JPH09157713A - Method for estimating erosion line of furnace bottom and structure of furnace bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for precisely estimating the balanced eroded line of a furnace bottom brick and the structure of a furnace bottom which can restrain the erosion of the furnace bottom brick as little as possible. SOLUTION: This estimation method of an eroded line of the furnace bottom in a blast furnace is executed by calculating temp. distribution of the brick at the furnace bottom part and fluidity and temp. distribution of molten iron based on a material balance equation and a momentum balance equation of the molten iron in the blast furnace lined with the brick and an energy balance equation of the total range containing the brick. The calculation is executed until the wear of the brick stops with a mathematical model calculating the progressing of the wear of the brick while discriminating the wear of the brick based on the calculated temp. distribution, and the wearing details and the balanced worn line of the furnace brick are estimated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace, an electric furnace, or a method for estimating an erosion line at the bottom of a furnace having a refractory lined therein for storing a high temperature metal melt. Regarding the bottom structure.

[0002]

2. Description of the Related Art Conventionally, the erosion line at the bottom of a blast furnace is based on the temperature of a thermocouple embedded in the refractory of the blast furnace that is actually operating, and the temperature and distance between the two points and the brick between them. It is estimated by the method of calculating the heat flux from the thermal conductivity of, and assuming the temperature of the operating surface in the furnace as the wear limit temperature of the material to calculate the remaining thickness.

Further, as seen in Japanese Patent Laid-Open No. 60-184606, heat transfer analysis is carried out by the boundary element method with a plurality of temperature measurement values provided around the furnace body as constraints, and the residual brick thickness is determined. A calculation method and the like are also known.

[0004]

However, these conventional estimation methods require actually measured temperature data, and cannot predict in advance how much brick erosion will progress.

Regarding the furnace bottom structure, with respect to the brick profile, a method for providing a refractory structure that is smooth in the circumferential direction and the height direction (Japanese Patent Laid-Open No. 6-240322) and brick stacking Various structures have been proposed, such as a method for regulating and relaxing thermal stress (Japanese Patent Laid-Open No. 62-96609). However, as described above, there is not sufficient means for predicting brick wear in advance, so it is not possible to select a brick material or a furnace bottom structure that can completely control brick wear.

Particularly in a blast furnace, as shown in FIG. 4, the conventional typical furnace bottom structure has a refractory brick 3 which is a clay-based brick inside the furnace (lining) and the outside of the furnace, that is, the steel shell 1. A carbonaceous brick 2 is arranged on the side (outer surface) to prevent bottom erosion and extend the service life. Here, what is important is that the refractory bricks 3 lined inside remain for a long time,
This is to prevent the temperature of the high-temperature melt inside from decreasing and to keep the erosion of the furnace bottom brick to a minimum.

An object of the present invention is to provide a method for accurately estimating the equilibrium wear line of a hearth brick and a hearth structure capable of suppressing the erosion of the hearth brick as much as possible.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted various experiments, and if the flow of molten pig iron at the bottom of the furnace and the heat transfer phenomenon in the region including bricks and the conditions of brick wear are clear, The present invention has been completed by finding that it is possible to accurately estimate the time transition of the wear line of the hearth bottom bricks by constructing the mathematical models to be described and solving them by advancing them in parallel and solving them.

The method for estimating the erosion line of the bottom of the furnace according to the present invention is the mass balance equation, momentum balance equation, and energy balance equation for the entire area including the brick of the molten metal melted in the brick lined furnace. Based on this, the temperature distribution of the bricks in the furnace bottom and the flow and temperature distribution of the metal melt are calculated, and a mathematical model for calculating the wear progress of the bricks while determining the wear of the bricks based on the calculated temperature distribution. The calculation is performed until the brick wear is stopped by, and the history of wear of the furnace bottom brick and the equilibrium wear line are estimated.

In the hearth bottom structure according to the present invention, it is assumed that carbonaceous bricks are used as an outer lining material and clayey bricks are used as an inner lining material, and that all are composed of carbonaceous bricks. Calculate the temperature distribution of bricks at the bottom of the furnace and the flow and temperature distribution of the metal melt based on the mass balance equation, momentum balance equation, and energy balance equation for the entire area of the molten metal in the furnace The remaining in the equilibrium wear line of the hearth brick estimated by performing calculations until the brick wear stops by a mathematical model that calculates the wear progress of the brick while determining the brick wear based on the calculated temperature distribution Characterized by having a carbonaceous brick that is an outer lining set to a thickness equal to or less than the brick thickness, and a clayey brick lined inside the carbonaceous brick That.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method of estimating an erosion line of a furnace bottom and a structure of the furnace bottom according to an embodiment of the present invention will be described with reference to the drawings.

First, the operation of one embodiment will be described below.
The bottom of the blast furnace is made up of the structure of bricks, its contents of hot metal and coke packed bed, and the hot metal mass balance equation (1), momentum balance (2), and the entire area including bricks Energy balance equation (3) is as follows.

[0013]

(Equation 1)

[0014] U: velocity vector, [rho: density, p: pressure, mu: Viscosity, beta: volume expansion coefficient, g: gravitational acceleration, Cp: specific heat, T: temperature, T _o: the reference temperature, lambda: thermal conductivity , Ε: porosity, φ: particle shape factor, d _p : particle size If the above equations (1) to (3) are solved simultaneously, the hot metal flow and the temperature change over time can be obtained. it can. Then, if the time is progressed while judging the wear of the brick based on the obtained temperature, it is possible to describe the wear progress of the furnace bottom brick. The procedure is shown in FIG. In FIG. 1, first, in step S1, an initial structure of a bottom brick is provided. This creates a grid.

In step S2, three variables U, p, T
Set the initial conditions of (velocity vector, pressure, temperature).
In step S3, the inflow condition of the hot metal is set. In step S4, the time t is advanced by Δt.

In step S5, the velocity vector U and the pressure p at t = t + Δt are obtained by the above equations (1) and (2). In step S6, t =
Find the temperature T at t + Δt. In step S7,
The brick wear is determined based on the temperature T.

Here, in the case of carbonaceous bricks, the abrasion loss of the bricks is determined based on 1150 ° C., which is the solidification temperature of the molten pig iron, because there is dissolution loss to the molten pig iron. The melting temperature is set to the limit temperature. Brick that has reached a temperature above this is replaced with hot metal to remove the bricks one after another.

For example, in this step 7, when the temperature of the lattice point in the brick calculated by the calculation exceeds the above-mentioned limit temperature, the physical properties on the calculated lattice point [density, thermal conductivity, viscosity (However, brick does not need viscosity)]
By replacing the with that of the hot metal, the brick wear is determined and the hot metal is replaced.

In step S8, it is judged whether or not the wear of the bricks has ended, and the process returns to step S4 to proceed with the calculation until it is judged that the wear has ended. Then, in step S8, it is finally determined that the equilibrium erosion has been reached when the brick is no longer worn. As a result, the equilibrium erosion line of the brick is obtained in step S9.

At this time, if all the bricks are made of carbonaceous bricks and the equilibrium wear line is obtained, no further brick wear progresses. Therefore, in FIG. If the thickness of the equilibrium wear line or less is used as the initial brick thickness of the carbonaceous brick 2 and is lined on the inside of the steel shell 1, and the refractory brick 3 which is a clay type brick is lined on the inside,
The refractory bricks 3 having higher fire resistance than the carbonaceous bricks 2 remain, the erosion of the furnace bottom can be reduced, and the refractory bricks 3 can be left. Typical compositions and physical properties of carbonaceous bricks and clayey bricks are shown below.

[0021]

[Table 1]

[0022]

EXAMPLE FIG. 3 shows a comparison between the estimation result of the equilibrium wear line of the bottom brick by this method and the actual measurement result obtained from the dismantling investigation after the shutdown of the blast furnace which was actually operating. Further, the dimensions of the furnace body at this time are shown in FIG. 2, and the operating conditions are shown in Table 2.

As shown in FIG. 3, the estimation by the method of the present invention shown in (a) successfully reproduces the actual measurement result shown in (b), and its usefulness is clear. That is, the erosion line can be accurately estimated by the equilibrium wear line estimated by the method of the present invention, and the thickness of the carbonaceous bricks is set to the same as or less than the estimated equilibrium wear line thickness in the furnace. Erosion can be minimized.

[0024]

[Table 2]

The dimensions of the furnace body were as follows, as shown in FIG. a: Inner diameter of brick (distance from center of furnace to inner surface of brick) b: Inner diameter of furnace top (distance from center of furnace to outer surface of brick at tap hole position) c: Inner diameter of furnace bottom (furnace center to furnace at position of bottom of brick) Distance to outer surface) h ₀ : Distance from furnace top to lenght (distance from taphole to bottom lenght outer surface) h ₁ : Height of furnace (distance from taphole to bottom brick inner surface)

[0026]

As described above, according to the present invention, the equilibrium wear line of the bottom brick can be predicted in advance,
The bottom brick can be designed appropriately. as a result,
Erosion of furnace bottom bricks can be minimized, and refractory bricks can remain.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a procedure for calculating an erosion transition of a hearth brick.

FIG. 2 is a schematic diagram illustrating dimensions of a furnace body.

FIG. 3 is a diagram showing a comparison between the equilibrium wear line estimation result of the bottom brick by this method and the brick wear line measurement result after the operation of the actual blast furnace is stopped.

FIG. 4 is a diagram showing a structure of a typical bottom of a blast furnace.

[Explanation of symbols]

 1: Iron skin, 2: Carbon-based brick, 3: Fireproof brick

Claims (2)

[Claims] 1. The temperature distribution of bricks at the bottom of the furnace is based on the mass balance equation, momentum balance equation, and energy balance equation for the entire area including bricks of the molten metal melted in the brick-lined furnace. Calculate the flow and temperature distribution of the metal melt, calculate until the brick wear is stopped by a mathematical model that calculates the wear progress of the brick while determining the wear of the brick based on the calculated temperature distribution, the furnace, A method for estimating the erosion line of the furnace bottom for estimating the wear history of the bottom brick and the equilibrium wear line. 2. In a furnace bottom structure in which a carbonaceous brick is used as an outer lining material and a clayey brick is used as an inner lining material, it is assumed that all are made of carbonaceous bricks, and a metal melt melted in the furnace. Based on the mass balance equation, the momentum balance equation, and the energy balance equation for the entire area including bricks, the temperature distribution of the bricks in the furnace bottom and the flow and temperature distribution of the metal melt are calculated, and the calculated temperature Set the thickness equal to or less than the remaining brick thickness in the equilibrium wear line of the hearth brick estimated by performing calculations until the brick wear stops by calculating the brick wear progress while determining the brick wear based on the distribution A furnace bottom structure comprising: a carbonaceous brick that serves as an external lining, and a clayey brick that is lined inside the carbonaceous brick.