JPS63206413A - Method for predicting reduction of blast furnace heat - Google Patents

Abstract

PURPOSE:To accurately estimate the dropping of the temp. of molten pig iron in a blast furnace by measuring differences in the temp. of the inner wall of the furnace at prescribed positions at regular time intervals and by considering negative values among the differences in place of the absolute value of the temp. of the inner wall. CONSTITUTION:Inner wall thermometers 3 are fitted to prescribed positions of a blast furnace 1 and differences in the temp. of the inner wall of the furnace are measured with the thermometers 3 at regular time intervals. Negative values among the differences are summed up. When the sum total exceeds a set value, it is supposed that the temp. of the wall has suddenly dropped owing to the falling of raw ore, and a warning is given which predicts the reduction of the furnace heat of the blast furnace.

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 in the local area of the blast furnace 1, which is 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. Based on this linear equation, the hot metal temperature "pig" is predicted from the temperature in the local area of 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 temperature of the blast furnace inner wall, 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 an inner wall thermometer at a predetermined location of the blast furnace, and measuring the temperature at predetermined time intervals using the inner wall thermometer. The temperature difference in the inner wall of the blast furnace is measured, and when the sum of the negative values of the inner wall temperature difference at a certain time exceeds a predetermined value, a decrease in blast furnace heat is predicted.

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

When the unloading speed in the blast furnace increases due to raw material charging conditions, charge distribution, etc., the level of the cohesive zone in the blast furnace decreases due to so-called raw ore unloading, resulting in a decrease in furnace heat.

By the way, when the cohesive zone level decreases, the furnace wall temperature at the corresponding portion also decreases rapidly. If this rapid temperature drop 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 hygrometer used in an embodiment of the present invention. As shown in the figure (a), the inner wall thermometer 3
7 pieces in the height direction of blast furnace 1 (3 pieces on the back).

(2 abdomens, 2 morning glories) As shown in the same figure (b), blast furnace 1
Install four in the circumferential direction. In other words, a total of 28 inner wall thermometers 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 disconnected from each other by an insulating material 8 and storing 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 staple, 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. In addition to the "furnace wall temperature", the "furnace temperature near the F wall" is
is being measured. Hereinafter, a concept including both will be described as "furnace wall temperature." As mentioned above, the FM sensor 3 has a larger number of measurement points than conventional thermometers such as sheathed thermocouples, satisfies rapid temperature measurement response, and is capable of long-term continuous temperature measurement. Improved reliability, improved durability,
Efforts are being made to improve 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 inner wall temperature of the first FM sensor 3 at time j is T
1. When closing, 1 sample J at time j, 1 ring time Δ, and the previous inner wall temperature is , then J-
1, I King 1. and T, , which inner wall temperature difference (difference value) ΔTJ,
I J-1,1... is J,1 6th...=T,, -T・, ...(1) J,l
J, I J-1,1. This state is shown in FIG.

This difference value ΔTj, , is multiplied by a weight W· in consideration of the height of each FM sensor 3 in one circumferential direction, etc. Roughly speaking, the difference value Δ
For positive T, , ViJ is 1 10; for other cases, it is multiplied by the positive/negative parameter V indicating Vr = 1, and the corrected difference value at time j (negative difference value ) CT... is obtained.

J, ICT...=W. .V. .ΔD1. ...(2)
J, l I I
J, first order, total FM of the absolute value of the corrected difference value CT.
If the SEJ,1 value becomes larger than a predetermined threshold ε, it is assumed that there has been a rapid temperature drop in the furnace wall due to raw ore descent, and an alarm predicting a decrease in furnace heat is output.

ST・≧ε (4) The above prediction method can be realized by a computer. FIG. 6 is a flowchart showing the flow of the process. In the figure, in step S1, the furnace wall temperature T of each FM sensor 3 is measured at every sampling time Δ. Next, in step S2, the difference value of each FM sensor 3 is calculated based on equation (1).

Then, in step S3, a total negative difference value sTj is determined based on equations (2) and (3). Furthermore, in step S4, this negative difference value sum ST・ is compared with a predetermined threshold value ε, and if equation (4) is satisfied, in step S5, the furnace heat decreases due to the increased unloading speed. It is assumed that this will occur and an alarm is output. On the other hand, if the equation (4) is not satisfied, it is assumed that there is no abnormality and the process returns to step S1.
Predict the decrease in furnace heat by repeating step 4.

FIGS. 7(a) and (b) are graphs showing the hot metal temperature "trio" and the sum of difference values STj over time. The hot metal temperature Tpig in FIG. (1 pig iron tap approximately 2 hours) is the actual temperature measured approximately every 30 minutes,
This is an intermittent tap with approximately 30 minutes between each tap. Furthermore, when a drop in hot metal temperature is observed, action is taken to raise the furnace heat.

In the figure, one scale indicates 100 minutes, and To is the control temperature.

FIG. 7(b) shows the total negative difference value ST obtained by equation (3).
It shows the change over time of 1 minute period of j, and ε is a threshold value. In the same figure (b), an alarm is generated. Therefore, in the event of an alarm, any action to increase the temperature of the hot metal (gas stream temperature) can be avoided.

Since the above prediction is performed based on the furnace wall temperature difference (negative difference value), accurate prediction can be made regardless of whether the absolute value of the furnace wall temperature is higher or lower. Furthermore, due to its ease of installation and good temperature measurement response, the FM sensor 3 can be placed to cover the entire circumference of the blast furnace, and by being able to grasp continuous inner wall temperature differences, more accurate predictions can be made. .

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. A conceptual diagram of the FM sensor, an explanatory diagram of the design, Fig. 4 is a graph showing changes over time in the furnace wall temperature measured by the FM sensor, Fig. 5 is a graph showing changes 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 used in one embodiment of the invention, and FIGS. 7(a) and (b)
are graphs showing the hot metal temperature and the sum of negative difference values STj, respectively; FIG. 8 is a side sectional view showing the arrangement of the furnace belly sonde in the blast furnace in the conventional technology; and FIG. 9 is the hot metal temperature and the temperature of the surrounding area inside the furnace. It is a graph showing the correlation.

Claims (1)

[Claims] (1) An inner wall thermometer is installed at a predetermined location in the blast furnace, and the inner wall temperature difference is measured at predetermined time intervals with the inner wall thermometer, and the sum of the parts showing a negative value of the inner wall temperature difference at a certain time is determined. A blast furnace heat drop prediction method that predicts a blast furnace heat drop when a value exceeds a predetermined value.