Nozzle arrangement for burner, and burner having such nozzle arrangement

Abstract

A nozzle arrangement for a combustor (12) has at least one nozzle pair (43, 46) comprising a fuel gas nozzle (43) for injecting fuel gas, the fuel gas nozzle having a fuel gas nozzle longitudinal axis (62), and the fuel gas nozzle (43) being connected to a fuel gas distribution device (17); the nozzle pair further comprises a secondary gas nozzle (46) for spraying a secondary gas, the secondary gas nozzle (46) being connected to the secondary gas distribution device (45); wherein the fuel gas nozzle (43) is arranged at least partially inside the secondary gas nozzle (46) in the direction of the fuel gas nozzle longitudinal axis (62); the secondary gas nozzle (46) covers the fuel gas nozzle (43) in the circumferential direction around the fuel gas nozzle longitudinal axis (62).

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to German patent application DE 10 2023 202 665.1, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a nozzle arrangement for a burner (particularly a gas burner), and to a burner including such a nozzle arrangement. Background Technology

[0004] In asphalt production facilities, various materials are processed, particularly heated, dried, and / or mixed together. During asphalt production, a significant portion of the energy input required for subsequent asphalt mixing processes is generated for drying the materials. The materials are heated during the drying process. Temperature levels can reach up to 450°C, depending specifically on the type of asphalt to be mixed and, in particular, on the proportion of old asphalt particles (also known as recycled materials) to be added. Drying takes place in a rotary kiln (also known as a drying drum). Heat generated by separate heating units is supplied to the rotary kiln. Heat generation is typically based on the combustion of fossil fuels such as natural gas, liquefied petroleum gas, heating oil, and / or pulverized coal. The combustion of fossil fuels contributes to climate problems.

[0005] Other non-fossil fuels, especially non-fossil fuel gases (such as hydrogen), have high reaction rates and result in high flame temperatures, leading to high heat loads on the burners and increased nitrogen oxide emissions. Summary of the Invention

[0006] The purpose of this invention is to enable the use of fuel gas with a high reaction rate in a burner in a highly efficient combustion manner, so that the service life of the burner is not undesirably shortened, and in particular, to achieve gentle operation of the burner.

[0007] According to the present invention, this objective is achieved by a nozzle arrangement having the features of claim 1 and a burner having the features of claim 11.

[0008] It has been found according to the present application that an efficient and advantageous combustion of a gas is possible if the gas is advantageously injected into a burner. By means of a nozzle arrangement according to the present application, which comprises at least one nozzle pair, a fuel gas and a secondary gas can be advantageously injected. Each nozzle pair has one fuel gas nozzle, through which a fuel gas is injected, in particular into a combustion chamber of a burner. It is also conceivable that the fuel gas is injected directly through the fuel gas nozzle into a working space which is to be heated by means of a burner flame. The working space can be, for example, a drying drum in an asphalt mixing plant. The fuel gas nozzle has a fuel gas nozzle longitudinal axis. The fuel gas nozzle is connected to a fuel gas distribution device, in particular to a fuel gas distribution chamber. The fuel gas distribution device can also or alternatively be configured as a pipe, a distribution element and / or a header. The fuel gas is supplied to the fuel gas nozzle by means of the fuel gas distribution device. The fuel gas distribution chamber is in particular configured annularly around a central burner longitudinal axis. The fuel gas nozzle is in particular configured as an inner nozzle.

[0009] The fuel gas is a gas with a high reaction rate, which can be efficiently and selectively combusted to generate heat. The fuel gas has a high flame temperature in air. For hydrogen, the flame temperature in air is 2130 °C. When the combustion temperature reaches 1400 °C, nitrogen oxide emissions occur, which increase approximately exponentially with increasing temperature. The fuel gas is in particular hydrogen and / or acetylene.

[0010] Each nozzle pair further comprises one secondary gas nozzle. The secondary gas nozzle is in particular configured as an outer nozzle and is in particular arranged around the fuel gas nozzle. The secondary gas nozzle serves to inject a secondary gas into the combustion chamber of the burner. In particular, the secondary gas is different from air. In particular, the secondary gas does not contain air. The secondary gas is air-free.

[0011] By using the secondary gas, the high reaction rate of the fuel gas can be selectively reduced in order to reduce the flame temperature, in particular local temperature peaks. By injecting the secondary gas, the combustion reaction in the burner can be selectively slowed down. This means that the combustion reaction is slowed down by adding the secondary gas. In particular, the nozzle arrangement serves to locally influence the flame temperature of the burner flame by selective injection.

[0012] In particular, the fuel gas nozzle and the secondary gas nozzle are arranged such that the supply of fuel gas and secondary gas is separate from the supply of air to the combustion chamber. In particular, fuel gas and secondary gas are supplied together to the combustion chamber, but separately from the air. In particular, a mixture of fuel gas and secondary gas is generated and supplied to the combustion chamber by means of the nozzle arrangement, where it is mixed with the air. In particular, no mixing of air with fuel gas and secondary gas takes place before the combustion chamber. There is no mixing of fuel gas with air in the nozzle arrangement. In particular, no air is supplied to the nozzle arrangement.

[0013] In addition to fuel gas and secondary gas, air is in particular processed in the burner. It is conceivable to supply and additionally burn a further fuel gas, which is referred to as secondary fuel gas. In particular, only gases are processed in the burner. The burner is in particular a gas burner. Furthermore, the burner according to the application can also process liquids and / or solids as fuel.

[0014] It has been found according to the application that by selective injection of secondary gas, the conversion rate of fuel per volume can be reduced. This reduces and in particular prevents the formation of high-temperature zones. Reducing the formation of high-temperature zones makes the combustion reaction more gentle on the burner. The service life of the burner is extended. The burner according to the application has ecological and economic advantages. In particular, it has been found that high-temperature zones are an important cause of the formation of nitrogen oxide (NOx) emissions. Reducing nitrogen oxide emissions makes the operation of the burner particularly environmentally friendly. In particular, the formation of nitrogen oxides can be prevented directly in the combustion process.

[0015] The heat generated according to the application is at least partially and in particular exclusively generated by burning hydrogen gas as fuel gas. The burning of hydrogen gas does not produce carbon dioxide. No carbon dioxide is produced during the burning of hydrogen gas. The burning of hydrogen gas is climate-friendly. Harmful exhaust gases and / or emissions are reduced. It is particularly advantageous if the hydrogen gas is produced from renewable energy sources, or in other words, if it is green hydrogen.

[0016] The burner is used to supply heat to a rotary kiln in a bitumen production facility. To this end, the burner is coupled to the rotary kiln. The burner flame generated by the burner can be burned directly in the rotary kiln. In this case, the burner and the rotary kiln are physically coupled to one another. In this case, the burner is arranged directly at the rotary kiln. Alternatively, the burner flame can be burned at a spatial distance from the rotary kiln, in particular in a hot gas generator. The heat generated thereby can be conducted as hot gas from the hot gas generator to the rotary kiln. The heat generated by the burner is supplied to the rotary kiln as hot gas. In this case, the burner is in particular indirectly coupled to the rotary kiln via a hot gas line.

[0017] The secondary gas is in particular exhaust gas and / or inert gas. The exhaust gas is in particular exhaust gas of an asphalt production plant, in particular of a rotary kiln which is heated by the burner. In this case, the exhaust gas of the rotary kiln is returned directly to the burner via an exhaust gas recirculation line. This direct return is referred to as recirculation. In addition or alternatively, there can be at least one other exhaust gas source from which exhaust gas is returned to the burner. The at least one other exhaust gas source is in particular another rotary kiln, a bucket elevator, a chimney and / or a filter device, in particular a filter dedusting system. In particular, there can be a plurality of exhaust gas recirculation lines which lead different exhaust gas sources to the burner. In particular, there is a system of exhaust gas recirculation lines by which the rotary kiln and / or the at least one other exhaust gas source is fluidically connected to the burner, in particular at least indirectly.

[0018] It is particularly advantageous if the exhaust gas returned is previously purified so that it is essentially free of dust particles. In particular, the exhaust gas returned is flue gas which has a dust particle content of less than 20 mg / m 3 , and in particular less than 10 mg / m 3 . Surprisingly, it has been found that purified exhaust gas, in particular flue gas, is particularly advantageous for slowing down the combustion reaction.

[0019] Alternatively, the exhaust gas can be at least partially loaded with dust particles, in particular with a dust load of less than 35 mg / m 3 .

[0020] In particular, inert gas can also be injected through the secondary gas nozzles. Inert gas is a gas which has a higher inert gas content than ambient air. It has been found that the use of inert gas enables a selective slowing down of the combustion reaction in the burner. Examples of inert gas include nitrogen, water vapor or noble gases such as helium, neon, argon, krypton, xenon and / or radon.

[0021] The secondary gas nozzles are connected to a secondary gas distribution device, in particular to a secondary gas distribution chamber. The secondary gas distribution chamber is configured annularly, in particular around the central burner longitudinal axis. The secondary gas distribution device is in particular arranged spatially separate from the fuel gas distribution device.

[0022] In the nozzle pair, the fuel gas nozzle is arranged at least partially inside the secondary gas nozzle along the fuel gas nozzle longitudinal axis. This means that the fuel gas injected through the fuel gas nozzle is first discharged into the secondary gas nozzle and then injected into the combustion chamber together with the secondary gas in particular. Thus, the fuel gas nozzle injects the fuel gas into the combustion chamber in particular in an indirect manner. Inside the secondary gas nozzle, the fuel gas mixes with the secondary gas. This prevents the fuel gas from coming into direct contact with the combustion air. In particular, an undesired high-temperature combustion can thus be prevented. This mixing is particularly advantageous because the fuel gas nozzle is enveloped, in particular completely enveloped, in the circumferential direction around the fuel gas nozzle longitudinal axis by the secondary gas nozzle. The secondary gas nozzle forms a mixing chamber for mixing the fuel gas and the secondary gas in particular. The mixing process takes place directly and is particularly efficient. The gas mixture thus produced is particularly suitable for combustion.

[0023] It is particularly advantageous if there is no direct mechanical connection between the fuel gas nozzle and the secondary gas nozzle. The fuel gas nozzle is in particular fixed directly to the fuel gas distribution chamber. The secondary gas nozzle is in particular fixed directly to the secondary gas distribution chamber. The fuel gas nozzle is arranged and held inside the secondary gas nozzle, in particular without contact. This in particular makes the gas flow, in particular the flow of the secondary gas through the secondary gas nozzle and around the fuel gas nozzle, continuous and uninterrupted.

[0024] The nozzle arrangement according to claim 2 enables a further improved gas mixing effect. By arranging the fuel gas discharge openings of the fuel gas nozzle inside the secondary gas nozzle, the mixing is improved.

[0025] The nozzle arrangement according to claim 3 makes a selectively adjusted mixing of the gases possible. By arranging the fuel gas discharge openings inside the secondary gas nozzle at a sufficient opening spacing, it can be ensured that the fuel gas has a sufficiently long co-flow path with the secondary gas inside the secondary gas nozzle. In particular, this opening spacing is at least 10%, in particular at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 75% and in particular at most 90% relative to the length of the secondary gas nozzle.

[0026] The cross-sectional area of the fuel gas discharge openings is smaller than the cross-sectional area of the secondary gas nozzle, in particular smaller than the cross-sectional area of the secondary gas nozzle at the axial position at which the fuel gas discharge openings are located. In particular, the cross-sectional area of the fuel gas discharge openings is at most 70%, in particular at most 60%, at most 50%, at most 40%, at most 30%, at most 20% and in particular at most 10% of the cross-sectional area of the secondary gas nozzle.

[0027] Due to the different cross-sectional areas, the flow velocity of the fuel gas is higher than the flow velocity of the secondary gas, in particular at least twice, three times, five times, eight times, or even at least ten times the flow velocity of the secondary gas. In particular, the flow velocity of the fuel gas is at least 500 m / s. The flow velocity of the secondary gas is in particular at least 50 m / s and in particular at most 100 m / s.

[0028] The nozzle arrangement according to claim 4 enables particularly advantageous flow conditions, in particular through the fuel gas nozzle and / or through the secondary gas nozzle at the outer surface of the fuel gas nozzle. Due to the reduced diameter of the fuel gas nozzle, the gas flow loss to the fuel gas nozzle can be reduced. In the reduced diameter, the cross-sectional area of the fuel gas nozzle is reduced in the direction of the longitudinal axis of the fuel gas nozzle. The cross-sectional area is in particular regressively reduced. This means that the outer contour of the fuel gas nozzle is concave and thus in particular curved. Alternatively, a linear reduction of the cross-sectional area can also be implemented, so that the outer contour of the fuel gas nozzle is conical. The cross-sectional shape of the reduced diameter in a plane perpendicular to the longitudinal axis of the fuel gas nozzle is in particular circular. However, the cross-sectional shape of the fuel gas nozzle, i.e. the inner contour, can also be non-circular, for example angularly free, in particular elliptical, or polygonal, such as square or hexagonal.

[0029] The reduced diameter is followed by a constant diameter in the direction of the longitudinal axis of the fuel gas nozzle. The constant diameter has a constant cross-sectional area along the longitudinal axis of the fuel gas nozzle. The fuel gas discharge opening is arranged at the downstream end of the constant diameter. In particular, the cross-sectional area of the constant diameter is the same as the cross-sectional area of the end of the reduced diameter. In particular, the transition from the reduced diameter to the constant diameter is stepless and in particular continuous. Overall, the fuel gas nozzle is approximately funnel-shaped or trumpet-shaped.

[0030] The change in cross-section of the fuel gas nozzle in the reduced diameter and the arrangement of the fuel gas nozzle with the reduced diameter inside the secondary gas nozzle result in a beneficial speed reduction of the secondary gas due to the increasing cross-section upon injection. Due to the difference in flow velocity, the mixing effect of the gases is further improved.

[0031] Alternatively, it is also conceivable that the fuel gas nozzle does not have a reduced diameter. In this case, the fuel gas nozzle can in particular have a constant cross-sectional area along the longitudinal axis of the fuel gas nozzle.

[0032] The nozzle arrangement according to claim 5 enables a particularly advantageous influence on the flow velocity, in particular of the fuel gas.

[0033] The corresponding fuel gas nozzle has in particular an advantageous cross-sectional reduction along the longitudinal axis of the fuel gas nozzle. In particular, the minimum cross-sectional area of the reduced diameter is at most 30%, in particular at most 25%, at most 20%, at most 10%, at most 5%, and in particular at least 1%, of the maximum cross-sectional area of the reduced diameter.

[0034] The nozzle arrangement according to claim 6 enables a simple supply of secondary gas from a secondary gas distribution device, in particular a secondary gas distribution chamber. In particular, the secondary gas can flow directly from the end face into the secondary gas nozzle. The nozzle arrangement is compact and robust. The nozzle arrangement can be easily integrated into a burner. The gas supply structure of the secondary gas distribution chamber is designed in one piece and enables easy integration.

[0035] The nozzle arrangement according to claim 7 is simple in geometry and facilitates low-cost manufacturing. In particular, the secondary gas nozzle itself is configured as a cylindrical sleeve. In particular, the inner contour of the secondary gas nozzle is cylindrical. It is also conceivable that the outer wall of the secondary gas nozzle is non-circular, in particular non-cylindrical, for fixation in the burner and / or is provided with integrated fixation elements.

[0036] According to claim 8, the concentric arrangement of the secondary gas nozzles enables a better gas mixing effect.

[0037] The nozzle arrangement according to claim 9 enables a particularly uniform, in particular homogeneous, injection of the fuel gas mixture. The plurality of nozzle pairs is arranged in circumferential direction around the arrangement central axis, in particular spaced apart from each other in circumferential direction. In particular, the nozzle pairs are arranged uniformly spaced apart in circumferential direction. The nozzle arrangement in particular comprises at least three, in particular at least four, at least six, at least eight, at least twelve, at least sixteen, and in particular at most fifty nozzle pairs. The number of nozzle pairs varies depending on the size of the burner and / or the nozzle diameter. It is particularly advantageous if all nozzle pairs are configured in the same way. It is also conceivable that at least two different nozzle geometries are employed for the fuel gas nozzles and / or the secondary gas nozzles, depending on the burner flame to be generated. Geometrically different nozzles, i.e. nozzle pairs of different geometry, can for example be arranged alternately in circumferential direction around the arrangement central axis. It has been found that the arrangement of nozzles of different geometry in circumferential direction enables an advantageous homogeneous gas injection.

[0038] In particular, the nozzle pairs are in the same axial position relative to the longitudinal axis of the burner. In addition or alternatively, it is also conceivable to arrange the nozzle pairs in different axial positions in order to enable a staged supply of fuel gas in the burner.

[0039] According to claim 10, the inclined arrangement of the nozzle pairs enables an advantageous influence on the geometry of the burner flame, in particular enables a focusing of the burner flame. It is particularly advantageous if all fuel gas nozzles are arranged at the same inclination angle relative to the arrangement central axis. In particular, the fuel gas nozzle longitudinal axes of the plurality of fuel gas nozzles intersect at one point, in particular all fuel gas nozzle longitudinal axes intersect at the same point, which is in particular located on the arrangement central axis.

[0040] It is conceivable that the inclination angle of the nozzle arrangement can be set to different values for different nozzle arrangements. This will enable a selective influence on the distribution profile of the supplied gas. In particular, the flame temperature, in particular the geometry of the burner flame, can be selectively changed.

[0041] The burner according to claim 11 has essentially all the advantages of the aforementioned inventive nozzle arrangement, which are cited here. The burner has a burner head and a combustion chamber, which are arranged in a burner housing. Air is drawn into the burner by means of an air inlet chamber. In the burner head, the combustion air is mixed with the gas injected by means of the nozzle arrangement and burned to form a burner flame. It is particularly advantageous if a swirl element is arranged upstream of the burner head for generating a swirl in the drawn-in air, in particular in the radial direction with respect to the longitudinal axis of the burner. The swirl element is in particular a static element, i.e. it is fixed in the burner.

[0042] The burner according to claim 12 enables an advantageous cooling of the burner head, in particular by means of the drawn-in air as secondary air flowing through the cooling cone from the outside. An annular gap is formed between the cooling cone and the burner head.

[0043] The burner according to claim 13 enables an advantageous supply of gas to the burner head. In particular, it can be ensured that the secondary air does not come into contact with the supplied gas before it reaches the burner head. By means of the nozzle arrangement, the gas passes through the annular gap without coming into contact with the air. In addition, the secondary gas nozzles in the annular gap form a flow obstruction for the secondary air, so that it is further generated in an advantageous swirl.

[0044] The burner according to claim 14 enables an advantageous integration of a fuel gas distribution chamber as a fuel gas distribution device and / or a secondary gas distribution chamber as a secondary gas distribution device on the burner housing. The distribution chambers are arranged on the outer surface of the burner housing, which is simple to implement and in particular enables a subsequent retrofitting. The burner housing can be simply supplemented with corresponding distribution chambers.

[0045] The burner embodiment according to claim 15 enables an advantageous supply of gas to the combustion chamber. In particular, the secondary gas nozzles open directly into the combustion chamber by means of the secondary gas discharge openings.

[0046] The features mentioned in the above claims and in the following description of embodiments of the inventive nozzle arrangement can, both individually or in any combination, be used for the improvement of the subject matter of the present invention. The combination of these features does not limit the improvement of the subject matter of the present invention, but is merely exemplary in nature. BRIEF DESCRIPTION OF DRAWINGS

[0047] Further features, advantageous embodiments and details of the present application will become apparent from the following description of embodiments in conjunction with the attached drawings, in which:

[0048] Figure 1 A schematic view of a bitumen production plant comprising a burner is shown;

[0049] Figure 2 A schematic view of a rotary kiln comprising Figure 1 a burner is shown;

[0050] Figure 3 A sectional view along Figure 2 line III-III in Fig. 3 is shown;

[0051] Figure 4 An enlarged detail view of a nozzle arrangement according to Figure 2 the present application in section IV is shown;

[0052] Figure 5 An enlarged perspective detail view of the nozzle arrangement shown in Fig. 6 is shown. Figure 4 DETAILED DESCRIPTION

[0053] A plant, generally designated 1 in Figure 1 Fig. 1, is used for producing bitumen. The plant 1 comprises a first apparatus 2 and a second apparatus 3, each of which is connected via a discharge line 4 to a (in particular common) filter dedusting system 5.

[0054] The plant 1 can also have only one apparatus 2, 3 or more than two apparatuses 2, 3. It is conceivable that one or more apparatuses 2, 3 are connected via a common discharge line 4 to the filter dedusting system 5. In particular, the filter dedusting system 5 is a central filter dedusting system of the plant 1 to which a plurality of, in particular all, apparatuses 2, 3 of the plant 1 are connected. It is also conceivable that each apparatus 2, 3 is assigned and connected to a separate filter dedusting system 5.

[0055] Optionally, a condensate separator 6 connected via a blower 7 to a chimney 8 is connected to the filter dedusting system 5. As Figure 1 shown, the condensate separator 6 can be arranged downstream of the filter dedusting system 5 and / or in addition or alternatively upstream of the filter dedusting system 5. In particular, in addition to the condensate separator 6, a recovery unit (not shown) is provided for recovering process heat, in particular generated in the condensate separator 6. To this end, the recovery unit can in particular be arranged such that it is integrated into the condensate separator 6.

[0056] ​It has been found that the condensate separator 6 can be advantageously used in the plant 1 if the off-gas of the plant 2, 3 is relatively clean, i.e. has a low level of pollution, in particular less polluted than the off-gas of a burner which combusts fossil fuels.

[0057] Alternatively, the plant 1 can also be configured without the filter dust removal system 5. In this case, the plant 2, 3 is directly connected to the condensate separator 6. It is also conceivable that there are multiple condensate separators 6, in particular one condensate separator 6 per plant 2, 3.

[0058] The first plant 2 comprises a rotary kiln 9 in which material is dried. The rotary kiln 9 has a material inlet 10 and a material outlet 11. In the shown embodiment, the material inlet 10 and the material outlet 11 are arranged at end faces of the rotary kiln 9, in particular at end faces opposite to each other.

[0059] A burner 12 is coupled to the rotary kiln 9. The burner 12 is configured to combust hydrogen as fuel gas and to generate a burner flame 13 which is at least partially arranged within the rotary kiln 9. The burner 12 is a hydrogen burner. The fuel gas is in particular the primary fuel. The primary fuel is mainly, in other words predominantly, the fuel used to generate heat in the burner 12. In particular, only hydrogen is combusted in the burner 12 to generate heat. In particular, a fuel gas line 14 which is connected to a fuel gas reservoir 15 is connected to the burner 12. The fuel gas reservoir 15 is in particular a storage container, in particular a tank, in which fuel gas, i.e. hydrogen, is pre-stored, in particular in gaseous form. The fuel gas reservoir 15 can also be configured to be connected to a fuel gas supply network.

[0060] A connector of a gas control section of the fuel gas line 14 is connected to a fuel gas distribution chamber 17 of the burner 12 via a compensator 16. The fuel gas distribution chamber 17 constitutes a fuel gas distribution device. Other configurations of the fuel gas distribution device are possible, e.g. a pipe, a distribution element or a manifold. The compensator 16 is a flexible compensation element. The compensator 16 is used to compensate movements of the fuel gas line 14, in particular due to thermal length changes, vibrations, wall penetrations and / or settlement events. The compensator 16 is arranged at a flange connection 18 between the fuel gas distribution chamber 17 and the fuel gas line 14.

[0061] An air line 19 is connected to the burner 12 to supply air, in particular ambient air.

[0062] A material transport direction 20 through the rotary kiln 9 is directed from the material inlet 10 to the material outlet 11 and in Figure 1 from right to left. A gas transport direction 21 through the rotary kiln 9 is directed from the burner 12 to the exhaust line 4, i.e. in Figure 1The material conveying direction 20 and the gas conveying direction 21 are oriented counter to each other. The rotary kiln 9 is operated in a counter-current process. The rotary kiln 9 can also be operated in a co-current process.

[0063] A secondary fuel line 22 can be connected to the burner 12 to supply secondary fuel to the burner 12. In particular fossil fuels, such as natural gas, liquefied petroleum gas, heating oil, coal, in particular pulverized coal, synthetic fuels (BtL) and / or wood chips are used as secondary fuel. The secondary fuel line 22 is supplied by a secondary fuel reservoir (not shown). Like the fuel gas reservoir 15, the secondary fuel reservoir can be configured as a storage tank and / or a supply network.

[0064] The connection of the burner 12 to the secondary fuel line 22 and its gas control section is realized via a secondary fuel distribution chamber 23 by means of a compensator 16. The compensator 16 is essentially identical to the compensator 16 on the fuel gas line 14 and is arranged at the respective position between the secondary fuel line 22 and the secondary fuel distribution chamber 23.

[0065] The first device 2 also comprises a waste gas return line 24 connected to the burner 12. The waste gas return line 24 can additionally also be connected directly to the rotary kiln 9, in particular via a branch line (not shown). The waste gas return line 24 serves to return waste gas to the burner 12. The waste gas return line 24 in particular serves for internal recirculation of waste gas from the rotary kiln 9. The waste gas return line 24 is connected directly to the chimney 8. Waste gas, in particular cleaned waste gas, in particular flue gas, is returned to the burner 12 via the waste gas return line 24. In addition, a waste gas bypass line 25 can be provided, by means of which the exhaust line 4 is connected directly to the waste gas return line 24. Dust-laden waste gas can be supplied to the burner 12 via the waste gas bypass line 25.

[0066] The facility 1 can have additional waste gas sources 26, for example filter elements. These additional waste gas sources can be connected directly to the waste gas return line 24 via the waste gas bypass line 25. In addition or alternatively, the waste gas sources 26 can be connected to the filter dust removal system 5 via the exhaust line 4. This makes it possible to supply cleaned waste gas from at least one waste gas source 26 to the burner 12.

[0067] A separate fan 27 is provided in the waste gas return line 24 to improve the supply of waste gas to the burner 12. One or more dampers 28 can be arranged along the waste gas return line 24 to selectively control the waste gas flow and in particular to selectively adjust the amount of added waste gas. In addition or alternatively, the waste gas flow rate can also be controlled using the fan 27, in particular by means of a frequency converter connected thereto.

[0068] In the embodiment shown, the waste gas return line 24 is branched, a first branch leading directly into the rotary kiln 9. A further branch of the waste gas return line 24 leads into the burner 12.

[0069] The rotary kiln 9 is configured to be drivable in rotation about an axis of rotation 29. The drive, in particular the rotary drive, required for this is known per se and is not shown in the figures for the sake of clarity.

[0070] The rotary kiln 9 has a burnout zone 30 extending along the axis of rotation 29 in the region of the burner flame 13. The rotary kiln 9 also has a heat transfer zone 31 in which heat is transferred to the material by convection.

[0071] The second plant 3 is configured substantially identically to the first plant 2, reference being made to the description thereof. One difference is that the second plant 3 comprises, in addition to the burner 12, a hot gas generator 32. The hot gas generator 32 is connected to the rotary kiln 9 by means of a hot gas line 33. The hot gas generator 32 is arranged between the burner 12 and the rotary kiln 9. In the second plant 3, the burner 12 is configured separately from the rotary kiln 9. In particular, the burner 12 is arranged completely outside the rotary kiln 9. The burner flame 13 is therefore arranged in the hot gas generator 32. The burner flame 13 is arranged outside the rotary kiln 9 of the second plant 3.

[0072] In the second plant 3, air guidance, in particular inside the rotary kiln 9 and / or in the hot gas generator 32, can be carried out using a circulating air fan and / or a waste gas fan (not shown in detail). These fans are in particular arranged outside the rotary kiln 9 and / or outside the hot gas generator 32, in particular along the connecting lines. A burnout zone 30 is therefore not required in the rotary kiln 9 of the second plant 3. The rotary kiln 9 of the second plant 3 comprises substantially only a heat transfer zone 31.

[0073] A waste gas return line 24 is therefore provided from the chimney 8 to the burner 12 of the second plant 3. In the embodiment shown, the waste gas return line 24 leading to the second plant 3 is configured separately from the waste gas return line 24 leading to the first plant 2. It is also possible to configure a common waste gas return line 24 with a corresponding branch. The waste gas bypass line 25 can therefore be connected to the waste gas return line 24 leading to the second plant 3. In particular, the rotary kiln 9 of each plant can constitute an additional waste gas source for the other plant.

[0074] In the embodiment shown, each plant 2, 3 has its own separate fuel gas reservoir 15. It is also possible to provide a common, centrally located fuel gas reservoir 15 in the facility 1, which is in fluid communication with a plurality of, in particular all, of the burners 12 of the facility 1.

[0075] The facility 1 accordingly has a central inert gas reservoir 34, also referred to as an inert gas source. Inert gas is stored in the inert gas reservoir 34. The inert gas has in particular a higher inert proportion than ambient air. In particular, nitrogen is used as inert gas. The inert gas reservoir 34 is connected via an inert gas line 35 to the burner 12 of each of the first plant 2 and the second plant 3. It is understood that a separate inert gas reservoir 34 can also be implemented for each burner 12. This makes it possible in particular to supply different inert gases to each burner 12.

[0076] The exhaust gas return line 24 and the inert gas line 35 each constitute a secondary gas line for supplying secondary gas to the burner 12. Secondary gas within the meaning of the present invention can be exhaust gas, in particular purified exhaust gas, and / or inert gas. The secondary gas can be used to selectively influence, in particular slow down, the combustion reaction in the burner 12.

[0077] The burner 12 has a mixing chamber 36 integrated into the burner 12. The mixing chamber 36 serves to mix fuel gas with secondary gas. The mixing chamber 36 is in particular arranged such that fuel gas is mixed with secondary gas before air is supplied from the air line 19. In particular, the fuel gas line 14 and the exhaust gas return line 24 and / or the inert gas line 35 are fluidically connected to the mixing chamber 36. It is also conceivable for the mixing chamber to be arranged outside the burner 12, in particular on the burner 12. The mixing chamber 36 can also be arranged outside and spaced apart from the burner 12 and in particular arranged upstream of the burner 12. It is conceivable for the fuel gas and the secondary gas to be mixed separately before being supplied to the burner 12.

[0078] The structure and function of the first plant 2, in particular the burner 12, will be explained in more detail below with reference to Figure 2 the second plant 3.

[0079] The burner 12 has a burner housing 38 with a longitudinal axis 37. The burner housing 38 has an air inlet chamber 39 at one end facing away from the rotary kiln 9, through which air, in particular ambient air, is drawn into the burner housing 38. To this end, the air line 19 and / or the silencer can be connected to the air inlet chamber 39. An air blower 40 is arranged along the burner housing 38 and is configured as an axial blower in the embodiment shown. It is understood that the air blower 40 can also be configured as a different type of blower, in particular a radial blower.

[0080] The burner 12 has in particular a flame sensor 41 for monitoring the burner flame 13. In particular, a plurality of flame sensors 41 can be implemented on the burner 12 and arranged spaced apart from one another, in particular in the burner housing 38, in particular along the longitudinal axis 37. Furthermore, there is a pilot burner 42 in the burner housing 38 for igniting the burner flame 13.

[0081] The fuel gas line 14 is connected to the burner housing 38 via a fuel gas distribution chamber 17. This fuel gas distribution chamber 17 is arranged annularly around the burner housing 38. At least one fuel gas nozzle 43 is connected to this fuel gas distribution chamber 17 in order to selectively supply fuel gas to the burner housing 38. In particular, a plurality of fuel gas nozzles 43 is provided.

[0082] Therefore, at least one, in particular a plurality, of secondary fuel nozzles 44 is connected to the secondary fuel distribution chamber 23. This secondary fuel nozzle 44 can be configured as a gas lance and can in particular be arranged in the burner housing 38 adjacent to the fuel gas nozzles 43.

[0083] The secondary gas line, i.e. the exhaust gas recirculation line 24 and / or the inert gas line 35, is connected to a secondary gas distribution chamber 45 of the burner 12. This secondary gas distribution chamber 45 constitutes a secondary gas distribution device and cooperates analogously to the fuel gas distribution chamber 17, which is referred to here for its description. This secondary gas distribution chamber 45 in particular extends around the burner housing 38. At least one, in particular a plurality, of secondary gas nozzles 46 for selectively discharging secondary gas to the burner housing 38 is connected to this secondary gas distribution chamber 45.

[0084] This at least one fuel gas nozzle 43 and this at least one secondary gas nozzle 46 constitute a nozzle arrangement 47, which is shown purely schematically in a simplified manner in Figure 2 .

[0085] In the region of the nozzle arrangement 47, in particular upstream of the nozzle arrangement 47, a swirl element 48, likewise shown only schematically, is arranged in the burner housing 38. This swirl element 48 serves to swirl the air tangentially. This swirl element 48 is in particular configured as a baffle, which in particular has a flow guide wheel. Depending on the fuel combination used, and thus in particular depending on the secondary fuel, in particular the secondary combustion gas, the swirl element 48 can be configured differently in terms of diameter, shape and / or structural details.

[0086] It is also conceivable to arrange the nozzle arrangement 47 upstream of the swirl element 48 and / or to arrange the individual nozzles 43, 46 upstream and / or downstream of the swirl element 48.

[0087] The swirl element 48 is arranged in a cooling cone 49 of the burner 12. In the shown embodiment, the cooling cone 49 has a cylindrical portion, which has an outer diameter of at least 80% of the inner diameter of the burner housing 38 at this point. In particular, the cooling cone 49 has an outer diameter of at least 85%, in particular at least 90%, in particular at least 95%, and in particular at most 99% of the inner diameter of the burner housing 38 at this point. The cooling cone 49 is in particular arranged in a region of the burner housing 38, in which the burner housing 38 is conically widened. The burner housing 38 has an expansion 50, which transitions into a cylindrical end portion 51. The end portion 51 and the expansion 50 constitute a burner head 52. A circumferential, in particular conically configured, annular gap 53 is formed between the outer wall of the cooling cone 49 and the inner wall of the burner head 52. The air flowing through the annular gap 53 is referred to as secondary air. Thus, the secondary air flows through the cooling cone 49. The air flowing centrally through the cooling cone 49 is referred to as primary air. Due to the fact that at least a portion of the air flows around the cooling cone 49 as secondary air, an air staging is possible.

[0088] In the shown embodiment, the burner head 52 improves the mixing of the combustion gases, in particular hydrogen and air. The burner flame 13 is formed downstream of the burner head 52, the shape of the burner flame being influenced by the geometry of the burner head. This means that the shape of the burner flame 13 can be selectively adjusted by appropriately selecting the burner head geometry. In particular, the larger the diameter at the outlet of the burner head 52, the larger the diameter D of the burner flame 13. F The larger the diameter D of the burner flame 13, the larger the diameter D of the burner flame 13.

[0089] The burner 12 is fixed to an end wall 54 of the rotary kiln 9. The end wall 54 is referred to as an outlet end wall, since the material outlet 11 is located in this region. The burner 12, in particular the burner housing 38, is fixed to the end wall 54 by means of fastening elements (not shown in detail).

[0090] The end wall 54 is arranged on the rotary kiln 9 overlapping in the axial direction and / or in the radial direction of the rotation axis 29. The end wall 54 constitutes a cover for the cylindrical opening of the rotary kiln 9. In particular, the rotary kiln 9 is not sealed by the end wall 54. A circumferential gap 55 is left between the end wall 54 and the rotary kiln 9. The circumferential gap 55 makes it possible to additionally supply air, in particular ambient air, to the rotary kiln 9.

[0091] The burner 12 is in particular arranged on the rotary kiln 9 in such a way that its longitudinal axis 37 coincides, i.e. is identical, with the rotation axis 29 of the rotary kiln 9. The burner 12 is arranged concentrically with the rotary kiln 9. The burner 12 is directly fixed and at least partially integrated into the rotary kiln 9. In particular, the burner head 52 and the burner flame 13 generated by the burner 12 are arranged, in particular completely, within the rotary kiln 9.

[0092] The burner 12 has a burner frame 56 via which the burner 12 is placed on the base. In the shown embodiment, the burner frame 56 is configured static, i.e. fixed, in particular secured. The burner frame 56 can also be configured movable, in particular along the longitudinal axis 37. To this end, the burner frame 56 can have rollers on its lower surface, which can in particular roll on suitable tracks. For an axial movement of the burner 12, an axial drive, in particular a pneumatic drive, is advantageous.

[0093] Along the longitudinal axis 37 or the rotational axis 29, the burner flame 13 has a length L F and a diameter D F oriented perpendicular thereto.

[0094] The rotary kiln 9 has an inner diameter D i In the burn-out zone 30, there are fireproof interior members 57 fixed to the inner wall of the rotary kiln 9. Due to these fireproof interior members 57, there is a reduced inner diameter D red in the burn-out zone 30. In axial direction, the fireproof interior members 57 extend along a length L A corresponding to the length of the burn-out zone 30. It is crucial that the length L A of the burn-out zone 30 is greater than the length L F of the burner flame 13 and that the burner 12 is arranged on the rotary kiln 9 in such a way that the burner flame 13 is arranged completely within the burn-out zone 30, in particular in axial direction of the rotational axis 29. It is also crucial that the diameter D F of the burner flame 13 is smaller than the reduced diameter D red . A direct flame contact of the fireproof interior members 57 is prevented.

[0095] A deflection plate 58 is arranged in the heat transfer zone 31 and is in particular fixed to the inner side of the rotary kiln 9. The deflection plate 58 is configured open and serves to form a material veil 59. It is in particular advantageous that the material veil 59 is as dense as possible. The density of the material veil 59 can be quantified indirectly, in particular by measuring the exhaust gas temperature. The lower the exhaust gas temperature, the greater the amount of heat previously transferred to the material. This means that the lower the exhaust gas temperature, the denser the material veil 59, and vice versa. The exhaust gas temperature depends on the burner output, the intended amount output, i.e. the mass flow rate of the material supplied to the rotary kiln 9, and the material temperature. The material temperature is in particular an input variable for controlling the burner output. It has been found that in the shown embodiment, an exhaust gas temperature of at least 100°C is advantageous.

[0096] It is understood that the exhaust gas temperature for monitoring the material veil 59 can assume different values depending on the material used, the burner 12 used or the combustion gas used.

[0097] The nozzle arrangement 47 will be described in the following with reference to Figures 3 to 5 in more detail.

[0098] The nozzle arrangement 47 serves for injecting gas into the combustor 12, in particular into the combustor head 52. The nozzle arrangement 47 has a plurality of nozzle pairs (in the shown embodiment 16 pairs), which are arranged annularly, in particular concentrically, around the longitudinal axis 37 of the combustor housing 38. The annular arrangement has an arrangement center axis 60, which coincides with the longitudinal axis 37. In circumferential direction around the arrangement center axis 60, the nozzle pairs are arranged spaced apart from each other, and in particular uniformly spaced apart. It is understood that there can be more or less than 16 pairs of nozzles. In particular, the circumferential distance between each other can be chosen to be different from each other, and in particular in any desired manner.

[0099] Each nozzle pair comprises a fuel gas nozzle 43 for injecting fuel gas into a combustion chamber 61 of the combustor 12. The combustion chamber 61 is understood to be the region, which is enclosed by the combustor head 52 and which faces the opening of the combustor 12. The fuel gas nozzle is connected to the fuel gas distribution chamber 17, and thus in fluid communication with the fuel gas distribution chamber 17. The fuel gas distribution chamber 17 is annular around the longitudinal axis 37 of the combustor housing 38. The fuel gas nozzle 43 has a fuel gas nozzle longitudinal axis 62, which is arranged inclined with respect to the longitudinal axis 37 by an inclination angle n. In particular, the nozzle pairs are each arranged with respect to the arrangement center axis 60 by the inclination angle n, such that the fuel gas nozzle longitudinal axes 62 intersect. In particular, all fuel gas nozzle longitudinal axes 62 intersect at a common point P, which is in particular on the arrangement center axis 60.

[0100] The fuel gas nozzle 43 is in particular an inner nozzle. The fuel gas nozzle 43 is at least partially arranged inside the secondary gas nozzle 46 along the fuel gas nozzle longitudinal axis 62.

[0101] Each nozzle pair further comprises a secondary gas nozzle 46 for injecting secondary gas into the combustion chamber 61. The secondary gas nozzle 46 is essentially a hollow cylinder, and in particular is arranged concentrically with the fuel gas nozzle longitudinal axis 62. The secondary gas nozzle 46 is in particular configured as a single piece, and in particular as a cylindrical sleeve.

[0102] The secondary gas nozzle 46 is connected to a secondary gas distribution chamber 45. The secondary gas distribution chamber 45 extends annularly around the longitudinal axis 37 of the combustor housing 38. It is crucial that the secondary gas distribution chamber 45 is configured separate from the fuel gas distribution chamber 17.

[0103] In a circumferential direction around the longitudinal axis 62 of the fuel gas nozzle, the secondary gas nozzle 46 sheaths, in particular completely sheaths, the fuel gas nozzle 43. The secondary gas nozzle 46 constitutes an outer nozzle arranged in a sleeve-like manner around the fuel gas nozzle 43. The secondary gas nozzle 46 is arranged at an axial distance from the side wall 63 of the fuel gas distribution chamber 17 with respect to the longitudinal axis 62 of the fuel gas nozzle. The spaced arrangement results in a flow-in gap between the side wall 63 and an end opening 64 of the secondary gas nozzle 46 facing the secondary gas distribution chamber 45.

[0104] The fuel gas nozzle 43 has a fuel gas discharge opening 65 arranged within the secondary gas nozzle 46. This makes it possible to pre-mix fuel gas and secondary gas in the secondary gas nozzle 46.

[0105] In particular, the fuel gas discharge opening 65 is arranged with an opening spacing A from a secondary gas discharge opening 66 of the secondary gas nozzle 46 oriented along the longitudinal axis 62 of the fuel gas nozzle. The opening spacing A is at least 10% of the length L of the secondary gas nozzle 46. S

[0106] The fuel gas nozzle 43 has a reduced-diameter portion 67 and an immediately following constant-diameter portion 68 along the longitudinal axis 62 of the fuel gas nozzle. The reduced-diameter portion 67 faces the fuel gas distribution chamber 17. The fuel gas nozzle 43 is in particular configured as a single piece.

[0107] In the reduced-diameter portion, the cross-sectional area of the fuel gas nozzle 43 decreases along the longitudinal axis 62 of the fuel gas nozzle. The decrease in the cross-sectional area is in particular gradual, but can also be configured to be linear. The outer contour of the reduced-diameter portion 67 is correspondingly configured to be concave or conical. The cross-sectional shape perpendicular to the longitudinal axis 62 of the fuel gas nozzle is in particular circular, but can also be other shapes, in particular oval or polygonal.

[0108] The constant-diameter portion is in particular configured to be cylindrical. It is crucial that the transition from the reduced-diameter portion to the constant-diameter portion is continuous and in particular edge-free.

[0109] The fuel gas nozzle 43 is in its entirety configured to be funnel-shaped or horn-shaped.

[0110] The minimum cross-sectional area of the reduced-diameter portion 67 is at most 50% of the maximum cross-sectional area thereof.

[0111] The operation of the facility 1, in particular the functioning of the burner 12 including the nozzle arrangement 47, will be explained in more detail in the following.

[0112] ​In the first plant 2, material is supplied to the rotary kiln 9 via the material inlet 10 and is conveyed through the rotary kiln 9 along a material conveying direction 20. In the heat transfer zone 21, the deflection plates 58 create a dense, continuous and uniform material curtain 59 so that the material is arranged within the rotary kiln 9 with a very large surface area. The material is heated by convection using the burner flame 13 which is arranged directly inside the rotary kiln 9.

[0113] The burner flame 13 is generated by the burner 12 which is operated with hydrogen as fuel gas. The hydrogen combustion can be slowed down by adding secondary gas, in particular returned off-gas and / or inert gas. This reduces the conversion rate of the fuel gas per volume. High temperature zones are prevented. In particular, it is ensured that high temperature zones are located only within the burnout zone 30.

[0114] Both the fuel gas and the secondary gas are sucked in by means of Figures 3 to 5 The shown nozzle arrangement 47 advantageously sprays. The fuel gas, in particular hydrogen, is provided in the burner 12 via the fuel gas distribution chamber 17 and is sprayed via the fuel gas nozzles 43. Due to the special configuration of the fuel gas nozzles 43, in particular with the reduced diameter portion 67, the fuel gas is advantageously sucked in and discharged at the fuel gas nozzle discharge opening 65 with a relatively high injection speed. The fuel gas is discharged into the secondary gas nozzles 46 which suck in the secondary gas via the end openings 64 from the secondary gas distribution chamber 45. The suction speed of the secondary gas is lower than the injection speed of the fuel gas. This speed difference between fuel gas and secondary gas leads to an improved mixing of fuel gas and secondary gas. The mixing takes place in particular inside the secondary gas nozzles 46. The secondary gas nozzles 46 constitute a mixing chamber for mixing fuel gas and secondary gas. It is also advantageous that the fuel gas is centrally, i.e. concentrically, sprayed into the secondary gas nozzles 46.

[0115] By adding secondary gas, i.e. in particular purified off-gas and / or inert gas, the high temperature zones are reduced, so that the formation of nitrogen oxides is reduced.

[0116] In particular, the nozzle arrangement according to the application ensures an advantageous mixing of fuel gas and secondary gas, in particular before the contact of the fuel gas with the combustion air takes place in the combustion chamber 61. The fluid flow is schematically shown in Figure 5 The flow arrows 69 indicate the fuel gas, the flow arrows 70 indicate the secondary gas, the flow arrows 71 indicate the primary air and the flow arrows 72 indicate the secondary air.

Claims

1. Nozzle arrangement for a burner (12), wherein the nozzle arrangement comprises at least one nozzle pair (43, 46) comprising: a. a fuel gas nozzle (43) for injecting a fuel gas, having a fuel gas nozzle longitudinal axis (62), the fuel gas nozzle (43) being connected to a fuel gas distribution device (17), b. a secondary gas nozzle (46) for injecting a secondary gas, the secondary gas nozzle (46) being connected to a secondary gas distribution device (45), wherein the fuel gas nozzle (43) is arranged at least partially inside the secondary gas nozzle (46) along the fuel gas nozzle longitudinal axis (62), wherein the secondary gas nozzle (46) envelopes the fuel gas nozzle (43) in a circumferential direction around the fuel gas nozzle longitudinal axis (62).

2. The nozzle arrangement of claim 1, wherein, The fuel gas nozzle (43) has a fuel gas discharge opening (65) arranged inside the secondary gas nozzle (46).

3. The nozzle arrangement of claim 2, wherein, The fuel gas discharge opening (65) is arranged with an opening spacing (A) in the orientation of the fuel gas nozzle longitudinal axis (62) relative to a secondary gas discharge opening (66) of the secondary gas nozzle (46).

4. A nozzle arrangement according to any preceding claim, characterised in that, The fuel gas nozzle (43) has a reduced diameter portion (67) and an equal diameter portion (68) following along the fuel gas nozzle longitudinal axis (62).

5. The nozzle arrangement of claim 4, wherein, The smallest cross-sectional area of the reduced diameter portion (67) is at most 50% of the largest cross-sectional area of the reduced diameter portion (67).

6. A nozzle arrangement according to any preceding claim, characterised in that, The secondary gas nozzle (46) is arranged spaced apart from the fuel gas distribution device (17) relative to the fuel gas nozzle longitudinal axis (62).

7. A nozzle arrangement according to any preceding claim, characterised in that, The secondary gas nozzle (46) is cylindrical about the fuel gas nozzle longitudinal axis (62).

8. A nozzle arrangement according to any preceding claim, characterised in that, The secondary gas nozzle (46) is arranged concentrically with the fuel gas nozzle longitudinal axis (62).

9. A nozzle arrangement according to any preceding claim, characterised in that A plurality of nozzle pairs are arranged spaced apart from each other in a circumferential direction around an arrangement center axis (60).

10. The nozzle arrangement of claim 9, wherein, The fuel gas nozzle longitudinal axes (62) are each arranged obliquely relative to the arrangement center axis (60) with an oblique angle (n), the fuel gas nozzle longitudinal axes (62) intersecting, in particular at one common point (P), in particular lying on the arrangement center axis (60).

11. Burner comprising: a. a burner housing (38) having a burner head (52) and a combustion chamber (61), b. an air intake chamber (39) for sucking in air, c. a nozzle arrangement according to any one of the preceding claims arranged in the burner housing (38).

12. The burner of claim 11, wherein The burner head (52) is enveloped by a cooling cone (49), an annular gap (53) being formed between the cooling cone (49) and the burner head (52).

13. The burner of claim 12, wherein The secondary gas nozzle (46) traverses the annular gap (53).

14. Burner according to any one of claims 11 to 13, characterized in that The fuel gas distribution device (17) and / or the secondary gas distribution device (45) are arranged on an outer side of the burner housing (38).

15. Burner according to any one of claims 11 to 14, characterized in that The secondary gas nozzle (46) opens into the combustion chamber (61), in particular directly.

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