JPH08157917A - Estimation of in-furnace condition at the time of blowing down in blast furnace - Google Patents

Abstract

PURPOSE: To provided an estimating method of in-furnace condition at the time of blowing down in a blast furnace. CONSTITUTION: When blowing down in a blast furnace, the in-furnace condition is estimated by taking the material balance based on blasting quantity, charging material surface temp., furnace top gas temp., furnace top gas components or by applying a thermodynamical equilibrium condition and the blow-off on the way of lowering the stock level and completing time of blowing down are judged to realize the quick blow-down in the blast furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a situation in a furnace at the time of blast furnace blasting, and more specifically, at the time of blast furnace blasting, based on an air flow rate, a charging surface temperature, and a gas component of a furnace top. The present invention relates to a method for estimating the in-furnace situation at the time of blast furnace bluffing by determining the material balance and estimating the in-furnace situation by applying thermodynamic equilibrium conditions to determine blow-by and blow-in completion time.

[0002]

2. Description of the Related Art Conventionally, blast furnace blowdown occurs due to fluctuations in furnace pressure. That is, when the pressure inside the furnace rises, clogging occurs,
After that, it is known that a blanket will occur. However, the information that can be obtained as the situation inside the furnace at the time of blast furnace bluffing includes the position of the charging surface due to sounding or microwaves,
There is no method to estimate the reaction occurring in the blast furnace during the scale reduction process, since it is about the surface temperature measured by the thermometer installed on the surface of the charge.

In general, increasing the amount of oxygen from the bottom of the blast furnace is good for the reaction of the charge, but causes blowout. That is, if there is no blow-through, it is preferable to increase the amount of oxygen as much as possible to accelerate the reaction of the charging material and finish the blow-drying as soon as possible. Charges that are cold from the top when the item is blown
Is not supplied, the temperature of the gas in the furnace rises and the equipment at the top of the furnace is damaged. For this reason, a coke of about 5 charge is placed in the furnace for thermal compensation, and water is added to suppress the temperature rise.

However, since this condition cannot be achieved, the oxygen amount is reduced 2 hours after the start of the blowdown, that is, while the limit air volume is checked. The problem is that it takes longer time.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and specifically, specifically, the top gas component, the top gas temperature, and the surface temperature of the charging material obtained online during the blow-down scale reduction process. , A method of estimating the reaction occurring in the furnace during the scale reduction process that can determine the mass balance from the measured values of the air flow rate, etc. and apply thermodynamic equilibrium conditions to this to shorten the blow-off time It is intended to be a proposal.

[0006]

[Means for Solving the Problems] That is, the present invention determines the material balance based on the amount of air blown, the surface temperature of the charged material, the temperature of the top gas, and the gas components of the top gas at the time of blast furnace blasting. It is characterized by adapting the thermodynamic equilibrium conditions to estimate the in-furnace condition and determine blow-through in the scale reduction process and blow-drying completion timing.

According to the present invention, it is possible to estimate the timing when the ore layer disappears (only the coke layer is formed) at a level above the tuyere in the furnace.

The structure and operation of the means of the present invention will be described below.

The present inventors constructed a model as shown in FIG. 1 in order to estimate the reaction in the furnace at the time of blowout. A method of constructing a reactor estimation model at the time of blowout will be explained.

First, as shown in FIG. 1, H ₂ O by water sprinkling is used.
It is assumed that the areas reached by are classified into three areas, A, B, and C, and that watering in each area causes the reactions shown by the following equations a, b, and c. The water arrival rate and the reaction rate are shown in Table 1, and the air flow rate, water sprinkling rate, and air flow moisture content are each expressed as X (Nm ² / m
in), Y (t / h), and Z (g / Nm ² ). A: H ₂ O + C → H ₂ + CO …… a B: H ₂ O + CO → H ₂ + CO ₂ …… b C: H ₂ O (liquid phase) → H ₂ O (gas phase) …… c

[0011]

[Table 1]

(1) When the reaction in the area A is simulated, it becomes as shown in Equation 1.

[0013]

[Equation 1]

Assuming that there is no ore in the charge (that is, only N ₂ and CO gas flow from the lower part of the furnace), the following equation 2 is given.

[0015]

[Equation 2]

(2) The reaction in the region B becomes as shown in equation 3.

[0017]

(Equation 3)

Here, assuming that the gas that has reached equilibrium in the region A and the reached water (attainment rate β) are in equilibrium, the following equation 4 is given.

[0019]

[Equation 4]

Using this model, H for each region in Table 1
The arrival rates α, β of ₂ O and the reaction rates X, Y of each reaction can be obtained, and the reaction in the furnace at the time of the blowdown can be estimated. H ₂
Derivation of the O reaching rates α and β is obtained according to Equation 5.

[0021]

(Equation 5)

Regarding the method of estimating the dry gas component when the estimated α and β are used, the reaction rates X and Y of the reactions a and b are obtained by solving the quadratic equation shown in the following equation 6 under the equilibrium condition. The estimation results are shown in Table 2.

[0023]

(Equation 6)

[0024]

[Table 2]

From equations (1) to (3) in the derivation of the achievement rates α and β, 0.42 × (2CO ₂ + CO-H ₂ ) V. .

[0026]

(Equation 7)

It can be inferred that this is because the charged material is in a flowing state, that is, in the dangerous area (a kind of blow-through) shown in FIG. → It is time to reduce wind.

Further, when Fg does not increase even when the wind is reduced, it is considered that the absolute amount of coke in the furnace has decreased, and it can be determined that it is the completion timing of the blowhole.

[0029]

[Example] As shown in FIG. 3, 3BF (secondary), 1BF (third) in order to shorten the blow-off time of Mizushima BF (fourth)
Achieved quick inventory by using the new "Industrial gas index" obtained from the inventory analysis of the inventory (4th: 10 hours 55 minutes,
Third: 13 hours 13 minutes).

In the conventional blow-off, the blown air was reduced due to fear of blow-through, but this time, by introducing and managing the following gas index, the blown-air amount was increased to the limit and the blow-off time was shortened. In addition, if the blown gas index is 1 or less, unreacted O
₂ indicates the limit of occurrence.

[0031]

As described in detail above, the present invention is
At the time of blast furnace blowing, the material balance is calculated based on the air flow rate, the surface temperature of the charged material, the gas temperature at the top of the furnace, and the gas components at the top of the furnace. Is estimated to determine the blow-through in the scale reduction process and the blow-drying completion time.

By using the method of the present invention, the blow-off time can be shortened, and the quick blow-off can be carried out. Therefore, there is an effect of suppressing the particle size of the residual coke in the hearth.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an in-reactor reaction estimation model during blast furnace in-furnace blowing according to the present invention.

FIG. 2 is a graph showing the relationship between time and air flow rate, cumulative air flow rate, and scale reduction level.

FIG. 3 is a graph showing the relationship between time and gas index.

Claims (1)

[Claims] 1. When a blast furnace is blown, a mass balance is determined based on the air flow rate, the surface temperature of the charged material, the furnace top gas temperature, and the furnace top gas component, and the thermodynamic equilibrium conditions are applied to this. A method for estimating the internal situation of a blast furnace at the time of the blowdown of a blast furnace by estimating the internal situation of the furnace to determine blow-through during the scale reduction process and the completion timing of the blowdown.