Method for solving the problem of mushroom head blocking the bottom gun ring gap of bottom oxygen blowing and powder injection combined blowing converter

Abstract

The present application relates to a kind of methods for solving bottom oxygen blowing, mushroom head of powder injection combined blowing converter is blocked bottom gun ring gap, belong to metallurgical industry steelmaking technical field.The technical scheme is: through ring gap gas supply parameter, calculate mushroom head gas permeability index, according to gas permeability index, select the blow refining end point temperature and furnace bottom gas supply parameter required for dredging ring gap, and according to the blow refining end point temperature, additional lime amount is added into furnace, to ensure the blow refining end point temperature, improve the phosphorus component of the liquid steel, meet the smelting requirement, finally, based on gas permeability index and dredging processing length, set the condition for terminating dredging ring gap processing, to solve the ring gap blockage caused by mushroom head too big.The beneficial effects of the present application are: it can effectively avoid the ring gap blockage caused by mushroom head too big, ensure the blow refining end point temperature to improve the phosphorus component of the liquid steel to meet the smelting requirement, reduce the risk of mushroom head too big to block bottom gun and cause accident.

Description

Technical Field

[0001] This invention relates to a method for solving the problem of clogging of the bottom lance circumferential seam in bottom-blown oxygen and powder-injected combined blowing converters, belonging to the field of steelmaking technology in the metallurgical industry. Background Technology

[0002] Compared to traditional combined-blown converters, the KOBM converter exhibits a series of smelting advantages, including lower ash consumption, higher metal yield, reduced splashing, lower carbon-oxygen accumulation, and more complete molten pool reaction, which have been highly recognized by metallurgical professionals. Currently, research on KOBM converter technology is gaining momentum in China. Meanwhile, some domestic steel companies have already put KOBM converters into industrial application.

[0003] The strong oxidizing atmosphere at the bottom of the KOBM converter, coupled with intense molten pool stirring, results in a short bottom life. This short bottom life has long been a stumbling block to the widespread adoption of KOBM converters. Research has identified several contributing factors to the short bottom life: the high-temperature oxidizing atmosphere around the bottom lance nozzle, chemical corrosion of the refractory material by SiO2 or FeO, physical erosion caused by intense stirring, and high-intensity thermal shock and stress around the bottom lance. However, thanks to the cooling effect of natural gas blown into the bottom lance's circumferential seam, a solid metallic mushroom-shaped nozzle with good permeability is formed at the bottom lance outlet during the smelting process. Figure 1 As shown, the mushroom head covers the bottom lance outlet, blocking contact between oxygen, molten steel, and the lance. The presence of the mushroom head effectively protects the bottom lance and contributes to extending the furnace bottom's lifespan. During smelting, the size of the mushroom head is dynamically changing, primarily influenced by the cooling gas flow rate. If the mushroom head shrinks or disappears, the bottom lance, lacking its protection, is highly susceptible to corrosion. An excessively large mushroom head leads to poor permeability, clogging the bottom lance, and even causing damage to bottom blowing elements and burnout of the furnace bottom distributor. This not only renders the bottom blowing CaO-O2 function ineffective but also affects smelting efficiency and production stability.

[0004] However, even with various technical measures to control the size of the mushroom head through bottom gas supply, it is still impossible to completely eliminate the occurrence of bottom lance circumferential seam blockage due to an excessively large mushroom head during production. Mechanical unblocking of blockages has disadvantages such as cumbersome operation, production interruption, and low efficiency. In view of this, the present invention aims to propose a method to solve the problem of bottom lance circumferential seam blockage caused by an excessively large mushroom head in bottom-blown oxygen and powder-injected combined blowing converter steelmaking, so as to reduce the risk of accidents caused by bottom lance blockage due to an excessively large mushroom head. Summary of the Invention

[0005] The purpose of this invention is to provide a method for solving the problem of mushroom head blockage in bottom-blown oxygen and powder-injected combined blowing converters, which can effectively avoid blockage caused by excessively large mushroom heads, ensure that the phosphorus content of the molten steel meets the smelting requirements after the blowing end temperature is increased, and solve the problems existing in the background technology.

[0006] The technical solution of this invention is:

[0007] The permeability index of the mushroom head is calculated using the gas supply parameters of the annular gap. Based on the permeability index, the required blowing endpoint temperature and furnace bottom gas supply parameters for unblocking the annular gap are selected. The amount of furnace lime added is then adjusted according to the blowing endpoint temperature to ensure the desired temperature is reached, thereby increasing the phosphorus content of the molten steel and meeting smelting requirements. Finally, based on the permeability index and unblocking time, conditions for terminating the unblocking process are set to address annular gap blockage caused by an excessively large mushroom head. The specific steps include:

[0008] Step 1: Read the gas flow rate and pressure of the bottom gun circumferential seam during the blowing process, and calculate the air permeability index α of the mushroom head using equation (1);

[0009] α= k M·F / (22.4*P) (1)

[0010] in, k This is a correction factor; it is 2 when natural gas is injected into the annular gap, and 1 when nitrogen or argon is injected. F is the gas flow rate of the annular gap, in Nm³. 3 / min, P is the gas pressure in the annular gap, in MPa, and M is the molar mass of the gas, in g / mol;

[0011] Step 2: Determine the distribution of the air permeability index of each bottom gun mushroom head in the furnace bottom;

[0012] If the air permeability index α of a bottom gun mushroom head is less than 2.5, then stop blowing and use mechanical means to clear the circumferential seam;

[0013] If the air permeability index of the mushroom head meets the following conditions: ① the air permeability index of at least one bottom gun mushroom head is 2.5≤α≤3.0, and the air permeability index of other bottom gun mushroom heads is α≥2.5; or ② the air permeability index of at least one bottom gun mushroom head is 3.0<α≤4.0, and the air permeability index of other bottom gun mushroom heads is 3.0<α≤8.0, then the method of melting the mushroom head is adopted to clear the circumferential seam.

[0014] If the air permeability index of at least one bottom gun mushroom head is 3.0 < α ≤ 4.0, and the air permeability index α of the other bottom gun mushroom heads is > 8.0, then there is no need to clean the circumferential seam.

[0015] If the air permeability index of all bottom gun mushroom heads is α>4.0, then there is no need to clear the circumferential seam.

[0016] Step 3: If the air permeability index of at least one bottom gun mushroom head is 3.0 < α ≤ 4.0, and the air permeability index of other bottom gun mushroom heads is 3.0 < α ≤ 8.0, the final temperature should be controlled at 1640℃ ≤ T ≤ 1670℃;

[0017] If the air permeability index of at least one bottom gun mushroom head is 2.5≤α≤3.0, and the air permeability index of other bottom gun mushroom heads is α≥2.5, the final temperature should be controlled at 1670℃<T≤1700℃;

[0018] Step 4: Add more lime to the furnace according to the set blowing endpoint temperature;

[0019] If the final temperature is set at 1640℃≤T≤1670℃, the amount of lime should be increased by 3.8-7.7 kg per ton of steel.

[0020] If the final temperature is set at 1670℃ < T ≤ 1700℃, the amount of lime should be increased by 5.8-9.6 kg per ton of steel.

[0021] Step 5: After the oxygen supply is stopped at the end of the blowing process, the actual temperature of the molten steel is measured using a secondary lance. The composition of the molten steel at the end of the smelting process is predicted by the computer control system, and the superheat of the molten steel is calculated using equations (2) and (3).

[0022] ΔT=TT L (2)

[0023] T L =1536.6-(88× w [C]+8× w [Si]+5× w [Mn]+30× w [P]) (3)

[0024] Where T is the endpoint molten steel temperature measured by the secondary lance, T L This refers to the solidification temperature of molten steel. w [C]、 w [Si]、 w [Mn]、 w [P] represents the mass percentage of carbon, silicon, manganese, and phosphorus in the molten steel;

[0025] If the superheat is below 100℃, the circumferential joint will not be cleared; if the superheat is above 100℃, the circumferential joint will be cleared.

[0026] Step 6: After the oxygen supply to the blowing process is stopped, argon gas is injected into the bottom lance, and the flow rate parameters of the argon gas injected into the bottom lance are selected according to the superheat of the molten steel.

[0027] If the superheat of the molten steel is 100℃≤T≤140℃, the argon flow rate in the central tube should be controlled at 20Nm. 3 / min -25Nm 3 / min, the flow rate ratio of the circumferential seam to the central pipe is controlled at 7%-9%;

[0028] If the superheat of the molten steel is 140℃ < T ≤ 170℃, the argon flow rate in the central tube should be controlled at 25 Nm. 3 / min -30Nm 3 / min, the flow rate ratio of the circumferential seam to the central pipe is controlled at 9%-11%;

[0029] Step 7: Calculate and monitor the air permeability index of each bottom gun mushroom head during bottom blowing argon in real time, and stop the circumferential joint blockage treatment operation based on air permeability and treatment time;

[0030] ① If the air permeability index of the bottom gun mushroom head is α≥4.0; or ② if the time for clearing the blockage of the circumferential seam is more than 5 minutes, then stop clearing the circumferential seam and proceed with the steel tapping operation.

[0031] The above-mentioned method for solving the problem of bottom lance circumferential gap blockage in bottom-blown oxygen and powder-injected combined blowing converters, wherein the bottom lance circumferential gap width is 1.5-3mm.

[0032] The above-mentioned method for solving the problem of bottom gun circumferential seam blockage of mushroom head in bottom-blown oxygen and powder injection combined blowing converters refers to 3-6 bottom guns.

[0033] The above method for solving the problem of clogging of the bottom lance annular seam in bottom-blown oxygen and powder injection combined blowing converters, in step one, during the blowing process, oxygen is injected into the central tube of the bottom lance, and the flow rate is controlled at 30 Nm. 3 / min -45Nm 3 / min; circumferential injection of natural gas, with the natural gas / oxygen flow ratio controlled at 8%-10%, and the flow rate between 2.4 Nm³. 3 / min -4.5Nm 3 / min.

[0034] In the above method for solving the problem of blockage of the bottom gun circumferential seam in bottom-blown oxygen and powder-injected combined blowing converters, in step five, if the superheat is greater than 100°C, the circumferential seam is cleared, and the clearing time is controlled within 5.0 minutes.

[0035] The beneficial effects of this invention are:

[0036] 1) After the mushroom head blocks the ring seam, the ring seam can be cleared online. The operation is convenient and overcomes the disadvantages of mechanical clearing, such as furnace shutdown, disassembly and production interruption.

[0037] 2) This invention reduces the shedding caused by an excessively large mushroom head, maintains the stable existence of the mushroom head, and provides effective protection for the bottom gun;

[0038] 3) This invention reduces the frequency of bottom gun blockage caused by excessively large mushroom heads, stabilizes the operation of bottom gas supply and powder injection functions, and further reduces the risk of secondary accidents caused by bottom gun blockage. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the present invention;

[0040] In the diagram: 1. Central tube; 2. Outer sleeve; 3. Circumferential seam; 4. Refractory material; 5. Mushroom head. Detailed Implementation

[0041] The invention will be further described below with reference to the accompanying drawings and examples.

[0042] See attached document Figure 1 The permeability index of the mushroom head is calculated using the gas supply parameters of the annular gap. Based on the permeability index, the required blowing endpoint temperature and furnace bottom gas supply parameters for unblocking the annular gap are selected. Additional furnace lime is added according to the blowing endpoint temperature to ensure the blowing endpoint temperature is reached, thereby increasing the phosphorus content of the molten steel and meeting smelting requirements. Finally, based on the permeability index and unblocking treatment time, conditions for terminating the unblocking treatment of the annular gap are set to solve the annular gap blockage caused by an excessively large mushroom head. The specific steps include:

[0043] Step 1: Read the gas flow rate and pressure of the bottom gun circumferential seam during the blowing process, and calculate the air permeability index α of the mushroom head using equation (1);

[0044] α= k M·F / (22.4*P) (1)

[0045] in, k This is a correction factor; it is 2 when natural gas is injected into the annular gap, and 1 when nitrogen or argon is injected. F is the gas flow rate of the annular gap, in Nm³. 3 / min, P is the gas pressure in the annular gap, in MPa, and M is the molar mass of the gas, in g / mol;

[0046] Step 2: Determine the distribution of the air permeability index of each bottom gun mushroom head in the furnace bottom;

[0047] If the air permeability index α of a bottom gun mushroom head is less than 2.5, then stop blowing and use mechanical means to clear the circumferential seam;

[0048] If the air permeability index of the mushroom head meets the following conditions: ① the air permeability index of at least one bottom gun mushroom head is 2.5≤α≤3.0, and the air permeability index of other bottom gun mushroom heads is α≥2.5; or ② the air permeability index of at least one bottom gun mushroom head is 3.0<α≤4.0, and the air permeability index of other bottom gun mushroom heads is 3.0<α≤8.0, then the method of melting the mushroom head is adopted to clear the circumferential seam.

[0049] If the air permeability index of at least one bottom gun mushroom head is 3.0 < α ≤ 4.0, and the air permeability index α of the other bottom gun mushroom heads is > 8.0, then there is no need to clean the circumferential seam.

[0050] If the air permeability index of all bottom gun mushroom heads is α>4.0, then there is no need to clear the circumferential seam.

[0051] Step 3: If the air permeability index of at least one bottom gun mushroom head is 3.0 < α ≤ 4.0, and the air permeability index of other bottom gun mushroom heads is 3.0 < α ≤ 8.0, the final temperature should be controlled at 1640℃ ≤ T ≤ 1670℃;

[0052] If the air permeability index of at least one bottom gun mushroom head is 2.5≤α≤3.0, and the air permeability index of other bottom gun mushroom heads is α≥2.5, the final temperature should be controlled at 1670℃<T≤1700℃;

[0053] Step 4: Add more lime to the furnace according to the set blowing endpoint temperature;

[0054] If the final temperature is set at 1640℃≤T≤1670℃, the amount of lime should be increased by 3.8-7.7 kg per ton of steel.

[0055] If the final temperature is set at 1670℃ < T ≤ 1700℃, the amount of lime should be increased by 5.8-9.6 kg per ton of steel.

[0056] Step 5: After the oxygen supply is stopped at the end of the blowing process, the actual temperature of the molten steel is measured using a secondary lance. The composition of the molten steel at the end of the smelting process is predicted by the computer control system, and the superheat of the molten steel is calculated using equations (2) and (3).

[0057] ΔT=TT L (2)

[0058] T L =1536.6-(88× w [C]+8× w [Si]+5× w [Mn]+30× w [P]) (3)

[0059] Where T is the endpoint molten steel temperature measured by the secondary lance, T L This refers to the solidification temperature of molten steel. w [C]、 w [Si]、 w [Mn]、 w [P] represents the mass percentage of carbon, silicon, manganese, and phosphorus in the molten steel;

[0060] If the superheat is below 100℃, the circumferential joint will not be cleared; if the superheat is above 100℃, the circumferential joint will be cleared.

[0061] Step 6: After the oxygen supply to the blowing process is stopped, argon gas is injected into the bottom lance, and the flow rate parameters of the argon gas injected into the bottom lance are selected according to the superheat of the molten steel.

[0062] If the superheat of the molten steel is 100℃≤T≤140℃, the argon flow rate in the central tube should be controlled at 20 Nm. 3 / min -25Nm 3 / min, the flow rate ratio of the circumferential seam to the central pipe is controlled at 7%-9%;

[0063] If the superheat of the molten steel is 140℃ < T ≤ 170℃, the argon flow rate in the central tube should be controlled at 25 Nm. 3 / min -30Nm 3 / min, the flow rate ratio of the circumferential seam to the central pipe is controlled at 9%-11%;

[0064] Step 7: Calculate and monitor the air permeability index of each bottom gun mushroom head during bottom blowing argon in real time, and stop the circumferential joint blockage treatment operation based on air permeability and treatment time;

[0065] ① If the air permeability index of the bottom gun mushroom head is α≥4.0; or ② if the time for clearing the blockage of the circumferential seam is more than 5 minutes, then stop clearing the circumferential seam and proceed with the steel tapping operation.

[0066] The width of the bottom gun circumferential seam is 1.5-3mm.

[0067] The number of base guns is 3-6.

[0068] In step one, during the blowing process, oxygen is injected through the central tube of the bottom lance, with the flow rate controlled at 30 Nm. 3 / min -45Nm 3 / min; circumferential injection of natural gas, with the natural gas / oxygen flow ratio controlled at 8%-10%, and the flow rate between 2.4 Nm³. 3 / min -4.5Nm 3 / min.

[0069] In step five, if the overheating exceeds 100°C, the circumferential seam is cleared, and the clearing time is controlled within 5.0 minutes. Example 1:

[0070] See attached document Figure 1 The process was implemented in a 260t bottom-blown oxygen and powder-injected combined blowing converter (KOBM). The furnace bottom is equipped with 6 bottom guns. The inner diameter of the center tube 1 of the bottom gun is 28mm and the thickness of the center tube is 6.25mm. The inner diameter of the outer sleeve 2 is 48mm and the thickness of the outer sleeve is 4mm. The center tube and the outer sleeve form an annular gap 3 with a width of 3.0mm.

[0071] During the blowing process, oxygen is injected through the center tube of the bottom lance at a flow rate of 35 Nm. 3 / min; natural gas is injected through the circumferential gap, and the percentage of natural gas flow rate in the circumferential gap to oxygen flow rate in the central tube is 10%. The permeability index of the mushroom head of the bottom gun circumferential gap is calculated according to the pressure and flow rate parameters of the natural gas in the circumferential gap. The natural gas flow rate of the circumferential gap of the 6 bottom guns is 3.5 Nm3 / min, and the pressures are: P1=1.09, P2=0.96, P3=0.68, P4=1.32, P5=1.46, P6=0.88. The permeability indices calculated by formula (1) are: α1=4.5, α2=5.2, α3=7.4, α4=3.8, α5=3.4, α6=5.7. The permeability indices α4 and α5 of the bottom gun mushroom head of the furnace bottom are between (3.0, 4.0], and the permeability indices of other mushroom heads are 3.0 < α i ≤8.0. Control the final blowing temperature at 1650℃, and add 1.0 ton of lime to the furnace. Stop oxygen supply at the final blowing point. The auxiliary lance measures the actual temperature of the molten steel at the final point as 1646℃, and the system calculates the final composition. w [C]=0.031%, w [Si]=0.008%, w [Mn]=0.12%, w [P] = 0.018%, and the solidification temperature is calculated as T using equation (3). L =1533℃, the superheat of the molten steel is calculated to be 113℃ according to equation (2), and the argon gas flow rate of the bottom lance center tube is set to 20Nm. 3 / min; Argon gas is injected into the circumferential seam, with a gas flow rate ratio of 7% for the circumferential seam to the central tube. The permeability index of each bottom nozzle is monitored in real time. After 3.5 minutes of bottom argon injection, the permeability indices of each bottom nozzle are: α1=4.8, α2=5.4, α3=4.8, α4=5.0, α5=5.1, α6=6.3, meaning the permeability index meets the condition α for stopping the circumferential seam clearing treatment. i >4.0, proceed with the tapping operation.

[0072] Example 2: Implemented in a 260t bottom-blown oxygen and powder-injected combined blowing converter (KOBM). The furnace bottom is equipped with 4 bottom guns. The inner diameter of the center tube 1 of the bottom gun is 28mm and the thickness of the center tube is 6.25mm. The inner diameter of the outer sleeve 2 is 48mm and the thickness of the outer sleeve is 4mm. The center tube and the outer sleeve form an annular gap 3 with a width of 1.65mm.

[0073] During the blowing process, oxygen is injected through the center tube of the bottom lance at a flow rate of 35 Nm. 3 / min; natural gas is injected through the annular gap, and the percentage of natural gas flow in the annular gap to oxygen flow in the central tube is 9%. The permeability indices of the mushroom heads in the annular gap of the four bottom lances are calculated based on the pressure and flow parameters of the natural gas in the annular gap, with results of α1=2.6, α2=3.7, α3=2.5, and α4=4.1. The permeability indices α1 and α3 of the mushroom heads in the bottom lances are between [2.5, 3.0], while α2 is between (3.0, 4.0]. The blowing endpoint temperature is controlled at 1700℃, and 2.5 tons of lime are added to the furnace. Oxygen supply is stopped at the blowing endpoint. The actual temperature of the molten steel at the endpoint is measured by the auxiliary lance at 1693℃, and the superheat of the molten steel is calculated to be 162℃. The argon flow rate in the central tube of the bottom lance is set to 30 Nm³. 3 / min; Argon gas is injected into the circumferential seam, with a gas flow rate ratio of 11% for the circumferential seam to the central tube. The permeability index of each bottom nozzle is monitored in real time. After 4.2 minutes of bottom argon injection, the permeability indices of each bottom nozzle are: α1=4.2, α2=6.1, α3=4.3, α4=5.2, meaning the permeability index meets the condition α for stopping the circumferential seam clearing treatment. i >4.0, proceed with the tapping operation.

[0074] Example 3: Implemented in a 260t bottom-blown oxygen and powder-injected combined blowing converter (KOBM). The furnace bottom is equipped with 6 bottom guns. The inner diameter of the center tube of the bottom gun is 28mm and the thickness of the center tube is 6.25mm. The inner diameter of the outer sleeve is 48mm and the thickness of the outer sleeve is 4mm. The center tube and the outer sleeve form an annular gap with a width of 1.70mm.

[0075] Oxygen is injected through the center tube of the bottom lance during the blowing process at a flow rate of 45 Nm. 3 / min; natural gas is injected through the annular gap, and the percentage of natural gas flow in the annular gap to oxygen flow in the central tube is 10%. The permeability indices of the six bottom-gun annular gap mushroom heads were calculated based on the pressure and flow parameters of the natural gas in the annular gap. The results are: α1=6.3, α2=7.2, α3=6.7, α4=3.7, α5=4.5, α6=3.1. The permeability indices α4 and α6 of the bottom-gun mushroom heads are between (3.0, 4.0), and the permeability indices of the other mushroom heads are 3.0 < α6. i ≤8.0. Control the final blowing temperature at 1660℃, and add 1.5 tons of lime to the furnace. Stop oxygen supply at the final blowing point. The actual temperature of the molten steel at the final point is measured by the auxiliary lance to be 1673℃, and the superheat of the molten steel is calculated to be 141℃. Set the argon flow rate injected into the center tube of the bottom lance to 25 Nm. 3 / min; Argon gas is injected into the circumferential seam, with a gas flow rate ratio of 10% for the circumferential seam to the central tube. The permeability index of each bottom nozzle is monitored in real time. After 1.2 minutes of bottom argon injection, the permeability indices of each bottom nozzle are: α1=7.8, α2=7.8, α3=6.9, α4=7.5, α5=6.4, α6=6.7, meaning the permeability index meets the condition α for stopping the circumferential seam clearing treatment.i >4.0, proceed with the tapping operation.

[0076] Example 4: Implemented in a 260t bottom-blown oxygen and powder-injected combined blowing converter (KOBM). The furnace bottom is equipped with 5 bottom guns. The inner diameter of the center tube of the bottom gun is 28mm and the thickness of the center tube is 6.25mm. The inner diameter of the outer sleeve is 48mm and the thickness of the outer sleeve is 4mm. The center tube and the outer sleeve form an annular gap with a width of 2.0mm.

[0077] During the blowing process, oxygen is injected through the center tube of the bottom lance at a flow rate of 35 Nm. 3 / min; natural gas is injected through the circumferential seam, and the percentage of natural gas flow in the circumferential seam to oxygen flow in the central tube is 9%. The permeability index of the mushroom head of the six bottom lances is calculated based on the pressure and flow parameters of the natural gas in the circumferential seam, with results of α1=3.4, α2=4.2, α3=2.8, α4=4.7, and α5=5.6. The permeability index α3 of the mushroom head of the bottom lance is between [2.5, 3.0]. The blowing endpoint temperature is controlled at 1680℃, and 2.0 tons of lime are added to the furnace. Oxygen supply is stopped at the blowing endpoint. The actual temperature of the molten steel at the endpoint is measured by the auxiliary lance as 1665℃, and the superheat of the molten steel is calculated to be 132℃. The argon flow rate injected through the central tube of the bottom lance is set to 22Nm. 3 / min; Argon gas is injected into the circumferential seam, with a gas flow rate ratio of 8% for the circumferential seam to the central tube. The permeability index of each bottom lance mushroom head is monitored in real time. After argon gas is injected into the bottom lance for 5.0 min, the permeability index of each bottom lance mushroom head is: α1=5.1, α2=6.4, α3=3.6, α4=7.1, α5=7.8. The circumferential seam clearing process is stopped, and the steel tapping operation is carried out.

[0078] Example 5: Implemented in a 260t bottom-blown oxygen and powder-injected combined blowing converter (KOBM). The furnace bottom is equipped with 6 bottom guns. The inner diameter of the center tube of the bottom gun is 28mm and the thickness of the center tube is 6.25mm. The inner diameter of the outer sleeve is 48mm and the thickness of the outer sleeve is 4mm. The center tube and the outer sleeve form an annular gap with a width of 1.5mm.

[0079] During the blowing process, oxygen is injected through the center tube of the bottom lance at a flow rate of 35 Nm. 3 / min; natural gas is injected through the annular gap, and the percentage of natural gas flow in the annular gap to oxygen flow in the central tube is 8%. The permeability index of the six bottom-gun annular gap mushroom heads was calculated based on the pressure and flow parameters of the natural gas in the annular gap. The results are: α1=3.8, α2=4.2, α3=4.6, α4=6.9, α5=5.4, α6=5.1. The permeability index α1 of the bottom-gun mushroom head is between (3.0, 4.0], and the permeability indices of the other mushroom heads are 3.0 < α. i≤8.0. Control the final blowing temperature at 1640℃, and add 1.5 tons of lime to the furnace. Stop oxygen supply at the final blowing point. The actual temperature of the molten steel at the final point is measured by the auxiliary lance to be 1638℃, and the superheat of the molten steel is calculated to be 106℃. Set the argon flow rate injected into the center tube of the bottom lance to 20 Nm³. 3 / min; Argon gas is injected into the circumferential seam, with a gas flow rate ratio of 7% for the circumferential seam to the central tube. The permeability index of each bottom nozzle is monitored in real time. After 2.0 min of bottom argon injection, the permeability indices of each bottom nozzle are: α1=4.9, α2=5.0, α3=6.8, α4=7.5, α5=6.1, α6=6.7, meaning the permeability index meets the condition α for stopping the circumferential seam clearing treatment. i >4.0, proceed with the tapping operation.

Claims

1. A method for solving the problem of clogging of the bottom lance circumferential seam in a bottom-blown oxygen and powder-injected combined blowing converter, characterized in that: Follow these steps: Step 1: Read the gas flow rate and pressure of the bottom gun circumferential seam during the blowing process, and calculate the air permeability index α of the mushroom head using equation (1); a= k M·F / (22.4*P) (1) in, k This is a correction factor; it is 2 when natural gas is injected into the annular gap, and 1 when nitrogen or argon is injected. F is the gas flow rate of the annular gap, in Nm³. 3 / min, P is the gas pressure in the annular gap, in MPa; M is the molar mass of the gas, in g / mol; Step 2: Determine the distribution of the air permeability index of each bottom gun mushroom head in the furnace bottom; If the air permeability index α of a bottom gun mushroom head is less than 2.5, then stop blowing and use mechanical means to clear the circumferential seam; If the air permeability index of the mushroom head meets the following conditions: ① the air permeability index of at least one bottom gun mushroom head is 2.5≤α≤3.0, and the air permeability index of other bottom gun mushroom heads is α≥2.5; or ② the air permeability index of at least one bottom gun mushroom head is 3.0<α≤4.0, and the air permeability index of other bottom gun mushroom heads is 3.0<α≤8.0, then the method of melting the mushroom head is adopted to clear the circumferential seam. If the air permeability index of at least one bottom gun mushroom head is 3.0 < α ≤ 4.0, and the air permeability index α of the other bottom gun mushroom heads is > 8.0, then there is no need to clean the circumferential seam. If the air permeability index of all bottom gun mushroom heads is α>4.0, then there is no need to clear the circumferential seam. Step 3: If the air permeability index of at least one bottom gun mushroom head is 3.0 < α ≤ 4.0, and the air permeability index of other bottom gun mushroom heads is 3.0 < α ≤ 8.0, the final temperature should be controlled at 1640℃ ≤ T ≤ 1670℃; If the air permeability index of at least one bottom gun mushroom head is 2.5≤α≤3.0, and the air permeability index of other bottom gun mushroom heads is α≥2.5, the final temperature should be controlled at 1670℃<T≤1700℃; Step 4: Add more lime to the furnace according to the set blowing endpoint temperature; If the final temperature is set at 1640℃≤T≤1670℃, the amount of lime to be added is 3.8-7.7 kg per ton of steel; If the final temperature is set between 1670℃ and T, the amount of lime to be added is 5.8-9.6 kg per ton of steel. Step 5: After the oxygen supply is stopped at the end of the blowing process, the temperature of the molten steel at the end of the process is measured by the auxiliary lance. The composition of the molten steel at the end of the process is predicted by the computer control system, and the superheat of the molten steel is calculated by formulas (2) and (3). ΔT=T-T L (2) T L =1536.6-(88× w [C]+8× w [Si]+5× w [Mn]+30× w [P]) (3) Where T is the endpoint molten steel temperature measured by the secondary gun, in °C; T L This is the solidification temperature of molten steel, expressed in °C. w [C]、 w [Si]、 w [Mn]、 w [P] represents the mass percentage of carbon, silicon, manganese, and phosphorus in the molten steel; If the superheat is below 100℃, the circumferential joint will not be cleared; if the superheat is above 100℃, the circumferential joint will be cleared. Step 6: After the oxygen supply to the blowing process is stopped, argon gas is injected into the bottom lance, and the flow rate parameters of the argon gas injected into the bottom lance are selected according to the superheat of the molten steel. If the superheat of the molten steel is 100℃≤ΔT≤140℃, the argon flow rate in the central tube should be controlled at 20Nm. 3 / min -25Nm 3 / min, the flow rate ratio of the circumferential seam to the central pipe is controlled at 7%-9%; If the superheat of the molten steel is 140℃ < ΔT ≤ 170℃, the argon flow rate in the central tube should be controlled at 25 Nm. 3 / min -30Nm 3 / min, the flow rate ratio of the circumferential seam to the central pipe is controlled at 9%-11%; Step 7: Calculate and monitor the air permeability index of each bottom gun mushroom head during bottom blowing argon in real time, and stop the circumferential joint blockage treatment operation based on air permeability and treatment time; ① If the air permeability index of the bottom gun mushroom head is α≥4.0; or ② if the time for clearing the blockage of the circumferential seam is more than 5 minutes, then stop clearing the circumferential seam and proceed with the steel tapping operation.

2. The method for solving the problem of bottom lance circumferential seam blockage at the mushroom head in a bottom-blown oxygen / powder-injected combined blowing converter according to claim 1, characterized in that: The width of the bottom gun circumferential seam is 1.5-3mm.

3. The method for solving the problem of bottom lance circumferential seam blockage at the mushroom head in a bottom-blown oxygen / powder-injected combined blowing converter according to claim 2, characterized in that: The number of base guns is 3-6.

4. The method for solving the problem of bottom lance circumferential seam blockage at the mushroom head in a bottom-blown oxygen / powder-injected combined blowing converter according to claim 1, characterized in that: In step one, during the blowing process, oxygen is injected through the central tube of the bottom lance, with the flow rate controlled at 30 Nm. 3 / min -45Nm 3 / min; circumferential injection of natural gas, with the natural gas / oxygen flow ratio controlled at 8%-10%, and the flow rate between 2.4 Nm³. 3 / min -4.5Nm 3 / min.

5. The method for solving the problem of bottom lance circumferential seam blockage at the mushroom head in a bottom-blown oxygen / powder-injected combined blowing converter according to claim 1, characterized in that: In step five, if the overheating exceeds 100°C, the circumferential seam is cleared, and the clearing time is controlled within 5.0 minutes.

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