JP4264005B2 - NOx low emission burner with high fuel gas recirculation rate - Google Patents

Description

  The present invention relates to improvements in burners such as those used in high temperature furnaces used for steam cracking of hydrocarbons. The present invention is particularly directed to nitrogen oxide (NOx) low emission FGR burners that use higher flue gas recirculation (FGR) rates.

    As a result of recent interest in reducing pollutants emitted from burners used in large furnaces and boilers, the structure of the burners has changed considerably. In the past, improvements to burner structures have been primarily aimed at improving heat distribution. Increasingly strict environmental regulations shifted the focus of the burner structure to minimize regulated contaminants.

  Nitrogen oxides (NOx) are formed at high temperatures in air. However, these compounds include, but are not limited to, nitric oxide and nitrogen dioxide. Reducing NOx emissions is a necessary goal to reduce air pollution and meet government regulations. In recent years, various mobile and stationary sources that emit NOx have been increasingly regulated as a result of research.

  One strategy to achieve a low NOx emission level is to install a NOx reduction catalyst to treat the furnace exhaust stream. This strategy, known as Selective Catalytic Reduction (SCR), is effective in meeting stricter rules and does not cause much demand for alternative improvements to the burner structure, but is very costly Is expensive.

  Burners used in large industrial furnaces can use either liquid fuel or gas fuel. A liquid fuel burner mixes fuel with steam before combustion and mixes fuel with air for combustion in the combustion zone to allow for more complete combustion.

  Gas fired burners are classified as either premix burners or raw gas burners, depending on the method used to synthesize the air and fuel. These two burners also differ in configuration and type of burner tip used.

  Since raw gas burners pour fuel directly into the air stream, fuel and air contamination occurs simultaneously with combustion. Since the airflow does not change much with respect to the fuel flow, the setting of the air register of the natural draft burner must be changed after the firing rate has changed. Therefore, frequent adjustments may be necessary. In addition, many raw gas burners generate a luminous flame.

  A premix burner mixes some or all of the fuel with some or all of the combustion air prior to combustion. The airflow is sufficiently proportional to the fuel flow because premixing is performed by using the energy present in the fuel flow. As a result, less adjustment is therefore required. Premixing fuel and air also facilitates achieving the required flame characteristics. Because of these properties, premix burners are often compatible with various steam cracking furnace configurations.

  Floor burning premix burners are used in many steam crackers and steam reformers. The main reason is that this burner has the ability to create a relatively constant heat distribution profile in the tall radiant section of the furnace. Since the flame is non-luminous, temperature management of the metal tube is facilitated. The premix burner is therefore the chosen burner for such a furnace. Premix burners can also be designed for special heat distribution profiles or flame shapes required in other types of furnaces.

  In gas-fired industrial furnaces, NOx is formed by the oxidation of nitrogen drawn into the burner along with the combustion air stream. It is widely believed that NOx formation occurs primarily in the flame region where both high temperature and abundant oxygen are present. Since ethylene furnaces are among the highest temperature furnaces used in the hydrocarbon processing industry, the burners within these furnaces tend to naturally release high levels of NOx.

  One technique for reducing NOx that has become widely accepted in the industry is known as staging. In staging, the primary flame zone is either air deficient (rich fuel) or fuel deficient (lean fuel). Balancing air or fuel is poured into the burner in the secondary flame zone or elsewhere in the combustion chamber. As is well known, a combustion zone in a multi-fuel state or a lean fuel state does not form NOx more than an air-fuel ratio that is closer to stoichiometry. Staging has been found to reduce the peak temperature in the primary flame zone and change the burning rate to reduce NOx. Since NOx formation increases exponentially with gas temperature, NOx emissions can be drastically suppressed by lowering the peak flame temperature even if it is small. However, this must be balanced with the fact that the radiant heat transfer decreases as the flame temperature decreases, while the carbon monoxide (CO) emissions, i.e., the indication of incomplete combustion, is of course actually increased. To do.

  With regard to premix burners, the term “primary air” means air premixed with fuel, and “secondary air”, in some cases “tertiary air” is for balance that is necessary for proper combustion. Means air. In the raw gas burner, the primary air is air that cooperates at a position closer to the fuel, and the secondary and tertiary air are air that cooperate at a position away from the fuel. The upper limit of flammability means a mixture (multi-fuel) containing the maximum fuel concentration at which a flame can propagate.

  Therefore, one set of techniques is to use a staged air or staged fuel burner that lowers the flame temperature, at a distance from stoichiometric conditions (either multi-fuel or multi-air), and the flame is Lower flame temperatures are achieved by performing initial combustion with the remaining air or fuel added only after radiating some heat to the fluid being heated in the furnace.

  Another technique for achieving lower flame temperatures involves diluting the mixture with an inert material. Combustion exhaust gas (product of combustion reaction) or steam is a commonly used diluent. Such burners are respectively classified as FGR (combustion exhaust gas recirculation) burners and steam injection burners.

U.S. Pat. US Pat. No. 5,092,761 discloses a method and apparatus for reducing NOx emissions from a premix burner by recirculating flue gas. The combustion exhaust gas is pulled through the pipe by the suction effect of the fuel gas and the combustion air passing through the venturi pipe portion of the burner pipe from the furnace to the pipe. The combustion exhaust gas is mixed with the combustion air in the primary air chamber before combustion, and the oxygen (O ₂ ) concentration of the combustion air in the primary air chamber is diluted to lower the flame temperature, thereby suppressing the release of NOx. .

  U.S. Pat. Analysis of the type of burner disclosed in US 5,092,761 reveals that the flue gas recirculation (FGR) ratio is in the range of approximately 5-10%.

The FGR ratio is determined as follows.

FGR ratio (%) = 100 [G / (F + A)]
Here, G is the combustion exhaust gas (lb) pulled into the venturi, F is the fuel (lb) burned in the burner, and A is the air (lb) pulled in the burner.

  The ability of this type of existing burner to generate higher FGR ratios is limited by the suction capability of the fuel orifice / gas spud / venturi combination. By further closing the primary air damper, it is possible to generate a lower pressure than the primary air chamber and increase the FGR ratio. However, when the FGR ratio is increased, the flame is more likely to be caught in the FGR duct, raising the combustion temperature, which may increase NOx and cause damage to the metal part.

  Commercial experience and models have shown that the flame tends to be pulled into the FGR duct when the flue gas recirculation rate is increased. It is this phenomenon that often reduces the amount of flue gas recirculation. As the flame (flame) enters the flue gas recirculation duct directly, the temperature of the burner venturi tends to rise, which increases the flame speed and reduces the NOx reduction effect of the recirculated flue gas. From an operational point of view, the flue gas recirculation rate needs to be lower in order to keep flames out of the FGR duct in order to maintain the life of the metal FGR duct.

  Therefore, what is needed is a burner for fuel combustion, and the amount of FGR can be increased without causing a problem that a flame is caught in the FGR duct, and the emission of NOx can be further reduced. It is a burner for fuel combustion.

  The present invention relates to burners used in furnaces such as in steam cracking. The burner is located in the first flame opening of the furnace. The burner is a primary air chamber and a burner pipe, a burner tip provided at a downstream end, an upstream end in fluid communication with the primary air chamber, and a downstream end of the burner pipe, and combustion of fuel is downstream of the burner tip. At least one having a burner tube including a burner tip directed to the first flame opening of the furnace as occurs at a first end located at the second opening of the furnace and a second end opening to the primary air chamber. The flue gas recirculation duct, the first flame opening, and the first end of the flue gas recirculation duct extend into the furnace to substantially pass the flow path between the first flame opening and the first end. A wall that is long and substantially provides a barrier to flow.

  In addition to the use of the walls described above, the present invention effectively moves the FGR duct inlet further away from the flame to avoid or at least minimize the entrainment of the flame. Therefore, the amount of combustion exhaust gas recirculation can be increased, the overall flame temperature can be lowered, and NOx production can be suppressed.

  The invention is further described below with reference to the accompanying drawings, which illustrate various embodiments of the invention as non-limiting examples.

  Although the present invention will be described with reference to a burner for use in a furnace or industrial furnace, it will be apparent to those skilled in the art that the teachings of the present invention can be applied to other processing elements such as, for example, boilers. Accordingly, it should be understood herein that the term “furnace” means a furnace, boiler, and other usable processing elements.

  Referring to FIGS. 1-3, the burner 10 includes a self-supporting burner tube 12 located in a well provided in the hearth 14. The burner tube 12 includes an upstream end 16, a downstream end 18, and a venturi tube portion 19. The burner tip 20 is provided at the downstream end 18 and is surrounded by an annular tile 22. The fuel orifice 11 (which can be located in the gas spud 24) is located at the upper end of the gas fuel riser 65 and is located at the upstream end 16 to introduce fuel into the burner tube 12. Fresh air or ambient air is introduced into the primary air chamber through opening 80 via conditioning damper 28 and mixed with fuel at upstream end 16 of burner tube 12 and passes upward through venturi section 19. To do. Fuel and fresh air combustion occurs downstream of the burner tip 20.

  A plurality of air ports 30 (FIGS. 2, 3A and 3B) begin in the secondary air chamber 32 and pass through the hearth 14 into the furnace. Fresh air or ambient air enters secondary air chamber 32 via conditioning damper 34 and enters the furnace via stage air inlet 30 as described in US Pat. No. 4,629,413 for secondary combustion. That is, stage combustion is performed.

  Unmixed cold fresh or ambient air that enters the secondary air chamber 32 through the damper 34 and enters the furnace through the air port 30 is also burned by the effect of fuel suction through the venturi section 19. It is pulled into the primary air chamber via an exhaust gas recirculation (FGR) duct 76. In the case of illustration, the duct 76 is a metal FGR duct.

  As shown in FIG. 1, in one aspect of the present invention, the FGR duct 76 is tilted outward at the inlet 84 so that the opening 82 of the FGR duct 76 is physically further away from the bottom of the burner tip 20. Thus, this tilted FGR duct inlet 84 prevents, or at least reduces, burner flames from being entrained in the FGR duct. In this embodiment, the burner 10 can provide high-speed flue gas recirculation (FGR). Such higher flue gas recirculation (FGR) rates, in turn, reduce overall flame temperature and NOx production.

  Referring to FIGS. 3A and 3B, the flame opening 23 is circular with a radius R, and in order to prevent the flame from being entrained in the duct opening 82, the lateral distance d of the duct opening 82 from the flame opening 23 is It is 0.5R or more. The fact that the duct inlet 84 is inclined outwards also allows the relatively small burner box 17 to be used continuously. Note that such FGR burners can be on the order of 6 feet in height (about 1.8 m to 2.1 m) and on the order of 3 feet in width (about 0.9 m to 1.2 m).

  Referring to FIGS. 2 and 5, in addition to using fuel gas as a diluent, another technical means for achieving lower flame temperatures through dilution is through water vapor radiation. This is achieved via the water vapor radiating tube 15. Water vapor may be emitted to the primary air chamber or the secondary air chamber. Preferably, water vapor is radiated upstream of the venturi tube portion 19.

  In an optional embodiment of the invention, the effective distance between the opening 82 of the FGR duct 76 and the bottom of the burner flame is increased. In this embodiment, a physical wall 95 is provided between the burner tip 20 and the opening 82 of the FGR 76. Wall 95 also prevents, or at least reduces, burner flames from being entrained in FGR duct 76, thus providing higher speed flue gas recirculation (FGR) to burner 10. Such higher speed flue gas recirculation in turn reduces overall flame temperature and NOx production. In accordance with the teachings of the present invention, the wall 95 can be straight (straight) as shown in FIG. 3A, or can be curved, as shown in FIG. Other shapes can be used, as will be clear to the user.

For example, the fuel gas containing 10-15% O ₂ is preferably 5-15% O ₂ , more preferably 2-10%, due to the suction effect of the fuel passing through the burner tube 12 venturi portion 19. It is pulled from near the hearth via the FGR duct 76 with O ₂ , particularly preferably 2-5% O ₂ . In this way, the primary air and the fuel gas are mixed in the primary air chamber that is in front of the combustion zone. Thus, the amount of inert material mixed with the fuel increases and lowers the flame temperature, thereby reducing NOx emissions.

  Closing the damper 28 in whole or in part limits the amount of fresh air drawn into the primary air chamber 26, thereby providing the vacuum necessary to pull the fuel gas from the hearth.

  Advantageously, a mixture of 20% to 80% fuel and 20% to 80% ambient air should be pulled through the flow path (FGR duct) 76. It is particularly preferred to use a mixture of 50% fuel and 50% ambient air. This preferred fuel to ambient air ratio is achieved by proper installation and design of the FGR duct 76 relative to the air inlet 30. That is, changing the geometric conditions of the air port 30 (this includes, but is not limited to, the distance of the air port from the burner tube, the number of air ports, and the size of the air ports) And the desired ratio of ambient air can be obtained.

  Optionally, one or more to increase the propulsive force provided by the venturi tube portion 19 to direct the flow of fuel, water vapor and fuel gas, air, and mixtures thereof into the burner tube 12. The water vapor discharge pipe 15 is arranged in the flow direction.

  Now, another embodiment of the present invention will be discussed with reference to FIGS. In this embodiment, the burner 10 includes a free-standing burner tube 12 located in the well of the hearth 14. The burner tube 12 includes an upstream end 16, a downstream end 18, and a venturi tube portion 19. The burner tip 20 is located at the downstream end 18 and is surrounded by an annular tile 22. A fuel orifice 11 (which can be located in the gas spud) is located at the upper end of the gas fuel riser 65 and at the upstream end 16 to direct fuel to the burner tube 12. Fresh air or ambient air is directed into the primary air chamber 26 via the regulating damper 28 and mixed with fuel at the upstream end 16 of the burner tube 12 and passes upwardly through the venturi tube section 19. The combustion of fuel and fresh air occurs downstream of the burner tip 20.

  A plurality of air ports 30 (FIGS. 5 and 6) begin in the secondary air chamber 32 and pass through the hearth 14 and into the furnace. Fresh air or ambient air enters secondary air chamber 32 via conditioning damper 34, passes through stage air inlet 30 and enters the furnace as described in US Pat. No. 4,629,413, ie secondary combustion. Causes combustion.

  The unmixed cold fresh air or ambient air that enters the secondary air chamber 32 via the damper 34 and enters the furnace through the air port 30 also causes the fuel to pass through the venturi section 19. Due to the suction effect, the air is pulled into the primary air chamber 26 through the flow path (FGR duct) 76. The flow path 76 is a metal FGR duct in the case of illustration.

  Referring to FIGS. 4-7, the wall 60 surrounds the burner tip 20 at the downstream end 18 of the burner 12 and surrounds the bottom of the flame downstream of the burner tip 20 and the second opening (FGR duct) 76 of the furnace. And a barrier between the at least one air port 30.

  In one embodiment of the invention, the wall 60 is perforated so that fuel gas and air do not penetrate it. In another embodiment of the present invention, the wall 60 has a plurality of wall holes 61 spaced around its periphery. In the illustrated embodiment, the opening 61 has a rectangular shape, and is arranged at the bottom of the wall so as to be spaced along the periphery of the wall 60. The advantage of using a plurality of wall openings 61 is in the arrangement of those openings, which is optimized to reduce the amount of oxygen from the stage air inlet 30 to reach the flame, and the oxygen to the flame Reduce the interference level. As will be appreciated by those skilled in the art, each wall opening is arranged to maximize the effective flow path from the air port 30 to the flame when arranged in this manner. However, the flue gas is advantageously allowed to enter the flame, making it possible to reduce the NOx emission level.

  According to a preferred embodiment of the present invention, each air port 30 has two wall openings 61 adjacent to each other in order to minimize the amount of oxygen flowing from the air ports 30 through the wall openings 61 to the bottom of the flame. Between the two.

  An observation and illumination port 50 (FIG. 5) allows a luminaire (not shown) to access the interior of the burner 10.

  Reference is now made to FIGS. 8 and 9 (where like numbers are used for like elements), which shows another embodiment of the present invention. In this embodiment, the above-described bulkhead and inclined duct teachings of the present invention may be applied with respect to a furnace having one or more burners and using an external FGR duct in fluid communication with the furnace exhaust gas 300. it can. One skilled in the art will appreciate that there are several burners 310 in the furnace, all of which can supply the furnace exhaust to the external FGR duct 376. It will be appreciated that the wall 60 surrounding the burner tip 20 at the downstream end 18 of the burner tube 12 provides a barrier between the flame bottom at the burner tip 20 and the at least one air port 30.

  Advantages similar to those described above through the use of the flue gas recirculation system of the present invention are achieved in a flat frame burner, as described below with reference to FIGS. 10 and 11 show a rat frame burner configuration similar to the new burner configuration shown in FIG. 1, while FIGS. 12 and 13 show a rat frame burner configuration similar to the new burner configuration shown in FIG.

Burner 110 includes a self-supporting burner tube 112 located in the well of hearth 114. Burner tube 112 includes an upstream end 116, a downstream end 118, and a venturi tube portion 119. The burner tip 120 is provided at the downstream end 118 and is surrounded by a peripheral tile 122. A fuel orifice 111 (which can be disposed within the gas spud 124) is disposed at the upstream end 116 to introduce fuel into the burner tube 112. Fresh or ambient air can be introduced into the primary air chamber 126 and mixed with fuel at the upstream end of the burner tube 112. Fuel and fresh air combustion occurs downstream of the burner tip 120. Fresh secondary air enters the secondary air chamber 132 via the damper 134. In order to recirculate the combustion exhaust gas from the furnace to the primary air chamber, the combustion exhaust gas recirculation flow path 176 extends through the furnace floor to the primary air chamber 126, so that the combustion exhaust gas is opened through the damper 128. Mixed with fresh air drawn from 180 to the primary air chamber. For example, fuel containing 0-15% O ₂ is drawn through the flow path 176 due to the suction effect of fuel through the venturi portion 119 of the burner tube 112. Primary air and fuel gas are mixed in the primary air chamber before the combustion zone.

  In operation, fuel orifice 111 (which is disposed in gas spud 124) discharges fuel into burner tube 112, where the fuel is mixed with primary air, recirculated flue gas, or mixtures thereof. The The fuel, recirculated flue gas, primary air, or mixture thereof is then discharged from the burner tip 120. The mixture in the venturi section 119 of the burner tube 112 remains below the multi-fuel flammability limit, i.e., there is insufficient air to support combustion. Most of the secondary air is added a finite distance away from the burner tip 120.

  Optionally, one or more steam to introduce the flow of fuel, steam and fuel gas, air, and mixtures thereof into burner tube 112 by increasing the thrust provided by venturi section 119. A radiation tube 115 may be provided.

  Referring now to FIGS. 10 and 11 together with the previous embodiment, the FGR duct 176 may be inclined outwardly at the inlet 184 such that the opening 182 of the FGR duct 176 is physically more spaced from the bottom of the burner tip 120. Good. Accordingly, the inlet 184 in the inclined FGR duct prevents or at least reduces burner flames from being entrained in the FGR duct 176. This achieves a higher flue gas recirculation (FGR) rate provided to the burner 110. These higher FGR rates, in turn, reduce the overall flame temperature and NOx production.

  The outward slope at the inlet 184 also allows continuous use of a relatively small burner box 117. Note that such an FGR burner can be on the order of 6 feet in height and 3 feet in width.

  Continuing with FIGS. 10 and 11, the advantages of the present invention with respect to the flat frame burner embodiment are further enhanced by increasing the effective distance between the opening 182 of the FGR duct 176 and the bottom of the burner flame. In this embodiment, the physical wall 195 described above is installed between the burner tip 120 and the opening 82 of the FGR duct 176. This wall may also prevent or at least reduce the burner flame from entraining in the FGR duct 176, thus providing the burner 110 with a higher flue gas recirculation (FGR) rate. These higher FGR rates, in turn, reduce overall flame temperature and NOx production.

  With respect to the flat frame burner embodiment shown in FIGS. 12 and 13 (similar to the embodiment of FIG. 4), the wall 160 includes a flame bottom at the burner tip 120, a furnace second opening 176 and the at least one said In order to provide a barrier between both of the air ports (not shown), the periphery of the burner tip 120 provided at the upstream end 116 of the burner tube 112 is surrounded. Wall 160 reduces the amount of oxygen that flows into the bottom of the flame.

Example 1
To illustrate the advantages of the present invention, without providing a wall surrounding the periphery of the burner tip to provide a barrier between the bottom of the flame of the present invention and both the flue gas recirculation duct and the secondary air port, the premix burner of performing flue gas recirculation of the type described in U.S. Patent No.5,092,761 _{H 2} (hydrogen) 30%, using a fuel gas containing natural gas 70% 6,119,000BTU / hr ( It was operated at a burning rate of 5,800,000 BTU / hr) . The burner NOx release value was 49 ppm.

Example 2
The premix burner of Example 1 was provided with a wall surrounding the tip of the burner to provide a barrier between the bottom of the flame of the present invention and both the flue gas recirculation duct and the secondary air port. The burner was operated at a burning rate of 6,135,000 BTU / hr using a fuel gas containing 30% H _{2 and} 70% natural gas. A NOx release value of 46.11 ppm was detected.

  Computer-based hydrodynamic model analysis and actual tests with the above-mentioned commercial units showed that the existing structure without the wall surrounding the burner tip has a high oxygen concentration zone above the FGR duct in the furnace. . Some of this oxygen flows into the bottom of the flame, and it is believed that a large amount of oxygen interferes with the bottom of the flame, resulting in high NOx production. While such co-currents cause favorable mixing and high burning rates, it is believed that this effect is likely to result in higher temperatures and higher NOx emission levels. In an effort to solve this problem, it has been discovered that using a wall between the flame and the oxygen recirculation zone in accordance with the present invention greatly reduces the interference between the flame and the oxygen recirculation zone.

  Although several burners of the present invention have been described with respect to a bed burning hydrocarbon steam furnace, these burners can also be used to perform other reactions in the furnace.

  It should also be noted that the flue gas recirculation system and methodology described here also has the utility that only flue gas is mixed with fuel gas at the inlet of the burner tube in a raw gas burner having a premix burner. . In fact, premix stage air burners of the type described in detail here can be operated with the damper door of the primary air chamber closed, with very satisfactory results.

  Although the invention has been described with reference to specific means, materials and embodiments, the invention is not limited to these specifically disclosed, but includes all equivalents to the claims. It is understood.

1 is a partial cross-sectional side view of an embodiment of a burner according to the present invention. It is a partial cross section side view which follows the 2-2 line of FIG. 3A is a partial cross-sectional side view taken along line 3-3 in FIG. FIG. 3B shows another embodiment of the present invention that employs a curved wall instead of the straight wall of FIG. 3A. FIG. 6 is a partial cross-sectional side view of another embodiment of a burner comprising a septum according to the present invention. It is a partial cross section side view which follows the 5-5 line of FIG. It is a top view which follows the 6-6 line of FIG. It is a perspective view of the partition according to this invention. It is a side view of an embodiment of the present invention using an external FGR. It is a top view of an embodiment of the invention using an external FGR. It is a partial cross section side view of the embodiment of the flat frame burner of the present invention. FIG. 11 is a partial cross-sectional side view of the embodiment of the flat frame burner of FIG. 10 taken along line 10-10 of FIG. It is a partial cross section side view of another embodiment of the flat frame burner of this invention. FIG. 13 is a partial cross-sectional side view of the embodiment of the flat frame burner of FIG. 12 taken along line 13-13 of FIG.

Claims (18)

A stage air burner (10,310,100),
(A) a primary air chamber (26, 126);
(B) a burner tube (12, 112) located in the first flame opening of the hearth (14, 114) , comprising (i) a downstream end (18, 118), and (ii) the primary air chamber ( 26, 126) and an upstream end (16, 116) in fluid communication, and (iii) a burner tip (20, 120) provided at the downstream end (18, 118) of the burner pipe (12, 112). A burner tube including a burner tip (20, 120) directed to the first flame opening of the furnace so that fuel combustion occurs downstream of the burner tip;
(B2) tiles (22, 122) surrounding the burner tip (20, 120) and forming the first flame opening;
(C) a first end located in a second opening laterally spaced from the first flame opening of the hearth (14, 114) and a second open to the primary air chamber (26, 126); At least one flue gas recirculation duct (76, 376, 176) having an end;
; (D) hearth a wall provided perpendicularly to the (14, 114) (95,60,195,160), said hearth (14, 114) prior to said first flame opening from Symbol a wall extending into the furnace between the first end before Symbol of flue gas recirculation duct (76,376,176),
(E) a secondary air chamber (32, 132) in fluid communication with at least one air port (30, 130);
(F) a venturi tube (19, 119) for pulling the combustion exhaust gas from the furnace via the combustion exhaust gas recirculation duct (76, 376, 176);
Including burner (10,310,100). The burner (10, 310, 100) of claim 1, wherein the venturi tube (19, 119) is part of a burner tube (12, 122). At least one released to the primary air chamber (26, 126) to limit the amount of air flowing into the primary air chamber (26, 126), thereby providing a vacuum to pull flue gas from the furnace. The burner (10, 310, 100) according to claim 1 or 2 , further comprising two first adjustable dampers (28, 128). At least one second adjustable damper (34, 134) released to the secondary air chamber (32, 132) to limit the amount of air flowing into the secondary air (32, 132); Burner (10, 310, 100) according to any one of claims 1 to 3 , comprising: The burner (10, 310, 100) according to claim 4 , wherein the air port (30, 130) is plural and the secondary air chamber (32, 132) is in fluid communication with the plurality of air ports. The first end of the at least one flue gas recirculation duct (76, 376, 176) is an effective distance from the first opening to minimize entrainment of a burner flame to the second opening. spaced claims 1 are to according to any one of 5 the burner (10,310,100). The first flame opening is circular with a radius R, and the distance that the second opening is laterally spaced from the first flame opening substantially entrains the burner flame into the second opening. The burner (10, 310, 100) according to any one of claims 1 to 6 , wherein the burner is 0.5R or more. The at least one flue gas recirculation duct (76, 376, 176) extends vertically from the primary air chamber (26, 126) and is angled outward from the first flame opening at the first end. The burner (10, 310, 100) according to any one of claims 1 to 7 , wherein the burner is connected to the second opening spaced laterally from the first flame opening. It said wall (60, 160) is a burner according to any one of claims 1 to 8 surround the burner tip (20, 120) (10,310,100). 10. Burner according to claim 9 , wherein the wall (60, 160) has a plurality of wall openings (61, 161). The burner of claim 10 , wherein the plurality of wall openings (61, 161) are located at the bottom of the wall. The burner ( 10 , 310, 100) of claim 10 , wherein the wall opening (61, 161) is rectangular . The wall extending into the furnace between the first flame opening and the first end of the flue gas recirculation duct (76,376, 176) is a partial wall (95,195). 1 burner (10, 310, 100). A partial wall (95, 195) extending into the furnace between the first flame opening and the first end of the flue gas recirculation duct (76, 376, 176) is curved and the burner 14. Burner (10, 310, 100) according to claim 13 , wherein the burner (10, 310, 100) is a wall partially surrounding the tip (20, 120). The burner according to any one of claims 1 to 14 , wherein the burner is a premix burner. 16. A burner according to any one of the preceding claims, wherein the burner is a flat frame burner (100). Burner according to the furnace of any one of claims 1 to 16, which is a steam cracking furnace (10,310,100). At least one comprising steam emission pipe (15, 115) according to claim 1 to a burner according to any one of 17 (10,310,100).

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