STAGED STEAM WASTE GAS FLARE

Abstract

A steam flare is provided that injects steam, unmixed with air into a waste gas stream at locations where the resulting accelerated steam and waste gas mixture upon exposure to the surrounding air induces a mixture of steam, waste gas and air with improved combustion and effectively complete destruction of the waste gas, and where under low-flow conditions, reduced steam and/or assist gas are required to maintain smokeless operation. The steam is injected via multiple tubes each controlled independently so that steam can normally be flowed via a first tube, and then, when operation loads require, flowed via a second tube. The first and second tubes may be concentric and may be in communication with steam supplies that have different pressures of steam.

Claims

1. A steam flare comprising: a flare gas conduit configured to receive waste gas and provide the waste gas to a combustion zone, and a steam tube located in said flare gas conduit, wherein said steam tube comprises an outer tube and an inner tube inside of said outer tube, both of said outer tube and said inner tube having at least one orifice configured to provide steam into the flare gas conduit.

2. The steam flare of claim 1, wherein the outer tube is in communication with a supply of steam having a first steam flow rate and a first pressure.

3. The steam flare of claim 2, wherein the inner tube is in communication with a supply of steam having a second steam flow rate and a second pressure, the second steam flow rate, the second pressure, or both being different, respectively, from the first steam flow rate and the first pressure.

4. The steam flare of claim 3, wherein the second pressure is lower than the first pressure for a given rate of steam flow to either the outer tube or the inner tube.

5. The steam flare of claim 3, wherein the second pressure is higher than the first pressure for a given rate of steam flow to either the outer tube or the inner tube.

6. The steam flare of claim 1, wherein a steam supply through the inner tube is independent of a steam supply of the outer tube.

7. The steam flare of claim 1 further comprising: a sensor; a flow regulating device configured to regulate a steam flow, a pressure, or both associated with steam provided by one of the inner tube and the outer tube; a controller in communication with the sensor and the flow regulation device and being configured to increase or decrease the steam flow, the pressure, or both based on a signal from the sensor.

8. A steam flare comprising: a flare gas conduit in communication with a source of flare gas; and, a steam tube located proximate said flare gas conduit so that steam from said steam tube is directed into a flame from combustion of said flare gas, wherein said steam tube comprises a plurality of tubes each having at least one orifice and a first tube from said plurality being configured to provide steam independent of steam provided from a second tube.

9. The steam flare of claim 8, wherein the first tube is concentric with the second tube.

10. The steam flare of claim 8, wherein the steam tube is disposed within the flare gas conduit.

11. The steam flare of claim 8, wherein the first tube is in communication with steam having a first steam flow rate and a first pressure.

12. The steam flare of claim 11, wherein the second tube is in communication with steam having a second steam flow rate and a second pressure, the second steam flow rate, the second pressure, or both being different, respectively, from the first pressure and the first steam flow rate.

13. The steam flare of claim 8 further comprising: a sensor; a flow regulating device configured to regulate a steam flow, a pressure, or both associated with steam provided by one of the first tube and the second tube; a controller in communication with the sensor and the flow regulation device and being configured to increase or decrease the steam flow, the pressure, or both based on a signal from the sensor.

14. A process of operating a steam flare comprising: sending a waste gas stream through a flare gas conduit at a first flare gas flow rate while providing a steam through a first steam tube in communication with a supply of steam having a first steam flow rate and a first pressure, wherein said first steam tube is proximate said flare gas conduit so that steam from the first steam tube mixes with waste gas from said waste gas stream; causing a flame to burn as a resulting mixture of said waste gas stream, said steam, and oxygen in outside ambient air; and, sending a second stream of steam through a second steam tube, wherein said second steam tube is in communication with a supply of stream having a second steam flow rate and a second pressure, and wherein said second pressure is greater than said first pressure for a given steam flow rate.

15. The process of claim 14 further comprising: monitoring said first flare gas flow rate of said waste gas stream; and when, said first flare gas flow rate exceeds a predetermined level, adjusting a flow rate of the second stream of steam.

16. The process of claim 14, wherein said first steam tube is concentric with said second steam gas tube.

17. The process of claim 14, wherein said first steam tube and said second steam tube are located within said flare gas conduit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is an isometric perspective of a top portion of a steam flare.

[0017] FIG. 2 is a view of the steam flare including a waste gas cylinder and tube for steam.

[0018] FIG. 3 is a cutaway upper portion of the steam flare.

[0019] FIG. 4 is an isometric view of two flare enclosure conduits.

[0020] FIG. 5 is a side cut view a flare gas conduit according to an aspect of the present invention.

[0021] FIG. 6 is a top view of the flare gas conduit of FIG. 5

DETAILED DESCRIPTION OF THE INVENTION

[0022] In some embodiments, the present invention delivers smokeless combustion while utilizing less than 0.20 lbs steam per lb of propane waste gas stream while requiring no steam for cooling and minimal steam for warming (less than 0.0006 lbs steam per maximum vent gas flow).

[0023] Some embodiments of the invention rely solely on completely internal steam, steam injected completely internally to the flare vent gas ducting with no exposure to surrounding atmospheric air while imparting a significant mixing and momentum transfer effect on the surrounding ambient air environment. Other flares rely on stream that is injected into the air near and immediately surrounding the periphery of the flare tip and aimed so that they drive steam and air near and immediately surrounding the periphery of the flare tip and aimed so that they drive stream and air into the waste gas or effluent stream of the waste gas. Such flares are referred to as External Steam Flares. There are other flares that may be termed Internal Steam Flares that rely on injecting steam through conduits, passageways, or a venturi from a surrounding air atmosphere thereby injecting air and steam through the containing wall or shell of the waste gas stream and into the central core of the waste gas stream.

[0024] As shown in FIG. 1, a waste gas stream passes up through a cylinder 12. Steam 2 is injected into the waste gas stream 1 at one or more locations 4 whereupon the resulting accelerated stream and waste gas mixture, upon exposure to the surrounding air induces the surrounding air into the waste gas (fuel) and steam mixture. There is no mixture of the surrounding air 3 with the waste gas stream 1 before exiting the top of the flare enclosure conduits. The steam and waste gas 5 are partially mixed prior to mixing with the surrounding ambient air 6 but emit from the confines of the flare enclosure or waste gas conduit with sufficient combined velocity and momentum to induce effective mixing of fuel and steam with the surrounding air to affect improved combustion and effectively complete destroying combustible waste gas. Relatively high velocity steam 2 transfers momentum to the relatively low velocity waste gas 1 and induces some mixing of steam and waste gas 5 before exiting into surrounding air 3. The resulting partially mixed steam and waste gas stream then imparts momentum, drawing in and mixing with, the surrounding ambient air 6 as the steam and waste gas emit from the flare enclosure conduits 7. In FIG. 1 are shown four sets of four enclosure conduits 7, conduit steam injection nozzles 8, rings 9, velocity seals 10, and hub steam injection nozzles 16. Also shown are transition plates 11, curved to allow for sufficient flow distribution into cans with minimal wind area and a hub expansion cylinder and plate 13 to mitigate growth from thermal stresses.

[0025] FIG. 2 is a view that includes the lower portion of the flare assembly with the cylinder 12 into which waste gas 1 passes and the pipe in which steam 2 is sent to the upper portion that contains the explained above. Hub steam injection nozzles 16 are shown, which result in steam separating the combusting waste gas stream mixture from the center hub metal.

[0026] FIG. 3 illustrates detail of several flare enclosure conduits. Steam 2 passes into flare conduits 7 and then into surrounding air 3 to be burned effectively. Rings 9 and velocity seals or flow-restricting cones 10 are shown in each enclosure conduit 7.

[0027] FIG. 4 is a view that shows more detail of two individual flare enclosure conduits 7 with steam 8 entering through a tube 14 that extends to near the top of the flare enclosure conduit while waste gas passes up to mix with the outside ambient air to then burn efficiently.

[0028] In other embodiments of the invention, there is a reliance on internally injected steam to keep the steam warm. This steam is injected wholly within the flare tip conduit enclosure and is sufficiently away from, upstream of, the exit to atmosphere opening of the flare tip that this steam completely mixes with the waste gas and imparts a small but largely insignificant momentum component to the waste gas stream and is sufficiently upstream of the flare exit as to impart no significant effect on enabling or enhancing the mixing of the resulting waste gas and steam mixture with the surrounding atmospheric air. This design relies on internal steam as injected through a conduit or venture drawing in surrounding air as described above. External steam is used in drawing in surrounding air from the periphery of the exiting waste gas stream and steam to keep warm is injected wholly within the flare waste stream conduit. In the depicted embodiment, t present invention relies on a new, separate and different mixing method of partially mixing steam with waste gas at a location where it can then mix with and impart momentum upon the surrounding atmospheric air.

[0029] The depicted embodiment shows twenty-four waste gas conduits 7, four on each of six transition sections, for a twenty-four inch riser cylinder 12. In another embodiment, the number and size of waste gas conduits and number and size of transition sections could vary more or less.

[0030] In one embodiment (pictured), the steam injection nozzle in located upstream of the plane at the exit of the waste gas conduit. In another embodiment (not pictured) the steam injection tip extends through and beyond the plane of at the exit of the waste gas conduit while remaining completely enveloped in the waste gas stream.

[0031] In the depicted embodiment, the waste gas tip has a ring 9 located near, but slightly upstream of the waste gas exit. This ring is not necessary, but can serve to 1) enhance the mixing of waste gas, steam and air, 2) stabilize or create as stable bluff body for flame stabilization and 3) serve as a fine tuning location whereby adjusting the size of the passage(s) in the ring the flow capacity of the flare can be adjusted to specifically meet the flow capacity requirements of a particular flaring application or operation. The benefits of adjusting the capacity of the flare to correctly match the flow and capacity requirements of a particular flaring application or operation include fuller utilization of the available pressure loss in the waste stream system thereby enhancing the mixing of the waste gas, steam and air. Improved or enhance mixing of waste gas, steam and air not only improves the combustion, thereby increasing the smokeless capacity of the flare burner but also further reduces the steam utilization of the flaring system to values of much less than 0.20 lbs steam is used per pound of propane waste gas approaching or less than 0.10 lbs steam used per pound of propane waste gas. This ring or rings can be located as depicted, upstream of the exit, at the exit or suspended on a structure and held downstream of the exit. These rings may also reside singularly or in plurality on the outside of the outside of the waste gas conduit. The depicted waste gas conduit 7 is cylindrical but in practice may be of various shapes including square, rectangular, oval or complex. Given the multiplicity of possible shapes, the ring(s) may be of various shapes and dimensions and may contain perforations or other surface features the may disrupt, guide or channel the flow of steam, waste gas or air to affect the mixing of the three component streams.

[0032] In the depicted embodiment, the waste gas tip has three velocity seals or flow-restricting cones 10 per waste stream conduit 7. These cones are not necessary but serve to 1) restrict air from flowing upstream into the flare transition or entry cylinder 12 under low-flow operating conditions, 2) maintain combustion in waste stream conduits 7, and 3) reduce combustion within the waste stream entry cylinder 12. Additionally, these cones can be increased or decreased in count per waste stream conduit or flow diverted from them as required.

[0033] Curved transition plate 11 is shown in the depicted embodiment, but this plate can be flat, sloped, or curved in a direction opposite to that depicted in the figure. The curved shape is utilized to optimize flow distribution while minimizing pressure drop. Hub cylinder and flat plate 13 are not required but as depicted are used to maximize equipment life. Other embodiments not depicted involve cone with flat plate or simple flat plate.

[0034] The entrance of steam 2 into mixing zone with waste gas stream 5 is depicted with nine orifices 15 at a forty degree angle from vertical. Other embodiments include more or less orifices down to a single orifice, ranging from an angle up to fifty degrees from vertical to directly vertical.

[0035] The depicted embodiment of FIGS. 1 to 4, displays hub steam injection nozzles which are not required but which lengthen the life of the equipment by separating the center hub metal from the combustion with cooling steam.

[0036] The present invention is also directed to providing a staged steam to the flare gas conduit. Accordingly, turning to FIGS. 5 and 6, a flare gas conduit with a staged steam injection is shown. The staged steam injection enables flare operators to effectively and efficiently fire their flares from light-off conditions to full hydraulic, rated, or regulated capacity on any effluent gas including unsaturated hydrocarbons without creating significant, reportable smoke while utilizing remarkably low steam rates (<0.09 kg (0.20 lb) steam/0.45 kg (1.0 lb) unsaturated hydrocarbon effluent) with relatively low-pressure steam (<689 kPa (100 psig)).

[0037] Some conventional steam flares operate at low, utility rates without smoking using steam to reduce smoke. However, these current designs have an upper limit of effluent flow rate, particularly when firing unsaturated hydrocarbons such as ethylene or propylene, where the steam injection is not enough to prevent smoking and at higher effluent flow rates the flare will smoke. This upper flow limit where smoke occurs is some fraction of full hydraulic, rated or regulated capacity. The upper flow limit where smoke occurs divided by the full hydraulic, rated or regulated capacity of a flare, expressed in percent, is defined as the Smokeless Capacity of a given flare design. It would be desirable to provide 100% smokeless flare design allowing operators to operate smokeless from light-off through utility rates and on up full emergency release rates without smoking while consuming minimal assist steam. The embodiments of the present invention depicted in FIGS. 5 and 6 are believed to provide this ability.

[0038] As shown in FIGS. 5 and 6, this embodiment is directed at a flare gas conduit 100 of a steam flare, such as the one depicted in FIGS. 1 to 4; however, the features of the embodiment of FIGS. 5 and 6 can be utilized in any steam-assisted flare burner. More specifically, there are several ways steam is injected into and around flares. The embodiment shown in FIGS. 5 and 6 depicted a form of internal steam injection or steam being injected inside of the flare conduit. It is also contemplated that the staged steam supply described herein could be utilized with external steam injection where the steam is injected outside of the flare conduit.

[0039] The flare gas conduit 100 is configured to receive a stream of waste gas 102 and to provide the waste gas 102 to a combustion zone 104 located above an end of the flare gas conduit 100. The use of the term above is in relation to the drawings and is not intending to be limited. A steam tube 106 is proximate to the flare gas conduit 100, and in the depicted embodiment, the steam tube 106 is within the flare gas conduit 100. Again, it is also contemplated that the steam tube 106 is located outside of the flare gas conduit 100.

[0040] The depicted steam tube 106 includes two or more steam tubes 106a, 106b. However, any number of steam tubes 106a, 106b . . . 106n can be included within the scope of the present embodiments.

[0041] In a preferred embodiment, the two stream tubes 106a, 106b are arranged in a concentric manner Thus, a first steam tube 106a is an outer tube and the second steam tube 106b is an inner tube. Again, this is merely preferred, and other configurations are contemplated.

[0042] Each steam tube 106a, 106b terminates in an end 108a, 108b having at least one orifice 110a, 110b. Preferably each steam tube 106a, 106b includes between one and twenty orifices 110a, 110b (or steam ports). The angles 1, 2 from the centerline of the orifices 110a, 110b. to the longitudinal axis A1-A1 of the flare gas conduit 100 can be between 0 to 90 degrees. Each of the steam tubes 106a, 106b is configured to receive a stream of steam 112a, 112b. The supply of steam 112a, 112b to each of the steam tubes 106a, 106b is independent. Accordingly, valves 114a, 114b can be used to control the flow of steam 112a, 112b into each of the steam tubes 106a, 106b so as to adjust a flow rate, a pressure, or both. Additionally, it is preferred, that at least one of the steam streams 112a, 112b has a greater pressure than the other for a given flow rate.

[0043] By using multiple steam tubes 106a, 106b that are independently controlled, the flare burner can utilize low pressure (i.e., between approximately 483 to 689 kPa (70 to 100 psig)) steam during normal operations or normal flow rates of waste gas 102 to provide 100% smokeless, operation, by providing, for example steam 112a from the first steam tube 106a. At higher than normal flow rates of the waste gas 102, the flare burner can use the higher pressure (i.e., greater than 689 kPa (100 psig)) steam, for example, steam 112b from the second steam tube 106b. Through this staging mechanism, the pressure of steam in the combustion zone 104 can be maintained at sufficient levels to achieve low steam utilization at the desired operation flow rates for both low and higher firing rates across and through the full operating range of the flare burner

[0044] It is also contemplated the steam flow is controlled automatically. Accordingly, a flow rate sensor 116 in the line for the waste gas 102 may be in communication with a controller 118 that includes at least one processor and memory storing computer-readable instructions that, when executed by the at least one processor, cause the controller 118 to perform a process that may include one or more steps. The controller 118 may be an Application Specific Integrated Circuit (ASIC), an electronic circuit, memory (shared, dedicated, or group) and/or a computer processor (shared, dedicated, or group) that executes one or more executable instructions (e.g., software or firmware programs) stored on the memory, a combinational logic circuit, and/or other suitable components that provide the described functionality. While this disclosure includes particular examples and arrangements of the units, the scope of the present system is not so limited, since other modifications will become apparent to the skilled practitioner. Some or all relevant information may be stored in databases for retrieval by the controller 118 (e.g., as a data storage device and/or one or more non-transitory machine-readable data-storage media storing executable instructions). The controller 118 is further configured to obtain, receive, and/or send information over a communication network (e.g., local communication network, the internet, an intranet). Specifically, the controller 118 may receive signals and/or parameters via the communication network. The controller 118 may display (e.g., in real time, with a short delay, with a long delay) performance information related to the received signals and/or parameters on an interactive display device (i.e., display screen), which may be accessible to an operator or user, either locally or over a communication network like the internet. Additionally, the controller 118 is configured to receive input, via, a keyboard, touch screen, mouse, or other device.

[0045] Accordingly, the controller 118 may receive signals relating to the flow of waste gas 102 and compare that against, for example, one or more predetermined levels or an acceptable range. If it is determined that the flow rate of the waste gas 102 is above the predetermined level, or outside of the acceptable range the controller 118 may provide signals so that the steam level changes. Accordingly, the controller 118 may also be in communication with, for example, the valves 114a, 114b so that the controller 118 can adjust the flow rate, pressure, or both of steam 112a, 112b.

[0046] It should be appreciated that the flow rate sensor 116 is merely exemplary, and other components could be used to provide signals to controller 118 for determining whether or not to adjust the flow rate, pressure, or both of steam 112a, 112b. For example, thermocouples or temperature sensors could be used. Alternatively, a camera (not shown) could be used to provide images that can be analyzed to determine the presence of smoke, and thus the controller could adjust the flow rate, pressure, or both steam 112a, 112b in response to a determination that there is smoke.

[0047] Any of the above lines, conduits, units, devices, vessels, surrounding environments, zones or similar may be equipped with one or more monitoring components including sensors, measurement devices, data capture devices or data transmission devices. Signals, process or status measurements, and data from monitoring components may be used to monitor conditions in, around, and on process equipment. Signals, measurements, and/or data generated or recorded by monitoring components may be collected, processed, and/or transmitted through one or more networks or connections that may be private or public, general or specific, direct or indirect, wired or wireless, encrypted or not encrypted, and/or combination(s) thereof; the specification is not intended to be limiting in this respect.

[0048] Signals, measurements, and/or data generated or recorded by monitoring components may be transmitted to one or more computing devices or systems. Computing devices or systems, such as the controller 118, may include at least one processor and memory storing computer-readable instructions that, when executed by the at least one processor, cause the one or more computing devices to perform a process that may include one or more steps. For example, the one or more computing devices may be configured to receive, from one or more monitoring component, data related to at least one piece of equipment associated with the process. The one or more computing devices or systems may be configured to analyze the data. Based on analyzing the data, the one or more computing devices or systems may be configured to determine one or more recommended adjustments to one or more parameters of one or more processes described herein. The one or more computing devices or systems may be configured to transmit encrypted or unencrypted data that includes the one or more recommended adjustments to the one or more parameters of the one or more processes described herein.

SPECIFIC EMBODIMENTS

[0049] While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[0050] A first embodiment of the invention is a steam flare comprising a waste gas cylinder connected at an upper portion of the waste as cylinder to a plurality of extensions that extend away from a center of the waste gas cylinder, wherein each of the extensions contain a plurality of flare gas conduits, and wherein a steam tube is located in each of the flare gas conduits. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare further comprises a ring at a top portion of the flare gas conduit and above a top portion of the steam tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the flare gas conduit is a tube having a cylindrical configuration. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the flare gas conduit is a tube having a square, rectangular, oval or complex configuration. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam tube comprises a single tube having branches that extend into each of the flare gas conduits. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the ring contains perforations or other surface features. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare further comprises a multiplicity of flow-reducing cones in the flare gas conduit and below a top portion of the steam tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare further comprises a singular flow-reducing cone in each of the flare gas conduits and below a top portion of the steam tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the stream flare comprises a curved transition piece from waste gas cylinder to flare gas conduits. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare comprises a straight transition piece from waste gas cylinder to flare gas conduits. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare has a sloped transition piece from waste gas cylinder to flare gas conduits. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein there is a flat plate capping the waste gas cylinder. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein there is a cone and a flat plate capping the waste gas cylinder. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare has a cylinder and a flat plate capping the larger concentric waste gas cylinder. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare has a steam tube with a singular orifice pointing vertical. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare has a team tube with two to twenty orifices, pointing at an angle between zero and fifty degrees from vertical. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the steam flare has external steam tubes injecting steam between hub metal and combusting stream.

[0051] A second embodiment of the invention is a process of operating a steam flare comprising sending a waste gas stream through a waste gas cylinder to a plurality of flare gas conduits while sending a stream of steam through a tube wherein the tube extends into the flare gas conduit, mixing the waste gas stream and the steam and then causing a flame to burn as a resulting mixture of the waste gas stream, the steam and oxygen in outside ambient air. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein a ring at an upper portion on a waste gas tip of the flare gas conduit comprises perforations or other surface features to direct mixture of the steam and the waste gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the flare gas conduit has a configuration selected from the group consisting of cylindrical, square, rectangular, oval and complex shapes. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein less than 0.09 kg (0.20 lbs) steam is used per pound of propane waste gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein a ring at the upper portion of the waste gas tip of the flare gas conduit comprises perforation or other surface features properly sized in proportion to the waste gas stream and thereby values approaching or less than 0.05 kg (0.10 lbs) steam is used per pound of propane waste gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein all of the steam is injected internally to the waste gas before exposure to surrounding atmospheric air. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein most of the steam is injected internally to waste gas before exposure to surrounding atmospheric air and some of the steam is injected externally to separate combusting stream from hub metal. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the steam imparts mixing and momentum transfer to the waste gas and the surrounding atmospheric air. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein a singularity or multiplicity of flow-reducing cones in the flare gas conduit reduce the amount of air flowing upstream into the flare gas conduit. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein reduced steam and/or assist gas is required to maintain smokeless operation under low-flow operating conditions. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein curved transition pieces between flare gas cylinder and the waste gas conduits improve flow distribution exiting the waste gas conduits and reduce pressure drop through flare gas system. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein a singular vertical orifice or multiple orifices at an angle are utilized to increase mixing of the steam, surrounding atmospheric air, and waste gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the orifices increase the velocity of the waste gas stream while reducing the level of atmospheric air backflow at low flow rates through partial steam-capping of the flare gas conduit.

[0052] A third embodiment of the invention is a steam flare comprising a flare gas conduit configured to receive waste gas and provide the waste gas to a combustion zone, and a steam tube located in the flare gas conduit, wherein the steam tube comprises an outer tube and an inner tube inside of the outer tube, both of the outer tube and the inner tube having at least one orifice configured to provide steam into the flare gas conduit. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the outer tube is in communication with a supply of steam having a first steam flow rate and a first pressure. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the inner tube is in communication with a supply of steam having a second steam flow rate and a second pressure, the second steam flow rate, the second pressure, or both being different, respectively, from the first steam flow rate and the first pressure. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the second pressure is lower than the first pressure for a given rate of steam flow to either the outer tube or the inner tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the second pressure is higher than the first pressure for a given rate of steam flow to either the outer tube or the inner tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein a steam supply through the inner tube is independent of a steam supply of the outer tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising a sensor; a flow regulating device configured to regulate a steam flow, a pressure, or both associated with steam provided by one of the inner tube and the outer tube; a controller in communication with the sensor and the flow regulation device and being configured to increase or decrease the steam flow, the pressure, or both based on a signal from the sensor.

[0053] A fourth embodiment of the invention is a steam flare comprising a flare gas conduit in communication with a source of flare gas; and, a steam tube located proximate the flare gas conduit so that steam from the steam tube is directed into a flame from combustion of the flare gas, wherein the steam tube comprises a plurality of tubes each having at least one orifice and a first tube from the plurality being configured to provide steam independent of steam provided from a second tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fourth embodiment in this paragraph, wherein the first tube is concentric with the second tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fourth embodiment in this paragraph, wherein the steam tube is disposed within the flare gas conduit. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fourth embodiment in this paragraph, wherein the first tube is in communication with steam having a first steam flow rate and a first pressure. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fourth embodiment in this paragraph, wherein the second tube is in communication with steam having a second steam flow rate and a second pressure, the second steam flow rate, the second pressure, or both being different, respectively, from the first pressure and the first steam flow rate. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fourth embodiment in this paragraph further comprising a sensor; a flow regulating device configured to regulate a steam flow, a pressure, or both associated with steam provided by one of the first tube and the second tube; a controller in communication with the sensor and the flow regulation device and being configured to increase or decrease the steam flow, the pressure, or both based on a signal from the sensor.

[0054] A fifth embodiment of the invention is a process of operating a steam flare comprising sending a waste gas stream through a flare gas conduit at a first flare gas flow rate while providing a steam through a first steam tube in communication with a supply of steam having a first steam flow rate and a first pressure, wherein the first steam tube is proximate the flare gas conduit so that steam from the first steam tube mixes with waste gas from the waste gas stream; causing a flame to burn as a resulting mixture of the waste gas stream, the steam, and oxygen in outside ambient air; and, sending a second stream of steam through a second steam tube, wherein the second steam tube is in communication with a supply of stream having a second steam flow rate and a second pressure, and wherein the second pressure is greater than the first pressure for a given steam flow rate. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fifth embodiment in this paragraph further comprising monitoring the first flare gas flow rate of the waste gas stream; and when, the first flare gas flow rate exceeds a predetermined level, adjusting a flow rate of the second stream of steam. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fifth embodiment in this paragraph, wherein the first steam tube is concentric with the second steam gas tube. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the fifth embodiment in this paragraph, wherein the first steam tube and the second steam tube are located within the flare gas conduit.

[0055] Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of this invention, without departing from the spirit and scope thereof, to make various changes and modifications of the invention and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0056] In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.