JPH02285013A - Method for preventing wear on the bottom side wall of blast furnaces - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for preventing damage to the side wall of a blast furnace bottom using a hot air control valve.

[Prior Art] In pursuit of high productivity, blast furnaces have become larger and operating conditions have become more severe, shortening the lifespan of the furnace bottom side walls and the furnace bottom. This is one of the factors that raises the production cost of pig iron.

In order to extend the life of the bottom side walls and bottom of a blast furnace, it is important to constantly monitor the erosion status of the bottom refractory during operation and take measures to protect the eroded areas. For this reason, multiple thermocouples are installed at the bottom of each blast furnace. The state of erosion is then estimated by heat transfer calculations based on the temperature of the side walls of the furnace bottom and the temperature of the furnace bottom, which are measured using thermocouples.

To prevent erosion of the side walls and bottom of the hearth, improve the material of the side walls and bottom of the bricks, and improve the brick structure (for example,
8-33258 and Japanese Utility Model Application Laid-Open No. 59-133646), partially blinding the tuyeres and introducing a TiO2 source have been practiced in the past.

[Problems to be Solved by the Invention] Since the material quality of the bricks for the side walls and the bottom of the furnace and the brick structure cannot be improved until the blast furnace is re-rolled, the only countermeasures taken during operation are the introduction of ties and sources. TiO2 sources are generally input by producing ilmenite sintered ore, but ilmenite sintered ore requires the use of expensive ilmenite ore and reduces the productivity of the sintering factory. Therefore, there is a problem that the manufacturing cost of pig iron increases. Furthermore, charging electric furnace slag with a high Ti content instead of charging ilmenite sintered ore has been carried out, but there are similar problems.

[Means for Solving the Problems] This invention attempts to solve the above-mentioned problems by operating a hot air control valve provided in the siding and changing the amount of air blown from the siding. This method is characterized by changing the shape of the furnace and increasing or decreasing the hearth porosity.

[Effect] When the air volume blown from the tuyere group is reduced, the furnace core near the relevant area grows and the center of the furnace core changes to the side of the tuyere group where the air volume is reduced). The porosity of the area becomes smaller. When the porosity decreases, the size of the bottom annular flow in the region below it decreases, and the erosion rate of the furnace wall decreases.

[Example] FIG. 7 is a longitudinal cross-sectional view of the attachment part of the hot air control valve, and FIG. 8 is a diagram showing an example of the arrangement of the hot air control valve. In Figure 7,
1 is an annular pipe disposed surrounding the furnace body, 2 is a hot air branch pipe, 3 is a hot air control valve, 4 is a blow pipe, and 5 is a tuyere. In Fig. 8, ○ and ◎ indicate the tuyeres 5, O indicates the tuyere without the hot air control valve, and ◎ indicates the tuyere with the hot air control valve. In this example, the hot air control valve is 3 are installed every other time. The furnace bottom side wall 7 shown in FIGS. 1 and 2 is provided with a plurality of thermocouples (not shown) for measuring the side wall temperature in the circumferential direction, and changes in the side wall temperature are constantly monitored. There is.

When the bottom side wall of the furnace is worn out, the temperature of the side wall increases, so the location of the wear on the bottom side wall can be identified. On the other hand, it is known that a large annular flow exists at the wear area. It is known that the porosity is large near the siding, which corresponds to the area where the furnace bottom annular flow is large.The present invention was created based on this knowledge, and it By operating the hot air control valve 3 provided in the corresponding tuyere 5 and changing the amount of air blown from the tuyere 5, the shape of the hearth 6 is changed and the hearth porosity is reduced.

By doing so, it is possible to suppress the progression of wear and tear on the hearth bottom side wall of the hearth annular flow at the relevant portion.

FIGS. 3A and 3B are explanatory diagrams showing the state before and after changing the shape of the furnace core by the method of the present invention.
In the figure, there is a wear spot 9 on the W side (west side), and at this time the furnace core 6 is biased toward Ell (east side). At this time, the porosity on the W side is large and the porosity on the E side is small. In such a case, as shown in Figure (B), throttle the hot air control valve on the W side. The furnace core grows on the W side and attenuates on the E side, shifting toward the W side. That is, since the porosity on the W side becomes smaller and the porosity on the E side becomes larger, the bottom annular flow on the W side becomes smaller.

The inventors conducted an actual furnace test to confirm the throttle range of the hot air control valve for effectively implementing the method of the present invention. FIGS. 5 and 6 are graphs showing the results.

The throttling range of the hot air control valve was set at three levels: 60 degrees, 90 degrees, and 180 degrees, centered on the position where the wear was most severe. Then, as shown in Fig. 4, the opening degree of the hot air control valve in the aperture range is set to 0%, and the opening degree of the hot air control valve in the tuyere, which corresponds to the part with the most wear and tear, is set to 0%. The opening degree was set at 100%, and the valve opening degree of the tuyere was changed linearly during this period. From Figure 5, it can be seen that the narrower the valve throttle range, the fewer days it takes to lower the furnace bottom side wall temperature to the original temperature, but from Figure 6, the narrower the valve throttle range, the greater the number of slips. I understand 0
When carrying out the method of the present invention, it is important to stabilize the blast furnace operation, so it can be said that the valve throttle range is preferably around 180 degrees.

Note that the valve opening of the tuyeres in the aperture range may be changed stepwise instead of linearly. There is no need to use sintered ore or electric furnace slag, and there is an effect that the temperature of the side wall of the furnace wall can be lowered without increasing the cost of pig iron.

FIG. 8, a longitudinal cross-sectional view of the material part, is a diagram showing an example of the arrangement of the hot air control valve.

DESCRIPTION OF SYMBOLS 1... Annular pipe, 2... Hot air branch pipe, 3... Hot air control valve, 4... Blow pipe, 5... Tuyere, 6... Furnace core, 7... Furnace bottom side wall .

Claims (2)

[Claims] (1) A blast furnace bottom characterized by operating a hot air control valve installed in the tuyere and changing the amount of air blown from the tuyere to change the shape of the hearth core and increase or decrease the hearth porosity. How to prevent wear and tear on the side walls. (2) Fully close the hot air control valve that corresponds to the area of the furnace bottom side wall with the highest side wall temperature, and linearly increase the valve opening of the hot air control valves in the left and right throttle ranges based on that hot air control valve to 100%. 2. The method for preventing damage to a side wall of a bottom of a blast furnace according to claim 1, wherein the damage to a side wall of a blast furnace bottom is increased.