JPS5871310A - Blasting method for blast furnace - Google Patents

Abstract

PURPOSE:To stabilize the operations of a blast furnace and to prolong the life of the furnace through prevention of hanging, slipping or blowing-by by regulating the rate of blasting in accordance with the limit rate of blasting determined from the pressure drop values in the plural positions in the blast furnace where heights differ. CONSTITUTION:The static pressures of the wall of a blast furnace 1 in the various parts thereof are measured by the pressure gages 2a, 2b, 2c, 2d and 2e mounted in the upper, middle and lower parts of the shaft, berry part and bosh part of said blast furnace; at the same time the furnace top pressure is measured with a pressure gage 2f mounted at the furnace top. From these measured values, the pressure drops DELTAP' from the respective measuring positions up to the furnace top are determined with a measuring device 3 for pressure drops; further the limit rate (v) of blasting is calculated with a calculator 4 for the rate of blasting from the measured value (v') of the rate of blasting of hot wind blasted through tuyeres 1a into the furnace 1, the load of the charging materials determined from operating conditons, the set value of the limit pressure drop indices in accordance with actual data, etc., and in accordance with such calculated value, the rate of blasting of hot wind is regulated by a hot wind regulator 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention proposes a blast furnace ventilation method that prevents shelving, slipping, blow-out, etc. that occur during blast furnace operation.

During blast furnace operation, when the pressure loss inside the furnace increases and this becomes balanced with the charge load, that is, the force of the falling charge, Tokoroura shelf suspension occurs, creating a large space inside the furnace. Since it is not possible to supply the charge material by using the method, it is necessary to artificially shelve the material. Also, if it is mild, there is no need to drop the shelf and it will fall naturally. FW slip occurs. Furthermore, if the balance between the pressure loss in the furnace and the charge load is significantly disrupted, the charge will blow up to the top of the furnace, causing so-called blow-through.

When these phenomena occur, it causes abnormalities in the temperature of the hot metal and the conditions inside the furnace.In particular, when blow-through occurs, the temperature at the top of the furnace rises extremely, which can lead to a major equipment-related accident. Therefore, when operating a blast furnace, it is a very important issue to perform proper operation to prevent these phenomena from occurring.

Conventionally, as a method to prevent these phenomena, blowing pressure and furnace m
The difference between the pressure and the charge load is determined, and the blowing pressure is set so that the index does not exceed a certain value, that is, the ratio of this to the charge load. It is known that this phenomenon is caused by K111 combinations such as the temperature distribution inside the furnace and the high temperature properties of the contents inside the furnace. It is not possible to completely prevent the occurrence of such problems as in the case of stairwells, etc. The present invention was developed in view of such circumstances.
The purpose of this paper is to propose a blast furnace ventilation method that prevents the occurrence of shelf hanging, slipping, blow-out, etc. in the furnace, and to stabilize the blast furnace operation and extend the life of the blast furnace.

In the blast furnace air blowing method according to the present invention, the blast furnace top pressure is measured, and the furnace wall static pressure is measured at a plurality of positions at different heights on the furnace wall. While determining the pressure loss from the pressure measurement position to the furnace top, the ratio to the burden load from the furnace top to each furnace wall static pressure measurement position wrt is determined depending on the operating conditions. First, the basic idea of the present invention will be explained. Figure 1 shows the different heights on the furnace wall. Is it a friend graph that shows the difference between the furnace wall static pressure and the furnace top pressure measured at multiple positions @VC, that is, the relationship between the pressure loss from each furnace wall static pressure measurement position to the furnace top and the furnace height? It can be seen that the pressure loss increases proportionally as the furnace height decreases, and increases rapidly near the blast tuyeres. On the other hand, Figure 2 is a graph showing the relationship between the charge load per unit surface injection and the furnace height from the furnace top to each furnace wall static pressure measurement position. It can be seen that the material load increases approximately proportionally as the furnace height decreases. The ratio of this pressure loss to the charge load, that is, the pressure loss index, is an effective index for understanding the unloading phenomenon. Theoretically, when this pressure drop index exceeds 1, shelf hanging, slipping, or blow-through will occur, but in actual furnaces, variations in the properties of the charge, wall surface friction, and load distribution of the charge in the radial direction of the blast furnace occur. The limit value of the pressure loss index (referred to as the critical pressure loss index) at which shelving, slipping, or blow-through occurs due to the influence of gas drift, etc. takes a value of 1 or less. After all, Fig. 3 is a graph showing the relationship between the pressure drop index in Berry svc and the number of occurrences of slip (including shelf hanging), which was obtained from the operating results of blast furnaces.In order to prevent slip occurrence, vcF' i. It can be seen that this pressure loss index should be kept smaller than 0.3.

As described above, in order to prevent the occurrence of shelving, slipping, or blow-through during blast furnace operation, it is preferable to perform blast furnace operation by setting air blowing conditions so that the &Ctj pressure loss index is equal to or less than the above-mentioned critical pressure loss index. It has been experimentally revealed that the relationship between the pressure loss index and the number of slip occurrences is the strongest in the data for the part of the verge shown in Figure 3.

Next, the method of the present invention will be explained in detail based on examples. FIG. 4 is a schematic diagram showing the implementation state of the method of the present invention, and the blast furnace 1 includes the upper shaft, middle shaft, lower shaft, part of the burr, and Bosch S#C pressure gauges 2a, 2b, 2c, and 2d, respectively.
, 2e are installed to form a trap so that the furnace wall static pressure at each section can be measured. The data of the furnace wall static pressure in each part obtained in this way is the measured pressure loss w
13, and a pressure gauge 2f installed on the top of the furnace.
The data of the furnace top pressure measured by the pressure loss measurement value f
ll13, and from both data, the pressure loss from each furnace wall quiet pressure side position '1' to the furnace top is determined. The air flow calculation device 4 flc u inputs this pressure loss data, but also inputs the measured air flow amount of the hot air blown into the blast furnace l from the tuyere 1a, the specific gravity of the contents in the furnace, and past data. Based on this, data regarding the limit pressure drop index for each furnace height, which has been set in advance, is also input, and based on these data, the air blast calculation device calculates the limit air blast amount as shown in the calculation flow diagram of Figure 6. .

The amount of hot air blown from the tuyere 1a is adjusted by the hot air regulator 6 based on this limit amount of air blown. In this way, by blowing hot air below the air blowing limit, it is possible to prevent shelf hanging, slipping, or blow-through.

Next, the contents of the calculation flow diagram shown in FIG. 5 will be described in detail. Generally, the pressure loss index d is determined by the Queen's formula (1).

However, ΔP1': Measured value of pressure loss from each position 1 to the top of the furnace, (measured value of pressure loss inside the furnace) γ8 = Specific gravity of the charge L: Distance from each position 1 to the top of the furnace, as well as shelf suspension, slip, or blow-through The pressure drop index α at the limit where this occurs (limit pressure drop index) is determined by the following formula (2), where: ΔP1: Pressure loss at the limit where shelving, slipping, or blow-through occurs (limit furnace pressure loss) Limit furnace The internal pressure loss ΔP1 is calculated using the following formula (3) n0ΔPl=α×γ8XL - (3) Also, using the measured value ΔP1' of the pressure loss in the furnace and the air flow measurement +i1V', the The ventilation resistance □ is determined by the following equation (4).

However, C6: Gas density β of the contents in the furnace: constant (for example, 0.58) By using these values, the air flow rate at the limit at which shelving, slipping, or blow-through occurs (limit air flow rate)
V is determined by the equation ti1 below.Thus, the limit ventilation amount V is calculated while determining the ventilation resistance of the contents in the furnace for each measurement position soil. Then, the measured air flow rate V' is shown below (6
) as shown in the formula. Blast furnace operation is performed by setting the airflow volume to V (the minimum value is taken among the measured values f111) or less.

When the equation (6) is transformed using the Fiil1 equation, (3) II, and (4) equation, it becomes the following equation ()).

That is, when operating the blast furnace under the air blowing conditions shown in equation (6), the pressure loss index α' can be kept below the critical pressure loss index α, and hanging, slipping, or blow-through can be prevented.

As described in detail below, in the blast furnace air blowing method according to the present invention, the blast furnace top pressure is measured, and the furnace wall static pressure is measured at a plurality of positions at different heights on the furnace wall. The pressure loss from the wall static pressure -1 position directly to the furnace r14 is determined, and on the other hand, depending on the operating conditions, each furnace wall static pressure measurement position li is determined from the furnace top.
1, the ratio of the pressure loss to the charge load, that is, the pressure drop index, is determined for each furnace wall static pressure measurement position, and for each measurement value 1i1, this pressure drop index is Since the blowing conditions are set to be below the limit value (limit pressure drop index) at which blow-through occurs, abnormalities in each part of the blast furnace can be ascertained. Therefore, in the atrium, the occurrence of abnormalities that cannot be prevented by the conventional method of increasing the blowing pressure f + iV so that the index does not exceed a certain value, that is, the occurrence of abnormalities due to the distribution of the temperature inside the furnace, the properties of the charged materials, etc. It is also possible to prevent this, which is highly effective in stabilizing blast furnace operation and extending the life of the blast furnace.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between pressure loss and furnace height. Figure 2 is a graph showing the relationship between burden load and furnace height.
The figure is a graph showing the relationship between the pressure loss 9 and the number of slip occurrences in Berry City, FIG. 4 is a schematic diagram showing the implementation state of the method of the present invention, and FIG. 5 is a flowchart for calculating the critical air flow rate. l...Blast furnace 2a, -b...f...Pressure gauge 3...
・Pressure loss measurement device @ 4...Before air flow rate calculation device 5...
Hot air A4 rig patent applicant Sumitomo Kinko Kogyo Co., Ltd. agent Patent attorney Noboru Kono 4 Sensai! 513!1 Mr. Commissioner of the Japan Patent Office/, Case Indication Recitation 56 Cattle Patent Application No. 168298
No. 2 Title of the invention Blast furnace air blowing method J, Ceramic body with the case of the person making the amendment Patent originator's agent J, "Detailed description of the invention" column of the specification subject to the amendment

Claims (1)

[Claims] 1. In addition to measuring the blast furnace top pressure, the furnace wall static pressure is also measured at multiple positions at different heights on the furnace wall, and these measured values are used to calculate the pressure loss from each furnace wall static pressure measurement position to the furnace top. At the same time, determine the charge load from the furnace top to each furnace wall static pressure measurement position according to the operating conditions, and determine the ratio of the pressure loss to the charge load for each furnace wall static pressure 611 fixed position, A method for blowing air in a blast furnace, characterized in that the blowing conditions are set so that this ratio satisfies a predetermined condition so as not to cause shelving, slipping, or blow-through.