JPS6254006A - Method for controlling distribution of temperature in blast furnace using rate of utilization of gaseous hydrogen in said furnace top - Google Patents

Abstract

PURPOSE:To simply detect and grasp the temp. conditions in a blast furnace in a proper and accurate manner by applying a method for controlling the distribution of temp. in a blast furnace according to the rate of utilization of gaseous hydrogen in the furnace top. CONSTITUTION:The amount of H2 in gas discharged from the top of a blast furnace is measured and the rate of utilization of gaseous hydrogen in the furnace is calculated by the formula. When the rate of utilization of gaseous hydrogen lowers to <=50%, the distribution of temp. in the furnace is controlled by changing the distribution of charge and/or the level of heat.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for controlling temperature distribution in a blast furnace using the hydrogen gas utilization rate of top gas.

(Prior art) Conventionally, the heat level inside the blast furnace has been evaluated by a method using the CO gas utilization rate of the furnace top gas.
In the method based on O gas utilization rate, SCO gas measurement C: In addition, the temperature distribution in the cow radial direction and furnace height direction within the furnace must be measured using various detection ends (furnace top sonde, shaft sonde, vertical sonde, etc.) Ta.

As an improvement measure for this method, for example, JP-A-59-226
109 (Japanese Patent Application No. 58-101284) discloses that the furnace gas is analyzed at multiple points in the radial direction of the blast furnace shaft to measure the hydrogen gas utilization rate or the hydrogen gas utilization rate/CO gas utilization rate. A method for measuring the temperature distribution in the furnace height direction at the above measurement points is disclosed.

(Problem to be solved by the invention) In the conventional method described above, since the value in one direction in the circumferential direction is used as the representative value, the variation in the circumferential direction becomes large in actual furnaces, and it is difficult to grasp the condition of the entire furnace. This method cannot be used for operational management. If we increase the number of measuring points in the circumferential direction and install multiple detection ends with sampling ports of about 10 strokes in the circumferential direction, we can mathematically calculate the hydrogen gas utilization rate by measuring at the detection ends at multiple points in the furnace. Even if the furnace diameter is 10
In a blast furnace with a diameter of about m, large errors occur because the sample amount is small relative to the whole, and appropriate measures cannot be taken. Furthermore, the above method requires sampling at multiple points in the radial direction, which requires a great deal of effort and cost to analyze the V%, and the data analysis is complicated. It has drawbacks such as not being able to match the furnace condition, so it cannot be said to be sufficient as a furnace condition management method.

The present invention is a simpler method than the above-mentioned conventional methods, and allows the situation inside the furnace to be grasped with high precision, and control can be performed based on this grasped situation inside the furnace, resulting in an extremely effective furnace. The purpose is to provide a method for controlling internal temperature distribution.

(Means to solve the problem) Original F! A is the hydrogen gas utilization rate ηH2 [(implant) Hz amount - discharged H2 amount calculated from the amount of H2 discharged n determined by measuring the amount of H2 in the top gas of the blast furnace and the amount of input H2.
There was a constant relationship between the amount of input H2)/the amount of input H2 (xioo), the furnace radius measured using various sondes, and the temperature distribution inside the furnace in the direction of the furnace height, and the hydrogen gas was used.

Therefore, the present invention measures H2t in the blast furnace top gas to determine the hydrogen gas utilization rate of the blast furnace, and when the hydrogen gas utilization rate becomes 50 or less (=, charging This is a furnace temperature distribution control method using the hydrogen gas utilization rate of blast furnace top gas, which is characterized by performing one or both of distribution change and heat level change, or a combination thereof.

Below are various data that led to the above findings.
Let me explain about the tar.

First, Figure 1 shows the temperature distribution inside the blast furnace. Figure 1 (a
) t (b) is a large blast furnace on March 26th (indicated by O)
The data was measured using a vertical sonde on May 29th (indicated by Δ).
fi position), 1100 at intermediate M (position 2.5m from the furnace wall) and peripheral P (position #!L 0.6m from the furnace wall)
The °C line is shown, and (b) is at ηH2 = 44.7.
The temperature distribution in the furnace height direction at the middle M is shown when (Δ) and when ηHs = 52.8 N (○).

The hole temperature distribution data shown in FIG. 1(b) and the corresponding hydrogen gas utilization rate in the furnace height direction are shown in FIG. Comparing the temperature distribution data for March 26th and May 29th in this figure, it can be seen that the length of the temperature around 100°C (high-temperature thermal storage zone) is significantly different.

Then, by rewriting the temperature distribution and hydrogen gas utilization data for March 26th and May 29th in Figure 2, we obtain the third residence.
Ru. From this figure, it can be seen that the data for March 26th and May 29th decrease in temperature (accompanyingly, the hydrogen gas utilization rate increases. The line drawn by the plot of the utilization rate and the hydrogen gas utilization rate on May 29th, when the heat reserve zone is short, is U 100 (intersects at around 1℃,
The temperature rapidly changes to 1lFIf around 0°C. This is thought to be due to the difference in the length of the thermal storage zone. In other words,
1000℃ for March 26th data and May 29th data
The difference in the increase in H20 in the vicinity is the difference in the increase in H20 in the vicinity.
The residence time near 0℃ was long on March 26th, and on May 2nd.
This is because the 9-day data is short, and therefore, the grain reduction reaction does not occur sufficiently in the May 29 data, which has a short residence time.
100 before reaching the equilibrium concentration of iron.
This is thought to be due to passing through the 0°C region.

Therefore, next, 900 to 110 in the middle part of the vertical sonde.
The relationship between the residence time at 0°C and the hydrogen gas utilization rate of the furnace top gas was determined, and Figure 4 was obtained. From this figure, it can be seen that the hydrogen gas utilization rate of the furnace top gas decreases as the residence time at 900 to 1100° C., which corresponds to the length of the heat storage zone, becomes shorter. In addition, measurements were made even if there were two areas (the center and the periphery), but the same results were obtained. This indicates that the rising temperature at the top is not sufficient.

Furthermore, FIG. 5 shows the relationship between the hydrogen gas utilization rate of the furnace top gas and the distance from the upper cline at the intermediate 1100° C. position.

In addition, the 1100°C position in the figure is considered to approximately correspond to the upper surface of the softened cohesive zone. From this figure, the middle part 1100
It can be seen that the hydrogen gas utilization rate of the furnace top gas decreases as the temperature rises.

Furthermore, Figure 6 (a) shows the 1100℃ line shape (cohesive zone shape (corresponding)), and the relationship between the ΔH length in (a) and the hydrogen gas utilization rate of the furnace top gas is shown in Figure 6 (b). ).

Here; ΔH is the center position at 1100°C and the circumferential position at 1100°C.
This is the difference in temperature. From the figure, it can be seen that as ΔH increases, the hydrogen gas utilization rate of the furnace top gas decreases.

From this, it is thought that the hydrogen gas utilization rate of the furnace top gas is low in the cohesive zone where the top layer of the cohesive zone has a large ΔH and the cohesive zone has a large center flow with a large difference in the root level.

From the data shown in Figures 5 and 6 above, it is clear that using the hydrogen gas utilization rate of the furnace top gas, it is possible to detect not only the temperature distribution in the furnace height direction but also the temperature distribution in the furnace radial direction. I also learned that it can be determined with sufficient reproducibility.

Therefore, it has become clear that preventive control of the furnace condition is possible by setting management standards for the hydrogen gas utilization rate and taking operational actions.

The lower limit control value for hydrogen gas utilization rate of furnace top gas is for various sondes (top sonde, shaft sonde).

The temperature distribution in the furnace in the direction of the furnace height (tl, fc, furnace radius, and furnace height) measured using a vertical sonde is determined in advance from the relationship with the hydrogen gas utilization rate of the furnace top gas. Specifically, the setting standard is determined using the length of the heat storage zone, which represents the surplus heat level in the furnace, as a guide, and in this case, ηH2 is 50 or less.

The temperature distribution control actions in the furnace when the hydrogen gas utilization rate of the furnace top gas falls below the lower limit include changing the sequence of the movable armor and changing the index finger level.

Burden distribution actions such as unequal charging (method of charging by changing the amount of IO and ■0 of ore), charging by particle size, and changing the bellless chute sequence and batch yield increase (temporarily;
There are several heat level change actions such as increasing the fuel ratio by several tens of batches), changing the amount of pulverized coal injected, and changing the blowing temperature, each of which can be done individually or in combination.

(Example) Next (- An example in a large blast furnace is shown.

The lower limit of the hydrogen gas utilization rate of the furnace top gas was set using the relationship between the residence time of 900 to 1100°C in the peripheral area measured using a vertical sonde and the hydrogen gas utilization rate of the furnace top gas, as shown in Figure 7. . As mentioned above, considering the length of the thermal conservation zone as the standard,
The value of the hydrogen gas utilization rate of the furnace top gas at the point where the residence time at 900-1100'C in the peripheral area where the ore/coke value is large and the temperature conditions are severe is 130 minutes was set as the lower limit. That is, the control lower limit value of the hydrogen gas utilization rate of the furnace top gas was set to 50%.

Based on this management standard, operational actions as illustrated in Figure 8 were carried out.

In other words, as shown in Figure 8 (a), the hydrogen gas utilization rate of the top gas decreased from January 3rd, and as a result of this, Figure 8 (d) (- as shown (= middle shaft The temperature of the sonde (Point 4 = 1lflt% radius position from the stock line is the vertical sonde intermediate position) decreased - the same figure (g) Deterioration of unloading such as plunge φ and slip S as shown in Fig. 2 occurred.

At this time, as shown in Figure 8 (b), there was no decrease in the CO gas utilization rate! 'L wasn't there.

The decrease in the hydrogen gas utilization rate of the furnace top gas is thought to be due to the excessive center flow suppressing the surrounding area as described in the explanation of Figure 6. Armor sequence 0AOo (indicates Af13.5 notch)
Changed from 0AO0, OA, OO, 0300 to 0AO0, OA, OO, 0300, reduced the value of ore/coke around 1, and took charge distribution action at 23:00 on 3rd to make it easier for gas to flow to the surrounding area.

Even after this action, the hydrogen gas utilization rate of the furnace top gas did not increase as shown in Figure 8 (a), and the hydrogen gas utilization rate in the furnace top gas did not increase as shown in Figure 8 (d).
As shown in Figure 8(f), the temperature of the middle shaft sonde did not rise, and the load condition continued to deteriorate due to thrust T, slip S, etc. As shown in
The amount of coke for 5 charges was changed from the usual 27 T/ch to 27.3 T/ch to increase the heat level in the furnace.

As a result, on the 6th (-), the hydrogen gas utilization rate of the furnace top gas increased, unloading became better, and the temperature at the 4 points of the central shaft sonde also recovered.Therefore, on the 6th, the movable armor sequence was returned to 0AOO. .

The increase in batch yield on the 6th was a hole-in-the-wall action taken to prevent excessive gas flow restriction in the surrounding area due to changes in movable armor. As mentioned above, as a result of taking prompt action to address the decline in the utilization rate of hydrogen gas in the furnace top gas,
As shown in Figure (C), stable operation could be maintained without a sudden drop in hot metal temperature.

(Effect of the invention) By using the furnace temperature distribution control method using the hydrogen gas utilization rate of the furnace top gas described above, it is possible to appropriately and accurately detect and grasp the temperature situation inside the furnace in a simple manner. By performing appropriate processing based on n
In addition, costs can be reduced by reducing the frequency of use of various detection terminals and omitting installation.

[Brief explanation of the drawing]

Figure 1 shows 1 for March 26th (0 mark) and May 29th (Δ mark).
The relationship between the temperature distribution in the furnace height direction at the 100° C. line and the intermediate portion is shown, and FIG. 2 shows the change in gas temperature and hydrogen gas utilization rate in the furnace height direction. Figure 3 shows the relationship between the furnace temperature and the hydrogen gas utilization rate, Figure 4 shows the relationship between the hydrogen gas utilization rate of the furnace top gas and the residence time of 900 to 1100°C in the middle part, and Figure 5
The figure shows the hydrogen gas utilization rate of the furnace top gas and the open position at 1100℃ in the middle part, and Figure 6 shows the hydrogen gas utilization rate of the furnace top gas and
The relationship between the shape of the 100°C line and the height difference ΔH between the center C and the periphery P of the furnace is shown. FIG. 8 shows an example of the operation of the embodiment of the present invention. Agent: Patent attorney Masaaki Akizawa, Mitsugai (2 people)

Claims (1)

[Claims] (1) Measure the amount of H_2 in the blast furnace top gas to determine the hydrogen gas utilization rate of the blast furnace, and when the hydrogen gas utilization rate falls below 50%, change the charge distribution, change the heat level A method for controlling temperature distribution in a blast furnace using the hydrogen gas utilization rate of top gas of a blast furnace, characterized in that either one of the changes or a combination of changes is performed. However, hydrogen gas utilization rate = (Input H_2 amount - Emission H
_2 amount) / (input H_2 amount) x 100