Premix combustion method, premix combustor, control system and computer program

Abstract

To achieve stable combustion with ultra-low nitrogen oxide production, the invention relates to a combustion method for combusting a fuel-air mixture (except for gas turbines), comprising: a) fully premixing 100% of a provided air stream (10) for combustion with a (gaseous) fuel (12), wherein step a) comprises: b) adding a first portion (A.1) of the fuel (12) to the air stream (10) in a first premixing zone (14.1), thereby forming a lean fuel-air mixture (16) that is not yet ignitable; and c) mixing one or more remaining portions (A.n) of the fuel (12) into the lean fuel-air mixture (16) in at least one further premixing zone (14.n) spaced apart from the first premixing zone (14.1) in flow direction, to form an ignitable fuel-air mixture (18) with excess air, wherein step c) comprises: d) generating a swirl in the fuel-air mixture (18) formed in the at least one further premixing zone (14.n). The invention also relates to a premix burner (40) configured to perform such premixing and combustion.

Description

Technical Field

[0001] This invention relates to a combustion method using a premixed combustion fuel-air mixture. It also relates to a premixed burner. Finally, it relates to a control system and computer program for such a premixed burner.

[0002] This invention relates to the field of combustion methods for burning gaseous fuels, particularly those used in buildings, ships, commerce and industry, and to the field of burners for performing such combustion methods, as specifically described in references [6] to

[10] . Background Technology

[0003] For technical background information, please refer to the following literature: [1] DE4329 971A1 [2] DE3606625A1 [3] DE1264668B [4] US2007 / 0207426A1 [5] US2004 / 0018461A1 [6] WO2018 / 141647A1 [7] “Technical information monoblock burners – Weishaupt burnerseries monarch® – WM30 350 to 6,200 kW”, Max Weishaupt GmbH brochure, downloaded on November 30, 2023. https: / / www.weishaupt.de / uploads / tx_weishaupt_documents / documents / 83211601. pdf [8] Max Weishaupt GmbH website, product information on Weishaupt burners, WM series monarch®, downloaded on November 30, 2023 from https: / / www.weishaupt.de / produkte / brenner / weishaupt-brenner-typenreihe-wm-monarchr-55-12000-kw [9] Weishaupt WKmono series burners, Max-Weishaupt GmbH company manual, downloaded on November 30, 2023 from https: / / www.weishaupt.de / uploads / tx_weishaupt_documents / documents / 83216401.pdf

[10] Weishaupt Industrial Burners WK Series, Max-Weishaupt GmbH Company Manual, downloaded on November 30, 2023 from https: / / www.weishaupt.de / uploads / tx_weishaupt_documents / documents / 83159801.pdf

[11] Information Sheet No. 66 from the German Federal Association for Heating Industries (BDH), downloaded on November 30, 2023 from https: / / www.bdh-industrie.de / fileadmin / user_upload / Publikationen / Infoblaetter / Infoblatt_Nr_66_NOx-Emission_Feuerungsanlagen_022020.pdf

[12] Wikipedia: Nitrogen Oxides; downloaded November 30, 2023 from https: / / de.wikipedia.org / wiki / Stickoxide

[13] DE4330160A1

[14] WO2021 / 250517A1 According to reference

[14] , premixed burners differ from diffusion burners: premixed burners fully premix the fuel-air mixture before introducing it into the combustion chamber to form the flame; while diffusion burners introduce air and fuel separately into the combustion chamber, where they are then mixed for combustion. Reference

[14] describes a burner for a very specific purpose: pre-treating various steel components before hot-dip galvanizing. This burner can operate in diffusion burner mode, where fuel and air are supplied separately to the combustion chamber; or in premixed mode, where air and fuel are premixed into a fuel-air mixture with excess air before being introduced into the combustion chamber.

[0004] Reference

[13] describes a combustor for a gas turbine equipped with a premixing device that produces a fuel-air mixture that is not yet ignitable, and a fuel injector that extends into the combustion chamber to add additional fuel to produce a flame immediately. The aim is to combine the advantages of a premixed combustor and a nozzle mixing combustor (i.e., a diffusion combustor).

[0005] According to reference [6], to date, premixed burners that premix the fuel-air mixture before introducing it into the flame space have been used to achieve low NOx emissions. In all known premixed burners, a rich fuel mixture is first produced, and then air is added to make it a lean fuel mixture. However, for burners known to date for the above applications, NOx emissions can only be reduced to a certain limit. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus that enable stable combustion of gaseous fuels and produce ultra-low nitrogen oxides.

[0007] To achieve this objective, the present invention provides a combustion method according to claim 1. The premixed burner, as well as the control system and computer program for it, are the subject of the other independent claims.

[0008] Advantageous embodiments are the subject of the dependent claims.

[0009] According to its first aspect, the present invention provides a method for combustion of a fuel-air mixture (a mixture of gaseous fuel and air), comprising: a) 100% of the airflow supplied for combustion is fully premixed with the (gaseous) fuel. Step a) includes: b) In the first premixing zone, a first portion of the fuel is added to the air stream to form a lean fuel-air mixture that is not yet ignitable; and c) In at least one additional premixing zone, one or more remaining portions of the fuel are mixed into the lean fuel-air mixture to produce an ignitable fuel-air mixture with excess air, the additional premixing zone being spaced apart from the first premixing zone in the flow direction. Step c) includes: d) To create a swirling flow in the fuel-air mixture.

[0010] This fully premixed fuel-air mixture flows into the combustion chamber through the outlet opening area and is burned by the flame there.

[0011] In embodiments of the invention, all air supplied for combustion is fully premixed; in particular, homogeneous mixing occurs. In some embodiments, a homogeneous and ignitable fuel-air mixture is produced, wherein fuel and air are homogeneously or uniformly distributed throughout the mixture. In other words, there are no regions of low or high fuel concentration in the resulting fuel-air mixture, and in particular, no regions of pure air without fuel. To achieve complete premixing, thorough mixing is first performed, at least in a first premixing zone, where sufficient fuel is supplied to produce a fuel-air mixture that is not yet ignitable but is preferably fully or substantially homogeneous and lean in fuel. In a second premixing zone, or when two or more premixing zones are provided, particularly in the final premixing zone, fuel is supplied to produce a homogeneous fuel-air mixture that is preferably still lean in fuel but ignitable. After the final premixing zone and swirling treatment, a homogeneous fuel-air mixture with excess air is formed. This mixture then flows from the premixing device into the combustion chamber through the outlet opening area.

[0012] In some embodiments, the combustion method includes the following steps: An airflow is generated by a blower.

[0013] In some embodiments, the combustion method includes the following steps: Preheat the airflow, especially by using waste heat through a heat exchanger.

[0014] In some embodiments, the combustion method includes the following steps: Adjust the speed of the airflow.

[0015] In some embodiments, the combustion method includes the following steps: Adjust the fuel distribution to the premixed zone.

[0016] In some embodiments, the combustion method includes the following steps: After the fuel-air mixture leaves the burner head, the main flame is generated in the combustion chamber.

[0017] In some embodiments, the combustion method includes the following steps: The primary flame stabilizes the main flame, which is generated by the ignitable fuel-air mixture.

[0018] In some embodiments, the combustion method includes the following steps: During full-load operation, a larger outlet cross-section is provided to the combustion chamber for the ignitable fuel-air mixture, while during partial-load operation, a smaller outlet cross-section is provided for the ignitable fuel-air mixture.

[0019] In some embodiments, the combustion method includes the following steps: The fuel-air mixture is distributed to an outlet region with a fixed outlet cross-section and an outlet region with a controllable outlet cross-section, and the controllable outlet cross-section is controlled according to the burner output to be produced.

[0020] In some embodiments, the combustion method, particularly step a), includes the following steps: A uniform and ignitable fuel-air mixture is produced, wherein fuel and air are uniformly distributed across the entire flow cross-section, at least at the end of the final premixing zone.

[0021] In some embodiments, step b) includes the following steps: 10% to 80% of the fuel is supplied in the first premixed zone.

[0022] In some embodiments, step b) includes the following steps: 30% to 70% of the fuel is supplied in the first premixed zone.

[0023] In some embodiments, step b) includes the following steps: 40% to 60% of the fuel is supplied in the first premixed zone.

[0024] Particularly preferred is that the fuel is distributed approximately in equal proportions among the premixing zones. The fuel is continuously added and thoroughly mixed until a homogeneous, ignitable fuel-air mixture with an excess of air is formed.

[0025] In some embodiments, step b) includes the following steps: Fuel is supplied through at least one or more hollow bodies. According to some embodiments, the following are used as hollow bodies: hollow bodies with nozzles distributed on their surfaces, hollow bodies with perforated surfaces, perforated gas conduits, gas conduits with lateral holes, gas conduits extending transversely to the flow direction and having holes, gas conduits extending longitudinally to the flow direction and having holes, partially annularly extended perforated hollow bodies, annularly perforated hollow bodies, hollow annular bodies preferably having holes extending along the central axis of the hollow annular body in the flow direction and at least in the inward-facing side region and / or at least in the outward-facing side region, hollow swirl vanes with holes, and hollow bodies combining several characteristics of the above-mentioned hollow bodies.

[0026] In some embodiments, step b) includes the following steps: A vortex is generated in the airflow, and a first portion of the airflow that forms the vortex is supplied.

[0027] In some embodiments, step b) includes the following steps: In different annular regions of the first premixing zone, opposing swirls are generated in the airflow.

[0028] In some embodiments, step c) includes the following steps: The remaining portion is mixed in the second and third premixing zones.

[0029] In some embodiments, step c) includes the following steps: In a primary flame generating apparatus for producing a primary flame, 1% to 15% fuel is mixed to produce the primary flame. Preferably, the proportion of fuel used for the primary flame is between about 5% and about 15%. Specifically, the proportion of fuel mixed in the primary flame generating apparatus is less than 10%, for example, about 4%, 5%, 6%, or 7%. The value “about” specifically includes all values ​​covered after rounding to an integer. For example, “about 5%” specifically includes values ​​between 4.50% and 5.49%.

[0030] In some embodiments, step c) includes the following steps: Fuel is mixed using at least one or more hollow bodies. According to some embodiments, in particular, the hollow body used for mixing in the at least one additional premixing zone is: a hollow body with nozzles distributed on its surface, a hollow body with a perforated surface, a perforated gas conduit, a gas conduit with lateral holes, a gas conduit with holes extending transversely to the flow direction, a gas conduit extending longitudinally along the flow direction and having holes, a partially annular perforated hollow body, an annular perforated hollow body, a hollow ring body preferably having holes extending along the central axis of the hollow ring body in the flow direction and at least in the inward-facing side region and / or at least in the outward-facing side region, a hollow swirl vane with holes, and a hollow body combining several characteristics of the aforementioned hollow bodies.

[0031] In some embodiments, step c) includes the following steps: The fuel is mixed through at least one opening in the baffle.

[0032] In some embodiments, step d) includes the following steps: In different annular regions of the at least one additional premixed zone, reverse swirls are generated in the fuel-air mixture.

[0033] In some embodiments, step d) includes the following steps: Swirling is generated in the fuel-air mixture during the transition to the at least one additional premixed zone.

[0034] In some embodiments, step d) includes the following steps: A vortex is generated before mixing.

[0035] In some embodiments, step d) includes the following steps: Swirling flow is generated during mixing.

[0036] In some embodiments, step d) includes the following steps: Swirling flow is generated by perforated swirl blades carrying a carrier gas.

[0037] A particularly preferred embodiment optionally provides the possibility of combustion of liquid fuel. Specifically, a selection between a gaseous fuel combustion mode and a liquid fuel combustion mode according to any of the foregoing embodiments is provided. In dual-fuel operation, in addition to gaseous fuel combustion according to any of the foregoing configurations, liquid fuel can also be burned.

[0038] According to another aspect, the present invention provides a premixed burner comprising: Flame tube, gas supply device, which provides the flame tube with all the air flow required for combustion; A premixing device configured to receive 100% of the airflow from the air supply device and premix the airflow with fuel before it leaves the flame tube. And swirling devices, The premixing device includes: A first fuel supply device, having a control device, is configured to add a first portion of fuel to the airflow in a first premixing zone, thereby forming a lean fuel-air mixture that has not yet been ignited. And at least one auxiliary fuel supply device having a control device, the at least one auxiliary fuel supply device being configured to add the remaining portion of fuel to the lean fuel-air mixture in at least one auxiliary premixing zone spaced apart from the first premixing zone in the flow direction, to produce an ignitable fuel-air mixture with excess air. The swirling device is configured to swirl the mixture formed in at least one second premixing zone. The flame tube has an outlet opening region configured to discharge a fully premixed fuel-air mixture into the combustion chamber for combustion.

[0039] In some embodiments, the control device is an electromechanical control device in which electronic components, particularly a computer-implemented control unit, are combined with mechanical control elements. The computer-implemented control unit is, for example, part of an overall control system (e.g., a combustion manager) that includes a processor and a memory loaded with corresponding software. The mechanical control elements are, for example, baffles, actuators, sliders, or fixed or variablely adjustable flow cross sections.

[0040] In some embodiments, the flame tube has a cylindrical sleeve. In some embodiments, the flame tube has an inlet opening arranged and designed to receive 100% of the airflow. In some embodiments, the flame tube has a tapered section near its downstream-facing end. In some embodiments, the flame tube has an outlet cross-section adjusting device for adjusting the outlet cross-section of a portion of the outlet opening region. In some embodiments, the flame tube has at least one slider for variablely adjusting the outlet cross-section of the flame tube.

[0041] In some embodiments, the air supply device includes a blower for generating an airflow. In some embodiments, the air supply device includes a preheating device for preheating the airflow. In some embodiments, the air supply device includes an exhaust heat exchanger for preheating the airflow using waste heat. In some embodiments, the air supply device includes an exhaust gas supply device for supplying exhaust gas to the airflow. In some embodiments, the air supply device includes a control device for controlling the airflow. In some embodiments, the control device of the air supply device is also an electromechanical control device as described above. As a control device, for example in a computer-implemented control system for a premixed burner, control routines as part of the control software are provided for controlling the blower and / or air dampers of the air supply device. In some embodiments, the air supply device includes a control interface capable of connecting to the control system of the premixed burner or a higher-level control system.

[0042] In some embodiments, the premixing device includes a first premixing zone and a second premixing zone, the second premixing zone being spaced apart from the first premixing zone in the flow direction. In some embodiments, the premixing device includes a first premixing zone, a second premixing zone, and a third premixing zone arranged sequentially along the flow direction. In some embodiments, the premixing device includes a fixed or variablely adjustable fuel flow channel cross-section for distributing a portion of the fuel to a first supply device and each additional fuel supply device. In some embodiments, the premixing device includes a regulating device for regulating fuel distribution. In some embodiments, the premixing device includes a fuel distribution ring for distributing fuel to a plurality of premixing zones. In some embodiments, the premixing device includes a control device (particularly an electromechanical control device as described above) for controlling fuel supply. In some embodiments, the premixing device includes a control interface capable of being connected to a control system.

[0043] In some embodiments, the first fuel supply device includes an inflow cross section whose dimensions are set relative to the inflow cross section of at least one additional fuel supply device, such that a predetermined first portion of fuel flows through the first fuel supply device. In some embodiments, the first fuel supply device includes an adjustment device for adjusting the inflow cross section. In some embodiments, the first fuel supply device includes at least one or more hollow bodies for supplying fuel. According to some embodiments, in particular, hollow bodies with nozzles distributed on their surfaces, hollow bodies with perforated surfaces, perforated gas conduits, gas conduits with lateral holes, gas conduits extending transversely to the flow direction and having holes, gas conduits extending longitudinally to the flow direction and having holes, partially annularly extended perforated hollow bodies, annularly perforated hollow bodies, hollow annular bodies, hollow annular bodies preferably having holes extending along the central axis of the hollow annular body in the flow direction and at least in the inwardly facing side region and / or at least in the outwardly facing side region, hollow swirl vanes with holes, and hollow bodies combining several characteristics of the aforementioned hollow bodies are used as the hollow bodies of the first fuel supply device. In some embodiments, the first fuel supply device includes computer-implemented control devices for controlling fuel supply. For example, these control devices are provided as part of the control software in a premixed burner control system.

[0044] In some embodiments, the one or more additional fuel supply devices have an inflow cross-section designed relative to the inflow cross-section of the first fuel supply, such that a predetermined additional portion of fuel flows through the respective additional fuel supply device. In some embodiments, the one or more additional fuel supply devices include a second fuel supply device located in a second premixing zone. In some embodiments, the one or more additional fuel supply devices include a third fuel supply device located in a third premixing zone. In some embodiments, the one or more additional fuel supply devices include an ignition flame fuel supply device for supplying a portion of fuel to an ignition flame, the portion of fuel being at most one-third of the portions of fuel from the first and second fuel supply devices. In some embodiments, the one or more additional fuel supply devices include a regulating device for regulating the inflow cross-section of the additional fuel supply device. In some embodiments, each of the one or more additional fuel supply devices includes at least one or more hollow bodies for mixing additional fuel portions. According to some embodiments, hollow bodies having nozzles distributed on their surfaces, hollow bodies having perforated surfaces, perforated gas conduits, gas conduits with lateral holes, gas conduits extending transversely to the flow direction and having holes, gas conduits extending longitudinally to the flow direction and having holes, partially annularly extending perforated hollow bodies, annularly perforated hollow bodies, hollow annular bodies, preferably having holes extending along the central axis of the hollow annular body in the flow direction and at least in the inward-facing side region and / or at least in the outward-facing side region, hollow swirl vanes with holes, and hollow bodies combining several characteristics of the aforementioned hollow bodies are used as hollow bodies for supplementary fuel supply devices. In some embodiments, the one or more fuel supply devices include computer-implemented control devices for controlling fuel supply. For example, these are also provided as part of control software in a premixed burner control system.

[0045] In some embodiments, the swirling device has swirling units for generating swirl in the airflow entering the first premixed zone. In some embodiments, the swirling device includes counter-swirling units for generating swirls with opposite swirling directions in different annular regions of the flame tube. In some embodiments, the swirling device includes a first swirling unit and at least one other swirling unit, the first swirling unit being located within or upstream of the first premixed zone, and the at least one other swirling unit being located at a transition point to or within another premixed zone. In some embodiments, the swirling device includes swirling blades arranged inwards and outwards. In some embodiments, the swirling device includes swirling blades formed as hollow bodies having nozzles for fuel supply. In some embodiments, the swirling device includes a primary flame swirling unit located at a baffle.

[0046] In some embodiments, the premixed burner further includes a baffle for stabilizing the primary flame. In some embodiments, the premixed burner further includes a liquid fuel nozzle for delivering liquid fuel to a combustion chamber downstream of the flame tube. In some embodiments, the premixed burner further includes a control system having a processor and a memory. In some embodiments, the premixed burner further includes a control device for controlling the fuel-to-air flow ratio. As described above, the control device is preferably an electromechanical control device. In some embodiments, the premixed burner further includes a control system configured to cause the premixed burner to perform one of the embodiments of the combustion method described above.

[0047] According to another aspect, the present invention provides a control system for a premixed burner according to one of the aforementioned configurations, the control system being configured to cause the premixed burner to automatically perform one of the embodiments of the above-described combustion method.

[0048] According to another aspect, the present invention provides a computer program comprising instructions that cause a premixed burner according to one of the above configurations to perform a combustion method according to one of the above embodiments.

[0049] The specific effects and advantageous configurations of the invention will be described in more detail below. In previously known combustion methods, fuel is premixed with air, intentionally creating an overly rich fuel-air mixture, to which an additional air stream is then added to achieve a lower flame temperature. This reduces the formation of thermal nitrogen oxides. To date, reducing thermal nitrogen oxides has been the sole concern of the prior art, as explained in more detail in reference

[11] .

[0050] However, as described in reference

[12] , nitrogen oxides in combustion are generally classified into three types based on their source and formation mechanism: thermal nitrogen oxides, fuel nitrogen oxides, and rapid nitrogen oxides. Thermal nitrogen oxides are produced at relatively high temperatures through the oxidation of nitrogen in the air. To date, existing nitrogen oxide emission reduction combustion concepts have focused only on this, see reference

[11] . The source of fuel nitrogen oxides is the amount of nitrogen bound to the fuel. This amount depends on the fuel used and cannot be reduced if a specific fuel (such as ammonia or biogas) is being burned. However, in some gaseous fuels (such as natural gas), the proportion of fuel-derived nitrogen oxides is negligible and very small.

[0051] By using the combustion method according to the invention and its advantageous configuration, as well as the premixed burner designed for performing the combustion according to the invention and its advantageous configuration, the formation of rapid nitrogen oxides can also be reduced, thereby achieving further nitrogen oxide emission reductions than before. In order to achieve nitrogen oxide emissions significantly below 50 milligrams per standard cubic meter when burning gaseous fuels (such as natural gas), rapid nitrogen oxides are also taken into consideration according to the invention.

[0052] In some embodiments of the invention, the combustion air flow is 100% directed through the premixing section of the burner, wherein at least a first premixing zone and a second premixing zone are spaced apart from each other in the flow direction. In the upstream first premixing zone, the fuel (gas) is supplied in a manner such that the resulting mixture is unignitable. For example, the combustion air ratio λ is greater than 2. In the downstream second (or third or other) premixing zone, which is still located within the premixing section through which the combustion air passes, an additional portion of fuel is mixed in such a manner that an ignitable mixture is produced. Advantageously, excess air is still used to cool the flame and reduce the formation of thermal nitrogen oxides. For example, the ignitable mixture is still lean fuel with a combustion air ratio λ greater than 1. Swirling is generated for good mixing. The ignitable mixture is directed through the flow cross-sectional area—i.e., the outlet opening area—into the combustion chamber (also called the furnace), which, in some embodiments, may be reduced during partial load operation. The flame is generated here.

[0053] By producing a fully premixed fuel-air mixture, the formation of rapid nitrogen oxides can be prevented or at least significantly reduced. Nevertheless, the load is easily controlled, and reignition does not occur.

[0054] The combustion method according to an advantageous embodiment of the invention does not require a metal mesh or other measures to prevent reignition. An ignitable fuel mixture is formed only in the final premixing zone in the flow direction. Here, the flow rate can be maintained at a sufficiently high level to prevent backfire. Even if backfire does occur, the volume of the ignitable mixture is very small. Therefore, high flow rates can be achieved, resulting in high combustion efficiency, while maintaining a stable combustion process despite extremely low nitrogen oxide production.

[0055] Accordingly, in this invention, the method of performing complete premixing is as follows: first, fuel is supplied to the airflow in a first premixing zone so that the resulting mixture is not yet ignitable; then, additional fuel is supplied in at least one second premixing zone (which is still located in the premixing section within the airflow) until it reaches a state where it can be ignited.

[0056] Preferred embodiments relate to the combustion method described above, which can be implemented through the appropriate design and control of a premixed burner. In particular, advantageous embodiments include appropriate control of the premixed burner. Other embodiments relate to a premixed burner configured to perform the combustion method via a corresponding premixing zone, a fuel supply device, and a control device (particularly a control device at least partially computer-implemented, i.e., not only for this purpose but also practically configured for this purpose).

[0057] The preferred configuration of the premixed burner is based on the prior art described in references [6] through

[10] and has the configuration features known in those references—unless they are superseded by specific features of embodiments of the invention described in more detail below. For more detailed possible embodiments, references [6] through

[10] are therefore included herein by reference. Attached Figure Description

[0058] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In the drawings: Figure 1 A block diagram is shown illustrating a premixed combustion method with ultra-low nitrogen oxide production, and some components of a premixed burner configured to perform the combustion method according to an advantageous embodiment; Figure 2 An axial longitudinal section of the burner head of a first embodiment of a premixed burner for performing the combustion method is shown; Figure 3 An axial longitudinal section of the burner head of a second embodiment of a premixed burner for performing the combustion method is shown; Figure 4 A block diagram is shown illustrating a combustion method configuration that can be used with [specific features]. Figure 2 The premixed burner at the burner head shown is operating at full load. Figure 5 A block diagram is shown illustrating a combustion method configuration that can be used with [specific features]. Figure 2 The premixed burner at the burner head shown operates under partial load. Figure 6 A perspective view of a premixing device at the burner head of a premixed burner is shown, which is used in another configuration to perform the combustion method. Figure 7 An axial longitudinal section of the burner head is shown, in which the burner head is installed. Figure 6 The premixing unit shown is configured to operate at full load, demonstrating the airflow and the flow paths of fuel and the fuel-air mixture; Figure 8 The axial longitudinal section of the burner head is shown, similar to... Figure 6However, it is set to operate at partial load, demonstrating the fuel flow path, which shows a variant of the premixing unit; Figure 9 It shows Figure 8 A perspective view of the premixing device at the head of the burner; Figure 10 A perspective view of a mixing unit with a dual-fuel (gas / liquid fuel) design is shown, which has features for equipping according to... Figure 8 and Figure 9 The fuel distribution at the burner head of the premixed device shown; and Figure 11 A cross-section of a burner head is shown, which is equipped with a dual-fuel mixing device, which includes, according to... Figure 8 or Figure 9 The premixing unit and the central atomizing nozzle for liquid fuel. Detailed Implementation

[0059] Figure 1 , Figure 4 and Figure 5 A block diagram of a combustion method for burning a fuel-air mixture is shown, wherein the gaseous fuel is premixed with air.

[0060] In this combustion method, 100% of the air stream 10 provided for combustion is completely premixed with the gaseous fuel 12. The complete premixing step includes the following steps: In the first premixing zone 14.1, a first portion A.1 of fuel 12 is added to the air stream 10, thereby forming a lean fuel-air mixture 16 that is not yet ignitable; and In at least one other premixing zone 14.n, the remaining portion An of fuel 12 is mixed into a lean fuel-air mixture 16 to produce an ignitable fuel-air mixture 18 with excess air (n represents a natural number greater than 1), the other premixing zone 14.n being spaced apart from the first premixing zone 14.1 in the flow direction.

[0061] The mixing step also includes at least the following steps: This causes the fuel-air mixture 18 to swirl.

[0062] For example, at least a first premixing zone 14.1 and a second premixing zone 14.2 are provided. Additional premixing zones 14.n can also be provided, such as a third premixing zone 14.3.

[0063] In some embodiments, a fully homogeneous, ignitable fuel-air mixture 18 with an excess of air is produced by mixing fuel in multiple premixing zones and passing it through swirl. In this mixture, fuel is distributed at a uniform concentration across the entire flow cross-section of the air, at least at the outlet opening region 70 where the fuel-air mixture 18 flows into the combustion chamber 60. In some embodiments, the formation of rapid nitrogen oxides is prevented or at least significantly reduced, particularly through this “homogeneous premixing” in the second / final premixing zone.

[0064] A preferred embodiment of the method is further characterized by its ability to integrate the combustion of liquid fuels.

[0065] A first fuel supply device 20.1 is assigned to a first premixing zone 14.1. The first fuel supply device 20.1 is controlled by a suitable control device (including actuator 22 and electronic control unit 24) such that a first portion A.1 of fuel 12 is supplied to the air flow 10, thereby forming a lean fuel-air mixture 16 in the first premixing zone 14.1 that is not yet ignitable. Each subsequent premixing zone 14.n is assigned an additional fuel supply device 20.n, which is also controlled by the same control device, such that the remaining portion An of fuel 12 is supplied to the lean fuel-air mixture 16, thereby forming an ignitable fuel-air mixture 18 with excess air in at least the last additional premixing zone 14.n in the flow direction.

[0066] At least in the final premixing zone 14.n, or at least in the final premixing zone 14.n, a swirl unit 26 of the swirl device 28 is provided for generating swirl in the fuel-air mixtures 16, 18. Figure 1 As shown by the dashed line, the premixing zone 14.1 may also be equipped with a swirl unit 26.

[0067] Each fuel supply device 20.1, 20.n includes at least one hollow body 30 for conveying fuel 12. The hollow body 30 is provided with nozzles or orifices so that the fuel 12 is added as uniformly as possible to the premixing zones 14.1, 14.2. This facilitates homogeneous premixing. For example, a gas conduit 32 may be provided as the hollow body 30; the gas conduit 32 may extend along or transverse to the flow direction, and preferably has orifices distributed on its surface. In addition, an annular element 34 having a cylindrical inner surface and an outer surface with gas outlet openings distributed on the inner and outer surfaces may also be provided as the hollow body 30. In some embodiments, the hollow body 30 is provided in the form of swirl blades 36 of a swirl device 28, the surfaces of which are distributed with gas outlet openings for supplying or mixing gaseous fuel 12.

[0068] Figure 1A premixed burner 40 configured to perform the combustion method is also shown in block diagram form. The premixed burner 40 includes a burner head 42 (also referred to as a flame head), which has a flame tube 44 ( Figure 1 For clarity, the text has been omitted, but... Figure 2 , Figure 6 , Figure 7 and Figure 10 (as shown in the diagram), and premixing device 46. Premixing zone 14.1, 14.n is formed within the flame tube 44. The premixing device 46 includes fuel supply devices 20.1 and 20.n. The air supply device 48 for providing airflow 10 is, for example, a blower 50. The premixed burner 40 also includes an electronic control unit 52, which has a processor 54 and a memory 56. The control routine is stored as software (computer program) in the memory 56. The control system 52 controls the blower 50 and the actuators of the premixed burner 40, causing the burner to perform the aforementioned combustion method. Therefore, the control system 52 also provides at least some control devices for fuel supply as part of the control routine.

[0069] Figure 1 Also shown is a combustion chamber 60, an optional exhaust gas recirculation system 64, and an equally optional air preheating device 66. The combustion chamber 60 contains a flame 62 generated downstream of the flame head during combustion. The exhaust gas recirculation system 64 is used to mix exhaust gas into the inlet of the air supply device 48, and the air preheating device 66 is used to heat the combustion air. For example, the air is preheated using the heat from the exhaust gas via an exhaust gas heat exchanger 68 before entering the blower 50.

[0070] like Figure 1 As further schematically shown by the dashed lines, the outlet cross-section of the outlet opening region 70 for the ignitable fuel-air mixture 18 with excess air can optionally be varied by a suitable actuator controllable by the control unit 52. The outlet opening region 70 includes, for example, a fixed outlet cross-section region 70.1 and a variable outlet cross-section region 70.2, which can be adjusted by an actuator, such as a movable air slider 72. This allows for a larger outlet cross-section for the ignitable fuel-air mixture 18 to the combustion chamber 60 during full-load operation and a smaller outlet cross-section for the ignitable fuel-air mixture during partial-load operation.

[0071] For example, fuel 12 is distributed to the respective premixing zones 14.1, 14.n in equal or optionally different proportions A1, An—particularly by setting or adjusting the flow cross-sections of the corresponding gas supply lines 58.1, 58.n. The total amount of fuel 12 is controlled by control unit 52 according to the desired load and the airflow 12 set for this purpose by blower 50. The combustion airflow—airflow 10—flows 100% through the premixing section of premixed burner 40, wherein at least the first premixing zone 14.1 and the second premixing zone 14.2 are spaced apart from each other in the flow direction. In the upstream first premixing zone 14.1, the fuel 12 (gas) is supplied in such a manner that… The resulting mixture 16 is unignitable. For example, the combustion air ratio λ is greater than 2. In a downstream second (or third, or other) premixing zone 14.2, 14.n—which is still within the premixing section through which the combustion air flows—another portion of fuel 12 is mixed in such a way that an ignitable mixture 18 is produced. Continuing to operate under excess air conditions is advantageous to cool the flame 62 and reduce the generation of thermal nitrogen oxides. For example, the ignitable mixture 18 remains a lean fuel mixture with a combustion air ratio λ greater than 1. Swirling is generated at least in the last premixing zone in the flow direction—and optionally also in at least one or all other premixing zones 14.1, 14.2, 14.n—to achieve adequate mixing. The ignitable mixture 18 is directed to the combustion chamber 60 through an outlet opening region 70, wherein in some embodiments, the outlet cross-section of the outlet opening region 70 may be reduced during partial load operation.

[0072] Figure 2 A first specific exemplary embodiment of the burner head 42 of the premixed burner 40 is shown. This embodiment is based on the burners described in references [9] and

[10] , which are equipped with, for example... Figure 2 The burner head 42 and premixing device 46 shown are configured to perform the combustion method described herein, with the software in the control unit 52—referred to as the combustion manager in references [9] and

[10] —being configured accordingly.

[0073] Figure 2 The premixing device 46 shown includes a first premixing zone 14.1, a second premixing zone 14.2, a third premixing zone 14.3, and an ignition flame generation zone 76. The ignition flame generation zone 76 includes a conical slotted baffle 78 through which a portion of the lean fuel-air mixture 16 is guided to supply the primary air required for ignition and to impart primary swirl to that portion of the mixture. The first and second premixing zones 14.1 and 14.2 each include perforated gas conduits 32 extending along and transverse to the flow direction. The third premixing zone 14.3 includes carrier gas swirl vanes 36.

[0074] Optionally, Figure 2 The premixed burner 46 shown can be designed for dual-fuel operation and is equipped with a secondary nozzle 80 for heating the fuel oil. Natural gas N is supplied to the premixing unit 46 as fuel 12. A regulating device 82 is also provided for regulating the distribution of fuel 46 among premixing zones 14.1, 14.2, and 14.3.

[0075] Figure 2 A particularly noteworthy example is an ultra-low NOx WK burner, designed for use in gas and dual-fuel burners with extremely high output power (e.g., 200 to 18,000 kW).

[0076] The premixed burner 46 employs the following NOx reduction technologies to complement natural gas (N) operation: By premixing fuel 12 with air 10, the generation of rapid NOxes is reduced compared to conventional diffusion flames. The flame temperature is lowered by using a high excess air, which reduces the formation of thermal NOxes. The premixed flame is characterized by its compactness and shorter flame length.

[0077] Fuel 12 is supplied to combustion air 10 or lean fuel-air mixture 16 via perforated gas conduits 32 (along the burner axial and transverse directions) through the first premixing zone 14.1 and the second premixing zone 14.2. In the third premixing zone 14.3, fuel 12 is directly fed into the swirl of fuel-air mixture 16 through fuel-carrying swirl vanes 36. At this point, ignitable fuel-air mixture 18 is discharged from the flame head 42 and enters the combustion chamber 60, where the main flame generated by fuel-air mixture 18 is stabilized and burned off by the primary flame. The primary flame is stabilized by the conical slotted baffle 78 and the primary swirl.

[0078] A small fraction of the total fuel (e.g., at most one-third to one-tenth of the other fraction) is directed to the ignition flame generation zone equipped with baffle 78. The primary flame (which may be a diffusion flame or a premixed flame) stabilizes the main flame.

[0079] The advantages of using an ignition flame (also known as a primary flame) for stabilization include, for example: providing defined and constant ignition conditions for the premixed air / fuel volume 18; reliable ignition performance; and process monitoring capabilities. For example, it can be achieved through... Figure 1 The probe 84 shown measures parameters of the combustion process, such as the ionization current of the primary flame.

[0080] exist Figure 2In the illustrated embodiment, the fuel distribution ring 86 provides adjustment options for the amount of fuel supplied to the three premixed zones 14.1, 14.2, and 14.3. In a simplified design, the fuel quantity can be adjusted by using threaded, variable, and adjustable baffles at all inlet cross-sections of the supply line.

[0081] The outlet cross sections 70.1 and 70.2 at the flame head 42 are reduced in size under partial load due to the air slider 72. This causes pressure buildup, which in turn increases the flow rate, thereby preventing the flame 62 from flashing back into the premixed zones 14.1 and 14n under partial load.

[0082] Fuel injection into the premixed zone is achieved by arranging a perforated pipe cross-section and / or any hollow geometry 30 with a nozzle. Figure 2 In one embodiment, a perforated gas conduit 32 and a similarly perforated hollow swirl vane 36 are used as a gas outlet.

[0083] Any additional atomizing unit can be operated using nitrogen oxide emission reduction technology, such as that found in burners manufactured by Max Weishaupt GmbH and sold under the multiflam® brand, which involves a conventional diffuse flame.

[0084] To improve system efficiency, preheated combustion air can be supplied to the flame head 42 via an optional exhaust gas heat exchanger 68.

[0085] To reduce the excess air coefficient while maintaining comparable pollutant emissions, recirculated exhaust gas from the boiler end can be mixed with combustion air via a combustion air blower. This helps reduce pollutant emissions.

[0086] Figure 3 A second embodiment of the burner head 42 of the premixed burner 40 is shown, which generally corresponds to the first embodiment, but is configured to have only a first premixing zone 14.1 and a second premixing zone 14.2. In the second embodiment, the gas conduit 32, which is more centrally arranged along the flow direction in the first embodiment and forms an intermediate premixing zone between the first and last premixing zones, is omitted. Apart from this, the second embodiment is identical to the first embodiment, and therefore further details can be found in the description of the first embodiment above.

[0087] Figure 4 The premixed burner 40 is shown (in particular) Figure 2 The diagram below shows a pure, exemplary block diagram of full-load operation (of the type shown). More specifically, Figure 4 The simplified gas flow (fuel flow) G and air flow L of the premixing device 46 of the WK series ultra-low NOx burner are shown, derived from the operation of known burners at full load VL according to references [9] and

[10] . Figure 5A block diagram illustrating an exemplary partial-load operation of the same premixed burner 40 is shown. More specifically, Figure 5 The simplified gas flow (fuel flow) B and air flow L of the premixing unit 46 of the WK series ultra-low NOx burner are shown, derived from the operation of known burners under partial load TL according to references [9] and

[10] . The block diagram is self-explanatory when using the following description.

[0088] B--Gas flow L--Airflow and mixed airflow VL -- Full load TL -- Partial Load 100 -- within the first premixing zone 14.1 102 -- Near the flame head outlet (additional premix zone) 62--Flame 104--" = 1.45 (Example of combustion air ratio for a fuel-air mixture 18 capable of being ignited) 106 -- Full load: 10000 kW / λ = 1.45 / O 2,tr = 7% 108--Air slider 72 open 110 -- Gas concentration 2.3 vol% <LEL !!! (λ = 1.45) (When λ = 1, the gas concentration is 3.3 vol% < <LEL)。

[0089] 112--Virtual = 4.48 114 -- Combustion Air (100%) 116-13800 mN³ / h (Example of 100% combustion air flow 10) 118-312 mN³ / h (Example values ​​for fuel supply) 120 -- First introduction of gas through perforated pipe (A.1 = 32% - Example) 122 -- Introducing a tertiary mixture via an air slider (Example: 50%) 124--6900 mN³ / h 126--Secondary fuel gas introduction via perforated gas pipeline (A.2 = 32% - Example) 128 -- Introducing a secondary mixture via a secondary swirl (Example: 38%) 130-5200 mN³ / h 132--Three-stage gas introduction via hollow swirl blades (A.3 = 32% - Example) 134 -- Primary mixing via primary swirl (12%) 136-1700 mN³ / h 138-29 mN³ / h ≈ 3% (A.4 - a portion of the fuel used to ignite the flame) 140 -- Minimum amount of primary combustion gas introduced through the baffle 142 -- Gas concentration 6.8 vol% 144 -- Gas concentration 8.2 vol% 146 -- Secondary Flame (= Primary Flame) 148 -- Gas concentration 4 vol% 150 -- Basic Flame (= Ignite Flame) 152--Partial load: 3500 kW / λ = 1.45 / O 2,tr = 7% 154--Air slider 72 Close 156--4800 mN 3 / h 158-109 mN 3 / h 160 -- Three-stage mixture via air slider (0%) 162 -- Secondary mixture (75%) passing through a secondary vortex 164--3600 mN³ / h 166 -- Primary mixing via primary swirl (25%) 168-1200 mN³ / h 170--10 mN 3 / h ≈ 3% 172 -- Gas concentration 8.2 vol% 174 -- Gas concentration 3.1 vol% Figure 4 and Figure 5 The values ​​given are merely examples for a specific burner design; depending on the design, these values—especially the same ratios between each other—may deviate upwards or downwards, for example, by a deviation factor ranging from 0.3 to 4, and particularly from 0.5 to 2. In particular, partial loads may vary. These values ​​are calculated using standard volumes and assuming instantaneous ideal mixing conditions. These values ​​should be considered rough estimates. Figure 4 and Figure 5The schematic diagram illustrates the process in the premixing unit 46 in a highly simplified manner. LEL refers to the lower explosive limit; for natural gas, it is E = 4.9 vol%. UEL refers to the upper explosive limit; for natural gas, it is E = 14.7 vol%.

[0090] In the following text, Figures 6 to 11 Further embodiments of the premixed combustor 40 are illustrated, which—thanks to the design of the fuel distribution and computer-implemented control system 52—are configured to perform the functions described above. Figure 1 The present invention describes an ultra-low nitrogen oxide emission reduction combustion method considering rapid nitrogen oxides.

[0091] Figures 6 to 11 The embodiments shown are specifically designed for the medium power range and are based in particular on known burners described in references [7] and [8], wherein the following is in conjunction with Figures 6 to 11 The described embodiment of the burner head 42 with premixing device 46 replaces the burner head or flame head shown therein, and wherein the software in the control system mentioned in references [7] and [8] is modified such that in the first premixing zone 14.1, fuel 12 is supplied to 100% of the total air flow 10, thereby forming a lean fuel-air mixture 16 that is not yet ignitable, and in at least one other premixing zone 14.n and optionally in the ignition flame generation zone 76, the remaining portion An of fuel is supplied to the lean fuel-air mixture 16, thereby forming an ignitable fuel-air mixture 18 with excess air under the action of swirling. As described above, complete (i.e. homogeneous) premixing can prevent or at least significantly reduce rapid nitrogen oxides.

[0092] Figure 6 A variant of the premixing device 46 is shown, which does not include the flame tube 44; Figure 7 A premixing device 46 in the burner head 42 is shown. The premixing device 46 has a flame tube 44 and an air flow or mixed air flow L and a fuel flow B for full-load operation. Figure 8 A slightly modified variant of the burner head 42 is shown, which has a flame tube 44 and a premixing device 46, configured for partial load operation, with fuel flow B indicated. Figure 9 Another variant of the premixing device 46 is shown. Figure 10 and Figure 11 An alternative embodiment of a burner head 42 with a premixing device 46 for dual-fuel operation (gas / liquid fuel, such as fuel oil) is shown.

[0093] exist Figures 6 to 11 In the embodiment, in addition to the first premixing zone 14.1 having the first fuel supply device 20.1, only the second premixing zone 14.2 having the second fuel supply device 20.2 is provided.

[0094] Fuel supply devices 20.1 and 20.2 are hollow bodies 30, which, in addition to including a centrally perforated gas conduit 32, also include an annular body 34. The annular body 34 has a cylindrical inner wall and a cylindrical outer wall, both of which have gas outlet openings distributed on their surfaces. In a variant not shown, only one fuel supply device (e.g., the second fuel supply device 20.2) has an annular body 34, while the first fuel supply device includes, for example, a gas conduit extending laterally in the flow direction.

[0095] The swirling device 28 includes at least one, preferably multiple, counter-swirling devices 88 for generating swirling flows with opposite swirling directions in different annular regions of the flame tube 44.

[0096] Specifically, a first swirl unit 26.1 is provided within or preferably before the first premixing zone 14.1, and at least one second swirl unit 26.2, 26.n is provided at or within the subsequent second premixing zones 20.2, 20.n. Figure 6 and Figure 7 In the variant shown, a third swirl unit 26.3 is provided (e.g., located at the inlet opening 98 of the baffle body housing 96), the third swirl unit 26.3 in Figures 8 to 11 Other variations shown are omitted. In the illustrated embodiment, each swirl unit 26.1, 26.2, designed as a counter-swirling unit, includes an inner arrangement 90 of swirl blades 92.1 (designed here as a simple plate without internal gas flow guides) and an outer arrangement 92 of swirl blades 92.2. The pitch / tilt direction of the inner swirl blades 92.1 is opposite to that of the outer swirl blades 92.2.

[0097] Figure 7 The diagram illustrates the range of a first premixing zone 14.1 and a second premixing zone 14.2, in which a lean fuel-air mixture 16 that is difficult to ignite is formed in the first premixing zone 14.1, and in which a homogeneous, ignitable fuel-air mixture 18 with excess air is formed in the second premixing zone 14.2.

[0098] The burner head 42 is also provided with an ignition flame generating zone 76, which has a baffle 78 for generating swirl, as described above with respect to the embodiment of Figure 2.

[0099] Furthermore, a conical housing 96 is provided near the outlet of the flame tube 44. An outlet opening region 70 is formed between the conical housing 96 and the opening of the flame tube 44. The housing 96 is slidable, thereby forming an air slider 72 for adjusting the outlet cross sections 70.1 and 70.2 of the outlet opening region 70.

[0100] An inlet opening 98 for supplying the ignition flame mixture is provided at the upstream end of the housing 96. The cross-section of the inlet opening 98 is smaller than the cross-section between the upstream end of the housing and the flame tube.

[0101] Due to the narrowing of the flow cross-section between the casing 96 and the flame tube, and the outlet cross-section of the outlet opening region 70, a high flow velocity is generated near the end of the flame head, thereby preventing reignition in the second premixing zone 14.2. Even if reignition unexpectedly occurs, the ignitable mixture 18 is only present in the second premixing zone 14.2, and therefore the critical mass is very small.

[0102] As shown in the comparison of Figures 7 and 8, by moving the housing 96, the outlet cross-section of the outlet opening region 70 can be reduced to accommodate partial load operation. In this way, even when operating under partial load, a high flow rate can still be maintained despite the low flow rate of the mixture 18 per unit time, thereby continuing to prevent reignition.

[0103] Figure 8 further illustrates the self-centering mechanism 180 for the premixing device 46, which simplifies the assembly process. Additionally, a gas flow guide 181 for uniform pressure distribution is shown, which is an improvement over previously known burners. There is no gas / air mixture in the rotating flange region 182, which is inherently leaky due to its function (not shown in detail, as this is known in principle from references [8] and [9]).

[0104] Figure 10 An optional gaseous / liquid fuel (e.g., fuel oil) dual-fuel design is shown, wherein, in addition to a premixing device 46 with different premixing zones 14.1, 14.2 for gas operation, a fuel distribution system 184 for liquid fuel (e.g., fuel oil) is also shown, which is commonly known in multiflam® burners. Figure 11 As shown, a central atomizing nozzle 186 (e.g., located at the center of the baffle 78) can be provided to replace or supplement the fuel distribution system 184.

[0105] To achieve safe combustion with ultra-low nitrogen oxide emissions, a combustion method for fuel-air mixtures (excluding gas turbines) has been proposed, which includes: a) Completely premixing 100% of the air stream (10) for combustion with (gaseous) fuel (12), wherein step a) includes: b) In the first premixing zone (14.1), a first portion (A.1) of fuel (12) is added to the air stream (10) to form a lean fuel-air mixture (16) that is not yet ignitable; and c) Mixing one or more remaining portions (An) of fuel (12) into a lean fuel-air mixture (16) in at least one other premixing zone (14.n), the at least one other premixing zone (14.n) being spaced apart from the first premixing zone (14.1) in the flow direction to produce an ignitable fuel-air mixture (18) with excess air. Step c) includes: d) To generate swirl in the fuel-air mixture (18) formed in at least one other premixed zone (14.n).

[0106] In addition, a premixed burner (40) configured to perform such premixing and combustion is proposed.

[0107] List of reference numerals: 10--Airflow 12--Fuel (gaseous) 14.1 -- First Premixed Zone 14.n -- Another premixed region (the nth premixed region, where n>1) 16 -- Lean fuel-air mixture that is difficult to ignite 18 -- A fuel-air mixture with excess air that is capable of ignition 20.1 -- First fuel supply unit 20.n -- Additional fuel supply device (nth fuel supply device) 22--Actuator 24--Electronic Control Unit 26--Swirl Unit 26.1 -- First Swirl Unit 26.2--Second Swirl Unit 26.3 -- Third Swirl Unit 28--Swirl apparatus 30 -- Hollow bodies used for supplying or mixing fuels 32--Gas Pipeline 34--Ring-shaped body 36--Swirl Blade 40--Premixed burner 42--Burner head (flame head) 44--Flame tube 46--Premixing device 48--Gas supply device 50--Blower 52--Control System (Example of electronic components in a control device) 54--Processor 56--Memory 58.1 -- Gas supply pipeline for the first fuel supply unit 58. -- (nth) auxiliary fuel supply unit's gas supply pipeline 60-- Combustion Chamber 62 -- Flame 64 -- Exhaust Gas Recirculation 66 -- Air preheating device 68 -- Exhaust Gas Heat Exchanger 70 --Exit opening area 70.1 -- Fixed outlet cross-sectional area 70.2 -- Variable outlet cross-sectional area 72 -- Air Slider 76 -- Ignition Flame Generation Area 78 -- baffle 80 -- Secondary nozzle 82 -- Adjustment device 84 -- Probe 86 -- Fuel Distribution Ring 88 -- Reverse vortex device 90 --Inner side arrangement 92 -- Swirl blades 94 --Outer side arrangement 96 -- Shell 98 -- Entrance opening 100 -- within the first premixing zone 14.1 102 -- Near the flame head outlet (additional premix zone) 104-- " = 1.45 (Example of combustion air ratio for a fuel-air mixture 18 capable of being ignited) 106-- Full load: 10000 kW / λ = 1.45 / O2,tr. = 7% (Parameter example at full load) 108-- Air slider 72 activated 110 -- Gas concentration 2.3 vol% <LEL !!! (λ = 1.45) (At λ = 1, the gas concentration is 3.3 vol% < <LEL)。

[0108] 112-- Virtual = 4.48 114 -- Combustion Air (100%) 116-13800 mN³ / h (Example of 100% combustion air flow 10) 118-312 mN³ / h (Example values ​​for fuel supply) 120 -- First introduction of gas through perforated pipe (A.1 = 32% - Example) 122 -- Introducing a tertiary mixture via an air slider (Example: 50%) 124--6900 mN 3 / h 126--Secondary fuel gas introduction via perforated gas pipeline (A.2 = 32% - Example) 128 -- Introducing a secondary mixture via a secondary swirl (Example: 38%) 130-5200 mN³ / h 132--Three-stage gas introduction via hollow swirl blades (A.3 = 32% - Example) 134 -- Primary mixing via primary swirl (12%) 136-1700 mN 3 / h 138-29 mN³ / h ≈ 3% (A.4 - a portion of the fuel used to ignite the flame) 140 -- Minimum amount of primary combustion gas introduced through the baffle 142 -- Gas concentration 6.8 vol% 144 -- Gas concentration 8.2 vol% 146 -- Secondary Flame (= Primary Flame) 148 -- Gas concentration 4 vol% 150 -- Basic Flame (= Ignite Flame) 152--Partial load: 3500 kW / λ = 1.45 / O2,tr. = 7% 154--Air slider 72 Close 156--4800 mN 3 / h 158-109 mN³ / h 160 -- Tertiary mixture introduced through air baffle (0%) 162 -- Secondary mixture (75%) introduced via secondary swirl 164--3600 mN³ / h 166 -- Primary mixture (25%) introduced via primary swirl 168-1200 mN³ / h 170-10 mN³ / h ≈ 3% 172 -- Gas concentration 8.2 vol% 174 -- Gas concentration 3.1 vol% 180--Self-centering mechanism 181--Gas flow diversion device 182--Swivel flange area 184 -- Fuel Distribution (Liquid Fuel / Oil Fuel) 186--Central atomizing nozzle A.1--Part One An--Part n B--Gas flow L--Airflow and mixed airflow VL -- Full load TL -- Partial Load

Claims

1. A combustion method for burning a fuel-air mixture, comprising: a) 100% of the air stream (10) supplied for combustion is fully premixed with the fuel (12). Step a) includes: b) In the first premixing zone (14.1), a first portion (A.1) of the fuel (12) is added to the air stream (10) to form a lean fuel-air mixture (16) that is not yet ignitable; and c) In at least one other premixing zone (14.n), one or more remaining portions (An) of the fuel (12) are mixed into a lean fuel-air mixture (16), the at least one other premixing zone (14.n) being spaced apart from the first premixing zone (14.1) in the flow direction to produce an ignitable fuel-air mixture (18) with excess air. Step c) includes: d) To induce a swirl in the fuel-air mixture (18) formed in at least one other premixing zone (14.n), wherein the combustion method further comprises: e) Allow the fuel-air mixture (18) generated in step c) to flow into the combustion chamber (60) through the outlet opening region (70), and f) Combustion of the fuel-air mixture (18) in the combustion chamber (60) by flames (62, 146).

2. The combustion method according to claim 1, further comprising at least one or more of the following steps: 2-1 The airflow (10) is generated by a blower (50); 2-2 The airflow (10) is preheated, particularly by using the heat of the exhaust gas through a heat exchanger (68); 2-3 Adjust the speed of the airflow (10); 2-4 Adjust the fuel distribution for the premixed zones (14.1, 14.n); 2-5 After the ignitable fuel-air mixture (18) leaves the flame head (42) in the combustion chamber (60), the fuel-air mixture (18) generates the main flame (146); 2-6 The primary flame (146) generated by the ignitable fuel-air mixture (18) is stabilized by the primary flame (150); 2-7 During full-load operation, a larger outlet cross section (70, 70.1, 70.2) is provided for the ignitable fuel-air mixture (18) to the combustion chamber (60), and a smaller outlet cross section (70, 70.1) is provided for the ignitable fuel-air mixture (18) during partial-load operation; 2-8 Distribute the ignitable fuel-air mixture (18) to an outlet region having a fixed outlet cross-section (70.1) and an outlet region having a controllable outlet cross-section (70.2), and control the controllable outlet cross-section (70.2) according to the combustion power to be generated; 2-9 At the end of at least the last premixing zone (14.n), a uniform and ignitable fuel-air mixture (18) is produced, wherein the fuel and air are uniformly distributed across the entire outlet flow cross section (70).

3. The combustion method according to any one of the preceding claims, wherein step b) comprises at least one, more, or all of the following steps: b1) Supply 10% to 80% of the fuel (12) in the first premixed zone (14.1); b2) Supply 30% to 70% of the fuel (12) in the first premixed zone (14.1); b3) Supply 40% to 60% of the fuel (12) in the first premixed zone (14.1); b4) The fuel (12) is supplied through at least one or more hollow bodies (30), the hollow bodies being selected from the group consisting of: hollow bodies (30) with nozzles distributed on their surfaces, hollow bodies (30) having perforated surfaces, perforated gas conduits (32), gas conduits (32) having lateral holes, gas conduits (32) extending transversely to the flow direction and having holes, gas conduits (32) extending longitudinally to the flow direction and having holes, partially annularly extended perforated hollow bodies (30, 34, 36), annularly perforated hollow bodies (30, 34), hollow annular bodies (34), the hollow annular bodies (34) preferably extending in the flow direction along the central axis of the hollow annular bodies (34) and having holes in at least one inwardly facing side region and / or at least one outwardly facing side region, hollow swirl vanes (36) having holes, and combinations of the above hollow bodies (30); b5) Generate a swirling flow in the airflow (10) and supply the first portion of the airflow (10) after the swirling flow is formed; b6) In different annular regions of the first premixing zone (14.1), reverse swirls are generated in the airflow (10); b7) At least at the end of the first premixed zone (14.1), a homogeneous lean fuel-air mixture (16) is formed, wherein the fuel and air are uniformly distributed across the entire flow cross section.

4. The combustion method according to any one of the preceding claims, wherein step c) comprises at least one, more, or all of the following steps: c1) The remaining portion (An) is mixed in the second premixing zone (14.2); c2) The remaining portion (An) is mixed in the second premixing zone (14.2) and the third premixing zone (14.3); c3) Supply 1% to 15% of the remaining portion of the fuel (12) to the primary flame generation zone (76) to generate a primary flame; c4) The fuel (12) is mixed by at least one or more hollow bodies (30) selected from the following: hollow body (30) with nozzles distributed on its surface, hollow body (30) with perforated surface, perforated gas pipe (32), gas pipe (32) with lateral holes, gas pipe (32) extending transversely to the flow direction and with lateral holes, gas pipe (32) extending longitudinally to the flow direction and with lateral holes, partially annular perforated hollow body (30, 34, 36), annular perforated hollow body (30, 34), hollow annular body (34), the hollow annular body (34) preferably extending in the flow direction along the central axis of the hollow annular body (34) and having holes in at least one inwardly facing side region and / or at least one outwardly facing side region, hollow swirl blade (36) with holes, and combinations of the above hollow bodies (30); c5) fuel (12) is supplied through at least one opening in the baffle (78).

5. The combustion method according to any one of the preceding claims, wherein step d) comprises at least one, more, or all of the following steps: d1) To generate a swirling flow in the fuel-air mixture (16, 18) located in the other premixing zone (14.n); d2) In different annular regions of the at least one other premixed zone (14.n), a counter-swirling flow is generated within the fuel-air mixture (16, 18); d3) A swirl is generated in the fuel-air mixture (16) during the transition to the at least one additional premixed zone (14.n); d4) Before mixing, a swirl is generated in the lean fuel-air mixture (16); d5) During mixing, swirls are generated in the fuel-air mixture (16, 18) to be enriched in order to improve combustibility; d6) Swirling flow is generated by perforated swirl blades (36) with a carrier gas; d7) A vortex is generated for the ignition flame (150) by a baffle (78) designed as a vortex unit (26).

6. A premixed burner (40), comprising: The flame tube (44) has an outlet opening area (70) configured to discharge an ignitable fuel-air mixture (18) into a combustion chamber (60) for combustion. An air supply device (48) is used to supply the flame tube (44) with the full air flow (10) for combustion; A premixing device (46) configured to receive 100% of the airflow (10) from the air supply device (46) and premix it with fuel (12) before the airflow (10) leaves the flame tube (44). And the swirling device (28), The premixing device (46) includes: A first fuel supply device (20.1) having a control device, wherein the first fuel supply device (20.1) is configured to add a first portion (A.1) of the fuel (12) to the airflow (10) in a first premixing zone (14.1) to form a lean fuel-air mixture (16) that is not yet ignitable. and at least one additional fuel supply device (20.n), the at least one additional fuel supply device (20.n) having a control device, wherein the at least one additional fuel supply device (20.n) is configured to mix one or more remaining portions (An) of the fuel (16) into the lean fuel-air mixture (16) in at least one other premixing zone (14.n), the other premixing zone being spaced apart from the first premixing zone (14.1) in the flow direction to produce an ignitable fuel-air mixture (18) with excess air, the fuel-air mixture (18) being discharged into the combustion chamber (60) through the outlet opening region (70) of the flame tube (44). The swirling device (28) is configured to at least cause the fuel-air mixture (16, 18) generated or present in the at least one other premixing zone (14.n) to swirl.

7. The premixed burner (40) according to claim 6, wherein the flame tube (44) has at least one or more of the following characteristics: 7-1 Cylindrical sleeve; 7-2 Inlet opening, said inlet opening being designed to receive 100% of the airflow; 7-3 The tapered section near the downstream end; 7-4 Outlet cross-section adjustment device (72), said outlet cross-section adjustment device (72) is used to adjust the outlet cross-section (70.2) of a portion of the outlet opening region (70); 7-5 At least one slider (72) for being able to adjust the outlet cross-section of the flame tube (44) in a variable manner.

8. The premixed burner (40) according to any one of claims 6 or 7, wherein the gas supply device (46) comprises at least one or more of the following features: 8-1 Blower (50), said blower (50) is used to generate said airflow (10); 8-2 Preheating device (66), the preheating device (66) is used to preheat the airflow (10); 8-3 Exhaust gas heat exchanger (68), said exhaust gas heat exchanger (68) preheats the airflow (10) by utilizing the heat of the exhaust gas; 8-4 Exhaust gas supply device (64), the exhaust gas supply device (64) is used to supply exhaust gas to the air flow (10); 8-5 Control device, the control device being used to control the airflow (10); 8-6 Control interface, which can be connected to the control system (52).

9. The premixed burner (40) according to any one of claims 6 to 8, wherein the premixing device (46) further comprises at least one or more of the following features: 9-1 A first premixing zone (14.1) and a second premixing zone (14.2) spaced apart from each other in the flow direction; 9-2 The first premixing zone (14.1), the second premixing zone (14.2), and the third premixing zone (14.3) are arranged sequentially in the flow direction; 9-3 A fixed or variablely adjustable fuel flow channel cross section, the fuel flow channel cross section being used to distribute the portion (A.1, An) of the fuel (12) to the first fuel supply device (20.1) and each subsequent fuel supply device (20.n); 9-4 Adjustment device (82), the adjustment device (82) is used to adjust fuel distribution; 9-5 Fuel distribution ring (84), the fuel distribution ring (84) being used to distribute the fuel (12) to a plurality of premixed zones (14.1, 14.n); 9-6 Control device, the control device being used to control fuel supply; 9-7 Control interface, which can be connected to the control system (52).

10. The premixed burner (40) according to any one of claims 6 to 9, wherein, The first fuel supply device (20.1) has at least one or more of the following features: 10-1 Inlet cross section, the size of which is set relative to the inlet cross section of the at least one auxiliary fuel supply device (20.n) such that a predetermined first portion (A.1) of the fuel (12) flows through the first fuel supply device (20.1); 10-2 Adjustment device (82), the adjustment device (82) is used to adjust the inlet cross-section of the first fuel supply device (20.1); 10-3 At least one or more hollow bodies (30) for supplying fuel, wherein the at least one hollow body is selected from the group consisting of: a hollow body (30) having nozzles distributed on its surface, a hollow body (30) having a perforated surface, a perforated gas conduit (32), a gas conduit (32) having lateral holes, a gas conduit (32) extending transversely to the flow direction and having holes, a gas conduit (32) extending longitudinally to the flow direction and having holes, a partially annularly extended perforated hollow body (30, 34, 36), an annularly perforated hollow body (30, 34), a hollow annular body (34) extending in the flow direction along the central axis of the hollow annular body (34) and having holes in at least one inward or outward side region, a hollow swirl vane (36) having holes, and combinations of the above hollow bodies (30); 10-4 A computer-implemented control device for controlling fuel supply.

11. The premixed burner (40) according to any one of claims 6 to 10, wherein, The auxiliary fuel supply device (20.n) has at least one or more of the following features: 11-1 Inflow cross section, the size of which is set relative to the inflow cross section of the first fuel supply device (20.1) such that a predetermined additional portion (An) of the fuel (12) flows through the additional fuel supply device (20.n); 11-2 The second fuel supply device (20.2) located in the second premixing zone (14.2); 11-3 The third fuel supply unit (20.3) is located in the third premixing zone (14.3); 11-4 Ignition flame fuel supply device, the ignition flame fuel supply device being used to supply a portion of the fuel (12) to the ignition flame (150), the portion supplied to the ignition flame (150) being at most one-third of the portions (A.1, A.2, A.3) of the first fuel supply device and the second fuel supply device (20.1, 20.2, 20.3); 11-5 Adjustment device (82), the adjustment device (82) is used to adjust the inflow cross section of the auxiliary fuel supply device (20.n); 11-6 At least one or more hollow bodies (30) for mixing fuels, wherein the at least one hollow body is selected from the group consisting of: hollow bodies (30) with nozzles distributed on their surfaces, hollow bodies (30) having perforated surfaces, perforated gas conduits (32), gas conduits (32) having lateral holes, gas conduits (32) extending transversely to the flow direction and having holes, gas conduits (32) extending longitudinally to the flow direction and having holes, partially annularly extended perforated hollow bodies (30, 34, 36), annularly perforated hollow bodies (30, 34), hollow annular bodies (34) extending in the flow direction along the central axis of the hollow annular body (34) and having holes in at least one inward or outward side region, hollow swirl vanes (36) having holes, and combinations of the above hollow bodies (30); 11-7 A computer-implemented control device for controlling fuel supply.

12. The premixed burner (40) according to any one of claims 6 to 11, wherein the swirl device (28) comprises at least one or more of the following features: 12-1 Swirl unit (26), the swirl unit (26) is used to generate swirl in the airflow (10) entering the first premixing zone (14.1); 12-2 Reverse swirling device (88), the reverse swirling device (88) is used to generate swirling flows with opposite swirling directions in different annular regions of the flame tube (44); 12-3 A first swirl unit (26.1) and at least one other swirl unit (26.2), wherein the first swirl unit (26.1) is located within or upstream of the first premixing zone (14.1), and the at least one other swirl unit (26.2) is located at the transition to or within the other premixing zone (14.n); The inner side (90) and outer side (94) of the swirl blades (92) are arranged; 12-5 swirl blades (36), the swirl blades (36) being designed as hollow bodies (30), the hollow bodies (30) having nozzles for fuel supply; 12-6 Primary flame swirl unit (26), the primary flame swirl unit (26) is located on the baffle (78).

13. The premixed burner (40) according to any one of claims 6 to 12, comprising at least one or more of the following additional features: 13-1 Baffle (78), said baffle (78) is used to stabilize the primary flame (146); 13-2 Liquid fuel nozzle (80), the liquid fuel nozzle (80) being used to deliver liquid fuel to the combustion chamber (60) downstream of the flame tube (44); 13-3 Control unit (52), the control unit (52) having a processor (54) and a memory (56); 13-4 Control device, the control device being used to control the ratio of the fuel (12) to the air flow (10); 13-5 Control system (52), the control system (52) being configured to cause the premixed burner (40) to perform the combustion method according to any one of claims 1 to 5.

14. A control system (52) for use with the premixed burner (40) according to any one of claims 6 to 13 and configured to cause the premixed burner (40) to automatically perform the combustion method according to any one of claims 1 to 5.

15. A computer program comprising instructions that cause a premixed burner (40) according to any one of claims 6 to 13 to perform the combustion method according to any one of claims 1 to 5.

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