Anti-clogging burner nozzle and method

Abstract

An anti-clogging burner nozzle device and a staged air operation method that reduce the peak temperature of the flame of the burner nozzle to provide low levels of NO x and other emissions. The burner nozzle can be used as an auxiliary burner nozzle for stabilizing the main burner flame or for other purposes.

Description

Technical Field

[0001] The present invention relates to preventing clogging while also producing low levels of NO x More particularly, but not by way of limitation, the present invention relates to burner nozzles of the type that can be used as auxiliary nozzles for combustor flame stabilization. Background Art

[0002] Industrial burners are commonly used in process heaters, boilers, furnaces, incinerators and other fired-heating systems to generate heat for use in crude oil refining, chemical production, petrochemical production and other large-scale industrial processes.

[0003] Process components in today's refineries, chemical plants and other plants must be able to operate for longer and longer periods of time without shutting down for major repairs and maintenance. In fact, maintenance cycles in many refineries and other plants are now up to four years or longer. Therefore, it is becoming increasingly important for burners and other critical equipment to continue operating for very long periods of time.

[0004] One of the main causes of downtime for industrial burners occurs when the fuel gas port of the burner nozzle(s) becomes clogged with debris or residue. Blockage of the fuel gas port can result in reduced or completely restricted fuel gas flow. Furthermore, if such a blockage occurs in a burner nozzle that is used to maintain the stability of the burner flame, the local temperature at the stabilization point can be reduced until the flame can no longer be maintained and the flame dies out. When loss of flame occurs in one or more burners of a multiple burner heating system, significant safety issues can arise, including the risk of explosion.

[0005] The auxiliary burner nozzle is a stable gas nozzle used to enhance the main flame of the burner, especially during upset conditions. Examples of upset conditions that may cause the burner flame to become unstable include, but are not limited to: (a) air flow to the burner is reduced to sub-stoichiometric levels, (b) the loss of temperature in the combustion heating system reaches a level below the minimum temperature required for igniting the fuel, or (c) a pressure excursion occurs in the combustion heating system.

[0006] Unfortunately, the auxiliary nozzles currently used in the art for flame stabilization purposes are particularly susceptible to clogging. The fuel gas ports of these auxiliary nozzles must be very small, typically 1 / 16 inch in diameter (i.e., only 0.0031 square inches of port flow area). As a result, even after filtering, the auxiliary nozzles currently used in the art are susceptible to clogging.

[0007] Therefore, there is a need for an improved burner nozzle that is resistant to plugging and can be used as an auxiliary nozzle for flame stabilization or for other purposes. The improved anti-plugging burner nozzle will preferably also produce very low levels of NO x and other emissions that are comparable to or better than the emission levels of secondary nozzles currently used in the art. Summary of the invention

[0008] The present invention provides a burner nozzle apparatus and operating method that meets the needs and alleviates the problems discussed above. The burner nozzle of the present invention is highly resistant to plugging and is particularly well suited for use as an auxiliary nozzle for maintaining the stability of the main burner flame, among other uses. The burner nozzle and operating method of the present invention also use a staged air combustion regime that converts NO x The generation of fuel and other emissions is reduced to very low levels. The low emission levels produced by the burner nozzles and methods of the present invention are comparable to or better than the levels produced by the auxiliary nozzles currently used in the art, which require the use of very small fuel exhaust ports and are easily clogged.

[0009] In one aspect, a burner nozzle device is provided, which preferably includes: (a) a shielding shell having a mixing chamber therein and an outer wall extending longitudinally, which surrounds the mixing chamber; (b) a fuel gas spud having a fuel port at a front end of the fuel gas spud positioned to discharge gas fuel into a rear longitudinal end of the mixing chamber; (c) a transverse base wall of the shielding shell, which is at the rear longitudinal end of the mixing chamber, the transverse base wall having a central opening disposed therethrough; (d) a transverse flame stabilizing ring of the shielding shell, which is at the front longitudinal end of the mixing chamber, the flame stabilizing ring having a discharge opening for the mixing chamber disposed therethrough; and (e) a flame deflector at the front longitudinal end of the shielding shell.

[0010] In another aspect, a method of operating a burner nozzle assembly is provided. The method preferably includes the following steps: (a) discharging gas fuel into a rear longitudinal end of a mixing chamber of a burner nozzle device, the mixing chamber having a transverse base wall at the rear longitudinal end of the mixing chamber, and the transverse base wall having at least a central opening formed therethrough; (b) using the momentum of the gas fuel flow discharged in step (a) to draw a substoichiometric amount of air or other oxygen-containing gas through at least the central opening of the transverse base wall to form a substoichiometric fuel-rich mixture of air or other oxygen-containing gas and gas fuel in the mixing chamber; (c) discharging the substoichiometric mixture of air or other oxygen-containing gas and gas fuel through a stabilization ring at the front longitudinal end of the mixing chamber to form a reduced pressure region outside the front longitudinal end of the mixing chamber to stabilize the flame of the burner nozzle device, the flame having an initial substoichiometric combustion region, in which a first portion of the gas fuel of the substoichiometric mixture of air or other oxygen-containing gas and gas fuel burns; and (d) causing the flame to turn outward laterally into the flow or body of air or other oxygen-containing gas to form a lean combustion region, in which the remaining portion of the gas fuel burns.

[0011] Additional aspects, features, and advantages of the present invention will become apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a cross-sectional front view of Example 2 of the burner nozzle device provided by the present invention.

[0013] Figure 2 Is it like Figure 1 FIG. 2 is a cross-sectional view of the flame deflector 12 of the burner nozzle device 2 of the present invention as viewed from perspective 2-2.

[0014] Figure 3 is a perspective view of a burner nozzle assembly 2 according to the present invention.

[0015] Figure 4 The burner nozzle arrangement 2 of the present invention is schematically shown connected to a fuel line 34 having an orifice union 36 installed therein. DETAILED DESCRIPTION

[0016] Embodiment 2 of the burner nozzle device of the present invention is Figures 1 to 4The burner nozzle 2 of the present invention preferably includes: a nozzle shielding shell 4 having a longitudinal axis 6; a mixing chamber 8 contained in the shielding shell 4; a gas fuel nozzle 10 positioned to discharge gas fuel into the rear longitudinal end of the mixing chamber 8; and a flame deflector 12 on the front longitudinal end of the shielding shell 4,

[0017] The nozzle shielding shell 4 preferably includes an outer wall 14 extending in the longitudinal direction, which surrounds the longitudinal axis 6 and the mixing chamber 8. The outer wall 14 is preferably cylindrical but may alternatively have a square, elliptical, or other cross-sectional shape. A series of small openings 16 are provided around and through the rear portion of the outer wall 14 to serve as emergency relief openings for gas expansion in the event of combustion occurring within the shielding shell 4 itself. For example, this may occur when burning hydrogen or similar fuels that have a high flame speed and require less oxygen.

[0018] The nozzle shield housing 4 preferably also includes (i) a transverse base wall 18 at the rear longitudinal end of the mixing chamber 8 and (ii) a transverse flame stabilization ring 20 at the front longitudinal end of the mixing chamber 8 .

[0019] The transverse base wall 18 at the rear end of the mixing chamber 8 has a central opening 22 disposed therethrough. When the gas fuel is discharged into the rear end of the mixing chamber 8 through the gas fuel nozzle 10, the momentum of the gas fuel flow draws air or other oxygen-containing gas into the mixing chamber 8 through the central base opening 22. In addition, the momentum of the gas fuel preferably also draws air or other oxygen-containing gas into the mixing chamber 8 through a plurality of openings 24 formed around the central base opening 22 through the base wall 18 of the shielding shell 4. The peripheral openings 24 disposed in the base wall 18 are preferably smaller than the central base opening 22.

[0020] The central base opening 22 and the peripheral base openings 24 of the shielding shell 4 are preferably sized so that the total amount of air or other oxygen-containing gas drawn through the base openings 22 and the base openings 24 for mixing with the gas fuel is a substoichiometric amount, i.e., an amount that is insufficient to burn all of the gas fuel discharged into the mixing chamber 8 through the gas fuel nozzle 10.

[0021] The transverse flame stabilization ring 20 at the forward longitudinal end of the mixing chamber 8 has a central discharge opening 26 disposed therethrough for discharging a sub-stoichiometric mixture of air or other oxygen-containing gas and gaseous fuel from the forward end of the mixing chamber 8. The diameter of the discharge opening 26 of the flame stabilization ring 20 (or other dimensions of the discharge opening 26 if the opening 26 is non-circular) and corresponding area are smaller than the cross-sectional diameter (or other cross-sectional dimensions of the mixing chamber 8 if the chamber 8 is non-cylindrical) and cross-sectional area of ​​the mixing chamber 8 so that the flow of the sub-stoichiometric gas mixture from the mixing chamber 8 through the flame stabilization ring 20 forms a reduced pressure region 28 on or near the stabilization ring 20 outside the forward end of the mixing chamber 8. The reduced pressure region 28 helps to maintain and otherwise stabilize the flame 30 produced by the burner nozzle 2 of the present invention so that the necessary time, temperature, and turbulence required for maintaining combustion are provided.

[0022] The gas fuel nozzle 10 has a fuel discharge port 32 in its front end for discharging gas fuel into the rear longitudinal end of the mixing chamber 8. The fuel discharge port 32 of the nozzle 10 is preferably located behind the base wall 18 of the shielding shell 4 so that the nozzle 10 discharges the gas fuel forward through the central opening 22 of the base wall 18. The fuel discharge port 32 may be formed directly in the front end of the gas fuel nozzle 10, or may be formed in an orifice plug placed in the front end of the nozzle 10.

[0023] To prevent clogging of the fuel takeover pipe discharge port 32, the port 32 is (a) preferably a large opening with a diameter of at least 1 / 8 inch (or equivalent size if it is non-circular), which corresponds to a flow area of ​​the discharge port 32 of at least 0.012 square inches, and (b) more preferably an opening with a diameter of at least 1 / 4 inch (or equivalent size if it is non-circular), which corresponds to a flow area of ​​the discharge port 32 of at least 0.049 square inches.

[0024] In addition, if Figure 4 As depicted in FIG. 1 , the gas fuel nozzle 10 is connected to a gas fuel supply line or riser 34 having an orifice assembly 36 containing flow orifices therein. The flow orifices in the orifice assembly 36 have a flow area that is (a) preferably at least 0.0068 square inches (which is equivalent to a circular orifice diameter of at least 3 / 32 inches) and (b) more preferably at least 0.012 square inches (which is equivalent to a circular orifice diameter of at least 1 / 8 inches).

[0025] However, the flow area of ​​the flow orifice is also preferably smaller than the size of the fuel nozzle discharge port 32. In the event that the system contains any debris that would be of sufficient size to block even the large discharge port 32 of the gas fuel nozzle 10, the debris would be blocked by the flow orifice in the orifice assembly 36, which would be located outside the combustion heating system and could be easily cleaned. The flow orifice in the orifice assembly 36 can also be used to meter the rate of flow of gas fuel from the external fuel supply manifold 38 to the burner nozzle 2 of the present invention.

[0026] The flame deflector 12 on the front longitudinal end of the shield shell 4 preferably includes: a rear opening 40; an internal flame space 42; a longitudinally extending side wall 44 extending partially around the internal flame space 42; an end wall 45 at the front longitudinal end of the side wall 44 of the flame deflector 12; and a lateral side opening 46. The end wall 45 is preferably a solid circular end wall extending laterally on the internal flame space 42 and covering the internal flame space 42. The longitudinally extending side wall 44 of the flame deflector 12 has a semicircular transverse cross-sectional shape extending from a first arc endpoint 48 to a second arc endpoint 50. The semicircular cross-sectional shape of the longitudinally extending side wall 44 is preferably an arc in the range from 120° to 270°, the arc extending from the first arc endpoint 48 to the second arc endpoint 50 and more preferably an arc of about 180°.

[0027] The lateral side opening 46 of the flame diverter 12 preferably extends (a) in a transverse cross-sectional plane from the first arc endpoint 48 of the side wall 44 to the second arc endpoint 50 and (b) longitudinally from the transverse flame stabilization ring 20 to the end wall 45 of the flame diverter 12. The lateral side opening 46 is preferably oriented to discharge the flame 30 of the burner nozzle 2 of the present invention laterally outward at an angle in the range of from 60° to 120°, more preferably about 90°, relative to the longitudinal axis 6 of the nozzle shield shell 4.

[0028] In other applications, the nozzle flame 30 is advantageously diverted by the flame diverter 12 to direct the flame 30 of the nozzle 2 of the present invention to the flange, shoulder, or end of the burner wall, or to any other stable point of the burner to maintain the stability of the main burner flame. In addition, the nozzle flame 30 is advantageously diverted by the flame diverter 12 to form a staged air operating state, which reduces the NO generated by the burner nozzle device 2 of the present invention. x and other emissions.

[0029] In the staged air operating state of the burner nozzle 2 of the present invention, the sub-stoichiometric fuel-rich mixture of air (or other oxygen-containing gas) and gas fuel flowing out of the front end of the mixing chamber 8 begins to burn in the sub-stoichiometric combustion zone 52, which includes the internal flame space 42 of the flame deflector 12. Next, the flame 30 traveling from the internal flame space 42 of the flame deflector 12 is laterally deflected into the flow or body of air or other oxygen-containing gas outside the burner nozzle 2 of the present invention. The deflection of the flame 30 into the external air or other oxygen-containing gas forms a lean combustion zone 54 outside the nozzle 2 of the present invention, and the remaining portion of the gas fuel that is not burned in the sub-stoichiometric combustion zone 52 is burned in the lean combustion zone 54.

[0030] In the method of operating the burner nozzle device 2 of the present invention, the gas fuel flows to the gas fuel nozzle 10 via the fuel line 34 and the orifice assembly 36 and is discharged forward from the discharge port 32 of the nozzle 10 through the central base opening 22 of the shielding shell 4. When the gas fuel flows through the central base opening 22 and flows into the rear end of the mixing chamber 8, the momentum of the gas fuel draws the outside air or other oxygen-containing gas into the rear end of the mixing chamber 8 through the central base opening 22 and the surrounding base openings 24. The base openings 22 and the base openings 24 are sized so that the amount of air or other oxygen-containing gas drawn through the base openings 22 and the base openings 24 is insufficient to burn all of the gas fuel and therefore forms a sub-stoichiometric mixture with the gas fuel in the mixing chamber 8.

[0031] The substoichiometric mixture of air or other oxygen-containing gas and gaseous fuel formed in the mixing chamber 8 is then discharged into the internal flame space 42 of the flame deflector 12 through the flame stabilization ring 20 at the front longitudinal end of the mixing chamber 8. This forms a pressure reduction area 28 outside the front end of the mixing chamber 8 for stabilizing the flame 30 of the burner nozzle 2 of the present invention. Due to the substoichiometric nature of the mixture of air or other oxygen-containing gas and fuel discharged from the mixing chamber 8 into the flow deflector 12, the flame 30 of the burner nozzle 2 starts in an initial substoichiometric fuel-rich combustion zone 52, which includes the internal flame space 42 of the flame deflector 12.

[0032] Next, the flame diverter 12 diverts the flame 30 of the burner nozzle 2 laterally outward into the outer flow or body of air or other oxygen-containing gas outside the burner nozzle arrangement 2. This forms an outer lean fuel combustion zone 54 in which the remaining gas fuel that was not burned in the initial substoichiometric combustion zone 52 is burned.

[0033] The staged air operation provided by burning a first portion of the fuel in the substoichiometric flame region 52 and then by burning the remaining portion of the fuel in the fuel lean flame region 54 reduces the peak temperature of the burner nozzle flame 30 in both regions and thereby reduces the NO generated by the burner nozzle 2 of the present invention. x and levels of other emissions.

[0034] Although the burner nozzle arrangement 2 of the present invention is shown in the drawings as being in a vertical orientation, it will be understood that the burner nozzle arrangement 2 may alternatively be oriented downward, horizontally, or at any other desired angle. In addition, although various elements and features of the burner nozzle arrangement 2 of the present invention are shown and described as having a cylindrical or circular shape, it will be understood that these elements and features may alternatively be square or oval in shape, or may have any other shape desired.

[0035] For example, the sizes of the burner nozzle 2 may range from small to extremely large, depending on the size of the burner in which the burner nozzle 2 of the present invention is used. For most cases, the overall dimensions of the burner nozzle 2 of the present invention will be such that: the total longitudinal length of the shield shell 4 and the flame diverter 12 will be in the range from about 4 inches to about 6 inches; the diameter of the shield shell 4 will be in the range from about 1 inch to about 4 inches; the longitudinal height of the lateral side opening 46 of the flame diverter 12 will be in the range from about 1 / 32 inch to about 1 / 2 inch; the diameter of the central base opening 22 will be in the range from about 5 / 8 inch to about 1 inch; and the diameter of each of the peripheral base holes 24 will be in the range from about 1 / 8 inch to about 1 / 4 inch.

[0036] Therefore, the present invention is well adapted to achieve the above-mentioned objects and obtain the above-mentioned purposes and advantages as well as those inherent therein. Although presently preferred embodiments have been described for the purposes of this disclosure, many changes and modifications will be apparent to those skilled in the art. Such changes and modifications are encompassed within the present invention as defined by the claims.

Claims

1. A burner nozzle device, include: a shielding shell having a mixing chamber therein and an outer wall extending in a longitudinal direction, the outer wall surrounding the mixing chamber; a gaseous fuel nozzle having a fuel port positioned to discharge gaseous fuel into a rear longitudinal end of the mixing chamber; a transverse base wall of the shielding shell at a rear longitudinal end of the mixing chamber, the transverse base wall having one or more openings disposed therethrough, a flow of air or other oxygen-containing gas being drawn through the one or more openings of the transverse base wall by the flow momentum of the gas fuel discharged through the fuel port of the gas fuel nozzle, the one or more openings including at least a central opening, and a flow area of ​​the one or more openings confining the flow of air or other oxygen-containing gas to a substoichiometric amount which mixes with the gas fuel in the mixing chamber to form a substoichiometric fuel-rich mixture; a transverse flame stabilization ring of the shield housing at a forward longitudinal end of the mixing chamber, the flame stabilization ring having a discharge opening disposed therethrough for the mixing chamber; and A flame deflector is provided at the front longitudinal end of the shielding shell, the flame deflector comprising an internal sub-stoichiometric combustion chamber, the sub-stoichiometric fuel-rich mixture is discharged from the mixing chamber through the discharge opening of the flame stabilization ring into the internal sub-stoichiometric combustion chamber and a portion of the gas fuel is burned in the internal sub-stoichiometric combustion chamber. 2 . The burner nozzle arrangement of claim 1 , further comprising a plurality of outer openings formed through the transverse base wall of the shield shell around the central opening of the transverse base wall.

3. The burner nozzle device according to claim 2, in, The outer opening formed through the lateral base wall of the shield shell is smaller than the central opening of the lateral base wall.

4. The burner nozzle device according to claim 1, in, The fuel port of the gas fuel nozzle is positioned rearward of the central opening of the transverse base wall of the shield shell and is oriented to discharge a flow of gas fuel through the central opening of the transverse base wall into the mixing chamber.

5. The burner nozzle device according to claim 1, in, The fuel port of the gaseous fuel nozzle has a flow area of ​​at least 0.049 square inches.

6. The burner nozzle arrangement of claim 1, further comprising a plurality of combustion expansion relief openings formed through the longitudinally extending outer wall of the shield shell in a rear portion of the mixing chamber.

7. The burner nozzle device according to claim 1, in, The flame diverter includes a lateral end wall and a lateral side opening at a front longitudinal end of the flame diverter.

8. The burner nozzle device according to claim 7, in: The flame deflector includes a side wall extending in the longitudinal direction; The longitudinally extending side wall of the flame deflector has a semicircular transverse cross-sectional shape extending from a first arc endpoint to a second arc endpoint; and The lateral side opening of the flame diverter extends from the first arc endpoint to the second arc endpoint.

9. The burner nozzle device according to claim 8, in, The semicircular transverse cross-sectional shape of the side wall of the flame diverter is an arc extending from the first arc end point to the second arc end point in a range from 120° to 270°.

10. The burner nozzle arrangement according to claim 9, in, The semicircular transverse cross-sectional shape of the side wall of the flame diverter is an arc of approximately 180° extending from the first arc endpoint to the second arc endpoint.

11. The burner nozzle device according to claim 9, in, The transverse end wall of the flame diverter is a solid, circular end wall at the forward end of the longitudinally extending side wall of the flame diverter.

12. The burner nozzle arrangement according to claim 11, in, The lateral side openings of the flame diverter extend longitudinally from the lateral flame stabilization ring at the front end of the mixing chamber to the solid, circular end wall of the flame diverter.

13. The burner nozzle assembly according to claim 1, further comprising: include: a fuel supply line extending to the gas fuel nozzle; an orifice assembly in said fuel supply line; and A flow orifice in the orifice assembly.

14. The burner nozzle arrangement according to claim 13, in: The fuel port of the gas fuel nozzle has a flow area of ​​at least 0.049 square inches; The flow orifice has a flow area of ​​at least 0.012 square inches; and The flow area of ​​the fuel port of the gas fuel nozzle is larger than the flow area of ​​the flow orifice.

15. A method of operating a burner nozzle assembly, comprising the steps of: a) discharging gaseous fuel into a rear longitudinal end of a mixing chamber of said burner nozzle arrangement, said mixing chamber having a transverse base wall at said rear longitudinal end of said mixing chamber and said transverse base wall having at least a central opening formed therethrough; b) using the flow momentum of the gaseous fuel discharged in step (a) to draw a sub-stoichiometric amount of air or other oxygen-containing gas through at least the central opening of the transverse base wall to form a sub-stoichiometric fuel-rich mixture of the air or other oxygen-containing gas and the gaseous fuel in the mixing chamber; c) discharging said substoichiometric mixture of air or other oxygen-containing gas and said gaseous fuel through a stabilizing ring at a forward longitudinal end of said mixing chamber to form a reduced pressure region outside said forward longitudinal end of said mixing chamber that stabilizes a flame of said burner nozzle arrangement, said flame having an initial substoichiometric combustion region in which a first portion of said gaseous fuel of said substoichiometric mixture of air or other oxygen-containing gas and said gaseous fuel burns; and d) turning the flame laterally outward into a stream or body of air or other oxygen-containing gas to form a fuel-lean combustion zone in which a remaining portion of the gaseous fuel is combusted.

16. The method according to claim 15, in, In step (b), the substoichiometric amount of air or other oxygen-containing gas is drawn by the flow momentum of the gaseous fuel through both (i) the central opening of the transverse base wall and (ii) a plurality of outer openings formed through the transverse base wall surrounding the central opening.

17. The method according to claim 16, in, The outer opening formed through the transverse base wall is smaller than the central opening of the transverse base wall.

18. The method according to claim 15, in, In step (d), the flame is diverted laterally outward using a flame diverter, the flame diverter comprising: transverse end walls and transverse side openings at the front ends of the longitudinally extending side walls, The longitudinally extending side wall of the flame deflector has a semicircular transverse cross-sectional shape forming an arc in the range from 120° to 270° extending from a first arc endpoint to a second arc endpoint, and The lateral side opening of the flame diverter extends from the first arc endpoint to the second arc endpoint.

19. The method according to claim 18, in, The lateral side opening of the flame diverter also extends longitudinally from the stabilization ring at the front longitudinal end of the mixing chamber to the lateral end wall of the flame diverter.

20. The method according to claim 15, in, The gaseous fuel is discharged in step (a) from a fuel port having a flow area of ​​at least 0.049 square inches.

21. The method of claim 20, further comprising, before step (a), the step of delivering the gaseous fuel through a flow orifice, the flow orifice having a flow area of ​​at least 0.012 square inches, and the flow area of ​​the fuel port being greater than the flow area of ​​the flow orifice.

Images