KR920006575Y1 - Converter - Google Patents

Abstract

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Description

Compound Blower

1 is a side view of a conventional composite blower.

Figure 2 is a schematic diagram showing the arrangement of the low odor vents in accordance with the present invention.

3 is a schematic diagram showing the arrangement change of the low odor vents for explaining the water model experiment.

4 is a graph showing the change of uniform mixing time according to the number of low odor holes and the arrangement state.

5 is a graph showing the effect of the decarburization rate according to the number of low odor vents.

6 is a graph showing a change in the decarburization rate according to the low oil flow rate.

7 is a graph showing the change in the Y value according to the low-venting opening and the flow rate.

8 is a graph showing the change in the slag (T. Fe) and Lp value according to the tuyere arrangement state.

9 is a graph comparing the calculated Kp value and the measured Kp value according to the air vent arrangement state.

10 is a graph showing the change of the end point [% C] and [% Mn] according to the tuyere arrangement state.

* Explanation of symbols for main parts of the drawings

2: windball

The present invention relates to a composite converter for injecting and purifying pure oxygen (99.99%) gas into molten steel through a squeezing lance and injecting and refining N ₂ and Ar gas from a low blowing hole installed at the bottom of the converter. The present invention relates to a composite blower converter in which the number and arrangement of low blowing holes to blow low odor gas are adjusted.

In recent years, attention has been focused on the low shunt converter method instead of the conventional shunt converter method. Since the low shunt converter method strongly stirs the molten steel as compared to the top shunt converter method (% T. Fe) As a result, the steelmaking process has various advantages that are superior to the upsetting converter method, such as good iron loss and good end point [% Mn].

However, in the conventional composite blower converter, the number and arrangement of low blow holes were set by considering only the uniform mixing time in the absence of slag in the water model experiment.

In other words, the furnace reaction of the converter is a refining process in which gas / liquid (gas oxygen-iron), liquid / liquid (molten iron-slag), gas / liquid / solid (gas oxygen-iron-slag-scrap metal-raw material) Even though the number model and arrangement of low odor vents derived from measuring the uniform mixing time of molten steel in the water model experiment were applied to the converter, the metallurgical characteristics of the upper blast furnace were compared and examined. It has not been proposed yet.

Therefore, in the case of using the conventional composite blower converter, the number and arrangement of low odor vents are controlled based on the water model test result considering only the homogeneous mixing of molten steel (molten steel stirring), and thus the scouring efficiency of dephosphorization and desulfurization copper is low. There was a downside.

Therefore, the present inventors have carried out the actual (250t composite blower converter) experiments considering the uniform mixing of molten steel and the mass transfer over several times, and proposed the present invention based on the results. The purpose is to improve the refining effect rate of dephosphorization and desulfurization while satisfying the stirring and mass transfer at the same time to maximize the stirring power.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In the present invention, as shown in FIGS. 1 and 2, in the 250t composite blow furnace 1 including a plurality of low blow holes 2, the number of the blow holes 2 is eight, and the eight blow holes are circular. The invention relates to a composite blower which is arranged in the form of a composite blower, and more preferably, eight blowholes arranged in a circle form four pairs, and the distance between the paired blowholes is shorter than the distance between the pairs. It is a foraging converter.

Hereinafter, the present invention will be described in more detail with reference to the experimental example using a water model experiment and an actual converter (250t composite blower converter).

Example 1

Water model experiment was performed by changing the number and arrangement of the tuyere as shown in Table 1 below with reference to FIG. 3 showing a lower cross-sectional view of a conventional 250 t converter formed with 14 tuyere, reduced to 1/15. The uniform mixing time was measured by detecting the change in the electrical conductivity of and the result is shown in FIG.

Here, the mouthpiece for low odor is 1 mm A short tube was used.

TABLE 1

As shown in FIG. 4, the eccentrically arranged tuyere types D, I, and J showed a short mixing time of molten steel, but in actual operation, since the eccentrically arranged part has a strong fluctuation of the molten steel, the refractory wear is good. I can't.

In addition, it can be seen that the larger the number of low odor holes, the longer the uniform mixing time, and the better the G type having six uniformly spaced intervals in the uniform mixing time.

Example 2

In general, the converter refining method is to oxidatively remove impurity elements inevitably contained in the furnace operation.

Therefore, how to quickly diffuse this impurity element into the cavity, that is, the reaction zone, which is formed when blown into molten steel through the intake lance, is a mixed steel in the converter. The effects were investigated using the decarburization rate at the end of decarburization and the results are shown in FIGS. 5 and 6.

Here, the decarburization rate was calculated by the amount of carbon and blown oxygen in molten steel during blowing, and the amount of carbon and blown oxygen at the point of blowing completion.

As can be seen in FIG. 5, it can be seen from FIG. 6 that there is no influence of the low odor opening and that the low odor is greatly contributed.

As shown in FIG. 4, the water model experiment has an effect on the number of windballs, whereas in FIG. 5, there is no influence on the number of windballs, and only the effect of low odor flow rate is consistent with the water model experiment of FIG.

Example 3

In the water model experiment that simulates the reaction between liquid / liquid (molten iron-slag) in the converter, oil (cotton oil + paraffin oil) as slag, water as molten iron, and thymol (C ₁₀ H ₁₄ O) contained in the oil phase We investigated the speed of movement to and the results are shown in FIG.

Here, the mass transfer rate of thymol in molten steel is as in (1), and the mass balance is as in (2).

The combination of these two equations is (3).

The higher the Kwat value in (3) is, the faster the thymol in molten steel moves.

Where Cw: thymol concentration in water (grms / cm 3), Co: thymol concentration in oil (grms / cm 3), Vw: volume of water (cm 3), A: interfacial area (cm 3), Vo: volume of oil ( Cm 3), t: time (min.), Kw: mass transfer coefficient, h: equilibrium distribution coefficient, C ° w: initial thymol concentration in water (grms / cm 3).

As shown in FIG. 7 (a), the effect on the number of air vents was clearly seen, and 8 low odor air vents were good, and the polypropylene was also confirmed in the state of being loaded.

This means that the reaction effect between molten iron and slag is significantly improved, which is advantageous for dephosphorization and demanganese in the converter.

Also, as shown in Figure 7 (b). As with the mixing characteristics of the water model test, it can be seen that as the low oil intake increases, the thymol moves faster.

Example 4

The actual dephosphorization reaction at 250t converter is expressed as (4).

Here, the distribution ratio Lp representing the progress of the dephosphorization reaction represents the ratio of (P) in which [P] in the steel escapes into the slag.

In this embodiment, the number of low odor vents in the actual 250t converter was changed to measure the Lp value according to (% T, Fe), and the results are shown in FIG.

In addition, the log Kp value calculated by the Suito equation < log Kp = [(CaO) + 0.3 (MgO)-0.5 (P ₂ O ₅ ) + 0.6 (MnO)] + 22810 / T-20.506 > Kp values were measured and the results are shown in FIG.

The end points [% Mn] and [% C] were also measured and the results are shown in FIG.

As shown in FIG. 8, the number of tufts of eight has a higher Lp value than the number of tufts.

In addition, as shown in FIG. 9 and FIG. 10, the number of 8 tuyere is close to the equilibrium, it can be seen that the eight low odor vents appear slightly higher in the end point [% Mn] and [% C].

As described above, in the conventional composite blower converter method, the number of low blast holes was set in consideration of the uniform mixing only in the number model experiment. As can be seen from the present embodiment, six uniform mixing times were the best in the number model experiment. In operation, the decarburization rate using the mixed characteristics was more influenced by the low odor flow rate than by the number of wind holes.

However, since the furnace reaction in the converter is a complex reaction of various impurities in the reaction zone and dephosphorization and demanganese between molten iron and slag, as mentioned in the conventional experiments, only the mixing time of the water model experiment was measured and used for actual operation. The biggest problem can be pointed out.

Therefore, as can be seen in Examples 3 and 4, it is clear that the number of eight low odor vents is good, as in the actual operation and in the dehydration simulation experiment that simulates the dephosphorization reaction in the converter in the water model experiment.

Therefore, in the case of 250t converter, the number of low odor vents was found to satisfy both the actual mixing characteristics and the mass transfer characteristics.

As described above, the present invention has an effect of improving the refining effect of dephosphorization, desulfurization, etc. by appropriately controlling the number and arrangement of the tuyere of the composite blower converter.

Claims (1)

In the 250-t composite blower converter (1) comprising a plurality of low blowing holes (2), it has eight blow holes (2), and each of the blow holes (2) is formed in four pairs of two each in a circular shape. Composite blower converter characterized in that arranged.