Multifunctional burner and method of operation

Abstract

A method for heating a reactor using a multifunctional burner, the method comprising feeding a primary fuel through an annular passage, feeding oxygen through a central passage within the annular passage, and feeding an auxiliary fuel through a central lance within the central passage to produce a flame extending into a furnace having a temperature and pressure; wherein the flow rates of auxiliary fuel and oxygen are increased while maintaining the equivalence ratio below 1 to increase the temperature of the furnace; wherein after a furnace temperature exceeds an auto-ignition temperature of the main fuel, a flow rate of the main fuel is increased to increase the equivalence ratio to greater than 1.

Description

[0001] Cross-references to related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 465,291, filed May 10, 2023, and U.S. Provisional Patent Application No. 63 / 534,914, filed August 28, 2023. Background Technology

[0002] This disclosure relates to systems and methods for operating a multi-functional burner in a partial oxidation (POx) reactor. POx reactors convert hydrocarbons into syngas at a much lower stoichiometric oxygen-to-fuel molar ratio and typically at elevated pressures and temperatures. Most POx reactors must first undergo a heating mode before entering an oxy-fuel mode, in which the reactor is slowly heated to prevent cracking or other damage to the refractory lining, in which the POx reactor generates syngas. Because reactor heating occurs at atmospheric pressure, this introduces a design mismatch for the burner between the heating and oxy-fuel modes. Typically, a separate burner is used for both modes, and the exchange occurs when the POx reactor reaches elevated temperatures, such as 1100–1400°C. Given the significant challenges in both safety and maintenance associated with exchanging burners at high temperatures, there is a commercial need for a single burner capable of operating in both modes. Attached Figure Description

[0003] The invention will now be described with reference to the accompanying drawings, wherein similar reference numerals denote similar elements: Figure 1 This is a cross-sectional side view of an oxygen-fuel burner based on existing technology.

[0004] Figure 2 This is a cross-sectional side view of a multi-functional burner with a central spray gun in a heating mode configuration.

[0005] Figure 3 This is a cross-sectional side view of a multi-functional burner with a central nozzle in an oxygen-fuel configuration.

[0006] Figure 4A This is a cross-sectional side view of a multi-functional burner with dual-channel spray guns in a heating mode configuration.

[0007] Figure 4B yes Figure 4A A variant in which the swirl blades are positioned in an annular area between the central channel and the dual-channel spray gun.

[0008] Figure 4C yes Figure 4B A cross-sectional side view of a multi-functional burner shows the effect of swirl blades on the recirculation zone in the flame.

[0009] Figure 4D1 yes Figure 4A A variant in which the swirl blades deflect from the dual-channel spray gun via an annular bypass gap.

[0010] Figure 4D2 This is an enlarged cross-sectional side view of the burner tip shown in 4D2.

[0011] Figure 4E yes Figure 4C A cross-sectional side view of a multi-functional burner shows the effect of swirl blades on the recirculation zone in the flame.

[0012] Figure 5 This is a cross-sectional side view of a multi-functional burner that defines key geometric parameters.

[0013] Figure 6 This is a cross-sectional side view of a multi-functional burner with a central spray gun and a drive mechanism for axially moving the central spray gun relative to the central channel.

[0014] Figure 7 This is an image of the drive mechanism used to move the central spray gun axially relative to the central channel.

[0015] Figure 8A This is a cross-sectional side view of a multifunctional burner with swirl blades that defines key geometric parameters.

[0016] Figure 8B yes Figure 8A A variant in which the center spray gun has a single channel and retracts from the outlet of the center channel.

[0017] Figure 9 This is a cross-sectional side view of a multi-functional burner with a central nozzle that operates with two fuel feed streams.

[0018] Figure 10 This is a cross-sectional side schematic diagram of a multifunctional burner with swirl blades that operates with a gaseous fuel feed stream and a solid and / or liquid fuel feed stream.

[0019] Figure 11 This is a schematic cross-sectional view of a swirl vane used in the channel of an air-fuel combustor.

[0020] Figure 12 yes Figure 11 A variant of the design, in which swirl blades are used in a reverse diffusion oxygen-fuel combustor.

[0021] Figure 13 This is a schematic diagram of the cross-section of the swirl blades in the converging channel.

[0022] Figure 14 It is a streamline diagram of a flow field with a swirling jet, which has strong swirling properties.

[0023] Figure 15 yes Figure 13 A variant in which a vent located upstream of the swirl vanes allows a portion of the fluid flow to bypass the swirl vanes.

[0024] Figure 16 yes Figure 15 A variant in which the swirl blades have varying swirl angles along the length of the blades.

[0025] Figure 17 This is a diagram showing the flame generated by an oxygen-fuel burner, illustrating the inner and outer flame portions.

[0026] Figure 18 This is a diagram showing the flame generated by an oxygen-fuel burner, illustrating the gap between the inner flame and the central channel.

[0027] Figure 19 This is a diagram showing the flame generated by an oxygen-fuel burner, illustrating the rise from the burner's outlet plane.

[0028] Figure 20 This is a graph showing the wall temperature in the burner as a function of the equivalence ratio for three different swirling conditions. Detailed Implementation

[0029] The following detailed description provides preferred exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the subsequent detailed description of preferred exemplary embodiments will provide those skilled in the art with an enabling description for carrying out the preferred exemplary embodiments of the invention. Various changes may be made to the function and layout of the elements without departing from the spirit and scope of the invention as set forth in the appended claims.

[0030] The articles “a” and “an” used herein, when applied to any feature in the embodiments of the invention described in the specification and claims, refer to one or more features. The use of “a” and “an” does not limit the meaning to a single feature unless such limitation is explicitly stated. The article “the” preceding a singular or plural noun or noun phrase indicates one or more specific features and may have a singular or plural meaning depending on the context in which it is used.

[0031] The term “and / or” placed between the first entity and the second entity includes any of the following meanings: (1) only the first entity, (2) only the second entity, or (3) both the first entity and the second entity. The term “and / or” placed between the last two entities in a list of three or more entities means that at least one entity in the list includes any particular combination of entities in this list. For example, “A, B and / or C” has the same meaning as “A and / or B and / or C” and includes the following combinations of A, B and C: (1) only A, (2) only B, (3) only C, (4) A and B but no C, (5) A and C but no B, (6) B and C but no A, and (7) A and B and C.

[0032] "Downstream" and "upstream" refer to the intended direction of flow of the process fluid. If the intended direction of flow of the process fluid is from the first unit to the second unit, then the second unit is located downstream of the first unit. In the case of a circulating flow, downstream and upstream refer to the first passage of the process fluid.

[0033] Figure 1 A cross-sectional side schematic diagram of an oxy-fuel burner according to the prior art is shown. A central channel 101 supplying oxygen 102 is surrounded by an annular channel 103 supplying main fuel 104, which includes one or more hydrocarbons, such as natural gas or any gaseous, liquid, or solid hydrocarbon. The outlet 114 of the annular channel 103 forms a convergence angle θ with the central axis of the oxy-fuel burner. The central channel can be opened from an inlet diameter D. ox,in Narrowing to the outlet diameter D ox,out This configuration, known as a reverse diffusion flame, where fuel surrounds oxygen, is commonly found in POx burners. Those skilled in the art will understand that oxygen-fuel burners designed according to the prior art for high pressures under substoichiometric conditions cannot deliver heat at a sufficiently low and stable rate during the heating of the reactor from cold conditions to temperatures exceeding 1200°C at ambient pressure without potentially causing irreparable damage to the furnace refractory. Therefore, a common practice is to utilize a separate “heating mode” air-fuel burner designed to provide a controlled temperature ramp at nominal atmospheric pressure, then physically remove this burner and replace it with a similar… Figure 1 Oxygen-fuel burner replacement.

[0034] Figure 2A cross-sectional side view of a multi-functional burner according to this disclosure is shown, which has a central nozzle 205 along the axis of a central channel 201. The convergence angle θ of the outlet of the annular channel relative to the central axis of the burner can be less than about 45°, or less than about 40°, or less than about 35°, or less than about 30°, or less than about 15°. The convergence angle θ of the outlet of the annular channel relative to the central axis of the burner can be in the range of 5° to 45°, or 10° to 40°, or 15° to 30°. The outlet of the central nozzle 205 can extend near the tip of the central channel 201, or can be retracted into the larger inner diameter region of the central channel 201 (e.g., in such a region). Figure 1 D shown ox,in (Section). The center lance 205 allows the multi-functional burner to operate in both heating and oxy-fuel modes. To assist in heating mode, the center lance 205 may include an ignition source 206, such as a high-voltage electrical device that generates a corona discharge (spark) from the center lance 205 to the center channel 201. The tip of the ignition source 206 may bend toward the tip of the outlet of the center lance 205 to aid in the formation of an electric arc (not shown). The center lance 205 may include a flame scanning device 207 having a line of sight along the length of the center lance 205 to detect the flame in the multi-functional burner. If the flame scanning device 207 is only needed during heating mode, it can be isolated from the POx burner using an isolation valve 208 during oxy-fuel mode.

[0035] Figure 2 The flow configuration for the heating mode is shown. In the heating mode, a central nozzle 205 feeds heating fuel 209, such as natural gas, typically at a flow rate significantly lower than required in the oxygen-fuel mode. An ignition source 206 is used to ignite the fuel-oxygen mixture to produce a flame, and a flame scanning device 207 monitors this flame. Oxygen 210 can be supplied through a central channel 201, and air 211 can be supplied through an annular channel 203.

[0036] Figure 3 The flow configuration for oxygen-fuel mode is shown once the required temperature in the POx reactor has been reached. The flow through the central nozzle 205 can be cut off, and the flame scanning device 207 can be isolated by closing one or more isolation valves 208. The central nozzle 205 can be purged with inert gas. Oxygen 210 can still be supplied through the central channel 201, but the main fuel source 212 can be supplied through the annular channel 203. During oxygen-fuel mode, the central nozzle 205 can retract into the larger diameter section of the central channel 201, as shown... Figure 2 As shown.

[0037] Those skilled in the art will understand that the conversion of air to primary fuel in the annular channel 203 requires careful design to ensure safe operation. A check valve can be used to prevent backflow into the sources of fuel, air, and / or purge gas. A ball valve can allow for the isolation and purification of sources of oxygen, fuel, air, and / or purge gas.

[0038] Figure 4A A cross-sectional side schematic diagram of a multi-functional burner according to the present disclosure is shown, the burner having a center nozzle including an inner channel 421 and an outer channel 422. The inner channel 421 of the center nozzle is retractable relative to the outer channel 422 in a direction away from the burner's outlet plane 423. The center nozzle and / or the inner channel 421 can be moved independently along the burner's axis. Although omitted in the figures, the center nozzle may include an ignition source and / or a flame scanning device, such as... Figure 2 As shown. The outlet of the central channel 401 can retract relative to the outlet of the annular channel 403 in a direction away from the outlet plane 423 of the burner. During heating mode, heating fuel 409 can be supplied via the inner channel 421 of the central nozzle, and heating mode oxygen 418 can be supplied via the outer channel 422 of the central nozzle. Air 411 can be supplied via both the central channel 401 and the annular channel 403. Delivering air via both the central channel 401 and the annular channel 403 reduces the airflow velocity at the outlet plane 423, which reduces both the required air pressure (thus reducing compression costs) and the risk of flame blowout or extinguishing (improving flame stability).

[0039] Figure 4B It shows Figure 4A A variation thereof, wherein one or more swirl vanes 424 are attached to an outer channel 422 of the central spray gun, the outer channel 422 extending at least partially into the central channel 401. In at least some embodiments, one or more swirl vanes 424 may be attached to the central channel 401. In cases where the central spray gun comprises a single channel, one or more swirl vanes 424 may be attached to the outermost channel of the central spray gun. For example, Figure 2 A and Figure 2 The embodiment shown in B may have one or more swirl vanes attached to a central nozzle, which extend at least partially into the central channel 201. The one or more swirl vanes 424 impart swirl to air 411 in heating mode and to oxygen in oxygen-fuel mode, which improves mixing in the flame.

[0040] Figure 4C enlarge Figure 4BThe tip of the multi-functional burner is shown to illustrate the effect of one or more swirl blades 424 on the flame. In oxygen-fuel mode, the swirl imparted to the oxygen flowing through the central channel creates radial expansion of the flame, which in turn generates an internal or central flow recirculation zone 425 within the flame. Recirculation has a positive effect by improving mixing, which reduces soot formation in the flame and minimizes flame length; however, the risk is that recirculation may cause the flame to be pulled back too far from the tip of the multi-functional burner, such that the flame impacts the metal of the multi-functional burner and causes damage, or at least increases the surface temperature and heat flux to the components of the burner nozzle compared to the non-swirl case.

[0041] Alternative embodiments of one or more swirl blades designed to mitigate the aforementioned risks are in Figure 4D1 As shown in, and in Figure 4D2 The image is magnified above. Here, one or more swirl vanes 424 are offset radially from the outer channel of the central nozzle. In at least some embodiments, this offset is achieved by mounting the one or more swirl vanes on a hub 426, which is offset from the outer channel of the central nozzle. The annular gap 427 between the one or more swirl vanes 424 and the outer channel 422 of the central nozzle allows a portion of the oxygen to create a slipflow around the one or more swirl vanes 424 during oxygen-fuel mode.

[0042] Figure 4E Enlarge the tip of the multi-functional burner in Figure 4D to show the effect of the annular gap 427 on the flame. The slipstream 428 of non-swirling oxygen reduces the magnitude of the heat flux returning from the flame to the multi-functional burner nozzle by pushing the inner recirculation zone 425 away from the multi-functional burner nozzle. Therefore, the annular gap reduces or eliminates the risk of the flame impinging on the multi-functional burner nozzle while maintaining the benefits of improved flame mixing to reduce soot formation and flame length. The same effect can also be observed in a single channel in a center lance (e.g., see...). Figure 8B ).

[0043] Figure 5 enlarge Figure 2 The tip of the multi-functional burner defines key geometric parameters for controlling the performance of the multi-functional burner. ox,out It is the inner diameter of the central passage 501 at the exit, d fuel It is the inner diameter of the center spray gun 505 at the exit, and X out It is the length by which the outlet of the center spray gun 505 retracts relative to the outlet of the center channel 501.

[0044] For D ox,out / d fuel For burners with a velocity less than 1.5, for example, when the fuel nozzle exit velocity is increased during heating mode by d fuelTo reduce X during heating mode to prevent the flame from being blown out. out / d fuel It could be a very small value. The risk of damage to the center nozzle 505 during oxygen-fuel mode can be mitigated by removing the center nozzle 505 during oxygen-fuel mode or by using a retraction mechanism to retract the center nozzle 505 at the end of heating mode. Figure 6 A cross-sectional side schematic of a POx burner with a center nozzle 605 on a drive mechanism (not shown) is shown. This drive mechanism is used to move the center nozzle toward the multi-function burner outlet plane 623 during heating mode and away from the multi-function burner outlet plane 623 during oxygen-fuel mode. Gasket seals 630, such as O-rings or packing glands, can be used to prevent gas leakage around the outer wall of the center nozzle. Figure 7 An example of a drive mechanism is shown, which utilizes a pneumatic cylinder 631 to move a plate 632 fixed to a center nozzle relative to a plate 633 fixed to a multi-functional burner. In at least some embodiments, the drive mechanism is radially offset from the central axis of the multi-functional burner, allowing the flame scanning device to have a clear line of sight along the center nozzle.

[0045] Figure 8A Enlarge the tip of the multi-functional burner in Figure 4D to define the key geometric parameters for controlling the performance of the multi-functional burner. D1 is the inner diameter of the outer channel 822 of the center nozzle 805, d fuel It is the inner diameter of the inner channel 821 of the center spray gun 805, and X hub It is the length by which the outlet of the inner channel 821 of the center spray gun 805 retracts relative to the outlet of the outer channel 822 of the center spray gun 805. A swirl It is the cross-sectional flow area of ​​one or more swirl blades 824, and A gap It is the cross-sectional flow area of ​​the annular gap 827. In at least some embodiments, A gap / A swirl The ratio is in the range of 0.05 to 0.75, or 0.1 to 0.5.

[0046] Figure 8B yes Figure 8A A variant of this design, in which the center spray gun 805 has a single channel and retracts from the outlet of the center channel 801. The length from the outlet of the center spray gun 805 to the outlet of the center channel 801 is x. n The diameter of the outlet of the center spray gun 805 is D1. x is in the range of 0.25 to 2.0. nThe value of / D1 can improve the development of the flame jet and reduce the risk of significant radial flame expansion before the flame leaves the multi-functional burner nozzle and enters the reactor. One or more swirl blades 824 can be fixed to the outer wall of the central channel 801 and to the outer surface of the circumferential hub. When the circumferential hub is used to mount one or more swirl blades 824, the annular gap can be defined as the space between the circumferential hub and the central spray gun 805. As... Figure 8A As shown, in at least some embodiments, A gap / A swirl The ratio is in the range of 0.05 to 0.75, or 0.1 to 0.5. The diameter of the hub is D. h The diameter of the central channel, which can accommodate one or more swirl vanes 824, is D. ox The center spray gun 805 may terminate in a portion of the center channel 801 that is wider than the outlet of the center channel 801; that is, the cross-sectional flow area of ​​the center channel 801 immediately downstream of the outlet of the center spray gun 805 may be greater than the cross-sectional flow area of ​​the center channel 801 at its outlet. The center spray gun 805 may terminate at an axial position upstream of the outlet of the circumferential hub. The center spray gun 805 may terminate at an axial position downstream of the inlet of the circumferential hub.

[0047] In oxygen-fuel mode, the center nozzle can provide an alternative fuel source, such as... Figure 9 As shown. In this configuration, primary fuel 912 is supplied via an annular channel 903, and oxygen 910 is supplied via a central channel 901, as previously described. However, instead of retracting, removing, or isolating the central nozzle 905, the central nozzle 905 delivers auxiliary fuel 935 to the multi-functional burner. In at least some embodiments, auxiliary fuel 935 has a higher calorific value than primary fuel 912. In at least some embodiments, auxiliary fuel 935 is a gaseous fuel, and primary fuel 912 is a liquid-phase hydrocarbon and / or solid-phase hydrocarbon in a liquid slurry. Auxiliary fuel 935 can stabilize the combustion of primary fuel 912 and / or reduce soot formation. The beneficial effects may be particularly pronounced when primary fuel 912 is operating in a reduced-flow mode, in which the flow rate of primary fuel 912 is less than 50% or less than 20% of the burner's design value for the oxygen-fuel mode. Typically, existing POx burners in low-mode conditions experience low momentum, leading to incomplete mixing and poor flame penetration into the reactor. This results in high soot formation and low carbon conversion efficiency, where carbon conversion efficiency is defined as 100% minus the percentage of unreacted primary fuel. However, we have found that when used in conjunction with any embodiment of a multi-fuel burner, Figure 9Combustions employing auxiliary fuels produce very low soot formation and high carbon conversion efficiency across a wide range of primary fuel flow rates (gas, liquid, solid, or any combination of phases). The use of auxiliary fuel 935 can also be particularly effective when the primary fuel is difficult to ignite and burn, such as petroleum coke, anthracite, high-moisture fuels, or gaseous fuels with higher calorific values ​​below approximately 500 Btu / scf. Auxiliary fuels may have many other beneficial uses, which are not explicitly stated herein.

[0048] Figure 10 A cross-sectional side view of a multi-functional burner is shown, wherein a gaseous auxiliary fuel 1035 is supplied via a central nozzle 1005, oxygen 1010 is supplied via a central channel 1001, and the main fuel 1012 is supplied in an annular channel 1003. The main fuel 1024 may be a liquid hydrocarbon, a solid hydrocarbon, or a combination of both in a liquid slurry. The central channel includes one or more swirl vanes 1024 with an annular gap 1027 to improve flame mixing without impinging the flame on the tip of the multi-functional burner. The combination of the gaseous auxiliary fuel 1035 and the one or more swirl vanes 1024 in the central channel 1001 significantly improves the combustion efficiency of liquid and / or solid hydrocarbons, a common challenge in POx reactors.

[0049] Any of the multi-functional burners described in this disclosure can be used in two modes: a heating mode for bringing the POx reactor above the auto-ignition temperature of the main fuel, and an oxygen-fuel mode for partially oxidizing the main fuel into syngas.

[0050] The heating mode includes the following steps: igniting heating fuel to produce a flame in the presence of oxygen, surrounding the flame with flowing air, detecting the presence of the flame with a flame scanning device, measuring the temperature of the POx reactor (which may be a single temperature measurement of the furnace refractory or an average of temperature measurements from different locations within the reactor), and adjusting the flow rates of the heating fuel and oxygen to achieve a desired temperature-time relationship. In at least some embodiments, the multi-functional burner operates at or near ignition in the presence of excess oxygen from both air and / or oxygen streams. The equivalence ratio of the multi-functional burner is defined as the ratio of fuel to oxygen divided by the stoichiometric ratio of fuel to oxygen, where both fuel and oxygen are defined as the total amount of fuel and oxygen introduced into the multi-functional burner through all channels, such as both air and oxygen streams. A fuel-rich flame has an equivalence ratio greater than 1, and a fuel-lean flame has an equivalence ratio less than 1. The equivalence ratio of the multi-functional burner during the heating mode may be less than 0.5, less than 0.4, or less than 0.3. In at least some embodiments, the equivalence ratio gradually increases with increasing POx reactor temperature but remains below 1 during the heating mode. Specifically, while the equivalence ratio can be controlled by varying the flow rates of air, oxygen, and / or heating fuel, in at least some embodiments, the equivalence ratio is controlled by varying only the flow rate of the heating fuel. This is done to minimize variations in the overall flow rate of the multi-functional burner, which is primarily related to the air flow. Thus, by maintaining a nominally constant air flow rate, the flame momentum and therefore the heat distribution remain substantially constant throughout the heating mode. Furthermore, it has been found that flame stability can be ensured with a substantially constant oxygen flow rate throughout the heating mode. Therefore, it is optimal to simultaneously control reactor heating and flame stability by setting both the air and oxygen flow rates to substantially constant values ​​while varying the fuel flow rate (and indirectly, the equivalence ratio) shortly after flame ignition in the heating mode. This prescribed variation of the equivalence ratio during the heating mode improves the controllability of the POx reactor temperature as a function of time, compared to methods where the equivalence ratio is kept constant and the overall flow rate of the multi-functional burner is significantly varied.

[0051] When the temperature of the POx reactor is significantly higher than the auto-ignition temperature of the main fuel (e.g., high enough to remain above the auto-ignition temperature of the main fuel after switching burner modes and pressurizing the reactor), the multi-functional burner can be switched from heating mode to oxygen-fuel mode by first cutting off the supply of air, oxygen, and heating fuel. The temperature at which the multi-functional burner can be switched is determined by process operation requirements and can exceed 1100°C or 1400°C. The annular channel of the multi-functional burner is then reconfigured to accept the main fuel flow, for example, by closing one or more valves on the air supply and opening one or more valves on the main fuel flow supply. The pipeline can be purged with inert gas as needed, for example, when the pipeline is switching from fuel to air or from air to fuel.

[0052] In at least some embodiments, the supply of heating fuel is then disconnected from or precisely isolated from the multi-functional burner. The multi-functional burner can then be restarted by allowing the main fuel to flow through an annular channel and oxygen through a central channel. At least a portion of the oxygen may contact one or more swirl vanes to impart swirl motion to the oxygen. The equivalence ratio of the multi-functional burner during oxygen-fuel mode can range from 2.5 to 5.0. This will produce a flame in the reactor when the reactor is above the auto-ignition temperature of the main fuel. The reactor can then be pressurized to the operating pressure for oxygen-fuel mode, typically greater than or equal to 10 bar. Oxygen-fuel mode continues to cause the main fuel to react with oxygen at a temperature and increased pressure above the auto-ignition temperature to produce syngas.

[0053] In at least some embodiments, when the multi-functional burner switches from heating mode to oxygen-fuel mode, the heating fuel is replaced with auxiliary fuel. This does not need to be changed if the auxiliary fuel and heating fuel come from the same source. When auxiliary fuel is used, the oxygen-fuel mode also includes an ignition source near the exit plane of the center nozzle, wherein the exit plane of the center nozzle is at a certain angle X. out / d fuel The passageway retracts upstream from its exit plane, as... Figure 5 As defined herein, the auxiliary fuel flowing through the center burner forms a flame immediately adjacent to the outlet of the center burner. Note that ignition of the auxiliary fuel upstream of the center channel outlet is crucial to ensuring the benefits of the auxiliary fuel as presented herein. The combustion rate of the auxiliary fuel can be controlled within the range of 5% to 25% of the combustion rate of the primary fuel. The combustion rate is defined herein as fuel flow rate multiplied by fuel calorific value (i.e., higher calorific value HHV, or lower calorific value LHV). Auxiliary fuel may be preferentially used when the total combustion rate of the fuel through the multi-functional burner is less than or equal to 50% of the design rate, or less than or equal to 20% of the design rate. The auxiliary fuel may be of the same composition as the primary fuel. The auxiliary fuel may be gaseous, and the primary fuel may be gaseous, liquid, and / or solid.

[0054] In some embodiments, the multi-functional burner may not require any hardware transition from an oxidizing environment in heating mode to a reducing environment in oxygen-fuel mode. With the multi-functional burner at atmospheric pressure or slightly above atmospheric pressure, the heating method can be initiated by injecting oxygen in the central channel at a substoichiometric ratio and auxiliary fuel in the central nozzle to maintain a reducing atmosphere. The equivalence ratio of auxiliary fuel to oxygen can be kept below 1, i.e., it can be lean fuel. The flame can be started by stimulating an ignition source near the burner outlet before or after the oxygen and central fuel flow is initiated. The flame can then be verified by a flame scanning device. The main fuel can then be supplied to the annular channel such that the overall equivalence ratio of the main fuel and auxiliary fuel to oxygen is less than 1 (lean fuel) and / or the flow rate of the auxiliary fuel can be greater than the flow rate of the main fuel. The reactor can be pressurized or kept near atmospheric pressure by increasing the auxiliary fuel, main fuel, and oxygen proportionally at the same substoichiometric ratio to increase the burner's heat load and maintain a constant reducing atmosphere during reactor heating. The flame scanning device and / or ignition source can be isolated from the reactor to prevent damage from pressure increases. When the reactor temperature reaches the target temperature, the heating mode can be seamlessly switched to the oxy-fuel mode startup by increasing the flow rate of the main fuel to increase the overall equivalence ratio of the main fuel and auxiliary fuel to oxygen to greater than 1 (rich fuel). The target temperature can be the auto-ignition temperature of the main fuel. The target temperature can be in the range of 1100°C to 1400°C. The mass flow rates of auxiliary fuel, main fuel, and oxygen can be increased proportionally with the reactor pressure to maintain a substantially constant rate in the burner and a substantially constant gas residence time in the reactor. This avoids any disruption caused by sudden increases in production and pressure in the system, both of which can be adverse effects of existing methods for switching from an oxidizing environment in the heating mode to a reducing environment in the oxy-fuel mode. Compared to existing methods, the seamless switch from the heating mode to the oxy-fuel mode minimizes the formation of solid carbon byproducts, which can cause sudden and significant increases in production, resulting in high rates and low residence times during the startup of the oxy-fuel mode, often leading to scaling in downstream equipment such as waste heat boilers. Those skilled in the art will understand the safety and performance benefits provided by eliminating the need to switch from an oxidizing heating mode to a reducing start-up oxy-fuel mode.

[0055] During oxy-fuel mode, the auxiliary fuel flow through the central injector can continue. By reacting the auxiliary fuel with oxygen flowing through the central channel, making the auxiliary fuel-oxygen mixture lean (with an equivalence ratio of less than 1.0), the mixture containing excess oxygen can be heated to a greater extent than is achievable by known preheating methods upstream of the oxy-fuel burner. The resulting heated mixture flow can then experience a rapid increase in velocity due to its elevated temperature and therefore lower density, and serves as a much more efficient oxidant for the primary fuel, significantly reducing soot production, increasing the conversion of the primary fuel to syngas, and optimizing the distribution of gasification products. The heated mixture also allows for the consumption of low-value feedstocks, such as biogas or low-calorific-value syngas, in the reactor. Due to the use of the heated auxiliary fuel-oxygen mixture, the feed injector can have enhanced regulation capabilities. The primary fuel flow rate can be reduced to lower the overall equivalence ratio of primary fuel and auxiliary fuel to oxygen to less than 1, allowing the reactor to return to heated mode or enter standby mode. The flow rate of the main fuel can be reduced to less than 50% of the burner's design value for oxygen-fuel mode, or less than 20% of that design value. Reducing the main fuel flow rate can lower the furnace temperature below the auto-ignition temperature of the main fuel. This operating method will allow for continuous cycling from heating mode to operating mode without the need to remove or replace a separate preheating burner.

[0056] In at least some embodiments, a moderating agent such as steam or carbon dioxide may be introduced into the burner to reduce NOx emissions. Any channel may be used to inject the moderating agent, including a central spray gun, an annular channel, and / or additional channels outside the annular channel.

[0057] The swirl vanes disclosed herein can also be utilized in oxy-fuel burners that lack the multi-functionality enabled by a center nozzle. The general concept of imparting swirl motion to a portion of the oxygen flow to improve mixing in the flame, while simultaneously bypassing a portion of the oxygen flow closer to the burner's centerline to push the recirculation zone away from the nozzle tip, would benefit any oxy-fuel burner. However, we have found that the physical means to achieve both effects may need to be adapted to oxy-fuel burners lacking multi-functionality.

[0058] Figure 11 A cross-sectional side schematic diagram of a central channel with one or more swirl vanes 1124 for an air-fuel combustor, as described by Beér and Chigier (Combustion Aerodynamics, 1983), is shown. One or more swirl vanes 1124 are mounted on a diameter D. s On the axis, and the diameter of the central channel is D. ch . Figure 12 It shows Figure 11A variant in which the central channel 1201 can be used to deliver oxygen 1210 to a reverse diffusion oxygen-fuel combustor, in which oxygen 1210 combines with fuel 1212 delivered through the surrounding annular channel 1203. Two drawbacks exist. Figure 11 and Figure 12 In the depicted central channel, one defect is the tendency for thermal damage to the swirl vanes caused by the extremely high temperature of the oxygen-fuel flame. We have found that by retracting the swirl vanes from the oxygen nozzle outlet plane back to a plane with a larger cross-sectional area, such as by employing... Figure 13 The depicted converging nozzle can compensate for this deficiency. When relatively cold oxygen 1310 flows through the swirl vanes 1324, the retracting... Figure 13 The converging nozzle outlet effectively protects the swirl blades 1324 from the significant portion of flame radiation. We also note that, although... Figure 13 The converging nozzle is symmetrical, but in at least some embodiments, the convergence can be asymmetrical, i.e., the wall can be inclined inward at a small angle or not inclined at all on one or more sides of the channel. In at least some embodiments, the convergence can be an abrupt change with a 90° bend to transition to a smaller cross-sectional area. In at least some embodiments, the convergence can be curved rather than linear.

[0059] Before describing the second defect, we note that each swirl vane can be deflected from the axis of the central channel by a swirl angle α, which can be the same for each vane, or one or more vanes can have different swirl angles. This one or more swirl vanes can be attached to a central axis, which can be solid or hollow. This one or more swirl vanes can terminate upstream at a point with a decreasing cross-sectional area. The distance from the termination of this one or more swirl vanes to the exit of the converging nozzle is defined as X. V And the diameter of the converging nozzle outlet is defined as D. O2,exit In at least some embodiments, the ratio X V / D O2,exit A value less than or equal to 10 is used to prevent significant loss of swirl intensity due to viscous dissipation. We also note that the intensity of the swirl imparted to the fluid in the central channel can be quantified by the swirl number S, which is defined as the axial flux G of the angular momentum. φ The ratio of the product of the axial thrust Gx and the burner nozzle outlet radius R. When S=G φ / G x When R is less than 0.6, the fluid is in a weak swirling state, and when S is greater than 0.6, the fluid is in a strong swirling state. According to Beér and Chigier, a system in a weak swirling state cannot induce internal recirculation, and therefore a flame in a weak swirling state "has only limited practical benefits." Figure 14 The streamlines of the flow field with a swirling jet having an S of 1.57 are shown. In this strong swirling state, the internal recirculation zone (IRZ) can be clearly seen to both improve mixing within the flame and extend upstream to a point very close to the exit plane, where the axial distance is equal to 0.

[0060] Regarding the prior art, we assert that the basis for utilizing swirl is primarily in air-fuel combustion, where the flame temperature is typically on the order of 1000°C lower than the flame temperature produced by the oxygen-fuel combustion applied in this invention. Furthermore, although... Figure 14 The described characteristics of the IRZ may be suitable or even desirable in some air-fuel flames, but if applied to oxy-fuel combustion, the proximity of the upstream tip of the IRZ to the burner nozzle will easily lead to nozzle overheating. This is the second drawback of the prior art. That is, while the presence of the IRZ is indeed beneficial as it enhances reactant mixing, improves carbon conversion efficiency, and minimizes soot formation within the flame, the proximity of the upstream location of the IRZ to the nozzle outlet is unacceptable for a wide range of oxy-fuel flames.

[0061] Figure 15 It shows Figure 11 A variant of the IRZ (Inlet / Outlet) is provided, wherein one or more vent holes are located upstream of one or more swirl vanes. The central shaft is hollow, allowing fluid 1510 to travel from the central channel into one or more vent holes 1539 and exit the central shaft nozzle outlet, thus bypassing one or more swirl vanes 1524. The bypassing of one or more swirl vanes 1524 allows for the realization of the benefits of improved mixing in the flame while mitigating the risk of pushing the flame back onto the burner. The central channel can be configured to deliver fuel or oxygen, while the surrounding annular channel is configured to deliver oxygen or fuel, respectively. We have found that the use of appropriately configured vent holes in the hollow shaft, in combination with oxygen delivery nozzles, is the most effective system for obtaining the benefits of swirl while avoiding the aforementioned drawbacks. This is because a) the oxygen vent flow exits the shaft substantially along the longitudinal axis of the burner, and b) it is accelerated within the converging section upon exiting the shaft. Therefore, even a relatively small vent flow rate (compared to the total oxygen flow in the nozzle) has an amplifying effect in the back propagation of the IRZ, which is centered along the burner axis.

[0062] The driving force for the venting flow is the back pressure generated by the one or more swirl vanes, which forces a portion of the fluid flow through the central channel into the one or more venting orifices. This portion is a function of the following: the number and size of the one or more orifices, the number of swirl vanes, the swirl vane angle α, the position of the one or more orifices relative to the one or more swirl vanes, the cross-sectional area of ​​the central channel at the one or more swirl vanes, the cross-sectional area of ​​the central channel at the nozzle outlet, and the total flow rate of the fluid in the central channel. In at least some embodiments, the total flow rate through the one or more venting orifices is in the range of approximately 1% to 50%, or 5% to 25%, of the total flow rate through the central channel upstream of the one or more venting orifices.

[0063] Figure 16 It shows Figure 15 A variation thereof, wherein one or more swirl blades have varying swirl blade angles along their length. The trailing edge 1651 of one or more swirl blades 1624 may have a swirl blade angle α. The leading edge 1652 of one or more swirl blades 1624 may have a swirl blade angle less than α. Figure 16 In the embodiment shown, there is a segment starting at the leading edge 1652 with a length of L. v Furthermore, the swirl blade angle is zero. In at least some embodiments, the swirl blade angle can gradually change from the leading edge 1652 to the trailing edge 1651.

[0064] Aspect 1: A multi-functional burner comprising: a tip configured to discharge a flame into a reactor; a center nozzle configured to deliver at least one fluid into the reactor via an outlet plane; a center channel surrounding the center nozzle and configured to deliver at least one fluid into the reactor via an outlet plane; and an annular channel surrounding the center channel and configured to deliver at least one fluid into the reactor via an outlet plane.

[0065] Aspect 2: According to the multi-functional burner of aspect 1, wherein the central spray gun includes an ignition device configured to ignite a flame near the end of the central spray gun.

[0066] Aspect 3: The multi-functional burner according to aspect 1 or aspect 2, wherein the outlet of the annular channel forms an angle θ of less than about 45° with respect to the central axis of the multi-functional burner.

[0067] Aspect 4: The multi-functional burner according to any one of aspects 1 to 3, wherein the cross-sectional flow area of ​​the central channel immediately downstream of the outlet of the central spray gun is greater than the cross-sectional flow area of ​​the central channel at the outlet of the central channel.

[0068] Aspect 5: The multi-functional burner according to any one of aspects 1 to 4, wherein the center spray gun includes an inner channel and an outer channel.

[0069] Aspect 6: A multi-functional burner according to any one of aspects 1 to 5, wherein the annular channel is configured to switch between fluid sources during operation of the multi-functional burner.

[0070] Aspect 7: A multi-functional burner according to any one of aspects 1 to 6, wherein the central channel includes one or more swirl vanes configured to impart swirling motion on at least a portion of the fluid traveling through the central channel.

[0071] Aspect 8: The multi-functional burner according to aspect 7, wherein the central channel includes an annular gap located between the central nozzle and the one or more swirl vanes, the annular gap being configured to bypass a portion of the fluid traveling through the central channel around the one or more swirl vanes.

[0072] Aspect 9: The multifunctional burner according to aspect 8, wherein the ratio of the cross-sectional flow area of ​​the annular gap to the cross-sectional flow area of ​​the one or more swirl blades is in the range of 0.05 to 0.75.

[0073] Aspect 10: The multi-functional burner according to aspect 8 or aspect 9 further includes a circumferential hub; wherein one or more swirl blades are fixed to the outer wall of the central channel and the outer surface of the circumferential hub; wherein the annular gap is defined as the space between the circumferential hub and the central spray gun.

[0074] Aspect 11: The multi-functional burner according to aspect 10, wherein the center spray gun terminates at an axial position upstream of the outlet of the circumferential hub.

[0075] Aspect 12: A method for operating a multi-functional burner, the method comprising a heating mode and an oxygen-fuel mode; wherein the heating mode comprises feeding air through an annular channel, feeding oxygen through a central channel within the annular channel, and feeding heating fuel through a central nozzle within the central channel to generate a flame extending into a furnace having a temperature; wherein the heating mode switches to the oxygen-fuel mode after the furnace temperature exceeds the auto-ignition temperature of the main fuel; and wherein the oxygen-fuel mode comprises feeding the main fuel through the annular channel and feeding oxygen through the central channel within the annular channel.

[0076] Aspect 13: The method according to aspect 12 further includes contacting at least a portion of the oxygen with one or more swirl blades.

[0077] Aspect 14: According to the method of aspect 13, the method further includes bypassing a portion of the oxygen through an annular gap located between the one or more swirl vanes and the center spray gun.

[0078] Aspect 15: The method according to any one of aspects 12 to 14, wherein the center spray gun retracts in an axial direction away from the tip of the multi-functional burner when the heating mode is switched to the oxygen-fuel mode.

[0079] Aspect 16: A method for operating a multi-functional burner, the method comprising feeding main fuel through an annular channel, feeding oxygen through a central channel within the annular channel, and feeding auxiliary fuel through a central nozzle within the central channel to generate a flame extending into a furnace having temperature and pressure; wherein the equivalence ratio of the auxiliary fuel to oxygen is maintained below 1.

[0080] Aspect 17: The method according to aspect 16 further includes increasing the flow rate of the primary fuel to increase the overall equivalence ratio of the primary fuel and auxiliary fuel to oxygen to greater than 1.

[0081] Aspect 18: According to the method of aspect 17, the increase in the flow rate of the main fuel occurs after the furnace temperature exceeds the auto-ignition temperature of the main fuel.

[0082] Aspect 19: The method according to any one of aspects 16 to 18, the method further comprising reducing the flow rate of the primary fuel to reduce the overall equivalence ratio of the primary fuel and auxiliary fuel to oxygen to less than 1.

[0083] Aspect 20: According to the method of aspect 19, the reduction in the flow rate of the main fuel reduces the furnace temperature to below the auto-ignition temperature of the main fuel.

[0084] Aspect 21: The method according to aspect 19 or aspect 20, wherein the flow rate of the main fuel is reduced to less than 50% of the design value for the flow rate of the main fuel.

[0085] Aspect 22: The method according to any one of aspects 16 to 21, wherein the flow rates of oxygen, primary fuel and auxiliary fuel, furnace temperature and furnace pressure are altered to maintain a substantially constant residence time of the gas in the furnace.

[0086] Aspect 23: The method according to any one of aspects 16 to 22, the method further comprising contacting at least a portion of the oxygen with one or more swirl blades.

[0087] Aspect 24: According to the method of aspect 23, the method further includes bypassing a portion of the oxygen through an annular gap located between the one or more swirl vanes and the center spray gun.

[0088] Aspect 26: An oxygen nozzle comprising: a hollow central shaft including one or more swirl vanes and one or more vent holes positioned upstream of the one or more swirl vanes; a central channel surrounding a central nozzle, the central channel being configured to deliver oxygen to a reactor through an outlet plane; wherein the cross-sectional area of ​​the central channel at the termination of the one or more swirl vanes is greater than the cross-sectional area of ​​the central channel at the outlet plane of the central channel.

[0089] Aspect 27: The oxygen nozzle according to aspect 26, wherein the one or more vents are configured to deliver a flow rate of oxygen through the one or more vents, the flow rate of oxygen being in the range of about 1% to 50% of the total flow rate of oxygen through the central channel upstream of the one or more vents.

[0090] Aspect 28: An oxygen nozzle according to aspect 26 or aspect 27, wherein the one or more swirl vanes include a leading edge and a trailing edge relative to the direction of oxygen flow; and wherein the swirl angle at the trailing edge of the one or more swirl vanes is greater than the swirl angle at the leading edge of the one or more swirl vanes.

[0091] Example according to Figure 13 (Solid wall) and Figure 15(Break Hole) The oxygen-fuel burner is constructed with a central channel. With a simple hardware modification, the "break hole" burner is configured to deliver approximately 10 or 15% of the total oxygen flow through one or more break holes. Under a wide range of commercially viable design and operating conditions, the flame front of the "break hole" burner is both stable and separated from the nozzle tip compared to a "solid wall" burner. Compared to a "solid wall" burner, the "break hole" burner offers lower surface temperatures at the burner nozzle, lower heat flux delivered to the burner surface, lower surface temperatures on one or more swirl vanes, reduced burner noise, improved flame stability, and more predictable burner performance. Furthermore, it was found that the flame can still generate an IRZ even when introducing a break hole into the burner design reduces the swirl number S for air-fuel flames, as cited by Beér and Chigier, to below 0.6. The formation of IRZ is likely due to the much faster flame expansion that occurs in swirling oxygen-fuel combustion compared to swirling air-fuel combustion, thus indicating the need for new design principles for swirling in oxygen-fuel flames.

[0092] Experimental tests were conducted on three embodiments of this disclosure: using, as shown in the figure Figure 2 The example of a burner without swirl, and its application as shown Figure 8B The burner shown is a full-swirl case and a partial-swirl case. Both the full-swirl and partial-swirl cases use blades with a swirl angle of 42.5°. The partial-swirl case has A... gap / A swirl The ratio is 0.3 and x n / D1=1. This full vortex case can be described as... Figure 8B A gap / A swirl =0 and x n / D1=0. All three burners have a convergence angle θ of 30° and utilize natural gas as both primary and auxiliary fuel. Figure 17 A diagram of an example flame from a test with an inner flame 1751 and an outer flame 1753 is shown. The outer flame angle β can be defined as the angle between the outer edge of the outer flame 1753 and the burner axis. Figure 18 The inner flame 1851 is shown in detail. The radial nozzle flame gap Δr can be defined as the distance between the outer edge of the inner flame 1851 and the inner edge of the outlet of the central channel. Figure 19 The image shows the outer flame that has been lifted off the burner's outlet plane. Flame lift-off distance ΔX lift It can be defined as the axial distance from the burner's outlet plane to the beginning of the outer flame. Measured performance parameters include: the wall temperature T near the nozzle tip. tip The wall temperature is in the central channel at X out / Dox,out The values ​​measured at 0.33 are: outer flame angle β; radial nozzle-flame gap Δr; and flame lift-off distance ΔX. lift .

[0093] Figure 20 The dimensionless wall temperature (T) is shown. tip -T oxygen ) / (T tipmax -T oxyge n) is a function of the equivalence ratio in the internal flame, where T oxygen It is the temperature of the oxygen fed into the burner and T tipmax This is the maximum wall temperature observed during the experiment. It can be noted that as the equivalence ratio approaches uniformity from the lean (fuel) side, all center channel configurations confirm the same trend in temperature with increasing inner flame equivalence ratio. This is because the flame temperature increases during this trend, while the amount of unreacted "cold" oxygen around the flame periphery decreases due to fuel consumption. Going further to the comparison, we note, unexpectedly, that the partially swirling design exhibits a lower nozzle tip temperature than the fully swirling or undisturbed design, and the highest temperature occurs in the undisturbed case. As an explanation, we first note that one effect of the presence of oxygen swirl is to increase the velocity of oxygen leaving the center channel. To some extent, some cold, i.e., unreacted oxygen remains, and the higher oxygen velocity will enhance convective cooling of the nozzle tip. This explains why the nozzle tip temperature without swirl is the highest of the three, but does not help explain the fact that the partially swirling design experiences the lowest temperature. One possible explanation involves delayed mixing between the inner flame and the (outer) swirling portion of oxygen flowing within the "mixing" partially swirling nozzle. This delay can be facilitated by a circumferential hub that separates the axial flow and swirling portions of the oxygen flow, and can be further amplified by the axial positioning of a central auxiliary fuel injector, the exit plane of which is located upstream of the exit plane of the circumferential hub. The effect of this delay will be a reduction in the rate at which the auxiliary fuel burns within the nozzle and an increase in the portion of unreacted “swirling” oxygen leaving the nozzle, resulting in enhanced cooling of the nozzle tip.

[0094] The radial nozzle flame gap Δr can be an important parameter for burner durability, preventing flame impact against the inner surface of the burner. High-quality images were captured during testing with the auxiliary fuel to oxygen equivalence ratio maintained at 0.2. To facilitate optical measurements, the main fuel was not used during these tests. The dimensionless radial nozzle flame gap is equal to 2*Δr / D. ox,outThe value is 0.34 in the non-swirling case, 0.36 in the partially swirling case, and 0.25 in the fully swirling case. We note that the radial nozzle flame gap is the highest in the partially swirling configuration and the lowest in the fully swirling configuration. The radial nozzle flame gap is driven by the mixing rate between the auxiliary fuel and oxygen within the burner nozzle. We specifically expect that a higher mixing rate will translate into a smaller radial gap between the flame edge and the inner wall of the nozzle. The results therefore indicate that the fully swirling case will have the highest rate of oxygen and auxiliary fuel mixing before exiting the nozzle, and the partially swirling case will have the lowest rate. This would also be an unexpected result without the previous nozzle temperature results and accompanying explanation. That is, it is thought that the increased oxygen velocity in the swirling section, combined with the axial / radial separation between the axial and swirling oxygen flow sections, both slows down the auxiliary fuel consumption rate and increases the convective cooling of the oxygen nozzle. Therefore, compared to the full swirl case, the lower fuel consumption rate and measured wall temperature inferred in this partial swirl case are consistent with the larger radial nozzle flame gap.

[0095] The outer flame angle β is known to indicate the rate of heat transfer from the flame to the burner nozzle and is therefore a determinant of burner service durability. A larger β value can correspond to a larger rate of heat transfer from the flame to the burner nozzle and a shorter burner life. The equivalence ratio of the auxiliary fuel / oxygen stream is 0.2, and the equivalence ratio of the combined reactant stream (primary fuel, auxiliary fuel, and oxygen) is 1.0. The outer flame angle β is 23.4° in the undulating case, 15.4° in the partially swirling case, and 27.0° in the fully swirling case. The initial rate of diffusion of the jet flame emanating from the burner nozzle is strongly influenced by both the mixing rate between the reactants and their subsequent chemical reaction rates. Thus, the results indicate that the partially swirling design configuration has the slowest initial mixing rate and chemical reaction rate (i.e., between the primary fuel stream and the auxiliary fuel / oxygen flame). This conclusion, while also unexpected, is consistent with the results previously presented in this paper. Surprisingly, for a given flow rate of reactants, one might expect the relative amount of oxygen swirling to be proportional to the rate of reactant mixing. This would suggest that the full swirling configuration would have the largest diffusion angle, which it does, but it also suggests that the partial swirling configuration would have the second largest diffusion angle. Therefore, the fact that the partial swirling configuration has the lowest diffusion angle must be further explained. When combined with the lower wall temperature and larger radial nozzle-flame gap observed in the partial swirling case, it can be concluded that, under the same auxiliary fuel and oxygen flow rates, the reactions occurring within the partial swirling nozzle are less than those occurring in the non-swirling or full swirling cases. This further suggests that the partial swirling embodiment has the lowest average center flame temperature and therefore a lower designed minimum velocity. In other words, the lower ratio of reaction between auxiliary fuel and oxygen within the partial swirling nozzle produces a lower-temperature lean-fuel (oxygen-rich) flame exiting the nozzle. And for this same embodiment, the lower temperature consequently produces a higher gas density and a lower gas velocity. The lower temperature will therefore correspond to a slower initial reaction rate between the central flame and the main fuel stream, and the lower jet velocity will contribute to the slower initial mixing rate between the central flame and the main fuel, due to the reduced shear between the streams.

[0096] Given the flame lift-off distance ΔX lift This relates to the dynamic stability of the burner, i.e., ΔX liftThe non-zero value of can correspond to the transition state between a stable anchored flame (zero lift-off height) and flame extinction. Furthermore, it has been observed that so-called "lifted" flames are more prone to positional oscillations, which can induce greater temporal instabilities in combustion products, and also result in greater pressure pulsations and noise relative to the behavior of anchored flames. Experiments were conducted for the worst-case lift-off condition, where the equivalence ratio of auxiliary fuel to oxygen was 0.1 and the ratio of auxiliary fuel to main fuel was 0.125. These conditions represent the lowest thermal power and temperature in the central flame and the highest momentum in the main fuel, and therefore represent the maximum probability of dynamic instabilities in the flame. Dimensionless flame lift-off distance (ΔX) lift / D ox,out The value is 0.34 in both the undisturbed and partially swirling cases, and almost twice that in the fully swirling case, at 0.65. The benefits seen in the previous parameters for the partially swirling case are therefore not accompanied by the instability penalty suffered by the fully swirling case. When the experiment was repeated with a nozzle having a convergence angle θ of 0°, the dimensionless flame lift-off distance was zero in all three cases, indicating improved flame stability.

[0097] Although the principles of the invention have been described above in conjunction with preferred embodiments, it should be clearly understood that this description is merely illustrative and not intended to limit the scope of the invention.

Claims

1. A multi-functional burner, the multi-functional burner comprising: A tip, configured to discharge flames into the reactor; A central spray gun, the central spray gun being configured to deliver at least one fluid to the reactor through an outlet plane; A central channel surrounding the central spray gun, the central channel being configured to deliver at least one fluid to the reactor via an outlet plane; and An annular channel surrounding the central channel is configured to deliver at least one fluid to the reactor via an outlet plane.

2. The multi-functional burner of claim 1, wherein the center nozzle includes an ignition device configured to ignite a flame near the end of the center nozzle.

3. The multi-functional burner according to claim 1, wherein the outlet of the annular channel forms an angle θ of less than about 45° with respect to the central axis of the multi-functional burner.

4. The multi-functional burner according to claim 1, wherein the cross-sectional flow area of ​​the central channel immediately downstream of the outlet of the central spray gun is greater than the cross-sectional flow area of ​​the central channel at the outlet of the central channel.

5. The multifunctional burner according to claim 1, wherein the center spray gun includes an inner channel and an outer channel.

6. The multi-functional burner of claim 1, wherein the annular channel is configured to switch between fluid sources during operation of the multi-functional burner.

7. The multifunctional burner of claim 1, wherein the central channel includes one or more swirl vanes configured to impart swirling motion on at least a portion of the fluid traveling through the central channel.

8. The multi-functional burner of claim 7, wherein the central channel includes an annular gap located between the central nozzle and the one or more swirl vanes, the annular gap being configured to bypass a portion of the fluid traveling through the central channel around the one or more swirl vanes.

9. The multifunctional burner according to claim 8, wherein the ratio of the cross-sectional flow area of ​​the annular gap to the cross-sectional flow area of ​​the one or more swirl blades is in the range of 0.05 to 0.

75.

10. The multifunctional burner according to claim 8, wherein the multifunctional burner further comprises a circumferential hub; The one or more swirl blades are fixed to the outer wall of the central channel and the outer surface of the circumferential hub; The annular gap is defined as the space between the circumferential hub and the central spray gun.

11. The multi-functional burner of claim 10, wherein the center spray gun terminates at an axial position upstream of the outlet of the circumferential hub.

12. A method for operating a multi-functional burner, the method comprising: Heating mode and oxygen-fuel mode; The heating mode includes feeding air through an annular channel, feeding oxygen through a central channel within the annular channel, and feeding heating fuel through a central nozzle within the central channel to generate a flame that extends into a furnace with a temperature. The heating mode switches to the oxygen-fuel mode after the furnace temperature exceeds the auto-ignition temperature of the main fuel; and The oxygen-fuel mode includes feeding the main fuel through the annular channel and feeding oxygen through the central channel within the annular channel.

13. The method of claim 12, further comprising contacting at least a portion of the oxygen with one or more swirl blades.

14. The method of claim 13, further comprising bypassing a portion of the oxygen through an annular gap located between the one or more swirl vanes and the center spray gun.

15. The method of claim 12, wherein the center spray gun retracts in an axial direction away from the tip of the multi-functional burner when the heating mode is switched to the oxygen-fuel mode.

16. A method for operating a multi-functional burner, the method comprising: The main fuel is fed through an annular channel, oxygen is fed through a central channel within the annular channel, and auxiliary fuel is fed through a central nozzle within the central channel to generate a flame that extends into the furnace with temperature and pressure. The equivalence ratio of the auxiliary fuel to oxygen is kept below 1.

17. The method of claim 16, further comprising increasing the flow rate of the primary fuel to increase the overall equivalence ratio of the primary fuel and auxiliary fuel to oxygen to greater than 1.

18. The method of claim 17, wherein the increase in the flow rate of the main fuel occurs after the furnace temperature exceeds the auto-ignition temperature of the main fuel.

19. The method of claim 16, further comprising reducing the flow rate of the primary fuel to reduce the overall equivalence ratio of the primary fuel and auxiliary fuel to oxygen to less than 1.

20. The method of claim 19, wherein the reduction in the flow rate of the main fuel reduces the furnace temperature to below the auto-ignition temperature of the main fuel.

21. The method of claim 19, wherein the flow rate of the main fuel is reduced to less than 50% of the design value for the flow rate of the main fuel.

22. The method of claim 16, wherein the flow rates of oxygen, primary fuel and auxiliary fuel, furnace temperature and furnace pressure are altered to maintain a substantially constant residence time of the gas in the furnace.

23. The method of claim 16, further comprising contacting at least a portion of the oxygen with one or more swirl blades.

24. The method of claim 23, further comprising bypassing a portion of the oxygen through an annular gap located between the one or more swirl vanes and the center spray gun.

25. An oxygen nozzle, the oxygen nozzle comprising: A hollow central shaft, the hollow central shaft including one or more swirl vanes and one or more vent holes, the one or more vent holes being located upstream of the one or more swirl vanes; A central channel surrounding a central spray gun, the central channel being configured to deliver oxygen to the reactor through an outlet plane; The cross-sectional area of ​​the central channel at the termination of one or more swirl blades is greater than the cross-sectional area of ​​the central channel at the outlet plane of the central channel.

26. The oxygen nozzle of claim 25, wherein the one or more vents are configured to deliver an oxygen flow rate through the one or more vents, the oxygen flow rate being in the range of about 1% to 50% of the total oxygen flow rate through the central channel upstream of the one or more vents.

27. The oxygen nozzle of claim 25, wherein the one or more swirl blades include a leading edge and a trailing edge relative to the direction of oxygen flow; and The swirl angle at the trailing edge of one or more swirl blades is greater than the swirl angle at the leading edge of one or more swirl blades.

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