US3281135A

US3281135A - Blast furnace apparatus

Info

Publication number: US3281135A
Application number: US333354A
Authority: US
Inventors: Frank J Boron
Original assignee: American Brake Shoe Co
Current assignee: American Brake Shoe Co
Priority date: 1963-12-26
Filing date: 1963-12-26
Publication date: 1966-10-25
Anticipated expiration: 1983-10-25

Description

1966 F. J. BORON 3,281,135

BLAST FURNACE APPARATUS Filed Dec. 26, 1963 2 Sheets-Sheet l Inventor Frank J. Boron Oct. 25, 1966 F. J. BORON BLAST FURNACE APPARATUS 2 Sheets-Sheet 2 Filed Dec. 26, 1963 Inventor Frank J. Boron 5 wwmjfwwm pm jHirorrzegaS United States Patent 3,281,135 BLAST FURNACE APPARATUS Frank J. Boron, Elyria, Ohio, assignor to American Brake Shoe Company, New York, N.Y., a corporation of Delaware Filed Dec. 26, 1963, Ser. No. 333,354 Claims. (Cl. 26630) This invention relates to blast furnace apparatus and in particular to the construction of a face plate that is to be associated with one end of a blast furnace blow- This application is a continuation-in-part application of co-pending application, Serial No. 249,492 filed January 4, 1963, now abandoned.

Air for sustaining combustion is usually introduced into a blast furnace through a blowpipe, and specifically the blowpipe has a fore end that seats in a tuyere that is located in the portion of the furnace immediately below the bosch, in the area of the molten slag.

The end of the blowpipe opposite the tuyere is joined to a so-called gooseneck which is an elbow-type pipe section, in turn connected to the circular bustle pipe that surrounds the bosch part of the furnace. The hot blast for sustaining combustion in the blast furnace is introduced forcefully into the bustle pipe to be directed through the blowpipe to the tuyere, and from thence into the area of the molten slag within the combustion area of the furnace.

The temperatures involved are quite severe, often resulting in premature failure of the blowpipe and adjacent parts. In particular, it is observed that there is early failure of the face plate which affords a seat for the end of the blowpipe opposite the end associated with the tuyere. Such failure is characterized by the development of cracks in the face place, apparently due to the large temperature differential that prevails between the inside and outside of the face plate. With a gas temperature inside the pipe of about 2000 F., the temperature differential on the outside of the face plate ranges from 1000 to 1500 F. Resultantly, the efficiency of the furnace is decreased due to the escape of gas through the face plate cracks. Moreover, imperfect seating or warpage sometimes occurs between the face plate and the adjacent end of the blowpipe. This can be traced to plastic flow at the inside diameter of the face plate since the outside diameter of the face plate has a substantially lower temperature, restricting the total expansion possible across the face plate.

The primary object of the present invention is to avoid the difiiculties noted above thereby more closely approximating theoretical efficiency in that possibility of cracks and plastic flow is lessened, and specifically it is an object of the present invention to accomplish this by loosely disposing a separate insert in the portion of the face plate where the adjacent end of the blowpipe seats. The insert introduces a boundary effect within the face plate which results in a much less severe temperature differential across the face plate as will be explained in more detail hereinafter.

Both the blowpipe and face plate have interior linings of insulation. However, the respective insulation linings do not always meet in a perfect fit, thus leaving a crack for the high temperature gas to heat the face plate and end of the blowpipe. The insulation at the juncture tends to deteriorate and fall out, thereby enlarging the area of the face plate and end portion of the blowpipe subjected to the high temperature gas. It is at this juncture, under a further object of the invention, that inserts protect or buffer the face plate or end portion of the blowpipe from the high temperature gas. Since the face plate is subjected to much lower temperatures than the temperature of the gas, the temperature differential through the face plate is much less than the temperature differential heretofore present in one-piece plates. Because the face plate metal is stronger at low temperatures and at lower temperature differentials, the face plate is less subject to cracking.

According to a more specific object of the invention, the insert material is formed of a more expensive and more highly heat resistant material than the material of the face plate so that the insert can more readily resist the tendency to crack and warp at the high temperature of the gas. Even if the insert does crack while being subjected to the high temperature at the interior of the face plate, the face plate still prevents the release of the high temperature gas. According to a more specific object of the invention the insert is loosely dis posed in a complemental seat therefor so that it can expand when heated and thereby be relieved of compressive forces. The leading end portion of the blowpipe is also subjected to the extreme temperature differential. The leading end of the blowpipe is contoured to fit within a complementary contoured seat in the face plate and this leading edge is subject to developing cracks whereby the hot gas can escape. Thus, a further object of the invention is to achieve a seal between the blowpipe and face plate less subject to cracking by affording an insert at the leading edge of the blowpipe to bear the brunt of the high temperature gas and reduce the temperature differential at the contoured end of the blowpipe. According to a further object of the invention, the insert for the blowpipe is of a more highly heat resistent material than the material of the blowpipe. According to a still further further object of the invention, the blowpipe insert is made to be loosely fitted within a seat, therefor in the blowpipe so that the insert may expand and not be subject to the compressive forces and plastic flow heretofore experienced with one-piece blowpipe end portions.

In accordance with another object of the invention both the face plate and blowpipe have separate inserts which receive the brunt of the high temperature gas and which serve to reduce the temperature differential across the face plate and the leading end portion of the blowpipe and thereby render the face plate and blowpipe less subject to cracking "at their sealed juncture.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawing which, by way of illustration, shows preferred embodiments of the present invention and the principles thereof and what is now considered to be the bestmode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIG. 1 is a sectional view of a blowpipe assembly contemplated under the present invention;

FIG. 2 is an exploded sectional view showing the face plate and the insert disassociated, and with typical temperature gradients indicated;

FIG. 3 is a plan view of the face plate and its insert on the line 3-3 of FIG. 1;

FIG. 4 is a view illustrating the over-all furnace connections that are involved;

FIG. 5 is a fragmentary sectional view of a modified form of the present invention.

FIG. 6 is a sectional view of an end portion of a blowpipe having an insert;

3 FIG. 7 is a sectional view of a blow-pipe assembly wherein the blowpipe and face plate each have individual inserts; and

FIG. 8 is a sectional view of an insert in a blowpipe with a face plate of the modified form of the FIG. 5. Referring first to FIG. 4, there is illustrated, somewhat schematically, a fragment of a blast furnace 10 near the bosch where the ring of tuyeres as 11 is located. Associated with each tuyere 11 is a blowpipe 12 having a fore end 13 configured to fit tightly in a complementally configured seat at the end of the tuyere 11 that is innermost with respect to the blast furnace 10.

The opposite end 15 of the blowpipe fits in a so-called face plate 17 in a manner described in more detail hereinafter. The face plate 17 includes an outer flange 18 adapted to be secured by bolts to the flange end 19 of a transition or intermediate conduit 20 in turn having a flange 21 bolted to the flange 22 of a gooseneck 25. The gooseneck 25 is connected to the bustle pipe (not shown) that surrounds or girdles the bosch portion of the furnace.

As shown in detail in FIG. 1, the blowpipe 12 as a whole includes an elongated tubular intermediate part 27 of uniform cylindrical section throughout its length. Preferably this intermediate section is cast centrifugally from a heat-resistant alloy. The two

end pieces

13 and 15 are separate sand castings preferably of a heat resistant alloy, and are secured to the respective ends of the intermediate tube 27 by welds W1 and W2.

The outer end face of the end section 15 of the blowpipe is in the form of a convex or outwardly arcuate con toured surface 39, and this contoured end of the blowpipe in any event is configured complemental to a seat 32 of the face plate 17.

As noted above, a marked deficiency in furnace operation occurs when a crack develops in the face plate or when the seat portion of the face plate is distorted because of plastic flow at its inner diameter. These defects are due to the large temperature differential that prevails between the inside diameter and the outside diameter of the face plate, and the manifest disadvantage is that gas escapes because of the lack of a good joint.

In accordance with the present invention, a large temperature .gradient across the face plate is avoided by lining the face plate seat 32 at least in part with a separate insert 35 composed of heat-resistant alloy. To this end, the portion of the face plate that receives the end 15 of the blowpipe is provided with an annular recess 37 formed inward from the flat outer face 38 thereof that is opposite the blowpipe 12. The recess 37 is of rightangle configuration including a flat axial wall 37A and a flat radial wall 37B disposed normal thereto.

The insert 35 is configured to fit complementally in the recess 37, and is accordingly cast to present a rightangled outer wall 46, FIG. 2, defined by an axial surface 40A and a radial surface 403 disposed at right angles thereto. The insert 35 as a whole is so sized that the flat outer face 41 thereof that is opposite the blowpipe will be flush with the surface 38 of the face plate as shown in FIG. 1 when the insert is arranged in the seat 37.

The insert 35 also includes a concave or inwardly arcuate surface 42 which in effect becomes a continuation of the arcuate face 32 of the face plate 17 when the insert is arranged in the seat 37 as will be evident in FIG. 1. As a consequence, the contoured surface 36 of the end '15 of the blowpipe nests against the arcuate seat afforded by the

curved surfaces

32 and 42 respectively of the face plate and the liner or insert 35 that is associated therewith.

It will be recognized that the annular outer rim 40A of the insert 35 presents, in cooperation with the axial wall 37A of the face plate seat 37, a barrier to the transfer of heat to and through the face plate 17. Thus, referring to FIG. 2, which is merely exemplary of typical relationships that can prevail from the standpoint of thermal gradients, it is assumed that the inside diameter of the insert 35 is at a temperature of 2000 F., and the temperature differential thereacross results in a temperature of approximately 1800 F. at the wall 40A. Since, however, there is a discontinuity or separation between the insert 35 and its related part 17 where the walls 40A and 37A are in opposition, transfer of heat to the face plate 17 is retarded, and the wall 37A can be assumed to be at a temperature of about 1400" F. with a relatively minor drop to 1000 F. at the outside diameter of the face plate 17.

Consequently there is not really the ordinary, wide temperature differential between the inside diameter of the face plate and the outside diameter thereof which is responsible for furnace inefficiency due to the manifest distortions in the face plate noted above. In this connection it may be observed that the thermal gradients noted in FIG. 2 are based on the absence of insulation. However, even when insulation is used as a lining for the blowpipe and transition piece 25, it disappears in a short time at the joint between the parts 15 and '25, which is the critical part of the construction here involved.

Various configurations, insofar as cross-section is concerned, can be used for the insert 35. However, under all circumstances the face plate insert or seat liner as 35 will present a female surface that is a complement of the contour presented by the adjacent male end of the blowpipe with which it will be in contact, and the insert will present an outer wall complemental to the recess in the face plate which affords a seat for the liner. Thus, another example of configuration that can be used is illustrated in FIG. 5 wherein the face plate 45 is shaped complement-a1 to a portion of the end 15 of the blowpipe. The face plate 45 is provided with an annular seat for an insert 48 that serves the function of the insert 35 described above. It will be observed in FIG. 5 that the insert 35 has an outer wall defined by two concentric

axial portions

48A and 48B joined by a radial wall 480 disposed normal thereto. The insert 48 presents an arcuate surface 48D that is a continuation of the blowpipe seat 46 of the face plate.

Thus, while the blowpipe 15 and connecting pipe 25 each have their interior, cylindrical surfaces lined with an insulating material, the face plate 17 often is not lined. Even where the face plate 15 is lined with insulation along its inner diameter wall, under actual operating conditions, the insulation is too narrow to hold and because of the cracks at its juncture with opposing insulating linings the high temperature gas causes the lining to break off. Under actual operating conditions, the contoured seats of the face plate and blowpipe do not fit so exactly that the insulated linings are abutted Without any space therebetween. Hence, an insert will be exposed in almost all cases to the high temperature gas.

In the embodiments of the invention shown in FIGS. 15, inclusive, only the

face plates

17 or 45 are provided with an insert or lining, namely inserts 35 or 48. However, in the embodiment of the invention shown in FIGS. 6-8, inclusive, the end section 15 of the blow pipe 12 is likewise furnished with an annular liner or insert 50 for seating in engagement with the complementary seats formed in either of the

face plates

17 or 45. The end portion 15 of the blowpipe is subjected to the high temperature gas since the insulation lining on the interior of the blowpipe disappears at this leading edge portion a short time after being subject to this 2000 F. temperature.

As shown in FIG. 6, the insert 50 is preferably tackwelded by small pieces of flat stock 56 at spaced locations to prevent leftward axial movement of the annular ring shaped insert 50. Rightward movement of the annular insert 50 is prevented by an outwardly extending radial flange 58 on the annular insert 50, which is in engagement with a radial end wall 59 of the blowpipe end section 15.

The outer peripheral surface 60 of the insert 50 is curved so as to be a continuation of the convex surface 30 of the blowpipe end section so that the adjoining convex surfaces 30 land 60 are received in the complementally shaped seating surfaces 32 and 42, respectively.

Thus, as seen in FIG. 6, the temperature differential between the outer surface 30 of the blowpipe and the inner axial surface 62 of the blowpipe is considerably lessened because the cross sectional thickness of the end portion of the blowpipe 15 is reduced and because the surface 62 is not subjected directly to the high temperature gas. The insert 50 is similar to the face plate inserts 35 and 48 in that the insert 50 is made of highly heat resistant alloys as are each of the face plate inserts 35 and 48. Inasmuch as the 2000* F. temperature of the hot gas is encountered at the inner-diameter of the insert, it is advantageous to have the insert of a material that displays greater resistance to heat than the outside diameter part with which the insert is associated. For example, the insert is preferably of a heat resistant alloy characterized by a heat resist-ant alloy of high chromium and high nickel type such as one that has a nickel content of 20% to 65%, chromium content of 25% to 35%, carbon content of 3% to .6%, a balance selected from the group consisting of cobalt, tungsten and iron. Alternatively, an insert could be a ring of ceramic material having a high resistance to the heat encountered at the interior of the pipe and thereby serving as buffer in the manner of heat resistant steel.

It is also preferred that the face plate 15 be of a heat resistant alloy, but inasmuch as the temperature to which the face plate is subjected is not as high as the temperature to which the insert is subjected, a less expensive heat resisting alloy can be used, for example, nickel content of to 20%, chromium content of 20% to 25%, carbon content of 3% to .6%, balance selected from the group consisting of tungsten, cobalt and iron. The blowpipe is made of the heat resistant alloys and in the manner set forth in my patent, Patent No. 2,937,018, issued May 17, 1960.

In the embodiment of the invention shown in FIG. 7, the blowpipe insert 50 extends to or adjacent to the end of the connecting conduit 25 and the insert 35 of the face plate 17 is disposed thereabove; FIG. 7 being essentially the same as FIG. 1, except that the blowpipe section end is provided with the insert 50. The blowpipe insert 50 is shown in FIG. 7 as seated against the face plate 45 and face plate insert 48 of the embodiment of the invention shown in FIG. 5.

As can best be understood from examination of FIGS. 7 and 8, when the hot gases flow through the connecting conduit 25 and blowpipe 12, the inner-diameter surfaces 65 of the

adjacent inserts

48 and 50, FIG. 8, are each exposed to a 2000 temperature. However, because these

inserts

48 and 50 are made of a more highly heat resistant alloy, these inserts can withstand the high temperatures more readily without cracking. Additionally, because of the narrowed cross sectional thickness of the face plates 47, 45 and end section 15, the temperature differential between the outside diameter and inside diameter of a face plate or end section is not nearly as high as the temperature differential would be if they were made in one part, as heretofore was the case. The temperature differential across an element is extremely important as the stress imparted to the metal varies mainly as a function of the temperature differential between the outside diameter and the inside diameter so that the less thick part has less stress.

As best apparent from FIGS. 7 and 8, even if one or more of the abutting inserts 35, 50 and 48, 50 becomes cracked, the outer face plate and blowpipe end portion 15 are still in sealed engagement at their respective complementary seats to prevent the loss of the gas. Thus, as heretofore explained, the face plate 17 and flange 15 are protected by the

respective inserts

35 and 50 and have much greater strength to assure a tight seal than they would possess if not afforded with the inserts.

Both the face plate inserts 35 and 45 and blowpipe inserts 50 are tack-welded in place to hold the inserts in proper position when machining the face plates and the end of the blowpipe 15. Also, the tack welds hold the inserts in proper position during assembly operations. However, as the inserts go up to temperature of approximately 2000 F, the tack welds no longer are effective and the inserts are free to radially expand because of a built-in clearance between the outside diameter and in sert and the inside diameter of its complementary face plate or end section. Thus, a clearance of approximately of an inch is provided and the insert is permitted to expand under high temperatures and hence will not be subjected to a compression or the plastic flow encountered in the one-piece face plate or blowpipe, which was not able to expand.

From the foregoing, it was seen that the blowpipe assembly of the present invention is assured a longer life and increased efliciency by affording at least one insert in either the blowpipe or face plate, or both to act as a barrier or buffer to protect the actual sealing face plate and blowpipe against cracking or distortion due to a large temperature drop thereacross. Also, the inserts bear the brunt of the interface with the high temperature gases so that the inner diameter portions of the respective complentary faces on the plate or blowpipe are subjected to a much lower temperature and hence that the outer portions will have greater strength to retain their seated positions.

It will be seen from the foregoing that under the present invention a face plate for a blowpipe is assured a longer life, and increased furnace efficiency is obtained, by so constructing the same as to include a loose, separable insert which in effect is an extension of the inner diameter of the face plate most directly associated with the hot gases fed to the furnace through the blowpipe. Such an insert breaks up the continuity of the face plate and thereby reduces the thermal gradient from the inside to the outside thereof, heretofore responsible for the face plate failures noted. Hence, while I have illustrated and described preferred embodiments of my invention, it is to be understod that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall Within the purview of the following claims.

I claim:

1. In a blowpipe assembly for a blast furnace wherein gas from a bustle is introduced into the furnace through a tuyere connected to the bustle by means including the blowpipe, an elongated blowpipe tube of generally cylindrical form affording a path for gas from the bustle pipe to the furnace tuyere, a face plate for supporting one end of the tube, said one end of the tube being provided with a contour complemental to a seat formed in the face plate with said contoured end of the tube comp lemental- 1y fitted in said seat, and said seat being lined at least in part with a separate substantially annular insert at the interior of said face plate thereby to create barriers to thermal transfer through the face plate from the inside to the outside diameter thereof.

2. A blowpipe assembly according to claim 1 wherein the insert includes a right-angled outer edge that fits a complemental seat in the face plate, and an arcuate side surface which abuts the contoured end of said tube.

3. In a blowpipe assembly for a blast furnace for conducting high temperature gas from a bustle and connecting pipe to a tuyere where the high temperature gas is introduced into the furnace, an elongated blowpipe tube of generally cylindrical form affording a conduit for gas, a face plate for securing one end of the blowpipe to the connecting pipe from the bustle, said one end of the blow-pipe being provided with a contoured seat, said face plate having a seat contoured complement'ally to the seat in said blowpipe for receiving the contoured end of the blowpipe, and at least one of said seats being lined at least in part with a separate substantially annular insert disposed at the interior cylindrical surface of the pipe and to be subjected directly to the hot gas.

4. The blowpipe assembly of claim 1 wherein said insert is of a more highly heat resistant material than the heat resistant material forming the seat which is being lined by said insert.

5. In -a blowpipe assembly for a blast furnace for conducting hi-gh temperature gas from a bustle and connecting pipe to a tuyere for introducing the hot gas into the furnace, an elongated bloWpi-pe tube of generally cylindrical form affording a conduit for gas, a face plate for securing one end of the blowpipe to the connecting pipe from the bustle, said one end of the blowpipe being provided With a contoured seat, said face plate being for-med with a seat contoured complementally to receive said contoured end of said blowpi-pe, said contoured end of said b lowpipe being lined at least in part with a separate substantially annular insert at the interior cylindrical surface of the blowpipe and at the leading edge of the blowpipe being received by said face plate, said insert bearing the brunt of high temperature gas at the leading end of the blowpipe.

6. The blowpipe assembly of claim 5 wherein said insert is of a more heat resistant material than the material of said bloW'pipe at the leading end thereof.

7. In a blowpipe assembly for a blast furnace, for conducting high temperature gas from a bustle and connecting pipe to a tuyere for introducing the hot gas into the furnace, an elongated blowpipe tube of generally cylindrical form affording a conduit for gas, a face plate for securing one end of the blow-pipe to the connecting pipe from the bustle, said one end of the blowpipe being provided with a contoured seat, an annular ring insert at the leading end of said blowpipe, said face plate having a seat contoured eomp lementally to said contoured seat of said blowpipe, and an substantially annular insert in said face plate disposed at the inner diameter of said face plate and engageable with said blowpipe insert.

8. In a blowpipe assembly for a blast furnace, for conducting high temperature gas from a hustle and connecting pipe to a tuyere for introducing the hot gas into the furnace, a long elongated blowpipe tube of generally cylindrical form affording a conduit for gas, a face plate for securing one end of the blowpipe to the connecting pipe from the bustle, said one end of the blowpipe being provided with a'contoured seat, said one end of said blowpipe being provided at its leading edge with an armate contour, and with an annular ring, the interior of said annular ring being subjected to the high temperature gas, the seat formed in said face plate of a contour complemental to the arcuate seat of said blow-pipe, said seat of said face plate being lined at least in part with an annular ring at the interior of said face plate and adjacent said insert of said blowpipe to receive exposure to the high temperature gas.

9. In a blow-pipe assembly for a blast furnace for conducting high temperature gas from a hustle and connecting pipe to a tuyere Where the hot gas is introduced into the furnace, an elongated blowpipe tube of generally cylindrical form affording a conduit for gas, a face plate for securing one end of the blowpipe to the connecting pipe from the bustle, said one end of the blowpipe being provided with a contoured seat, said one end of said blowpipe being provided at its leading edge with an armate contour, an annular blowpi-pe insert having an outer face contoured to be an extension of said arcuate contour of said blowpipe end, the interior of said annular insert being subjected to the high temperature gas, a seat formed in said face plate of a contour complemental to the arcuate seat of said blowpipe, said seat of said face plate being lined at least in part with an annular face plate insert having an arcuate surface for complemental engagement with the contoured face of said annular blowipipe insert.

10. The blowpipe assembly of claim 9 wherein said annular inserts are of a more highly heat resistant metal than the heat resistance metal of their respective blowpipe and face plate.

References Cited by the Examiner UNITED STATES PATENTS 714,726 12/1902 Marsh 2S5329 X 909,959 1/1909 Stoddard 285329 1,005,359 10/1911 Symons 26641 1,362,702 12/1920 Ives 26641 1,844,194 2/1932 Maltitz 266-30 2,023,025 12/1935 McKee 26641 2,087,842 7/1937 Gerwig .266-41 2,937,018 5/1960 Boron 266-41 FOREIGN PATENTS 235,316 6/1925 Great Britain.

CHARLIE T. MOON, Primary Examiner.

Claims

1. IN A BLOWPIPE ASSEMBLY FOR A BLAST FURNACE WHEREIN GAS FROM A BUSTLE IS INTRODUCED INTO THE FURNACE THROUGH A TUYERE CONNECTED TO THE BUSTLE BY MEANS INCLUDING THE BLOWPIPE, AN ELONGATED BLOWPIPE TUBE OF GENERALLY CYLINDRICAL FORM AFFORDING A PATH FOR GAS FROM THE BUSTLE PIPE TO THE FURNACE TUYERE, A FACE PLATE FOR SUPPORTING ONE END TO THE TUBE, SAID ONE END OF THE TUBE BEING PROVIDED WITH A CONTOUR COMPLEMENTAL TO A SEAT FORMED IN THE FACE PLATE WITH SAID CONTOURED END OF THE TUBE COMPLEMENTALLY FITTED IN SAID SEAT, AND SAID SEAT BEING LINED AT LEAST IN PART WITH A SEPARATE SUBSTANTIALLY ANNULAR INSERT AT THE INTERIOR OF SAID FACE PLATE THEREBY TO CREATE BARRIERS TO THERMAL TRANSFER THROUGH THE FACE PLATE FROM THE INSIDE TO THE OUTSIDE DIAMETER THEREOF.