Abstract:
A metallurgical lance for introducing gas into a volume of molten material in a furnace includes a head having a bore extending therethrough, a mounting assembly at the head in the bore, and a nozzle detachably secured to the mounting assembly by a connection, the nozzle adapted to coact with a tool releasably engagable with the nozzle to insert and withdraw same from the lance head through the bore without dismantling the nozzle.

Description:
FIELD OF INVENTION 
     This invention relates to metallurgical lances for introducing gas into a volume of metal in a vessel. 
     BACKGROUND OF INVENTION 
     Metallurgical lances having a head with at least one gas ejector therein are know. See for example, U.S. Pat. No. 6,709,630 to Cameron et al. which issued Mar. 23, 2004, and which is hereby incorporated herein by reference. The ejector disclosed in Cameron et al. has a nozzle surrounded by a shrouding gas passage. In practice, because of routine wear and tear, it is necessary to replace the nozzle from time to time. This is accomplished by removing the lance from the vessel and then removing the nozzle from the lance which can only be achieved by cutting the lance head from the lance for access to an interior upper end thereof, as can be seen for example from the drawings of the above mentioned patent. This is time consuming, awkward to effect and may compromise the structural integrity of the lance head. 
     SUMMARY OF INVENTION 
     According to the invention, the nozzle is removably mounted in the lance head in such a manner that removal of the nozzle from the head can be effected by use of a tool adapted to engage and remove the nozzle from below the head without dismantling or cutting the lance to effect nozzle replacement. The nozzle may have screw-threaded engagement with the head or may be connected thereto by a bayonet connection. 
     It is therefore an object of this invention to provide a metallurgical lance with a nozzle adapted to be replaced by a tool in a less time consuming and less damaging manner. 
     Accordingly, there is provided herein: 
     A metallurgical lance for introducing gas from a volume of molten material in a vessel, comprising a head having a bore extending through the head from a proximal end to a distal end thereof, a mounting assembly at the head adjacent the proximal end of the bore, and a nozzle located in the bore and detachably secured to the mounting assembly by a connection which enables detachment of the nozzle from the mounting assembly to be effected by a tool engageable with the nozzle by movement of the tool from outside of the head, whereby the nozzle can then be withdrawn from the bore through the distal end of the head. 
     A head for a metallurgical lance, comprising a bore extending through the head from a proximal end to a distal end thereof, a mounting assembly at the head adjacent the proximal end of the bore, and a nozzle located in the bore and detachably secured to the mounting assembly by a connection which enables detachment of the nozzle from the mounting assembly to be effected by a tool engageable with the nozzle by movement of the tool from outside of the head, whereby the nozzle can then be withdrawn from the bore through the distal end of the head. 
     A method of removing a nozzle from a metallurgical lance, wherein the metallurgical lance includes a head having a bore extending through the head from a proximal end to a distal end thereof, a mounting assembly at the head adjacent the proximal end of the bore, and a nozzle located in the bore and detachably secured to the mounting assembly, the method comprising engaging the nozzle with a tool by movement of the tool from outside of the head, operating the tool to effect detachment of the nozzle from the mounting assembly and removing the detached nozzle from the bore through the distal end of the head. 
     A head for a lance, comprising a body portion having a proximal end for connection to the lance, and a distal end disposed away from the proximal end; and a nozzle supported in the body portion and adapted to be removably mounted therewith through the distal end of the body portion. 
     A method of removing a nozzle from a gas ejector of a lance head, comprising releasably engaging the nozzle with a tool at the gas ejector, displacing the position of the nozzle in the gas ejector with the tool, and removing the nozzle form the lance head through the gas ejector with the tool. 
     In a method of disposing a nozzle in a lance, wherein the lance is of the type having a proximal end, and a distal end opposed to the proximal end and at which gas is ejected, the improvement comprising removably mounting the nozzle to the lance from the distal end with a tool operable to displace the nozzle for selective mounting and removal from said lance. 
     A tool for selectively mounting and a removing a nozzle with respect to an ejector discharge end of a lance, comprising a body portion, engaging means disposed at the body portion for releasably engaging a select region of the nozzle for displacement of the nozzle from the ejector discharge end, wherein the body portion is movable to actuate the engaging means into a select position with respect to the nozzle. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, of which: 
         FIG. 1  is a sectional side view of part of a head of a metallurgical lance showing an ejector in which the nozzle is secured in the head by means of a bayonet connection, a nozzle removal tool also being shown; 
         FIG. 2  is a sectional elevation view of a mounting ring forming part of the head shown in  FIG. 1 ; 
         FIG. 3  is a cross-section view through the line A-A in  FIG. 2 ; 
         FIG. 4  is a cross-section view through the line B-B in  FIG. 2 ; 
         FIG. 5  is a view from below of a retaining ring forming part of the head shown in  FIG. 1 ; 
         FIG. 6  is a plan view of the retaining ring shown in  FIG. 5 ; 
         FIG. 7  is an enlarged view of part of  FIG. 1  showing how the removal tool engages the nozzle; 
         FIG. 8  is a sectional side view of part of the head of a metallurgical lance showing an ejector in which the nozzle is secured in the head by screw-threaded engagement, a nozzle removal tool also being shown; 
         FIG. 9  is an enlarged view of part of  FIG. 8  showing how the removable tool engages with the nozzle; 
         FIG. 10  is a sectional elevation view of a mounting ring forming part of the head shown in  FIG. 8 ; and 
         FIG. 11  is a sectional side view of part of the head of a metallurgical lance showing an ejector having a nozzle which is removable from below and which has a metering passage for the shroud gas at the lower end of the nozzle. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Referring to the Figures,  FIG. 1  shows part of a head  10  of a metallurgical lance, a gas supply chamber  12  with annular passages for cooling fluid, therebeing an inner inlet passage  14  and an outer outlet passage  16  connected by a connecting chamber or passage  18 . The head  10  includes an ejector shown generally at  20 , which includes a nozzle  22  removably mounted in a bore  24  at a tip  26  of the head  10 . A distal or bottom end of the nozzle  22  is set back or recessed from a lower or distal end of the bore  24 . The nozzle  22  includes a passageway  23  extending therethrough. 
     Referring also to the  FIGS. 2-4 , the nozzle  22  is held in place by a bayonet connection at its upper or proximal end. A mounting assembly including a mounting bracket or ring  30  is secured to the head  10  at the upper or proximal end of the bore  24  by mechanical fasteners such as screws  32 , and the nozzle  22  has a plurality of equi-angularly spaced outwardly projecting lugs  34  at its upper end which releasably engage complementary shoulders  33  integral with the mounting ring  30  in such a manner as to form a bayonet connection. 
     A retaining ring  35  prevents excessive inward displacement of the nozzle  22  into the head  10 . The retaining ring  35  is adjustably held in position on the mounting ring  30  by fasteners such as set screws  37 . As shown in  FIG. 5 , a surface of the retaining ring  35  is provided with a plurality of equally spaced biasing members such as spring plates  39 , which is shown in  FIG. 1 . Each of the spring plates  39  bear against the lugs  34  of the nozzle  22 . The spring plates  39  help to retain the nozzle  22  in its demountably coupled position. As shown in  FIGS. 5 and 6 , the retaining ring  35  is formed with a plurality of equally spaced slot-like apertures  41  that permit gas to flow from the chamber  12  through an annular passage  38  which exists between the bore  24  and the nozzle  22 . 
     The nozzle  22  also has external lugs  36  disposed at an exterior of the nozzle approximately midway along said nozzle&#39;s length. The lugs  36  contact the wall of the head at the bore  24  as shown in  FIG. 1 . 
     Referring to  FIG. 7 , a tool  40  is provided of a construction to both remove and mount the nozzle  22  with respect to the bore  24 . The tool  40  includes a main body  42  with a shaft  44  extending from one end and a tapered portion  46  extending from the other end of the body  42 . An annular ledge  48  extends around the end of the main body  42  adjacent the forward portion  46 , and the ledge  48  has a series of pins  50  extending from the ledge  48  toward the forward portion  46 . A lower edge of the nozzle  22  has recesses  52  constructed and arranged to receive corresponding ones of the pins  50 . 
     When it is desired to remove the nozzle  22 , the tool  40  is engaged with the lower or distal end portion of the nozzle  22  as shown in  FIG. 7 , with the tapered portion  46  inserted into the nozzle  22  for the pins  50  to be in registration with and engage respective ones of the recesses  52 . The tool  40  is then rotated about its longitudinal axis as shown generally at “X” by means of a rotational force applied to the shaft  44  so as to uncouple the lugs  34  on the nozzle  22  from the shoulders  33  on the mounting ring  30 . It will then be possible to withdraw the nozzle  22  from the lower or distal end of the bore  24 . A new nozzle can then be disposed in the bore  24  to be removably mountable with the head  10  in a reverse manner. 
     The operation of the lance shown in  FIGS. 1-7  is similar to the operation of the lances disclosed in U.S. Pat. No. 6,709,360, said patent incorporated herein by reference. Gas, typically oxygen, is supplied under pressure to the chamber or passage  12 . Most of the gas passes directly through the passageway  23  to the nozzle  22 . Some of the gas, however, flows through the annular passage  38  between the wall at the bore  24  and the nozzle  22 . The discharge end of annular passage  38  has an appropriate convergence and/or divergence section  95  so as to effect a perfect expansion of the annular gas stream. The section  95  of the annular passage  38  is preferably created by selected machined profiles for the outer surfaces of the nozzle  22 , which are calculated in a manner similar to that employed for the design of a convergent-divergent profile at the interior of the nozzle  22 . 
     During operation in a hot metallurgical environment, the gas flowing from the passage  38  helps to protect the distal end of the nozzle  22  from erosion or other damage attributable to the hot environment. The retracted or recessed position of the distal end of the nozzle  22  relative to the distal end of the bore  24  helps to protect the nozzle  22  from damage by hot gases. The gas ejected from the distal end of the annular passage  38  effectively merges with gas ejected from the passageway  23  through the distal end of the nozzle  22 , and the merged gas stream typically passes at high velocity into a volume of molten metal to be treated. 
     The lance shown in  FIGS. 1-7  is operatively associated with a manipulator (not shown) of a kind known in the art. The manipulator is able to lower and raise the lance head  10 . When it is desired to replace the nozzle  22  with a new nozzle, the manipulator is operated to raise the lance and hence the head  10 . The nozzle  22  may then be removed with the tool  40  being inserted from below as shown in  FIG. 1 . A new nozzle  22  may then be inserted. If desired, however, the lance may be removed from the manipulator and the nozzle  22  removed and a new nozzle fitted at a location remote from the metallurgical furnace served by the lance. Such may be done with the lance held in any convenient orientation to enable the tool to be inserted and actuated for removal or insertion of the nozzle  22  as the operation may require. 
       FIGS. 8 and 9  show another embodiment for mounting a nozzle  62  in the lance head  10 . For simplicity, elements in  FIGS. 8 and 9  which correspond to elements in  FIGS. 1-7  rely on the same reference numerals, unless indicated otherwise. In this embodiment, an outer surface of the nozzle  62  is threaded at its upper end for releasable engagement with a complementary thread formed on an inner surface of a mounting ring or bracket  64  secured to the head  10  by mechanical fasteners such as screws  66 . The mounting ring  64  as shown in  FIG. 10  is formed with a plurality of equally-spaced passages  68  therethrough to permit gas to flow from the chamber  12  through the annular passage  38  which exists between the bore  24  and the nozzle  62 . 
     Referring to  FIG. 9 , a tool  70  has a cylindrical open-ended body  72  with a lower end wall  74  from which a handle  76  extends. An end of the cylindrical body  72  remote from the end wall  74  has axially extending slots  78  corresponding in number and circumferential location with the lugs  36  on the nozzle  62 . The body  72  has an interior of sufficient size and shape to receive at least a portion of the nozzle  62  therein. 
     When it is desired to remove the nozzle  62 , the tool  70  is engaged with the nozzle  62  by sliding the cylindrical body  72  into the annular passage  38 , such that the body  72  is between the nozzle  62  and the wall at the bore  24  in the tip  26  of the lance head  10  until the lugs  36  engage the slots  78 . The tool  70  is then rotated to threadably disengage the nozzle  62  from the mounting ring  64  and thus enable the nozzle  62  to be withdrawn from the lower end of the bore  24 . Thereafter, a new nozzle can be fitted in a reverse manner. 
     The tool shown in  FIGS. 1-7  may be used with a nozzle having a screw thread connection to the mounting bracket, while the tool shown in  FIG. 9  may be used with a nozzle having a bayonet-type connection to the mounting ring  34 . 
       FIG. 11  shows a further embodiment in which a metering passage is provided. In this embodiment, a nozzle  82  is screw threaded into engagement with a mounting bracket or ring  84  secured to the inner upper end of the tip  26  by mechanical fasteners such as screws  86 , and a spacing collar  88  is located between the mounting bracket  84  and an annular shoulder  90  at an exterior of the nozzle  82 . The exterior of the nozzle  82  is screw threaded at the appropriate location to engage with internal screw threads on the mounting bracket  84 . The spacing collar  88  can be attached to the nozzle  82  by mechanical fasteners such as screw threads (not shown) or by set screws (not shown). The spacing collar  88  is formed with one or a plurality of metering orifices  92  therethrough. The metering orifices  92  meter the flow of gas from the chamber  12  via axial passages  94  to the annular passage  38 . The flow of gas through the annular passage  38  is determined by the number and size of the metering orifices. 
     A shroud of low Mach velocity can be produced by restricting the gas flow through a series of the metering orifices  92  in the spacing collar  88 . The gas is expanded in the annular passage  38  and exits through the converging and/or diverging channel  95 . The ability to control the shroud gas facilitates a simple method to change the quantity of, or thrust contributed by, the shroud gas as dictated by the changes to process requirements. 
     The nozzle  82  can be removed by an arrangement such as described with reference to  FIGS. 1 and 8 . 
     It will be understood that the embodiment(s) described herein is/are merely exemplary and that a person skilled in the art may make many variations and modifications without departing form the spirit and scope of the invention. All such modifications are intended to included within the scope of the invention as defined in the appended claims. It should be understood that the embodiments described above are not only in the alternative, but can be combined.