JPH0285308A - Method for controlling temperature of molten iron in blast furnace operation - Google Patents

Abstract

PURPOSE:To quickly achieve molten iron temp. to the aimed temp. by obtaining calculated input heat variation and also blowing hot blast giving a large quantity of the input heat variation more than the above calculated variation from a tuyere. CONSTITUTION:For example, the temp. variation pattern of the molten metal to blowing of the hot blast giving the calculated input variation step by step at zero point of a time is obtd. by calculating from simulation based on the past data. This temp. variation pattern has gentle inclination of raising temp. of the molten iron at the 0 point. Based on these relation, the calculated input heat variation giving to hot blast is obtd. from difference between the molten iron temp. and the aimed temp. to be achieved and also the hot blast giving a large quantity of the input heat variation more than this calculated input heat variation is blown from the tuyere. Then, when the molten iron temp. comes to the temp. in the prescribed range making the aimed temp. the center, the input variation to be given to the hot blast is changed over to the calculated input variation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention particularly relates to a method for controlling the temperature of hot metal in blast furnace operation, which enables rapid temperature control of hot metal.

[Conventional technology]

In blast furnace operation, it is essential to control the temperature of hot metal in the blast furnace within a certain temperature range.

Therefore, not only when the temperature of hot metal differs from the target temperature, but also when it is determined that the temperature will differ from the target temperature in the near future, use the following procedure to calculate the amount of change in heat input to the hot air. The temperature of the hot metal is controlled by blowing hot air with a calculated heat input change through the tuyere.

That is, the relationship between the heat input change amount ΔU obtained by heat balance calculation, shemission calculation, or data analysis and the required heat change amount Δy of the hot metal is expressed as the relational expression Δy−K・ΔU including the proportionality constant K. If the temperature of the hot metal differs from the target temperature, apply this difference Δy′ to the above relational expression and use ΔU゛−Δy゛/K as the calculated heat input change amount, as shown in Figure 4 (Calculation). As shown in Fig. 5 (Explanatory diagram of the state in which a temperature change amount is given to hot air), by continuing to blow hot air given this calculated heat input change amount from the tuyere, As shown in Figure 1), the temperature of the hot metal in the blast furnace is controlled to reach the target temperature by increasing the temperature of the hot metal with a gentle rising gradient. Ta.

[Problem to be solved by the invention]

Although it is possible to make the temperature of hot metal in the blast furnace reach the target temperature using the conventional temperature control method described above, it is still possible to make the temperature of hot metal in the blast furnace reach the target temperature, as explained below. It has some problems.

That is, according to the conventional hot metal temperature control method described above, the fifth
As shown in the figure, since the temperature change rate of the hot metal is very slow, there is a problem in that a large amount of hot metal is produced at a temperature that deviates from the target temperature. In other words, if the temperature of the hot metal deviates from the target temperature, the amount of work to adjust the composition will increase as the hot metal composition differs from the planned amount, the fuel ratio will increase, and the blast furnace will cool down, so this will cause problems in blast furnace operation. Undesirable.

In addition, as mentioned above, since the temperature change rate of hot metal is very slow, it is difficult to judge whether the temperature of hot metal reaches the target temperature by blowing hot air with a changed calculated heat input change amount. This was difficult, and there was a risk that the temperature of the hot metal could be incorrectly controlled during Ishitoshi's blast furnace operation.

Therefore, it is an object of the present invention to provide a blast furnace operating method that can solve the above-mentioned problems and quickly achieve the target temperature of the pig iron.

[Means to solve the problem]

The gist of the method for controlling the temperature of hot metal in a blast furnace operation according to the present invention is to control the temperature of hot metal in a blast furnace by changing the amount of heat of hot air blown in from a tuyere. Based on the relationship between the amount of heat input change and the temperature change of hot metal based on past data, the calculated amount of change in heat input given to the hot air is calculated from the temperature difference between the temperature of hot metal in the blast furnace and its target temperature, and this calculated amount is calculated. Hot air with a large heat input change that is larger than the heat change is blown into the tuyeres, and when the temperature of the hot metal reaches a predetermined range centered around the target temperature, the input to the hot air is The method is characterized in that the amount of heat change is changed to the calculated amount of heat input change.

[Function] In the present invention, the method for controlling the temperature of hot metal in blast furnace operation is as described above, so that by blowing hot air through the tuyeres that gives a large heat input change amount that is larger than the calculated heat input change amount, The temperature of the hot metal in the blast furnace changes rapidly, and when the hot air is then switched to the one given the calculated heat input change amount, the temperature change of the hot metal becomes gradual.

Since the temperature of the hot metal is already close to the target temperature due to the blowing of hot air with the large amount of heat input change, even if the temperature changes thereafter are gradual, the temperature of the hot metal can be controlled using the conventional temperature control method. The target temperature is reached in less time than the time required to achieve the target temperature.

〔Example〕

In one embodiment of the present invention, the temperature of hot metal is io lower than the target temperature.
Taking the case where 'c is low as an example, Figure 1 is a diagram explaining the state of hot air with a large heat input change needle, Figure 2 is a diagram explaining the temperature rise of hot metal, and the change in magnification for the calculated heat input change amount. Figure 3 is an explanatory diagram of the relationship between the settling time (the time required to reach a temperature equivalent to 80% of the temperature difference between the temperature of hot metal at the initial stage and the set target temperature), and Figure 4 above. , and FIG. 5.

It is known that there are two ways to change the amount of heat of the hot air blown in from the tuyere: one is to change the temperature of the hot air, and the other is to change the amount of moisture, but their functions are the same. In this embodiment, the former method of changing the temperature of the hot air is adopted.

First, as shown in FIG. 4, a temperature change pattern of hot metal with respect to the blowing of hot air with a stepwise calculated heat input change amount at a certain time 0 is calculated and determined by simulation based on past data. This temperature change pattern is as shown in Fig. 5, and the rising gradient of the temperature of the hot metal is gentle. From the relationship between the difference 10'C and the temperature change shown in FIGS. 4 and 5, the calculated amount of change in heat input ΔU' to be given to the hot air is determined using the formula ΔU'-Δy'/f(co).

This calculated heat input change given to the hot air blown in from the tuyere ■ΔU′
The magnification of the large amount of change in heat input, which has a larger amount of heat than It was doubled.

Then, the hot air with twice the large amount of change in heat input is applied until the temperature of the hot metal reaches 120% of the temperature difference between the initial temperature of the hot metal and the target temperature, in other words, as shown in the second blow. , the air was blown until the temperature reached 2°C higher than this target temperature.

Specifically, the time T required for the temperature to reach a temperature 2°C higher than the target temperature from time 0 is calculated using the following formula, f (T)XΔu
'-(10°CX1.2)/2, required time T=
14 hours, and during these 14 hours, 2
By blowing hot air with double the amount of change in heat input,
The temperature of the hot metal was made to reach 120% of the above temperature.

Next, the amount of change in heat input given to the hot air is changed to the calculated amount of change in heat input ΔU', and the amount is blown into the tuyere to gradually lower the temperature of the hot metal. Approximately 30 hours after the start of temperature control work, the PJ
We were able to reach the temperature. Although the required time of 30 hours may seem like a very long time, if the conventional hot metal temperature control method described above is applied to a blast furnace with a capacity of 14,500 m' to which the temperature control method of the present invention is applied. For example, it takes more than 50 hours to reach the target temperature.
Therefore, it will be well understood that the method of controlling the temperature of hot metal according to the present invention is significantly improved over the conventional method of controlling the temperature of hot metal.

In addition, the time between blowing the hot air that gave the large heat input change amount and the multiplier of the large heat input change amount to the calculated heat input change amount, that is, the time after blowing the hot air that gave the large heat input change amount, The relationship between the amount of change in heat input applied to the hot air and the time required to change it to the amount of calculated heat input change is an inversely proportional relationship in which the larger the magnification is, the shorter the time is.

In detail, the above results and other experimental results are shown as follows.
The result will be as shown in Figure 3. That is, in this figure, the vertical axis shows the above-mentioned settling time (hr) until the temperature reaches within ±20% (±2°C) of the temperature difference between the hot metal temperature and the target temperature, and the horizontal axis shows the calculated settling time (hr). It shows the magnification of the calculated heat input change amount,
In addition, the numerical values indicating each percentage in the figure indicate the percentage of the achieved temperature with respect to the temperature difference between the initial hot metal temperature and the target temperature when switching to the calculated heat input change amount.

Therefore, as can be well understood from this figure, the temperature rise gradient of hot metal, as shown in Figure 2, rises rapidly in the initial stage in any case, and then gradually rises with a gentle slope until the temperature rises. is rising or falling to reach the target temperature.

Moreover, the temperature difference between the temperature of hot metal before heating and the target temperature is 8
The time required to reach 0% temperature, that is, the above-mentioned settling time, was about 29 hours in the conventional temperature control method, but was about 4 hours in this example. In this way, the temperature of the hot metal in the blast furnace can be quickly raised to a predetermined target temperature, and the temperature can be easily maintained within a predetermined range.

In order to bring the temperature of the hot metal to the target temperature more quickly, it would be possible to give the hot air a large amount of change in heat input with a higher magnification, but there are problems with the capacity of the hot air temperature adjustment equipment and Considering the uniformity of the temperature and the thermal shock of the above-mentioned equipment, it is desirable to suppress the magnification to about 4 times.

Further, in the above-described embodiments, the case where the temperature of hot metal is increased is explained, but even when the temperature of hot metal that is too high is to be lowered, the amount of change in heat input given to the hot air can be made negative. Therefore, the present invention This does not in any way deviate from the technical philosophy of .

Further, this embodiment described above is only one specific example of the present invention, and therefore this embodiment does not limit the technical scope of the present invention.

〔Effect of the invention〕

In the present invention, the method for controlling the temperature of hot metal in a blast furnace is based on the relationship between the amount of heat input change given to hot air and the temperature change of hot metal based on past data. Calculate the amount of change in heat input given to the hot air from the tuyere, and blow hot air with an amount of adult heat change larger than this calculated amount of heat input from the tuyere so that the temperature of the hot metal is centered around the target temperature. When the temperature falls within a predetermined range, the amount of change in heat input given to the hot air is switched to the calculated amount of change in heat input.

Therefore, according to this hot metal temperature control method, hot air with a large heat input change amount larger than this calculated heat input change amount is blown into the tuyere, so the temperature of the hot metal in the blast furnace is 2. , and when hot air given the calculated heat input change amount determined above is blown, the temperature change of the hot metal becomes gradual, so the temperature of the hot metal can be adjusted more quickly compared to the conventional hot metal temperature control method. It is now possible to reach the target temperature.

Therefore, unlike conventional hot metal temperature control methods, a large amount of hot metal that does not reach the target temperature is not produced in large quantities, and the production amount of hot metal that does not reach the target temperature is significantly reduced. Now you can do it.

In addition, as mentioned above, since the rate of increase in the temperature change of hot metal is very fast, it is possible to clearly see the temperature change of hot metal based on the change in the amount of change in heat input to hot air, so it is possible to check whether the temperature of hot metal reaches the target temperature. It has become easier to judge whether or not the blast furnace has been used, and there is no longer any risk of incorrect temperature control of the hot metal during subsequent blast furnace operations.

Therefore, according to the present invention, it has been possible to establish an extremely excellent and useful method for controlling the temperature of hot metal in blast furnace operation, which can quickly achieve the target temperature of hot metal.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the state of hot air giving a large amount of heat input change in this example, Fig. 2 is an explanatory diagram of the temperature rise of hot metal in this example,
Figure 3 is an explanatory diagram of the relationship between the settling time due to the change in magnification with respect to the calculated heat input change amount in this embodiment, Figure 4 is an explanatory diagram of the state in which the conventional calculated heat input change amount is applied to hot air, and Figure 5 is the calculation FIG. 2 is an explanatory diagram of a temperature rise state of hot metal based on hot air blowing with a heat input change amount. Patent applicant Kobe Steel, Ltd.

Claims (1)

[Claims] (1) In a method for controlling the temperature of hot metal in a blast furnace in which the temperature of hot metal in a blast furnace is controlled by changing the amount of heat of hot air blown in from the tuyeres, the past relationship between the amount of change in heat input to the hot air and the change in temperature of hot metal Based on the relationship based on the data, calculate the calculated heat input change amount given to the hot air from the temperature difference between the temperature of the hot metal in the blast furnace and its target temperature, and also calculate the large heat input change amount that is larger than the calculated heat input change amount. blowing hot air given the above from the tuyere, and when the temperature of the hot metal reaches a temperature within a predetermined range centered on the target temperature, the amount of change in heat input given to the hot air is switched to the amount of change in heat input given to the hot air as described above. A method for controlling the temperature of hot metal in blast furnace operation, characterized by the following.