Hydrogen-based flash ironmaking reaction kinetics experimental device and method

Abstract

The invention discloses a hydrogen-based flash ironmaking reaction kinetics experimental device and method, and the experimental device comprises a vertical high-temperature tube furnace lifting mechanism, a bottom buffer speed reduction mechanism, a gas supply system, a feeding device, a cold quenching device, a temperature controller, a laser displacement sensor, an acceleration sensor and a computer; the vertical high-temperature tube furnace lifting mechanism comprises a base, a vertical guide rail bracket, a guide rail, a sliding block, a vertical high-temperature tube furnace, a pull rope, a pulley block and an electric capstan; the bottom buffer speed reducing mechanism comprises a spring; the gas supply system comprises a reducing gas supply system and an inert gas supply system, and the feeding device is a piezoelectric driving type feeding machine; the cold quenching device comprises a cold quenching device body, an electronic refrigeration sheet and a refrigeration sheet controller. By accurately controlling the vertical high-temperature tube furnace to descend at constant acceleration, a low-gravity environment is created in the furnace, the relative descending speed of iron ore powder particles in the furnace is changed, and the descending time of the iron ore powder particles is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical engineering, and in particular to a hydrogen-based flash ironmaking reaction kinetics experimental device and method. Background Art

[0002] At present, hydrogen-based flash ironmaking, as a new type of pyrometallurgical ironmaking process that does not require carbonaceous reducing agents and fuels, has become a green and low-carbon smelting technology that has attracted much attention. Hydrogen-based flash ironmaking technology uses a flash furnace. The mineral particles are heated in the reaction tower and come into contact with hydrogen to produce a gas-solid reduction reaction.

[0003] The hydrogen-based flash ironmaking reduction experiment based on a small-scale experimental flash furnace or a vertical high-temperature tubular furnace is the main experimental means to explore the reduction rate of iron ore powder particles. During the experiment, the iron ore powder particles fall freely from the top to the bottom in the furnace, and react with reducing gases such as H2 in the furnace tube. The length of the reaction time is directly affected by the size of the furnace tube: for mineral iron ore powder particles with a particle size of 75um-150um, a furnace tube of up to 3 to 6 meters is often required to ensure that the iron ore powder particles have a reaction descent time of about 2s in the furnace. The use of 3 to 6-meter furnace tubes has problems such as large design size, high energy consumption of the heating module, and high price, which restricts the in-depth study of the reduction kinetics of hydrogen-based flash ironmaking. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a hydrogen-based flash ironmaking reaction kinetics experimental device and method.

[0005] The technical solution of the present invention to solve the above problems is:

[0006] A hydrogen-based flash ironmaking reaction kinetics experimental device comprises: a vertical high-temperature tubular furnace lifting mechanism, a bottom buffer deceleration mechanism, a gas supply system, a feeding device, a quencher, a temperature controller, a laser displacement sensor, an acceleration sensor and a computer; wherein;

[0007] The vertical high-temperature tube furnace lifting mechanism comprises a base, a vertical guide rail bracket, a guide rail, a slider, a vertical high-temperature tube furnace, a pull rope, a pulley block and an electric winch. Vertical guide rail brackets are respectively provided on both sides of the base, and guide rails are respectively provided on the inner sides of the vertical guide rail brackets. Both sides of the vertical high-temperature tube furnace are connected to the corresponding guide rails through sliders; a pulley block is provided above the vertical high-temperature tube furnace, and a pull rope is wound on the pulley block, one end of the pull rope is connected to a hook on the vertical high-temperature tube furnace, and the other end is connected to the electric winch;

[0008] The bottom buffer deceleration mechanism includes a spring, which is arranged on the base corresponding to the slider;

[0009] The gas supply system includes a reducing gas supply system and an inert gas supply system, and both the reducing gas supply system and the inert gas supply system include a compressed gas cylinder, a pressure reducer and a mass flow controller, and the compressed gas cylinder is connected to the air inlet of the vertical high-temperature tube furnace through the pressure reducer and the mass flow controller;

[0010] The feeding device is a piezoelectric driven feeding machine, the outlet of the piezoelectric driven feeding machine is connected to the feeding port of the vertical high temperature tube furnace through a vertical metal round tube, and the piezoelectric driven feeding machine rises and falls together with the vertical high temperature tube furnace;

[0011] The quencher includes a quencher body, an electronic refrigeration plate and a refrigeration plate controller. The quencher body is a truncated cone structure that is narrow at the top and wide at the bottom. The quencher body is connected to the outlet of the vertical high-temperature tube furnace through a flange. An electronic refrigeration plate is provided at the bottom of the quencher body, and the electronic refrigeration plate is connected to the refrigeration plate controller.

[0012] The mass flow controller, piezoelectric driven feeder, refrigeration plate controller, temperature controller, laser displacement sensor, acceleration sensor, and electric winch controller are all connected to the computer for communication; the laser displacement sensor is used to measure the position of the vertical high temperature tube furnace, and the acceleration sensor is used to measure the descending acceleration of the vertical high temperature tube furnace.

[0013] Furthermore, the bottom buffer deceleration mechanism also includes permanent magnets, and permanent magnets with opposite polarities are correspondingly arranged on the bottom and the base of the vertical high-temperature tube furnace.

[0014] Furthermore, the maximum release length of the pull rope satisfies that the distance between the quencher body and the base is 10 to 15 cm.

[0015] Furthermore, limit switches are provided at the upper and lower ends of the guide rail, and the limit switches are linked with the electric winch controller. When the vertical high-temperature tube furnace triggers the limit switch, the electric winch stops.

[0016] Furthermore, the mass flow controller is connected to the air inlet of the vertical high-temperature tube furnace through a spring expansion tube.

[0017] Furthermore, a gas outlet is provided on one side of the lower portion of the furnace tube of the vertical high-temperature tube furnace, and the gas outlet is connected to an exhaust gas treatment device.

[0018] Furthermore, a cross grid is provided at the inner bottom of the quencher body.

[0019] Further, the vertical high temperature tube furnace is connected to the temperature controller via a spring cable.

[0020] The present invention also discloses an experimental method of the above-mentioned hydrogen-based flash ironmaking reaction kinetics experimental device, and the specific steps are as follows:

[0021] Step S1: Start: clean the vertical high-temperature tube furnace and check the connection status of each device;

[0022] Step S2: setting experimental parameters, including iron ore powder particle size, heating temperature, gas flow rate and iron ore powder particle addition amount;

[0023] Step S3: placing a quenching medium into the quencher body, and adding screened iron ore powder particles of a specified particle size into the piezoelectric driven feeder;

[0024] Step S4: Install the vertical high-temperature tube furnace in place, connect the top of the furnace tube to a piezoelectric driven feeder, connect the bottom to a cold quencher, check the air tightness of the equipment, evacuate the furnace tube for a leak test, and after the test is completed, control the inert gas supply system through a computer program to introduce inert gas to ensure that the oxygen in the furnace is completely emptied, close the inert gas supply system, clean the surrounding area, and set up metal guardrails to prevent people from entering;

[0025] Step S5: heating the furnace tube to a specified temperature at a rate of 10-20°C / min and keeping the temperature constant, controlling the reducing gas supply system to introduce reducing gas at a flow rate of 0.1-5L / min for at least 30 minutes, ensuring that the furnace tube is completely filled with reducing gas and then closing the furnace tube;

[0026] Step S6: Calculate the longest falling time t of the iron ore powder particles, calculate the control parameters according to the longest falling time t and import them into the electric winch controller. The longest falling time t of the iron ore powder particles is the free fall stage time t1 of the iron ore powder particles before the vertical high-temperature tube furnace drops at a constant acceleration, and the vertical high-temperature tube furnace constant acceleration stage time t w The time of deceleration and stationary stage of vertical high temperature tube furnace t e The sum of t = t1 + t w +t e ;

[0027] Step S7: Calculate the single feeding amount and feeding times according to the feeding amount of the iron ore powder particles;

[0028] Step S8: Raise the vertical high-temperature tube furnace to the high point T, close the gas valve and stop the gas supply;

[0029] Step S9: Control the piezoelectric driven feeder to feed, and the iron ore powder particles fall into the furnace tube through the vertical metal round tube;

[0030] Step S10: When the iron ore powder particles descend to the high temperature zone close to the vertical high temperature tube furnace, the electric winch controller controls the vertical high temperature tube furnace to descend according to the control parameters. The whole descent process is divided into three stages, the first stage is the free fall stage, the second stage is the constant acceleration stage, and the third stage is the deceleration and stationary stage;

[0031] In the second stage, the computer receives the data from the laser displacement sensor and the acceleration sensor and performs real-time analysis. The data processing module of the computer software calculates the current descent acceleration and the target constant acceleration a of the control parameters. w According to the deviation, the PID control algorithm is used to calculate the output adjustment of the electric winch, so as to control the constant acceleration of the high-temperature tube furnace. The target constant acceleration is lower than the gravity acceleration to ensure that the iron ore powder particles can continue to descend relative to the vertical high-temperature tube furnace.

[0032] Step S11: the iron ore powder particles gradually fall into the quencher body. When the iron ore powder particles freely fall to the middle and lower part of the vertical high-temperature tube furnace, the vertical high-temperature tube furnace is in a deceleration and stationary stage. Under the deceleration effect of the pull rope, the permanent magnet and the spring, the vertical high-temperature tube furnace is in a deceleration and descending state until it stops descending. At this time, the vertical high-temperature tube furnace is at a low point B.

[0033] Step S12: Control the reducing gas supply system to introduce reducing gas, and keep it for 3 to 5 minutes, then return to step S8 to repeat the experimental process until the cycle reaches the set number of times and then enter step S13;

[0034] Step S13: controlling the inert gas supply system to introduce inert gas, the vertical high-temperature tube furnace stops working, and the vertical high-temperature tube furnace enters a cooling stage. The entire cooling process lasts for 4 to 6 hours until the vertical high-temperature tube furnace cools to room temperature;

[0035] Step S14: disassembling the quencher body, collecting the cooled reduced iron ore powder particles, and placing them in a nitrogen-protected drying oven for drying; then, testing and analyzing the dried samples;

[0036] Step S15: Whether the conditional experiment is completed, if not, proceed to step S2; if the conditional experiment is completed, proceed to step S16;

[0037] Step S16: Calculate reaction kinetic parameters according to the metallurgical reaction kinetics principle;

[0038] Step S17: End.

[0039] Further, the calculation of the longest falling time t of the iron ore powder particles in step S6 includes the following steps:

[0040] Step S91: The free fall stage of the iron ore powder particles before the vertical high-temperature tube furnace descends at a constant acceleration: calculate the acceleration du of the iron ore powder particles at each moment in this stage t / dt, speed u t and displacement d1. When displacement d1 is greater than the initial displacement D of the iron ore powder particle, s Output the free fall time t1 of the iron ore powder particles in this stage, and the initial displacement D of the iron ore powder particless is the displacement of the iron ore powder particles before the vertical high-temperature tube furnace descends at a constant acceleration;

[0041] Step S92: Vertical high temperature tube furnace constant acceleration stage: Set the initial value of constant acceleration a1 of the vertical high temperature tube furnace, and calculate the acceleration du of the iron ore powder particles at each moment in this stage. w / dt, speed u w And displacement d2, when the vertical high temperature tube furnace reaches the maximum travel distance H, the vertical high temperature tube furnace constant acceleration stage time t is output w ;

[0042] Step S93: vertical high-temperature tube furnace deceleration and stationary stage; calculate the acceleration du of the iron ore powder particles at each moment in this stage e / dt, speed u e and displacement d3, until the iron ore powder particles fall into the bottom of the quencher, output the deceleration and static stage time t of the vertical high-temperature tube furnace in this stage e ; Calculate the total fall time T d ;

[0043] Step S94: Determine the total falling time T d Is it the longest falling time t? If yes, go to step S95; if not, go to step S92 to reset the constant acceleration value of the vertical high-temperature tube furnace;

[0044] Step S95: Determine the descending speed u of the iron ore powder particles in the vertical high-temperature tube furnace at the constant acceleration stage w Is it always greater than the lower limit value U of the iron ore powder particle descent speed in the constant acceleration stage? m If yes, proceed to step S96; if no, proceed to step S92 to reset the constant acceleration value of the vertical high-temperature tube furnace;

[0045] Step S96: Output control parameters.

[0046] Beneficial effects:

[0047] The present invention can control the descent of a vertical high-temperature tube furnace in real time and accurately. By accurately controlling the descent of the vertical high-temperature tube furnace at a constant acceleration, a low-gravity environment is created in the furnace, and the relative descent speed of iron ore powder particles in the furnace is changed, so that iron ore powder particles with a particle size of 75 to 150 um can extend the descent time, and a descent time of more than 2 seconds can be achieved in a 1-meter furnace tube. This not only provides equipment support for low-cost high-temperature hydrogen reduction kinetic experiments, but also provides important technical references for the construction of a theoretical prototype of hydrogen-based flash ironmaking. The experimental device and method can also be applied to the research on particle reaction kinetics of high-temperature flash metallurgical processes of other minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a structural schematic diagram of a preferred embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the structure of a quencher in a preferred embodiment of the present invention;

[0050] Figure 3 It is a diagram of the experimental steps in a preferred embodiment of the present invention;

[0051] Figure 4 A schematic diagram of the lifting of a preferred embodiment of the present invention;

[0052] Figure 5 A diagram showing the steps for calculating control parameters in a preferred embodiment of the present invention;

[0053] Figure 6 : is a comparison diagram of the motion relationship curve of free fall motion only and the motion relationship curve of the present invention in a low gravity environment; wherein A1-A4 are motion relationship curve diagrams of free fall motion only, and B1-B4 are motion relationship curve diagrams of the present invention in a low gravity environment;

[0054] In the figure: vertical high-temperature tube furnace 1, slider 2, hook 3, pull rope 4, split high-power silicon rectifier 5, temperature controller 6, computer 7, spring cable 8, furnace tube 9, piezoelectric driven feeder 10, quencher body 11, flange 12, vertical metal round tube 13, base 14, vertical guide rail bracket 15, guide rail 16, electric winch 17, pulley block 18, permanent magnet 19, spring 20, limit switch 21, compressed gas cylinder 22, pressure reducer 23, mass flow controller 24, spring telescopic tube 25, exhaust gas treatment device 26, laser displacement sensor 27, acceleration sensor 28, electric winch controller 29, electronic refrigeration plate 30, refrigeration plate controller 31. DETAILED DESCRIPTION

[0055] In order to make the technical means, creative features, objectives and effects achieved by the present invention simple and clear, the present invention is further explained below with reference to specific schematic diagrams.

[0056] During the free fall reduction reaction of 75-150um iron ore powder particles in the high-temperature furnace tube 9 of ≤1m, the falling time is <1s. In order to prolong the falling time of iron ore powder particles in the high-temperature furnace tube 9, theoretically, the particle size of iron ore powder can be reduced by p , increase the fluid density ρ g or viscosity μ gHowever, in the hydrogen-based flash ironmaking process, changing the fluid density and viscosity only by increasing the temperature cannot significantly increase the falling time of the iron ore powder particles. In addition, although reducing the particle size of the iron ore powder (such as less than 45 microns) can increase the falling time of the iron ore powder particles in the furnace, this will significantly increase the grinding cost and is not suitable for the requirements of large-scale industrial experiments. Therefore, in order to study the iron reduction degree of larger iron ore powder particles (such as 75-150um) under the condition of a falling time of 2-3s, it is possible to consider constructing low gravity conditions to reduce the falling speed of the iron ore powder particles, thereby effectively extending the falling time of the iron ore powder particles in the furnace tube 9.

[0057] For example, see Figure 1 As shown, a hydrogen-based flash ironmaking reaction kinetics experimental device includes: a vertical high-temperature tube furnace lifting mechanism, a bottom buffer deceleration mechanism, a gas supply system, a feeding device, a quencher, a temperature controller 6, a laser displacement sensor 27, an acceleration sensor 28 and a computer 7; wherein; the vertical high-temperature tube furnace lifting mechanism includes a base 14, a vertical guide rail bracket 15, a guide rail 16, a slider 2, a vertical high-temperature tube furnace 1, a pull rope 4, a pulley block 18 and an electric winch 17, vertical guide rail brackets 15 are respectively provided on both sides of the base 14, and guide rails 16 are respectively provided on the inner side of the vertical guide rail bracket. Preferably, the length of the guide rail 16 is between 5 and 8 meters; both sides of the vertical high-temperature tube furnace 1 are connected to the corresponding guide rails 16 through the slider 2; a pulley block 18 is provided above the vertical high-temperature tube furnace 1, and a pull rope 4 is wound on the pulley block 18, and one end of the pull rope 4 is connected to the vertical The hook 3 on the high-temperature tube furnace 1 is connected, and the other end is connected to the electric winch 17. Through the drive of the electric winch 17, the pull rope 4 is pulled by utilizing the labor-saving characteristics of the pulley block 18, and the fixing and lifting of the vertical high-temperature tube furnace 1 are realized by pulling the pull rope; the vertical high-temperature tube furnace 1 adopts silicon-molybdenum rods as heating elements, and the temperature measurement adopts platinum-rhodium thermocouples. The power is provided by the split high-power silicon rectifier 5, and the precise control of the furnace temperature is realized by the temperature controller 6. The inner liner of the vertical high-temperature tube furnace 1 is made of lightweight and high-temperature resistant fiber materials to effectively reduce the overall weight of the furnace. The furnace tube 9 is made of alumina or quartz glass round tubes to ensure that the furnace tube 9 is located in the center of the vertical high-temperature tube furnace 1. The furnace tube 9 is the key reaction area. Preferably, the diameter of the furnace tube 9 is controlled between 60 and 100 mm, the length is 1.0 meter, and the length of the high-temperature zone is greater than 0.8 meters;

[0058] The bottom buffer deceleration mechanism includes a spring 20, which is arranged on the base 14 corresponding to the slider 2. By arranging the spring 20 as a decelerator, the risk of the vertical high-temperature tube furnace 1 falling to the ground due to the breakage of the pull rope 4 is avoided, thereby improving safety.

[0059] The gas supply system includes a reducing gas supply system and an inert gas supply system. Both the reducing gas supply system and the inert gas supply system include a compressed gas cylinder 22, a pressure reducer 23 and a mass flow controller 24. The compressed gas cylinder 22 is connected to the air inlet of the vertical high-temperature tubular furnace 1 through the pressure reducer 23 and the mass flow controller 24. The reducing gas is preferably hydrogen; the inert gas is nitrogen or argon.

[0060] The feeding device is a piezoelectric driven feeder 10, the outlet of the piezoelectric driven feeder 10 is connected to the feed port of the vertical high temperature tube furnace 1 through a vertical metal round tube 13, and the piezoelectric driven feeder 10 rises and falls together with the vertical high temperature tube furnace 1. Preferably, the single feeding amount of iron ore powder is 5 to 20 mg;

[0061] The quencher is used for rapid cooling and collection; it includes a quencher body 11, an electronic refrigeration plate 30 and a refrigeration plate controller 31. The quencher body 11 is a truncated cone structure that is narrow at the top and wide at the bottom. The quencher body 11 is made of stainless steel. The quencher body 11 is connected to the outlet of the vertical high-temperature tube furnace 1 through a flange 12. Since the furnace tube 9 will generate a large amount of heat radiation during operation, it is easy to cause the temperature of the quencher body 11 to rise. The quencher body 11 is filled with a quenching medium. Preferably, the quenching medium is an ice-water mixture. In addition, a high-power electronic refrigeration plate 30 and a refrigeration plate controller 31 are installed at the bottom of the quencher body 11 to ensure that the ice-water mixture in the quencher body 11 will not completely melt and heat up or solidify and freeze during the experimental period.

[0062] The mass flow controller 24, the piezoelectric driven feeder 10, the refrigeration plate controller 31, the temperature controller 6, the laser displacement sensor 27, the acceleration sensor 28, and the electric winch controller 29 are all communicatively connected to the computer 7; the laser displacement sensor 27 is used to measure the position of the vertical high-temperature tube furnace 1, and the acceleration sensor 28 is used to measure the descending acceleration of the vertical high-temperature tube furnace 1.

[0063] In this embodiment, the bottom buffer deceleration mechanism also includes a permanent magnet 19. The bottom of the vertical high-temperature tube furnace 1 and the base 14 are correspondingly provided with permanent magnets 19 with opposite polarities. When the vertical high-temperature tube furnace 1 descends to near the bottom, the vertical high-temperature tube furnace 1 will be effectively stopped by utilizing the principle of mutual repulsion of like magnetic poles, thereby avoiding safety accidents that may be caused by the vertical high-temperature tube furnace 1 falling to the ground, and further enhancing safety.

[0064] To ensure safety, the maximum release length of the pull rope 4 satisfies the distance between the quencher body 11 and the base 14 of 10 to 15 cm.

[0065] In this embodiment, limit switches 21 are provided at the upper and lower ends of the guide rail 16, and the limit switch 21 is linked with the electric winch controller 29. When the vertical high-temperature tube furnace 1 triggers the limit switch 21, the electric winch 17 stops.

[0066] In order to ensure that the gas pipeline can be elastically expanded and contracted during the lifting process, the mass flow controller 24 is connected to the air inlet of the vertical high-temperature tube furnace 1 through a spring expansion tube 25. This design also effectively reduces the problem of deviation of the descending trajectory of iron ore powder particles due to gas disturbance.

[0067] In this embodiment, a gas outlet is provided on one side of the lower portion of the furnace tube 9 of the vertical high-temperature tube furnace 1, and the gas outlet is connected to an exhaust gas treatment device 26 to ensure the environmental protection and safety of the experimental process.

[0068] like Figure 2 As shown, a cross grid is provided at the inner bottom of the quencher body 11, and the cross grid can suppress the shaking of the quenching medium during the lifting process.

[0069] In order to ensure continuous power supply and heating of the circuit of the vertical high-temperature tube furnace 1 during the lifting process, the vertical high-temperature tube furnace 1 is connected to the temperature controller 6 via a spring cable 8 .

[0070] See also Figure 3 As shown, the present invention also discloses an experimental method of the above-mentioned hydrogen-based flash ironmaking reaction kinetics experimental device, and the specific steps are as follows:

[0071] Step S1: Start: clean the vertical high-temperature tube furnace 1 and check the connection status of each device;

[0072] Step S2: setting experimental parameters, including iron ore powder particle size, heating temperature, gas flow rate and iron ore powder particle addition amount;

[0073] Step S3: placing a quenching medium into the quencher body 11, and adding screened iron ore powder particles of a specified particle size into the piezoelectric driven feeder 10;

[0074] Step S4: Install the vertical high-temperature tubular furnace 1 in place, connect the top of the furnace tube 9 to the piezoelectric driven feeder 10, and the bottom to the cold quencher, check the air tightness of the equipment, evacuate the equipment for leak test, and after the test, control the inert gas supply system through the computer 7 program to introduce inert gas to ensure that the oxygen in the furnace is completely emptied, close the inert gas supply system, clean the surrounding site and set up metal guardrails to prevent people from entering;

[0075] Step S5: heating the furnace tube 9 to a specified temperature (1000-1600° C.) at a rate of 10-20° C. / min and keeping the temperature constant, controlling the reducing gas supply system to introduce reducing gas at a flow rate of 0.1-5 L / min for at least 30 minutes, ensuring that the furnace tube 9 is completely filled with reducing gas and then closing the furnace tube 9;

[0076] Step S6: Calculate the longest falling time t of the iron ore powder particles, calculate the control parameters according to the longest falling time t and import them into the electric winch controller 29, the longest falling time t of the iron ore powder particles is the free fall stage time t1 of the iron ore powder particles before the vertical high-temperature tubular furnace 1 falls at a constant acceleration, the vertical high-temperature tubular furnace 1 constant acceleration stage time t w Vertical high temperature tube furnace 1 deceleration and stationary stage time t e The sum of t = t1 + t w +t e , vertical high temperature tube furnace 1 deceleration and stationary stage time t e The end condition is that the furnace is stationary and the iron ore powder particles completely fall into the quencher;

[0077] Step S7: Calculate the single feeding amount and feeding times according to the feeding amount of the iron ore powder particles;

[0078] Step S8: Figure 4 As shown, the vertical high-temperature tube furnace 1 is pulled up to the high point T, and the gas valve is closed to stop the gas supply;

[0079] Step S9: Control the piezoelectric driven feeder 10 to feed, and the iron ore powder particles fall into the furnace tube 9 through the vertical metal round tube 13;

[0080] Step S10: When the iron ore powder particles descend to the high temperature zone close to the vertical high temperature tube furnace 1, the electric winch controller 29 controls the vertical high temperature tube furnace 1 to descend according to the control parameters. The whole descending process is divided into three stages, the first stage is the free fall stage, the second stage is the constant acceleration stage, and the third stage is the deceleration and stationary stage;

[0081] In the second stage, the computer 7 receives the data from the laser displacement sensor 27 and the acceleration sensor 28, performs real-time analysis, and the data processing module of the computer software calculates the current descent acceleration and the target constant acceleration a of the control parameter. w According to the deviation, the PID control algorithm is used to calculate the output adjustment amount of the electric winch 17, so as to control the high-temperature tube furnace 1 to descend at a constant acceleration; the target constant acceleration is lower than the gravity acceleration to ensure that the iron ore powder particles can continue to descend relative to the vertical high-temperature tube furnace 1;

[0082] Step S11: the iron ore powder particles gradually fall into the quencher body 11. When the iron ore powder particles freely fall to the middle and lower part close to the vertical high-temperature tube furnace 1, the vertical high-temperature tube furnace 1 is in a deceleration and stationary stage. Under the deceleration effect of the pull rope 4, the permanent magnet 19 and the spring 20, the vertical high-temperature tube furnace 1 is in a deceleration and descending state until it stops descending. At this time, the vertical high-temperature tube furnace 1 is at the low point B.

[0083] Step S12: Control the reducing gas supply system to introduce reducing gas, and keep it for 3 to 5 minutes, then return to step S8 to repeat the experimental process until the cycle reaches the set number of times and then enter step S13;

[0084] Step S13: Control the inert gas supply system to introduce inert gas, the vertical high-temperature tube furnace 1 stops working, and the vertical high-temperature tube furnace 1 enters a cooling stage. The entire cooling process lasts for 4 to 6 hours until the vertical high-temperature tube furnace 1 cools to room temperature;

[0085] Step S14: disassembling the quencher body 11, collecting the cooled reduced iron ore powder particles, and placing them in a nitrogen-protected drying oven for drying; then, testing and analyzing the dried samples to evaluate the reduction degree and phase composition of the iron ore powder particles;

[0086] Step S15: Whether the conditional experiment is completed, if not, proceed to step S2; if the conditional experiment is completed, proceed to step S16;

[0087] Step S16: Calculate reaction kinetic parameters according to the metallurgical reaction kinetics principle;

[0088] Step S17: End.

[0089] Calculating the longest falling time t of the iron ore powder particles in step S6 includes the following steps:

[0090] Step S91: the free fall stage of the iron ore powder particles before the vertical high-temperature tube furnace 1 descends at a constant acceleration: calculate the acceleration du of the iron ore powder particles at each moment in this stage t / dt, speed u t and displacement d1. When displacement d1 is greater than the initial displacement D of the iron ore powder particle, s Output the free fall time t1 of the iron ore powder particles in this stage, and the initial displacement D of the iron ore powder particles s is the displacement of the iron ore powder particles before the vertical high-temperature tubular furnace 1 descends at a constant acceleration;

[0091] Step S92: Constant acceleration stage of vertical high temperature tube furnace 1: set the initial value a1 of constant acceleration of vertical high temperature tube furnace 1, calculate the acceleration du of iron ore powder particles at each moment in this stage w / dt, speed u w and displacement d2. When the vertical high-temperature tube furnace 1 reaches the maximum travel distance H, the vertical high-temperature tube furnace 1 constant acceleration stage time t is output. w ;

[0092] Step S93: the vertical high-temperature tube furnace 1 deceleration and stationary stage; calculate the acceleration du of the iron ore powder particles at each moment in this stage e / dt, speed u eand displacement d3, until the iron ore powder particles fall into the bottom of the quencher, the vertical high-temperature tube furnace 1 deceleration and stationary stage time t is output at this stage e ; Calculate the total fall time T d ;

[0093] Step S94: Determine the total falling time T d Is it the longest descending time t? If so, proceed to step S95; if not, proceed to step S92 to reset the constant acceleration value of the vertical high-temperature tube furnace 1 until the total descending time T d The maximum decline time t is when it stops increasing;

[0094] Step S95: Determine the descending speed u of the iron ore powder particles in the vertical high-temperature tube furnace 1 during the constant acceleration stage w Is it always greater than the lower limit value U of the iron ore powder particle descent speed in the constant acceleration stage? m If yes, proceed to step S96; if no, proceed to step S92 to reset the constant acceleration value of the vertical high-temperature tube furnace 1;

[0095] Step S96: output control parameters and draw a motion relationship curve diagram.

[0096] Specifically: Assuming that the iron ore powder is spherical iron ore powder particles, given the particle size d of the iron ore powder p , iron ore powder particle density ρ p , iron ore powder particle initial displacement D s , the maximum travel distance H of the vertical high-temperature tube furnace 1, the length of the furnace tube L, the lower limit value U of the falling speed of the iron ore powder particles in the constant acceleration stage m is a known quantity;

[0097] Target constant acceleration a w And vertical high temperature tube furnace 1 constant acceleration stage time t w The maximum travel distance H satisfies 0.5·a w ·t w 2 ≤H.

[0098] The displacement distance d of the iron ore powder particles is less than or equal to the furnace tube length L, that is, d≤L; the displacement d of the iron ore powder particles is the displacement d1 in the time period t1, t w Displacement of time period d2, t e The sum of the displacement d3 of the time period is calculated as:

[0099]

[0100] Where u t is the falling speed of iron ore powder particles in time period t1, u w t w The falling speed of iron ore powder particles in the time period, ue t e The rate of decline over a period of time.

[0101] Iron ore powder particles are mainly subject to three kinds of forces in hydrogen fluid: (1) forces unrelated to the relative descent of hydrogen fluid-iron ore powder particles: inertia and gravity; (2) forces related to the relative descent of hydrogen fluid-iron ore powder particles, and the direction of the forces is along the relative descent direction: drag force, additional mass force and Basset force; (3) forces related to the relative descent of hydrogen fluid-iron ore powder particles, and the direction of the forces is perpendicular to the relative descent direction: lift force, Magnus force and Saffman force; The process involved in the free fall of iron ore powder particles in the furnace is relatively complicated, and the calculation process is simplified. Iron ore powder particles are subject to gravity, buoyancy and drag force; The calculation formula for the force relationship of iron ore powder particles is:

[0102]

[0103] In the formula, F D is the drag force on the iron ore powder particles, F G is the gravity on the iron ore powder particles, F B is the buoyancy of the iron ore powder particles, Re is the Reynolds number, A p is the center area of ​​the iron ore powder particle, V p is the volume of iron ore powder particles, m p is the mass of iron ore powder particles, ρ p is the density of iron ore powder particles; g is the density of hydrogen, u g is the gas velocity, u p is the particle velocity of iron ore powder, du p / dt is the time derivative of velocity, i.e. acceleration, and g is the acceleration due to gravity.

[0104] When the gas velocity u g When is 0, according to the force relationship of iron ore powder particles, the general calculation formula for the acceleration of iron ore powder particles is:

[0105]

[0106] In the formula, μ g is the viscosity, d p is the particle size of iron ore powder.

[0107] When the iron ore powder particles are in the free fall stage before the vertical high-temperature tube furnace 1 drops at a constant acceleration, the acceleration to which the iron ore powder particles are subjected is:

[0108]

[0109] During the deceleration and stationary stage of the vertical high-temperature tube furnace 1, the acceleration to which the iron ore powder particles are subjected is:

[0110]

[0111] In the constant acceleration stage of vertical high-temperature tube furnace 1, the acceleration formula of iron ore powder particles is calculated according to the force relationship of iron ore powder particles:

[0112]

[0113] Where g is the acceleration of gravity; M is the molecular weight; T is the temperature; σ is the Lennard-Jones parameter; Ω is the dimensionless characteristic number;

[0114] Take the furnace tube 9 with a length of 1m as an example, the furnace temperature is 1200℃, the hydrogen content is 100%, the partial pressure is 1bar, and the hydrogen density is 0.018kg / m 3 , viscosity is 2.45e-5kg·m -1 ·s -1 The particle density of iron ore powder is 4700kg / m 3 , the displacement D of the iron ore powder particles in time period t1 s The maximum travel distance H is 6 m, and the furnace descent height is 0.1 m. According to the above method and formula, the descent time of 100 μm iron ore powder particles in the furnace is 2.16 s, which is 1.10 s higher than the descent time of 1.06 s in the free fall mode alone. At this time, the required descent acceleration of the vertical high-temperature tube furnace 1, i.e., the target constant acceleration a w 9.5m / s 2 , constant acceleration descent maintenance time t w It is 1.1s. Under the same conditions, for 200um iron ore powder particles, the falling time calculated according to the above method and formula is 1.54s, which is 1.00s higher than the falling time of 0.54s in the free fall mode alone.

Claims

1. A hydrogen-based flash ironmaking reaction kinetics experimental device, characterized in that: include: Vertical high temperature tube furnace lifting mechanism, bottom buffer deceleration mechanism, gas supply system, feeding device, quencher, temperature controller, laser displacement sensor, acceleration sensor and computer; among them; The vertical high-temperature tube furnace lifting mechanism comprises a base, a vertical guide rail bracket, a guide rail, a slider, a vertical high-temperature tube furnace, a pull rope, a pulley block and an electric winch. Vertical guide rail brackets are respectively provided on both sides of the base, and guide rails are respectively provided on the inner sides of the vertical guide rail brackets. Both sides of the vertical high-temperature tube furnace are connected to the corresponding guide rails through sliders; a pulley block is provided above the vertical high-temperature tube furnace, and a pull rope is wound on the pulley block, one end of the pull rope is connected to a hook on the vertical high-temperature tube furnace, and the other end is connected to the electric winch; The bottom buffer deceleration mechanism includes a spring, which is arranged on the base corresponding to the slider; The gas supply system includes a reducing gas supply system and an inert gas supply system, and both the reducing gas supply system and the inert gas supply system include a compressed gas cylinder, a pressure reducer and a mass flow controller, and the compressed gas cylinder is connected to the air inlet of the vertical high-temperature tube furnace through the pressure reducer and the mass flow controller; The feeding device is a piezoelectric driven feeding machine, the outlet of the piezoelectric driven feeding machine is connected to the feeding port of the vertical high temperature tube furnace through a vertical metal round tube, and the piezoelectric driven feeding machine rises and falls together with the vertical high temperature tube furnace; The quencher includes a quencher body, an electronic refrigeration plate and a refrigeration plate controller. The quencher body is a truncated cone structure that is narrow at the top and wide at the bottom. The quencher body is connected to the outlet of the vertical high-temperature tube furnace through a flange. An electronic refrigeration plate is provided at the bottom of the quencher body, and the electronic refrigeration plate is connected to the refrigeration plate controller. The mass flow controller, piezoelectric driven feeder, refrigeration plate controller, temperature controller, laser displacement sensor, acceleration sensor, and electric winch controller are all connected to the computer for communication; the laser displacement sensor is used to measure the position of the vertical high temperature tube furnace, and the acceleration sensor is used to measure the descending acceleration of the vertical high temperature tube furnace.

2. A hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: The bottom buffer deceleration mechanism also includes a permanent magnet. The bottom and the base of the vertical high-temperature tube furnace are correspondingly provided with permanent magnets with opposite polarities.

3. A hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: The maximum release length of the pull rope meets the requirement that the distance between the quencher body and the base is 10 to 15 cm.

4. A hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: Limit switches are provided at the upper and lower ends of the guide rails, and the limit switches are linked with the electric winch controller. When the vertical high-temperature tube furnace triggers the limit switch, the electric winch stops.

5. The hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: The mass flow controller is connected to the air inlet of the vertical high-temperature tube furnace through a spring expansion tube.

6. A hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: A gas outlet is arranged on one side of the lower part of the furnace tube of the vertical high-temperature tube furnace, and the gas outlet is connected to an exhaust gas treatment device.

7. The hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: The inner bottom of the quencher body is provided with a cross grid.

8. The hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, characterized in that: The vertical high temperature tube furnace is connected to the temperature controller via a spring cable.

9. The experimental method of a hydrogen-based flash ironmaking reaction kinetics experimental device according to claim 1, wherein the specific steps are as follows: Step S1: Start: clean the vertical high-temperature tube furnace and check the connection status of each device; Step S2: setting experimental parameters, including iron ore powder particle size, heating temperature, gas flow rate and iron ore powder particle addition amount; Step S3: placing a quenching medium into the quencher body, and adding screened iron ore powder particles of a specified particle size into the piezoelectric driven feeder; Step S4: Install the vertical high-temperature tube furnace in place, connect the top of the furnace tube to a piezoelectric driven feeder, connect the bottom to a cold quencher, check the air tightness of the equipment, evacuate the furnace tube for a leak test, and after the test is completed, control the inert gas supply system through a computer program to introduce inert gas to ensure that the oxygen in the furnace is completely emptied, close the inert gas supply system, clean the surrounding area, and set up metal guardrails to prevent people from entering; Step S5: heating the furnace tube to a specified temperature at a rate of 10-20°C / min and keeping the temperature constant, controlling the reducing gas supply system to introduce reducing gas at a flow rate of 0.1-5L / min for at least 30 minutes, ensuring that the furnace tube is completely filled with reducing gas and then closing the furnace tube; Step S6: Calculate the longest falling time t of the iron ore powder particles, calculate the control parameters according to the longest falling time t and import them into the electric winch controller. The longest falling time t of the iron ore powder particles is the free fall stage time t1 of the iron ore powder particles before the vertical high-temperature tube furnace drops at a constant acceleration, and the vertical high-temperature tube furnace constant acceleration stage time t w The time of deceleration and stationary stage of vertical high temperature tube furnace t e The sum of t = t1 + t w +t e ; Step S7: Calculate the single feeding amount and feeding times according to the feeding amount of the iron ore powder particles; Step S8: Raise the vertical high-temperature tube furnace to the high point T, close the gas valve and stop the gas supply; Step S9: Control the piezoelectric driven feeder to feed, and the iron ore powder particles fall into the furnace tube through the vertical metal round tube; Step S10: When the iron ore powder particles descend to the high temperature zone close to the vertical high temperature tube furnace, the electric winch controller controls the vertical high temperature tube furnace to descend according to the control parameters. The whole descent process is divided into three stages, the first stage is the free fall stage, the second stage is the constant acceleration stage, and the third stage is the deceleration and stationary stage; In the second stage, the computer receives the data from the laser displacement sensor and the acceleration sensor and performs real-time analysis. The data processing module of the computer software calculates the current descent acceleration and the target constant acceleration a of the control parameters. w According to the deviation, the PID control algorithm is used to calculate the output adjustment of the electric winch, so as to control the constant acceleration of the high-temperature tube furnace. The target constant acceleration is lower than the gravity acceleration to ensure that the iron ore powder particles can continue to descend relative to the vertical high-temperature tube furnace. Step S11: the iron ore powder particles gradually fall into the quencher body. When the iron ore powder particles freely fall to the middle and lower part of the vertical high-temperature tube furnace, the vertical high-temperature tube furnace is in a deceleration and stationary stage. Under the deceleration effect of the pull rope, the permanent magnet and the spring, the vertical high-temperature tube furnace is in a deceleration and descending state until it stops descending. At this time, the vertical high-temperature tube furnace is at a low point B. Step S12: Control the reducing gas supply system to introduce reducing gas, and keep it for 3 to 5 minutes, then return to step S8 to repeat the experimental process until the cycle reaches the set number of times and then enter step S13; Step S13: controlling the inert gas supply system to introduce inert gas, the vertical high-temperature tube furnace stops working, and the vertical high-temperature tube furnace enters a cooling stage. The entire cooling process lasts for 4 to 6 hours until the vertical high-temperature tube furnace cools to room temperature; Step S14: disassembling the quencher body, collecting the cooled reduced iron ore powder particles, and placing them in a nitrogen-protected drying oven for drying; then, testing and analyzing the dried samples; Step S15: Whether the conditional experiment is completed, if not, proceed to step S2; if the conditional experiment is completed, proceed to step S16; Step S16: Calculate reaction kinetic parameters according to the metallurgical reaction kinetics principle; Step S17: End.

10. The experimental method according to claim 9, characterized in that: Calculating the longest falling time t of the iron ore powder particles in step S6 includes the following steps: Step S91: The free fall stage of the iron ore powder particles before the vertical high-temperature tube furnace descends at a constant acceleration: calculate the acceleration du of the iron ore powder particles at each moment in this stage t / dt, speed u t and displacement d1. When displacement d1 is greater than the initial displacement D of the iron ore powder particle, s Output the free fall time t1 of the iron ore powder particles in this stage, and the initial displacement D of the iron ore powder particles s is the displacement of the iron ore powder particles before the vertical high-temperature tube furnace descends at a constant acceleration; Step S92: Vertical high temperature tube furnace constant acceleration stage: Set the initial value of constant acceleration a1 of the vertical high temperature tube furnace, and calculate the acceleration du of the iron ore powder particles at each moment in this stage. w / dt, speed u w And displacement d2, when the vertical high temperature tube furnace reaches the maximum travel distance H, the vertical high temperature tube furnace constant acceleration stage time t is output w ; Step S93: vertical high-temperature tube furnace deceleration and stationary stage; Calculate the acceleration du of the iron ore powder particles at each moment in this stage e / dt, speed u e and displacement d3, until the iron ore powder particles fall into the bottom of the quencher, output the deceleration and static stage time t of the vertical high-temperature tube furnace in this stage e ; Calculate the total fall time T d ; Step S94: Determine the total falling time T d Is it the longest falling time t? If yes, go to step S95; if not, go to step S92 to reset the constant acceleration value of the vertical high-temperature tube furnace; Step S95: Determine the descending speed u of the iron ore powder particles in the vertical high-temperature tube furnace at the constant acceleration stage w Is it always greater than the lower limit value U of the iron ore powder particle descent speed in the constant acceleration stage? m If yes, proceed to step S96; if no, proceed to step S92 to reset the constant acceleration value of the vertical high-temperature tube furnace; Step S96: Output control parameters.

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