A method for improving the amount of coal gas recovery in the early stage of smelting under a low iron consumption mode

Abstract

A method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode includes the following steps: 1) When the converter is started and ignited, the speed of the primary dust collector fan is 1200 r / min to 1300 r / min; 2) After the converter is started and ignited normally, the movable fume hood is lowered to the lower limit; 3) The converter is blown for 1 minute and 30 seconds to complete the start-up curve, and the blowing oxygen pressure is increased to 0.90 Pa to 0.95 MPa; 4) The position of the blowing lance in the early stage is reduced from 1.85 m to 1.65 m to increase the temperature rise rate of the molten pool in the early stage; 5) The timing and structure of charging are adjusted according to the trend of molten iron temperature and carbon monoxide content in flue gas; 6) The speed of the primary dust collector fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met. This method optimizes the timing of material feeding by adjusting the position of the blowing lance, the material distribution structure, and the speed of the primary dust removal fan in the early stage of the blowing process, and by combining the trend of carbon monoxide content in the flue gas. This enables rapid temperature increase in the early stage of the blowing process, thereby improving the timing of carbon-oxygen reaction and gas recovery time in the early stage of converter smelting.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy and steelmaking technology, and more specifically, to a method for increasing the amount of gas recovered in the early stage of smelting under a low iron consumption mode. Background Technology

[0002] With abundant scrap steel resources, major steel mills across the country have begun to adopt low-iron-consumption operations. However, under low-iron-consumption conditions, the amount of molten iron is low while the amount of scrap steel is high, resulting in low molten pool temperatures in the early stages of smelting. On the other hand, when the molten pool temperature reaches above 1450℃, the carbon-oxygen reaction begins to proceed violently. Therefore, when the heat is insufficient in the early stages, the carbon-oxygen reaction is delayed. Although the oxygen content in the flue gas drops below 1%, the carbon monoxide content in the flue gas is below 8%, which does not meet the recovery conditions, resulting in a long gas release time and delaying the gas recovery time.

[0003] In summary, the low iron consumption operation in the existing technology results in insufficient converter heat and low initial temperature, which delays the carbon-oxygen reaction and the initial gas recovery time, causing some carbon monoxide waste and adversely affecting carbon emissions, energy indicators and cost control. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode. It innovatively proposes to increase the gas recovery time under low iron consumption by rapidly increasing the temperature in the early stage of smelting, adjusting the fan speed according to the carbon monoxide content in the flue gas, and adjusting the fan speed in stages, thereby reducing the energy waste caused by gas release.

[0005] This invention provides a method for increasing the amount of coal gas recovered in the early stage of smelting under low iron consumption mode, comprising the following steps:

[0006] 1) When the converter is started and ignited, the primary dust removal fan speed is 1200 r / min to 1300 r / min;

[0007] 2) After the converter is started and ignited normally, lower the movable fume hood to the lower limit position;

[0008] 3) After 1 minute and 30 seconds of converter blowing, the blowing curve is completed, and the blowing oxygen pressure is increased to 0.90 Pa to 0.95 MPa;

[0009] 4) The position of the blowing lance in the early stage was reduced from 1.85m to 1.65m to increase the rate of temperature rise of the molten pool in the early stage;

[0010] 5) Adjust the timing and structure of charging according to the trend of molten iron temperature and carbon monoxide content in flue gas;

[0011] 6) The speed of the primary dust removal fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met.

[0012] Preferably, step 1) specifically comprises:

[0013] When the converter is started to blow and ignite, the speed of the primary dust removal fan is adjusted from 1300r / min~1400r / min to 1200r / min~1250r / min.

[0014] Preferably, after the converter has finished adding iron and scrap steel, the converter is rocked to the "zero position", then rocked back 14° to 16°, and then rocked back to the "zero position" before the lance is lowered and the blowing and ignition are started.

[0015] Preferably, the amount of molten iron charged is 128 to 129 tons, the amount of scrap steel added is 37 to 38 tons, the temperature of molten iron is 1420℃ to 1430℃, and the silicon content of molten iron is 0.3% to 0.4%.

[0016] Preferably, the blowing curve in step 3) is specifically as follows:

[0017] From 0s to 30s, the oxygen lance flow rate is 17500 to 18500 m³ / h. 3 / h;

[0018] 30s–50s, oxygen lance flow rate 19500–20500 m³ / h 3 / h;

[0019] 50s–60s, oxygen lance flow rate 21500–22000 m³ / h 3 / h;

[0020] 60s–70s, oxygen lance flow rate 23500–24500 m³ / h 3 / h;

[0021] 70s–90s, oxygen lance flow rate 29000–30000 m³ / s 3 / h.

[0022] Preferably, after the gun position is lowered to 1.65m in step 4), the blowing gun position is gradually lowered after 2 minutes of blowing, and finally the gun position is lowered to the normal gun position of 1.45m.

[0023] Preferably, in step 5), when the carbon monoxide content in the flue gas is greater than 5%, the first batch of slag-forming material is added.

[0024] Preferably, the first batch of slag-forming materials includes one or more of ore, lime, dolomite, and dust removal briquettes.

[0025] Preferably, if the temperature of the molten iron is below 1400℃, no ore is added to the first batch of slag-forming material.

[0026] Preferably, step 6) specifically comprises:

[0027] After the ignition and blowing are normal, reduce the fan speed to 1050 r / min to 1070 r / min. For the primary dust removal fan in the early stage of smelting, the speed is increased in stages: when the carbon monoxide content in the flue gas is 0% to 5%, the fan speed is 1150 r / min to 1200 r / min; when the carbon monoxide content in the flue gas is 5% to 8%, the fan speed is 1250 r / min to 1290 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min.

[0028] The blower speed is adjusted according to the slight pressure difference at the furnace mouth during the blowing process.

[0029] This invention provides a method for increasing the amount of gas recovered in the early stage of smelting under a low iron consumption mode, comprising the following steps: 1) When the converter is started and ignited, the speed of the primary dust collector fan is 1200 r / min to 1300 r / min; 2) After the converter is started and ignited normally, the movable fume hood is lowered to the lower limit; 3) The converter is blown for 1 minute and 30 seconds to complete the start-up curve, and the blowing oxygen pressure is increased to 0.90 Pa to 0.95 MPa; 4) The position of the blowing lance in the early stage is reduced from 1.85 m to 1.65 m to increase the temperature rise rate of the molten pool in the early stage; 5) The timing and structure of the charging are adjusted according to the trend of the molten iron temperature and the carbon monoxide content in the flue gas; 6) The speed of the primary dust collector fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met. Compared with the prior art, the method for increasing the amount of gas recovered in the early stage of smelting under the low iron consumption mode provided by the present invention achieves better overall interaction by adjusting the position of the blowing lance, the material distribution structure and the speed of the primary dust removal fan in the early stage, and optimizing the timing of feeding in combination with the trend of carbon monoxide content in the flue gas. This results in rapid temperature increase in the early stage of blowing, and improves the timing of carbon-oxygen reaction and gas recovery time in the early stage of converter smelting. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides a method for increasing the amount of coal gas recovered in the early stage of smelting under low iron consumption mode, comprising the following steps:

[0032] 1) When the converter is started and ignited, the primary dust removal fan speed is 1200 r / min to 1300 r / min;

[0033] 2) After the converter is started and ignited normally, lower the movable fume hood to the lower limit position;

[0034] 3) After 1 minute and 30 seconds of converter blowing, the blowing curve is completed, and the blowing oxygen pressure is increased to 0.90 Pa to 0.95 MPa;

[0035] 4) The position of the blowing lance in the early stage was reduced from 1.85m to 1.65m to increase the rate of temperature rise of the molten pool in the early stage;

[0036] 5) Adjust the timing and structure of charging according to the trend of molten iron temperature and carbon monoxide content in flue gas;

[0037] 6) The speed of the primary dust removal fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met.

[0038] This invention provides a method for increasing the amount of coal gas recovered in the early stage of smelting under low iron consumption mode, comprising the following steps:

[0039] Step 1): When the converter is started blowing and igniting, the primary dust removal fan speed is 1200r / min~1300r / min.

[0040] In this invention, step 1) is preferably specifically:

[0041] When the converter is started to blow and ignite, the speed of the primary dust removal fan is adjusted from 1300r / min~1400r / min to 1200r / min~1250r / min;

[0042] More preferably:

[0043] When the converter is started and ignited, the speed of the primary dust collector fan is adjusted from 1300-1400 r / min to 1250 r / min. This reduces the initial air intake and the oxygen content in the flue.

[0044] In this invention, after the converter is filled with iron and scrap steel, it is preferred to shake the converter to the "zero position", then preferably shake the converter backward by 14° to 16°, more preferably 15°, and then preferably shake the converter back to the "zero position" before lowering the lance and starting the blowing and ignition.

[0045] In this invention, the preferred amount of molten iron is 128 to 129 tons, the preferred amount of scrap steel is 37 to 38 tons, the preferred temperature of molten iron is 1420°C to 1430°C, more preferably 1425°C, and the preferred silicon content of molten iron is 0.3% to 0.4%, more preferably 0.35%.

[0046] In a preferred embodiment of the present invention, step 1) specifically comprises:

[0047] Before adding molten iron to the converter, the primary dust removal fan speed is 1250 r / min. After the converter is finished adding iron and scrap steel, the converter is rocked to the "zero position", then rocked back 15°, and then rocked back to the "zero position" before the lance is lowered and the blowing and ignition are started.

[0048] Step 2): After the converter is started and ignited normally, lower the movable fume hood to the lower limit position; the purpose is to prevent air intake. This invention does not have any special restrictions on the method of lowering the movable fume hood to the lower limit; any operation method familiar to those skilled in the art can be used.

[0049] In a preferred embodiment of the present invention, step 2) specifically comprises:

[0050] After the converter starts blowing and igniting normally, lower the movable fume hood to the lower limit.

[0051] Step 3): The converter blows for 1 minute and 30 seconds to complete the initial blowing curve (90s), and the blowing oxygen pressure is increased to 0.90Pa~0.95MPa. The main purposes are to quickly increase the initial temperature and to strengthen the initial stirring. However, the existing technology does not have any special provisions for this. After the initial blowing and ignition are normal, the oxygen pressure is increased to above 0.90MPa, and the first batch of slag-forming material is added, without considering the carbon monoxide content in the flue gas.

[0052] In this invention, the opening-blowing curve is preferably as follows:

[0053] From 0s to 30s, the oxygen lance flow rate is 17500 to 18500 m³ / h. 3 / h;

[0054] 30s–50s, oxygen lance flow rate 19500–20500 m³ / h 3 / h;

[0055] 50s–60s, oxygen lance flow rate 21500–22000 m³ / h 3 / h;

[0056] 60s–70s, oxygen lance flow rate 23500–24500 m³ / h 3 / h;

[0057] 70s–90s, oxygen lance flow rate 29000–30000 m³ / s 3 / h;

[0058] More preferably:

[0059] From 0s to 30s, the oxygen lance flow rate is 18000 m³ / s. 3 / h;

[0060] 30s–50s, oxygen lance flow rate is 20000 m³ / s 3 / h;

[0061] 50s–60s, oxygen lance flow rate is 21900 m³ / s. 3 / h;

[0062] 60s–70s, oxygen lance flow rate is 24000 m³ / s. 3 / h;

[0063] From 70s to 90s, the oxygen lance flow rate was 29400 m³ / s. 3 / h.

[0064] In a preferred embodiment of the present invention, step 3) specifically comprises:

[0065] After the initial ignition is normal, complete the initial ignition curve (90 seconds) and increase the oxygen pressure to 0.92 MPa; the specific initial ignition curve is described above and will not be repeated here.

[0066] Step 4): The position of the blowing lance in the early stage is reduced from 1.85m to 1.65m to increase the rate of temperature rise of the molten pool in the early stage.

[0067] In this invention, after the gun position is lowered to 1.65m, the blowing process continues for 2 minutes, and then the blowing gun position is gradually lowered until it is finally lowered to the normal gun position of 1.45m.

[0068] In this invention, the main purpose of lowering the converter blowing lance position to 1.65m is to enhance early stirring and rapidly increase the molten pool temperature by utilizing the lower lance position.

[0069] In a preferred embodiment of the present invention, step 4) specifically comprises:

[0070] The converter was initially set to blow lance position of 1.65m. After blowing for 2 minutes, the blowing lance position was gradually lowered, and at 4 minutes and 30 seconds, the lance position was lowered to the normal position of 1.45m.

[0071] Step 5): Adjust the timing and structure of feeding according to the trend of molten iron temperature and carbon monoxide content in flue gas.

[0072] In this invention, when the carbon monoxide content in the flue gas is greater than 5% (volume percentage), it is preferable to add the first batch of slag-forming material.

[0073] In this invention, the first batch of slag-forming material preferably includes one or more of ore, lime, dolomite and dust removal briquettes; if the molten iron temperature is below 1400℃, no ore is added to the first batch of slag-forming material, mainly because it is necessary to increase the initial temperature and accelerate the carbon-oxygen reaction.

[0074] In a preferred embodiment of the present invention, step 5) specifically comprises:

[0075] When the blowing process reaches 1 minute and 38 seconds, the carbon monoxide content in the flue gas reaches 5.6%, and the first batch of slag-forming materials is added: 2400 kg of lime, 1230 kg of raw dolomite, and 750 kg of dust removal briquettes.

[0076] Step 6): The speed of the primary dust removal fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met.

[0077] In this invention, step 6) is preferably specifically:

[0078] After the ignition and blowing are normal, reduce the fan speed to 1050 r / min to 1070 r / min. For the primary dust removal fan in the early stage of smelting, the speed is increased in stages: when the carbon monoxide content in the flue gas is 0% to 5%, the fan speed is 1150 r / min to 1200 r / min; when the carbon monoxide content in the flue gas is 5% to 8%, the fan speed is 1250 r / min to 1290 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min.

[0079] The blower speed is adjusted according to the slight pressure difference at the furnace mouth during the blowing process;

[0080] More preferably:

[0081] After the ignition is normal, reduce the fan speed to 1060 r / min; for the primary dust removal fan in the early stage of smelting, the speed is increased in stages: when the carbon monoxide content in the flue gas is 0% to 5%, the fan speed is 1180 r / min; when the carbon monoxide content in the flue gas is 5% to 8%, the fan speed is 1270 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min.

[0082] The blower speed is adjusted according to the slight pressure difference at the furnace mouth during the blowing process.

[0083] In this invention, the furnace mouth micro-pressure differential is maintained at ±50Pa.

[0084] In a preferred embodiment of the present invention, the adjustment of the fan speed can be found in the table below.

[0085] Table 1. Parameters for Adjusting Fan Speed

[0086] Increase in fan speed, r / min -120 -70 -40 0 0 30 60 100

[0087] Note: When the speed is negative, it is to reduce the fan speed.

[0088] In a preferred embodiment of the present invention, step 6) specifically comprises:

[0089] After the blowing and ignition are normal, reduce the fan speed to 1060 r / min. During the early stage of smelting, the primary dust removal fan will be increased in stages. When the carbon monoxide content in the flue gas is 0% to 5%, the fan speed is 1180 r / min; when the carbon monoxide content in the flue gas is 5% to 8%, the fan speed is 1270 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min. During the blowing process, adjust the fan speed according to the furnace mouth micro-pressure difference (the furnace mouth micro-pressure difference is maintained at ±50 Pa) (the adjustment of the fan speed is subject to the above limitations and will not be repeated here).

[0090] When the converter blows for 2 minutes and 40 seconds, the carbon monoxide content in the flue gas increases to 8.2% and the oxygen content in the flue gas drops to below 0.53%, meeting the conditions for gas recovery.

[0091] The present invention has the following beneficial effects:

[0092] The present invention provides a method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode. This is achieved by adjusting the position of the blowing lance, the material distribution structure, and the speed of the primary dust collector fan, and by optimizing the timing of material feeding in conjunction with the trend of carbon monoxide content in the flue gas. This results in a better overall interaction, leading to rapid temperature increase in the early stage of blowing, improving the timing of carbon-oxygen reaction and the gas recovery time in the early stage of converter smelting. Experimental results show that after implementing this invention, the gas recovery time is advanced by more than 30 seconds compared to before optimization, and the gas emission is reduced by 151 m³. 3 The first measure is to improve the utilization rate of carbon monoxide in flue gas; the second measure is to significantly reduce the amount of flue dust overflow in the early stage of smelting by implementing phased speed increases of the blowers, thereby reducing particulate matter emissions and improving the working environment for employees.

[0093] This invention provides a method for increasing the amount of gas recovered in the early stage of smelting under a low iron consumption mode, comprising the following steps: 1) When the converter is started and ignited, the speed of the primary dust collector fan is 1200 r / min to 1300 r / min; 2) After the converter is started and ignited normally, the movable fume hood is lowered to the lower limit; 3) The converter is blown for 1 minute and 30 seconds to complete the start-up curve, and the blowing oxygen pressure is increased to 0.90 Pa to 0.95 MPa; 4) The position of the blowing lance in the early stage is reduced from 1.85 m to 1.65 m to increase the temperature rise rate of the molten pool in the early stage; 5) The timing and structure of the charging are adjusted according to the trend of the molten iron temperature and the carbon monoxide content in the flue gas; 6) The speed of the primary dust collector fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met. Compared with the prior art, the method for increasing the amount of gas recovered in the early stage of smelting under the low iron consumption mode provided by the present invention achieves better overall interaction by adjusting the position of the blowing lance, the material distribution structure and the speed of the primary dust removal fan in the early stage, and optimizing the timing of feeding in combination with the trend of carbon monoxide content in the flue gas. This results in rapid temperature increase in the early stage of blowing, and improves the timing of carbon-oxygen reaction and gas recovery time in the early stage of converter smelting.

[0094] To further illustrate the present invention, the following embodiments will be described in detail.

[0095] Example 1

[0096] A method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode includes the following steps:

[0097] The amount of molten iron charged was 128.5 tons, and the amount of scrap steel was 37.2 tons; the temperature of the molten iron was 1425℃, and the silicon content of the molten iron was 0.35%.

[0098] 1) The speed of the dust removal fan before adding molten iron to the converter is 1250 r / min; after adding iron and scrap steel to the converter, the converter is rocked to the "zero position", then the converter is rocked back 15°, and then the converter is rocked back to the "zero position", and the lance is lowered and the blowing and ignition are started.

[0099] 2) After the converter is started and ignited normally, lower the movable fume hood to the lower limit position;

[0100] 3) After the initial ignition is normal, complete the initial ignition curve (90 seconds) and increase the oxygen pressure to 0.92 MPa;

[0101] 4) The converter blowing lance position is 1.65m. After blowing for 2 minutes, the blowing lance position is gradually lowered. At 4 minutes and 30 seconds, the lance position is lowered to the normal lance position of 1.45m.

[0102] 5) When the blowing reaches 1 minute and 38 seconds, the carbon monoxide content in the flue gas reaches 5.6%, and the first batch of slag-forming materials is added: 2400 kg of lime, 1230 kg of raw dolomite, and 750 kg of dust removal briquettes.

[0103] 6) After the blowing and ignition are normal, reduce the fan speed to 1060 r / min; for the primary dust removal fan in the early stage of smelting, the speed is increased in stages. When the carbon monoxide content in the flue gas is 0% to 5%, the fan speed is 1180 r / min; when the carbon monoxide content in the flue gas is 5% to 8%, the fan speed is 1270 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min. During the blowing process, adjust the fan speed according to the furnace mouth micro-pressure difference (the furnace mouth micro-pressure difference is maintained at ±50 Pa).

[0104] When the converter blows for 2 minutes and 40 seconds, the carbon monoxide content in the flue gas increases to 8.2% and the oxygen content in the flue gas drops to below 0.53%, meeting the conditions for gas recovery.

[0105] Comparative Example 1

[0106] A method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode includes the following steps:

[0107] The amount of molten iron charged was 128.3 tons, and the amount of scrap steel was 36.9 tons; the temperature of the molten iron was 1448℃, and the silicon content of the molten iron was 0.36%.

[0108] 1) The speed of the dust removal fan before adding molten iron to the converter is 1230 r / min; after adding iron and scrap steel to the converter, the converter is rocked to the "zero position", then the converter is rocked back 13°, and then the converter is rocked back to the "zero position", and the lance is lowered and the blowing and ignition are started;

[0109] 2) After the converter is started and ignited normally, lower the movable fume hood to the lower limit position;

[0110] 3) After the initial ignition is normal, complete the initial ignition curve (90 seconds) and increase the oxygen pressure to 0.93 MPa;

[0111] 4) The converter blowing lance position is 1.80m. When blowing reaches 2 minutes and 30 seconds, the blowing lance position is gradually lowered. When blowing reaches 4 minutes and 30 seconds, the lance position is lowered to the normal lance position of 1.45m.

[0112] 5) When the blowing reaches 2 minutes and 3 seconds, the carbon monoxide content in the flue gas reaches 5.3%, and the first batch of slag-forming materials is added: 2530 kg of lime, 1180 kg of raw dolomite, and 830 kg of dust removal briquettes.

[0113] 6) After the blowing and ignition are normal, reduce the fan speed to 1048 r / min; for the primary dust removal fan in the early stage of smelting, the speed is increased in stages. When the carbon monoxide content in the flue gas is 0% to 5%, the fan speed is 1170 r / min; when the carbon monoxide content in the flue gas is 5% to 8%, the fan speed is 1290 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min. During the blowing process, adjust the fan speed according to the furnace mouth micro-pressure difference (the furnace mouth micro-pressure difference is maintained at ±50 Pa).

[0114] When the converter reaches 3 minutes and 13 seconds of blowing, the carbon monoxide content in the flue gas increases to 8.1% and the oxygen content in the flue gas decreases to below 0.46%, meeting the conditions for gas recovery.

[0115] The comparison shows that Comparative Example 1 verified that the high-position blowing in the early stage affected the heating rate of the molten pool, resulting in a lag in the carbon-oxygen reaction. The experimental results show that the gas recovery time in Comparative Example 1 was about 15 seconds earlier than normal. Although the fan speed was adjusted in the early stage of smelting, the temperature of the molten pool increased slowly in the early stage, resulting in a lag in the carbon-oxygen reaction and an insignificant effect.

[0116] Comparative Example 2

[0117] A method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode includes the following steps:

[0118] The amount of molten iron charged was 128.4 tons, and the amount of scrap steel was 37.2 tons; the temperature of the molten iron was 1443℃, and the silicon content of the molten iron was 0.33%.

[0119] 1) The speed of the dust removal fan before adding molten iron to the converter is 1250 r / min; after adding iron and scrap steel to the converter, the converter is rocked to the "zero position", then the converter is rocked back 15°, and then the converter is rocked back to the "zero position", and the lance is lowered and the blowing and ignition are started.

[0120] 2) After the converter is started and ignited normally, lower the movable fume hood to the lower limit position;

[0121] 3) After the initial ignition is normal, complete the initial ignition curve (90 seconds) and increase the oxygen pressure to 0.95 MPa;

[0122] 4) The converter blowing lance position is 1.65m. When blowing reaches 2 minutes and 20 seconds, the blowing lance position is gradually lowered. When blowing reaches 4 minutes and 15 seconds, the lance position is lowered to the normal lance position of 1.45m.

[0123] 5) When the blowing reaches 1 minute and 42 seconds, the carbon monoxide content in the flue gas reaches 5.5%, and the first batch of slag-forming materials is added: 2320 kg of lime, 1180 kg of raw dolomite, and 780 kg of dust removal briquettes.

[0124] 6) After the initial blowing and ignition are normal, the primary dust removal fan does not adopt a phased speed-up mode. Before the gas recovery begins, the fan speed is 1250 r / min. After the recovery conditions are met, the fan speed is adjusted according to the slight pressure difference at the furnace mouth.

[0125] When the converter blows for 3 minutes and 18 seconds, the carbon monoxide content in the flue gas increases to 13.6% and the oxygen content in the flue gas drops to below 1.0%, which is the specific gas recovery condition.

[0126] The comparison in Example 2 confirms that: without adjusting the fan speed, more draft air (more air) is drawn in, resulting in a high oxygen content in the flue gas. Due to the excessive oxygen content, the conditions for gas recovery are not met. The experimental results show that in Example 1, the carbon monoxide content in the flue gas reached 8.2% in 2 minutes and 40 seconds. Due to the adjustment of the lance position in the early stage of smelting, the heating rate in the early stage of smelting was fast, and the carbon-oxygen reaction was brought forward. On the other hand, because the fan speed was not adjusted, more draft air was drawn in, resulting in a high oxygen content in the flue gas, which did not meet the conditions for gas recovery.

[0127] In summary, comparative experiments show that after implementing this invention, firstly, the gas recovery time is reduced by more than 30 seconds compared to the previous method, and the gas emission is reduced by 151m³. 3 The first measure is to improve the utilization rate of carbon monoxide in flue gas; the second measure is to significantly reduce the amount of flue dust overflow in the early stage of smelting by implementing phased speed increases of the blowers, thereby reducing particulate matter emissions and improving the working environment for employees.

[0128] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for increasing the amount of coal gas recovered in the early stage of smelting under a low iron consumption mode, characterized in that, Includes the following steps: 1) When the converter is started and ignited, the primary dust removal fan speed is 1200r / min~1300r / min; 2) After the converter is started and ignited normally, lower the movable fume hood to the lower limit position; 3) After 1 minute and 30 seconds of converter blowing, the blowing curve is completed, and the blowing oxygen pressure is increased to 0.90 Pa to 0.95 MPa; 4) The position of the blowing lance in the early stage was reduced from 1.85m to 1.65m to increase the rate of temperature rise of the molten pool in the early stage; 5) Adjust the timing and structure of feeding according to the trend of molten iron temperature and carbon monoxide content in flue gas; when the carbon monoxide content in flue gas is greater than 5%, add the first batch of slag-forming materials; 6) The speed of the primary dust collector fan is increased in a stepwise manner to reduce the amount of air intake and the amount of carbon monoxide burned in the flue gas; gas recovery is carried out after the conditions for gas recovery are met. The specific opening curve mentioned in step 3) is as follows: For a time ≥0s and <30s, the oxygen lance flow rate is 17500~18500 m³ / s. 3 / h; For a time interval of 30 seconds or more but less than 50 seconds, the oxygen lance flow rate is 19500~20500 m³ / s. 3 / h; For a time interval of 50 seconds or more but less than 60 seconds, the oxygen lance flow rate is 21,500~22,000 m³ / s. 3 / h; For a time interval greater than or equal to 60 seconds and less than 70 seconds, the oxygen lance flow rate is 23500~24500 m³ / s. 3 / h; For a time interval of 70 seconds or more but less than 90 seconds, the oxygen lance flow rate is 29,000 to 30,000 m³ / s. 3 / h.

2. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 1, characterized in that, Step 1) specifically refers to: When the converter is started to blow and ignite, the speed of the primary dust removal fan is adjusted from 1300r / min~1400r / min to 1200r / min~1250r / min.

3. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 2, characterized in that, After the converter has finished adding iron and scrap steel, it is rocked to the "zero position". Then the converter is rocked back 14°~16° and then rocked back to the "zero position". The lance is lowered and the blowing and ignition are started.

4. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 3, characterized in that, The amount of molten iron charged is 128 to 129 tons, and the amount of scrap steel added is 37 to 38 tons; the temperature of the molten iron is 1420℃ to 1430℃, and the silicon content of the molten iron is 0.3% to 0.4%.

5. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 1, characterized in that, In step 4), after the gun position is lowered to 1.65m, after blowing for 2 minutes, the blowing gun position is gradually lowered, and finally the gun position is lowered to the normal gun position of 1.45m.

6. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 1, characterized in that, The first batch of slag-forming materials includes one or more of ore, lime, dolomite, and dust collector briquettes.

7. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 6, characterized in that, If the temperature of the molten iron is below 1400℃, no more ore will be added to the first batch of slag-forming material.

8. The method for increasing the amount of gas recovered in the early stage of smelting under low iron consumption mode according to claim 1, characterized in that, Step 6) specifically involves: After the ignition is normal, reduce the fan speed to 1050 r / min~1070 r / min. For the primary dust removal fan in the early stage of smelting, the speed is increased in stages: when the carbon monoxide content in the flue gas is 0%~5%, the fan speed is 1150 r / min~1200 r / min; when the carbon monoxide content in the flue gas is 5%~8%, the fan speed is 1250 r / min~1290 r / min; when the carbon monoxide content in the flue gas is greater than 8%, the fan speed is 1300 r / min. The blower speed is adjusted according to the slight pressure difference at the furnace mouth during the blowing process.