US3702694A

US3702694A - Method and apparatus for judging the conditions of blast furnace

Info

Publication number: US3702694A
Application number: US142605A
Authority: US
Inventors: Naoteru Oda; Seiichi Nishimura; Hideo Komatsu
Original assignee: Sumitomo Metal Industries Ltd
Current assignee: Nippon Steel Corp
Priority date: 1970-05-20
Filing date: 1971-05-12
Publication date: 1972-11-14
Anticipated expiration: 1989-11-14
Also published as: DE2124969B2; FR2090168B1; GB1342927A; NL158849B; CA933272A; DE2124969C3; NL7106901A; DE2124969A1; JPS5025415B1; FR2090168A1

Abstract

AMONG THE SOLID BORNE SOUNDS GENERATED BY THE MANTLE OF THE BLAST FURNACE IN OPERATION, THE MAGNITUDE OF THE LEVEL OF THE SOLID BORNE SOUNDS WITHIN THE SPECIFIC FREQUENCY BAND IS CORRELATED WITH THE CONDITIONS OF THE BLAST FURNACE, FOR EXAMPLE, SLIPPIN, HANGING OR FALLING OF THE HANGING. A DETECTOR DETECTS SOLID BORNE SOUNDS FROM THE MANTLE

OF THE BLAST FURNACE, A BAND PASS FILTER CIRCUIT SELECTS THE SOLID BORNE SOUNDS WITHIN THE SPECIFIC FREQUENCY BAND, AND AN INTEGRATION CIRCUIT PRODUCES SIGNALS EXPRESSING THE MEAN INTENSITY LEVEL OF THE SELECTED SOLID BORNE SOUNDS. THROUGH THE SIGNALS THE CONDITION OF THE BLAST FURNACE IS JUDGED.

Description

Nov. 14, 1972 NAOTERU ODA ET AL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLAST FURNACE Filed May 12, 1971 B Sheets-Sheet 1 I STOCK LINE 5TH DECK 4TH DECK 3RD DECK THE MEASUR- ING POINTS OPTIMUM 2ND DECK 1ST DECK HEIGHT OF SHAFT iNvENToRs. No: ohru 00 Sa'l'ctu r' N s n u r4 MJz 0 Kowafs n Q5, Mm 4A0! M A-aer5 Nov. 14, 1972 NAOTERU ODA ET AL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLAST FURNACE Filed May 12, 1971 8 Sheets-Sheet 2 5 0 4TH DECK B o 3RD DECK o 2ND DECK w 5 8 o g .0 8 w 0 2| O 8 n m 0.6 0.7 0.8 Q9 L0 L2 L4 TOTAL THICKNESS (I WALL (m) 3 WM awn AcgNfS Nov. 14, 1972 NAOTERU ODA ETAL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLAST FURNACE Filed May 12, 1971 8 Sheets-Sheet 4.

NORTH d 20- a M 1 O L FIG. 3C 20 EAST o O- m L SOUTH 9 L 20 WEST U) 0 A W T|ME (Hr) FIG. 30

50mm BORNE souwo LEVEL 7* -TIME (day) INVENTOR fiqo'fli'u OJQ su' l 1' .M'shimur Ilia/10 kbma'l'su Nov. 14, 1972 NAOTERU ODA ETAL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLAST FURNACE Filed Bay 12, 1971 6 Sheets-Sheet 6 F/g. 3E

\NVENTORS. A/aa1crm OJQ 1; M'shi ra Ih'aho Komanad 3 We! Md Acewr;

Nov. 14, 1972 NAOTERU ODA ETAL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLAST FURNACE Filed May 12, 1971 8 Sheets-Sheet 6 ,0 3RD DECK,NORTH J 3RD DECK. EAST LU IO- l O O -|0 3RD DECK,SOUTH E ZOWC O an O 3 o O 3RD DECK, WEST HANGING VERY W BAD e000 2v, WM M Ana-N AGENTS Nov. 14, 1972 NAOTERU ODA ETAL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CQRDITIQNS OF BLAST FURNACE Filed May 12, 1971 8 Sheets-Sheet 7 4TH U'ICK, NQRTH IO- M A m 4TH DECK.EAST uJ IO- 0 Z 5 --IO M 4TH IECK. SOUTH E M O [D o.

4TH DECK. WEST 20- lO-W HANGING- VERYBAD- BAD GOOD l 1 --TlME(Hr) INVENTOR5: Naofcru Ody, Scfiehi Nr shlmurq Hie/co Komafsu AGENT;

Nov. 14, 1972 NAOTERU 00 ET AL 3,702,694

METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLAST FURNACE Filed May 12. 1971 8 Sheets-Sheet a |NVENTOR55 Nag hr-h Od S il'zhf N JII M um H e co Kama H mam Md 8 1 mwh United States Patent 3,702,694 METHOD AND APPARATUS FOR JUDGING THE CONDITIONS OF BLASI FURNACE Naoteru Oda, Kobe, Seiichi Nishimura, Takatsuki, and I-Iideo Komatsu, Suita, Japan, assignors to Sumitomo Metal Industries, Ltd., Osaka, Japan Filed May 12, 1971, Ser. No. 142,605 Claims priority, application Japan, May 20, 1970, 45/ 43,510 Int. Cl. C21b 7/24 US. Cl. 266-27 6 Claims ABSTRACT OF THE DISCLOSURE Among the solid borne sounds generated by the mantle of the blast furnace in operation, the magnitude of the level of the solid borne sounds within a specific frequency band is correlated with the conditions of the blast furnace, for example, slipping, hanging or falling of the hanging. A detector detects solid borne sounds from the mantle of the blast furnace, at band pass filter circuit selects the solid borne sounds within the specific frequency band, and an integration circuit produces signals expressing the mean intensity level of the selected solid borne sounds. Through the signals the condition of the blast furnace is judged.

The present invention relates to the method and apparatus for judging the conditions of the blast furnace by detecting the solid borne sounds generated in the mantle of the furnace during operation.

It has always been desirable to examine directly the conditions in the inside of the blast furnace during op eration. This has not been accomplished owing to the high temperature and to the vastness of the capacity of the furnace, with the only exception being that a sounding rod is used for judging the conditions of the furnace indirectly and intermittently. In this conventional method, a rod is lowered from the top of the furnace until it reaches the top of the burden (charged materials), then the reading of the rod, expressing the fall of the stock level within the furnace, is visually observed or recorded by remote control to thereby estimate the conditions of the furnace intermittently. Although the conventional method is effective in estimation of the overall hanging wherein the level fall of the burden completely stops, it has such disadvantages that it is not always effective in estimation of the creation and the growing stage of local hangings, which is particularly important in operation, and that the sounding rod must be drawn up each time when ores and coke are charged and again lowered after the ores and coke are charged.

The conditions of the furnace can be estimated to some extent only by fluctuations of the discharge and the hot air pressure. However, the measured values of these factors are related to the resistance of the entire blast furnace. Therefore, it is difiicult to detect the growth of the local hangings by the measurement of such factors.

The solid borne sounds of the mantle of the blast furnace are produced by mixed propagation of sounds generated by the burdens being disturbed within the furnace and the gases passing through the burdens. And it has been found that a specific solid borne sound contains various information through which change of the condition within the furnace can be estimated. In other words, it has been found that the condition of the blast furnace can be detected by extracting the fluctuation of intensity level of selected solid borne sounds.

A feature of the present invention is that the condition of the blast furnace which is constantly changing with the progress of the furnace operation can be estimated continuously by the changes of reading of the measurement charts.

Another feature of the present invention is that the transition of blast furnace condition can be foreseen by detecting the signals following the changes of the furnace conditions in the neighborhood of the measuring points of the furnace.

Taking advantage of the fact that a component of relatively high frequency among solid borne sounds of the blast furnace mantle faithfully follows the sounds corresponding to the furnace conditions in the neighborhood of the measuring points, the present invention intends to control the furnace with stability and to thereby facilitate production increase and normal operation by providing a plurality of solid borne sound measuring devices around each deck of the furnace, detecting the changes of furnace conditions nearby the measuring points, foreseeing the transitions of the furnace conditions such as hanging, slip, local change of the wall thickness, analyzing them and taking necessary correcting control.

An object of the present invention is to detect changes of conditions at the points within the furnace, to foresee the transition of the entire furnace condition, and to thereby promote the normal operation of the furnace. In the apparatus according to the present invention, a plurality of solid borne sound detectors are mounted at a plurality of specific points on the blast furnace mantle for detecting changes of the furnace wall thickness, changes of the burden and the positions thereof through the magnitude of the level of the sounds in the specific frequency band within an octave above and below 8,000 Hz. at each measuring point and the furnace is controlled through the signals.

In the present invention, a specific frequency band, an octave range from 5,600 Hz. to 11,200 Hz., is selected firstly because the frequency of the sound generated by the hot air blasted into the furnace and passing through the charged materials is around 8,000 Hz. and this is presumed to be the frequency representing the reactions within the furnace, and secondly because the frequency band around 8,000 Hz. is far from the 1,000 Hz. band representing the combustion sounds nearby the tuyere and various mechanical operation sounds and therefore substantially free from noises disturbing the judgment of the condition of the blast furnace.

FIG. 1 is a schematic illustration of the optimum points on the blast furnace mantle for detecting the solid borne sounds, the mantle being shown in elevation and partly in section;

FIG. 2 is a graphical illustration of the correlation between the total thickness of the furnace wall including the deposits and the solid borne sound level;

FIGS. 3(A)-(E) are oscillograms showing changes of the solid borne sound with time in various conditions of the furnace;

FIGS. 4(A) and (B) are graphical illustrations of the corresponding relationship between the solid borne sound level and the condition of the furnace shown in contrast to each other in comparatively long time; and

FIG. 5 is a block diagram of the apparatus according to the present invention.

An embodiment of the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1 shows positions on the mantle where the solid borne sound detectors are to be mounted. The detector is a piezo-electric type pick-up made of, for example, barium or zirconium titanate. It is preferable that four detectors are provided at each height of 2nd through 4th decks around the furnace, one at every in other words, one

each at north, east, south and west of each height around the furnace of 2nd through 4th decks. It should be noted that the detectors will catch noise signals at higher positions, namely close to the stock level of the furnace and at lower positions, namely close to the belly, caused respectively by charging sounds at the top and combusting sounds near the tuyere. The preferable mounting positions of said pick-ups (detectors) are referred to in FIG. 1 as 2nd through 4th decks above. However, since such expression may not give the same definitions of the positions in a furnace of different capacity, type or construction, the optimum detecting positions are shown in Table l with reference to the shaft height (from the belly to the stock line).

TABLE 1 Optimum detecting positions Shaft Height from Capacity height, In. the belly,rn. Shaft ratio A 14.3 s-11.9 1. s/4-3. an 15.3 5-ll. 5 1. 3l-l-314 20. 8 5-12.6 1/4-2.4/

Therefore, the range of the optimum detecting points is from A to A of the height of the furnace, and it is preferable that the lowest limit be set at least 5 meters higher than the belly.

In FIG. 2, the relationship between the solid borne sound level (db), obtained by amplifying the sound signal detected by said solid borne sound detector, passing the amplified sound signal through a band pass filter from 5,600 Hz. to 11,200 Hz. and logarithmically compressing, and the thickness of wall (meter) at each detecting point is plotted. There is a strong positive correlation and rectilinear relation between the absolute values of the solid borne sound level and the total thickness of the Wall including the deposits as shown in FIG. 2. After the correlation between the total wall thickness and the average solid borne sound level is obtained, further variation of the wall thickness can be estimated through it with an accuracy of at least :75 mm.

FIG. 3 shows oscillograms expressing the solid borne sound levels measured at the 4 points: north, east, sound and west around the furnace mantle at the height of the 3rd deck (at the middle of the shaft height, see FIG. 1) under various furnace conditions. FIG. 3(A) shows the condition of normal operation, wherein no noticeable variation is seen at each level and the magnitude at each level directly corresponds to the thickness of the entire furnace wall including the deposits nearby each detecting point. In such a condition, the absolute value of the entire wall thickness can be obtained directly from FIG. 2. The furnace wall is thick in the east to west direction and thin in the north to south direction.

FIG. 3(B) is an oscillogram of the solid borne sound level in the condition that the ball of the burdens within the furnace becomes somewhat discontinuous and the fall is not proceeding uniformly at each loctaion. This phenomenon occurs almost always immediately after the charging. It is very important as a source of information for normal operation of the blast furnace to be able to understand the so-called habit, namely the tendency that the fall of the burdens does not prorceed uniformly at the north, east, south and west of the furnace since this tendency causes unbalance of charging and affects the variation of the wall thickness.

FIG. 3(C) is an example of the oscillogram of the solid borne sound showing the aggravated condition wherein the inside of the furnace has become so unstable that the burdens do not fall down and, accordingly, there is the possibility of slip within the furnace at any moment. This oscillogram shows the occurrernce of a local slip. And when a slip on a large scale occurs, this phenomenon is observed at all the detecting points. And it becomes possible to locate the position of the slip and to foresee it. The condition of the furnace becomes more and more unstable and finally hanging occurs. It is understood that hanging occurs because, in general, hard deposits are formed on the inner surface of the furnace to prevent temporarily the burdens from falling down. Accordingly, it can be said that the wall thickening phenomenon foretells the possibility of hanging. The sudden change of the solid borne sound level as shown in FIG. 3(C) directly indicates the considerable unbalance of the furnace condition. Immediately after the end of this phenomenon, hanging will occur.

Accordingly, as soon as said phenomenon occurs, adequate measures must be taken according to the measured values or engineering judgement of the furnace condition, such as drop of the inner pressure (for example, in high pressure operation the pressure is dropped from 2.5 atmospheric pressure to 1-l.5 A.P., and in low pressure operation from 1.5 to l-0.5 A.P.), reduction of blast and airflow, adjustment of the position or amount of blow-in of hot air and heavy oil, temporary suspension of the blow-in, or change of position or amount of charging by adjusting the rotation of the charging bell to a specific angle, etc.

FIG. 3(D) is an example of the oscillogram showing that the wall thickness nearby the detecting points increases suddenly and that the possibility of occurrence of hanging grows large. This oscillogram shows that this wall thickness occurs toward south and west. Generally, this phenomenon tends to occur continuously for several days before the occurrence of hanging. Therefore, this is an effective source of information in foreseeing the position and the time of the expected occurrence of hanging. This figure faithfully depicts the transition of the blast furnace condition recovering from the hanging wherein in a couple of or several days from the formation of hanging, the hard deposits fell down and then the normal furnace operation was resumed.

FIG. 3(E) is an example of the oscillogram showing the solid borne sound level catching the so-called hanging phenomenon which begins to occur several hours before the actual completion of the hanging. The curves of the oscillogram show that when the hanging phenomenon begins to occur (K at the north portion of the furnace, the deposits on the inner surface of the furnace suddenly grow, and, as a result of the fact that the gas fiow changes at the section and is suddenly reduced, the solid borne sound level of the hanging portion drops, and in the west area, the gas flow begins to increase suddenly (N and the solid borne sound level rises. All of these show that there is a hanging at the northeast area of the furnace. Sharp peaks (K H and N at the right ends of the curves indicate the sound caused by the fall of the hanging, namely the sudden elimination of the hanging.

This indication is very important also in foreseeing whether a new hanging is being formed in the furnace immediately after the fall of the former hanging or if the normal condition is completely resumed in the furnace operation.

From the analysis of these oscillograms, it is understood that it is possible in the method of the present invention to detect the occurrence of slip and hanging sooner and provide practical means for stabilizing the furnace operation better than in the conventional method utilizing, for example, sounding rods.

In FIGS. 4(A) and (B), the values of the solid borne sound level measured continuously for several days at eight points selected at north, east, south and west around the furnace at the height of the 3rd 4 of the shaft height) and the 4th of the shaft height) decks respectively are plotted in correspondence to the furnace conditions. As marked along the ordinate of the graphs shown at the bottom of FIG. 4(A) and FIG. 4(B), the furnace condition is classified into four categories, namely, good, bad, very bad and hanging which are judged by the readings of the sounding gages (sounding rods) applied at two positions and are shown in the graph in comparison to the curves measured by the method of the present invention, wherein the terms are defined as follows:

"hanging represents a condition wherein the readings of the both sounding gages applied at the two positions do not change;

very bad" represents a condition wherein the readings of the both sounding gages at the two positions do not change at all or change suddenly and the level of the burden drops suddenly also;

"bad" represents a condition wherein one of the readings of the sounding gages is similar to those in very bad above and the other shows smooth fall; and

"good" represents a condition wherein both of the readings of the sounding gages show relatively smooth fall and the level of the burden also drops smoothly.

The average level of the solid borne sound measured over a long time is expressed by a chain line in each diagram. From the comparison between the curves and the average level line, it is understood that, both at the 3rd and 4th decks, the solid borne sound level changes as much as :15 db before and after the hanging, in other words, the magnitude of the solid borne sound changes in the range of more than :5 times of the average level.

The average level is low at the north and east sides both at 3rd and 4th decks. This fact foretells that the furnace wall is thick on these sides and the possibility of hanging is great in these areas. The hanging begins to occur at the time t1 and last for about hours. In this case, 6-7 hours before the time :1, a sudden change of the solid borne sound level is observed in the southwest area which is followed by a slip and it seems that the average level is restored once. In fact, however, the furnace condition becomes worse. The solid borne sound level drops in the northeast area at 4th deck which shows that a hanging is formed at that area. If various countermeasures as described above are taken before the formation of the hanging, it would be possible to prevent the hanging.

FIG. 5 shows a block diagram of a continuous detecting apparatus to be mounted on the mantle of a blast furnace for measuring the solid borne sound level of the mantle. As described above, for example, a plurality of bariumor zirconium titanate pick-ups 1 are firmly fixed on the mantle by means of bolt welding or tap screws at more than 4 positions along the circumference of the mantle at the height of about A-% from the bottom of the shaft length of the furnace, in other words, the belly. If a bolt of 20 mm. in diameter and 200 mm. in length is used and the pick-up is attached at the lending end of the bolt, the temperature of the pick-up can be maintained under 70 C. by the cooling effect and, therefore, no further attention is needed to cooling.

It is preferable that pre-amplifiers 2 be provided as near as possible to the pick-ups. Outputs of these amplifiers are switched in turn by switch 3 for switching sequentially the pick-ups disposed at each measuring point, supplied to the main amplifier 4, passed through the 5,600 Hz.-1l,200 Hz. high frequency band pass filter 5, amplified by the amplifier 6, rectified by the rectifier 7, and converted into the D.C. output by the D.C. amplifier 8 for driving the servo motor M so as to drive the servo motor M through the switch 3' interlocked with the switch 3. The servo motor has a three-staged tandem potentiometer for interlinking so as to keep the output amplitude at zero and for mechanically rotating the potentiometer 9-1, 9-2 and 9-3. The circuit within the chain line comprising 6, 7, 8 and the servo motors M above is a logarithmic compression circuit according to the servo mechanism system.

Output of the potentiometer 9-2 is supplied to the integrator 20 where the input of the varying solid borne sound level is integrated by time and the average value of it is recorded in the recorder 13. The integrator 20 used here is a variable integrator capable of setting any integrating time ranging from the order of several seconds to that of several minutes.

Output of the logarithmic compression circuit, namely the voltage representing the varying solid borne sound level, is applied to the inputs of the floating pen 31 and the integrator 10. To the setting arm 32 of the potentiometer 9-3 is applied a voltage from the setter 17 representing the predetermined level of the solid borne sound. In the potentiometer 9-3, accordingly, the signal expressing the deviation between the set value from the setter 17 and the variable value provided by the floating pen 31 moved by the servo motor M is applied to the integrator 10.

As described above, the negative deviation signal indicates particularly the aggravating tendency of the furnace condition such as hanging. On the other hand, since the positive deviation signal has no direct relation to such aggravating tendency of the furnace condition, the sign of the negative deviation signal is reversed in the integrator 10 and amplified by multiplying by such a coefiicient as, for example, 3-5 while the positive deviation signal is manipulated so as to be weakened to facilitate the judgement of the furnace condition.

The adder 11 accepts successively the integrated inputs from the measuring points (only four points are shown in FIG. 4 but generally more than 10 points are used in actual operation) switched one by one, sums them up and feeds them to the memory circuit 12 of pulse system. This memory circuit 12 is provided for storing the outputs of the adder l1 enlarging the integration time by the number of the memory elements disposed in parallel and is constructed so as to accept new signals one by one, to shift the signals from left to right by one position at each acceptance of a new signal and to eliminate the oldest signal one by one. The signals presently stored in the memory circuit 12 are all added in series by the adder l3, matched against the predetermined value in the indicator 15. And when the output of a signal exceeds the predetermined output value, an alarm signal is supplied by the output terminal 16.

Output of each integrator 10 is applied to each indicator 18 and the absolute value of the average level of the solid borne sounds is indicated. It is possible that the outputs be indicated by the indicator 18 as the absolute value of db, or when it is necessary, as the absolute value of the wall thickness. Alternatively, when the output of each measuring point is introduced to an adequate calculating unit, the output may be expressed as an information signal from the terminal 14 and supplied as an absolute output of the solid borne sound level or a control signal.

As described above in detail, by measuring the solid borne sound at a plurality of appropriate points on the mantle of the blast furnace and observing the values measured continuously for a long time, accurate information on various furnace conditions, such as wall thickness, slip, hanging and fall of the hanging, can be obtained successively, and by analyzing such information future furnace conditions can be foreseen and the blast furnace can be correctively controlled at relatively low cost. Consequently, the present invention provides the optimum method and apparatus for judging the blast furnace condition by using the information explained above as the source of control command for the normal operation of the furnace.

We claim:

1. A method of judging the condition of a blast furnace which comprises:

(a) sensing the level of solid borne sound at a plurality of points in the mantle of said blast furnace;

(b) generating signals in response to the sensed levels at the respective points; and

(c) displaying indicia representative of said signals as an indication of the thickness of the furnace wall at said points.

2. A method as set forth in claim 1, wherein said points are distributed about the circumference of said mantle at each of a plurality of levels, said levels being located between A and of the shaft height of the blast furnace.

3. A method as set forth in claim 2, wherein said signals are generated in response to the level of sound in a frequency band between 5,600 Hz. and 11,200 Hz.

4. A method as set forth in claim 1, wherein an alarm signal is generated when the thickness of the furnace wall at one of said points, as indicated by said indicia, differs from a predetermined value.

5. An apparatus for judging the condition of a blast furnace comprising:

(a) sensing means mounted on the mantle of said furmate for sensing the level of solid borne sound at a plurality of spaced points of said mantle;

(b) signal generating means for generating respective signals in response to the sound levels at said points; and

8 (c) display means connected to said signal generating means for displaying indicia in response to the generated signals.

6. An apparatus as set forth in claim 5, further comprising filter means interposed between said signal generating means and said display means for limiting display to signals generated in response to sound in a selected frequency hand between 5,600 Hz. and 11,200 Hz.

References Cited UNITED STATES PATENTS 3,078,707 2/1963 Weaver 26625 GERALD A. DOST, Primary Examiner U.S. Cl. X.R. 2662$