Telescopic chute for injection and dosing of KR desulfurizer in molten iron and its use method

Abstract

The invention discloses a telescopic chute for injecting and dosing a molten iron KR desulfurizer, comprising an inner center tube, an outer sleeve, an inner arc tube, an outer arc sleeve, an inner conical tube and an outer conical tube, and an outer jet swirl mechanism; the inner center hole of the inner center tube, the inner center hole of the inner arc tube and the inner conical hole of the inner conical tube are connected to form an inner jet channel, the annular cavity between the outer sleeve and the inner center tube, the annular cavity between the inner arc tube and the outer arc sleeve, and the gap between the inner conical tube and the outer conical tube are connected to form an outer jet channel; the bottom outlet of the inner jet channel is an inner jet nozzle, and the bottom outlet of the outer jet channel is an outer jet nozzle. Through the stable performance of the above-mentioned positive effects, the technical requirements of efficient entrainment and mixing of the desulfurizer in the set fine particle size range and the interface desulfurization reaction are met, and the comprehensive purposes of shortening the stirring time of molten iron KR, reducing the consumption of desulfurizer, stabilizing the desulfurization effect of molten iron, reducing the iron loss of slag removal and the temperature drop of desulfurized molten iron are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of molten iron pretreatment, and in particular to a telescopic chute for injecting and dosing 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 obliquely passes through the opening of the dust removal hood and extends into the above the stirring vortex liquid surface of the molten iron tank. The desulfurizer (generally composed of about 90% active lime and about 10% fluorite) is added to the molten iron stirring vortex liquid surface by gravity drive, that is, gravity feeding. The desulfurizer on the liquid surface is continuously stirred, entrained and mixed in the molten iron to achieve desulfurization reaction at the interface between the desulfurizer and the molten iron. Therefore, it has excellent desulfurization reaction kinetics conditions 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. In order to reduce the amount of dust suction and escape during the desulfurization agent addition process, many companies, based on their own equipment conditions, have adopted the method of increasing the maximum critical size of desulfurizer particles and reducing the content of desulfurizer fine powder, so as to reduce the amount of desulfurizer airflow entrainment and escape, and increase the desulfurizer molten iron stirring and suction rate, so as to achieve the purpose of reducing desulfurizer consumption and dust environmental pollution. However, 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 problem that the feeding tube is easy to be blocked and the feeding speed is unstable, which not only affects the stability of the molten iron KR stirring desulfurization process operation, but also the desulfurizer accumulated in the telescopic feeding chute instantly falls, 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 of the operating environment, increasing the loss of the desulfurizer, and reducing the reaction interface area of ​​the desulfurizer. For this reason, the smooth and stable feeding technology of the desulfurizer has received great attention from enterprises and scholars, and a technical solution for gas injection and feeding of desulfurizer has been proposed. 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 comprehensive goals of reducing the particle size of the desulfurizer, increasing the reaction area, and reducing the escape of dust removal suction.

[0004] In view of the shortcomings of conventional gravity feeding method, such as easy agglomeration of powder, large loss of escape and small specific surface area of ​​large particle desulfurizer, the document "Chen Rong, Zhang He, Chen Shuyan, Application of dense phase transportation of active lime in KR process desulfurization project, Modern Metallurgy, 2014, No. 6" introduces a main equipment for desulfurizer gas transportation and desulfurizer telescopic chute injection and feeding, which is mainly composed of a powder storage silo, a valve station, a spraying tank, a conveying pipeline, an inclined straight telescopic chute, etc. The automatic dosing process of desulfurizer gas injection is as follows: first open the pressure relief valve of the injection tank to release the residual pressure of the injection tank, open the feed valve, open the discharge valve after a delay of several seconds, open the upper fluidization valve at the bottom of the desulfurizer storage bin, and start to discharge the desulfurizer from the storage bin to the injection tank. The weighing system of the injection tank starts to measure. When the lime in the injection tank is equal to the weight of the desulfurizer calculated by the desulfurization model, close the discharge valve, close the feed valve after a delay of several seconds, close the pressure relief valve and the upper fluidization valve after a delay of several seconds, open the lower fluidization valve and the pressure increasing valve of the injection tank, the powder starts to fluidize and pressurize, and at the same time the auxiliary blowing valve is opened to clear the residual in the pipeline. Dust, when the pressure of the spray tank reaches the set spray pressure, the spray valve at the bottom of the spray tank automatically opens, and the fluidized desulfurizer is pressed from the bottom of the spray tank to the conveying pipeline, and then sprayed to the molten iron vortex liquid surface through the inclined telescopic chute nozzle extending above the molten iron tank; the actual application effect shows that the particles with a particle size of 0.5-1.0mm in the desulfurizer account for more than 80%, and the particles less than 0.3mm and greater than 1.2mm are about ≤5% on average. When the spray pressure is 0.3MPa, it takes about 65s to transport 900kg of desulfurizer, which meets the process requirements. The outlet speed of the desulfurizer is not convenient to measure. From the observation of the desulfurization process, most of the desulfurizer enters the molten iron with the V-shaped vortex of the molten iron, and the dust collector captures very little dust.

[0005] In addition, the Chinese patent "Han Jun, Chen Ming, Liu Luchang, et al., A control method for KR desulfurization method, application number: 201410682036.2" discloses a specific operation step of KR stirring desulfurization of molten iron, wherein the desulfurizer is added by nitrogen injection, and the specific operation is: the order of opening is the auxiliary blowing valve, bottom blowing valve, fluidization valve and pressure feeding valve, and the delay is 10 seconds after the addition is completed, and then the pressure feeding valve, fluidization valve, bottom blowing valve and auxiliary blowing valve are closed in sequence, and then the weight of the desulfurizer in the weighing bucket is weighed. If the weight of the desulfurizer is zero, the feeding chute is lifted. If the weight of the desulfurizer is not zero, the auxiliary blowing valve, bottom blowing valve, fluidization valve and pressure feeding valve are opened in sequence to blow the desulfurizer until the weight of the desulfurizer is zero. The desulfurizer is added evenly in sections according to the different weights of added desulfurizer. Specifically, when the weight of the desulfurizer is less than 1000Kg, the material is not added in sections and is added all at once; when the weight of the desulfurizer is greater than 1000Kg and less than 2000Kg, the material is added in two times; when the weight of the desulfurizer is greater than 2000Kg and less than 2900Kg, the material is added in three times; when the weight of the desulfurizer is greater than 2900Kg, 2900Kg of material is added in three times and then the material is automatically re-prepared; and the expected transformation effect of reducing the desulfurizer consumption has been achieved in actual production applications. However, calculated based on the rated loading capacity of the molten iron tank of 200 tons, the desulfurizer consumption is still relatively high, with the maximum consumption reaching 10Kg / t iron. From the above, it can be seen that compared with the gravity dosing method of desulfurizer in molten iron KR stirring desulfurization, the desulfurizer carrier gas blowing addition has achieved the expected effect of reducing the desulfurizer dust removal suction escape and stabilizing the desulfurizer addition acceleration, but the desulfurizer consumption is still high. The reasons are analyzed to be the escape of desulfurizer and the aggregation in the center of the stirring vortex. Due to the small particle size of the sprayed desulfurizer, the convective entrainment and dispersion of fine particles increases. Due to the uncertainty of the desulfurizer blowing addition point, the uncertainty of the desulfurizer jet impact point on the molten iron vortex surface is caused, which aggravates the rebound of the desulfurizer liquid surface and causes the agglomeration of the desulfurizer in the center of the stirring vortex, increasing the difficulty of desulfurizer suction, reducing the specific surface area of ​​the desulfurizer, and restricting the improvement of the reaction utilization rate of the desulfurizer.

[0006] In view of the above problems, the Chinese patent "Naoki Kikuchi, Masaki Koizumi, Takashi Yamauchi, et al., Desulfurization method of molten iron, application number: 201080029394.3" discloses a molten iron KR stirring desulfurization method, which aims to expand the reaction surface area of ​​the desulfurizer and improve the utilization rate of the desulfurizer. The lime-based desulfurizer is sprayed onto the molten iron stirring vortex liquid surface through a straight-cylinder spray gun with a nozzle vertically downward on the liquid surface, using reducing gas, inert gas or non-oxidizing gas as the spray carrier gas; the relationship between the rotation radius (R) of the stirrer and the empty radius (D) of the molten iron tank is controlled to be R≤(1 / 2)×D, and the center of the molten iron tank is controlled to be from the spray gun to the spray gun. The horizontal distance (A) of the center of the gun satisfies the relationship R≤A≤(1 / 2)×D, which avoids the formation of desulfurizer agglomeration when the nozzle is close to the stirring center and the desulfurizer escape when the nozzle is close to the outside of the molten iron tank; by controlling the desulfurizer particle size range to 30-400μm, it avoids the excessively fine particle size desulfurizer being entrained and escaped by the rising airflow and dust removal suction; by limiting the upper limit of the desulfurizer particle size, the reaction interface area of ​​the desulfurizer is increased, and the reaction utilization rate of the desulfurizer is improved; by stirring, mixing and dispersing the desulfurizer, the interface contact reaction between molten iron and the desulfurizer is realized, and finally the purpose of reducing the desulfurizer consumption and improving the desulfurization efficiency of molten iron is achieved. It can be seen that this technology overcomes the shortcomings of the original natural gravity feeding, such as the easy escape of desulfurizer fine powder and the small specific surface area of ​​coarse particles, which is conducive to the improvement of the utilization rate of desulfurizer reaction. However, the desulfurizer consumption is as high as 7Kg / t iron, and there is still a high consumption of desulfurizer, indicating that the problem of desulfurizer escape or agglomeration still needs to be further improved. In addition, the strict control range of desulfurizer particle size of 30-400μm is not conducive to the processing and preparation of desulfurizer and quality control, and increases the preparation and storage cost of desulfurizer. At the same time, due to the reaction force of the molten iron liquid surface on the impact of the desulfurizer jet, within the above control range where the desulfurizer particle size is obviously fine, the fine particles of desulfurizer rebound and escape due to insufficient kinetic energy of liquid surface penetration or gather in the center of the stirring vortex, especially after the formation of the molten iron stirring vortex, the desulfurizer is sprayed and added. Due to the spray angle formed between the molten iron vortex liquid surface and the vertical downward jet, the liquid surface of the desulfurizer particles is further weakened. The penetration kinetic energy and the rebound of the desulfurizer particles on the liquid surface are particularly serious, which intensifies the entrainment and dispersion of the desulfurizer by the rising airflow on the liquid surface, its dust removal and suction escape, and the aggregation in the center of the stirring vortex, increasing the desulfurizer loss and reducing the desulfurization agent reaction interface area and desulfurization utilization rate; in addition, for conventional molten iron KR stirring desulfurization equipment, the existing feeding mechanism of the inclined telescopic chute cannot meet the requirements of the vertical arrangement of the jet spray gun, and the desulfurization platform, frame and feeding system must be comprehensively transformed, which increases the difficulty of implementation under the existing equipment conditions. At present, there are no reports of actual production applications in China.

[0007] Aiming at the problem of desulfurizer particle escape and vortex center agglomeration that are difficult to avoid when spraying desulfurizer on the molten iron liquid surface, the Chinese patent "Zhang Yu, Song Xiaoyan, Zhang Zhongbei, etc., a molten iron desulfurization device and method, application number: 201610531529.5" discloses a molten iron desulfurization device including a spray tank, a stirring device, a lifting device, and a molten iron tank, wherein the stirring device is composed of a rotating drive mechanism, a main shaft and a stirrer of a hollow structure coaxially connected in sequence, and the conveying pipe is connected to the output shaft of the rotating drive mechanism so that the internal space of the conveying pipe is connected with the internal space of the main shaft and the stirrer to form a desulfurizer spraying and adding channel; its operating process is: after the molten iron temperature is measured and sampled, the lifting drive mechanism is started to drive the stirring device to move downward until the stirrer is 150-250mm away from the molten iron liquid surface, and the blowing ventilation pipe is opened to spray nitrogen from the lower end of the stirrer, the gas pressure is 0.4-0.6MPa, and the spraying amount is 20-30Nm 3 / h; the stirring device continues to move downward, so that the lower end of the stirrer is below the molten iron liquid level, the main ventilation pipe and the discharge port of the spray tank are opened, and the gas-carrying desulfurizer is sprayed out from the lower end of the stirrer. The gas spraying volume is 30-40Nm 3 / h, start the rotary drive mechanism to rotate the agitator, the rotation speed is 30 ~ 80r / min; when the amount of desulfurizer added reaches the set value, stop the ventilation of the main ventilation pipe, close the discharge port of the spray tank, keep the ventilation of the auxiliary ventilation pipe, and the gas injection volume is 20 ~ 30Nm 3 / h, the agitator rotates for 4 to 6 minutes, and the rotation speed is reduced to 8 to 12r / min. The lifting drive mechanism is started to move the stirring device upward until the lower end of the agitator is higher than the upper edge of the molten iron tank, and the rotating drive mechanism, lifting drive mechanism and blowing ventilation pipe are closed; the molten iron temperature is measured, sampling and slag are removed to complete the molten iron desulfurization. Compared with the conventional molten iron KR stirring desulfurization, the desulfurizer is directly sprayed into the deep of the molten iron pool, avoiding the escape of the desulfurizer added on the liquid surface and the escape of dust removal suction, improving the kinetic conditions of the desulfurization reaction, and at the same time, reducing the slag operation before the molten iron slag removal, shortening the molten iron desulfurization slag removal production cycle, and reducing the slag removal iron loss. However, the desulfurizer blowing and conveying system is complex, difficult to process and manufacture, and the reliability of the rotary seal is poor. So far, there has been no report on actual production application.

[0008] In view of the shortcomings of the above-mentioned technology in actual production application, based on the positive effect of spraying and adding desulfurizer deep into the molten iron pool to suppress the escape and escape, the Chinese patent "Zhao Yanyu, Han Shaowei, Sun Yonglin, etc., a molten iron desulfurization device and method, application number: 202110962319.2" discloses a desulfurization device consisting of a spraying gas source, a silo, a feed pipe, a straight-cylinder desulfurization spray gun, a molten iron tank and a stirrer. The method for using the desulfurization device is also disclosed, and the specific steps are: inserting the stirrer under the molten iron liquid surface; after the stirrer speed is stable, inserting the desulfurization spray gun below the molten iron liquid surface, and the distance between the lower end of the desulfurization spray gun and the molten iron liquid surface is greater than or equal to 1 / 5 of the static liquid level; spraying desulfurizer into the molten iron at a spraying flow rate of 500-900NL / min and a desulfurizer addition amount of 100-400kg / min; lifting the desulfurization spray gun after the spraying is completed; lifting the stirrer after the stirring is completed to complete the molten iron stirring and desulfurization. It can be seen that the invention uses high-pressure blowing carrier gas to directly spray the desulfurizer through the desulfurization spray gun below the molten iron liquid surface, promotes the dispersion of the desulfurizer, avoids the desulfurizer from escaping and agglomerating, and improves the desulfurizer specific surface area and desulfurization reaction utilization rate. However, the large flow rate and shallow depth of the desulfurizer spraying in the molten iron will inevitably lead to violent splashing during the spraying process, especially the large flow rate spraying under the molten iron liquid surface of the spray gun under the condition of rotating stirring of the agitator. The high-speed jet and fixed spray gun will form a strong interference with the stirring flow field. The strong stirring and spraying kinetic energy coupling and the stirring flow field blocking and inhibition of the fixed spray gun will seriously endanger the stable operation and safe production of the equipment. This is also the main reason why there has been no actual production application report so far.

[0009] In view of the difficulty in implementing the above patent technology, the Chinese patent "Yu Tongxin, He Teng, Ma Xinghuo, a molten iron desulfurization device for saving desulfurizer and its application, application number: 201510427173.6" discloses a desulfurizer chute composed of a straight fixed pipe and a mobile pipe, and also includes a desulfurizer silo connected to the fixed pipe and a blower connected to the fixed pipe through an air supply pipe, and a swirl assembly composed of several swirl blades is arranged in the mobile pipe, and the inner diameter of the fixed pipe is ≥25 0mm, the inner diameter of the moving tube is ≥350mm; in the application process, the moving tube extends to 500mm above the liquid level of the molten iron in the ladle, and clean air or non-oxidizing gas is sent into the desulfurizer chute through the blower. The desulfurizer silo transports the desulfurizer to the desulfurizer chute, and the gas and desulfurizer are mixed and pass through the cyclone component to form a low-speed gas-solid two-phase flow rotating fluid. The gas-solid two-phase flow rotating fluid is fully in contact with the molten iron in a rotating state, so that the desulfurizer is effectively absorbed by the molten iron. Since the conveying gas is a slow rotating fluid, it promotes the dispersion of the desulfurizer. There is no special requirement for the particle size of the desulfurizer. The gas-solid two-phase flow containing the desulfurizer has a large cyclone cross-section, which is convenient for the absorption of the molten iron surface, avoiding the agglomeration of the desulfurizer on the surface of the molten iron, reducing the escape loss of the desulfurizer and the dust removal load. At the same time, the conveying gas will not penetrate into the molten iron, thereby avoiding the influence of moisture in the conveying gas on the molten iron. Therefore, clean air can be used as the conveying gas instead of other non-oxidizing gases, and the desulfurization cost is reduced. Through the test on the desulfurization station of the 180t steelmaking converter, the air volume of the blower is 3000~6000m 3 / h, adjustable, the liquid surface radius of 180t molten iron ladle is 1750mm, the distance from the center of moving tube to the center of molten iron ladle is 1167mm, the outer circle rotation speed of the two-phase flow coming out of the moving tube is 20m / s, the linear speed of the molten iron on the molten iron surface at the center of the moving tube is 20m / s, and the desulfurizer consumption is reduced from the original 11kg / t iron to 9.5kg / t iron. Otherwise, it can be seen that the desulfurizer consumption of the experiment is lower than that of the original system, but the indicators are still high. The reason is that the kinetic energy of the desulfurizer sprayed at a low speed by the large-diameter moving tube vortex is small, and the desulfurizer cannot penetrate the liquid surface smoothly into the molten iron. It still needs to rely on the stirring vortex suction to pull down and mix, and the dynamic behavior of the desulfurizer entering the molten iron is less affected; the air on the liquid surface is easily drawn into the spraying vortex flow, resulting in a large vortex jet cross-section and a large desulfurizer escape area. At the same time, the jet velocity drops quickly, and the ability to resist the convection entrainment of the liquid surface air is small, and the fine desulfurizer is easy to escape; no requirements for the particle size control of the desulfurizer are proposed. If the particle size control requirements are the same as the conventional gravity feeding method, the kinetic energy of the spray jet is conducive to reducing the amount of desulfurizer escape. This is also the main reason why relevant steel companies currently use the inclined feeding telescopic chute of the original gravity feeding of the molten iron KR mixing equipment to carry out spray feeding transformation.

[0010] Based on the current technical status of the coexistence of gravity feeding and blowing feeding of the telescopic chute of the molten iron KR stirring desulfurization equipment, and in view of the differences in the movement behavior of the desulfurizer between the two feeding methods, Chen Junfu, Ouyang Degang, Li Likun and others have formulated the "Calcium-based Desulfurizer for Steelmaking Hot Water Pretreatment" industry standard through systematic hot tests, statistical analysis of production data and extensive solicitation of opinions. The standard number is YB / T 4809-2020, which not only limits the chemical composition of the desulfurizer, but also limits the control range of the desulfurizer particle size under different desulfurizer addition methods. For the two feeding methods of desulfurizer blowing jet feeding and natural gravity feeding to the molten iron liquid surface in actual production, the control range of the desulfurizer particle diameter is 0.1-1.5mm and 0.3-2.5mm, respectively. For the spraying jet dosing method of desulfurizer, the jet blowing of desulfurizer is accelerated, which increases the jet kinetic energy of desulfurizer, strengthens the kinetic energy dispersion of desulfurizer, and reduces the entrainment and dispersion of desulfurizer by natural convection of molten iron surface. Therefore, the particle diameter of desulfurizer is much smaller than that of gravity feeding method, so as to achieve the purpose of expanding the reaction area of ​​desulfurizer and improving the utilization rate of desulfurizer. This is also the main reason for the transformation of the feeding system of molten iron KR desulfurization equipment to the spraying feeding method.

[0011] From the above, it can be seen that the above-mentioned related patents disclose their desulfurizer blowing feeding devices and their use methods, some of which have not been applied due to difficulties in implementation or great safety hazards in implementation. Some patented technologies have achieved implementation effects that are better than conventional gravity feeding of desulfurizers, but the improvement effect is not outstanding. The specific reason is that the corresponding process parameters have not been systematically optimized and determined, such as: the optimization matching problem of the blowing feeding process and the desulfurizer particle size distribution, the optimization matching problem of the desulfurizer injection landing point and the stirring process, the optimization problem of the blowing jet direction, etc. Although the formulation and release of the desulfurizer metallurgical industry standards provide corresponding desulfurizer particle size and composition control standards for the two methods of desulfurizer gravity feeding and blowing feeding, they fail to provide the control standards for the specific feeding process parameters of the two desulfurizer feeding methods. There is still great development potential. In addition, the smaller the desulfurizer particle size, the larger the specific surface area, the higher the desulfurizer reaction speed and utilization rate, but the greater the desulfurizer airflow entrainment and escape, the higher the dust removal and suction escape rate. Compared with the gravity addition of desulfurizer by telescopic chute, the injection addition promotes the mixing and dispersion of desulfurizer by improving the kinetic energy of desulfurizer jet, and reduces the escape rate of desulfurizer, so it can adapt to desulfurizer with smaller particle size. For this reason, based on the technical development direction of hot metal KR desulfurizer injection, it is urgent to develop low-cost, low-loss, efficient and stable hot metal KR desulfurizer injection equipment and comprehensive application technology, so as to further improve the utilization rate of desulfurizer and improve the technical and economic indicators of hot metal KR stirring desulfurization. Summary of the invention

[0012] The purpose of the present invention is to address the deficiencies of the above-mentioned technology and provide a telescopic chute for injecting and adding KR desulfurizer into molten iron and a method for using the same, so as to reduce the escape rate of the desulfurizer, increase the reaction specific surface area of ​​the desulfurizer, promote the stirring, entrainment, mixing and dispersion of the desulfurizer, improve the desulfurization efficiency of molten iron, and achieve the comprehensive purposes of improving the kinetic conditions of the KR desulfurization reaction of molten iron and the technical and economic indicators of molten iron desulfurization.

[0013] To achieve the above-mentioned purpose, the present invention provides a telescopic chute for injecting KR desulfurizing agent into molten iron, comprising an inner center tube, an outer sleeve, an inner arc tube, an outer arc tube, an inner conical tube and an outer conical tube, and an outer jet swirl mechanism; the inner center tube and the outer sleeve are coaxially arranged, the inner arc tube and the outer arc tube are concentrically arranged, and the inner conical tube and the outer conical tube are arranged on a common axis; the inner center tube is inserted into the center hole of the outer sleeve, the top end of the inner center tube extends out of the top end of the outer sleeve, and the top end of the outer sleeve is welded and sealed with the outer cylindrical surface of the inner center tube; the top end surface of the inner arc tube is welded with the bottom end surface of the inner center tube, and the top end surface of the outer arc tube is welded with the lower end surface of the outer sleeve; the inner conical tube is welded with the bottom end surface of the inner center tube, and the inner conical tube is welded with the lower end surface of the outer sleeve; the inner conical tube is welded with the bottom end surface of the inner center tube, and the inner conical tube is welded with the lower end surface of the outer sleeve; the inner conical tube is welded with the bottom end surface of the inner center tube, and the inner conical tube is welded with the outer conical tube. The top surface of the tube is welded to the bottom surface of the inner arc tube, and the top surface of the outer conical tube is welded to the bottom surface of the outer arc sleeve; the inner center hole of the inner center tube, the inner center hole of the inner arc tube and the inner conical hole of the inner conical tube are connected to form an inner jet channel, and the annular cavity between the outer sleeve and the inner center tube, the annular cavity between the inner arc tube and the outer arc sleeve, and the gap between the inner conical tube and the outer conical tube are connected to form an outer jet channel; the bottom outlet of the inner jet channel is the inner jet nozzle, and the bottom outlet of the outer jet channel is the outer jet nozzle to form a double jet nozzle; one end of the outer jet swirl mechanism is welded to the outer surface of the inner conical tube, and the other end is welded and fixed to the bottom port of the outer conical tube.

[0014] Furthermore, the inner jet channel is connected to the delivery pipe and desulfurizer spray tank of the spray system through a first connecting hose at the top of the inner center tube; the outer jet channel is connected to the high-pressure nitrogen system through a second connecting hose on the upper side of the outer sleeve.

[0015] Furthermore, the bottom plane of the inner center tube is flush with the bottom plane of the outer sleeve, the top end surface of the inner arc tube is flush with the top end surface and the bottom end surface of the outer arc sleeve, the top end surface and the bottom end surface of the inner conical tube are flush with the outer conical tube, and the bottom end surface of the outer jet swirl mechanism is flush with the bottom end surface of the outer conical tube.

[0016] Furthermore, the outer jet swirl mechanism comprises a plurality of spiral steel sheets, which are evenly distributed and welded around the outer circumferential surface of the inner conical tube, and the spiral rise angle γ is 65° to 75°.

[0017] Furthermore, the lengths of the inner conical tube and the outer conical tube are both 100-150 mm, the cone angle α of the inner conical tube is 20-30°, and the cone angle β of the outer conical tube is 40-60°.

[0018] Furthermore, the inner jet nozzle is a circular nozzle with a diameter D of 100 to 150 mm.

[0019] Furthermore, the outer jet nozzle is an annular nozzle, and the annular gap width δ is 0.5-1.5 mm.

[0020] Furthermore, the double-jet nozzle sprays in a direction perpendicular to the stirring vortex surface, and the relationship between the distance S between the center point of the nozzle and the stirring axis of the agitator and the agitator rotation radius R is S=(0.8~1.5)R, and the vertical distance L to the liquid surface is L=350~450mm.

[0021] Furthermore, the double-jet nozzle has a spray direction perpendicular to the stirring vortex surface, and the relationship between the distance S between the center point of the nozzle and the stirring axis of the agitator and the agitator rotation radius R is S=(1.0~2.0)R, and the vertical distance L to the liquid surface is L=400~500mm.

[0022] A method for using the telescopic chute for injecting and dosing the molten iron KR desulfurizing agent as described above is also provided, and the method is operated and used according to the following molten iron KR stirring desulfurization process steps:

[0023] 1) The temperature of the molten iron in the incoming molten iron tank is measured, sampled and the slag is removed. According to the molten iron temperature, composition, molten iron volume, target sulfur, etc., the self-feedback corrected empirical desulfurization model in the operating system is used to calculate the desulfurizer dosage W and the stirring time τ;

[0024] 2) Start the agitator lifting trolley to immerse the agitator into the molten iron, so that the immersion depth h of the bottom surface of the agitator blade is 50-55% of the static liquid level depth H of the molten iron;

[0025] 3) The stirrer is started to rotate, and the stirring speed is adjusted so that the radial exposed length m of the upper surface of the stirrer blade in the vortex is 15 to 50 mm, and the radial stirring is performed at a stable speed;

[0026] 4) Start the lifting mechanism to drive the outer casing down to adjust the telescopic chute for KR desulfurizer injection and addition, and control the telescopic chute according to the requirements of S = (0.8 ~ 1.5) R, L = 350 ~ 450mm; where S is the distance between the center point of the nozzle and the stirring axis of the agitator, and R is the rotation radius of the agitator;

[0027] 5) According to the desulfurizer dosage W and stirring time τ obtained by model calculation, the desulfurizer dosage acceleration q is calculated using the formula q=W÷(τ-4.5), and the desulfurizer injection acceleration of the inner jet nozzle is adjusted accordingly. At the same time, the nitrogen gas source of the outer jet nozzle is turned on, and the desulfurizer is sprayed to the molten iron surface through the inner jet circular nozzle, and the nitrogen cyclone jet is sprayed through the outer jet annular nozzle. The gas injection flow rate is 50-100m 3 / h; After spraying for τ-4.5min, close the internal and external jet spraying systems, start the lifting mechanism to lift the telescopic slide back to its original position;

[0028] 6) Continue to rotate the stirrer at a stable stirring speed until the stirring time reaches τ, then stop stirring and lift the stirrer back to its original position; measure the temperature of the molten iron, take samples and remove the slag to complete the desulfurization treatment of the molten iron.

[0029] Compared with the existing straight-cylindrical desulfurizer injection and dosing telescopic chute, the KR desulfurizer injection and dosing telescopic chute of the present invention is designed with a composite structure consisting of an inner jet straight pipe section, an inner jet special-shaped pipe section, an outer jet straight pipe section, an outer jet special-shaped pipe section, an outer jet swirl mechanism, and a double jet nozzle, thereby forming an inner and outer coaxial double jet flow structure of a carrier gas injection desulfurizer central jet and an outer ring nitrogen injection jet. Through a large number of water model tests and industrial test comparisons, it can be seen that the external annular nitrogen jet in the coaxial double jet has a boosting and shielding effect on the central desulfurizer jet, inhibits the kinetic energy attenuation of the desulfurizer central jet, improves the desulfurizer's ability to penetrate the molten iron liquid surface, reduces the desulfurizer molten iron stirring and suction resistance, increases the desulfurizer stirring and suction volume and the desulfurization reaction utilization rate, and at the same time, shields the high-temperature natural convection of the molten iron tank surface on the entrainment and dust removal suction escape of the desulfurizer central jet, reducing the desulfurizer escape loss; through the surrounding coordination of the external annular nitrogen jet kinetic energy on the impact zone of the central desulfurizer jet, the impact rebound and lifting of the desulfurizer injection liquid surface is inhibited, and the convection entrainment and dust removal escape of the desulfurizer addition process are further inhibited. The invention discloses a novel method for the invention of the present invention to reduce the loss of desulfurizer by escaping and reducing the loss of desulfurizer by escaping; the design of the external jet swirl mechanism increases the swirl intensity of the external annular nitrogen jet, improves the penetration ability of the external annular nitrogen jet on the natural convection flow field of the liquid surface and the surrounding shielding integrity of the external annular jet on the central desulfurizer jet, and strengthens its shielding and boosting efficiency on the central desulfurizer jet; the experimental research and optimization of the injection direction of the double-jet nozzle and the center point position of the nozzle further improve the penetration ability of the central jet desulfurizer on the molten iron liquid surface and the boosting and shielding effect of the external nitrogen annular swirl jet; the optimization of the structural size of the double-jet nozzle ensures the stable realization of the above-mentioned positive effects, especially the synergistic effect of the external nitrogen annular swirl jet on the central jet of the desulfurizer. By optimizing the composition and particle size of the desulfurizer, not only the escape loss in the desulfurizer injection and addition process is reduced, but also the specific surface area of ​​the desulfurizer is increased, thereby improving the reaction utilization rate of the desulfurizer; by mechanically connecting and installing the outer casing and the conventional inclined lifting mechanism and adjusting the installation angle, the precise control of the injection direction and the center position of the nozzle of the KR desulfurizer injection and addition telescopic chute of the present invention is ensured, which facilitates the technical implementation of the existing KR desulfurization station, greatly reduces the amount of technical implementation and transformation engineering and the difficulty of implementation, and improves the technical adaptability.

[0030] For the method of using the telescopic chute for injecting and dosing the molten iron KR desulfurizer of the present invention, in step 1), a conventional self-feedback corrected empirical desulfurization model is used to calculate the desulfurizer dosage W (kg) and the stirring time τ (min), and the self-feedback correction function of the model is used to complete the optimization of the desulfurization model adapted to the telescopic chute for injecting and dosing the molten iron KR desulfurizer of the present invention, so as to ensure the reliable realization of the technical implementation effect. Through the control of the insertion depth and speed of the stirrer in steps 2) and 3) and the control of the injection direction and the center point of the double jet nozzle in step 4), the best desulfurizer entrainment and mixing dynamic conditions are created for the desulfurizer injection and dosing using the telescopic chute of the present invention; through the optimization of the desulfurizer injection speed and the nitrogen flow rate of the outer jet annular nozzle in step 5), the desulfurizer stirring and entrainment rate is improved, the desulfurizer escape loss is reduced, and the high-efficiency entrainment mixing and interface desulfurization reaction of the desulfurizer in the set fine particle size range is achieved; through the optimization of the stirring duration in step 6), the reaction time of the desulfurizer is guaranteed and the desulfurizer reaction utilization rate is improved.

[0031] From the above, it can be seen that compared with the prior art, the present invention meets the technical requirements of efficient entrainment mixing and interfacial desulfurization reaction of the desulfurizer in the set fine particle size range through the stable performance of the above-mentioned positive effects, and achieves the comprehensive purposes of shortening the KR stirring time of molten iron, reducing the consumption of desulfurizer, stabilizing the desulfurization effect of molten iron, reducing slag removal iron loss and desulfurization molten iron temperature drop. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the telescopic chute structure for injecting and adding KR desulfurizing agent into molten iron according to the present invention;

[0033] Figure 2 for Figure 1 An enlarged schematic diagram of the combination of the inner conical tube and the outer conical tube;

[0034] Figure 3 for Figure 2 Schematic diagram from top view;

[0035] Figure 4 It is a schematic diagram of desulfurizer injection and dosing on the vertical stirring vortex surface with double jet nozzles;

[0036] Figure 5 This is a schematic diagram of the double jet nozzle vertically spraying desulfurizer on the static molten iron liquid surface.

[0037] The components in the figure are numbered as follows:

[0038] Inner jet channel 1, central tube 1.1, first connecting hose 1.2, outer jet channel 2, outer sleeve 2.1, second connecting hose 2.2, inner arc tube 3, outer arc sleeve 4, outer jet swirl mechanism 5, conical tube 6, outer conical tube 7, inner jet nozzle 8, outer jet nozzle 9. DETAILED DESCRIPTION

[0039] 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.

[0040] like Figure 1 , 2 The telescopic chute for injecting KR desulfurizing agent into molten iron as shown in 3 comprises an inner center tube 1.1, an outer sleeve 2.1, an inner arc tube 3, an outer arc sleeve 4, an inner conical tube 6 and an outer conical tube 7, as well as an outer jet swirl mechanism 5; the inner center tube 1.1 and the outer sleeve 2.1 are coaxially arranged, the inner arc tube 3 and the outer arc sleeve 4 are concentrically arranged, and the inner conical tube 6 and the outer conical tube 7 are arranged on a common axis. The inner center tube 1.1 is inserted into the center hole of the outer sleeve 2.1, and the bottom plane of the inner center tube 1.1 is flush with the bottom plane of the outer sleeve 2.1, the top end of the inner center tube 1.1 extends out of the top end of the outer sleeve 2.1, and the top end of the outer sleeve 2.1 is welded and sealed with the outer cylindrical surface of the inner center tube 1.1; the top end surface of the inner arc tube 3 is flush with the top end surface and the bottom end surface of the outer arc sleeve 4, and the top end surface of the inner arc tube 3 is welded with the bottom end surface of the inner center tube 1.2, and the top end surface of the outer arc sleeve 4 is welded with the lower end surface of the outer sleeve 2.1; the inner arc The top end surface and bottom end surface of the conical tube 6 are flush with those of the outer conical tube 7, and the top end surface of the inner conical tube 6 is welded to the bottom end surface of the inner arc tube 3, and the top end surface of the outer conical tube 7 is welded to the bottom end surface of the outer arc sleeve 4; the inner center hole of the inner center tube 1.1, the inner center hole of the inner arc tube and the inner conical hole of the inner conical tube are connected to form an inner jet channel 1, and the annular cavity between the outer sleeve and the inner center tube, the annular cavity between the inner arc tube and the outer arc sleeve, and the gap between the inner conical tube and the outer conical tube are connected to form an outer jet channel 2. The inner jet channel 1 is connected to the delivery pipe and desulfurizer spray tank of the spray system through the first connecting hose 1.2 at the top of the inner central tube 1.2; the outer jet channel 2 is connected to the high-pressure nitrogen system through the second connecting hose 2.2 on the upper side of the outer sleeve 2.1; the bottom outlet of the inner jet channel 1 is the inner jet nozzle 8, and the bottom outlet of the outer jet channel 2 is the outer jet nozzle 9 to form a double jet nozzle. One end of the outer jet swirl mechanism 5 is welded to the outer surface of the inner conical tube 6, and the other end is welded and fixed to the bottom port of the outer conical tube 7, and the bottom end surface of the outer jet swirl mechanism 5 is flush with the bottom end surface of the outer conical tube 7.

[0041] The outer jet swirl mechanism 5 includes a plurality of spiral steel sheets, which are uniformly distributed and welded around the outer surface of the inner conical tube, and the spiral rise angle γ is 65° to 75°. The lengths of the inner conical tube 3.2 and the outer conical tube 4.2 are both 100 to 150 mm, the cone angle α of the inner conical tube 6 is 20 to 30°, and the cone angle β of the outer conical tube 7 is 40 to 60°. The inner jet nozzle 8 is a circular nozzle with a diameter D of 100 to 150 mm; the outer jet nozzle 9 is an annular nozzle with an annular gap width δ of 0.5 to 1.5 mm. The injection direction of the double-jet nozzle is perpendicular to the stirring vortex surface. The relationship between the distance S between the center point of the nozzle and the stirring axis of the agitator and the agitator rotation radius R is S = (0.8 ~ 1.5) R (or S = (0.8 ~ 1.5) R), and the vertical distance L to the liquid surface is L = 350 ~ 450 mm (or L = 400 ~ 500 mm).

[0042] The outer sleeve 2.1 of the KR desulfurizer injection and dosing telescopic chute is mechanically connected and installed with a conventional tilting lifting mechanism. Through the adjustment of the installation angle and telescopic length of the outer sleeve 2.1 and the driving of the lifting mechanism, the precise control of the injection direction and the center position of the nozzle of the KR desulfurizer injection and dosing telescopic chute is achieved. Except for the KR desulfurizer injection and dosing telescopic chute structure and the high-pressure nitrogen system with an additional outer annular swirl jet, other equipment is the same as the conventional hot metal KR desulfurization equipment.

[0043] The use method of the telescopic chute for injecting KR desulfurizer into molten iron, such as Figure 4 As shown, the hot metal KR stirring desulfurization process is operated and used according to the following steps:

[0044] 1) The temperature of the molten iron in the incoming molten iron tank is measured, sampled and slag removed. According to the molten iron temperature, composition, molten iron volume, target sulfur, etc., the self-feedback corrected empirical desulfurization model in the operating system is used to calculate the desulfurizer dosage W (Kg) and the stirring time τ (min).

[0045] 2) Start the agitator lifting trolley and immerse the agitator into the molten iron so that the immersion depth h of the bottom surface of the agitator blade is 50-55% of the static liquid level depth H of the molten iron.

[0046] 3) The stirrer is started to rotate, and the stirring speed is adjusted so that the radial exposed length m of the upper surface of the stirrer blade in the vortex is 15 to 50 mm, and the radial stirring is performed at a stable speed;

[0047] 4) Start the lifting mechanism to drive the outer casing down to adjust the telescopic chute for KR desulfurizer injection and control the telescopic chute according to the requirements of S = (0.8 ~ 1.5) R, L = 350 ~ 450 mm.

[0048] 5) According to the desulfurizer dosage W (Kg) and stirring time τ (min) obtained by model calculation, the desulfurizer addition acceleration q (Kg / min) is calculated using the experimental optimization formula q = W ÷ (τ-4.5), and the desulfurizer injection acceleration of the inner jet nozzle is adjusted accordingly. At the same time, the nitrogen gas source of the outer jet nozzle is turned on, and the desulfurizer is sprayed to the molten iron surface through the inner jet circular nozzle, and the nitrogen cyclone jet is sprayed through the outer jet annular nozzle. The gas injection flow rate is 50-100m 3 / h; After spraying for τ-4.5min, close the internal and external jet spraying systems, and start the lifting mechanism to lift the telescopic slide back to its original position.

[0049] 6) Keep the stirring speed stable and continue to rotate the stirrer until the stirring time reaches τ, then stop stirring and lift the stirrer back to its original position. Then measure the temperature, take samples and remove the slag from the molten iron to complete the desulfurization treatment of the molten iron.

[0050] Through industrial tests at the KR stirring desulfurization station in a 200-ton molten iron tank, the desulfurizer injection acceleration was 218Kg / min, the injection time was 5.5min, the whole desulfurization stirring time was 10min, and the desulfurizer consumption per ton of iron was reduced from 7.5Kg to 6Kg.

[0051] Example 2

[0052] A KR desulfurizer injection and dosing telescopic chute, such as Figure 5 As shown, the difference from Example 1 is that: except that the injection direction of the double jet nozzle is perpendicular to the static liquid surface of the molten iron, the relationship between the distance S between the center point of the nozzle and the stirring axis of the stirrer and the rotation radius R of the stirrer is S=(1.0~2.0)R, and the vertical distance L from the liquid surface is 400~500mm; the desulfurizer is composed of active lime and fluorite, and the weight percentage chemical composition is: CaO 74~80%, CaF25~10%, SiO2≤5%, S≤0.05%, H2O≤1%; the desulfurizer particle size range is 0.1~1.0mm, and the preferred range is 0.4~1.0mm. In the method for using the telescopic chute for injecting and adding the molten iron KR desulfurizer, the control requirements of the telescopic chute in step 4) are S=(1.0~2.0)R, L=400~500mm. Others are the same as Example 1.

[0053] Through industrial tests at the KR stirring desulfurization station in a 300-ton molten iron tank, the desulfurizer injection acceleration was 290.5Kg / min, the injection time was 6.5min, the whole desulfurization stirring time was 11min, and the desulfurizer consumption per ton of iron was reduced from 7.5Kg to 6.3Kg.

Claims

1. A telescopic chute for injecting KR desulfurizing agent into molten iron, characterized in that: The invention comprises an inner central tube (1.1), an outer sleeve (2.1), an inner arc tube (3), an outer arc sleeve (4), an inner conical tube (6), an outer conical tube (7), and an outer jet swirl mechanism (5); the inner central tube (1.1) and the outer sleeve (2.1) are coaxially arranged, the inner arc tube (3) and the outer arc sleeve (4) are coaxially arranged, and the inner conical tube (6) and the outer conical tube (7) are arranged on a common axis; the inner central tube (1.1) is inserted into the central hole of the outer sleeve (2.1), the top end of the inner central tube (1.1) extends out of the top end of the outer sleeve (2.1), and the top end of the outer sleeve (2.1) and the outer cylindrical surface of the inner central tube (1.1) are welded and sealed; the top end surface of the inner arc tube (3) and the bottom end surface of the inner central tube (1.1) are welded together, and the top end surface of the outer arc sleeve (4) and the bottom end surface of the outer sleeve (2.1) are welded together. ; The top end surface of the inner conical tube (6) is welded to the bottom end surface of the inner arc tube (3), and the top end surface of the outer conical tube (7) is welded to the bottom end surface of the outer arc sleeve (4); the inner center hole of the inner center tube (1.1), the inner center hole of the inner arc tube (3) and the inner conical hole of the inner conical tube (6) are connected to form an inner jet channel (1), and the annular cavity between the outer sleeve and the inner center tube, the annular cavity between the inner arc tube and the outer arc sleeve, and the gap between the inner conical tube and the outer conical tube are connected to form an outer jet channel (2); the bottom outlet of the inner jet channel (1) is an inner jet nozzle (8), and the bottom outlet of the outer jet channel (2) is an outer jet nozzle (9) to form a double jet nozzle; one end of the outer jet swirl mechanism (5) is welded to the outer surface of the inner conical tube (6), and the other end is welded and fixed to the bottom end of the outer conical tube (7); The method of using the telescopic chute for injecting and dosing the hot metal KR desulfurizer is to follow the following hot metal KR stirring desulfurization process steps: 1) Measure the temperature, take samples and remove the slag before the molten iron in the incoming molten iron ladle. According to the molten iron temperature, composition, molten iron volume and target sulfur, the self-feedback corrected empirical desulfurization model in the operating system is used to calculate the desulfurizer dosage W and the stirring time τ; 2) Start the agitator lifting trolley to immerse the agitator into the molten iron, so that the immersion depth h of the bottom surface of the agitator blade is 50-55% of the static liquid level depth H of the molten iron; 3) The stirrer is started to rotate, and the stirring speed is adjusted so that the radial exposed length m of the upper surface of the stirrer blade in the vortex is 15 to 50 mm, and the radial stirring is performed at a stable speed; 4) Start the lifting mechanism to drive the outer casing to descend and adjust the telescopic chute for KR desulfurizer injection and addition, and control the telescopic chute according to the requirements of S = (0.8-1.5) R, L = 350-450 mm; the injection direction of the double jet nozzle is perpendicular to the stirring vortex surface, the distance between the center point of the nozzle and the stirring axis of the agitator is S, the vertical distance to the liquid surface is L, and R is the rotation radius of the agitator; 5) According to the desulfurizer dosage W and stirring time τ obtained by model calculation, the desulfurizer dosage acceleration q is calculated using the formula q=W÷(τ-4.5), and the desulfurizer injection acceleration of the inner jet nozzle is adjusted accordingly. At the same time, the nitrogen gas source of the outer jet nozzle is turned on, and the desulfurizer is sprayed to the molten iron surface through the inner jet circular nozzle, and the nitrogen cyclone jet is sprayed through the outer jet annular nozzle. The gas injection flow rate is 50-100m 3 / h; After spraying (τ-4.5)min, close the internal and external jet spraying systems, start the lifting mechanism to lift the telescopic slide back to its original position; 6) Continue to rotate the stirrer at a stable stirring speed until the stirring time reaches τ, then stop stirring and lift the stirrer back to its original position; measure the temperature of the molten iron, take samples and remove the slag to complete the desulfurization treatment of the molten iron.

2. The telescopic chute for injecting KR desulfurizing agent into molten iron according to claim 1, characterized in that: The inner jet channel (1) is connected to the delivery pipe and the desulfurizer spray tank of the spray system through a first connecting hose (1.2) at the top of the inner central tube (1.1); the outer jet channel (2) is connected to the high-pressure nitrogen system through a second connecting hose (2.2) at the upper side of the outer sleeve (2.1).

3. The telescopic chute for injecting and adding KR desulfurizing agent into molten iron according to claim 1, characterized in that: The bottom plane of the inner center tube (1.1) is flush with the bottom plane of the outer sleeve (2.1); the top end surface of the inner arc tube (3) is flush with the top end surface and the bottom end surface of the outer arc sleeve (4); the top end surface and the bottom end surface of the inner conical tube (6) are flush with the top end surface and the bottom end surface of the outer conical tube (7); and the bottom end surface of the outer jet swirl mechanism (5) is flush with the bottom end surface of the outer conical tube (7).

4. The telescopic chute for injecting KR desulfurizing agent into molten iron according to claim 1, characterized in that: The outer jet swirl mechanism (5) comprises a plurality of spiral steel sheets which are evenly distributed and welded around the outer circumference of the inner conical tube, and the spiral rise angle γ is 65° to 75°.

5. The telescopic chute for injecting KR desulfurizing agent into molten iron according to claim 1, characterized in that: The lengths of the inner conical tube (6) and the outer conical tube (7) are both 100-150 mm, the cone angle α of the inner conical tube (6) is 20-30°, and the cone angle β of the outer conical tube (7) is 40-60°.

6. The telescopic chute for injecting KR desulfurizing agent into molten iron according to claim 1, characterized in that: The inner jet nozzle (8) is a circular nozzle with a diameter D of 100 to 150 mm.

7. The telescopic chute for injecting KR desulfurizing agent into molten iron according to claim 1, characterized in that: The outer jet nozzle (9) is an annular nozzle, and the annular gap width δ is 0.5-1.5 mm.

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