JPS6021310A - Method for estimating distribution of charge layer in blast furnace - Google Patents

Abstract

PURPOSE:To improve the accuracy in estimating the thickness distribution of the charger layer in a furnace with a less number of measurement with a profile memter by making use of the depth (index) obtd. by detecting approximately continuously the descending condition at one point on the surface of the charge in the furnace near the wall of the furnace top separately from the depth measured with a top profile meter. CONSTITUTION:The calculation depth YCn.i of the charge corresponding to the depth at the i-th point of the optional n-th batch by a furnace top profile meter S is calculated by the equation and the calculation is seccessively repeated, by which the profiles on the surface and bottom surface of the charge are determined. The average layer thickness distribution at every charging is then estimated. In the equation, a-d: constants, xn.i: the coordinate in the radial direction in the furnace, Zn: the sliding amt. to be determined with each charge, k: the constant of a descending speed distribution, R0: the radius of the furnace port, Rs: the radial distance from the furnace wall to the measuring point with the meter S, DELTASn.i: the index descending amt. of sounding at one point from the stage of charging up until measurement.

Description

[Detailed Description of the Invention] Technical Field The technical content described in this MeiMB book regarding the method for estimating the layer thickness distribution of blast furnace charge is to estimate the layer thickness distribution, which does not extend to the gas distribution in the furnace but has a close correlation. In relation to the development results aimed at stabilizing blast furnace operations and extending the life of the furnace through the management of furnace heat loads, the technology to which blast furnace operation control belongs will be reviewed. Located in the field.

Regarding the technical back-splitting charge distribution In general, during blast furnace operation, the distribution of the blast furnace charge at the top of the furnace is influenced by a complex interplay of various factors, but the main factors are as follows. 11) Physical properties of the charge - density per grain Jy, coefficient of internal friction, etc. 2) Charge charging speed 8) Charging conditions - coke base, ore/yoke.

Stock line 4) Fall trajectory of charging flow - notch position of movable armor in bell blast furnace, bevel around 1 of distribution chute in bellless blast furnace 5) Charging sequence - charging time schedule 6) Inside the furnace Gas Flow When the blast furnace charge is charged into the furnace through the charging device at the top of the furnace, the distribution of the blast furnace charge in the furnace is determined by the effects of each of the above factors.

The most important point in reducing the fuel ratio and stabilizing operation is the layer thickness distribution of the blast furnace charge in the radial direction within the furnace (hereinafter simply referred to as charge layer thickness distribution).

This thickness distribution of the charge layer is extremely important in blast furnace operation because it is closely linked to the gas distribution in the furnace.
Great efforts have been made to control this.

This gas distribution needs to be managed to satisfy the tentative requirements from both the operational and equipment aspects regarding the following points.

1) Reducing the fuel ratio by improving the gas utilization rate 2) Stable operation based on smooth unloading 3) Extending the life of the furnace body by managing the heat load on the furnace body In order to improve the gas utilization rate and obtain stable unloading On the other hand, in order to reduce the heat load on the furnace body, a gas distribution oriented toward the center flow is required.
The charge and layer thickness distributions are controlled with the aim of achieving a gas distribution that satisfies both of these requirements.

Control operations for the charge layer thickness distribution Now, methods for controlling the charge layer thickness distribution include 1) changing the charge 2) changing the coke base, sinter ratio, and pellet ratio 8) changing the charging method 4) These include stock lines, charging sequences, movable armor notches in bell blast furnaces, or distribution chute inclination angles in bellless blast furnaces.

Among these, the most common changes to the charging method are by adjusting the moorable 7-meter in a pellet blast furnace and by adjusting the distribution chute in a bellless blast furnace. This method attempts to change the layer thickness distribution of the charge 11 and, as a result, to help the gas distribution in the furnace meet the target.

The gas distribution can be measured using a shaft sonde (used for component analysis of the gas sampled at each position in the radial direction) and a fixed sonde at the furnace mouth (used to measure gas temperature at several points in the radial direction). is common.

However, the quantitative relationship between the control amount of the movable armor and the distribution chute on the gas distribution obtained by these sonde measurements is still not fully understood, and it is unavoidable to rely on the above gas distribution information. Based on this, the charge layer thickness distribution is controlled by trial and error, in which the movable armor or the distribution chute is changed, and further changes are considered depending on the subsequent change trend in the gas distribution. Even if such a charging method is changed, the expected gas distribution does not easily match, and the current situation is that adjustment over a long period of time is required to obtain the target gas distribution.

Of course, in order to quantitatively understand the relationship between charge layer thickness distribution and gas distribution and to improve charge control technology,
It is essential to more accurately understand the condition of the charge in the furnace. A furnace top profile meter has been developed.

These sensors are contact (mechanical) and non-contact (μ
Next, we will explain the problems using the top profile meter of Sounding 2, which uses a contact type measuring weight, as a representative example. It is also common to the model.

Regarding the example of sounding, Fig. 1 shows a sounding-type furnace top profile meter 8 using measuring weights. The device, 8 is a measuring weight, 4 is a wire rope for raising and lowering the measuring weight, 5 and 5' are guide sheaves, 6 is a movable pulley with the wire rope device 4 fixed in the lance 1, and 7 is a wire rope for raising and lowering the measuring weight. A fixed skid is attached to the rear end of the lance l, 9 is an operating rope wrapped around both pulleys, 10 is its fixed end, 1
1 is the winding trunk of the operating rope, ■2 is the guide sheep,
18 is a tension detection lever for the operating rope 9, and 14 is a counter spring.

By rotating the chain mechanism 2, the °C lance 1 is advanced toward the furnace core from the opening 15' in the top furnace wall 15 of the blast furnace through a seal (not shown for simplicity).
can move forward with the lance 1 and send the lance 1 to a crazy radial position. At this time, the measuring weight 3
is slightly lifted.

When the operating rope 9 is loosened by the winding drum 11 at this position, for example, the solid line position in the figure, and the measuring weight 3 is lowered,
When the measuring weight 8 reaches the surface of the non-entered object 16, the tension of the operating rope 9 decreases rapidly, and the counter spring 14
．． Since the tension detection lever tg rotates, landing on the floor can be detected.

Therefore, the coordinates of the measurement point can be expressed by the progress X of the lance l in the radial direction within the furnace and the depth y of the measuring weight 8 at this time.

After this detection of landing, the lance l is further advanced at predetermined distances as shown by the broken line, and the next depth is measured along with the progress. By repeating this operation, the actual measurement points on the surface of the charge 16 in the radial direction of the furnace (for example, 1 per cycle of each charging batch
0 points) will be obtained.

Each measurement data consists of the measurement time of the j-th fish in the charging batch, the radial advance and depth for each measurement point, and is exactly the same for this roe contact type furnace top profile meter.

By the way, the layer thickness of the charge is determined by the distribution 9 of the ratio of the layer thickness of ore and coke formed as a result of charging the charge into the furnace.
according to particle size distribution and mixed layer distribution of ore and coke.

As shown in FIG. 2, for example, in a bell-type blast furnace, a raw material 16' falls into the furnace from a large bell 17, and follows an inclination angle determined by the characteristic values (particle size, shape, etc.) of the raw material.
“It accumulates like this.

After this accumulation progresses and the amount of accumulation reaches the accumulation limit,
The deposit 16'' flows toward the center of the furnace, and at the end of charging, the charging profile of the charge 16 is formed as shown by the phantom line.

Thereafter, redistribution of the charge 16 may occur due to changes in the gas flow during the entire descent of the charge 16, such as inflow due to fluctuations in the stable inclination angle of the charge 16.

Prior art and its problems Conventional control of the charge layer thickness distribution involves, in the illustrated example, moving a movable armor (hereinafter abbreviated as HA) 18 back and forth to control the falling position 1i'+ of the raw material 16' into the furnace. This is done by changing the distribution state, mainly the radial distribution of the ratio of ore to coke (hereinafter referred to as 0/Q), by changing the deposition state.

Therefore, in order to control the charge distribution from MA 1.8 K, J, HA thickness and the resulting 0//c! It is necessary to know the distribution.

This charge layer thickness distribution has conventionally been determined by calculation using a furnace top profile meter such as a lifter according to the procedure described below.

As shown in Figure 11m8 (a), each time the raw material 16' is charged from the large bell 17, the furnace top profile meter first calculates the charge at the charging end time Tn, l for that batch (referred to as the nth batch). The radial profile Pn, 1 of the charge and then the surface profile Pn, 2 of the charge at a time Tn, 2 immediately before the (n+z)th batch charging thereafter are measured. .

And over the radial direction of the furnace, from time −□ to Tn, 2
Calculate the average rate of descent vn over time leading to .

(2) 4J As shown in Figure 8 (b), the (n+x)th batch charging end time T (n + □) and the surface profile P (n + □) 9 at □ are measured using a furnace top profile meter, and at the same time, At time T(n+□), □, the time of the previous nth batch "n, 1" T(n+x), □
The surface profile ps descends over time up to ps
, □ are extrapolated using the above-mentioned average descent speed V 2 to obtain an estimated profile.

(8) The measured surface profile of the (n+1)th batch at time T(n+□), □ is ``(n+□)5, and the estimated profile Psn2 of the nth batch, i.e., i(n+
i) From the bottom profile of the th batch, i(n+i)
Calculate the layer thickness of the second patch.

In this way, the furnace top profile meter was used to perform 8 measurement operations [2 times for the nth batch, 1 time for the (n+1)th batch]
Although the layer thickness of the (n+x)th batch is calculated as follows, such an O/Q estimation method has the following problems.

Pointing out the problem The charge surface profile obtained by measurement using a furnace top profile meter has a very large variation according to the experience of actual operation.As a result, the layer thickness distribution estimated by this method also has a large variation. The estimation accuracy of layer thickness distribution is poor.

Therefore, in order to use the charge layer thickness distribution estimated by such a method as an ITJ control guideline for the charge distribution, it is necessary to improve the estimation accuracy.

To do this, considering the above-mentioned dispersion, it is necessary to carry out the 1411 determination on several dozen charges, but this is currently difficult considering the durability of the profile meter and the cost required for its measurement. The practical upper position is σ.

Regarding the basic idea and the problems beyond the purpose of the invention, the inventors have come up with the idea that the number of measurements made by the furnace top profile meter can be reduced by effectively and advanced use of index information as described below. It is an object of the present invention to improve the estimation accuracy of thickness distribution.

The index finger is the depth obtained by almost continuously detecting the descent condition at one point on the surface of the furnace contents 16 in the vicinity of the top furnace wall 15 of the blast furnace, separately from the furnace top profile meter S. It is.

Structure of the Invention The above object is achieved by a procedure mainly consisting of the following matters.

Charge calculation depth YOn, 1 corresponding to the depth of the first point of any n-th batch by the blast furnace charge top profile meter
is calculated using the following formula, and by repeating this calculation 11μ times, the surface profile of the charge and the bottom surface profile of the charge are determined, and - the average layer thickness distribution for each charge is calculated. A method for estimating blast furnace charge layer thickness distribution.

YCnl, = (axn2, +bxnl□+cx1□1
, 10d) 10zna, b, c, d: Constant, Xn1,: 4 radial seats in the furnace, Z9: Slide width determined for each charging, k: descending speed distribution constant, Ro = furnace mouth radius, R8: Radial distance from the furnace wall to the furnace top profile meter measurement point, Δ
Sn. In addition to the surface profile, a correct detection of the descent velocity distribution is required for estimating the underside profile of the charge.

When estimating the descending velocity distribution for the surface profile of each batch, we focused on using index information that constantly measures the descending state of the charge for each batch.

As shown in FIG. 2 again, the depth at a single point as index finger information is determined by placing the test weight 20 attached to the tip of the wire 19 that moves up and down on the surface of the charge 16 using the winding and unwinding device. This can be obtained by following the descent of the object 16 and detecting its situation.

Here, when the raw material 16' on the large bell 17 is charged into the furnace, detection can be continued at all times except for retracting the measuring weight 20 from the burial, so the furnace top profile meter is used as the basis of the blast furnace raw material charging schedule. The measurement data is much more abundant than that of the conventional method.

In FIG. 2, 21 is a winding and unwinding drum, 22 is a counterweight, and 28 is a drive device with a reduction gear and a brake.

Regarding the descending velocity distribution, as a result of examining the relationship between the index descending amount and the descending it at each point in the radial direction obtained by the furnace top profile meter, it was found that the descending velocity distribution of the charge can be determined by using the radial distance of the blast furnace as a parameter. It was confirmed that it can be treated as a linear approximation of the descending speed.

Therefore, we investigated a charge distribution model using index finger information from single-point saunsing and measurement data from a profile meter. The charge distribution model is created based on the actual measurement data of the charge surface profile using a profile meter and the index finger data of the measurement batch.

This model follows the following assumptions.

(1) First, we consider that there is a profile of the charge that is uniquely determined by the type of charge (ore or coke) and its HA position, with a typical example of a bell blast furnace. The profile is considered to be this standard profile that is successively slid downward in the depth direction by an amount determined for each charge (hereinafter this mouse will be referred to as slide b zn).

Total JI depth YCn,i of the charge corresponding to the first black mark of the furnace top profile meter S for the charge of the current n-th batch
is expressed as follows using the depth YSn,i obtained from the target profile, the slide view zn, and the descending speed distribution ΔYn,i corrected for the time from loading to measurement.

YCn, i −YSn,, +zn+ΔYn, i'・
・・・・・・・・・(1)(2) Next, the descending velocity distribution of the charge is determined by the distance 11J [l1Xn, ,
It is approximated by the linear expression of

k: descending rate distribution constant, R: furnace mouth radius, xn, i' radial coordinate in the furnace, R8: radial distance from the furnace wall to the furnace top profile meter measurement point, ΔSn, □: from the time of charging to the time of measurement Difference descent amount of one point sinking Based on these two assumptions, calculate the depth of the charge corresponding to each defined time of the furnace top profile meter, and calculate the calculated depth that best matches the actual value measured by the profile meter. Once the standard profile and descent rate distribution constants are obtained to match, the layer thickness distribution of the charge can be calculated using only index information from single-point scanning that is constantly measured.

Here, first, the standard profile YSn,i determined by the type of charge and the MA position is approximated by an 8th order equation of the distance xn, □ from the furnace wall, for example, as shown in the following equation.

However, f: the furnace wall is taken as 0, and the distance from it in the direction of the furnace core is taken as positive; Y: Y=0 at X-0, and the distance vertically downward from it is taken as positive.

YSn, 1-aXn, i, +bXn,
1 + CXn, , + d”...(8)a
, b, c, d: constants (21, (Substituting the formula 81 into the formula (i1), the calculated depth of the charge corresponding to the first iris of the n-th batch YCn, □
becomes as follows.

Y(:jn, 1 = (a Xn, 1 +bXn
, i + CXn9, +d) +Z.

By the way, if the y-coordinate of the actual measurement point of the furnace top profile meter S for the first black of the Mnth batch of charging is YRn, , then the sum of squares E of the error with the above calculated value YOn, , is expressed by the following formula. It will be done.

-E=FLf (yRn + l -YCn*i
)2...(5) Constant terms a, b, c,' of the standard profile are set so that the sum of squares E of this error is minimized.
(1. Determine the slide amount Zn (n=17-n) and the descending rate constant k.

After determining the constant term in this way, the depth according to the standard profile, 2 YSn, i=”n, i +bXn, i jCxn, i+
The layer thickness distribution is estimated using d and the descent rate distribution constant k.

In order to calculate the layer thickness of the charge, it is necessary to estimate the profile of the surface and bottom surface of the charge, and by the following procedure, the layer thickness distribution of T = T6n is calculated at the time of charging the nth batch. The case of estimating ℃ will be explained according to FIGS. 4 and 5.

(A) KS Estimation of the bottom surface profile of the n-th batch charge (11 First, the (n-1
) for the th batch at time T as shown in Figure 4 (al).
The depth YC(n-□)9, given by the profile at the time of charging the (nz)th batch in s(n-1), is
It is calculated from YS (n-1), i according to its standard profile and the slide fl Z determined for each charge.

(2) As shown in FIG. 5, the index finger of the nth batch between the time of charging the i (n-1)th batch and the time of charging the anth batch, that is, from time T8 (n-□) T8
The amount of sounding drop ΔS over time until reaching nVc is taken as the index finger.

(3) Descending speed distribution constant and Zauning descent amount ΔS
Calculate the amount of descent at each point using

(4) Depth YS(n-□)2 according to a semi-profile,
+tX The descent profile of the m(nz)th batch, which is the profile of the bottom surface of the charge of the nth batch, is estimated from the amount of descent at each point (FIG. 4(b)).

(Bl Estimated time TK Ogero 74 of the surface profile of the charge of the n-th batch The profile n of the n-th batch is determined by one of the following methods using the depth YS according to the standard profile n,1.

[l] Use the sliding amount at the time of charging (Fig. 6 (a)
)).

[2] Descent profile of the (n-1)th batch and in
Using the standard profile of the second batch, the amount of sliding is calculated back so that the calculated layer volume is equal to the volume of the charge (actual value) (rSO diagram (b)).

By performing calculations (A) and (B) for each batch, the average layer thickness of coke and ore is calculated.

Example 6000 The results of the average layer thickness distribution according to the present invention obtained through experiments conducted in a blast furnace having a capacity of t/d are shown in FIG.

The layer thickness of ore is maximum at the furnace wall and decreases toward the furnace core, while the opposite trend was observed in the case of coke, but these layer thicknesses are almost consistent with conventional knowledge, and this It can be seen that the method for estimating layer thickness is appropriate.

Next, from measurement Al (solid line) to measurement A2 (dashed line), the movable
This corresponds to the time when the action of pushing the armor was added.

This shows that the average layer thickness of ore increases at the periphery and decreases at the core.

Effects of the Invention As described above, the effective use of index information according to the present invention results in good estimation accuracy of the layer thickness distribution, as shown in the above results, and advantageously contributes to stable operation of the blast furnace and extension of the life of the furnace body. be able to.

[Brief explanation of drawings]

Figure 1 is an illustration of the furnace top profile meter, l, IN, and
Figure 2 is an explanatory diagram of the procedure for measuring the index finger of the charge, and Figure 8 (a
1, (bl is an explanation of the conventional example of estimating the charge layer thickness distribution using the furnace top profile 6F, and Figures 4 (a) and (b) are the steps for estimating the bottom profile of the charge for the nth batch. FIG. 5 is an explanatory diagram of the measurement procedure for the index finger drop of the nth batch, and FIGS. 6(a) and (b) are explanatory diagrams of the estimation procedure of the surface profile of the in-th patch charge. , Figure 7 is a graph showing a specific example of the layer thickness distribution of ore and coke. Patent applicant Kawasaki Steel Corporation (a) Figure 3 , b) Figure 5 Rule l) Th. 'Tsuchi□a Suni 1 Kino

Claims (1)

[Claims] L Charge calculation depth YCn corresponding to the depth of the first point of any n-th batch measured by the top profile meter of the blast furnace charge
. A method for estimating the thickness distribution of blast furnace charge using the estimation of %. Note YCn2, = (axn+i8+bxn1,” 7)-
cx,, +d) +zna, b, c, d: Constant xn, i 'Radial coordinate in the furnace zn: Slide' amount determined for each charge k: Descending rate distribution constant Ro: Furnace mouth radius R6: From the furnace wall Radial distance to the furnace top profile meter measurement point ΔSn, i ' Amount of drop in the index finger of one-point sinking from charging to measurement