JPS63312910A - Method for predicting lowering of furnace heat in blast furnace - Google Patents

Abstract

PURPOSE:To accurately predict lowering of furnace heat by arranging plural thermometers for inner wall in line in the vertical direction from lower part in the blast furnace, measuring differences of the inner wall temps. at the prescribed time intervals and comparing with the presetting value. CONSTITUTION:The thermometers 3 for the inner wall are arranged in line on seven points from a first level 31 to a seventh level 37, from the lower part toward vertical direction in the blast furnace 1 and also on four points in the inner circumferential direction at each level in the blast furnace 1. The differences of the inner wall temps. are measured by these thermometers 3 for the inner wall at the prescribed time intervals. In this constitution, in the case where the positive value of the difference of the inner wall temps. at any level lower than the m-th level (2<=m<=7) exceeds a preset value within the prescribed time after the positive value of the difference of the inner wall temps. at the m-th level exceeds a preset value, it is predicted that the blast furnace heat is lowered. By this method, the lowering of molten pig iron temp. can be accurately predicted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for predicting heat drop in a blast furnace for stable operation of a blast furnace.

(Prior art and its problems) It has been known for a long time that in order to maintain stable operation of a blast furnace, it is necessary to keep the temperature of hot metal constant. For this reason, blast furnace operators have always needed to predict changes in blast furnace heat.

Prediction of temperature drop is extremely important in blast furnace furnace thermal changes, especially since hot metal may solidify due to temperature drop and may no longer flow out of the blast furnace.

As a method for predicting blast furnace furnace heat, Japanese Patent Application Laid-Open No. 60-39107
There are some that have been disclosed. This method is based on the viewpoint that the charge temperature around the furnace belly has a strong correlation with the hot metal temperature.
As shown in FIG. 8, the relationship between the temperature around the furnace belly area detected by the sensor (belly sonde) 2 installed in the blast furnace 1 and the temperature of the hot metal is subjected to linear regression as shown in FIG. 9. Based on this linear equation, the hot metal temperature 'pip is predicted from the temperature around the furnace abdomen.

However, with this method, it is necessary to insert the furnace probe 2 in order to measure the temperature near the inner wall of the furnace, which means that temperature measurements can only be carried out intermittently, which naturally deteriorates the accuracy of hot metal temperature prediction. There was a problem.

Further, even if the hot metal temperature is the same, the furnace temperature may change due to changes in the production plan, raw material charging conditions, etc. Therefore, the linear equation based on the absolute value of the furnace wall temperature shown in FIG. 9 has the problem that accurate prediction cannot necessarily be made.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems of the prior art, to continuously measure the furnace inner wall temperature, and to accurately predict the decrease in hot metal temperature regardless of the absolute value of the inner wall temperature. It is an object of the present invention to provide a method for predicting heat reduction in a blast furnace.

(Means for Achieving the Object) In order to achieve the above object, the blast furnace heat drop prediction method according to the present invention includes installing inner wall thermometers at the first to second levels from below in the height direction of the blast furnace. The inner wall temperature difference was measured at each predetermined time interval using an inner wall thermometer, and the part showing a positive value of 1 m degree difference in the mth (2≦m≦k) level exceeded the predetermined value. During a subsequent predetermined period of time, the blast furnace heat drop is predicted when any of the portions showing a positive value of the inner wall temperature difference below the (m-1> level) exceeds a predetermined value.

(Example) The following may be considered as a cause of the decrease in furnace heat of a blast furnace.

High-temperature air (gas flow) blown up from the blast furnace tuyeres to adjust the temperature and amount of hot metal is usually blown into the center of the furnace. However, the raw material charging conditions.

Due to reasons such as charge distribution, a large amount of gas may suddenly flow to the periphery of the furnace. As a result, 1”e O+C−+
The endothermic reaction of Fe + C○ is promoted and the furnace heat decreases.

By the way, when a large amount of gas flows around the furnace, Na
, when the deposits in the furnace such as Pb and the stagnation layer peel off and fall off the wall, the temperature of the furnace wall in that part increases rapidly. This sudden'I! If an i temperature rise is detected, a decrease in furnace heat can be predicted.

FIGS. 1(a) and 1(b) are a side sectional view and a plan sectional view, respectively, showing the arrangement of an inner wall thermometer used in an embodiment of the present invention. As shown in the figure (a), the inner wall thermometer 3
7 pieces (3 on the back, 2 on the abdomen, 2 on the morning glory) from the box level 3 in the height direction from the bottom of the blast furnace 1, and 4 pieces in the circumferential direction of the blast furnace 1 as shown in Figure (b). Install one. In other words, a total of 28 inner wall hygrometers 3 are installed in four directions and seven levels.

The inner wall thermometer is, for example, disclosed in Japanese Utility Model Application No. 57-81 by the present applicant.
531. The one disclosed in Japanese Utility Model Publication No. 59-16816 may be used, and FIG. 2 is a conceptual diagram showing the inner wall thermometer (hereinafter referred to as "rFM sensor") disclosed in the latter.

In the figure, reference numeral 4 denotes a sheath type thermometer having two conductive wires 5 buried in parallel insulatively and having a temperature sensing part 6 on the front end side. The temperature-sensing parts 6 are arranged in parallel so as to be placed at different parts in the length direction, and a roughly sheathed dummy rod 7 is connected to the tips of the temperature-sensing parts 6 to align the leading ends. The sheath type dummy rod 7 has two conductive wires 5 buried in parallel insulating manner, and has substantially the same thermal conductivity as the sheath type temperature measuring element 4. The FM sensor 3 is formed by keeping the sheath type temperature measuring element 4 in a non-contact manner with an insulating material 8 and housing it in a sheath tube 9.

FIG. 3 is an explanatory diagram of the installation of the FM sensor 3. In the figure, 10 to 13 are the walls of the blast furnace, 10 is a brick, and 1
1 is a stave, 12 is a stamp, and 13 is an iron skin. F
As shown in the figure, the M sensor 3 is installed inside the furnace wall by welding to a packing 14 and a welded portion 15. Note that 16 is a filler, and 17 is a milk injection port into which the filler 16 is poured.

Note that due to the installation and structure of the FM sensor 3 described here, the FM sensor 3 itself is eroded along with the erosion of the furnace wall, and the sheath type temperature sensing element 4 may be exposed inside the furnace near the furnace wall. This means that the temperature j in the furnace near the furnace wall is being measured along with "furnace'!! 4 degrees". Hereinafter, a concept including both will be described as "furnace wall temperature." As mentioned above, compared to conventional thermometers such as sheathed thermocouples, the FM sensor 3 has a large number of measurement points, satisfies rapid temperature measurement response, is capable of long-term continuous temperature measurement, and is highly reliable. The aim is to improve performance, durability, and workability.

Each FM sensor 3 measures the inner wall temperature of the blast furnace 1 at every predetermined sampling time Δt, as shown in FIG. Here, the first (i
= 1 to 4), the inner wall temperature of the FM sensor 3 is T.
Let T be the inner wall temperature at + time Δtffi for one assembly J at time j, then
J-1, the inner wall temperature difference (difference value) J between I T, and T, ,
k, I J-1,k, +ΔT, , is J, +ΔT・ ,=T・・・−■, ・・・・(1) J,
, + J, + J-1, and +.

This state is shown in FIG.

To this difference value ΔT・, to J for each FM sensor 3,
+ Multiply the weight Wl by taking into account the height and the direction of one circumference. moreover,
To the difference value Δ”j, for i is negative, to ■, i
”0, for other values, vk, the positive/negative parameter ■ indicating i=1 is also multiplied by i, and the corrected difference value at time j (
A positive difference value) CT・・ is obtained.

J, Ni, + CT・・=W,・■ ,・Δ King, ,...(2) J
, + k, + J, + Next, the sum of the corrected difference values CTj, .

, and so on.

STj, = , Σ CTj, , ...
(3) Izzj Then, according to the following equation (4), if at least one value STj, (m=1 to 7) of this total difference value STj, becomes larger than a predetermined threshold ε for each level, then It is considered that there is a possibility that the temperature of the wall suddenly rose due to deposits falling on the wall inside the furnace.

ST, ≧ε...(4)J
, l m (m=one of 1 to 7) After that, within an appropriately set hold time, (
4) The (
m-1) FM sensor for each level below level 3. (J
The sum of positive difference values STj, , of =1 to (m-1)) is then (
5) A threshold value ε in which at least one value is predetermined for each level according to the formula.

When it becomes larger, it is assumed that there has been a rapid temperature rise on the furnace wall due to the falling of deposits inside the furnace, and an alarm is output to predict a decrease in furnace heat.

STj,, ≧ε□ ...(5)(
1 = 1 to (m-1)) In addition, in formula (4), ST・ ≧ ε1 ... (6)
When J,1 is established for the first time, an alarm is output at this point.

The above prediction method can be realized by a computer. FIG. 6 is a 70-chart showing the flow of the process. In the same figure, in step S1, the furnace wall temperature T of each FM sensor 3 is measured at every heating time Δ. Next, in step S2, the difference value of each FM sensor 3 is calculated based on equation (1).

Then, in step S3, the sum of positive difference values ST·J for each height level is determined based on equations (2) and (3).

Find k. Furthermore, in step S4, the total sum of positive difference values ST·J for each of these seven height levels is determined.

A comparison is made between k and a predetermined threshold value ε for each level, and if equation (4) is satisfied at any height level, the process moves to the next step S5. On the other hand, if equation (4) is not satisfied at all height levels, it is assumed that there is no abnormality, and the process returns to step s1, and the furnace heat drop prediction is continued by repeating steps 81 to S4.

In step S4, at the height of the m-th level, (
4) If the formula is satisfied, in step S5, m=1
If m=1, it is assumed that a decrease in furnace heat will occur in step $9, and an alarm is output.

If m≠1 is determined in step $5, the next step S
6, the variation time t is set to t. - Initialize to 〇 and set the hold time at the same time.

Next, in step S7, it is checked whether the fluctuation time t exceeds the hold time t. This means that the furnace heat drop sign detected by the m-th level FM sensor 311 is the (m-1)th level.
This takes into consideration the delay in propagation time that is also detected by the FM sensor 3 below the level. Therefore, the varying time tc
If exceeds the hold time hr, the Mm level FM
The sign of decrease in furnace heat detected by sensor 3 is regarded as an error, and the process returns to step S1.

On the other hand, if the fluctuation time tC does not exceed the hold time hr, the process moves to the next step S8. In step S8, the total sum of positive difference values STj, (j!=1 to (m-1)) by the FM sensor 3 below the (m-1)th level, and the threshold value εl predetermined for each level are calculated. Make a comparison and (5)
If the formula is satisfied at any height level, it is assumed that a decrease in furnace heat will definitely occur, and step S9
outputs an alarm. On the other hand, the sum of all positive difference values S
If Tj, , does not satisfy equation (5), step S7
Returning to , it is confirmed again whether the fluctuation time t exceeds the hold time ri, and the furnace heat drop prediction is continued.

FIG. 7 shows the fifth level FM sensor 35 in actual operation.
(a), the sum of positive difference values (b) by each of the FM sensors 34 to 31 of the fourth to fourth rubles (b) to (
It is a graph showing temporal changes in e) and hot metal temperature (f) in a temporal manner, where TC is the control temperature 1f. Same figure (
As shown in a), at time to, the fifth level positive difference value sum STj, 5 exceeds the threshold ε, and at time t. Then, at time t1 within the hold time hr, as shown in FIG. 4(d), the second level positive difference value sum ST* exceeds the threshold value ε2, and an alarm is output again. In this case, as shown in the figure ([), the temperature of the hot metal is the control temperature T. It can be seen that it has decreased further. Therefore, if any action is taken to raise the hot metal temperature at time t1 (increasing the temperature of the gas flow, reducing the amount of water supplied to the blast furnace, etc.), it is sufficient to
The decrease in furnace heat shown in can be avoided.

Since the above prediction is performed based on the furnace wall temperature difference (positive difference value), accurate prediction can be made regardless of whether the absolute value of the furnace wall temperature is higher or lower. Moreover, in addition to detecting abnormalities using equation (4) for the difference in furnace wall temperature at each height level, the fluctuation in the upper part of the furnace can be detected using equation (5) for the difference in furnace wall temperature below the level at which the abnormality was detected. By detecting the downward propagation of heat, it is possible to predict the decrease in furnace heat more accurately and without losing opportunities.

In addition, because of its ease of installation and good temperature measurement response, the FM sensor 3 can be placed to cover the entire circumference of the furnace, and by being able to grasp continuous inner wall temperature differences, more accurate predictions can be made. can.

In this embodiment, an FM sensor is used as the inner wall thermometer, but a normal temperature sensor (for example, a sheathed thermocouple) can be used instead, although there are problems in terms of service life. In addition, even if a stave thermometer or a brick-embedded thermometer is used, its reliability and
Although the prediction accuracy decreases slightly due to the low temperature response,
Can be substituted.

Further, in this embodiment, 28 FM sensors 3 were installed in 7 levels and in 4 directions, but it goes without saying that they may be installed appropriately depending on the characteristics of the blast furnace.

(Effects of the Invention) As explained above, according to the present invention, it is possible to accurately predict the drop in hot metal temperature based on the continuous blast furnace inner wall temperature difference, regardless of the magnitude of the absolute value of the inner wall temperature. Can be done.

[Brief explanation of the drawing]

FIGS. 1(a) and 3(b) are a side sectional view and a plan sectional view, respectively, showing the arrangement of an FM sensor used in an embodiment of the present invention in the blast furnace wall, and FIGS. 2 and 3 are sectional views, respectively. FM sensor conceptual diagram, installation explanatory diagram, Fig. 4 is a graph showing the change over time in the furnace wall temperature measured by the FM sensor, Fig. 5 is a graph showing the change over time in the difference value of the furnace wall temperature measured by the FM sensor, FIG. 6 is a flowchart showing the flow of processing when a computer is applied to an embodiment of the present invention. FIG. A graph showing the sum of positive difference values measured by sensors and temporal changes in hot metal temperature in relation to each other over time. Fig. 8 is a side sectional view showing the arrangement of the furnace belly sonde in the blast furnace in the conventional technology. Fig. 9 is It is a graph showing the correlation between hot metal temperature and furnace peripheral temperature.

Claims (1)

[Claims] (1) Install inner wall thermometers at the 1st to kth levels from below in the height direction of the blast furnace, and measure the inner wall temperature difference at each predetermined time interval with the inner wall thermometers, mth (2≦m ≦k) Within a predetermined time after the part showing a positive value of the inner wall temperature difference of the level exceeds a predetermined value, the part showing a positive value of the inner wall temperature difference of the (m-1)th level or less A blast furnace heat drop prediction method that predicts a blast furnace heat drop when any of the above exceeds a predetermined value.