JP2009293096A - Method for injecting bottom-blowing agitation gas in melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for injecting bottom-blowing agitation gas in a melting furnace by which in injection of the bottom-blowing agitation gas for agitating molten metal into the melting furnace, strong swiveling flow is generated in the molten metal in the melting furnace thereby the molten metal is sufficiently agitated. <P>SOLUTION: On a furnace bottom wall of the melting furnace, four or more bottom-blowing tuyeres are provided which are arranged at an equal interval on the same circle with the furnace center axis as a center. While the one bottom-blowing tuyere selected from the arranged bottom-blowing tuyeres and having more gas-injecting quantity than those of the others are changed over to the other one successively in the same turning direction, the bottom-blowing agitation gas for agitating the molten metal is injected into the furnace from the whole arranged bottom-blowing tuyeres. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  In the present invention, when a bottom blowing gas for stirring the molten metal is blown into the melting furnace, a strong swirling flow is generated in the molten metal in the melting furnace so that the molten metal can be sufficiently stirred. The present invention relates to a method for blowing a bottom blowing agitation gas in a melting furnace.

  The mainstream of the current ironmaking method is the blast furnace method, but a coal-based reduced iron production method is known as a future ironmaking method. As a coal-based reduced iron production method, a compacted body made of powdered ore and powdered coal is preliminarily reduced in a rotary hearth furnace to obtain reduced iron, and this reduced iron is continuously supplied to an iron bath melting furnace while maintaining a high temperature. The finely divided carbon material supplied as a fuel and a reducing agent is burned with excess oxygen for secondary combustion, and the reduced iron is refined and reduced to obtain a molten iron (pig iron) It has been known.

  By the way, generally, in melting using a molten metal bath, such as melting of reduced iron in the iron bath melting furnace, the melting rate is improved by generating a swirling flow in the molten metal and stirring the molten metal. Can do.

  Here, as a conventional technique for generating the swirling flow, for example, there is a bottom blowing tuyere disclosed in Japanese Patent Application Laid-Open No. 2006-274364. 9 is a perspective view schematically showing an example of the upper end surface of the bottom blowing tuyere in the bottom blowing tuyere according to the prior art, and FIG. 10 is an enlarged side view showing the vicinity of the opening of the flow channel in FIG. .

  The bottom blowing tuyere according to this prior art is a bottom blowing tuyere disposed at the bottom of a refining vessel for containing and refining molten metal, and blows refining gas into the refining vessel. As shown in FIG. 10, two or more flow channels 52 for refining gas are formed in a tubular shape in a tuyere refractory 51 formed in a cylindrical shape (FIG. 9 shows an example in which six flow channels 52 are provided. The flow path 52 is opened at the upper end surface of the tuyere refractory 1, and is the center of the opening of the flow path 52 on the circumference around the central axis CL 1 of the tuyere refractory 51. The opening center points Cp are arranged at equal intervals, and the inclination angle α formed by the vertical line passing through the opening center point Cp and the center axis CL2 of the flow path 52 is in the range of 10 to 45 ° at all the opening center points Cp. It is the bottom blown tuyere. The center axis CL2 of the refining gas flow path 52 is preferably in the tangential direction of the circumference CA where the opening center point Cp is arranged in plan view.

  FIG. 11 is a cross-sectional view schematically showing an example in which a refining gas is blown from a bottom blowing tuyere into a molten metal in a refining vessel in a bottom blowing tuyere according to the prior art. The bottom blowing tuyere is arranged so that the upper end surface thereof is exposed on the upper surface of the furnace bottom refractory 55. The refining gas 54 is supplied from the lower part of the bottom blowing tuyere and is blown into the molten metal 53 as bubbles 54 a from the openings through the flow paths 52. Then, the flow path 52 of the refining gas is inclined at a constant inclination angle α with respect to the vertical line at each opening center point Cp, so that the bubbles 54 a of the refining gas 54 blown into the molten metal 53 are generated. A swirling flow SE is formed.

However, in the above-described conventional technology, there is room for improvement in that a strong swirling flow is generated in the molten metal because the gas flow rate per flow path of the refining gas is limited.
JP 2006-274364 A (FIGS. 1 to 3)

  Accordingly, an object of the present invention is to sufficiently stir the molten metal by generating a strong swirling flow in the molten metal in the melting furnace when the bottom blowing stirring gas for stirring the molten metal is blown into the melting furnace. Another object of the present invention is to provide a method for blowing a bottom blowing agitation gas in a melting furnace.

  In order to solve the above problems, the present invention takes the following technical means.

  According to the first aspect of the present invention, four or more bottom blowing tuyere arranged at equal intervals on the same circle centered on the core axis of the furnace are provided on the bottom wall of the melting furnace. A bottom blowing aeration gas for agitating molten metal from all the arranged bottom blowing tuyere while sequentially switching the bottom blowing tuyere with a gas blowing flow rate higher than the other around the tuyere This is a method for blowing a bottom blowing agitation gas in a melting furnace characterized by blowing into the inside.

  According to a second aspect of the present invention, there is provided a method for injecting a bottom blowing agitating gas in the melting furnace according to the first aspect, wherein a plurality of bottom blowing tuyere having a larger gas blowing flow rate than the others among the arranged bottom blowing tuyere. This is characterized in that the number is set.

  The method of blowing the bottom blowing agitation gas in the melting furnace according to the present invention comprises four or more bottom blowing tuyere arranged at equal intervals on the same circle centered on the furnace axis in the furnace bottom wall of the melting furnace. For the agitated molten metal from all the bottom blowing tuyere at the same time while sequentially switching the bottom blowing tuyere with the gas blowing flow rate larger than the other ones in sequence for the arranged bottom blowing tuyere The bottom blowing agitation gas is blown into the melting furnace. As a result, a strong swirling flow can be generated in the molten metal in the melting furnace to sufficiently stir the molten metal, and the melting rate can be improved.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining the method of the present invention, and is a diagram schematically showing an iron bath melting furnace in which eight bottom blowing tuyere are provided on the furnace bottom wall.

As shown in FIG. 1, on the bottom wall 10 a of the iron bath melting furnace 10, eight pieces from the first to the eighth in this example are equally spaced on the same circle centered on the furnace axis. bottom tuyeres ₁₁ 1 to 11 ₈ is provided for. Bottom tuyeres 11 ₁ to 11 _8, tuyere axial line extending in the vertical direction is provided so as to be parallel with the furnace axial line.

  FIG. 2 shows one bottom blowing tuyere (indicated by black circles) in which the gas blowing flow rate is higher than the others in the eight bottom blowing tuyere arranged on the bottom wall of the iron bath melting furnace shown in FIG. It is a top view for demonstrating setting and switching the said bottom blowing tuyere sequentially around the same.

The method of the present invention, in the example shown in FIG. 2, the gas blowing rate of bottom-blown agitation for a gas for the bottom tuyeres 11 ₁ to 11 ₈ are arranged in Rosokokabe 10a (inert gas such as N ₂ gas) One bottom blowing tuyere with more than the others is set, and as shown in FIG. 2, the bottom blowing tuyere is sequentially switched in the same direction (clockwise in the illustrated example), so that blowing bottom-blown agitation gas to the bottom-blown tuyeres 11 ₁ to 11 ₈ iron bath type melting furnace 10 from. Thereby, a strong swirling flow can be generated in the molten iron in the iron bath melting furnace 10 to sufficiently stir the molten iron, and the melting rate can be improved.

  Here, in the present invention, it is necessary to provide four or more bottom blowing tuyers provided on the bottom wall of the melting furnace in order to generate a swirling flow in the molten metal in the melting furnace. The number of bottom blowing tuyere provided on the bottom wall of the furnace is in the range of 4 to 8 in terms of the complexity of the structure due to the increase in the number of tuyere and the effect of swirling flow, although it depends on the capacity of the melting furnace to be applied. Is good.

  In the method of the present invention, a plurality of bottom blowing tuyere with a gas blowing flow rate higher than the others is set, for example, two or three, and the bottom blowing tuyere is sequentially switched around the same. It is also possible to make it. In this case, as shown in FIGS. 3 and 4 to be described later, the number of bottom blowing tuyere located between the bottom blowing tuyere (shown by black circles in FIGS. 3 and 4) having a higher gas blowing flow rate than others. It is preferable to set the position of the bottom blowing tuyere where the gas blowing flow rate is higher than the others so that the number becomes substantially the same.

  FIG. 3 shows two bottom blowing tuyere (indicated by black circles) in which the gas blowing flow rate is higher than the others in the eight bottom blowing tuyere arranged on the bottom wall of the iron bath melting furnace shown in FIG. It is a top view for demonstrating setting and switching the said bottom blowing tuyere sequentially around the same.

The method of the present invention, in the example shown in FIG. 3, bottom-blown feather the gas blowing rate of the stirring gas bottom blowing the bottom-blown tuyeres 11 ₁ to 11 ₈ are arranged in Rosokokabe 10a was larger than the other Two mouths are set instead of one, and as shown in FIG. 3, all the bottom blowing feathers are simultaneously changed while repeating the bottom blowing tuyere sequentially in the same direction (clockwise in the illustrated example). so that blowing bottom-blown agitation gas to the mouth 11 ₁ to 11 ₈ iron bath type melting furnace 10 from. As a result, a strong swirling flow can be generated more reliably in the molten iron in the iron bath melting furnace 10 than in the case of FIG. 2, and the molten iron can be sufficiently stirred, thereby improving the melting rate. Can do.

  FIG. 4 shows three bottom blowing tuyere (indicated by black circles) in which the gas blowing flow rate is higher than the others in the eight bottom blowing tuyere arranged on the bottom wall of the iron bath melting furnace shown in FIG. It is a top view for demonstrating setting and switching the said bottom blowing tuyere sequentially around the same.

The method of the present invention, in the example shown in FIG. 4, bottom-blown feather the gas blowing rate of the stirring gas bottom blowing the bottom-blown tuyeres 11 ₁ to 11 ₈ are arranged in Rosokokabe 10a was larger than the other Three mouths are set, and as shown in FIG. 4, all the bottom blowing tuyere 11 _{1 to} 11 11 are simultaneously switched while repeating the sequential switching of the bottom blowing tuyere in the same direction (clockwise in the illustrated example). _A bottom-blown stirring gas is blown into the iron bath melting furnace 10 from ₈ . As a result, a strong swirling flow can be generated more reliably in the molten iron in the iron bath melting furnace 10 than in the case of FIG. 2, and the molten iron can be sufficiently stirred, thereby improving the melting rate. Can do.

  FIG. 5 is a perspective view schematically showing a state where a stirring gas blowing apparatus for carrying out the method of the present invention is provided in an iron bath melting furnace.

As shown in FIG. 5, the lower surface of the furnace bottom wall 10a of the iron bath type melting furnace 10, the bottom tuyeres ₁₁ 1 to 11 total are connected to each of the ₈ 8 pieces of the gas blowing nozzle pipe ₁₂ 1 to 12 ₈ is attached. The stirring gas blowing device 20 has a hollow cylindrical shape, and the gas blowing nozzle tubes 12 _{1 to} 12 ₈ are connected to the circumferential wall of the stirring gas blowing device 20, and an outer fixed container into which high pressure bottom blowing stirring gas is introduced from the outside. 30, no an inverted cup-shaped, rotatably disposed while sliding on the outer fixed vessel 30 peripheral surface to the outer stationary container 30, its circumference wall, the gas blowing gas for the nozzle pipe 12 ₁ to 12 ₈ while the gas blowing nozzle pipe and the supply flow rate was more than any other sequentially switched in the same round, for supplying the introduced bottom-blown agitation gas to the nozzle pipe 12 ₁ to 12 ₈ blowing all of the gas at the same time An inner rotating body 40 having a predetermined number of openings and a rotation driving device 50 that rotates the inner rotating body 40 in the same direction are configured.

  6 is a perspective view schematically showing the configuration of the stirring gas blowing device shown in FIG. 5, FIG. 7 is a perspective view schematically showing the configuration of the outer fixed container in FIG. 6, and FIG. 8 is an inner rotating body in FIG. It is a perspective view which shows the structure of no.

6 and 7, the circumferential wall of the outer stationary container 30 which forms a hollow cylindrical, equally spaced eight for the nozzle pipe connecting opening 31 _{1-31 8} in the circumferential direction is formed cage, in accordance with the these openings ₃₁ 1 to 31 _8, the nozzle pipe ₁₂ 1 to 12 ₈ blowing the eight gas of the same size are connected. Further, a gas introduction pipe 32 for introducing a high-pressure bottom-blown stirring gas into the outer fixed container 30 is connected to the circumferential wall of the outer fixed container 30.

As shown in FIG. 6, an inner rotating body 40 having an inverted cup shape that rotates while sliding on the inner peripheral surface of the outer fixed container 30 is provided in the outer fixed container 30. On the circumferential wall of the inner rotating body 40, as shown in FIG. 8, a circumference is formed corresponding to the positions of the _eight nozzle tube connection openings 31 _{1 to} 318 formed in the outer fixed container 30. eight openings ₄₁ 1 to 41 ₈ at regular intervals are formed in the direction.

These openings ₄₁₁ to 41 _8, as shown in FIG. 8, six small apertures ₄₁ 2 _{to 41 4,} 41 6 and to 41 _8, two large openings formed in the pair of opposing positions It consists of parts 41 ₁ and 41 ₅ . Small openings _{41 2-41} 4 ₄₁ 6-41 _8, as shown in FIG. 6, so that the nozzle pipe connecting opening ₃₁ 1-31 ₈ of the outer stationary container 30, for example, to about half open size Is formed. Moreover, large openings ₄₁ 1, 41 _5, as shown in FIG. 6, the nozzle pipe connecting opening ₃₁ 1-31 ₈ is formed to a size that will let completely open.

  Further, a cross-shaped frame 42 is fixed to the lower end portion of the inner rotary body 40, and is rotationally driven by the rotary drive device 50 provided below the outer fixed container 30 at the axial center portion of the cross-shaped frame 42. The rotating shaft 43 is coupled.

  In the stirring gas blowing apparatus 20 configured as described above, a high-pressure bottom blowing stirring gas is introduced into the outer fixed container 30 from the gas introduction pipe 32. In the outer fixed container 30, the inner rotating body 40 is continuously rotated at a predetermined constant speed, for example, clockwise by the rotation driving device 50. The bottom blowing agitation gas introduced into the outer fixed container 30 is guided into the inner rotating body 40 from the bottom opening portion by the cross-shaped frame 42.

Then, the inner rotary body 40, the openings ₄₁ 1 to 41 ₈ are formed on the circumferential wall. Therefore, with the rotation of the inner rotary body 40, gas agitation bottom blowing the bottom-blown tuyere ₁₁ 1 to 11 ₈ via the nozzle pipe ₁₂ 1 to 12 ₈ blown gas is supplied, and, in this example, the as shown in FIG. 3, the bottom tuyeres 11 ₁ to 11 ₈ two bottom tuyeres a gas blowing flow rate of bottom-blown agitation gas was more than others for, while repeatedly sequentially switching it clockwise , so that the all of the bottom tuyeres 11 ₁ to 11 ₈ bottom iron bath type melting furnace 10 from the blowing stirring gas at the same time is blown. Thereby, a strong swirling flow can be generated in the molten iron in the iron bath melting furnace 10, the molten iron can be sufficiently stirred, and the melting rate can be improved.

It is a figure for demonstrating the method of this invention, Comprising: It is a figure which shows schematically the iron bath type melting furnace provided with eight bottom blowing tuyere on the furnace bottom wall. One bottom blowing tuyere (indicated by black circles) having a gas blowing flow rate higher than the others is set in the eight bottom blowing tuyere arranged on the bottom wall of the iron bath melting furnace shown in FIG. It is a top view for demonstrating switching a bottom blowing tuyere sequentially around the same. Two bottom blowing tuyere (indicated by black circles) having a gas blowing flow rate higher than the others are set in the eight bottom blowing tuyere arranged on the bottom wall of the iron bath melting furnace shown in FIG. It is a top view for demonstrating switching a bottom blowing tuyere sequentially around the same. In the eight bottom blowing tuyere arranged on the bottom wall of the iron bath melting furnace shown in FIG. It is a top view for demonstrating switching a bottom blowing tuyere sequentially around the same. It is a perspective view which shows roughly the state with which the gas blowing apparatus for stirring for implementing the method of this invention is equipped with the iron bath type melting furnace. It is a perspective view which shows roughly the structure of the gas blowing apparatus for stirring shown in FIG. It is a perspective view which shows schematically the structure of the outer side fixed container in FIG. It is a perspective view which shows roughly the structure of the inner side rotary body in FIG. It is a perspective view which shows typically the example of the upper end surface of a bottom blowing tuyere in the bottom blowing tuyere by a prior art. It is a side view which expands and shows the opening part vicinity of the flow path in FIG. It is sectional drawing which shows typically the example which blows refinement gas from the bottom blow tuyeres to the molten metal in the refining container in the bottom blow tuyeres by a prior art.

Explanation of symbols

10 ... iron bath type melting furnace 10a ... Rosokokabe ₁₁ 1 to 11 8 _... bottom tuyeres ₁₂ 1 to 12 8 _... gas blowing nozzle pipe 20 ... gas stirrer injectors 30 ... outer fixed container ₃₁ 1-31 ₈ ... Nozzle pipe connection opening 32... Gas introduction pipe 40... Inner rotor 41 ₁ , 41 ₅ ... Large opening 41 _{2 to} 41 ₄ , 41 _{6 to} 41 ₈ ... Small opening 42. 50. Rotation drive device

Claims (2)

  The bottom wall of the melting furnace is provided with four or more bottom blowing tuyere arranged at equal intervals on the same circle centered on the furnace axis, and the gas blowing flow rate is set for the arranged bottom blowing tuyere. It is characterized in that bottom blowing agitating gas for stirring molten metal is blown into the melting furnace from all the arranged bottom blowing tuyere while sequentially switching the number of bottom blowing tuyeres more than others in the same direction. A method of blowing a gas for bottom blowing stirring in a melting furnace.   2. A plurality of bottom blowing tuyere having a larger gas blowing flow rate than the others among the arranged bottom blowing tuyere are set. Method.

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