JP2008116195A - Partial pre-mix flare burner and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flare burner that is particularly suitable for use in connection with ground flares and other types of flares in which it is important to control the height of the flame envelope. <P>SOLUTION: The flare burner includes a pre-mix zone including a pre-mix chamber into which air is entrained. A uniform mixture of fuel and air is formed in the pre-mix zone and caused to exit an air/fuel outlet in the top of the pre-mix chamber. In one embodiment, the amount of air in the fuel/air mixture that exits the air/fuel outlet is in excess of the stoichiometric amount of air required to support combustion of the fuel in the mixture. Fuel is injected around the perimeter of the air/fuel outlet, combustion is initiated and a flame envelope is created. By injecting a mixture of fuel and air that includes excess air into the center of the flame envelope, combustion of the central portion of the flame envelope is accelerated which allows more fuel to be flared with a given flame envelope height. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus and method for burning combustible waste gas and diverted fuel stock. In one embodiment, the present invention relates to ground flare burners, ground flares, and related methods.

  Flare apparatus and methods are used to burn and treat combustible waste gas and diverted fuel stock in various applications. For example, flare devices are typically located in production facilities, refineries, processing plants, etc., and exhausted combustible waste gases and / or ventilation, shutdown, abnormalities or emergencies in these facilities. Process the fuel stock stream split in between. It is usually desirable or essential to combust combustible waste gas and diverted fuel stock (hereinafter referred to as “fuel”) without generating smoke. Smokeless combustion is achieved by ensuring that the unoxidized soot does not form enough to separate from the flame. This is accomplished by mixing a sufficient amount of oxygen with the fuel so that it remains effective without making the mixture excessively fuel rich.

  In many applications, the length of the flame envelope formed by the flare is also important. Examples of flare types where a relatively short flame envelope is desirable are aesthetic flares (eg, pit-type closed flares), ground flares, and high-pressure flares in floating production facilities. In such flares, it is often necessary to make the flame invisible to the surrounding community. On the other hand, such flares must have the ability to burn large volumes of fuel at any given time. The length of the flame envelope tends to increase as the volume of fuel burned increases.

  Typical for applications where the amount of fuel to be burned at a given time varies from a relatively small volume to a very high volume (eg, over 1,000,000 pounds per hour (453,600 kg)) In addition, ground flare (also referred to as multi-point flare) is used. Multiple stage burners are used to accommodate changes in fuel volume and to allow the fuel to be burned in a smokeless state. The flow to each stage burner is controlled by a control system that is responsive to the pressure and volume of the fuel to be combusted. Thus, sufficient pressure can be used for the operation of each burner to ensure that the proper amount of air is taken in and that sufficient mixing of the air and fuel occurs. Smokeless combustion in the range is guaranteed.

  Ground flare systems are generally spread over a large area, for example 3 acres, and are surrounded by large fences or other enclosures. The enclosure functions to shield personnel and animals from the flame area and to minimize radiation, visibility and noise to the surrounding area. The enclosure is typically made of metal or some other thermorefractive material and is 20 to 60 feet (about 6.1 m to about 18.3 m) in height. Thus, the construction and maintenance of the enclosure can be costly.

  Burner spacing and fuel flow in the ground flare system are also important. The burners need to be placed close enough together to produce cross ignition and packed closely together as a whole to reduce the overall dimensions of the system and the surrounding enclosure. In view of cost, it is desirable that the number of ignition pilots be minimal. A typical unit includes one pilot at the end of each row of burners. However, the burners should not be so close to each other that they obstruct airflow and prevent smokeless combustion, or coalesce the flame into a fireball that exceeds the height of the enclosure. Also, the fuel flow must be controlled so that the individual flame height does not exceed the enclosure height.

  One type of ground flare burner that has been used to date includes a plurality of diffusing jets for supplying fuel and drawing in the air necessary for combustion. These jets are injected into the atmosphere at a rate sufficient to draw combustion air into the jet. When the fuel is ignited, air from the surrounding environment is taken laterally from above the fuel discharge point. As the flow velocity is reduced, the buoyancy effect of the hot gas acts to facilitate the overall fuel and air mixing process, which allows the remaining fuel to be burned completely.

  The entire flame envelope formed by using only a diffusing jet to supply the fuel and take in the air necessary for combustion laterally contains a high concentration of fuel cores. This fuel core is maintained until the outer portion of the flame envelope begins to burn. As the outer portion of the flame envelope burns, air can enter the inner region of the flame envelope, thereby completing the oxidation process. Unfortunately, due to the interaction of the individual fuel jets, the high concentration of fuel cores formed at the center of the flame envelope increases the fuel flow rate to provide greater throughput and increases the length of the flame envelope. And / or without the generation of smoke. Increasing the length of the flame envelope often requires a higher enclosure height surrounding the ground flare, which can significantly increase the cost of the enclosure.

  The present invention provides a flare burner useful for use in ground flares, high pressure flares, and other types of flare apparatus. For example, the flare burner of the present invention overcomes the problems associated with ground flare that have been used so far. The present invention also provides a ground flare apparatus and method for burning fuel in a flare burner.

  According to the present invention, a flare burner is provided that can burn a high volume of fuel in a relatively short flame envelope. The reduction in the length of the flame envelope provides many advantages. For example, the height of the enclosure around the ground flare can be reduced, or the volume of fuel that can be burned at the height of the existing enclosure can be increased.

  The flare burner of the present invention includes a premix zone that includes a premix chamber, an auxiliary fuel inlet for injecting fuel into the premix zone, and a main fuel outlet. Preferably, the inventive flare burner further comprises a fuel supply conduit in fluid communication with the auxiliary fuel inlet and the main fuel outlet.

  The premix chamber includes a top, a bottom, and sidewalls that connect the top to the bottom. The sidewall includes an inner surface and an outer surface. An air inlet is located at one of the bottom and side walls, and an air / fuel outlet is located at the top.

  The auxiliary fuel inlet, relative to the premix zone, the injection of fuel from the auxiliary fuel inlet into the premix zone draws air into the premix zone, thereby forming a mixture of fuel and air in the premix zone And is positioned such that it exits from the air / fuel outlet of the premix chamber.

  The main fuel outlet is positioned relative to the top of the premix chamber such that fuel can be injected from the main fuel outlet around the circumference of the air / fuel outlet of the premix chamber. In one embodiment, the main fuel outlet is spaced outwardly from the premix chamber to provide a space between the outer surface of the premix chamber sidewall and the main fuel outlet. As discussed further below, this space allows fresh air to be taken from below the burner to a point near the fuel port located inside the main fuel outlet. Promoting mixing by such air entrapment can be important in some applications (eg, when heavy hydrocarbons or unsaturated fuels are burned).

  The fuel supply conduit directs fuel to the auxiliary fuel gas inlet and the main fuel gas outlet. Fuel can be supplied to the auxiliary fuel inlet and the main fuel outlet at the same or different pressures depending on the application.

  The flare burner of the present invention may further include a fuel film disposed around the outer periphery of the premix chamber. The fuel membrane includes a fuel inlet and is in fluid communication with the main fuel outlet. In some embodiments, the fuel membrane is also in fluid communication with the auxiliary fuel inlet. To provide the air intake space described above, the fuel film can be spaced from the outer surface of the side wall of the premix chamber to the outside.

  Depending on the particular construction of the inventive flare burner, the premixing zone can consist of only the premixing chamber, or the area below and / or above the actual premixing chamber also includes the premixing chamber. be able to. For example, if the air inlet of the premix chamber is at the bottom of the premix chamber and the auxiliary fuel inlet is spaced below the air inlet, the fuel and air are the air inlet and the premix. Begin mixing below the chamber. Also, fuel and air typically continue to be mixed above the air / fuel outlet located at the top of the premix chamber prior to ignition and combustion in the combustion zone.

  The premix chamber and fuel film can be formed in a variety of shapes and sizes. In one embodiment, the premix chamber and the fuel film have a circular cross section. In another embodiment, the premix chamber and the fuel film have a rectangular cross section.

  In order to increase the air uptake caused by injecting fuel into the premix zone through the auxiliary fuel inlet, the inner surface of the premix chamber can include a section that is a Coanda surface. The auxiliary fuel inlet is positioned relative to the premixing chamber such that fuel can be injected from the auxiliary fuel inlet onto the Coanda surface. The fuel adheres to and travels along a passage on the Coanda surface to form a relatively thin membrane that allows more air to be taken into the premixing chamber and the air and fuel. Cause more thorough mixing in the premix chamber.

  The ratio of the length of the premix chamber to the hydraulic diameter (inner diameter) (inner hydraulic diameter) is about 0.25: 1 to about 4: 1. Units where the ratio of premix chamber length to hydraulic diameter (inner diameter) is greater than 4: 1 will function with additional benefits, but will generally be very costly. In one embodiment, the ratio of premix chamber length to hydraulic diameter (inner diameter) is about 1: 1 to about 3: 1. In another embodiment, the ratio of premix chamber length to hydraulic diameter (inner diameter) is about 1: 1 or less. Premixing chambers with relatively short lengths can cause ground combustion and other flaring devices where burner length (ie height) is important, or highly reactive fuels can cause internal combustion. May be advantageous in certain applications. Also, in some constructions, the fuel allows a uniform mixing of air and fuel to be achieved even if the length of the premix chamber is a very low ratio to the hydraulic diameter (inner diameter). Under the circumstances (eg, multiple small jets; high pressure).

  The ground flare of the present invention includes a plurality of flare burners, a fence or other enclosure extending around the flare burner, and a fuel supply line for supplying fuel to the flare burner. At least one of the flare burners is the flare burner of the present invention described above.

  The present invention also includes a method of combusting fuel with a flare burner, wherein the combusted fuel is injected into the combustion zone through the fuel outlet of the burner to form a flame envelope to burn the fuel. Ignited. In accordance with the method of the present invention, a portion of the fuel is introduced into the premixing zone of the flare burner so that air is taken into the premixing zone and produces a mixture of air and fuel in the premixing zone. . A mixture of air and fuel is injected from the premix zone into the center of the flame envelope.

  The amount of air taken into the premix zone and injected into the center of the flame envelope is preferably the stoichiometric amount of air required to assist the combustion of fuel introduced into the premix zone At least about 15%. In some applications, a “fuel rich” mixture of fuel and air (ie, less than 100% of the stoichiometric amount of air required to assist combustion of fuel introduced into the premix zone) It is expedient to inject a mixture containing a quantity of air into the center of the flame envelope. However, in many applications, a “lean” mixture of fuel and air (ie, the stoichiometric amount of air required to assist combustion of fuel introduced into the premix zone). It is desirable to inject a mixture containing more than 100% air into the center of the flame envelope. In many applications, the amount of air taken into the premix zone and injected into the center of the flame envelope is the stoichiometry of air required to assist the combustion of fuel introduced into the premix zone. Range from about 125% to about 300% of the target amount.

  The amount of fuel introduced into the premix zone preferably ranges from about 5% to about 50% of the total amount of fuel burned by the flare burner. By injecting a premixed fuel stream into the center of the flame envelope in accordance with the method of the present invention, the flame envelope includes a combustion portion at the center as well as at the outer surface of the flame envelope. The resulting toroidal (donut-shaped) flame provides further mixing and turbulence, which results in a more uniform and rapid combustion of the flame envelope. As a result, the height of the flame envelope can be reduced, or the volume of fuel that can be burned in a given flame envelope can be increased. Other advantages are also achieved by the inventive flare burner and method.

  Accordingly, it is an overall object of the present invention to provide a flare burner and associated method capable of burning a high volume of fuel with a relatively short and uniform flame envelope.

  Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art from the following description of the preferred embodiment, when read with reference to the accompanying drawings.

  Referring now to the drawings, and in particular to FIGS. 1-3, a prior art ground flare burner is illustrated and is generally indicated by the numeral 10. Prior art burner 10 includes a burner casting 12 attached to a fuel riser 14. The burner casting 12 includes a central portion 15 and a plurality of fuel outlet arms 16 disposed concentrically around the central portion and on top of the riser 14. Each of the fuel outlet arms 16 includes one or more fuel ports 18. The fuel is supplied directly to the fuel port 18, i.e. the fuel is not initially premixed with air. Accordingly, the fuel jet (jet) formed by the port 18 is a diffusion fuel jet.

  FIG. 3 schematically shows a flame envelope 20 formed by the burner 10. Fuel (shown schematically by black arrows) is injected through the port 18 into the combustion zone 22 at a high velocity that draws air into the jet. Air from the surrounding environment is taken laterally from above the fuel discharge point. As the flow rate is reduced, the buoyancy action of the hot gas contributes to the overall mixing control of the fuel, which allows the combustion to take place completely. The entire flame envelope 20 has a length 23 and includes a high concentration fuel core 24. The fuel core 24 remains unoxidized until the outer portion 26 of the flame 22 begins to burn. Although the center of the flame envelope may include several air pockets 28, the amount of air in the air pockets is not sufficient to assist in uniform combustion of the fuel core 24. The high concentration fuel core 24 is substantially intact until sufficient exhaustion of the outer portion 26 of the fuel allows a sufficient amount of air to enter the inner boundary of the flame envelope and the oxidation process is completed. The state is kept. Unfortunately, the high concentration fuel core 24 of the flame envelope 20 makes it difficult to increase fuel flow to assist larger flames without increasing frame length and / or generating smoke. .

Flare Burner of the Present Invention Referring now to FIGS. 4-8, one embodiment of the flare burner of the present invention is illustrated and is generally designated 30. Flare burner 30 includes a premix zone 31 that includes a premix chamber 32, an auxiliary fuel inlet 34 for injecting fuel into the premix zone, a main fuel outlet 36, and a fuel supply conduit 38. As used herein and in the appended claims, “fuel” refers to the flare burner, flare apparatus of the present invention (eg, ground flare apparatus of the present invention) and waste gas burned by the method, By diverted fuel stock and / or other gas or liquid. For example, a heavy unsaturated fuel or a partial pressure of a saturated fuel may be in liquid form when it is saturated or has not reached saturation. As shown in FIG. 4, pilot 40 applies to burner 30 (to burners 130, 230, and 330, as described below) to initially ignite the fuel / air mixture released from the burner. Also).

  In the embodiment illustrated by FIGS. 4-8, the premix chamber 32 of the flare burner 30 provides the main part of the premix zone 31. A mixture of fuel and air (preferably a substantially uniform mixture) can be formed in a premix zone 31 that includes a premix chamber 32. As discussed below, the mixture formed in the premix zone 31 may be either fuel rich or fuel lean. The premixing chamber 32 includes a circular cross section and has a cylindrical shape. The premix chamber includes a top 42, a bottom 44, a sidewall 46 connecting the top to the bottom, an air inlet 48 disposed at the bottom 44, and an air / fuel outlet 50 disposed at the top 42. As shown, the top 42 and bottom 44 are open, thereby forming an air inlet 48 and an air / fuel outlet 50. As a result, each of the air inlet 48 and air / fuel outlet 50 also has a circular cross-section. The lower portion 52 of the premix chamber 32 is flared outwardly to increase the incoming fuel and air flow rates, resulting in a bell-shaped (rounded) shape in the lower section. Alternatively, the lower portion 52 of the premixing chamber 32 does not have an outwardly extending shape, that is, the entire premixing chamber has a uniform cylindrical shape. As best shown in FIG. 5, the premix zone 31 is a premix space 31 (a) below the premix chamber 32 (between the auxiliary fuel inlet 34 and the bottom 44 of the premix chamber and the air inlet 48). ), A premix chamber interior 31 (b), and a premix space 31 (c) just above the top 42 of the premix chamber and the air / fuel outlet 50. In the embodiment shown in FIGS. 4-9, the primary mixing of premixed air and fuel occurs in the interior 31 (b) of the premix chamber 32 and the premix space 31 (c).

  The ratio of the length (ie height) of the premix chamber 32 to the hydraulic diameter (inner diameter) is about 0.25: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. . The exact ratio of the length (ie height) of the premix chamber 32 to the hydraulic diameter (inner diameter) will depend somewhat on the type of fuel being burned and the pressure that can be used for intake and mixing. . In general, the longer the premixing chamber, the better the fuel and air can be mixed within the chamber. However, this advantage is balanced with cost and other considerations. In a preferred embodiment, the ratio of the length (ie, height) of the premix chamber 32 to the hydraulic diameter (inner diameter) is about 1.5: 1. As used herein and in the appended claims, the “hydraulic diameter (inner diameter)” is four times the area in the premix chamber divided by the perimeter of the inner surface of the side wall of the premix chamber. Means things.

  In the auxiliary fuel inlet 34, the fuel injection from the auxiliary fuel inlet into the premixing zone 31 takes air into the premixing space 31 (a) with respect to the premixing zone 31, and enters the premixing chamber 32 through the air inlet 48. So that a mixture of fuel and air (preferably a substantially homogeneous mixture) is formed in the premixing zone and discharged from the air / fuel outlet 50 in the upper part 42 of the premixing chamber. Placed in position. The fuel and air continue to be mixed in the premix space 31 (c). Combustion of the fuel and air mixture typically does not occur until the mixture exits from the air / fuel outlet 50 (generally a distance away from the air / fuel outlet). The distance from the air / fuel outlet 50 at which combustion occurs varies with the amount of air in the mixture and the rate at which the mixture is discharged from the air / fuel outlet. In some cases, short destage timing sequences can cause combustion in the premix zone (eg, in a short time, very low pressure scenario). As shown in FIGS. 6 and 7, the auxiliary fuel inlet 34 includes a central fuel injector 54 having one or more fuel ports 58 therein.

  An annular fuel film 60 is disposed around the outer periphery of the premixing chamber 32. The fuel membrane 60 connects to the fuel supply conduit 38 and is in fluid communication with the main fuel outlet 36. The fuel film 60 includes an open top 62, a bottom 64, and an outer side wall 66 and an inner side wall 67 that connect the top to the bottom. In the embodiment illustrated by FIGS. 4-8, the inner sidewall 67 of the fuel film 60 is also the sidewall 46 of the premix chamber 32. An annular seal 68 is attached to the bottom 64 of the fuel membrane 60 to ensure membrane integrity and extends around the side wall 46 of the premix chamber 32. In another embodiment (as illustrated in FIGS. 25-28 and described below), the fuel film 60 is annular between the outer surface of the side wall 46 of the premix chamber 32 and the main fuel outlet 36. In order to provide the above-mentioned space, it can be arranged with a space from the side wall 46 to the outside. This annular space allows air to be taken from the underside of the burner to a point near the fuel port 74 located inside the main fuel outlet 36. In this embodiment, the inner sidewall 67 of the membrane 60 is separated from the sidewall 46 of the premix chamber 32.

  The main fuel outlet 36 is positioned relative to the top 42 of the premix chamber such that fuel can be injected from the main fuel outlet 36 around the perimeter 69 of the air / fuel outlet 50 of the premix chamber. Has been. As best shown in FIG. 6, the main fuel outlet 36 includes an annular flat fuel injector body 70 having a plurality of fuel ports 74 therein. The fuel jet formed by port 74 is a diffusion fuel jet. An annular fuel injector body 70 is attached to the open upper portion 62 of the annular membrane 60 such that the fuel port 74 is disposed around the outer periphery 69 of the air / fuel outlet 50 of the premix chamber. The inner diameter and outer diameter of the annular membrane 60 and the inner diameter and outer diameter of the annular fuel injector body 70 are substantially the same. Fuel can be injected annularly around the outer periphery 69 of the air / fuel outlet 50 from the main fuel outlet 36 (ie, the annular fuel injector body 70). The ports 74 can be arranged with dimensions and spacing to control the manner in which fuel is injected from the ports (eg, direction and speed). This feature allows the shape and length of the entire flame envelope to be controlled in connection with fuel and air flow through the air / fuel outlet 50.

  As shown in FIG. 7, the diffusion fuel port 74 can be spaced from the fuel injector body 70 by a corresponding plurality of short gas risers or tip extensions 76 as required. By spacing the port 74 from the fuel injector body 70 using a riser 76, more air intake in the lateral direction can be obtained in some applications. The riser also allows the port structure and the fuel flow characteristics obtained with this structure to be mechanically changed as required.

  Another embodiment of an annular fuel injector body 70 is shown in FIG. In this embodiment, a plurality of fuel ports 74 are arranged in a strategically spaced manner around the outer periphery, the inner periphery, and the middle of the fuel injector body 70. This spacing of the fuel ports 74 around the fuel injector body 70 allows the intake passage between the jets to be utilized for better mixing and intake. As will be appreciated by those skilled in the art, the fuel injector body 70 can include various repetitions of the port 74. The particular port structure used will depend on various factors including the type of fuel being burned (including the molecular weight of the fuel stream, the calorific value, the chemical amount and the temperature) and the pressure that can be used in connection with these fuels. Will change accordingly.

  A fuel supply conduit 38 is in fluid communication with the auxiliary fuel inlet 34 and the main fuel outlet 36 to direct fuel to the inlet 34 and outlet 36. The fuel supply conduit 38 includes a main branch 80 having a first end 82 and a second end 84. The first end 82 includes a flange 86 for connecting the first end to a fuel source (as will be appreciated by those skilled in the art, these types of connections more typically include pipe sections. Formed by direct welding to merge into some other mechanical connection, which does not require a gasket (eg, gaskets between corresponding flanges are generally not able to withstand the radiant heat of the surrounding environment) . The second end 84 is connected to a corresponding inlet 88 in the outer sidewall 66 of the fuel film 60. The fuel supply conduit 38 also includes an auxiliary branch 90 that connects the fuel supply conduit to the auxiliary fuel inlet 34. The auxiliary branch 90 includes a first end 92 and a second end 94. The first end 92 is connected to the main branch 90 of the supply conduit 38. A connecting portion 96 connects the second end portion 94 to the auxiliary fuel inlet 34. Alternatively, a separate fuel supply conduit or riser (not a single integrated conduit or riser 38) can direct fuel to the auxiliary fuel inlet 34 and the main fuel outlet 36. Separate conduits or risers will typically extend from a common fuel header.

  The operation of the flare burner 30 will be described with reference to FIG. A portion of the fuel to be burned (shown schematically by a black arrow) is directed through the main branch 80 of the fuel supply conduit 38 to the fuel film 60 and the main fuel outlet 36. A portion of the combusted fuel is also introduced into the auxiliary fuel inlet 34 through the auxiliary branch 90 of the fuel supply conduit 38. Injection of fuel from the auxiliary fuel inlet 34 into the premixing zone 31 and the premixing chamber 32 draws air into the premixing space 31 (a) and through the air inlet 48 into the interior 31 (b) of the premixing chamber. And thereby forming a mixture of fuel and air (preferably a substantially uniform mixture) within the premixing zone, and the mixture is discharged from the air / fuel outlet 50. Fuel and air continue to be mixed for a short distance above the air / fuel outlet 50. The remaining fuel to be combusted is from the main fuel outlet 36 around the perimeter 69 of the premix chamber air / fuel outlet 50 and thus around the air / fuel mixture coming out of the premix chamber air / fuel outlet. Are injected in an annular shape. The burner preferably has the amount of air taken into the premix zone 31 containing the premix chamber 32 exceeds the stoichiometric amount of air required to burn the fuel injected into the premix zone. Designed and operated as such. This excess air is provided in the center of the flame envelope to burn the center fuel. However, as will be described further below, in some applications, the burner burns fuel injected into the premix zone 31 with the amount of air drawn into the premix zone 31 including the premix chamber 32. Designed and operated to be below the stoichiometric amount of air required for it (still still combustable). A "fuel rich" mixture of fuel and air (ie, a mixture containing less than the stoichiometric amount of air required to assist combustion of the fuel introduced into the premix zone) Injecting into the center of the flame envelope is desirable in some applications.

  FIG. 24 schematically illustrates the flame envelope 100 formed by the flare burner 30 (and the burners 130, 230, and 330 described below). As shown, excess air is injected from the premix chamber 32 into the center 102 of the flame envelope 100. The excess air shown by the air pocket 103 in FIG. 24 mixes with the fuel in the central portion 102 of the flame envelope 100 and actually forms two initial flammable zones, zones 104 (a) and 104 (b). To do. If no air is supplied in this way, the fuel in the center 102 of the flame will contain oxidant (until the outer portion 105 of the flame envelope begins to burn and the next fuel layer can contact the air). Air). Supplying air to the central portion 102 of the flame envelope 100 not only forms a flammable central zone, but also separates the flame because the inner combustion zone expands with the heat of combustion. By adding another combustion flame inside the larger main flame, considerable turbulence is further created, which promotes fuel core mixing and dispersion. The result is a more uniform and quicker combustion of the flame envelope, which shortens the overall length of the flame or allows much more fuel to be burned with the same flame length. . As the amount of excess air supplied to the central portion 102 of the flame envelope 100 increases, the flame length decreases or the volume of fuel that can be burned at a given flame height increases. For example, as shown in FIG. 24, the flame envelope 100 has a length 106 that is substantially shorter than the length 23 of the prior art flame envelope 20 shown in FIG. 3 for the same amount of fuel.

  Referring now to FIGS. 9-12, a second embodiment of the flare burner of the present invention is illustrated, which is indicated generally by the reference numeral 130. Similar to another embodiment of the inventive flare burner, the flare burner 130 includes a premix zone 131 that includes a premix chamber 132, an auxiliary fuel inlet 134 for injecting fuel into the premix zone, and a main fuel outlet 136. And a fuel supply conduit 138. A pilot (as shown in FIG. 4) may be associated with the burner 130 to initially ignite the fuel and air mixture released by the burner.

  In the embodiment shown in FIGS. 9-12, the premix chamber 132 of the flare burner 130 provides the main part of the premix zone 131. A mixture of fuel and air (preferably a substantially uniform mixture) may be formed in a premix zone 131 that includes a premix chamber 132. As discussed below, the mixture formed in the premix zone 131 may be either fuel rich or fuel lean. The premixing chamber 132 includes a circular cross section and has a cylindrical shape. The premix chamber includes a top 142, a bottom 144, a sidewall 146 connecting the top to the bottom, an air inlet 148 disposed at the bottom 144, and an air / fuel outlet 150 disposed at the top. As shown, the top 142 and bottom 144 are open, thereby forming an air inlet 148 and an air / fuel outlet 150. Thus, each of the air inlet 148 and the air / fuel outlet 150 also has a circular cross section.

  As best shown in FIG. 10, the premix zone 131 is a premix space 131 (a) below the premix chamber 32 (between the auxiliary fuel inlet 134 and the bottom 144 of the premix chamber and the air inlet 148). ), A premix chamber interior 131 (b), and a premix chamber top 142 and a premix space 131 (c) just above the air / fuel outlet 150. In the embodiment shown in FIGS. 9-12, the primary mixing of air and fuel occurs in the interior 31 (b) of the premix chamber 132 and the premix space 131 (c). Side wall 146 of premix chamber 132 includes an inner surface 154 and an outer surface 156. The lower section 158 of the side wall 146 is curved outwardly to provide an annular Coanda surface 160 on the inner surface 154 of the side wall.

  The ratio of the length (ie height) of the premix chamber 132 to the hydraulic diameter (inner diameter) is about 0.25: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. . The exact ratio of the length (height) of the premix chamber 132 to the hydraulic diameter (inner diameter) will depend somewhat on the type of fuel being burned and the pressure that can be used for intake and mixing. . In general, the longer the premixing chamber, the better the fuel and air can be mixed within the chamber. However, this advantage is balanced with cost and other considerations. In a preferred embodiment, the ratio of the length (ie, height) of the premix chamber 132 to the hydraulic diameter (inner diameter) is about 1.5: 1.

  The auxiliary fuel inlet 134 has an injection of fuel from the auxiliary fuel inlet into the premixing zone 131 with respect to the premixing zone 131, taking air into the premixing space 131 (a) and through the air inlet 148 into the premixing chamber. So that a mixture of fuel and air (preferably a substantially uniform mixture) is formed in the premixing zone and discharged from the air / fuel outlet 150 in the upper part 142 of the premixing chamber. Placed in position. The fuel and air continue to be mixed in the premix space 131 (c). Combustion of the fuel and air mixture typically does not occur until the mixture leaves the air / fuel outlet 150 (generally a distance away from the air / fuel outlet). The distance from the air / fuel outlet 150 at which combustion occurs varies with the amount of air in the mixture and the rate at which the mixture is released from the air / fuel outlet. In some cases, a short destage timing sequence may cause combustion in the premix zone (eg, in a short time, very low pressure scenario). As shown in FIGS. 10 and 12, the auxiliary fuel gas inlet 134 includes an annular distribution manifold 164 having a plurality of fuel ports 166 therein. The fuel port 166 is a substantially circular opening. As shown by FIG. 10, the annular distribution manifold 164 is positioned relative to the premix chamber 132 such that fuel can be injected annularly from the manifold 164 onto the annular Coanda surface 160. Yes.

  FIG. 10A shows another embodiment of an annular distribution manifold 164. In this embodiment, fuel port 166 is an elongated hole or slot. The slot shape of the fuel port 166 allows fuel to be injected onto the annular Coanda surface 160 in a sheet-like pattern. This serves to increase the uptake and mixing efficiency provided by the Coanda surface and also allows fuel to be injected from the manifold 164 at a higher rate. If desired, the slots 166 can be coupled together to form a continuous elongated hole or slot in the distribution manifold 164.

  An annular fuel film 170 is disposed around the outer periphery of the premix chamber 132. The fuel membrane 170 is connected to the fuel supply conduit 138 and is in fluid communication with both the main fuel outlet 136 and the auxiliary fuel inlet 134. The fuel membrane 170 includes an open top 172, a bottom 174, and an outer sidewall 176 and an inner sidewall 177 that connect the top to the bottom. In the embodiment illustrated by FIGS. 9-12, the inner sidewall 177 is also the sidewall 146 of the premix chamber. An annular seal 178 is attached to the bottom 174 of the fuel membrane 170 and extends around the side wall 146 of the premix chamber 132 to ensure membrane integrity. In another embodiment (as illustrated by FIGS. 25-28 and described below), the fuel membrane 170 is annular between the outer surface of the side wall 146 of the premix chamber 132 and the main fuel outlet 136. In order to provide this space, the space 146 may be spaced outward from the side wall 146. This annular space allows air to be taken from the underside of the burner to a point near the fuel port 192 located inside the main fuel outlet 136. In this embodiment, the inner sidewall 177 of the membrane 170 is separated from the sidewall 146 of the premix chamber 132.

  Auxiliary fuel supply conduits 180 (a), 180 (b), 180 (c), 180 (d) extend from the fuel membrane 170 to the auxiliary fuel inlet 134 (ie, to the annular distribution manifold 164) to provide fuel. From the fuel membrane 170 to the inlet 134 (ie, the manifold 164). Each of the auxiliary fuel supply conduits 180 (a), 180 (b), 180 (c), 180 (d) has a first end 182 attached to the fuel membrane 170 and an inlet 134 (ie, manifold 164). ) Attached to the second end 184.

  The main fuel outlet 136 is positioned relative to the upper portion 142 of the premix chamber 132 such that fuel can be injected from the main fuel outlet around the perimeter 186 of the air / fuel outlet 150 of the premix chamber. Has been. As best shown in FIG. 11, the main fuel outlet 136 includes a flat annular fuel injector body 188 having a plurality of fuel ports 192 therein. The fuel jet formed by port 192 is a diffusion fuel jet. An annular fuel injector body 188 is attached to the open top 172 of the annular membrane 170 such that the fuel port 192 is disposed around the outer periphery 186 of the air / fuel outlet 150 of the premix chamber 132. The inner diameter and outer diameter of the annular membrane 170 and the inner diameter and outer diameter of the fuel injector body 188 are substantially the same. Fuel can be injected annularly around the outer periphery 186 of the air / fuel outlet 150 from the main fuel outlet 136 (ie, the annular fuel injector body 188). Ports 192 can be sized and spaced to control the manner in which fuel is injected from the port (eg, direction and speed). This feature, in conjunction with fuel and air flow through the air / fuel outlet 150, allows the overall shape and length of the flame envelope to be controlled.

  As shown in FIG. 7, the diffusion fuel port 192 can be spaced from the fuel injector body 188 by a corresponding plurality of short gas risers or tip extensions 196 as required. By spacing the port 192 from the fuel injector body 188 using a riser 196, more air intake in the lateral direction can be achieved in some applications. The riser also allows the port structure and the fuel flow characteristics obtained with this structure to be mechanically changed as required. Another embodiment of the fuel injector body 70 illustrated by FIG. 8 may be used in place of the annular fuel injector body 188. As will be appreciated by those skilled in the art, the injector body 188 can include various repetitions of the port 192. The particular port structure used will depend on various factors including the type of fuel being burned (including the molecular weight of the fuel stream, the calorific value, the chemical amount and the temperature) and the pressure that can be used in connection with these fuels. Will change accordingly.

  The fuel supply conduit 138 is in fluid communication with the auxiliary fuel inlet 134 and the main fuel outlet 136 to direct fuel to the inlet 134 and outlet 136. The fuel supply conduit 138 has a first end 200 and a second end 202. The first end 200 includes a flange 204 for connecting the first end to a fuel source (again, these types of connections are more typically made by welding). The second end 202 is connected to a corresponding inlet 206 in the outer side wall 176 of the annular gas film 170. Alternatively, a separate fuel supply conduit or riser (not an integrated single conduit or riser 138) can direct fuel to the auxiliary fuel inlet 134 and the main fuel outlet 136. Separate conduits or risers will typically run from a common fuel header.

  The operation of the flare burner 130 will be described with reference to FIG. The fuel to be combusted (schematically indicated by black arrows) is directed through the fuel supply conduit 138 to the annular gas film 170. Part of the fuel is guided by the fuel film 170 to the main fuel outlet 136 (ie, the annular injector body 188). The remainder of the fuel is transferred by the fuel membrane 170 through the auxiliary fuel supply conduits 180 (a), 180 (b), 180 (c), 180 (d) to the auxiliary fuel inlet 134 (ie, the annular distribution manifold 164). Led. Fuel is injected from the fuel port 166 of the annular distribution manifold 164 through the premix space 131 (a) onto the annular Coanda surface 160 of the inner surface 154 of the premix chamber 132. By injecting fuel from the gas port 166 into the premix zone 131 and the premix chamber 132, air is taken into the premix space 131 (a) and passes through the air inlet 148 to the interior 131 (b) of the premix chamber. ), Whereby a mixture of fuel and air (preferably a substantially uniform mixture) is formed in the premix zone and discharged from the air / fuel outlet 150. Fuel and air continue to be mixed for a short distance above the air / fuel outlet 150. By injecting fuel from the fuel port 166 onto the Coanda surface 160, the fuel adheres to and travels along the passage on the Coanda surface, forming a relatively thin film that allows air to flow more. It is efficiently taken in and air and fuel are mixed more efficiently. Fuel to be combusted exits from the main fuel outlet 136 (annular injector body 188), around the outer periphery 186 of the air / fuel outlet 150 of the premix chamber 132, and thus from the air / fuel outlet 150 of the premix chamber. It is injected around the incoming air / fuel mixture. The flare burner 130 preferably has a stoichiometric amount of air required to burn the fuel injected into the premixing zone 131 so that the amount of air taken into the premixing zone 131 containing the premixing chamber 132. Designed and operated to exceed. This excess air is provided in the center of the flame envelope to burn the center fuel. However, as will be described further below, in some applications, the burner burns fuel injected into the premix zone 131 with the amount of air taken into the premix zone 131 that includes the premix chamber 132. Designed and operated to be below the stoichiometric amount of air required for A fuel rich ("fuel-rich") mixture of fuel and air (i.e., less than the stoichiometric amount of air required to assist combustion of the fuel introduced into the premix zone). It may be desirable in some applications to inject the containing mixture) into the center of the flame envelope.

  Flare burner 130 provides the same benefits as provided by flare burner 30. The flame envelope 100 schematically illustrated by FIG. 24 is also formed by a flare burner 130.

  Referring now to FIGS. 13-18, a third embodiment of the flare burner of the present invention is illustrated, generally indicated by the reference numeral 230. Similar to another embodiment of the inventive flare burner, the flare burner 230 includes a premix zone 231 that includes a premix chamber 232, an auxiliary fuel inlet 234 for injecting fuel into the premix zone, and a main fuel outlet 236. As well as a fuel supply conduit 238. A pilot (as shown in FIG. 4) may be associated with the burner 130 to initially ignite the fuel and air mixture released by the burner.

  In the embodiment shown in FIGS. 13-18, the premix chamber 232 of the flare burner 230 provides the main part of the premix zone 231. A mixture of fuel and air (preferably a substantially uniform mixture) may be formed in a premix zone 231 that includes a premix chamber 232. As discussed below, the mixture formed in the premix zone 231 may be either fuel rich or fuel lean. The premix chamber 232 includes a rectangular cross section and has a rectangular shape. The premix chamber includes a top 242, a bottom 244, and a sidewall 246 connecting the top to the bottom, an air inlet 248 disposed at the bottom 244, and an air / fuel outlet 250 disposed at the top. As shown, the top 242 and bottom 244 are open, thereby forming an air inlet 248 and an air / fuel outlet 250. Accordingly, air inlet 248 and air / fuel outlet 250 also each have a rectangular cross section.

  As best shown in FIG. 14, the premix zone 231 has a premix space 231 (a) below the premix chamber 232 (between the auxiliary fuel inlet 234 and the bottom 244 of the premix chamber and the air inlet 248). ), A premix chamber interior 231 (b), and a premix chamber top 242 and a premix space 231 (c) just above the air / fuel outlet 250. In the embodiment shown in FIGS. 13-18, the primary mixing of air and fuel occurs in the interior 31 (b) of the premix chamber 232 and the premix space 231 (c).

  Side wall 246 of premix chamber 232 includes four side walls 246 (a), 246 (b), 246 (c) and 246 (d). Each of the sidewalls 246 (a), 246 (b), 246 (c), and 246 (d) includes an inner surface 254 and an outer surface 256. The lower portion 258 of each of the sidewalls 246 (a), 246 (b), 246 (c) and 246 (d) is curved outwardly to provide an annular Coanda surface 260 on the inner surface 254 of the sidewall. . The ratio of the length (ie height) of the premix chamber 232 to the hydraulic diameter (inner diameter) is from about 0.25: 1 to about 4: 1, preferably from about 1: 1 to about 3: 1. . The exact ratio of the length (height) of the premix chamber 232 to the hydraulic diameter (inner diameter) will depend somewhat on the type of fuel being burned and the pressure that can be used for intake and mixing. In general, the longer the premixing chamber, the better the fuel and air can be mixed within the chamber. However, this advantage is balanced with cost and other considerations. In a preferred embodiment, the ratio of the length (ie, height) of the premix chamber 232 to the hydraulic diameter is about 1.5: 1.

  The auxiliary fuel inlet 234 is relative to the premixing zone 231 where fuel injection from the auxiliary fuel inlet into the premixing zone takes air into the premixing space 231 (a) and through the air inlet 248 through the premixing chamber 232. Into which a mixture of fuel and air (preferably a substantially uniform mixture) is formed in the premix zone and discharged from the air / fuel outlet 250 in the top 242 of the premix chamber. It is arranged in such a position. Combustion of the fuel and air mixture typically does not occur until the mixture leaves the air / fuel outlet 250 (generally a distance away from the air / fuel outlet). The distance from the air / fuel outlet 250 at which combustion occurs varies with the amount of air in the mixture and the rate at which the mixture is discharged from the air / fuel outlet. In some cases, a short destage timing sequence may cause combustion in the premix zone (eg, in a short time, very low pressure scenario).

  As best shown in FIG. 18, the auxiliary fuel inlet 234 includes two tubular distribution manifolds 264 (a) and 264 (b), each of which has a plurality of fuel ports 266 therein. Have. The fuel port 266 is a substantially circular hole. The distribution manifold 264 (a) is in a position relative to the premix chamber 232 such that fuel can be injected from the manifold 264 (a) onto the Coanda surface 260 of the inner surface 254 of the sidewall 246 (a). Has been placed. Similarly, the distribution manifold 264 (b) has a Coanda surface 260 on the inner surface 254 of the side wall 246 (c) where the fuel faces the premixing chamber 232 from the manifold 264 (b) to the side wall 246 (a). It is arranged at a position where it can be jetted upward. As will be appreciated by those skilled in the art, various configurations of ports and jets can be used to inject fuel onto the Coanda surface of this embodiment. For example, the number and spacing of fuel ports can be varied depending on the desired thickness of the film to be formed on the Coanda surface.

  FIG. 17A shows another embodiment of tubular distribution manifolds 264 (a) and 264 (b). In this embodiment, fuel port 266 is an elongated hole or slot. The slot shape of the fuel port 266 causes fuel to be injected in a sheet-like pattern onto the annular Coanda surface 260, which functions to increase the uptake and mixing efficiency provided by the Coanda surface, and is also capable of higher capacity. Allows the gas to be burned. If desired, the slots 266 can be coupled to form continuous elongated holes or slots in the distribution manifolds 264 (a) and 264 (b). The fuel port 266 can be formed not only in circular holes and slots, but also in other shapes depending on the particular application. Examples of other shapes include elongated ovals and rectangular slots.

  A rectangular fuel film 270 is disposed around the outer periphery of the premix chamber 232. The fuel membrane 270 connects to the fuel supply conduit 238 and is in fluid communication with both the main fuel outlet 236 and the auxiliary fuel inlet 234. The fuel membrane 270 includes an open top 272, a bottom 274, and an outer sidewall 276 and an inner sidewall 277 that connect the top to the bottom. In the embodiment illustrated by FIGS. 13-18, the inner sidewall 277 is also the sidewall 246 of the premix chamber. A matching seal mechanism 278 is attached to the bottom 274 of the fuel membrane 270 and extends around the sidewall 246 of the premix chamber 232 to ensure membrane integrity. In another embodiment (as illustrated in FIGS. 25-28 and described below), the fuel membrane 270 includes sidewalls 246 (a), 246 (b) that are sidewalls 246 of the premix chamber 232. , 246 (c) and 246 (d) can be spaced apart from the outer surface 256 of the sidewall 246 to provide a space between the outer surface 256 of the main fuel outlet 236. This space allows air to be taken from the underside of the burner to a point near the fuel port 292 located inside the main fuel outlet 236. In this embodiment, the inner sidewall 277 of the membrane 270 is separated from the sidewall 246 of the premix chamber 232.

  Auxiliary fuel supply conduits 280 (a), 280 (b), 280 (c), 280 (d) are connected from the fuel membrane 270 to the auxiliary fuel inlet 234 (ie, tubular distribution manifolds 264 (a) and 264 (b)). And) deliver fuel from the fuel membrane to the auxiliary fuel inlet. Each of the auxiliary fuel supply conduits 280 (a), 280 (b), 280 (c), 280 (d) has a first end 282 and a second end 284 attached to the fuel membrane 270. Including. The second end 284 of the conduit 280 (a) and the second end 284 of the conduit 280 (b) are attached to opposite ends of the tubular distribution manifold 264 (a). The second end 284 of the conduit 280 (b) and the second end 284 of the conduit 280 (c) are attached to opposite ends of the tubular distribution manifold 264 (b).

  The main fuel outlet 236 is positioned relative to the upper portion 242 of the premix chamber 232 such that fuel can be injected from the main fuel outlet around the perimeter 286 of the air / fuel outlet 250 of the premix chamber. Has been. As best shown in FIG. 15, the main fuel outlet 236 includes a flat rectangular fuel injector body 288 having a plurality of diffusion fuel ports 292 therein. The fuel jet formed by port 292 is a diffusion fuel jet. The fuel injector body 288 is attached to the open top 272 of the fuel membrane 270 such that the diffusion fuel port 292 is disposed around the outer periphery 286 of the air / fuel outlet 250 of the premix chamber 232. The inner and outer diameters of the fuel film 270 and the outer and inner diameters of the fuel injector body 288 are substantially the same. Fuel can be injected around the outer periphery 286 of the air / fuel outlet 250 from the main fuel outlet 236 (ie, the fuel injector body 288). Ports 292 can be arranged with dimensions and spacing to control the manner in which fuel is injected from the port (eg, direction and speed). This feature allows the shape and length of the entire flame envelope to be controlled in connection with fuel and air flow through the air / fuel outlet 250.

  As shown by FIG. 16, the diffusion fuel port 292 can be spaced from the fuel injector body 288 by a plurality of corresponding short gas risers or tip extensions 296 as required. By placing the port 292 away from the fuel injector body 288 by a riser 296, more air can be taken in the lateral direction in some applications. The riser also allows the port structure and the fuel flow characteristics obtained with this structure to be mechanically changed as required. As will be appreciated by those skilled in the art, the injector body 288 can include various repetitions of the port 292. The particular port structure used will depend on various factors including the type of fuel being burned (including the molecular weight of the fuel stream, the calorific value, the chemical amount and the temperature) and the pressure that can be used in connection with these fuels. Will change accordingly.

  The fuel supply conduit 238 is in fluid communication with the auxiliary fuel inlet 234 and the main fuel outlet 236 to direct fuel gas to the inlet 234 and outlet 236. The fuel supply conduit 238 has a first end 300 and a second end 302. As shown, the first end 300 includes a flange 304 for connecting the first end to a fuel gas source (again, these types of connections are more typically welded). Made by). The second end 302 is connected to a corresponding inlet 306 in the outer sidewall 176 of the annular fuel film 270. Alternatively, separate fuel supply conduits or risers (rather than a single integrated conduit or riser 238) can direct fuel to the auxiliary fuel inlet 234 and the main fuel outlet 236. Separate conduits or risers will typically extend from a common fuel header.

  Referring to FIG. 14, in the operation of burner 230, the fuel to be combusted (shown schematically by a black arrow) is directed to fuel film 270 through fuel supply conduit 238. Part of the fuel is guided to the main fuel outlet 236 (and the injector body 288) by the fuel film 270. The remaining portion of the fuel is passed through the auxiliary fuel supply conduits 280 (a), 280 (b), 280 (c), 280 (d) by the membrane 270 through the auxiliary fuel inlet 234 (and the tubular of the auxiliary fuel supply conduit). Distribution manifolds 264 (a) and 264 (b)). Fuel is injected from the fuel ports 266 of the distribution manifolds 264 (a) and 264 (b) onto the Coanda surface 260 on the inner surface 254 of the side walls 246 (a) and 246 (c) of the premix chamber 232. By injecting fuel from the fuel port 266 into the premix zone 231 and the premix chamber 232, air is taken into the premix space 231 (a) and through the air inlet 248 the interior 231 (b ), Whereby a mixture of fuel and air (preferably a substantially uniform mixture) is formed in the premix zone and discharged from the air / fuel outlet 250. Fuel and air continue to be mixed for a short distance above the air / fuel outlet 250. By injecting fuel from the fuel port 266 onto the Coanda surface 260 of the inner surface 254 of the sidewalls 246 (a) and 246 (c), the fuel adheres to and travels along the Coanda surface passage, A thin membrane is formed on this passageway, which allows the air to be taken in more efficiently and the air and fuel to be mixed more efficiently. The fuel to be combusted from the main fuel outlet 236 (and the annular fuel injector body 288) around the periphery 286 of the air / fuel outlet 250 of the premix chamber 232 and thus the air / fuel outlet of the premix chamber. Around the air / fuel mixture coming out of. The flare burner 230 preferably has a stoichiometric amount of air required to burn the fuel injected into the premixing zone 231 so that the amount of air taken into the premixing zone 231 including the premixing chamber 232. Designed and operated to exceed. This excess air is provided in the center of the flame envelope to burn the center fuel. However, as described further below, in some applications, the burner 230 causes the amount of air taken into the premix zone 231 that includes the premix chamber 232 to burn the fuel injected into the premix zone. Designed and operated to be below the stoichiometric amount of air required to do. A flame envelope with a fuel-rich mixture of fuel and air (ie, a mixture containing less than the stoichiometric amount of air required to assist combustion of the fuel introduced into the premix zone) It may be desirable in some applications to inject into the center.

  Flare burner 230 provides the same benefits as provided by flare burner 30 and flare burner 130. The flame envelope 100 schematically illustrated by FIG. 24 is also formed by a flare burner 230.

  The polygonal (in the illustrated embodiment, rectangular) shape of the flare burner 230 can provide greater flexibility in spacing the flare burner for ground flare burners. Also, such a shape is higher with respect to how fuel is directed from the diffusion gas port 292 due to the fact that this geometry can be rotated to change the interaction zone. Can provide flexibility.

  Referring now to FIGS. 19-23, a fourth embodiment of the flare burner of the present invention is illustrated, which is indicated generally by the reference numeral 330. Similar to another embodiment of the inventive flare burner, the flare burner 330 includes a premix zone 331 including a premix chamber zone 332, an auxiliary fuel inlet 334 for injecting fuel into the premix zone, a main fuel outlet 336. As well as a fuel supply conduit 338. A pilot 40 (as shown in FIG. 4) may be associated with the burner 330 to initially ignite the fuel and air mixture released by the burner.

  A mixture of fuel and air (preferably a substantially uniform mixture) may be formed in a premix zone 331 that includes a premix chamber 332. As discussed below, the mixture formed in the premix zone 331 may be either fuel rich or fuel lean. The premix chamber 332 includes a circular cross section and has a cylindrical shape. The premix chamber includes a top 342, a bottom 344, a sidewall 346 connecting the top to the bottom, an air inlet 348 disposed at the bottom 344, and an air / fuel outlet 350 disposed at the top 342. Sidewall 346 includes an inner surface 347 and an outer surface 349. As shown, the top 342 and bottom 344 are open, thereby forming an air inlet 348 and an air / fuel outlet 350. Thus, each of the air inlet 348 and the air / fuel outlet 350 also has a circular cross section. The ratio of the length (ie, height) of the premix chamber 332 to the hydraulic diameter (inner diameter) is about 0.25: 1 to about 4: 1.

  In the embodiment illustrated by FIGS. 19, 20, 22 and 23 (not including the extension cylinder 400 discussed below), the ratio of the length (ie, height) of the premix chamber 332 to the hydraulic diameter (inner diameter). Is about 1: 1 or less. Preferably, in the embodiment illustrated by FIGS. 19, 20, 22 and 23 (not including the extension cylinder 400 discussed below), the hydraulic diameter (inner diameter) of the length (ie, height) of the premix chamber 332. ) Is from about 0.25: 1 to about 1: 1. As discussed above, a longer premix chamber generally allows for better mixing of fuel and air within the premix chamber. However, in the embodiment illustrated by FIGS. 19 and 20, the length (ie, height) of the premix chamber 332 is good if the ignition delay is kept constant by adjusting the flame propagation speed. It has been found that it is still sufficient to cause mixing. As best shown in FIG. 20, the premix zone 331 of this particular embodiment (not including the extension cylinder 400 discussed below) is below the premix chamber 332 (auxiliary fuel inlet 334, premix chamber The premixing space 331 (a) (between the bottom 344 and the air inlet 348), the premixing chamber interior 331 (b), and the premixing chamber top 342 and the preheating just above the air / fuel outlet 350. Includes mixing space 331 (c). In this embodiment, air and fuel mixing occurs in all three sections of the premix zone 331.

  The auxiliary fuel inlet 334, relative to the premix zone 331, the injection of fuel from the auxiliary fuel inlet into the premix zone draws air into the premix space 331 (a) and through the air inlet 348 the premix chamber 332. Into which a mixture of fuel gas and air (preferably a substantially uniform mixture) is formed in the premix zone and discharged from the air / fuel outlet 350 in the top 342 of the premix chamber. It is arranged in such a position. Combustion of the fuel and air mixture typically does not occur until the mixture leaves the air / fuel outlet 350 (generally a distance away from the air / fuel outlet). The distance from the air / fuel outlet 350 at which combustion occurs varies with the amount of air in the mixture and the rate at which the mixture is discharged from the air / fuel outlet. In some cases, a short destage timing sequence may cause combustion in the premix zone (eg, in a short time, very low pressure scenario).

  As shown by FIGS. 19 and 22, the auxiliary fuel inlet 334 is disposed concentrically around the casting 352 having a bull nose (spherical portion) 353 and around the bull nose, and the air inlet 348 of the premixing chamber 332. A plurality of fuel outlet arms 354 disposed centrally below. The auxiliary fuel inlet 334 is concentric with the air inlet 348 and the premix chamber 332. In the embodiment illustrated by FIGS. 19 and 20, the auxiliary fuel inlet 334 is spaced below the air inlet 348 of the premix chamber 332. The auxiliary fuel inlet 334 can be located in the range of zero inches to 2 inches (0 cm to 5.08 cm) below the air inlet 348 and is preferably located about 1 inch (2.54 cm) below the air inlet. The The exact distance may vary according to the type of fuel being burned, the particular application, the allowable length of the flame envelope, and other factors.

  Each fuel outlet arm 354 and bull nose 353 includes a plurality of fuel ports 356. The ports 356 are arranged in a line along the longitudinal axis of each fuel outlet arm 354. Another embodiment of the auxiliary fuel inlet 334 is illustrated by FIG. In this embodiment, the gas outlet arms 354 each include two rows of diffusion fuel ports 356, with each port in each row aligned so as not to face the port in the adjacent row. The auxiliary fuel inlet 334, including the fuel outlet arm 354, is intentionally made small so as to maximize the interaction between the released fuel and the captured air. The “bluff body” effect caused by the size and shape of the inlet 334 is minimized and a clean approach of air to the emitted fuel is maintained.

  An annular fuel film 360 is disposed around the outer periphery of the premix chamber 332. The fuel membrane 360 is connected to the fuel supply conduit 338 and is in fluid communication with the main fuel outlet 336. The fuel membrane 360 includes an open top 362, a bottom 364, and an outer sidewall 366 and an inner sidewall 367 that connect the top to the bottom. In a preferred embodiment, the outer sidewall 366 is spaced about 3 inches from the inner sidewall 367 (this distance depends on the nature of the fuel and the overall structure of the burner). ). In the embodiment illustrated by FIGS. 19, 20, 22, and 23, the inner sidewall 367 of the fuel film 360 is also the outer surface 349 of the sidewall 346 of the premix chamber 332. In another embodiment (as illustrated in FIGS. 25-28 and described below), the fuel membrane 360 is between the outer surface 349 of the side wall 346 of the premix chamber 332 and the main fuel outlet 336. In order to provide an annular space, the sidewall 346 may be spaced apart from the outer surface 349. This space allows air to be taken from below the burner to a point near the fuel port 374 located inside the main fuel outlet 336. In this embodiment, the inner sidewall 367 of the membrane 360 is separated from the sidewall 346 of the premix chamber 332.

  The main fuel outlet 336 is positioned relative to the top 342 of the premix chamber such that fuel can be injected from the main fuel outlet 336 around the perimeter 368 of the premix chamber air / fuel outlet 350. Has been. As best shown in FIG. 22, the main fuel outlet 336 includes a flat annular fuel injector body 370 having a plurality of fuel ports 374 therein. The fuel jet formed by port 374 is a diffusion fuel jet. The ports 374 are preferably spaced apart by 6 degrees, although this spacing may vary depending on the particular application. An annular fuel injector body 370 is attached to the open top 362 of the annular membrane 360 such that the fuel port 374 is disposed around the outer periphery 368 of the air / fuel outlet 350 of the premix chamber. The inner diameter and outer diameter of the annular membrane 360 and the inner diameter and outer diameter of the fuel injector body 370 are substantially the same. Fuel can be injected annularly around the outer periphery 386 of the air / fuel outlet 350 from the main fuel outlet 336 (ie, the fuel injector body 370). Ports 374 may be sized and spaced to control the manner in which fuel is injected from the port (eg, direction and speed). This feature allows the shape and length of the entire flame envelope to be controlled in connection with fuel and air flow through the air / fuel outlet 350.

  As shown in FIG. 7, the diffusion fuel port 374 can be spaced from the fuel injector body 370 by a plurality of corresponding short gas risers or tip extensions 376 as required. By spacing the port 374 from the fuel injector body 370 using a riser 376, more air intake in the lateral direction can be achieved in some applications. The riser also allows the port structure and the fuel flow characteristics obtained with this structure to be mechanically changed as required. As will be appreciated by those skilled in the art, the injector body 370 can include various repetitions of the port 374. The particular port structure used will depend on various factors including the type of fuel being burned (including the molecular weight of the fuel stream, the calorific value, the chemical amount and the temperature) and the pressure that can be used in connection with these fuels. Will change accordingly.

  A fuel supply conduit 338 is in fluid communication with the auxiliary fuel inlet 334 and the main fuel outlet 336 to direct fuel to the inlet 334 and outlet 336. The fuel supply conduit 338 includes a main branch 380 having a first end 382 and a second end 384. The first end 382 includes a flange 386 for connecting the first end to the fuel gas source (again, these types of connections are more typically made by welding). The second end 384 is connected to a corresponding inlet 388 in the outer sidewall 366 of the fuel film 360. The fuel supply conduit 338 also includes an auxiliary branch 390 that connects the fuel supply conduit to the auxiliary fuel inlet 334. The auxiliary branch 90 includes a first end 392 and a second end 394. The first end 392 is connected to the main branch 390 of the fuel supply conduit 338. The second end 394 is connected to the auxiliary fuel inlet 334 (specifically, the casting 352). Alternatively, a separate fuel supply conduit or riser (not an integrated single conduit or riser 338) can direct fuel to the auxiliary fuel inlet 334 and the main fuel outlet 336. Separate conduits or risers will typically extend from a common fuel header.

  Now referring specifically to FIG. 21, another embodiment of a flare burner 330 is shown. This embodiment is identical to the previously described embodiment of burner 330 except that it also includes a premix chamber extension cylinder 400. The premix chamber extension cylinder 400 extends the length of the premix chamber 332. In this embodiment, the ratio of the length (ie, height) of the premix chamber to the hydraulic diameter (inner diameter) is about 1: 1 to about 4: 1, more preferably about 1: 1 to about 3. : 1. Most preferably, in this embodiment, the ratio of premix chamber length (ie height) to hydraulic diameter (inner diameter) is about 1.5: 1. The cylinder 400 includes an upper section 402, a lower section 404, and an intermediate section 406 connecting the upper section and the lower section. The middle section 406 is attached to the inner side wall 367 of the annular fuel film 360.

  With the premix chamber extension cylinder 400, the top 342 of the premix chamber 332 and the air / fuel outlet 350 are spaced above the main fuel outlet 336. The top 342 of the premix chamber 332 and the air / fuel outlet 350 are in the range of about 0.5 inches to about 10 inches (about 1.27 cm to 25.4 cm) above the main fuel outlet 336, preferably about 6 inches. In the range of inches to about 8 inches (about 15.24 cm to 20.32 cm). The exact distance may vary according to the type of fuel being burned, the particular application, the allowable height of the flame envelope, and other factors. The bottom 344 of the premix chamber 332 is substantially flush with the auxiliary fuel inlet 334 or about 1 inch (2.54 cm) above the auxiliary fuel inlet 334. As shown in FIG. 21, the premix zone 331 in this particular embodiment (including the extension cylinder 400) is below the premix chamber 332 (auxiliary fuel inlet 334, premix chamber bottom 344 and air inlet 348). A premixing space 331 (a), a premixing chamber interior 331 (b), and a premixing chamber top 342 and a premixing space 331 (c) just above the air / fuel outlet 350. . In this embodiment, the primary mixing of air and fuel occurs in the premix chamber 332 (premix space 331 (b)).

  The upper section 402 of the premix chamber extension cylinder 400 functions both as a windshield and as a physical barrier to retard ignition. Specifically, the upper section 402 counteracts adverse cross-flow air effects that may cause the flame to be directed inside the diameter of the premix chamber and interfere with the flare burner smokeless performance. Upper section 402 also functions to separate the premixed fuel stream from the diffusion flame ignition. Similarly, the lower section 404 of the cylinder 400 acts as a bottom windshield and serves to prevent the flame from being pulled back and causing premature ignition. Also in this embodiment, the length of the premixing chamber 332 is increased by the extension cylinder 400, thereby increasing the mixing of fuel and air in the premixing chamber. Extension cylinders are not necessary for all applications, for example, extension cylinders may not be needed when cross-flow action is not an issue or when burning low molecular weight fuel. Whether or not a shield is included depends on the molecular weight and calorific value of the fuel being burned, whether the fuel contains saturated or unsaturated hydrocarbons, the associated temperature and pressure, and other factors.

  In the embodiment shown in FIG. 21, the inner sidewall 367 of the membrane 360 is attached to the middle section 406 of the extension cylinder 400. In another embodiment (as illustrated in FIGS. 25-28 and described below), the fuel membrane 360 is used to provide a space between the outer surface of the extension cylinder 400 and the main fuel outlet 336. In this case, the extension cylinder 400 may be spaced apart from the outside. This space allows air to be taken from below the burner to a point near the fuel port 374 located inside the main fuel outlet 336.

  The operation of the flare burner 330 will be described with reference to FIGS. A portion of the combusted fuel (shown schematically by black arrows) is directed through the main branch 380 of the fuel supply conduit 338 to the fuel film 360 and the main fuel outlet 336. Some of the fuel that is combusted is also directed to the auxiliary fuel inlet 334 through the auxiliary branch 390 of the fuel supply conduit 338. Injection of fuel from the auxiliary fuel inlet 334 into the premixing zone 331 and the premixing chamber 332 draws air into the premixing space 331 (a) and introduces it into the premixing chamber through the air inlet 348, thereby Within the premix zone, a mixture of fuel and air (preferably a substantially uniform mixture) is formed and discharged from the air / fuel outlet 350. Fuel and air continue to be mixed for a short distance above the air / fuel outlet 350. The remaining fuel to be combusted is from the main fuel outlet 336, around the perimeter 368 of the air / fuel outlet 350 of the premix chamber, and thus of the air / fuel mixture coming out of the air / fuel outlet of the premix chamber. It is injected around. Also in this embodiment, once the extension cylinder 400 is installed, further mixing occurs and the premixed flow exiting the air / fuel outlet 350 is in contact with the diffusion flame formed upon discharge of fuel from the main fuel outlet 336. Interaction isolates it from early ignition. The use of the extension cylinder 400 serves to increase the overall effect provided by the use of the premixed flow. Flare burner 330 preferably has a stoichiometric amount of air required to burn the fuel injected into the premixing zone 331, including the premixing chamber 332. Designed and operated to exceed. This excess air is provided in the center of the flame envelope to burn the center fuel. However, as will be described further below, in some applications, the burner 330 causes the amount of air taken into the premix zone 331 including the premix chamber 332 to burn the fuel injected into the premix zone. Designed and operated to be below the stoichiometric amount of air required to do. A "fuel rich" mixture of fuel and air (ie, a mixture containing less than the stoichiometric amount of air required to assist combustion of the fuel introduced into the premix zone) Injecting into the center of the flame envelope is desirable in some applications.

  Flare burner 330 provides the same benefits as provided by flare burners 30, 130, and 230. The flame envelope 100 schematically illustrated by FIG. 24 is also formed by a flare burner 330.

  Referring now to FIGS. 25-28, there are illustrated modifications that can be made to the previously described fourth embodiment of the inventive flare burner (embodiment shown by FIGS. 19-23). The same changes can be made in the first, second and third embodiments of the inventive flare burner described above as well.

  In this embodiment, the flare burner 330 includes a premix chamber extension cylinder 400. However, the extension cylinder 400 (and thus the premixing chamber 332) is not directly attached to the fuel film 360, but is spaced inward from the fuel film so that there is air between the extension cylinder and the fuel film. Provides a flow path, which allows air to efficiently reach the fuel port 374 located inside the main fuel outlet 336. The diameter of the extension cylinder 400 (and thus the premix chamber 332) is much smaller than the inner diameter of the fuel film 360. In this embodiment, the ratio of length (ie height) of the premix chamber to hydraulic diameter (inner diameter) ranges from about 0.5: 1 to about 4: 1, more preferably about 1: 1. In the range of about 3: 1. Most preferably, the ratio of premix chamber length (ie height) to hydraulic diameter (inner diameter) is about 1.5: 1.

  Due to the smaller diameter of the extension shield 400, an annular space 430 exists between the inner side wall 367 of the fuel film 360 and the outer surface of the extension cylinder 400 (also the outer surface 349 of the side wall 346 of the premix chamber 332). A plurality of thin rectangular gusset plates 432 are used to centrally hold the extension cylinder 400 (and thus the premix chamber 332) within the fuel membrane 360. As illustrated, four plates 432 are disposed 90 degrees apart from one another in the annular space 430. One end of each plate 432 is attached to the inner side wall 367 of the fuel film 360. The other end of each of the plates 432 is attached to the outer surface of the extension cylinder 400 (also the outer surface 349 of the side wall 346 of the premix chamber 332). Except for this change described above, the burner 330 shown in FIGS. 25-28 is identical in all respects to the embodiment shown in FIGS. 19-23 and described above.

  The main fuel outlet 336 is still such that fuel can be injected from the main fuel outlet 336 around the perimeter 368 of the premix chamber air / fuel outlet 350 relative to the top 342 of the premix chamber 132. Placed in position. The annular space 430 extends the air path to allow fresh oxidant (oxidant) to efficiently reach the fuel port 374 located inside the main fuel outlet 336, and the cylinder and fuel film. It only brings in between. The operation of the burner 330 is the same as in the previous embodiment, except that fresh air is drawn through the annular space 430 from below the burner by the propulsion in the row inside the fuel port 374. The entrained air approaches and mixes with the fuel emitted by the inner row of fuel ports 374 at the main fuel outlet 336. For example, this enhanced mixing control provided by the annular space 430 is useful when burning relatively heavy unsaturated fuel stocks that have a high tendency to emit smoke. This method optimizes the burner for combustion that does not emit soot.

  As will be appreciated by those skilled in the art, the same modifications can be made to the other three embodiments of the inventive flare burner described above. For example, in a modification of the embodiment illustrated by FIGS. 4-8, the cross-sectional diameter of the premix chamber 32 is reduced and the premix chamber 32 is spaced inward from the fuel film 60. The inner side wall 67 of the annular fuel membrane 60 or the side wall 46 of the premix chamber 32 is added (as shown, the inner side wall of the membrane and the side wall of the premix chamber are the same). The annular seal 68 is eliminated. By disposing the premixing chamber 32 inward from the fuel film 60, an air space is provided between the premixing chamber and the fuel film. Thus, fresh air can be taken from below the burner to a point near the fuel discharged from the fuel port 74 inside the main fuel outlet 36. As shown by FIGS. 25-28, the premix chamber 32 can be placed in the center of the fuel film 60 and attached to the fuel film 60 using a plurality of gussets.

  FIG. 28 schematically illustrates a flame envelope 100 formed by a modified flare burner 330 (and, if modified in the same manner, burners 130, 230, 330) illustrated by FIGS. As shown, excess air is injected from the premix chamber 332 into the center 102 of the flame envelope 100. The excess air, indicated by air pocket 103 in FIG. 28, mixes with the fuel in the center of flame envelope 100 to actually form two initial zones, zones 104 (a) and 104 (b). Air is taken from below the burner 330 to a point near the fuel discharged by the fuel port 374 in the inner row of the main fuel outlet 336. Air entrained through the annular space 430 improves mixing control and provides faster and more uniform combustion within the entire flame envelope 100. As shown by FIG. 28, the length 106 of the flame envelope 100 is substantially shorter for the same amount of fuel than the length 23 of the prior art flame envelope 20 shown by FIG.

Overview The partial premixing method of the present invention allows two flame zones to be initiated within the same flame envelope when the fuel is combusted. The outer flame zone is typically the flame zone normally observed in burners of the type previously used (ie, the type using only diffusive mixing). The outer layer of gas is ruptured to expose a continuous layer of gas, causing gas diffusion and subsequent combustion to repeat. The second flame zone is formed by the premix zone of the burner, which delivers the combustible mixture inside the main flame envelope. This combustion flow field acts to form a significant turbulent state at the core of the flame that is not common in ordinary diffusion flames. As the premix zone becomes more fuel lean, the flame becomes shorter due to the additional oxidant delivered to the core of the flame. Excess air is used by the rest of the flame cloud to function to reduce the flame length (or allow mass flow to be increased) and still emit It also serves as a quenching (flame extinguishing) mechanism for reducing (such as nitrogen oxides and carbon monoxide). Excess air also reduces soot formation and burns all unburned hydrocarbons.

  Each of the flare burners 30, 130, 230, and 330 preferably has the amount of air taken into the premix zone and injected into the center of the flame envelope to cause the combustion of fuel introduced into the premix zone. Designed and operated to range from about 15% to about 300% of the stoichiometric amount of air required to assist. Therefore, the fuel-rich process (a mixture of fuel introduced into the premix zone and air in an amount less than 100% of the stoichiometric amount of air required to assist the combustion of the fuel is Injected into the center), fuel lean method (fuel introduced into the premix zone, and air in an amount greater than 100% of the stoichiometric amount of air required to assist combustion of this fuel) And the mixture is injected into the center of the flame envelope. Each method has its advantages over the typical diffusion / free jet driven combustion methods that have been used so far. The particular method used will vary depending on the particular application, including the type of fuel being burned and the pressure available. This method can be modified by typical port arrangements and fuel delivery mechanisms.

  When using the fuel-rich method, a portion of the fuel injected into the center of the flame initiates a smaller combustion envelope at the core of the flame, which shortens the length of the flame and at the same time flame envelope. Acts to form an additional turbulent combustion zone in the center of When using the fuel lean method, the length of the flame envelope is considerably shortened by burning a larger portion of the premixed fuel at the core of the flame. The excess air carried by the premixed flow method then serves to initiate further combustion with respect to the center of the remaining flame envelope. Additional turbulence formed by the fuel expands in the center of the flame during combustion, then mixes for the remaining fuel, breaks up the high concentration fuel core, and breaks the crushed fuel into the outer flame. It works to promote by extruding to the boundary.

  When using a fuel rich process, it is important that the premixed stream delivered to the center of the flame envelope is maintained within a combustible range. Otherwise, mixing and combustion cannot be increased in the center of the flame envelope. The promotion of mixing is provided by a premixed flame that starts at the core of the flame and expands at high speed, forming a very large turbulent flow at the core of the flame.

  However, in many applications, a “lean” mixture of fuel and air (ie, greater than 100% of the stoichiometric amount of air required to assist combustion of fuel introduced into the premix zone). It is desirable to inject a mixture containing a quantity of air into the center of the flame envelope. In many applications, the amount of air taken into the premix zone and injected into the center of the flame envelope is the stoichiometry of air required to assist the combustion of fuel introduced into the premix zone. Range from about 125% to about 300% of the target amount. Preferably, the amount of air entrained in the premix zone is from about 150% to about 300% of the stoichiometric amount of air required to assist the combustion of fuel injected into the premix zone. More preferably, it is about 175% to about 300%. As the amount of excess air entrained in the premix zone increases (ie, the amount of air entrained in the premix zone requires the air chemistry necessary to assist combustion of fuel introduced into the premix zone. Increasing beyond the stoichiometric amount) also increases the benefits regarding flame length and emissions. It may be advantageous that the amount of air taken into the premix zone is greater than about 300% of the stoichiometric amount of air required to assist the combustion of fuel injected into the premix zone. This will require an external air intake source (e.g., steam injection), and other modifications may also be required and will therefore be very costly.

  The amount of air taken into each premix zone of burners 30, 130, 230 and 330 depends on the pressure and mass flow of fuel injected from the auxiliary fuel inlet, the type of fuel burned, the structure of the auxiliary fuel inlet (inlet The number and size of the ports in the air), the placement of the auxiliary fuel inlet relative to the air inlet leading to the premix chamber, and the size of the air inlet. In many applications, the ultimate goal is to obtain a very lean, preferably flammable, fuel / air mixture. The flammable lean mixture will quickly absorb fuel that needs to be combustible again once it enters the core of the flame envelope. If a flammable mixture is obtained, the air and gas form a large flame zone inside the flame envelope, which significantly increases the rate at which the fuel is oxidized and at the same time creates large turbulence. Forming will also increase the diffusive mixing at the outer surface of the flame zone. The additional combustible material carried to the center of the flame envelope also serves as a quench mechanism to reduce the production of emissions such as nitrogen oxides and carbon monoxide. The additional rate of causing combustion while maintaining the two flame fronts also acts to reduce the production of carbon monoxide and soot, and also reduces the emission of unburned hydrocarbons.

  The fuel is injected from under the burner into the fuel jet and premix zone with sufficient momentum to easily take in air. Depending on the molecular weight of the fuel and the delivery pressure that can be used for uptake, the burner can take in air from 2 feet below the auxiliary fuel inlet.

  Preferably, the amount of fuel introduced into each premix zone of burners 30, 130, 230 and 330 ranges from about 5% to about 50% of the total amount of fuel to be burned by the flare burner, more preferably About 10% to about 30%. Most preferably, the amount of fuel introduced into the premix chamber ranges from about 10% to about 25% of the total amount of fuel to be burned by the flare burner. The amount of fuel introduced into the premix zone can be controlled by manipulating the fuel port diameter and fuel pressure.

  As the proportion of fuel introduced into the premix zone increases, the flame length becomes shorter and the smokeless performance of the burner increases. However, an appropriate balance between the proportion of fuel injected into the premix zone and the amount of air that can be drawn into the premix zone must be achieved. When using the fuel lean method, the amount of air taken into the premix zone is at least about 125% of the stoichiometric amount of air required to assist the combustion of fuel injected into the premix zone. It is usually important to be. If the amount of air is less than this ratio, a very reactive (flammable) mixture can be formed that tends to cause the burner to burnback or flash back at the maximum ratio, eventually damaging the burner. There is sex. As the amount of air taken in increases, the quench effect increases and the fuel flame speed decreases. This condition is ideal for increasing the ignition delay of the premix flow, and thus the premix flow ignition point is local to the flame core prior to combustion for maximum benefit. Is guaranteed.

  A sufficiently lean flow of air and fuel will ensure that the mixture does not ignite until the air / fuel mixture exits the air / fuel outlet and reaches the center of the flame envelope. If the fuel / air mixture exits the air / fuel outlet and enters the flame envelope, the mixture takes in enough additional fuel to become a combustible mixture, at which point the fuel is in the main flame envelope. Ignite inside. Such flow control forms an in-flame flame that has two separate flame fronts, ie, a toroidal flame structure. The additional turbulence created by the gas expanding at the center of the flame during combustion breaks down the high concentration fuel core and pushes this crushed piece of fuel to the outer flame boundary for the remaining fuel. Work to promote a mixed situation. This method reduces the flame height and the possibility of emitting smoke and increases overall combustion efficiency by promoting mixing.

  It is important that the air / fuel mixture in each premix zone of burners 30, 130, 230 and 330 does not combust until it exits the air / fuel outlet of the premix zone. If combustion occurs in the premix chamber, for example, back pressure will be applied to the premix chamber, and the amount of air taken into the premix chamber will be greatly reduced.

  By delivering only a portion of the fuel to be burned to each premix zone of burners 30, 130, 230 and 330, the overall cross-sectional dimensions of the burner are relatively small. If a burner is designed and constructed that can supply 100% of the air required for combustion throughout the premixing process, the size of the burner will be very large. Such burner venturi or mixer sections will inevitably be quite large and will lack the ability to accommodate low fuel pressures.

  Although the premixing chambers of each of the burners 30, 130, 230 and 330 of the present invention are relatively small, the assembled equipment is used to form a premixed flow of air and fuel incorporating a large amount of excess air. Sufficient air and fuel can be supplied. As a result, a significant increase in the overall fuel flow can be realized while the flame height and diameter remain the same. The burner of the present invention, depending on the type of fuel being burned, will deliver 1.4 times more fuel than is typically deliverable by the diffusion jet type burners used so far. Can be easily adapted to the fuel flow rate that can be designed. This can often be achieved with the same flame length and diameter approximately maintained. If a higher flame height is allowed, a fuel flow rate that is considerably higher than the diffusion jet type burners that have been used can be obtained. Furthermore, when combined with each embodiment of the burner of the present invention, the ignition interval and flame turndown capability can be maintained while increasing the fuel flow rate. For low molecular weight fuels, the flame emissivity can also be reduced somewhat by adjusting the flame, reducing the overall flame temperature. In some cases, this allows the burner to maintain the distance between the burner and the fence or to minimize this increase in distance as the fuel flow rate increases. Excess air delivered to the center of the flame not only supplies air to the center of the flame, but also serves to reduce the timed rate at which the resulting fuel cloud is oxidized as it exits the burner tip. This results in a cleaner, smokeless flame that is shorter in proportion to a given heat release. Fuel dilution and subsequent quenching action on the flame also serves to reduce emissions of nitrogen oxides and carbon monoxide. The fuel and air flow through the premix chamber also assists in cooling the burner assembly.

  Various configurations of the auxiliary fuel inlet have been described. Still other structures are possible, and these structures include a multi-point injector body or header that is drilled to maximize air intake and mixing in view of available fuel pressure. Each lower section of the previously described embodiments can include a Coanda surface or can be a straight section. If a Coanda surface is used, the auxiliary fuel inlet port may be a circular orifice (jet) or slot. In addition to Coanda technology, fuel can be injected at a relatively high rate to quickly obtain a fuel and air mixture that can be injected from the auxiliary fuel inlet into the center of the flame envelope. The dimensions of various parts of the inventive flare burner (including the premix chamber and fuel film dimensions) can be varied. In addition, a wide variety of port configurations (eg, port dimensions, spacing between ports) can be used in combination with the main and auxiliary fuel inlets. The particular dimensions and structure used will depend on the type of fuel and the molecular weight, temperature, heating value and reactivity of the fuel, operating parameters (eg, available pressure) and other factors.

  Although generally not necessary, a third inert fluid is placed in the premixing zone of the inventive flare burner (any of the flare burner embodiments) to increase air uptake into the premixing zone. Can be injected. Examples of third inert fluids that can be used include steam, air, and nitrogen. Steam is preferred.

  The drawings illustrate circular and rectangular (polygonal) embodiments of the inventive flare burner. Each of the flare burner embodiments of the present invention can also be formed in other geometric shapes. For example, in addition to circular and rectangular shapes, elliptical, triangular, square, pentagonal, octagonal and other polygonal shapes can be used. These other geometries may prove advantageous in terms of cost or manufacturing. The optimal method is to form a lean excess air stream that can be delivered from the premix chamber to the center of the flame body. However, even in fuel rich streams, the enhanced mixing provided by the burner of the present invention provides benefits over the diffusion-only type burners previously used.

Ground Flare of the Present Invention Referring to FIG. 29, a ground flare of the present invention is schematically illustrated and is generally indicated by reference numeral 420. The ground flare 420 includes a plurality of flare burners 422, an enclosure 424 extending around the flare burner, and a fuel supply line 426 for supplying fuel to the flare burner.

  Flare burners are arranged in rows 430 (a) to (f) and rows 432 (a) to (e). Rows 430 (a)-(f) form a first stage 434 of flare burner 422, and rows 432 (a)-(e) form a second stage 436 of flare burner 422. At least one of the flare burners 422 is one of the embodiments of the inventive flare burner described above. Preferably, each of the flare burners 422 in the second stage 436 (the burner used when a relatively high volume of fuel needs to be burned) is one of the flare burner embodiments of the present invention described above. If desired, each of the flare burners 422 in both the first stage 434 burner and the second stage 436 burner is one of the embodiments of the inventive flare burner described above.

  The fuel supply line 426 includes a main line 440 that terminates in the distribution manifold 442. A first stage supply line 444 and a second stage supply line 446 are attached to and in fluid communication with the distribution manifold 442. Individual first stage supply lines 450 (a)-(f) extend from the first stage fuel supply line 444 to corresponding burner rows 430 (a)-(f). Similarly, each second stage supply line 452 (a)-(e) extends from the second stage fuel supply line 446 to a corresponding burner row 432 (a)-(e). For example, the first end 382 of the main branch 380 of the fuel supply conduit 338 of the inventive flare burner 330 is attached to one of the individual supply lines 450 (a)-(f) or 452 (a)-(e). It has been. If another type of flare burner is also used for the ground flare 420, the fuel supply conduits of these burners are connected to one of the individual supply lines 450 (a)-(f) or 452 (a)-(e). Installed properly.

  A series of pilots 460 (a)-(f) are in fluid communication with the first stage supply line 444 and are appropriately spaced from the burner and fuel prior to ignition. The pilot is typically located near the first flare burner 422 in the corresponding row 430 (a)-(f). Similarly, a series of pilots 462 (a)-(e) are in fluid communication with the second stage supply line 446 and are located near the first flare burner 422 in the corresponding row 432 (a)-(e). Has been.

  Enclosure 424 surrounds flare burner 422 and includes a plurality of posts 470 and a fence section 472 coupled between the posts. The height of the enclosure or fence ranges from about 30 feet to about 60 feet (about 9.14 m to 18.3 m). Enclosure 424 is designed so that air can be drawn through the enclosure and from under the enclosure into the ground flare.

  In operation of the ground flare 420 of the present invention, the fuel to be combusted is introduced into the distribution manifold 442 through the main line 440. A valve control system (not shown) functions to distribute fuel to the first stage fuel supply line 444 or to both the first stage fuel supply line 444 and the second stage fuel supply line 446. When a relatively low volume of fuel is introduced into the distribution manifold 442, the valve system directs the fuel only to the first stage fuel supply line 444. When the volume of fuel gas introduced into distribution manifold 442 is relatively large, fuel is introduced into both first stage fuel supply line 444 and second stage fuel supply line 446. Additional stages can be incorporated to circulate fuel in and out. Fuel is directed from one or both of fuel supply lines 444 and 446 to corresponding individual supply lines 450 (a)-(f) and / or 452 (a)-(e), depending on the volume of the fuel. . Fuel is supplied from the individual supply lines 450 (a)-(f) and / or 452 (a)-(e) to the flare burners in the corresponding rows 430 (a)-(f) and 432 (a)-(e). 422.

  As required, pilots 460 (a)-(f) and pilots 462 (a)-(e) ignite the fuel released from the corresponding first burner 422 in each of the rows. The ignited fuel from the first burner 422 in each row then ignites the fuel released from the adjacent burner, and this fuel ignites the fuel emitted from the next burner in this row. In this way, ignition continues until the fuel released from each of the burners in this row is ignited. Air required for combustion is drawn through the walls of the enclosure 424 and / or from below the walls. There is no need to supply air separately to the burner 422 or ground flare.

  The ground flare of the present invention utilizes a relatively small volume of fuel (e.g., less than 3,000 pounds per hour (1361 kg)) to a very large volume of fuel gas (e.g., molecular weight of fuel being burned, pressure utilization). Depending on the potential, temperature and other factors, it can be used to burn 10,000 pounds to 15,000 pounds per hour (4,536 kg to 6,804 kg or more). Even at very high flow rates (eg, 10,000 pounds per hour (4,536 kg)), the flame envelope formed by the ground flare burner of the present invention can be housed in a typical ground flare enclosure. it can. The flare burner structure of the present invention allows higher volume fuels to be burned using smaller ports and higher pressure without significantly increasing the height of the flame envelope formed by the ground flare. Alternatively, the height of the flame can be reduced, thereby reducing the height of the enclosure 424. The burner of the present invention draws air from under the burner, which allows the burner to be placed closer to the ground, which also reduces the required height of the enclosure 424. . With fewer burners and associated parts, the required footprint will be smaller.

  In many cases, the ground flare burner 422 of the present invention is incorporated into an existing ground flare as an improved component, so that the height of the flame envelope is not much higher than the height of the enclosure around the ground flare. The fuel can be combusted. Also, the range of smokeless ratio at a given flame tip can be significantly increased by the structure of the burner. If an increase in throughput is realized, more gas can be delivered to individual headers. Thereby, the number of headers can be reduced, and the number of control mechanisms (for example, a gas control valve, a shutoff valve, a control valve, and physical piping) to which the headers are connected can be reduced. By increasing the capacity by reducing the number of headers, the enclosure 434 can be made smaller.

  The ground flare of the present invention can be used to burn various types of fuel gases. Examples of these gases are saturated hydrocarbons and unsaturated hydrocarbons (eg propane and propylene and mixtures of propane and propylene, mixtures of propane, propylene and hydrogen), steam and / or inert gases such as Nitrogen, carbon monoxide, argon and the like.

  The above description of the ground flare of the present invention is intended to illustrate how ground flare is used, particularly in connection with ground flare. As will be appreciated by those skilled in the art, the installation of ground flares determines how the ground flares are configured, the number and type of burners, headers, flow systems, control valves and associated components, and the enclosure surrounding the installation. There are various variations associated with type and height, as well as many other methods. The ground flare of the present invention includes any ground flare installation in which the flare burner of the present invention is used.

Inventive Method In accordance with the inventive method, fuel is combusted in one of the inventive flare burners 30, 130, 230 or 330. Referring to FIG. 24, fuel is injected into the combustion zone 101 through the fuel injector body (ie, main fuel outlet 36, 136, 236 or 336) and ignited to form the flame envelope 100 and burn the fuel. A portion of the fuel to be burned is taken into the premixing zone, including the premixing chamber of the burner (ie, the premixing chamber 32, 132, 232 or 332) and the fuel and air Of the mixture (preferably a substantially uniform mixture) is introduced to form in the premix zone. The mixture of air and fuel is then injected from the premix chamber into the center 104 of the flame envelope. As discussed above, the amount of air taken into the premix zone and injected into the center of the flame envelope is the stoichiometric amount of air required for combustion from the fuel rich and combustible mixture. It may be in the range of a mixture in which more than air is taken up. This premixed fuel and air flow injected into the center of the flame envelope initiates the second flame zone and forms a toroidal flame envelope. The overall result is that the entire flame envelope burns faster and more uniformly, which provides the advantages discussed above with respect to the inventive flare burner.

  As discussed above, the amount of air taken into the premix zone and injected into the center of the flame envelope is preferably required to assist in the combustion of fuel introduced into the premix zone. At least about 15% of the stoichiometric amount of air. In some applications, a “fuel rich” mixture of fuel and air (ie, less than 100% of the stoichiometric amount of air required to assist combustion of fuel introduced into the premix zone) It is appropriate to inject a mixture containing a quantity of air into the center of the flame envelope. However, in many applications, a “lean” mixture of fuel and air (ie, greater than 100% of the stoichiometric amount of air required to assist combustion of fuel introduced into the premix zone). It is desirable to inject a mixture having a quantity of air into the center of the flame envelope. In many applications, the amount of air taken into the premix zone and injected into the center of the flame envelope is the stoichiometry of air required to assist the combustion of fuel introduced into the premix zone. Range from about 125% to about 300% of the target amount.

  The amount of fuel introduced into the premix zone and premix chamber (ie, premix chamber 32, 132, 232 or 332) ranges from about 5% to about 50% of the total amount of fuel to be burned by the flare burner. More preferably, it is in the range of about 10% to about 30%, and most preferably in the range of about 10% to about 25%.

  In order to further illustrate the present invention, the following examples are given.

Example I
The flare burner 30, which is the first embodiment of the flare burner of the present invention, was compared with the prior art high capacity diffusion type ground flare burner, that is, the burner illustrated in FIGS. Two of the inventive flare burners were tested. One flare burner is about 30 inches (76.2 cm) in length and the other flare burner is about 16 inches (40.6 cm) in length. The flare burner port structure of the present invention was adapted to match the 3 square inch flow area contained in prior art flare burners.

  Initially, the inventive flare burner was tested alone. Tests were performed using propane and propylene. About 20% of the fuel was injected into each premix chamber of the inventive flare burner. The remaining fuel was then injected around the periphery of the air / fuel mixture released from the premix chamber. When using both types of fuel described above, it has been determined that each of the inventive flare burners can hold a significant amount of fuel flow while deploying a smokeless flame. It has been found that the flame envelope emitted from each burner is very stable, can have a high turndown ratio, and is highly symmetric throughout the entire range of combustion heat dissipation. The flame envelope emitted from each burner was observed to be very short in length and small in diameter.

  A flare burner of the present invention having a length of about 30 inches (76.2 cm) was then compared to a prior art burner. Two flare burners were tested side by side. The burners were attached to the same header to ensure that each burner was supplied with the same volume of fuel.

  At many of the observed test points, it has been observed that the inventive flare burner forms a flame envelope of shorter length. The flare burner of the present invention continued to burn even at low pressures during turndown, indicating that the range of operability has been somewhat expanded. At the maximum fuel flow, the flame envelope produced by the flare burner of the present invention was shorter in overall length than the flame envelope length of the prior art high volume diffusion type ground flare burner. However, in this scenario, the vertical cross section (width) of the flame envelope formed by the prior art flare burner was larger than the flame envelope formed by the inventive flare burner. In the flare burner of the present invention, no flashback was observed until the pressure was clearly below 1 psig (6.89 kPaG). It has been found that the radiation from the flame envelope produced by the inventive flare burner is equal to or slightly less than that produced by the flame envelope formed by the prior art flare burner. During turndown conditions, prior art flare burners emitted smoke at approximately the same rate as the inventive flare burner. At approximately the same flow rate and pressure, smoke flying from both burners may usually be observed. However, the flare burner of the present invention was found to maintain a lower concentration of smoke during the initial test at a lower pressure than the diffuser type burner tip. Prior art burners have changed to emit higher concentrations of smoke when pressure is reduced.

Example II
A flare burner 230, a third embodiment of the inventive flare burner, was also tested and compared to the prior art flare burners discussed above. The performance of this embodiment of the inventive flare burner has been found to be at least equivalent to prior art burners. However, the burner of the present invention emitted more smoke at lower pressure than the first embodiment of the inventive flare burner described in Example I. The range of smokeless operation was comparable to the smokeless performance of prior art flare burners.

  In this test, the corners of the premix chamber of the inventive flare burner formed a complex flow pattern that appeared to somewhat impede mixing conditions within the premix chamber. As a result, it was observed that a quasi-layered fuel-rich zone was formed at the corner of the premixed release region, and a visible smoke layer was observed over the entire surface of the flame zone. On the other hand, the tested flare burners of the present invention were able to process approximately three times the amount of fuel that could be processed by prior art flare burners.

  The weld used to assemble the inventive flare burner test unit described in this example was defective and eventually failed (after performing a significant amount of testing). The weld in question was used only for the test unit (made from carbon steel). Welding failures are not due to design problems and have nothing to do with actual burner operation or performance. In any case, tests have shown that the flare burner 230 is highly capable of handling large volumes of fuel flow while reducing the problem of flue gas.

  Thus, the present invention is well adapted to carry out the tasks and to achieve the objects and benefits described above and specific to the present invention. Many modifications may be made by those skilled in the art, and such modifications are encompassed within the spirit of the invention as defined by the appended claims.

FIG. 1 is a front view of a prior art ground flare burner. FIG. 2 is a top view of the flare burner shown in FIG. FIG. 3 is a schematic view of a flame envelope formed by the prior art flare burner shown in FIGS. FIG. 4 is a perspective view of the first embodiment of the ground flare burner of the present invention. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. FIG. 6 is a top view of the burner shown in FIGS. 4 and 5. FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 6 and shows the riser and / or tip extension used selectively. FIG. 8 shows another embodiment of an annular fuel injector body that can be used with the first, second and fourth embodiments of the inventive flare burner. FIG. 9 is a perspective view of a second embodiment of the flare burner of the present invention. 10 is a cross-sectional view taken along line 10-10 of FIG. FIG. 10A shows another embodiment of an annular distribution manifold used with the second embodiment. FIG. 11 is a top view of the flare burner shown in FIGS. 9 and 10. 12 is a cross-sectional view taken along line 12-12 of FIG. FIG. 13 is a perspective view of a third embodiment of the flare burner of the present invention. 14 is a cross-sectional view taken along line 14-14 of FIG. FIG. 15 is a top view of the flare burner shown in FIGS. 13 and 14. FIG. 16 is a cross-sectional view taken along line 16-16 of FIG. 13 and shows the riser or tip extension used selectively. 17 is a cross-sectional view taken along line 17-17 in FIG. FIG. 17A shows another embodiment of a tubular distribution manifold used with the third embodiment. 18 is a cross-sectional view taken along line 18-18 of FIG. FIG. 19 is a perspective view of a fourth embodiment of the flare burner of the present invention. 20 is a cross-sectional view taken along line 20-20 of FIG. FIG. 21 is a cross-sectional view taken along line 21-21 of FIG. 22, showing the burner components used selectively. FIG. 22 is a top view of the burner shown in FIGS. FIG. 23 shows another embodiment of the auxiliary fuel inlet of the burner shown by FIGS. FIG. 24 is a schematic view of a flame envelope formed by embodiments of the flare burner of the present invention. FIG. 25 is a perspective view showing the changes that can be made to each embodiment of the inventive flare burner. 26 is a cross-sectional view taken along line 26-26 of FIG. FIG. 27 is a top view of the burner shown in FIG. 25 and FIG. FIG. 28 is a schematic view of a flame envelope formed by each embodiment of the inventive flare burner modified in the manner illustrated by FIGS. FIG. 29 is a schematic diagram of one embodiment of a ground flare of the present invention.

Claims (46)

A premixing chamber, wherein the premixing chamber is disposed at the top, the bottom, a sidewall connecting the top to the bottom, an air inlet disposed at one of the bottom and the sidewall, and the top A premix zone having an air / fuel outlet;
An auxiliary fuel inlet for injecting fuel into the premixing zone, with respect to the premixing zone, fuel injection from the auxiliary fuel inlet into the premixing zone is air into the premixing zone; An auxiliary fuel inlet positioned such that a mixture of fuel and air is formed in the premixing zone and discharged from the air / fuel outlet of the premixing chamber;
Arranged at a main fuel outlet such that fuel can be injected from the main fuel outlet around the air / fuel outlet of the premixing chamber relative to the top of the premixing chamber. A main fuel outlet,
Flare burner with   The flare burner of claim 1, wherein the air inlet is located at the bottom of the premix chamber.   The flare burner of claim 1, wherein the main fuel outlet is spaced outward from the premixing chamber to provide an air intake space between the main fuel outlet and the premixing chamber.   The flare burner of claim 1, further comprising a fuel film disposed around an outer periphery of the premix chamber, the film including a fuel inlet and in fluid communication with the main fuel outlet.   The fuel film and the main fuel outlet are spaced apart from the premix chamber to provide an air intake space between the fuel film and main fuel outlet and the premix chamber. Item 5. The flare burner according to Item 4.   The flare burner of claim 4, wherein the membrane is also in fluid communication with the auxiliary fuel inlet.   The flare burner of claim 1, further comprising a fuel supply conduit in fluid communication with the auxiliary fuel inlet and the main fuel outlet for directing fuel to the auxiliary fuel inlet and the main fuel outlet.   The flare burner of claim 1, wherein the main fuel outlet comprises a plurality of fuel ports disposed around an outer periphery of the air / fuel outlet of the premix chamber.   The premixing chamber including the air / fuel outlet, the fuel membrane, and the main fuel outlet each have a circular cross-section so that fuel can flow from the main fuel outlet to the outer periphery of the air / fuel outlet. The flare burner according to claim 4, wherein the flare burner can be sprayed in an annular shape around the periphery.   The flare burner of claim 1, wherein the sidewall of the premix chamber includes an inner surface and an outer surface, the inner surface having a section that is a Coanda surface.   The flare burner of claim 10, wherein the auxiliary fuel inlet is positioned relative to the premixing chamber such that fuel can be injected from the auxiliary fuel inlet onto the Coanda surface.   The flare burner of claim 4, wherein the sidewall of the premix chamber includes an inner surface and an outer surface, the inner surface having a section that is a Coanda surface. The air inlet is disposed at the bottom of the premix chamber, the premix chamber including the air inlet, the membrane and the auxiliary fuel inlet each have a circular cross-section;
The flare burner of claim 12, wherein the Coanda surface extends annularly around the inner surface of the side wall of the premix chamber.   The flare burner according to claim 13, wherein the auxiliary fuel inlet is disposed at a position with respect to the premixing chamber such that fuel can be injected annularly from the auxiliary fuel inlet onto the Coanda surface.   The inner surface includes two opposing sections that are Coanda surfaces, and the auxiliary fuel inlet, relative to the premixing chamber, fuel is injected from the auxiliary fuel inlet onto each of the Coanda surfaces. The flare burner according to claim 10, wherein the flare burner is arranged at such a position.   The flare burner of claim 1, wherein the ratio of the length of the premix chamber to the inner hydraulic diameter is in the range of about 0.25: 1 to about 4: 1.   The flare burner of claim 1, wherein the ratio of the length of the premix chamber to the inner hydraulic diameter is about 1: 1 or less. A premixing chamber, the premixing chamber having a top, a bottom, a sidewall connecting the top to the bottom, an air inlet disposed at the bottom, and an air / fuel outlet disposed at the top; And a ratio of the length of the premix chamber to the inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1;
An auxiliary fuel inlet for injecting fuel into the premixing zone, with respect to the premixing zone, fuel injection from the auxiliary fuel inlet into the premixing zone is air into the premixing zone; An auxiliary fuel inlet positioned such that a mixture of fuel gas and air is formed in the premixing zone and discharged from the air / fuel outlet of the premixing chamber;
Arranged at a main fuel outlet such that fuel can be injected from the main fuel outlet around the air / fuel outlet of the premixing chamber relative to the top of the premixing chamber. A main fuel outlet,
A fuel supply conduit in fluid communication with the auxiliary fuel inlet and the main fuel outlet to direct fuel to the auxiliary fuel inlet and the main fuel outlet;
Flare burner with   The flare burner of claim 18, wherein the premixing chamber including the air inlet and the air / fuel outlet and the main fuel outlet have a circular cross section.   The flare burner of claim 18, wherein the main fuel outlet is spaced outwardly from the premixing chamber to provide an air intake space between the premixing chamber and the main fuel outlet. .   An annular fuel membrane disposed around an outer periphery of the premix chamber, the membrane being in fluid communication with the main fuel outlet, and connecting the top, bottom, and top to the bottom; The flare burner of claim 19 having a side wall.   The flare burner of claim 21, wherein the main fuel outlet comprises a plurality of fuel ports attached to the top of the fuel membrane and extending around an outer periphery of the air / fuel outlet of the premix chamber.   The fuel membrane and the main fuel outlet are spaced apart from the premixing chamber to provide an air intake space between the premixing chamber and the fuel membrane and the main fuel outlet. 23. A flare burner according to claim 22.   The flare burner of claim 18, wherein the ratio of the length of the premix chamber to the inner hydraulic diameter is not greater than about 1: 1.   The flare burner of claim 24, wherein the auxiliary fuel inlet is spaced below the air inlet of the premix chamber.   The flare burner of claim 18, wherein the air / fuel outlet of the premix chamber is spaced above the main fuel outlet. A ground flare including a plurality of flare burners, an enclosure extending around the flare burner, and a fuel supply line for supplying fuel to the flare burner, wherein at least one of the flare burners comprises:
A premixing chamber having a top, a bottom, a sidewall connecting the top to the bottom, an air inlet disposed on one of the bottom and the sidewall, and an air / fuel outlet disposed on the top Including a premix zone,
An auxiliary fuel inlet for injecting fuel into the premixing zone, with respect to the premixing zone, fuel injection from the auxiliary fuel inlet into the premixing zone is air into the premixing zone; An auxiliary fuel inlet positioned such that a mixture of fuel gas and air is formed in the premixing zone and discharged from the air / fuel outlet of the premixing chamber;
A main fuel outlet, relative to the upper part of the premixing chamber, where fuel can be injected from the main fuel outlet around the periphery of the air / fuel outlet of the premixing chamber A main fuel outlet arranged in the
Including ground flare.   28. A ground flare as claimed in claim 27, wherein the air inlet is located at the bottom of the premix chamber.   28. A ground according to claim 27, wherein the main fuel outlet is spaced outward from the premix chamber to provide an air intake space between the premix chamber and the main fuel outlet. Flare.   28. The ground flare of claim 27, wherein the flare burner further comprises a fuel film disposed around an outer periphery of the premix chamber, the film including a fuel inlet and in fluid communication with the main fuel outlet. .   The fuel membrane and the main fuel outlet are spaced apart from the premixing chamber to provide an air intake space between the premixing chamber and the fuel membrane and the main fuel outlet. The ground flare of claim 30.   The ground flare of claim 30, wherein the membrane is also in fluid communication with the auxiliary fuel inlet.   28. The ground flare of claim 27, further comprising a fuel supply conduit in fluid communication with the auxiliary fuel inlet and the main fuel outlet for directing fuel to the auxiliary fuel inlet and the main fuel outlet.   28. A ground flare as claimed in claim 27, wherein the main fuel outlet comprises a plurality of fuel ports disposed around an outer periphery of the air / fuel outlet of the premix chamber.   The premixing chamber including the air / fuel outlet, the fuel membrane, and the main fuel outlet each have a circular cross-section so that fuel flows from the main fuel outlet to the periphery of the air / fuel outlet. The ground flare according to claim 30, wherein the ground flare can be sprayed in a ring shape.   28. The ground flare of claim 27, wherein the sidewall of the premix chamber includes a section that includes an inner surface and an outer surface, the inner surface being a Coanda surface.   The flare burner of claim 36, wherein the auxiliary fuel outlet is positioned relative to the premixing chamber such that fuel can be injected from the auxiliary fuel outlet onto the Coanda surface.   31. The ground flare of claim 30, wherein the sidewall of the premix chamber includes a section that includes an inner surface and an outer surface, the inner surface being a Coanda surface. The air inlet is disposed at the bottom of the premix chamber, the premix chamber including the air inlet, the membrane and the auxiliary fuel inlet each have a circular cross-section;
39. The ground flare of claim 38, wherein the Coanda surface extends annularly around the inner surface of the side wall of the premix chamber.   40. A ground flare according to claim 39, wherein the auxiliary fuel inlet is positioned relative to the premixing chamber such that fuel can be injected annularly from the auxiliary fuel inlet onto the Coanda surface. .   The inner surface includes two opposing sections that are Coanda surfaces, and the auxiliary fuel inlet, relative to the premixing chamber, fuel is injected from the auxiliary fuel inlet onto each of the Coanda surfaces. The ground flare according to claim 36, wherein the ground flare is disposed at such a position. A method of combusting fuel using a flare burner, wherein the fuel to be combusted is injected into the combustion zone through the fuel outlet of the burner and ignited to form a flame envelope and combust the fuel.
Introducing a portion of the fuel to be burned into the premix zone of the burner so as to entrain air into the premix zone and form a mixture of air and fuel in the premix zone;
Injecting a mixture of the air and fuel from the premixing zone into the center of the flame envelope;
Including methods.   The amount of air taken into the premix zone and injected into the center of the flame envelope is the stoichiometric amount of air required to assist the combustion of fuel introduced into the premix zone. 43. The method of claim 42, wherein the method ranges from about 125% to about 300% of the amount.   The amount of air taken into the premix zone and injected into the center of the flame envelope is the stoichiometric amount of air required to assist the combustion of fuel introduced into the premix zone. 44. The method of claim 43, wherein the method ranges from about 150% to about 300% of the amount.   43. The method of claim 42, wherein the amount of fuel introduced into the premix zone ranges from about 5% to about 50% of the total amount of fuel to be burned by the flare burner.   46. The method of claim 45, wherein the amount of fuel introduced into the premix zone ranges from about 10% to about 30% of the total amount of fuel to be burned by the flare burner.

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