Methods of upgrading a conventional combustion system to include a perforated flame holder
Embodiments disclosed herein are directed to methods of upgrading a conventional combustion system into an upgraded combustion system that includes a perforated flame holder. For example, the perforated flame holder may improve operational efficiency of the combustion system and/or reduce pollutants such as NO x output by the upgraded combustion system.
1. A method of upgrading a conventional combustion system having a combustion chamber defined by a combustion pipe disposed in a shell configured to hold water, the method comprising:
removing a first fuel nozzle assembly from the shell of the conventional combustion system, the first nozzle assembly including one or more vortex generating structures configured to promote combustion in and/or near an output of the first fuel nozzle assembly;
installing a flame holder assembly into the combustion chamber, the flame holder assembly including a refractory body and a flame holder mounted to a support structure, the flame holder assembly configured to produce a flame at least temporarily held by the flame holder; and
installing a second fuel nozzle assembly at least partially into the conventional combustion system including securing a base of the second fuel nozzle assembly to the shell of the conventional combustion system, the support structure being secured to the base with the flame holder spaced from the base, wherein the second fuel nozzle assembly does not include one or more vortex generating structures configured to promote combustion in and/or near an output of the second fuel nozzle assembly.
2. The method of claim 1 wherein the second fuel nozzle assembly is configured to deliver unburned fuel and oxidant to the flame holder.
3. The method of claim 1 wherein the one or more vortex generating structures include swirl vanes.
4. The method of claim 1 further comprising modifying the first fuel nozzle assembly to form the second fuel nozzle assembly.
5. The method of claim 1 , further comprising installing a preheating device that is configured to heat the flame holder to a temperature sufficient to cause a combustion reaction in and/or near the flame holder.
6. The method of claim 5 wherein the preheating device includes an electrical resistance heater.
7. The method of claim 1 wherein the support structure is configured such that the flame holder is positioned at a selected distance from the second fuel nozzle assembly inside the combustion chamber.
8. The method of claim 1 wherein the support structure includes a plurality of legs coupled to a base, the base configured to attach to a front wall of the conventional combustion system and further configured to receive the second fuel nozzle assembly, the base including an outer tube for receiving an oxidant.
9. The method of claim 8 , further comprising selecting a length of the plurality of legs such that the flame holder is positioned at or near a centroid or a terminal end of a flame output by the first fuel nozzle assembly in the conventional combustion system prior to the conventional combustion system being upgraded with the flame holder assembly.
10. The method of claim 1 , further comprising removing a burner tile from a position proximate to the first fuel nozzle assembly.
11. The method of claim 1 , further comprising:
determining a centroid or a terminal end of a flame output by the first fuel nozzle assembly in the combustion chamber prior to removing a first fuel nozzle assembly from the conventional combustion system; and
positioning the flame holder to be at or near the centroid or the terminal end of the flame output by the first fuel nozzle assembly in the conventional combustion system prior to the conventional combustion system being upgraded with the flame holder assembly.
12. The method of claim 1 , wherein the refractory body is secured to the support structure opposite to the base and the flame holder is mounted to the support structure spaced from the refractory body between the refractory body and the base.
13. The method of claim 12 , wherein the flame holder assembly includes thermal insulation thermally coupled to the support structure at least proximate to the refractory body.
14. The method of claim 1 , wherein the flame holder is adjustable between (1) a first position aligned with an opening in the base providing fluid communication between the second fuel nozzle assembly and the flame holder assembly and (2) a retracted second position that is offset from opening in the base.
15. The method of claim 14 , wherein the flame holder is configured to hold the start-up flame until the flame holder assembly reaches a predetermined operating temperature and not hold the start-up flame after the flame holder assembly reaches the predetermined operating temperature.
16. The method of claim 1 , wherein the refractory body includes at least one of cordierite or mullite.