RU2745312C1 - Exhaust gas torch with low steam consumption and high smoke capabilities - Google Patents

Abstract

FIELD: refineries.SUBSTANCE: invention relates to a flare device used in refinery and petrochemical plants for burning large volumes of generated waste gases during breaks in the normal operation of the plant. The proposed steam torch comprises a waste gas cylinder, the top of which is connected to a plurality of extensions extending from the center of said waste gas cylinder. In addition, each of said extensions contains a plurality of flare gas ducts, and in each of said flare gas ducts there is a steam pipe for injecting steam into the exhaust gas prior to exposure to ambient atmospheric air.EFFECT: said invention is aimed at improving quality of the smokeless operation of the flare device under conditions of low flow rate in order to maintain the smokeless operation with less use of steam and / or auxiliary gas.9 cl, 4 dwg

Description

Priority declaration

This application claims priority over US Provisional Patent Application No. 62 / 559,318, filed September 15, 2017, the entire contents of which are incorporated herein by reference.

Background of the invention

The present invention relates to an improved flare device, and in particular to an efficient steam flare device.

Steam flare devices are used in refineries and petrochemical plants to burn large volumes of generated waste gases during interruptions in normal plant operation. An extremely important operating parameter is the possibility of "smoke-free" operation. Large quantities of high pressure steam are used to supply ambient air and forcibly mix the air with the exhaust gases. The greater the amount of mixed air per pound of steam injected into the exhaust gas, the higher the achievable smokeless capability.

A flare device for the combustion and disposal of combustible gases is well known. Flare devices are usually installed on flare stacks and located in mining, distillation, processing plants, etc., to recover flammable waste gases or other flammable gas streams that are diverted for any reason, including, but not limited to, ventilation, shutdown, equipment failure and / or emergencies. A flare device is essential in emergencies such as fire or power failure, and a properly functioning flare system is an essential component to prevent destruction of the installation in any of the above or other situations.

In one illustrative example of a "conventional" prior art high performance steam torch design, the flue gas stream enters the bottom of the flare tip through a 60 inch diameter flue gas connector (conduit). The flare tip is 9 to 10 feet in diameter. A plurality of 8 inch diameter nozzles are provided that extend through the wall of the flare tip near the base and then vertically to the outlet end of the tip. A “venturi mixer” is connected to the inlet. Steam injection nozzles are located at the inlet end of the Venturi mixer. The high pressure steam injection delivers atmospheric air that passes through the nozzle and is injected into the exhaust gas, which travels from the exhaust gas inlet at the bottom of the tip through the space around the air fitting to the outlet end of the tip. Only a small portion of the required combustion air passes through the nozzles. The remainder of the required combustion air flows upward around the outer surface of the flare tip. At the outlet end of the flare tip is a second set of steam fittings used to force air into the flue gas stream.

This design has several disadvantages. First, the relatively small 8-inch fittings severely limit the amount of air that can be supplied with steam. Second, the steam flow and the waste gas flow are substantially parallel, which means the mixing efficiency is reduced. Finally, the waste gas tends to flow through the center of the tip rather than being evenly distributed over the diameter of the tip. As a result, higher concentrations of exhaust gas accumulate in the center of the tip, resulting in incomplete combustion and the formation of smoke.

It is generally desirable to burn the flammable gas without generating smoke, and such smokeless or substantially smokeless combustion is usually required. One way to achieve smokeless combustion is by supplying combustion air with a steam jet pump, sometimes referred to as an ejector. Thanks to the combustion air, the flammable gas is completely oxidized, which means that the formation of smoke is prevented. Thus, steam is usually used as a driving force to move air in a flare device. By supplying a sufficient amount of combustion air and good mixing of the incoming air with the combustion gas, the vapor-air mixture and the combustion gas can be combusted without the formation of smoke. In a conventional flare device, only a portion of the required combustion air is supplied using a motive force such as a blower, steam jet pump, compressed air or other gas. Most of the required combustion air is obtained from the surrounding atmosphere along the entire length of the flame.

One known type of steam flare device comprises a substantially cylindrical gas tube into which a combustible gas is supplied. The bottom steam stream is fed through a plurality of steam pipes at the inlet and is forced through a bend in the steam pipe, causing a pressure drop. The bending causes the steam pipes to change direction so as to be parallel to the outer cylinder. A central stream of steam is injected into the center of the gas pipe to allow the combustible gas and steam to flow upward through the outer pipe and mix with the steam exiting the downstream steam pipes. At the upper end or outlet of the gas pipe, steam injectors direct the steam radially inward to control the peripheral portion of the mixture exiting the gas pipe, thereby igniting the air-vapor mixture and the gas mixture. A central steam flow is provided to prevent combustion inside the gas pipe. Internal combustion is typically observed at low gas flow rates such as purge rates and is exacerbated by crosswind, plugging effects caused by overhead steam flow, and if the purge gas has a lower molecular weight than air. The purge rate is typically the minimum flow rate of gas that is continuously fed into the flare to prevent an explosion in the flare stack.

Another type of steam torch uses only center and top steam injectors and works in a similar manner. The steam torches described in this document can be used for smokeless combustion. However, such a flare device may require more steam per flue gas than other types of steam flares, especially at larger sizes; in addition, they can make too much noise. The noise from the bottom steam stream can be damped, while the noise from the top steam stream is difficult or impossible to drown out due to its proximity to the flame. Due to the muffler for the bottom steam flow, not only additional costs arise, but also the wind load in the flare barrel increases, which means that the costs for the flare barrel increase. Due to the high cost of steam, piping and flare stack design, it is desirable to use less steam to achieve smokeless combustion. Thus, there is a need for improved flare apparatus and methods for smokeless combustion of combustible gases in air with reduced noise and increased efficiency to burn more fuel without increasing the amount of steam.

In low flow conditions, steam is often introduced to maintain smokeless combustion, and the amount increases with stronger winds; however, due to regulatory requirements that the combined steam / flue gas mixture must have a heat capacity greater than 270 BTU / scf and additional auxiliary gas, usually methane, must be added to maintain smokeless combustion. With many steam flares, steam and air / vapor mixture is introduced into the flue gas fairly evenly, whereas the flue gas may exit the flare unevenly in stronger winds, and equipment must maintain a higher steam and / or auxiliary gas supply to maintain smokeless combustion. Thus, there is a need for an improved flare device capable of utilizing reduced steam and / or assist gas supply under low flow conditions, regardless of wind conditions.

Summary of the invention

In one embodiment, the invention provides a steam flare comprising a flue gas cylinder, the top of said flue gas cylinder being connected to a plurality of extensions extending from the center of said flue gas cylinder, each of the extensions comprising a plurality of flare gas ducts, and a steam pipe is provided in each of the flare gas ducts. The steam flare may have a ring at the top of said flare gas duct and above the top of said steam tube. The steam flare may further have one or more flow restricting cones in some section of the flare gas duct below the outlet from the duct. The flare gas duct can be a tube having a cylindrical configuration or other configuration such as a square, rectangular, oval, or complex configuration. The steam pipe can be a single pipe having branches that extend into each of said flare gas passages. The steam outlet can be a single orifice or a plurality of straight vertical or angled openings. The ring may have perforations or other surface features. The transition from the waste gas cylinder to the waste gas equipment can be completely horizontal, with a certain slope, with a bend in any direction, or a combination of two or more of these options. The waste gas cylinder head may include a flat plate, a cone, a smaller concentric cylinder, or a combination of two or more of these.

In another embodiment, the invention provides a method for operating a steam flare comprising feeding an exhaust gas stream through an exhaust gas cylinder into a plurality of flare gas passages while simultaneously supplying a steam flow through a pipe, said pipe extending into said flare gas passage, with mixing the specified flow of waste gas and specified steam, followed by igniting the resulting mixture of the specified flow of exhaust gas, specified steam and oxygen of the external air. At the top of the waste gas tip in the flare gas duct, there may be a ring containing perforations or other surface features for guiding a mixture of said vapor and said waste gas. The steam flare may have one or more speed limiters or flow restricting cones in some section of said flare gas duct below the outlet from the duct to reduce backflow of atmospheric air to the flare extensions, thereby further reducing the amount of auxiliary gas and / or steam required to maintain smokeless combustion at low flow rates. The steam outlet may include a straight vertical orifice or a plurality of angled orifices to increase mixing of the steam, ambient ambient air and flue gas and further increase the exhaust gas flow rate while reducing backflow of ambient air at low flow rates due to partial closure of the flare gas duct by steam, thereby reducing the amount of auxiliary gas and / or steam required to maintain smokeless combustion under low flow rate conditions. The flare gas duct may have a configuration selected from the group consisting of cylindrical, square, rectangular, oval, and complex shapes. The transition from flue gas cylinder to flue gas extension can be completely horizontal, tilted, bent in a certain direction, or a combination of these options to reduce the pressure drop across the tip, to avoid the need for an increase in the nominal tip size with higher design requirements; in addition, this improves the structural integrity of the ferrule by reducing stress due to thermal expansion during combustion within the ferrule. The waste gas cylinder head may include a flat plate, cone, smaller concentric cylinder, or a combination of these to reduce thermal expansion stresses, increase structural integrity of the device, and provide better flow distribution within the flare device, thereby providing an acceptable pressure drop. The invention also relates to a situation in which atmospheric air entering the handpiece mixes with the waste gas and auxiliary gas and burns inside the handpiece, thereby heating the handpiece and reducing the life of the equipment; therefore, reducing air intrusion is important to maximize equipment life under low flow rate conditions. In addition, the invention provides advantages with a small amount of steam required, less than 0.20 pounds of steam per pound of propane waste gas. All steam is injected into the exhaust gas prior to exposure to ambient atmospheric air. The steam mixes and impulses the specified exhaust gas and the specified ambient atmospheric air. The invention also provides advantages at low flow rates where less steam and / or assist gas is required to maintain smokeless combustion and increase equipment life.

Brief description of graphic materials

FIG. 1 is an isometric perspective view of the top of a steam torch.

FIG. 2 is a view of a steam torch including an exhaust gas cylinder and a steam pipe.

FIG. 3 is a cross-sectional view of the upper part of the steam torch.

FIG. 4 shows an isometric view of two enclosed flame channels.

Detailed description of the invention

The present invention achieves smokeless combustion using less than 0.20 pounds of steam per pound of propane waste gas stream, requiring no steam for cooling and requiring a minimum amount of steam for heating (less than 0.0006 pounds of steam per maximum vent gas flow).

The invention uses exclusively internal steam, i.e. steam injected exclusively into the vent flare gas without exposure to ambient atmospheric air, with a significant agitation and momentum transfer effect on the ambient air. Other flares use a flow that is injected into the air in the vicinity of and immediately around the periphery of the flare tip and is directed so as to propel steam and air in the vicinity of and immediately around the periphery of the flare tip and directed so as to direct the steam and air into the interior of the exhaust gas or exhaust stream. gas. Such flares are called "external flow steam flares". There are other flares, which may be referred to as "internal flow steam flares", which inject steam through ducts, passages or venturi tubes from the surrounding air atmosphere, thereby injecting air and steam through the containment wall or enclosure of the exhaust gas flow into the core. waste gas flow.

In the present invention, as shown in FIG. 1, the exhaust gas flow passes upward through the cylinder 12. Steam 2 is injected into the exhaust gas stream 1 at one or more locations 4, whereby the resulting accelerated mixture of steam and exhaust gas, when exposed to ambient air, draws the ambient air into the exhaust gas (fuel) mixture and a couple. There is no mixing of the ambient air 3 with the waste gas flow 1, up to the exit from the upper part of the enclosed flame channels. Steam and exhaust gas 5 are partially mixed prior to mixing with ambient air 6, but are ejected from the flare housing or exhaust gas duct restraints at a combined speed and momentum sufficient to ensure efficient mixing of fuel and steam with ambient air to improve combustion and efficiently destruct combustion. waste gas. The relatively high-speed steam 2 imparts a pulse to the relatively low-speed exhaust gas 1, and because of this, there is some mixing of the steam and the exhaust gas 5 before exiting into the ambient air 3. The resulting partially mixed stream of steam and exhaust gas then imparts an impulse to the ambient air 6, draws it in and mixes with it as steam and exhaust gas are released from the enclosed flare channels 7. FIG. 1 shows four sets of four shielded channels 7, channel fittings 8 for steam injection, rings 9, speed limiters 10 and nozzles 16 with a steam injection sleeve. In addition, adapter plates 11 are shown bent to ensure sufficient flow distribution into the nozzles with minimal exposure of the surface to wind load, and an expansion cylinder with a sleeve and a plate 13 to suppress expansion under thermal loads.

FIG. 2 is a view that includes the lower part of the torch assembly with the cylinder 12 into which the exhaust gas 1 flows and with the pipe through which the steam 2 is supplied to the upper part containing the above elements. Shown are nozzles 16 with a steam injection sleeve, with the help of which a stream is obtained that separates the combustible mixture of the exhaust gas from the metal of the central sleeve.

FIG. 3 shows a detailed view of the enclosed torch channels. Steam 2 enters the torch channels 7 and then into the ambient air 3 for efficient combustion. Rings 9 and speed limiters or flow-limiting cones 10 are shown in each bounded passage 7.

FIG. 4 is a view showing in more detail two separate enclosed flare ducts 7 with steam 2 entering through pipe 14, which reaches almost to the top of the flare duct, while the exhaust gas flows upward and mixes with the external air to ensure efficient combustion. ...

In other embodiments, the internal injection steam is used to keep the steam hot. This vapor is completely injected into the flare tip housing at a sufficient distance and before reaching the outlet of the flare tip to the atmosphere, so that this vapor is completely mixed with the exhaust gas and imparts a small but mostly negligible torque component to the exhaust gas flow, and sufficiently does not reach the exit from the flame, so as not to have a significant effect on ensuring or improving the mixing of the resulting mixture of waste gas and steam with the ambient atmospheric air. This design uses internal steam injected through a venturi or venturi to suck in ambient air as described above. External steam is used to draw in ambient air from the periphery of the exhaust gas outlet stream, and steam is injected exclusively into the exhaust gas flow path in the flare to maintain heat. The present invention employs a novel separate and distinct mixing method with partial mixing of steam with exhaust gas at a location where it can then mix with ambient atmospheric air and impart impulse to it.

In the depicted embodiment, twenty-four flue gas ducts 7 are shown, four for each of the six transition sections per twenty-four-inch vertical cylinder 12. In another embodiment, the number and size of the waste gas ducts, as well as the number and size of the transition sections, may vary more. or less.

In one embodiment (shown in the figure), the steam injection nozzle is located short of the exit plane from the exhaust gas duct. In another embodiment (not shown), the steam supply tip extends through and out of the exit plane of the flue gas duct while still being completely in the flue gas stream.

In the embodiment shown, the flue gas nozzle has a ring 9 located close to but slightly short of the outlet of the flue gas. This ring is not necessary, but can serve 1) to improve the mixing of exhaust gas, steam and air, 2) to stabilize or create a stable bluff body to stabilize the flame, and 3) as a fine adjustment location, by adjusting the size of the duct (s ) in the ring, the throughput can be adjusted to meet the specific throughput requirements for a particular application or flare mode of operation. The advantages of adjusting the flare capacity to match the flow and capacity requirements of a particular application or flare mode of operation include better utilization of the available pressure drop across the flue gas stream system, resulting in improved mixing of flue gas, steam and air. By improving or enhancing the mixing of flue gas, steam and air, not only is combustion improved, and hence the possibility of smokeless operation of the flare burner is increased, but also the steam consumption in the flare system is further reduced to values much less than 0.20 pounds of steam per pound of exhaust propane gas. or less than 0.10 pounds of steam per pound of propane waste gas. This ring or rings may be located, as shown, short of the outlet, at the outlet, or may be attached to a structure and held outside the outlet. These rings can also be located singly or in multiples on the outside of the waste gas passage. The waste gas duct 7 shown is cylindrical in shape, but in practice it can have various shapes, including square, rectangular, oval or complex shapes. Given the many possible shapes, the "ring (s)" can be of various shapes and sizes and can contain perforations or other surface features that can cut, direct or conduct a stream of steam, waste gas, or air to effect mixing of the three component streams.

In the embodiment shown, the flue gas nozzle has three speed limiters or flow restricting cones 10 per flue gas flow passage 7. These cones are optional, but serve 1) to prevent air from entering the transition sections of the flame or inlet cylinder 12 at low flow rates, 2) to maintain combustion in channels 7 and 3) to reduce combustion in the inlet cylinder 12 for introducing waste gas flow ... In addition, the number of these cones in the waste gas passage can be increased or decreased, or the flow can be diverted from them as needed.

In the embodiment shown, a curved adapter plate 11 is shown, but this plate may be flat, inclined, or curved in the opposite direction to that shown in the figure. The curved shape is used to optimize flow distribution while minimizing pressure drop. The center cylinder and flat plate 13 are optional, but are used in the illustrated embodiment to maximize equipment life. Other not shown options for implementation include a cone with a flat plate or a simple flat plate.

The entry of steam 2 into the mixing zone with the waste gas stream 5 is shown with nine holes 15 at an angle of forty degrees from the vertical. Other embodiments include more or fewer holes, up to one hole ranging from an angle of up to fifty degrees from vertical to vertical.

In the depicted embodiment, sleeve nozzles for steam injection are shown, which are optional but which increase the life of the equipment by preventing the metal of the central sleeve from being burned by the cooling steam.

Specific embodiments

While the following description is specific to specific embodiments, it should be understood that the present description is intended to be illustrative and not to limit the scope of the foregoing description and the appended claims.

A first embodiment of the invention is a steam flare comprising a flue gas cylinder, the top of the flue gas cylinder being connected to a plurality of extensions extending from the center of the flue gas cylinder, each of the extensions comprising a plurality of flare gas ducts, and wherein in each of the flare gas ducts contains a steam pipe. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section, wherein the steam torch further comprises a ring at the top of the flare gas duct and above the top of the steam tube. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the flare gas duct is a tube having a cylindrical configuration. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the flare gas duct is a pipe having a square, rectangular, oval, or complex configuration. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam pipe comprises a single pipe having branches that extend into each of the flare ducts. gas. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the ring has perforations or other features on the surface. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section, wherein the steam torch further comprises a plurality of flow restricting cones in the flare gas duct and below the top of the steam tube. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section, wherein the steam torch further comprises one flow restricting cone in each of the flare gas passages and below the top of the steam tube. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam torch comprises a curved adapter from the flue gas cylinder to the flare gas ducts. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam torch comprises a straight adapter from the exhaust gas cylinder to the flare gas ducts. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, the steam torch having an inclined transition from the exhaust gas cylinder to the flare gas ducts. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein there is a flat plate covering the waste gas cylinder. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, with a cone and a flat plate covering the waste gas cylinder. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam torch has a cylinder and a flat plate covering a larger concentric waste gas cylinder. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam torch has a steam pipe with a single vertical opening. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam torch has a steam tube with 2-20 holes located at an angle from zero to fifty degrees from vertical. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the steam torch has external steam tubes injecting steam between the bushing metal and the combustion stream.

A second embodiment of the invention is a method of operating a steam flare, including feeding an exhaust gas stream through an exhaust gas cylinder into a plurality of flare gas passages while simultaneously supplying a steam flow through a pipe, the pipe extending into the flare gas passage while mixing the flow of waste gas and steam, followed by ignition of the resulting mixture of the flow of waste gas, steam and oxygen of the external air environment. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the ring at the top of the exhaust gas tip in the flare gas duct contains perforations or other features surfaces for guiding the mixture of steam and waste gas. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the flare gas duct 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 the preceding embodiments presented in this section up to the first embodiment presented in this section, using less than 0.09 kg (0.20 lb) steam per pound of propane flue gas ... An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the ring at the top of the flue gas tip in the flare gas duct comprises perforations or other surface the elements are suitably sized in proportion to the flue gas flow and thus use values approaching 0.05 kg (0.10 lb) steam per lb of propane flue gas, or less. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, with all of the steam injected into the exhaust gas prior to exposure to ambient atmospheric air. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, where most of the steam is injected into the exhaust gas prior to exposure to ambient atmospheric air, and a portion of the steam is injected outside. , to separate the burnt stream from the metal of the sleeve. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, with the steam mixing and impulsing the exhaust gas and ambient atmospheric air. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section, wherein a single or multiple flow restricting cones in the flare gas duct reduce the amount of air flowing into the flare gas duct. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, with a reduction in steam and / or auxiliary gas flow required to maintain smokeless operation under low flow conditions. An embodiment of the invention is one, any or all of the previous embodiments in this section, up to the first embodiment in this section, whereby due to the curved transitions between the exhaust gas cylinder and the flare gas passages, the distribution of the flow exiting from the passages is improved. flare gas, and the pressure drop in the flue gas system is reduced. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein a single vertical hole or a plurality of angled holes is used to improve mixing of ambient atmospheric air vapor and exhaust gas. An embodiment of the invention is one, any or all of the preceding embodiments presented in this section up to the first embodiment presented in this section, wherein the openings increase the flow rate of the exhaust gas, while due to the partial closure of the flare gas duct by steam ambient air return flow rate at low flow rates.

Claims (9)

1. A steam flare comprising an exhaust gas cylinder, the upper part of said exhaust gas cylinder being connected to a plurality of extensions extending from the center of said exhaust gas cylinder, each of said extensions comprising a plurality of flare gas ducts, and each from said flare gas ducts there is a steam pipe for injecting steam into the exhaust gas prior to exposure to ambient atmospheric air. 2. A steam flare according to claim 1, wherein said flare gas duct is a tube having a cylindrical, square, rectangular, oval or complex configuration. 3. A steam flare according to claim 1, further comprising a plurality of flow restricting cones in said flare gas duct and below the top of said steam pipe. 4. A steam flare according to claim 1, which comprises a curved, straight or oblique transition member from said waste gas cylinder to said flare gas ducts. 5. A steam torch according to claim 1, which comprises a cone and / or a flat plate covering the waste gas cylinder. 6. A steam torch according to claim 1, wherein said steam pipe has two to twenty holes directed at an angle of zero to fifty degrees from vertical. 7. The method of functioning of the steam torch according to any one of paragraphs. 1-6, comprising feeding an exhaust gas stream through an exhaust gas cylinder into a plurality of flare gas channels while simultaneously feeding a steam flow through a pipe, said tube extending into said flare gas channel, mixing said waste gas stream and said steam followed by igniting the resulting mixture of said waste gas stream, said vapor and oxygen of the external air environment, while all of said vapor is injected into said waste gas prior to exposure to ambient atmospheric air. 8. The method of claim 7, wherein the ring at the top of the flue gas tip in said flare gas conduit contains perforations or other surface features of suitable size in proportion to the flue gas flow, and hence values approaching 0.05 are used. kg (0.10 lb) steam per lb propane flue gas, or less. 9. The method of claim 7, wherein the curved transitions between the flue gas cylinder and said flare gas passages improve flow distribution from said flare gas passages and reduce the pressure drop across the flue gas system.

Images