KR20080029901A - Partial pre-mix flare burner and method - Google Patents

Abstract

A partial pre-mix flare burner and a method using the same are provided to lower the height of a flame envelope and to increase the volume of fuel, which is burned, relative to the predetermined length of the flame envelope. A flare burner comprises a pre-mix area having a pre-mix chamber(32), an auxiliary fuel inlet(34) and a main fuel outlet(36). The pre-mix chamber includes an upper portion(42), a lower portion(44), a sidewall(46) for connecting the upper portion and the lower portion, an air inlet(48) provided in the upper portion or the sidewall, and an air/fuel outlet(50) provided in the upper portion. The auxiliary fuel inlet is located at a predetermined position in the pre-mix area such that mixture of fuel and air is formed in the pre-mix area. The main fuel outlet is located at a predetermined position in the upper portion of the pre-mix area such that the fuel is sprayed from a peripheral portion of the air/fuel outlet.

Description

PARTIAL PRE-MIX FLARE BURNER AND METHOD}

The present invention relates to a flaring apparatus and a method of flaring flammable waste gas and diverted fuel stock. In one embodiment, the present invention relates to a ground flare burner, a ground flare and a method associated therewith.

Flare devices and methods are used to burn and dispose of flammable waste gases and converted fuel raw materials in various applications. For example, flares are typically placed in production facilities, refineries, process plants, etc., for disposal of abandoned flammable waste gases and / or fuel feed streams that are diverted during aeration, shutdown, upset or emergency conditions. Flaring of the flammable waste gas and the converted fuel raw material (hereinafter referred to as "fuel"), which does not generate smoke, is generally preferred or indeed essential. Smokeless flaring is achieved by ensuring that unoxidized soot is not formed in an amount sufficient to leave the flame. This is accomplished by ensuring that a sufficient amount of oxygen is mixed with the fuel to prevent the mixture from becoming too fuel rich and ineffective.

In many applications, the length of the flame envelope generated by the flares is also important. Examples of flare types for which a relatively short flame envelope is preferred include aesthetic flares such as pit-type enclosed flares, ground flares and high pressure flares on floating production equipment. In such flares, it is often necessary to make the flame invisible to the surrounding organizations. On the other hand, such flares need to 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 to be burned increases.

Ground flares, also known as multi-point flares, are commonly used in applications where the amount of fuel to be burned at any given time can vary from a relatively small volume to a very large volume (eg, over 1,000,000 pounds per hour). . Multiple stage burners are used to accommodate changes in fuel volume and allow fuel to be burned in a lead-free manner. The flow to each stage of the burner is guided by a control system that responds to the pressure and volume of fuel to be burned. In this way, each burner can utilize sufficient pressure in operation to ensure that an adequate amount of air is entrained and that the air and fuel are sufficiently mixed to ensure reliable lead-free combustion within the scope of application.

Ground flare systems are typically spread over large areas, such as three acres, and surrounded by large fences or other enclosures. The enclosure functions to reject humans and animals from the flame zone and to minimize radiation, visibility, and noise into the surrounding area. The enclosure typically consists of a metal or other heat resistant material and is 20 to 60 feet in height. As a result, it can be costly to manufacture and maintain the enclosure.

In the ground flare system, the burner space and fuel flow rate are also important. The burners need to be close enough to each other so that cross-lighting can occur and generally need to be packed close enough to reduce the size of the system and the surrounding enclosure as a whole. In terms of cost, it is desirable to minimize the number of ignition pilots. A typical unit includes a single pilot at the end of each row of burners. On the other hand, the burners should not be so close to each other that they limit air flow and hinder smokeless combustion or that the flames coalesce into a ball of fire that exceeds the height of the enclosure. In addition, the flow rate of the fuel must be controlled so that the height of the individual flame does not exceed the enclosure height.

One type of ground flare burner that has been used so far includes a plurality of diffusion jets for distributing fuel and drawing in the air required for combustion. This diffusion jet is injected into the atmosphere at a sufficient speed to draw combustion air into the jet. When the fuel is ignited, air from the surrounding environment is entrained laterally from above the discharge point of the fuel. As the speed of the stream decreases, the buoyancy effect of the hot gas affects the overall mix of fuel and air, allowing the combustion of the remaining fuel to complete.

The entire flame envelope produced by using only a diffusion jet to disperse the fuel and entrain it in a lateral splash of the air needed for combustion comprises a central fuel-rich core. The central core of this fuel remains intact until the outer portion of the flame envelope begins to burn. As the outer portion of the flame envelope burns, air may enter the inner boundary of the flame envelope to complete the oxidation process. Unfortunately, due to the interaction of the individual fuel jets, the rich fuel core formed in the center of the flame envelope makes it difficult to support large capacity by increasing the flow rate of the fuel without increasing the length of the flame envelope and / or generating smoke. . Increasing the length of the flame envelope often results in higher enclosure heights surrounding the ground flare, which can significantly increase the cost of the enclosure.

According to the present invention, useful flare burners are provided in connection with ground flares, high pressure flares and other types of flares. For example, the flare burners of the present invention solve the problems associated with on-ground flare burners that have been used so far. The present invention also provides a fuel flaring method in a ground flare device and a flare burner.

According to the present invention, there is provided a flare burner capable of burning a large volume of fuel using a relatively short flame envelope. Reducing the length of the flame envelope has many advantages. For example, the height of the enclosure surrounding the ground flare may be lowered or the volume of fuel burnable using existing enclosure height may be increased.

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

The premix chamber includes sidewalls connecting the upper, lower and upper portions to the lower portion. The side wall includes an inner side and an outer side. The air inlet is arranged at one of the bottom and side walls, and the air / fuel outlet is arranged at the top.

The auxiliary fuel inlet is disposed at a predetermined position with respect to the premix zone such that when air is injected from the auxiliary fuel inlet into the premix zone, air is splashed into the premix zone, whereby a mixture of fuel and air is formed in the premix zone. To the air / fuel outlet of the premix chamber.

The main fuel outlet is arranged at a predetermined position relative to the top of the premix chamber such that fuel can be injected from the main fuel outlet around the main system of the air / fuel outlet of the premix chamber. In one embodiment, the main fuel outlet is spaced outward from the premix chamber to provide a space between the outer surface of the premix chamber sidewall and the main fuel outlet. As described below, this space allows fresh air to be entrained from below the burner to a point adjacent to the fuel port disposed inside the main fuel outlet. Improved mixing by this droplet entrainment may be important in certain applications, such as when burning high molecular weight hydrocarbons or unsaturated fuels.

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

The flare burner of the present invention may further comprise a fuel membrane disposed around the outer perimeter of the premix chamber. This 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 aforementioned air droplet entrainment space, the fuel membrane may be spaced apart from the outer side of the sidewall of the premix chamber.

Depending on the particular configuration of the flare burners of the present invention, the premix region may consist of the premix chamber alone or may comprise a premix chamber with regions below and / or above the actual premix chamber. For example, when 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, fuel and air begin to mix below the air inlet and the premix chamber. In addition, fuel and air typically continue to mix above the air / fuel outlet disposed above the premix chamber prior to ignition and combustion in the combustion zone.

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

In order to enhance the droplet entrainment of the air resulting from injecting fuel through the auxiliary fuel inlet into the premix region, the inner surface of the premix chamber may include a portion that is a Coanda surface. The auxiliary fuel inlet is positioned at a location relative to the premix chamber such that fuel can be injected from the auxiliary fuel inlet onto the coanda surface. The fuel tends to follow and maintain the path of the Coanda surface, and can form a relatively thin film to allow more air to be entrained in the premix chamber and for better mixing of the fuel and air within the premix chamber.

The premix chamber may have a ratio of length to inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1. Units with premix chambers having a ratio of length to inner hydraulic diameter greater than 4: 1 function to have additional advantages but are generally limited in terms of cost. In one embodiment, the premix chamber has a ratio of length to inner hydraulic diameter in the range of about 1: 1 to about 3: 1. In another embodiment, the premix chamber has a ratio of length to inner hydraulic diameter of about 1: 1 or less. Relatively short length premix chambers may be advantageous for ground flares, other flare applications where the length (or height) of the burners is important, or where highly reactive fuels will internally burn. Also in some configurations, the fuel has a secondary fuel inlet (e.g., a plurality of small jets or high pressures) under conditions that allow the attainment of uniform mixing of air and fuel even when the premix chamber has a very small length to inner hydraulic diameter ratio. Sprayed from.

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

The present invention also includes a fuel flaring method using a flare burner, wherein the fuel to be burned is injected through the fuel outlet of the burner into the combustion zone and ignited to produce a flame envelope and burn the fuel. According to the method of the present invention, a portion of the fuel to be burned is injected into the premix region of the flare burner in such a manner as to entrain air into the premix region and produce a mixture of air and fuel in the premix region. The mixture of air and fuel is injected from the premix zone into the central portion of the flame envelope.

The amount of air entrained in the premix zone and injected into the central portion of the flame envelope is preferably at least about 15% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone. In some applications, a mixture of “fuel-rich” fuel and air into the central portion of the flame envelope (ie, a mixture having less than 100% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone). Spraying) is appropriate. However, in most applications, more than 100% of the stoichiometric amount of air required to support combustion of a mixture of “fuel lean” fuel and air into the central portion of the flame envelope (ie, fuel injected into the premix zone). It is preferable to spray the mixture). In most applications, the amount of air splashed into the premix zone and injected into the central portion of the flame envelope is from about 125% to about 300 of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone. Belongs to the range of%.

The amount of fuel injected into the premix zone is preferably in the range of about 5% to about 50% of the total amount of fuel to be burned by the flare burner. By injecting the premix fuel stream into the central portion of the flame envelope according to the method of the invention, the flame envelope comprises combustion at its center as well as at its outer side. The resulting toroidal flame creates turbulence that results in additional mixing and combustion of a more uniform and rapid flame envelope. As a result, the height of the flame envelope can be lowered or the volume of fuel burnable using a given flame envelope can be increased. Other advantages are achieved by the flare burner and flaring method of the present invention.

It is therefore a general object of the present invention to provide a flare burner and a method associated therewith which are capable of burning a large amount of fuel in a relatively short and uniform flame envelope.

The flare burner according to the present invention can burn large volumes of fuel using a relatively short flame envelope. By injecting the premix fuel stream into the central portion of the flame envelope, since the flame envelope burns not only at its outer side but also at its center, turbulent flows occur, resulting in further mixing and combustion of the more uniform and faster flame envelope. Will generate Thus, it is possible to lower the height of the flame envelope and further increase the volume of fuel that can be burned for the length of a given flame envelope.

Other additional objects and advantages of the present invention will become more apparent to those skilled in the art upon reading the description of the preferred embodiment described below with reference to the accompanying drawings.

With reference to the drawings, in particular FIGS. 1 to 3, a ground flare burner of the prior art is generally shown and indicated by the reference numeral 10. The burner 10 of the prior art includes a burner casting 12 attached to the burner riser 14. Burner casting 12 includes a central portion 15 and a plurality of fuel outlet arms 16 disposed concentrically around the central portion and the top of riser 14. Each fuel outlet arm 16 includes one or more fuel ports 18. The fuel is supplied directly to the fuel port 18, ie the fuel is not initially premixed with air. As a result, the fuel jet generated by the fuel port 18 becomes a diffusion fuel jet.

3 shows a flame envelope 20 generally produced by the burner 10. Fuel (typically indicated by black arrows) is injected into the combustion zone 22 at high speed through the fuel port 18, which draws air into the fuel jet. Air from the surrounding environment is entrained laterally from above the discharge point of the fuel. As the speed of the stream decreases, the buoyancy effect of the hot gas then affects the overall mixing of the fuel and allows complete combustion. The flame envelope 20 as a whole includes a central core 24 having a predetermined length 23 and rich in fuel. The central core 24 of the fuel remains unoxidized until the outer portion 26 of the flame 22 begins to burn. Although the central portion of the flame envelope may include some air pockets 28, the amount of air in the air pockets is insufficient to support homogeneous combustion of the central core 24 of the fuel. The fuel-rich center core 24 generally remains intact until the outer portion 26 of the fuel is sufficiently weakened to allow a sufficient amount of air to enter the inner range of the flame envelope and to allow the oxidation process to complete. Keep it. Unfortunately, the fuel-rich central core 24 in the center of the flame envelope 20 increases the flow rate of fuel to support large flames without increasing the length of the flame and / or generating smoke. Makes things difficult

Of the present invention Flare  burner

4 to 8, one embodiment of the flare burner of the present invention is indicated in parallel with reference numeral 30. The flare burner 30 includes a premix region 31 including a premix chamber 32, an auxiliary fuel inlet 34, a main fuel outlet 36 and a fuel feed conduit 38 for injecting fuel into the premix region. It includes. As used herein and in the appended claims, "fuel" refers to waste gas that will be burned by the flare burner, flare apparatus (e.g., ground flare apparatus of the present invention) and method of the present invention. , Raw material of a dedicated fuel and / or other gas or liquid. The liquid can be formed, for example, when the partial pressure of a large molecular weight unsaturated or saturated fuel is at or below the standard state. As shown in FIG. 4, pilot 40 is coupled with burner 30 (also including burners 130, 230, and 330, described below) to initially ignite the mixture of fuel and air discharged by the burner. Can be.

In the embodiment shown in FIGS. 4-8, the premix chamber 32 of the flare burner 30 occupies a significant portion of the premix region 31. A mixture of fuel and air (preferably a substantially homogeneous mixture) may be formed in the premix region 31 that includes the premix chamber 32. As will be described later, the mixture formed in the premix region 31 may be a rich or thin fuel mixture. The premix chamber 32 has a round cross section and a cylindrical shape. The premix chamber has an upper portion 42, a lower portion 44, a side wall 46 connecting the upper portion to the lower portion, an air inlet 48 disposed at the lower portion 44, and an air / fuel outlet 50 disposed at the upper portion 42. ). As shown, the top 42 and bottom 44 are open to form an air inlet 48 and an air / fuel outlet 50. As a result, the air inlet 48 and the air / fuel outlet 50 each also have a round cross section. The lower portion 52 of the premix chamber 32 is spread outward so that the lower portion has a (very round) longitudinal shape to increase the flow rate of the fuel and air flowing therein. Alternatively, the lower portion 52 of the premix chamber 32 does not spread outwards, ie the entire premix chamber has a uniform cylindrical shape. As best shown in FIG. 5, the premix region 31 is located in the premix space 31a (below the auxiliary fuel inlet 34 and the bottom 44, and under the auxiliary fuel inlet and premix chamber below the premix chamber 32). Between the air inlet 48, the interior 31b of the premix chamber, and the premix space 31c directly above the air / fuel outlet 50 and the top 42 of the premix chamber. In the embodiment shown in Figs. 4-9, the main mixing of the premix air and fuel takes place in the interior 31b of the premix chamber 32 and in the premix space 31c.

The premix chamber 32 has a ratio of length (or height) to inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. The exact ratio of the length (or height) of the premix chamber 32 to the inner hydraulic diameter will depend, in part, on the type of fuel to be burned and the pressure available for droplet entrainment and mixing. In general, long premix chambers can result in better mixing of fuel and air therein, but this advantage is balanced by cost and other considerations. In a preferred embodiment the ratio of the length (or height) of the premix chamber 32 to the inner hydraulic diameter is about 1.5: 1. As used in this specification and the appended claims, "inside hydraulic diameter" means four times the internal area of the premix chamber divided by the perimeter of the inner side of the sidewall of the premix chamber.

The auxiliary fuel inlet 34 is disposed at a predetermined position with respect to the premix region 31 so that when fuel is injected from the auxiliary fuel inlet into the premix region, the auxiliary fuel inlet 34 passes through the air inlet 48 and into the premix space 31a. 32) is entrained in air, thereby allowing a mixture of fuel and air, preferably a substantially homogeneous mixture, to be formed in the premix zone and discharged to the air / fuel outlet 50 of the top 42 of the premix chamber. Fuel and air continue to mix in the premix space 31c. The mixture of fuel and air is typically not combusted until the mixture exits the air / fuel outlet 50, ie generally the separation distance from the air / fuel outlet. The separation distance from the air / fuel outlet 50, where combustion occurs, depends on the amount of air in the mixture and the speed of the mixture exiting the air / fuel outlet. In some cases, due to the timing sequence of the short de-stage, combustion may occur in the premix region (eg, according to the scheme of very low pressure, for a short duration). 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 membrane 60 is disposed around the outer periphery of the premix chamber 32. The fuel membrane 60 is connected to the fuel feed conduit 38 and in fluid communication with the main fuel outlet 36. The fuel membrane 60 includes an open top 62, a bottom 64 and an inner sidewall 67 and an outer sidewall 66 connecting the top to the bottom. In the embodiment shown in FIGS. 4-8, the inner sidewall 67 of the fuel membrane 60 also becomes the sidewall 46 of the premix chamber 32. The annular seal 68 is secured to the lower portion 64 of the fuel membrane 60 and extends around the sidewalls 46 of the premix chamber 32 to ensure the integrity of the membrane. In a variant, as illustrated in FIGS. 25-28 and described below, the fuel membrane 60 may include a premix chamber to provide an annular space between the outer surface of the sidewall 46 and the main fuel outlet 36. 32 may be spaced outward from sidewall 46. The annular space allows air to be entrained from below the burner to a point adjacent to the fuel port 74 disposed on the inner side of the main fuel outlet 36. In this embodiment, the inner sidewall 67 of the fuel membrane 60 is distinct from the sidewall 46 of the premix chamber 32.

The main fuel outlet 36 has a predetermined position relative to the upper portion 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. Is placed on. As best shown in FIG. 6, the main fuel outlet 36 includes a flat, annular fuel injector body 70 with a plurality of fuel ports 74 therein. The fuel jet generated by the fuel port 74 is a diffusion fuel jet. The annular fuel injector body 70 is secured to the open top 62 of the annular membrane 60 such that the fuel port 74 is disposed around the perimeter 69 of the air / fuel outlet 50 of the premix chamber. . The inner and outer diameters of the annular membrane 60 and the annular fuel injector body 70 are approximately the same. Fuel may be injected annularly around the main system 69 of the air / fuel outlet 50 from the main fuel outlet 36 (ie the annular fuel injector body 70). The fuel port 74 may be sized and spaced to control how fuel is injected from the port (eg, direction and speed). This feature, associated with the flow of fuel and air through the air / fuel outlet 50, allows the shape and length of the entire flame envelope to be controlled.

As shown in FIG. 7, the diffusion fuel port 74 may be spaced from the fuel injector body 70 by a plurality of corresponding short gas risers or tip extensions 76, as desired. Using the riser 76 to space the fuel port 74 from the fuel injector body 70 may result in better lateral droplet entrainment of air in some applications. The riser also allows mechanical changes in port shape and thus fuel flow characteristics as needed.

A variant of the annular fuel injector body 70 is shown in FIG. 8. In this variant, the plurality of fuel ports 74 are strategically spaced around the outside, inside and center of the fuel injector body 70. Spacing the fuel port 74 around the fuel injector body 70 in this manner allows the droplet entrainment passages between the jets to be used for better mixing and droplet entrainment. As will be appreciated by those skilled in the art, the injector body 70 may include a fuel port 74 that is variously repeated. The particular port shape used will depend on a variety of factors including the type of fuel to be burned (including molecular weight, calorific value, stoichiometry and temperature of the stream) and the pressure available in connection with it.

The fuel supply conduit 38 is in fluid communication with the auxiliary fuel inlet and the main fuel outlet 36 to direct fuel to the auxiliary fuel inlet 34 and the main fuel outlet. The fuel feed conduit 38 includes a main branch 80 having a first end 82 and a second end 84. The first end 82 comprises a flange 86 for connecting the first end to a source of fuel (as will be appreciated by those skilled in the art, this type of connection is more generally made by welding pipe sections directly to each other or Or with some other mechanical connection that does not require a gasket, for example a gasket between corresponding flanges generally cannot tolerate radiant heat in the surrounding environment). The second end 84 is connected to a corresponding inlet 88 at the outer sidewall 66 of the fuel membrane 60. The fuel feed conduit 38 also includes an auxiliary branch 90 that connects the fuel feed conduit to the auxiliary fuel inlet 34. The secondary 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 fuel feed conduit 38. The coupling 96 connects the second end 94 to the auxiliary fuel inlet 34. Alternatively, a separate fuel feed conduit or riser may direct fuel to the secondary fuel inlet 34 and main fuel outlet 36 (as opposed to a single unitary conduit or riser 38). A separate conduit or riser typically extends from the common fuel header.

The operation of the flare burner 30 will be described with reference to FIG. 5. The portion of the fuel to be burned (usually indicated by the black arrow) is guided through the main branch 80 of the fuel feed conduit 38 to the fuel membrane 60 and to the main fuel outlet 36. A portion of the fuel to be burned is also guided from the auxiliary branch to the auxiliary fuel inlet 34 through the auxiliary branch 90 of the fuel feed conduit 38. When fuel is injected from the auxiliary fuel inlet 34 into the premix region 31 and the premix chamber 32, air is splashed into the premix space 31a and through the air inlet 48 into the interior 31b of the premix chamber. Thus, a mixture of fuel and air (preferably substantially homogeneous mixture) is formed in the premix zone and exits the air / fuel outlet 50. Fuel and air continue to mix over a short distance above the air / fuel outlet 50. The remaining fuel to be burned is annular around the main system 69 of the air / fuel outlet 50 of the premix chamber from the main fuel outlet 36 and further around the air / fuel mixture which is discharged to the air / fuel outlet of the premix chamber. Sprayed. The burner is designed and designed in such a way that the amount of air entrained into the premix region 31 including the premix chamber 32 exceeds the stoichiometric amount of air required to combust the fuel injected into the premix region. It is desirable to work. Excess air is supplied to the center of the flame envelope so that fuel is burned inside the flame envelope. However, as will be discussed below, in some applications, the burner may have a stoichiometric amount of air required to burn fuel injected into the premix region with the amount of air entrained in the premix region 31 including the premix chamber 32. It is designed and operated in such a way as to be below (the fuel can still burn). In some applications, a mixture of "fuel-rich" fuel and air (ie, a mixture having less than the stoichiometric amount of air required to support combustion of fuel injected into the premix zone) is injected into the central portion of the flame envelope. It is desirable to.

FIG. 24 shows the flame envelope 100 produced by the flare burner 30 (including the burners 130, 230 and 330 described below). As shown, excess air is injected from the premix chamber 32 into the central portion 102 of the flame envelope 100. Excess air, indicated by air pocket 103 in FIG. 24, mixes with fuel in the central portion 102 of flame envelope 100 to effectively form two initial flammable regions, that is, regions 104a and 104b. Otherwise, the fuel in the central portion 102 of the flame is not in contact with the oxidant (air) until the outer portion 105 of the flame envelope begins to combust and the next fuel layer is able to contact air. Supplying air to the central portion 102 of the flame envelope 100 not only creates a flammable central region but also disperses the flame when the inner combustion region expands due to combustion heat. The addition of separate combustion flames within a large main flame significantly increases turbulence which improves mixing, destroying the central core of the fuel. As a result, a more uniform and rapid flame envelope may be burned to shorten the overall length of the flame or to burn significantly more fuel at the same flame length. As the excess amount of air supplied to the central portion 102 of the flame envelope 100 increases, the length of the flame decreases or the volume of fuel that can burn at a given flame height increases. For example, as shown in FIG. 24, the flame envelope 100 will have a length 106 that is significantly shorter than the length 23 of the flame envelope 20 of the prior art shown in FIG. 3 in the same amount of fuel. .

9 to 12, a second embodiment of the flare burner of the present invention is indicated in parallel with reference numeral 130. Like the flare burner according to another embodiment of the present invention, the flare burner 130 includes a premix region 131 including a premix chamber 132, an auxiliary fuel inlet 134 for injecting fuel into the premix region, A main fuel outlet 136 and a fuel feed conduit 138. A pilot (such as shown in FIG. 4) may be coupled to burner 130 to initially ignite the mixture of fuel and air released by the burner.

In the embodiment shown in FIGS. 9-12, the premix chamber 132 of the flare burner 130 occupies a significant portion of the premix region 131. A mixture of fuel and air (preferably a substantially homogeneous mixture) can be formed in the premix region 131 including the premix chamber 132. As will be described later, the mixture formed in the premix region 131 may be a rich fuel or a lean fuel mixture. The premix chamber 132 has a round cross section and a cylindrical shape. The premix chamber includes a top 142, a bottom 144, sidewalls 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. do. As shown, top 142 and bottom 144 are open to form air inlet 148 and air / fuel outlet 150. As a result, the air inlet 148 and the air / fuel outlet 150 each also have a round cross section.

As best shown in FIG. 10, the premix region 131 is located in the premix space 131a below the premix chamber 132 (between the auxiliary fuel inlet 134 and the bottom 144 and of the auxiliary fuel inlet and the premix chamber). Between the air inlet 148, the interior 131b of the premix chamber, and the top 142 of the premix chamber and the premix space 131c directly above the air / fuel outlet 150. In the embodiment shown in Figs. 9-12, the main mixing of air and fuel occurs in the interior 131b of the premix chamber 132 and in the premix space 131c. Sidewall 146 of premix chamber 132 includes an inner side 154 and an outer side 156. The lower portion 158 of the sidewall 146 is flared outwardly in the form of a cantilever to impart an annular Coanda surface 160 to the medial side 154 of the sidewall.

The premix chamber 132 has a ratio of length (or height) to inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. The exact ratio of the length (or height) of the premix chamber 132 to the inner hydraulic diameter will depend, in part, on the type of fuel to be burned and the pressure available for droplet entrainment and mixing. In general, long premix chambers can result in better mixing of fuel and air therein, but this advantage is balanced by cost and other considerations. In a preferred embodiment, the ratio of length (or height) to the inner hydraulic diameter of the premix chamber 132 is about 1.5: 1.

The auxiliary fuel inlet 134 is disposed at a predetermined position with respect to the premix region 131 to inject fuel from the auxiliary fuel inlet into the premix region into the premix space 131a and through the air inlet 148 to premix the chamber. Furnace air is entrained, thereby allowing a mixture of fuel and air, preferably a substantially homogeneous mixture, to form within the premix zone and to discharge to the air / fuel outlet 150 of the top 142 of the premix chamber. Fuel and air continue to mix in the premix space 131c. The mixture of fuel and air is typically not combusted until the mixture exits the air / fuel outlet 150, ie generally the distance away from the air / fuel outlet. The separation distance from the air / fuel outlet 150 where combustion occurs varies depending on the amount of air in the mixture and the speed of the mixture exiting the air / fuel outlet. In some cases, due to the timing sequence of the short removal step, combustion may occur in the premix region (eg, according to the scheme of very low pressure, for a short duration). As shown in FIGS. 10 and 12, the auxiliary fuel gas inlet 134 includes an annular distribution manifold 164 having one or more fuel ports 166 therein. The fuel port 166 is a substantially round hole. As shown in FIG. 10, the annular dispensing manifold 164 may be configured for the premax chamber 132 so that fuel can be injected into the annular Coanda surface 160 from the manifold 164. It is located at the position.

10A shows a variation of the annular distribution manifold 164. In this variant, the fuel port 166 is an elongated hole or slot. Slots formed in the fuel port 166 serve to improve the effect of mixing and mixing caused by the coanda surface and are annular as a sheet-like pattern that allows fuel to be injected from the manifold 164 at higher speeds. Has a shape that allows fuel to be injected onto the Coanda surface 160. Slot 166 may be connected to form a continuous elongated hole or slot in distribution manifold 164 as desired.

The annular fuel membrane 170 is disposed around the outer circumference of the premix chamber 132. The fuel membrane 170 is connected to the fuel feed 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 inner sidewall 177 and an outer sidewall 176 connecting the top to the bottom. In the embodiment shown in FIGS. 9-12, the inner sidewall 177 is also a sidewall 146 of the premix chamber. The annular seal 178 is fixed to the lower portion 174 of the fuel membrane 170 and extends around the sidewall 146 of the premix chamber 132 to ensure the integrity of the membrane. In a variant, as illustrated in FIGS. 25-28 and described below, fuel membrane 170 may be provided with a premix chamber to provide an annular space between the outer surface of sidewall 146 and main fuel outlet 136. 132 may be spaced outwardly from sidewall 146 of 132. The annular space allows air to be entrained from below the burner to a point adjacent to the fuel port 192 disposed inside the main fuel outlet 136. In this embodiment, the inner sidewall 177 of the fuel membrane 170 is distinct from the sidewall 146 of the premix chamber 132.

Auxiliary fuel feed conduits 180a, 180b, 180c, and 180d may be assisted from annular fuel membrane 170 to deliver fuel from fuel membrane 170 to auxiliary fuel inlet 134 (ie, manifold 164). Extends to fuel inlet 134 (ie, annular distribution manifold 164). Each auxiliary fuel feed conduit 180a, 180b, 180c, and 180d has a first end 182 secured to the fuel membrane 170 and a second end secured to the inlet 134 (ie, the manifold 164). 184.

The main fuel outlet 136 is at a predetermined position relative to the top 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. Is placed on. 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 generated by port 192 is a diffuse fuel jet. The annular fuel injector body 188 has an open top 172 of the annular membrane 170 such that the fuel port 192 is disposed around the perimeter 186 of the air / fuel outlet 150 of the premix chamber 132. Is stuck on. The inner and outer diameters of the annular membrane 170 and the annular fuel injector body 188 are approximately equal. Fuel may be injected annularly around main system 186 of air / fuel outlet 150 from main fuel outlet 136 (ie, annular fuel injector body 188). The port 192 may be sized and spaced to control how fuel is injected from the port (eg, direction and speed). This feature, associated with the flow of fuel and air through the air / fuel outlet 150, allows the shape and length of the entire flame envelope to be controlled.

As shown in FIG. 7, the diffusion fuel port 192 may be spaced from the fuel injector body 188 by a plurality of corresponding short gas risers or tip extensions 196 as needed. Using the riser 196 to space the port 192 from the fuel injector body 188 can result in better lateral droplet entrainment of air in some applications. The riser also allows the shape of the port and the resulting fuel flow characteristics to be changed mechanically as needed. A variant of the fuel injector body 70 shown in FIG. 8 can also 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 may include various repeating ports 192. The particular port shape used will depend on a variety of factors including the type of fuel to be burned (including molecular weight, calorific value, stoichiometry and temperature of the stream) and the pressure available in connection with it.

The fuel supply conduit 138 is in fluid communication with the auxiliary fuel inlet and the primary fuel outlet 136 to direct fuel to the auxiliary fuel inlet 134 and the primary fuel outlet. Fuel feed 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 source of fuel (this type of connection may be more typically made by welding). The second end 202 is connected to a corresponding inlet 206 at the outer sidewall 176 of the annular gas film 170. Alternatively, a separate fuel delivery conduit or riser may direct fuel to the secondary fuel inlet 134 and the main fuel outlet 136 (as opposed to a single unitary conduit or riser 138). A separate conduit or riser typically extends from the common fuel header.

An operation of the burner 130 will be described with reference to FIG. 10. The fuel to be burned (usually indicated by the black arrows) is guided through the fuel feed conduit 138 to the annular fuel membrane 170. A portion of the fuel is guided by the fuel membrane 170 to the main fuel outlet 136 (ie, the annular injector body 188). The remaining fuel is led by fuel membrane 170 through fuel feed conduits 180a, 180b, 180c and 180d to auxiliary fuel inlet 134 (ie, annular distribution manifold 164). Fuel is injected from the fuel port 166 of the annular distribution manifold 164 through the premix space 131a onto the annular Coanda surface 160 on the inner side 154 of the premix chamber 132. Injection of fuel from the gas port 166 into the premix zone 131 and the premix chamber 132 causes air to splash into the premix space 131a and through the air inlet 148 into the interior 131b of the premix chamber. This allows a mixture of fuel and air (preferably a substantially homogeneous mixture) to form in the premix zone and exit the air / fuel outlet 150. Fuel and air continue to mix over a short distance over the air / fuel outlet 150. Injecting fuel from the fuel port 166 onto the coanda surface 160 causes the fuel to follow and follow the path of the coanda surface, forming a relatively thin film to entrain the droplets of air and fuel and air more efficiently. Results in mixing. The fuel to be burned is from the main fuel outlet 136 (annular injector body 188) around the main system 186 of the air / fuel outlet 150 of the premix chamber 132 and further the air / fuel outlet of the premix chamber. It is sprayed around the air / fuel mixture exiting 150. The flare burner 130 is such that the amount of air entrained into the premix region 131 including the premix chamber 132 exceeds the stoichiometric amount of air required to combust the fuel injected into the premix region. It is preferred to be designed and operated in a manner. Excess air is supplied to the center of the flame envelope such that fuel is combusted inside the flame envelope. However, as described below, in some applications, the burner is stoichiometric of the air where the amount of air entrained into the premix region 131 including the premix chamber 132 is required to burn fuel injected into the premix region. It is designed and operated in such a way that it is below the positive amount. Injecting a mixture of "fuel-rich" fuel and air (i.e., a mixture having less than the stoichiometric amount of air required to support combustion of fuel injected into the premix zone) to the central portion of the flame envelope Preferred in the application.

The flare burner 130 has the same advantages as those obtained from the flare burner 30 described above. The flame envelope 100, shown roughly in FIG. 24, is also produced by the flare burner 130.

13 to 18, a third embodiment of the flare burner of the present invention is indicated in parallel with reference numeral 230. Like other embodiments of the flare burner of the present invention, the flare burner 230 includes a premix region 231 including a premix chamber 232, an auxiliary fuel inlet 234 for injecting fuel into the premix region, Main fuel outlet 236 and fuel feed conduit 238. The pilot (as shown in FIG. 4) may be combined with burner 230 to initially ignite the mixture of fuel and air released by the burner.

In the embodiment shown in FIGS. 13-18, the premix chamber 232 of the flare burner 230 occupies a significant portion of the premix region 231. A mixture of fuel and air (preferably a substantially homogeneous mixture) may be formed in premix region 231 including premix chamber 232. As described below, the mixture formed in the premix region 231 may be a rich or lean mixture of fuel. The premix chamber 232 is rectangular in cross section and has a rectangular shape. The premix chamber includes an upper portion 242, a lower portion 244, a sidewall 246 connecting the upper portion to the lower portion, an air inlet 248 disposed on the lower portion 244, and an air / fuel outlet 250 disposed on the upper portion. do. As shown, top 242 and bottom 244 are open to form air inlet 248 and air / fuel outlet 250. As a result, each of the air inlet 248 and the air / fuel outlet 250 also has a rectangular cross section.

As best shown in FIG. 14, the premix region 231 is defined by a premix space 231a (below the auxiliary fuel inlet 234 and the bottom 244 and below the premix chamber 232) of the auxiliary fuel inlet and the premix chamber. Between the air inlet 248, the interior 231b of the premix chamber, and the top 242 of the premix chamber and the premix space 231c directly above the air / fuel outlet 250. In the embodiment shown in FIGS. 13-18, the main mixing of air and fuel occurs in the interior 231b of the premix chamber 232 and in the premix space 231c.

Sidewall 246 of premix chamber 232 includes four sides 246a, 246b, 246c and 246d. Respective sides 246a, 246b, 246c, and 246d include an inner side 254 and an outer side 256. The lower portion 258 of each side 246a, 246b, 246c and 246d is flared outwardly in a cantilevered shape to impart an annular Coanda surface 260 to the medial side 254 of the side. The premix chamber 232 has a ratio of length (or height) to inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. The exact ratio of the length (or height) of the premix chamber 232 to the inner hydraulic diameter will depend, in part, on the type of fuel to be burned and the pressure available for droplet entrainment and mixing. In general, long premix chambers can result in better mixing of fuel and air therein, but this advantage is balanced by cost and other considerations. In a preferred embodiment, the ratio of the length (or height) of the premix chamber 232 to the inner hydraulic diameter is about 1.5: 1.

Since the auxiliary fuel inlet 234 is disposed at a predetermined position with respect to the premix region 231, when the fuel is injected from the auxiliary fuel inlet to the premix region, the premix chamber is connected to the premix space 231a and through the air inlet 248. Air is entrained to 232 such that a mixture of fuel and air, preferably a substantially homogeneous mixture, is formed in the premix zone and exits the air / fuel outlet 250 of the top 242 of the premix chamber. Do it. The mixture of fuel and air is typically not combusted until the mixture exits the air / fuel outlet 250, ie, generally beyond the separation distance from the air / fuel outlet. The separation distance from the air / fuel outlet 250, where combustion occurs, varies depending on the amount of air in the mixture and the speed of the mixture exiting the air / fuel outlet. In some cases, due to the timing sequence of the short removal step, combustion may occur in the premix region (eg, according to the scheme of very low pressure, for a short duration).

As shown in FIG. 18, the auxiliary fuel inlet 234 includes two tubular distribution manifolds 264a and 264b with a plurality of fuel ports 266 inside each. The fuel port 266 is a substantially round hole. Dispensing manifold 264a is positioned at a location relative to the premax chamber 232 such that fuel can be injected from the manifold 264a onto the coanda surface 260 on the inner side 254 of the side 246a. It is arranged. Similarly, dispensing manifold 264b is directed to premix chamber 232 such that fuel can be injected from manifold 264b onto coanda surface 260 on inner side 254 of opposing side 246c. It is arrange | positioned at a predetermined position. As will be appreciated by those skilled in the art, various shapes of fuel ports and jets may be used in this embodiment to inject fuel onto the Coanda surface. The number and spacing of the fuel ports may vary, for example, depending on the required thickness of the film to be produced on the Coanda surface.

A variation of each of the tubular distribution manifolds 264a and 264b is shown in FIG. 17A. In this variant, the fuel port 266 is an elongated hole or slot. Slots formed in the fuel port 266 serve to enhance the entrainment and mixing effect generated by the coanda surface, and the annular coanda surface 260 as a sheet-like pattern that allows a larger volume of gas to burn. It is a shape that allows fuel to be injected onto the tank. Slots 266 may be connected to form elongated holes or slots in the distribution manifolds 264a and 264b as needed. In addition to the round holes and slots, the fuel port 266 may be formed in other shapes depending on the particular application. Examples of other shapes include elongated ellipses and rectangular slots.

The rectangular fuel membrane 270 is disposed around the outer periphery of the premix chamber 232. The fuel membrane 270 is connected to the fuel feed conduit 238 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 inner sidewall 277 and an outer sidewall 276 connecting the top to the bottom. In the embodiment shown in FIGS. 13-18, the inner sidewall 277 is also a sidewall 246 of the premix chamber. The corresponding seal mechanism 278 is secured to the bottom 274 of the fuel membrane 270 and extends around the sidewall 246 of the premix chamber 232 to ensure the integrity of the membrane. In a variant, as illustrated in FIGS. 25-28 and described below, the fuel membrane 270 may be provided with a premix chamber to provide an annular space between the outer surface of the sidewall 246 and the main fuel outlet 236. 232 may be spaced outwardly from the outer surface 256 of the sides 246a, 246b, 246c, and 246d of the sidewall 246. The annular space allows air to be entrained from below the burner to a point adjacent to the fuel port 292 disposed inside the main fuel outlet 236. In this embodiment, the inner sidewall 277 of the fuel membrane 270 is distinct from the sidewall 246 of the premix chamber 232.

Auxiliary fuel feed conduits 280a, 280b, 280c, and 280d provide auxiliary fuel inlet 234, ie tubular distribution manifolds 264a and 264b, from fuel membrane 270 to carry fuel from the fuel membrane to the auxiliary fuel inlet. Extends. Each auxiliary fuel feed conduit 280a, 280b, 280c, and 280d includes a first end 282 and a second end 284 secured to the fuel membrane 270. The second ends 284 of the conduits 280a and 280d are secured to opposite ends of the tubular distribution manifold 264a. Second ends 284 of conduits 280b and 280c are secured to opposite ends of the tubular distribution manifold 264b.

The main fuel outlet 236 is in a predetermined position relative to the top 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. Is placed on. As best shown in FIG. 15, the main fuel outlet 236 includes a flat, rectangular fuel injector body 288 with a plurality of diffusion fuel ports 292 therein. The fuel jet generated by port 292 is a diffusion fuel jet. The fuel injector body 288 adheres to the open top 272 of the fuel membrane 270 so that the diffusion fuel port 292 is disposed around the perimeter 286 of the air / fuel outlet 250 of the premix chamber 232. do. The inner and outer diameters of the membrane 270 and the fuel injector body 288 are approximately equal. Fuel may be injected from the main fuel outlet 236 (ie, fuel injector body 288) around the perimeter 286 of the air / fuel outlet 250. The port 292 may be sized and spaced to control how fuel is injected from the port (eg, direction and speed). This feature, associated with the flow of fuel and air through the air / fuel outlet 250, allows control of the shape and length of the entire flame envelope.

As shown in 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 desired. Using the riser 296 to space the port 292 from the fuel injector body 288 may result in better lateral droplet entrainment of air in some applications. The riser also allows the shape of the port and the resulting fuel flow characteristics to be changed mechanically as needed. As will be appreciated by those skilled in the art, the injector body 288 can include variously repeated ports 292. The particular port shape used depends on a variety of factors including the type of fuel to be burned (including molecular weight, calorific value, stoichiometry and temperature of the stream) and the pressure available in connection with it.

The fuel supply conduit 238 is in fluid communication with the secondary fuel inlet 234 and the primary fuel outlet 236 to direct fuel gas to the primary fuel outlet. Fuel feed 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 source of fuel (also, this type of connection is more generally made by welding). The second end 302 is connected to the corresponding inlet 306 at the outer sidewall 276 of the annular fuel membrane 270. Alternatively, a separate fuel feed conduit or riser may direct fuel to the auxiliary fuel inlet 234 and the main fuel outlet 236 (as opposed to a single unitary conduit or riser 238). A separate conduit or riser typically extends from the common fuel header.

Referring to FIG. 14, in operation of burner 230, fuel to be burned (usually indicated by a black arrow) is guided to fuel membrane 270 through fuel feed conduit 238. A portion of the fuel is guided by the fuel membrane 270 to the main fuel outlet 236 (and the annular injector body 288). The remaining fuel is guided by fuel membrane 270 through fuel feed conduits 280a, 280b, 280c and 280d to auxiliary fuel inlet 234 (and tubular distribution manifolds 264a and 264b). Fuel is injected from the fuel ports 266 of the distribution manifolds 264a and 264b onto the coanda surface 260 on the inner side 254 of the sides 246a and 246b of the premix chamber 232. When fuel is injected from the fuel port 266 into the premix region 231 and the premix chamber 232, air is splashed into the premix space 231a and through the air inlet 248 into the interior 231b of the premix chamber. Thus, a mixture of fuel and air (preferably substantially homogeneous mixture) is formed in the premix zone and exits the air / fuel outlet 250. Fuel and air continue to mix over a short distance over the air / fuel outlet 250. Injecting fuel from the fuel port 266 onto the coanda surface 260 on the medial side 254 of the sides 246a and 246b causes the fuel to maintain and follow the path of the coanda surface, resulting in a relatively thin membrane. Formed as a result of more efficient air droplet entrainment and mixing of fuel and air. The fuel to be burned is from the main fuel outlet 236 (and the tubular fuel injector body 288) around the perimeter 286 of the air / fuel outlet 250 of the premix chamber 232 and further the air / It is injected around the air / fuel mixture exiting the fuel outlet 250. The flare burner 230 is designed so that the amount of air entrained into the premix region 231 including the premix chamber 232 exceeds the stoichiometric amount of air required to combust the fuel injected into the premix region. It is desirable to work. Excess air is supplied to the center of the flame envelope so that fuel is burned inside the flame envelope. However, in some applications, as will be described below, burner 230 may include a portion of the air required to burn fuel injected into the premix region with the amount of air entrained into the premix region 231 including premix chamber 232. It is designed and operated in such a way that it is below the stoichiometric amount. Injecting a mixture of "fuel-rich" fuel and air (i.e., a mixture with less than the stoichiometric amount of air required to support combustion of fuel injected into the premix zone) into the central portion of the flame envelope is some application. Preferred at

Flare burner 230 has the same advantages as those obtained from flare burners 30 and 130. The flame envelope 100, shown roughly in FIG. 24, is also produced by the flare burner 230.

The polygonal shape of the flare burner 230 (rectangle in the illustrated embodiment) may allow greater flexibility in forming gaps in the flare burner in ground flare applications. This shape can also allow greater flexibility in how fuel is oriented from the diffusion gas port 292 due to the fact that the geometry can rotate to change the interaction area.

19 to 23, a fourth embodiment of the flare burner of the present invention is indicated in parallel with reference numeral 330. Like other embodiments of the flare burner of the present invention, the flare burner 330 includes a premix region 331 including a premix chamber 332, an auxiliary fuel inlet 334 for injecting fuel into the premix region, and a main A fuel outlet 336 and a fuel supply conduit 338. Pilot 40 (as shown in FIG. 4) may be coupled to burner 330 to initially ignite the mixture of fuel and air discharged by the burner.

A mixture of fuel and air (preferably a substantially homogeneous mixture) may be formed in the premix region 331 including the premix chamber 332. As described below, the mixture formed in the premix region 331 may be a rich fuel or a lean fuel mixture. The premix chamber 332 has a round cross section and a cylindrical shape. The premix chamber comprises a top 342, a bottom 344, sidewalls 346 connecting the top to the bottom, an air inlet 348 disposed at the bottom 344 and an air / fuel outlet disposed at the top 342. 350). Sidewall 346 includes an inner side 347 and an outer side 349. As shown, top 342 and bottom 344 are open to form air inlet 348 and air / fuel outlet 350. As a result, each of the air inlet 348 and the air / fuel outlet 350 also has a rounded cross section. The premix chamber 332 has a ratio of length (or height) to inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1.

In the embodiments shown in FIGS. 19, 20, 22 and 23 (without the extension cylinder 400 described below), the ratio of the length (or height) of the premix chamber 332 to the inner hydraulic diameter is about. 1: 1 or less. Preferably, the length (or height) of the premix chamber 332 versus the inner hydraulic diameter in the embodiments shown in FIGS. 19, 20, 22 and 23 (without the extension cylinder 400 described below). Ratios range from about 0.25: 1 to about 1: 1. As mentioned above, long premix chambers generally allow for better mixing of fuel and air in the premix chamber. However, in the embodiment shown in FIGS. 19 and 20 it has been found that the length (or height) of the premix chamber 332 is still sufficient for good mixing as long as the ignition delay is maintained by adjusting the flame propagation rate. As best shown in FIG. 20, the premix region 331 in certain embodiments (not including the extension cylinder 400 described below) may have a significant amount of premix space 331a (secondary fuel inlet) under the premix chamber 332. Between 334 and bottom 344 and between the auxiliary fuel inlet and the air inlet 348 of the premix chamber, the interior 331b of the premix chamber, and the top 342 of the premix chamber and the air / fuel outlet ( 350, a premix space 331c directly above it. In this embodiment, the mixing of air and fuel occurs in all three portions of premix area 331.

The auxiliary fuel inlet 334 is disposed at a predetermined position with respect to the premix region 331, and when fuel is injected from the auxiliary fuel inlet to the premix region, it passes through the air inlet 348 to the premix space 331a and the premix chamber. Air is entrained to 332, whereby a mixture of fuel gas and air, preferably a substantially homogeneous mixture, is formed in the premix zone and exits the air / fuel outlet 350 of the top 342 of the premix chamber. To help. The mixture of fuel and air is typically not combusted until the mixture exits the air / fuel outlet 350 and generally beyond the separation distance from the air / fuel outlet. The separation distance from the air / fuel outlet 350, where combustion occurs, varies depending on the amount of air in the mixture and the speed of the mixture exiting the air / fuel outlet. In some cases, due to the timing sequence of the short removal step, combustion may occur in the premix region (eg, according to the scheme of very low pressure, for a short duration).

As shown in FIGS. 19 and 22, the auxiliary fuel inlet 334 is arranged concentrically around the bull nose 353 and the bull nose and centered below the air inlet 348 of the premix chamber 332. Burner casting 352 having a plurality of fuel outlet arms 354. The auxiliary fuel inlet 334 is concentric with the air inlet 348 and the premix chamber 332. In the embodiment shown in 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 may be in the range of 0 to 2 inches below the air inlet 348, and may preferably be about 1 inch below the air inlet. The exact distance may vary depending on the type of fuel to be burned in certain applications, the length of the flame envelope allowed and other factors.

Each fuel outlet arm 354 and fire nose 353 include a plurality of fuel ports 356. These ports 356 are arranged in a straight line along the longitudinal axis of each fuel outlet arm 354. 23 shows a variant of the auxiliary fuel inlet 334. In this variant, each gas outlet arm 354 includes two rows of diffusion fuel ports 356, each port of each row being aligned so as not to directly intersect the ports of adjacent rows. The auxiliary fuel inlet 334 including the fuel outlet arm 354 is intentionally small to allow as much interaction as possible between the discharged fuel and the droplet entrained air. The "bluff body" effect created by the size and shape of the auxiliary fuel inlet 334 is minimized to create a full access state of air to the released fuel.

The annular fuel membrane 360 is disposed around the outer circumference of the premix chamber 332. The fuel membrane 360 is connected to the fuel feed conduit 338 in fluid communication with the main fuel outlet 336. The fuel membrane 360 includes an open top 362, a bottom 364 and an inner sidewall 367 and an outer sidewall 366 connecting the top to the bottom. In a preferred embodiment, the outer sidewall 366 is about 3 inches away from the inner sidewall 367 (this distance depends on the nature of the fuel and the overall shape of the burner). In the embodiment shown in FIGS. 19, 20, 22, and 23, the inner sidewall 367 of the fuel membrane 360 is also the outer surface 349 of the sidewall 346 of the premix chamber 332. According to a variant illustrated in FIGS. 25-28 and described below, fuel membrane 360 provides premix chamber 332 to provide an annular space between outer surface 349 of sidewall 346 and main fuel outlet 336. ) May be spaced outwardly from the outer side surface 349 of the sidewall 346. The annular space allows air to be entrained from below the burner to a point adjacent to the fuel port 374 disposed on the inner side of the main fuel outlet 336. In this embodiment, the inner sidewall 367 of the fuel membrane 360 is distinct from the sidewall 346 of the premix chamber 332.

The main fuel outlet 336 is connected to the top 342 of the premix chamber 232 such that fuel can be injected from the main fuel outlet 336 around the perimeter 368 of the air / fuel outlet 350 of the premix chamber. It is arrange | positioned at a predetermined position. 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 372 therein. The fuel jet generated by port 374 is a diffusion fuel jet. The spacing may depend on the particular application, but the ports 374 are preferably spaced apart by 6 degrees. The annular fuel injector body 370 is secured to the open top 362 of the annular membrane 360 such that the fuel port 374 is disposed around the perimeter 368 of the air / fuel outlet 350 of the premix chamber. . The inner and outer diameters of the annular membrane 360 and the fuel injector body 370 are approximately equal. Fuel may be annularly injected from the main fuel outlet 336 (ie, fuel injector body 370) around the perimeter 368 of the air / fuel outlet 350. The port 374 can be sized and spaced to control how fuel is injected (eg, direction and speed) from the port. This feature, associated with the flow of fuel and air through the air / fuel outlet 350, allows the shape and length of the entire flame envelope to be controlled.

As shown in FIG. 7, the diffusion fuel port 374 may be spaced from the fuel injector body 370 by a plurality of corresponding short gas risers or tip extensions 376 as desired. Using the riser 376 to space the port 374 from the fuel injector body 370 may result in better lateral droplet entrainment of air in some applications. The riser also allows the shape of the port and the resulting fuel flow characteristics to be changed mechanically as needed. As will be appreciated by those skilled in the art, the fuel injector body 370 may include various repeated ports 374. The particular port shape used will depend on a variety of factors including the type of fuel to be burned (including molecular weight, calorific value, stoichiometry and temperature of the stream) and the pressure available in connection with it.

The fuel supply conduit 338 is in fluid communication with the auxiliary fuel inlet and the primary fuel outlet 336 to direct fuel to the auxiliary fuel inlet 334 and the primary fuel outlet. The fuel feed 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 a source of fuel (also, this type of connection is more generally made by welding). The second end 384 is connected to a corresponding inlet 388 at the outer sidewall 366 of the fuel membrane 360. The fuel supply conduit 338 also includes an auxiliary branch 390 that connects the fuel supply conduit to the auxiliary fuel inlet 334. This auxiliary branch portion 390 includes a first end 392 and a second end 394. The first end 392 is connected to the main branch 380 of the fuel feed conduit 338. The second end 394 is connected to an auxiliary fuel inlet 334 (specifically casting 352). Alternatively, a separate fuel delivery conduit or riser may direct fuel to the auxiliary fuel inlet 334 and the main fuel outlet 336 (as opposed to a single unitary conduit or riser 338). A separate conduit or riser typically extends from the common fuel header.

Referring to FIG. 21, a modification of the flare burner 330 is illustrated. This embodiment is also the same as the embodiment of burner 330 described above except that it includes a premix chamber extension cylinder 400. The premix chamber extension cylinder 400 extends along the length of the premix chamber 332. In this embodiment, the premix chamber has a ratio of length (or height) to inner hydraulic diameter in the range of about 1: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. Most preferably, in this embodiment, the premix chamber has a ratio of length (or height) to inner hydraulic diameter in the range of about 1.5: 1. The cylinder 400 includes an upper portion 402, a lower portion 404, and an intermediate portion 406 that connects the upper and lower portions to each other. The intermediate portion 406 is secured to the inner sidewall 367 of the annular fuel membrane 360.

Due to the premix chamber extension cylinder 400, the top 342 and air / fuel outlet 350 of the premix chamber 332 are spaced above the main fuel outlet 336. Top 342 and air / fuel outlet 350 of premix chamber 332 range from about 0.5 inches to about 10 inches above main fuel outlet 336, preferably from about 6 inches to about 8 inches. The exact spacing may vary depending on the type of fuel to be burned, the particular application, the length of the flame envelope allowed and other factors. The lower portion 344 of the premix chamber 332 is located approximately the same height as the auxiliary fuel inlet 334 or about one inch higher. As shown in FIG. 21, the premix region 331 in certain embodiments (including the extension cylinder 400) may have a premix space 331a (auxiliary fuel inlet 334 and bottom) under the premix chamber 332. Between 344 and between the auxiliary fuel inlet and the air inlet 348 of the premix chamber, the interior 331b of the premix chamber, and just above the top 342 and the air / fuel outlet 350 of the premix chamber. Premix space 331c is included. In this embodiment, the main mixing of air and fuel occurs in the premix chamber 332 (premix region 331b).

The upper portion 402 of the premix chamber extension cylinder 400 serves as a wind shield as well as a physical barrier to delay ignition. Specifically, the upper portion 402 counteracts the effects of harmful cross-flow air, which can force flames inside the diameter of the premix chamber and interfere with the smokeless capacity of the flare burner. The upper portion 402 also serves to isolate the premix fuel stream from diffuse flame ignition. Similarly, the lower portion 404 of the cylinder 400 acts as a lower wind shield, helping to prevent the flame from returning and ignite prematurely. Again, the length of the premix chamber 332 increased by the extension cylinder 400 improves the mixing of fuel and air in the premix chamber. Extension cylinders are not necessary in all applications, such as may not be necessary when cross flow effects are not an issue or when low molecular weight fuels are burned. The inclusion or absence of the shield will depend on the molecular weight and calorific value of the fuel to be burned, whether the fuel contains saturated or unsaturated hydrocarbons, the temperature and pressure involved and other factors.

In the embodiment shown in FIG. 21, the inner sidewall 367 of the membrane 360 is secured to the middle portion 406 of the extending cylinder 400. In a variant, as illustrated in FIGS. 25-28 and described below, fuel membrane 360 extends cylinder 400 [to provide an annular space between the outer surface of the extension cylinder and main fuel outlet 336. Furthermore, it may be spaced outward from the outer surface of the premix chamber 332. The space allows air to be entrained from below the burner to a point adjacent to the fuel port 374 disposed on the inner side of the main fuel outlet 336.

An operation of the flare burner 330 will be described with reference to FIGS. 20 and 21. The portion of the fuel to be burned (usually indicated by the black arrow) is guided through the main branch 380 of the fuel feed conduit 338 to the fuel membrane 360 and the main fuel outlet 336. The portion of fuel to be burned is also guided from the auxiliary branch to the auxiliary fuel inlet 334 through the auxiliary branch 390 of the fuel feed conduit 338. Injection of fuel from the auxiliary fuel inlet 334 into the premix region 331 and the premix chamber 332 causes air to be splashed into the premix space 331a and through the air inlet 348 into the premix chamber, thus fuel And a mixture of air (preferably substantially homogeneous) is formed in the premix zone and allows it to exit the air / fuel outlet 350. Fuel and air continue to mix over a short distance over the air / fuel outlet 350. The remaining fuel to be burned is injected from the main fuel outlet 336 around the perimeter 368 of the air / fuel outlet 350 of the premix chamber and further around the air / fuel mixture exiting the air / fuel outlet of the premix chamber. . Again, when the extension cylinder 400 is installed, premix streams are obtained and the premix stream exiting the air / fuel outlet 350 interacts with the diffusion flames formed as soon as fuel is discharged from the main fuel outlet 336. It is isolated from ignition. The use of extension cylinder 400 serves to enhance the overall effect created by the use of the premix stream. The flare burner 330 is such that the amount of air entrained into the premix region 331 including the premix chamber 332 exceeds the stoichiometric amount of air required to combust the fuel injected into the premix region. It is desirable to design and operate. Excess air is supplied to the center of the flame envelope so that fuel is burned inside the flame envelope. However, as will be discussed below, in some applications, burner 330 is the air required to burn fuel injected into the premix region with the amount of air entrained into premix region 331 including premix chamber 332. It is designed and operated in such a way that it is below the stoichiometric amount of. Injecting a mixture of “fuel-rich” fuel and air (ie, a mixture with less than the stoichiometric amount of air required to support combustion of fuel injected into the premix zone) into the central portion of the flame envelope is some application. May be preferred.

The flare burner 330 has the same advantages as those obtained from the flare burners 30, 130, and 230 described above. The flame envelope 100, generally indicated in FIG. 24, is also produced by the flare burner 330.

25 to 28, there is shown a modification that can be made to the fourth embodiment of the flared burner of the present invention (the embodiment shown in Figs. 19 to 23) described above. The same modification can be applied to the above-described first, second and third embodiments of the flare burners of the present invention.

In this embodiment, the flare burner 330 includes a premix chamber extension cylinder 400. However, instead of sticking directly to the fuel membrane 360, the extension cylinder 400 (and further the premix chamber 332) provides an air passage between the extension cylinder and the fuel membrane so that air is disposed inside the main fuel outlet 336. It is spaced inward from the fuel membrane to efficiently reach the fuel port 374. The diameter of the extension cylinder 400 (and further the premix chamber 332) is significantly smaller than the inner diameter of the fuel membrane 360. In this embodiment, the premix chamber has a ratio of length (or height) to inner hydraulic diameter in the range of about 0.5: 1 to about 4: 1, preferably about 1: 1 to about 3: 1. Most preferably, the premix chamber has a ratio of length (or height) to inner hydraulic diameter in the range of about 1.5: 1.

Due to the small diameter of the extension cylinder 400, the inner sidewall 367 of the fuel membrane 360 and the outer surface of the extension cylinder 400 (this surface is also the outer surface of the sidewall 346 of the premix chamber 332). 349) is an annular space 430. A plurality of thin rectangular gusset plates 432 are used to center the extension cylinder 400 (and further the premix chamber 332) inside the fuel membrane 360. As shown, the four plates 432 are arranged to be spaced 90 degrees within the annular space 430. One end of each plate 432 is fixed to the inner sidewall 367 of the fuel membrane 360. The other end of each plate 432 is fixed to the outer side of the extension cylinder 400, which is also the outer side 349 of the sidewall 346 of the premix chamber 332. In addition to the above modifications, the burner 330 shown in FIGS. 25 to 28 is the same as the above-described embodiment shown in FIGS. 19 to 23 in all respects.

The main fuel outlet 336 is in a predetermined position 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 air / fuel outlet 350 of the premix chamber. It is still deployed. The annular space 430 merely provides an air passage between the extension cylinder and the fuel membrane to allow fresh oxidant to effectively reach the fuel port 374 disposed inside the main fuel outlet 336. The operation of burner 330 remains the same except that fresh air is entrained from below the burner by the kinetic force of the inner heat of fuel port 374 through annular space 430. The splash entrained air is brought into close proximity with the fuel to be released by the heat inside the fuel port 374 on the main fuel outlet 336 and mixed with the fuel. For example, the improved mixing method provided by the annular space 430 is useful when burning relatively heavy and unsaturated fuel feeds that tend to smoke more easily. It allows the burner to be optimal for soot-free combustion.

As will be appreciated by those skilled in the art, the same modifications may also be made to the other three embodiments of the flare burners of the present invention described above. For example, in a variation of the embodiment shown in FIGS. 4-8, the cross sectional diameter of the premix chamber 32 is reduced and the premix chamber 32 is spaced inwardly from the fuel membrane 60. Either the inner sidewall 67 of the annular fuel membrane 60 or the sidewall 46 of the premix chamber 32 is added (as shown, the inner sidewall of the membrane and the sidewall of the premix chamber are the same). The annular seal 68 is omitted. Spacing the premix chamber 32 inward from the fuel membrane 60 provides air space between the premix chamber and the fuel membrane. Fresh air can then be entrained from below the burner to a point very close to the fuel exiting the fuel port 74 inside the main fuel outlet 36. The premix chamber 32 may be attached to the fuel membrane centered inside the fuel membrane 60 using a plurality of gussets as shown in FIGS. 25-28.

FIG. 28 shows the flame envelope 100 produced by the modified flare burner 330 shown in FIGS. 25-27, including burners 130, 230, and 330 when deformed in the same manner. As shown, excess air is injected from the premix chamber 332 to the central portion 102 of the flame envelope 100. Excess air, indicated by air pocket 103 in FIG. 28, mixes with fuel in the central portion 102 of flame envelope 100 to effectively form two initial flammable regions, that is, regions 104a and 104b. The air is also entrained through the annular space 430 from below the burner 330 to a point very close to the fuel exiting from the inner heat of the fuel port 374 of the main fuel outlet 336. The air entrained through the annular space 430 improves mixing and produces faster and more uniform combustion within the overall flame envelope 100. As shown in FIG. 28, the flame envelope 100 has a length 106 that is substantially smaller than the length 23 of the conventional flame envelope 20 shown in FIG. 3 for the same amount of fuel.

General information

The partial pre-mix approach of the present invention allows two flame zones to be initialized within the same flame envelope as the fuel burns. The outer flame zone is a typical zone generally observed in burners of the type used so far, ie only using diffusion mixing. The outer layer of gas is finely divided to expose the continuous gas layer in repeated diffusion and subsequent combustion. The second flame zone is created by the premix zone of the burner carrying the combustible mixture inside the main flame envelope. This combustion flow field serves to create significant turbulent regions in the atypical flame core in normal diffusion flames. The thinner the fuel in the premix zone, the shorter the flame will be due to the additional oxidant carried to the flame core. Excess air is used by the rest of the flame cloud and also serves as a cooling mechanism to reduce emissions such as nitrogen dioxide and carbon monoxide, shortening the flame (or allowing mass flow to increase). Excess air also reduces the formation of soot and allows all unburned hydrocarbons to burn.

Each flare burner 30, 130, 230, and 330 is entrained in the premix zone so that the amount of air injected into the central portion of the flame envelope is required to support combustion of fuel injected into the premix zone. It is preferably designed and operated to fall in the range of about 15% to about 300% of the theoretical amount. Thus, a fuel rich approach (method of injecting a mixture of fuel and air into the central portion of the flame envelope, less than about 100% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone) and the fuel lean approach Both methods can be used (a method of injecting a mixture of fuel and air in excess of about 100% of the stoichiometric amount of air required to support the combustion of fuel injected into the premix region into the central portion of the flame envelope). Each approach has inherent advantages over conventional diffusion jet / free jet driven combustion methods used to date. The particular approach used will depend on the particular application, including the type of fuel to be burned and the pressure available. This approach can be modified by conventional porting and fuel delivery mechanisms.

When using a fuel rich approach, some of the fuel injected into the center of the flame envelope will initiate a small flame envelope that burns at the core of the flame, which shortens the flame while also creating additional turbulent combustion zones in the center of the flame envelope. Play a role. When using a fuel lean approach, the flame envelope will be considerably shorter as more premixed fuel burns in the flame core. The excess air carried by the premix flow method then serves to further initiate combustion for the center of the remaining flame envelope. The additional turbulence generated by the fuel expanding at the center of the flame during combustion then increases the mix of the remaining fuel by subdividing the rich fuel core and pushing it to the outer flame boundary.

When using a fuel rich approach, it is important to ensure that the premix stream carried to the center of the flame envelope remains within the combustible range. Otherwise mixing and combustion may not be increased at the flame envelope center. Improved mixing will benefit from premix flames that initiate at the core of the flame and expand at a significant rate to form significant turbulence in the core of the flame.

However, in most applications, more than about 100% of the stoichiometric amount of air required to support combustion of a “lean” mixture of fuel and air (ie, fuel injected into the premix zone) into the central portion of the flame envelope. It is preferable to spray the mixture). In most applications, the amount of air entrained in the premix zone and injected into the central portion of the flame envelope is about 125% to about 300% of the stoichiometric amount of air required to support combustion of fuel injected into the premix area. Belongs to the range. Preferably, the amount of air entrained into the premix region is from about 150% to about 300%, more preferably from about 175% to about 300% of the stoichiometric amount of air required to support combustion of fuel injected into the premix region. It belongs to the range of 300%. As the amount of excess air entrained into the premix zone increases (i.e., the amount of air entrained into the premix zone exceeds the stoichiometric amount of air required to support combustion of fuel injected into the premix zone). As increases), the benefits associated with flame length and emissions also increase. Although an amount of air in excess of 300% of the stoichiometric amount of air required to support the combustion of fuel injected into the premix zone is advantageously entrained in the premix zone, External sources or other possible modifications are required, which leads to enormous cost increases.

The amount of air entrained into the premix area of each burner 30, 130, 230 and 330 includes the pressure and mass flow of fuel injected from the auxiliary fuel inlet, the type of fuel to be burned and the number and size of internal ports. It depends greatly on the configuration of the auxiliary fuel inlet, the replacement of the auxiliary fuel inlet to the premix chamber for the air inlet and the size of the air inlet. For most applications, the ultimate goal is to obtain a mixture of fuel and air that is very lean and preferably flammable. Flammable and lean mixtures will quickly receive the fuel needed to become flammable again in the core of the flame envelope. Obtaining a flammable mixture, the air and gas will then create a large flame zone on the inside of the flame envelope, which speeds up the fuel's oxidation while also creating significant turbulence to increase diffusion mixing on the outer surface of the flame zone. Will increase significantly. The additional mass delivered to the center of the flame envelope also serves as a cooling mechanism to reduce the production of emissions such as nitrogen dioxide and carbon monoxide. The increased rate at which combustion occurs while maintaining the two flame fronts also serves to reduce the production of carbon monoxide and soot, and to reduce emissions of unburned hydrocarbons.

The fuel has enough momentum to radially entrain air and is injected from below the burner into the jet (s) and premix area of the fuel. Depending on the molecular weight of the fuel and the transport pressure available for splash entrainment, the burner can entrain air from within 2 feet below the auxiliary fuel inlet.

Preferably, the amount of fuel injected into the premix area of each burner 30, 130, 230 and 330 ranges from about 5% to about 50%, more preferably of the total amount of fuel to be burned by the flare burner. About 10% to about 30%. Most preferably, the amount of fuel injected into the premix chamber ranges from about 10% to about 25% of the total amount of fuel to be burned by the flare burner. By adjusting the diameter of the fuel port and the pressure of the fuel, it is possible to control the amount of fuel injected into the premix region.

The larger the proportion of fuel injected into the premix zone, the shorter the flame and the higher the lead-free capability of the burner. However, a proper balance must be made between the proportion of fuel injected into the premix zone and the amount of air that can be splashed into the premix zone. When a fuel lean approach is used, it is generally important to ensure that the amount of air entrained into the premix region is at least about 125% of the stoichiometric amount of air required to support combustion of fuel injected into the premix region. Lower amounts of air can produce a very reactive (combustible) mixture that can make the burner burn-back or flashback at full speed. The greater the amount of entrained air, the higher the cooling effect and the lower the flame speed of the fuel. This condition is ideal for increasing the ignition delay of the premix stream to ensure that the ignition point of the premix stream is local to the core of the flame prior to combustion for maximum gain.

A sufficiently thin stream of air and fuel will ensure that the mixture does not ignite until the mixture of air and fuel exits the air / fuel outlet and reaches the center of the flame envelope. When a mixture of fuel and air exits the air / fuel outlet and enters the flame envelope, the mixture then receives sufficient additional fuel to be a combustible mixture when the fuel is ignited within the main flame envelope. This flow creates flame within the geometry of the flame or toric flame that burns in front of the two individual flames. The additional turbulence generated by the gas expanding at the center of the flame during combustion then serves to increase the mode of mixing for the remaining fuel by subdividing the rich fuel core and pushing it to the outer flame boundary. This approach reduces the height of the flame and the ability to produce smoke, while also increasing the overall combustion efficiency due to the increased mixing.

For each burner 30, 130, 230 and 330 it is important that the air / fuel mixture in the premix zone does not burn until it exits the air / fuel outlet of the premix zone. Combustion in the premix chamber, for example, supports the pressure of the premix chamber and greatly reduces the amount of air entrained into the premix chamber.

By carrying only a portion of the fuel that will be burned into the premix area of each burner 30, 130, 230 and 330, the overall cross-sectional size of the burner becomes relatively small. The size is limited to design and build a burner capable of supplying 100% of the air required by the total premix approach. The venturi or mixer portion of such burners must be significantly larger and lack the capacity to accept low fuel pressure.

The premix chamber of each burner 30, 130, 230 and 330 according to the invention is relatively small, but the apparatus is sufficient to produce a premix stream of air and fuel using a significant amount of droplet entrained excess air. It can supply air and fuel. As a result, a significant increase in the overall fuel flow can be realized at comparable flame heights and diameters. Depending on the type of fuel to be burned, the burner of the present invention readily accommodates fuel flow rates designed to deliver fuel at speeds in excess of 1.4 times that typically achieved by diffusion jet type burners used to date. can do. In most cases, this can also be achieved while maintaining approximately the same flame length and diameter. When a large flame height is allowed, a significantly larger fuel flow rate can be obtained compared to the burner of the diffusion jet type that has been used so far. In addition, with respect to each embodiment of the burner of the present invention, ignition space placement and turn-down capabilities can be maintained while the fuel flow rate is increased. With respect to fuels of low molecular weight, the brighter part of the flame can also be reduced to some extent with alleviation of the flame, lowering the overall flame temperature. In some cases, this allows the burner to maintain or only minimally increase the spacing between the burners and the fencing between them as the fuel flow rate increases. The excess air carried to the center of the flame not only supplies air to the center of the flame, but also serves to reduce the rate at which the resulting fuel fumes are set to oxidize as soon as they exit the burner tip. This is proportionally shorter for a given heat release, forming a cleaner lead-free flame. The effect of dilution and subsequent cooling of the flame also serves to reduce nitrogen oxides and carbon monoxide emissions. The flow of fuel and air through the premix chamber also helps to cool the burner assembly.

The various configurations of the auxiliary fuel inlet have been described above. Additional constructions are also possible, including perforated multi-point injector bodies or headers to maximize splash entrainment and mixing of air in terms of available fuel pressure. The lower portion of each embodiment described above may comprise a Coanda surface or may be a straight portion. When using a Coanda surface, the port of the auxiliary fuel inlet can be a round orifice (jet) or slot. In addition to Coanda technology, fuel can be injected at a relatively high speed from the auxiliary fuel inlet to quickly obtain a mixture of fuel and air that can be injected into the center of the flame envelope. The dimensions of the various configurations of the flare burners of the present invention, including the dimensions of the premix chamber and fuel membrane, can vary. Moreover, it is possible to adopt various shapes of the ports (eg the size of the ports, the spacing between the ports) in relation to the main fuel outlet and the auxiliary fuel inlet. The specific dimensions and shapes used may depend on the type of fuel, molecular weight, temperature, calorific value, fuel reactivity, operating parameters (eg, available pressure) and other factors.

Although not generally necessary, a third inert fluid may be injected into the premix region of the flare burners (flare burners of all embodiments) of the present invention to enhance the entrainment of air to the premix region. Examples of third inert fluids that can be used include steam, air and nitrogen. Of these, steam is preferred.

In the accompanying drawings, there are shown embodiments of round shape and rectangular (polygon) of the flare burners of the present invention. Each embodiment of the flare burner of the present invention may also be formed in other geometric shapes. For example, ovals, triangles, squares, pentagons, octagons and other polygons may be employed in addition to round and rectangular shapes. Such other geometries can prove beneficial in terms of cost and fabrication. The optimal approach is to create a sparse excess air stream that can be transported from the premix chamber to the center of the main portion of the flame. However, fuel rich streams still provide a benefit for burners of the type using only diffusion that has been used so far since the mixing is improved by the burners of the present invention.

Ground of the present invention Flare

Referring to FIG. 29, the ground flare of the present invention is schematically shown at 420. The ground flare 420 includes a plurality of flare burners 422, an enclosure 424 extending around the flare burners, and a fuel supply pipe 426 for supplying fuel to the flare burners.

The flare burners are arranged in rows 430a through 430f and rows 432a through 432e. Rows 430a-430f form the first stage 434 of the flare burners 422, while rows 432a-432e form the second stage 436 of the flare burners. One or more of flare burners 422 are one of the embodiments of flare burners of the present invention described above. Preferably, each flare burner 422 in the second stage 436 of the flare burner 422 (burner used when a relatively large volume of fuel needs to be burned) needs to be described in accordance with the present invention. One of the embodiments of the flare burner. As needed, each of the flare burners 422 in both the first stage 434 of the burner and the second stage 436 of the burner is one of the embodiments of the flare burners of the present invention described above.

Fuel supply line 426 includes main line 440 terminating at distribution manifold 442. The first stage supply pipe 444 and the second stage supply pipe 446 are fixed in fluid communication with the distribution manifold 442. Each of the first stage supply pipes 450a to 450f extends from the first stage fuel supply pipe 444 to corresponding burner rows 430a to 430f. Similarly, the individual second stage supply pipes 452a through 452e extend from the second stage fuel supply pipe 446 to the corresponding burner rows 432a through 432e. For example, the first end 382 of the main branch 380 of the fuel delivery conduit 338 of the flare burner 330 of the present invention is secured to one of the individual supply pipes 450a to 450f or 452a to 452e. . Also, when other types of flare burners are used in the ground flare 420, the fuel feed conduits of these burners are appropriately secured to one of the individual supply lines 450a to 450f or 452a to 452e.

The series of pilots 460a-460f is in fluid communication with the first stage feed canal 444 and positioned with a suitable burner and fuel separation prior to ignition. The pilot is typically disposed adjacent to the first flare burner 422 in corresponding rows 430a through 430f. Similarly, a series of pilots 462a-462e are in fluid communication with second stage feed duct 446 and are positioned adjacent to first flare burner 422 in corresponding rows 432a-432e.

The enclosure 424 surrounds the flare burner 422 and includes a plurality of posts 470 and a fence portion 472 connected between these posts. The height of the enclosure or fence ranges from about 30 feet to about 60 feet. Enclosure 424 is designed to allow air to be sucked through the enclosure and to be sucked into the ground flap below the enclosure.

In the operation of the ground flare 420 of the present invention, the fuel to be burned is guided through the main line 440 to the distribution manifold 442. The valve control system (not shown) functions to distribute fuel to either the first stage fuel supply pipe 444 or both the first stage fuel supply pipe 444 and the second stage fuel supply pipe 446. When a relatively small volume of fuel is directed to the distribution manifold 442, the valve system directs the fuel only to the first stage fuel supply pipe 444. When the volume of fuel gas guided to the distribution manifold 442 is relatively large, the fuel is guided to both the first stage fuel supply pipe 444 and the second stage fuel supply pipe 446. In addition, additional stage tasks may be incorporated for cycle in and cycle out as needed. The fuel is guided from one or both of fuel supply pipes 444 and 446 to corresponding individual supply pipes 450a through 450f and / or 452a through 452e depending on the volume of fuel. The fuel is directed to the flare burner 422 from the individual feed ducts 450a-450f and / or 452a-452e in corresponding rows 430a-430f and / or 432a-432e.

If necessary, pilots 460a through 460f and 462a through 462e ignite the fuel discharged from the corresponding first burners 422 in their respective rows. The fuel ignited from the first burner 422 in each row then ignites the fuel discharged from the adjacent burner and then from the next burner in the row, etc., until the fuel discharged from each burner in that row ignites. Ignite the fuel released. The air required for combustion is drawn through the walls of the enclosure 424 and / or through the bottom thereof. It is not necessary to separately supply air to burner 422 or ground flare.

The ground flares of the present invention range from relatively small volumes of fuel (eg, up to 3,000 pounds per hour) to significantly larger volumes of fuel gas (eg, from 10,000 to an hour per hour depending on the molecular weight of the fuel to be burned, available pressure, temperature and other factors). Up to 15,000 pounds). Even for very large flow rates (eg 10,000 pounds per hour), the flame envelope produced by the ground flare burners of the present invention can be accommodated in conventional ground flare enclosures. The construction of the flare burner of the present invention allows larger volumes of fuel to burn at smaller ports and at higher pressures without significantly increasing the height of the flame envelope produced by the ground flare. Alternatively, the flame height can be lowered so that the height of the enclosure 424 is reduced. The burner of the present invention pumps air from underneath the burner, allowing the burner to be placed closer to the ground, and the required height of the enclosure 424 is also lowered as a result. As the number of burners and their associated parts decreases, less ground may be required.

In many cases, existing ground flares are retrofitted with flare burners 422 of the present invention so that more fuel is burned without causing the height of the flame envelope to be significantly greater than the height of the enclosure surrounding the ground flare. Can be. Also, due to the structure of the burners, the lead-free ratio for a given flare tip can be significantly larger within limits. By implementing an increase in throughput, more gas may be carried per individual header. This can make the number of headers combined with fewer control mechanisms such as gas control valves, shutoff valves, regulators and physical piping smaller. Increasing capacity with fewer headers also allows the enclosure 434 to be made smaller.

The ground flares of the present invention can be used to burn various types of fuel gases. Examples may include saturated and unsaturated hydrocarbons, such as propane, propylene and mixtures thereof, with or without hydrogen, water vapor and / or inert gases such as nitrogen, carbon, monoxide, argon, and the like.

The foregoing description of the ground flare of the present invention illustrates the ground flare, and in particular, how to use the flare burner of the present invention with it. As will be appreciated by those skilled in the art, the ground flare installation depends on how it is constructed: the number and type of burners, headers, flow systems, control valves and related components, the type and height of the enclosure surrounding the installation, and many other methods. It can be varied widely. The ground flare of the present invention may include any ground flare facility utilizing the flare burner of the present invention.

Method of the invention

According to the method of the present invention, fuel is burned in one of the flare burners 30, 130, 230 and 330 of the present invention. Referring to FIG. 24, fuel is injected into the combustion zone 101 through a fuel injector body (ie, main fuel outlets 36, 136, 236, and 336) to produce a flame envelope 100 and burn fuel. Is burned for. Some of the fuel to be combusted entrains the air into the premix zone and produces a mixture of air and fuel (preferably a substantially homogeneous mixture) inside the premix zone (ie, premix chambers 32, 132). 232 or 332). The mixture of air and fuel is then injected from the premix chamber into the central portion 104 of the flame envelope. Again, as described above, the amount of air that is entrained in the premix zone and injected into the central portion of the flame envelope ranges from a rich but combustible mixture to a mixture with splash entrained air that exceeds the stoichiometric amount required for combustion. It may be in the range of. This premixed stream of fuel and air injected into the center of the flame envelope initiates the second flame region to create an annular flame envelope. The overall result is that the entire flame envelope burns faster and more uniformly, thus obtaining the aforementioned advantages associated with the flare burners of the present invention.

As noted above, the amount of air entrained into the premix zone and injected into the central portion of the flame envelope is at least about 15% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone. Injecting a mixture of "fuel-rich" fuel and air (i.e., a mixture with less than 100% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone) into the central portion of the flame envelope. Is preferred in some applications. However, in most applications, a mixture of "fuel-lean" fuel and air (i.e., mixtures in excess of 100% of the chemopolitan amount of air required to support combustion of fuel injected into the premix zone) is used. It is preferred to spray into the central portion of the flame envelope. In most applications, the amount of air entrained in the premix zone and injected into the central portion of the flame envelope is about 125% to about 300% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone. Belongs to the scope of.

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

Please refer to the examples below to illustrate the invention in more detail.

Example 1

The flare burner 30 according to the first embodiment of the flare burner of the present invention was compared with a conventional high performance diffusion type ground flare burner, that is, the burners shown in Figs. Two flare burners of the present invention, each having a length of about 30 inches and about 16 inches, were tested. The flare burner of the present invention was designed to have a port corresponding to a three square inch flow area included in a conventional flare burner.

The flare burners of the present invention were first tested alone. The test was done using propane and propylene. About 20% of fuel was injected inside the premix chamber of each of the flare burners of the present invention. The remaining fuel was then injected around the main system of the air / fuel mixture withdrawn from the premix chamber. It has been found that each of the flare burners of the present invention can maintain significant fuel flow while generating unleaded flames using two types of fuel. The flame envelope from each burner was found to be very stable, with a significant turndown ratio and very symmetrical over the entire range of heat dissipation by combustion. The flame envelope from each burner was observed to be very short in length and small in diameter.

Then, the flare burner of the present invention having a length of about 30 inches was compared with a conventional burner. Two flare burners were tested side by side. The burners were fixed to the same header so that the same volume of fuel was supplied to each burner.

The flare burners of the present invention have been observed to produce a short flame envelope at most of the test points observed. The flare burner of the present invention remained ignited at low pressure during load regulation, indicating that the operating range was somewhat extended. At maximum fuel flow rate, the flame envelope generated by the flare burners of the present invention was shorter in total length than conventional high performance diffusion type ground flare burners. However, according to this scheme, the vertical cross section (width) of the flame envelope produced by the conventional flare burner was larger than the flame envelope produced by the flare burner of the present invention. No burn-back was observed in the flare burners of the present invention until the pressure was significantly below 1 psig. Radiation from the flame envelope generated by the flare burners of the present invention has been shown to be equivalent to or slightly weaker than radiation generated by the flame envelope generated by conventional flare burners. During the load regulation state, conventional flare burners generated smoke at approximately the same rate as the flare burners of the present invention. The trailing of the mist was typically noticeable from both burners at approximately the same flow rate and pressure. But. The flare burners of the present invention have been shown to maintain a less dense haze trail at lower pressures than diffusion type burner tips during initial testing. Conventional burners have transitioned to more smoke generation when the pressure is reduced.

Example 2

In addition, the flare burner 230 according to the third embodiment of the flare burner of the present invention was tested and compared with the conventional flare burner described above. The performance of the third embodiment of the flare burner of the present invention has been shown to be at least equivalent to the burner of the prior art. However, the burner of the present invention produced more smoke at a lower pressure than the first embodiment of the flare burner of the present invention described in Example 1. The lead-free operating range was comparable to the lead-free performance of conventional flare burners.

In this test, the corners of the premix chamber in the flare burners of the present invention produced a complex flow pattern that visually appeared to somewhat inhibit the mode of mixing in the premix chamber. As a result, spurious stratified fuel rich areas were observed to form at the corners of the premix discharge area, which resulted in visible visible layers over the entire surface of the flame area. On the other hand, the flared burner of the present invention tested was able to handle almost three times the amount of fuel that could be handled by conventional flare burners.

The welding used to assemble the test unit of the flare burner of the invention described in this example is incomplete (only after performing the appropriate tests) and eventually breaks. The weld in question was used only for the test unit (made of carbon steel), and the breakage of the weld was not due to design issues and was not related to the actual burner operation or performance. Tests have shown that in any case flare burners 230 can handle large amounts of fuel flow with minimal misting problems.

Accordingly, the present invention is very suitable for carrying out the objects of the present invention, and achieves the objects and advantages as well as the inherent objects thereof. Numerous variations can be made by those skilled in the art, but such variations are included in the spirit of the present invention as defined by the appended claims.

1 is a front elevational view showing a ground flare burner of the prior art.

FIG. 2 is a plan view of the flare burner shown in FIG. 1. FIG.

FIG. 3 shows the general shape of the flame envelope produced by the prior art flare burners shown in FIGS. 1 and 2.

4 is a perspective view of a first embodiment of a ground flare burner of the present invention.

5 is a cross-sectional view taken along line 5-5 of FIG. 4.

6 is a plan 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 showing an optional riser or tip extension.

FIG. 8 shows a variant of an annular fuel injector body that can be used in connection with the first, second and fourth embodiments of the flare burners of the present invention.

9 is a perspective view of a second embodiment of the flare burner of the present invention.

FIG. 10 is a cross-sectional view taken along the line 10-10 of FIG. 11.

10A is a diagram showing a modification of the annular distribution manifold used in connection with the second embodiment.

FIG. 11 is a plan view of the flare burner shown in FIGS. 9 and 10.

12 is a cross-sectional view taken along line 12-12 of FIG. 10.

Figure 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. 13.

FIG. 15 is a plan view of the flare burner shown in FIGS. 13 and 14.

16 is a cross-sectional view taken along line 16-16 of FIG. 13 showing an optional riser or tip extension.

FIG. 17 is a cross-sectional view taken along the line 17-17 of FIG. 15.

FIG. 17A shows a variation of the tubular distribution manifold used in connection with the third embodiment.

18 is a cross-sectional view taken along line 18-18 of FIG. 14.

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. 19.

FIG. 21 is a cross-sectional view taken along the line 21-21 of FIG. 22, showing optional components of the burner.

22 is a plan view of the burner shown in FIGS. 19 to 21.

FIG. 23 is a view showing a modification of the auxiliary fuel inlet of the burners shown in FIGS. 19 to 22.

FIG. 24 is a view showing a general shape of the flame envelope generated by each embodiment of the flare burner of the present invention.

Fig. 25 is a perspective view showing modifications that can be made to each embodiment of the flare burner of the present invention.

FIG. 26 is a cross-sectional view taken along the line 26-26 of FIG. 27.

FIG. 27 is a plan view of the burner shown in FIGS. 25 and 26.

FIG. 28 shows the general shape of the flame envelope produced by each embodiment of the flare burner of the present invention when improved in the manner shown in FIGS. 25-27.

29 is a view schematically showing an embodiment of the ground flare of the present invention.

<Explanation of symbols for the main parts of the drawings>

30, 130, 230, 330: flare burner

31, 131, 231, 331: premix area

31a, 131a, 231a, 331a: premix space

31b, 131b, 231b, 331b: internal

31c, 131c, 231c, 331c: premix space

32, 132, 232, 332 premix chamber

34, 134, 234, 334: auxiliary fuel inlet

36, 136, 236, 336: main fuel outlet

38, 138, 238, 338: fuel feeding conduits

40: pilot

48, 148, 248, 348: air inlet

50, 150, 250, 350: air / fuel outlet

54: fuel injector

58: fuel port

60: fuel membrane

68: seal

70, 188: fuel injector body

74, 192: fuel port

76, 196, 296, 376: gas riser or tip extension

100: flame envelope

164, 264: distribution manifold

166, 266: fuel port

170, 270, 360: fuel membrane

400: Premix Chamber Extension Cylinder

420: Ground Flare

422: Flare Burner

424: Enclosure

426: fuel supply pipe

434: first stage

436 second stage

442: Distribution Manifold

444: first stage supply pipe

446 second stage supply pipe

Claims (46)

A premix region comprising a premix chamber, the premix chamber comprising a top, a bottom, sidewalls connecting the top to the bottom, an air inlet disposed on one of the bottom and the sidewalls, and an air / fuel outlet disposed on the top. A premix area to be provided, An auxiliary fuel inlet for injecting fuel into the premix region, the auxiliary fuel inlet being positioned at a predetermined position with respect to the premix region such that air is splashed into the premix region when fuel is injected from the auxiliary fuel inlet to the premix region; An auxiliary fuel inlet, whereby a mixture of fuel and air is formed in the premix zone and discharged to the air / fuel outlet of the premix chamber; A main fuel outlet disposed at a predetermined position relative to the top of the premix chamber such that fuel can be injected from the main fuel outlet around the perimeter of the air / fuel outlet of the premix chamber Flare burner that includes. The flare burner of claim 1, wherein the air inlet is disposed at the bottom of the premix chamber. 2. The flare burner of claim 1, wherein said main fuel outlet is spaced outwardly from said premix chamber to provide an air droplet entrainment space therebetween. 2. The flare burner of claim 1, further comprising a fuel membrane disposed about an outer circumference of the premix chamber, the fuel membrane comprising a fuel inlet and in fluid communication with the main fuel outlet. 5. The flare burner of claim 4, wherein the fuel membrane and the main fuel outlet are spaced outwardly from the premix chamber to provide an air droplet entrainment therebetween. 5. The flare burner of claim 4, wherein the fuel membrane is in fluid communication with the auxiliary fuel inlet. 2. The flare burner of claim 1, further comprising a fuel feed conduit in fluid communication with said auxiliary fuel inlet and said primary fuel outlet for directing fuel to said auxiliary fuel inlet and said primary fuel outlet. 2. The flare burner of claim 1, wherein the main fuel outlet includes a plurality of fuel ports disposed around a perimeter of the air / fuel outlet of the premix chamber. 5. The fuel cell of claim 4, wherein each of the premix chamber, the fuel membrane, and the main fuel outlet, including the air / fuel outlet, is rounded such that fuel is annularly injected around the perimeter of the air / fuel outlet from the main fuel outlet. Flare burner having a cross section. The flare burner of claim 1, wherein the sidewall of the premix chamber comprises an inner side and an outer side, the inner side having a portion that is a Coanda Surface. 11. The flare burner of claim 10, wherein the auxiliary fuel inlet is disposed in a predetermined position relative to the premix chamber such that fuel can be injected from the auxiliary fuel inlet onto the coanda surface. 5. The flare burner of claim 4, wherein the sidewall of the premix chamber comprises an inner side and an outer side, the inner side having a portion that is a coanda surface. The method of claim 12, wherein the air inlet is disposed in the lower portion of the premix chamber, each of the premix chamber, the fuel membrane and the auxiliary fuel inlet including the air inlet has a round cross section, And the coanda surface extends annularly around the inner side of the sidewall of the premix chamber. The flare burner of claim 13, wherein the auxiliary fuel inlet is disposed in a predetermined position relative to the premix chamber such that fuel can be annularly injected from the auxiliary fuel inlet onto the coanda surface. 11. The method of claim 10, wherein the inner surface includes two opposing portions that are coanda surfaces, wherein the auxiliary fuel inlet is adapted to the premix chamber so that fuel can be injected from the auxiliary fuel inlet to each of the coanda surfaces. Flare burner which is in a predetermined position. The flare burner of claim 1, wherein the premix chamber has a ratio of length to inner hydraulic diameter in the range of about 0.25: 1 to about 4: 1. The flare burner of claim 1, wherein the premix chamber has a ratio of length to inner hydraulic diameter of about 1: 1 or less. A premix region comprising a premix chamber, the premix chamber having a top, a bottom, sidewalls connecting the top to the bottom, an air inlet disposed in the bottom, an air / fuel outlet disposed in the top, and about 0.25 A premix region having a ratio of length to inner hydraulic diameter in the range of from 1 to about 4: 1, An auxiliary fuel inlet for injecting fuel into the premix region, the auxiliary fuel inlet being positioned at a predetermined position with respect to the premix region such that air is splashed into the premix region when fuel is injected from the auxiliary fuel inlet to the premix region; An auxiliary fuel inlet, whereby a mixture of fuel and air is formed in the premix zone and discharged to the air / fuel outlet of the premix chamber; A main fuel outlet disposed at a predetermined position relative to the upper portion of the premix chamber such that fuel can be injected from the main fuel outlet around the perimeter of the air / fuel outlet of the premix chamber; 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 that includes. 19. The flare burner of claim 18, wherein the premix chamber including the air inlet and the air / fuel outlet and the main fuel outlet have a round cross section. 19. The flare burner of claim 18, wherein the main fuel outlet is spaced outwardly from the premix chamber to provide an air droplet entrainment space therebetween. 20. The system of claim 19, further comprising an annular fuel membrane disposed about an outer circumference of the premix chamber, the fuel membrane in fluid communication with the main fuel outlet and connecting top, bottom and top to the bottom. A flare burner having side walls. 22. The flare burner of claim 21, wherein the main fuel outlet includes a plurality of fuel ports attached to the top of the fuel membrane and extending around a perimeter of the air / fuel outlet of the premix chamber. The flare burner of claim 22, wherein the fuel membrane and the main fuel outlet are spaced outwardly from the premix chamber to provide an air droplet entrainment space therebetween. 19. The flare burner of claim 18, wherein the premix chamber has a ratio of length to inner hydraulic diameter of about 1: 1 or less. The flare burner of claim 24, wherein the auxiliary fuel inlet is spaced below the air inlet of the premix chamber. 19. 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 comprising 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 includes: A premix region comprising a premix chamber, the premix chamber comprising a top, a bottom, sidewalls connecting the top to the bottom, an air inlet disposed on one of the bottom and the sidewalls, and an air / fuel outlet disposed on the top. A premix area to be provided, An auxiliary fuel inlet for injecting fuel into the premix region, the auxiliary fuel inlet being positioned at a predetermined position with respect to the premix region such that air is splashed into the premix region when fuel is injected from the auxiliary fuel inlet to the premix region; An auxiliary fuel inlet, whereby a mixture of fuel and air is formed in the premix zone and discharged to the air / fuel outlet of the premix chamber; A main fuel outlet disposed at a predetermined position relative to the top of the premix chamber such that fuel can be injected from the main fuel outlet around the perimeter of the air / fuel outlet of the premix chamber Ground flare that includes. 28. The ground flare of claim 27 wherein said air inlet is disposed below said premix chamber. 28. The ground flare of claim 27 wherein said main fuel outlet is spaced outwardly from said premix chamber to provide an air droplet entrainment space therebetween. 28. The ground flare of claim 27 wherein the flare burner further comprises a fuel membrane disposed about an outer perimeter of the premix chamber, the fuel membrane comprising a fuel inlet and in fluid communication with the main fuel outlet. 33. The ground flare of claim 30 wherein said fuel membrane and said main fuel outlet are spaced outwardly from said premix chamber to provide an air droplet entrainment space therebetween. 31. The ground flare of claim 30 wherein said fuel membrane is also in fluid communication with said auxiliary fuel inlet. 28. The ground flare of claim 27 further comprising a fuel feed conduit in fluid communication with said auxiliary fuel inlet and said primary fuel outlet for directing fuel to said auxiliary fuel inlet and said primary fuel outlet. 28. The ground flare of claim 27 wherein the main fuel outlet comprises a plurality of fuel ports disposed around a perimeter of the air / fuel outlet of the premix chamber. 31. The fuel cell of claim 30, wherein each of the premix chamber, the fuel membrane, and the main fuel outlet including the air / fuel outlet is rounded such that fuel can be annularly injected around the perimeter of the air / fuel outlet from the main fuel outlet. Ground flare having a cross section. 28. The ground flare of claim 27 wherein said sidewall of said premix chamber comprises an inner side and an outer side, said inner side having a portion that is a coanda surface. 37. The ground flare of claim 36 wherein the auxiliary fuel inlet is disposed at a location relative to the premix chamber such that fuel can be injected from the auxiliary fuel inlet onto the coanda surface. 31. The ground flare of claim 30 wherein the sidewall of the premix chamber comprises an inner side and an outer side, the inner side having a portion that is a coanda surface. The method of claim 38, wherein the air inlet is disposed in the lower portion of the premix chamber, wherein each of the premix chamber, the fuel membrane and the auxiliary fuel inlet including the air inlet has a rounded cross section, And the Coanda surface extends annularly around the inner side of the sidewall of the premix chamber. 40. The ground flare of claim 39 wherein the auxiliary fuel inlet is in a predetermined position relative to the premix chamber such that fuel can be annularly injected from the auxiliary fuel inlet onto the coanda surface. 37. The premix chamber of claim 36, wherein the medial side includes two opposing portions that are coanda surfaces, wherein the auxiliary fuel inlet is adapted to the premix chamber so that fuel can be injected from the auxiliary fuel inlet to each of the coanda surfaces. The ground flare which is in a predetermined position. A fuel flaring method using a flare burner, wherein the fuel to be burned is injected through a burner's fuel outlet into a combustion zone, and is ignited to generate a flame envelope and burn fuel. Injecting a portion of the fuel to be combusted into the premix zone of the burner in such a manner as to entrain air into the premix zone and produce a mixture of air and fuel in the premix zone; Injecting the mixture of air and fuel from the premix zone into the central portion of the flame envelope Fuel flaring method that is improved including. 43. The method of claim 42 wherein the amount of air entrained into the premix zone and injected into the central portion of the flame envelope is about 125% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone. And from about 300% to fuel flaring method. The amount of air entrained in the premix zone and injected into the central portion of the flame envelope is about 150% of the stoichiometric amount of air required to support combustion of fuel injected into the premix zone. And from about 300% to fuel flaring method. 43. The method of claim 42, wherein the amount of fuel injected into the premix region 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 injected into the premix region ranges from about 10% to about 30% of the total amount of fuel to be burned by the flare burner.

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