Staged gas injection system

Abstract

This invention provides a staged gas injection system for a flare head that can discharge exhaust gases into a combustion zone. The staged gas injection system includes, for example, a first gas injection assembly and a second gas injection assembly. The first gas injection assembly is configured to inject gas (e.g., steam or a gas other than steam) into the flare head or combustion zone at a high flow rate and high pressure. The second gas injection assembly is configured to inject gas (e.g., steam and / or a gas other than steam) into the flare head or combustion zone at a low flow rate and high pressure. This invention also provides a flare head including the staged gas injection system.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 066,494, filed October 9, 2020, which is incorporated herein by reference. Technical Field

[0003] This invention relates to a staged gas injection system for a torch head. Background Technology

[0004] Industrial flares used for burning and handling flammable gases are well-known. Such flares typically consist of one or more flare heads mounted on a flare tower. The flare head initiates combustion of the gases and releases the combustion products into the atmosphere. Flares are located at production, refining, or processing facilities. In many cases, a single facility includes more than one flare.

[0005] For example, industrial flares are used to treat flammable gases, exhaust gases, and other types of gases (collectively referred to as "exhaust gases") that require treatment. Industrial flares are used to safely combust flammable gas flows that are transferred and released due to system venting, equipment shutdowns and malfunctions, and equipment emergencies (including fires and power outages). A properly operated flare system can be a critical component in preventing equipment damage and destruction.

[0006] Industrial flares are expected and typically required to operate in a relatively smokeless manner. For example, smokeless operation can often be achieved by ensuring that exhaust gases are mixed with a sufficient amount of air for a relatively short period to adequately oxidize the soot particles formed in the flame. In applications with lower pressures, the momentum of the exhaust gas flow alone may not be sufficient to provide smokeless operation. In such cases, auxiliary media such as steam and / or air can be used to provide the necessary power to entrain ambient air from around the flare unit. Many factors must be considered when selecting a smoke-suppressing auxiliary medium, including local energy costs and availability.

[0007] The most common auxiliary medium used to add momentum to low-pressure gases is steam. Steam is typically injected through one or more sets of nozzles associated with the flare head. In addition to adding momentum and entraining air, steam can dilute the gas and participate in the chemical reactions involved in combustion, both of which help suppress smoke. In an example of a simple steam-assisted system, several steam injectors extend from a steam manifold or ring installed near the flare head outlet. The steam injectors direct steam jets into the combustion zone adjacent to the flare head. One or more valves (e.g., those that can be remotely controlled by an operator or automatically controlled based on changing operating parameters) are used to regulate the steam flow to the flare head. The steam jet draws air from the surrounding atmosphere into the exhaust gas, which has a high level of turbulence. This prevents wind from blowing the flame from the combustion zone into and around the flare head. The injected steam, the introduced air, and the exhaust gas combine to form a mixture that helps the exhaust gas burn without producing visible smoke.

[0008] A steam injection system for injecting steam into the exhaust gas stream requires control valves, piping to deliver steam to the flare head, steam injection nozzles, and distribution piping to deliver steam to the steam injection nozzles. Some flares include multiple steam lines with multiple sets of steam injection nozzles for discharging steam to different locations associated with the flare head.

[0009] Steam injection systems can encounter various problems. For example, a steam injection system uses the momentum of steam to entrain and mix air with the exhaust gas for smokeless combustion. For instance, at the design flow rate, steam is discharged from the steam nozzle at the speed of sound (Mach = 1 or greater). As the steam flow rate decreases, the steam pressure at the nozzle decreases, and eventually the flow rate decreases low enough that the steam discharge velocity is less than the speed of sound. As the steam velocity decreases, the efficiency with which the steam entrains and mixes with the exhaust gas decreases. For example, at the design flow rate, a flare head may require 0.3 pounds of steam per pound of exhaust gas to achieve smokeless combustion. Under reduced conditions (e.g., lower steam injection pressure), the same flare head and the same exhaust gas (in terms of composition) may require 1.2 pounds or more of steam per pound of exhaust gas to achieve smokeless combustion. This increases the operating costs of the flare.

[0010] Additionally, when the flare head operates at low exhaust gas flow rates, air and exhaust gas can mix within the flare head. This is typically due to the exhaust gas being less dense than the surrounding air and wind blowing air into the flare head. When air and exhaust gas mix, combustion may occur. When combustion occurs within the flare head, the internal tubes will experience a temperature rise. If the tubes become too hot, material degradation and deformation will occur, shortening the flare head's lifespan.

[0011] To prevent such damage to the flare head, manufacturers recommend continuously injecting steam into or around the flare head at a minimum flow rate (often referred to as the minimum steam rate), depending on the nature of the steam injection assembly. Continuously injecting steam at the minimum steam rate helps keep the temperature of the internal metal tubing and other equipment below the point where drastic degradation would occur. For example, the minimum steam rate allows sufficient steam and airflow through the internal tubing to transfer enough heat from it, thus keeping the tubing temperature within acceptable limits.

[0012] Newly issued U.S. government regulations may change how operators control flares. In the future, operators may have to consider the calorific value of exhaust gases, as well as the amount of steam delivered to the flare, in accordance with current regulations. This could pose challenges when the flare is operating under downscaling conditions. For example, operators may need to use make-up gases (e.g., natural gas) to enrich the exhaust gases to maintain a net calorific value in the combustion zone of 270 btu / scf or higher. Depending at least in part on the cost of the make-up gas, such requirements could cost operators hundreds of thousands to millions of dollars annually.

[0013] One way to reduce the amount of make-up gas required is to lower the minimum steam consumption rate. However, a lower minimum steam consumption rate may shorten the flare's lifespan, thus requiring more frequent shutdowns and increasing associated costs. A potential related problem is water hammer. If insufficient steam is supplied to keep the steam lines warm and cool, introducing steam into the cold lines can lead to knocking or water hammer problems.

[0014] In some cases, multi-emission flares are used where the exhaust gas is lighter than air. When this type of exhaust gas is emitted at a low flow rate, it may preferentially flow through only a few internal tubular modules. If this occurs, air can flow down the internal tubular modules that do not receive exhaust gas. The fuel-air mixture then follows, and may eventually return to the flare head, stabilizing the flame within it. The steam flow at the minimum steam consumption rate can provide sufficient momentum to limit the amount of air that can flow into the flare head and solve this problem. Summary of the Invention

[0015] This disclosure provides a staged gas injection system for a flare head that can discharge exhaust gases into a combustion zone. A flare head that can discharge exhaust gases into a combustion zone is also provided.

[0016] In one embodiment, the staged gas injection system provided by this disclosure is used for a flare head that can discharge exhaust gas into a combustion zone and includes an inner tubular member disposed within an outer tubular member. In this embodiment, the staged gas injection system includes a first gas injection assembly and a second gas injection assembly. The first gas injection assembly is configured to inject gas into the inner tubular member of the flare head at a high flow rate and high pressure, and includes a first-stage gas source and a first gas injection nozzle fluidly connected to the first-stage gas source. The first-stage gas source may be a steam source and / or an alternative gas source. The second gas injection assembly is configured to inject gas into the inner tubular member of the flare head at a low flow rate and high pressure, and includes a second-stage gas source and a second gas injection nozzle fluidly connected to the second-stage gas source. The first and second gas injection assemblies are close to each other and oriented in the same direction, such that both the first and second gas injection assemblies inject gas into the inner tubular member of the flare head.

[0017] In another embodiment, the staged gas injection system provided by this disclosure is used for a flare head that can discharge exhaust gas into a combustion zone. In this embodiment, the staged gas injection system includes a first gas injection assembly and a second gas injection assembly. The first gas injection assembly is configured to inject gas into the combustion zone at a high flow rate and high pressure, and includes a first-stage gas source and a first gas injection nozzle fluidly connected to the first-stage gas source. The first-stage gas source is a steam source and / or a substitute gas source. The second gas injection assembly is configured to inject gas into the combustion zone at a low flow rate and high pressure, and includes a second-stage gas source and a second gas injection nozzle fluidly connected to the second-stage gas source. The first and second gas injection assemblies are close to each other and oriented in the same direction, such that both the first and second gas injection assemblies inject gas into the combustion zone.

[0018] In one embodiment, the flare head provided by this disclosure can discharge exhaust gas into a combustion zone and includes an inner tubular member disposed within an outer tubular member and a staged gas injection system. In this embodiment of the flare head, the staged gas injection system includes a first gas injection assembly and a second gas injection assembly. The first gas injection assembly is configured to inject gas into the inner tubular member of the flare head at a high flow rate and high pressure, and includes a first-stage gas source and a first gas injection nozzle fluidly connected to the first-stage gas source. The first-stage gas source is a vapor source and / or a substitute gas source. The second gas injection assembly is configured to inject gas into the inner tubular member of the flare head at a low flow rate and high pressure, and includes a second-stage gas source and a second gas injection nozzle fluidly connected to the second-stage gas source. The first and second gas injection assemblies are close to each other and oriented in the same direction, such that both the first and second gas injection assemblies inject gas into the inner tubular member of the flare head.

[0019] In another embodiment, the flare head provided by this disclosure can discharge exhaust gas into a combustion zone and includes a staged gas injection system. In this embodiment of the flare head, the staged gas injection system includes a first gas injection assembly and a second gas injection assembly. The first gas injection assembly is configured to inject gas into the combustion zone at a high flow rate and high pressure, and includes a first-stage gas source and a first gas injection nozzle fluidly connected to the first-stage gas source. The first-stage gas source is a steam source and / or a substitute gas source. The second gas injection assembly is configured to inject gas into the combustion zone at a low flow rate and high pressure, and includes a second-stage gas source and a second gas injection nozzle fluidly connected to the second-stage gas source. The first and second gas injection assemblies are close to each other and oriented in the same direction, such that both the first and second gas injection assemblies inject gas into the combustion zone. Attached Figure Description

[0020] The accompanying drawings included in this application illustrate certain aspects of the embodiments described herein. However, the drawings should not be considered as exclusive embodiments. The disclosed subject matter is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art who benefit from this disclosure.

[0021] Figure 1A This is a cross-sectional view of one embodiment of the staged gas injection system disclosed herein.

[0022] Figure 1B This is a cross-sectional view of another embodiment of the staged gas injection system disclosed herein.

[0023] Figure 2A It shows different torch configurations. Figure 1A The diagram shows a cross-sectional view of a staged gas injection system.

[0024] Figure 2B It shows different torch configurations. Figure 1B The diagram shows a cross-sectional view of a staged gas injection system.

[0025] Figure 3A yes Figure 1A A cross-sectional view of an additional embodiment of the staged gas injection system shown.

[0026] Figure 3B yes Figure 1B A cross-sectional view of an additional embodiment of the staged gas injection system shown.

[0027] Figure 4A yes Figure 1A A cross-sectional view of an additional embodiment of the staged gas injection system shown.

[0028] Figure 4B yes Figure 1B A cross-sectional view of an additional embodiment of the staged gas injection system shown.

[0029] Figure 5 This is a side view of the implementation scheme of the staged gas injection system disclosed in this article.

[0030] Figure 6 yes Figure 5 A top view of an embodiment of the staged gas injection system shown.

[0031] Figure 7 This is a side view of one embodiment of the gas injection nozzle disclosed herein.

[0032] Figure 8 yes Figure 7 The top view of the gas injection nozzle is shown.

[0033] Figure 9 This is a cross-sectional view of the implementation scheme of the three-stage gas injection system disclosed in this article.

[0034] Figure 10 This is a side view of another embodiment of the three-stage gas injection system disclosed in this article.

[0035] Figure 11 yes Figure 10 Top view of the gas injection assembly shown.

[0036] Figure 12 It shows Figure 10 and Figure 11 The cross-sectional view shown is of a staged gas injection assembly, such as the internal tubular component for a single torch head.

[0037] Figure 13 It is a graph that compares the normalized steam / hydrocarbon ratio (lb / lb) with the normalized flare fuel ratio (lb / hr) corresponding to a high-flow-rate, high-pressure steam nozzle with the normalized steam / hydrocarbon ratio (lb / lb) with the normalized flare fuel ratio (lb / hr) corresponding to a low-flow-rate, high-pressure steam nozzle.

[0038] Figure 14 This is a graph comparing the air entrainment performance using steam and air as the first-stage gas source. Detailed Implementation

[0039] This disclosure can be more readily understood by referring to this specific embodiment. For simplicity and clarity, reference numerals may be repeated in different figures where appropriate to indicate corresponding or similar elements. Furthermore, numerous specific details are set forth to provide a thorough understanding of the various embodiments described herein. However, those skilled in the art will understand that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail to avoid obscuring the relevant features described. Moreover, this description should not be considered as limiting the scope of the embodiments described herein. The figures are not necessarily drawn to scale, and some portions have been enlarged to better illustrate the details and features of this disclosure.

[0040] This disclosure provides a staged gas injection system and a flare head including the staged gas injection system.

[0041] It has been found that the aforementioned problems can be solved by providing a staged gas injection system capable of discharging steam, substitute gas, or steam and substitute gas into a flare device at various stages (i.e., at various flow rates and pressures). For example, the staged gas injection system disclosed herein can be a two-stage system comprising two gas injection nozzles, one nozzle for injecting steam and / or substitute gas into the flare head at a high flow rate and high pressure (e.g., as in a conventional standard steam injection system), and the other nozzle for injecting steam and / or substitute gas into the flare head at a low flow rate and high pressure at the same location. As another example, the staged gas injection system can be a three-stage system comprising three gas injection nozzles, one nozzle for injecting steam and / or substitute gas into the flare head at a high flow rate and high pressure (e.g., as in a conventional standard steam injection system), another nozzle for injecting steam and / or substitute gas into the flare head at a low flow rate and high pressure at the same location, and the remaining nozzle for injecting steam and / or substitute gas into the flare head at an even lower flow rate and high pressure at the same location. The number of stages that can be used is not limited. For example, four or five gas injection nozzles may also be used, each with the capability to discharge steam and / or alternative gas into the flare unit at different flow rates and pressures. The number of stages to be used in a given application depends on, for example, the type of flare unit, the location of the staged gas injection system relative to the flare head, and other factors known to those skilled in the art who benefit from this disclosure.

[0042] The staged gas injection system disclosed herein allows gas-assisted flares to operate with reduced steam and / or other auxiliary gases at reduced exhaust gas flow rates. For example, the staged gas injection system disclosed herein provides the momentum required to effectively entrain and mix air with exhaust gas under downgraded conditions. Additionally, when steam is used as at least one staged gas, this system provides the ability to maintain the temperature in the steam line at acceptable levels. The system uses less steam under downgraded conditions without affecting the flare head's lifespan.

[0043] As used herein and in the appended claims, “exhaust gas” means exhaust gas, flammable gas, equipment gas, and any other type of gas that can be processed by an industrial flare. Alternative gas refers to a gas other than steam. Examples of alternative gases that may be used include air, nitrogen, equipment gas, natural gas, and mixtures thereof. As described above, alternative gas may be emitted by a staged gas injection system through one or more gas injection nozzles that inject the gas into the flare head at a relatively low flow rate (compared to the relatively high flow rate associated with, for example, a conventional standard steam injection system). Whether alternative gas is used and the specific alternative gas (or gases) used will depend, for example, on the desired flame profile and characteristics. When the same type of gas is used in combination with more than one gas injection nozzle, the corresponding gas source can be the same. For example, in a two-stage system using only steam in each stage, the first-stage gas source and the second-stage gas source can be the same gas source, i.e., a steam source.

[0044] The staged gas injection system disclosed herein, generally denoted by reference numeral 40, will now be described with reference to the accompanying drawings. For example, Figure 1A , Figure 2A , Figure 3A and Figure 4A An embodiment of a staged gas injection system 40 comprising two separate gas injection components is shown, as well as its use in combination with four different torch head configurations. Figure 1B , Figure 2B , Figure 3B and Figure 4B An embodiment of a staged gas injection system 40, comprising two separate gas injection components partially combined into a single unit, is shown, as with... Figure 1A , Figure 2A and 4A The four different torch head configurations shown are used in combination. Figure 5 and Figure 6 Showing more details Figure 1B , Figure 2B , Figure 3B and Figure 4B The two-stage gas injection assembly is shown. Figure 7 and Figure 8Another embodiment of the two-stage gas injection assembly that can be used in this paper is shown. Figure 9 An embodiment of a staged gas injection system 40 comprising three separate gas injection assemblies is shown, as with... Figure 1A and Figure 1B The torch head configuration shown is used in combination. Figure 10 and Figure 11 An embodiment of a staged gas injection system 40 is shown, in which three separate gas injection components are combined into a single unit. Figure 12 It shows Figure 10 and Figure 11 The three-stage gas injection assembly shown is, as with Figure 1A and Figure 1B The torch head configuration shown is used in combination. Figure 13 The results achieved by testing the staged gas injection system disclosed herein are shown.

[0045] As used herein and in the appended claims, injecting steam and / or alternative gas at “high flow rate and high pressure” means, based on each nozzle, injecting steam from the corresponding gas injection nozzle at a flow rate (flow capacity) of at least 2000 lb / hr and a pressure of at least 50 psig. As used herein and in the appended claims, injecting steam and / or alternative gas at “low flow rate and high pressure” means, based on each nozzle, injecting steam and / or other gas from the corresponding gas injection nozzle at a flow rate (flow capacity) of half or less than that of the corresponding gas injection nozzle used for the next larger stage, and a pressure of at least 50 psig. For example, in a two-stage system, injecting steam and / or alternative gas at “low flow rate and high pressure” in the second stage means, based on each nozzle, injecting steam and / or alternative gas from the corresponding gas injection nozzle at a flow rate (flow capacity) of half or less than that of the corresponding high flow / high pressure nozzle, and a pressure of at least 50 psig. For example, in a three-stage system, injecting steam and / or substitute gas at “low flow and high pressure” in the third stage means, on a per-nozzle basis, injecting steam and / or substitute gas from the corresponding gas injection nozzle at a flow rate (flow capacity) of half or less than that used for the second stage and at a pressure of at least 50 psig. For example, reducing the nozzle flow rate (flow capacity) in the second and subsequent stages (if used) to half or less of that used for the next larger stage can be achieved by using nozzles, each including one or more exhaust ports, whose total exhaust area is half or less of the total exhaust area of ​​one or more exhaust ports for each nozzle used for the next larger stage.

[0046] The pressure at which steam and / or other gases are injected from the gas injection nozzles used for each stage can also vary with the stage. For example, the pressure used can vary from 5 psig to 300 psig, including 60 psig, 90 psig, 100 psig, 120 psig, 150 psig, 180 psig, 210 psig, 240 psig, and 270 psig. Suitable pressure ranges may include 5 psig to 200 psig, 5 psig to 100 psig, 20 psig to 300 psig, 20 psig to 200 psig, 20 psig to 100 psig, 40 psig to 300 psig, 40 psig to 200 psig, 40 psig to 100 psig, 60 psig to 300 psig, 60 psig to 200 psig, and 60 psig to 100 psig. The gas injection assembly and corresponding nozzles can utilize available steam in production, refining, or processing equipment where the flare assembly is installed.

[0047] The staged gas injection system 40 is used in conjunction with a flare assembly (not fully shown). The flare assembly includes a flare riser (not shown) for directing the exhaust gas flow to the flare head 10. The flare head 10 is attached to the flare riser and is configured to discharge the exhaust gas flow into a combustion zone 70 in the atmospheric environment adjacent to the flare head.

[0048] For example, in Figure 1A , Figure 1B , Figure 9 and Figure 12 In the illustrated configuration, the flare head 10 includes an outer tubular member 12, an inner tubular member 14, and a premixing zone 16. The outer tubular member 12 includes an inlet 18, an outlet 20, and a gas passage 22. The inner tubular member 14 includes an inlet 24, an outlet 26, and a gas passage 28. The inner tubular member 14 is coaxially disposed within the outer tubular member 12. For example, exhaust gas enters the gas passage 22 through the inlet 18 of the outer tubular member 12, enters the premixing zone 16, and enters the combustion zone 70 through the outlet 20 of the outer tubular member. The premixing zone 16 is located between the outlet 26 of the inner tubular member 14 and the outlet 20 of the outer tubular member 12. In the premixing zone 16, vapors and / or substitute gases discharged through the outlet 26 of the inner tubular member 14 mix with the exhaust gas and are discharged into the combustion zone 70 through the outlet 20 of the outer tubular member 12. Discharging the exhaust gas mixture from the premixing zone 16 into the combustion zone 70 entrains additional air into the exhaust gas. As those skilled in the art who benefit from this disclosure will understand, experimental components (not shown) may also be associated with the torch head 10 to ignite the exhaust gas / air mixture in the combustion zone 70.

[0049] For example, in Figure 2A and Figure 2BIn the configuration shown, the torch head 10 includes an outer tubular member 12, two inner tubular members 14, and a premixing zone 16. The outer tubular member 12 includes an inlet (not shown), an outlet 20, and a gas passage 22. Each of the inner tubular members 14 includes an inlet 24, an outlet 26, and a gas passage 28. The inner tubular members 14 are disposed within the outer tubular member 12. For example, although... Figure 2A and Figure 2B Two internal tubular components 14 are shown, but more than two (e.g., four or six) internal tubular components 14 may be positioned within the external tubular component 12. For example, exhaust gas enters gas passage 22 through the inlet of the external tubular component 12 (not shown), enters premixing zone 16, and enters combustion zone 70 through the outlet 20 of the external tubular component. The premixing zone 16 is located between the outlet 26 of the internal tubular component 14 and the outlet 20 of the external tubular component 12. In the premixing zone 16, vapors and / or substitute gases discharged through the outlet 26 of the internal tubular component 14 are mixed with the exhaust gas and discharged into combustion zone 70 through the outlet 20 of the external tubular component 12. Discharging the exhaust gas mixture from the premixing zone 16 into combustion zone 70 entrains additional air into the exhaust gas. As those skilled in the art who benefit from this disclosure will understand, experimental components (not shown) may also be associated with the torch head 10 to ignite the exhaust gas / air mixture in combustion zone 70.

[0050] For example, in Figure 3A and Figure 3B In the configuration shown, the torch head 10 includes an outer tubular member 12 and two inner tubular members 14. The outer tubular member 12 includes an inlet (not shown), an outlet 20, and a gas passage 22. Each of the inner tubular members 14 includes an inlet (not shown), an outlet 26, and a gas passage 28. The inner tubular members 14 are disposed within the outer tubular member 12. For example, although... Figure 3A and Figure 3B Two internal tubular components 14 are shown, but more than two (e.g., four or six) internal tubular components 14 may be positioned within the external tubular component 12. For example, exhaust gas enters gas passage 22 through the inlet of the external tubular component 12 and enters combustion zone 70 through the outlet 20 of the external tubular component. Grade gas (vapor and / or substitute gas) enters combustion zone 70 through the internal tubular component 14, through its outlet 26. Discharging the exhaust gas and grade gas mixture into combustion zone 70 will entrain additional air into the exhaust gas. As those skilled in the art who benefit from this disclosure will understand, experimental components (not shown) may also be associated with torch head 10 to ignite the exhaust gas / air mixture in combustion zone 70.

[0051] For example, in Figure 4A and Figure 4BIn the configuration shown, the flare head 10 includes two outer tubular members 12, two inner tubular members 14, and two premixing zones 16. Each outer tubular member 12 includes an inlet 18, an outlet 20, and a gas passage 22. Each inner tubular member 14 includes an inlet 24, an outlet 26, and a gas passage 28. The inner tubular members 14 are disposed within the outer tubular members 12. An exhaust manifold 30, having an inlet 32, an outlet 34, and a gas passage 36, surrounds the outer tubular members 12. For example, exhaust gas enters the gas passage 36 of the exhaust manifold 30 through the inlet 32, enters the inlet 18 of the outer tubular member 12 through the outlet 34 of the exhaust manifold, enters the gas passage 22, enters the premixing zone 16, and enters the combustion zone 70 through the outlet 20 of the outer tubular member (in this flare head configuration, two separate combustion zones can be formed). The premixing zone 16 is located between the outlet 26 of the inner tubular member 14 and the outlet 20 of the outer tubular member 12. In the premixing zone 16, vapors and / or substitute gases discharged through outlet 26 of the internal tubular member 14 are mixed with exhaust gases and discharged through outlet 20 of the external tubular member 12 into one or more combustion zones 70. Discharging the exhaust gas mixture from the premixing zone 16 into one or more combustion zones 70 will entrain additional air into the exhaust gases. As those skilled in the art who benefit from this disclosure will understand, one or more experimental components (not shown) may also be associated with the torch head 10 to ignite the exhaust gas / air mixture in one or more combustion zones 70.

[0052] Now for specific reference Figure 1A , Figure 2A , Figure 3A and Figure 4A An embodiment of the staged gas injection system 40 disclosed herein will be described in more detail. Figure 2A , Figure 3A and Figure 4A In this embodiment, a two-stage gas injection system 40 is used (each of these embodiments). In this embodiment, the staged gas injection system 40 includes a first gas injection assembly 50 and a second gas injection assembly 60 that are close to each other and oriented in the same direction, such that both gas injection assemblies inject vapor and / or alternative gas into the torch head 10 (e.g., Figure 1A , Figure 2A and Figure 4A (as shown) or combustion zone 70 (as shown) Figure 3AAs used herein and in the appended claims, the statement that the first gas injection assembly 50 and the second gas injection assembly 60 are close to each other and oriented in the same direction such that both gas injection assemblies inject vapor (and / or, in the case of assembly 60, a substitute gas) into the torch head 10 or the combustion zone 70 means that at least a portion of each gas injection assembly (e.g., a gas injection nozzle) is close to each other and oriented in the same direction such that both gas injection assemblies inject vapor and / or a substitute gas into the torch head 10 or the combustion zone 70. For example, the gas sources of the assemblies are not necessarily oriented in the same direction.

[0053] The first gas injection assembly 50 is configured to inject steam and / or substitute gas into the torch head 10 at high flow rate and high pressure (e.g., ...). Figure 1A , Figure 2A and Figure 4A (as shown) or combustion zone 70 (as shown) Figure 3A As shown in the diagram, the first gas injection assembly 50 includes a first-stage gas source 52 and a gas injection nozzle 54 fluidly connected to the first-stage gas source. The first-stage gas source 52 is a vapor source and / or an alternative gas source that supplies this first-stage gas to the gas injection nozzle 54.

[0054] The second gas injection assembly 60 is configured to inject gas (vapor and / or substitute gas) into the torch head 10 at a low flow rate and high pressure (e.g., Figure 1A , Figure 2A and Figure 4A (as shown) or combustion zone 70 (as shown) Figure 3A As shown in the diagram. The second gas injection assembly 60 includes a second-stage gas source 62 and a second gas injection nozzle 64 fluidly connected to the second-stage gas source. The second-stage gas source 62 supplies steam and / or substitute gas to the second gas injection nozzle 64. The second gas injection nozzle 64 includes at least one exhaust port whose total exhaust area is not greater than half the respective total exhaust area of ​​one or more exhaust ports of the high-flow-rate, high-pressure gas injection nozzle 54. This allows the second gas injection assembly 60 to inject gas at low flow rates and high pressures.

[0055] like Figure 1A , Figure 2A and Figure 4AAs shown, the first gas injection assembly 50 is configured to inject a first-stage gas (vapor and / or substitute gas) into the internal tubular member 14 of the flare head 10 at a high flow rate and high pressure. The second gas injection assembly 60 is configured to inject a second-stage gas (vapor and / or substitute gas) into the internal tubular member 14 of the flare head 10 at a low flow rate and high pressure. The injection of the first-stage gas by the first gas injection assembly 50 and the injection of the second-stage gas by the second gas injection assembly 60 into the internal tubular member 14 draws air from the surrounding environment into the premixing zone 16 of the flare head 10 and into the exhaust gas guided to the premixing zone by the gas passage 22.

[0056] like Figure 3A As shown, the first gas injection assembly 50 is configured to inject a first-stage gas (vapor and / or substitute gas) into the combustion zone 70 at a high flow rate and high pressure. The second gas injection assembly 60 is configured to inject a second-stage gas (vapor and / or substitute gas) into the combustion zone 70 at a low flow rate and high pressure. The injection of the first-stage gas by the first gas injection assembly 50 and the injection of the second-stage gas by the second gas injection assembly 60 into the combustion zone 70 draws air from the surrounding environment and mixes it with the exhaust gas.

[0057] Now for reference Figure 1B , Figure 2B , Figure 3B , Figure 4B , Figure 5 and Figure 6 Another embodiment of the staged gas injection system 40 disclosed herein will be described. Figure 2B , Figure 3B and Figure 4B In this embodiment, a two-stage gas injection system 40 is used (each of these embodiments).

[0058] Figure 1B , Figure 2B , Figure 3B , Figure 4B , Figure 5 and Figure 6 The embodiment of the staged gas injection system 40 shown is consistent in all respects with Figure 1A , Figure 2A , Figure 3A and Figure 4AThe illustrated staged gas injection system 40 is implemented in the same way, except that the first gas injection assembly 50 and the second gas injection assembly 60 are partially combined to form a single unit. Partially combining the gas injection assemblies into a single unit improves the staged gas distribution performed by system 40. For example, gas injection nozzle 54 and gas injection nozzle 64 are combined together as a single unit. The first gas injection assembly 50 and the second gas injection assembly 60 remain close to each other and oriented in the same direction, such that both gas injection assemblies inject vapor (and / or, in the case of assembly 60, an alternative gas) into the torch head 10 (e.g., Figure 1B , Figure 2B and Figure 4B (as shown) or combustion zone 70 (as shown) Figure 3B As shown in the diagram. The first gas injection assembly 50 is still configured to inject first-stage gas (vapor and / or substitute gas) into the torch head 10 at high flow rate and high pressure (as shown in the diagram). Figure 1B , Figure 2B and Figure 4B (as shown) or combustion zone 70 (as shown) Figure 3B (as shown). The second gas injection assembly 60 is still configured to inject a second-stage gas (vapor and / or replacement gas) into the flare head 10 at a low flow rate and high pressure (as shown). Figure 1B , Figure 2B and Figure 4B (as shown) or combustion zone 70 (as shown) Figure 3B As shown in the diagram. The second gas injection nozzle 64 still includes at least one discharge port, the total discharge area of ​​which is not greater than half the corresponding total discharge area of ​​one or more discharge ports of the high flow, high pressure gas injection nozzle 54.

[0059] like Figure 6 As fully illustrated, the second gas injection nozzle 64 includes multiple exhaust ports 64a, 64b, 64c, 64d, 64e, and 64f. The gas injection nozzle 64 may include more than six or fewer exhaust ports as needed. For example, six to 24 exhaust ports may be used. As with other embodiments of the staged gas injection system 40, the emission of stage gas (vapor and / or replacement gas) draws air from the surrounding atmosphere and mixes it with the exhaust gas, also contributing to smokeless combustion.

[0060] Now for reference Figure 7 and Figure 8 Another embodiment of the staged gas injection system 40 will be described. This embodiment is similar in all respects to... Figure 1B , Figure 2B , Figure 3B and Figure 4B The illustrated staged gas injection system 40 is the same in implementation, except for the construction of the second gas injection nozzle 64. In this implementation, as... Figure 7 and Figure 8 As shown, the discharge area of ​​the second gas injection nozzle 64 is positioned above the vertical central axis of the first gas injection nozzle 54. Alternatively, the discharge area of ​​the second gas injection nozzle 64 may be flush with or positioned below the first gas injection nozzle 54. For example, Figure 7 and Figure 8 The implementation scheme of the staged gas injection system 40 shown can replace Figure 1B , Figure 2B , Figure 3B , Figure 4B , Figure 5 and Figure 6 The implementation scheme of the staged gas injection system 40 shown.

[0061] Figure 9 It shows the relationship with Figure 1A Another embodiment of the staged gas injection system 40 used in conjunction with the flare assembly and flare head 10 is shown. In this embodiment, the staged gas injection system 40 is a three-stage gas injection system, comprising a first gas injection assembly 100, a second gas injection assembly 102, and a third gas injection assembly 104. The first gas injection assembly 100, the second gas injection assembly 102, and the third gas injection assembly 104 are all close to each other and oriented in the same direction, such that all three gas injection assemblies inject stage gas (vapor and / or substitute gas) into the internal tubular member 14 of the flare head 10.

[0062] The first gas injection assembly 100 is configured to inject a first-stage gas (vapor and / or substitute gas) at a high flow rate and high pressure into the internal tubular member 14 of the torch head 10 of the torch assembly. The first gas injection assembly 100 includes a first-stage gas source 108 fluidly connected to a first gas injection nozzle 110. The first-stage gas source 108 supplies the first-stage gas to the first gas injection nozzle 110. The first gas injection nozzle 110 discharges the first-stage gas into the internal tubular member 14 and thereby draws air from the surrounding atmosphere into a premixing zone 16.

[0063] The second gas injection assembly 102 is configured to inject a second-stage gas (vapor and / or substitute gas) into an internal tubular member 14 at a low flow rate and high pressure. The second gas injection assembly 102 includes a second-stage gas source 112 fluidly connected to a second gas injection nozzle 114. The second-stage gas source 112 supplies the second-stage gas to the second gas injection nozzle 114. The second gas injection nozzle 114 includes at least one outlet having a total discharge area not greater than half the respective total discharge area of ​​one or more outlets of the high-flow-rate, high-pressure first gas injection nozzle 110. This allows the second gas injection assembly 102 to inject gas at a low flow rate and high pressure.

[0064] The third gas injection assembly 104 is configured to inject a third-stage gas (vapor and / or substitute gas) at a low flow rate and high pressure into the internal tubular member 14 of the flare head 10 of the flare assembly. The third gas injection assembly 104 includes a third-stage gas source 116 fluidly connected to a third gas injection nozzle 118. The third-stage gas source 116 supplies the third-stage gas to the third gas injection nozzle 118. The third gas injection nozzle 118 includes at least one exhaust port whose total exhaust area is not greater than half the corresponding total exhaust area of ​​one or more exhaust ports of the second gas injection nozzle 114. This allows the third gas injection assembly 104 to inject gas at even lower flow rates and high pressures. As with other embodiments of the staged gas injection system 40, the emission of the stage gas (vapor and / or substitute gas) draws in air from the surrounding atmosphere and mixes it with the exhaust gas, also promoting smokeless combustion.

[0065] Now for reference Figure 10 and Figure 11 Another embodiment of the staged gas injection system 40 will be described below. This embodiment of the staged gas injection system 40 is similar in all respects to... Figure 9 The illustrated implementation of staged gas injection 40 is identical, except that the first gas injection assembly 100, the second gas injection assembly 102, and the third gas injection assembly 104 are partially combined to form a single unit. Partially combining the gas injection assemblies into a single unit improves the stage gas distribution performed by system 40. For example, gas injection nozzles 110, 114, and 118 are combined together as a single unit. Gas injection assemblies 100, 102, and 104 remain close to each other and oriented in the same direction, such that all three gas injection assemblies inject stage gas (vapor and / or substitute gas) into the flare head 10 or combustion zone 70. The first gas injection assembly 100 is still configured to inject first-stage gas into the flare head 10 or combustion zone 70 at a high flow rate and high pressure. The second gas injection assembly 102 and the third gas injection assembly 104 are still configured to inject gas (vapor and / or substitute gas) into the flare head 10 or combustion zone 70 at a lower flow rate and high pressure. The second gas injection nozzle 114 still includes at least one discharge port, the total discharge area of ​​which is not greater than half the corresponding total discharge area of ​​one or more discharge ports of the high-flow, high-pressure gas injection nozzle 110. The third gas injection nozzle 118 also includes at least one discharge port, the total discharge area of ​​which is not greater than half the corresponding total discharge area of ​​one or more discharge ports of the gas injection nozzle 114. For example, this embodiment of the staged gas injection system 40 can replace... Figure 9 The staged gas injection system 40 shown.

[0066] like Figure 11As fully illustrated, the second gas injection nozzle 114 includes a plurality of discharge ports 114a, 114b, 114c, 114d, 114e, and 114f. The gas injection nozzle 114 may include more than six or fewer discharge ports as needed. For example, six to 24 discharge ports may be used. The second gas injection nozzle 114 is positioned around the first gas injection nozzle 110. The third gas injection nozzle 118 is positioned on the vertical central axis of the first gas injection nozzle 110. Although... Figure 11 A third gas injection nozzle 118 is shown positioned above the first gas injection nozzle 110, but the third gas injection nozzle may also be flush with or positioned below the first gas injection nozzle. As with other embodiments of the staged gas injection system 40, the emission of stage gases (vapors and / or replacement gases) draws air from the surrounding atmosphere and mixes it with the exhaust gas, also contributing to smokeless combustion.

[0067] Figure 12 It shows that Figure 10 and Figure 11 The implementation scheme of the staged gas injection system 40 shown is combined with Figure 1A and Figure 1B The illustrated flare configuration utilizes a first gas injection nozzle 110, a second gas injection nozzle 114, and a third gas injection nozzle 118, each discharging a stage gas (vapor and / or substitute gas) into an internal tubular member 14 to draw air from the surrounding environment into a premixing zone 16 within the external tubular member 12 of the flare head 10. The drawn-in air enters the exhaust gas through gas passage 22 before leaving the flare head 10. The exhaust gas / air mixture then exits the flare head 10. This again has the advantage of promoting smokeless combustion of the exhaust gas.

[0068] Although not shown in the figures, other features may also be included in the staged gas injection system 40 disclosed herein. For example, in an applicable embodiment, the second gas injection assembly 60 may be thermally connected to the first gas injection assembly 50. This allows the second gas injection assembly 60 to transfer heat to the first gas injection assembly 50 and help maintain the temperature of the steam line in the first gas injection assembly at an acceptable level. For example, the temperature of the steam line may be maintained at or above the saturation temperature of water at local atmospheric pressure.

[0069] In another embodiment, the staged gas injection system 40 includes a gas injection assembly. The gas injection assembly includes a stage gas source (vapor source and / or alternative gas source) and a fluidly connected gas injection nozzle. The stage gas source supplies stage gas (vapor and / or alternative gas) to the gas injection nozzle. The gas injection nozzle is a variable-area nozzle capable of changing the stage gas outlet area as the stage gas pressure increases, thereby achieving the effects of high pressure and low flow rate, and high pressure and high flow rate.

[0070] The advantage of using steam to introduce air into the exhaust gas is that it achieves smokeless combustion of the exhaust gas. The advantage of a staged gas injection system, which includes a gas injection assembly for injecting steam (and / or a substitute gas) at low flow rates and high pressures, is that it allows the flare assembly to operate with less steam under downgraded conditions. It allows the necessary momentum to introduce air into the exhaust gas under downgraded conditions while utilizing less steam. For example, the XP operating with 330 lb / hr of steam... ™ The standard steam nozzle of the torch (sold by John Zink Hamworthy Combustion of Tulsa, Oklahoma) operates at less than 0.11 psig and generates approximately 3 pounds of force (lbf) of momentum. A low-flow nozzle operating at approximately 5 psig will also generate approximately 3 lbf of momentum, but requires less than 70 lb / hr of steam to achieve this effect.

[0071] The flare head provided in this disclosure includes a flare head having the staged gas injection system 40 described above. The flare head may include any configuration of the flare head 10 described above. Any embodiment of the staged gas injection system 40 described above can be used in conjunction with the flare head. As will be understood, the stage gases used for each stage can be the same gas or different gases. For example, the first stage gas, the second stage gas, and the third stage gas (if used) can all be vapor; or the first stage gas can be vapor, and the second stage gas can be a substitute gas (e.g., nitrogen or air); or the first stage gas can be a substitute gas (e.g., nitrogen or air), and the second stage gas can be vapor; or the first stage can be vapor and a substitute gas, and the second stage can be a substitute gas; or the first stage can be air, the second stage can be nitrogen, and the third stage can be vapor. Other combinations may also be used.

[0072] Example

[0073] This article was tested Figure 4B The staged gas injection system is shown. As shown, the torch head 10 includes both a standard high-flow-pressure (HFHP) steam nozzle and a low-flow-pressure (LFHP) steam nozzle. During testing, steam is injected through both the HFHP and LFHP ​​nozzles.

[0074] The first phase of the test involved sending steam at various flow rates to the HFHP nozzle while simultaneously shutting off the steam flow to the LFHP ​​nozzle. For each flow rate of HFHP steam, the hydrocarbon flow rate to the flare head was adjusted to the maximum value that would still produce smokeless combustion.

[0075] The second phase of the test involved sending steam at various flow rates to the LFHP ​​nozzle while simultaneously shutting off the steam flow to the HFHP nozzle. For each flow rate of LFHP ​​steam, the hydrocarbon flow rate to the flare was adjusted to the maximum value that would still produce smokeless combustion.

[0076] Figure 13 The test results are shown. In summary, the tests demonstrate that using LFHP ​​steam nozzles can reduce the amount of steam required for smokeless combustion under reduced conditions.

[0077] In addition, computer model simulations (based on experimental test data) were conducted to compare the air entrainment performance using steam and air as the first-stage gas source. Figure 14 The results of this simulation are shown. The results indicate that, for a given first-stage gas source pressure, the air entrainment properties of air and gas are almost identical. Therefore, it can be explained that the first-stage gas can be vapor or a substitute gas.

[0078] Therefore, this disclosure is well-suited to achieving the stated purposes and advantages, as well as those inherent therein. The specific embodiments disclosed above are merely illustrative, as modifications and implementations of this disclosure may be made in ways that will be apparent to those skilled in the art with the aid of the teachings herein. Furthermore, there is no intention to limit the details of the constructions or designs shown herein except as described in the following claims. It is thus apparent that the specific illustrative examples of the above disclosure may be altered or modified, and all such changes are considered to be within the scope and spirit of this disclosure. Although apparatuses and methods may be described in a manner that “comprises,” “contains,” “has,” or “includes” various components or steps, in some examples, apparatuses and methods may also “consist substantially of” or “comprise” the various components or steps. Whenever a numerical range with a lower and upper limit is disclosed, any number falling within that range and any ranges included therein are specifically disclosed. Specifically, each value range disclosed herein (in the form of “from about a to about b” or equivalently “from about a to b” or equivalently “from about a ab”) should be understood to list each number and range included within a broader range of values. In addition, the terms in the claims have their clear and ordinary meaning unless otherwise explicitly and clearly defined in the specification.

Claims

1. A staged gas injection system for a flare head, the flare head being capable of discharging exhaust gas into a combustion zone downstream of the flare head, and the flare head including an inner tubular member disposed within an outer tubular member to form a premixing zone downstream of the inner tubular member and within the outer tubular member, the staged gas injection system comprising: The first-stage gas source is the source of the first-stage gas, wherein the first-stage gas is composed of a substitute gas; A first gas injection assembly, configured to inject a first-stage gas into the internal tubular member of the torch head at a high flow rate and high pressure, and comprising: A first gas injection nozzle is fluidly connected to a first-stage gas source, and the first gas injection nozzle receives first-stage gas from the first-stage gas source; The second-stage gas source is the source of the second-stage gas; A second gas injection assembly, configured to inject a second-stage gas into the internal tubular member of the torch head at a low flow rate and high pressure, and comprising: A second gas injection nozzle, fluidly connected to a second-stage gas source, receives second-stage gas from the second-stage gas source, wherein the first gas injection assembly and the second gas injection assembly are close to each other and oriented in the same direction, such that the first gas injection assembly injects first-stage gas into the internal tubular member of the torch head, and the second gas injection assembly injects second-stage gas into the internal tubular member of the torch head, and wherein the low flow rate indicates that the first gas injection assembly and the second gas injection assembly are configured such that, based on each nozzle, the low flow rate is half or less than the high flow rate.

2. The staged gas injection system according to claim 1, wherein the second stage gas includes a substitute gas.

3. The staged gas injection system according to claim 1, wherein the second stage gas comprises vapor.

4. The staged gas injection system according to any one of the preceding claims, wherein the first stage gas consists of air.

5. The staged gas injection system according to claim 1, further comprising: A third gas injection assembly is configured to inject gas at a low flow rate and high pressure into the internal tubular member of the torch head, and The first gas injection assembly, the second gas injection assembly, and the third gas injection assembly are close to each other and oriented in the same direction, such that the first gas injection assembly, the second gas injection assembly, and the third gas injection assembly inject gas into the internal tubular member of the torch head.

6. The staged gas injection system according to claim 5, wherein: The third gas injection assembly includes: The third-level gas source is the source of the third-level gas; A third gas injection nozzle, fluidly connected to the third-stage gas source, allows the third gas injection assembly to inject the third-stage gas into the internal tubular member of the torch head at a low flow rate and high pressure.

7. The staged gas injection system according to claim 6, wherein the third stage gas is a substitute gas.

8. The staged gas injection system according to any one of claims 5 to 7, wherein the low flow rate of the second gas injection component indicates that the first gas injection component and the second gas injection component are configured such that, based on each nozzle, the low flow rate of the second gas injection component is half or less than the high flow rate, and the low flow rate of the third gas injection component indicates that the second gas injection component and the third gas injection component are configured such that, based on each nozzle, the low flow rate of the third gas injection component is half or less than the low flow rate of the second gas injection component.

9. A staged gas injection system for a flare head, the flare head being capable of discharging exhaust gas into a combustion zone downstream of the flare head, the staged gas injection system comprising: The first-stage gas source is the source of the first-stage gas, wherein the first-stage gas is composed of a substitute gas; A first gas injection assembly, configured to inject a first-stage gas into the combustion zone at a high flow rate and high pressure, and including a first gas injection nozzle fluidly connected to a first-stage gas source, the first gas injection nozzle receiving the first-stage gas from the first-stage gas source; The second-stage gas source is the source of the second-stage gas; A second gas injection assembly, configured to inject the second-stage gas into the combustion zone at a low flow rate and high pressure, and including a second gas injection nozzle fluidly connected to a second-stage gas source, the second gas injection nozzle receiving the second-stage gas from the second-stage gas source. The first gas injection assembly and the second gas injection assembly are close to each other and oriented in the same direction, such that the first gas injection assembly injects a first-stage gas into the combustion zone, and the second gas injection assembly injects a second-stage gas into the combustion zone, and wherein the low flow rate means that the first gas injection assembly and the second gas injection assembly are configured such that, based on each nozzle, the low flow rate is half or less than the high flow rate.

10. The staged gas injection system of claim 9, wherein the second stage gas comprises a substitute gas.

11. The staged gas injection system of claim 9, wherein the second stage gas comprises vapor.

12. The staged gas injection system according to any one of claims 9 to 11, wherein the first stage gas consists of air.

13. The staged gas injection system according to claim 9, further comprising: A third gas injection assembly is configured to inject gas into the combustion zone at a low flow rate and high pressure. The first gas injection assembly, the second gas injection assembly, and the third gas injection assembly are close to each other and oriented in the same direction, such that the first gas injection assembly, the second gas injection assembly, and the third gas injection assembly inject gas into the combustion zone.

14. The staged gas injection system according to claim 13, wherein: The third gas injection assembly includes: The third-level gas source is the source of the third-level gas; A third gas injection nozzle is fluidly connected to the third-stage gas source, such that the third gas injection assembly injects the third-stage gas into the combustion zone at a low flow rate and high pressure.

15. The staged gas injection system of claim 13 or 14, wherein the low flow rate of the second gas injection component indicates that the first gas injection component and the second gas injection component are configured such that, based on each nozzle, the low flow rate of the second gas injection component is half or less than the high flow rate, and the low flow rate of the third gas injection component indicates that the second gas injection component and the third gas injection component are configured such that, based on each nozzle, the low flow rate of the third gas injection component is half or less than the low flow rate of the second gas injection component.

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