Burner assembly

Abstract

Known burner assemblies comprise at least one duct, leading into a furnace chamber, for a first reactant such as fuel, a plurality of ducts, leading into the furnace chamber, for a second reactant such as oxygen, and a controller for controlling the mass fluxes of the first and second reactant which are fed into the furnace chamber via the ducts. The burner assembly according to the invention additionally comprises, downstream of the controller in a duct for the second reactant, a distribution device for distributing the entirety of the fed mass flux of the second reactant to the plurality of ducts for the second reactant.

Description

[0001] Burner arrangement

[0002] The invention relates to a burner arrangement with at least one feed for a first reactant opening into a furnace chamber and a plurality of feeds for a second reactant opening into the furnace chamber, as well as a control device for controlling the mass flows of first and second reactant introduced into the furnace chamber via the feeds.

[0003] Such burner arrangements are well known and are used, for example, in staged combustion to reduce NOx emissions in combustion processes. The combustion air is supplied to the flame in two or more partial streams from widely separated positions. A portion of the combustion air is thus withheld from the main combustion zone, which generally leads to a substoichiometric combustion reaction and, in the case of carbon-containing fuels, to high carbon monoxide production. The resulting comparatively low adiabatic combustion temperature in the main combustion zone reduces the formation of thermal NOx. In addition, the carbon monoxide produced also directly reduces locally present NOx. The unburned fuel components are subsequently combusted by a secondary air stream at a certain distance from the main combustion zone.The most prominent examples of this type of combustion are boxer furnaces in power plants, where the combustion air is even divided into primary, secondary and tertiary air.

[0004] Because this type of staged combustion requires a lot of space, only large combustion chambers (e.g., steam boilers in power plants) are suitable; they are generally unsuitable for use in glass melting furnaces, for example. Furthermore, the local production of large quantities of carbon monoxide is not always desirable for safety reasons, but also because of the associated disadvantages in product properties.

[0005] In contrast to air burners, oxygen burners (oxyfuel burners) use technically highly pure oxygen as the oxidizer. Especially in the case of high-temperature oxygen burners, such as those used in glass melting furnaces, where combustion chamber temperatures of 1450°C and higher are required, very high concentrations of nitrogen oxides are generated due to residual nitrogen in the oxidizer, the introduction of false air into the furnace chamber, and emissions from the feed materials. Therefore, it has already been proposed to apply the principle of staged combustion to such combustion processes.

[0006] For example, EP 0 762 050 A1 and EP 3 366 994 A1 disclose oxygen burner assemblies with staged combustion. These have a flat flame burner with an oval outlet opening, from which at least one further, likewise oval-shaped outlet lance for secondary oxygen is arranged at a vertical distance. Such multiple oxygen supplies make it possible to vary the oxygen flows supplied via burner and outlet lance(s) and to achieve different oxygen concentrations in different areas of the furnace chamber. The more oxygen is fed to the outer areas of the furnace chamber, the greater the staged combustion and thus the nitrogen oxide-reducing effect. Furthermore, staged combustion has proven particularly advantageous in glass production, where a reduced oxygen concentration below the flame creates a local atmosphere rich in carbon monoxide.The carbon monoxide counteracts the formation of foam in the molten glass and is also able to reduce foam that has already formed.

[0007] However, the known arrangements have the disadvantage of a comparatively complex control technique in terms of apparatus and process technology when changing the mass flows of the gases introduced into the furnace chamber, which is also the object of the present invention to improve.

[0008] This object is achieved in a burner arrangement of the type and intended purpose mentioned above in that a distribution device is connected to a supply line for the second reactant, downstream of the control device (as viewed in the flow direction of the second reactant), by means of which the distribution of a mass flow of the second reactant supplied to the burner arrangement via the supply line to the plurality of supplies for the second reactant can be adjusted. Advantageous embodiments of the invention are specified in the subclaims.

[0009] The burner arrangement according to the invention thus has, in addition to the control device that determines the total reactant flow rates, a distribution device by means of which - even during ongoing operation of the burner arrangement - different distributions (hereinafter also referred to as "operating modes") of the flow rate of one of the reactants introduced into the furnace chamber can be set to its feeds, without changing the total flow rate of this reactant supplied. To set a different operating mode, the respective flow rates of the reactant supplied through the feeds do not have to be switched on or off or adjusted independently of one another; rather, the total flow rate of this reactant supplied to the burner arrangement remains the same even when the operating mode changes and is simply redistributed to the individual feeds.Thus, a reduction in the flow rate at a first feed always leads to an increase in the flow rate at at least one additional feed, and vice versa. Such a distribution device can also be provided for all other reactants that are introduced into the furnace chamber via a plurality of feeds of the burner arrangement.

[0010] For example, a burner arrangement according to the invention consisting of a burner and at least one additional feed lance can be converted during operation from a first operating mode, in which both reactants are introduced completely via the burner, into another operating mode, in which one of the reactants (e.g. oxygen) is introduced only via the feed lance(s) or in a predefined mixed manner via both introduction devices, without the total amount of this reactant introduced into the furnace chamber changing.

[0011] In a particularly space-saving and easy-to-operate embodiment of the invention, the distribution device comprises a distribution element (seen in the flow direction of the reactant) that is fluidly connected on the upstream side to the supply line for the second reactant and on the downstream side via flow passages to the plurality of feeds for this reactant, as well as a distribution disc designed as a perforated disc, which is rotatably mounted on the distribution element but can be locked in predetermined angular positions. The distribution disc is equipped with flow openings that interact with the flow passages of the distribution element to establish a flow connection.The flow openings, which act like an orifice, are distributed in different numbers per area on the distributor disc and / or they have different cross-sections, so that by rotating the distributor disc, the size and / or number of the flow openings interacting with a flow passage of the distribution element, and thus the reactant flow rate introduced into this flow passage, can be changed. In this way, by rotating the distributor disc by a predetermined angle, a predetermined distribution of a flow rate of the second reactant flowing from the supply line to the feeds can be achieved.

[0012] Preferably, the distribution device can be adjusted manually and / or with a servomotor to change the operating modes. In the case of the aforementioned distribution device with a distribution element and distributor disc, the angular position of the distributor disc is preferably adjusted automatically with a servomotor and / or manually with a hand crank.

[0013] In order to be able to adapt the distribution device to different requirements, the distribution disc is expediently detachably connected to the distribution element in order to be able to replace the distribution disc with another distribution disc that can be mounted on the distribution element and has a different number and / or size and / or geometry of flow openings.

[0014] The reactants are fuel and one or more oxidants. For example, the burner assembly according to the invention is designed and suitable for operation with a fuel, such as hydrogen or a carbon-containing fuel, such as natural gas, oil, or coal dust, as the first reactant and with an oxidant, such as pure oxygen or an oxygen-containing gas, such as air, as the second reactant. "Pure oxygen" is understood here to mean a gas that has an oxygen content of at least 90 vol.%, preferably at least 99 vol.%.

[0015] In the burner arrangement according to the invention, the feeds for the first and / or second reactant can be designed as part of a burner, wherein, for example, one feed or multiple feeds for the first reactant and one feed or multiple feeds for the second reactant are arranged coaxially to one another and discharge into the furnace chamber at a common burner mouth. Alternatively or additionally, the feeds for the first and / or second reactant can also be designed in the form of feed lances, by means of which at least a partial stream of the reactant can be introduced into the furnace chamber separately from other reactants or from other partial streams of the same reactant.

[0016] For example, a burner assembly according to the invention comprises a burner with a fuel supply and an oxygen supply for primary oxygen. Furthermore, the burner assembly has at least one supply lance by means of which secondary oxygen can be introduced into the furnace chamber. By means of the distribution device, an oxygen flow supplied to the burner assembly can be distributed in different ways to the oxygen supply of the burner or the supply lance(s).In particular, the burner arrangement can be switched alternately between a first operating mode, in which the oxygen proportion introduced via the burner is essentially stoichiometric to the introduced fuel, and a second operating mode, in which a substoichiometric introduction occurs via the oxygen supply of the burner and full stoichiometricity is achieved by the introduction of secondary oxygen via a supply lance (stage combustion). If the introduction of secondary oxygen occurs above the burner in this second operating mode, an oxygen-poor and carbon monoxide-rich atmosphere forms below the burner. Such an atmosphere is particularly advantageous in glass melting furnaces, as it reduces foam formation in the lower region of the furnace chamber in a glass melt heated by the fuel arrangement according to the invention.The burner arrangement according to the invention is therefore preferably used in a glass melting furnace.

[0017] An embodiment of the invention will be explained in more detail with reference to the drawings. The schematic views show:

[0018] Fig. 1 : A burner arrangement according to the invention in longitudinal section

[0019] Fig. 2: The burner arrangement from Fig. 1 in a front view, seen from

[0020] Direction B in Fig. 1 ,

[0021] Fig. 3a: A distribution device for distributing the oxygen of a burner arrangement according to the invention in longitudinal section,

[0022] Fig. 3b: The distribution device from Fig. 3a in cross section along the section line

[0023] BB in Fig. 3a and

[0024] Fig. 3c: A distribution element in Fig. 3b in the distribution device according to

[0025] Fig. 3a interacting distributor disc in top view.

[0026] The burner arrangement 1 shown in Fig. 1, for example, intended for heating a glass melting furnace, has a burner 2 which is accommodated in a passage 3 of a burner quarl 4. The burner 2 has a cylindrical, central fuel channel 5 for supplying fuel (first reactant) and an oxygen supply 6 arranged coaxially around the latter for supplying primary oxygen (oxygen is the second reactant here), which open into a furnace chamber 8 at a burner mouth 7 of the burner 2. The burner 2 is, for example, a high-impulse burner in which the reactants are introduced into the furnace chamber 8 at a flow velocity of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s. The high velocity of the introduced gases leads to intensive recirculation of the combustion gases present in the furnace chamber, which, among other things,a reduction in the temperature of a flame forming in the furnace chamber 8 (not shown here) and thus a reduction in NOx emissions.

[0027] To enable staged combustion, the burner assembly 1 has a plurality of oxygen lances 10, 11 for introducing secondary oxygen, which, in the exemplary embodiment, are guided through the burner block 4 parallel to the burner axis 12 of the burner 2. An upper oxygen lance 10 is arranged vertically spaced from a horizontal plane (burner plane) 13 running through the axis of the burner 2, while a lower oxygen lance 11 is arranged vertically below the burner plane 13.

[0028] The oxygen lances 10, 11 can also be high-impulse introduction systems, ie the oxygen flow introduced into the furnace chamber 8 by the oxygen lances 10, 11 has a speed of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s.

[0029] Within the scope of the invention, it is also conceivable that not only one oxygen lance 10, 11, but a plurality of oxygen lances (not shown here) are provided above and / or below the burner 2; these can open into the furnace chamber 8, for example, along a horizontal line or in another manner, for example in a ring around the burner 2.

[0030] The fuel channel 5 is connected via a fuel line 15 to a source of a gaseous fuel (not shown here). The fuel used may be, for example, a hydrocarbon-containing gas, such as natural gas, or a hydrogen-containing gas, or a mixture of both. The oxygen supply 6 and the oxygen lances 10, 11 are connected via connecting lines 16, 17, 18 to an oxygen line 19, which in turn is connected to a source of the second reactant (also not shown here), for example, an oxygen tank.

[0031] A control system 20 is arranged in the fuel line 15 and the oxygen line 19 and is in data communication with, for example, an electronic controller 21. Control valves 22, 23 are provided in the control system 20, by means of which the total flow rates of fuel and oxygen introduced into the furnace chamber 8 can be regulated depending on predetermined parameters, such as a temperature measured in the furnace chamber 8. A distribution device 25 is also provided in the oxygen line 19, by means of which an oxygen flow supplied via the oxygen line 19 can be variably distributed between the connecting lines 16, 17, 18, and thus between the oxygen supply 6 and the oxygen lances 10, 11. The distribution device 25 can be adjusted manually or by means of the controller 21, as explained in more detail below by way of example.

[0032] During operation of the burner assembly 1, a fuel flow is introduced into the furnace chamber 8 via the fuel line 15 and the fuel channel 5. At the same time, an oxygen flow is supplied via the oxygen line 19, which is preferably stoichiometric or slightly superstoichiometric to the fuel flow. The oxygen flow is fully distributed among the connecting lines 16, 17, 18 in the distribution device 25 and enters the furnace chamber 8 via the oxygen supply 6 or the oxygen lances 10, 11. There, it is ignited with the fuel flow, whereupon a flame (not shown here) forms in the furnace chamber 8.

[0033] The following operating modes are preferred, which can also be adjusted or changed during operation using the distribution device 25: a) At least a large portion of the oxygen is directed to the oxygen supply 6. The flows of fuel and primary oxygen introduced into the furnace chamber 8 at the burner mouth 7 of the burner 2 are therefore at least almost stoichiometric to one another. No or at most a small oxygen flow is introduced via the oxygen lances 10, 11, which merely serves to cool the oxygen lances 10, 11 and thus only contributes to the combustion of the fuel in the furnace chamber 8 to a small extent. This operating mode is preferred, for example, when starting the burner 2 or for heating up the furnace chamber 2. b) A large portion of the oxygen is introduced into the furnace chamber 8 via the upper oxygen lance 10 (single-stage combustion).A smaller residual flow is introduced via the oxygen supply 6 solely for the purpose of stabilizing the flame forming in front of the burner mouth 7. No or at most a small oxygen flow is introduced via the lower oxygen lance 11, which merely serves to cool the oxygen lance 11 and contributes only slightly to the combustion of the fuel in the furnace chamber 8. In this operating mode, combustion below the burner level 13 is overall substoichiometric. As a result, increased carbon monoxide is formed in this area, which, when the burner assembly 1 is used in a glass melting furnace, suppresses the formation of foam on the molten glass or reduces foam that has already formed.c) All or a large portion of the total oxygen supplied is distributed between the oxygen lances 10, 11 (two-stage combustion), whereby oxygen-rich or oxygen-poor atmospheres can be created above or below the burner level 13 by varying the distribution of the oxygen flows introduced via the upper oxygen lance 10 and the lower oxygen lance 11. Any small residual flow is introduced via the oxygen supply 6 solely for the purpose of cooling the burner 2 (if necessary) or stabilizing a flame. In this operating mode, particularly low levels of nitrogen oxides are produced.

[0034] These operating modes can of course also be set if, instead of the burner arrangement 1 shown here with one oxygen lance 10, 11 above or below the burner level 13, a burner arrangement according to the invention with a plurality of oxygen lances above and / or below the burner level 13 is used.

[0035] With reference to Figs. 3a to 3c, a simple, robust, and cost-effective option is now described for dividing the oxygen flow supplied via the oxygen line 19 into the connecting lines 16, 17, 18 according to the aforementioned operating modes. The distribution device 25 comprises a housing 26 in which a distribution element 27 is permanently mounted. The distribution element 27 is a perforated plate permanently mounted in the distribution device 25 with three flow passages 28a, 28b, 28c, which in turn are in flow communication with the connecting lines 16, 17, 18. In the exemplary embodiment shown here, the flow passages 28a, 28b, 28c are each equally sized, circular segment-shaped openings; however, other geometries and / or size ratios between the three flow openings are equally conceivable within the scope of the invention.

[0036] A distributor disc 29 is mounted on the distribution element 27 and coaxially therewith, rotatably about an axis 30 common to the distribution element 27 and the distributor disc 29. The distributor disc 29 is also designed as a perforated disc and equipped with flow openings 31a, 31b, 31c, 31d. The flow openings 31a, 31b, 31c, 31d are arranged spaced apart from one another in the circumferential direction and, in the exemplary embodiment shown here, each have different cross-sections; alternatively or in addition, a different number of flow openings 31a, 31b, 31c, 31d can also be provided in different regions of the same surface area of ​​the distributor disc 29. The distributor disc 29 is connected via a shaft 32 to a drive arranged outside the housing 26, for example a hand crank 33 or a stepper motor (not shown here). In the embodiment shown in Fig.In the position shown in Figure 3a, the distribution element 27 and the distribution disc 29 are arranged such that the flow passage 28a and the flow opening 31a as well as the flow passage 28c and the flow opening 31c lie one above the other and in this way establish a flow connection between the oxygen line 19 and the connecting line 17 or 16 (further flow connections, not visible here, exist in this position of the distribution disc 29 between the oxygen line 19 and the connecting line 18 via the flow passage 28b and the flow opening 31b as well as between the oxygen line 19 and the connecting line 16 via the flow passage 28c and the flow opening 31d).

[0037] The housing 26, which accommodates the distribution element 27 and the distribution disc 29, is intended to ensure that all of the oxygen supplied via the oxygen line 19 passes through flow openings 31a, 31b, 31c, 31d in the distribution disc 29 and flow passages 28a, 28b, 28c in the distribution element 27 into one or more of the connecting lines 16, 17, 18. It is therefore connected in a gas-tight manner, for example via flange connections, to the oxygen line 19 and the connecting lines 16, 17, 18 and has a likewise gas-tight passage 34 for the shaft 32.

[0038] Due to the different opening cross-sections of the flow openings 31a, 31b, 31c, 31d and / or the number of flow openings 31a, 31b, 31c, 31d per unit area in the distributor disc 29, rotation of the distributor disc 29 causes the oxygen flow supplied from the oxygen line 19 to be distributed differently between the connecting lines 16, 17, 18 and thus between the oxygen supply 6 and the oxygen lances 10, 11. With a suitable design of the distributor disc 29, for example with differently sized flow openings 31a, 31b, 31c, 31d spaced apart in the circumferential direction, the operating modes described above can thus be easily adjusted; in particular, this does not require interrupting the operation of the burner arrangement 1 or changing the oxygen flow supplied via the oxygen line 19.

[0039] The distributor disk 29 shown here with flow openings 31a, 31b, 31c, 31d is merely an example of a possible distributor disk 29. The flow openings 31a, 31b, 31c, 31d of the distributor disk 29 are preferably designed such that the pressure loss of the burner arrangement 1 as a whole remains essentially constant even during the switching of the distributor disk 29 and thus the switching has no influence on the operation of the control system 20 arranged upstream of the oxygen supply 19. The geometries suitable for this purpose and / or the required number of flow openings 31a, 31b, 31c, 31d in the distributor disk 29 depend in particular on the respective intended oxygen flows and must be determined individually, for example empirically, for each burner arrangement 1.

[0040] In order to adapt the distribution device 20 to different requirements, the distributor disc 29 is preferably detachably connected to the distribution element 27, and the housing 26 can be opened in a manner not shown here in order to be able to exchange the distributor disc 29, if necessary, for another distributor disc with a different number and / or size and / or geometry of the flow openings present therein.

[0041] 1 burner arrangement

[0042] 2 burners

[0043] 3 Implementation

[0044] 4 burner stone

[0045] 5 Fuel channel

[0046] 6 Oxygen supply

[0047] 7 Brenner mouth

[0048] 8 Furnace room

[0049] 9

[0050] 10 oxygen lance

[0051] 11 Oxygen lance

[0052] 12 burner axis

[0053] 13 Brenner level

[0054] 14 Vertical plane

[0055] 15 Fuel line

[0056] 16 connecting line

[0057] 17 connecting line

[0058] 18 connecting line

[0059] 19 Oxygen line

[0060] 20 Control system

[0061] 21 Control

[0062] 22 Control valve

[0063] 23 Control valve

[0064] 24 -

[0065] 25 Distribution device

[0066] 26 housings

[0067] 27 Distribution element

[0068] 28a, 28b, 28c Flow passage

[0069] 29 Distributor disc

[0070] 30 axis

[0071] 31 a, 31 b, 31 c, 31 d flow opening

[0072] 32 Wave

[0073] 33 Hand crank

[0074] 34 Implementation

Claims

Patent claims 1. Burner arrangement with at least one feed (5) for a first reactant opening into a furnace chamber (8) and a plurality of feeds (6, 10, 11) for a second reactant opening into the furnace chamber (8), as well as a control device for controlling the mass flows of first and second reactant introduced into the furnace chamber via the feeds (5, 6, 10, 11), characterized in that a feed line (19) for the second reactant is followed, downstream of the control device, by means of which distribution device the distribution of a mass flow of the second reactant supplied to the burner arrangement (1) via the feed line (19) to the plurality of feeds (6, 10, 11) for the second reactant can be adjusted.

2. Burner arrangement according to claim 1, characterized in that the distribution device (20) has a distribution element (27) which is fluidically connected to the supply line (19) on the inflow side and to the feed lines (6, 10, 11) via flow passages (28a, 28b, 28c) on the outflow side, and a distributor disc (29) designed as a perforated disc, which is rotatably mounted on the distribution element (23) but can be locked in predetermined angular positions and is equipped with flow openings (31a, 31b, 31c, 31d) which interact with the flow passages (28a, 28b, 28c) of the distribution element (27) to produce a flow connection, and which are distributed differently on the distributor disc (29) and / or have different flow cross sections such that upon rotation of the distributor disc (29) by a predetermined Angle of rotation a predetermined distribution of a mass flow of the second reactant flowing from the feed line (19) to the feeds (6, 10,11 ) is carried out., 3. Burner arrangement according to claim 1 or 2, characterized in that the distribution device (25) is adjustable manually and / or with a servo motor.

4. Burner arrangement according to one of the preceding claims, characterized in that the distributor disc (29) is detachably connected to the distribution element (27).

5. Burner arrangement according to one of the preceding claims, characterized in that a fuel, such as natural gas or hydrogen, is provided as the first reactant and an oxidant, such as oxygen, is provided as the second reactant.

6. Burner arrangement according to one of the preceding claims, characterized in that at least one feed (5) for the first reactant and at least one feed (8) for the second reactant are arranged in a burner housing.

7. Burner arrangement according to one of the preceding claims, characterized in that at least one feed (5) for the first reactant and / or at least one feed for the second reactant opens into the furnace chamber (8) in the form of a feed lance (10, 11).

8. Glass melting furnace with a furnace chamber (8), characterized in that a burner arrangement (1) according to one of the preceding claims, installed in a wall of the furnace chamber (8), is used to heat the furnace chamber.

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