Method for reducing oxygen-enriched side-blown iron-containing material by using biomass carbon source

Abstract

The invention discloses a method for reducing an oxygen-enriched side-blown iron-containing material by using a biomass carbon source, and particularly relates to the technical field of metallurgical process optimization and efficient utilization of carbon resources. By constructing a multi-point temperature monitoring system and combining carbon source pretreatment, oxygen enrichment disturbance control and rhythm function driving, dynamic matching of carbon source release and an oxygen channel is achieved, an alternate local reduction window is formed, and the reduction efficiency and the carbon utilization rate are effectively improved; meanwhile, by recognizing a high-residual reducing gas area, adjusting a tail gas extraction path and guiding the tail gas into a preheating area, tail gas heat value recovery and carbon recycling are achieved; the method has the advantages of high reaction efficiency, low carbon emission, low energy consumption and high system controllability, and is suitable for low-carbon metallurgy and resource recycling scenes.

Description

Technical Field

[0001] This invention relates to the field of metallurgical process optimization and efficient utilization of carbon resources, specifically to a method for using biomass carbon sources to reduce iron-containing materials by oxygen-enriched side-blowing. Background Technology

[0002] With the continuous advancement of low-carbon, high-efficiency, and green smelting processes in the iron and steel metallurgical industry, the clean and efficient reduction of iron-containing materials has become one of the key technological bottlenecks. In traditional blast furnace smelting processes, the reducing agent mainly relies on coke, which has problems such as high carbon emissions, low reaction efficiency, and high dependence on high-quality coking coal resources, which seriously restricts the development of green metallurgy.

[0003] Against this backdrop, oxygen-enriched side-blowing technology has attracted attention due to its high oxygen concentration, fast reaction rate, and enhanced reduction capacity through localized high temperatures. However, the following technical challenges exist in the practical application of oxygen-enriched side-blowing of iron-containing materials: The uneven pyrolysis of biomass carbon sources in a high-temperature, oxygen-rich environment can easily lead to local overheating and sintering, affecting the uniformity of reduction of iron-containing materials; (biomass pellets only provide heat and do not participate in reduction, while the oxygen-rich combustion of the gas produced by pyrolysis provides heat).

[0004] Due to the significant difference in particle size between biomass pellets and iron-containing materials, a stress gradient is easily formed at the gas-solid interface, leading to an unstable reaction interface. (Biomass powder and iron-containing materials are easily compressed into pellets and reduced upon heating. Each pellet is an independent reduction system, ensuring sufficient reduction of iron ore.)

[0005] Conventional biomass char powder has high reactivity, but the problem of oxygen-enriched combustion in the upper layer is solved, and it is converted into a heat source. However, it lacks effective path control and carbon efficiency management methods, making it difficult to achieve selective carbon reduction path regulation. When oxygen-enriched air is blown in, local hot spots are easily formed. If the release location of the biomass carbon source is misaligned with the high-temperature reaction zone, it will cause reverse reduction or secondary oxidation, resulting in a significant decrease in reduction efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a method for using biomass carbon source to reduce iron-containing materials by oxygen-enriched side blowing, so as to overcome the shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for using biomass carbon source for the reduction of iron-containing materials by oxygen-enriched side-blowing, comprising: Step S1: Load carbon-containing cold-solidified pellets with a particle size range of 5-45mm into the oxygen-enriched side-blowing device, and obtain the temperature change inside the furnace by monitoring the cooling water temperature. Step S2: Mix biomass pellets with iron-containing materials at a mass fraction of 5-20% to obtain cold-fixed pellets of 5-45mm. Step S3: Introduce an oxygen-enriched flow with an oxygen concentration of 40% to 70% into the oxygen-enriched side-blowing channel, and adjust the side-blowing angle so that the oxygen cuts into the iron-containing material layer at an angle of 10° to 20° in the horizontal direction, forming a multi-level turbulent vortex field with the biomass carbon source mixing layer. Step S4: Based on the multi-point temperature distribution information obtained by the temperature control thermocouple array in step S1, establish a temperature field-carbon gas release coupling model, reverse the region where the biomass carbon source gasification release path coincides with the main oxygen channel, and calculate the optimal release rhythm function. Step S5: Utilize rhythm functions to regulate the biomass carbon source feeding rate and the instantaneous flow rate of oxygen-enriched gas to form a dynamic alternating local reduction window; Step S6: At the end of the reaction, adjust the tail gas extraction path according to the reduction conversion rate distribution of iron-containing materials, and introduce the high residual reducing gas into the preheating zone to realize calorific value recovery and carbon efficiency reuse.

[0008] Preferably, the construction of the temperature field-carbon release coupling model includes: Temperature data at different depths and locations are collected in real time during the reaction process using a temperature-controlled thermocouple array to ensure the acquisition of continuous temperature change curves; A three-dimensional temperature distribution matrix is ​​constructed based on the collected data, and the region between thermocouples is compensated and fitted using linear interpolation to obtain a complete spatial temperature field. The temperature distribution is superimposed on the location of the carbon source, and the thermal activation zone is set according to the critical starting temperature of the pyrolysis reaction. The thermal activation zone is defined as a spatial subdomain with a temperature greater than or equal to 450℃.

[0009] Preferably, the method for reverse-engineering the carbon release path includes: Based on the superposition of the spatial distribution function of carbon source particles and temperature field data, the heat conduction rate and local temperature gradient are calculated using the finite element method. By establishing a set of carbon source pyrolysis kinetic equations, the carbon generation rate in each unit region is determined. The first-order reaction kinetic model is preferred, with its reaction rate constant following the Arrhenius formula, and the thermally activated region is used as the input boundary condition. By combining the oxygen-enriched flow velocity vector field, the region where the carbon release area intersects with the main oxygen channel is marked as the effective coupling domain, and its overlapping volume fraction is used to measure the cooperative efficiency of the reaction.

[0010] Preferably, the calculation of the optimal release rhythm function includes: The effective coupling domain is integrated over time to extract the synchronization between carbon release and oxygen main flux. The coupling index R is calculated and defined as the reciprocal of the square integral of the difference between the ratio of carbon to oxygen molar flux per unit volume and the target ratio. Based on the above coupling index R, an optimization objective function is constructed, and a genetic algorithm is used for multi-parameter iteration. The optimized input parameters include carbon source feed rate, carbon source distribution density, side-blown oxygen flow rate, and nozzle opening and closing frequency. The final output rhythm function is a function of the carbon source supply rate and time, in the form q(t), where t is the reaction time and q is the carbon source supply rate per unit time, achieving phase coincidence between the peak carbon release and the peak oxygen enrichment disturbance.

[0011] Preferably, the method of regulating the biomass carbon source feeding rate and the instantaneous flow rate of oxygen-enriched gas using a rhythm function specifically includes: The generated rhythm function q(t) is used as an input variable to link the execution modules in the carbon source feeding system and the oxygen-enriched injection system respectively. The carbon source feeding system adopts a screw feeder controlled by a stepper motor. Its feeding rate responds in real time to the change of the q(t) function value, and the adjustment frequency is not less than 1 Hz. The oxygen-enriched jet system controls the gas flow rate through servo valves, with an opening change response time of less than 1 second, ensuring that the oxygen-enriched flow rate reaches its maximum value at the rhythm peak.

[0012] Preferably, adjusting the exhaust gas extraction path according to the reduction conversion rate distribution of iron-containing materials specifically includes: The carbon monoxide to carbon dioxide concentration ratio in the tail gas at different locations at the end of the reaction was obtained by using a multi-point infrared online gas analyzer, and the degree of local reduction reaction was calculated. The region with a carbon monoxide volume fraction higher than 10% and a carbon dioxide volume fraction lower than 5% is defined as the high residual reducing gas region. The optimal exhaust gas extraction port is automatically selected based on the location coordinates of the high residual reducing gas zone.

[0013] Preferably, the temperature-controlled reactive thermocouple array is layered and embedded along the thickness direction of the material layer, specifically including: A layer of thermocouple sensing points is set on the upper and lower surfaces of the material layer to obtain the difference in heat exchange rate between the upper and lower surfaces. Multiple thermocouple nodes are vertically arranged at 10 mm intervals inside the material layer to form a three-dimensional temperature monitoring grid. Each thermocouple node is connected to the main controller via a high-speed data acquisition module, enabling dynamic monitoring.

[0014] Preferably, the interaction process between the perturbation vortex structure and carbon release is optimized through CFD simulation, specifically including: A three-dimensional simulation model was constructed, which included the nozzle structure, material layer porosity, and carbon source distribution. The gas flow boundary conditions were set using non-slip boundaries. Turbulence calculations were performed using the Reynolds stress model or the large eddy simulation model, and the degree of overlap between the airflow path and the carbon release path was simulated by combining the gas-solid coupling algorithm. Based on the simulation results, the nozzle layout was optimized to ensure that the average residence time of the local vortex structure in the reaction zone is not less than 0.3 seconds.

[0015] The technical effects and advantages provided by the present invention in the above technical solution are as follows: This invention constructs a rhythmic control mechanism based on temperature field feedback to coordinate the supply of biomass carbon source and the disturbance behavior of oxygen-enriched gas, forming a dynamic alternating local reduction window. This not only significantly improves the reduction efficiency and carbon source conversion rate of iron-containing materials, but also achieves precise recovery and calorific value reuse of residual reducing gas in the tail gas, reducing system energy consumption and improving carbon efficiency. It effectively solves the problems of low carbon utilization, local overheating sintering, and serious energy loss in traditional processes, demonstrating excellent green metallurgical application prospects and industrial promotion value. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0017] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1, please refer to Figure 1 As shown in this embodiment, the method for reducing iron-containing materials using biomass carbon source in oxygen-enriched side-blown combustion includes: Step S1: Load carbon-containing cold-solidified pellets with a particle size range of 5-45mm into the oxygen-enriched side-blowing device, and obtain the temperature change inside the furnace by monitoring the cooling water temperature. Step S2: Mix biomass pellets with iron-containing materials at a mass fraction of 5-20% to obtain cold-fixed pellets of 5-45mm. Step S3: Introduce an oxygen-enriched flow with an oxygen concentration of 40% to 70% into the oxygen-enriched side-blowing channel, and adjust the side-blowing angle so that the oxygen cuts into the iron-containing material layer at an angle of 10° to 20° in the horizontal direction, forming a multi-level turbulent vortex field with the biomass carbon source mixing layer. Step S4: Based on the multi-point temperature distribution information obtained by the temperature control thermocouple array in step S1, establish a temperature field-carbon gas release coupling model, reverse the region where the biomass carbon source gasification release path coincides with the main oxygen channel, and calculate the optimal release rhythm function. Step S5: Utilize rhythm functions to regulate the biomass carbon source feeding rate and the instantaneous flow rate of oxygen-enriched gas to form a dynamic alternating local reduction window; Step S6: At the end of the reaction, adjust the tail gas extraction path according to the reduction conversion rate distribution of iron-containing materials, and introduce the high residual reducing gas into the preheating zone to realize calorific value recovery and carbon efficiency reuse.

[0020] In the oxygen-enriched side-blown reduction method for iron-containing materials based on biomass carbon source described in this invention, the objective of step S1 is to construct a controllable reaction environment, ensure uniform distribution of carbon-containing raw materials and stable reaction space, and realize real-time monitoring of temperature changes in the furnace, so as to provide necessary thermal data support for subsequent carbon source release regulation and oxygen-enriched disturbance path matching.

[0021] The raw material used in this step is carbon-containing cold-set pellets, which are composed of iron concentrate, biochar powder, and binder (such as bentonite or starch) mixed and granulated in a preset ratio, pressed into shape at room temperature, and then naturally dried and cured. These cold-set pellets have advantages such as regular shape, moderate strength, and good air permeability, making them suitable for maintaining structural integrity and uniformly releasing carbon gas in oxygen-rich and disturbed environments.

[0022] The carbon-containing cold-cured pellets are loaded into the oxygen-enriched side-blown reactor via a mechanical feeding device, and their particle size is controlled within the range of 5–45 mm. The following factors were considered when setting this particle size range: The minimum particle size (5 mm) ensures that the pellets have sufficient mechanical strength and shatter resistance to prevent them from breaking into powder under high temperature disturbance; The maximum particle size (45 mm) ensures that oxygen can penetrate into the interior of the particles and form multiple pyrolysis channels, enhancing the uniformity of carbon gas release; The particle size distribution can be selected as normal or slightly skewed to improve the bulk density and gas-solid contact area.

[0023] The pellets are laid in layers in the bottom charging area of ​​the reactor. The stacking height can be adjusted according to the furnace type and oxygen flow disturbance design, and is generally controlled in the range of 100 to 300 mm.

[0024] To achieve thermal field monitoring and dynamic control of the reaction process, this invention employs a cooling water temperature difference monitoring method to indirectly reflect temperature changes within the furnace. The specific method is as follows: In the cooling system of the furnace shell or furnace of the oxygen-enriched side-blowing device, inlet and outlet water temperature sensors are installed to measure the cooling water inlet temperature T_in and outlet temperature T_out, respectively. The cooling water flow rate Q is obtained in real time through a flow meter; Based on the principle of energy conservation, the heat absorbed by the furnace body per unit time, ΔQ, can be estimated using the following formula: Where ρ is the density of cooling water ( C is the specific heat capacity ( Q is the volumetric flow rate ( T_out and T_in are the outlet and inlet water temperatures, respectively. The trend of heat release in the furnace is reflected in the increase or decrease of ΔQ, which can indirectly deduce information about the reaction intensity or carbon release rate.

[0025] In the oxygen-enriched side-blown reduction method for iron-containing materials based on biomass carbon source described in this invention, the main purpose of step S2 is to uniformly mix biomass particles with iron-containing raw materials in an appropriate ratio and granulate them to form cold-solidified pellets with moderate strength and good reactivity, thereby providing a controllable microstructure basis and carbon source distribution conditions for the stable reaction under subsequent high-temperature oxygen-enriched disturbance environment.

[0026] The mixed raw materials involved in this step mainly include the following two categories: Iron-containing materials: Select high-grade iron concentrate or high-grade iron oxide powder with strong reactivity, preferably with a particle size of less than 0.15 mm, in order to improve the pelletizing bonding strength and reaction uniformity; Biomass pellets: The sources include biochar powder or crushed biomass pellets obtained by pre-processing agricultural and forestry waste (such as rice husks, sawdust, straw powder, etc.), with a particle size controlled between 100 and 500 μm, a moisture content of less than 8%, and high volatile matter and specific surface area.

[0027] To improve the uniformity of mixing, both iron-containing materials and biomass carbon sources need to be screened to remove impurities and dried at room temperature to avoid affecting the pelletizing effect due to differences in moisture content.

[0028] The addition ratio of biomass pellets was set at 5-20% of the total mass of iron-containing materials. This range has been experimentally verified to achieve a balance between the carbon source's participation in the reduction reaction and the pelletizing strength. When the mass fraction is less than 5%, the carbon source content is insufficient, resulting in insufficient subsequent carbon gas release and affecting the reduction efficiency. When the mass fraction is higher than 20%, the pellet structure is loose, which affects mechanical strength and stacking stability, and it is easy to break and pulverize under high temperature disturbance.

[0029] The mixing process is carried out using a twin-shaft high-intensity mixer or a vertical agitator, with the mixing time controlled between 3 and 8 minutes, and the mixing speed set between 60 and 120 rpm depending on the material characteristics. To determine the mixing quality, the "local sampling deviation rate" method can be used for evaluation; a mixing uniformity of 90% or higher is sufficient to meet the pelletizing requirements.

[0030] After uniform mixing, the mixture is formed into pellets using a disc pelletizer or a forced pelletizer. The pellet size is controlled between 5 and 45 mm. This particle size range is set based on the following criteria: pellets smaller than 5 mm are easily carried by airflow or sintered into lumps under high-temperature oxygen-rich disturbance, resulting in poor stability; pellets larger than 45 mm are difficult to pyrolyze internally, limiting carbon release and reducing reaction efficiency; the preferred particle size distribution exhibits a bell-shaped curve, with a median particle size of around 25 mm, which is beneficial for the permeability of the reaction bed and the spatial uniformity of carbon release. After cold solidification, the pellets are naturally dried at room temperature or dried using a low-temperature air-drying device for 12–24 hours to reduce their moisture content to below 5%, ultimately forming carbon-containing cold-solidified pellets with moderate strength and regular morphology.

[0031] To ensure granulation quality and reaction compatibility, the obtained cold-set pellets must meet the following technical specifications: project Technical Requirements compressive strength ≥20 N / piece Bulk density <![CDATA[1.8~2.4 g / cm 3 ]]> Carbon content (on a dry basis) 8–18 wt% Roundness of pellet morphology ≥85% Moisture content ≤5 wt% (after air drying) After sampling, the finished pellets are sent to the subsequent step S1 and loaded into the reactor loading area to provide a standardized reaction unit for the oxygen-enriched side-blowing disturbance reaction.

[0032] Oxygen-enriched gas is obtained using pressure swing adsorption (PSA) or membrane separation technology to separate high concentrations of oxygen from ordinary air. The volume fraction of the prepared oxygen-enriched gas needs to be controlled between 40% and 70%, and dynamically adjusted according to the reaction temperature range, the reactivity of the carbon source, and the thickness of the material layer.

[0033] To ensure that the oxygen-enriched flow has a stable flow state and pressure before entering the nozzle, this invention uses a pressure-stabilizing buffer tank system to control the blowing pressure within the range of 0.05 to 0.15 MPa, and the airflow fluctuation rate (i.e., the ratio of the difference between the maximum and minimum flow rates within 1 minute to the average value) is controlled within ±5%.

[0034] After pressure stabilization, the gas flows through a silent flow stabilizer (the structure can be a multi-stage perforated plate or a honeycomb rectifier) ​​to eliminate gas pulsation and output quasi-laminar flow characteristics. Through this treatment, the oxygen-enriched flow entering the jet channel has a predictable and controllable velocity field, laying the foundation for the formation of subsequent turbulent eddies.

[0035] The oxygen-enriched spray structure of this invention is located in the lower middle part of the side wall of the reaction device, maintaining a horizontal angle with the material layer. The nozzle adopts an elliptical or slit-type opening structure, with its major axis arranged along the material flow direction, and the outlet width controlled at 2-8 mm, which is conducive to the formation of a pressure differential induced structure after the airflow enters the material layer.

[0036] The nozzle is equipped with an electrically adjustable tilt mechanism, which can precisely adjust the spray angle within the range of 10° to 20°, with an adjustment accuracy of no less than 1°. The angle adjustment is based on the temperature gradient information fed back from the thermocouple array in the reaction zone, combined with a fuzzy control algorithm to set a dynamic target angle, ensuring that the jet direction always points towards the thermally active area.

[0037] The nozzles are evenly arranged along the length of the material layer, with a spacing of 10 to 20 centimeters between adjacent nozzles. Each nozzle has its flow rate and angle parameters independently controlled by an intelligent diversion valve group, enabling regional responsive spraying adjustment.

[0038] This invention, through precise control of the nozzle structure, flow rate, and angle, enables the oxygen-enriched flow to generate the following three disturbance mechanisms after entering the mixture layer of iron-containing materials and biomass carbon sources: Primary impact zone: The nozzle exit area is a compression disturbance zone formed by the direct impact of high-energy gas on the material layer; Shear reflux zone: High-speed oxygen-enriched flow shears and forms reflux vortices in the porous structure of the material, causing local disturbance to the carbon source; Microscale vortex domain: Local vortex structures are formed in the interparticle gaps, which enhances the contact probability and reaction interface between the gas and the carbon source.

[0039] The superposition of the above-mentioned perturbation structures forms a three-dimensional vortex network structure, known as a multi-level perturbation vortex field. Its structural stability and spatial positioning are experimentally verified using a particle image velocimetry (PIV) system to ensure that the overlap rate between the vortex core region and the carbon source enrichment region is not less than 85%. If the deviation exceeds this threshold, the system will trigger a fine-tuning of the nozzle angle or flow velocity to correct the perturbation direction.

[0040] To accurately construct the perturbation field distribution and guide nozzle parameter design, this invention introduces a computational fluid dynamics (CFD) simulation platform to construct a three-dimensional perturbation field model. The model construction method is as follows: The geometric model was constructed based on the actual nozzle arrangement, material layer thickness and carbon source distribution, and the porosity was determined experimentally (range 0.35 to 0.55). The boundary conditions are set as follows: the nozzle inlet is a constant flow velocity boundary, and the upper and lower boundaries of the material layer are set as wall-no-slip boundaries. The Reynolds stress model (RSM) or large eddy simulation (LES) was selected for the turbulence model. RSM is suitable for evaluating the location of stable vortex formation, while LES is suitable for capturing unsteady microscale vortex behavior. The gas-solid coupling adopts the Euler-Euler two-fluid model, in which the gas phase uses the incompressible continuity equation and the solid phase particle behavior is calculated by the particle pressure model. The disturbance dwell time (i.e., the average time that the oxygen-rich eddy exists in the carbon source region) is used as an evaluation indicator. The target value is set to be no less than 0.3 seconds. If it is lower than this threshold, it will be considered that the disturbance effect is insufficient.

[0041] The simulation results will output a vortex core location distribution map, a velocity vector map, and a carbon source contact probability map. Combined with nozzle parameter optimization, a perturbation enhancement matrix will be formed to guide the comprehensive optimization of nozzle angle, flow velocity, spacing, and time series.

[0042] The aforementioned disturbance structure and the reaction temperature field form a linked control mechanism. The local temperature distribution acquired by the temperature control array will be linked with the angle control module in the jetting system, and a fuzzy logic control algorithm will be used to establish a temperature-disturbance intensity mapping relationship.

[0043] The core control variables of this algorithm include: Current temperature at the monitoring point; Temperature difference in neighboring areas; Current flow rate at the nozzle; The impact rate of the previous round of adjustments on temperature changes.

[0044] Fuzzy rules are set in the form of IF-THEN, for example: If the IF temperature is too high and the temperature difference is large, then increase the jetting angle and reduce the flow rate. If the temperature is low and the eddy current intensity is low, then reduce the jet angle and increase the flow rate.

[0045] The above control strategy can achieve dynamic coordination between disturbance eddies and thermal reaction behavior, maximizing carbon-oxygen reaction efficiency and heat conduction uniformity.

[0046] Thermocouple arrays are deployed at multiple depths and lateral positions within the material layer, with a sampling frequency set to 10 Hz, meaning 10 sets of temperature data are collected per second to ensure high temporal resolution. Each set of data includes temperature values ​​from three lateral points across the upper, middle, and lower layers of the material layer, for a total of nine measurement points.

[0047] The collected temperature data is first spatially expanded using linear interpolation to fill in gaps in areas without temperature data points, forming a three-dimensional temperature distribution matrix. This matrix describes temperature changes in the X, Y, and Z directions, meaning temperature is a function of position (x, y, z) T(x, y, z). Then, temperature contour analysis tools are used to visualize this three-dimensional temperature matrix as a multi-layer temperature cloud map, providing fundamental data for subsequent identification of carbon release zones.

[0048] To determine the thermally activated region of the carbon source, a threshold temperature of 450 degrees Celsius for the initial pyrolysis of the carbon source is set. That is, when the temperature T(x,y,z) of a certain region is ≥ 450 degrees Celsius, the region is considered to have reached the conditions for carbon release and is denoted as the thermally activated region. The spatial distribution of this region is surrounded by an isothermal surface T = 450℃ in the temperature field, forming a dynamically changing three-dimensional region.

[0049] By combining the thermally activated zone and the initial carbon source distribution data, spatial inversion of the carbon release path can be achieved. The carbon source distribution function is set as C(x,y,z), representing the carbon source concentration at any point in the three-dimensional material layer. This function is determined by a preset feeding mode and can be a uniform distribution, a linearly decreasing distribution, or a zoned weighted distribution.

[0050] The intersection of the thermally activated zone and the carbon source distribution is defined as the effective carbon release zone. This zone is divided into sections, with each section being a 100 cubic millimeter unit. The pyrolysis rate is estimated for each unit. The pyrolysis rate R_T in this unit is represented by the first-order reaction kinetic equation, and its calculation formula is as follows: Where A is the frequency factor, and its value range is... to E_a is the apparent activation energy, expressed in joules per mole, and its value is approximately... J / mol, R is the gas constant, 8.314 J / (mol·K), T is the cell temperature in K (Kelvin), and C is the carbon source concentration in the current cell.

[0051] By calculating the above reaction rates unit by unit in the three-dimensional carbon source distribution region, a carbon release pathway map can be constructed.

[0052] In step S3, oxygen-enriched gas is injected into the material layer from the nozzle at an initial velocity v0 along a set angle (10°–20°). This airflow path can be solved in CFD simulation to obtain its velocity vector field V_O(x,y,z), with the main channel defined as a continuous path region where the velocity modulus is greater than 1.2 times the average value. The effective carbon-oxygen coupling domain is extracted by spatially overlapping the carbon release rate distribution R_T(x,y,z) with the oxygen main channel region V_O(x,y,z).

[0053] The effective coupling domain is the area where carbon and oxygen highly overlap, representing the main region of high reaction efficiency. The coupling efficiency η is defined as the ratio of the volume fraction of this domain to the total carbon source release area volume, calculated as: η = V_overlap / V_total; where V_overlap is the volume of the carbon-oxygen overlap region, and V_total is the volume of all carbon release areas. Empirical verification shows that when the η value is higher than 0.7, the carbon conversion rate in the reaction zone can reach over 80%.

[0054] To achieve dynamic synergy between carbon release behavior and oxygen-enriched disturbance behavior, this invention constructs an optimal release rhythm function q(t), which represents the relationship between the carbon source feed rate per unit time and time. The goal is to achieve phase coincidence between the peak carbon release and the peak oxygen-enriched disturbance to enhance reduction efficiency.

[0055] The steps to construct this function are as follows: Input parameter settings: including upper limit of carbon source feed rate, current material layer thickness, current oxygen enrichment flow cycle, and target coupling efficiency (preferably ≥0.75); Optimization objective function definition: the objective function is set as follows. ; where Φ(t) is the carbon release rate curve and Ψ(t) is the oxygen-enriched flow velocity disturbance curve. The smaller the square integral of the difference between the two, the better the coupling effect. Algorithm implementation: A genetic algorithm is used to solve the problem, with a population size of 50, an evolutionary generation of 100, a crossover rate of 0.6, and a mutation rate of 0.1. The function output format is: q(t) is a piecewise continuous function with periodic characteristics. Two to three release peaks are set within the oxygen-enriched cycle, and the peak times are not more than 0.5 seconds off from the center point of the oxygen-enriched disturbance time window.

[0056] The generated q(t) rhythm function is input to the carbon source feeding control system through the interface module to achieve precise control of the carbon source feeding rate.

[0057] To ensure the model's adaptability and dynamic response capability, this invention designs a sliding window reconstruction mechanism. In actual operation, the current temperature field data is resampled and the rhythm function is updated every 60 seconds, with a sampling window length of 10 seconds, covering three oxygen-enriched perturbation cycles. All calculations are performed in edge computing units to avoid latency accumulation.

[0058] In addition, the material supply response time is controlled within 3 seconds, that is, the delay from the update of the rhythm function to the change in material supply is no more than 3 seconds, ensuring that the system has near real-time response capability.

[0059] By matching the temperature field-carbon release coupling model with the oxygen-enriched flow channel, the rhythm function q(t) of carbon source supply was obtained. This function is an expression of the carbon source supply rate per unit time as a function of time, and can be a continuous or piecewise function.

[0060] In this step, q(t) is input into the linkage execution system to drive the carbon source feeding unit and the oxygen-enriched injection unit respectively: The carbon source feeding unit uses a precision stepper motor-driven screw feeder with variable frequency response capability. The maximum adjustment frequency of the feeding rate response q(t) is 1 Hz, meaning that the feeding adjustment can be completed once per second, with a response time delay of less than 1.5 seconds. The oxygen-enriched injection unit uses a servo-electrically controlled valve assembly located at the front end of each nozzle. The injection flow rate is synchronously adjusted according to the coupling peak period in q(t), with a maximum airflow adjustment frequency of 2 Hz and a response time of less than 1 second, ensuring that the injection disturbance and carbon release coincide in the time domain.

[0061] The system is centrally scheduled by a controller that uses an edge computing architecture to avoid delays caused by large amounts of data transmission.

[0062] The "dynamic alternating local reduction window" proposed in this invention refers to a highly efficient micro-region in which carbon gas generated by biomass carbon source gasification and the disturbance zone guided by oxygen-enriched jet form a high degree of overlap in time and space within the iron-containing material layer, promoting the occurrence of selective reduction reaction. This micro-region is intermittent and mobile during the reaction process.

[0063] The conditions for building a window are defined as follows: The instantaneous value of the carbon release rate R_C in a certain spatial region reaches more than 70% of the maximum value in that region; The intensity of oxygen-enriched airflow disturbance I_O (measured by local airflow flux) reaches more than 70% of its peak value in the same region; The spatial overlap volume of the above two conditions is greater than 50% of the volume of the disturbance unit, and the duration Δt ≥ 1 second.

[0064] A spatial cell that meets the above conditions is defined as an effective restoration window. Multiple windows appear sequentially within the perturbation period, forming an alternating window sequence.

[0065] Typically, within a standard perturbation cycle (e.g., 10 seconds), two to three windows can be designed, with each window lasting between 1 and 5 seconds. A thermal buffer zone is set between the windows to prevent local sintering caused by continuous high-temperature reactions.

[0066] To achieve a high degree of synchronization between carbon source release and oxygen-enriched flow perturbation, this invention constructs a carbon-oxygen phase coupling function Φ(Δt) to describe the time offset Δt between the peak carbon release and the peak oxygen-enriched flow velocity. The function is defined as follows: Where Δt is the difference between the peak time of carbon source feeding and the peak time of oxygen enrichment disturbance (in seconds), and τ is the expected synchronization tolerance, which is set to 0.5 seconds based on experience.

[0067] When Δt approaches 0, Φ(Δt) approaches 1, indicating that carbon release and oxygen enrichment disturbance are highly synchronized; when Δt exceeds τ, Φ(Δt) decreases significantly, indicating phase decoupling.

[0068] By setting Φ(Δt) ≥ 0.8 as the effective synchronization threshold, the system will continuously detect the degree of carbon-oxygen phase matching in the current cycle. If it is lower than this value, the adjustment mechanism will be triggered.

[0069] To ensure the synchronization of carbon source supply and oxygen enrichment flow and the continuous optimization of window efficiency, this invention sets up a fuzzy PID control algorithm as a feedback control strategy. Its control objective is to minimize the Φ(Δt) deviation and maintain the stability of the reduction window efficiency E_w.

[0070] The fuzzy variables in the control system are defined as follows: Input 1: Current phase difference level (small, medium, large); Input 2: Rate of temperature change (positive, steady, negative); Input 3: Coupled region disturbance stability (high, medium, low); Outputs: Carbon source advance feeding amount Δq, oxygen enrichment flow rate adjustment range Δv.

[0071] Control rule base, for example: IF phase difference is large and temperature change is negative; THEN advance feeding amount is large. The IF phase difference is medium and the disturbance stability is low. The THEN oxygen-enriched flow rate adjustment range is medium.

[0072] The controller refreshes the adjustment strategy every 10 seconds to ensure dynamic responsiveness.

[0073] The response efficiency E_w of the recovery window is quantified in the following way: Where η_C is the carbon conversion rate (the proportion of carbon participating in the reaction), η_O is the oxygen utilization rate (the proportion of oxygen participating in the reduction reaction per unit time), and α and β are weighting factors, which are set to 0.6 and 0.4 by default.

[0074] If E_w is below 90% of the periodic average for three consecutive windows, the rhythm function q(t) is automatically recalculated, and the nozzle angle is fine-tuned and the carbon source distribution is locally optimized. If E_w recovers and increases by more than 5% within 30 seconds, this parameter will be fixed to the current model configuration and written into the predictive control library.

[0075] This invention employs a multi-point infrared gas analyzer (NDIR) to detect the spatial distribution of exhaust gas at the reactor end. Sensors are positioned at multiple locations within the exhaust gas emission channel, enabling real-time acquisition of the following key indicators: Carbon monoxide volume fraction (CO%) carbon dioxide volume fraction ( ); Hydrogen gas integral ( ); Exhaust gas temperature and flow rate information.

[0076] The above data can be used to determine whether the local reduction reaction is complete. The specific method for determining this is as follows: If the CO volume fraction in the exhaust gas of a certain area is greater than 10%, and If the volume fraction is less than 5%, the region is defined as a high residual reducing gas region; If the volume fraction of H2 is greater than 3%, the area can also be considered to contain recyclable reducing gas.

[0077] This definition standard is an empirical threshold, which can be set to CO > 8% based on specific process optimizations. < 6% > 2%.

[0078] The coordinates and values ​​of these detection points are input into the exhaust gas management module. A spatial distribution map of the exhaust gas reducing gas is constructed using two-dimensional interpolation or three-dimensional fitting methods, and a priority extraction region matrix is ​​output for the exhaust gas guidance system to retrieve.

[0079] To achieve precise capture and guidance of high residual reducing gases, this invention designs a switchable multi-port tail gas extraction system. The device is located at the tail end of the reactor and specifically includes: Three to five exhaust gas extraction ports are arranged horizontally. Each port is equipped with an independent electrically operated valve, flow meter, and pressure sensor; All ports are independently opened / closed and the pumping rate is adjusted via a program control module.

[0080] At the end of the reaction, the system selects the area with the highest residual gas concentration as the main extraction port based on the aforementioned tail gas distribution map, and dynamically adjusts other ports to auxiliary or closed states.

[0081] To prevent airflow disturbances from affecting the main reaction zone, all extraction pipelines are equipped with back pressure control valves and anti-backflow check valves. The system pressure is controlled slightly lower than that of the main reaction zone by 0.01 to 0.02 MPa to create a stable negative pressure for extraction without causing reverse gas movement.

[0082] The extracted high-temperature exhaust gas, rich in reducing components, is not directly discharged into the atmosphere, but is introduced into the preheating zone at the front end of the reactor through pipelines for heat recovery and carbon reuse.

[0083] The preheating system structure is as follows: The exhaust gas heat exchanger can be either a cross-flow or parallel-flow plate heat exchange unit. The newly introduced iron-containing material and biomass carbon source mixture first passes through this heat exchanger to exchange sensible heat with the exhaust gas. The heat exchange efficiency is controlled at 60% to 80%, the outlet temperature of the new material is increased to 150 to 250°C, and the exhaust gas temperature is reduced to below 150°C.

[0084] In addition, a portion of the exhaust gas is introduced into the carbon source preheating chamber to heat up the unpyrolyzed carbon source, stimulate its microporous structure, and enhance its subsequent activity and reaction rate.

[0085] To prevent exhaust gas with insufficient calorific value from entering the system and disrupting the overall temperature balance, an exhaust gas introduction threshold condition is set: The inlet system will automatically shut down when the CO concentration is below 8% or the gas temperature is below 400°C. The exhaust bypass emission channel is activated, and the exhaust gas is discharged into a safe area after being purified by dust removal.

[0086] To evaluate the effectiveness of exhaust gas recovery in carbon utilization, a carbon efficiency recovery rate model R_c is established, defined as follows: Where M_r represents the total molar amount of CO and H2 in the recovered tail gas (calculated under standard conditions); M_c represents the total molar amount of carbon source added in the current cycle.

[0087] This ratio reflects how much of the added carbon source is "unutilized" in the exhaust gas and successfully recovered and reheated. Based on experimental data and thermodynamic simulations, a recovery level of R_c ≥ 0.6 (i.e., 60%) is considered good. The system compares the R_c value of each cycle with the amount of carbon source input and automatically optimizes according to the following rules: when R_c is below 60% for three consecutive cycles, the peak value of the rhythm function q(t) is automatically reduced by 5%; the nozzle arrangement and disturbance frequency are re-evaluated using a CFD model to avoid concentrated release of carbon source without full utilization; the optimized parameters are stored in the model database as reference input for intelligent control in subsequent cycles.

[0088] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for using biomass carbon source to reduce iron-containing materials via oxygen-enriched side-blowing, characterized in that: include: Step S1: Load carbon-containing cold-solidified pellets with a particle size range of 5-45mm into the oxygen-enriched side-blowing device, and obtain the temperature change inside the furnace by monitoring the cooling water temperature. Step S2: Mix biomass pellets with iron-containing materials at a mass fraction of 5-20% to obtain cold-fixed pellets of 5-45mm. Step S3: Introduce an oxygen-enriched flow with an oxygen concentration of 40% to 70% into the oxygen-enriched side-blowing channel, and adjust the side-blowing angle so that the oxygen cuts into the iron-containing material layer at an angle of 10° to 20° in the horizontal direction, forming a multi-level turbulent vortex field with the biomass carbon source mixing layer. Step S4: Based on the multi-point temperature distribution information obtained by the temperature control thermocouple array in step S1, establish a temperature field-carbon gas release coupling model, reverse the region where the biomass carbon source gasification release path coincides with the main oxygen channel, and calculate the optimal release rhythm function. Step S5: Utilize rhythm functions to regulate the biomass carbon source feeding rate and the instantaneous flow rate of oxygen-enriched gas to form a dynamic alternating local reduction window; Step S6: At the end of the reaction, adjust the tail gas extraction path according to the reduction conversion rate distribution of iron-containing materials, and introduce the high residual reducing gas into the preheating zone to realize calorific value recovery and carbon efficiency reuse.

2. The method for reducing iron-containing materials using biomass carbon source according to claim 1, characterized in that: in, The construction of the temperature field-carbon release coupling model includes: Temperature data at different depths and locations are collected in real time during the reaction process using a temperature-controlled thermocouple array to ensure the acquisition of continuous temperature change curves; A three-dimensional temperature distribution matrix is ​​constructed based on the collected data, and the region between thermocouples is compensated and fitted using linear interpolation to obtain a complete spatial temperature field. The temperature distribution is superimposed on the location of the carbon source, and the thermal activation zone is set according to the critical starting temperature of the pyrolysis reaction. The thermal activation zone is defined as a spatial subdomain with a temperature greater than or equal to 450℃.

3. The method for reducing iron-containing materials by using biomass carbon source according to claim 2, characterized in that: in, The method for reverse-engineering the carbon release path includes: Based on the superposition of the spatial distribution function of carbon source particles and temperature field data, the heat conduction rate and local temperature gradient are calculated using the finite element method. By establishing a set of carbon source pyrolysis kinetic equations, the carbon generation rate in each unit region is determined. The first-order reaction kinetic model is preferred, with its reaction rate constant following the Arrhenius formula, and the thermally activated region is used as the input boundary condition. By combining the oxygen-enriched flow velocity vector field, the region where the carbon release area intersects with the main oxygen channel is marked as the effective coupling domain, and its overlapping volume fraction is used to measure the cooperative efficiency of the reaction.

4. The method for reducing iron-containing materials by using biomass carbon source according to claim 3, characterized in that: in, The calculation of the optimal release rhythm function includes: The effective coupling domain is integrated over time to extract the synchronization between carbon release and oxygen main flux. The coupling index R is calculated and defined as the reciprocal of the square integral of the difference between the ratio of carbon to oxygen molar flux per unit volume and the target ratio. Based on the above coupling index R, an optimization objective function is constructed, and a genetic algorithm is used for multi-parameter iteration. The optimized input parameters include carbon source feed rate, carbon source distribution density, side-blown oxygen flow rate, and nozzle opening and closing frequency. The final output rhythm function is a function of the carbon source supply rate and time, in the form q(t), where t is the reaction time and q is the carbon source supply rate per unit time, achieving phase coincidence between the peak carbon release and the peak oxygen enrichment disturbance.

5. The method for reducing iron-containing materials by oxygen-enriched side-blowing using biomass carbon source according to claim 1, characterized in that: in, The method of regulating the biomass carbon source feeding rate and the instantaneous flow rate of oxygen-enriched gas using a rhythm function specifically includes: The generated rhythm function q(t) is used as an input variable to link the execution modules in the carbon source feeding system and the oxygen-enriched injection system respectively. The carbon source feeding system adopts a screw feeder controlled by a stepper motor. Its feeding rate responds in real time to the change of the q(t) function value, and the adjustment frequency is not less than 1 Hz. The oxygen-enriched jet system controls the gas flow rate through servo valves, with an opening change response time of less than 1 second, ensuring that the oxygen-enriched flow rate reaches its maximum value at the rhythm peak.

6. The method for reducing iron-containing materials by using biomass carbon source according to claim 1, characterized in that: in, The adjustment of the exhaust gas extraction path based on the reduction conversion rate distribution of iron-containing materials specifically includes: The carbon monoxide to carbon dioxide concentration ratio in the tail gas at different locations at the end of the reaction was obtained by using a multi-point infrared online gas analyzer, and the degree of local reduction reaction was calculated. The region with a carbon monoxide volume fraction higher than 10% and a carbon dioxide volume fraction lower than 5% is defined as the high residual reducing gas region. The optimal exhaust gas extraction port is automatically selected based on the location coordinates of the high residual reducing gas zone.

7. The method for reducing iron-containing materials by oxygen-enriched side-blowing using biomass carbon source according to claim 1, characterized in that: in, The temperature-controlled reactive thermocouple array is layered and embedded along the thickness direction of the material layer, specifically including: A layer of thermocouple sensing points is set on the upper and lower surfaces of the material layer to obtain the difference in heat exchange rate between the upper and lower surfaces. Multiple thermocouple nodes are vertically arranged at 10 mm intervals inside the material layer to form a three-dimensional temperature monitoring grid. Each thermocouple node is connected to the main controller via a high-speed data acquisition module, enabling dynamic monitoring.

8. The method for reducing iron-containing materials by oxygen-enriched side-blowing using biomass carbon source according to claim 1, characterized in that: in, The interaction process between the perturbation vortex structure and carbon release was optimized through CFD simulation, specifically including: A three-dimensional simulation model was constructed, which included the nozzle structure, material layer porosity, and carbon source distribution. The gas flow boundary conditions were set using non-slip boundaries. Turbulence calculations were performed using the Reynolds stress model or the large eddy simulation model, and the degree of overlap between the airflow path and the carbon release path was simulated by combining the gas-solid coupling algorithm. Based on the simulation results, the nozzle layout was optimized to ensure that the average residence time of the local vortex structure in the reaction zone is not less than 0.3 seconds.

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