Slag splashing furnace protection method

Abstract

The invention provides a converter slag splashing protection method, a used oxygen lance is a multi-stream oxygen lance, an oxygen lance nozzle comprises a main airflow channel, an auxiliary airflow channel and a peripheral cooling channel which are sequentially sleeved from inside to outside, and the main airflow channel, the auxiliary airflow channel and the peripheral cooling channel are coaxially arranged; the top of the main airflow channel is communicated with a first air supply pipe, and a plurality of inner spraying holes blowing towards the bottom are uniformly formed in the bottom of the main airflow channel in the circumferential direction; an air inlet of the auxiliary air flow channel is communicated with a second air supply pipe, and a plurality of outer spraying holes blowing towards the side wall are formed in the middle of the auxiliary air flow channel in the circumferential direction; the converter slag splashing protection method comprises the following steps that S1, after tapping, a slag modifier is added into a converter; s2, nitrogen spraying and slag splashing are carried out for multiple times to protect the furnace, main airflow is adopted for slag splashing during nitrogen spraying, and main airflow and auxiliary airflow are adopted for slag splashing alternately; and S3, the slag splashing condition of the furnace lining is checked. According to the furnace protection method, a uniform slag splashing layer can be formed on the surface of the furnace lining during slag splashing, so that the furnace body is better protected.

Description

Technical Field

[0001] The invention relates to the technical field of converter steelmaking, and in particular to a slag splashing furnace protection method. Background Art

[0002] The converter and its ancillary equipment have become the main steelmaking equipment used by major steel group companies. Among them, the top-blown oxygen lance is one of the main ancillary devices for its steelmaking production. The device is placed above the converter and blows oxygen into the converter to refine the molten steel, or sprays nitrogen to complete the slag splashing and furnace protection operations.

[0003] The basic principle of slag splashing furnace protection technology is to adjust the composition of the remaining end slag after steel is tapped from the converter, and use the end slag with saturated or supersaturated MgO content to blow out high-pressure nitrogen from the oxygen lance nozzle. Through the splashing of high-pressure nitrogen, a layer of high-melting-point splashing slag layer that is well sintered and attached to the furnace lining is formed on the surface of the furnace lining. The splashing slag layer has good corrosion resistance and can reduce the mechanical scouring of the furnace lining during the steelmaking process, thereby protecting the furnace lining bricks, reducing their damage, and increasing the life of the furnace lining.

[0004] At present, common converter oxygen lances are composed of three layers of steel pipes and gun body nozzles, wherein the inner steel pipe is a gas channel, the sleeve formed between the inner steel pipe and the inner second steel pipe is a cooling water inlet pipe, the sleeve formed between the inner second steel pipe and the outer steel pipe is a cooling water return pipe, the inlet pipe and the return pipe are connected at the gun body nozzle. When in use, oxygen is introduced into the gas channel, and the oxygen is sprayed into the converter through the oxygen nozzle hole of the gun body nozzle made of copper and other materials, and undergoes redox reaction with carbon, silicon and other elements in the steel to release heat and refine the molten steel, or nitrogen is introduced into the gas channel to perform slag splashing furnace protection operation; the cooling water flows through the inlet pipe to the vicinity of the gun body nozzle to cool the oxygen lance and the gun body nozzle, and then returns through the return pipe to take away the heat. However, the design of the oxygen lance of the current slag splashing furnace protection technology has not changed much. On the basis of the existing single gas flow channel, only the number and size of the spray holes are increased. Although it can increase the uniformity of slag coverage around the furnace and improve the effect of slag splashing furnace protection to a certain extent, the effect is limited.

[0005] Chinese patent CN202210870539.7 discloses a method for automatic slag splashing and furnace protection of a converter, comprising the following steps: step 1: control the amount of slag inside the converter after steel is tapped; step 2: adjust the internal composition of the slag inside the converter; step 3: first slag splashing and furnace protection; step 4: second slag splashing and furnace protection, the steps are as follows: adjust the oxygen gun height to 1000mm, and blow nitrogen; the nitrogen blowing time is controlled to 20s; step 5: third slag splashing and furnace protection, the steps are as follows: adjust the oxygen gun height to 800mm, blow nitrogen; the nitrogen blowing time is controlled to 100s; step 6: the last slag splashing and furnace protection, the steps are as follows: adjust the oxygen gun height to 700mm, blow nitrogen, and the nitrogen blowing time is controlled to 100s; step 7: check the slag splashing of the furnace lining. The automatic slag splashing and furnace protection method of the converter adopts scientific slag splashing and furnace protection technology. Through repeated slag splashing operations, it not only avoids the phenomenon of leakage and slag hanging on the inner wall of the furnace, but also ensures the uniformity of the slag hanging thickness because of the multiple gradual progressive forms. However, during smelting in the steel plant, it was found that although the patented slag splashing furnace protection method in which the height of the oxygen lance is gradually reduced can avoid slag leakage in the height direction, the uniformity of the slag layer thickness on the side wall of the converter cannot be guaranteed. The furnace body in the area with thinner slag layer will be damaged during long-term smelting, and the overall life of the converter will be limited.

[0006] The present application proposes a multi-stream oxygen lance, which can form a uniform slag splashing layer on the surface of the furnace lining during slag splashing, thereby better protecting the furnace body. Summary of the invention

[0007] The object of the present invention is to provide a multi-stream oxygen lance and a slag splashing furnace protection method for slag splashing furnace protection in view of the drawbacks of the prior art.

[0008] The technical solution adopted by the present invention to solve its technical problem is:

[0009] A converter slag splashing furnace protection method, the oxygen lance used is a multi-stream oxygen lance, the oxygen lance nozzle includes a main airflow channel, a secondary airflow channel and a peripheral cooling channel which are sequentially sleeved from the inside to the outside, the main airflow channel, the secondary airflow channel and the peripheral cooling channel are coaxially arranged; the top of the main airflow channel is connected to a first air supply pipe, and a plurality of inner spray holes for spraying toward the bottom are uniformly arranged in the circumferential direction at the bottom of the main airflow channel; the air inlet of the secondary airflow channel is connected to a second air supply pipe, and a plurality of outer spray holes for spraying toward the side wall are circumferentially arranged in the middle of the secondary airflow channel;

[0010] The converter slag splashing furnace protection method comprises the following steps:

[0011] S1. After steel is tapped, a slag adjusting agent is added into the converter to adjust the slag composition inside the converter;

[0012] S2, multiple nitrogen spraying to splash slag to protect the furnace, when spraying nitrogen, the main airflow splashing slag, the main airflow + auxiliary airflow splashing slag alternately;

[0013] S3. Check the slag splashing of the furnace lining. Pour out the slag when the requirements are met. The slag splashing furnace protection is completed.

[0014] A further improvement of the present invention is that: a plurality of inner nozzles corresponding to the inner spray holes are provided at the bottom of the oxygen gun, the inner spray holes are connected to the inner nozzles through an inner cone tube, and the inner cone tube runs through the secondary air flow channel; the outer spray holes run through the peripheral cooling channel through an outer nozzle pipe, and an outer nozzle is connected to the outer end of the outer nozzle pipe.

[0015] A further improvement of the present invention is that the inner diameter of the inner cone tube gradually increases from the inlet end to the outlet end, and the angle α between the central axis of the inner cone tube and the central axis of the main air flow channel is 10° to 15°.

[0016] A further improvement of the present invention is that the height h of the outer spray hole from the bottom of the secondary airflow channel is 30 to 50 mm; the outer spray pipe is a straight pipe inclined upward, and the angle β between the central axis of the outer spray pipe and the horizontal direction is 15° to 25°.

[0017] A further improvement of the present invention is that the Mach number of the main airflow is 1.85-2.5, and the Mach number of the secondary airflow is 2.5-3.

[0018] In step S1, the slag conditioning agents are coke powder and quicklime; the amount of coke powder added is 1.0-1.1 kg per ton of steel, and the amount of quicklime added is 1.0-2.3 kg per ton of steel.

[0019] In the step S1, after adding the slag conditioning agent, the converter is subjected to nitrogen blowing treatment to fully remove ferrous oxide; the oxygen lance height during nitrogen blowing is 600 mm, only the main gas flow is used for nitrogen blowing, and the nitrogen blowing time is 20 seconds.

[0020] The step S2 includes slag splashing operations at four different gun positions, and the specific method is as follows:

[0021] S21, one-time slag splashing furnace protection

[0022] Adjust the oxygen lance height to 1500mm, open the first nitrogen branch, keep the second nitrogen branch closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s;

[0023] Maintain the oxygen lance height at 1500mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s;

[0024] S22, secondary slag splashing furnace protection

[0025] Adjust the oxygen lance height to 1200mm, open the first nitrogen branch, keep the second nitrogen branch closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s;

[0026] Maintain the oxygen lance height at 1200mm, rotate the furnace body to tilt -10 to 10°, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s;

[0027] S23, three-time slag splashing furnace protection

[0028] Adjust the oxygen lance height to 900mm, open the first nitrogen branch, keep the second nitrogen branch closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s;

[0029] Maintain the oxygen lance height at 900mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s;

[0030] S24, four times of slag splashing to protect the furnace

[0031] Adjust the oxygen gun height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s;

[0032] Maintain the oxygen gun height at 600mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s.

[0033] In step S2, when only the main airflow is used to spray nitrogen, the spraying pressure is 1.2-1.5 MPa; when the main airflow + the secondary airflow are used to spray nitrogen at the same time, the total pressure of the main airflow and the secondary airflow is 1.2-1.5 MPa, wherein the main airflow flow accounts for more than 60% of the total nitrogen supply, and the secondary airflow flow accounts for less than 40% of the total nitrogen supply.

[0034] Through the above technical solution, the beneficial effects obtained by the present invention are:

[0035] The invention discloses a converter slag splashing furnace protection method, which adopts a multi-stream oxygen lance with a special structure. The oxygen lance nozzle comprises a main airflow channel and a secondary airflow channel. The main airflow channel is sprayed downward, and the secondary airflow channel is sprayed toward the outer peripheral side wall. Therefore, nitrogen can be blown from multiple directions simultaneously during the slag splashing furnace protection operation, ensuring that all parts of the inner wall of the converter can be evenly slaged, and the slag layer thickness is uniform, thereby improving the service life of the converter.

[0036] The multi-stream oxygen lance of the present invention can be used for smelting oxygen blowing and slag splashing nitrogen blowing. The type of gas source and the pressure of each gas flow are adjusted according to actual use requirements so that the blowing requirements can be met.

[0037] In the method of the present invention, the position of the blowing gun is continuously moved downward, and the main airflow nitrogen blowing and the main and auxiliary airflow nitrogen blowing operations are combined. Due to the low operating gun position, the impact intensity of the airflow of the main channel on the molten pool is relatively large, and the depth and surface radial velocity of the pit formed cause splashing when the droplets separate from the pit surface. Due to the effect of the tangential impulse, the sticky slag can be promoted to spirally rise, and the airflow through the auxiliary flow channel provides a tangential impulse, which can better interfere with the rotation speed and direction of the splashing slag. When the slag is splashed, a uniform splashing slag layer can be formed on the surface of the furnace lining, which better protects the furnace body.

[0038] During the local slag splashing furnace protection operation, the present invention tilts the furnace body by -10° to 10°, which promotes more sticky slag to adhere locally to the steel outlet surface and the feed surface, thereby better protecting vulnerable parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a multi-stream oxygen lance nozzle of the present invention;

[0040] Figure 2 This is a schematic diagram of the gas supply pipeline connection structure of the multi-stream oxygen lance nozzle.

[0041] In the figure, 1, main air flow channel, 1-1, inner spray hole, 1-2, inner cone tube, 1-3, inner nozzle, 1-4, reinforcing support, 2, secondary air flow channel, 2-1, outer spray hole, 2-2, outer nozzle, 2-3, outer nozzle, 3, peripheral cooling channel, 3-1, return water chamber, 3-2, water inlet chamber, 4, first air supply pipe, 5, second air supply pipe, 6, flow control valve, 7-1, first oxygen branch pipe, 7-2, second oxygen branch pipe, 8-1, first nitrogen branch pipe, 8-2, second nitrogen branch pipe, 9, oxygen supply main pipe, 10, nitrogen supply main pipe. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] See also Figure 1 A converter slag splashing protection method includes a nozzle, which includes a main airflow channel 1, a secondary airflow channel 2 and a peripheral cooling channel 3 which are sequentially arranged from the inside to the outside, and the main airflow channel 1, the secondary airflow channel 2 and the peripheral cooling channel 3 are all coaxially arranged.

[0044] The main airflow channel 1 is a cylindrical channel arranged in the middle of the secondary airflow channel 2. The top of the main airflow channel 1 is connected to the first air supply pipe 4. The bottom of the main airflow channel 1 is uniformly provided with a plurality of inner spray holes 1-1 in the circumferential direction. The bottom of the secondary airflow channel 2 is provided with a plurality of inner spray heads 1-3 corresponding to the inner spray holes 1-1. The inner cone tube 1-2 runs through the secondary airflow channel 2 but is not connected. The inner spray holes 1-1 are connected to the inner spray heads 1-3 through the inner cone tube 1-2. After the main airflow from the first air supply pipe 4 enters the main airflow channel 1, it is sprayed downward by the inner spray heads 1-3 through the inner cone tube 1-2.

[0045] In order to ensure that the air pressure of each inner nozzle 1-3 is uniform and stable, the bottom of the main air flow channel 1 is set to be an arc shape to avoid flow dead corners.

[0046] The number of the inner spray holes 1 - 1 is preferably 4 to 6.

[0047] The inner diameter of the inner cone tube 1-2 gradually increases from the inlet end to the outlet end, and the angle α between the central axis of the inner cone tube 1-2 and the central axis of the main airflow channel 1 is 10° to 15°. The Mach number of the gas in the inner cone tube 1-2 is 1.85 to 2.5.

[0048] In order to improve the support stability of the main air flow channel 1, a reinforcing support 1-4 is further provided between the bottom of the main air flow channel 1 and the bottom of the secondary air flow channel 2.

[0049] The secondary airflow channel 2 is arranged around the main airflow channel 1, and the secondary airflow channel 2 is completely separated from the main airflow channel 1. The air inlet of the secondary airflow channel 2 is connected to the second air supply pipe 5. A plurality of external spray holes 2-1 are opened in the middle of the secondary airflow channel 2 along the circumferential direction to spray toward the side wall. The external spray holes 2-1 penetrate the peripheral cooling channel 3 through the external spray pipe 2-2, and the external nozzle 2-3 is connected to the outer end of the external nozzle 2-2. After the secondary airflow from the second air supply pipe 5 enters the secondary airflow channel 2, it is sprayed toward the circumferential direction of the converter side wall through the external spray holes 2-1 by the external nozzle 2-3.

[0050] The height h of the outer spray holes 2-1 from the bottom of the secondary air flow channel 2 is 30-50 mm; the number of the outer spray holes 2-1 is preferably four, and can also be set to a greater even number, uniformly distributed along the circumferential direction.

[0051] The outer nozzle 2-2 is a straight tube inclined upward, and the angle β between the central axis of the outer nozzle 2-2 and the horizontal direction is 15° to 25°. The Mach number of the gas in the outer nozzle 2-2 is 2.5 to 3. The secondary airflow ejected by the outer nozzle 2-3 has a faster impact force than the main airflow ejected by the inner nozzle 1-3, thereby changing the direction and angle of the main airflow to lead out the splashing slag.

[0052] By setting the inner nozzle angle α and the outer nozzle angle β, the gas injection direction is more suitable for slag splashing, and the dead corner of slag splashing is eliminated through the coordination of the main airflow and the auxiliary airflow.

[0053] Each of the outer nozzles 2-2 is provided with an independent control valve, which can open one or several secondary flow channels according to needs to adjust the injection direction of the interference slag splashing.

[0054] The peripheral cooling channel 3 includes a water return chamber 3-1 close to the secondary airflow channel 2 and a water inlet chamber 3-2 far from the secondary airflow channel 2. The bottom of the water return chamber 3-1 is connected to the bottom of the water inlet chamber 3-2 to achieve the flow of circulating water. The water inlet chamber 3-2 is connected to the cooling water inlet pipe, and the water return chamber 3-1 is connected to the cooling water return pipe.

[0055] The first air supply pipe 4 connected to the main air flow channel 1 and the second air supply pipe 5 connected to the secondary air flow channel 2 are both provided with independently controlled flow control valves 6. The flow control valves 6 can adjust the flow rate and flow between the main air flow in the main air flow channel 1 and the secondary air flow in the secondary air flow channel 2, thereby ensuring that the inner and outer layers of air flow can simultaneously adjust the angle and speed of slag splashing in the slag splashing furnace protection, thereby forming uniform protection on the furnace body.

[0056] Specifically, if Figure 2 As shown, the first gas supply pipe 4 is connected to the first oxygen branch pipe 7-1 and the first nitrogen branch pipe 8-1 respectively, and the second gas supply pipe 5 is connected to the second oxygen branch pipe 7-2 and the second nitrogen branch pipe 8-2 respectively. The first oxygen branch pipe 7-1 and the second oxygen branch pipe 7-2 are connected to the oxygen supply main pipe 9 respectively, and the first nitrogen branch pipe 8-1 and the second nitrogen branch pipe 8-2 are connected to the nitrogen supply main pipe 10 respectively. The first oxygen branch pipe 7-1, the second oxygen branch pipe 7-2, the first nitrogen branch pipe 8-1, and the second nitrogen branch pipe 8-2 are respectively provided with valves that can be opened and closed independently. During the converter smelting process, the first oxygen branch pipe 7-1 and the second oxygen branch pipe 7-2 are opened to top blow oxygen into the molten steel; when splashing slag to protect the furnace, the first nitrogen branch pipe 8-1 and the second nitrogen branch pipe 8-2 are opened to provide slag splashing power.

[0057] A slag splashing furnace protection method for a converter comprises the following steps:

[0058] S1. After steel is tapped, a slag adjusting agent is added into the converter to adjust the slag composition inside the converter;

[0059] S2, multiple nitrogen spraying and slag splashing to protect the furnace;

[0060] S3. Check the slag splashing condition of the furnace lining. Pour out the slag when the requirement is met. The slag splashing furnace protection is completed.

[0061] In step S1, the slag in the converter can be completely retained, or part of the slag can be transferred and the total amount of slag can be controlled to 10% to 15% of the converter capacity. After the slag amount is controlled, the thickness of the slag splashing layer is highly uniform and the slag splashing effect is better. In the case where all the slag is retained, since the amount of slag in each batch is not exactly the same, a large amount of slag may cause the thickness of the slag splashing layer to be locally too thick, but there is no other adverse effect on the furnace body.

[0062] The slag conditioning agent includes coke powder and quicklime. The amount of coke powder added is usually 1.0-1.1 kg per ton of steel, preferably 1.05 kg per ton of steel; the amount of quicklime added is usually 1.0-2.3 kg per ton of steel, preferably 1.05-2.10 kg per ton of steel.

[0063] After adding the slag conditioning agent, the converter needs to be nitrogen blown to fully remove ferrous oxide. Generally speaking, the oxygen gun height is 600mm and the nitrogen blowing time is 20s. During nitrogen blowing, only the inner nozzle is used for main airflow blowing.

[0064] The step S2 includes slag splashing operations at four different gun positions, and the specific process is as follows:

[0065] S21, one-time slag splashing furnace protection

[0066] Adjust the oxygen gun height to 1500mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle (main airflow) for 100s;

[0067] Maintain the oxygen lance height at 1500mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, and blow nitrogen through the inner nozzle (main airflow) and the outer nozzle (secondary airflow) at the same time, and the blowing time is 100s;

[0068] S22, secondary slag splashing furnace protection

[0069] Adjust the oxygen gun height to 1200mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle (main airflow) for 100s;

[0070] Maintain the oxygen lance height at 1200mm, rotate the furnace body to tilt -10 to 10°, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, and blow nitrogen through the inner nozzle (main airflow) and the outer nozzle (secondary airflow) at the same time for 100s to ensure that there is slag adhesion on both the feeding surface and the steel tapping surface of the furnace lining;

[0071] S23, three-time slag splashing furnace protection

[0072] Adjust the oxygen gun height to 900mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle (main airflow) for 100s;

[0073] Maintain the oxygen lance height at 900 mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, and blow nitrogen through the inner nozzle (main airflow) and the outer nozzle (secondary airflow) at the same time for 100 seconds;

[0074] S24, four times of slag splashing to protect the furnace

[0075] Adjust the oxygen gun height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle (main airflow) for 100s;

[0076] Maintain the oxygen gun height at 600 mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, and blow nitrogen through the inner nozzle (main airflow) and the outer nozzle (secondary airflow) at the same time for 100 seconds.

[0077] In step S3, if the thickness of the local slag layer is insufficient after checking the slag splashing of the furnace lining, the oxygen lance needs to be lowered to the vicinity of the defective position for supplementary spraying. During supplementary spraying, nitrogen blowing can be selected from the inner or outer spray holes according to the actual position of the slag to be supplemented.

[0078] In the above-mentioned slag splashing process, when only the main airflow is used to spray nitrogen, the spraying pressure is 1.2-1.5Mpa; when the main airflow + secondary airflow are used to spray nitrogen at the same time, the total pressure of the main airflow and the secondary airflow is 1.2-1.5Mpa, the main airflow flow accounts for more than 60% of the total nitrogen supply, and the secondary airflow flow accounts for less than 40% of the total nitrogen supply.

[0079] It should be noted that in the above-mentioned slag splashing process, when the main airflow and the secondary airflow are used to spray nitrogen to splash the slag at the same time, the furnace body can be tilted, that is, the furnace body is rotated and tilted by -10 to 10 degrees, which can better spray to the dead corners of the furnace body and improve the uniformity of the slag layer. However, for the second slag splashing in step S32, the slag splashing height is just near the feed surface and the steel-out surface. The tilting furnace body operation is better for ensuring that the slag adheres to the feed surface and the steel-out surface of the furnace lining. Therefore, the tilting furnace body operation when spraying the secondary airflow in step S32 is a required operation, and the operation of spraying the secondary airflow in other steps is an optional operation, which is specifically selected according to the state of the converter.

[0080] The present invention is further described below by way of examples and comparative examples. The following examples are all actual production data of the steelmaking plant of Delong Steel Co., Ltd.

[0081] Example 1

[0082] The slag splashing furnace protection method comprises the following steps:

[0083] S1. After steel is tapped, all the slag inside the converter is retained, the amount of molten steel is about 95 tons, and the amount of slag is about 11-12 tons; 100kg of coke powder and 150kg of quicklime are added to deoxidize the slag and adjust the slag composition inside the converter; then the oxygen lance height is adjusted to 600mm, and nitrogen is blown to remove ferrous oxide, and the nitrogen blowing time is 20s;

[0084] S2, spray nitrogen and slag to protect the furnace at four different gun positions, the specific steps include:

[0085] S21, one-time slag splashing furnace protection

[0086] Adjust the oxygen gun height to 1500mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle with a blowing pressure of 1.2-1.5Mpa and a blowing time of 100s;

[0087] Maintain the oxygen lance height at 1500mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the blowing pressure of the inner nozzle is 1.2Mpa, the blowing pressure of the outer nozzle is 0.3Mpa, and the blowing time is 100s;

[0088] S22, secondary slag splashing furnace protection

[0089] Adjust the oxygen lance height to 1200mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0090] Maintain the oxygen lance height at 1200mm, rotate the furnace body to tilt -10 to 10°, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the inner nozzle blowing pressure is 1.2Mpa, the outer nozzle blowing pressure is 0.3Mpa, and the nitrogen blowing time is 100s to ensure that there is slag adhesion on both the feeding surface and the steel tapping surface of the furnace lining;

[0091] S23, three-time slag splashing furnace protection

[0092] Adjust the oxygen lance height to 900mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0093] Maintain the oxygen gun height at 900mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the blowing pressure of the inner nozzle is 1.1Mpa, the blowing pressure of the outer nozzle is 0.4Mpa, and the blowing time is 100s;

[0094] S24, four times of slag splashing to protect the furnace

[0095] Adjust the oxygen lance height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0096] Maintain the oxygen lance height at 600mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the blowing pressure of the inner nozzle is 1.0Mpa, the blowing pressure of the outer nozzle is 0.5Mpa, and the blowing time is 100s;

[0097] S3. Check the slag splashing of the furnace lining and find that the thickness of the slag splashing layer is uniform and meets the requirements; pour out the slag and the slag splashing furnace protection is completed.

[0098] Example 2

[0099] The slag splashing furnace protection method comprises the following steps:

[0100] S1. After steel is tapped, all the slag inside the converter is retained, the amount of molten steel is about 95 tons, and the amount of slag is about 11-12 tons; 100kg of coke powder and 150kg of quicklime are added to deoxidize the slag and adjust the slag composition inside the converter; then the oxygen lance height is adjusted to 600mm, and nitrogen is blown to remove ferrous oxide, and the nitrogen blowing time is controlled to 20s;

[0101] S2, nitrogen spraying, slag splashing and furnace protection at four different gun positions, the specific steps include:

[0102] S21, one-time slag splashing furnace protection

[0103] Adjust the oxygen gun height to 1500mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle with a blowing pressure of 1.2-1.5Mpa and a blowing time of 100s;

[0104] Maintain the oxygen lance height at 1500mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the blowing pressure of the inner nozzle is 1.2Mpa, the blowing pressure of the outer nozzle is 0.2Mpa, and the blowing time is 100s;

[0105] S22, secondary slag splashing furnace protection

[0106] Adjust the oxygen lance height to 1200mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0107] Maintain the oxygen lance height at 1200mm, rotate the furnace body to tilt -10 to 10°, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the inner nozzle blowing pressure is 1.1Mpa, the outer nozzle blowing pressure is 0.3Mpa, and the nitrogen blowing time is 100s to ensure that there is slag adhesion on both the feeding surface and the steel tapping surface of the furnace lining;

[0108] S23, three-time slag splashing furnace protection

[0109] Adjust the oxygen lance height to 900mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0110] Maintain the oxygen lance height at 900mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the blowing pressure of the inner nozzle is 1.0Mpa, the blowing pressure of the outer nozzle is 0.4Mpa, and the blowing time is 100s;

[0111] S24, four times of slag splashing to protect the furnace

[0112] Adjust the oxygen lance height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0113] Maintain the oxygen lance height at 600mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the inner nozzle blowing pressure is 0.9Mpa, the outer nozzle blowing pressure is 0.5Mpa, and the nitrogen blowing time is 100s;

[0114] S3. Check the slag splashing of the furnace lining and find that the thickness of the slag splashing layer is uniform and meets the requirements; pour out the slag and the slag splashing furnace protection is completed.

[0115] Example 3

[0116] The slag splashing furnace protection method comprises the following steps:

[0117] S1. After steel is tapped, all the slag inside the converter is retained, the amount of molten steel is about 95 tons, and the amount of slag is about 11-12 tons; 100kg of coke powder and 100kg of quicklime are added to deoxidize the slag and adjust the slag composition inside the converter; then the oxygen lance height is adjusted to 600mm, and nitrogen is blown to remove ferrous oxide, and the nitrogen blowing time is controlled to 20s;

[0118] S2, nitrogen spraying, slag splashing and furnace protection at at least four different gun positions, the specific steps include:

[0119] S21, one-time slag splashing furnace protection

[0120] Adjust the oxygen gun height to 1500mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle with a blowing pressure of 1.2-1.5Mpa and a blowing time of 100s;

[0121] Maintain the oxygen lance height at 1500mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the inner nozzle blowing pressure is 1.2Mpa, the outer nozzle blowing pressure is 0.1Mpa, and the nitrogen blowing time is 100s;

[0122] S22, secondary slag splashing furnace protection

[0123] Adjust the oxygen lance height to 1200mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0124] Maintain the oxygen lance height at 1200mm, rotate the furnace body to tilt -10 to 10°, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the inner nozzle blowing pressure is 1.1Mpa, the outer nozzle blowing pressure is 0.2Mpa, and the nitrogen blowing time is 100s to ensure that there is slag adhesion on both the feeding surface and the steel tapping surface of the furnace lining;

[0125] S23, three-time slag splashing furnace protection

[0126] Adjust the oxygen lance height to 900mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0127] Maintain the oxygen lance height at 900mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the inner nozzle blowing pressure is 1.0Mpa, the outer nozzle blowing pressure is 0.3Mpa, and the nitrogen blowing time is 100s;

[0128] S24, four times of slag splashing to protect the furnace

[0129] Adjust the oxygen lance height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0130] Maintain the oxygen gun height at 600mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen through the inner nozzle and the outer nozzle at the same time, the blowing pressure of the inner nozzle is 0.9Mpa, the blowing pressure of the outer nozzle is 0.4Mpa, and the blowing time is 100s;

[0131] S4. Check the slag splashing of the furnace lining and find that the thickness of the slag splashing layer is uniform and meets the requirements; pour out the slag and the slag splashing furnace protection is completed.

[0132] Comparative Example 1

[0133] This comparative example is a comparative example of Example 1, and its furnace protection operation steps and control parameters are basically the same as those of Example 1. The only difference from Example 1 is that in the process of nitrogen spraying and slag splashing furnace protection, each gun position only uses the main airflow to spray nitrogen, and the main airflow + auxiliary airflow nitrogen spraying step is removed.

[0134] That is, step S2 includes the following:

[0135] S21, one-time slag splashing furnace protection

[0136] Adjust the oxygen gun height to 1500mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle with a blowing pressure of 1.2-1.5Mpa and a blowing time of 100s;

[0137] S22, secondary slag splashing furnace protection

[0138] Adjust the oxygen lance height to 1200mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0139] S23, three-time slag splashing furnace protection

[0140] Adjust the oxygen lance height to 900mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s;

[0141] S24, four times of slag splashing to protect the furnace

[0142] Adjust the oxygen gun height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, and blow nitrogen through the inner nozzle for 100s.

[0143] Comparative Example 2

[0144] This comparative example is a comparative example of Example 1, and its furnace protection operation steps and control parameters are basically the same as those of Example 1. The only difference from Example 1 is that in step S22, when the primary airflow + the secondary airflow are used to simultaneously spray and splash slag, the converter body is always kept vertical and the furnace body is not tilted.

[0145] Comparative Example 3

[0146] This comparative example is a comparative example of Example 1, and its furnace protection operation steps and control parameters are basically the same as those of Example 1. The only difference from Example 1 is that in the process of nitrogen spraying and slag splashing furnace protection, in the step of simultaneous nitrogen spraying of the main gas flow + the secondary gas flow, the main gas flow blowing pressure is 0.9MPa (equal to 60%), and the secondary gas flow blowing pressure is 0.6MPa (equal to 40%).

[0147] After the slag splashing furnace protection was completed in Examples 1 to 3 and Comparative Examples 1 to 3, the slag splashing furnace protection effects were tested respectively, and the measured data are shown in the following table.

[0148]

[0149]

[0150] It can be seen from the data in the above table that in Examples 1 to 3 of the slag splashing furnace protection method of the present invention, the slag splashing effect is significantly improved with the increase of the blowing pressure during the slag splashing process, especially when the external nozzle secondary airflow is added, the average thickness of the slag splashing layer is improved to varying degrees. This is because when the secondary airflow is sprayed, the airflow along the β angle direction increases the flight height of the slag and enables the splashed slag to adhere more firmly to the furnace wall, thereby increasing the thickness of the slag splashing layer and helping to protect the furnace lining.

[0151] Comparative Example 1 only uses the main airflow spraying, which is the existing conventional slag splashing furnace protection method. According to the measurement, the slag layer thickness is generally thin, with an average slag layer thickness of 10mm, which is only half of the average slag layer thickness of the embodiment method, and the slag layer thickness of the furnace wall is uneven, with a maximum slag layer thickness of 27mm and a minimum of 3mm. The furnace protection effect is poor, and the converter life is short, which is about 3,000 furnaces lower than that of Example 1.

[0152] Comparative Example 2 uses the main airflow and the secondary airflow to spray simultaneously, but the converter body is not tilted. The tilt of the furnace body helps the slag to splash more on the steel outlet and the large surface of the furnace mouth, increasing the thickness of the slag splashing layer at the large surface of the furnace mouth, thereby better protecting the furnace lining and improving the furnace life. After the tilt of Comparative Example 2 was cancelled, the average thickness of the slag splashing layer on the large surface of the steel outlet was significantly reduced, and it affected the average thickness of the slag splashing layer of the entire furnace body. The maximum thickness of the slag layer was 26mm and the minimum thickness was 10mm, and the furnace body life was short.

[0153] In Comparative Example 3, the method of simultaneously spraying the main airflow and the secondary airflow is added, and the thickness of the slag splashing layer on the large surface of the steel outlet and the average thickness of the slag splashing layer of the furnace body are significantly higher than those of Comparative Example 1 and Comparative Example 2. However, due to the relatively small spraying pressure of the main airflow, the slag splashing height is slightly lower, and the adhesion of the slag layer and the furnace lining is deteriorated, resulting in the thickness of the slag splashing layer at the steel outlet and the furnace body being significantly lower than the thickness of the slag splashing layer in Example 1, which in turn reduces the life of the converter by about 2,000 furnaces.

[0154] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A converter slag splashing protection method, characterized in that: The oxygen lance used is a multi-stream oxygen lance, and the oxygen lance nozzle comprises a main airflow channel (1), a secondary airflow channel (2) and a peripheral cooling channel (3) which are sequentially arranged from the inside to the outside, and the main airflow channel (1), the secondary airflow channel (2) and the peripheral cooling channel (3) are all coaxially arranged; the top of the main airflow channel (1) is connected to a first air supply pipe (4), and a plurality of inner spray holes (1-1) for spraying toward the bottom are uniformly arranged in the circumferential direction at the bottom of the main airflow channel (1); the air inlet of the secondary airflow channel (2) is connected to a second air supply pipe (5), and a plurality of outer spray holes (2-1) for spraying toward the side wall are arranged in the circumferential direction in the middle of the secondary airflow channel (2); The converter slag splashing furnace protection method comprises the following steps: S1. After steel is tapped, a slag adjusting agent is added into the converter to adjust the slag composition inside the converter; S2, multiple nitrogen spraying to splash slag to protect the furnace, when spraying nitrogen, the main airflow splashing slag, the main airflow + auxiliary airflow splashing slag alternately; S3. Check the slag splashing condition of the furnace lining. Pour out the slag when the requirement is met. The slag splashing furnace protection is completed.

2. The converter slag splashing protection method according to claim 1, characterized in that: The bottom of the oxygen gun is provided with a plurality of inner nozzles (1-3) corresponding to the inner nozzle holes (1-1) one by one, the inner nozzle holes (1-1) and the inner nozzles (1-3) are connected via an inner cone tube (1-2), and the inner cone tube (1-2) penetrates the secondary air flow channel (2); the outer nozzle holes (2-1) penetrate the peripheral cooling channel (3) via an outer nozzle pipe (2-2), and the outer end of the outer nozzle pipe (2-2) is connected to the outer nozzle (2-3).

3. The converter slag splashing protection method according to claim 2, characterized in that: The inner diameter of the inner conical tube (1-2) gradually increases from the inlet end to the outlet end, and the angle α between the central axis of the inner conical tube (1-2) and the central axis of the main air flow channel (1) is 10° to 15°.

4. The converter slag splashing protection method according to claim 1, characterized in that: The height h of the outer spray hole (2-1) from the bottom of the secondary airflow channel (2) is 30-50 mm; the outer spray pipe (2-2) is a straight pipe inclined upward, and the angle β between the central axis of the outer spray pipe (2-2) and the horizontal direction is 15°-25°.

5. The converter slag splashing protection method according to claim 2, characterized in that: The Mach number of the main airflow is 1.85-2.5, and the Mach number of the secondary airflow is 2.5-3.

6. The converter slag splashing protection method according to claim 1, characterized in that: In step S1, the slag conditioning agents are coke powder and quicklime; the amount of coke powder added is 1.0-1.1 kg per ton of steel, and the amount of quicklime added is 1.0-2.3 kg per ton of steel.

7. The converter slag splashing protection method according to claim 6, characterized in that: In the step S1, after adding the slag conditioning agent, the converter is subjected to nitrogen blowing treatment to fully remove ferrous oxide; the oxygen lance height during nitrogen blowing is 600 mm, only the main gas flow is used for nitrogen blowing, and the nitrogen blowing time is 20 seconds.

8. The converter slag splashing protection method according to claim 1, characterized in that: The step S2 includes slag splashing operations at four different gun positions, and the specific method is as follows: S21, one-time slag splashing furnace protection Adjust the oxygen lance height to 1500mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s; Maintain the oxygen lance height at 1500mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s; S22, secondary slag splashing furnace protection Adjust the oxygen lance height to 1200mm, open the first nitrogen branch, keep the second nitrogen branch closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s; Maintain the oxygen lance height at 1200mm, rotate the furnace body to tilt -10~10°, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the auxiliary gas flow at the same time, and the blowing time is 100s; S23, three-time slag splashing furnace protection Adjust the oxygen lance height to 900mm, open the first nitrogen branch, keep the second nitrogen branch closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s; Maintain the oxygen lance height at 900mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s; S24, four times of slag splashing to protect the furnace Adjust the oxygen gun height to 600mm, open the first nitrogen branch pipe, keep the second nitrogen branch pipe closed, blow nitrogen with the main gas flow, and blow nitrogen for 100s; Maintain the oxygen gun height at 600mm, open the first nitrogen branch pipe and the second nitrogen branch pipe at the same time, blow nitrogen with the main gas flow + the secondary gas flow at the same time, and the blowing time is 100s.

9. The converter slag splashing protection method according to claim 8, characterized in that: In step S2, when only the main airflow is used to spray nitrogen, the spraying pressure is 1.2~1.5Mpa; when the main airflow + the secondary airflow are used to spray nitrogen at the same time, the total pressure of the main airflow and the secondary airflow is 1.2~1.5Mpa, wherein the main airflow flow accounts for more than 60% of the total nitrogen supply, and the secondary airflow flow accounts for less than 40% of the total nitrogen supply.

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