Patent Publication Number: US-11029026-B2

Title: Flare tip assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 62/807,819 filed Feb. 20, 2019, titled “FLARE TIP ASSEMBLY,” the disclosure of which is incorporated herein in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE INVENTION 
     Embodiments disclosed herein relate generally to a flare tip assembly used in the combustion of gases in flare stacks for the destruction of combustible vapors in various applications, including those on oil and gas production pads, crude oil tank batteries, midstream liquified natural gas processing facilities, offshore platforms, and refining and petrochemical applications during normal and emergency operations, for efficient combustion of both low pressure vapors and high pressure vapors in a single stack, as the embodiments can safely flare both sub sonic and sonic flows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. 
         FIG. 1  depicts a flare tip assembly in accordance with an embodiment of the present invention. 
         FIG. 2  depicts a flare tip assembly in accordance with an embodiment of the present invention. 
         FIGS. 3A &amp; 3B  depict a flare tip assembly in accordance with an embodiment of the present invention. 
         FIGS. 4A &amp; 4B  depict a portion of the flare tip assembly shown in  FIGS. 1-3 , in accordance with an embodiment of the present invention. 
         FIGS. 5A &amp; 5B  depict a flare tip assembly in accordance with an embodiment of the present invention. 
         FIG. 6  depicts a cone portion of the flare tip assembly in accordance with an embodiment of the present invention. 
         FIGS. 7A &amp; 7B  depict a cone portion of the flare tip assembly in accordance with an embodiment of the present invention. 
         FIGS. 8A &amp; 8B  depict a cone portion of the flare tip assembly in accordance with an embodiment of the present invention. 
         FIGS. 9A to 9E  depict partial perspective views of a flare tip assembly in accordance with an embodiment of the present invention. 
         FIG. 10  depicts a shroud portion in accordance with an embodiment of the present invention. 
         FIG. 11  depicts a shroud portion in accordance with an embodiment of the present invention. 
         FIG. 12  depicts an anti-rotation slotted guide  119  as shown in  FIGS. 2-4 , in accordance with an embodiment of the present invention. 
         FIGS. 13A-13D  depict flow profiles using a flare tip assembly in accordance with an embodiment of the present invention. 
         FIG. 14  depicts a capacity curve for a high turndown ratio flare tip assembly in accordance with an embodiment of the present invention. 
         FIGS. 15 to 19  depict example flare capacity curves for various single flare tip assemblies in embodiments of the present invention. 
     
    
    
     While certain embodiments will be described in connection with the preferred illustrative embodiments shown herein, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by claims. In the drawing figures, which are not to scale, the same reference numerals are used throughout the description and in the drawing figures for components and elements having the same structure, purpose or function. 
     DETAILED DESCRIPTION 
     Turning now to the detailed description of the preferred arrangement or arrangements of various embodiments of the present invention, it should be understood that, although an illustrative implementation of one or more embodiments are provided below, the inventive features and concepts may be manifested in other arrangements and that the scope of the invention is not limited to the embodiments described or illustrated. The various specific embodiments may be implemented using any number of techniques known by persons of ordinary skill in the art. The disclosure should in no way be limited to the illustrative embodiments, drawings, and/or techniques illustrated below, including the exemplary designs and implementations illustrated and described herein. The scope of the invention is intended only to be limited by the scope of the claims that follow. Furthermore, the disclosure may be modified within the scope of the appended claims along with their full scope of equivalents. 
     While the making and using of various embodiments of the present disclosure are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the disclosure and do not limit the scope of the disclosure. 
     The present disclosure will now be described more fully hereinafter with reference to the accompanying figures and drawings, which form a part hereof, and which show, by way of illustration, specific example embodiments. Subject matter may, however, be embodied in a variety of different forms and, therefore, covered or claimed subject matter is intended to be construed as not being limited to any example embodiments set forth herein; example embodiments are provided merely to be illustrative. Likewise, a reasonably broad scope for claimed or covered subject matter is intended. Among other things, for example, subject matter may be embodied as methods, devices, components, or systems. The following detailed description is, therefore, not intended to be taken in a limiting sense. 
     Throughout the specification and claims, terms may have nuanced meanings suggested or implied in context beyond an explicitly stated meaning. Likewise, the phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment and the phrase “in another embodiment” as used herein does not necessarily refer to a different embodiment. It is intended, for example, that claimed subject matter include combinations of example embodiments in whole or in part. 
     In general, terminology may be understood at least in part from usage in context. For example, terms, such as “and”, “or”, or “and/or,” as used herein may include a variety of meanings that may depend at least in part upon the context in which such terms are used. Typically, “or” if used to associate a list, such as A, B or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B or C, here used in the exclusive sense. In addition, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures or characteristics in a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context. 
     As shown in  FIGS. 1-3 , an embodiment of the present invention provides a flare tip assembly  100  that is capable of firing at very low rates and low pressure and firing during upset with high flow and high pressure without smoking, in order to follow federal and state regulations. The flare tip assembly  100  provides a high turndown ratio operation by adjusting the open area for gas flow automatically In one embodiment of the present invention, the flare tip assembly  100  is mounted on the top of new or existing flare stacks (not shown) and utilizes the various pressures of the waste stream to adjust the open area for proper fuel and air mixing. 
     As shown in  FIGS. 1-5 , a flare tip assembly  100  according to an embodiment of the invention is provided for the combustion of vapors in a flare system. The flare tip assembly  100  is designed to safely and efficiently burn vapors, including hydrocarbon bearing waste and vent streams. The flare tip assembly  100  includes a nozzle tube  101  such as a machined pipe tapered on top to fit a machined cone  104  with a diameter based on flow area needed. This nozzle tube  101  is fitted for example with a flanged connection  102  (see e.g.,  FIG. 9D ) or other suitable connection for mounting to an elevated flare stack (not shown). Opposite the flanged end  102  is a machined chamfered end  103  that is angled to allow the seating and sealing of the cone  104  in low pressure operations and to optimize waste and vent stream vapor flow. For example, the machined chamfered end  103  is can be angled between 15° and 80°, such as 30°, 45°, 60° and 75°, and other angles that can be used to optimize waste and vent stream vapor flow. 
     The nozzle tube  101  can include machined slots (not shown), spaced along the length of the nozzle tube  101  for attaching centering guides  105 . Within the nozzle tube  101  there is a connecting rod  108  that extends within the nozzle tube  101  along the nozzle tube  101 &#39;s longitudinal axis. The connecting rod  108  passes through the centering guides  105  installed in the nozzle tube  101  and extends into the spring assembly  109 . The connecting rod  108  also extends through an anti-rotation slotted guide  119  ( FIGS. 2, 3, 4 and 12 ) that is connected to a rotation stop rung  120 . In one embodiment the spring assembly  109  sets below the flanged end  102  of the nozzle tube  101 , which takes the spring assembly  109  below the flare&#39;s active flame, making it readily serviceable. See e.g.,  FIG. 9D . In another embodiment (not shown), the spring assembly  109  is located above the flanged end  102 . In another embodiment, a spring connection tube  110  encloses the spring assembly  109 . In a further aspect of this embodiment, at one end of the spring connection tube  110  a cap  113  is attached to the spring connection tube  110 . The type, design and material of spring assembly  109  can be the same or different depending on the flare tip design and gas stream properties. In one embodiment, single or multiple compression springs are used in the spring assembly  109 . See e.g.,  FIG. 5A . In another embodiment, a stack of disc springs is used to achieve the desired function. See e.g.,  FIG. 9D . In another embodiment (not shown), the spring assembly  109 , connection tube  110  and cap  113  are removed and the gravity force of the cone  104  and connecting rod  108  can still achieve the design functions. 
     At the end of the connecting rod  108  that is opposite to the spring assembly  109 , a cone shaped structure  104  is connected to the connecting rod  108 . In one embodiment, the cone  104  is attached to the connecting rod  108  by welding a substantially flat shaped cone  104  bottom to the connecting rod  108 , which is attached at the bottom center of the cone  104 . In other embodiments, the cone  104  is integrally formed with the connecting rod  108 , or the cone  104  is connected to the connecting rod  108  using a threaded connector, or the cone  104  is connected to the connecting rod  108  using a pinned connection, or the connecting rod  108  extends up through the cone  104  and is connected to the bottom of a concaved section  112  of the cone  104  body, or any combination thereof and the like. See e.g.,  FIGS. 3-8 . 
     The cone  104  is preferably a machined cone with a concave top  112  having a taper with a cone angle of between 15° and 80°, such as 30°, 45°, 60°, 75° and other angles, from the top to the bottom. See e.g.,  FIG. 6 . The cone  104  can be manufactured by many means such as casting, fabricated with tubes welded therein, 3-D printing or any other appropriate manufacturing methods. Sizing of the cone  104  is designed based on diameter of nozzle tube  101  and desirable flowrates at various inlet pressure. The transition from the concave top  112  to the taper is a rounded edge. In one embodiment of the present invention the cone has rounded smooth edges, which enhance the and help maintain a controlled frame profile. In a further aspect of any embodiment of the present invention, the cone tip diameter is sized to achieve designed flow across a wide range of capacities, and include cone diameters of 2-inch, 3-inch, 4-inch, 6-inch and 8-inch. 
     In one embodiment, the cone  104  is designed such that the tapered end sits within a seat formed by the chamfered end  103  of the nozzle tube  101 . See e.g.,  FIGS. 3, 5A, 9C, 9E, 13D . In one embodiment, the cone  104  includes tubular firing orifices  111  drilled from the bottom of the concaved top  112  through the cone  104  body and exiting along an outer surface of the cone  104 . The diameter, angle of attack, and total amount of firing orifices  111  are configured based on flowrate and size of the flare tip assembly  100 , to optimize fuel gas dispersion and air/fuel mixing. In one embodiment, the diameter of firing orifices  111  changes between 1/16 in and ½ in, including ⅛ in, 3/16 in, ¼ in, ⅜ in, and other sizes. In one embodiment, the total amount of firing orifices  111  changes between 2 and 12, including 4 ( FIG. 5A, 7, 9C ),  6  ( FIG. 4, 8 ),  8 ,  10 , and other numbers. In a further aspect of an embodiment, the firing orifices  111  are drilled from the bottom of concaved top  112  through the cone  104  body and preferably exit at approximately half the height of the cone  104 . See e.g.,  FIGS. 3-8, 9C . In another aspect of an embodiment, the orifices  111  are preferred to be axisymmetric and tangential to the cone  104 . See e.g.,  FIGS. 3-8, 9C . 
     In an embodiment of the present invention, the cone  104  and tubular firing orifices  111  are configured to minimize the use of purge gas and/or velocity reduction devices in order to prevent burn back inside the nozzle tube  101  and flare stack (not shown). For example, in an embodiment of the present invention, no or minimum purge gas is required. In an embodiment of the present invention, the tip design minimizes and or does away with the need of purge gas and/or velocity seals used to prevent the back flow of combustible gases back into the nozzle tube  101  and flare stack (not shown) during low fire conditions. For example, in one embodiment this is achieved due to the cone  104  shape with the concave top  112 , with a cone  104  angle of between 15° and 80°, along with the multiple tangential tubular orifices  111  that pass through the cone  104  body starting in the concave face  112  and passing through the cone  104  at an angle. See e.g.,  FIGS. 3-8, 9C . The combination of these firing orifices  111  and the sealing of the cone  104  to the chamfered end  103  at low flowrate, means that the flow must pass through the firing orifices  111  where in one embodiment, by size and position they achieve a length over diameter of greater than two, which can help prevent the propagation of the flame front back through the firing orifices  111  even at very low pressures. 
     Around the perimeter of the nozzle tube  101  there are gusset halves  106  for lower shroud  107  mounting. See e.g.,  FIGS. 1-3, 9B . In one embodiment, the shroud assembly can include two parts—the upper  114  and lower shroud  107 . In one embodiment, the shrouds  107 ,  114  are tubular. In another embodiment, the shrouds  107 ,  114  are approximately twice or three times the diameter of the nozzle tube  101 . In one embodiment, the lower shroud  107  is positioned with mounting gussets  117  so that nozzle tube  101  is placed at the center of lower shroud  107  and the bottom of lower shroud  107  is approximately twelve to twenty-four inches below the exit of the nozzle tube  101 . See e.g.,  FIGS. 3-8, 9A, 9B . The mounting gussets  117106  can be outside of lower shroud  107  as in  FIG. 1-3  or inside as in  FIGS. 9A and 9B . The lower shroud  107  also contains the pilot hood  116  extending from its side at a 45°-degree angle. The pilot hood  116  allows for the pilot flame to intersect the fuel exit area between the nozzle tube  101  and cone  104 . See e.g.,  FIGS. 13A-13D . This covered pilot design prevents excessive wear and damage of the pilot assembly. The upper shroud  114  is attached to the top of the lower shroud  107  with mating flanges  118  and extends upwards some distance. In one embodiment, the distance or height of the upper shroud  114  is based on flow rate and flare size. For example, to address the issue of the flame being affected by wind and to help induce more efficient mixing, in one embodiment of the present invention a larger/longer shroud  114  can be used, for example going from a 12″ shroud height to 36″ shroud height. In one embodiment of invention, using a shroud  114  having a larger length over diameter (LID) ratio provides better fuel and air mixing, which allows for more stable combustion before the mixture is dispersed by wind. Exemplar features of various flare tip embodiments of the present invention are shown below in Table 1. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Cone 
                   
                   
                   
                   
                   
                   
               
               
                   
                 TIP 
                 Cone 
                 Shroud 
                 Number of 
                 Shroud 
                 Orifice 
                 Orifice Angle  
               
               
                   
                 Size 
                 Angle 
                 Height 
                 Orifices 
                 L/D 
                 Diameter 
                 of Attack 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 HTDR- 
                 2″ 
                 15° to 80° 
                 25′ 
                 4 to 10 
                 3 to 6 
                 1/16″ to 1/2″ 
                 30° to 60° 
               
               
                 Mini 
                   
                   
                   
                   
                   
                   
                   
               
               
                 HTDR-1 
                 3″ 
                 15° to 80° 
                 35′ 
                 4 to 10 
                 3 to 6 
                 1/16″ to 1/2″ 
                 30° to 60° 
               
               
                 HTDR-2 
                 4″ 
                 15° to 80° 
                 45′ 
                 4 to 10 
                 3 to 6 
                 1/16″ to 1/2″ 
                 30° to 60° 
               
               
                 HTDR-3 
                 6″ 
                 15° to 80° 
                 65′ 
                 4 to 10 
                 3 to 6 
                 1/16″ to 1/2″ 
                 30° to 60° 
               
               
                 HTDR-4 
                 8″ 
                 15° to 80° 
                 85′ 
                 4 to 10 
                 3 to 6 
                 1/16″ to 1/2″ 
                 30° to 60° 
               
               
                   
               
            
           
         
       
     
     In one embodiment, there are a number of spaced openings  115  around the perimeter of the top of the upper shroud  114 . See e.g.,  FIGS. 1-3, 10, 11 . In a further aspect of this embodiment, the upper shroud  114  includes equally spaced openings  115  around the perimeter of the top of the upper shroud  114 . The spacing and total numbers of spaced openings  115  varies depending on flare size. The design of the upper shroud  114  with spaced openings  115  not only enhances stability of the flame front but helps to negate some of the effects of crosswinds. In one embodiment, the upper shroud  114  includes multiple rows of spaced openings  115 . In this embodiment, during for example high fire situations, the multiple rows of spaced openings  115  allow more air to be induced in the mixture allowing for complete combustion, thus promoting smokeless performance. 
     The shape of the tapered cone  104  with a concave top  112 , and use of the tangential firing orifices  111 , and use of upper shroud  114  with openings  115 , aid to induce a vortex flow which creates more turbulence when mixing the fuel stream with the annular air flow between the nozzle tube  101  and lower shroud  107 , thus allow for a stable flame attachment in both low and high pressure flow conditions, providing a high turndown ratio configuration, See e.g.,  FIGS. 1-3, 10, 11 . In a further aspect of an embodiment of the present invention, the cone  104  design directs fuel flow outward at a predetermined angle for optimized mixing and interaction with the shroud  107 ,  114 , which creates a unique and efficient flow pattern that is carried throughout the flare firing range resulting in a stable, smokeless operation. 
     In one embodiment, during normal low-pressure operation the fuel, such as a hydrocarbon-based waste stream, is introduced to the fuel inlet on the base of an elevated flare stack (not shown) and will travel up through the stack and exit out of the nozzle tube  101 /cone  104  assembly. In one embodiment, if this is a low-pressure stream, for example less than one pound per square inch gauge (PSIG) pressure, the cone  104  is completely seated at the chamfered end  103  of nozzle tube  101 , with the fuel stream only passing through the firing orifices  111 . This low-pressure flow is ignited as it exits the firing orifices  111  by the pilot and the concave top  112  of the cone  104  is designed to further create a low-pressure zone of recirculation to maintain stability. Air is drawn into the bottom of the lower shroud  107  in a low-pressure case as the result of a draft created from heating the air inside the shroud  107 . In one embodiment, the spring assembly  109  is configured allow cone  104  to move upward and unseat from the chamfered end  103  of nozzle tube  101  as the pressure is increased inside the nozzle tube  101 . See e.g.,  FIGS. 1-3, 9D . In this embodiment, cone  104  will begin move upward creating an annular orifice around the perimeter of the cone  104  and the exit of the nozzle tube  101 , while also applying some tension to the spring assembly  109 . Fuel gas stream now exits through both the annular orifice mentioned above and the firing orifices  111 . Once the pressure exceeds a predetermined value, for example approximately eight PSIG, the cone  104  is fully extended and the effective annular orifice open area is equal to the open area of the nozzle tube  101 . As the cone  104  begins to rise the pressure of the fuel gas will begin to create a venturi effect at the air inlet to the shroud  107  pulling a certain percentage of the needed combustion air into the shroud  107  and  114 , thus creating a partial premix condition. The partial premix in conjunction with the variable annular orifice between tapered surface of cone  104  and chamfered end  103  of nozzle tube  101 , firing orifices  111  and shroud  107 ,  114  allow better fuel dispersion and fuel/air mixing, creating a very stable smokeless operation across a wide range of fuel gas pressure. 
     Referring to  FIGS. 13A-13D , depicted are example flow contours that depict the flow of C 3 H 8  (propane) in millions of standard cubic feet per day (MMSCFD) through a flare tip assembly embodiment of the present invention and travel of the cone  104  away and unseated from the nozzle tube  101  as the flow rate is increased. These flow contours are calculated by using advanced Computational Fluid Dynamics (CFD) simulation. As depicted the C3H8 flow rate increases respectively in  FIGS. 13A-13D . And as the flow increase, for example, 4.05 MMSCFD in  FIG. 13A  and 13.36 MMSCFD in  FIG. 13D , the cone  104  is completely unseated in  FIG. 13D  as compared to the location of the cone  104  within the nozzle tube  101  as depicted in  FIGS. 13A-13C . As also depicted, the flow is substantially uniform. 
     Above certain fuel pressure which is enough to overcome the spring tension and gravitational force of cone  104 , rod  108  and spring assembly  109 , the cone  104  tip will lift up creating more open area for the gas flow. The lifting distance of cone  104  is related to fuel pressure allowing for a design that adjusts the open area for various conditions while also being capable of firing variable range of fuels compositions. The flare tip assembly  100  is designed so that the cone  104  will start to lift and rise until full open within an appropriate gas pressure range, achieving better fuel/air mixing and also preventing high upstream back pressure. To create more tension in order to keep the cone  104  tip from becoming fully open at a low pressure stiffer springs should be used in the system. For example, in an embodiment of the present invention, six (6) polywave springs can be used for the spring assembly  109 . For example, during testing, using six (6) polywave springs, the system became fully open at about 4-5 PSIG. In a further aspect of an embodiment of the present invention, the configuration of the spring assembly  109 , and cone  104  design yield a larger turndown capability, keeping the fuel gas exit velocity within the design range by preventing the system from opening fully too early. The spring assembly  109  is designed to have a spacer (not shown) that will allow variable tension loading to add more flexibility. 
     In one embodiment, this apparatus, when mounted on an elevated flare stack (not shown) facilitates the mixing of fuel and air across a wide range of fuel pressures, allowing for the efficient combustion of the fuel stream, with ninety-eight percent (98%) or higher destruction efficiency and with no visible smoke. In a further aspect of an embodiment of the present invention, the flare tip assembly  100  including cone  104 , firing orifices  111 , spring assembly  109  and shroud  114  with openings  115  is designed based on the maximum flow rate that is required and the maximum available gas pressure, while maintaining acceptable gas velocity at exit of shroud  114 . 
     In one embodiment of the present invention, the flare tip assembly  100  provides a greater than 200 to 1 turndown ratio of the flare. In a further aspect of an embodiment of the present invention, the cone  104  geometry design and inclusion of firing orifices  111  allows for accommodating low and high-pressure vent gas eliminating the need for multiple flares (e.g., a low-pressure flare assembly and a high-pressure flare assembly). See e.g.,  FIG. 14 . For example, as shown in  FIG. 14 , a flare capacity curve for a flare tip assembly in accordance with an embodiment of the present invention shows that the single flare tip assembly can operate at a pressure range of 0 to 30 psig with a volumetric gas flow of 0 to approximately 24 MMSCFD, as opposed to requiring multiple flare assemblies to operate over this range. Moreover, the single flare tip assembly of an embodiment of the present invention can operate over this range while meeting emission requirements. For example, a small traditional flare would operate in the curve  125  region, a medium traditional flare would operate in the  126  region, and a large traditional flare would operate in the  127  region. 
     Further examples of flare capacity curves for various single flare tip assemblies in accordance with an embodiment of the present invention are shown in  FIGS. 15-19 . As shown in  FIGS. 15-19 , curve A represents a light fuel gas having a lower heating value (LHV) of 1067.87 btu/scf and a molecular weight (MW) of 20.62, curve B represents the a medium fuel gas having a lower heating value (LHV) of 1542.99 btu/scf and a molecular weight (MW) of 31.28, and curve C represents a heavy fuel gas having a lower heating value (LHV) of 2250:96 btu/scf and molecular weight (MW) of 43.47. For example, as shown in  FIG. 15 , the Flare-Mini flare tip assembly in accordance with an embodiment of the present invention can operate at a pressure range of 0 to 50 psig with a volumetric gas flow of 0 to approximately 4.4 MMSCFD for a light fuel gas. 
     As shown in  FIG. 16 , the FLARE-1 flare tip assembly in accordance with an embodiment of the present invention can operate at a pressure range of 0 to 40 psig with a volumetric gas flow of 0 to approximately 8.8 MMSCFD for a light fuel gas. 
     As shown in  FIG. 17 , the FLARE-2 flare tip assembly in accordance with an embodiment of the present invention can operate at a pressure range of 0 to 30 psig with a volumetric gas flow of 0 to approximately 13 MMSCFD for a light fuel gas. 
     As shown in  FIG. 18 , the FLARE-3 flare tip assembly in accordance with an embodiment of the present invention can operate at a pressure range of 0 to 30 psig with a volumetric gas flow of 0 to approximately 29 MMSCFD for a light fuel gas. 
     As shown in  FIG. 19 , the FLARE-4 flare tip assembly in accordance with an embodiment of the present invention can operate at a pressure range of 0 to 30 psig with a volumetric gas flow of 0 to approximately 50 MMSCFD for a light fuel gas. 
     In a further aspect of an embodiment of the present invention, the upper shroud  114  length, openings  115  quantity, size, and placement further allow for accommodating low and high-pressure vent gas eliminating the need for multiple flares (e.g., a low-pressure flare assembly and a high pressure flare assembly). 
     This flare tip assembly  100  can be used in a wide range of applications and in certain situations negate the need for multiple flares or pieces of combustion equipment as it can safely flare both sub sonic and sonic flows. It would be suited for applications including those on oil and gas production pads, crude oil tank batteries, midstream liquified natural gas processing facilities, offshore platforms, and refining and petrochemical applications. Embodiments of the present invention can be used in conjunction with other smoke-reducing technologies, such as air-assisted flare, steam-assisted flare for handling heavier fuels and other applications that have poor air/fuel mixing. As mentioned earlier, embodiments of the present invention can be installed on flare stacks for elevated flares. Furthermore, they can also be used for ground flares, enclosed combustors and other combustion devices including thermal oxidizers, etc. Serial and/or parallel uses of multiple embodiments of the present invention can be arranged for applications such as multi-point ground and/or elevated flaring. 
     Although the apparatuses and methods described herein have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art may be able to study the exemplar embodiments and identify other ways to practice the invention that are not exactly as described herein. It is the intent of the inventor that variations and equivalents of the invention are within the scope of the claims while the description, abstract and drawings are not to be used to limit the scope of the invention. The invention is specifically intended to be as broad as the claims below and their equivalents.