CN108977620B - A single-channel secondary combustion oxygen lance for improving the scrap ratio in converters and its use method - Google Patents
A single-channel secondary combustion oxygen lance for improving the scrap ratio in converters and its use method Download PDFInfo
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- CN108977620B CN108977620B CN201811184284.9A CN201811184284A CN108977620B CN 108977620 B CN108977620 B CN 108977620B CN 201811184284 A CN201811184284 A CN 201811184284A CN 108977620 B CN108977620 B CN 108977620B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
- C21C5/4606—Lances or injectors
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
- C21C5/4606—Lances or injectors
- C21C5/462—Means for handling, e.g. adjusting, changing, coupling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
一种提高转炉废钢比的单流道二次燃烧氧枪及其使用方法，包括枪体和喷头，所述枪体包括由中间管道、中间环缝和外围管道组成的三层钢管结构，所述中间管道通入氧气，所述中间环缝通入冷却水，所述外围管道流出回水，所述喷头的端面设置有主氧喷孔，所述喷头的侧壁设置有副氧喷孔，所述副氧喷孔流量占总供氧流量的15％～30％，所述主氧喷孔流量占总供氧流量的70％～85％，本发明单流道二次燃烧氧枪，氧枪的主氧喷孔与常规传统氧枪设计一致，在原有喷头基础上，开设副氧喷孔，在保证副氧喷孔射流既不与主氧喷孔射流发生“卷吸”现象又不对转炉炉衬造成侵蚀的情况下，利用副氧喷孔射出的氧气射流与炉内一氧化碳燃烧产生大量的热量来加热钢水，提高转炉废钢比。
A single-channel secondary combustion oxygen lance for improving the scrap ratio of converters and a method of using the same, including a lance body and a nozzle. The lance body includes a three-layer steel pipe structure composed of a middle pipe, a middle ring seam and a peripheral pipe. Oxygen flows into the middle pipe, cooling water flows into the middle annular seam, and return water flows out of the peripheral pipe. The end face of the nozzle is provided with a main oxygen nozzle hole, and the side wall of the nozzle head is provided with a secondary oxygen nozzle hole. The flow rate of the secondary oxygen nozzle hole accounts for 15% to 30% of the total oxygen supply flow rate, and the flow rate of the main oxygen nozzle hole accounts for 70% to 85% of the total oxygen supply flow rate. The single-flow channel secondary combustion oxygen lance of the present invention, the oxygen lance The main oxygen nozzle hole is consistent with the conventional oxygen lance design. On the basis of the original nozzle, the secondary oxygen nozzle hole is opened to ensure that the secondary oxygen nozzle jet will not be "entrained" with the main oxygen nozzle jet and will not be aligned with the converter lining. When corrosion occurs, the oxygen jet ejected from the secondary oxygen nozzle hole and the carbon monoxide combustion in the furnace are used to generate a large amount of heat to heat the molten steel and increase the scrap ratio in the converter.
Description
Technical Field
The invention belongs to the technical field of converter steelmaking, and particularly relates to a single-channel secondary combustion oxygen lance for improving the steel scrap ratio of a converter and a use method thereof.
Background
At present, the proportion of electric furnace steel in China is still less than 10%, the converter process is still the main process of steel in China, and all large steel enterprises are greatly improving the waste steel ratio of the converter. The means for improving the scrap steel ratio of the converter, which are commonly used in the current mass production, mainly comprise: scrap preheating and converter adding of a heat supplementing agent (coke, siC and the like), but the two technologies for improving the scrap ratio have the defects: the former needs special heating equipment, and the latter often introduces sulfur, phosphorus and other impurities into molten steel, and the molten steel increases nitrogen to influence the cleanliness of the molten steel.
In the converter steelmaking process, converter gas as a by-product is generally recycled by a steelworks. However, if the converter gas is used by secondary combustion in the converter, the method is the most economical method with highest heat efficiency for gas recycling. The secondary combustion oxygen lance technology is a thermal compensation method capable of improving the secondary combustion rate of converter steelmaking, and is characterized in that a secondary hole is formed in a traditional converter steelmaking oxygen lance, so that oxygen jet ejected from a main hole is subjected to decarburization reaction, and a large amount of heat is generated by combusting oxygen jet ejected from the secondary hole with carbon monoxide in a converter, so that the heat of the converter is fully utilized, and the waste steel ratio of the converter is improved. However, the existing secondary combustion oxygen lance technology has the following defects: (1) the double-runner secondary combustion oxygen lance has high processing and manufacturing difficulty due to complex equipment; the oxygen lance lifting mechanism and the cooling water system have high requirements, so that the oxygen lance lifting mechanism and the cooling water system are difficult to reform on the basis of the traditional oxygen lance system of the existing converter, and are difficult to popularize and apply in large scale in mass production; (2) the secondary combustion heat compensation effect of the double-flow-stream oxygen lance (single flow passage) is limited due to the fact that the flow rate of the auxiliary holes is less than 15%, so that the capability of improving the temperature of molten steel and increasing the scrap steel ratio of the converter is insufficient; and the design cooling difficulty of the number of the outlets of the auxiliary holes is great (especially the area of the outlets of the auxiliary holes) compared with the number of the inlets of the auxiliary holes, and the double-flow oxygen lance with the design of the auxiliary holes is not suitable for industrial production.
Disclosure of Invention
Aiming at the defects of the prior art, the invention designs the novel single-channel secondary combustion oxygen lance, which is characterized in that only a spray nozzle is modified on the basis of the traditional oxygen lance, namely, a reasonable auxiliary oxygen spray hole is formed on the basis of the original spray nozzle, and the converter steelmaking process is optimized on the basis of the single-channel secondary combustion oxygen lance, so that the secondary combustion rate of coal gas in the converter steelmaking process is effectively improved, the steel charge amount of a converter scrap is increased, the steel charge ratio of the converter is improved, the oxygen blowing time is shortened, the smelting period of the converter is shortened, and the terminal desulfurization rate of the converter is improved.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the utility model provides an improve single-channel secondary combustion oxygen rifle of converter steel scrap ratio, its characterized in that includes rifle body and shower nozzle, the rifle body includes the three-layer steel tube structure of constituteing by intermediate pipeline, intermediate circular seam and peripheral pipeline, the intermediate pipeline lets in oxygen, the intermediate circular seam lets in the cooling water, the peripheral pipeline flows back water, the terminal surface of shower nozzle is provided with main oxygen orifice, the lateral wall of shower nozzle is provided with the auxiliary oxygen orifice, auxiliary oxygen orifice flow accounts for 15% -30% of total oxygen supply flow, main oxygen orifice flow accounts for 70% -85% of total oxygen supply flow.
The opening angle between the main oxygen spray hole axis and the gun body axis is alpha, the alpha is set to 9-18 degrees, the opening angle between the auxiliary oxygen spray hole and the gun body axis is beta, and the beta is 2.1-2.5 times of the alpha.
The axial distance L between the main oxygen spray hole and the auxiliary oxygen spray hole is 40-150 mm.
The number of the main oxygen spray holes is 3-6, and the number ratio of the auxiliary oxygen spray holes to the main oxygen spray holes is 1.0-2.0 times.
The main oxygen jet orifice is arranged into a conventional Laval type structure, and the throat diameter d of the main oxygen jet orifice Throat part 25 mm-45 mm, and the diameter d of the outlet of the main oxygen spray hole 1 Is d Throat part 1.1 to 1.5 times of the total weight of the composition.
The auxiliary oxygen spray hole is of a straight cylinder type or sudden jump expansion type structure, and the diameter d of the inlet of the auxiliary oxygen spray hole of the straight cylinder type structure 2 Is d Throat part 0.3 to 0.5 times of the total weight of the steel sheet; diameter d of expansion section of auxiliary oxygen jet hole with abrupt expansion structure 3 Is the diameter d of the inlet of the auxiliary oxygen jet hole 2 1.1 to 1.5 times of the total weight of the composition.
A method for using a single-channel secondary combustion oxygen lance for improving the steel scrap ratio of a converter adopts the single-channel secondary combustion oxygen lance for improving the steel scrap ratio of the converter, which comprises the following steps,
step 1, pouring out slag after tapping of the previous furnace is completed, blocking a tap hole, adding scrap steel into a converter by a crown block, and then adding molten iron in a ladle into the converter;
step 2, controlling the designed single-channel secondary combustion oxygen lance by a secondary combustion oxygen lance lifting mechanism, and providing proper oxygen supply pressure and flow; adding a first batch of slag charge while oxygen is fed and blown, wherein the addition amount is three fourths of the total slag amount of the whole furnace;
step 3, after 3-4 min of blowing, the first slag charge is well converted, and then the second slag charge is added; in the blowing process, the oxygen supply flow and the oxygen supply pressure are controlled within a reasonable range, so that the stirring of a converter molten pool is enhanced, and the molten steel in the molten pool is uniform in composition and temperature; when the blowing reaches the requirement of steelmaking seeds, lifting a gun, stopping blowing, pouring out the furnace, sampling and tapping.
The oxygen supply pressure in the step 2 is 0.75-1.25 Mpa, the oxygen supply pressure is 1.05-1.25 times of the oxygen supply pressure of a conventional oxygen gun, and the oxygen supply flow in the step 2 is 17000-45000 Nm 3 And/h, the oxygen supply flow is 1.10-1.35 times of the oxygen supply flow of the conventional oxygen lance.
The invention has the advantages that,
(1) The single-channel secondary combustion oxygen lance has the advantages that the design of the main oxygen jet orifice of the oxygen lance is consistent with that of a conventional oxygen lance, a reasonable auxiliary oxygen jet orifice structure is arranged on the basis of an original jet head, and under the condition that the auxiliary oxygen jet orifice jet flow is ensured not to be involved with the main oxygen jet orifice jet flow and not to erode a converter lining, a great amount of heat is generated by the combustion of the oxygen jet flow emitted by the auxiliary oxygen jet orifice and carbon monoxide in the converter to heat molten steel, so that the amount of added steel scraps is increased, and the steel scraps ratio of the converter is improved; the secondary combustion oxygen lance is also beneficial to slag melting in the converter smelting process, increases the oxygen supply intensity, reduces the oxygen supply time, shortens the converter smelting period and improves the end point desulfurization rate of the converter.
(2) The single-flow-channel secondary combustion oxygen lance does not need to reform the original lance body, only reforms the oxygen lance nozzle, has the same number of outlets and inlets of the auxiliary holes, has less reform on the cooling water inlet pipeline, has good cooling effect on the lance body, small processing difficulty and low manufacturing cost. The oxygen supply flow of the oxygen lance auxiliary oxygen spray hole can reach 15-30% of the total oxygen supply flow, the oxygen supply pressure of the oxygen is 1.05-1.25 times of the pressure of the conventional oxygen lance, and the oxygen supply flow is 1.10-1.35 times of the conventional oxygen lance flow; therefore, the secondary combustion oxygen lance can greatly improve the secondary combustion rate of carbon monoxide in the converter, and does not influence the decarburization of the main oxygen hole of the oxygen lance and the metallurgical function of slag splashing.
Drawings
FIG. 1 is a schematic diagram of a single-channel secondary combustion oxygen lance I in example 1, wherein the number of main oxygen spray holes is 4, the number of auxiliary oxygen spray holes is 6, and the auxiliary oxygen spray holes have a straight cylinder structure;
FIG. 2 is a schematic diagram of a single-channel secondary combustion oxygen lance II in example 2, wherein the number of main oxygen spray holes is 4, the number of auxiliary oxygen spray holes is 6, and the auxiliary oxygen spray holes have a jump expansion type structure;
FIG. 3 is a schematic diagram of a structure of a single-channel secondary combustion oxygen lance III in embodiment 3, wherein the number of main oxygen spray holes is 5, the number of auxiliary oxygen spray holes is 8, and the auxiliary hole type is a straight cylinder type structure;
FIG. 4 is a schematic diagram of a structure of a single-channel secondary combustion oxygen lance IV of the embodiment 4, wherein the number of main oxygen spray holes is 4, the number of auxiliary oxygen spray holes is 8, and the hole type of the auxiliary oxygen spray holes is a straight-cylinder structure;
1-gun body, 2-spray head, 3-middle pipeline, 4-middle circumferential seam, 5-peripheral pipeline, 6-main oxygen spray hole and 7-auxiliary oxygen spray hole.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples.
The utility model provides an improve single-channel secondary combustion oxygen rifle of converter steel scrap ratio, its characterized in that includes rifle body 1 and shower nozzle 2, rifle body 1 includes the three-layer steel pipe structure of constituteing by intermediate pipeline 3, intermediate circular seam 4 and peripheral pipeline 5, intermediate pipeline 3 lets in oxygen, intermediate circular seam 4 lets in the cooling water, peripheral pipeline 5 flows the return water, the terminal surface of shower nozzle 2 is provided with main oxygen orifice 6, the lateral wall of shower nozzle 2 is provided with vice oxygen orifice 7, vice oxygen orifice 7 flow accounts for 15% -30% of total oxygen supply flow, main oxygen orifice 6 flow accounts for 70% -85% of total oxygen supply flow.
The opening angle between the axis of the main oxygen spray hole 6 and the axis of the gun body 1 is alpha, the alpha is set to 9-18 degrees, the opening angle between the axis of the auxiliary oxygen spray hole 7 and the axis of the gun body 1 is beta, and the beta is 2.1-2.5 times of the alpha.
The axial distance L between the main oxygen spray hole 6 and the auxiliary oxygen spray hole 7 at the spray head 2 is 40 mm-150 mm.
The number of the main oxygen spray holes 6 is 3-6, and the number ratio of the auxiliary oxygen spray holes 7 to the main oxygen spray holes 6 is 1.0-2.0.
The main oxygen jet orifice 6 is arranged into a conventional Laval type structure, and the throat diameter d of the main oxygen jet orifice 6 Throat part 25 mm-45 mm, and the diameter d of the outlet of the main oxygen jet orifice 6 1 Is d Throat part 1.1 to 1.5 times of the total weight of the composition.
The auxiliary oxygen spray hole 7 is of a straight cylinder type or sudden jump expansion type structure, and the diameter d of the inlet of the auxiliary oxygen spray hole 7 of the straight cylinder type structure 2 Is d Throat part 0.3 to 0.5 times of the total weight of the steel sheet; diameter d of expansion section of auxiliary oxygen jet orifice 7 with abrupt expansion structure 3 Diameter d of the inlet of the auxiliary oxygen jet hole 7 2 1.1 to 1.5 times of the total weight of the composition.
The smelting effects of the oxygen lances I, II, III and IV of the invention are respectively tested on top-bottom combined blown converters of 80t, 120t, 180t and 210t of a certain steel mill in China, and particularly the waste steel ratio of the converters before and after the oxygen lances are used is compared in detail.
Example 1
At present, a conventional common oxygen lance is adopted on an 80-ton converter of the steel mill, the average steel charge amount is generally 8.37t, and the steel charge amount is lower. The slag added in the first batch is generally two thirds of the total slag, the slag melting time is 4-6 min, the oxygen supply time is 14.5-15.7 min, and the desulfurization rate at the smelting end point is 5.1-6.3%.
As shown in FIG. 1, in the embodiment, the auxiliary oxygen nozzle 7 of the single-channel secondary combustion oxygen lance I is of a straight cylinder structure, the single-channel secondary combustion oxygen lance I is applied to the on-site converter steelmaking process on an 80t converter, the number of main oxygen nozzles of the oxygen lance is 4, the number of auxiliary oxygen nozzles is 6, the opening angle alpha of the main oxygen nozzles 6 is 9 degrees, the opening angle beta of the auxiliary oxygen nozzles 7 is 20 degrees, and the diameter d of the throat opening Throat part 25mm, diameter d of outlet of main oxygen nozzle 6 1 28mm, diameter d of the inlet of the auxiliary oxygen nozzle 7 2 The axial distance L between the main oxygen spray hole 6 and the auxiliary oxygen spray hole 7 at the nozzle 2 is 40mm and is 10 mm.
The specific implementation is as follows: after the tapping of the previous furnace is completed, pouring slag, blocking the tapping hole, adding scrap steel into the converter by using a crown block, adding molten iron in a ladle into the converter, wherein the temperature of the molten iron is generally higher than 1300 ℃, then lowering the lance by using an oxygen lance lifting mechanism to supply oxygen, wherein the oxygen supply pressure is 0.75-0.85 Mpa, and the oxygen supply flow is 17000-21000 Nm 3 And/h, adding a first batch of slag while feeding oxygen and blowing, wherein the addition amount is three fourths of the total slag amount of the whole furnace, and after 3-4 min of blowing, the first batch of slag is well converted, and then adding a second batch of slag. Oxygen supply pressure and flow rate base during converting periodThe slag is kept unchanged, so that the slag is prevented from being dried back and splashed; at the end of blowing, a secondary combustion oxygen lance lifting mechanism is utilized to reduce the distance between an oxygen lance and a molten pool, so that the molten steel composition and the temperature of the molten pool are uniform, the stirring is enhanced, the iron content in slag is reduced, and the iron loss is reduced; when the blowing reaches the requirement of steelmaking seeds, lifting a gun, stopping blowing, pouring out the furnace, sampling and tapping.
Sampling analysis is carried out on the result, after the single-channel secondary combustion oxygen lance I is used, the oxygen blowing time is shortened to 12.2-13.5 min in the smelting process, and the desulfurization rate at the smelting end point is improved to 8.9-11.3%. The amount of the steel scraps entering the furnace is increased from 8.37t to 10.25t, and the amount of the steel scraps entering the furnace is increased:
example 2
At present, a conventional common oxygen lance is adopted on a 120-ton converter of a steelworks, the average steel charging scrap amount is generally 15.37t, and the steel charging scrap amount is lower. The slag added in the first batch is generally two thirds of the total slag, the slag melting time is 4-6 min, the oxygen supply time is 13.7-14.9 min, and the desulfurization rate at the smelting end point is 4.7-5.3%.
As shown in FIG. 2, in the present embodiment, the secondary oxygen jet holes 7 of the single-channel secondary combustion oxygen lance II are of a jump expansion structure, the single-channel secondary combustion oxygen lance II is applied to the on-site converter steelmaking process on a 120-ton converter, the number of the main oxygen jet holes 6 of the oxygen lance is 4, the number of the secondary oxygen jet holes 7 is 6, the opening angle alpha of the main oxygen jet holes 6 is 15 degrees, the opening angle beta of the secondary oxygen jet holes 7 is 35 degrees, and the diameter d of the throat opening Throat part 35mm, diameter d of outlet of main oxygen nozzle 6 1 45mm, diameter d of the inlet of the auxiliary oxygen nozzle 7 2 14mm diameter d 3 The axial distance L between the main oxygen spray hole 6 and the auxiliary oxygen spray hole 7 at the nozzle 2 is 80mm and is 18 mm.
The specific implementation is as follows: after the tapping of the previous furnace is completed, pouring out slag, blocking the tapping hole, adding scrap steel into the converter by using a crown block, adding molten iron in a ladle into the converter, wherein the temperature of the molten iron is generally higher than 1300 ℃, and then lowering a lance by using an oxygen lance lifting mechanism for supplyingOxygen, oxygen supply pressure of 0.85-1.05 Mpa and oxygen supply flow of 28000-30000 Nm 3 And/h, adding a first batch of slag while feeding oxygen and blowing, wherein the addition amount is three fourths of the total slag amount of the whole furnace, and after 3-4 min of blowing, the first batch of slag is well converted, and then adding a second batch of slag. In the middle of converting, the oxygen supply pressure and flow are basically kept unchanged, so that the slag is ensured not to be dried back and splashed; at the end of blowing, a secondary combustion oxygen lance lifting mechanism is utilized to reduce the distance between an oxygen lance and a molten pool, so that the molten steel composition and the temperature of the molten pool are uniform, the stirring is enhanced, the iron content in slag is reduced, and the iron loss is reduced; when the blowing reaches the requirement of steelmaking seeds, lifting a gun, stopping blowing, pouring out the furnace, sampling and tapping.
After sampling analysis is carried out on the result, the oxygen lance II with the single flow channel is used, the oxygen blowing time is shortened to 11.8-13.2 min in the smelting process, the desulfurization rate at the smelting end point is improved to 7.8-8.6%, the steel charge amount is increased from 15.37t to 18.45t, and the steel charge amount is increased:
example 3
At present, a 180-ton converter in a steel plant adopts a conventional common oxygen lance III, the average steel charging scrap amount is generally 16.35t, and the steel charging scrap amount is lower. The slag added in the first batch is generally two thirds of the total slag, and the slag melting time is 4-6 min. The oxygen supply time is 13.5-14.8 min, and the desulfurization rate is 5.7-6.4%.
As shown in FIG. 3, in the present embodiment, the secondary oxygen jet holes 7 of the single-channel secondary combustion oxygen lance III are in a straight cylinder structure, the single-channel secondary combustion oxygen lance III is applied to the on-site converter steelmaking process on a 180-ton converter, the number of main oxygen jet holes 6 of the oxygen lance is 5, the number of secondary oxygen jet holes 7 is 8, the opening angle alpha of the main oxygen jet holes 6 is set to 18 degrees, the opening angle beta of the secondary oxygen jet holes 7 is 40 degrees, and the diameter d of the throat opening Throat part 40mm, diameter d of outlet of main oxygen nozzle 6 1 50mm, diameter d of the inlet of the auxiliary oxygen nozzle 7 2 The axial distance L between the main oxygen spray hole 6 and the auxiliary oxygen spray hole 7 at the nozzle 2 is 100mm and is 20mm.
The specific implementation is as follows: after the tapping of the previous furnace is completed, pouring slag, blocking the tapping hole, adding scrap steel into the converter by using a crown block, adding molten iron in a ladle into the converter, wherein the temperature of the molten iron is generally higher than 1300 ℃, then lowering the lance by using an oxygen lance lifting mechanism to supply oxygen, wherein the oxygen supply pressure is 0.95-1.15 Mpa, and the oxygen supply flow is 29600-32500 Nm 3 And/h, adding a first batch of slag while feeding oxygen and blowing, wherein the addition amount is three fourths of the total slag amount of the whole furnace, and after 3-4 min of blowing, the first batch of slag is well converted, and then adding a second batch of slag. In the middle of converting, the oxygen supply pressure and flow are basically kept unchanged, so that the slag is ensured not to be dried back and splashed; at the end of blowing, a secondary combustion oxygen lance lifting mechanism is utilized to reduce the distance between an oxygen lance and a molten pool, so that the molten steel composition and the temperature of the molten pool are uniform, the stirring is enhanced, the iron content in slag is reduced, and the iron loss is reduced; when the blowing reaches the requirement of steelmaking seeds, lifting a gun, stopping blowing, pouring out the furnace, sampling and tapping.
Sampling analysis is carried out on the result, after the single-channel secondary combustion oxygen lance IV of the design is used, the oxygen blowing time is shortened to 11.2-12.3 min in the smelting process, and the desulfurization rate is improved to 9.5-10.7%. The amount of the steel scraps entering the furnace is increased from 16.35t to 21.32t, and the amount of the steel scraps entering the furnace is increased:
example 4
At present, a conventional common oxygen lance is adopted on a 210 ton converter of a steelworks, the average steel charge amount is generally 19.35t, and the steel charge amount is lower. The slag added in the first batch is generally two thirds of the total slag, the slag melting time is 4-6 min, and the slag melting time is long. In the converter smelting process, the average oxygen supply time is 15.4-16.7 min, and the desulfurization rate is 5.6-6.7%.
As shown in FIG. 4, in the embodiment, the auxiliary oxygen nozzle of the single-channel secondary combustion oxygen lance IV is of a straight cylinder structure, the single-channel secondary combustion oxygen lance IV is applied to the on-site converter steelmaking process on a 210-ton converter, the number of main oxygen nozzles of the oxygen lance is 4, and the number of auxiliary oxygen nozzles of the oxygen lance is 8.The opening angle alpha of the main oxygen jet orifice 6 is 18 degrees, the opening angle beta of the auxiliary oxygen jet orifice 7 is 45 degrees, and the diameter d of the throat opening Throat part 45mm diameter d of outlet of main oxygen nozzle 6 1 60mm, diameter d of the inlet of the auxiliary oxygen nozzle 7 2 20mm. The axial distance L between the main oxygen spray hole 6 and the auxiliary oxygen spray hole 7 at the spray head 2 is 120mm.
The specific implementation is as follows: after the tapping of the previous furnace is completed, pouring slag, blocking the tapping hole, adding scrap steel into the converter by using a crown block, adding molten iron in a ladle into the converter, wherein the temperature of the molten iron is generally higher than 1300 ℃, then lowering the lance by using an oxygen lance lifting mechanism to supply oxygen, wherein the oxygen supply pressure is 0.90-1.25 Mpa, and the oxygen supply flow is 40000-45000 Nm 3 And/h, adding a first batch of slag while feeding oxygen and blowing, wherein the addition amount is three fourths of the total slag amount of the whole furnace, and after 3-4 min of blowing, the first batch of slag is well converted, and then adding a second batch of slag. In the middle of converting, the oxygen supply pressure and flow are basically kept unchanged, so that the slag is ensured not to be dried back and splashed; at the end of blowing, a secondary combustion oxygen lance lifting mechanism is utilized to reduce the distance between an oxygen lance and a molten pool, so that the molten steel composition and the temperature of the molten pool are uniform, the stirring is enhanced, the iron content in slag is reduced, and the iron loss is reduced; when the blowing reaches the requirement of steelmaking seeds, lifting a gun, stopping blowing, pouring out the furnace, sampling and tapping.
Sampling analysis is carried out on the result, after the single-channel secondary combustion oxygen lance IV of the design is used, the oxygen blowing time is shortened to 13.2-14.5 min in the smelting process, and the desulfurization rate is improved to 9.4-11.2%. The amount of the steel scraps entering the furnace is increased from 19.35t to 25.13t, and the amount of the steel scraps entering the furnace is increased:
as can be seen from examples 1, 2, 3 and 4, the four single-channel secondary combustion oxygen lances designed by the invention are used, so that slag melting is fast, oxygen supply time is shortened, and smelting period is shortened in the converter smelting process; the desulfurization rate of the smelting end point is improved; particularly, the steel scrap quantity of the converter is greatly increased, wherein the single-channel secondary combustion oxygen lances III and IV used in the embodiment 3 and the embodiment 4 have the best field use effect, and the steel scrap quantity of the converter is obviously improved.
Claims (3)
1. The single-channel secondary combustion oxygen lance for improving the steel scrap ratio of the converter is characterized by comprising a lance body and a nozzle, wherein the lance body comprises a three-layer steel pipe structure consisting of a middle pipeline, a middle circular seam and a peripheral pipeline, oxygen is introduced into the middle pipeline, cooling water is introduced into the middle circular seam, return water flows out of the peripheral pipeline, a main oxygen spray hole is arranged on the end face of the nozzle, an auxiliary oxygen spray hole is arranged on the side wall of the nozzle, the flow of the auxiliary oxygen spray hole accounts for 15% -30% of the total oxygen supply flow, and the flow of the main oxygen spray hole accounts for 70% -85% of the total oxygen supply flow;
the opening angle between the main oxygen spray hole axis and the gun body axis is alpha, the alpha is set to 9-18 degrees, the opening angle between the auxiliary oxygen spray hole and the gun body axis is beta, and the beta is 2.1-2.5 times of the alpha; the axial distance L between the spray heads of the main oxygen spray holes and the auxiliary oxygen spray holes is set to be 40-150 mm;
the main oxygen jet orifice is arranged into a conventional Laval type structure, and the throat diameter d of the main oxygen jet orifice Throat part 25 mm-45 mm, and the diameter d of the outlet of the main oxygen spray hole 1 Is d Throat part 1.1 to 1.5 times of the total weight of the composition; the auxiliary oxygen spray hole is of a straight cylinder type or sudden jump expansion type structure, and the diameter d of the inlet of the auxiliary oxygen spray hole of the straight cylinder type structure 2 Is d Throat part 0.3 to 0.5 times of the total weight of the steel sheet; diameter d of expansion section of auxiliary oxygen jet hole with abrupt expansion structure 3 Is the diameter d of the inlet of the auxiliary oxygen jet hole 2 1.1 to 1.5 times of the total weight of the composition.
2. The single-channel secondary combustion oxygen lance for improving the scrap ratio of a converter as set forth in claim 1, wherein: the number of the main oxygen spray holes is 3-6, and the number ratio of the auxiliary oxygen spray holes to the main oxygen spray holes is 1.0-2.0 times.
3. A method for using a single-channel secondary combustion oxygen lance for improving the steel scrap ratio of a converter, which is characterized by comprising the following steps of,
step 1, pouring out slag after tapping of the previous furnace is completed, blocking a tap hole, adding scrap steel into a converter by a crown block, and then adding molten iron in a ladle into the converter;
step 2, controlling the single-channel secondary combustion oxygen lance by a secondary combustion oxygen lance lifting mechanism, and providing proper oxygen supply pressure and flow; adding a first batch of slag while oxygen is fed and blown, wherein the addition amount is three fourths of the total slag amount of the whole furnace; the oxygen supply pressure is 0.75-1.25 Mpa, the oxygen supply pressure is 1.05-1.25 times of the oxygen supply pressure of a conventional oxygen gun, and the oxygen supply flow is 17000-45000 Nm 3 And/h, the oxygen supply flow is 1.10-1.35 times of the oxygen supply flow of the conventional oxygen lance;
step 3, after 3-4 min of blowing, the first slag charge is well converted, and then the second slag charge is added; in the blowing process, the oxygen supply flow and the oxygen supply pressure are controlled within a reasonable range, so that the stirring of a converter molten pool is enhanced, and the molten steel in the molten pool is uniform in composition and temperature; when the blowing reaches the requirement of steelmaking seeds, lifting a gun, stopping blowing, pouring out the furnace, sampling and tapping.
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| CN111254250A (en) * | 2020-01-21 | 2020-06-09 | 鞍钢股份有限公司 | Smelting method for improving converter scrap steel ratio |
| CN114717380A (en) * | 2022-03-21 | 2022-07-08 | 北京科技大学 | Supersonic secondary combustion oxygen lance for improving converter steel scrap ratio |
| CN116837170A (en) * | 2023-08-16 | 2023-10-03 | 攀钢集团攀枝花钢铁研究院有限公司 | Oxygen lance nozzle for improving oxygen lance air supply dynamic condition of vanadium extraction converter |
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Application publication date: 20181211 Assignee: Jiangsu Shidai Hongyuan Environmental Protection Technology Co.,Ltd. Assignor: Northeastern University Contract record no.: X2021210000016 Denomination of invention: A single channel secondary combustion oxygen lance for increasing scrap ratio of converter and its application method License type: Common License Record date: 20210407 |
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