JPH01162707A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To reduce bias of distribution of heat flowing ratio to circular direction and to uniformize Si content in molten iron to the circular direction in the furnace by measuring the distribution of the heat flowing ratio to the circular direction in the furnace at the time of operating a blast furnace and controlling hot blast flowing rate with a hot blast control valve arranged to tuyere based on the above measured valve. CONSTITUTION:At the time of operating the blast furnace, temp. and pressure is each zone 11-14 equally dividing the cross sectional plane in the blast furnace into four are detected with detectors 20, and the data are transmitted into a calculator 15 from a measuring instruction 7 and at there, the heat flowing ratio at each zone 11-14 is calculated. This calculated value is inputted into a controlling device 16 and opening degree of flow rate control valve for hot blast arranging to the tuyere group 21-24 at the four zones corresponding to the zones 11-14 in accordance with the deviation is adjusted, so that the above deviation becomes the min. When the deviation of the heat flowing ratio reduces by adjusting hot blast flowing rate from each tuyere group 21-24 at four ranges, the deviation in the temp. of the molten iron to the circular direction in the blast furnace is eliminated, and the deviation of Si content in the molten iron tapped below each tuyere group 21-24 is made to extremely little.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a blast furnace operating method for eliminating imbalance in hot metal components, particularly Si, due to the taphole of a blast furnace.

U Conventional technology In recent years, with the increase in the size of blast furnaces, the burden inside the furnace,
Or the temperature distribution tends to be uneven in the circumferential direction, which causes unevenness in the molten level in the furnace, making blast furnace operation unstable, and also changes the temperature or composition of the hot metal tapped by the tap hole. This issue has begun to receive close attention.

In order to deal with these problems, attempts have been made to make the distribution of raw materials such as sintered ore and coke charged into the blast furnace uniform within the furnace. The raw materials for the blast furnace are sintered ore or iron ore and coke that are charged in alternating layers, and an attempt is made to make the thickness of the layers of the raw materials uniform by driving an armor plate near the stock line. It is something to do. It is expected that this will equalize the ventilation resistance when the hot air blown from the tuyere passes through the raw material layer, and that the reduction and melting reactions will proceed uniformly.

[Problems to be Solved by the Invention] However, the relationship between the thickness of the raw material layer and the deviation in the melting level is not necessarily a direct one, and when the deviation occurs due to unforeseen disturbances, the conventional method It is difficult to eliminate or reduce this.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a blast furnace operating method that reduces the deviation of hot metal components, particularly Si, in the circumferential direction within the furnace.

[Means for solving the problems and their effects] The blast furnace operating method according to the present invention measures the distribution of the heat flow ratio in the circumferential direction inside the furnace, and based on this, the hot air control valve installed in the tuyere controls the tuyeres. It is characterized in that the flow rate of hot air at the mouth is controlled to reduce the bias in the distribution of the heat flow ratio in the circumferential direction.

The heat flow ratio is defined in the blast furnace without molten liquid, and is the heat capacity ratio of solid and gas, and is a function of position and time. In addition, the heat flow ratio is an indicator of the quality of the heat exchange between the solid raw materials that are charged from the top of the blast furnace and are lowered one after another, and the hot air that is blown in from the tuyere and ascends. The position and shape of the so-called cohesive zone, where the charging material changes state from solid to liquid, collectively indicate changes in furnace conditions such as gas flow distribution and temperature distribution. Direct measurement of the position and shape of the cohesive zone has already been carried out by the inventor of this application, but it is difficult to constantly measure it due to cost. The same applicant has developed a method for measuring the heat flow ratio as shown in Japanese Patent Application Laid-open No. 41581/1983, which can be constantly measured for control purposes during blast furnace operation.

This heat flow ratio is constantly measured, and if there is a deviation in the measured value in the circumferential direction, increase the flow rate of hot air from the tuyere corresponding to the direction where the heat flow ratio is small, and monitor the change in the heat flow ratio. Adjust the tuyere flow rate so that this becomes uniform in the circumferential direction.

[Embodiments] Examples of the present invention will be described based on the attached drawings. FIG. 1 is a longitudinal cross-sectional view of a blast furnace, in which 1 is a shaft portion of the blast furnace, 2 is an annular tube, and 3 is a tuyere.

7 is a measuring device for measuring the cohesive zone level 8, and this measuring device 7
The length of the cable can be determined from the time it takes for the electric pulse to reach the cohesive zone level and be reflected back from the cable 9, so the depth to the weld zone can be determined.

Reference numeral 10 indicates a gas chromatograph for analyzing the exhaust gas from the blast furnace.Similar to the measuring device 7, only one of each is shown in this figure for the sake of clarity;
(2) Four portions are provided corresponding to the four regions shown in cross section 5.

Figure 2 is a blast furnace operation control block diagram, and 5 is V- in Figure 1.
Represents the cross section of the V level and divides it into four equal areas 1
1, 12, 13, and 14, which represent the positions of the detectors 20 that measure the heat flow ratio one by one. 6 represents a cross section at the tuyere level indicated by ■-■ in Fig. 1, and tuyere groups 21, 22, 23, 24 corresponding to the four equally divided areas are shown.
It shows. There are about 40 tuyeres in total in a large blast furnace, but here we have three tuyeres each corresponding to the four equal areas.
Let me represent you. The heat flow ratio is defined as the ratio of the heat capacity of the solid to the gas for a specific location and time in the blast furnace. This measurement method is determined by differential calculation from the measured values of the temperature and pressure of the gas in the furnace at regular intervals, and was discovered by the same applicant as mentioned above.

Next, the operation of the blast furnace configured as above will be explained. Data on temperature and pressure at multiple locations in the vertical direction representing the four regions shown in the ■-V cross section 5 in Figure 2 are sent from the measuring device 7 to the computer 15, where the heat flow ratio is calculated. be done. The calculated heat flow ratios at the four locations are input to a controller 16 that controls the flow rate of hot air from the tuyeres, and the tuyere groups 21 at the four locations corresponding to regions 11 to 14 are inputted to the controller 16 that controls the flow rate of hot air from the tuyeres. The opening degree of the flow control valves attached to each of the 24 tuyeres is adjusted. This adjustment continues until the deviation is minimized.

The functions of the measuring device 7 and gas chromatograph 10 shown in FIG. 1 are as follows. As mentioned above, the size of the heat flow ratio corresponds to the quality of heat exchange between the hot air and the charged raw material.In areas where the heat flow ratio is large, heat exchange is delayed and the cohesive zone level is relatively low compared to other areas. very low. In addition, when Co2/Co in the exhaust gas obtained from the gas chromatograph 7 is relatively large, the reduction reaction of iron oxide in the furnace is active, and the distance that the ore falls as a solid is long, so the cohesive zone level is low. This corresponds to a large heat flow ratio.

From this point of view, the measuring device 7 or the gas chromatograph 1
The measured value measured at 0 is input into the computer 15, compared with the constantly measured heat flow ratio, and used for checking this.

When the deviation of the heat flow ratio is reduced as described above, the deviation of the tap iron temperature in the circumferential direction is also reduced, and the deviation of Si in the hot metal due to the tap hole is also reduced. To express this in concrete numerical values, the difference between the maximum and minimum Si [%] in hot metal depending on the taphole was 0.1% in the conventional example, but
In this example, it was 0.02%.

[Effect of the invention] According to the present invention, the distribution of the heat flow ratio in the circumferential direction inside the furnace is measured,
Based on this, the hot air flow rate of the tuyere is controlled by the hot air control valve provided in the tuyere, thereby reducing the deviation of Si in the molten iron in the circumferential direction.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a blast furnace according to an embodiment of the present invention, and FIG. 2 is a block diagram of blast furnace operation control. 1... Blast furnace, 2... Annular tube, 3... Tuyere, 7...
・Measuring device, 8... Cohesive zone level, 9... Cable,
10... Gas chromatograph, 11 to 14... Region, 15... Computer, 16...
・Controller, 20... Heat flow ratio detector, 21 to 24・
...tuyere group.

Claims (1)

[Claims] In the blast furnace operation method, the distribution of the heat flow ratio in the circumferential direction inside the furnace is measured, and based on this, the hot air flow rate of the tuyere is controlled by the hot air control valve provided in the tuyere, and the circumferential distribution of the heat flow ratio is A blast furnace operating method characterized by reducing the bias of.