US2749112A - Blast furnaces provided with tuyeres having baffles - Google Patents

Description

2 Sheets-Sheet l F. J. ZIPPLER June 5, 1956 BLAST FURNAcEs PROVIDED WITH TUYERES HAVING BAFFLES Filed Aug. 24. 1955 IN VEN TOR. FRANCIS J. ZIPPLER.

ATTORNEYS.

BLAST FURNACES PROVIDED WITH TUYERES HAVING BAFFLES Filed Aug. 24, 1953 F. J. ZIPPLER June 5, 1956 2 Sheets-Sheet 2 INVENTOR. FRANCIS J. ZIPPLER.

ATTORNEYS.

United States Patent 2,749,112 BLAST FURNACES PRovlDn WITH TUYERES HAVING BAFFLES Francis I. Zippler,littsburgh, Pauassignorof one-half to Henry G. Bolster, Pittsburgh, Pa.

Application .s1-'igual '24, 1955s, seal 315,994 4 Claims. (Cl. 2466-30) This invention` is yfor an improvement in vmetallurgical furnaces of the type in which air is introduced into the combustion and 'smelting ch'amln'er through aplur'a'lity of tuyeres such, for example, as blast furnaces and cupola furnaces, and is for an improvement wherein a more uniform discharge of air from all of the tuyeres iny be produced. l y

ln the operation of a blast furnace, the blast of hot air brought to ya large pipe that l"encircles the bosh of the furnace, vand wliieh is commonly referred to as a bustle pipe. At regulartintervals around the furnace there are tuyeres at alevel below the bustle pipe, and air is led from the bustle pipe to the 'tuye'res through pipes that lead downwardly from the bustle pipe, and which bend horizontally to direct the air into the tuyere. Usually the tuyere is supported in a pipe that passes through the bosh of the furnace commonly referred to las a tuyere cooler, and the pipe leading out 'of the bustle pipe is joined to the tuyere cooler.

One diyliculty in this arrangement is that it is practically impossible to robtain la 'uniform discharge of vair into the furnace from each of the vvtly'eres. Invariably one'tuyere will pull more air than another, and rs'tn'nel'of the tuyeres will be starved while others take more tha'n is required. An uneven discharge of air causes 'uneven cornbu'stion in the furnace, a mass of material often building up above the tuyeres on one' side of the furnace, interfering 'With proper reduction of ore, and the downward passage ofthe furnace charge. Various gattempts have been 'made 'to control the flow of air 'through the use of dampers in the pipes leading to 'the several tuy'eres, but this has not proved to be satisfactoryfand Tconstant 'adjustment `of the da'mpe'rs is required. Also itha's been proposed to use ori'ce plates having `'dillere'nt'sied openings therethrough in an 'attempt to secure more uniform distribution of fair, b'ut this has not proved to be'sati'sfac't'ory. Such da'r'npers and Iorifice plates restrict or lchange the cross-sectional area of the air passage. v

According to the present invention, a Vuniform Vdistribution of air is yattained by the 'provision of baffles in the lconduit between the bustle pipe andthe tuyere s'oarra'nged as to create varied conditions of turbulence in the stream of air flowing to the tuyere, which turbulence impedes to a greater or lesser extent V"the'moven'ient of the air without, however, throttling by reduction of size of the free air passage the volume of flow. As a result of this, it is possible to obtain a 'nice control of the distribution of the air and secure uniformity `of distribution not heretofore attainable.

The object of my invention therefore is to provide in a blast furnace or like furnace an arrangement vwherein more nearly uniform distribution of air from all of the tuyeres can be yobtained to thus increase the capacity of the lfurnace and reduce destructive conditions.

'My invention maybe more fully understood by referenee to the'raecon'ipanying drawings, in which:

Fig. l'epresents'i'nor'e or less s'cher'n'atically ra vertical Patent-'ed June 5, l1956 ICC 2 section through the lower part of a conventional 'blast furnace showing the bustle pipe and some of the tuye'res with the conventional air duct at one side and a baffle unit as herein described at the other; y Fig. 2 isa transverse section 'through one form of baffling unit embodying my invention; v

Fig. 3 is a similar view through another complementary unit;

Fig. l is still a similar view of another unit in the series;

Fig. 5 is a similar view of still a fourth unit for the series; j

Fig; 6 is a view similar to Fig. 2 showing 'a somewhat modified arrangement; and i Fi'g.y 7 is a flat plane projection of a portion of the bustle pipeV showing one manner of using the'baling units of my invention.

Referring first to Fig. 1, 2 designates the shell of the blast furnace, and 3 i's the bosh having an annular series of tuyeres t at regular'intervals around the base. Corn- 'moiily there are Vtwelve V`1 '"Oilftee1"l /S'leh tuyeres. Each tu'ye'r'e is mounted in a tubular water-cooled body 5 which is known a's the tuy'ere cooler, and the vtuyere 'cooler is joined to a horizontal pipe 6. Each pippe 6 ha's'an elbow 7 at its outer e'nd that is joined in aconve'ntional furnace t'o a vertical pipe section Sas s'een "at the left of Fig. l, and this sectionin turn is connected 'to an outlet pipe 9 leading from the circular manifold 'or 'bustle pipe ylll that Vsurrounds the lower Vpart of the blast furnace, and to vwhich the hot air blast is delivered from a source not shown. Thehotblast of air from the bustle'pipe is th'us 'discharged into the several tuyeres, and an effort is made to supply sufficient air so 'as to meet the requirements of 'all Vof the tuyer'es.

According to the present invention, the baffling means above referred to is interposed somewhere between the bustle pipe and the tuyere. Conveniently the flanged `section of the pipe 8 may be removed andthe battling unit B 'to be described is put in its place as shown at the right of Fig. l.

As shown in Figj2, the b'aflling unit comprises -a tubular :body 11 having a ange 12 at its upper lend by means of which it can be bolted'to thepipe 9. At the lower part of the tubular 'section 11 the b'ody has 'outwardly flared walls 13 forming an internal chamber C of substantially greater diameter 'than the tubular section 1l. At `14 the body is flared to the maximum diameter, and there is a short length where its diameter remains constant or substantially constant, and 'then the walls 15 are tapered reversely to the walls 12, terminating at -an opening 16 that has thefsar'ne dia-meter as'the tubular section 1l. The body 'may have va flange 17 around the portion l5 `so vas to be bolted to the flange at the top of'the elbow 17.

It will be understood that while l 'describe the unit as being a replacement for the tubular section it may vbe locatedelsewhere between the bustle pipe and the tuyere, and may even constitute the tuyere cooler.

Inside the chamber 13 is a conical baille i8, the tip Vof which is at fabout the center of the opening 16, while the base of the baille is in a `horizontal plane which passes through the part 14 of mavimum diameter. The cone is preferably icast integrally in the body, and there is an annular passageway 19 outside the cone and inside the inwardly converging walls 15, the area of which is roughly equal to the area of the passageway in the tubular part'll. As shown by the arrows, the base of the cone is directed toward the stream of air flowing toward the tuyere so as to form an impedance to the free flow of air. Except as 'the air is impeded in this way and by the resulting turbulence, the unit does not throttle the flow of air, and the passage for the lair is v'not restricted. A `normal..amount terminating at a discharge opening 26, While 27 is the flange around the lower end of the body.

Also positioned inside the body is a baille 28 which corresponds to the baille 18 in shape and size, but the baflle 28 is eccentric to the longitudinal axis through the unit instead of being concentric as is the baffle in the form shown in Fig. 2. As a result of this eccentricity, the air passage 29 between the outer surface of the cone and the inwardly converging walls 25 is elliptical, the point of minimum width being at 29', and the point of maximum width being at 29". The baille in this case will also be effective as is the baille in Fig. 2 to create a condition of turbulence, but the total amount of impedance offered by it will be less than in Fig. 2, because some of the air will approach more nearly a straight line flow. The total area of the passageway around the cones in each case is the same, so that one unit does not restrict the flow of air more than the other, execpt as to the baflling effect being different.

In the unit shown in Fig. 4, the overall design is again the same as in Fig. 2, there being a tubular upper part 31 corresponding to the part 11, and it is surrounded by a flange 32. It merges into an outwardly flaring wall 33, and 34 is the portion of maximum diameter, and below this there is an inwardly converging wall 35 terminating in an opening 36, and 37 is an annular flange to enable the unit to be bolted into place. In this form also there is a chamber C and there is an internal baille 38 also in the form of a cone, but the baffle is positioned more eccentrically than the baffle 28 in Fig. 3 so that the point of the cone at one position intersects the wall 3S, and part of the cone is common to the wall 35. This of course pro vides a crescent-shaped passage 39, the area of which, however, would be substantially equal to or not less than the area of the passage through the upper part 31 of the unit. Here again the baille will impede the flow of air, but less drastically than the baffling in Figs. 2 or 3, but the area of the passageway through which the air flows will not be different than in the other forms.

In the fourth form of unit shown in Fig. 5, there is the upper tubular part 41 corresponding to the part 11 of 2, and which has a flange 42 around its top. The lower end of part 41 merges into an outwardly flared wall 43, and 44 is the portion of maximum diameter. Below the part 44 there is an inwardly sloped flared wall 45, terminating in an opening 46, and 47 is the flange around the bottom of the unit. In this case the baille is in the form of an annulus providing a cylindrical wall 48, and an annular internal curved shoulder 48. It is substantially as though the cone of Fig. 2 had been expanded radially and converted into an annulus of triangular section. The passageway through the center, terminating at 49, is of substantially the same area as the passageways 19, 29 and 39 of Figs. 2, 3 and 4 respectively, but is entirely concentric with the passageway through the part 41. The air flowing through the unit shown in Fig. will be obstructed less than the air flowing through any of the three forms previously described, but nevertheless due to the expansion that occurs in the chamber C there will be a turbulence which, while not directly obstructing the flow of the air, will produce an impedance.

In using these units, a study is made of the blast furnace to determine the inequality of the air distribution. This can be determined first by measuring the flow through any tuyere in accordance with the prevailing practice. Secondly the behavior of the furnace, the variations in the lives of the tuyeres, and other factors also give the operator some idea of the air distribution pattern of the furnace. This pattern being determined, the section of down pipe 8 is then removed from each location around the furnace where some change is to be made, and at certain locations the unit shown in Fig. 3 will be employed. At others the unit shown in Fig. 4 will be used, and still others, the unit shown in Fig. 5 may be used. At some stations the pipe 8 may remain without any replacement, In other furnaces, the form shown in Fig. 2 may not be used, but the form shown in Figs. 3, 4 and 5 may be used, or there may be various combinations depending on the particular characteristics of the furnace. There are normally from twelve to fourteen tuyeres on an average blast furnace, and the disposition of the units will not necessarily follow the same sequence in any two furnaces, and in all furnaces the entire series of baffles may not be required.

The purpose of the units is not comparable to that of a damper in that they do not valve or throttle the flow of air, the area of the passageway through the unit being generally about the same, or at least as great, as the area of the passageway in any other part of the conduit between the bustle pipe and the tuyere nozzle. The purpose is to impede rather than to throttle the flow of air, and the extent of the impedance is varied in the flow of air to different tuyeres. The impedance to flow is thus reflected back to the bustle pipe, so that the bustle pipe serves to function somewhat as a wind box instead of merely being a manifold.

When the units are placed in the down pipe between the bustle pipe and the elbow 7, they do not interfere with any of the usual operations of changing the tuyeres, and they can be put into the furnace and changed about without taking the furnace out of operation. After being installed in the desired arrangement around the furnace, they cannot be adjusted or tampered with except when they are removed.

The unit shown in Figs. 2 to 5 inclusive in each case includes a chamber of expanded diameter and a baffling means effectively arranged in the outlet of the chamber. The baling means is here shown as a particular form of cone having a concaved base that is presented toward the incoming gas, but the baille can be of a variety of forms, and the shape of the chamber can be modified in various ways. For illustration, one such modification is shown in Fig. 6 where there is a unit having a cylindrical upper part 51 with a flange 52 at the top. There is a laterally extending wall 53 around the base of the part 51 joined to a vertical wall 54, and at the bottom of the wall 54 there is another laterally turned wall 55 that joins to the outlet connection 56 having a flange S7 thereon. The chamber C in this case, instead of being of a reversely flared form, is cylindrical. The baille may comprise a plate which is either concentric or eccentric. In Fig. 6 the baflle designated 58 is in the form of a plate centrally positioned in the chamber, and the area of the space between the periphery of the baffle and the wall 54 is at least as great as the area of the passageway within the part 51. The plate may or may not be provided with a hole 59 at its center, and this hole may be merely a peep-hole, or it may be a hole of substantial area.

It will thus be seen that the form of the unit and the shape of the baffle may vary within wide limits, but no matter how formed, the function of the baffle is to offer more or less impedance to the direct line flow of air and create a condition of turbulence without throttling from a 'free area standpoint the capacity of the passageways for the air.

For purposes of illustration l have in Fig. 7 shown in flat projection a portion of a bustle pipe with a succession of baffling units of different effectiveness arranged therein to illustrate one manner in which the several units are employed. In this showing the tuyere that takes the most air has the unit shown in Fig. 2, while on each side of it are units shown in Fig. 3, etc. As previously indicated, while l prefer to put the units in the down pipe leading from the bustle pipe, the unit may be placed in the pipe 6 or even built into the cooler in which the tuyere is mounted.

Various other changes and modifications will be apparent to those skilled in the art and within the scope of the appended claims. In the appended claims I use the term blast furnace as including a structure having a series of tuyeres supplied from a manifold or bustle pipe, including for example a cupola furnace.

I claim:

1. An air blast system for blast furnaces comprising a plurality of tuyeres having discharge ends terminating in the blast furnace, a bustle pipe, a separate conduit connecting each tuyere with the bustle pipe whereby air may llow separately from the bustle pipe through each tuyere into the furnace, means disposed between the bustle pipe and the end of each tuyere providing an expansion chamber of larger cross-sectional area than the conduit or the discharge end of the tuyere, and a baille in the expansion chamber across part of the area of the chamber that obstructs the free flow of air through the chamber, the area of the bame being sulliciently less than the full area of the chamber across which it partially extends as to provide an air passage through the chamber past the baille at least as great as the area of the conduit whereby the baille obstructs but does not restrict the free ow of air from the bustle pipe to the discharge end of the tuyere, the baflle in some chambers being concentric with respect to the longitudinal axis of the chamber in the direction of the air travel and in other chambers being eccentric to produce dilerent turbulent effects in the air ow to different tuyeres.

2. An air blast system for blast furnaces comprising a plurality of tuyeres opening into the blast furnace, a bustle pipe for supplying air to all of the tuyeres, a separate conduit connecting each of the tuyeres to a bustle pipe and providing a separate air passage to each tuyere, and a unit in some of the conduits between the bustle pipe and the tuyere having a chamber therein of substantally larger cross-sectional area than the crosssectional area of the conduit or the cross-sectional area of the tuyere, said chamber permitting the air to expand radially, and a baille in each chamber extending crosswise of the direction of air travel from one end of the chamber to the other, there being a free air passage through the chamber past the baille substantially as great in area as the transverse area of the conduit whereby the air passage is not restricted by such unit, but turbulence is created by the baille.

3. An air blast system as defined in claim 2 wherein the baille in some chambers is on center with respect to the longitudinal axis of the unit, and in some chambers is eccentric to create dilerent elects of turbulence in the air flow to diierent tuyeres.

4. A unit for connection into the conduit which carries air from the bustle pipe of a blast furnace to the tuyere comprising a body having flanged ends for connection into the conduit, said body having a portion intermediate said ends of radially increased diameter providing a radi ally enlarged expansion chamber in the body between its two ends, and a baffle in said chamber crosswise of its longitudinal axis, the area of the baille being less than the full transverse area of the chamber whereby there is a free air passage through the chamber, the area of the free air passage past the baille being substantially equal to the cross-sectional area of the conduit into which said tlanged ends of the body are designed to be connected.

References Cited in the le of this patent UNITED STATES PATENTS 1,092,623 Zippler Apr. 7, 1914 1,145,648 Zippler July 6, 1915 1,726,298 Hayes Aug. 27, 1929 2,295,604 Reece Sept. 15, 1942 2,471,776 Reece May 31, 1949 FOREIGN PATENTS 273,714 Germany May 7, 1914

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