US3722871A - Blast furnace with staggered tuyere system - Google Patents

Abstract

Tuyere systems for blast furnaces are disclosed embodying two or more rows of tuyeres, to provide increased capacity for injection of blast air and for injection of materials to control temperatures and reactions inside the blast furnace. The increased capacity provided by more than one row of tuyeres makes possible the introduction of air and injected other materials in sufficient quantities to provide desired temperatures and reactions, and efficient operation of blast furnaces of exceptionally large diameters. The tuyeres are disclosed as arranged substantially equidistantly from the iron notch to make possible equalization of heating around the notch, and to minimize hazardous conditions. At least four iron notches are utilized, and advantageous processes are disclosed for withdrawing iron through the iron notches. Tuyeres in the multiple rows may be divided into groups through which injection materials may be injected into the furnace independently of the tuyeres in other groups to provide control of internal condition temperatures and reactions in the furnace.

Description

Elite States Greaves ate 154] BLAST FURNACE WITH STAGGERED TUYERE SYSTEM [75] Inventor: Melvin J. Greaves, Cleveland, Ohio [73] Assignee: Arthur G. McKee & Company,

Cleveland, Ohio 22 Filed: Oct. 15, 1970 21 Appl.No.: 80,907

Primary ExaminerRobert D. Baldwin Attorney-Bosworth, Sessions, Herrstrom & Cain [57] ABSTRACT Tuyere systems for blast furnaces are disclosed embodying two or more rows of tuyeres, to provide increased capacity for injection of blast air and for injection of materials to control temperatures and reactions inside the blast furnace. The increased capacity provided by more than one row of tuyeres makes possible the introduction of air and injected other materials in sufficient quantities to provide desired temperatures and reactions, and efficient operation of blast furnaces of exceptionally large diameters. The tuyeres are disclosed as arranged substantially equidistantly from the iron notch to make possible equalization of heating around the notch, and to minimize hazardous conditions. At least four iron notches are utilized, and advantageous processes are disclosed for withdrawing iron through the iron notches. Tuyeres in the multiple rows may be divided into groups through which injection materials may be injected into the furnace independently of the tuyeres in other groups to provide control of internal condition temperatures and reactions in the furnace.

3 Claims, 8 Drawing Figures Patented March 27, 1973 5 Sheets-Sheet 2 INVENTOR.

M54 z/m/ J lzm/s Boowzrwh 8.246

Han/14am Patented March 27, 1973 5 Sheets-Sheet 3 Patented March 27, 1973 I 3,722,871

5 Sheets-Sheet 4 INVENTOR.

MEZV/A/ J. leffll fs BY 80 mm, 3.044% 9 HMEMXM BLAST FURNACE WITH STAGGERED TUYERE SYSTEM This invention relates to blast furnace apparatus, and more particularly to systems of tuyeres embodied in blast furnace apparatus.

BACKGROUND OF THE INVENTION For convenience, the invention will be discussed in connection with blast furnace apparatus for reducing iron ore to metallic iron, although at least certain aspects the invention may be applicable to other types of blast furnaces.

In the blast furnace art, the present tendencies are toward the building of increasingly larger blast fur naces, to obtain larger and more efficient production, some of the furnaces projected or under construction having production capacities of l0,000 tons or more of pig iron per day.

In conventional blast furnace practice, air for burning the coke in the burden to produce reducing conditions for reducing the iron oxides in the burden to metallic iron and to generate heat for melting the iron, is introduced through tuyeres above the hearth of the furnace. However, when the furnace diameter is increased substantially in the design of large furnaces, the problem of introducing sufficient amounts of air' is also increased, since the amount of air to be introduced is generally proportional to the square of the furnace diameter.

Moreover, in all blast fumaces, even those of relatively small diameters, there are problems of maintaining reaction conditions as uniform as possible across the cross section of the furnace, and of controlling the temperatures and reaction conditions to provide for efficient reduction of the iron ore and production of metallic pig iron of desired quality. These problems greatly increase as the furnace size is increased.

SUMMARY OF THE INVENTION The present invention provides apparatus for solving these problems, and also for making possible the proper and efficient operation of furnaces of exceptionally large diameters. According to the present invention, at least two superposed rows of tuyeres are used in the lower portion of the furnace above the hearth, the tuyeres being arranged preferably in staggered relation to each other.

Preferably, the tuyeres are so arranged that immediately above an iron notch, the tuyere of the lower row is omitted, and the tuyeres in the lower and upper rows are so arranged relative to the iron notch that the iron notch is substantially equidistant from such tuyeres, to provide for equalization of temperatures and reactions and minimizing of hazardous conditions in the vicinity of and over the iron notch. A slag notch may also be disposed above the iron notch if desired, and also be substantially equidistant from tuyeres in the upper and lower rows.

Furthermore, according to the invention, several iron notches are utilized, preferably at least four, so that at least two iron notches can be opened at the same time to provide for rapid outflow of pig iron from widely spaced locations around the furnace, which is important in furnaces of large capacity and important in making possible greater uniformity of pig iron characteristics, and so that advantageous tapping iron product as a result of the injection. Powdered coke or coal, or ground flux may also be injected for temperature control and for the addition of desired reactants.

According to the invention, moreover, groups of tuyeres in the multiple rows of tuyeres may be operable independently of other groups for injection of materials so as to provide greater flexibility in operation and control of temperatures and reactions in localized zones within the furnace to provide desired overall temperatures and conditions above the furnace at the general level of the tuyeres.

DESCRIPTION OF DRAWINGS These and other features and advantages of the invention will be apparent from the following discussio in connection with the drawings in which: I

FIG. I is a side elevation of a blast furnace embodyingthe invention, parts being broken away for clearness;

FIG. 2 is a section of the furnace of FIG. I to the same scale and along line 22 of FIG. 1;

FIG. 3 is a developed-diagrammatic view to a larger scale showing a preferred arrangement of the tuyeres in relation to the iron notches;

FIG. 4 is a section generally along line 4-4 of FIG. 1 and to a larger scale, showing two tuyeres in superposed rows;

FIG. 5 is a detail section to an enlarged scale of alternate tuyeres that may be advantageously used, the section being offset to show two staggered tuyeres in section;

FIG. 6 is a diagrammatic cross section of a furnace embodying the invention, showing the raceway formed by combustion inside the furnace at the tuyeres; and

FIG. 7 is a diagrammatic view showing a system embodying arranged in two rows of tuyeres arranged according to the invention, and means for injecting materials into the furnace through separate groups of tuyeres for localized control of temperatures and reactions in the furnace at the tuyere level; and

FIG. 8 is a diagrammatic view to a smaller scale than FIG. 6 to illustrate operations with five iron notches.

DESCRIPTION The invention is described below in connection with a blast furnace generally similar to that disclosed in U. S. Pat. No. 3,431,691 of M. J. Greaves and Tage Werner. As shown in FIGS. 1 and 2, this furnace comprises a supporting structure 1 comprising an essentially rigid horizontal frame 2 surrounding the furnace portion 3. The frame is supported by four widely spaced outwardly inclined legs 4. Furnace portion 3 is supported from the frame 2 by connector members 5 connected to the frame 2, and to the shell 6 of the furnace and a ring member 7 connected to shell 6 above the bosh 8 of the furnace.

A superstructure 9 is supported from frame 2. The upper portion of the furnace is not shown since this may be conventional. Shell 6 has a conventional refractory lining 10.

As shown in FIGS. 1, 3 and 4, the illustrated furnace embodies two rows 11 and 12 of tuyeres, row 11 being made up of tuyeres 11a and 11b and row 12 being made up of tuyeres 12a and 12b, the tuyeres in the two rows being disposed in staggered relation relative to each other entirely around the circumference of the furnace below the bosh; in this embodiment there are four iron notches 13. These iron notches are disposed equiangularly and circumferentially equidistantly around the furnace at the same horizontal level. In this arrangement of tuyeres, moreover, there is no tuyere in the lower row immediately over each iron notch 13, and each notch 13 and tuyeres 11a of the upper row and tuyeres 12a of the lower row are arranged as shown in FIG. 3 so that these tuyeres are substantially equidistant from such iron notch by distance D, and the notch is equidistant between adjacent tuyeres 11a in the upper row.

To aid in this, and to provide added heat to compensate for the omitted tuyere in the lower row above the iron notch, tuyeres 11a in the upper row over each iron notch are substantially closer together, than the other tuyeres in that row.

With this arrangement, large volumes of blast air can be supplied even in furnaces of exceptionally. large diameter, to make possible efficient and effective operation. Moreover, the arrangement of tuyeres around the iron notches makes possible uniform heating in the vicinity of the notch while eliminating any possibility of the blast blowing out through the iron notch during tapping. Moreover, the tuyeres are located outside of the zone Z of potential. hazard around the iron notch one of which zones is shown in broken lines'in FIG. 3.

The tuyeres may beof conventional construction, as in FIG. 4, which shows two tuyeres 11a and 12a; tuyere 12a isshown in section, while tuyere 11a, which is identical is not. Each tuyere, in known manner com prises a tuyere stock 15 connected to a blow pipe 16 the inner end of which nests in a water-cooled tuyere casting 17 having discharge passage 18. Tuyere stock 15 of lower tuyere 12a communicates with a gooseneck portion 19 that opens into heat-insulated bustle pipe 20 connected to a suitable conventional source, not shown, of hot blast air. The tuyere stock of upper tuyere 11a is connected to a gooseneck portion 21 that also opens into bustle pipe 20. Pipe 20 is supported from ring member 7 by hangers 22. The tuyeres shown in this figure discharge generally'horizontally into the furnace.

Each of these tuyeres, moreover, has means for injecting materials other than air into the furnaces; that illustrated in FIG. 4 comprises a tube 25, connected through valve -26 to a supply conduit 27, that discharges into blow pipe 16.

Preferably tuyeres 11a discharging generally horizontally are used above the iron notch avoid providing a hazardous condition at this area. Tuyeres 12b in the lower row between the iron notches preferably are designed to discharge blast air and injection material downwardly at an angle to the horizontal to avoid too much interaction between these tuyeres and the ones above.

Furthermore, it is preferable that the tuyeres in the upper row between the iron notches be substantially larger in diameter than those in the lower row to make possible increased air flow and hence increased reaction activity in the upper region which is nearest the burden in the furnace above, and to make possible injection of larger amounts of injection materials.

FIG. 5 illustrates these features, with lower tuyeres 12b having a tuyere cooler casting 17b shaped to discharge downwardly, preferably at anangle of about 22 from the horizontal, and the upper tuyere 1 lb being of substantially larger diameter and capacity than the lower tuyere 12a and other tuyeres 11a and 12b and having a tuyere cooler casting 29 shaped to discharge generally horizontally.

FIG. 5 also illustrates that other types of injection means may be employed. In this figure, each casting 17b and 29 has a passage 31 discharging into casting discharge passage 18 near the end of the casting in the furnace, and connected to a tube 32 that communicates through valve 26 with a conduit 27 to a source of injection material.

Arrangement of the tuyeres in two ormore rows, in generally staggered relationship, also makes for more efficient combustion and more uniform reaction because it causes the formation of a more continuous and more homogeneous raceway of combustion gases and flame in the furnace. In conventional furnaces, with widely spaced tuyeres in a single row, there is an individual zone or opening in the burden around each tuyere, into which the blast air discharges and in which combustion and generation of reducing gases occur. These individual zones are in general separated from their neighbors.

According to the present invention, however, because of the relatively close, staggered relationship of the tuyeres, the zones generatedby adjacent tuyeres merge so that a substantially continuous generally annular raceway R or zone of flame and reducing gases substantially free of burden is formed inside of the furnace in the vicinity of the tuyeres. The raceway R is shown in cross section in FIGS. 4 and S, and in plan in FIG. 6, in which latter figure the merging of adjacent zones into a single zone is illustrated. As shown in FIG. 5, moreover, the raceway is deeper in the vicinity of those lower tuyeres that discharge downwardly.

Preferably, as illustrated in FIG. 7 the injection means for the tuyeres are connected together in groups that are individually connectible to each of a multiplicity of conduits, as shown as 33 to 39 inclusive in FIG. 7,

g for supplying various types of injection materials to the individual groups of tuyeres. Thus, in the arrangement shown in FIG. 7, the four tuyeres, 12a, 11a, 11a and 12a in the vicinity of each iron notch 13 are connected together to form a group A connected to conduit 40 and communicating through conduits 41-47 and their respective control valves 41a-47a with the conduits 33-39.

Moreover, each group of tuyeres 11b in the'upper row between each pair of groups A are connected together to form a group designated as B connected to a conduit 50. Each conduit 50 communicates through one of conduits 51-57 and the appropriate control valves 51a-57a with a selected one of conduits 33-39.

Similarly, each group of tuyeres 12b in the lower row between each pair of groups A are connected together to form a group designated as C that is connected to a conduit 60. Each conduit 60 for each group C can communicate through one of conduits 61-67 and the appropriate one of control valves 61a-67a with a selected one of conduits 33-39.

The control valves are connected by suitable operating means designated by lines 71 to a control unit 72. This may be a manually operable control unit, or if desired even a computer type control unit, to open or close the valves desired.

There are thus, in the illustrated embodiment, a total of 16 groups of tuyeres, each of which groups may be individually controlled to inject into the furnace any one of seven injection materials. Consequently, it is possible to control the injection of materials into the tuyeres and into the furnace at various locations around the furnace. The operator, therefore, has an opportunity to adjust the temperature and the basicity of the hearth individually in the neighborhood of each iron notch. He can do this by using a suitable one of various injection materials, such as oxygen, steam, calcined lime, ground limestone, pulverized coke or coal or low hydrogen tar, methane or natural gas'or oil or other material containing substantial amounts of hydrogen, or iron ore, or other materials.

Thus, for example, if the operator finds that the furnace is running cold just prior to tapping the furnace, he can add either oxygen, or carbon in the form of coke or coal, or tar, to increase combustion to raise the temperature at the portion of the furnace where the oxygen or fuel is injected. If the furnace is running hot, he can inject steam or natural gas to coolit in the vicinity of the injection. If there is insufficient lime and the temperature is too high, he can inject ground limestone, and if there is insufficient lime and the temperature is not too high, he can inject calcined lime. Likewise, if the conditions described above exist in the lower portion of the raceway R, the condition can be corrected by these same additions into the tuyeres of the group C, whereas if the condition exists in the upper portion of the raceway, these same materials can beinjected into the tuyeres of group B.

Furthermore, if the temperature and chemical conditions are satisfactory along the vertical axis of the furnace, but one side of the furnace requires adjustment to make the furnace operate uniformly, then groups of tuyeres on the cold side of the furnace can have injections through them of-oxygen or carbon to cause additional heating. If the furnace is too hot, the groups of tuyeres on the hot side can have injected through them steam or methane or natural gas or air to chill the furnace. If additional lime is required, the condition can be corrected by injecting calcined lime if the temperature is satisfactory, and ground limestone if the temperature is too hot.

The addition of lime or limestone also, particularly when it is injected in the upper tuyeres is beneficial in removing sulphur.

It is preferable, that when oxygen is added, it be blown in at the lower level tuyeres since greater combustion effectiveness is thus provided.

Furthermore, if desired, iron ore can be introduced by the injection system into the tuyeres not only for temperature control, but also to provide added iron values. If high purity iron ore is introduced through the tuyeres, then the oxygen in the iron ore will also reduce the amount of air that is needed to be introduced into the tuyeres. Oxygen introduced by the ore can reduce the oxygen required to be added by blast air by an equivalent amount. If desired, a properly proportioned mixture of finely divided iron ore, finely divided coke or coal and finely divided flux material such as hydrolized or calcined lime, may be injected through some or all of the tuyeres for temperature or reaction control and while adding reactants that produce useful values in the product. These reactants can be cold, but preferably are preheated.

v Thus, the arrangement of staggered tuyeres and the grouping of the tuyeres for injection purposes makes possible great flexibility of operation and control.

The use of four or more iron notches also makes possible great flexibility and efficiency in operation, particularly in large furnaces. One, two, three or more notches can be tapped simultaneously, depending on the production rate, while at least one is closed or under repair.

Preferably, the iron notches are operated to discharge iron in a staggered manner, so that at any one time iron is being removed from the furnace from one old opened, and one newly opened iron notch to minimize erosion due to tapping, while at least two notches are closed. Preferably, moreover, iron notches on opposite sides of the furnaces are operated simultaneously so as to provide for more uniform removal of iron and more uniform operation of the furnace.

These advantages are apparent from the following discussion in connection with FIGs. 6 and 8.

Thus, as shown inFIG. 6 showing for iron notches 13a, 13b, 13c, and 13d, the iron notches may be opened in pairs, in the following sequence:

13a and 13b and 13d 13c and 13a 13d and 13b An even better cycle is provided when five iron notches are used, as illustrated diagrammatically in FIG. 8 showing five notches 13-1, 13-2, 13-3, 13-4, and 13-5 used in a furnace having two or more rows of staggered tuyeres as described above which are equiangularly and circumferentially equidistantly arranged at the same level around the furnace. These notches may be opened in pairs to discharge metal in a sequence as follows:

13-1 and 13-3 13-2 and 13-4 13-3 and 13-5 13-4 and 13-1 13-5 and 13-2 l3-.1 and 13-4 13-2 and 13-5 13-3 and 1.3-1

13-4 and 13-2 13-5 and 13-3 Thus an even greater number of combinations is possible, particularly when the first mentioned notch of a pair is opened before the second notch of a pair. Moreover, three notches are closed at all times.

It is also possible to operate the furnace so that one iron notch is always open, in which case slag is removed as it is formed, which makes possible the unique result of making possible uniform desulphurization of the iron.

lf slag notches are employed, which-may not be necessary if one iron notch is always open, they may be operated in conventional manner in conjunction with their associated iron notches.

From the above, it is apparent that the disclosed arrangements of tuyeres in a plurality of rows, particularly the arrangement indicated whereby several iron notches are used, each of which is essentially equidistant from tuyeres in the several rows, provides a great flexibility of operation and means for increasing the control of the furnace conditions.

Moreover, the staggered arrangement of tuyeres makes possible the utilization of a substantially larger number of tuyeres than is possible in conventional practice, which is important in introducing necessary or desired volumes of air and injection materials into furnaces of the extremely large sizes now beingbuilt or projected.

While two rows of staggered tuyeres have been shown, it is apparent that more than two rows may be utilized if desired, and that the tuyeres in the rows may be arranged somewhat differently than illustrated, although the illustrated staggered arrangements are preferable from a standpoint of operating conditions and added strength of the furnace wall. Although both rows of tuyeres are shown as supplied with air from one bustle pipe, more than one pipe may be used, such as one for reach row of tuyeres.

Other injection materials than those mentioned may be used, and more or less injection materials may be supplied.

It will be apparent to those skilled in the art that the disclosed apparatus may be modified in various manners other than those indicated above without departing from the spirit of the invention, and that the invention will provide advantages other than those indicated. It is intended that the patent shall cover by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

I claim:

l. Blast furnace apparatus comprising two superposed rows of tuyeres extending around the furnace,

the tuyeres in two adjacent rows being staggered relative to each other, the adjacent tuyeres in each row of staggered tuyeres and in adjacent rows of staggered tuyeres being sufficiently close together to permit the openings in the burden around the tuyeres caused by discharge of blast air through the tuyeres and combustion in the vicinity of the tuyeres to merge so that a substantially continuous generally annular raceway of flame and reducing gases substantially free of burden is formed inside the furnace in the vicinity of the tuyeres, and a notch for the discharge of material from the blast furnace that is disposed below the rows of tuyeres substantially equidistantly from the tuyeres in said two rows said discharge notch being disposed substantially equi lstantly between the tuyeres in an upper row, there being no tuyere in the lower row above the discharge notch.

2. The apparatus of claim 1 in which tuyeres adjacent the notch in a row of tuyeres above the notch are more closely spaced than other tuyeres in said row to provide substantial uniformity of heat generated by utilization of material emitted from the tuyeres notwithstanding omission of a tuyere below said row because of the notch.

3. Blast furnace apparatus comprising two superposed rows of tuyeres extending around the furnace, the tuyeres in two adjacent rows being staggered relative to each other, the adjacent tuyeres in each row of staggered tuyeres and in adjacent rows of staggered tuyeres being sufficiently close together to permit the openings in the burden around the tuyeres caused by discharge of blast air through the tuyeres and combustion in the vicinity of the tuyeres to merge so that a substantially continuous generally annular raceway of flame and reducing gases substantially free of burden is formed inside the furnace in the vicinity of the tuyeres, and at least four notches for the discharge of material from the blast furnace that are disposed below the rows of tuyeres substantially equidistantly from the tuyeres in said two rows and are substantially equidistantly spaced around the furnace, each discharge notch being disposed substantially equidistantly between the tuyeres in an upper row, there being no tuyere in the lower row above the discharge notch, the tuyeres adjacent each notch in a row of tuyeres above the notch being more closely spaced than other tuyeres in said row to provide substantially uniformity of heat generated by utilization of materials emitted from the tuyeres notwithstanding omission of any tuyere below said row because of said notch.

Claims (3)

1. Blast furnace apparatus comprising two superposed rows of tuyeres extending around the furnace, the tuyeres in two adjacent rows being staggered relative to each other, the adjacent tuyeres in each row of staggered tuyeres and in adjacent rows of staggered tuyeres being sufficiently close together to permit the openings in the burden around the tuyeres caused by discharge of blast air through the tuyeres and combustion in the vicinity of the tuyeres to merge so that a substantially continuous generally annular raceway of flame and reducing gases substantially free of burden is formed inside the furnace in the vicinity of the tuyeres, and a notch for the discharge of material from the blast furnace that is disPosed below the rows of tuyeres substantially equidistantly from the tuyeres in said two rows, said discharge notch being disposed substantially equidistantly between the tuyeres in an upper row, there being no tuyere in the lower row above the discharge notch.

2. The apparatus of claim 1 in which tuyeres adjacent the notch in a row of tuyeres above the notch are more closely spaced than other tuyeres in said row to provide substantial uniformity of heat generated by utilization of material emitted from the tuyeres notwithstanding omission of a tuyere below said row because of the notch.

3. Blast furnace apparatus comprising two superposed rows of tuyeres extending around the furnace, the tuyeres in two adjacent rows being staggered relative to each other, the adjacent tuyeres in each row of staggered tuyeres and in adjacent rows of staggered tuyeres being sufficiently close together to permit the openings in the burden around the tuyeres caused by discharge of blast air through the tuyeres and combustion in the vicinity of the tuyeres to merge so that a substantially continuous generally annular raceway of flame and reducing gases substantially free of burden is formed inside the furnace in the vicinity of the tuyeres, and at least four notches for the discharge of material from the blast furnace that are disposed below the rows of tuyeres substantially equidistantly from the tuyeres in said two rows and are substantially equidistantly spaced around the furnace, each discharge notch being disposed substantially equidistantly between the tuyeres in an upper row, there being no tuyere in the lower row above the discharge notch, the tuyeres adjacent each notch in a row of tuyeres above the notch being more closely spaced than other tuyeres in said row to provide substantially uniformity of heat generated by utilization of materials emitted from the tuyeres notwithstanding omission of any tuyere below said row because of said notch.

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