BOQUI LINE OF INJECTION OF COMBUSTI BLE OF CONTRAFFUJO IN A SYSTEM QUADOR-HERVI DOR
Cross Referencing With Related Requests This application claims the benefit of the filing date of the United States Request Series No. 60 / 474,470, filed on May 31, 2003, now pending.
CAM PO AND BACKGROUND OF THE INVENTION The field of the invention generally relates to fuel injection nozzles and, more particularly, to a counterflow fuel injection nozzle. The burners are used in kettles, heaters and other applications for the conversion of fuel into heat. The heat is then transferred to make hot water, steam and / or hot air or to create energy, depending on the application. In a burner-boiler system (eg, a chimney pipe and industrial water tube boilers), fuel is typically injected through boilers to create a flame. The fuel is combined with air flow around or adjacent to the nozzle. Finally, the fuel burns to create a flame, with the purpose of maximizing the conversion of the fuel that is burned during this combustion process in order to achieve complete combustion. The manner in which the fuel is injected (ie, its direction, velocity and interaction with other fluid streams) in the current of air affects the profile or shape of the flame and thus greatly determines the term of the combustion and the Heating heat in the oven. The injection method affects the total geometry and physical characteristics of the bob itself. For example, the fuel is typically injected through the passage (s) formed in the nozzle and, more particularly, the nozzle body. These physical characteristics include the amplitude or diameter, separation and inclination or decline of the passage (s) or channel (s) in particular. A purpose of continuous design is to achieve control of the mixture (eg, quality, uniformity, speed, etc.) of the fuel and air through the burner so that the air and fuel mix evenly. Variations in the amplitude, separation and decline of the boquil passages used to dissipate the fuel from the boiler produced mixing results, flame profiles, flame locations and total combustion performance factors. variants. It has been found that the inclined injection passages that inject the fuel in a counterflow manner contribute positively to the aforementioned factors. By "counterflow" it is meant that the fuel is injected into a flow of air such that at least one fuel flow vector component opposes at least one vector component of the air flow. Therefore, it would be desirable, in a burner that uses a gaseous fuel (e.g., natural gas), to be able to improve the control of the fuel mixture with air by introducing the fuel into the air in a manner a counterflow.
BACKGROUND OF THE INVENTION A counterflow fuel injection nozzle is set forth herein for injecting fuel, the nozzle comprising: a nozzle wall having an interior surface defining a nozzle interior. The front to receive a fuel therein, the fuel also having a fuel passage formed in the wall of the nozzle to distribute the fuel from the inside to an external location of the nozzle, distributing the fuel to the location outside in a direction of fuel flow injection. When an air stream is provided in a predominant air flow direction at the outer location of the nozzle, at least one vector component of the fuel flow injection direction opposes at least one vector component of the direction of dominant air flow. Other objects, aspects and advantages of the invention will be apparent after a thorough reading of the detailed description in the following with the drawings.
BRIEF DESCRIPTION OF THE INVENTION The embodiments of the invention are set forth in relation to the accompanying drawings and are for illustrative purposes only. The invention is not limited in its application to the details of construction or installation of the components illustrated in the drawings. The invention is capable of other modalities or of being practiced or carried out in various ways. No similar numerical references are used to indicate similar components. In the drawings: Figure 1 is a partially exploded, perspective view of a burner incorporating a counterflow fuel injection nozzle embodiment of the present invention; Figure 1 a is a front view of a burner incorporating a counterflow fuel injection nozzle embodiment of the present invention; Fig. 2a is a side cut-away view, taken along the line 2a-2a of Fig. 1a; Figure 2b is a diagram illustrating in a schematic manner the concept of counterflow with respect to a representation of the present inventive counterflow fuel injection nozzles; Figure 2c is a representation of various orifice and distance parameters associated with the counterflow fuel injection nozzle illustrating the parameters affecting the interaction of the fuel jets of the adjacent nozzles; Figure 2d is a graphical representation of various fuel penetration depths and total fuel distribution patterns associated with the present invention; Figure 3 is an enlarged sectional view, taken along the line 3-3 of Figure 2a; Figure 4 is a perspective view of a mode of the counterflow fuel injection nozzle, according to an aspect of the present invention;
Figure 5 is a lower sectional view, taken along line 5-5 of Figure 3; Fig. 6 is a perspective view of another embodiment of the counterflow fuel injection nozzle according to an aspect of the present invention; Figure 7 is a side sectional view of the counterflow fuel injection nozzle of Figure 6; Fig. 8 is a bottom sectional view taken along line 8-8 of Fig. 7 and illustrating exemplary contraflux injection angles; Fig. 9 is a perspective view of another embodiment of the counterflow fuel injection nozzle according to an aspect of the present invention; Fig. 10 is a side sectional view of the counterflow fuel injection nozzle of Fig. 9; Fig. 11 is a front sectional view, taken along line 11 of Fig. 10 and illustrating the exemplary angular spacing of the fuel injection ports; Fig. 12 is a perspective view of another embodiment of the counterflow fuel injection nozzle according to an aspect of the present invention; Fig. 13 is a side sectional view of the counterflow fuel injection nozzle of Fig. 12; Fig. 14 is a sectional, side, partial view of another embodiment of the counterflow fuel injection nozzle according to an aspect of the present invention; and Figure 15 is a perspective view of the counterflow fuel injection nozzle of Figure 14.
DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In the figures, similar numbers are used to designate similar parts through the drawings, and various pieces of equipment, such as valves, fittings, pumps and the like, are omitted in order to simplify the description of the invention. However, those skilled in the art will realize that such conventional equipment can be used as desired. In addition, although the invention is applicable to various fuel burner equipment, this will be discussed for illustration purposes in connection with a steam or hot water boiler. Figure 1 is a partially exploded view, in perspective, of a burner 1 incorporating a mode of a counterflow fuel injection nozzle 2 of the present invention. The burner 1 can receive a gaseous fuel (e.g., propane, natural gas, etc.) from a fuel source (not shown) through a pipeline or fuel line (not shown) and supply inside the burner through of the lance 14. The total combustion air flow is indicated by arrow 3, with primary air 4, secondary air 5 and tertiary air 6 flowing through other paths (as directed at the burner inlet, for example , around a diffuser 7 and between injection nozzles) to promote complete combustion. Air flows can have, in addition to air, combustion gas products (FGR). In general, the 02 levels are lower in the combustion gas products than in the air. Therefore, more air may be necessary in the primary, secondary or tertiary air flows to achieve the necessary levels of oxygen, required to complete the combustion. Oxygen levels may preferably be in the range of 11-21%, more preferably in the range of 15-21% and more preferably in the range of 16-19%. Figure 1a is a front view of a burner incorporating a counterflow fuel injection nozzle embodiment of the present invention and Figure 2a is a side elevation view taken along line 2a-2a of the figure 1a. Referring to Figures 1a and 2a, fuel is introduced into the burner 10 at a number of locations through the distributor 11. More specifically, the fuel is introduced through a plurality of radially disposed fuel pipes or lances 14. In addition , the central injection pipe 13 is used to distribute fuel through nozzles 15 in order to create a flame in the center of the burner. The burner 10 further includes a diffuser (also called a "cyclonizer"), generally referred to by the number 18, having blades 20. Tertiary air is introduced into the burner 10, also indicated by the number 6, and the diffuser 18 imparts a rotating movement to the air in order to increase the mixture of air and fuel. The radially disposed lances 14 end with injection nozzles 16, also referred to herein as simply "injectors" or "nozzles". The distance 19 between the upper part 17 of the nozzle 16 and the start of the diffuser flat area 21 is an important factor for the successful application of the nozzle 16 since it will affect the mixing capabilities of the fuel and the air. The space between the nozzle 16 and the outer ring 25, as indicated by the arrow 27, is also important in the mixing capacities. The primary, secondary and tertiary air is introduced into the burner 10, as shown. In the embodiment shown, the "predominant airflow direction" corresponds to an airflow direction in which air travels from a generally upstream location of the fuel injectors to a location generally downstream of the fuel injectors. . The air flow can be influenced by structures or "flattened bodies" inside the burner itself (for example, the diffuser, distributors, fuel lines, etc.). As will be described in more detail below, and as shown in Figure 1, at least a portion of the air flow is directed or distributed beyond the diffuser and generally along or beyond the nozzles 16. Figure 2b is a diagram that schematically illustrates the concept of backflow with respect to a representation of this counterflow fuel injection nozzle., inventive. As shown, fuel flows into nozzle 510 in an initial fuel flow direction 51 8 and flows inwardly 514 from the nozzle. The fuel is distributed from nozzle interior 514 along a fuel flow injection direction 520 (Fcombustib | e). The fuel is typically injected at a preferred pressure of up to 20 psig. The "fuel flow injection angle" is the angle at which the fuel is injected out of the counterflow fuel injection nozzle and, more specifically, the interior of the nozzle, through openings , orifices or openings 516a-b to an outer location of the nozzle. The direction of injection of the fuel flow is determined by the injection angle of the fuel flow T in which the fuel is distributed from the inside of the fuel. The trajectory is determined by the angle, as well as fuel and air velocity. As shown, the angle is measured from a plane that is normal or perpendicular to the surface of the nozzle. The fuel flowing along the fuel flow injection direction 520 includes a perpendicular flow vector component 522 (~ F) and a counterflow vector component 524 (). By "perpendicular" it is meant that the vector component is perpendicular to the prevailing air flow direction and by "counterflow" it is understood that the vector component opposes the predominant air flow direction. To promote the fuel and air mixture, the fuel is injected along the fuel injection direction 520 into the air flowing in a direction of dominant air flow 526 (Faire). The mixture typically occurs in a place outside the jar. It is noted that the fuel flow injection direction vector is shown in a schematic manner to illustrate the injection angle of the fuel flow more clearly, but that the fuel flow path takes a more complex trajectory (it is say, it curves or rotates) due to the injection of the fuel into the prevailing air flow and as the distance the fuel travels from the nozzle increases. This more complex trajectory is indicated by the arrow 525. The fuel flows in the direction of fuel flow injection such that it is generally inclined with respect to the direction of the prevailing air flow, resulting in a counterflow angle? , which is measured with respect to the predominant air flow direction. A "counterflow angle" exists when at least one vector component (i.e., a counterflow fuel vector component) of the fuel flow injection direction is opposite to at least one vector component of the direction of the fuel flow. predominant air flow (ie, a counterflow air vector component). As shown schematically, the counterflow fuel vector component 524 opposes or is opposed (and therefore flows against) at least one counterflow vector component of the predominant air flow direction 526. An important purpose for distributing fuel in an air flow in order to create a counterflow angle is to achieve, or substantially achieve, the complete mixing of the fuel in the air. Preferably, the spectrum of injection angles of the fuel flow T varies from about 15 degrees to about 90 degrees (ie, meaning 90 degrees in full counterflow). In a preferred embodiment, the counterflow angle is approximately 30 degrees. Figure 3 is an enlarged sectional view taken along the line 3-3 of Figure 2a, in particular illustrating a sectional view of the nozzle 16 according to one aspect of the present invention in greater detail. . Figure 4 is a perspective view of an embodiment of the counterflow fuel injection nozzle according to one aspect of the present invention. The injection nozzle 1 6 includes a nozzle body 28. And FIG. 5 is a sectional view, lower, taken along line 5-5 of Figure 3. Referring to Figures 3-5, the nozzle body 28 has a nozzle wall 30 and the nozzle wall 30 defines a nozzle interior 32. As shown, the nozzle 16 is generally in the form of a "T". Its interior of bulb 32 is the one that receives the fuel to be distributed and finely injected in the current of air to produce a flame. Since the interior of the nozzle 32 acts as a fuel conduit, the shape of the orifice, the diameters of the orifice, the distribution of holes and the injection angles all contribute to the manner in which the fuel is distributed. through the entire interior of the nozzle 32. The modality shown is only representative and it is contemplated that other shapes, geometric features and body profiles may be used appropriately. That is to say, the nozzle can have other curves, inclinations, angles and inner and inner geometries suitable in a particular way and still meet the objectives of the injection nozzle 1 6. Also, any suitable material can be used in the construction of the injection nozzle 1 6, although stainless steel is a preferred material, among others. The interior surface 34 of the nozzle wall 30 defines the interior of the nozzle 32 in which fuel is received from the fuel line 14. Various means of connection between the fuel line 14 and the fuel line 14 are possible. Injection nozzle 16. The nozzle body 28 further includes a series of fuel passages 40 which end in holes or openings 42 formed in the wall of the nozzle to distribute the fuel from the inside. According to the above, fuel flows from the interior of the nozzle 32 through the passages 40 and out of the nozzle 1 6 through holes 42 towards an air flow (see Figures 1-2). It is contemplated that the size, shape and placement of the holes and passages may vary to achieve the desired mixing effect (ie, mixing between the air flow and the fuel injected into the air). The size of the holes in the bulb is critical because if the holes are too small, "clogging" and other similar problems can occur. One factor in determining the proper size, shape and placement of holes and passages is the position of the nozzle relative to the air flow. Another factor is the geometry of the nozzle itself. The placement of holes can be selected to promote mixing by distributing fuel in the predominant air flow. The result is that the air is dragged (transported in a stream) into the fuel to achieve a better mix. Finally, the purpose is to achieve uniform mixing and it has been found that a more uniform mixture results from a wide dispersion of the fuel in an air flow. In the embodiment illustrated in Figures 3-5, the representative passages and the placement of holes are shown in a representative manner. The fuel is injected along a fuel injection direction 40. The representative fuel injection paths are illustrated by arrows 44. More specifically, in one embodiment, the passages may be easy and the orifices may be be round Although any hole size is contemplated, in one embodiment, the holes can be sized to have a diameter in a range of from about 0.0625 inches to about 0.141 inches. In one embodiment, the holes can be separated, as measured from their respective centers, from about 0.325 to about 0.75 inches, with an exemplary distance of 0.5-inch holes. A design purpose is to select the size, the shape and placement of the holes in the nozzle to reduce, or substantially eliminate, the interference between the orifices (e.g., a fuel injection direction crossing, in whole or in part, with another direction of fuel injection). gas). As shown in Figure 2c, for a given nozzle N, the distance between the orifices of an exemplary nozzle is L and the diameter of the holes is D. The L / D ratio will define the interaction between the adjacent holes. The diameter of the holes will determine the depth of penetration of the fuel (gas) and the total distribution patterns of the fuel. L determines whether adjacent fuel jets result in a mixture or combination of fuel streams. As shown in Figure 2d, the exemplary depth of fuel penetration and fuel distribution patterns x1 and x2 are illustrated for two holes y and z of different orifice diameters. It is contemplated that variations in size, shape and placement of the orifices may be from nozzle to nozzle (ie, for a nozzle orifice to holes and separations are identical), or the size, shape and placement may vary from orifice. to hole. In a preferred embodiment, the ratio of L to D is approximately 5. The interaction between adjacent nozzles (in addition to the staggering of the holes) can be an effective means for effecting the fuel jet interaction. In general, it can be said that the backflow angle (ie, the angle created by the direction of injection of the fuel flow with respect to the direction of the predominant air flow) effects the downstream mixing of the orifices. It has been found that ideal mixing conditions occur when the counterflow angle is such that the direction of the fuel flow is not completely opposite to the predominant air flow direction. The counterflow angle also effects the location of the air / fuel mixture and allows control whether the mixture is more or less current below the nozzles. This can be advantageous for a variety of reasons. For example, by keeping the mixture of air and fuel even more current under the nozzles, the flame can still be created further downstream, and the nozzle can be protected from exposure to high levels of heat. This can be used to prevent the nozzles from burning prematurely. Also, the size, number and placement of passages and holes in the body of the nozzle allow the sculpture of the flame (also called flame configuration or flame formation) to achieve an optimal mixture in relation to the geometry of the furnace. In general, it has been found that when conditions approach "full backflow" (ie, when the paths of fuel and air are completely opposite each other), a better mix may occur, although less control of the mixture will be achieved. , since the paths of the trajectories will be unpredictable. Also, the selection of the counterflow angle depends on conditions such as the distribution, direction and speed of the air flow in the burner. Figure 6 is a perspective view of another embodiment of a counterflow fuel injection nozzle according to an aspect of the present invention. Figure 7 is a sectional, side view of a counterflow fuel injection nozzle of Figure 6 and Figure 8 is a sectional, side view taken along line 8-8 of Figure 7. Figures 6 -8 also illustrate exemplary counterflow injection angles. Referring to FIGS. 6-8, the nozzle body 1 28 has a nozzle wall 130 and the nozzle wall 130 defines an interior of the nozzle body 132. As shown, the nozzle 1 16 is generally "in shape". T truncates "since it is truncated when compared to the modality of Figures 3-5. This is the interior of the body of the nozzle 132 which receives the fuel to be distributed and finally injected into the air stream to produce a flame. Since the interior of the body of the nozzle 1 32 acts as a fuel conduit, the shapes of the orifice, as with the other embodiments, the orifice diameters, the distribution and injection angles of the orifices, all contribute to the manner in which the fuel is distributed throughout the interior of the nozzle 132. shown is only representative and it is contemplated that other forms, geometric features and body profiles could be used appropriately. Also, any suitable material can be used in the construction of injection nozzles 116, although stainless steel is a preferred material, among others. The interior surface 134 of the nozzle wall 130 defines the interior of the nozzle 132 in which fuel from the fuel line 114. is received. The fuel line 114 includes an optional threaded portion 136 for threaded insertion in a threaded portion. coupling 138 of the inner surface 134, if a threaded connection is desired. Although a threaded clutch is shown and preferred, it is contemplated that other means of connection between the fuel line 114 and the injection nozzle 116 are possible. The body of the nozzle 128 further includes a series of fuel passages 140 terminating in holes or openings 142 formed in the wall of the nozzle to distribute the fuel from the interior. According to the above, fuel flows from the interior of the nozzle 132 through the passages 140 and out of the nozzle 116 through holes 142 towards an air flow (again, see Figures 1-2). It is contemplated that the size, shape and placement of the holes and passages may vary to achieve the desired mixing effect (i.e., mixing between the air and the fuel injected into the air). Again, the placement of holes will be selected to promote mixing by distributing fuel in the prevailing air flow. In the embodiment illustrated in Figures 6-8, the representative passages and the placement of the holes are shown in a representative nozzle. The fuel is injected along representative directions of fuel injection 144. The size and placement of the various passages and orifices are similar to those described in detail above with respect to Figures 3-5. Figure 9 is a perspective view of another embodiment of the counterflow fuel injection nozzle according to an aspect of the present invention. A design parameter of mode 9 is the limited receiving area shown, such that the nozzle shown could be incorporated into smaller burners, particularly where the insertion of a larger T-area or nozzle would not otherwise fit adequately in the space provided. Figure 1 0 is a side sectional view of the counterflow fuel injection nozzle of Figure 9. Figure 1 1 is a front sectional view, taken along the line 1 1 - 1 1 of the figure 1 0. Figures 9-1 1 illustrate exemplary fuel flow injection angles and angular separation of holes. Referring to FIGS. 9-1 1, the nozzle body 228 has a nozzle wall 230, and the nozzle wall 230 defines an interior of the nozzle body 232. As shown, the nozzle 216 includes several contours that can be seen in FIG. They define a primary notch or groove, placed circumferentially to the center 233, which defines a surface 235. The shape of the nozzle is generally referred to herein as "fungiform". The interior of the body of the nozzle 232 is that which receives the fuel by distributing it and finally injecting it into the air stream to produce a flame. Since the interior of the body of the nozzle 232 acts as a fuel conduit, the particularized curves, inclinations, angles and surface and interior geometry of the injection nozzle 21 6 will dictate the manner in which the fuel is distributed. Throughout the interior of the body of the tube 232. The modality shown is only representative and it is contemplated that other forms can be adequately used., geometric characteristics and body profiles. Also, any suitable material can be used in the construction of the injection nozzle 21 6, although steel is a preferred material among others. The interior surface 234 of the nozzle wall 230 defines the interior of the nozzle 232 in which the fuel from the fuel line 21 is received. 4. The fuel line 214 includes a threaded portion 236 for insertion. threaded in a threaded coupling portion 238 of the inner surface 234. Although a threaded clutch is shown and preferred, it is contemplated that other means of connection between the fuel pipe 214 and the injection nozzle 21 are possible. The nozzle body 228 further includes a series of passages 240 that terminate in holes or openings 242 formed in the wall of the fuel distribution nozzle and, more particularly, the orifices formed in the surface 235 of the notch or notch. primary slot, positioned circumferentially to the center 233. According to the above, the fuel flows from the interior of the nozzle 232 through the passages 240 and out of the nozzle 216 through holes 242 toward an air flow (again, see Figures 1-2). It is contemplated that the size, shape and placement of the holes and passages may vary to achieve the desired mixing effect. Up to here, the placement of holes will be selected to promote mixing by distributing fuel in the prevailing air flow. In the embodiment illustrated in Figures 9-11, the representative passages and the placement of the holes are shown in a representative nozzle. The fuel is injected along a fuel injection direction 244. The representative fuel injection paths are illustrated by arrows 244. The size and placement of the various passages and orifices are similar to those described above in detail with with respect to figures 3-5. Fig. 12 is a perspective view of another embodiment of the counterflow fuel injection nozzle 416 according to one aspect of the present invention. Figure 13 is a side cut view of the counterflow fuel injection nozzle 416 of Figure 12. Figures 12-13 also illustrate fuel injection and counterflow fuel injection paths. Referring to Figures 12-13, the nozzle body 428 has a nozzle wall 430, and the nozzle wall 430 defines a nozzle interior 432. This interior of the nozzle body 432 is the one that receives the fuel through distribute and finally inject in the air stream to produce a flame. Since the interior of the nozzle body 432 acts as a fuel conduit, the particularized curves, inclination angles and surface and interior geometry of the injection nozzle 416 will dictate the manner in which the fuel is distributed through the entire interior of the nozzle body 432. So far, any suitable material can be used in the construction of the injection nozzle 416, although stainless steel is a preferred material, among others. The inner surface 434 of the nozzle wall 430 defines the interior of the nozzle 432 in which fuel from the fuel line 414 is received. The fuel line 414 includes the threaded portion 436 for threaded insertion in a threaded portion. coupling 438 of the inner surface 434. Although a threaded clutch is shown and preferred, it is contemplated that other means of connection between the fuel line 414 and the injection nozzle 416 are possible. The body of the nozzle 428 further includes a series of fuel passages 440 terminating in holes or openings 442 formed in the wall of the nozzle 430 and, more specifically, slot 433, to distribute the fuel. The groove 433 prevents air from rupturing the gas coming out of the orifices by shearing and allows the gas to develop a propulsion current, which results in a more consistent mixture.
The fuel flows from the interior of the nozzle 432 through the passages 440 and out of the nozzle 416 through holes 442 into an air flow (again, see Figs. 1-2). It is contemplated that the size, shape and placement of the holes and passages may vary to achieve the desired mixing effect. Again, the placement of holes can be selected to promote mixing by distributing fuel in the prevailing air flow. In the embodiment illustrated in Figures 12-1, the representative passages and orifice placement are shown in a representative manner. The fuel is injected along a fuel injection direction 444. In a modality of the counterflow fuel injection nozzles, used in Figures 1 2 and 1 3, the passages may be cylindrical and the holes can be round. Although any hole size is contemplated, in one embodiment, the holes can be sized to have a diameter in a range from about 0.0625 inches to about 0.14 inches. The angular separation of the orifices varies, in a fashion, from about 45 degrees to about 60 degrees. It is contemplated that there may be variations in size, shape and placement on a base from hole to hole and / or from mouthpiece to mouth. However, it is understood that a design purpose is to select the size, shape and placement of the holes to reduce or minimize interference between the fuel flow paths of the orifices (e.g., an ejection direction). of fuel that crosses, in whole or in part, another direction of fuel injection). The pattern of holes (ie, the number and position of the holes), as well as the size of the hole (eg, as determined by the diameter of the hole) may vary. In this way, the mixing of air and fuel can be carried out in order to control and achieve complete or substantially complete combustion, a feature of the present invention. Referring now to Figures 14 and 15, another embodiment of the counterflow fuel injection nozzle 500 is shown in accordance with an aspect of the present invention. In this embodiment, the nozzle 500 includes a threaded outer surface 502 with retaining nut 504 threaded therein to secure the nozzle 500 against the burner housing portion 506, such as by clipping the slot 507 and rotating the nozzle 500 appropriately. . The nozzle 500 includes a perforated portion, channel or passage 508 (shown in dashed lines) terminating in a nozzle opening 509. Fuel is injected in a fuel flow injection direction (combustion) to a predominant air direction ( Faire) Again, the fuel is injected through the nozzle opening 509 such that at least one combustion component is opposite to Faire. The most localized mixture can occur at each counterflow nozzle and, more specifically, through the orifices through which the fuel is distributed or dispersed from each nozzle to the predominant air flow. In this way, the amount or level of mixture, as well as the place (s) in which the mixture is made, can be adjusted or varied at convenience by varying the size and location of the mixture. the holes. It is contemplated that each of the above-described embodiments of the inventive counter-fuel fuel injection nozzles may include a plurality of passages, each having a unique, non-interfering, fuel injection direction. By "non-interfering" it is meant that, at the point at which the fuel leaves the nozzles (through the nozzle openings), the fuel coming from a passage having an address tends not to cross the direction of the passing fuel from another passage. The holes can also be directed at various angles to achieve the desired mixing qualities. In another aspect of the present invention, a method of mixing a fuel and air in a burner-kettle system is exposed. The system comprises a nozzle having a nozzle wall defining a nozzle interior for receiving the fuel and the nozzle further includes a fuel passage formed in the nozzle wall. The method comprises the passage of air in a predominant airflow direction along an exterior of the nozzle wall. The method further includes distributing the fuel in an injection direction of the fuel flow from the interior through the fuel passage to the air passing in the direction of the prevailing air stream along the exterior of the wall of the fuel. nozzle. The method further includes the counterflow mixture of the fuel distributed in the direction of fuel flow injection with the air passing in the direction of the prevailing air stream. Significantly, at least one vector component of the fuel flow injection direction opposes at least one vector component of the direction of the prevailing air stream. Also, the use of the counterflow nozzle provides additional burner stability with increased fuel-gas recirculation (FGR) rates (when FGR is used) to achieve lower NOx levels. As known to those skilled in the art, the rotation ratio is the ratio of maximum fuel inlet velocity to the minimum fuel velocity of a variable inlet burner and depends on the size of the burner and the control methodology. . Typical, low NOx burners have a limited turn, but with this invention, advantageously, with a low NOx operation a higher turning rate is possible and a turn from about 7 to 1 to about 10 to 1 has been achieved by using the counterflow nozzles present. It is noted that a gas mixer nozzle retrofit is contemplated for a burner used with a chimney kettle, commercial water pipe or larger industrial water pipe boiler. The retrofit can be part of equipment that includes a counterflow fuel injection nozzle that is used to replace a fuel injection no-backflow nozzle. A fuel injection no-backflow nozzle would not provide at least one vector component of a fuel flow injection direction opposing at least one vector component of a predominant air flow direction when an air stream is provided in a predominant airflow direction at an exterior location of the nozzle. Although any method is outlined in a step-by-step sequence, the termination of acts or steps in a particular chronological order is not mandatory. In addition, modification, reinstallation, combination, rearrangement or similar of steps acts are contemplated, and is considered within the scope of the description and claims. Although the present invention has been described in terms of a preferred embodiment (s), it is recognized that equivalences, alternatives and modifications are possible apart from those expressly stated, and within the scope of the appended claims.