JPH05271728A - Method for preventing blowby in blast furnace - Google Patents

Abstract

PURPOSE:To provide a preventing method of blowby by beforehand predicting the blowby in a blast furnace. CONSTITUTION:Plural pressure sensor groups 3 uniformly arranged in the circular direction of a shaft part 2 of the blast furnace 1 are arranged to plural steps in the height direction of the shaft part 2 to measure the pressure. When the ratio of difference between the max. value and the min. value in the measured values with the pressure sensors 3 at the same height level to the average value of this height level exceeds the preset ratio, the blasting is reduced to prevent the blowby. As the sign before the development of blowby can surely be detected, the blowby can be prevented. Therefore, the reduction of production caused by the blowby is prevented and the stable furnace condition can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting blow-through in a blast furnace in advance and preventing it.

[0002]

2. Description of the Related Art Generally, in blast furnace operation, it is important to control the falling state of the charged raw material. It is necessary to keep That is, in the blast furnace, while the charging raw material such as iron ore charged from the upper part of the furnace descends, the overall thermal balance is maintained through steps such as stepwise temperature increase, reduction, and melting. .

When blow-through or slip occurs in the furnace of the blast furnace, the charging raw material falls without going through the above process, and the thermal energy held by the gas is released outside the furnace, so that the heat balance is maintained. It often collapses and the inside of the blast furnace cools down, often causing a malfunction of the furnace.

[0004]

However, a method for predicting in advance the blow-through of gas generated in the blast furnace has not been established. Therefore, when the raw material deteriorates or the air flow is changed,
A blow-through occurred and disturbed the layer structure of the raw materials in the furnace, resulting in a significant reduction in production.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and a plurality of pressure sensor groups, which are evenly arranged in the circumferential direction of the shaft portion of a blast furnace, are installed in the shaft portion. The pressure is measured by arranging it in multiple stages in the vertical direction, and the ratio of the difference between the maximum and minimum pressure values measured by pressure sensors at the same height level to the average pressure value at that height level exceeds the set ratio. This is a method for preventing blow-through in a blast furnace, which is characterized by reducing the wind when the wind blows.

[0006]

[Function] A plurality of pressure sensor groups arranged in the circumferential direction of the shaft portion of the blast furnace are arranged in a plurality of stages in the height direction of the shaft portion to measure the gas pressure in the furnace, which occurs before the blow-through. It is possible to detect the collapse of the pressure balance in the circumferential direction. After detecting the collapse of the pressure balance in the circumferential direction,
By immediately reducing the wind, it is possible to prevent blow through.

[0007]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 is a block diagram for detecting abnormality of gas pressure balance in the circumferential direction according to the present invention. In FIG. 1, 1 is a blast furnace,
Reference numeral 2 denotes a pressure sensor 3 which is provided on the side wall of the shaft portion 2 of the blast furnace 1 and measures the pressure of gas flowing near the inner side wall of the furnace. The pressure sensor 3 moves the shaft 2 in the circumferential direction 4
These four pressure sensors 3 are arranged at equal positions.
Are arranged in 10 steps in the height direction of the shaft portion 2.

The measured value of the pressure sensor 3 is transmitted to the calculator 5 via the A / D converter 4. The calculator 5 has a pressure deviation calculating means in the circumferential direction of each stage and a pressure transition graph creating means in each position in the circumferential direction of each stage.

The pressure deviation calculating means performs the following calculations. (1) The difference ΔP = P _max −P _min between the maximum pressure value P _max and the minimum pressure value P _min in the circumferential direction of each stage is calculated for each measurement time. (2) The average value P of the pressure in the circumferential direction of each stage at each measurement time
ask for _ave . (3) For (ΔP / P _ave ) × 100% ≧ 5%, YE
Judge S or NO. (4) If the answer is YES, the display 6 displays the reduced wind% and gives an alarm. Alternatively, an instruction to reduce air is issued to a blower control valve (not shown). Note that the wind reduction% is set to a value between 3 and 5% depending on the furnace conditions at that time. When the display and warning of the wind reduction are issued, the operator manually operates the blow control valve to reduce the wind.

In the pressure transition graph creating means, the transition for each position in the circumferential direction for each stage is drawn on the same graph. The graph thus drawn can be displayed on the display 6 and can be printed out by a printer (not shown) if necessary.

FIG. 2 is an example of a circumferential pressure transition graph during normal stable operation of a certain stage, and FIG. 3 is a circumferential pressure transition graph when there is an indication of blow-through of a certain stage. Is an example of. In the example of FIG. 3, about 20 minutes (ΔP / P _ave ) ×
Since 100% ≧ 5%, a 3% wind reduction is implemented to prevent blow through.

[0012]

Since the present invention is constructed as described above, the sign before the occurrence of blow-through can be detected with certainty, so that blow-through can be prevented. Therefore, it is possible to prevent production decrease due to blow-through and maintain a stable furnace condition.

[Brief description of drawings]

FIG. 1 is a block diagram for detecting an abnormal gas pressure balance in a circumferential direction according to the present invention.

FIG. 2 is a graph showing an example of changes in circumferential pressure during stable operation according to the present invention.

FIG. 3 is a graph showing an example of changes in circumferential pressure when a sign of blow-through according to the present invention appears.

[Explanation of symbols]

 1 Blast furnace 2 Shaft part 3 Pressure sensor 4 A / D converter 5 Computing unit 6 Indicator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sumiyuki Kishimoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. A plurality of pressure sensor groups, which are evenly arranged in the circumferential direction of the shaft portion of a blast furnace, are arranged in a plurality of stages in the height direction of the shaft portion to measure the pressure, and the pressure at the same height level is measured. A method for preventing blow-through in a blast furnace, which comprises reducing air flow when the ratio of the difference between the maximum and minimum pressure values measured by a sensor to the average pressure value at that height level exceeds a set ratio.