Oxygen-enriched blast furnace operation method

Abstract

The present invention discloses an oxygen-enriched blast furnace operation method, in which after the furnace is warmed up, a charge is loaded, heated nitrogen gas is blown in through the tuyere to preheat, and then hot coal gas and oxygen gas are sent through the tuyere to control the theoretical combustion temperature to be 2350-2400°C. When the theoretical amount of iron in the furnace can reaches 60% of the normal safe allowable amount of iron, iron is tapped. Then, the input load is gradually increased, and the input amounts of reducing gas and oxygen gas are increased to achieve normal tapping and load adjustment in the furnace, and the theoretical combustion temperature at this stage is 2400-2500°C. In the present invention, heated nitrogen gas is blown onto the raw materials, thereby quickly and effectively drying the raw materials and raising the raw material temperature, and the blast furnace coal gas system can be made to run smoothly. In addition, heated reducing coal gas is blown into the furnace through the tuyere, so that the high-temperature, highly reducing coal gas can immediately participate in the reduction reaction with the charge at the top after entering the furnace. When combusted together with the blown-in oxygen gas, a large amount of heat is released, which quickly raises the temperature of the furnace can, shortens the blast furnace operation time, and effectively reduces the consumption of raw fuel.

Description

[Technical Field]

[0001] The present invention relates to the technical field of blast furnace iron making, and specifically to a method for operating a blast furnace by injecting coal gas with oxygen enrichment. [Background technology]

[0002] In conventional blast furnace operation, a charge is formed by mixing sinter, pellets, coke, and solvent in a certain ratio. The charge is then loaded into the furnace from the top, and hot air is blown into the blast furnace through the tuyere. As the charge moves through the blast furnace and comes into contact with the hot air, heat transfer and oxidation-reduction reactions occur, generating coal gas. The coal gas then moves upward and leaves the blast furnace through the riser. The blast furnace materials melt during the reaction and drip as molten iron and slag, which then exits the blast furnace through the taphole. Conventional blast furnace operation initially suffers from slow heat storage in the furnace chamber, low coal gas heating value, large fluctuations in coal gas usage, and insufficient indirect reduction. To accelerate the oxygen reduction reaction in the blast furnace, blast furnace operators typically increase the amount of coke and operate with an ultra-light charge load. However, this method of operation results in high fuel consumption and a long reaction cycle, and the furnace cans must go through an extremely cold and hot process, making furnace operations more difficult and risky. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention aims to provide a new method for operating an oxygen-enriched blast furnace in order to ensure safer blast furnace operation, higher efficiency, reduced carbon emissions, and economical operational goals. [Means for solving the problem]

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An oxygen-enriched blast furnace operation method, Furnace warming work (S1) involves: 1) fully opening the mixed gas valve to send cold air, and after sending the air, setting the pressure at the furnace top to 10 kPa and the air volume to 300 m 3 / min. 2) After the air temperature and the air volume are stabilized, the gas mixing valve is manually adjusted to control the actual air temperature rise according to the temperature rise curve. After the air temperature is stabilized at 150°C according to the temperature at the tip of the tuyere, the air volume is set to 400-500 m. 3 / min, and when the temperature exceeds 400°C, the air volume is increased to 500m 3 / min, and when the temperature of the air falls below 400°C during the temperature drop period, the air volume is set to 400 m 3 / min and maintain it. During the temperature increase or air volume increase process, the temperature at the furnace top should be kept below 250°C and the temperature of the airtight box should be kept below 50°C. If the temperature at the furnace top exceeds 250°C, the air volume should be increased to 50m 3 / min / times, and gradually reducing the average value of the air volume to 0 after 24 to 26 hours (S1); Charge charging work (S2), in which after the furnace warm-up is completed, charge charging is started, first putting one batch of pure coke into the bottom of the furnace, then installing a coil pipe for discharging coal gas from the tap hole, putting one batch of pure coke into the bottom, putting sleepers into the furnace can, then putting a load charge into the middle and lower part of the furnace body to make the coke rate 1500 to 1800 kg / t, putting coke with the load charge into the middle part of the furnace body to make the coke rate 1100 to 1300 kg / t, putting coke with the load charge into the upper part of the furnace body to make the coke rate 800 to 1000 kg / t, and putting normal charge into the furnace throat and the upper part of the furnace body to make the coke rate 500 to 600 kg / t; After the charge is loaded, nitrogen gas is cooled or heated and then sprayed. The pressure and flow rate of the nitrogen gas are adjusted by a control valve group, and the nitrogen gas enters a heating device, passes through a blower header pipe, an enclosure pipe, and a branch pipe, and then enters the blast furnace through the tuyere. First, room temperature nitrogen gas is sprayed onto the charge for 1 hour. Then, the heating device is started, and the temperature of the nitrogen gas is increased at a rate of 300°C / h. After 2.5 hours, if the temperature of the nitrogen gas entering the furnace reaches 900°C or higher, the heated nitrogen gas is sprayed onto the materials for 2 hours to quickly and effectively increase the temperature of the materials. During this period, the blast furnace is opened to allow ventilation, and nitrogen gas is sprayed onto the coal gas pipeline network to spray into the furnace and the coal gas pipeline network. The coal gas outlet pipe in the taphole is opened, and the dust removal function for the taphole is performed. (S3) After high-temperature nitrogen gas at 900 to 1200°C is blown at a constant temperature for 2 to 4 hours, the reducing coal gas injection system at the tuyere is started up, and the reducing coal gas has a composition of CO: 60 to 75%, CO2: 5%, H2: 10 to 15%, and O2: 0.5%. The valves of the reducing coal gas injection system are opened and closed to set a predetermined flow rate (10,000 to 15,000 m 3 / h), and turning on the reducing coal gas quick switching valve and the flow rate control valve, so that the reducing coal gas enters the heating device, mixes with nitrogen gas and is heated, passes through the blast header pipe, the enclosure pipe, the branch pipe, and then enters the blast furnace through the tuyere; and the target heating temperature is set to 900-1200°C, and the reducing coal gas is heated before being blown into the tuyere, so that the purpose of quickly raising the temperature of the furnace can only be achieved by the high-temperature reducing coal gas; and after the high-temperature reducing coal gas enters the furnace, it can immediately participate in the reduction reaction with the upper load charge, and ensure that the oxygen-iron in the raw material is reduced and then enters the furnace can in the form of metallic iron; and two or three torches are installed at the taphole, so that the coal gas can be fully combusted after it emerges from the taphole; and step (S4) of taking regional coal gas monitoring measures for the environment and measures to prevent coal gas poisoning. After introducing high-temperature reducing coal gas of 900 to 1200°C or higher into the furnace and injecting it for 1 to 2 hours, the oxygen gas injection system in the tuyeres is started, and oxygen gas is injected into the tuyeres at a rate of 15,000 to 25,000 m 3 Step (S5) to blow in at / h, After the oxygen gas injection system is started, the pressure and flow rate of the oxygen gas are adjusted by the oxygen gas valve stand, and then the oxygen gas is mixed with the high-temperature reducing coal gas and high-temperature nitrogen gas in the passage of the small sleeve in the tuyere, and enters the blast furnace, where the high-temperature coal gas and the coke in front of the tuyere are ignited at the tip of the small sleeve (S6); After the ignition at the tuyere is successful, start reducing the amount of nitrogen gas injected, and during that period, adjust the oxygen content of the overall amount of injected nitrogen gas at the tuyere to 75-100%, while gradually increasing the amount of coal gas injected, raising the heating temperature of the coal gas to 1100-1200°C, and controlling the theoretical combustion temperature before the tuyere to be within the range of 2350-2400°C (S7); Step (S8) of continuously monitoring the coal gas components at the furnace top, and when the O2 content is less than 1% and the CO content is more than 16%, the output coal gas is deemed to meet the conditions for recovery into the pipeline network, and the grid-connected valve and the cutoff valve are turned on to make the furnace top unvented, thereby completing the work of introducing the coal gas into the pipeline network, and after the introduction of the coal gas is completed, the pressure at the top begins to increase to 60-100 KPa, and as much of the initial high-temperature coal gas in the tuyere area as possible is blown out through the taphole, thereby achieving the purpose of heating the furnace can and the materials in the furnace can; a step (S9) of stabilizing the amount of oxygen gas entering the furnace and increasing the amount of hot coal gas injected from the tuyere to maintain the wind speed at the tuyere at 200-250 m / s and the theoretical combustion temperature at the tuyere at 2350-2400°C, and when it is calculated that the theoretical amount of iron in the furnace can has reached 60% of the normal safe allowable amount of iron, opening the tap hole to perform the first tapping; A step (S10) of gradually increasing the input load and increasing the input amount of reducing coal gas to adjust the theoretical combustion temperature at the tuyere to 2400 to 2500 ° C.; Next, the process includes a step (S11) of achieving normal tapping and adjusting the load in the furnace in accordance with the calculated theoretical hot metal production rate and the safe allowable iron content of the blast furnace, completing the silicon reduction work for the hot metal, and achieving the operational goal of making the oxygen-enriched blast furnace safe. [Effects of the Invention]

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0007] In the method of the present invention, the heated nitrogen gas is blown onto the raw materials, thereby quickly and effectively drying the materials and raising their temperature. This ensures sufficient heat in the furnace chamber for subsequent stages and efficient reduction reactions using highly reducing reducing coal gas. Hot nitrogen gas is blown through the tuyeres to preheat and dry the charge, while simultaneously inertizing the system and preparing it for the introduction of nitrogen and coal gas. The technical measure of heating the reducing coal gas before blowing it through the tuyeres achieves the goal of quickly raising the furnace chamber temperature. The high-temperature, highly reducing coal gas can immediately participate in the reduction reaction with the charge at the top after entering the furnace, ensuring that the temperature of the slag generated after the load charge enters the furnace chamber is sufficient, ensuring stable and efficient operation of the entire smelting process. When the hot coal gas is blown in, the reducing gas immediately undergoes an oxygen-reduction reaction with the charge, generating heat. This process skips the coal gas generation step in conventional blast furnace operation and instead reacts hot coal gas directly with the charge. Oxygen gas is injected through the tuyere to react with the coal gas, intensifying the oxygen-reduction reaction. This reduces raw fuel consumption by 60% compared to conventional blast furnaces, achieving a comprehensive fuel ratio of 800 kg / t. Furthermore, because the blast furnace is operated entirely by blowing coal gas into the furnace with oxygen, the amount of coal gas in the furnace is smaller than in conventional blast furnaces, allowing for smoother operation. Furthermore, the ignition process has been further simplified, requiring only oxygen gas to be delivered. This is an advantage over the COREX process, which also involves pure oxygen smelting, as it eliminates the need for manual ignition via the tuyere. Finally, oxygen gas is directly injected into the furnace through the tuyere to maintain the theoretical combustion temperature before the tuyere in the range of 2350-2400°C, and the oxygen gas and reducing coal gas are mixed in the small sleeve passage in the tuyere and then injected into the furnace, thereby enhancing the intensity of smelting. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a graph of the temperature rise of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following clearly and completely describes the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without any creative efforts are within the scope of protection of the present invention.

[0010] The present invention provides the following technical solutions:

[0011] The oxygen enrichment blast furnace operation method includes the following steps: In furnace warming work (S1), 1) Fully open the mixed gas valve to send in cold air. After sending in the air, set the pressure at the top of the furnace to 10 kPa and the air volume to 300 m 3 / min, 2) After the air temperature and volume are stabilized, manually adjust the gas mixing valve to control the actual air temperature rise according to the temperature rise curve, according to the temperature at the tip of the tuyere. The temperature rise curve is as shown in Figure 1. After the air temperature is stabilized at 150°C, the air volume is set to 400-500m 3 / min, and when the air temperature exceeds 400°C, the air volume is increased to 500m 3 / min, and when the temperature drops below 400°C during the temperature drop period, the air volume will be increased to 400m3 until the end of the temperature drop. 3 / min and maintain it. During the temperature increase or air volume increase process, the temperature at the furnace top should be below 250℃ and the temperature of the airtight box should be below 50℃. If the temperature at the furnace top exceeds 250℃, the air volume should be increased to 50m 3 / min / times, and gradually decrease so that the average airflow reaches 0 after 24 to 26 hours.

[0012] In the charge charging operation (S2), after the furnace warm-up is completed, the charging of the charge begins. First, one batch of pure coke is charged into the bottom of the furnace, then a coil pipe for extracting coal gas is installed from the taphole, and one batch of pure coke is charged. After putting sleepers into the furnace can, a load charge is charged into the middle and lower part of the furnace body at a coke rate of 1500 to 1800 kg / t, coke with a load charge is charged into the middle part of the furnace body at a coke rate of 1100 to 1300 kg / t, coke with a load charge is charged into the upper part of the furnace body at a coke rate of 800 to 1000 kg / t, and normal charge is charged into the furnace throat and upper part of the furnace body at a coke rate of 500 to 600 kg / t.

[0013] In step (S3), after the charge is loaded, nitrogen gas is cooled or heated and then sprayed. The pressure and flow rate of the nitrogen gas are adjusted by the control valves. The nitrogen gas enters the heating device, passes through the blast header pipe, the enclosure pipe, and the branch pipe, and then enters the blast furnace through the tuyere. First, room temperature nitrogen gas is sprayed onto the charge for 1 hour. Then, the heating device is started and the temperature of the nitrogen gas is increased at a rate of 300°C / h. After 2.5 hours, if the temperature of the nitrogen gas entering the furnace reaches 900°C or higher, the heated nitrogen gas is sprayed onto the materials for 2 hours to quickly and effectively increase the material temperature. During this period, the blast furnace is opened to allow ventilation, and nitrogen gas is sprayed onto the coal gas pipeline network, blowing it into the furnace and the coal gas pipeline network. The coal gas outlet pipe at the taphole is opened to provide dust removal for the taphole.

[0014] In step (S4), after blowing high-temperature nitrogen gas at 900 to 1200°C at a constant temperature for 2 to 4 hours, the reducing coal gas injection system at the tuyere is started, and the valve group of the reducing coal gas injection system is set to a predetermined flow rate (10,000 to 15,000 m 3 / h), and the reducing coal gas quick switching valve and flow control valve are turned on. The reducing coal gas enters the heating device, where it is mixed with nitrogen gas and heated before passing through the blast header pipe, shroud pipe, and branch pipe before entering the blast furnace through the tuyeres. The target heating temperature is set at 900-1200°C, and the reducing coal gas is heated before being injected through the tuyeres. The high-temperature reducing coal gas alone can achieve the purpose of quickly raising the furnace casing temperature. After the high-temperature reducing coal gas enters the furnace, it can immediately participate in the reduction reaction with the upper load charge, ensuring that the oxygen-iron in the raw materials is reduced and enters the furnace casing in the form of metallic iron. Two to three torches are installed at the taphole to ensure that the coal gas can be fully combusted after it emerges from the taphole. Measures for environmental coal gas monitoring and prevention of coal gas poisoning are also in place.

[0015] In step (S5), high-temperature reducing coal gas at 900 to 1200°C or higher is introduced into the furnace and injected for 1 to 2 hours, after which the oxygen gas injection system at the tuyere is started and oxygen gas is injected into the tuyere at a rate of 15,000 to 25,000 m 3 Blow in at / h.

[0016] In the ignition operation (S6), after the oxygen gas injection system is started, the pressure and flow rate of the oxygen gas are adjusted by the oxygen gas valve stand, and then the oxygen gas is mixed with the high-temperature reducing coal gas and high-temperature nitrogen gas in the passage of the small sleeve in the tuyere, and enters the blast furnace, where it ignites the high-temperature coal gas and the coke in front of the tuyere at the tip of the small sleeve.

[0017] In step (S7), after successful ignition at the tuyere, the amount of nitrogen gas injected begins to decrease, and during that period, the oxygen content of the overall amount injected at the tuyere is adjusted to be 75 to 100%, while the amount of coal gas injected is gradually increased, and the heating temperature of the coal gas is increased to 1100 to 1200°C, so that the theoretical combustion temperature before the tuyere is controlled to be in the range of 2350 to 2400°C.

[0018] In step (S8), the coal gas components at the furnace top are continuously monitored. If the O2 content is less than 1% and the CO content is more than 16%, the output coal gas is deemed to meet the conditions for being returned to the pipeline network. The grid-connected double-barrel valve and the cutoff valve are turned on to make the furnace top unventable, thereby completing the introduction of the coal gas into the pipeline network. After the introduction of the coal gas is completed, the pressure at the top begins to increase to 60-100 KPa, and as much of the initial high-temperature coal gas in the tuyere area as possible is blown out through the taphole, thereby achieving the purpose of heating the furnace can and the materials inside the furnace can.

[0019] In step (S9), the amount of oxygen gas entering the furnace is stabilized and the amount of hot coal gas injected from the tuyere is increased to maintain the wind speed at the tuyere at 200 to 250 m / s and the theoretical combustion temperature at the tuyere at 2350 to 2400°C.When it is calculated that the theoretical amount of iron in the furnace can has reached 60% of the normal safe allowable amount of iron, the tap hole is opened and the first tapping is performed.

[0020] In step (S10), the furnace load is gradually increased, the amount of reducing coal gas entering the furnace is increased, and the theoretical combustion temperature at the tuyere is adjusted to 2400 to 2500°C.

[0021] In step (S11), normal tapping and load adjustment in the furnace are performed according to the calculated theoretical hot metal production rate and the safe allowable iron content of the blast furnace, and the silicon reduction work in the hot metal is completed, thereby achieving the operational goal of safe operation of the oxygen-enriched blast furnace.

Claims

[Claim 1] Furnace heating work (S1) in which heated and compressed air is introduced into the hot air furnace to heat the furnace for 24 hours; After the furnace warm-up is complete, the charge preparation work begins. First, one batch of pure coke is placed in the bottom of the furnace, then a coil pipe for discharging coal gas is installed from the tap hole, and pure coke is added. After placing sleepers in the furnace can, a charge with a coke rate of 1500 to 1800 kg / t is placed in the middle and lower part of the furnace body, a charge with a coke rate of 1100 to 1300 kg / t is placed in the middle part of the furnace body, a charge with a coke rate of 800 to 1000 kg / t is placed in the upper part of the furnace body, and a charge with a coke rate of 500 to 600 kg / t is placed in the furnace throat and the upper part of the furnace body, so that the total coke rate of the charges placed is 800 to 900 kg / t (S2). After the charge preparation work is completed, nitrogen gas is cooled and heated before being sprayed. The pressure and flow rate of the nitrogen gas are adjusted by a group of control valves, and then the nitrogen gas enters a heating device, passes through a blower header pipe, an enclosure pipe, and a branch pipe, and then enters the blast furnace through a tuyere. First, room temperature nitrogen gas is sprayed onto the charge for 1 hour. Then, the heating device is started and the temperature of the nitrogen gas is increased at a rate of 300°C / h. After 2.5 hours, the temperature of the nitrogen gas entering the furnace reaches 900-1200°C or higher. Then, the heated nitrogen gas is sprayed onto the raw materials for 2-4 hours, thereby quickly and effectively raising the temperature of the raw materials. During the period when the nitrogen gas is being sprayed, the blast furnace is opened to allow ventilation, and nitrogen gas is sprayed onto the coal gas pipeline network, thereby spraying it into the furnace and the coal gas pipeline network. The pipe for discharging the coal gas at the tap hole is opened, and the dust removal function for the tap hole is performed. (S3) After 2 to 4 hours of constant-temperature blowing of high-temperature nitrogen gas at 900 to 1200°C, the reducing coal gas injection system at the tuyere is started, and the valve group of the reducing coal gas injection system is opened to a predetermined flow rate of 10,000 to 20,000 m ３ / h, and starts up, and turns on the reducing coal gas quick switching valve and flow control valve, so that the reducing coal gas enters the heating device, mixes with nitrogen gas and heats it, passes through the blower header pipe, the enclosure pipe, the branch pipe, and then enters the blast furnace through the tuyeres; and the target heating temperature is set to 900-1200°C, and the reducing coal gas is heated before being blown into the tuyeres. The high-temperature reducing coal gas alone can achieve the purpose of quickly raising the temperature of the furnace can. After entering the furnace, the high-temperature reducing coal gas can immediately participate in the reduction reaction with the upper charge, ensuring that the iron oxygen in the raw material is reduced and then enters the furnace can in the form of metallic iron. Two or three torches are installed at the taphole, ensuring that the coal gas can be fully combusted after it emerges from the taphole; and step (S4) of taking regional coal gas monitoring measures and coal gas poisoning prevention measures for the environment. After introducing high-temperature reducing coal gas of 900°C or higher into the furnace and injecting it for 1 to 2 hours, the oxygen gas injection system at the tuyere is started and oxygen gas is injected into the tuyere at a rate of 15,000 to 25,000 m ３ / h blowing step (S5); After the oxygen gas injection system is started, the pressure and flow rate of the oxygen gas are adjusted by the oxygen gas valve stand, and then the oxygen gas is mixed with the high-temperature reducing coal gas and high-temperature nitrogen gas in the passage of the small sleeve in the tuyere, and enters the blast furnace, where the high-temperature coal gas and the coke in front of the tuyere are ignited at the tip of the small sleeve (S6). After the tuyere ignition is successful, start to reduce the amount of nitrogen gas injected, adjust the oxygen content of the overall amount of injected gas at the tuyere to 75-100 vol%, and gradually increase the amount of coal gas injected, raise the heating temperature of the coal gas to 1100-1200°C, and control the combustion temperature before the tuyere to be in the range of 2350-2400°C (S7); Continuously monitor the coal gas components at the furnace top and ２ and (S8) after the content of CO is less than 1 vol% and the content of CO exceeds 16 vol%, the output coal gas is deemed to meet the conditions for recovery into the pipeline network, and the valve for introducing the coal gas into the pipeline network and the cutoff valve are turned on to make the furnace top unvented, thereby completing the operation of introducing the coal gas into the pipeline network. After the introduction of the coal gas is completed, the pressure at the top begins to increase to 60-100 KPa, and the initial high-temperature coal gas in the tuyere region is blown out through the tap hole, thereby achieving the purpose of heating the furnace can and the raw materials in the furnace can. A step (S9) of adjusting the amount of oxygen gas entering the furnace and synchronously adjusting the amount of hot coal gas injected from the tuyere to maintain the wind speed at the tuyere at 200-250 m / s and the combustion temperature at the tuyere at 2350-2400°C, and when it is calculated that the amount of iron in the furnace has reached 60 wt% of the normal safe allowable amount of iron, opening the tap hole and performing the first tapping; Step (S10) of gradually increasing the amount of charge fed to the blast furnace and increasing the amount of reduced coal gas entering the furnace to adjust the combustion temperature at the tuyere to 2400 to 2500 ° C; and (S11) adjusting the normal tapping and charging in the furnace according to the calculated hot metal production amount and the safe allowable iron content of the blast furnace, thereby completing the silicon reduction work of the hot metal and achieving the operational goal of safe operation of the oxygen-enriched blast furnace. An oxygen-enriched blast furnace operation method.

Images