Improved descaling nozzle assembly

Abstract

To provide an improved spray nozzle assembly for directing thin, straight-line, high-pressure liquid spray onto moving steel slabs for penetrating and removing scale buildup in steel processing operations.SOLUTION: A spray nozzle assembly includes a liquid inlet defined by an upstream strainer and a downstream high-impact attachment tube for accelerating a liquid flow. A one-piece multi-stage liquid straightening vane segment is disposed within a central liquid flow passage of the nozzle assembly for more effectively reducing liquid turbulence of the high-pressure liquid flow with resultant improved control in the tightness of a thin flat spray panner. The one-piece vane segment further is adapted for efficient assembly and replacement in the spray nozzle assembly without the need for handling and precise alignment of a plurality of individual vane elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001]

[0001] The present invention relates to a spray nozzle assembly, and more particularly to a descaling spray nozzle assembly that is particularly effective in directing a wide, thin line of high-pressure liquid discharge to penetrate and remove scale from steel in steelmaking operations. [Background technology]

[0002]

[0002] Descaling spray nozzle assemblies are widely used in steel processing to direct a wide, thin line of high-pressure spray onto the surface of a steel slab to penetrate and remove the buildup of iron oxide scale on the surface prior to rolling and subsequent processing of the steel. In such spray systems, it is desirable that the high-pressure liquid discharge be as thin or narrow as possible to achieve maximum impact pressure and maximum penetration of the scale. It is also desirable that the distribution of the liquid discharge be uniform across the width of the spray pattern.

[0003]

[0003] Such descaling spray nozzle assemblies typically include a tubular body, sometimes referred to as a high-impact attachment tube, having a liquid flow passage that tapers inward in the downstream direction to accelerate the liquid flow; a strainer attached to the upstream end of the tubular body to filter particulate matter and scale from recycled steel mill water typically used in descaling processes; and a tungsten carbide insert tip attached to the downstream end of the tubular body and having an elongated liquid discharge orifice for forming and directing a flat spray discharge pattern. The high-pressure liquid, typically at a pressure of 2000 to 4000 psi, directed through the strainer typically turns at right angles into the high-impact attachment tube, creating extensive turbulence that can adversely affect the uniformity and impact force of the discharge spray.

[0004] To reduce turbulence and straighten the liquid flow through the high-impact attachment tube before passing through the spray tip, it is known to provide a vane having a plurality of radial vane elements downstream of the strainer, which effectively defines a plurality of circumferentially spaced laminar flow passages. It is also known to use a plurality of vanes assembled so as to be axially spaced apart in stages and circumferentially offset from one another to further improve liquid straightening.

[0005] Even with such vanes, significant turbulence can remain in the high-pressure flow, some of which is generated by the vanes themselves, reducing the energy of the liquid and the impact force of the discharge spray. Wear on the tubes by the high-pressure liquid can also reduce efficient liquid distribution. Furthermore, the use of multiple stages of vanes requires precise assembly and alignment of the vanes in the proper position relative to one another, which can hinder efficient assembly and replacement. Summary of the Invention

[0006] SUMMARY OF THE INVENTION It is an object of the present invention to provide a descaling spray nozzle assembly that more effectively directs and channels liquid through the spray nozzle assembly with reduced turbulence and energy loss.

[0007]

[0007] Another object is to provide a descaling spray nozzle assembly as described above having multiple stages of liquid straightening vanes that more effectively reduce turbulence and energy losses in the liquid flow that can change the impact force of the discharged liquid spray.

[0008] A further object is to provide a descaling spray nozzle assembly of the type described in which the liquid straightening vanes are less susceptible to wear from high pressure liquid directed through the spray nozzle assembly over time.

[0009] A further object is to provide a descaling spray nozzle assembly of the foregoing type having a plurality of liquid straightening vanes that is adapted for easier and more efficient assembly. A related object is to provide a descaling spray nozzle assembly of the type that eliminates the need to handle and precisely assemble a plurality of individual vanes.

[0010] A further object is to provide a descaling spray nozzle assembly of the type described which is relatively simple in design and lends itself to economical manufacture.

[0011] Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic end elevation view of an exemplary descaling spray system having a spray nozzle assembly according to the present invention; [Figure 2] FIG. 2 is a partial enlarged cross-sectional view of one of the descaling spray nozzle assemblies of an exemplary spray system. [Figure 3] FIG. 3 is an end view of an enlarged downstream end of the exemplary spray nozzle assembly taken through the plane of line 3-3 of FIG. 2. [Figure 4] FIG. 2 is an enlarged longitudinal cross-sectional view of a tungsten carbide insert spray tip of an exemplary spray nozzle assembly. [Figure 5] 5 is an enlarged longitudinal cross-sectional view of the spray nozzle assembly shown in FIG. 2 taken along the plane of line 5-5. [Figure 6] FIG. 2 is an enlarged side view of an integral vane segment of an exemplary spray nozzle assembly. [Figure 7]Fig. 7 is a longitudinal cross-sectional view of the integral vane segment shown in Fig. 6. Fig. 7A is an enlarged detail view of the upstream end of one of the vane sections of the exemplary integral vane segment shown in Fig. 7. Fig. 7B is an enlarged detail view of the end of a vane element of the exemplary integral vane segment. [Figure 8] FIG. 2 is an end view of the upstream end of an exemplary integral vane segment. [Figure 9] FIG. 2 is an end view of the downstream end of an exemplary integral vane segment. [Figure 10] FIG. 7 is a cross-sectional view taken along line 10-10 in FIG. 6. [Figure 11] FIG. 11 is a cross-sectional view taken along the plane of line 11-11 in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0013]

[0025] While the invention is susceptible to various modifications and alternative constructions, specific exemplary embodiments thereof are shown in the drawings and are described in detail below. It should be understood, however, that the intention is not to limit the invention to the particular forms disclosed, but rather, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention.

[0014]

[0026] Referring now more particularly to the drawings, an exemplary descaling spray system 10 having a plurality of spray nozzle assemblies 11 according to the present invention is shown for directing high-pressure liquid sprays onto opposite sides of a moving steel slab 12 in a steelmaking operation. The spray system 10 in this case includes an upper liquid supply header 14a and a lower liquid supply header 14b that are supplied with plant water that is typically recycled in the steelmaking facility. The spray nozzle assemblies 11 are mounted in laterally spaced relation along their respective headers 14a, 14b so as to produce a plurality of flat, thin, linear spray patterns 13 that penetrate and remove scale across the entire width of the steel slab 12. The spray nozzle assemblies 11 in this case are supported in a depending relationship from the upper liquid supply header 14a to direct a liquid spray onto the upper side of the moving slab 12, and the spray nozzle assemblies 11 are supported to extend upwardly relative to the lower liquid supply header 14b to direct a spray pattern across the underside of the slab 12. Each spray nozzle assembly 11 is supported by its respective header 14a, 14b, with an upstream end within the header for receiving the feed liquid therefrom and a downstream end positioned outside the header to face the moving slab 12. Each of the spray nozzle assemblies 11 is of similar construction, so only one will be described in detail herein.

[0015]

[0027] Each exemplary spray nozzle assembly 11 has an elongated nozzle body 13 with an upstream section in the form of an elongated, generally cup-shaped liquid strainer 18 through which feedwater from headers 14a, 14b enters the spray nozzle assembly 11, and a downstream section in the form of an elongated, high-impact attachment tube 15 supported within walls 16 of the headers 14a, 14b. A tungsten carbide insert spray tip 19 is attached to the downstream end of the high-impact attachment tube 15, with an elongated discharge orifice 20 formed therein for discharging and directing a flat spray pattern, and a spray tip retainer 21 secures the spray tip 19 in the attached position. The spray tip retainer 21 is threaded onto the downstream end of the high-impact attachment tube 15, with an inwardly directed annular lip 22 holding the spray tip 19 in adjacent relation to the downstream end of the high-impact attachment tube 15.

[0016]

[0028] The spray nozzle assembly 11 of this example is supported within the header 14 by a cylindrical adapter 23 that is suitably secured within the radial opening of the header 14. The adapter 23 has an externally threaded lower end against which an outwardly extending radial flange 21 a of the spray tip retainer 21 is retained by an internally threaded retaining ring 24 that is secured to the cylindrical adapter 23.

[0017]

[0029] To accelerate the liquid as it passes through the spray nozzle assembly, the high impact attachment tube 15 is formed with a liquid passage 25 that tapers inwardly in the downstream direction. In this case, a tungsten carbide insert spray tip 19 secured to the downstream end of the high impact attachment tube 15 is formed with an inlet passage section 32 that communicates between the high impact attachment tube passage 25 and the discharge orifice 20 through a radial inlet passage section 34 (FIG. 4). The elongated discharge orifice 20 in this example is defined by a cylindrical groove or cylindrical cut 35 that extends transversely across the end of the spray tip 19 in intersecting relationship with the inlet passage section 34.

[0018]

[0030] To filter small particulate matter that may be present in the recycled steel mill water channeled through the headers 14a, 14b from the flow entering the spray nozzle assembly 11, the strainer 18 is formed with a plurality of elongated slits 38 circumferentially around the strainer that partially communicate through the strainer's cylindrical side wall 39 to the upstream end 39a of the cylindrical side wall. The feed water enters the strainer 18 primarily radially through the elongated slits 38 and must make a 90° change of direction, causing significant turbulence in the liquid as it is directed into the inwardly tapering flow passage 25 of the high impact attachment tube 15 before being directed from the spray tip 19. As indicated above, turbulence in the high-pressure liquid stream directed at the spray tip 19 can adversely affect liquid discharge by increasing the transverse thickness, particularly of thin linear spray patterns, which can reduce the impact force and penetration of the liquid, thereby altering the liquid distribution, particularly at the ends of wide spray patterns, resulting in uneven liquid penetration and uneven scale removal.

[0019]

[0031] According to an important aspect of this embodiment, the spray nozzle assembly includes an integral multi-stage liquid straightening vane segment 40 disposed within a central liquid passage 41 of the nozzle body 13, defined by the upstream strainer 18 and the high-impact attachment tube 15, which more effectively reduces turbulence of the liquid prior to direction to and through the spray tip 19, resulting in improved control of the tightness of the thin, flat spray pattern and the uniformity of liquid distribution throughout the spray pattern. The exemplary integral multi-stage liquid straightening vane section 40 includes a plurality of integrally formed, circumferentially offset liquid straightening vane sections 45 a, 45 b, which facilitate easier and more efficient assembly and replacement of the spray nozzle assembly without the tedious handling of multiple individual vane components. The exemplary integral vane segment 40 in this case comprises a central longitudinally extending hub 44 having a first vane section or upstream vane section 46a including a plurality of flat vane elements 45a extending radially outward from the central hub 44 in a radial plane passing through the longitudinal axis of the central liquid flow passage 41, and a second vane section or downstream vane section 45b located downstream of the first vane section 45a including a plurality of similar flat vane elements 45b circumferentially offset relative to the vane elements 45a of the first vane section 45a and extending radially outward from the common central longitudinal hub 44.

[0020]

[0032] The exemplary unitary vane segment 40 has an outer cylindrical collar 48 integrally formed around and surrounding the vane elements 46a, 46b of both the upstream vane section 46a and the downstream vane section 46b. The outer collar 48, central hub 44, and vane elements 46a of the upstream vane section 45a define a plurality of circumferentially spaced, enclosed laminar flow passages 50a (FIG. 11), while the outer collar 48, central hub 44, and vane elements 46b of the downstream vane section 45b define a second annular array of enclosed laminar flow passages 50b circumferentially offset from the laminar flow passages 50b of the first vane section 45a (FIG. 10). In the illustrated embodiment, vane sections 45a, 45b each have five radial vane elements 46a, 46b extending between a common central hub 44 and an outer collar 48 to define five circumferentially spaced laminar flow passages 50a, 50b, with the vane elements 46b of the downstream vane section 45b positioned longitudinally intermediate the vane elements 46a of the upstream vane section 45a. Preferably, vane sections 45a, 45b each have a common number of vane elements 46a, 46b between four and six.

[0021]

[0033] To facilitate gradual rectification of the high-pressure liquid 46a passing through the vane segments 40 before entering the high-impact attachment pipe 15, the vane elements 46b of the downstream vane section 46b are axially spaced and circumferentially offset from the radial vane elements 45a of the upstream vane section 46a. In the illustrated embodiment, when viewed longitudinally, the vane elements 46b of the downstream vane section 45b are aligned midway with respect to the laminar flow passage 50a of the upstream vane section 45a. The vane elements 46a, 46b in this case each have an equal longitudinal length L and are separated by an axial gap D (FIGS. 5 and 7) that defines the length of the transition passage 52 between the vane sections 45a, 45b. In a preferred embodiment, the gap D is less than half the axial length of the individual lengths of the vane elements 46a, 46b.

[0022]

[0034] According to a further aspect of this embodiment, the vane segments 40 have a streamlined design to reduce turbulence and energy loss in the high-pressure liquid flow directed therethrough. More specifically, the vane segments 40 are designed to minimize blunt surfaces that tend to impede the high-pressure liquid flow and impart additional turbulence to the high-pressure liquid flow. To this end, the central hub 44 is formed with a longitudinal central passage 54 that defines an additional laminar flow path through the vane segments 40. The central hub 44 is formed with a frustoconical outer liquid guide surface 56 that tapers radially outward in the downstream direction (FIGS. 7 and 7B), and further includes a protrusion 55 extending upstream of the upstream valve 45a. The frustoconical liquid guide surface 56 intersects with the central liquid passage 54 of the hub 44 to define a pointed annular inlet end 58 for both the central liquid passage 54 and the frustoconical liquid guide surface 56. It has been found that such upstream protrusions 55 facilitate directing liquid into the central liquid passage 54 and frusto-conical liquid guide surface 56, and into the laminar flow passage 50a of the upstream valve 45a, in a more controlled manner, without blunt surfaces that would add additional turbulence to the high-pressure liquid flow. To further facilitate directing liquid into the laminar flow passage 50a, the vane elements 46a, 46b of the upstream and downstream valves 45a, 45b have pointed upstream ends 58s, as shown in FIG. 7A. The central hub 44 in this case again further includes a downstream protrusion 59 having an outer frusto-conical surface tapering inward in the downstream direction to guide liquid from the laminar flow passage 50b of the downstream valve 45b into the high-pressure attachment tube 25.

[0023]

[0035] In further practicing this embodiment, the spray nozzle assembly 11 is adapted for efficient assembly with vane segments 40 comprising separate sections of the nozzle body 13 of the spray nozzle assembly. To that end, the vane segments 40 are mounted so as to be interposed between the upstream section of the nozzle body, in this case the liquid strainer 18, and the downstream section of the nozzle body, in this case the high-impact attachment tube 15. In the illustrated embodiment, the downstream end of the strainer 18 is fixedly crimped onto the upstream end of the collar 48 of the vane segment, and the downstream end of the collar 48 of the vane segment is crimped onto the upstream end of the high-impact attachment tube 15. The collar 48 of the vane segment 40 in this case has a diameter that matches the diameters of the high-impact attachment tube 15 and the strainer 18. It will be appreciated that such a spray nozzle assembly 11 can be easily assembled without handling or precisely aligning a large number of liquid baffle vanes.

[0024]

[0036] From the foregoing, it can be seen that a descaling spray nozzle assembly is provided to reduce turbulence and energy loss to more effectively and efficiently straighten the liquid flow through the spray nozzle assembly. The one-piece multi-stage liquid straightening vane segments further minimize turbulence and energy loss in the liquid flow, which can change the impact force of the discharge liquid spray, and are less susceptible to wear from the high-pressure liquid directed through the spray nozzle assembly over time. Furthermore, the spray nozzle assembly is adapted for easier and more efficient assembly and replacement, without the need to handle and precisely align multiple individual vane elements. [Explanation of symbols]

[0025] 10...Descaling spray system, 11...Spray nozzle assembly, 12...Steel slab, 13...Nozzle body, 14...Header, 14a...Upper liquid supply header, 14b...Lower liquid supply header, 15...High impact attachment tube, 16...Wall, 18...Liquid strainer, 19...Insert spray tip, 20...Discharge orifice, 21...Spray tip retainer, 21a...Radial flange, 22...Annular lip, 23...Cylindrical adapter, 24...Retaining ring, 25...High impact attachment tube passage, 32...Inlet passage section, 34...Radial inlet passage section, 35...Notch , 38...slit, 39...cylindrical sidewall, 39a...upstream end, 40...integral multi-stage liquid straightening vane segment, 41...central liquid passage, 44...central longitudinal hub, 45a...upstream vane section, first vane section, 45b...downstream vane section, second vane section, 46a...upstream vane section, 46b...downstream vane section, 48...outer cylindrical collar, 50a...laminar flow passage, 50b...laminar flow passage, 52...transition passage, 54...longitudinal central passage, 55...upstream protrusion, 56...frustoconical liquid guide surface, 58...pointed upstream end, 59...downstream protrusion

Claims

1. A steel processing system for removing iron oxide scale from a steel slab, comprising: upper and lower headers (14a, 14b) disposed above and below steel slabs directed through the steel processing system, each header connected to a supply of high-pressure liquid; each of the upper and lower headers (14a, 14b) having a plurality of descaling liquid spray nozzle assemblies (11) mounted in widthwise spaced relation to each other for directing a liquid spray linearly across the upper and lower widths of a steel slab being directed through the steel processing system; Each of the plurality of descaling liquid spray nozzle assemblies (11) includes an elongated nozzle body (13) having a liquid flow passage (25) and a spray tip (19); the nozzle body liquid flow passage (25) has a liquid inlet communicating with high pressure liquid directed through each header to which the spray nozzle assembly is attached, the nozzle body liquid flow passage having a section extending downstream along a longitudinal axis of the liquid flow passage with an inwardly tapered diameter for accelerating liquid through the inwardly tapered portion; the spray tip at the downstream end of the nozzle body (13) has an elongated discharge orifice oriented transverse to the direction of steel slabs being directed through the steel processing system for discharging and directing a linear liquid spray; an integral multi-stage vane segment (40) disposed within the liquid flow passage of the nozzle body upstream of the spray tip; the integral multi-stage vane segment comprising an upstream vane section (45a) and a downstream vane section (45b) downstream of the upstream vane section; the upstream vane section and the downstream vane section each have a substantially equal number of radial vane elements (46a, 46b) defining a plurality of longitudinally extending, circumferentially spaced apart laminar flow passages in communication with the liquid inlet for longitudinally directing liquid in a direction parallel to a longitudinal axis of the liquid passage; the vane elements of the upstream vane section and the downstream vane section are circumferentially offset from one another such that each of the upstream vane sections is oriented substantially centrally with respect to the radial pair of vane elements of the downstream vane section when viewed axially of the downstream vane section; 1. A steel processing system comprising: a supply of high-pressure liquid pressurized to a pressure in the range of 2000 to 4000 psi; and wherein the vane elements reduce turbulence and rectify the flow of liquid passing through the upstream vane section and the downstream vane section, such that a discharge line of the liquid spray from the discharge orifice of the spray tip has a uniform liquid distribution throughout the line, thereby penetrating and removing iron oxide scale that accumulates on a steel slab across the width of the steel slab during steel processing.

2. the integral multi-stage vane segment (40) includes a central hub (44) extending longitudinally along a central axis of the integral multi-stage vane segment, the vane elements of the upstream vane section and the downstream vane section each extending radially outward from the central hub; The steel processing system of claim 1 .

3. the integral multi-stage vane segment (40) includes an integrally formed outer cylindrical collar (48) disposed surrounding the vane elements of both the upstream vane section and the downstream vane section, the outer cylindrical collar (48) surrounding the plurality of laminar flow passages extending axially through the upstream vane section and the downstream vane section. The steel processing system of claim 2 .

4. the central hub (44) of the integral multi-stage vane segment has an upstream protrusion (55) extending upstream of the upstream vane section, the upstream protrusion (55) having a frusto-conical outer guide surface (56) tapering outward in a downstream direction to direct liquid into the circumferentially spaced laminar flow passages of the upstream vane section; The steel processing system of claim 2 .

5. the central hub having an axial flow passage extending therethrough to define a further laminar flow passage, and the frusto-conical outer guide surface of the upstream projection intersecting the axial flow passage of the central hub to form a pointed annular upstream end of the upstream projection for dividing a flow of liquid for directing through the further laminar flow passage and onto the frusto-conical outer guide surface of the upstream projection; 5. The steel processing system of claim 4.

6. the vane elements of the upstream vane section and the downstream vane section have pointed upstream ends for dividing liquid flow into the corresponding annular laminar flow passages of the upstream vane section and the downstream vane section, respectively; 5. The steel processing system of claim 4.

7. the central hub having downstream frustoconical projections tapering inwardly in a downstream direction for directing liquid from the circumferentially spaced laminar flow passages of the downstream vane sections; 5. The steel processing system of claim 4.

8. the upstream vane section and the downstream vane section each have a substantially equal number of vane elements; The steel processing system of claim 2 .

9. the upstream vane section and the downstream vane section are axially spaced apart from one another to define a transition flowpath between the upstream vane section and the downstream vane section. The steel processing system of claim 2 .

10. the liquid inlet is defined by a strainer having a plurality of longitudinal openings formed therein and circumferentially disposed about the strainer and parallel to a longitudinal axis of the elongated nozzle body; The steel processing system of claim 1 .

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