JPS63206412A - 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 positive 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. Positive (incremental) 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 risen owing to the falling of a deposit from the wall, 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 total value of the positive value 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.

High-temperature air (gas flow) blown up from the blast furnace tuyeres to adjust the temperature of the hot metal and the temperature of the 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, FeO+C-)Fe
The endothermic reaction of +CO 2 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. If this rapid 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 Figure (a), there are seven inner wall thermometers 3 in the height direction of the blast furnace 1 (three on the back).

(2 abdominal parts, 2 morning glory parts), and 4 pieces are installed in the circumferential direction of the blast furnace 1 as shown in FIG. 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 that they are arranged at different lengthwise positions, and a sheath-type 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 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. In addition to "furnace wall temperature", "furnace temperature near the furnace wall"
is being measured. 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 inner wall temperature of the i-th FM sensor 3 at time j is expressed as
, and if 1 sample J at time j, 1 ring time Δ and the previous inner wall temperature Tj-1,i, then T
1. and T, , which inner wall temperature difference (difference value) ΔTJ, l
It becomes J-1,1. This state is shown in FIG.

This difference value ΔT... is multiplied by a weight W, taking into account the height J of each FM sensor 3, the circumferential direction, etc. Furthermore, if the difference value ΔT... is negative, ViJ, 1 = O1. For other values, it is also multiplied by a positive/negative parameter V, which indicates V, = 1, and the corrected difference at time j is Obtain the value (positive difference value) CTj, .

CT・・=W・・■・・ΔT・ ,
...(2) J, I I I
J, first order, total F of corrected difference value CTj, .
The total sum for the M sensor 3 is taken and this is set as STj.

ST, = Σ CTj, ... (
3) J λ・1 According to the following equation (4), if the value of the total difference value STj becomes larger than a predetermined threshold value ε (approximately 50 degrees), the furnace wall will suddenly fall due to wall deposits inside the furnace. It assumes that there has been a significant temperature rise and outputs an alarm predicting a decrease in furnace heat.

STj≧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 Tj,i 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 as (
1) Calculate based on the formula.

Then, in step S3, the total positive difference value STj is calculated based on equation (21, (3)).Furthermore, in step S4, this positive difference value total STj is compared with a predetermined threshold ε, If formula (4) is satisfied, it is assumed that a decrease in furnace heat will occur due to rapid peripheral flow of gas flow, and an alarm is output.On the other hand, if formula (4) is not satisfied, it is assumed that there is no abnormality. Returning to step S1, the furnace heat decrease is predicted by repeating steps 81 to $4.

FIGS. 7(a) and 7(b) are graphs showing the hot metal temperature Tpia and the sum of difference values STj over time, respectively. In Figure 7 (a), 1 degree of hot metal salt, ig, is the actual temperature of 1 point every 30 minutes during tapping into the hot metal pot (approximately 2 hours of 1 tapping), and the temperature between tapping and next tapping. This is intermittent pig iron that is separated for about 30 minutes between the pig irons.In addition, when a drop in the hot metal temperature is observed, action is taken to raise the furnace heat.

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

FIG. 7(b) shows the total positive 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 at A1 to A7. Therefore, at each alarm A1-A7, any action (increasing the temperature of the gas stream, raising the temperature of the gas stream,
If the water container supplied to the blast furnace is dropped, etc.), the decrease in furnace heat as shown in (a) (2), (2), (2), and (2) can be avoided.

The above prediction is made based on the furnace 9 temperature difference (positive difference 11), so it does not depend on the absolute value of the furnace wall temperature.
Accurate predictions can be made. 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 predictive WI accuracy is slightly lower due to the low temperature measurement response, it can be used as a substitute.

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. 7(a);
(b) is a graph showing the hot metal temperature and the total positive difference value STj, 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 graph showing the hot metal temperature and the inside of the furnace. It is a graph showing the correlation of ambient temperature.

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 a predetermined time interval with the inner wall thermometer, and the sum of the portions that show a positive value of the inner wall temperature difference at a certain time. A blast furnace heat drop prediction method that predicts a blast furnace heat drop when a value exceeds a predetermined value.