JP3373011B2 - How to use a converter lance - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the use of a lance for blowing a converter.
More particularly, the present invention relates to a method of using a converter blasting lance having a sub-nozzle capable of performing secondary combustion in a furnace without shortening the life of a converter refractory and improving thermal efficiency. [0002] A characteristic of an in-furnace reaction in a converter is a vigorous stirring and rapid reaction of a steel bath caused by a supersonic oxygen jet supplied from a nozzle of a converter blowing lance. . High-purity, high-energy gas-oxygen flow causes a gas-steel bath reaction typified by a decarburization reaction at the fire point (collision surface between the oxygen jet and the steel bath), and promotes slagging, slag, steel bath reaction. Progress simultaneously. [0003] When the mixing ratio of hot metal of the converter material is as high as about 95%, C in the hot metal was sufficient as a heat source for raising the temperature of the molten steel. Increasing the proportion of the stone requires that the heat source for raising the temperature of the molten steel be compensated in some way. As a means of this, together with a method of adding carbonaceous materials such as coke, a secondary combustion method in which CO gas generated by blowing decarburization is burned with O ₂ injected from a nozzle different from that used for blowing, and transmitted to a steel bath There is. Various types of converter blasting lances for secondary combustion have been proposed. The purpose of the lance is to add a conventional blowing main nozzle and a blast nozzle near the main nozzle.
A secondary nozzle for the next combustion is provided. For example, Japanese Patent Application Laid-Open No. 62-44517 discloses that in a converter blasting lance having a sub-nozzle together with a main nozzle for refining, the sub-nozzle has a tapered shape or an inside so that the discharge flow rate becomes subsonic. A converter blowing lance having a perforated plate, a shape provided with a gas flow resistor such as a change in the cross section of a flow path, or a combination thereof is disclosed. [0005] In such a converter blast blowing lance, three to five main nozzles for decarburization refining and sub-nozzles for secondary combustion are alternately arranged. When the O ₂ spouting from the Laval-shaped main nozzle at a supersonic speed collides with the steel bath even from a height of about 1 to 3 m from the steel bath, the pressure is higher than the static pressure of the slag bath on the upper surface of the steel bath. Since it is high and maintains a flow velocity exceeding the speed of sound, it reaches the steel bath and stirs molten steel to promote a rapid decarburization reaction. On the other hand, the sub-nozzle has a shape that is widened or provided with a gas resistor, or a shape obtained by combining them. And / or the pressure of the O ₂ gas increases due to the influence of the gas flow resistor and the flow velocity begins to decrease, and the gas is discharged at a subsonic speed. For this reason, the thermal efficiency is improved by secondary burning 20 to 40% of the CO gas generated by the decarburization reaction of the molten steel. According to the prior art disclosed in the above publication, the secondary combustion rate of CO gas in the converter is high and the effect of improving thermal efficiency can be obtained, but on the other hand, the temperature in the furnace increases. There is a problem that the refractory of the converter is worn out and the life of the refractory is shortened. In order to reduce the wear of the converter refractories, several tons of the slag are left in the converter without discharging the entire amount of slag from the converter after tapping of the converter, and the converter is rocked in the tapping and charging directions. A slag coating technique for attaching slag to the furnace inner wall is effective. However, the slag coating can be reliably performed by swinging the converter in the tapping and charging directions in the angle range of ± 20 degrees with respect to the furnace center line in the tapping and charging directions. Is difficult to perform slag coating. For this reason, even if the slag coating technology is adopted, there is a problem that the refractory of the converter not coated with the slag is affected by the secondary combustion, so that the wear of the refractory cannot be suppressed. [0008] The present invention solves the above-mentioned problems of the prior art, and uses a converter blowing lance having a main nozzle for refining and a sub-nozzle for secondary combustion. CO in furnace
It is an object of the present invention to provide a method for using a converter blasting lance that can reduce the wear of a converter refractory even when promoting secondary combustion of gas. [0009] SUMMARY OF THE The present invention for achieving the above object includes a sub-nozzle of the main nozzle and a secondary combustion for refining, the sub-nozzle discharge velocity is subsonic Will be
Shape with a divergent and / or gas flow resistor
In how to use the lance for the converter blowing that is the, this
When the converter blowing lance is inserted into the converter ,
Selection to placed as sub nozzle position of the scan is positioned steel output of the converter capable of slag coating on the furnace inner wall, a furnace center with respect to charging direction of the furnace center line within the angular range of 20 degrees ± This is a method of using a converter lance for blowing. According to the present invention, the position of the sub-nozzle of the converter blasting lance is set at an angle of ± 20 degrees from the center of the furnace with respect to the furnace center line in the charging direction so that the inner wall of the converter can be slag coated. it arranged is chosen to lie within the range. Therefore, the CO gas generated by the decarburization reaction caused by the contact between the steel bath and the O ₂ gas ejected at supersonic speed from the main nozzle of the converter blowing lance is converted into slag by the subsonic O ₂ gas discharged from the sub nozzle. Secondary combustion can be performed efficiently near the coated converter refractory. As a result, the effect of the high temperature inside the furnace due to the secondary combustion affects only the converter refractory protected by the slag coating, and affects the portion of the converter refractory not coated with the slag coating. Since is not directly affected by the high temperature due to the secondary combustion, wear of the converter refractory is reduced, and the life of the converter refractory is extended. Next, details of the present invention will be described with reference to the illustrated embodiment. As shown in FIGS. 1 and 2, the converter blasting lance according to the present invention includes a secondary nozzle 2 for secondary combustion in addition to a main nozzle 2 for refining communicating with the flow path 1 of the lance body 10. A plurality of main nozzles 2 are shown in the drawing.
And two sub nozzles 3 arranged symmetrically. The main nozzle 2 has a normal Laval shape, while the sub nozzle 3 has a flow path at an angle outward with respect to the lance axis and a small-diameter flow path 3a to a large-diameter flow path so that the discharged oxygen gas has a subsonic velocity. 3b has a widening shape.
Reference numeral 4 denotes a water cooling passage formed by a partition plate 5 provided in the lance main body 10. The sub-nozzle 3 moves from the small-diameter passage 3a to the large-diameter passage 3
Since has previously spread b, when flowing from the oxygen flow path 1 to the small-diameter passage 3a, becomes a state close to the speed of sound in the inlet portion, the O ₂ gas under the influence of flared to large diameter channel 3b The pressure increases and the flow velocity decreases, resulting in a subsonic discharge velocity. The shape of the divergent sub-nozzle gives a divergent taper,
A sub-nozzle with a tapered tip may be provided with a gas flow resistor such as a perforated plate or alternately a multi-stage flow passage changing plate in a multi-stage to reduce the flow rate of O ₂ gas to a subsonic discharge flow rate. it can. By the way, as shown in the plan view of FIG.
Is supported by a trunnion bearing 9 via a trunnion shaft 8 attached to both sides of a trunnion ring 7 provided so as to surround the body, so as to be tiltable to the tapping side and the loading side. As described above, after tapping from the converter, the converter 6 is swung to the tapping side and the charging side with slag remaining in the converter 6 to perform slag coating and protect the converter refractory. However, the slag coating can be applied to the converter refractory only within an angle range of ± 20 degrees from the furnace center to the furnace center line in the tapping and charging directions. Therefore, in the present invention, the position of the pair of sub-nozzles 3 disposed on the lance main body 10 of the converter blasting lance as described above is aligned with the furnace center line 11 of the converter 6 in the tapping and charging directions. it is intended to select to place used to be positioned from the furnace center within an angular range of 20 degrees ± against. When the pair of sub-nozzles 3 are symmetrically arranged on the lance main body 10, it is optimal to position them on the furnace center line 11. Accordingly, the four main nozzles 2 disposed in the lance body 10 of the converter blowing lance inserted into the converter 6
Steel is refined by a gas-steel bath reaction typified by a decarburization reaction at a fire point where a supersonic oxygen jet gushing from the steel bath collides with the steel bath, and CO gas is generated. Meanwhile, tapping of converter 6
Since in response to the loading direction of the furnace center line is disposed a pair of sub-nozzles 3 provided lance body 10, subsonic oxygen gas of about flow velocity 60 m / sec to be discharged from the sub nozzle 3, the slag coating Is discharged to the vicinity of the converter refractory protected by the above, and the CO gas generated by the refining of the steel is efficiently secondary-combusted mainly on the tapping side and the charging side. Therefore, the effect of the high-temperature combustion flame generated by the secondary combustion of the CO gas by the O ₂ gas discharged from the sub-nozzle 3 affects the converter refractory on the tapping side and the charging side coated with slag. As such, damage to the converter refractory in this area is reduced. The converter refractory on the side of the trunnion shaft, which is not coated with slag or is not sufficiently coated, has a high-temperature combustion flame generated by secondary combustion of CO gas by O ₂ gas discharged from the auxiliary nozzle 3. Since it is not directly affected, the wear of the converter refractory in this area is also reduced. As shown in FIG. 1 and FIG.
FIG. 3 shows a pair of sub-nozzles 3 arranged at symmetrical positions of FIG.
180ton / ch converter was charged were disposed in a furnace to match the furnace center line 11 of 6, 450 Nm ³ / min from the main nozzle 2, the oxygen gas from the sub nozzle 3 50 Nm ³ / min blow, When the lance height is 3m, the secondary combustion rate of CO gas generated in the furnace is 15 ~ 20
%, It was possible to improve the secondary combustion rate from the conventional 8 to 13%. As a result, it has become possible to increase the scrap ratio in the converter raw material. In this case, since the slag coating was applied to the converter refractory on the tapping side and the charging side, the erosion of the converter refractory can be suppressed to the same level as in the conventional case where secondary combustion is not performed. Was. As described above, according to the present invention, the slag coating is applied to the converter refractory by oscillating in the tapping and charging direction of the converter after tapping the converter. The secondary nozzle of the lance for converter blowing is placed within an angle range of ± 20 degrees to the center line of the furnace in the tapping / charging direction, and the secondary combustion causes the erosion of the converter refractory. It is possible to suppress and improve the thermal efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a converter blasting lance according to the present invention, as viewed in the direction of arrows AA in FIG. FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3 is a plan view of a converter, showing a range in which a sub-nozzle of a converter blowing lance is arranged. [Description of Signs] 1 flow path 2 main nozzle 3 sub nozzle 4 water cooling passage 5 partition plate 6 converter 7 trunnion ring 8 trunnion shaft 9 trunnion bearing 10 lance body

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21C 5/46 101

Claims (1)

(57) includes a main nozzle Oyo sub nozzle for beauty secondary combustion for Patent Claims 1. A refining, the sub-nozzle discharge velocity is subsonic
With divergent and / or gas flow resistors
In the method of using the lance for converter blowing blasting,
When this converter blowing lance is inserted into the converter ,
Selection to placed as sub nozzle position of Nsu is located steel output of the converter capable of slag coating on the furnace inner wall, a furnace center with respect to charging direction of the furnace center line within the angular range of 20 degrees ± A method for using a lance for converter blowing, characterized in that :