Combustor liner
By designing a porous burner bushing with a regular hollow mesh and spiral support, the problem of burner bushing consistency and characteristic control in the prior art has been solved, achieving predictable burner performance and structural stability, and simplifying the optimization process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EDWARDS LTD
- Filing Date
- 2021-10-05
- Publication Date
- 2026-06-02
AI Technical Summary
Existing porous burner bushings are made of fiber or polyurethane foam, which have connecting lines that affect macroscopic consistency and burner characteristics that depend on operator experience and repeated testing, making them difficult to predict and control.
A porous burner bushing composed of a regularly perforated mesh is used, and an optically opaque wall structure is formed by additive manufacturing, including interconnected basic concentric layers and helical supports, avoiding connecting lines and enabling predictable burner characteristic control.
It provides a burner structure with consistent inner surface ignition rate, low back surface temperature and minimum thickness, which simplifies the optimization process, avoids repeated trials, and ensures macroscopic consistency and performance stability of the structure.
Smart Images
Figure CN116324276B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to radiant burners for gas emission reduction systems, particularly porous burner bushings, methods for designing porous burner bushings, and methods for manufacturing porous burner bushings. Background Technology
[0002] Radiation burners are known and commonly used to treat exhaust gas streams from manufacturing tools used, for example, in the semiconductor or flat panel display manufacturing industries. During such manufacturing, residual compounds are present in the exhaust gas stream pumped out of the manufacturing tools.
[0003] Known radiant burners use combustion to remove compounds from exhaust gas streams. Fuel gas is mixed with the exhaust gas stream, and this mixture is fed into a combustion chamber laterally surrounded by the outlet surface of a porous gas burner. Fuel gas and air are simultaneously supplied to the porous burner liner to achieve flameless combustion at the outlet surface. The amount of air passing through the porous burner liner is sufficient not only to consume the fuel gas supply to the burner but also to consume all combustibles in the gas stream mixture injected into the combustion chamber.
[0004] Typically, porous burner liners are made of laminated stacks of fibers or polyurethane foam, which can be powder-coated and sintered in various ways, or left unsintered.
[0005] The inventors have discovered that known bushings suffer from many drawbacks. For example, both fiber-based bushings and foam bushings are typically formed from sheets, which leads to the presence of join lines, affecting their macroscopic consistency. Furthermore, since both fiber lamination and foam formation processes are random or pseudo-random, altering the characteristics of burner bushings has, to date, relied on operator experience and trial-and-error.
[0006] The present invention at least partially solves these and other problems of the prior art. Summary of the Invention
[0007] In a first aspect, the present invention provides a porous burner bushing for a gas emission reduction system. The porous burner bushing includes a hollow body defined by walls. The walls comprise a plurality of interconnected, substantially concentric layers, wherein each layer of the wall comprises a substantially regular perforated mesh. The substantially regular perforated mesh of each layer is configured such that it is out of phase with one or more adjacent layers. Furthermore, the walls comprise a sufficient number of layers arranged such that the walls are optically opaque when viewed from the outside in any radially inward direction perpendicular to the walls.
[0008] In a second aspect, the present invention provides a porous burner bushing for a gas emission reduction system, the burner bushing comprising a hollow body defined by a wall, the wall comprising a plurality of interconnected layers, wherein each layer comprises at least one right-handed basic helical strut connected to at least one left-handed basic helical strut.
[0009] The present invention also provides a method for manufacturing a porous burner bushing according to the foregoing aspects, preferably by additive manufacturing.
[0010] Advantageously, the porous burner bushing and manufacturing method disclosed herein can provide a regular structure that mimics the random structure of existing foam and fiber laminate burner bushings, thereby allowing burner characteristics to be controlled in a predictable manner, simplifying optimization, and avoiding the need for iterative trials associated with known burner bushing designs.
[0011] The result is a combustion-supporting structure with a consistent inner surface ignition rate, low back surface temperature, and minimal thickness. Near-optical blindness can be achieved with as few as six layers, and three times the amount required for optical blindness provides a sufficiently low back surface temperature. The design goal can be to achieve maximum thermal conductivity within the layers while minimizing thermal conductivity between layers. Typically, in use, the back surface temperature (i.e., the temperature of the outermost wall) will be approximately ambient temperature (e.g., 22°C). Typically, in use, the inner surfaces (e.g., the innermost walls) will be at temperatures ranging from approximately 800°C to approximately 1000°C. Fuel and air typically flow from the back surface to the inner surface for combustion. Attached Figure Description
[0012] The present invention will be further described with reference to the following drawings, which are intended to be non-limiting.
[0013] Figure 1 and Figure 2 A schematic diagram of the porous burner layer is provided.
[0014] Figure 3 A single left-handed helix is shown in the image of a porous burner bushing.
[0015] Figure 4 The left-hand and right-hand helices of the porous burner bushing are shown.
[0016] Figure 5 One layer of the porous burner bushing is shown.
[0017] Figure 6 The two layers of the porous burner bushing are shown.
[0018] Figure 7 The ten layers of the porous burner bushing are shown.
[0019] Figure 8The innermost layer of the replacement porous burner bushing is shown.
[0020] Figure 9 The burner bushing with an intermediate spacer layer is shown in two layers.
[0021] Figure 10 The optically opaque wall of the porous burner bushing is shown.
[0022] Figure 11 Showing Figure 10 A top view of the burner bushing wall.
[0023] Figure 12 A burner bushing with an external perforated foil cover is shown.
[0024] Figure 13 Showing the formation Figure 2 The spiral strip of foil covering in the middle.
[0025] Figure 14 The truncated conical burner bushing is shown. Detailed Implementation
[0026] This invention provides a porous burner bushing for a gas emission reduction system. The burner bushing includes a hollow body defined by a wall. The wall includes multiple interconnected layers.
[0027] Each layer of the wall defining the hollow body may include a generally regular perforated mesh. Typically, the mesh will include multiple supports and nodes arranged to form a porous mesh. The mesh may consist of one or more repeating units, preferably each repeating unit is substantially identical, and preferably each repeating unit includes multiple supports and nodes defining one or more pores or voids. Typically, the volume proportion of voids is relatively large compared to the volume proportion of repeating units, preferably the majority of the volume of the repeating unit is voids.
[0028] Preferably, the porous burner bushing is optically opaque when viewed from the outside in any radially inward direction perpendicular to the outermost surface of the wall. Therefore, the wall can comprise enough layers arranged such that there is no straight radially inward path from the outermost surface of the wall to the innermost surface that is not blocked (i.e., intersecting) by at least one pillar and / or node forming part of the wall. The perforated mesh has voids or pores that provide a straight radially inward path through the entire thickness of the layer. Therefore, a single-layer porous burner bushing wall cannot be both perforated and optically opaque.
[0029] The minimum number of layers required to achieve optical opacity may be affected by the diameter of the strut and the phase shift between adjacent layers.
[0030] Preferably, the wall comprises more layers than the minimum number required to achieve optical opacity, preferably at least twice the number of layers required to achieve optical opacity, and more preferably at least three times the number of layers required to achieve optical opacity. Typically, the wall comprises at least three layers, for example from about 3 to about 20 layers, preferably from about 4 to about 12 layers, and more preferably from about 4 to about 9 layers.
[0031] Advantageously, the three times optical opacity provides a sufficiently low back surface temperature (e.g., approximately ambient temperature) during use.
[0032] Each layer of the perforated mesh can be configured such that it is out of phase with one or more adjacent layers. That is, when viewed radially inwards perpendicular to the outer surface of the layer, the repeating units of adjacent layers are not aligned. Instead, typically, the repeating units of one layer are circumferentially offset from the repeating units of adjacent layers, such that when viewed radially inwards perpendicular to the outermost layer of the wall, the nodes of adjacent layers are not aligned.
[0033] Preferably, when viewed radially inward along the outermost layer perpendicular to the wall, at least a portion of the corresponding struts of repeating units in adjacent layers will at least partially, but not completely, overlap. The circumferential offset between adjacent layers can be referred to as the interlayer pitch. Typically, the interlayer pitch is from about 5% to about 30% of the strut diameter, for example, about 10%.
[0034] Preferably, the mesh is substantially continuous throughout the entire layer. Advantageously, there may be no connecting lines within each layer.
[0035] Preferably, the layer includes at least one right-handed basic helical strut connected to at least one left-handed basic helical strut, and preferably includes a plurality of right-handed basic helical struts connected to at least one left-handed basic helical strut.
[0036] When a layer comprises two or more right-handed basic helical struts connected to two or more left-handed basic helical struts, preferably, the right-handed struts are substantially parallel and the left-handed struts are substantially parallel.
[0037] Preferably, the right-handed pillars of each layer are substantially parallel to the right-handed pillars of each other layer. Preferably, the left-handed pillars of each layer are substantially parallel to the left-handed pillars of each other layer.
[0038] Preferably, the right-hand and left-hand pillars of each layer have substantially the same helical pitch. The helical pitch can be defined as the height of a complete helical loop, measured parallel to the helical axis.
[0039] Right-handed and left-handed spiral struts of a layer can also be circumferentially offset from the intralayer pitch. Typically, the intralayer pitch can be the same as or different from the interlayer pitch.
[0040] Here, either right-handed or left-handed helices can be referred to as instances. A wall layer may include one or more instances, typically two or more. Preferably, the number ranges from about 6 to about 400 instances, more preferably from about 8 to about 120 instances. For a given helical pitch and burner bushing circumference, reducing the number of instances in a layer will increase the node spacing. For burner bushings with relatively high helical pitches, the number of instances is typically higher (from about 100 to 400 instances), while for burner bushings with relatively low helical pitches, the number of instances is typically lower (from about 6 to about 20 instances). Generally, for a given strut diameter and in-layer pitch, the higher the number of instances per layer, the fewer layers are required to achieve optical opacity.
[0041] As discussed, the intra-layer pitch and inter-layer pitch can be substantially the same. Preferably, the intra-layer pitch is from about 5% to about 30% of the strut diameter, for example, about 10%.
[0042] In addition to the number of layers required to contribute to optical opacity, the positive-zero interlayer and intralayer pitches ensure that the helical struts can intersect with adjacent helical struts at the nodes. That is, the struts overlap radially at the nodes relative to the longitudinal axis of the burner liner.
[0043] The amount of overlap contributes to both the structural integrity of the wall and the radial thermal conductivity. Therefore, a balance can be struck between these two properties depending on the burner's material selection, size, and intended use. It has been found advantageous to overlap the strut diameter radially with respect to the longitudinal axis of the burner bushing by approximately 10%, preferably from about 5% to about 15%, particularly in low helical pitch embodiments.
[0044] Conversely, it has also been found that intralayer overlap of approximately 100%, such as greater than approximately 90% or greater than approximately 95% of the strut width, is advantageous, particularly for relatively high helical pitch embodiments in which each layer includes a relatively high number of samples.
[0045] For the purposes of this invention, a relatively low helical pitch can be considered to have a helical angle from about X to about Y.
[0046] Additionally or alternatively, a relatively high helical pitch can be considered to have a helical angle greater than Y, preferably from about V to about W.
[0047] As discussed, in embodiments, each layer may include a plurality of right-handed basic helical struts connected to a plurality of spaced-apart left-handed basic helical struts. Additionally, one or more basic helical struts of each layer may intersect with and be integrally formed with the basic helical struts of adjacent layers. Preferably, each basic helical strut intersects with and is integrally formed with the basic helical struts of adjacent layers.
[0048] In an alternative embodiment, one or more radially extending spacers may connect the first layer to adjacent layers. Typically, multiple circumferentially separated radially extending spacers separate the first layer from adjacent layers. The radially extending spacers are in the form of intermediate spacer layers that separate each adjacent main layer of the wall.
[0049] Preferably, the spacers are spaced substantially uniformly around the outer surface of the inner layer and the inner surface of the outer layer, and are connected to the outer surfaces of both layers. The spacers typically separate one layer from the adjacent layer by a radial distance substantially equal to the diameter and / or radial thickness of the spacer. In the case of multiple intermediate spacer layers in a porous burner, the spacers of adjacent intermediate spacer layers are preferably offset circumferentially. The spacers can advantageously reduce radial / interlayer heat conduction (e.g., when the node-to-node spacing is relatively low) and / or increase the thermal path through the burner.
[0050] Radially extending spacers can be in the form of slats, but are typically longitudinally extending slats. Longitudinally extending slats can usually be substantially straight, although they can also be in the form of a helix or a portion thereof.
[0051] Intermediate spacer layers are typically used in the walls of porous burner bushings with low node spacing, for example less than about 4 mm, preferably from about 1 mm to about 4 mm.
[0052] As those skilled in the art will understand, the dimensions of the walls of a porous burner bushing will depend on the intended use, and therefore the invention is not intended to be limited to any particular wall geometry. However, typically, the walls of a porous burner bushing will be substantially tubular with a substantially annular cross-section. The radial thickness of the wall is typically relatively small compared to the radius of the tube it provides.
[0053] Typically, the walls of a porous burner bushing will have an axial length of from 50 mm to about 500 mm, more preferably from about 60 mm to about 200 mm, such as about 75 mm and about 150 mm.
[0054] The inner diameter of the wall of the porous burner bushing can be from about 50 mm to about 250 mm, preferably from about 100 mm to about 200 mm, for example about 150 mm and about 175 mm.
[0055] Typically, the aspect ratio (i.e., the ratio of the inner diameter of the wall to its height) is from about 5:1 to about 1:5, for example from about 3:1 to about 1:3. An aspect ratio greater than 1:1 is preferred, for example from about 1:1 to about 1:5, or preferably from about 2:3 to about 1:3.
[0056] The radial thickness of the wall of the porous burner bushing is preferably from 1 to about 10 mm, and more preferably from about 2 mm to about 6 mm.
[0057] Without being bound by theory, the number of helical turns completed by each basic helical strut in each layer will be determined by its helical pitch and the aspect ratio of the porous burner bushing. For example, for a burner bushing of a given length, a relatively low-pitch helix can perform a relatively high number of helical turns, while for a burner of the same length, a relatively high-pitch helix will perform a lower number of helical turns.
[0058] A porous burner bushing can be provided in which each layer of right-handed and left-handed basic helical struts completes more than one full helical turn. Alternatively, each basic helical strut can complete a partial helical turn, preferably one or fewer.
[0059] refer to Figure 1 and Figure 2 For ease of understanding, Figure 1 and Figure 2 The unfolded layers, which have been flattened, are shown.
[0060] H = Height
[0061] HP = Helical pitch
[0062] <° = Helix angle = Tan -1 (HP / C)
[0063] C = perimeter = π. D
[0064] D = diameter
[0065] C / I = Perimeter divided by the number of samples
[0066] I = (sample of LH or RH spiral in the layer)
[0067] NS = node spacing = (C 2 +HP 2 ) 0.5 / (2xI)
[0068] n = starting angle, calculated as ((360 / sample) / (offset-1) = 0, n, 2n, 3n, etc.
[0069] Table 1 illustrates, with non-limiting examples, how adjusting various parameters of the burner bushing (including inner diameter, height, wire diameter, intra-layer pitch, sample, layer and inter-layer pitch) can facilitate control of nodal spacing, density, and nodal spacing relative to wire dimensions. It is noteworthy that, for example, nodal spacing can be significantly increased or decreased without affecting the bulk density of the burner bushing to varying degrees.
[0070]
[0071] Table 1
[0072] *The starting angle is calculated as ((360 / sample) / (offset-1)0, n, 2n, 3n, etc.
[0073] **Achieve blindness based on arbitrary parameters of line thickness and line spacing.
[0074] Therefore, technicians can adjust the characteristics of the burner bushing in a predictable manner, thereby solving the problem of identifying known porous burners.
[0075] Preferably, the porous burner bushing wall has a bulk density of from about 65% to about 90%, more preferably from about 70% to about 85%. This can be calculated by comparing the calculated mass of the porous structure with the mass of a solid cylinder having the same nominal dimensions.
[0076] Turning Figure 3 The diagram illustrates a left-handed basic helical support (1). The helix (1) has a height (H) of 75 mm and a helical pitch of 25 mm. Therefore, the helix (1) shown in the diagram has three helical turns. The support diameter is 0.3 mm.
[0077] Figure 4 Showing the connection to Figure 2 A left-handed helical support (1) and a right-handed helical support (2) are formed to create a pair of helical samples (3). The right-handed helix (2) is substantially the same as the left-handed helix (1), except for their direction of rotation. The interlayer offset is 0.27 mm, such that where the basic helical supports overlap, their overlap is approximately 10% of their diameter. Preferably, the basic helical supports of the sample pair meet at one end in an end-to-end, face-to-face configuration. Figure 3 In the embodiment shown, the two ends of the spiral struts forming the sample pair meet in an end-to-end face-to-face configuration.
[0078] While not strictly necessary, it is preferred that each helical strut of a layer begins at node (13) and / or ends at node (14), and preferably, each helical strut of each layer of the wall begins at node (13) and / or ends at node (14). This configuration can simplify manufacturing and / or improve structural robustness.
[0079] Figure 5 Showing according to Figure 3 The layer comprises twelve sample pairs (twenty-four spiral samples). This layer is the innermost layer of the wall. The wall has an inner diameter (D) of 75 mm. The spiral struts all have a substantially circular cross-section. The spiral struts all have substantially the same diameter (e.g., 0.3 mm).
[0080] Figure 6 Showing Figure 5The first layer (4) is surrounded by the second layer (5). In the illustrated embodiment, the second layer (5) comprises the same number of samples as the innermost layer (4). Typically, each layer will comprise the same number of samples, although they may increase or decrease in the same radially outward direction.
[0081] The interlayer pitch between the first and second layers is 0.27 mm. The intralayer offset is 0.27 mm. Therefore, where the struts of adjacent layers form nodes, they overlap by approximately 10% of their diameter.
[0082] As can be seen from the second layer (4) offset from the innermost layer, the optical transparency of the burner liner is reduced. That is, when viewed radially inward, the outer layer area with a direct, unobstructed path to the longitudinal axis of the burner liner is reduced.
[0083] As discussed above, preferably, the porous burner bushing comprises enough layers to be optically opaque. Advantageously, this means there is no direct radial path from the outer surface of the burner bushing to the inner surface, which would lead to localized overheating.
[0084] Figure 7 The porous burner bushing wall (6) is shown, which includes Figure 5 and Figure 6 The layers shown are constructed as ten concentric layers. The burner bushing wall is optically opaque in any radial inward direction perpendicular to the outer surface of the wall.
[0085] Preferably, the porous burner bushing comprises at least three times the minimum number of layers required to achieve the optical opacity of the selected layer configuration, each of which is referred to herein individually as an opacity group. The minimum number of layers required to achieve optical opacity can be calculated using finite element analysis. The wall may comprise from about 9 to about 25 layers.
[0086] Advantageously, it can be seen that the porous burner bushing does not include connecting lines because each layer is substantially uniform and continuous. The absence of connecting lines improves the macroscopic uniformity of the burner bushing and ultimately enhances its performance. In embodiments, the burner bushing may be substantially transversely isotropic.
[0087] Figure 8 The innermost layer (7) of the porous burner with an alternative configuration is shown.
[0088] As illustrated, layer (7) comprises multiple left-handed (8) and right-handed (9) helical struts. In this example, the intralayer overlap of the basic helical struts is approximately 100%. That is, the helical struts pass directly through each other at each node (16). The height of the porous burner bushing is also 75 mm; however, the helical pitch is 250 mm, thus each helical strut completes 0.3 helical turns. The helical struts have a diameter of 0.3 mm. There are 120 samples in this layer. This can be considered a relatively steep angle (high helical angle) structure. Such structures may be advantageous because they can be more easily additively manufactured.
[0089] As in the previous embodiments, the basic spiral struts meet at one end in an end-to-end, face-to-face configuration.
[0090] Preferably, each helical strut of a layer begins at a node and / or ends at a node (15), and preferably each helical strut of each layer of the wall begins at a node and / or ends at a node. This configuration can simplify manufacturing and / or improve mechanical strength and structural robustness.
[0091] As can be seen from Figure 1 and Table 1, this arrangement type may provide a node spacing that is significantly smaller than... Figures 1 to 7 The arrangement shown.
[0092] Smaller node spacing may contribute to higher thermal conductivity.
[0093] The illustrated perforated mesh features repeating units with diamond-shaped cell units. Figure 8 and Figure 9 As can be seen, the repeating units within a layer are basically the same. Similarly, the repeating units in each layer are basically the same as those in the adjacent layers.
[0094] In one embodiment, adjacent layers may be formed directly on the outer surface of the inner layer.
[0095] Alternatively, such as Figure 9 As illustrated, radially adjacent layers (10, 11) can be joined together using one or more radially extending spacers (12). In the illustrated embodiment, the radially extending spacers (12) are in the form of one or more longitudinally extending slats (12). The slats illustrated are substantially straight.
[0096] The circumferential spacing (CS) of the radially extending spacer (12) is equal to or greater than the node spacing (NS) of the layer, preferably greater than the node spacing (NS) of the layer, and preferably at least twice the node spacing (NS) of the layer.
[0097] In embodiments, the radially extending spacers (12) can be considered in the form of intermediate spacer layers that separate the main layers (10, 11) of the wall (i.e., those formed by the basic helical struts). Preferably, each intermediate spacer layer (12) may comprise from about 10 to about 50 longitudinally extending strips, preferably from about 20 to about 30 longitudinally extending strips, for example, 24. Preferably, the longitudinally extending strips of the spacer layer are circumferentially spaced substantially uniformly (i.e., evenly spaced around the periphery of the layer to which they are attached).
[0098] Preferably, the longitudinally extending slats have a circumferential spacing of from about 5 to about 20 mm, for example, 10 mm. The diameter of the slats may be larger or smaller than the diameter of the basic helical strut, but preferably they are substantially the same.
[0099] Advantageously, providing radially extending spacers can significantly reduce the layer-to-layer thermal conductivity of the wall and / or further increase the adjustability of the porous burner bushing and / or improve the structural integrity of the wall.
[0100] like Figure 9 and Figure 11 As illustrated, due to the out-of-phase nature of adjacent layers (10, 11), the nodes (17, 18) (19, 20) of adjacent layers are offset. That is, the nodes of one layer do not overlap with the nodes of the adjacent layers. Preferably, as illustrated, starting from the innermost layer, the node of the next outer layer is positioned such that it is substantially radially aligned with the centroid of the unobstructed path (void) through all its radially inward layers leading to the center of the burner bushing. Typically, this arrangement is repeated from the innermost layer of the wall until optical opacity is achieved. The same arrangement can then be repeated by any other group of opacities located radially outward.
[0101] It will be understood that the number of layers required to achieve optical opacity will vary depending on the thickness (diameter) of the basic helical strut, the number of samples per layer, the form and number of radially extending spacers, and the diameter of the walls. Preferably, about four or five layers are required to achieve optical opacity.
[0102] Preferably, the basic helical support has a substantially circular cross-section. Preferably, the basic helical support has a diameter from about 0.1 mm to about 1 mm, more preferably from about 0.2 mm to about 0.7 mm, for example 0.3 mm.
[0103] Preferably, the wall comprises at least three times the minimum number of layers required to achieve optical opacity (i.e., at least three groups of opacities). Figure 10 An optically opaque wall (23) according to this embodiment is shown.
[0104] Increasing the number of opaque groups increases the thermal path from the outermost surface of the burner bushing wall to the innermost surface. Preferably, each opaque group repeats the same layer-to-layer offset pattern as its radially inward opaque group to achieve opacity.
[0105] Advantageously, this arrangement has been found to provide the desired heat transfer characteristics commensurate with known burner bushings.
[0106] Preferably, when present, the radially extending spacers of adjacent intermediate spacer layers, particularly the longitudinally extending strips (21, 22), can also be circumferentially offset. This arrangement in Figure 8 and Figure 11 As shown in the diagram. Advantageously, this can also increase the thermal path and / or reduce the thermal conductivity through the wall.
[0107] The porous burner bushings illustrated so far are all basically cylindrical tubes; however, it will be understood that the burner bushings according to the present invention can take other hollow body forms, for example... Figure 14 The hollow truncated conical burner bushing shown is illustrated. Those skilled in the art will understand that the spiral path of the struts and the shape of the repeating units can vary throughout the layer and / or between layers to accommodate a non-cylindrical hollow body.
[0108] The inventors have also discovered that using a consistent circular cross-section strut to form a hollow truncated conical burner results in higher porosity at the blunt end of the cone, which is more pronounced in structures with a large aspect ratio. This can be achieved by varying the cross-section of the strut from one end to the other. For example, a smaller helical strut diameter can be used at the narrow end of the truncated conical burner bushing, and a larger diameter strut at its wider end; or more preferably, helical struts with elliptical cross-sections of different cross-sections can be used; or still more preferably, inclined elliptical cross-section struts can be used at the large end, wherein the inclination angle matches the cone angle.
[0109] Additionally or alternatively, the porous burner bushing may also include one or more flow distribution elements, preferably such as Figure 13 The diagram shows a pair of counter-rotating spiral bands (26, 27).
[0110] Typically, the spiral pitch and band geometry are chosen so that a circular pattern of a selected number of samples provides a controlled open area.
[0111] like Figure 12As shown, the porous burner bushing described herein may also include a perforated sheet (24) attached to the outermost (upstream) layer of the wall, the perforated sheet defining the outer surface of the porous burner bushing. Preferably, the holes (25) of the sheet are substantially aligned with the voids in the outermost layer of the wall. The perforated sheet (24) may be integrally formed with or subsequently attached to the remainder of the burner bushing. Additionally or alternatively, the perforated foil may be formed from a circular pattern of reverse-rotating strips, for example, multiple of which are in... Figure 13 It is displayed in the middle.
[0112] Preferably, the flow distribution element provides approximately 5% of the opening area (e.g., the area of the orifice) and / or 0.75 mm. 2 and 1mm 2 The pore size (e.g., hole size), for example, 0.8 mm. 2 .
[0113] Preferably, the flow distribution element, such as a strip and / or perforated sheet, is metallic, preferably comprising a metal or alloy, preferably a high-temperature oxidation-resistant alloy, and preferably selected from iron-chromium-yttrium alloys. Groups of 600 and 718, 314 stainless steel, and iron-chromium-aluminum alloys.
[0114] Preferably, the porous burner bushing is a single, integral structure. It is preferably made of a single material, most preferably a metallic material.
[0115] Preferably, the porous burner bushing is additively manufactured, preferably using powder bed fusion technology. Preferably, the construction direction is parallel to the longitudinal axis of the porous burner bushing.
[0116] Alternatively, the burner liner can be formed from a fusion line.
[0117] Preferably, the burner bushing is metallic. More preferably, the burner bushing is made of metal or alloy, preferably a high-temperature oxidation-resistant alloy, and more preferably selected from the group consisting of iron-chromium-yttrium alloys, Inconel 600 and 718, 314 stainless steel, and iron-chromium-aluminum alloys.
[0118] The burner bushing of the present invention can be fitted into the radiant burner of a gas emission reduction system, preferably for flameless combustion with inward ignition. The present invention also provides a gas emission reduction system comprising a porous burner according to the aspects and embodiments disclosed herein. The porous burner bushing according to the present invention can be installed during the manufacture of the radiant burner or retrofitted to a pre-used radiant burner. Suitable radiant burners are described in EP1773474A and / or sold by Edwards Vacuum (RTM) under the trade name Atlas (RTM).
[0119] To avoid ambiguity, features of any aspect or embodiment described herein may be combined with necessary modifications.
[0120] It will be understood that various modifications may be made to the illustrated embodiments without departing from the spirit and scope of the invention as defined by the appended claims, as interpreted under patent law.
[0121] Figure Labels
[0122] 1. Left-handed spiral support
[0123] 2 Right-hand spiral support
[0124] 3 Spiral sample pairs
[0125] 4 Innermost layer
[0126] 5 Second layer
[0127] 6. Porous burner bushing wall
[0128] 7 Innermost layer
[0129] 8. Left-handed spiral
[0130] 9. Right-handed spiral
[0131] 10 Inner Layer
[0132] 11 Outer layer
[0133] 12 longitudinally extending slats
[0134] 13 nodes
[0135] 14 nodes
[0136] 15 nodes
[0137] 16 nodes
[0138] 17 nodes
[0139] 18 nodes
[0140] 19 nodes
[0141] 20 nodes
[0142] 21. Longitudinal slats
[0143] 22 Longitudinal slats
[0144] 23 wall
[0145] 24 Perforated Sheets
[0146] 25 holes
[0147] 26 Spiral Ribs
[0148] 27 Spiral Ribbon
[0149] 28. Frustum conical porous burner bushing
Claims
1. A porous burner bushing for a gas emission reduction system, the burner bushing comprising a hollow body defined by a wall comprising a plurality of interconnected concentric layers; in, Each layer of the wall consists of a regularly perforated mesh; Each layer of the regular perforated mesh is configured such that it is out of phase with one or more adjacent layers, and the wall comprises a sufficient number of layers arranged such that the wall is optically opaque when viewed from the outside in any radially inward direction perpendicular to the wall. One or more radially extending spacers in the form of longitudinally extending slats connect the first layer to the adjacent layer.
2. The porous burner bushing according to claim 1, wherein, Each layer includes at least one right-handed spiral pillar connected to at least one left-handed spiral pillar.
3. The porous burner bushing according to claim 1, wherein, The wall comprises more layers than are required to achieve optical opacity.
4. The porous burner bushing according to claim 3, wherein, The wall comprises at least twice the number of layers required to achieve optical opacity.
5. The porous burner bushing according to any one of claims 1 to 4, wherein, The wall comprises 3 to 20 layers.
6. The porous burner bushing according to claim 2, wherein, Each layer of right-handed and left-handed spiral pillars completes more than one full spiral turn.
7. The porous burner bushing according to claim 6, wherein, The spiral support of each layer intersects with the spiral support of the adjacent layer and forms an integral part of it.
8. The porous burner bushing according to any one of claims 1 to 4, wherein, Each layer includes multiple circumferentially spaced right-handed helical struts, which are connected to multiple circumferentially spaced left-handed helical struts.
9. The porous burner bushing according to claim 8, wherein, Each spiral support completes less than one spiral turn.
10. The porous burner bushing according to any one of claims 1 to 4, wherein, Multiple radially extending spacers separate the first layer from the adjacent layers.
11. The porous burner bushing according to claim 10, wherein, The spacers are evenly spaced apart.
12. The porous burner bushing according to any one of claims 1 to 4, wherein, The multiple interconnect layers are arranged concentrically.
13. The porous burner bushing according to any one of claims 1 to 4, wherein, The hollow body is tubular or truncated conical.
14. The porous burner bushing according to any one of claims 1 to 4, wherein, The outermost layer of the wall is connected to a perforated sheet defining the outer surface of the porous burner bushing, wherein the perforations of the sheet are aligned with the openings in the outermost layer of the wall.
15. An additively manufactured porous burner bushing according to any of the preceding claims, wherein, The burner liner is manufactured using powder bed fusion.