JPH0328309A - Converter and method for cooling furnace body of converter - Google Patents

Abstract

PURPOSE:To efficiently cool a converter by arranging plural holes to outer iron shell in the converter, packing metal material having large heat conductivity therein and cooling this metal material. CONSTITUTION:Plural holes 3 are bored to the iron shell 1 forming outer shell of a converter and the metal material 4 for cooling of Cu, Cu alloy, Al alloy, etc., having a heat conductivity larger than that of the steel plate, is embedded therein. This embedding metal material 4 is embedded under condition of making this tip part to project from the iron sheel 1 in the converter and covered with half-cutting pipe 5 on this. Cooling water 6 is introduced inside thereof and the material 4 is cooled. At the other way, the embedding metal material 4 is forcedly cooled with air injection 8 from a nozzle 7 to efficiently cool the iron sheel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a converter with excellent cooling performance for the furnace body and a method for cooling the converter body suitable for this converter. (Prior Art) In the converter method, the cost of refractories for the furnace body occupies a large portion of the total cost, and many techniques have been proposed to reduce the cost. For example, Yoichi Kaise ``
“Development and Challenges of Refractories in Japan” Refractories 40 (19
88) P2-13.

In recent converter operations, the refining temperature tends to be higher due to higher quality steel.

It is a well-known fact that the lifespan of bricks decreases in inverse proportion to the rise in temperature, and many attempts have been made to strengthen the cooling of the converter body in order to extend the lifespan of bricks.

In particular, MgO-C bricks have a high thermal conductivity, so by cooling them from the outside, the temperature of the working surface of the brick can be lowered, which has a significant effect on extending the life of the brick. "Improving Furnace Life with Shell Cooling and Single-layer Wound Lining" Refractories 40 (198
8) P609, Kazuya Higuchi et al. “Advances in technology to extend the life of converter machinery and equipment,” Kawasaki Giho 20 (1988) P48-5
5 and Utility Model Application Publication No. 53-106707. However, this technique is only effective for MgO-C bricks and cannot be applied to the entire converter.

On the other hand, for more effective external cooling of bricks in electric furnaces, for example, Hiroshi Kyoda, "Advances in Refractories for Electric Furnaces," Vol.
There is a disclosure on page 139 of the 14th Nishiyama Memorial Lecture.

(Problems to be Solved by the Invention) Now, in a converter, if the furnace body can be cooled in the same manner as in the above-mentioned electric furnace, it is thought that it will greatly contribute to improving the life of the bricks.

However, unlike the wall (water-cooled part) of an electric furnace, the steel shell of a converter is a single structure, supporting the static pressure of the molten steel and the weight of the bricks, so it must be given sufficient strength. Therefore, the steel shell cannot be made into a divided structure like a water-cooled panel, and it is impossible to release stress caused by thermal expansion.

Furthermore, in a converter, the only part that does not come into contact with molten steel is the upper trunnion side, making it structurally difficult to apply water cooling on a large scale.

For the above reasons, current water cooling of converters has been limited to the extent that water cooling pipes are brought into contact with the outside of the steel shell.

Therefore, the object of this invention is to propose a converter having a structure with excellent cooling ability for the furnace body, especially bricks, and a furnace body cooling method suitable for this converter.

(Means for Solving the Problem) The inventors investigated a method for safely cooling the furnace body without impairing the functions of the converter shell, and found that the heat conduction properties of the converter shell were improved. We have found that it is effective to replace part of the iron skin with a material with high thermal conductivity, such as copper.

That is, this invention is a converter made of bricks piled up inside a steel shell, with holes provided in the whole or part of the steel shell,
This converter is made by filling the holes with a material that has higher thermal conductivity than the steel shell.

In addition, the method of this invention cools the portion filled with the above-mentioned material with high thermal conductivity by water cooling or air cooling. Next, the converter according to the present invention will be specifically explained.

Figure 1 is a partial cross-section of the converter body, and as shown in the figure, the entire or part of the steel shell 1, which also forms the outer shell of the converter, is covered with bricks 2 with circular or oval openings. A plurality of through holes 3 are formed at equal intervals, and these holes 3 are made of a material with higher thermal conductivity than the iron skin 1 (for example, copper, copper alloy, or AI).
It is filled with an embedding material 4 made of (aggregation).

Note that the shape of the hole 3 does not need to be limited to a circular or oval shape as long as it does not cause stress concentration against the load applied to the iron skin 1. In addition, the diameter and spacing of the holes 3 should be set taking into account the distortion of the shell 1 due to heat, and that the shell after the hole 3 shape has the strength necessary for the converter. good. Specifically, as shown in Fig. 4, the relationship r/L between the distance L between adjacent holes 3 and the radius r of the holes 3 is selected to be less than 1, and the portions to which the stress of supporting the furnace body is applied are , the arrangement is such as to avoid hole 3. Furthermore, as shown in the cross section of the hole 3 shown in FIG. 5, since the difference in thermal expansion between the steel shell 1 and the embedded material 4 is generally different, the increase in tensile stress on the steel shell 1 due to the thermal expansion force with the embedded material 4 is avoided. , the diameter of the hole 3 is the same as that of the filling material 4.
Make it thicker than the outer diameter of. Further, the wall thickness around the opening of the hole 3 of the iron shell 1 is increased in order to alleviate stress concentration. When fixing the embedded material 4, a filler material 9 is used to absorb the difference in thermal expansion. On the other hand, if the embedded material 4 filling the hole 3 is recessed inward from the surface of the steel shell 1, the cooling effect will be small, so it is preferable that its tip protrudes even slightly from the steel shell 1, as shown in the figure. The protrusion length is normally preferably within a range of 100 mm to avoid contact with the furnace support structure. Alternatively, as shown in FIG. 5, it is also possible to increase the area required for heat radiation by providing a heat sink 10.

In addition, when filling the hole 3 of the iron shell 1 with the embedding material 4, for example, if the embedding material 4 is a Cu chip, the coefficient of thermal expansion of CuO is larger than that of the steel shell, so if the Cu chip is installed using the cooling method, As the skin temperature rises, the contact surface between the steel skin and the Cu chip becomes compressed, and since Cu has lower hardness than the steel skin, the steel skin surface sinks into the Cu part, so there is no reduction in heat conduction due to contact. , which is advantageous. In order to improve the crimping condition, it is desirable to remove scale and degrease the contact surface between the iron shell and the embedded material.

(Function) If the above structure is applied to a converter, it is effective for cooling the furnace body, but it is even more effective to forcibly cool the 4 parts of the embedded material.

That is, as shown in FIG. 2, there is a method in which the embedding material 4 is covered with a half-split pipe 5 and cooling water 6 is introduced into the vibrator 5 for forced cooling, and as shown in FIG. It is advantageous to use a method of forced cooling with air flow 8 from nozzles 7 placed opposite to each other: In general, in water cooling, the cooling intensity α is α(kcal/m" ・hr ・'C) = k v
"'~01V: cooling water flow rate m/s, k: water cooling method, organized by constants determined by water temperature, for example, when v = 1 m/s, the cooling intensity α is 5000 to 7000 kcal/m" -hr
・It is clear that a large cooling effect can be obtained.

Similarly, in air cooling using impinging airflow, the cooling intensity α is α = = kvO-7 V: air flow velocity tags, k: air cooling method, constant determined by air temperature. For example, when V = 100 m/s, Cooling intensity α is 250 kcal/m”・hr・”C% Same 5
At 0 m/s, the cooling effect is approximately 150 kcal/mz・hr・°C, which is 6 to 10 times more effective than air cooling. Further, since the iron skin usually has a thickness of about 50 to 70 mm, the area contributing to heat conduction to the embedded material can be relatively large.

(Example) In an 85-ton top-bottom blowing converter lined with MgO-C (20%) bricks, holes of 30 mmφ were formed in a lattice shape at a pitch of 15 cm in the steel shell of the upper throttle part and side body part. ,
Filling material (pure copper) is embedded in these holes, and the upper constriction part is water-cooled (cooling water flow rate: 21/S, water temperature: 40°C) L according to Fig. 2, and the side body part is air-cooled (air-cooled) according to Fig. 3. Ejection pressure: 2 to 4 kg/cm"G) L, CrK stone was melted and reduced. For comparison, similar cooling was performed in a converter without embedded material in the steel shell. The operation was carried out.

After brick-laying, 100 charges of Cr ore were subjected to melt reduction blowing (average blowing time 70 minutes), and the temperature of the iron skin side and brick surface at the 101st charge and the wear rate of the bricks up to 100 charges were measured. The results are shown in the table below.

Therefore, wear and tear on the refractories in the furnace is reduced, and the life of the furnace can be greatly extended.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a converter body according to the present invention, FIGS. 2 and 3 are cross-sectional views explaining the cooling method according to the present invention, FIG. 4 is a schematic diagram showing hole diameters and distances between adjacent holes, FIG. 5 is a diagram showing an example of attaching the filling material to the steel shell hole portion. 1... Iron shell 2... Brick 3... Hole
4... Embedded material 5... Half pipe 6... Cooling water 7... Nozzle 8...
Air flow 9...Filling material 10...Radiation plate (effect of the invention) This invention greatly improves the cooling effect of the converter furnace body.Figure 1Figure 2Figure 3Figure 4Figure 5

Claims (1)

[Claims] 1. A converter made of bricks piled up inside a steel shell, with holes provided in all or part of the steel shell, and the holes made of a material with higher thermal conductivity than the steel shell. A buried converter. 2. A converter furnace body characterized in that holes are provided in all or part of the steel shell of the converter, the holes are embedded with a material having higher thermal conductivity than the steel shell, and the embedded portions are water-cooled or air-cooled. cooling method.