nozzle from the startup position to a operational position.
36 . The method of claim 34 wherein the performing a burner startup procedure further includes holding the primary flame holder in a startup position and emitting a flow of fuel from the primary nozzle at a startup rate, the startup rate being sufficiently low as to enable a stable flame within the fuel flow, and wherein the terminating the burner startup procedure includes moving the primary flame holder from the startup position to a operational position.
37 . The method of claim 29 wherein the applying thermal energy to a primary flame holder includes applying an electrical potential across first and second electrodes positioned to apply electrical energy to a flame supported by the primary nozzle.
38 . The method of claim 29 wherein the applying thermal energy to a primary flame holder includes:
applying an electrical charge having a first polarity to a flame supported by the primary nozzle; and
holding a portion of the flame near the primary flame holder by applying a voltage having a second polarity, opposite the first polarity, to an electrode.
39 . The method of claim 37 wherein the applying a voltage to an electrode includes applying the voltage to an electrode positioned on a face of the primary flame holder.
40 . The method of claim 37 wherein the terminating the burner startup procedure includes retracting the electrode from a position between the primary nozzle and the primary flame holder.
41 . The method of claim 29 wherein the applying thermal energy to a primary flame holder includes directing a laser beam onto a surface of the primary flame holder.
42 . The method of claim 29 wherein the applying thermal energy to a primary flame holder includes directing a microwave emission onto a surface of the primary flame holder.
43 . The method of claim 29 , comprising detecting a temperature of the portion of the primary flame holder.