JP2009068033A - Apparatus for distributing bottom-blowing gas in converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for distributing bottom-blowing gas in a converter which is set to a bottom-blowing converter or a top-and bottom-blowing converter and can uniformly distribute gas or solid-gas two-phase fluid into the plurality of tuyeres at the converter bottom. <P>SOLUTION: In the apparatus for distributing the bottom-blowing gas in the converter, in which a gas circling chamber provided with an outer cylinder and an inner cylinder at the top part is disposed and the plurality of separated chambers divided to each tuyere at the lower part, are disposed, on the side wall of the outer cylinder, an outer cylinder opening part connected with a flowing-in tube, is arranged, and the upper end part of the inner cylinder is opened in the outer cylinder and this lower end part is connected with the plurality of separated chambers, and the minimum distance (a) axial in the axial direction from the upper end part of the outer cylinder opening hole part to the upper end part of the inner cylinder, is ≥0.25 times of the size (b) of the outer cylinder opening hole part in the axial direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a converter bottom blowing gas distribution device installed in a bottom blowing converter or an upper bottom blowing converter and capable of equally dividing a gas or a solid-gas two-phase fluid into a plurality of tuyere at the bottom of the converter. About.

In order to adjust the components of the molten steel, for example, a converter 2 as shown in FIG. 2 is installed in a steelmaking factory. In general, tuyeres 3 are provided at multiple locations on the bottom of the converter to satisfy performance such as good agitation of the molten steel M by the bottom blowing gas F, small furnace body vibration, and no spitting. It is. Below the converter bottom, a converter bottom blowing gas distribution device is installed.
In converter refining, which is equipped with a converter for blowing converter bottom gas, a gas or solid-gas two-phase fluid such as pure oxygen, inert gas or mixed gas from a plurality of tuyere 3 at the converter bottom Is blown through the distribution device 1. The powder blown from the plurality of tuyere at the bottom of the converter together with the gas is a solid acting as a flux such as quicklime and fluorite, and the particle size is relatively coarse with a particle size of 40 μm or more accounting for 50 wt% or more.

  When a gas or solid-gas two-phase fluid is blown from a plurality of tuyere 3 at the bottom of the converter, if the distribution of the solid-gas two-phase fluid including the powder distribution is large between tuyere, Not only can the smelting performance not be obtained, but also at the tuyere 3 where the flow rate of the bottom blowing gas F is large, the wear proceeds quickly due to the promotion of the hot spot reaction and the increase in wear due to the powder. If the tuyere wear due to the powder progresses quickly, it is necessary to repair not only the tuyere but also the entire converter bottom. For this reason, when the solid-gas two-phase fluid is blown from the plurality of tuyere 3 at the bottom of the converter, it is desired that not only the gas volume is equal but also the powder distribution is equal between the tuyere.

Here, the structure of a converter bottom blowing gas distributor installed below the converter bottom will be described with reference to the drawings. FIG. 3 is a perspective view showing an external appearance of a converter bottom blowing gas distribution device 1 to which the present invention is applied, and FIG. 4 is a perspective view showing the inside of the converter bottom blowing gas distribution device 1 to which the present invention is applied.
In FIG. 3, 5 indicates an inflow pipe connected to the outer cylinder 4. In FIG. 4, R indicates a swirl flow generated by the inflow flow I flowing into the gas swirl chamber 9 from the outer cylinder opening 8.

The gas swirl chamber 9 in which the swirl flow R is generated includes an outer cylinder 4 with a lid in which an outer cylinder opening 8 is formed, and an inner cylinder 6, and the lower end of the inner cylinder 6 is connected to a plurality of compartments. Yes. An inflow pipe 5 is connected to the outer cylinder 4. 7 indicates a compartment partitioned for each tuyere. Connected to each compartment 7 is a connecting pipe for air-transporting the gas or solid-gas two-phase fluid after distribution by the distribution device 1 to the tuyere.
In the converter bottom blowing gas distribution apparatus 1 having such a structure, when a gas or a solid-gas two-phase fluid is supplied to the inflow pipe 5, as shown in FIG. A swirl flow R is generated by the inflow flow I flowing in. The swirl flow R formed in the gas swirl chamber 9 flows into the inner cylinder 6 while swirling the upper end of the inner cylinder 6, then descends while swirling in the inner cylinder 6, and then flows into the plurality of compartments 7. Then, it is ejected as bottom blowing gas F from the tuyere 3 into the converter 2 through the connecting pipe connected to the compartment 7.

Therefore, when the gas or solid-gas two-phase fluid is blown from the plurality of tuyere 3 at the bottom of the converter, the distribution of gas or solid-gas two-phase fluid is biased for each compartment 7 of the converter bottom blowing gas distributor 1. If it is large, problems will arise in the refining of the converter and the bottom life of the converter.
By the way, the distribution apparatus which can equalize solid-gas two-phase fluid is disclosed (patent documents 1, 2, and 3). Patent Document 1 discloses a powder supply device in which an orifice made of a material sufficiently durable to powder wear is attached to each tuyere in the middle of a distributor or a pipe downstream of the distributor. 2 and 3 disclose an axisymmetric-shaped air-transporting granular material distribution device.
JP 2001-304773 A JP 58-69620 A Japanese Patent Laid-Open No. 58-216829

However, although Patent Document 1 shows a structure in which an orifice is attached to each tuyere, a converter bottom blowing gas capable of evenly dividing a solid-gas two-phase fluid into a plurality of tuyere at the bottom of the converter. The structure of the dispensing device 1 itself is not shown.
Moreover, the airflow distribution apparatus of patent document 2, 3 is an apparatus suitable for airflow-transporting pulverized coal and coke powder to the tuyere part of a blast furnace, and the converter as demonstrated in FIG. It is difficult to apply to a bottom blowing gas distribution device.

  In view of the above-mentioned problems of the prior art, the present invention is installed in a bottom blown converter or an upper bottom blown converter, and can divide a gas or a solid-gas two-phase fluid into a plurality of tuyere at the bottom of the converter. It is an object of the present invention to provide a converter for blowing converter bottom blowing gas.

  In order to solve the above problems, the inventors have conducted numerical experiments by changing the dimensions of each part of the distributor itself, and as a result, interference between the swirl flow generated in the gas swirl chamber and the inflow flow from the inflow pipe. The solid-gas two-phase fluid can be evenly divided into a plurality of lower compartments, and the interference between the swirling flow and the inflowing flow in the gas swirl chamber It has been found that this can be realized by optimizing the positional relationship with the upper end of the cylinder, and the following invention has been made.

  The present invention provides a converter bottom blowing gas distribution device in which a gas swirl chamber having an outer cylinder and an inner cylinder is arranged at the upper portion, and a plurality of compartments divided for each tuyere are arranged at the lower portion thereof. An outer cylinder opening for connecting an inflow pipe is provided on a side wall of the outer cylinder, an upper end of the inner cylinder is opened in the outer cylinder, and a lower end thereof is connected to a plurality of compartments, from an upper end of the outer cylinder opening. The converter bottom blown gas distribution device is characterized in that the minimum axial distance a to the upper end of the inner cylinder is 0.25 times or more the axial dimension b of the outer cylinder opening.

  According to the converter bottom blowing gas distribution device according to the present invention, interference between the swirl flow generated in the gas swirl chamber and the inflow flow from the inflow pipe is reduced, and the solid gas two-phase is provided in the plurality of lower compartments. It becomes possible to equalize the fluid. As a result, by installing it in the bottom blown converter or top bottom blown converter, gas or solid-gas two-phase fluid can be evenly divided into multiple tuyere at the bottom of the converter, and uneven wear between tuyere Can be suppressed, and the lifetime of the furnace bottom can be maximized.

Hereinafter, the structure of the converter bottom blowing gas distribution device according to the present invention will be described. The basic structure of the distribution device according to the present invention is the same as that of the conventional distribution device 1 described with reference to FIGS. That is, the gas swirl chamber 9 having the outer cylinder 4 and the inner cylinder 6 is arranged at the upper part, and a plurality of compartments 7 divided for each tuyere are arranged at the lower part. The upper end of the inner cylinder 6 opens into the outer cylinder, and the lower end thereof is connected to the plurality of compartments 7.

The inflow pipe 5 is connected to the outer cylinder opening 8 of the gas swirl chamber 9 in a direction along the inner peripheral surface of the outer cylinder 4, and the inflow flows into the gas swirl chamber 9 from the outer cylinder opening 8. The swirl flow R is generated by the flow I.
The feature of the present invention is that the positional relationship between the outer cylinder opening 8 and the upper end of the inner cylinder 6 is as follows. That is, as shown in FIG. 1, the entire outer cylinder opening 8 is located on the side of the compartment 7 from the upper end of the inner cylinder 6, that is, below the upper end of the inner cylinder 6. This is a distribution device 1 in which the minimum axial distance a from the upper end to the upper end of the inner cylinder 6 is 0.25 or more of the axial dimension b of the outer cylinder opening 8.

  In FIG. 1A, the positional relationship (a / b) between the outer cylinder opening 8 and the upper end of the inner cylinder 6 affects the uniformity (Max (abs (residual / average)) of bottom blowing gas distribution. 1B is a cross-sectional view of a main part for explaining the positional relationship, and FIG. 1B is also a YY vertical cross-sectional view of FIG. The circumferential position of the longitudinal section is the position where the axial distance from the upper end of the outer cylinder opening 8 to the upper end of the inner cylinder 6 is minimum.

The numerical experiment was performed by changing the dimensions of each part of the distribution device 1 as follows (refer to the example for the dimension conditions of each part). In the case of only gas that does not contain powder (oxygen gas) and in the case of a solid-gas two-phase fluid that contains powder, fluid simulation is performed. Thus, it was evaluated by (Max (abs (residual / average)).
The gas flow allocated to each of the plurality of lower compartments 7 is measured, and the difference in the gas flow rate in each compartment 7 with respect to the average flow rate is defined as a residual (= gas flow rate in each compartment−average flow rate). Among the absolute values obtained by dividing the difference by the average flow rate, the maximum value was defined as (= Max (abs (residual / average)).

As is apparent from FIG. 1 (a) showing the result, when a gas swirl chamber having a / b of 0.25 or more is used, a plurality of lower compartments are provided as compared with a gas swirl chamber having a smaller value than that. It can be seen that the solid-gas two-phase fluid can be evenly distributed.
However, fluid simulation in the case of a solid-gas two-phase fluid containing powder assumes that the powder is uniformly distributed in the gas and the behavior of the solid-gas two-phase fluid is the same as that of the gas only. I went. Specifically, the average density of the solid-gas two-phase fluid = the density of the gas + LLD (Lime Load Factor), and LLD = 1.43.

Next, the operation of the converter bottom blowing gas distribution apparatus 1 having the above-described structure will be described with reference to FIGS.
Since the inflow flow I flowing into the gas swirl chamber is along the direction along the inner peripheral surface of the outer cylinder 4, an angular momentum is given to the gas flow in the upper gas swirl chamber, and the outer cylinder opening 8 is entirely inside. Since it is below the upper end of the cylinder 6, a stable swirl flow R is formed. When the minimum axial distance a from the upper end of the outer cylinder opening 8 to the upper end of the inner cylinder 6 is 0.25 or more of the axial dimension b of the outer cylinder opening 8, the interference between the swirling flow R and the inflow flow I is As a result, the swirl flow R becomes a nearly axisymmetric flow.

And since the shape of the inner cylinder 6 and each compartment 7 is axisymmetric, after flowing down to the inside of the inner cylinder 6, there is no difference in the gas flow. The same applies when the inflow I is a solid-gas two-phase fluid. As a result, the solid-gas two-phase fluid can be divided into the plurality of lower compartments 7.
In the converter bottom blowing gas distribution device 1 according to the present invention, the number of inflow pipes connected to the side wall of the outer cylinder 4 is not limited to one, and the same effect can be obtained by using a plurality of inflow pipes.

  On the other hand, if the upper end of the outer cylinder opening 8 is located above the upper end of the inner cylinder 6 or if a / b is less than 0.25, the swirl flow generated in the gas swirl chamber and the inflow flow from the inflow pipe Disturbance of the swirl flow increases due to the interference. For this reason, local bias occurs in the solid-gas two-phase fluid distributed to the plurality of lower compartments 7.

(Dimensions of converter bottom blowing gas distributor 1)
The inner diameter of the outer cylinder 4 is 900 mm, the total height of the distributor 1 is 750 mm, the minimum axial distance a from the upper end of the outer cylinder opening 8 to the upper end of the inner cylinder 6 is 120 mm, and the axial dimension b of the outer cylinder opening 8 is b = Numerical values based on the above fluid simulation with case A with 300 mm and a / b = 0.4, and case B with a = -60 mm and axial dimension b = 300 mm and a / b = -0.2 The experiment was conducted. The number of compartments 7 was set to 18.

  As a result, the case A with a / b = 0.4 was able to equalize the solid-gas two-phase fluid into the plurality of lower compartments as compared with the case B with a / b = −0.2.

The inner diameter of the outer cylinder 4 = 800 mm to 1000 mm, the total height of the distributor 1 = 600 mm to 900 mm, the minimum axial distance a = 0 mm to 240 mm from the upper end of the outer cylinder opening 8 to the upper end of the inner cylinder 6, the outer cylinder opening 8 The axial dimension of b = 240mm ~ 360mm. The numerical experiment by the above fluid simulation was performed with a / b = 0 to 1.0 and the number of compartments 7 = 18.
As a result, when the gas swirl chamber having a / b of 0.25 or more is used, the solid-gas two-phase fluid can be evenly distributed to the plurality of compartments as compared with the gas swirl chamber having a / b of less than 0.25. In both Examples 1 and 2, the inflow conditions were 5 kg / cm ² G, the flow rate was 670 Nm ³ / min, and the outflow gas pressure was adjusted so that the inflow flow pressure was 5 kg / cm ² G.

  When the gas is blown from each tuyere 3 at the bottom of the actual converter, the gas is reduced to a predetermined pressure from the gas holder through the pressure reducing valve, and the gas having a predetermined flow rate through the flow rate adjusting valve passes through the rotary joint. It is supplied to the inflow pipe 5. When the powder is blown together with the gas from each tuyere 3 at the bottom of the converter, the powder is cut out by a quantitative cutting device (not shown), mixed with the gas, and supplied to the inflow pipe 5 as a solid-gas two-phase fluid.

(A) is a graph which shows the influence which the positional relationship of an outer cylinder opening part and the upper end of an inner cylinder has on the uniformity of bottom blowing gas distribution, (b) is principal part sectional drawing explaining the positional relationship. It is sectional drawing which illustrates the blowing system of converter bottom blowing gas. It is a perspective view of the distribution apparatus of the converter bottom blowing gas to which this invention is applied. It is a perspective view which shows the inside of the distribution apparatus of the converter bottom blowing gas to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Distributor 2 Converter 3 tuyere 4 Outer cylinder 5 Inflow pipe 6 Inner cylinder 7 Compartment 8 Outer cylinder opening 9 Gas swirl chamber F Bottom blowing gas M Molten steel R Swirling flow I Inflow a From the upper end of outer cylinder opening Minimum axial distance to the upper end of the inner cylinder b Axial dimension of the outer cylinder opening

Claims (1)

In the converter bottom blowing gas distribution device, in which a gas swirl chamber having an outer cylinder and an inner cylinder is arranged at the upper part, and a plurality of compartments divided for each tuyere are arranged at the lower part thereof,
The upper end of the inner cylinder opens into the outer cylinder, the lower end thereof is connected to a plurality of compartments, and an outer cylinder opening for connecting an inflow pipe is provided on the side wall of the outer cylinder, from the upper end of the outer cylinder opening A converter bottom blowing gas distribution device, wherein a minimum axial distance a to the upper end of the inner cylinder is 0.25 times or more of an axial dimension b of the outer cylinder opening.

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