JPS60113156A - Method for measuring deviation in circumferential direction of dropping speed of material loaded into shaft furnace - Google Patents

Abstract

PURPOSE:To detect easily and surely the ununiform state in the circumferential direction of the dropping speed of a material loaded to the lower part of a furnace, by measuring the temperature of the front of tuyere. CONSTITUTION:A contactless thermometer 11 which can measure the temperature of the front of plural tuyeres attached in the circumferential direction of a funace body is provided in a viewing window 12 of a bend part of a blast branch pipe 9. Thermometers 11 are provided for all tuyeres or plural tuyeres at intervals of a certain length in the circumferential direction. The temperature of the front of tuyeres measured by these thermometers indicates a value corresponding to the heat incoming and outgoing state of a combustion zone in the front of tuyeres. Though this heat incoming and outgoing state is varied by various factors, it is determined by a ratio O/C of ore raw materials to fuel in the top of the furnace if the other conditions are fixed. Then, the ratio O/C of the material loaded to the shaft furnace is changed by >=10% of normal operation, and dropping of this changed loaded material to the front of tuyeres is detected as a variance of temperature by thermometers for measuring the temperature of the front of tuyeres. The differences between the time of the change of the ratio O/C and the time of the detection of the temperature change in individual tuyeres are compared with one another, and this time difference is obtained as deviation of the dropping speed of the loaded material in the circumferential direction.

Description

[Detailed Description of the Invention] Technical Field - Seal [鈷n) 浔子; Translation 1 甜 1 ADA TO 1 Note: Regarding accurately grasping the circumferential direction deviation of the freezing degree of λ feed IThT. The technical content described in the specification is smooth and stable.
The purpose of this paper is to provide a standard for accurately estimating reaction behavior in a shaft furnace in connection with maintaining the reaction in the furnace.

Technical background In a shaft furnace, for example, a blast furnace, the charges, that is, the raw materials such as ore, sintered ore, and pellets, and the fuel, such as coke feed, are alternately mixed at a certain ratio through an upper bell and a lower bell. At the same time, air is blown from the tuyeres via the annular pipe and the blower branch pipe to burn the coke that has descended to the point where it is present, and to raise the temperature of the descending raw material by the high-temperature reducing gas produced by combustion. , reduce and melt.

Figure 1 shows a vertical cross section of a blast furnace. In the figure, 1 is the iron shell, 2 is the lining refractory, 3 is the tuyere, 4 is the small bell, 5 is the large bell, 6 is the coke, and 7 is the ore (burnt ore). 8 is annular; 19 is a blowing branch pipe; and 1O is a taphole.

At this time, in order to stabilize the operation of the blast furnace, that is, to stabilize the various components of the molten product over time, it is important for K to have uniformity of reaction in the circumferential direction of the blast furnace.

To ensure such uniformity, O/C in the circumferential direction is
uniformity of air flow, uniformity of air flow rate, and uniformity of descending speed of the charge.

If these uniformities are disturbed, the temperature of the charge in the furnace increases,
The reduction and melting rates will be non-uniform, e.g. in Figure 2 (
As shown in (a), the temperature difference (T
Air T+n1n) increases, and the number of slips increases accordingly, resulting in 81
% fluctuation becomes large.

Disturbances in uniformity lead to unstable operating conditions and large fluctuations in the composition of the molten product.

Slip is a phenomenon in which the descending of the charge stops from the upper part of the morning glory of the blast furnace to the middle of the shaft, making it difficult for the gas to rise and increasing the wind pressure.
This is a phenomenon that starts to fall due to some reason, and an increase in shelf suspension → slip makes the operation of the blast furnace unstable.

In order to correct such unstable behavior, it is necessary to detect as early as possible the progress of non-uniform reaction in the circumferential direction of the blast furnace, and take measures such as reducing the amount of air flow and reducing the percentage of the blast furnace. It is necessary to carry out operations to correct the causes of such problems, such as non-uniform circumference, non-uniform air flow, non-uniform growth of substances deposited on the furnace wall, etc.

Purpose of the Invention A method for early detection of circumferential non-uniformity in the inside of a furnace, in particular a method for easily and reliably detecting circumferential non-uniformity in the rate of descent of the charge in the lower part of the furnace, which directly affects the variation in pig iron composition. It is an object of this invention to provide the following.

Structure of the Invention The above object can be advantageously achieved by a procedure consisting of the following points.

Ratio of ore raw material and fuel in shaft furnace charge 0//C
is changed by 10% or more of normal operation, and then the temperature in the combustion zone before the tuyere, the brightness, or the embedded temperature at the tip of the tuyere are continuously measured at multiple blast tuyeres, and the above ratio % is determined. It is detected by the change in the measured value that the changed charge is coming down just before the change, and the difference between the time when the ratio % is changed and the above detection time is compared for each tuyere, and this difference is used to determine the circumference. A method for measuring the circumferential deviation of the charge-falling rate in a shaft furnace, which consists in determining the deviation of the charge-falling rate in the direction.

Now, FIG. 8 shows a cross section of the main part of the blast furnace including the tuyere 3.

Normally, a plurality of tuyeres 8 are installed in the circumferential direction of the furnace body, and the combustion zone inside the furnace has a so-called raceway temperature (
A non-contact thermometer 11 for measuring the tuyere temperature (hereinafter simply referred to as the temperature before the tuyere) is inserted into the peephole 12 at the bend of the blower branch pipe 9.
to be installed.

This thermometer 11 can be installed for each tuyere, but sometimes it is sufficient to install it for multiple tuyeres spaced apart in the circumferential direction. The pre-tuyere temperature measured by the meter corresponds to the heat balance state in the combustion zone immediately before the tuyere. 13 in the figure is a thermometer 11
The support leg 14 is a siding cooling box.

Now, the heat balance state of the combustion zone changes depending on various factors, but if other conditions are constant, it is first determined by the percentage of charge at the top of the furnace.

Figure 4 shows an example of the change in the temperature before the tuyere over time when O is changed, and also shows the width of the change in the temperature before the tuyere, which reflects the change in the temperature and the corresponding heat balance state in the combustion zone. The relationship is shown in FIG.

From FIG. 4, even when O/c is constant, a fairly large change in the immediate temperature is observed, and this is thought to be due to intermittent changes in the rate of descent of the charge.

However, as shown in Figure 5, when ``/Ck'' is changed by 10% or more, the change in the temperature before the tuyere is clearly distinguishable from the intermittent change in the rate of descent of the burden and can be detected. I found out.

Here, the lag time in the change timing of 0/C (the time when the immediate temperature changes from the charging of the charge to the top of the furnace) indicates the lag in the residence time of coke in the furnace.

Although not shown, the means for measuring the temperature at the front end may be a luminance measuring device, or a device for measuring the temperature at the end point, instead of the temperature meter shown in FIG. 8.
Even if a thermometer 15 embedded in the tip of the tuyere 8 as shown in the figure was used, almost the same detection results could be obtained.

Now, let's look at an example of the relationship between the charge descending speed deviation and the hot metal composition fluctuation in the circumferential pressure for four tuyeres located in four directions, north, south, east, west, and with capacity lo, ooo t/B, out of 88 tuyeres. The details are as follows.

FIG. 7 shows the transition of the temperature in front of the tuyere in four circumferential directions (E, S, W, N) when O/C was reduced by about 15% from 8.75 to 3.19. Differences can be seen in the timing at which the temperature in front of the tuyere starts to rise due to the decrease in 0/c, and it can be seen that the temperature starts to rise in the order of S, E, and WXN.

To calculate the difference between the time of change of each tuyere temperature and the time of change of each tuyere temperature from the time of % change, that is, the residence time of the charge in the furnace in each measurement direction, the correlation coefficient between the temperature outside of 0 and the tuyere temperature is expressed as time t , 2t , 8t...
..., shift by 12t.

t is 1 minute to about 10 degrees.

Calculation of the correlation coefficient is performed as follows. First, calculate the average ``/c'' and the temperature in front of the tuyere at an arbitrary position at an appropriate time interval (approximately 1 to 10 minutes).

Let these be X(, ), y(□) 1=1 to N.

Values of X and y with the same 1 are for the same time, and the larger the value of 1, the later the data is.

Using such data (X(□), y(□+n))
Create a set of data and calculate the correlation coefficient for this set.

For example, when the time delay ΔT-00 for data (Xl lyl ) * (X2 + Y2) + (-
XB IY8) ””’(Xl-1+”/1-1),
(xl, y4)...(xn, yn) Also, when time delay ΔT=1, (xl +'Y2)r (X2+yB)+ (XB +
y4) ...'...("1-1 +y4) '...
...(XH-1+'Yn) Using this data combination, r
□Fill in.

Similarly, when ΔT=j, (X1+'Y1+j)+(X2+72+j) ""'
(x11y1+j) -0'' (X, -j+y,) Use this data combination to calculate r3.

Calculate by assuming that ■ is stored for about 20 hours, j is stored for about 7 hours, and the pitch is about IO minutes.

Gradually increase the value of n, plot r and J, and calculate the change in the correlation coefficient. For example, in the case of Figure 8, it is 4.5 H.
With r delay, there is a good correspondence between furnace top% and tuyere front temperature, so 4
．． 5 Hr is obtained as the residence time in the furnace.

FIG. 9 is a plot of the results calculated using the above procedure for four points in the circumferential direction (N, E, SSW). It is clear that the shift time that shows a peak in this figure is the residence time in the furnace, and that by dividing the distance from the charging level to the grain level K, the rate of charge descent can be determined.

A similar measurement was carried out, and the deviation of the descending speed (maximum value - minimum value) determined from this and 81% of the pig iron in each tap for one day before the seventh measurement.
Figure 10 shows the relationship between the standard deviation of

It was found that the deviation of the charge descending speed in the circumferential direction obtained as described above has a good correlation with operational instability.

Effects of the Invention According to the present invention, blast furnace operation is improved by managing the deviation of the charge descending speed in the circumferential direction, and when this deviation tends to increase, an operation is performed to equalize it in the circumferential direction. greatly helps in achieving stabilization.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the blast furnace during operation, Fig. 2 is a graph showing the correspondence between circumferential deviation and operational stability, Fig. 3 is a cross-sectional view of the siding section, and Fig. 4 is an O/C A graph showing an example of the change in tuyere temperature at the time of change. Figure 5 is a graph showing the correspondence between the range of change in Q/c and the range of change in tuyere temperature. Figure 6 is a schematic diagram of a thermometer embedded in the tuyere. In addition, Fig. 7 is a graph showing changes in the temperature in front of the tuyere in four directions around the circumference when changing 0/C, and Figs. 8 and 9 are graphs showing the relationship between the residence time in the furnace and the correlation coefficient. Figure 1O is a graph showing the correspondence between the circumferential descending velocity deviation and the standard deviation of 81% in hot metal. Patent applicant: Kawasaki Steel Corporation Figure 1 Figure 2 (a) (p) (Japanese) Figure 3 Figure 4 1 H but FB'l (8 now) Figure 5 Figure 7 rf, between (fB button ↓ 2 hours)

Claims (1)

[Claims] L The ratio of ore raw material and fuel in the shaft furnace charge is
The above ratio was changed by changing the temperature by 10% or more compared to normal operation, and then continuously measuring the temperature, brightness, or embedded temperature at the tip of the tuyere in front of multiple air tuyeres. Detect the falling object to the front of the tuyere by the change in the measured value, compare the difference between the time when the above ratio '/c was changed and the above detection time, and use this difference to determine the circumference. Method for measuring deviation in circumferential direction of charge descending speed in a shaft furnace characterized by measuring deviation of charge descending speed in the direction 0