TECHNICAL FIELD

[0001] The invention relates to the conversion of alkanes to alkyne and alkene compounds and reactors for such conversion.

BACKGROUND

[0002] Natural gas is an attractive feedstock for producing higher value products because of its low cost and ready availability. This is especially true with the increased production of natural gas from shale gas deposits that have occurred in recent years as a result of advancements in horizontal drilling and hydraulic fracturing technology.

[0003] Natural gas typically contains more than 85% methane. Under specific conditions for conversion and selectivity, methane can be converted into the higher value products of acetylene and ethylene. Processes for such conversion include the thermal pyrolysis of natural gas. Thermal pyrolysis is an endothermic process requiring a great amount of heat input. This is provided by the combustion of a fuel source to provide the necessary amount of heat and high temperatures to facilitate the conversion reactions. This thermal conversion has primarily been conducted using three different techniques. These include 1) co-pyrolysis along with combustion, 2) staged combustion followed by pyrolysis, and 3) combustion phase followed the utilization of shock waves to manipulate pyrolysis conditions.

[0004] Because of the high heat and temperature requirements, issues are often encountered in conventional thermal pyrolysis methods. This may include non-uniform temperature zones within the pyrolysis reactor where temperatures vary so that areas inside the reactor where the temperature is below the conversion temperature will result in inefficiencies in selectivity and lower conversion. Heat losses associated with higher temperatures may also be encountered.

[0005] Furthermore, the high heat and temperatures required in the thermal pyrolysis reaction can detrimentally affect the reactor itself. The materials of the reactor wall may degrade and even melt if subjected to temperatures of 2000 °C or more, which is not uncommon in such pyrolysis processes. This is particularly true where there are non-uniform temperature zones or the creation of hot spots within the reactor. Choked or throated reactors, which facilitate accelerated gas flow and are commonly used in pyrolysis reactors, often create hot spots that can result in material degradation and failure. Soot buildup on the reactor walls is also a common problem so that reactor may have to be shut down and cleaned more frequently. [0006] Accordingly, improvements are needed that overcome the aforementioned shortcomings.

SUMMARY

[0007] A method of conversion of light alkanes to thermal pyrolysis reaction products is carried out by introducing an alkane-containing feed stream of Ci to C ₄ alkanes into a reactor vessel defined by a reactor wall that defines an interior reaction chamber of the reactor vessel. The reactor vessel has an inlet at one end for introducing the alkane-containing feed stream into the reaction chamber and an opposite outlet at the other end of the reactor vessel for discharging reaction products from the reaction chamber out of the reactor vessel. That portion of the reactor vessel located between the inlet and outlet defines a flow path that extends between the inlet and outlet of the reactor vessel.

[0008] A combustion gas mixture is introduced through a plurality of burners that are spaced apart from one another at different positions along the length and perimeter of the reactor vessel between the inlet and outlet. The plurality of burners each having a nozzle oriented at a non-parallel angle relative to the flow path so that combustion gases are discharged from the nozzle from the reactor wall into the reaction chamber at non-parallel angles relative to the flow path. The alkane-containing feed stream is allowed to be converted to thermal pyrolysis reaction products comprising at least one of alkenes and alkynes within the reactor vessel. The thermal pyrolysis products are removed through the outlet of the reactor vessel.

[0009] In particular embodiments, temperatures ranging from 1400 °C to 1850 °C are maintained within the reaction chamber. The alkane-containing feed stream may be a methane-containing feed stream and the thermal pyrolysis reaction products may comprise at least one of ethylene and acetylene. The nozzle of at least one burner of the plurality of burners may be oriented at a perpendicular angle relative to the flow path.

[0010] In some embodiments, the least one burner of the plurality of burners has a nozzle that is rotatable about an axis oriented perpendicular to the flow path so that the angle of the nozzle can be adjusted and so that combustion gases can be selectively discharged from the nozzle into the reaction chamber at different non-parallel angles relative to the flow path. The at least one burner of the plurality of burners may have a nozzle that is selectively rotated from 0° to 30° downstream about an axis oriented perpendicular to the flow path to adjust the angle of the nozzle so that combustion gases can be selectively discharged from the nozzle into the reaction chamber at different non-parallel angles relative to the flow path. [0011] In particular embodiments, the reactor wall is jacketed with a cooling jacket to absorb heat from the reactor walls during the conversion. The reactor may be a non-choked reactor.

[0012] The gas flow within the interior of the reactor may be subsonic. The residence time within the reactor vessel may be from 10 milliseconds or less.

[0013] The combustion gas mixture may be fuel rich. The plurality of burners may be spaced apart from one another upon the reactor wall in a staggered configuration extending along the length of the reactor vessel.

[0014] A thermal pyrolysis reactor includes a reactor vessel defined by a reactor wall that defines an interior reaction chamber of the reactor vessel. The reactor vessel has an inlet at one end for introducing a feed stream to be converted into the reaction chamber and an opposite outlet at the other end of the reactor vessel for discharging thermal pyrolysis reaction products from the reaction chamber out of the reactor vessel. That portion of the reactor vessel located between the inlet and outlet defines a flow path that extends between the inlet and outlet of the reactor vessel. A plurality of burners are spaced apart from one another upon the reactor wall for introducing combustion gases within the reaction chamber at different positions along the length and perimeter of the reactor vessel between the inlet and outlet to facilitate conversion of the feed stream to thermal pyrolysis reaction products. The plurality of burners each have a nozzle oriented at a non-parallel angle relative to the flow path so that combustion gases are discharged from the nozzle from the reactor wall into the reaction chamber at non-parallel angles relative to the flow path.

[0015] In particular embodiments, the nozzle of at least one burner of the plurality of burners is oriented at a perpendicular angle relative to the flow path. At least one burner of the plurality of burners may also have a nozzle that is rotatable about an axis oriented perpendicular to the flow path so that the angle of the nozzle can be adjusted. The at least one burner of the plurality of burners may have a nozzle that is rotatable from 0° to 30° downstream about an axis oriented perpendicular to the flow path so that the angle of the nozzle can be adjusted.

[0016] The reactor wall may be jacketed with a cooling jacket to absorb heat from the reactor walls. The reactor may be a non-choked reactor. The plurality of burners may be spaced apart from one another upon the reactor wall in a staggered configuration extending along the length of the reactor vessel. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a more complete understanding of the embodiments described herein, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying figures, in which:

[0018] FIG. 1 is a plot of the effect of temperature on the molar fraction stability of various compounds, including methane, acetylene, and ethylene;

[0019] FIG. 2 is a plot of the conversion to acetylene from various feeds as a function of temperature in thermal pyrolysis reactions;

[0020] FIG. 3 is an elevational side view of a schematic of a thermal pyrolysis reactor constructed in accordance with an embodiment of the invention;

[0021] FIG. 4 is a cross-sectional side view of a schematic of a thermal pyrolysis reactor constructed in accordance with an embodiment of the invention;

[0022] FIG. 5 is a top plan view of a schematic of a thermal pyrolysis reactor that has been scaled up using multiple unit reactor cells in accordance with an embodiment of the invention; and

[0023] FIG. 6 is a computational fluid dynamic (CFD) computer simulation plot from Example 1 of the contours of mass fraction of methane and acetylene, as well as the static temperature. DETAILED DESCRIPTION

[0024] In thermal pyrolysis reactions, maximum conversion and selectivity for certain products may occur within narrow reaction parameters. Thus, maximum control of reactor parameters is desired to maintain the reaction within these narrow parameters. With respect to the conversion of alkanes, such as Ci to C ₄ alkanes, to alkyne and alkene reaction products through thermal pyrolysis, increased efficiencies in conversion and selectivity may be obtained within narrow temperature windows and short residence times (i.e., milliseconds) to avoid undesirable reactions. High conversion and selectivity for the conversion of methane, which is the predominant component of natural gas, to acetylene and ethylene may be achieved within such a narrow temperature window.

[0025] It should be noted that throughout the description, although the discussion and examples presented may relate to the conversion of methane to acetylene and ethylene products, the methods and systems presented may be equally applicable to the conversion of other alkane compounds to higher value alkyne and alkene compounds, which are similar in nature. [0026] Referring to FIG. 1, the effect of temperature on the molar fraction stability of various compounds, including methane (CH ₄ ), acetylene (C ₂ H ₂ ), and ethylene (C ₂ H ₄ ). As can be seen, as the temperature is increased, selectivity and conversion to acetylene increases steadily. At a temperature of about 1400 °C the selectivity and conversion to acetylene begins to reach its highest level, where it tends to stabilize as the temperature is increased.

[0027] FIG. 2 shows the conversion to acetylene using various feeds, as represented by the atomic ratios for hydrogen and carbon (H/C), as a function of temperature, where H/C = 4 correlates to a methane feed. As can be seen for methane, the highest conversion to acetylene is reached at a temperature of above 1450 °C. The acetylene conversion tends to stabilize with higher temperatures. As can be seen from FIG. 1, the molar fraction stability is at the same temperature range as that for acetylene so ethylene is also being formed at these temperatures.

[0028] As can be seen from FIGS. 1 and 2, maintaining the pyrolysis within an ideal pyrolysis temperature zone can result in higher conversion and selectivity for the higher value products of acetylene and ethylene. In particular, a temperature range of from 1400 °C to 1850 °C that can be uniformly maintained within the pyrolysis zone of the pyrolysis reactor can result in increased conversion and selectivity for acetylene. In certain instances, the temperature range may be from 1400 °C to 1800 °C.

[0029] It should be noted in the description, if a numerical value, concentration or range is presented, each numerical value should be read once as modified by the term "about" (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. Also, in the description, it should be understood that an amount range listed or described as being useful, suitable, or the like, is intended that any and every value within the range, including the end points, is to be considered as having been stated. For example, "a range of from 1 to 10" is to be read as indicating each and every possible number along the continuum between about 1 and about 10. Thus, even if specific points within the range, or even no point within the range, are explicitly identified or referred to, it is to be understood that the inventor appreciates and understands that any and all points within the range are to be considered to have been specified, and that inventor possesses the entire range and all points within the range.

[0030] While these temperatures may be achieved in conventional reactors, they cannot be maintained uniformly as the temperature profile varies greatly within the pyrolysis zone due to uneven and non-uniform heat input from the combustion zone. In accordance with the embodiments described herein, a pyrolysis reactor can be provided that overcomes the shortcomings of conventional pyrolysis reactors. In particular, the methods and reactor(s) described herein create a uniform temperature zone for high conversion of alkanes, such as methane, to the higher value products of alkynes and alkenes, such as acetylene and ethylene.

[0031] Furthermore, the methods and reactor(s) described herein direct combustion away from the reactor walls to ensure cooler conditions on the wall to ensure long-term durability of the reactor. A more uniform temperature within the pyrolysis zone that is at or near the ideal temperature for pyrolysis can also be provided that minimizes heat losses associated with higher temperatures. This can be done with an extraordinary level of control over the process to enable online or remote monitoring and control to offset any feedstock variations or variations in other operating parameters.

[0032] This can be achieved by distributing a number of burners that are spaced apart from one another at different positions along the length and around perimeter of the reactor vessel for introducing a combustion gas mixture for supplying heat to facilitate the pyrolysis reaction. FIG. 3 shows an elevational side view of unit pyrolysis reactor 10 formed from a reactor vessel 12 defined by a reactor wall 14.

[0033] The reactor 10 is non-choked or is not provided with a throat, as in some pyrolysis reactors to increase the velocity of gases through the reactor. Such choked or throated reactors tend to develop hotspots on the throat portion as a result of the constriction created so that heating is non-uniform. Such throated reactors can also encounter material failure due to the excessive heat created by these hotspots. Accordingly, the reactor wall 14 is shown as being cylindrical having a substantially uniform diameter along its length.

[0034] The reactor wall 14, as well as other components of the reactor 10, may be made of suitable materials that can be subjected to the high temperatures encountered in the pyrolysis reaction. These are materials that do not readily degrade or melt at temperatures above 1500 °C. Examples of such materials include stainless steel, such as 321 stainless steel, and refractory materials. In one example, the reactor wall 14 may be formed from an outer wall 14A of refractory material with an interior stainless steel liner 14B, as shown in FIG. 4.

[0035] An inlet 16 is provided at an end of the reactor 10 for introducing a feed stream 18 to be converted. The feed stream 18 may be a hydrocarbon gas that contains one or more alkanes. These may be light alkanes such as Ci to C ₄ alkanes. In certain instance, the feed stream may be predominantly methane (i.e., >50 mol%) or entirely methane. In particular embodiments, the feed stream may be composed of natural gas, which may have a methane content of from 85 mol% to 97 mol% or more. The feed stream may be preheated prior to being introduced into the reactor. In some cases the feed stream 18 may be a pretreated feed stream that has been treated to remove undesirable components, such as sulfur-containing compounds.

[0036] FIG. 4 shows a cross-sectional side view of the reactor 10. As shown, the reactor wall 14 of the reactor vessel 12 defines an interior reaction chamber 20 that provides a pyrolysis zone where the pyrolysis reaction takes place converting the feed stream to thermal pyrolysis reaction products, such as alkynes and alkenes. In the case of a methane feed stream, the pyrolysis reaction products include acetylene and ethylene. Referring to FIG. 3, an outlet 22 is provided on the opposite end of the reactor 10 for discharging or removing the reaction products 24 from the reactor vessel 12. That portion of the reactor vessel 12 located between the inlet 16 and outlet 22 defines a flow path 26 that extends between the inlet 16 and outlet 22 of the reactor vessel 12. The flow path 26 is shown as coinciding with a central longitudinal axis of the reactor vessel 12.

[0037] As shown in FIGS. 3 and 4, a plurality of burners 28 are spaced apart from one another upon the reactor wall 14 for introducing combustion gases within the reaction chamber 20. The burners 28 are positioned at different positions along the length and perimeter of the reactor vessel 12 between the inlet 16 and outlet 22 to facilitate conversion of the feed stream to thermal pyrolysis reaction products. The plurality of burners 28 each having a burner nozzle 30 oriented at a non-parallel angle relative to the flow path so that combustion gases are discharged from the nozzle 30 from the reactor wall 14 and directed into the reaction chamber 20 at non-parallel angles relative to the flow path 26 or central axis. In particular embodiments, at least one or more or all of the nozzles 30 are oriented so that combustion gases are discharged from the nozzle 30 and directed towards the center of the reaction chamber 20. This may be towards the central longitudinal axis of the reaction chamber 20. As described herein, where any nozzle discharges a particular spray pattern, when reference is made to the angle of orientation for the nozzle or discharge of gases it is meant to refer to the angle of that line that extends through the center of the spray pattern or angle as it originates from the nozzle.

[0038] In certain embodiments, at least one or more or all of the burner nozzles 30 is mounted on a rotatable mounting so that the nozzle 30 is rotatable about an axis oriented perpendicular to the flow path 26 or the central longitudinal axis of the reaction chamber 20 so that the angle of the nozzle 30 can be adjusted. An actuator (not shown) may be provided for actuating the burner nozzle 30 and/or mounting so that the angle of the burner nozzle 30 can be selectively adjusted. The actuator may be electrically coupled to a control system (not shown) of the reactor 10 to selectively adjust the angle of any one or more or all of the burner nozzles 30.

[0039] FIG. 3 shows the angle of rotation 32 of the burner nozzles 30. The angle of rotation 32 may vary but in certain embodiments the angle may be 5°, 10°, 15°, 20°, 25°, or 30° from the perpendicular angle (i.e., angle 32 = 0°) relative to the flow path 26 or the central longitudinal axis of the reaction chamber 20. This causes the burner nozzles to rotate downstream along the flow path 26 or along the central longitudinal axis of the reaction chamber 20 so that discharged combustion gases always remain directed toward the center of the reaction chamber 20. While the burner nozzles 30 may rotate about an axis perpendicular to the flow path 26 or the central longitudinal axis of the reaction chamber 20, rotation from side to side about a non-perpendicular axis may be limited or prevented to prevent combustion gases from being directed away from the center of the reaction chamber. By rotating the burner nozzles 30 between the perpendicular and downstream positions, a swirling or variable flow of the combustion gases may be provided that facilitates uniform heating within the reaction chamber 20 and provides more efficient mixing of the hot combustion gas with the introduced feed stream.

[0040] As shown in FIG. 3, the burner nozzles 30 may be spaced apart from one another and arranged in a staggered configuration about the perimeter and along the length of the reactor wall 14. In such staggered configuration, the burner nozzles 30 may be circumferentially spaced apart from 5° to 45° from the next closest longitudinally adjacent nozzle about the perimeter of the reactor wall 14. In some instances, the nozzles may be staggered along the length of the reactor vessel 12 with only one burner nozzle located at each longitudinal position or particular distance from the reactor inlet 16. In certain embodiments, however, two or more nozzles 30 may be circumferentially spaced from 5° to 180° around the perimeter of the reactor wall 14 at a particular longitudinal position or distance from the reactor inlet 16. Thus, two or more nozzles may be spaced at or nearly the same longitudinal position or distance from the reactor inlet 16 along all or a portion of the length of the reactor vessel 12. In particular embodiments, those nozzles located at or nearly the same longitudinal position may be spaced from 25° to 180° apart. Thus, for example, in one configuration for the reactor 10, you may have multiple pairs of nozzles 30, with each pair being located at the same longitudinal position or distance from the reactor inlet 16. The pairs of nozzles 30 may be spaced along the length of the reactor chamber 20, with the nozzles of pair being located on opposite sides (i.e., 180° apart) of the reactor wall 12 from one another. In such instances, the next longitudinally adjacent pair of nozzles 30 are also circumferentially spaced apart 180° but are each spaced from 5° to 45° from the next closest longitudinally adjacent nozzle. As can be understood, various staggered configurations for the burner nozzles can be provided in this manner. The nozzles may be longitudinally spaced apart from 0.05L to 0.3L, where L is the length of the reaction chamber 20 as measured from the inlet. In certain embodiments, the nozzles may be longitudinally spaced apart from 0.05L to 0.2L, with 0.1L being a particularly useful distance.

[0041] The spacing of the burner nozzles 30 may be such that the spray patterns do not longitudinally overlap but are longitudinally spaced apart a distance. In other embodiments, the spacing of the burner nozzles 30 is such that the spray patterns from each nozzle may longitudinally overlap with the spray pattern of the next longitudinally adjacent burner nozzle 30. This longitudinal overlap may be present when the nozzles 30 are all oriented at an angle of 0°. In other embodiments, the spray pattern may longitudinally overlap with the next longitudinally adjacent nozzle only when the nozzle 30 is rotated downstream toward the next longitudinally adjacent nozzle when the adjacent nozzle 30 is oriented at a perpendicular orientation (i.e., angle 32 = 0°).

[0042] In certain embodiments, the reactor vessel 12 may be jacketed. As shown in FIG. 4, all or a portion of the reactor wall 14 is surrounded by a cooling jacket 34 to facilitate cooling of the reactor wall 14. The coolant for the cooling jacket 32 will typically be water that is circulated through the cooling jacket 34. This prevents the reactor wall 14 from becoming too hot and increases the life of the reactor 10. The cooling jacket also provides a means for measuring heat loss. By monitoring the flow rate and temperature of the water or coolant entering the cooling jacket 32 and the temperature of the water or coolant exiting the cooling jacket 32 the amount of heat and energy lost from the reactor can be determined. This also provides feedback that can be used in providing process control for the reactor.

[0043] In the conversion of light alkanes by thermal pyrolysis, combustion gases are introduced through the burner nozzles 30 into the reactor 10 to provide the necessary heat for reaction. The combustion gases are those combustible hydrocarbons that provide sufficient heat for the pyrolysis reaction. The combustion gases will include a mixture of oxygen gas (0 ₂ ) or an oxygen gas source (such as air) and the combustible hydrocarbons. In many instances, the hydrocarbons used for the combustion fuel are the same or similar to the hydrocarbons of the feed stream 18, such as methane or natural gas. The combustion gases are fuel rich so that the amount of oxygen present is entirely consumed during the pyrolysis reaction so that no oxygen gas is discharged from the reactor. In certain embodiments, the amount of hydrocarbon fuel and oxygen gas in the combustion gases may range from a hydrocarbon/0 ₂ mass ratio of from 0.25 to 0.45. As an example of a suitable mixture for the combustion gases using a methane fuel, the mass fraction of methane may be 0.235 with the mass fraction for 0 ₂ being 0.765, which would provide a hydrocarbon/0 ₂ mass ratio of approximately 0.3. The combustion gases may be preheated prior to being introduced into the reactor.

[0044] The combustion gases are ignited within the reaction chamber 20 and are introduced at a sufficient rate to maintain the desired reaction temperatures within the reaction chamber 20. As discussed previously, this will typically be from 1400 °C to 1850 °C.

[0045] With the reactor 10 at the required temperature, a gas feed stream to be converted, such as the feed stream 18 (e.g., methane or natural gas), is introduced into the reactor 10 through inlet 16. The feed stream 18 is introduced to provide a gas flow rate that is subsonic. In particular embodiments, the gas flow rate may be regulated to provide a residence time within the reactor 10 milliseconds or less. In certain embodiments, the residence time may be from 3 milliseconds to 10 milliseconds.

[0046] The combustion gases provided by the burners 28 can be controlled to accommodate variations in feedstock or other operating parameters. This may include the amount or rate of combustion gases delivered to the reactor through the burner nozzles and/or rotation or orientation of the burner nozzles. In some embodiments, one or more or all of the burner nozzles 30 may be rotated continuously during the reaction, such as to provide a swirling or variable flow throughout the reaction. In other instance, the burner nozzles 30 may be rotated periodically or at selected times to adjust the temperature within a particular region of the reaction chamber 20. In certain instances, the burner nozzles 30 may be operated sequentially, with some being rotated while others remaining fixed. This may include sequential rotating around the circumference of the reactor or along the length of the reactor or both. In this way, different swirl or flow patterns of the reaction gases can be created.

[0047] Because the combustion gases are directed toward the center of the reaction chamber 20, more uniform heating occurs within the desired temperature range, as discussed previously. Furthermore, the combustion gases are directed away from the walls of the reactor so that the walls do not overheat, as may occur with conventional reactors. The cooling jacket 34 also facilitates cooling of the reactor walls to increase their life and durability. This also reduces soot formation that may build up on the reactor walls.

[0048] The reactor and method allows light alkanes, such as Ci to C ₄ alkanes, and in particular methane, to be converted by thermal pyrolysis to alkynes and alkenes, such as acetylene and ethylene. The thermal pyrolysis products 24 are removed from the reactor vessel 12 through outlet 22 for collection and storage or further processing.

[0049] The reactor 10 described above may constitute or form the basis of a single reactor unit cell. Using the configuration and characteristics of the reactor unit 10, a reactor of increased scale may be provided based upon this single reactor unit cell. Such scalability is much more straight forward than for conventional reactors, as one can replicate the unit reactor cell with very little modification.

[0050] Referring to FIG. 5, a top plan view of such a scaled reactor 40 is shown. As can be seen the reactor 40 includes multiple inlets 42, which each generally correspond to the inlet 16 of the reactor 10. The reactor 40 differs from that of reactor 10 in that a single reactor vessel 44 defined by reactor wall 46 accommodates the multiple inlets 42. While the reactor 40 is shown with a rectangular transverse cross section, it may have a cylindrical cross section, as well as other configurations to accommodate the multiple inlets. The inlets 42 allow for the introduction of multiple feed streams into the reaction chamber 48 defined by the reactor wall 46, which may be similar to the reactor wall 14 and be jacketed with a cooling jacket, as well. The feed streams introduced through inlets 42 may be the same as those discussed with respect to the feed stream 18 of FIG. 3.

[0051] The reactor 40 includes burner nozzles 50 for introducing combustion gases into the reaction chamber 48 and may be the same as the burner nozzles 30 described with respect to the reactor 10. The burner nozzles 50 may be oriented and function in a similar manner, as well. With respect to the reactor 40, the burner nozzles 50 may be spaced in a similar manner upon the reactor wall 44 in a similar manner to those burner nozzles 30 used in reactor 10. This may include the staggered configurations and spacing previously discussed.

[0052] The following examples serve to further illustrate various embodiments and applications.

EXAMPLES

EXAMPLE 1

[0053] A thermal pyrolysis conversion reaction was simulated using an ANSYS ^® Fluent computational fluid dynamic (CFD) computer simulation was conducted wherein a hypothetical methane feed was converted to acetylene and ethylene. The simulated reaction was carried out in a hypothetical cylindrical 321 stainless steel reactor that was 20 inches in length and had a diameter of 4 inches. The inlet had a diameter of 1.2 inches. Six burners having burner nozzles that were oriented so that the combustion gas discharge was directed towards the center axis of the reactor. The burner nozzles were spaced around the perimeter of the reactor approximately 3 inches apart, with the first burner being located approximately 1 inch from the inlet. The burners were staggered around the perimeter of the reactor and were circumferentially spaced apart every 45° from the next longitudinally adjacent burner along the length of the reaction chamber. The burner nozzles each had an inlet into the reaction chamber with a diameter of 0.6 inch.

[0054] The combustion gases constituted a fuel/oxygen mixture of 0.235 mass fraction of methane and 0.765 mass fraction of 0 ₂ . These were preheated to a temperature of 300 °K and fed into the reaction chamber of the reactor at a rate of 0.0085 kg/s to provide a reaction temperature of 1400°C to 1850 °C.

[0055] Methane was preheated to a temperature of 837 °K and fed into the reactor inlet at a rate of 0.016 kg/s. The reaction products were determined by CFD and provided a conversion of 80.2%, a selectivity of 43.3%, and a yield of 34.7% for acetylene. A plot of the contours of mass fraction of methane and acetylene, as well as static temperature, are shown in FIG. 6.

[0056] While the invention has been shown in some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes and modifications without departing from the scope of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.