Tuyere Stock For Furnaces

Abstract

A feed conduit having utility in the transmission of heated fluids is disclosed. The apparatus of the present invention is characterized by a curved section, which communicates at its discharge end with a nozzle which supplies the heated fluid to the desired environment, and by a straight portion, which couples the source of heated fluid to the curved portion; the straight portion being formed from at least three members with an intermediate member being connected to the end members by means of articulated joints comprised of cardan compensators. The bellows units of the cardan compensators are protected from the fluid being transmitted by cascade joints packed with a compressible refractory material.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the transmission of heated fluids. More specifically, the present invention is directed to an expansible conduit which may be employed as a tuyere feed line for the delivery of preheated gas to a furnace. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art

While not limited thereto in its utility, the present invention is particularly well suited for use as an improved tuyere feed line for shaft furnaces. In shaft furnaces, particularly in blast furnaces, preheated air is injected into the furnace through nozzles or tuyeres. The preheated air is delivered to the vicinity of the injection nozzles via a common supply conduit, normally of circular cross-section, which is mounted exterior of and around the furnace. A plurality of injection nozzles are located on the periphery of the furnace and are connected to the supply conduit by means of feed lines or conduits known in the art as tuyere stocks.

Prior art tuyere stocks typically comprise a number of tubular elements which are internally lined with a refractory material. The high temperature of the air or gas blown into the furnace causes deformation, and particularly thermally induced expansion, of the various components of the tuyere stock. In order to minimize or prevent leakage of gas being supplied to the furnace and to increase the life of the apparatus, a number of procedures have previously been adopted in an attempt to compensate for the expansion and contraction of tuyere stock components. One of these prior art compensation procedures consists of the inclusion of swivel joints or articulations between the tubular elements comprising the tuyere stock. Swivel joints have, however, been a continuous source of trouble, particularly at the temperatures presently employed for the air injected into blast furnaces of modern design. In an attempt to avoid the problems inherent in swivel joints, one or all of the joints between the tubular tuyere stock elements have been replaced by rigid connections and a compressible element has been incorporated into the tuyere stock to compensate for deformations caused by thermal expansion. These compressible elements have generally consisted of a compensator member comprising a corrugated metal bellows. It has previously been believed that such metal bellows, if intended to take up both the horizontal and vertical expansions of the tuyere stock, must comprise a relatively large number of undulations or bellows units. Also in accordance with the prior art, the interior of the compensator bellows is protected by a comparatively long internal guiding tube which is of lesser diameter than the bellows and which is lined with refractory material. Since it is impossible to accurately predict the deformations of the tuyere stock components, and particularly of the compensator, the risk of deformation of the internal guide tube resulting from the extremely high temperatures of the air or gas insufflated is quite high, causes continuous trouble during operation and reduces the service life of the tuyere stock.

SUMMARY OF THE INVENTION

The present invention overcomes the above-discussed and other disadvantages and deficiencies of the prior art by providing a novel device which may be employed as a feed line for the injection of preheated air into a furnace. In accordance with the present invention, a tuyere stock is comprised of a first, straight conduit connected at a first end via a cardan compensator to the common supply pipe for the preheated fluid which is to be injected into a furnace. The other end of this straight conduit is connected, also via a joint constructed as a cardan compensator, to the actual injection nozzle. The cardan compensators compensate for the differential expansions caused by heating of the components of the apparatus and also counteract any unforeseen deviations in the assembly.

In a preferred embodiment, the straight portion of the feed line of the present invention comprises three tubular members connected in series. The facing ends of the two outwardly disposed tubular members are respectively connected to the intermediate member by means of cardan joint compensators. The opposite end of a first, outboard tubular member is rigidly secured to the supply conduit for the preheated fluid while the opposite end of the other outer member is affixed to a curved portion of the tuyere stock which, in turn, is connected to the injection nozzle. The two outer tubular members which comprise the straight or rectilinear portion of the feed line of the present invention also function as guide and protective tubes for the undulations of the pair of cardan compensators.

A particularly novel feature of the present invention resides in the employment of cascade type joints as part of the articulated feed tube defined by the cardan compensators. In addition, the present invention contemplates the use of highly refractory and compressible fibers as insulating material in these cascaded joints thereby substantially eliminating circulation of heated fluid in the interior of the joint structure. This additional protection for the interior of the joint structure substantially reduces the thermal stresses to which the undulaions of the bellows units of the cardan compensators are subjected.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may be better understood and its numerous objects and advantages and will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the two figures and in which:

FIG. 1 is a cross-sectional, side elevation view of a preferred embodiment of the present invention; and

FIG. 2 is a cross-sectional view, taken along line A--A of FIG. 1, of the preferred embodiment of the invention.

Description of the Preferred Embodiments:

With reference now to FIG. 1, a circular conduit 1 serves as a supply of preheated air or gas which is to be injected into a furnace via an injection nozzle or tuyere 2. The injection nozzle 2 passes through an outer wall 30 of the furnace in the manner well known in the art and is surrounded by a cooling jacket 9. Supply conduit 1 is connected to nozzle 2 via a feed line or tuyere stock indicated generally at 5.

Feed line 5 is comprised of welded steel plates formed into a conduit having an internal lining of refractory material. The feed line 5 is comprised of a nose or downstream section 3, bend or elbow section 4, and a straight section 29 which provides communication between the elbow 4 and supply conduit 1. The straight section 29 of feed line 5 is, in turn, comprised of serially connected cylindrical tubular members 17, 19 and 22.

The upstream end of nose section 3 of feed line 5 is affixed to the curved section 4 by means of flanges 10 which are preferably bolted together. The opposite end of nose section 3 communicates with nozzle 2 and is spring loaded against a spherical joint 6 which comprises part of nozzle 2. Nose section 3 also includes an injection nozzle 53 whereby a combustible fuel may be delivered to nozzle 2 simultaneously with the preheated fluid from supply conduit 1.

The bent section 4 of the feed line, which defines an obtuse angle, is affixed at its upstream end to the downstream end of cylindrical tube 22 of the straight portion 29 of the feed line. The connection of section 4 to tube 22 is by means of a substantially horizontal collar assembly 11--11' and cotter bolts 12. The use of the horizontal collar and bolts 12 facilitates removal and replacement of the subassembly comprising sections 3 and 4. Section 4 is welded to collar member 11 and is provided with an inspection port 13. Port 13 is situated upstream of the curved portion of section 4 to improve the operation and durability of the refractory lining.

The straight or rectilinear portion 29 of feed line 5 comprises, as noted above, three serially connected tubular members which are joined to one another via a pair of cardan compensators indicated generally at 14 and 15. Compensators 14 and 15 serve to compensate for horizontal and vertical expansions which take place during operation of the apparatus and also to correct for any constructional variations which may have occurred during manufacture of the components and assembly of the apparatus. It is also to be noted that the subdivision of straight portion 29 of the feed line into three members facilitates the application of the refractory lining internally thereof.

The downstream end of rectilinear feed line section 29, consisting of cylindrical member 22, is welded to the horizontal collar 11'. A steel extension sleeve 39 which defines the other end of tube 22 is attached, preferably by welding, to the first end of the flexible or bellows unit of cardan compensator 14. Sleeve 39 extends over and thus shields the major part of the bellows unit of compensator 14. The other end of the bellows unit is attached to an intermediate collar 23 which also forms part of compensator 14.

The intermediate tubular member 19 is rectilinear feed line section 29 is detectably fastened to intermediate collar 23 via a flange 18, which is affixed to member 19, and bolts. The mechanical connection between tubular members 22 and 19 is completed by means of two pair of articulation arms indicated at 21 and 25. Considering the axis of the feed line, pairs of arms 21 and 25 are positioned in mutually perpendicular planes. First ends of arms 21 are rigidly connected, for example by welding, to flange 18 and are rotatably connected at their opposite ends to a cardan ring 24 by connectors 41 and 41'. Arms 25 are also rigidly connected to flange 18 and extend to connectors 42 and 42' on ring 24. A steel socket 38 is welded to flange 18 to form a slight downward extension of tubular member 19. In some applications it has been found desirable to fabricate socket 38 and the sleeve 39 of tubular section 22 from refractory steel.

The internal linings of refractory material provided in the three cylindrical tubular members 17, 19 and 22 are respectively indicated at 36, 37 and 40. It is to be noted that in the region of cardan compensator 14, the refractory linings applied to socket 38 and sleeve 39 define a cascade joint 43. The interior of cascade joint 43 is filled with a highly refractory and compressible fiber which prevents the heated fluid traversing feed line 5 from circulating or remaining within the joint structure. The cascade joint construction thus substantially eliminates the circulation of heated fluid in the space between the exterior of the joint and the interior of the bellows unit of the compensator and thus constitutes an effective means of providing thermal protection for the undulations of the bellows unit as well as for those other parts of the articulation joint system which are not provided with a refractory lining. It will be obvious to those skilled in the art that, in order not to impair the insulating properties of the apparatus, the gap in the cascade joint which is filled with the refractory fiber must not exceed certain maximum limits while also being of sufficient size to insure that thermally induced angular movements of the joint are not impeded.

It is also to be noted that, in order to insure that the refractory lining of the cascade joint 43 is not destroyed by mechanical strains during assembly and operation, angular displacements of the articulated joint must be maintained within certain limits. With reference to FIG. 2, it may be seen that arresting devices 44, 44' and 45, 45' are welded to the exterior of the cardan ring 24 to limit the angular displacements of the articulation arms 21 and 25 respectively. As noted above, the articulation arms are rotatably attached to the arresting devices by connectors 41 and 42.

The second or upstream cardan compensator system 15, which is installed between the upper end of the intermediate tubular member 19 and the upper tubular member 17, is similar to compensator 14. Tubular member 19 is welded to first end of the bellows unit of compensator 15 and is provided with a steel extension sleeve 35. Sleeve 35 shields the major portion of the bellows unit from the interior of the feed line. The refractory lining on sleeve 35 cooperates with a complimentary refractory lining, which extends in the downstream direction from the end of tubular member 17, to define a second cascade joint 46. As in the case of joint 43, cascade joint 46 is packed with a compressible, refractory material.

The first or upper end of tubular member 17 is secured, by means of a flange 20 and bolts, to an outlet socket 31 of the supply conduit 1. The opposite end of tubular member 17 is provided with a conical steel collar 34 which is welded to both tubular member 17 and to the upstream end of the bellows unit of compensator 15. The refractory lining which aids in defining cascade joint 46 is applied to collar 34 and both collar 34 and sleeve 35 may be fabricated of refractory steel.

The coupling between tubular member 17 and 19 of the rectilinear portion 29 of the tuyere feed line 5 is achieved in the same manner as the coupling between tubular members 19 and 22. To this end, a cardan ring 32 having pairs of articulation arms 47, 47' and 48, 48' is provided. First ends of arm 47 and 47' are affixed to tubular member 17 and the second ends of these arms are rotatably coupled to ring 32 by means of connectors 49 and 49'. First ends of arms 48 and 48' are affixed to the exterior of tubular member 19 and the other ends of these arms are rotatably attached to ring 32 by means of connectors 50 and 50'. Arresting 51, 51' and 52, 52' are welded to the exterior of cardan ring 32 in order to limit the angular displacements of the articulation system.

An important feature of the present invention resides in the fact that the two compensators 14 and 15 are provided adjacent the ends of a relatively long, straight portion of the feed tube. Accordingly, the deformations to be taken up by each of compensators 14 and 15 will remain within comparatively moderate limits and the compensators may thus be constructed with a limited number of undulations. In the embodiment shown compensators 14 and 15 each employ only two undulations. The use of a pair of compensators in accordance with the present invention offers the further advantage in that the feed tube is absolutely hermetic in operation.

A hanger member 27 is depicted as extending between outer wall 30 of the furnace and the intermediate tubular member 19. Hanger 27 serves to provide additional support for the rectilinear portion 29 of the feed tube 5 during periods when sections 3 and 4 of the feed tube are disconnected from the remainder of the apparatus.

Tuyere feed lines fabricated in accordance with the present invention have the advantage of very simple construction and can be formed of welded plates thereby greatly facilitating the application of the refractory lining. As a result of the fact that the present invention may also be assembled and adjusted in a much easier manner than prior art devices of like character, tuyere feed lines in accordance with the present invention are less expensive than those previously available.

To summarize, the feed lines in accordance with the present invention offer the essential advantage that compensation for all thermally induced deformations is achieved with a pair of cardan compensators; each compensator having a limited number of bellows units and being arranged adjacent oppositely disposed ends of a straight section of the feed line. The present invention also minimizes the component parts of the feed line which are subjected to heated fluid flowing through the device. The latter improvement is accomplished through the use of insulated cascade joints which shield from the fluid. As a result of the above-discussed novel features, the service life of the feed lines of the present invention is considerably increased when compared to the prior art and the efficiency of the apparatus is similarly improved since all joints between components of the invention are hermetic.

While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the present invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

Claims

What is claimed is:

1. Apparatus for transmitting heated fluid comprising:

a first tubular member;

a second tubular member; and

first expansible joint means coupling a first end of said first member to a first end of said second member, said joint means including:

means external of said tubular members and attached to each of said members for rendering said joint means hermetic;

a sleeve extension on the first end of one of said members;

a socket extension on the first end of said other of said members;

a refractory material lining the internal surface of said sleeve extension, said lining defining a tube section having an inner diameter which varies in step-wise fashion; and

a refractory material lining on said socket extension, said socket extension lining cooperating with said sleeve extension lining to define a cascade joint.

2. The apparatus of claim 1 further comprising:

a compressible refractory material positioned between the linings on said extensions.

3. The apparatus of claim 2 wherein said external means comprises:

a bellows unit, said bellows unit being attached to said members adjacent the first ends thereof;

ring means positioned radially outward from said bellows unit, said ring means being supported from one of said members; and

articulation arms extending between said ring means and the other of said members.

4. Apparatus for transmitting heated fluid comprising:

a first tubular member;

a second tubular member;

a third tubular member;

first expansible joint means coupling a first end of said first member to a first end of said second member, said first joint means including:

means external of said first and second tubular members and attached to each of said members for rendering said first joint means hermetic;

a sleeve extension on the first end of one of said first and second members;

a socket extension on the first end of said other of said first and second members;

a refractory material lining the internal surface of said sleeve extension, said lining defining a tube section having an inner diameter which varies in step-wise fashion; and

a refractory material lining on said socket extension, said socket extension lining cooperating with said sleeve extension lining to define a cascade joint; and second expansible joint means coupling a second end of said third member to the second end of said second member.

5. The apparatus of claim 4 wherein said second joint means comprises:

means external of said second and third tubular members and attached to each of said members for rendering said second joint means hermetic;

a sleeve extension on the second end of one of said second and third members;

a socket extension on the second end of said other of said second and third members;

a refractory material lining the internal surface of said sleeve extension, said lining defining a tube section having an inner diameter which varies in step-wise fashion; and

a refractory material lining on said socket extension, said socket extension lining cooperating with said sleeve extension lining to define a cascade joint.

6. The apparatus of claim 5 wherein each of said external means comprises:

a bellows unit attached to the adjacent members in the vicinity of the confronting ends thereof;

ring means positioned radially outward from said bellows unit, said ring means being supported from one of said members; and

articulation arms extending between said ring means and the other of said members.

7. The apparatus of claim 6 further comprising:

a compressible refractory material positioned between the linings on said extensions.