Agitator with molten iron KR desulfurization agent emission suppression and use method

Abstract

The present invention discloses an agitator with molten iron KR desulfurization agent emission suppression and a method of using the agitator, comprising an agitator body and a suppression device installed on the agitator body, the suppression device comprising a hub, a plurality of rotating blades uniformly distributed circumferentially around the outer wall surface of the hub, and a refractory heat-insulating coating coated on the rotating blades and the hub surface; each rotating blade comprises a blade root and a fan blade, the fan blade is connected and fixed to the outer side surface of the blade root, the fan blade is arranged in an inclined installation, and the inclination direction is the same as the rotation direction of the agitator body; the axial height of the hub is the same as the axial height of the blade root or is 50 to 100 mm higher than the axial height of the blade root. By adding a dispersion suppression device to the agitator shaft of the existing molten iron KR agitator, the existing agitator is newly provided with a function of suppressing the emission of desulfurization agent, thereby achieving the comprehensive purposes of suppressing the emission and escape loss of dust during the addition of desulfurization agent, improving the reaction utilization rate of desulfurization agent, and improving the technical and economic indicators of molten iron desulfurization.

Description

Technical Field

[0001] The invention relates to the technical field of molten iron pretreatment, and in particular to an agitator capable of suppressing the escape of a molten iron KR desulfurizing agent and a use method thereof. Background Art

[0002] The molten iron KR mechanical stirring desulfurization process uses a single-layer cross-arranged agitator with rectangular or inverted right-angled trapezoidal blades immersed in the molten iron to rotate and stir. The telescopic feeding chute arranged downward and inclined passes through the opening of the dust removal hood and extends above the stirring vortex liquid surface of the molten iron tank. The desulfurizer is added to the molten iron stirring vortex liquid surface by the gravity of the desulfurizer or the injection of the carrier gas. The desulfurizer is stirred, entrained and mixed on the molten iron liquid surface to achieve desulfurization reaction at the interface between the desulfurizer and the molten iron. Therefore, it has excellent desulfurization reaction kinetics and has become the preferred process for deep desulfurization of molten iron.

[0003] During the KR stirring desulfurization process of molten iron, the high temperature of the molten iron, which can reach nearly 1500℃, leads to strong natural convection of air in the space above the molten iron surface. During the desulfurizer addition process, the strong natural convection rising flow field above the liquid surface carries a large amount of desulfurizer particles to float and escape, especially the fine desulfurizer powder with fine particle size. Although the strong suction negative pressure of the dust removal exhaust port of the splash shield suppresses the environmental pollution caused by the dust emission of the desulfurizer to the operating platform, the dust extraction and escape of the desulfurizer is increased, which not only reduces the effective utilization rate of the desulfurizer and increases the consumption of the desulfurizer, but also increases the dust removal load and operation cost of the dust removal system. Although increasing the desulfurizer particle size and reducing the desulfurizer fine powder content reduces the amount of desulfurizer entrained in the air flow and escapes, and increasing the desulfurizer molten iron stirring entrainment rate, the purpose of reducing desulfurizer consumption and dust environmental pollution has been achieved, but for the interface reaction form of lime particle surface contact in molten iron KR desulfurization, the increase of desulfurizer particles will lead to a sharp decrease in the specific surface area of ​​lime particles, a decrease in the effective utilization rate of desulfurizer, and an increase in desulfurizer consumption. This is also one of the main reasons for the significant differences in the particle size range and desulfurizer consumption of molten iron KR desulfurizers from different companies. In addition, the gravity feeding method of the telescopic feeding chute of the desulfurizer has the problems of easy clogging of the feeding pipe and unstable feeding speed, which not only affects the stability of the operation of the molten iron KR stirring desulfurization process, but also the desulfurizer accumulated in the telescopic feeding chute instantly falls down, which also aggravates the escape of the desulfurizer and the escape of dust removal suction and the accumulation of the liquid surface in the center of the stirring vortex, worsening the dust pollution in the operating environment, increasing the loss of the desulfurizer, and reducing the reaction interface area of ​​the desulfurizer. This is also the main reason why many steel companies use blowing carrier gas to carry out desulfurizer injection and feeding transformation. Through the high-pressure carrier gas acceleration of the desulfurizer, the injection speed and kinetic energy of the desulfurizer are increased, the aggregation of the desulfurizer is suppressed, and the ability to resist the escape of air flow is enhanced, so as to achieve the purpose of reducing the particle size of the desulfurizer and increasing the reaction interface area of ​​the desulfurizer. However, active lime is easy to be pulverized by moisture and has low strength. It is easy to be pulverized during the stirring, mixing and conveying process. The dust emission and dust removal suction escape of the desulfurizer fine powder are still very obvious, which also limits the degree of reduction of the desulfurizer particle size. It can be seen that how to reduce the dust emission and dust suction escape during the addition process of KR desulfurizer in molten iron has become one of the important technical ways to reduce the consumption of desulfurizer, improve the technical and economic indicators of desulfurization and achieve stable deep desulfurization of molten iron. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned technology and provide a stirrer and a method of use with the function of suppressing the escape of KR desulfurizer in molten iron, so as to achieve the comprehensive goals of suppressing the escape and loss of dust in the process of adding desulfurizer, improving the reaction utilization rate of desulfurizer, and improving the technical and economic indicators of molten iron desulfurization.

[0005] To achieve the above-mentioned purpose, the present invention provides an agitator with KR desulfurizer emission suppression function for molten iron, comprising an agitator body and a suppression device installed on the agitator body, the suppression device comprising a hub, a plurality of rotating blades uniformly distributed circumferentially around the outer wall surface of the hub, and a refractory heat-insulating coating coated on the rotating blades and the hub surface; each rotating blade comprises a blade root and a fan blade, the fan blade is connected and fixed to the outer side surface of the blade root, the fan blade is installed in an inclined manner, and the inclination direction is the same as the rotation direction of the agitator body; the axial height of the hub is the same as the axial height of the blade root or is 50 to 100 mm higher than the axial height of the blade root.

[0006] Furthermore, the blade root is an arc-shaped steel plate, the fan blades are arc-shaped fan blades or straight fan blades, the arc-shaped fan blades or straight fan blades are installed and arranged obliquely, the inclination direction is the same as the rotation direction of the agitator body, and the inclination angle α is 5 to 25°.

[0007] Furthermore, the arc-shaped steel plate has an axial height of 150 to 200 mm and a thickness of 8 to 16 mm.

[0008] Furthermore, the number of the rotating blades is 3 to 5.

[0009] Furthermore, the coating thickness of the fire-resistant heat-insulating coating is 2 to 5 mm.

[0010] Furthermore, the inner wall of the hub is coaxially welded and fixed to the metal stirring shaft of the stirrer through a plurality of connecting steel bars.

[0011] Furthermore, the distance L between the upper end surface of the hub and the lower end surface of the agitator connecting flange is 500-1000 mm.

[0012] Furthermore, the number of the connecting steel bars is 6 to 12.

[0013] Furthermore, the raw materials of the fire-resistant heat-insulating coating include, by weight percentage: 10-15% fly ash beads, 5-10% thermosetting phenolic resin, 2-3% thermoplastic phenolic resin, 35-50% sintered mullite fine powder, 5-10% low-melting point glass powder, 5-8% sintered magnesia fine powder, α-Al 2 O 3 Micro powder 5-8%, silicon dioxide micro powder 3-5%, explosion-proof fiber 0.1-0.2% and ferric nitrate 0.05-0.15%, and the balance is ethylene glycol.

[0014] A method for using the stirrer with KR desulfurization agent dissipation suppression as described above is also provided, comprising the following steps:

[0015] 1) According to the design structural size requirements, prepare a circular steel cylinder hub, multiple connecting steel bars and a metal core of the agitator body, and use the connecting steel bars to coaxially weld and connect the hub and the metal core shaft of the agitator;

[0016] 2) The agitator body is transported to the site, hoisted onto the agitator replacement trolley, and then multiple rotating blades are welded and fixed on the outer side of the hub as required;

[0017] 3) Use connecting bolts to install the agitator on the replacement trolley online;

[0018] 4) coating the prepared refractory heat-insulating coating on the outer surface of the rotating blades and the hub according to the coating thickness requirements; and using the molten iron level of the newly launched agitator molten iron tank to suspend and immerse the molten iron to bake, the refractory heat-insulating coating on the outer surface of the rotating blades and the hub is baked;

[0019] 5) Carry out molten iron KR stirring desulfurization production according to the molten iron KR stirring desulfurization process.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: by adding a fugitive emission suppression device to the stirring shaft of the existing molten iron KR agitator, the existing agitator is newly added with a function of suppressing the fugitive emission of the desulfurizer, thereby achieving the comprehensive purposes of suppressing the fugitive emission and escape loss of dust during the desulfurizer addition process, improving the reaction utilization rate of the desulfurizer, and improving the technical and economic indicators of molten iron desulfurization.

[0021] Figure 1 It is a three-dimensional schematic diagram of an agitator with molten iron KR desulfurization agent emission suppression function according to the present invention;

[0022] Figure 2 for Figure 1 Schematic diagram of the top view of the medium suppression device;

[0023] Figure 3 for Figure 2 AA section view of the mid-curved fan blade;

[0024] Figure 4 for Figure 2 AA section view of a medium-inclined straight blade;

[0025] Figure 5 for Figure 1 A schematic diagram of the main view;

[0026] Figure 6 for Figure 5 BB cross-section diagram;

[0027] Figure 7 It is a schematic diagram of the service state of the present invention.

[0028] The components in the figure are numbered as follows:

[0029] Rotating blades 1, blade roots 1.1, fan blades 1.2, wheel hubs 2, fire-resistant heat-insulating coatings 3, connecting steel bars 4, agitator body 5, agitator metal core shaft 5.1, and suppression device 6. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clearer understanding of the present invention, but they do not constitute a limitation on the present invention.

[0031] like Figure 1 , 4 The agitator with the function of suppressing the escape of molten iron KR desulfurizer shown in the figure comprises an agitator body 5 and a suppressing device 6 mounted on the agitator body 5, wherein the suppressing device 6 comprises a hub 2, a plurality of rotating blades 1 uniformly distributed circumferentially around the outer wall surface of the hub 2, and a refractory heat-insulating coating 3 coated on the rotating blades 1 and the hub 2. In this embodiment, the number of rotating blades 1 is 3 to 5. Each rotating blade 1 comprises a blade root 1.1 and a fan blade 1.2; the blade root 1.1 is a circular arc steel plate, the axial height of the circular arc steel plate is 150 to 200 mm, and the thickness is 8 to 16 mm; as shown in FIG. Figure 2 , 3 As shown, the fan blade 1.2 is an arc-shaped fan blade or a straight fan blade, and the arc-shaped fan blade or the straight fan blade is installed and arranged in an inclined manner, and the inclination direction is the same as the rotation direction of the agitator body 5, and the inclination angle α is 5 to 25°; the fan blade 1.2 is welded and fixed to the outer side of the arc-shaped steel plate, and the fan blade 1.2 is made by machining the steel plate, and the thickness of the steel plate is 5 to 8 mm. The hub 2 is a circular steel cylinder, and the axial height is the same as the axial height of the blade root 1.1 or 50 to 100 mm higher than the axial height of the blade root 1.1. In this embodiment, the wall thickness of the hub 2 is 10 to 20 mm. The fire-resistant heat-insulating coating 3 is applied to the surface of the rotating blade 1 and the hub 2, and the coating thickness is 2 to 5 mm.

[0032] like Figure 5 , 6 As shown, the inner wall of the hub 2 is coaxially welded and fixed to the agitator metal stirring shaft 5.1 through multiple connecting steel bars 4. The distance L between the upper end face of the hub 2 and the lower end face of the agitator connecting flange is 500 to 1000 mm. In this embodiment, the number of connecting steel bars 4 is 6 to 12.

[0033] The agitator with molten iron KR desulfurization agent emission suppression of the present invention is connected coaxially and rigidly to the stirring shaft of the agitator body by the suppression device, thereby ensuring the structural integrity of the suppression device and the agitator body, and realizing the addition of an emission suppression device to the existing agitator; during the molten iron KR stirring and desulfurization process, the agitator drives the suppression device blades to rotate coaxially and at the same speed to form a molten iron liquid surface stirring vortex and an axial fan airflow in the space above the liquid surface; through the axial fan airflow blowing to the central area of ​​the molten iron vortex liquid surface, the formation of natural convection rising airflow in the central area of ​​the space above the vortex liquid surface is suppressed, and the molten iron vortex liquid surface is promoted to capture and entrain and mix the contact reaction of the desulfurizer in the central axial flow; further, the suppression device blades rotate to entrain the gas and particulate fine powder in the space area above the molten iron vortex liquid surface, thereby suppressing the emission of the desulfurizer and the dust removal suction escape, and the axial fan airflow blowing to the molten iron vortex liquid surface through the central area is realized. The capture and contact mixing of desulfurizer particle powder in the outer area is achieved; through the continuous rotation of the agitator, the airflow in the space above the molten iron vortex liquid surface and the circulation of the desulfurizer particle fine powder are realized, and the molten iron vortex liquid surface continuously captures and sucks the desulfurizer particle fine powder; through the multi-blade rotating blade structure design of the suppression device fan blade, the flow field intensity of the rotating axial fan of the suppression device is improved, the suppression ability of the natural convection rising airflow in the space above the molten iron vortex liquid surface is increased, and the capture and mixing and dispersion effect of the desulfurizer particle fine powder is improved; through the arc-shaped fan blade or the straight fan blade inclined installation structure design of the rotating blade and the arrangement of the fan blade in the same direction of rotation of the agitator, it is ensured that the fan blade of the suppression device rotates to blow the axial fan airflow of the molten iron vortex liquid surface stably, drive the desulfurizer particle fine powder to move to the molten iron vortex liquid surface, improve the capture rate and suction amount of the molten iron vortex liquid surface of the desulfurizer, suppress the dust emission of the desulfurizer, and reduce the dust removal suction escape loss.

[0034] In addition, the refractory heat-insulating coating 3 is obtained by coating and drying the refractory heat-insulating coating. The raw materials of the refractory heat-insulating coating include, by weight percentage: 10-15% fly ash beads, 5-10% thermosetting phenolic resin, 2-3% thermoplastic phenolic resin, 35-50% sintered mullite fine powder, 5-10% low melting point glass powder, 5-8% sintered magnesia fine powder, α-Al 2 O 3 5-8% of micro powder, 3-5% of silicon dioxide micro powder, 0.1-0.2% of explosion-proof fiber and 0.05-0.15% of ferric nitrate, and the balance is ethylene glycol. The above raw materials are forcibly stirred and mixed by a vertical mixer to obtain the required fire-resistant heat-insulating coating.

[0035] By coating the rotating blades and the outer surface of the hub of the suppression device with fire-resistant heat-insulating coating and its low thermal conductivity, the heating rate of the suppression device under service conditions is reduced, high-temperature oxidation and high-temperature deformation are prevented, and the structural stability and comprehensive strength of the suppression device during service are ensured; by compounding thermosetting and thermoplastic phenolic resins in the fire-resistant heat-insulating coating, the coating baking bonding strength and the integrity of the coating structure during the baking process are improved; by adding low-melting-point glass powder (melting point 400℃), the low-temperature sintering performance of the coating and the secondary film formation of the coating are promoted, the carbonization shrinkage pores of the organic binder during the service process are compensated, the coating bonding strength and structural integrity are improved, medium-temperature oxidation is prevented, the fugitive suppression function is stabilized, and the service life of the suppression device is extended. Cheap, high bonding strength.

[0036] like Figure 7 As shown, the method for using the above-mentioned stirrer with molten iron KR desulfurization agent emission suppression includes the following steps:

[0037] 1) According to the design structural size requirements, prepare a circular steel cylinder hub 2, a plurality of connecting steel bars 4 and a metal core of the agitator body 5, and use the connecting steel bars 4 to coaxially weld and connect the hub 2 and the agitator metal core shaft 5.1;

[0038] 2) The agitator body 5 is transported to the site, hoisted onto the agitator replacement trolley, and then the plurality of rotating blades 1 are welded and fixed on the outer side of the hub 2 as required;

[0039] 3) Use connecting bolts to install the agitator on the replacement trolley online;

[0040] 4) Coating the prepared refractory heat-insulating coating to the outer surface of the rotating blades 1 and the hub 2 according to the coating thickness requirements; and utilizing the hovering and immersion baking opportunity of the molten iron level of the newly-launched agitator molten iron tank to complete the baking treatment of the refractory heat-insulating coating 3 on the outer surface of the rotating blades 1 and the hub 2.

[0041] 5) According to the hot metal KR stirring desulfurization process, hot metal KR stirring desulfurization production is carried out, such as Figure 7 shown.

[0042] Through industrial tests at 200-ton and 300-ton molten iron tank KR stirring desulfurization stations, the desulfurizer consumption per ton of iron was reduced from 7.5Kg to below 6.0Kg, achieving the industrial test effect of reducing the dust emission of desulfurizer and the loss of dust removal and suction escape, and reducing the consumption of desulfurizer.

[0043] The above-mentioned method of use provides a guarantee for the processing, preparation, installation and fixation of the suppression device and its use following the agitator, thereby ensuring the stable and reliable realization of the suppression function of the molten iron KR desulfurizer emission.

Claims

1. A stirrer with the function of suppressing the escape of KR desulfurization agent from molten iron, characterized in that: The invention comprises an agitator body (5) and a suppression device (6) installed on the agitator body (5), wherein the suppression device (6) comprises a hub (2), a plurality of rotating blades (1) uniformly distributed circumferentially around the outer wall surface of the hub (2), and a fire-resistant heat-insulating coating (3) coated on the surface of the rotating blades (1) and the hub (2); each rotating blade (1) comprises a blade root (1.1) and a fan blade (1.2); the fan blade (1.2) is connected and fixed to the outer side surface of the blade root (1.1); the fan blade is arranged to be installed in an inclined manner, and the inclination direction is the same as the rotation direction of the agitator body (5); the axial height of the hub (2) is the same as the axial height of the blade root (1.1) or is 50 to 100 mm higher than the axial height of the blade root (1.1); The inner wall of the hub (2) is coaxially welded and fixed to the metal core shaft (5.1) of the stirrer through a plurality of connecting steel bars (4); the raw materials of the fire-resistant heat-insulating coating include, by weight percentage: 10-15% fly ash floating beads, 5-10% thermosetting phenolic resin, 2-3% thermoplastic phenolic resin, 35-50% sintered mullite fine powder, 5-10% low-melting point glass powder, 5-8% sintered magnesia sand fine powder, 5-8% α-Al2O3 fine powder, 3-5% silica fine powder, 0.1-0.2% explosion-proof fiber and 0.05-0.15% ferric nitrate, and the balance is ethylene glycol.

2. The agitator with the function of suppressing the escape of molten iron KR desulfurizing agent according to claim 1, characterized in that: The blade root (1.1) is an arc-shaped steel plate, and the fan blade (1.2) is an arc-shaped fan blade or a straight fan blade. The arc-shaped fan blade or the straight fan blade are both arranged to be installed in an inclined manner, and the inclination direction is the same as the rotation direction of the agitator body (5). The inclination angle α is 5 to 25°.

3. The agitator with the function of suppressing the escape of molten iron KR desulfurizing agent according to claim 2, characterized in that: The arc-shaped steel plate has an axial height of 150 to 200 mm and a thickness of 8 to 16 mm.

4. The agitator with suppression of molten iron KR desulfurization agent emission according to claim 1, characterized in that: The number of the rotating blades (1) is 3 to 5.

5. The agitator with the function of suppressing the escape of molten iron KR desulfurizing agent according to claim 1, characterized in that: The coating thickness of the fire-resistant heat-insulating coating (3) is 2 to 5 mm.

6. The agitator with suppression of molten iron KR desulfurization agent emission according to claim 1, characterized in that: The distance L between the upper end surface of the hub (2) and the lower end surface of the agitator connecting flange is 500-1000 mm.

7. The agitator with the function of suppressing the escape of molten iron KR desulfurizing agent according to claim 1, characterized in that: The number of the connecting steel bars (4) is 6 to 12.

8. A method for using the stirrer with suppressed evaporation of KR desulfurizer in molten iron as claimed in claim 1, characterized in that: The steps include: 1) According to the design structural dimension requirements, a circular steel cylinder hub (2), a plurality of connecting steel bars (4) and a metal core of the agitator body (5) are prepared, and the hub (2) and the agitator metal core shaft (5.1) are coaxially welded and fixed using the connecting steel bars (4); 2) transporting the agitator body (5) to the site, hoisting it onto the agitator replacement trolley, and then welding and fixing the plurality of rotating blades (1) on the outer side of the hub (2) as required; 3) Use connecting bolts to install the agitator on the replacement trolley online; 4) coating the prepared refractory heat-insulating coating on the outer surface of the rotating blade (1) and the wheel hub (2) according to the coating thickness requirement; and utilizing the suspending and immersion baking opportunity of the molten iron liquid level of the newly launched agitator molten iron tank to complete the baking treatment of the refractory heat-insulating coating (3) on the outer surface of the rotating blade (1) and the wheel hub (2); 5) Carry out molten iron KR stirring desulfurization production according to the molten iron KR stirring desulfurization process.

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