JPS5910967B2 - Blast furnace operating method excellent in preventing slip occurrence - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a blast furnace that is excellent in preventing the occurrence of slip, and is concerned with a method of operating a blast furnace that is capable of controlling the pressure loss in the furnace (the lower part of the blast furnace, the furnace belly, the lower part of the shaft) and the temperature in the furnace body cooling device. By detecting and keeping them within proper control,
We propose a new method that prevents the occurrence of slip by adjusting the excess or deficiency of the gas flow near the furnace wall, which causes slip, and by optimizing the shape of the inert zone in the furnace.

Recently, due to the rise in the price of heavy oil, oil-less operation, which does not involve injection of heavy oil through the tuyere, has been implemented.

However, with this transition to oil-less operation, a problem has arisen in that slips (unstable unloading phenomena) occur frequently.

On the other hand, conventionally, the radial gas flow distribution inside the furnace was
Adjustments were mainly made using ore/, oke, etc., in order to stabilize loading and unloading.

However, these measures were actually insufficient and did not lead to effective slip prevention.

In response to this, the present inventors discovered that the gas flow distribution in the lower part of the furnace and the gas flow distribution in the upper part of the furnace do not necessarily match, and that the charge distribution is determined based on the gas temperature in the upper part of the furnace as in the conventional method. It was discovered that the method of controlling gas flow in the lower part of the furnace, which has a strong influence on slip occurrence, is not effective for adjusting the gas flow distribution in the lower part of the furnace.

Furthermore, according to the research of the present inventors, the phenomenon in which slips occur frequently after shifting to oil-less operation is due to the fact that the coke and ore in the lower part of the furnace are in a semi-molten state due to poor gas flow near the furnace wall. It was discovered that the reactor profile was such that mixed layers, that is, inactive zones, grew randomly or disappeared.

Therefore, when we analyzed past blast furnace operation data regarding the gas flow near the furnace wall in the lower part of the furnace and the shape of the inert zone, we found that the temperature inside the cooling device in the lower part of the furnace and It was confirmed that there is a close relationship between pressure measurement values and slip occurrence.

Figure 1-1b of the drawing shows the relationship between the temperature inside the cooling device and the occurrence of slip in the past blast furnace operation results, obtained for the temperature measurement position in the direction of the furnace height. On the other hand, during oil-less operation, the temperature was low and slips occurred frequently.

On the other hand, Fig. 1 10 shows the pressure loss in the furnace and the occurrence of slip? The relationship was determined for the pressure measurement position in the furnace height direction.

In this case as well, the pressure drop in the furnace is smaller in the oil-less operation, where slips occur frequently, than in the heavy oil injection period.

In particular, if we focus on the S-1 stave level shown in Figure 1-1a, which is the furnace belly, we can see that in both temperature and pressure drop, the occurrence of slip during operation during the heavy oil injection period is low, and the occurrence of slip during oil-less operation is low. It can be seen that there is a large difference at different times.

In this way, during the oil-less period when slips occur frequently, the temperature,
The reason why the pressure drop is low is because the gas permeability in the furnace is poor in that area, creating the aforementioned inert zone, which prevents smooth unloading of the charge and induces slippage. Conceivable.

In short, the indicated values of the pressure drop inside the furnace and the temperature inside the cooling device in the lower part of the furnace indicate the suitability of the gas flow near the furnace wall and the inert zone.

Therefore, by using the above two measured values as indicators and adjusting them within the desired range obtained from experience by controlling the charge distribution, air flow rate, air temperature, etc., it is possible to increase the slippage of the charge. can be effectively prevented.

The present invention is a method of operating a blast furnace that is effective in preventing slippage and is based on the above-mentioned knowledge.

The details of the configuration will be explained below. FIG. 2 of the drawings shows, as mentioned above, the in-furnace pressure loss in the lower part of the furnace and the temperature of the furnace body cooling device are measured, the values are indexed, and it is calculated whether they are maintained at appropriate values7. This shows an embodiment of the present invention in which the charge distribution is adjusted based on the output, and the operation is performed so that appropriate pressure drop values and temperature values are obtained, thereby preventing the occurrence of slip.

The reference numeral 1 in the figure is a furnace body cooling device such as a stave or a cooling plate, 2 is an in-furnace pressure gauge, and a plurality of these are installed in the circumferential height direction of the blast furnace body. The data is recorded in the process computer.

Next, based on the actual measured values, we will mainly adjust the charging distribution (Or
An example of management by performing vcoke) will be described.

Note that the measured values are indexed for convenience of processing.

First, the temperature of the furnace body cooling device 1 is determined by providing a plurality of measurement points in the height direction and circumferential direction of the lower part of the furnace from the morning glory to the lower part of the furnace chest, and measuring the temperature Tij at each location.

j indicates the height direction, and j indicates the circumferential direction.

First, the measured values of the morning glory part are weighted twice and converted into an index for easier management.

In creating the index, temperature is stratified in units of 100 degrees (for example, 0 to 100 degrees Celsius, 10 points, 100 to 200 degrees Celsius = 1
points, 200 to 30022 points...), points are given to the temperature at each measurement position.

Here, the reason why the temperature is divided at 100° C. is to simplify indexing, and it is possible to use an appropriate numerical value.

Furthermore, the reason why the temperature in the morning glory part is given twice the weight is that the temperature in the morning glory part is more sensitively influenced by the gas flow distribution in the furnace than the temperature in other parts, so this influence was taken into account when creating the index.

The temperatures in the furnace belly and the lower part of the shaft are also indexed in the same way as in the morning glory area.

However, since the morning glory region does not show the influence of the gas flow distribution in the furnace as sensitively as the morning glory region, weighting is not applied to the morning glory region.

Temperature index C of the reactor body cooling system obtained in this way
CT I ).

On the other hand, for the measurement data of the furnace pressure, a pressure loss value (performed by determining the pressure difference ΔPi between the upper and lower measurement positions) is determined for each height level.

Based on these measured values and indices, the gas flow near the furnace wall is adjusted as follows.

That is, as shown in the flowchart of Fig. 3, the experimentally determined furnace wall gas flow shortages are shown for each shaft gas flow rate at each operating level: αLi (lower limit of pressure loss), βL (C
The appropriateness or inappropriateness of the furnace wall gas flow is determined based on the values of αHi (pressure loss upper limit) and βH (CTI upper limit), which indicate excessive gas flow on the furnace wall. Optimization will be achieved by adjusting the nearby charge distribution, and operations will be conducted to prevent slippage.

To explain this point more specifically, the cooling device temperature index CTI obtained by the indexing and the pressure loss value Δ
Set the management value based on Pi.

In this case, if the pressure loss value ΔPi (pressure loss value lower limit αLi and cooling device temperature index CTI < CTI lower limit βL) is within the set values, it is assumed that there is a risk of slippage due to inert zone growth due to insufficient flow on the furnace wall, and cleaning is performed. A charge distribution adjustment called a pattern is carried out.

This either causes more coke to be distributed on the furnace wall, or increases the ratio of coke to ore near the furnace wall. This is an operation to remove the inactive zone.

On the other hand, if the above conditions are not satisfied, the pressure loss value ΔPj
1 Pressure loss value upper limit αHI N and cooling device temperature CTI
> Compare the CTI upper limit βH, and if it is within this set value, it is assumed that there is a risk of equipment damage such as damage to the cooling system due to excessive flow on the furnace wall, or slippage, and a charge distribution adjustment called a restraining pattern is implemented. .

This is an operation method in which the charge distribution is adjusted in the opposite manner to the cleaning pattern described above, and the amount of coke is less on the furnace wall and the ore is more distributed on the furnace wall.

If the above conditions are not met, it is assumed that the gas flow near the furnace wall is good and there is no risk of slippage or equipment damage, and the ratio of ore to coke on the furnace wall side is maintained as is.

In addition, in the example, based on past operation results,
Lower limit αLi and upper limit αHI of pressure loss value ΔPi B, 0.
1~Q, 2Kf/z Cooling system temperature index CTI lower limit βL
and βH were set at 10 to 30 points.

This means that ΔPi is 0. 1 KVC = less than 1, CTI is 1
If the score is less than 0, there is a history of frequent slips, ΔPI
exceeds 0.2K9/,,1 and CT■ exceeds 30 points,
This means that there is a record of occurrence of a so-called raw ore fall situation in which the charged material in a vermilion state falls onto the furnace wall side.

4 to 6 of the drawings show the results of implementing the method of the invention.

As shown in FIG. 6, during the period L1 during which the heavy oil injection operation from the tuyere was performed, there were few slips, and during the period L2 when the oil-less operation was performed, slips occurred frequently.

Therefore, when the present invention was experimentally implemented in period L3,
The occurrence of slips has been reduced.

For this reason, when the present invention was fully implemented in period L4, there were almost no slips.

FIG. 4 shows changes in the pressure loss value in the furnace and the temperature in the cooling device during the period L4 during which the present invention was implemented, corresponding to each location in the furnace height direction.

4b shows the change in the pressure loss value in the furnace, and C in FIG. 4 shows the temperature change in the cooling device. Because there is an inert zone on the wall, SPo-S, which corresponds to the lower part of the furnace,
The pressure drop value at P2 is low.

Furthermore, the temperature inside the cooling device is also low.

Therefore, when the cleaning pattern according to the present invention was implemented, after 64 hours, as shown by the chain line, the inert zone was removed, the pressure value in the lower part of the furnace increased, and the temperature in the cooling device also increased. The occurrence of slips has been reduced.

On the other hand, if the inactive zone disappears, there is a risk of damage to the cooling device or slippage, so in the present invention, a restoring pattern is implemented instead of the above-mentioned cleaning pattern.

The results are shown in Figures 5b and 5c. As can be seen from this figure, in the chain line indicating the period after this restoring pattern was implemented, after 8 hours, both the pressure drop value and the temperature inside the cooling device became low, and an inert zone began to form.
By controlling the pressure drop value and the temperature inside the cooling device within the set range, we were able to significantly reduce the frequency of slip occurrences.

In addition, although we have shown an example of adjusting the pressure loss inside the furnace and the temperature inside the cooling device by adjusting the charging distribution, it is also possible to adjust the pressure loss inside the furnace and the temperature inside the cooling device by adjusting the charging distribution. You may go.

As is clear from the above description, by carrying out the present invention, the occurrence of slip can be prevented, thereby improving the gas utilization rate and reducing the coke ratio.

In addition, by implementing the present invention, the growth of the inert zone can be made appropriate, the gas flow near the furnace wall can be optimized, and unloading can be stabilized, which is effective in preventing damage to the cooling device and falling off.
It has the effect of improving the life of the furnace body and stabilizing the furnace condition of the blast furnace.

[Brief explanation of the drawing]

Figure 1 of the drawings is a diagram showing the changes in the furnace body cooling system temperature and pressure loss value in the furnace during the heavy oil injection operation period and the oil-less operation period, and Figure 2 is a schematic diagram of the blast furnace showing the buried position of the measuring equipment. , Fig. 3 is a flow diagram of gas flow management near the furnace wall, Fig. 4 is a graph showing the changes in the pressure loss value in the furnace and the temperature of the furnace body cooling device showing the results of implementing the cleaning pattern operation, and Fig. 5 is a diagram showing the results of implementing the restraining pattern operation. FIG. 6 is a diagram showing the changes in furnace pressure drop value and furnace body cooling device temperature showing the results, and is a diagram showing the relationship between the conventional example and the example of the present invention with respect to the frequency of slip occurrence. 1...Furnace body cooling device, 2...Furnace pressure gauge.

Claims (1)

[Claims] 1. When operating a blast furnace under furnace conditions where slips are likely to occur due to no injection of heavy oil from the tuyeres, the pressure loss value in the furnace at the lower part of the blast furnace and the temperature in the furnace body cooling system are used as indicators.
A blast furnace operating method excellent in preventing the occurrence of slip, characterized in that the operation is performed to appropriately maintain an inert zone by adjusting the gas flow near the furnace wall so that these indicators fall within predetermined ranges.