Iron ore sintering ignition method based on blast furnace hot air

Abstract

The iron ore sintering ignition method based on the blast furnace hot air comprises the steps that an air inducing pipe is arranged between a hot blast stove and a sintering machine, high-grade oxygen-enriched hot air obtained after a blast furnace blast heating task is completed in the hot blast stove is induced, and the high-grade oxygen-enriched hot air is conveyed to an ignition section of the sintering machine through the air inducing pipe; the temperature of the hot air is adjusted to the target ignition temperature in an air mixing mode; through segregation material distribution, the proportion of the solid fuel in the thickness range of 30-80 mm on the surface layer of the sintering mixture is increased by 2-3% compared with the average fuel proportion of a material layer; and the hot air after temperature regulation passes through a nozzle on an ignition cover of the sintering machine. The high-temperature oxygen-enriched hot air of the blast furnace hot blast stove is directly utilized, gas combustion is completely abandoned, the Boudol reaction caused by oxygen consumption and high-concentration CO2 generation due to gas combustion is fundamentally eliminated, solid fuel can be sufficiently combusted in the oxygen-enriched atmosphere, and the utilization rate is remarkably increased.

Description

Technical Field

[0001] This invention relates to the field of sintering technology in iron and steel metallurgy, specifically to a method for igniting iron ore sintering based on blast furnace hot blast. Background Technology

[0002] Sintering is an important raw material pretreatment process in iron and steel smelting. It aims to ignite solid fuels (such as coke powder) in the mixture to partially melt and bind iron ore powder, forming sintered ore with sufficient strength and metallurgical properties.

[0003] Currently, the sintering ignition process commonly used by steel companies both domestically and internationally uses gas (such as blast furnace gas, coke oven gas, converter gas, or natural gas) as the main heat source, supplemented by combustion air, to form a high-temperature flame inside the ignition hood to heat the mixture on the surface of the sintering trolley.

[0004] However, this traditional gas ignition method has the following inherent defects and limitations: (1) Consuming oxygen and producing high concentrations of CO2: When the gas burns inside the ignition hood, it consumes a large amount of oxygen in the combustion air and inevitably produces high concentrations of carbon dioxide (CO2). This results in a localized reducing atmosphere in the ignition area with insufficient oxygen content.

[0005] (2) The Bodor reaction is triggered, resulting in low utilization of solid fuel: At the high ignition temperature, the large amount of CO2 produced by the combustion of the gas will undergo a strong Bodor reaction with the solid fuel (carbon) in the mixture (CO2+C→2CO). This reaction is an endothermic reaction, which not only consumes a large amount of solid fuel, but also causes heat loss on the surface of the sinter due to its endothermic characteristics, resulting in low actual utilization of solid fuel and insufficient ignition, which in turn causes fluctuations in the quality of sintered ore.

[0006] (3) High solid fuel consumption and carbon emissions: In order to compensate for the heat loss caused by the Bourdon reaction and insufficient ignition, the proportion of solid fuel usually needs to be increased in production. This not only increases the production cost, but also directly leads to high solid fuel consumption and carbon dioxide emissions in the sintering process, making it difficult to meet the current requirements of green and low-carbon manufacturing.

[0007] To address the shortcomings of traditional ignition technology, the industry has proposed several improvement schemes, but all of them have significant drawbacks: Existing technology 1: Oxygen-enriched ignition Increasing the oxygen content in the combustion air by 5-10 percentage points can alleviate the oxygen deficiency problem in the ignition zone. However, this method cannot reduce the high concentration of CO2 produced by the combustion of the gas itself, and therefore cannot fundamentally inhibit the Bourdon reaction, resulting in limited effectiveness in reducing CO generation and solid fuel consumption. Furthermore, oxygen-enriched operation is costly. For example, increasing the oxygen concentration by 5 percentage points in a 265m² sintering machine increases the cost by approximately 300 yuan per hour, equivalent to about 1 yuan per ton of ore, making it uneconomical.

[0008] Existing technology 2: Waste heat combustion-aiding air preheating Using waste heat to preheat combustion air can reduce gas consumption. While this method offers some energy savings, it remains fundamentally within the realm of gas ignition and has very limited effectiveness in reducing CO2 emissions and addressing core issues such as the Bourdon reaction.

[0009] Existing technology 3: Microwave ignition Microwave energy is used to directly heat air, achieving low-temperature, high-oxygen ignition. Although this technology has shown potential in the laboratory, its application in large-scale industrial sintering equipment still faces significant challenges in terms of microwave source lifespan, equipment size, and maintenance costs, making large-scale implementation in enterprises currently impossible.

[0010] In summary, existing sintering ignition technologies, due to inherent flaws, high costs, or immature technology, are all unable to effectively achieve efficient utilization of solid fuels and significant reduction in carbon dioxide emissions while ensuring the quality of sintered ore.

[0011] Therefore, developing a completely new sintering ignition method that can overcome the above-mentioned defects in principle is of extremely urgent industrial demand and significant environmental importance. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an iron ore sintering ignition method that couples the heat source of the blast furnace hot blast stove with the strengthening of material segregation, thereby synergistically improving the ignition quality and the quality of sintered ore.

[0013] The technical problem to be solved by the present invention is achieved through the following technical solution: a method for igniting iron ore sintering based on blast furnace hot blast, the steps of which are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine to induced draft of the high-grade oxygen-enriched hot blast after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot blast is 1100℃~1300℃, the oxygen content is 23%~25%, and the carbon dioxide concentration is 1%~1.5%. (2) The high-grade oxygen-enriched hot air is transported to the ignition section of the sintering machine through the duct, and the hot air temperature is adjusted to the target ignition temperature by mixing with air. The volume flow rate of the mixed air accounts for 30% to 70% of the volume flow rate of the high-grade oxygen-enriched hot air in the duct. The target ignition temperature is 700℃ to 1000℃. (3) By segregating the material, the solid fuel ratio in the 30mm~80mm thickness range of the sintered mixture surface layer is increased by 2%~3% compared with the average fuel ratio of the material layer; (4) The hot air after temperature adjustment passes through the nozzles on the ignition cover of the sintering machine. The nozzles are arranged in parallel along the width of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering machine trolley. The spray wind speed is 5~15m / s, and ignition is carried out in this way. The ignition time is 60s~120s, and the ignition negative pressure is 4000Pa~6000Pa.

[0014] The technical problem to be solved by the present invention can also be achieved by the following technical solution: In the above-mentioned iron ore sintering ignition method based on blast furnace hot air, in step (1), the induced draft pipe is covered with a ceramic fiber insulation layer.

[0015] The technical problem to be solved by the present invention can also be achieved through the following technical solution: In the above-described iron ore sintering ignition method based on blast furnace hot air, the proportion of the mixed air in step (2) is determined by the following formula: r = (T h -T m ) / (T m -T c ); Where r is the blending ratio, T h T represents the real-time temperature of the high-grade oxygen-enriched hot air in step (1). m For the target ignition temperature, T c This represents the real-time temperature of the air.

[0016] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the iron ore sintering ignition method based on blast furnace hot air described above, wherein an air mixing pipeline is connected to the outer wall of the induced draft pipe, and an electric regulating valve and a temperature sensor are installed in both the air mixing pipeline and the induced draft pipe.

[0017] The technical problem to be solved by the present invention can also be achieved by the following technical solution: In the above-mentioned iron ore sintering ignition method based on blast furnace hot air, in step (4), the nozzle is a slit nozzle with a slit width of 10mm~15mm.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are: (1) This invention directly utilizes the high temperature and oxygen-enriched hot air of the blast furnace hot blast stove, completely eliminating the combustion of gas, fundamentally eliminating the Bourdor reaction caused by the consumption of oxygen and the generation of high concentrations of CO2 by the combustion of gas, so that solid fuel can be fully burned in an oxygen-enriched atmosphere, and the utilization rate is significantly improved. (2) Since no gas is used, this method completely eliminates the direct carbon dioxide emissions generated by the combustion of gas in the sintering ignition process; at the same time, due to the reduction of solid fuel consumption, the carbon emissions used to produce solid fuel are indirectly reduced. On the one hand, it provides an effective technical path for steel enterprises to achieve green and low-carbon production, and on the other hand, it ensures that the surface ignition of the sintered material is uniform and sufficient, forming a high-quality combustion layer. (3) The core heat source of this method comes from the existing facilities in the steel plant - the hot blast stove of the blast furnace. There is no need to invest in the construction of new heating furnaces or electric heating systems. The conveying system can use insulated pipes and existing nozzles. The temperature can be flexibly adjusted by adding air. The system has a high degree of integration and is easy to implement. It is very suitable for low-cost energy-saving transformation of existing sintering production lines. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0020] The specific technical solutions of the present invention will be further described below with reference to the accompanying drawings, so as to enable those skilled in the art to further understand the present invention, without constituting a limitation on its rights.

[0021] Example 1, referring to Figure 1 A method for igniting iron ore sintering based on blast furnace hot blast, the steps of which are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine. The induced draft pipe is covered with a ceramic fiber insulation layer and is used to induced draft for the high-grade oxygen-enriched hot air after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot air is 1100℃, the oxygen content is 23%, and the carbon dioxide concentration is 1%. (2) The high-grade oxygen-enriched hot air is transported to the ignition section of the sintering machine through the duct, and the temperature of the hot air is adjusted to the target ignition temperature by mixing in air. The volumetric flow rate of the mixed air accounts for 30% of the volumetric flow rate of the high-grade oxygen-enriched hot air in the duct. Specifically, the proportion of the mixed air is determined by the formula r = (T h -T m ) / (T m -T c The determination is made by ), where r is the blending ratio and T is the blending ratio. h T represents the real-time temperature of the high-grade oxygen-enriched hot air in step (1). m For the target ignition temperature, T cThe real-time temperature of the air is 700°C. An air mixing pipeline is connected to the outer wall of the exhaust pipe. Both the air mixing pipeline and the exhaust pipe are equipped with electric regulating valves and temperature sensors. (3) By segregating the material, the solid fuel ratio within a 30mm thickness range on the surface of the sintered mixture is increased by 2% compared to the average fuel ratio of the material layer; (4) The hot air after temperature adjustment passes through the nozzle on the ignition cover of the sintering machine. The nozzle is a slit nozzle with a slit width of 10 mm. The nozzle is arranged in parallel along the width direction of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering trolley. The spray wind speed is 5 m / s, and ignition is performed in this way. The ignition time is 60 s and the ignition negative pressure is 4000 Pa.

[0022] Example 2, refer to Figure 1 A method for igniting iron ore sintering based on blast furnace hot blast, the steps of which are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine. The induced draft pipe is covered with a ceramic fiber insulation layer and is used to induced draft for the high-grade oxygen-enriched hot air after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot air is 1300℃, the oxygen content is 25%, and the carbon dioxide concentration is 1.5%. (2) The high-grade oxygen-enriched hot air is transported to the ignition section of the sintering machine through an exhaust duct, and the temperature of the hot air is adjusted to the target ignition temperature by mixing in air. The volumetric flow rate of the mixed air accounts for 70% of the volumetric flow rate of the high-grade oxygen-enriched hot air in the exhaust duct. Specifically, the proportion of the mixed air is determined by the formula r = (T h -T m ) / (T m -T c The determination is made by ), where r is the blending ratio and T is the blending ratio. h T represents the real-time temperature of the high-grade oxygen-enriched hot air in step (1). m For the target ignition temperature, T c The real-time temperature of the air is 1000℃. An air mixing pipeline is connected to the outer wall of the exhaust pipe. Both the air mixing pipeline and the exhaust pipe are equipped with electric regulating valves and temperature sensors. (3) By segregating the material, the solid fuel ratio within the 80mm thickness range of the sintered mixture surface layer is increased by 3% compared to the average fuel ratio of the material layer; (4) The hot air after temperature adjustment passes through the nozzle on the ignition cover of the sintering machine. The nozzle is a slit nozzle with a slit width of 15mm. The nozzle is arranged in parallel along the width direction of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering trolley. The spray wind speed is 15m / s, and ignition is performed in this way. The ignition time is 120s and the ignition negative pressure is 6000Pa.

[0023] In Examples 1-2, this method eliminates the use of any gas, thereby improving fuel utilization and directly reducing solid fuel consumption by promoting complete combustion of solid fuels. Furthermore, by completely eliminating gas combustion, it directly eliminates carbon dioxide emissions generated during the ignition process, achieving emission reduction at the source and combining economic and environmental benefits.

[0024] Example 3: A method for igniting iron ore sintering based on blast furnace hot blast, the steps of which are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine. The induced draft pipe is covered with a ceramic fiber insulation layer and is used to induced draft for the high-grade oxygen-enriched hot air after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot air is 1200℃, the oxygen content is 21%, and the carbon dioxide concentration is 1%. (2) The high-grade oxygen-enriched hot air is delivered to the ignition section of the sintering machine through the exhaust pipe, and the temperature of the hot air is adjusted to the target ignition temperature by mixing with air. The exhaust pipe is equipped with an electric regulating valve and a temperature sensor. (3) The hot air after temperature adjustment passes through the nozzle on the ignition cover of the sintering machine. The nozzle is a slit nozzle with a slit width of 10 mm. The nozzle is arranged in parallel along the width direction of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering trolley. The spray wind speed is 10 m / s, and ignition is performed in this way. The ignition time is 100 s and the ignition negative pressure is 5000 Pa.

[0025] In Example 3, high-grade oxygen-enriched hot air directly drawn from the hot blast stove was used for ignition. Compared with the traditional method of using coke oven gas for ignition, the solid fuel consumption was reduced from 49.3 kg / t to 44.6 kg / t, CO2 emissions were reduced by about 5.8 kg / t, CO emissions were reduced by about 5.6 kg / t, and the sinter drum index was increased by 0.5 percentage points.

[0026] Example 4: A method for igniting iron ore sintering based on blast furnace hot blast, the steps of which are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine. The induced draft pipe is covered with a ceramic fiber insulation layer and is used to induced draft for the high-grade oxygen-enriched hot air after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot air is 1200℃, the oxygen content is 21%, and the carbon dioxide concentration is 1%. (2) The high-grade oxygen-enriched hot air is delivered to the ignition section of the sintering machine through the exhaust pipe, and the temperature of the hot air is adjusted to the target ignition temperature by mixing with air. The exhaust pipe is equipped with an electric regulating valve and a temperature sensor. (3) By segregating the material, the solid fuel ratio within the 80mm thickness range of the sintered mixture surface layer is increased by 3% compared to the average fuel ratio of the material layer; (4) The hot air after temperature adjustment passes through the nozzle on the ignition cover of the sintering machine. The nozzle is a slit nozzle with a slit width of 10 mm. The nozzle is arranged in parallel along the width direction of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering trolley. The spray wind speed is 10 m / s. Ignition is carried out in this way. The ignition time is 100 s and the ignition negative pressure is 5000 Pa.

[0027] In Example 3, high-grade oxygen-enriched hot air directly drawn from the hot blast stove was used for ignition, and segregation feeding was additionally employed. Through segregation feeding, the solid fuel ratio within the 80mm thickness of the sintering mixture surface layer was increased by 3% compared to the average fuel ratio of the material layer. Compared with the effect of traditional coke oven gas ignition, solid fuel consumption was reduced from 49.3kg / t to 37.1kg / t, CO2 emissions were reduced by approximately 22kg / t, CO emissions were reduced by approximately 9.5kg / t, and the sinter drum index was increased by 3.0 percentage points.

[0028] Example 5: A method for igniting iron ore sintering based on blast furnace hot blast, the steps of which are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine. The induced draft pipe is covered with a ceramic fiber insulation layer and is used to induced draft for the high-grade oxygen-enriched hot air after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot air is 1200℃, the oxygen content is 21%, and the carbon dioxide concentration is 1%. (2) The high-grade oxygen-enriched hot air is delivered to the ignition section of the sintering machine through the exhaust duct, and the temperature of the hot air is adjusted to the target ignition temperature by mixing with air. The volumetric flow rate of the mixed air accounts for 50% of the volumetric flow rate of the high-grade oxygen-enriched hot air in the exhaust duct. An air mixing pipeline is connected to the outer wall of the exhaust duct. Both the air mixing pipeline and the exhaust duct are equipped with electric regulating valves and temperature sensors. (2) The high-grade oxygen-enriched hot air is delivered to the ignition section of the sintering machine through the exhaust pipe, and the temperature of the hot air is adjusted to the target ignition temperature by mixing with air. The exhaust pipe is equipped with an electric regulating valve and a temperature sensor. (3) By segregating the material, the solid fuel ratio within the 80mm thickness range of the sintered mixture surface layer is increased by 3% compared to the average fuel ratio of the material layer; (4) The hot air after temperature adjustment passes through the nozzle on the ignition cover of the sintering machine. The nozzle is a slit nozzle with a slit width of 10 mm. The nozzle is arranged in parallel along the width direction of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering trolley. The spray wind speed is 10 m / s. Ignition is carried out in this way. The ignition time is 100 s and the ignition negative pressure is 5000 Pa.

[0029] In Example 5, high-grade oxygen-enriched hot air directly drawn from the hot blast stove was used for ignition, and segregation feeding was additionally employed. Through segregation feeding, the solid fuel ratio within the 80mm thickness of the sintering mixture surface layer was increased by 3% compared to the average fuel ratio of the material layer. Furthermore, air with a volumetric flow rate of 50% was mixed in during the induced draft process. Compared with the effect of traditional coke oven gas ignition, solid fuel consumption was reduced from 49.3kg / t to 36.1kg / t, CO2 emissions were reduced by approximately 25kg / t, CO emissions were reduced by approximately 11.5kg / t, and the sinter drum index was increased by 3.7 percentage points.

Claims

1. A method for igniting iron ore sintering based on blast furnace hot blast, characterized in that, The steps are as follows: (1) An induced draft pipe is installed between the hot blast stove and the sintering machine to induced draft of the high-grade oxygen-enriched hot blast after the blast furnace blast heating task is completed in the hot blast stove. The temperature of the high-grade oxygen-enriched hot blast is 1100℃~1300℃, the oxygen content is 23%~25%, and the carbon dioxide concentration is 1%~1.5%. (2) The high-grade oxygen-enriched hot air is transported to the ignition section of the sintering machine through the duct, and the hot air temperature is adjusted to the target ignition temperature by mixing with air. The volume flow rate of the mixed air accounts for 30% to 70% of the volume flow rate of the high-grade oxygen-enriched hot air in the duct. The target ignition temperature is 700℃ to 1000℃. (3) By segregating the material, the solid fuel ratio in the 30mm~80mm thickness range of the sintered mixture surface layer is increased by 2%~3% compared with the average fuel ratio of the material layer; (4) The hot air after temperature adjustment passes through the nozzles on the ignition cover of the sintering machine. The nozzles are arranged in parallel along the width of the sintering trolley and sprayed vertically onto the surface of the sintering mixture on the sintering machine trolley. The spray wind speed is 5~15m / s, and ignition is carried out in this way. The ignition time is 60s~120s, and the ignition negative pressure is 4000Pa~6000Pa.

2. The iron ore sintering ignition method based on blast furnace hot blast according to claim 1, characterized in that, In step (1), the air duct is covered with a ceramic fiber insulation layer.

3. The iron ore sintering ignition method based on blast furnace hot blast according to claim 1, characterized in that, In step (2), the proportion of the mixed air is determined by the following formula: r = (T h -T m ) / (T m -T c ); Where r is the blending ratio, T h T represents the real-time temperature of the high-grade oxygen-enriched hot air in step (1). m For the target ignition temperature, T c This represents the real-time temperature of the air.

4. The iron ore sintering ignition method based on blast furnace hot blast according to claim 1, characterized in that: An air mixing pipe is connected to the outer wall of the exhaust duct, and both the air mixing pipe and the exhaust duct are equipped with an electric regulating valve and a temperature sensor.

5. The iron ore sintering ignition method based on blast furnace hot blast according to claim 1, characterized in that: In step (4), the nozzle is a slit nozzle with a slit width of 10mm to 15mm.

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