WO2023134369A1

WO2023134369A1 - Oxygen enrichment blast-furnace blow in method

Info

Publication number: WO2023134369A1
Application number: PCT/CN2022/138698
Authority: WO
Inventors: 田宝山; 田庄; 刘永想; 臧疆文; 安志庆
Original assignee: 新疆八一钢铁股份有限公司
Priority date: 2022-01-12
Filing date: 2022-12-13
Publication date: 2023-07-20
Also published as: CN114427011A; CN114427011B

Abstract

Disclosed in the present invention is an oxygen blast-furnace blow in method. The method comprises: filling a furnace with a furnace charge material after the furnace is dried, injecting and heating nitrogen at a tuyere for preheating, then feeding hot coal gas and oxygen through the tuyere, controlling the theoretical combustion temperature at 2350-2400ºC, and performing iron tapping once the theoretical iron amount in a hearth reaches 60% of the normal safe iron capacity; and then, gradually increasing an in-furnace load, increasing an in-furnace reduction coal gas amount and oxygen amount, and organizing normal iron tapping and in-furnace load adjustment, wherein the theoretical combustion temperature during this stage is 2400-2500ºC. In the present invention, heated nitrogen is used for purging materials, such that quick and effective drying is achieved, the temperature of materials is increased, and a blast-furnace coal gas system is made inert; a heated reduction coal gas is blown therein through the tuyere, and the high-temperature and high-reducibility coal gas, upon entering the furnace, immediately undergoes a reduction reaction with the upper furnace charge material, and are combusted with injected oxygen to release a large amount of heat, so that the temperature of the hearth can be quickly increased, the blow-in time is shortened, and the raw material and fuel consumption is effectively reduced.

Description

A kind of oxygen-enriched blast furnace start-up method

technical field

The invention belongs to the technical field of blast furnace ironmaking, and in particular relates to a blast furnace start-up method for injecting gas rich in oxygen.

Background technique

In the opening of a traditional blast furnace, sinter, pellets, coke, and solvents are used to form the charge in a certain proportion. The charge is put into the furnace from the top of the furnace, and hot air is blown into the tuyere of the blast furnace. Heat transfer occurs when the charge moves in contact with the hot air in the blast furnace. And oxidation-reduction reaction produces gas, the gas moves upward from the riser to leave the blast furnace, the blast furnace material melts and drops into molten iron and slag during the reaction process, and the liquid slag iron is discharged from the blast furnace from the tap hole. During the start-up process of the traditional blast furnace, there are difficulties in the initial hearth heat storage process, low calorific value of gas, large fluctuations in gas utilization rate, and insufficient indirect reduction process. Blast furnace workers usually The furnace is started by increasing the amount of coke and using ultra-light-load furnace materials. This method consumes a lot of fuel and has a long reaction cycle. The furnace hearth usually needs to experience extreme cold and extreme heat. The operation before the furnace is difficult and risky.

Contents of the invention

The purpose of the present invention is to provide a new method for starting an oxygen-enriched blast furnace, so as to ensure that the goals of safe, efficient, carbon-reducing and economical start-up of the blast furnace can be realized.

To achieve the above object, the present invention provides the following technical solutions:

A method for starting an oxygen-enriched blast furnace, comprising the following steps:

S1. Oven operation:

1) Fully open the air mixing valve to send cold air. After the air is supplied, the furnace top pressure is set to 10kpa, and the air volume is set to 300m ³ /min;

2) After the air temperature and air volume are stable, manually adjust the air mixing valve, and control the actual air temperature rise according to the temperature rise curve. The temperature at the front end of the air outlet shall prevail. After the air supply temperature is stable at 150°C, the air volume shall be specified as 400-500m ³ /min; When the temperature is higher than 400°C, the air volume is specified to be 500m ³ /min; when the air supply temperature is ≤400°C during the cooling period, the air volume is specified to be 400m ³ /min and kept until the end of the cooling period. During heating or adding air, ensure that the furnace top temperature is ≤250°C , the temperature of the airtight box is ≤50°C, when the furnace top temperature is >250°C, reduce the air volume by 50m ³ /min/time, and gradually reduce the air volume to 0 on average in 24-26 hours.

S2. Charging filling operation:

After finishing the oven, the charge filling starts. First add 1 batch of clean coke to the bottom of the furnace, then arrange the coil pipes exported from the iron mouth gas, and then add 1 batch of clean coke, then add sleepers to the hearth, and then add loading materials to the middle and lower parts of the furnace body. The coke ratio is 1500-1800kg/t. The middle part of the furnace is filled with empty coke with loaded materials, the coke ratio is 1100-1300kg/t, the upper part of the furnace body is empty coke with loaded materials, the coke ratio is 800-1000kg/t, and the furnace and the upper part of the furnace are added with normal materials, the coke ratio is 500-600kg/t.

S3. Nitrogen cold blowing and hot blowing after filling the furnace charge. The nitrogen gas enters the heating device after adjusting the pressure and flow rate by the control valve group, and then enters the blast furnace from the tuyere after passing through the air supply main pipe, surrounding pipes, and branch pipes. First blow nitrogen at room temperature for purge After charging for 1 hour, start the heating device, raise the nitrogen temperature, and increase the nitrogen temperature at a rate of 300°C/h. After 2.5 hours, the nitrogen temperature in the furnace reaches above 900°C. Use the heated nitrogen to purge the material for 2 hours, quickly and effectively Raise the material temperature. During the period, the blast furnace is vented and opened, the gas pipe network is purged with nitrogen, the furnace and the gas pipe network are purged, the gas outlet pipe of the iron port is opened, and the dust removal of the iron port is started;

S4. After purging at 900-1200°C high-temperature nitrogen constant temperature for 2-4 hours, start the reducing gas injection system at the tuyere, and the reducing gas composition is CO: 60-75%, CO ₂ : 5%, H ₂ : 10-15%, O ₂ : 0.5%, the valve group of the reduction gas injection system begins to start according to the set flow rate (10000-15000m ³ /h), and the reduction gas quick-cut valve and the flow control valve are opened, and the reduction gas enters the heating device and is mixed with nitrogen and heated Then enter the blast furnace from the tuyere through the main air supply pipe, surrounding pipe and branch pipe. And set the heating target temperature to be 900-1200°C. After the reduced gas is heated, it is blown in from the tuyere, and the high-temperature reduced gas can achieve the purpose of rapidly raising the hearth temperature, and the high-temperature reducing gas can immediately participate in the reduction reaction of the upper load material after entering the furnace, so as to ensure that the iron oxide in the material is reduced. Metallic iron forms into the hearth. Set up 2-3 torches at the iron mouth to ensure that all the gas is ignited after gushing out of the iron mouth, and do a good job of regional environmental gas monitoring and anti-gas poisoning measures;

S5. After injecting high temperature reducing gas above 900-1200℃ into the furnace for 1-2 hours, start the oxygen injection system at the tuyere, and send 15000-25000m ³ /h of oxygen to the tuyere.

S6. Ignition operation: After the oxygen injection system is started, oxygen is mixed with high-temperature reducing gas and high-temperature nitrogen at the small channel of the tuyere after adjusting the pressure and flow through the oxygen valve table, enters the blast furnace, and ignites the high-temperature gas at the front of the small set. Coke in front of the tuyere.

S7. After the tuyere is successfully ignited, start to reduce the amount of nitrogen added. During this period, adjust the overall oxygen content of the tuyere to 75-100%, gradually increase the amount of gas injection, raise the gas heating temperature to 1100-1200°C, and reduce the theoretical combustion temperature before the tuyere. Control at 2350-2400°C;

S8. Continuous monitoring of furnace top gas composition, O ₂ content is less than 1%, CO content exceeds 16%, and the output gas is ready to be recycled into the pipeline network. Open the net mesh valve and cut-off valve, close the furnace top to vent, and complete the gas introduction After entering the pipe network, after the introduction of coal gas, start to increase the top pressure to 60-100Kpa, so that the initial high-temperature gas in the tuyere area can be sprayed out from the iron port as much as possible to achieve the purpose of heating the hearth and hearth materials;

S9. Stabilize the amount of oxygen entering the furnace, increase the amount of high-temperature gas injected from the tuyere, keep the wind speed at the tuyere at 200-250m/s, and the theoretical combustion temperature at the tuyere at 2350-2400°C. Calculate the theoretical iron content in the hearth to reach 60% of the normal safe iron content %, open the iron mouth and place the first furnace of iron;

S10. Gradually increase the load into the furnace, increase the amount of reducing gas into the furnace, and adjust the theoretical combustion temperature of the tuyere to 2400-2500 °C;

S11. Follow up to organize normal tapping and load adjustment in the furnace according to the calculated theoretical molten iron output and the safe iron capacity of the blast furnace, and complete the silicon reduction operation of the molten iron, so as to achieve the goal of safe start-up of the oxygen blast furnace.

Compared with prior art, the beneficial effect of the present invention is:

The method of the present invention uses the heated nitrogen to purge the materials, which can quickly and effectively dry and increase the temperature of the materials, ensuring sufficient heat in the subsequent furnace hearth and efficient reduction reaction of the highly reducing reducing gas; While preheating and drying the furnace charge, inert the system to prepare for sending oxygen and gas; the technical measure of heating the reduced gas and blowing it in from the tuyere can achieve the purpose of quickly raising the hearth temperature, and the high temperature and high When the reducing gas enters the furnace, it can immediately trigger the reduction reaction of the upper load material, which can ensure that the temperature of the slag and iron generated after the load material enters the hearth is sufficient, so that the entire smelting process can proceed smoothly and efficiently; after the hot gas is fed in, the reducing gas immediately Oxidation-reduction reaction with charge to generate heat. This process is equivalent to skipping the traditional blast furnace gas production process, directly allowing the hot gas to react with the furnace charge, and the tuyere sends oxygen to react with the gas to intensify the redox reaction process, so its raw fuel consumption is 60% less than that of traditional blast furnaces , The comprehensive fuel ratio of starting the furnace is 800kg/t. Because the furnace is opened with full oxygen injection gas, the bosh gas volume is smaller than that of the traditional blast furnace gas, and the blast furnace runs better; the ignition operation is simpler, and the ignition operation can be completed by sending oxygen, which is better than the COREX process, which is also pure oxygen smelting. Personnel are required to ignite the tuyere; oxygen is directly injected into the furnace from the tuyere, and the theoretical combustion temperature in front of the tuyere is kept between 2350-2400 ° C. Oxygen and reduced gas are mixed and injected into the furnace at the small channel of the tuyere to increase the smelting intensity.

Description of drawings

Fig. 1 is the heating curve diagram of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The present invention provides the following technical implementation solutions:

S1. Oven operation:

2) After the air temperature and air volume are stable, manually adjust the air mixing valve to control the actual air temperature rise according to the heating curve, and the temperature at the front end of the air outlet shall prevail. The heating curve is shown in Figure 1.

After the air supply temperature is stable at 150°C, the air volume is specified to be 400-500m ³ /min; when the supply air temperature is >400°C, the air volume is specified to be 500m ³ ^/ min; Keep until the end of cooling, during heating or adding air, ensure that the temperature of the furnace top is ≤250°C, and the temperature of the airtight box is ≤50°C. When the temperature of the furnace top is >250°C, reduce the air by 50m ³ /min/time, 24-26 hours In this stage, the air volume is gradually reduced to 0 on average.

S2. Charging filling operation:

S4. After 900-1200°C high-temperature nitrogen constant temperature purge for 2-4 hours, start the reduction gas injection system at the tuyere, the valve group of the reduction gas injection system will start according to the set flow rate (10000-15000m ³ /h), and turn on the reduction gas Quick cut valve, flow regulating valve, reducing gas enters the heating device, mixes with nitrogen, heats up, and then enters the blast furnace through the air supply main pipe, surrounding pipe, and branch pipe from the tuyere. And set the heating target temperature to be 900-1200°C. After the reduced gas is heated, it is blown in from the tuyere, and the high-temperature reduced gas can achieve the purpose of rapidly raising the hearth temperature, and the high-temperature reducing gas can immediately participate in the reduction reaction of the upper load material after entering the furnace, so as to ensure that the iron oxide in the material is reduced. Metallic iron forms into the hearth. Set up 2-3 torches at the iron gate to ensure that all the gas is ignited after gushing out of the iron gate, and do a good job in regional environmental gas monitoring and anti-gas poisoning measures;

S8. Continuous monitoring of furnace top gas composition, O ₂ content is less than 1%, CO content exceeds 16%, and the output gas is ready to be recycled into the pipeline network. Open the net mesh valve and cut-off valve, close the furnace top to vent, and complete the gas introduction After entering the pipe network, after the gas induction is completed, start to increase the top pressure to 60-100Kpa, so that the initial high-temperature gas in the tuyere area can be sprayed out from the iron port as much as possible to achieve the acceleration.

the purpose of hot hearths and hearth materials;

S9. Stabilize the amount of oxygen entering the furnace, increase the amount of high-temperature gas injected from the tuyere, keep the wind speed at the tuyere at 200-250m/s, and the theoretical combustion temperature at the tuyere at 2350-2400°C. When the theoretical iron content in the furnace hearth reaches 60% of the normal safe iron capacity, open the iron mouth and put the first furnace iron;

Claims

A method for starting an oxygen blast furnace, which is characterized in that: after the furnace is baked, the furnace charge is filled, and the tuyere is blown and heated with nitrogen for 5 hours, the charge is preheated and the blast furnace gas system is inert, and then the tuyere is fed with hot gas and oxygen to control the theoretical combustion temperature At 2350-2400°C, when the theoretical iron content in the hearth reaches 60% of the normal safe iron capacity, the iron is tapped; then gradually increase the load into the furnace, increase the amount of reducing gas into the furnace, and control the theoretical combustion temperature at this stage at 2400-2500 ℃, organize normal tapping and furnace load adjustment.
A method for starting an oxygen-enriched blast furnace according to claim 1, characterized in that it comprises the following steps:

S1. Oven operation: Send heated compressed air through the hot blast stove for 24 hours; S2. Furnace charge filling operation: After the oven is completed, start the charge filling operation; Coil pipe, add net coke afterward, add sleepers to the furnace hearth, and then load material in the middle and lower part of the furnace body, the coke ratio is 1500-1800kg/t, add empty coke in the middle part of the furnace body with load material, the coke ratio is 1100-1300kg/t, the furnace Empty coke with loaded material on the upper part of the furnace, the coke ratio is 800-1000kg/t, normal material is added to the furnace and the upper part of the furnace body, the coke ratio is 500-600kg/t, and the comprehensive coke ratio of the furnace charge is 800-900kg/t; S3. After the furnace charge is filled Nitrogen cold blowing, hot blowing, nitrogen is adjusted by the control valve group to adjust the pressure and flow, then enters the heating device, and then enters the blast furnace from the tuyere after passing through the air supply main pipe, surrounding pipe, branch pipe, blowing nitrogen at room temperature to purge the charge for 1 hour, and then start heating The device raises the temperature of nitrogen gas at a rate of 300°C/h. After 2.5 hours, the temperature of nitrogen gas entering the furnace reaches above 900-1200°C. Use the heated nitrogen gas to purge the material for 2-4 hours to quickly and effectively increase the temperature of the material. Open, purge the gas pipe network with nitrogen, purge the furnace and the gas pipe network, open the gas outlet pipe of the iron port, and start the operation of the dust removal at the iron port; S4. Start the reduction gas injection system at the tuyere, the valve group of the reduction gas injection system starts to start according to the set flow rate of 10000-20000m 3 /h, open the reduction gas quick cut valve and flow regulating valve, the reduction gas enters the heating device and mixes with nitrogen for heating Enter the blast furnace from the tuyeres through the main air supply pipe, surrounding pipes, and branch pipes, and set the heating target temperature at 900-1200°C, heat the reduced gas and blow it in from the tuyere, and the high-temperature reduced gas can quickly increase the hearth temperature. Moreover, when high-temperature reducing gas enters the furnace, it can immediately participate in the reduction reaction of the upper load material, ensuring that the iron oxide in the material is reduced and enters the furnace hearth in the form of metallic iron. 2-3 torches are installed at the iron port to ensure that the gas gushes out from the iron port. Ignite all of them, and do a good job of regional environmental gas monitoring and gas poisoning prevention measures; S5. After injecting high-temperature reduced gas above 900°C into the furnace for 1-2 hours, start the tuyere oxygen injection system and send oxygen to the tuyere for 15000-25000m 3 /h; S6. Ignition operation: After the oxygen injection system is started, oxygen is mixed with high-temperature reduction gas and high-temperature nitrogen at the small tuyere channel through the oxygen valve table to adjust the pressure and flow rate, enter the blast furnace, and be introduced at the front of the small set. Burn high-temperature gas and coke in front of the tuyere; S7. After the tuyere is ignited successfully, start to reduce the amount of nitrogen added. During the period, adjust the overall blast oxygen content of the tuyere to 75-100%, and gradually increase the gas injection volume, and raise the gas heating temperature to 1100 -1200°C, the theoretical combustion temperature before the tuyere is controlled at 2350-2400°C; S8. Continuous monitoring of the furnace top gas composition, the O2 content is less than 1%, and the CO content exceeds 16%. Mesh glasses valve, cut-off valve, close the top of the furnace to vent, and complete the operation of introducing gas into the pipe network. After the completion of introducing gas, start to increase the top pressure to 60-100Kpa, so that the initial high-temperature gas in the tuyere area is ejected from the iron port to reach the heating hearth and The purpose of hearth materials; S9. Adjust the amount of oxygen into the furnace, adjust the amount of high-temperature gas injected by the tuyeres simultaneously, keep the wind speed at the tuyere at 200-250m/s, and the theoretical combustion temperature at the tuyere at 2350-2400°C. Calculate the theoretical iron content in the hearth to reach When the normal safe iron capacity is 60%, open the iron gate to put the first furnace of iron; S10. Gradually increase the load into the furnace, increase the amount of reducing gas into the furnace, and adjust the theoretical combustion temperature of the tuyere to 2400-2500 °C; S11. Follow up according to the calculation Theoretical molten iron output and blast furnace safe iron capacity organize normal tapping and load adjustment in the furnace to complete the silicon reduction operation of molten iron, thereby achieving the goal of safe start-up of the oxygen blast furnace.
A method for starting an oxygen-enriched blast furnace according to claim 1, characterized in that: before starting the furnace, first use cold nitrogen to purge the material and the gas system, then use the heater to heat the nitrogen to purge and preheat the charge, and then start the reduction Coal gas, whose composition is CO: 60-75%, CO 2 : 5%, H 2 : 10-15%, O 2 : 0.5%, preheats and reduces the charge, and finally sends oxygen to realize ignition and start-up.
A method for starting an oxygen-enriched blast furnace according to claim 1, characterized in that: the materials in the furnace are purged with hot nitrogen, hot coal gas and reduced, oxygen is directly sent through the tuyere, and coke and reduced gas in the furnace are ignited , realize the ignition of the furnace, and adjust the amount of reducing gas and nitrogen injected into the furnace to adjust the theoretical combustion temperature of the tuyere in a reasonable space after 2350-2400 ° C. While adding oxygen, gradually increase the amount of reducing gas injection. Reduce the amount of nitrogen into the furnace, and gradually realize the smelting mode of full oxygen and reduced gas injection at the tuyere. After the furnace is turned on normally, the amount of oxygen per ton of iron is 200-300m 3 /t, and the amount of reduced gas injection per ton of iron is 500-750m 3 /t , The reducing gas temperature is 900-1200°C.