LOW NOx EMISSION BURNER FOR FIRING LIQUID FUELS OR FUEL GAS AND METHOD OF OPERATION

Abstract

A liquid fuel or hybrid fuel burner and method of operating the burner are described. The combustion air and/or NOx reducing medium are introduced at more than one location in the burner. A portion of the combustion air and the NOx reducing medium can be injected into the primary combustion zone through the NOx reducing medium conduit which surrounds the fuel injector which injects atomized liquid fuel or fuel gas into the primary combustion zone. Another portion of the combustion air and the NOx reducing medium can be introduced into the primary combustion zone through a passage in the burner tile surrounding the NOx reducing medium conduit. A third portion of NOx reducing medium can be injected outside the burner tile. NOx reducing medium can be introduced into any combination of the three locations.

Claims

1. A liquid fuel or hybrid fuel burner comprising: a plenum having a combustion air inlet; a burner tile connected to the plenum, the burner tile forming a primary combustion zone; a fuel injector positioned in the plenum, the fuel injector comprising an inlet and an outlet, the outlet positioned in the primary combustion zone; a passage through the burner tile from the plenum to the primary combustion zone for combustion air and NOx reducing medium; a primary fuel gas conduit comprising a primary fuel gas inlet and a primary fuel gas outlet, the primary fuel gas outlet positioned in the primary combustion zone; and a NOx reducing medium inlet into the plenum, or a NOx reducing medium conduit positioned in the plenum, the NOx reducing medium conduit comprising a NOx reducing medium conduit inlet and a NOx reducing medium conduit outlet, the NOx reducing medium conduit outlet positioned in the primary combustion zone, wherein the fuel injector is positioned in the NOx reducing medium conduit, or a staged NOx reducing medium conduit comprising a staged NOx reducing medium inlet and a staged NOx reducing medium outlet, the staged NOx reducing medium outlet positioned outside the burner tile, or combinations thereof.

2. The burner of claim 1 wherein NOx reducing medium conduit further comprises a combustion air inlet located in the plenum.

3. The burner of claim 1 further comprising: a secondary fuel gas conduit comprising a secondary fuel gas inlet and a secondary fuel gas outlet, the secondary fuel gas outlet positioned outside the burner tile.

4. The burner of claim 3 wherein the secondary fuel gas conduit is connected to the primary fuel gas conduit.

5. The burner of claim 1 wherein the NOx reducing medium conduit and the fuel injector are in a concentric arrangement.

6. The burner of claim 1 further comprising a flame stabilization device in the primary combustion zone.

7. The burner of claim 6 wherein the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof.

8. The burner of claim 1 wherein the passage through the burner tile surrounds the NOx reducing medium conduit.

9. The burner of claim 1 wherein the passage through the burner tile and the NOx reducing medium conduit are in a concentric arrangement.

10. A method of reducing production of NOx gases at a burner comprising: injecting one or more of a liquid fuel, or a fuel gas, or an atomizing medium from a fuel injector into a primary combustion zone defined by a burner tile forming an atomized liquid fuel or fuel gas or both; injecting a first portion of NOx reducing medium into the primary combustion zone from a NOx reducing medium conduit surrounding the fuel injector, or injecting a second portion of NOx reducing medium into the primary combustion zone through a passage in the burner tile, or injecting a third portion of NOx reducing medium outside the burner tile, or combinations thereof; and injecting combustion air into the primary combustion zone through the passage in the burner tile, whereby the combustion air and the atomized liquid fuel or fuel gas or both react and produce a flame in the primary combustion zone.

11. The method of claim 10 further comprising: passing a first portion of the combustion air into the NOx reducing medium conduit; and wherein injecting the first portion of the NOx reducing medium into the primary combustion zone comprises injecting the first portion of the NOx reducing medium and the first portion of the combustion air into the primary combustion zone.

12. The method of claim 10 further comprising; injecting primary fuel gas through a primary fuel gas outlet into the primary combustion zone wherein the combustion air and the primary fuel gas react and produce a flame inside the primary combustion zone.

13. The method of claim 10 further comprising; injecting secondary fuel gas through a secondary fuel gas outlet into an area outside the burner tile wherein the combustion air from the passage and the secondary fuel gas react and produce a flame outside the primary combustion zone.

14. The method of claim 10 wherein the atomizing medium comprises steam, air, nitrogen, fuel gas, or combinations thereof.

15. The method of claim 10 further comprising; stabilizing the flame with a flame stabilization device in the primary combustion zone.

16. The method of claim 15 wherein the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof.

17. The method of claim 10 wherein injecting the combustion air and the second portion of NOx reducing medium into the primary combustion zone through the passage in the burner tile comprises introducing the combustion air and the second portion of NOx reducing medium into a plenum connected to the burner tile and wherein the combustion air and the second portion of NOx reducing medium pass from the plenum through the passage in the burner tile to the primary combustion zone.

18. The method of claim 10 wherein the passage in the burner tile surrounds the NOx reducing medium conduit.

19. The method of claim 10 wherein the first portion of NOx reducing medium, or the second portion of NOx reducing medium, or the third portion of the NOx reducing medium, or combinations thereof comprise: flue gas from a combustion zone; flue gas from the exhaust of a heater, a boiler, or a furnace; steam; nitrogen; carbon dioxide; or combinations thereof.

20. The method of claim 10 further comprising: monitoring at least one NOx value for the flame; and adjusting a flowrate of the first portion of NOx reducing medium, or the second portion of NOx reducing medium, or the third portion of the NOx reducing medium, or combinations thereof based on the at least one NOx value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a front section view of one embodiment of the burner of the present invention.

[0010] FIG. 2 is a left section view of the burner of FIG. 1.

[0011] FIG. 3 is a plan view of the burner of FIG. 1.

[0012] FIG. 4 is a front section view of another embodiment of the burner of the present invention.

[0013] FIG. 5 is a left section view of the burner of FIG. 4.

[0014] FIG. 6 is a plan view of the burner of FIG. 4.

DESCRIPTION

[0015] The burner of the present invention delivers low NOx emissions for processes involving the combustion of liquid fuel or fuel gas which it achieves through the targeted injection of a NOx reducing medium. The low NOx emissions may reduce permitting difficulties and may reduce or eliminate the need to purchase offsetting NOx credits (if available).

[0016] A conventional liquid fuel burner may comprise a centrally located fuel injector (also known as an oil gun when liquid fuels are used). Liquid fuels include, but are not limited to, hydrocarbons which are normally liquid at ambient conditions including naphtha, alcohols, diesel fuel, bunker fuel oil, distillate oil, crude oil, and the like.

[0017] Liquid fuel must be atomized and changed through a phase shift to gaseous form by the atomizing medium in order to burn. The liquid fuel injector is a device for mixing the liquid fuel with the atomizing medium. The atomizing medium may be steam, air, nitrogen, fuel gas, and the like. Steam is the most commonly used atomizing medium, followed by air.

[0018] When fuel gas is used, the atomizing medium may not be needed, although it can be used if desired.

[0019] The fuel injector is often centrally located in a concentric assemblage of cylinders which make up the burner assembly. The central fuel injector is often surrounded by or directly adjacent to a flame stabilization device such as an oil tile, flame diffusor, flame holder, bluff body or other devices used to stabilize the base of the flame front. The flame is established downstream of the fuel injector on or near the flame stabilization device. This is the injection point for the liquid fuel and the atomizing medium or the fuel gas optionally with the atomizing medium. A portion of the combustion air is directed into and around the fuel injector and the flame stabilization device. The remaining portion of the combustion air is injected around and outside of the centrally located fuel injector and flame stabilization device. In some cases, a portion of the combustion air is injected at the periphery of the burner assembly for delayed mixing with the fuel. This periphery air injection is termed staged air and is used to lower NOx emissions by delaying combustion and by reducing the partial pressure of oxygen immediately surrounding the fuel injector. Combustion air means any oxygen-containing gas including, but not limited to air, oxygen, flue gas, and the like.

[0020] High partial pressure of oxygen produces higher NOx emissions. In order to reduce the partial pressure, fuel gas may be injected outside of the fuel injector (primary fuel gas) or at the outer periphery of the burner tile (staged fuel gas).

[0021] When gas firing capability is included in a liquid fuel burner, this is termed a combination liquid/gas burner, a dual fuel burner, or a hybrid fuel burner. The combination burner can fire 100% liquid fuel, 100% gaseous fuel, or any proportion of fuel gas and liquid fuel. The burner of the present invention can be incorporated in a combination liquid/gas fuel burner design.

[0022] In advanced low NOx burners, as more fully described in U.S. Pat. No. 11,649,960 B2, a NOx reducing medium, such as steam, flue gas from a combustion zone or heater exhaust, nitrogen, carbon dioxide, or other inert media is introduced in specific targeted locations in the burner assembly.

[0023] In the present invention, combustion air and/or a NOx reducing medium are introduced at more than one location in the burner. A portion of the combustion air and the NOx reducing medium can be injected into the primary combustion zone through the NOx reducing medium conduit which surrounds the fuel injector which injects atomized liquid fuel or fuel gas into the primary combustion zone. Another portion of the combustion air and the NOx reducing medium can be introduced into the primary combustion zone through a passage in the burner tile surrounding the NOx reducing medium conduit.

[0024] The burner comprises a plenum connected to a burner tile. The burner tile defines a primary combustion zone. The plenum has a NOx reducing medium inlet and a combustion air inlet. There is a passage through the burner tile from the plenum to the primary combustion zone. The burner includes a NOx reducing medium conduit surrounding a fuel injector, and the outlet of the NOx reducing medium conduit and the outlet of the fuel injector are in the primary combustion zone. The burner also includes a primary fuel gas conduit with one or more primary fuel gas outlet(s) which are utilized when the burner is used in a dual fuel arrangement. The primary fuel gas outlet(s) are in the primary combustion zone. In some instances, the burner may optionally also include one or more staged fuel gas conduit(s) with one or more staged fuel gas outlet(s). The staged fuel gas outlet(s) are located outside the burner tile. The staged fuel gas conduit(s) can be connected to the primary fuel gas conduit to provide fuel gas to the staged fuel gas outlet(s).

[0025] The NOx reducing medium is injected into the primary combustion zone from two places. A first portion of the NOx reducing medium enters the inlet of the NOx reducing medium conduit. A first portion of the combustion air is introduced into the NOx reducing medium conduit from the plenum through one or more combustion air inlet(s) in the NOx reducing medium conduit. The first portion of the NOx reducing medium and the first portion of the combustion air are mixed in the NOx reducing medium conduit and introduced into the primary combustion zone through the outlet of the NOx reducing medium conduit. The combustion air and the atomized liquid fuel or the fuel gas react and produce a flame in the primary combustion zone.

[0026] A second portion of the NOx reducing medium and a second portion of the combustion air is introduced into the primary combustion zone through the passage in the burner tile. The second portion of the NOx reducing medium is introduced into the plenum through a NOx reducing medium inlet and the combustion air is introduced into the plenum through a combustion air inlet. The first portion of the combustion air from the plenum enters the NOx reducing medium conduit through one or more combustion air inlet(s) (e.g., openings or holes) in the conduit, as discussed above. The remainder of the combustion air and the second portion NOx reducing medium flows through the passage in the burner tile into the primary combustion zone.

[0027] A third portion of the NOx reducing medium can be injected outside the burner tile in staged NOx reducing medium outlets. The third portion of the NOx reducing medium can be introduced into the plenum through a second of the NOx reducing medium inlet. The third portion of the of the NOx reducing medium flows through a second of the NOx reducing medium conduit outside of the burner tile.

[0028] The NOx reducing medium can be injected into any combination of one, two, or all three of these locations.

[0029] The primary fuel gas from the primary fuel gas outlet reacts with the combustion air in the primary combustion zone and produces a flame.

[0030] There are one or more secondary fuel gas conduit(s) located outside the burner tile. The secondary fuel gas conduit(s) may be connected to the primary fuel gas conduit, or they can be separate. The secondary fuel gas from the secondary fuel gas outlet(s) reacts with combustion air downstream of the primary combustion zone.

[0031] The fuel injector, the NOx reducing medium conduit, and the passage in the burner tile are typically in a concentric arrangement, although this is not required.

[0032] The burner may include a flame stabilization device. Any suitable flame stabilization device can be used. Suitable flame stabilization devices include, but are not limited to, oil tiles, flame diffusers, flame holders, bluff bodies, or combinations thereof.

[0033] Another aspect of the invention is a method of reducing production of NOx gases at a burner. In one embodiment, the method comprises injecting a liquid fuel and an atomizing medium, or a fuel gas and optionally an atomizing medium from a fuel injector into a primary combustion zone defined by a burner tile forming an atomized liquid fuel, or a fuel gas, or an atomized fuel gas. A first portion of NOx reducing medium is injected into the primary combustion zone from a NOx reducing medium conduit surrounding the fuel injector. Combustion air and a second portion of NOx reducing medium is injected into the primary combustion zone through a passage in the burner tile. The combustion air and the atomized liquid fuel react and produce a flame in the primary combustion zone.

[0034] In some embodiments, the method further comprises passing a portion of the combustion air into the NOx reducing medium conduit. In this case, injecting the first portion of the NOx reducing medium into the primary combustion zone comprises injecting the first portion of the NOx reducing medium and the first portion of the combustion air into the primary combustion zone.

[0035] In some embodiments, the method further comprises injecting primary fuel gas through a primary fuel gas outlet into the primary combustion zone wherein the combustion air and the primary fuel gas react and produce a flame inside the primary combustion zone.

[0036] In some embodiments, the method further comprises injecting secondary fuel gas through a secondary fuel gas outlet into an area outside the burner tile wherein the combustion air from the passage and the secondary fuel gas react and produce a flame outside the primary combustion zone.

[0037] In some embodiments, the atomizing medium comprises steam, air, nitrogen, fuel gas, or combinations thereof.

[0038] In some embodiments, the method further comprises stabilizing the flame with a flame stabilization device in the primary combustion zone. In some embodiments, the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof.

[0039] In some embodiments, injecting the combustion air and the second portion of NOx reducing medium into the primary combustion zone through the passage in the burner tile comprises introducing the combustion air and the second portion of NOx reducing medium into a plenum connected to the burner tile and wherein the combustion air and the second portion of NOx reducing medium pass from the plenum through the passage in the burner tile to the primary combustion zone.

[0040] In some embodiments, the passage in the burner tile surrounds the NOx reducing medium conduit.

[0041] In some embodiments, the first portion of NOx reducing medium, or the second portion of NOx reducing medium, or both comprise: flue gas from a combustion zone; flue gas from the exhaust of a heater, a boiler, or a furnace; steam; nitrogen; carbon dioxide; or combinations thereof.

[0042] In some embodiments, the method further comprises: monitoring at least one NOx value for the flame; and adjusting a flowrate of the first portion of NOx reducing medium, the second portion of NOx reducing medium, or both based on the at least one NOx value.

[0043] Based on operational needs and NOx reduction demand, a control system is designed to modulate the proportion of NOx reducing media directed to the any one of these locations, primary, secondary, or periphery. Passageways between the primary, secondary, or periphery injection locations may provide for the communication and passage of combustion air and/or NOx reducing media between the primary, secondary or periphery areas.

[0044] By designing for and actively controlling the injection rates, locations, localized stoichiometry, and NOx reducing medium introduced to the combustion process, the flame, the NOx production can be mitigated to extremely low values, e.g., less than 10 ppmvd with relatively modest amounts of NOx reducing media, such as flue gas. By designing for and actively controlling the injection rates, locations, localized stoichiometry, and NOx reducing medium introduced to the combustion process, the flame and the NOx formation can be mitigated while maintaining good burner and flame stability and continuous operation.

[0045] While the lowest NOx emissions may be produced when the burner is receiving highest rates of NOx reducing medium, this may also be the incipient point of burner instability. This incipient instability can be detected by a high-speed pressure transmitter and associated instability detection software, similar to that described in U.S. Pat. No. 7,950,919. However, unlike U.S. Pat. No. 7,950,919 where principally combustion chamber oxygen is controlled and adjusted to react to instability, in this invention, the rate and location of NOx reducing medium can be controlled.

[0046] Generally, the NOx emissions from the heater may be monitored along with the stack oxygen and the combustion chamber pressure or draft. The rate, the amount of NOx reducing medium delivered, or both may be increased at the desired locations in the flame zone until the required NOx reduction is achieved. Once the desired NOx level is achieved, no additional NOx reducing medium may be introduced. If the burner becomes unstable, the rate and/or location of the NOx reducing medium can be controlled or the excess air, oxygen levels adjusted as suggested in U.S. Pat. No. 7,950,919 until burner stability is achieved.

[0047] It is further contemplated that visual field or infrared cameras may be used to monitor flame stability and quality aspects using artificial intelligence, AI, such as described in U.S. Patent Publ. No. 2020/0386404 (incorporated herein by reference). When instabilities or other anomalies in the flame image are detected with the AI, the amount and location of the NOx reducing medium and/or other control aspects of the heater controls system, such as excess oxygen, can be adjusted and controlled to simultaneously deliver the lowest level of NOx (or at least the required level) with good burner flame stability.

[0048] If there is a loss of NOx reducing medium at any time, the present burner will still work safely as a conventional low NOx burner. The NOx emissions may increase, but the burner will otherwise remain stable and continue to deliver heat reliably to the process in the heater, boiler or furnace. Further, the burner will operate, in the view of the burner operator, just as conventional burners operate with no special operational issues.

[0049] The introduction of NOx reducing medium may be by fixed static control devices or by automated computer control. Therefore, the burner operates, to the point of view of the operator, conventionally with draft and oxygen control as prescribed in API Recommended Practice 535, Third Edition, May 2014, Burners for Fired Heaters in General Refinery Service. Namely, draft and oxygen are controlled with the stack damper and burner air inlet register and/or the induced draft fan and forced draft fan control settings.

[0050] Process heaters are direct fired heaters, which are used mainly to heat process fluids to temperatures of more than 204 C. in the radiation and convection sections. The typical flue gas temperature entering the convection section is more than 815 C.; this temperature may vary with various heater designs and capacities.

[0051] Combustion air contains approximately 21% O.sub.2 and 78% N.sub.2 and is supplied to the burner to provide the oxidizing component (O.sub.2) required in the combustion process. Nitrogen plays no part in the combustion of fuel gas and would, ideally, pass through the burner without reacting.

[0052] However, there are three primary processes that create NOx during fuel gas combustion: thermal NOx, which is temperature dependent, fuel NOx, which is fuel-bound nitrogen and local O.sub.2, and prompt NOx, which is not of concern here.

[0053] Thermal NOx is formed at very high temperatures and is a result of the oxidation of nitrogen found in combustion air. Thermal NOx is the predominant type of NOx generated during combustion of natural gas and is a function of the temperature and residence time of the nitrogen at that temperature. The higher the temperature of the flame, the greater the formation of thermal NOx.

[0054] The primary focus of a control system for this invention is to reduce the amount of thermal NOx produced. The levels of excess air, the temperature of the air, and the way the air is mixed with the gas will affect the production of NOx.

[0055] The targeted De-NOx gas injection (TDGi) system includes the low NOx burner described above, a TDGi blower with an automated inlet isolation valve and manual outlet valves, instrumentation (e.g., flow meters, oxygen meters, temperature and pressure sensors and transmitters, and the like), and a variable frequency drive (VFD) control system. This unique design will utilize a TDGi technique to reduce the NOx emissions significantly.

[0056] The flame temperature may be reduced to lessen NOx production by adding a non-reactive gas into the burner. Suitable non-reactive gases include, but are not limited to, carbon dioxide, nitrogen, steam, flue gas, other inert gas, or combinations thereof.

[0057] One source for the non-reactive gas is a flue gas that, after the combustion chamber, will be inert and have a temperature substantially lower than the burner flame temperature.

[0058] The TDGi control system (TDGiCS) provides orderly and safe startup, operation, and shutdown of the TDGi system. The design of the TDGi incorporates blowers, isolation valves, critical analyzer, and sensors to execute the Start/Stop/Shutdown sequence of the TDGi. All necessary permissive, sequence status, and alarms related to TDGi can be displayed on an interface on a TDGi panel located in the field.

[0059] Prior to start up, the operator should ensure that all utilities (instrument air, power, etc.,) are available to the system. Low point drains should be drained to remove any condensate/liquid in the lower part of the TDGi ducting, and when drainage is completed, drain valves should be closed before starting operation of the TDGi system. Lastly, it should be verified that no TDGi related alarm conditions exist in the distributed control system (DCS).

[0060] The system should be purged to remove flammable vapors and gases that may have entered any portion of the system volume (e.g., the process Heater, the TGDi ducting section to stack exit, etc.) during the shutdown period. The process heater purging should be completed before starting TDGi purging.

[0061] When the interlocks are satisfied (the TDGi fan inlet block valve is closed and the TDGi fan should not be running), the start of the process heater purge sequence can be performed. The TDGi purge sequence can then be initiated. The purge time is set to ensure that at least eight (8) volume changes through the TDGi system have occurred.

[0062] The TDGi Process Control Loop shall be allowed to operate only if all the following safety interlocks are satisfied: the process heater fuel gas pressure is more than a first predetermined value and less than a second predetermined value; the process heater firebox temperature is more than a first predetermined value and less than a second predetermined value; the process heater firebox O.sub.2 is more than 0.5% and less than an O.sub.2 predetermined value; the TDGi total flow less than a predetermined value.

[0063] If all the above interlocks are satisfied, the flow controllers will be released to automatic mode, i.e., loop control operation. If any of the above interlocks are not satisfied, the TDGi will go to shutdown mode.

[0064] For the summation of stoichiometric air to fuel ratio for each fuel components and multiply that by max heat release to get the stoichiometric air volume. This is the dry volume of air without excess air. To include water, multiply the dry volume air with lb of water to lb of air ratio. This is the stoichiometric wet air volume.

[0065] The excess air ratio is multiplied with the stoichiometric wet air volume to get the combustion air flow. To get the final combustion air, this calculation is performed and and summed for all fuels to the heater.

[0066] The total stack flow is the total combustion air flow plus the total fuel flow.

[0067] The TDGi NOx controller remote set point calculation (to calculate the demand for TDGi total flow) is the TDGi Ratio x the total stack flow. The TDGi ratio is typically in the range of 0.06 to 0.08.

[0068] The TDGi total flow is set as the process variable (PV) for the TDGi NOx Controller. As the TDGi total flow decreases below the remote set point, the TDGi controller output (CV) increases. The output is sent to TDGi VFD. This will increase the speed of the VFD and bring the TDGi total flow up to the remote set point. The TDGi controller automatically adjusts the speed of the VFD to maintain the calculated remote set point.

[0069] The TDGi ratio on the remote set point to the controller is calculated based on the burner test results with NOx values that were less than the predetermined NOx value. Based on those results, the recommended flue gas recirculation rate is about 6-8% of the total stack flow to ensure low NOx generation and good operation. The recirculation gas flow rate should not be adjusted outside of a 5-13% range.

[0070] In automatic mode, the TDGi controller continually calculates output values based on PV and SP values over time. There are times, however, when it is desirable to allow a human operator to manually override the automatic action of the PID controller. Applicable instances include commissioning, emergencies, and maintenance procedures.

[0071] FIGS. 1-3 illustrate one embodiment of a burner 100 according to the present invention. The burner 100 comprises a plenum 105 connected to a burner tile 110. The plenum 105 has a combustion air inlet 115 through which combustion air 120 flows into the plenum 105, and a NOx reducing medium inlet 125 through which NOx reducing medium 130 flows into the plenum 105.

[0072] The burner tile 110 forms a primary combustion zone 135.

[0073] The burner 100 includes a fuel injector 140 which has an inlet 145 and an outlet 150 in the primary combustion zone 135. Liquid fuel 155 and atomizing medium 160 enter the inlet 145 of the fuel injector 140 and flow upward to the fuel injector outlet 150. Alternatively, fuel gas 200 could be introduced into the fuel injector 140. In the case where fuel gas 200 is injected in primary combustion zone, atomizing medium 160 may not be injected.

[0074] The fuel injector 140 is surrounded by a NOx reducing medium conduit 165 which has an inlet 170 and an outlet 175. The NOx reducing medium 180 enters the NOx reducing medium conduit 165 and flows upward. A portion of the combustion air 120 enters the NOx reducing medium conduit 165 through openings 185. The combustion air 120 and NOx reducing medium 180 mix and exit through the NOx reducing medium conduit outlet 175 into the primary combustion zone 135 where the combustion air 120 reacts with the atomized liquid fuel from the fuel injector outlet 150 and forms a flame.

[0075] Combustion air 120 and NOx reducing medium 130 in the plenum 105 flow upward through a passage 190 in the burner tile 110 into the primary combustion zone 135.

[0076] A primary fuel gas conduit 195 carries fuel gas 200 from the primary fuel gas conduit inlet 205 to the primary fuel gas conduit outlets 210 where it reacts with the combustion air 120 in the primary combustion zone 135.

[0077] As shown in FIG. 2, there are staged fuel gas conduits 215 located outside the burner tile 110. The staged fuel gas conduits 215 are connected to the primary fuel gas conduit 195 which supplies fuel gas to them. Fuel gas from the outlets 220 of the staged fuel gas conduits 215 reacts with combustion air 120 from the primary combustion zone 135 downstream of the burner tile 110 to form a flame.

[0078] There is a flame stabilization device 225 at the NOx reducing medium conduit outlet 175 of the NOx reducing medium conduit 165.

[0079] FIG. 3 is a plan view of the burner 100 showing the locations of the fuel injector outlet 150, NOx reducing medium conduit outlet 175, flame stabilization device 225, primary fuel gas conduit outlets 210, staged fuel gas conduit outlets 220.

[0080] FIGS. 4-6 illustrate another embodiment of a burner 100 according to the present invention.

[0081] The burner 300 comprises a plenum 305 connected to a burner tile 310. The plenum 305 has a combustion air inlet 315 through which combustion air 320 flows into the plenum 305, and a NOx reducing medium inlet 325 through which NOx reducing medium 330 flows into the plenum 305.

[0082] The burner tile 310 forms a primary combustion zone 335.

[0083] The burner 300 includes a fuel injector 340 which has an inlet 345 and an outlet 350 in the primary combustion zone 335. Liquid fuel 355 and atomizing medium 360 enter the inlet 345 of the fuel injector 340 and flow upward to the fuel injector outlet 350. Alternatively, fuel gas 400 could be introduced into the fuel injector 340. In the case where fuel gas 400 is injected in primary combustion zone, atomizing medium 360 may not be injected.

[0084] The fuel injector 340 is surrounded by a NOx reducing medium conduit 365 which has an inlet 370 and an outlet 375. The NOx reducing medium 380 enters the NOx reducing medium conduit 365 and flows upward. A portion of the combustion air 320 enters the NOx reducing medium conduit 365 through openings 385. The combustion air 320 and NOx reducing medium 380 mix and exit through the NOx reducing medium conduit outlet 375 into the primary combustion zone 335 where the combustion air 320 reacts with the atomized liquid fuel from the fuel injector outlet 350 and forms a flame.

[0085] Combustion air 320 and NOx reducing medium 330 in the plenum 305 flow upward through a passage 390 in the burner tile 310 into the primary combustion zone 335.

[0086] A primary fuel gas conduit 395 carries fuel gas 400 from the primary fuel gas conduit inlet 405 to the primary fuel gas conduit outlets 410 where it reacts with the combustion air 320 in the primary combustion zone 335.

[0087] In this embodiment, there is a staged NOx reducing medium conduit 430 (one or more) with a staged inlet 435 and a staged outlet 440. A third portion of the NOx reducing medium 380 is introduced into the staged inlet(s) 435 of the staged NOx reducing medium conduit(s) 430. The staged outlet(s) 440 of the staged NOx reducing medium conduits 430 are outside the burner tile 310.

[0088] As shown in FIG. 5, there are staged fuel gas conduits 415 located outside the burner tile 310. The staged fuel gas conduits 415 are connected to the primary fuel gas conduit 395 which supplies fuel gas to them. Fuel gas from the outlets 420 of the staged fuel gas conduits 415 reacts with combustion air 320 from the primary combustion zone 335 downstream of the burner tile 310 to form a flame.

[0089] There is a flame stabilization device 425 at the NOx reducing medium conduit outlet 375 of the NOx reducing medium conduit 365.

[0090] FIG. 6 is a plan view of the burner 300 showing the locations of the fuel injector outlet 350, NOx reducing medium conduit outlet 375, flame stabilization device 425, primary fuel gas conduit outlets 410, staged fuel gas conduit outlets 420, and staged NOx reducing medium conduit outlets 440.

[0091] The NOx reducing medium can be introduced into one or more of the NOx reducing medium inlet 325, and/or the NOx reducing medium conduit inlet 370, and/or the staged NOx reducing medium conduit inlet 435. The flow of NOx reducing medium into one or more of these inlets can be controlled by monitoring at least one NOx value for the flame. The flow rate of the NOX medium to each of the inlets can be independently adjusted based on the at least one NOx value.

[0092] It should be appreciated and understood by those of ordinary skill in the art that various other components such as valves, pumps, fans, filters, coolers, etc. were not shown in the drawings as it is believed that the specifics of same are well within the knowledge of those of ordinary skill in the art and a description of same is not necessary for practicing or understanding the embodiments of the present invention.

[0093] Any of the above lines, conduits, units, devices, vessels, surrounding environments, zones or similar may be equipped with one or more monitoring components including sensors, measurement devices, data capture devices or data transmission devices. Signals, process or status measurements, and data from monitoring components may be used to monitor conditions in, around, and on process equipment. Signals, measurements, and/or data generated or recorded by monitoring components may be collected, processed, and/or transmitted through one or more networks or connections that may be private or public, general or specific, direct or indirect, wired or wireless, encrypted or not encrypted, and/or combination(s) thereof; the specification is not intended to be limiting in this respect.

[0094] Signals, measurements, and/or data generated or recorded by monitoring components may be transmitted to one or more computing devices or systems. Computing devices or systems may include at least one processor and memory storing computer-readable instructions that, when executed by the at least one processor, cause the one or more computing devices to perform a process that may include one or more steps. For example, the one or more computing devices may be configured to receive, from one or more monitoring component, data related to at least one piece of equipment associated with the process. The one or more computing devices or systems may be configured to analyze the data. Based on analyzing the data, the one or more computing devices or systems may be configured to determine one or more recommended adjustments to one or more parameters of one or more processes described herein. The one or more computing devices or systems may be configured to transmit encrypted or unencrypted data that includes the one or more recommended adjustments to the one or more parameters of the one or more processes described herein.

[0095] The computing device of system unit may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

[0096] The memory may be any suitable known or other machine-readable storage medium. The memory may comprise non-transitory computer readable storage medium such as, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory may include a suitable combination of any type of computer memory that is located either internally or externally to the device such as, for example, random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. The memory may comprise any storage means (e.g., devices) suitable for retrievably storing the computer-executable instructions executable by the controller or a computing device.

[0097] The methods and steps described herein may be implemented in a high-level procedural or object-oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of the controller or computing device. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for control gas flow to a burner described herein may be stored on the storage media or the device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein.

[0098] Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.

SPECIFIC EMBODIMENTS

[0099] While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[0100] A first embodiment of the invention is a liquid fuel or hybrid fuel burner comprising a plenum having a combustion air inlet; a burner tile connected to the plenum, the burner tile forming a primary combustion zone; a fuel injector positioned in the plenum, the fuel injector comprising an inlet and an outlet, the outlet positioned in the primary combustion zone; a passage through the burner tile from the plenum to the primary combustion zone for combustion air and NOx reducing medium; a primary fuel gas conduit comprising a primary fuel gas inlet and a primary fuel gas outlet, the primary fuel gas outlet positioned in the primary combustion zone; and a NOx reducing medium inlet into the plenum, or a NOx reducing medium conduit positioned in the plenum, the NOx reducing medium conduit comprising a NOx reducing medium conduit inlet and a NOx reducing medium conduit outlet, the NOx reducing medium conduit outlet positioned in the primary combustion zone, wherein the fuel injector is positioned in the NOx reducing medium conduit, or a staged NOx reducing medium conduit comprising a staged NOx reducing medium inlet and a staged NOx reducing medium outlet, the staged NOx reducing medium outlet positioned outside the burner tile, or combinations thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein NOx reducing medium conduit further comprises a combustion air inlet located in the plenum. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a secondary fuel gas conduit comprising a secondary fuel gas inlet and a secondary fuel gas outlet, the secondary fuel gas outlet positioned outside the burner tile. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the secondary fuel gas conduit is connected to the primary fuel gas conduit. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the NOx reducing medium conduit and the fuel injector are in a concentric arrangement. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a flame stabilization device in the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the passage through the burner tile surrounds the NOx reducing medium conduit. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the passage through the burner tile and the NOx reducing medium conduit are in a concentric arrangement.

[0101] A second embodiment of the invention is a method of reducing production of NOx gases at a burner comprising injecting one or more of a liquid fuel, or a fuel gas,, or an atomizing medium from a fuel injector into a primary combustion zone defined by a burner tile forming an atomized liquid fuel or fuel gas or both; injecting a first portion of NOx reducing medium into the primary combustion zone from a NOx reducing medium conduit surrounding the fuel injector, or injecting a second portion of NOx reducing medium into the primary combustion zone through a passage in the burner tile, or injecting a third portion of NOx reducing medium outside the burner tile, or combinations thereof; and injecting combustion air into the primary combustion zone through the passage in the burner tile, whereby the combustion air and the atomized liquid fuel or fuel gas or both react and produce a flame in the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising passing a first portion of the combustion air into the NOx reducing medium conduit; and wherein injecting the first portion of the NOx reducing medium into the primary combustion zone comprises injecting the first portion of the NOx reducing medium and the first portion of the combustion air into the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising; injecting primary fuel gas through a primary fuel gas outlet into the primary combustion zone wherein the combustion air and the primary fuel gas react and produce a flame inside the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising; injecting secondary fuel gas through a secondary fuel gas outlet into an area outside the burner tile wherein the combustion air from the passage and the secondary fuel gas react and produce a flame outside the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the atomizing medium comprises steam, air, nitrogen, fuel gas, or combinations thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising; stabilizing the flame with a flame stabilization device in the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein injecting the combustion air and the second portion of NOx reducing medium into the primary combustion zone through the passage in the burner tile comprises introducing the combustion air and the second portion of NOx reducing medium into a plenum connected to the burner tile and wherein the combustion air and the second portion of NOx reducing medium pass from the plenum through the passage in the burner tile to the primary combustion zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the passage in the burner tile surrounds the NOx reducing medium conduit. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the first portion of NOx reducing medium, or the second portion of NOx reducing medium, or the third portion of the NOx reducing medium, or combinations thereof comprise flue gas from a combustion zone; flue gas from the exhaust of a heater, a boiler, or a furnace; steam; nitrogen; carbon dioxide; or combinations thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising monitoring at least one NOx value for the flame; and adjusting a flowrate of the first portion of NOx reducing medium, or the second portion of NOx reducing medium, or the third portion of the NOx reducing medium, or combinations thereof based on the at least one NOx value.

[0102] Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of this invention, without departing from the spirit and scope thereof, to make various changes and modifications of the invention and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0103] In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.