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Title:
FLUID DISPERSION APPARATUS
Document Type and Number:
WIPO Patent Application WO/2016/074095
Kind Code:
A1
Abstract:
A burner for a flash smelting furnace comprises a tubular lance enclosing a first gas flow passage and having a lower end portion which includes one or more gas outlet passages. The lower end portion has upper and lower annular sealing surfaces facing one another, with an annular nozzle portion located between the upper and lower annular sealing surfaces. The gas outlet passages are at least partly defined by the annular nozzle portion, and extend between the first gas flow passage and the outer surface of the lance. The annular nozzle portion may comprise a plurality of arcuate segments which are separable from each other and from the upper and lower sealing surfaces, such that the annular nozzle portion can be removed for service upon separation of the upper and lower annular sealing surfaces from one another.

Inventors:
JASTRZEBSKI MACIEJ URBAN (CA)
MARINCIC IVAN (CA)
VICKRESS DUSTIN ALEXANDER (CA)
ASSIE TAJINDER (CA)
HAYWOOD ROSS JEFFREY (AU)
Application Number:
PCT/CA2015/051183
Publication Date:
May 19, 2016
Filing Date:
November 13, 2015
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HATCH LTD (CA)
International Classes:
F27B15/14; C22B5/02; C22B15/00; F23D1/00; F27B15/10; F27D3/16
Foreign References:
US20110074070A12011-03-31
Attorney, Agent or Firm:
RIDOUT & MAYBEE LLP (250 University AvenueToronto, Ontario M5H 3E5, CA)
Download PDF:
Claims:
What is claimed is:

1 . A burner for a flash smelting furnace, wherein the burner comprises a tubular lance enclosing a first gas flow passage and having an outer surface, the lance extending along a longitudinal axis and having a lower end portion which includes one or more gas outlet passages extending outwardly from said axis, wherein the lower end portion comprises: an upper annular sealing surface and a lower annular sealing surface, wherein the upper and lower annular sealing surfaces face each other;

an annular nozzle portion located between the upper and lower annular sealing surfaces;

wherein the said one or more gas outlet passages are at least partly defined by the annular nozzle portion, said one or more gas outlet passages extending between the first gas flow passage and the outer surface of the lance.

2. The burner of claim 1 , wherein the annular nozzle portion comprises a plurality of arcuate segments.

3. The burner of claim 2, wherein each of the arcuate segments of the annular nozzle portion describes an arc of about 180 degrees or less.

4. The burner of claim 2 or 3, wherein the annular nozzle portion includes at least two of said arcuate segments.

5. The burner of any one of claims 2 to 4, wherein the arcuate segments are separable from each other and from the upper and lower sealing surfaces, upon separation of the upper and lower annular sealing surfaces from one another along the longitudinal axis.

6. The burner of any one of claims 1 to 5, wherein the upper annular sealing surface, the lower annular sealing surface and the annular nozzle portion are each located in a plane which is substantially perpendicular to the longitudinal axis.

7. The burner of any one of claims 1 to 6, wherein at least a portion of the annular nozzle portion is releasably clamped between the upper annular sealing surface and the lower annular sealing surface.

8. The burner of any one of claims 1 to 7, wherein the annular nozzle portion has at least one upper surface portion which is sealed to the upper annular sealing surface and at least one lower surface portion which is sealed to the lower annular sealing surface.

9. The burner of any one of claims 1 to 8, wherein the lower end portion of the lance includes a dispersion cone in the form of a truncated cone, the dispersion cone having an upper edge and a lower edge, wherein the lower edge is of larger diameter than the upper edge, and wherein the upper annular sealing surface is provided at the lower edge of the dispersion cone.

10. The burner of any one of claims 1 to 9, wherein the lance comprises an outer lance tube and an inner lance tube, wherein the inner and outer lance tubes are concentrically arranged and extend along the longitudinal axis, wherein the first gas flow passage is provided in an annular space between the inner and outer lance tubes, and wherein the inner lance tube includes an inner lance flange which closes a lower end of the first gas flow passage, and wherein the lower annular sealing surface is formed on said inner lance flange.

1 1 . The burner of any one of claims 1 to 10, wherein the annular nozzle portion comprises:

a continuous upper surface sealed to the upper annular surface;

a continuous lower surface sealed to the lower annular surface;

an inner face and an outer face; and

a plurality of said gas outlet passages;

wherein each of the gas outlet passages is located between the upper and lower surfaces of the annular nozzle portion, and wherein each of the gas outlet passages extends between the inner and outer faces of the annular nozzle portion.

12. The burner of claim 1 1 , wherein the annular nozzle portion includes a plurality of said gas outlet passages, wherein the gas outlet passages are spaced apart along a circumference of the annular nozzle portion, and wherein each of the gas outlet passages comprises a cylindrical hole extending from the inner face to the outer face of the annular nozzle portion.

13. The burner of claim 1 1 , wherein the annular nozzle portion includes one of said gas outlet passages, and wherein said one gas outlet passage is in the form of a substantially continuous slit extending about substantially an entire circumference of said annular nozzle portion.

14. The burner of claim 13, wherein the substantially continuous slit has a variable cross-sectional height between the inner face and the outer face of the annular nozzle portion, having a maximum height at the inner face and/or the outer face, and a minimum height at a point between the inner and outer faces, defining a converging-diverging nozzle opening.

15. The burner of any one of claims 1 to 10, wherein the annular nozzle portion has an outer portion and an inner portion, the outer portion being located radially outwardly of the inner portion, wherein the outer portion of the annular nozzle portion is in sealed engagement with the upper and lower annular sealing surfaces, and wherein the inner portion of the annular nozzle portion is located radially inwardly of the upper annular sealing surface.

16. The burner of claim 15, wherein the annular nozzle portion has an upper surface which includes an annular shoulder which extends upwardly along the longitudinal axis from the outer to the inner portion of the annular nozzle portion, such that the inner portion is of greater thickness than the outer portion.

17. The burner of claim 15 or 16, comprising a plurality of said gas outlet passages, wherein each of the gas outlet passages is defined by an open channel formed in the outer portion of the annular nozzle portion, and one or both of the upper annular sealing surface and the lower annular sealing surface, wherein each of the open channels is in flow communication with the first gas flow passage.

18. The burner of claim 17, wherein each of the gas outlet passages is defined by said open channel and by both the upper annular sealing surface and the lower annular sealing surface, such that each of the gas outlet passages has a top defined by the upper annular sealing surface, a bottom defined by the lower annular sealing surface, and opposed sides defined by sides of the open channel, and wherein the open channel extends inwardly into the inner portion of the annular nozzle portion and is in flow communication with the first gas flow passage.

19. The burner of claim 17, wherein at least some of said gas outlet passages comprise upper gas outlet passages, each of the upper gas outlet passages being defined by said open channel and by the upper annular sealing surface, wherein the open channel is formed in the upper surface of the annular nozzle portion, such that each of the upper gas outlet passages has a top defined by the upper annular sealing surface, a bottom defined by a bottom surface of said open channel, and opposed sides defined by sides of said open channel.

20. The burner of claim 17 or 19, wherein at least some of the gas outlet passages comprise lower gas outlet passages, each of the lower gas outlet passages being defined by said open channel and by the lower annular sealing surface, wherein the open channel is formed in the lower surface of the annular nozzle portion, such that each of the lower gas outlet passages has a top defined by a top surface of said open channel, a bottom defined by the lower annular sealing surface, and opposed sides defined by sides of said open channel.

21 . The burner of any one of claim 20, wherein the inner portion of the annular nozzle portion is provided with a plurality of communication openings extending between the upper surface and the lower surface of the annular nozzle portion, and providing said flow communication between the lower gas outlet passages and the first gas flow passage.

22. The burner of claim 21 , wherein each of the communication openings is in flow communication with at least one of the lower gas outlet passages.

23. The burner of any one of claims 20 to 22, wherein the annular nozzle portion comprises a plurality of said upper gas outlet passages and a plurality of said lower gas outlet passages, wherein the upper gas outlet passages are arranged in an upper row extending about the circumference of the annular nozzle portion, and the lower gas outlet passages are arranged in a lower row extending about the circumference of the annular nozzle portion.

24. The burner of claim 23, wherein the upper gas outlet passages differ in one or more of the following aspects from the lower gas outlet passages:

(a) cross sectional area;

(b) number;

(c) angle relative to longitudinal axis; and

(d) angle relative to radial direction.

25. The burner of any one of claims 1 to 12 and 15 to 24, wherein the annular nozzle portion comprises a plurality of said gas outlet passages, and wherein each of said gas outlet passages is angled relative to the radial direction so as to create a swirling, tangential gas flow.

26. The burner of claim 25, wherein the gas outlet passages are curved.

27. The burner of any one of claims 1 to 12 and 15 to 24, wherein the annular nozzle portion comprises a plurality of said gas outlet passages, and wherein each of said gas outlet passages varies in cross-sectional area along its length.

28. An annular nozzle plate adapted to be retained between a lower edge of a dispersion cone and an inner lance flange of a tubular lance in a burner for a flash smelting furnace, wherein the annular nozzle plate comprises:

(a) an upper surface adapted to seal to an annular sealing surface of the lower edge of the dispersion cone; (b) a lower surface adapted to seal to an annular sealing surface of the inner lance flange;

(c) an outer face;

(d) a plurality of gas outlet passages formed in said annular nozzle plate, each of said gas outlet passages comprising an open channel which is open at one or both of the upper and lower surface of the annular nozzle plate, and wherein the open channel has an inner end and an outer end, the outer end of the open channel being located at the outer face of the annular nozzle plate.

29. The burner of claim 28, wherein each of said open channels extends throughout a height of the annular nozzle plate, from the upper surface to the lower surface.

30. The burner of claim 28, wherein said plurality of gas outlet passages includes a plurality of upper gas outlet passages, each of said upper gas outlet passages comprising an open channel which is formed in the upper surface of the annular nozzle plate and which is open at the upper surface of the annular nozzle plate.

31 . The burner of claim 28 or 30, wherein said plurality of gas outlet passages includes a plurality of lower gas outlet passages, each of said lower gas outlet passages comprising an open channel which is formed in the lower surface of the annular nozzle plate and which is open at the lower surface of the annular nozzle plate.

Description:
FLUID DISPERSION APPARATUS

CROSS-REFERENCE TO RELATED APPLICATION

[0001 ] This application claims priority to and the benefit of United States Provisional Patent Application No. 62/080,272 filed November 15, 2014, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

[0002] The present invention relates to a fluid dispersion apparatus for use with smelting technology and related processes. In one aspect, the present invention relates to a fluid dispersion apparatus for use with a concentrate burner or a flash burner. In another aspect, a fluid dispersion nozzle for use with smelting technology and related processes is disclosed.

BACKGROUND

[0003] Effective flash smelting of ore concentrates requires smelting combustion reactions to be carried out as efficiently as possible. A flash smelting furnace typically includes an elevated reaction shaft at the top of which is positioned a burner where particulate feed material and reaction gas are brought together. In the case of copper smelting, the feed material is typically an ore concentrate containing copper and iron sulphide minerals. The concentrate is usually mixed with a silica flux and combusted with pre-heated air or oxygen-enriched air. Molten droplets are formed in the reaction shaft and fall to the hearth, forming a copper-rich matte and an iron-rich slag phase.

[0004] A conventional burner includes an outer windbox plenum, a water-cooled sleeve, a velocity adjustment cone, and an internal lance. The burner typically contains a cooling block that is attached to the windbox plenum and integrates with the roof of the furnace reaction shaft. [0005] The lower portion of the adjustment cone and the inner edge of the cooling block create an annular channel. Oxygen enriched combustion air enters the windbox and is discharged to the reaction shaft through the annular channel.

[0006] The water-cooled sleeve and the internal lance create an annular channel within the combustion air flow annulus. The feed material is introduced from above and descends through the water-cooled sleeve into the reaction shaft inside the annular channel. Deflection of the feed material into the reaction gas is promoted by a bell-shaped tip at the lower end of a lance situated in the center of the water-cooled sleeve.

[0007] Typical lance tips contain a solid dispersion ring in the lower tip assembly that contains a series of equally spaced radial holes of constant diameter, as referenced in US Patent 4147535. The holes direct compressed air outwardly from the pressurized interior of the lance to disperse the feed material in an umbrella-shaped reaction zone. Lance tips of this type are associated with disadvantages that can adversely affect the burner performance and cause inefficiencies, such as for example, plugging of the air openings due to furnace accretions. Such events may cause uneven feed and air distribution in the reaction shaft. These events occur frequently and are only corrected by removal of the lance from the furnace, followed by in-situ cleaning of the plugged openings, or complete replacement of the lance to allow complete disassembly and cleaning of the plugged dispersion ring holes.

[0008] In-situ cleaning of accretions is typically performed by carefully drilling out each hole. This cleaning operation is both time consuming and risks damaging the holes, which adversely affects the uniformity of the air flow distribution, causing irregularities in feed distribution and combustion efficiency. There is also a risk that furnace accretions may be forced into the dispersion air cavity during drilling, where they may harden inside. The safest means of cleaning, as to preserve the condition of the nozzle openings, is by removing the solid ring, complete with gaskets, and cleaning in the maintenance shop. This requires replacement of the plugged lance in the furnace, followed by a full disassembly of the removed lance. Disassembly must take place away from the burner, in a maintenance shop with sufficient space to facilitate the separation of the inner and outer lance assemblies. In any case, this work requires much time and effort to drill through the accretions in the openings with sufficient care not to cause damage to the air openings. From beginning to completion, the cleaning process typically takes up to two days to complete.

[0009] The first goal of the inventors is to provide an improved dispersion air nozzle design, where the dispersion ring is replaced with interchangeable "stencils", which supply uniformly-distributed air flow, while minimizing equipment down time required for cleaning. This is accomplished by simplifying the in-situ cleaning, as well as eliminating the requirement for disassembly in a maintenance shop to effect a replacement of the stencil.

[0010] The second goal of the inventors is to provide various replaceable stencil designs for the purpose of achieving different, more optimal, feed and process air spatial distributions and injection velocities. This is done to allow the operator to fine tune plant smelting operations, to provide optimal burn efficiency and longer operating duration between stencil replacement or cleaning.

SUMMARY OF THE INVENTION

[001 1 ] The following summary is intended to introduce the reader to the more detailed description that follows, and not to define or limit the claimed subject matter.

[0012] According to one aspect, a dispersion air stencil is provided in two or more nozzle segments which, when assembled, form a ring. The nozzle segments comprise plates with individually milled or otherwise formed nozzles. The stencil is inserted into and held between the dispersion cone and the lower flange of the lance tip. Cleaning of the nozzle openings is performed after removing and replacing the stencil, which requires that the lance be sufficiently untensioned to create a gap between the dispersion cone and lower flange (approximately 20-50 mm) to remove the stencil segments and replace with a new, clean set. This replacement can be completed in the working spaces of the smelter in the vicinity of the burner, and does not require full disassembly of the lance. This has the advantage that the lance need not be moved to a maintenance shop or other remote location because there is no requirement to remove the entire inner lance from the assembly. Stencil replacement can be completed in as little as 2 hours, compared to the 2 day duration for the existing solid ring design.

[0013] Additionally, the dispersion air stencil does not require gaskets, which are typically used in existing lance designs. The stencil is simply compressed between the inner and outer lance assemblies, which provide sufficient compression that a small amount of sealant can be applied to the contact faces to minimize leaks while simplifying maintenance procedures. Furthermore, the stencil contains a registered face on the bottom surface to ensure that it is properly positioned and seated on the inner lance, while a retaining face on the top surface prevents the stencil from ejecting during operation.

[0014] In some examples, the dispersion air stencil openings are machined into a variety of custom shapes to allow different dispersion air flow patterns and velocities.

[0015] In some examples, the dispersion air stencil contains multiple rows of machined nozzles along the axis.

[0016] In some examples, the dispersion air stencil consists of a single, continuous slit opening around the entire circumference.

[0017] In some examples, the dispersion air stencil openings are curved to produce a gas flow into the reaction shaft with a tangential component of velocity. This induces a swirling flow, increasing the turbulence of the solid feed material while in the flash smelter reaction shaft.

[0018] In some examples, the stencil nozzle openings are designed as a converging- diverging nozzle geometry, thereby allowing operation at supersonic air speeds. This provides additional flow momentum into the reaction shaft, allowing the total mass flow rate of compressed air to be substantially reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order that the claimed subject matter may be more fully understood, references will be made to the accompanying drawings, in which: [0020] Figure 1 is a cross-sectional view of the tip of a lance from a burner for a flash smelting furnace, assembled with a typical two-piece stencil, each stencil forming a semicircular segment.

[0021 ] Figure 2 is a close-up of Detail A of Figure 1 .

[0022] Figure 3 is an enlarged cross-sectional perspective view of the lance tip of Figure 1 ;

[0023] Figure 4 is an isometric view of the first embodiment of a dispersion air stencil having individually machined nozzle openings.

[0024] Figure 5 is an isometric view of the first embodiment of the dispersion air stencil, cut in two semicircular segments.

[0025] Figure 6 is a close-up of Detail A of Figure 5.

[0026] Figure 7 is an isometric view demonstrating the stencil replacement process whereby the inner lance assembly is lowered and the two semicircular dispersion air stencil segments are removed from the formed gap between the inner and outer lance, and replaced with a new stencil set.

[0027] Figure 8 is an isometric view of the second embodiment containing multiple rows of nozzle openings along the central axis of the stencil.

[0028] Figure 9 is an isometric view of the second embodiment of a dispersion air stencil, cut in two semicircular segments.

[0029] Figure 10 is a close-up of Detail B of Figure 9.

[0030] Figure 1 1 is an isometric view of the third embodiment consisting of a curved stencil pattern to supply air flow with a tangential velocity component into the reaction shaft.

[0031 ] Figure 12 is an isometric view of the third embodiment of a dispersion air stencil, cut in two semicircular segments. [0032] Figure 13 is a close-up of Detail C of Figure 12.

[0033] Figure 14 is an isometric view of the fourth embodiment, which consists of discrete nozzles with calculated converging-diverging flow areas to supply supersonic air flow.

[0034] Figure 15 is an isometric view of the fourth embodiment of a dispersion air stencil, cut in two semicircular segments.

[0035] Figure 16 is a close-up of Detail D of Figure 15.

[0036] Figure 17 is an isometric view of the fifth embodiment, which consists of a single continuous slit nozzle around the entire circumference, with a calculated converging- deverging flow area to supply supersonic air flow.

[0037] Figure 18 is a cross-section along line 18-18' of Figure 17.

[0038] Figure 19A is an isometric view of the fifth embodiment of a dispersion air stencil, cut in two semicircular segments.

[0039] Figure 19B is a close-up of Detail E of Figure 19A.

[0040] Figure 20 is an isometric top view of a sixth embodiment of a dispersion air stencil containing enclosed nozzle openings.

[0041 ] Figure 21 is an isometric bottom view of the sixth embodiment of a dispersion air stencil, cut in two semicircular segments.

DETAILED DESCRIPTION OF EMBODIMENTS

[0042] In the following description, specific details are set out to provide examples of the claimed subject matter. However, the embodiments described below are not intended to limit the claimed subject matter. It will be apparent to those skilled in the art that many variations of the specific embodiments may be possible within the scope of the claimed subject matter. [0043] Unless otherwise stated, the terms "inner" and "outer" used herein refer to radial positions or directions, relative to a central longitudinal axis. Therefore, the term "inner" and "outer" are used to describe relative proximity to the axis.

[0044] Figures 1 to 3 show a portion of a burner for a flash smelting furnace, specifically the lower end portion of a tubular lance 10 having an outer surface 12 which will be surrounded by a water-cooled sleeve (not shown) and an annular passageway for combustion air flow.

[0045] The tubular lance 10 extends along a longitudinal axis A (Figs. 1 and 3), and comprises an inner lance tube 14 and an outer lance tube 16. The inner and outer lance tubes 14, 16 are concentrically arranged and extend along the longitudinal axis A. A first gas flow passage 18 is enclosed within the lance 10, and is provided in an annular space between the inner and outer lance tubes 14, 16. The inner lance tube 14 has a hollow interior defining a second gas flow passage 20. In addition, the inner lance tube 14 includes an inner lance flange 22 at its lower end, the inner lance flange 22 surrounding a central opening of the second gas flow passage 20 and closing the lower end of the first gas flow passage 18.

[0046] The lower end of lance 10 includes one or more gas outlet passages 24 extending outwardly to the outer surface 12 of lance 10. The lower end of lance 10 also includes an upper annular sealing surface 26 and a lower annular sealing surface 28, wherein the upper and lower annular sealing surfaces 26, 28 face each other. The lower end of lance 10 further includes an annular nozzle portion 30 which is located between the upper and lower annular sealing surfaces 26, 28. The annular nozzle portion 30 is sometimes referred to herein as a "stencil" or a "dispersion air stencil".

[0047] The one or more gas outlet passages 24 are at least partly defined by the annular nozzle portion 30, and extend between the first gas flow passage 18 and the outer surface 12 of the lance 10, so as to permit outflow of the gas and feed material from the first gas flow passage 18.

[0048] In the illustrated embodiment, the lower end portion of the lance 10, also referred to herein as the lance tip, includes a dispersion cone 32 in the form of a truncated cone having an upper edge 34 which is attached to a cylindrical section of the outer lance tube 16, such that the dispersion cone 32 forms a lower extension of the outer lance tube 16 and introduces a radial component to the axial direction of flow at the lower end of the first gas flow passage 18.

[0049] The dispersion cone 32 also has a lower edge 36 having a larger diameter than the upper edge 34, wherein the upper annular sealing surface 26 is provided at the lower edge 36 of the dispersion cone 32.

[0050] It can be seen from the drawings that the lower annular sealing surface 28 is formed on the inner lance flange 22, and is opposed to the upper annular sealing surface 26. Each of the upper and lower annular sealing surfaces 26, 28 are located in a plane which is substantially perpendicular to the longitudinal axis A.

[0051 ] The annular nozzle portion 30 is located between the upper and lower annular sealing surfaces 26, 28 and is also located in a plane which is substantially perpendicular to the longitudinal axis A. At least a portion of the annular nozzle portion 30 is releasably clamped between the upper and lower annular sealing surfaces 26, 28, allowing it to be quickly removed and replaced without the need for relocating the lance 10 to a maintenance shop. In the illustrated embodiment, the compressive load used to secure the annular nozzle portion 30 is supplied by tensioning the inner lance tube 16 and its flange 22 against the dispersion cone 32, which puts the outer lance tube 16 in compression. In alternate embodiments, the upper and lower annular sealing surfaces may be held together by removable mechanical fasteners such as bolts (not shown).

[0052] The annular nozzle portion 30 has at least one upper surface portion 38 which is sealed to the upper annular sealing surface 26 and at least one lower surface portion 40 which is sealed to the lower annular sealing surface 28. The upper and lower surface portions 38, 40 may have a number of different configurations and may comprise continuous or discontinuous surfaces, as will be further discussed below. The seal between the upper and lower surface portions 38, 40 and the respective annular sealing surfaces 26, 28 is substantially gas-tight, and may be provided by any means which permits removal and replacement of the annular nozzle portion 30. For example, the seal may be provided by gaskets and/or sealants (not shown).

[0053] According to some embodiments described herein, and as shown in Figures 5 and 7, the annular nozzle portion 30 may comprise a plurality of arcuate segments 42, permitting removal of the segments by untensioning the inner lance tube 22 (in the direction of vertical arrow 44 in Figure 7) to separate the upper and lower annular sealing surfaces 26, 28, and pulling the segments radially outwardly in the direction of the horizontal arrows 46 in Figure 7. As can be seen, this permits the segments 42 to be removed without completely disassembling lance 10. Thus, a fouled annular nozzle portion 30 or a segment 42 thereof can be easily removed and a new nozzple portion 30 or segment 42 inserted. The inner lance tube 16 can then be quickly retensioned, clamping the annular nozzle portion 30 in place.

[0054] In the embodiment of Figure 7, and in other embodiments described herein, the annular nozzle portion 30 includes two semi-circular segments 42, each describing an arc of about 180 degrees. To permit easy removal of segments, they should each describe an arc of about 180 degrees or less, although the permissible length of the arc is at least partly determined by the diameter of lower end of the inner lance flange 22. Although two segments 42 are shown in the drawings, the annular nozzle portion 30 may comprise three or more segments 42. The lengths of the segments 42 making up the annular nozzle portion 30 are not necessarily equal. Furthermore, although the ends of segments 42 may be in contact with one another, it will be appreciated that it may be desirable to provide gaps between adjacent segments 42, for example to provide additional gas outlet passages 24.

[0055] The following is a description of various configurations of the annular nozzle portion portion 30.

[0056] In the embodiment of Figures 4 to 6, there is illustrated an embodiment of an annular nozzle portion 30 which has a stencil-like appearance, having gas outlet passages 24 defined by a plurality of machined openings extending completely through the nozzle portion 30. Although the annular nozzle portion 30 of Figures 4 to 6 is shown as being comprised of two segments, it will be appreciated that it may comprise a continuous ring, or that it may comprise three or more segments of equal or unequal length.

[0057] The annular nozzle portion 30 of Figures 4 to 6 is in the form of a flat plate having an upper surface 48 adapted to seal to the upper annular sealing surface 26 and a lower surface 50 adapted to seal to the lower annular sealing surface 28. The annular nozzle portion 30 further comprises an outer face 52, and a plurality of gas outlet passages 24. Each of the gas outlet passages 24 comprises an open channel 54 having an inner end 56 and an outer end 58 which is located at the outer face 52 of the annular nozzle portion 30. Each of the open channels 54 is in flow communication with the first gas flow passage 18 at its inner end 56.

[0058] In Figures 4 to 6, each of the open channels 54 extends throughout the height of the annular nozzle portion 30, i.e. from the upper surface 48 to the lower surface 50. Therefore, when the annular nozzle portion 30 of Figures 4 to 6 is sealed between the upper and lower annular sealing surfaces 26, 28, each of the gas outlet passages 24 is defined by the open channel 54 and by both the upper and lower annular sealing surfaces 26, 28, such that each of the gas outlet passages 24 has a top defined by the upper annular sealing surface 26, a bottom defined by the lower annular sealing surface 28, and opposed sides defined by sides of open channel 54.

[0059] As now explained with reference to Figures 1 to 3, the annular nozzle portions 30 described herein may further comprise means for positioning and retaining the nozzle portion 30 in place between the upper and lower annular sealing surfaces 26, 28. In this regard, it can be seen from Figure 2 that the inner lance flange 22 may include a shoulder 60. The annular nozzle portion 30 includes an inner face 62 which abuts against shoulder 60 when the annular nozzle portion 30, or the segments thereof 42, are placed on the inner lance flange 22, bringing them into proper position.

[0060] In addition, as can be seen from Figure 2, the annular nozzle portion 30 includes an inner portion 64 and an outer portion 66, wherein the outer portion 66 is located radially outwardly of the inner portion 64. When installed in lance 10, the outer portion 66 is in sealed engagement with and between the upper and lower annular sealing surfaces 26, 28, while the inner portion 64 is located radially inwardly of the upper annular sealing surface 26.

[0061 ] As best seen in Detail A of Figure 2, the upper surface 48 of the annular nozzle portion 30 is provided with an annular shoulder 68 which separates the inner and outer portions 64, 66, and which extends upwardly along axis A from the outer portion 66 to the inner portion 64 of the annular nozzle portion 30, such that the inner portion 64 is thicker than the outer portion 66. In the present embodiment the shoulder 68 is discontinuous, and is interrupted by the open channels 54. However, it will be appreciated that the shoulder 68 may bridge the channels 54.

[0062] The shoulder 68 has a diameter which is slightly smaller than the inner diameter at the lower edge 36 of the dispersion cone 32, such that the shoulder 68 fits within and engages the lower edge 36 of dispersion cone 32. This helps to properly position the annular nozzle portion 30 and to retain it in place and prevent it from ejecting as a result of the positive pressure within the tip of lance 10. Although the lower surface 50 of the annular nozzle portion 30 is seen as being flat, it will be appreciated that the retaining shoulder 68 may be provided on the lower surface 50 instead of the upper surface 48.

[0063] In order to provide flow communication between the gas outlet passages 24 and the first gas flow passage 18, the open channel 54 extends throughout the entire outer portion 66 of the annular nozzle portion 30, from the outer face 52 to the shoulder 68, and the open channel 54 also extends inwardly of shoulder 68, into the inner portion 64 of the annular nozzle portion 30. Thus, the portion of each open channel 54 located inwardly of shoulder 68 provides an inlet passage into each of the gas outlet passages 24.

[0064] Figures 8 to 10 illustrate an annular nozzle portion 30 according to a second embodiment. The annular nozzle portion 30 of the second embodiment may comprise a continuous ring as in Figure 8 or it may be comprised of two or more segments 42 as shown in Figure 9. It will also be appreciated that annular nozzle portion 30 may comprise three or more segments of equal or unequal length. The embodiment of Figures 8 to 10 includes many of the same elements as the embodiment of Figures 4 to 6, which are identified by like reference numerals. [0065] In this regard, the annular nozzle portion 30 of Figures 8 to 10 comprises an annular plate with a stencil-like appearance, having an upper surface 48 provided with an annular shoulder 68 separating the plate into inner and outer portions 64, 66, a lower surface 50, an outer face 52 and an inner face 62.

[0066] The annular nozzle portion 30 of Figures 8 to 10 includes a plurality of gas outlet passages 24, including a plurality of upper gas outlet passages 24' and a plurality of lower gas outlet passages 24".

[0067] Each of the upper gas outlet passages 24' comprises an open channel 54' which is formed in the upper surface 48 of the annular nozzle portion 30, wherein the open channel 54' is open at the upper surface 48 of the annular nozzle portion 30. Therefore, when the annular nozzle portion 30 is sealed between the upper and lower annular sealing surfaces 26, 28, each of the upper gas outlet passages 24' is defined by the open channel 54' and by the upper annular sealing surface 26, such that each of the upper gas outlet passages 24' has a top defined by the upper annular sealing surface 26, a bottom defined by a bottom surface of the open channel 54', and opposed sides defined by sides of open the channel 54'.

[0068] Each of the lower gas outlet passages 24" comprises an open channel 54" which is formed in the lower surface 50 of the annular nozzle portion 30, wherein the open channel 54" is open at the lower surface 50 of the annular nozzle portion 30. Therefore, when the annular nozzle portion 30 is sealed between the upper and lower annular sealing surfaces 26, 28, each of the lower gas outlet passages 24" is defined by the open channel 54" and by the lower annular sealing surface 28, such that each of the lower gas outlet passages 24" has a top defined by a top surface of the open channel 54", a bottom defined by the lower annular sealing surface 28, and opposed sides defined by sides of open the channel 54".

[0069] The upper and lower gas outlet passages 24' and 24" are separated from one another between their inner and outer ends 56, 58, and it can be seen that the inner ends 56 of the passages 24' and 24" extend inwardly to the inner portion 64 of the annular nozzle portion 30. Located inwardly of the inner ends 56 of passages 24' and 24" are communication openings 70 extending from the upper surface 48 to the lower surface 50, i.e. completely through the annular nozzle portion 30. These communication openings 70 provide flow communication between the first gas flow passage 18 and the upper and lower gas outlet passages 24' and 24".

[0070] It can be seen from Figures 8 to 10 that each of the communication openings 70 may be in flow communication with at least one of the upper gas outlet passages 24' and at least one of the lower gas outlet passages 24". For example, in the illustrated embodiment, each communication opening 70 is in flow communication with one of the upper gas outlet passages 24' and with two of the lower gas outlet passages 24".

[0071 ] Although the embodiment of Figures 8 to 10 includes both upper and lower gas outlet passages 24' and 24", it will be appreciated that other embodiments may include only upper gas outlet passages 24' or lower gas outlet passages 24".

[0072] In the embodiment of Figures 8 to 10, the upper gas outlet passages 24' are arranged in an upper row extending about the circumference of the annular nozzle portion 30, and the lower gas outlet passages 24" are arranged in a lower row extending about the circumference of the annular nozzle portion 30. In various embodiments, some of which are described herein, the upper gas outlet passages 24' may differ in one or more of the following aspects from the lower gas outlet passages 24":

(a) cross sectional area;

(b) number;

(c) angle relative to longitudinal axis; and

(d) angle relative to radial direction.

[0073] In Figures 8 to 10, the upper and lower gas outlet passages 24', 24" differ from one another in number (the upper passages 24' being fewer in number) and in cross-sectional area (the upper passages 24' having greater area). Thus, lower passages 24" may be of smaller area and of lower flow rate, providing a high velocity injection jet capable of disrupting particle re-circulation zones under the upper passages 24'. Although the lower passages 24" may slowly become clogged with time, they will act as sacrificial air nozzles to the upper passages 24' which provide most of the dispersion air flow out from the lance

10 and into the surrounding reaction shaft (not shown). In contrast, US Patent US6238457 implements a multi-row nozzle design, but only to improve the resulting umbrella-like distribution of feed, without any claims to benefit the issue of clogging via sacrificial high- velocity, low-flow rate nozzles.

[0074] Figures 1 1 to 13 illustrate an annular nozzle portion 30 according to a third embodiment. The annular nozzle portion 30 of the third embodiment may comprise a continuous ring as in Figure 1 1 or it may be comprised of two segments 42 as shown in Figure 12. It will also be appreciated that annular nozzle portion 30 may comprise three or more segments of equal or unequal length. The embodiment of Figures 1 1 to 13 includes many of the same elements as the embodiments of Figures 4 to 6 and 8 to 10, and these elements are identified by like reference numerals.

[0075] The embodiment of Figures 1 1 to 13 is similar to that of Figures 4 to 6, wherein each of the open channels 54 extends throughout the height of the annular nozzle portion 30, i.e. from the upper surface 48 to the lower surface 50. The embodiment of Figures 1 1 to 13 also includes an annular shoulder 68 which, instead of being discontinuous as in Figures 4 to 6, is in the form of a continuous ring which bridges the open channels 54 along the upper surface 48 of the annular nozzle portion.

[0076] The embodiment of Figures 1 1 to 13 differs from the embodiment of Figures 4 to 6 in that the gas outlet passages 24 are curved, and they are all angled relative to the radial direction so as to create a swirling, tangential gas flow discharged from the lance 10 into the surrounding reaction shaft. This increased swirl and turbulence intensity within the reaction shaft results in improved combustion. US Patent application US 201 1/0074070 A1 (Yasuda et al.) discloses an injection nozzle of a dispersion air apparatus, which supplies spiral flow through straight holes formed at an angle other than perpendicular to the outside surface of the dispersion ring. However, because Yasuda et al. uses straight holes, it cannot practically supply dispersion air flow at a small angle to the tangent surface of the circular dispersion ring, limiting the maximum swirl intensity that can be achieved. The curved and angled gas outlet passages 24 of the present embodiment, shown in Figures

1 1 to 13, provide additional swirl intensity of the dispersion air. [0077] Figures 14 to 16 illustrate an annular nozzle portion 30 according to a fourth embodiment. The annular nozzle portion 30 of the fourth embodiment may comprise a continuous ring as in Figure 14 or it may be comprised of two segments 42 as shown in Figure 15. It will also be appreciated that annular nozzle portion 30 may comprise three or more segments of equal or unequal length. The embodiment of Figures 14 to 16 includes many of the same elements as the embodiments of Figures 4 to 6 and 8 to 13, and these elements are identified by like reference numerals.

[0078] The embodiment of Figures 14 to 16 is similar to that of Figures 8 to 10 in that it includes a row of upper gas outlet passages 24' and a row of lower gas outlet passages 24". In the embodiment of Figures 14 to 16, the upper and lower gas outlet passages 24' and 24" correspond with one another in terms of number, and cross sectional area. However, in this embodiment the individual gas outlet passages 24' and 24" vary in cross- sectional area along their length. More specifically, the passages 24' and 24" are cut into a profile with a controlled converging-diverging nozzle opening cross-section to produce supersonic exit air velocities. This allows the user to supply additional flow momentum into the reaction shaft at a lower mass flow rate. Dispersion air, typically at ambient oxygen concentration, dilutes the oxygen-enriched air in the ignition zone in the vicinity of the burner. Reducing the level of dilution promotes a higher local oxygen concentration, facilitating prompt ignition of the concentrate.

[0079] Figures 17 to 19B illustrate an annular nozzle portion 30 according to a fifth embodiment. The annular nozzle portion 30 of the fifth embodiment may comprise a continuous ring as in Figure 17 or it may be comprised of two segments 42 as shown in Figures 19A-B. It will also be appreciated that annular nozzle portion 30 may comprise three or more segments of equal or unequal length. The embodiment of Figures 17 to 19B includes many of the same elements as the embodiments of Figures 4 to 6 and 8 to 16, and these elements are identified by like reference numerals.

[0080] In the embodiment of Figures 17 to 19B, the annular nozzle portion 30 comprises an upper portion 72 and a lower portion 74 which may be joined together by relatively thin webs (not shown). Between the upper and lower portions 72, 74 there is provided a single gas outlet passage 24 is in the form of a slit extending substantially continuously about the circumference of the annular nozzle portion 30. Rather than a single continuous slit, it will be appreciated that the annular nozzle portion 30 may include two or more slit-like gas outlet passages 24.

[0081 ] As best seen in the cross-section of Figure 18, the slit-like gas outlet passage 24 has a variable cross-sectional height between the inner face 62 and the outer face 52 of the annular nozzle portion, having a maximum height at the inner face 62 and/or the outer face 52, and a minimum height at a point between the inner and outer faces 62, 52. This configuration of the gas outlet passage 24 cross-section, as shown in Figures 17 to 19B, defines a controlled converging-diverging nozzle opening to produce supersonic exit air velocities. The operational advantage of this embodiment is similar to that shown in Figures 14 to 16, however, the continuous slit-shaped gas outlet passage 24 provides a more uniform injection profile of the dispersion air around the circumference of the lance 10.

[0082] Figures 20 and 21 illustrate an annular nozzle portion 30 according to a sixth embodiment. The annular nozzle portion 30 of the sixth embodiment may comprise a continuous ring as in Figure 20 or it may be comprised of two segments 42 as shown in Figure 21 . It will also be appreciated that annular nozzle portion 30 may comprise three or more segments of equal or unequal length. The embodiment of Figure 8 includes many of the same elements as the embodiments of Figures 4 to 6 and 8 to 19B, and these elements are identified by like reference numerals.

[0083] In the embodiment of Figures 20 to 21 , the annular nozzle portion 30 comprises a continuous upper surface 48 for sealing to the upper annular surface 26, a continuous lower surface 50 for sealing to the lower annular surface 28, an inner face 62 and an outer face 52, and a plurality of gas outlet passages 24. Each of the gas outlet passages 24 are located between the upper and lower surfaces 48, 50 of the annular nozzle portion 30, i.e. the sides of the passages 24 are completely enclosed within the annular nozzle portion 30. The gas outlet passages 24 are spaced apart along the circumference of the annular nozzle portion 30, and each of the passages 24 comprises a cylindrical hole extending inwardly from the outer face 52 of the annular nozzle portion 30. These cylindrical holes are substantially perpendicular to the longitudinal axis, and may be formed by drilling. [0084] It will be appreciated by those skilled in the art that many variations are possible within the scope of the claimed subject matter. The embodiments that have been described above are intended to be illustrative and not defining or limiting. For example, there are many possible geometries that can be adapted into the split stencil design allowing quick replacement.

[0085] While the above subject matter has been described in the context of burners for flash smelting furnaces, it will be appreciated that it may also have application to other burners for pulverous feed materials, such as burners for furnaces that are fueled by pulverous coal.