Method and system for measuring reducibility of iron ore under hydrogen-rich smelting condition of blast furnace

Abstract

The invention relates to the field of blast furnace ironmaking processes, in particular to a method and a system for measuring reducibility of iron ore under a blast furnace hydrogen-rich smelting condition, an iron ore sample is placed in a high-pressure reaction tube to be heated to a set temperature and kept constant for a set time, then the iron ore sample is switched into hydrogen-rich mixed gas, and the pressure is increased to a set pressure for a reaction; the reaction temperature in the high-pressure reaction tube is monitored in real time, the content of water vapor in tail gas generated in the reaction process is monitored through an online gas analyzer, and the reduction degree is calculated; after the reaction is finished, inert gas cooling is switched, and an iron ore sample is taken out and weighed; and drawing a reduction degree-time curve, and calculating a reduction rate constant. The experimental device has the advantages that through the design of the multi-component dynamic gas distribution system and the high-pressure reaction tube, the hydrogen-rich mixed gas, the high-pressure environment (95-300KPa) and the high-temperature condition of the hydrogen-rich smelting (including pure hydrogen smelting) of the blast furnace can be accurately simulated in the laboratory environment for the first time, and the technical blank that the traditional equipment cannot simulate the high-hydrogen-content working condition is filled.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and in particular to a method and system for determining the reducibility of iron ore under hydrogen-rich blast furnace smelting conditions. Background Technology

[0002] The steel industry is a vital foundation of the national economy, but it is also a major contributor to energy consumption and carbon emissions. Against the backdrop of global green and low-carbon development, hydrogen-rich blast furnace smelting technology has become one of the core directions for the steel industry to achieve energy conservation, carbon reduction, and green transformation. The development and optimization of related processes are currently in a critical stage of industrial testing and widespread application.

[0003] Currently, the standard method for determining the reducibility of iron ore is mainly based on the international standard ISO 4695, and adopts... A mixed gas is used as a reducing agent, and weight loss is measured at atmospheric pressure and a fixed temperature. However, this traditional method has the following significant limitations: 1. Insufficient adaptability to different atmospheres: Existing equipment cannot simulate the complex atmosphere in hydrogen-rich blast furnace smelting where the hydrogen gas fraction is as high as 30% to 70%, and it especially lacks the ability to simulate the complex atmosphere. The ability to regulate dynamic changes in components. Water vapor produced by hydrogen reduction ( This will have an inhibitory effect on subsequent reduction reactions, which traditional devices cannot achieve. Real-time adjustment and stable control of the ratio; 2. Distortion of thermodynamic and kinetic conditions: The reduction of iron oxides by hydrogen is a strongly endothermic reaction, leading to unstable temperature in the reaction system. Traditional isothermal control methods are insufficient to maintain an isothermal environment, resulting in deviations in reduction kinetic data. Furthermore, the high diffusion rate and mass transfer characteristics of hydrogen differ fundamentally from those of traditional CO reduction, making it impossible for existing equipment to accurately reflect the reduction behavior under hydrogen-rich conditions. 3. Lack of high-pressure environment: In actual operation, the top pressure of a hydrogen-rich blast furnace is typically between 95 and 180 kPa, while the blast pressure is typically between 200 and 300 kPa. Pressure selection must consider the reduction rate, smooth furnace operation, and equipment capacity. Higher top pressure is preferable when the hydrogen content increases to reduce pressure drop and stabilize the gas flow. However, existing measuring devices mostly operate at atmospheric pressure and lack high-pressure sealing, explosion-proof, and safety control functions, making it impossible to simulate the gas-solid reaction process under real pressure conditions. 4. Measurement method error: Under high pressure, the main source of error in the traditional weight loss method for measuring the reduction rate of hydrogen-rich sinter comes from... Interference from reduction products, the influence of thermal effects, distortion of experimental conditions, and weighing errors can cause results to deviate from actual values. The higher the hydrogen-rich ratio, the better. The more significant the impact on reduction and thermal effects, especially under high top pressure and high hydrogen-rich conditions, the greater the deviation will be. However, current technologies lack alternative online detection methods suitable for high-pressure environments. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for determining the reducibility of iron ore under hydrogen-rich blast furnace smelting conditions. This method can simulate the hydrogen-rich blast furnace smelting atmosphere, has high pressure and high temperature adaptability, supports dynamic control of multi-component gases and online reducibility monitoring, and enhances its application value in promoting the development and optimization of hydrogen-rich blast furnace smelting processes.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for determining the reducibility of iron ore under hydrogen-rich blast furnace smelting conditions includes: The iron ore sample was placed in a high-pressure reaction tube, and inert gas was introduced to purge the air. After heating to the set temperature of 900~950℃ and holding it at that temperature for half an hour, switch to a hydrogen-rich mixed gas, pressurize the gas pressure at 100~180KPa, and react for 3 hours. In a hydrogen-rich gas mixture, , And accounting for 40% of the hydrogen-rich gas mixture, It accounts for 55% of the hydrogen-rich gas mixture. It accounts for 5% of the hydrogen-rich gas mixture; The reaction temperature in the high-pressure reaction tube is monitored in real time, and the water vapor content in the tail gas generated during the reaction is monitored by an online gas analyzer to calculate the degree of reduction. After the reaction is complete, switch to inert gas cooling, remove the iron ore sample and weigh it; Plot the degree of reduction versus time curve and calculate the reduction rate constant.

[0006] In hydrogen-rich gas mixture The ratio can be steplessly adjusted between 0% and 100%.

[0007] The degree of fidelity is calculated using the following formula: ①; In formula ①, This indicates the change in the amount of water produced in the reaction, and 56 represents the molar mass of iron. This represents the total mass of iron in the sample, and 18 represents the molar mass of water. Indicates the degree of fidelity.

[0008] The exhaust gas includes a mixture of gases exiting from the high-pressure reaction tube outlet, containing unreacted gases. , , and the products of the reaction gas.

[0009] The reduction rate constant is given by the following formula: ②; In formula ②, Indicates reaction time. dR / dt represents the slope of the redistribution-time curve over time t, and dR / dt represents the redistribution R versus time. The instantaneous rate of change is used to characterize the reduction reaction rate of iron ore under hydrogen-rich conditions.

[0010] A system for determining the reducibility of iron ore under hydrogen-rich blast furnace smelting conditions includes a high-pressure reaction tube, a dual-zone heating furnace, a steam generator, a mass flow controller, and an online gas analyzer. The high-pressure reaction tube is made of a high-pressure and corrosion-resistant alloy and is used to hold iron ore samples and provide a high-temperature and high-pressure reaction environment. The heating furnace is a dual-zone heating furnace, located in the gas inlet section and sample reaction section of the high-pressure reaction tube respectively. It is used to adjust the temperature of the gas inlet section and sample reaction section of the high-pressure reaction tube respectively, to preheat the hydrogen-rich mixed gas introduced, and to provide real-time heat compensation for the temperature drop caused by the endothermic hydrogen reduction reaction during the iron ore reduction reaction. The steam generator employs either the bubbling method or the steam permeation membrane method, with an adjustable steam concentration range of 5-30 vol%. The mass flow controller is used to adjust the proportion of the hydrogen-rich gas mixture leading to the high-pressure reactor; For online gas analyzers, choose laser-based online gas analyzers.

[0011] The gas inlet section is the area where gas enters from the front end of the high-pressure reaction tube, mainly used for preheating the gas. The sample reaction section is the area in the middle of the high-pressure reaction tube where the iron ore sample is placed, mainly used to maintain the reaction temperature.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. Through the design of a multi-component dynamic gas distribution system and a high-pressure reaction tube, it is the first time that the hydrogen-rich mixed gas, high-pressure environment (95~300KPa) and high-temperature conditions of hydrogen-rich blast furnace smelting (including pure hydrogen smelting) can be accurately simulated in a laboratory environment, filling the technical gap that traditional equipment cannot simulate high hydrogen content working conditions. 2. Real-time monitoring using an online gas analyzer The method generates quantities and calculates the degree of reduction, completely avoiding measurement errors caused by buoyancy effects in the weightlessness method under high pressure, making the degree of reduction data more accurate and reliable. 3. The dual-zone heating furnace can dynamically compensate for the temperature drop caused by the strong endothermic reaction of hydrogen reduction, maintain the constant temperature of the reaction zone, eliminate the interference of temperature fluctuations on the reduction kinetic data, and obtain a more realistic reaction rate constant (k value). 4. Integrated high-pressure explosion-proof design, using thick-walled Inconel 625 alloy reaction tube and "self-sealing thread + graphite gasket" end structure to ensure the sealing reliability and explosion-proof safety of the system under high pressure conditions of 95~300KPa; 5. In the reduction reaction of iron ore under hydrogen-rich smelting conditions in a blast furnace, water vapor can mix with hydrogen in a set ratio to simulate the actual gaseous environment inside the blast furnace, improving the authenticity and applicability of the reducibility test results. Under high-temperature conditions, water vapor can indirectly reduce iron ore through a reaction, affecting the progress and overall efficiency of the reduction process. The introduction of water vapor will change the density and viscosity of the reactant gases, thus affecting the reducing gases (such as...). The diffusion rate of CO between iron ore particles further interferes with the kinetics of the reduction reaction, making the measurement results more reflective of the reduction performance under actual mass transfer conditions. Attached Figure Description

[0013] Figure 1 This is a diagram of a system for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace.

[0014] In the diagram: 1. Dual-zone heating furnace; 2. High-pressure reaction tube; 3. Mass flow controller; 4. Steam generator; 5. Thermocouple temperature sensor; 6. Frame; 7. Vertical support; 8. High-pressure reaction tube support; 9. Lifting device; 10. Online gas analyzer; 11. Gas mixer. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0016] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0017] Example 1 See Figure 1A system for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace includes a frame structure, a high-pressure reaction tube 2, a thermal compensation module, a dynamic gas distribution system, an online gas analyzer 10, and a thermocouple temperature sensor 5. The frame structure supports and fixes the components in the system and assists in completing experimental operations and the safe movement of the high-pressure reaction tube 2. The frame structure includes a lifting device 9, a frame 6, and a vertical support 7 installed at one end of the frame 6. The frame 6 is fixedly connected to the high-pressure reaction tube support 8. During the experiment, the high-pressure reaction tube 2 is placed inside the thermal compensation module, which is fixedly connected to the frame 6. The vertical support 7 is equipped with the lifting device 9, which is controlled by an electric arc furnace lifting mechanism. After the experiment, the lifting device 9 lifts the high-pressure reaction tube 2 through the hook below, detaching it from the thermal compensation module and transferring it to the high-pressure reaction tube support 8 for cooling. The next step of the experiment can only be carried out after the temperature of the high-pressure reaction tube 2 drops below 100°C. This system can simulate the hydrogen-rich smelting environment of a blast furnace (high hydrogen content, high pressure, high temperature, and multi-component reducing gas), enabling dynamic determination of the reducibility of iron ore. This makes the detection of the medium-temperature reduction performance of iron ore under hydrogen-rich smelting conditions in a safer, lower-consumption, faster, and more accurate manner. The high-pressure reaction tube 2 is used to hold the iron ore sample and provide a high-temperature, high-pressure reaction environment. It is made of high-pressure resistant and corrosion-resistant alloy (such as Inconel 625) material, featuring a hydrogen-proof lining and a self-sealing structure. One end uses a "self-sealing thread + graphite gasket" structure. The thread has a conical or spherical sealing structure. When tightened, the graphite gasket (high-temperature and high-pressure resistant) is compressed, tightly sealing the tube end and connectors, enhancing overall sealing. This, combined with the end seal of the hydrogen-proof lining, forms a double leak-proof system. The thermal compensation module uses a heating furnace, which is a dual-zone furnace with two independent heating areas located at the gas inlet section and the sample reaction section of the high-pressure reaction tube 2, respectively. This allows for the separate adjustment of the temperatures in the gas inlet section and the sample reaction section of the high-pressure reaction tube 2 to control the temperature of the introduced hydrogen-rich mixed gas (which includes…). The process involves preheating and real-time heat compensation for the temperature drop caused by the endothermic hydrogen reduction reaction during the iron ore reduction reaction. The gas inlet section is where the gas enters from the front end of the high-pressure reaction tube 2, primarily for preheating the gas. The sample reaction section is the area in the middle of the high-pressure reaction tube 2 where the iron ore sample is placed, primarily for maintaining the reaction temperature. The dual-zone heating furnace 1 uses a PID upper and lower limit adaptive control method for adjustment: the real-time monitored reaction temperature inside the high-pressure reaction tube 2 is compared with the set temperature to obtain the deviation. According to the deviation The range of the PID controller adjusts the upper and lower limits of the heating furnace temperature; the thermocouple temperature sensor 5 is used to monitor the reaction temperature in the high-pressure reaction tube 2 in real time. The dynamic gas distribution system includes a steam generator 4 and a mass flow controller 3. The mass flow controller 3 is a gas mass flow controller used to adjust the proportion of hydrogen-rich mixed gas leading to the high-pressure reaction tube 2, with an adjustment accuracy of [insert accuracy here]. The steam generator 4 employs either bubbling or steam permeation membrane methods, and the steam concentration is adjustable within a certain range. Both types of generators can stably produce water vapor, but the bubbling method emphasizes simplicity, while the vapor permeation membrane method emphasizes purity and selectivity.

[0018] A laser-based online gas analyzer was selected for real-time detection of exhaust gases. Concentration, response time <1s.

[0019] A method for determining the reducibility of iron ore under hydrogen-rich blast furnace smelting conditions includes: S1. Place iron ore with a particle size of 10~12.5mm (ISO4701 standard) in a high-pressure reaction tube, heat to 105℃, and introduce... Purge the reaction tube to remove air; S2. After heating to 900-950℃ and holding at that temperature for half an hour, switch to a hydrogen-rich mixed gas and pressurize to 100-180 kPa for a reaction time of 3 hours; in the hydrogen-rich mixed gas... The ratio can be steplessly adjusted between 1% and 100%, that is, by dynamically controlling the flow rate ratio of the gas source, and combining it with an online analysis and feedback system for real-time correction (dynamic flow rate ratio method), controlled by a mass flow controller. The inlet flow rates of both CO and other gases will affect the output of the mass flow controller. CO passes through gas mixer 11.

[0020] Mix thoroughly according to the target ratio, and install an online gas analyzer at the outlet of the mixed gas for real-time monitoring. The concentration of CO is measured, and the detection data from the online gas analyzer is fed back to the host computer for comparison with the set target ratio. The flow parameters of the mass flow controller are automatically corrected to achieve dynamic compensation of the ratio and simulate the transition condition between hydrogen-rich and pure hydrogen.

[0021] S3. Real-time monitoring of the reaction temperature in the high-pressure reaction tube, and monitoring of the water vapor content in the exhaust gas generated during the reaction process using an online gas analyzer. The exhaust gas includes a gas mixture discharged from the outlet of the high-pressure reaction tube, containing unreacted gas. and the products of the reaction For gases, the reduction degree is calculated using the following formula: ①; The principle of Formula ①: It indirectly calculates the iron reduction rate by using the "amount of water produced." It utilizes the stoichiometric relationship of the "amount of water produced" in the reduction reaction of iron oxides to convert the easily detectable change in the amount of water into the "iron reduction ratio." This indicates the change in the amount of water produced in the reaction. The amount of water generated in the experiment was calculated; 56 represents the molar mass of iron. This indicates the total mass of iron in the sample, including both unreduced and reduced iron, and is usually determined from the raw material composition before the experiment; 18 represents the molar mass of water. Indicates the degree of fidelity.

[0022] S4. After the reaction is complete, switch to inert gas cooling, take out the iron ore sample and weigh it; S5. Plot the degree of restoration versus time curve and calculate the restoration rate constant using the following formula: ②; In formula ②, Indicates reaction time. dR / dt represents the reduction rate constant, and dR / dt represents the degree of reduction R with respect to time. The instantaneous rate of change is used to characterize the reduction reaction rate of iron ore under hydrogen-rich conditions.

[0023] This invention, through a multi-component dynamic gas distribution system and high-pressure reaction tube design, is the first to accurately simulate the hydrogen-rich mixed gas, high-pressure environment (95~300KPa), and high-temperature conditions of hydrogen-rich blast furnace smelting (including pure hydrogen smelting) in a laboratory environment, filling the technological gap that traditional equipment cannot simulate high-hydrogen content operating conditions; and employs an online gas analyzer for real-time monitoring. The method generates and calculates the degree of reduction, completely avoiding measurement errors caused by buoyancy effects in the weightlessness method under high pressure, making the degree of reduction data more accurate and reliable. A dual-zone heating furnace is used to dynamically compensate for the temperature drop caused by the strong endothermic reaction of hydrogen reduction, maintaining a constant temperature in the reaction zone and eliminating the interference of temperature fluctuations on reduction kinetic data, thus obtaining a more realistic reaction rate constant (k value). An integrated high-pressure explosion-proof design, using thick-walled Inconel 625 alloy reaction tubes and a "self-sealing thread + graphite gasket" end structure, ensures the sealing reliability and explosion-proof safety of the system under high pressure conditions of 95~300KPa. In the iron ore reduction reaction under hydrogen-rich smelting conditions in a blast furnace, water vapor can mix with hydrogen in a set ratio to simulate the actual gas phase environment inside the blast furnace, improving the authenticity and applicability of the reducibility measurement results. Under high-temperature conditions, water vapor can indirectly reduce iron ore through a reaction, affecting the progress and overall efficiency of the reduction process. The introduction of water vapor changes the density and viscosity of the reactant gases, thus affecting the reducing gases (such as...). The diffusion rate of CO between iron ore particles further interferes with the kinetics of the reduction reaction, making the measurement results more reflective of the reduction performance under actual mass transfer conditions.

Claims

1. A method for determining the reducibility of iron ore under hydrogen-rich blast furnace smelting conditions, characterized in that, include: The iron ore sample was placed in a high-pressure reaction tube, and inert gas was introduced to purge the air. After heating to the set temperature of 900~950℃ and holding it at that temperature for half an hour, switch to a hydrogen-rich mixed gas, pressurize the gas pressure at 100~180KPa, and react for 3 hours. In a hydrogen-rich gas mixture, , And accounting for 40% of the hydrogen-rich gas mixture, It accounts for 55% of the hydrogen-rich gas mixture. It accounts for 5% of the hydrogen-rich gas mixture; The reaction temperature in the high-pressure reaction tube is monitored in real time, and the water vapor content in the tail gas generated during the reaction is monitored by an online gas analyzer to calculate the degree of reduction. After the reaction is complete, switch to inert gas cooling, remove the iron ore sample and weigh it; Plot the degree of reduction versus time curve and calculate the reduction rate constant.

2. The method for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace according to claim 1, characterized in that, The hydrogen-rich mixed gas The ratio can be steplessly adjusted between 0% and 100%.

3. The method for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace according to claim 1, characterized in that, The degree of reduction is given by the following formula: ①； In formula ①, This indicates the change in the amount of water produced in the reaction, and 56 represents the molar mass of iron. This represents the total mass of iron in the sample, and 18 represents the molar mass of water. Indicates the degree of fidelity.

4. The method for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace according to claim 1, characterized in that, The exhaust gas includes a gas mixture discharged from the outlet of the high-pressure reaction tube, containing unreacted gas. and the products of the reaction gas.

5. The method for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace according to claim 1, characterized in that, The reduction rate constant is given by the following formula: ②； In formula ②, Indicates reaction time. This represents the slope of the redistribution-time curve within the time segment t. The degree of reduction R is expressed as a function of time. The instantaneous rate of change is used to characterize the reduction reaction rate of iron ore under hydrogen-rich conditions.

6. A system for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace, implementing the method described in claims 1-5, characterized in that, Includes high-pressure reaction tubes, dual-zone heating furnace, steam generator, mass flow controller, and online gas analyzer; The high-pressure reaction tube is made of a high-pressure and corrosion-resistant alloy and is used to hold iron ore samples and provide a high-temperature and high-pressure reaction environment. The heating furnace is a dual-zone heating furnace, located in the gas inlet section and sample reaction section of the high-pressure reaction tube respectively. It is used to adjust the temperature of the gas inlet section and sample reaction section of the high-pressure reaction tube respectively, to preheat the hydrogen-rich mixed gas introduced, and to provide real-time heat compensation for the temperature drop caused by the endothermic hydrogen reduction reaction during the iron ore reduction reaction. The steam generator employs either the bubbling method or the steam permeation membrane method, and the steam concentration is adjustable within a certain range. ; The mass flow controller is used to adjust the proportion of the hydrogen-rich gas mixture leading to the high-pressure reactor; For online gas analyzers, choose laser-based online gas analyzers.

7. The system for determining the reducibility of iron ore under hydrogen-rich smelting conditions in a blast furnace according to claim 6, characterized in that, The gas inlet section is the area where gas enters at the front end of the high-pressure reaction tube, mainly used for preheating the gas. The sample reaction section is the area in the middle of the high-pressure reaction tube where the iron ore sample is placed, mainly used to maintain the reaction temperature.

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