Device and application method for biomass multi-path coordinated reduction of iron ore

Abstract

The application provides a biomass multi-path collaborative iron ore reduction device and application method, and relates to the technical field of iron ore reduction. The biomass multi-path collaborative iron ore reduction device comprises a biomass supply and distribution unit, a first circulating fluidized bed system, a second circulating fluidized bed system and a gas circulation and energy integration system. The method is prepared by integrating the device structure of biomass combustion heat supply, gasification gas supply and multi-stage fluidized bed reduction, and comprises biomass distribution and energy conversion, iron ore preheating and solid-solid separation, multi-path collaborative reduction and agglomeration inhibition, and energy closed loop and near zero emission. Low-carbon, high-energy-efficient and high-purity iron products are prepared. The method is stable, easy to implement, low in cost, high in efficiency, and beneficial to industrial large-scale production and popularization and application.

Description

Technical Field

[0001] This invention relates to the technical field of iron ore reduction, and in particular to an apparatus and application method for the multi-pathway synergistic reduction of iron ore by biomass. Background Technology

[0002] To achieve the "dual carbon" goal, it is urgent to develop new metallurgical processes that are low-carbon or even zero-carbon.

[0003] Currently, the low-carbon metallurgical technologies related to this invention are mainly classified into the following categories: 1. Hydrogen-rich blast furnace smelting technology: Based on existing blast furnaces, this technology partially replaces coke and pulverized coal by injecting natural gas, coke oven gas, or hydrogen from the tuyeres. Theoretically, it can achieve a carbon emission reduction of 10%-30%, but it cannot achieve zero carbon emissions. For example, the ULCOS project in Europe and Baowu Group in China are conducting industrial trials in this field.

[0004] 2. Gas-based direct reduction shaft furnace technology: This technology is currently the mainstream gas-based direct reduction process, represented by the MIDREX and HYL-III methods. It uses syngas (H2+CO) produced from natural gas through catalytic cracking or partial oxidation as a reducing agent to reduce lump ore or pellets to direct reduced iron (DRI) within a shaft furnace. Although this process eliminates the coking and sintering steps, reducing carbon emissions by approximately 40%-60% compared to traditional blast furnaces, its reducing gas source still relies on fossil fuels (natural gas). Furthermore, China has scarce natural gas resources, and most processes adopt a "coal-to-gas + shaft furnace" approach, resulting in limited emission reduction effects and a complex process flow.

[0005] 3. Direct hydrogen reduction technology: This is one of the most promising directions in zero-carbon metallurgy, using 100% H2 as a reducing agent, with completely zero carbon emissions in the product. Existing research and technical solutions mainly focus on the adaptive modification of vertical shaft furnaces. However, when using direct hydrogen reduction in vertical shaft furnaces, the low heat capacity and strong endothermic effect of H2 can easily lead to excessively low temperatures in the lower part of the furnace, requiring a large amount of additional heat, thus posing a challenge to the system's thermal efficiency.

[0006] 4. Biomass in Iron and Steel Metallurgy: Currently, the application of biomass in the iron and steel industry is in the exploratory stage, and the main methods include: (1) Blast furnace injection: Biomass char is mixed with pulverized coal and injected into the blast furnace as part of the reducing agent and fuel.

[0007] (2) Biomass briquettes: Biomass is mixed with iron ore powder to make composite furnace charge to increase the mechanical strength of pellets for use in blast furnaces or direct reduction processes.

[0008] (3) As a reducing gas: Biomass is gasified to produce syngas, which is used to reduce iron ore.

[0009] Chinese patent CN109680114A discloses a system and method for pulverized coal gasification and synergistic iron ore reduction. The system includes a pyrolysis gasification device, a reduction device, and a first cyclone separator. The method includes what? Obviously, this system and method have technical defects such as dependence on fossil energy (coal, natural gas), single reduction path, inability to directly use iron ore powder, and low system energy efficiency.

[0010] However, these existing technologies have the following problems: 1) Whether it is hydrogen-rich blast furnace or gas-based vertical shaft furnace, the reducing agent essentially contains carbon elements (CO or C), and the reduction will inevitably produce CO2, which belongs to "low carbon" rather than "zero carbon" technology.

[0011] 2) Blast furnace and vertical shaft furnace processes require the use of high-grade, high-strength lump ore or pellets, which places stringent requirements on raw material pretreatment (ore beneficiation, pelletizing), making it impossible to directly use widely available iron ore powder.

[0012] 3) In a fully hydrogen-reduced environment, the only product is H2O. When the partial pressure of water vapor in the system increases, the reduction reaction (Fe2O3) is accelerated. x O γ +yH2 The reduction of iron by H₂ (xFe + yH₂O) proceeds in the reverse direction, inhibiting the reduction process and reducing the metallization rate. Furthermore, the reduction of iron by H₂ is a strongly endothermic reaction, while the heat transfer efficiency in the vertical furnace is relatively low, leading to a decrease in the reaction rate and an increase in energy consumption.

[0013] 4) During high-temperature reduction, iron ore particles are prone to adhesion and sintering, which is a key factor limiting fluidized bed reduction processes. This can lead to disruption of the fluidization state, bed deactivation, and even equipment shutdown. Current technologies lack economical and effective means to suppress this phenomenon.

[0014] 5) Existing technologies have failed to achieve graded and efficient utilization of biomass. Simply burning or gasifying biomass ignores the high reactivity, porous structure, and low impurity characteristics of the derived coke, and fails to apply it as a functional material in the reduction process. Summary of the Invention

[0015] The main objective of this invention is to address the technical problems of existing gas-based direct reduction of iron, such as the inability to completely solve CO2 emissions, the suppression of reduction efficiency by water vapor partial pressure in the all-hydrogen reduction process, and the easy adhesion and loss of iron ore flow during fluidized bed reduction. Therefore, a device and application method for the multi-pathway synergistic reduction of iron ore using biomass are proposed, which can solve the aforementioned problems.

[0016] The technical solution is as follows: A biomass multi-path synergistic reduction device for iron ore, comprising a biomass supply and diversion unit, a primary circulating fluidized bed system, a secondary circulating fluidized bed system, and a gas circulation and energy integration system.

[0017] Optionally, the biomass supply and distribution unit includes a biomass silo for storing and transporting biomass raw materials, and a distributor for distributing the biomass raw materials to two paths for combustion and gasification according to a preset ratio. The function of the distributor is to distribute the biomass raw materials to the two paths according to the preset ratio: one path is used for direct combustion and heating, and the other path is used for gasification to produce syngas. The outlet of the biomass silo is connected to the distributor through a feeder. This enables a stable and controllable supply of biomass raw materials.

[0018] Optionally, the primary circulating fluidized bed system includes a combustion furnace, the bottom of which is divided into two regions—a combustion zone and a gasification zone—by an air distribution plate to meet differentiated reaction conditions; a fluidizing air inlet connected to the tail gas pipeline of the primary circulating fluidized bed is provided below the air distribution plate; an iron ore powder inlet is provided at the top of the combustion furnace; the top of the combustion furnace is connected to the air inlet of the primary gas-solid separator via a pipeline; and a solid distributor is provided directly below the solid outlet of the primary gas-solid separator.

[0019] Optionally, the primary gas-solid separator separates high-temperature gas from solid particles (preheated iron ore powder, biomass coke, and ash); the solid distributor...

[0020] Optionally, the combustion chamber is a vertical cylindrical container. The combustion zone has a first biomass inlet and a gas inlet. The gas inlet contains a mixture of air and O2 after passing through an air separator. Its function is to provide the main heat required by the system through combustion. The gasification zone has a second biomass inlet and an H2O inlet for the tail gas from the secondary circulating fluidized bed after passing through a condenser. Its function is to convert solid biomass into syngas rich in CO and H2 as a reducing agent donor for the secondary circulating fluidized bed.

[0021] Optionally, the solids distributor is provided with a first discharge port and a second discharge outlet. The first discharge port is connected to the bottom of the combustion furnace via a return pipe to maintain material circulation in the primary bed. The second discharge outlet connects the iron ore powder from the iron ore powder inlet to the lower part of the reduction reaction zone of the secondary circulating fluidized bed via a conveying pipeline. The function of the solids distributor is to dynamically adjust the distribution of solid materials within the system, enriching the iron ore powder through density differences to achieve the conveying of preheated ore powder to the secondary bed.

[0022] Optionally, the iron ore powder inlet is used to feed iron ore powder to be preheated, the main component of which is Fe2O3, which serves as a catalyst for biomass gasification while preheating; the fluidizing air inlet is used to utilize the waste heat and chemical energy of the primary bed flue gas, while providing the fluidizing medium (biomass ash).

[0023] Optionally, the secondary circulating fluidized bed system includes a reduction reaction furnace, the bottom of which is provided with an air distribution plate, a solid inlet, a gas inlet, and an iron discharge port.

[0024] Optionally, the reduction reaction furnace is a vertical cylindrical container, the gas inlet is used to introduce H2 from the water electrolysis unit and syngas generated in the primary fluidized bed gasification zone, and the iron discharge port is used to discharge the metallic iron produced by reduction.

[0025] Optionally, the solid inlet is connected to the second outlet of the solid distributor for introducing preheated iron ore powder and residual biomass coke from the bottom of the primary fluidized bed; the top outlet of the reduction reactor is connected to the inlet of the secondary gas-solid separator, which separates the reacted gas from the incompletely reacted solid particles, realizing the circulation of solid materials in the secondary bed and ensuring high reduction and metallization rates; a return feed inlet is provided directly below the solid outlet of the secondary gas-solid separator, and the outlet of the return feedlet is connected to the upper part of the reduction reactor, which transports the incompletely reacted solid particles back to the reaction zone.

[0026] Optionally, the gas circulation and energy integration system includes a primary gas circulation pipeline and a secondary gas circulation pipeline. The primary gas circulation pipeline includes a connecting pipeline between the gas outlet of the primary gas-solid separator and the inlet of the gasification zone of the combustion furnace, wherein the H2O and CO2 after combustion are used as gasifying agents and directly used in the biomass gasification process. The secondary gas circulation pipeline includes a connecting pipeline between the gas outlet of the secondary gas-solid separator and the gas inlet at the bottom of the reduction reaction furnace.

[0027] Optionally, a water vapor concentration detection device is installed in the secondary gas circulation pipeline. When the concentration is less than 3%, the gas outlet of the secondary gas-solid separator is connected to the fluidizing air inlet at the bottom of the secondary circulating fluidized bed furnace to participate in the circulation as supplementary reducing gas. When the concentration exceeds 3%, the waste heat and unreacted chemical energy (H2, CO) of the high-temperature flue gas (CFB2 reduction tail gas) of the secondary circulating fluidized bed system are recovered to the primary circulating fluidized bed system to improve the overall system energy efficiency.

[0028] An application method for the biomass multi-path synergistic reduction of iron ore apparatus, comprising the following steps: S1. Biomass Diversion and Energy Conversion: Based on the composition of the iron ore powder to be reduced and the final iron product metallization rate requirement, the biomass raw material and its diversion ratio in the diverter are selected. The biomass raw material is divided into two paths by the diverter: one path of biomass raw material is transported into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO + H2; the other path of biomass raw material enters the combustion zone of the combustion furnace and co-combusts with hydrogen to provide the main heat source for the system. S2. Iron ore preheating and solid-solid separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas and circulating hot bed material in the combustion furnace and is rapidly preheated; the preheated mixture is captured by the primary gas-solid separator and sorted by the solid distributor based on density differences: the denser hot iron ore powder preferentially enters the secondary circulating fluidized bed system, while the light biomass coke and ash are returned to the primary circulating fluidized bed system for circulation or discharged; S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reaction furnace of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas and biomass coke. Biomass coke acts as an in-situ coating agent, covering the particle surface of hot iron ore powder, thereby effectively blocking the connection of iron grains and completely solving the problem of fluidized bed adhesion and flow loss. S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air to achieve the recycling of chemical and thermal energy. The system's only carbon source is biomass feedstock (carbon neutralization), and the hydrogen source is electrolyzed water (zero carbon), thus achieving near-zero carbon emissions throughout the entire process.

[0029] Alternatively, biomass raw materials include sawdust, straw, rice husks, etc., which are widely available.

[0030] Alternatively, iron ore powder smaller than 8mm can be used directly, eliminating the need for agglomeration.

[0031] Optionally, the rapid preheating rate is 90-180℃ / min, the preheating temperature is 800-950℃, and the preheating time is 5-12min; the density of the hot iron ore powder is greater than 4.3-5.0 g / cm³. 3 .

[0032] Optionally, the temperature of the synergistic reduction is 780-950℃ and the time is 35-90min; the thickness of the biomass coke coating on the surface of the hot iron ore powder particles is 0.02-0.20mm.

[0033] Optionally, the synergistic effect of multiple reducing agents (H2 / CO / biochar) can increase the reduction rate by more than 30%.

[0034] Optionally, the final metallization rate of iron products is stabilized at over 91%, which is better than that of traditional gas-based shaft furnaces (75-85%) and single hydrogen-based fluidized beds (typically <85% due to water vapor inhibition).

[0035] Optionally, the carbon emission intensity is less than 0.1 ton CO2 / ton iron, which is at least 95% lower than that of a traditional blast furnace.

[0036] Optionally, after the secondary circulating fluidized bed system has been running continuously for 120 hours, a shutdown inspection revealed that there were no large pieces of coke or agglomerated material inside the bed, and the fluidizing air pressure was stable.

[0037] Optionally, energy balance calculations show that, thanks to gas circulation, the system’s overall thermal efficiency exceeds 80%.

[0038] Technical principle of the invention: The core working principle of this invention lies in achieving efficient zero-carbon reduction of iron ore by decoupling biomass diversion and utilization from the multi-stage fluidized bed process.

[0039] To address the technical challenges of existing gas-based direct reduction of iron, such as the inability to completely resolve CO2 emissions, the suppression of reduction efficiency by water vapor partial pressure in the all-hydrogen reduction process, and the tendency of iron ore to agglomerate and lose flow during fluidized bed reduction, this invention provides a multi-stage circulating fluidized bed method for the synergistic reduction of iron ore via biomass. This method includes biomass diversion and energy conversion, iron ore preheating and solid-solid separation, synergistic reduction via multiple pathways and agglomeration suppression, and energy closed-loop and near-zero emissions, thereby achieving near-zero CO2 emissions, efficient reduction, and stable operation.

[0040] Another objective of this invention is to provide an apparatus for implementing the above-mentioned method. This apparatus integrates biomass diversion, combustion, gasification, and multi-stage fluidized bed reduction, possessing the characteristics of high system energy efficiency, strong raw material adaptability, and high operational flexibility. Therefore, the core of the apparatus system of this invention lies in the integrated synergistic system of biomass combustion heating, gasification gas supply, and multi-stage fluidized bed reduction. Specifically: a biomass supply and diversion unit is used for the stable and controllable supply of biomass raw materials, as well as the direct combustion heating and gasification of biomass raw materials to produce syngas; a primary circulating fluidized bed system includes a biomass gasification and combustion section and a preheating section for iron ore powder; a secondary circulating fluidized bed system includes an iron ore powder reduction section; and a gas circulation and energy integration system includes the recycling of primary gas (H2O and CO2 after combustion) and secondary gas (supplementary reducing gas and CFB2 reduction tail gas).

[0041] Another objective of this invention is to provide a method for using biomass coke as an in-situ coating agent, which effectively inhibits the adhesion of iron particles during the reduction process by controlling its mass ratio with iron ore powder, while promoting synergistic reduction with H2, thereby improving the metallization rate and product purity.

[0042] The above technical solution has at least the following advantages compared with the existing technology: The above-mentioned solution, proposed by the present invention, is a method for improving the high-cycle fatigue performance of TiAl alloy by shot peening. It can solve the technical problems in the prior art, such as the inability to achieve orders-of-magnitude improvement in the high-cycle fatigue performance of TiAl alloy, poor practicality, low depth and uniformity of residual compressive stress field distribution, and the introduction of residual compressive stress often accompanied by a significant increase in surface roughness and the generation of surface damage such as microcracks.

[0043] The method of this invention combines biomass energy with water electrolysis to produce hydrogen, thereby eliminating dependence on fossil fuels and achieving near-zero carbon dioxide emissions in the ironmaking process from the source. The carbon emission intensity is <0.1 tons CO2 / ton of iron, which is more than 95% lower than that of traditional blast furnaces (about 1.8 tons).

[0044] This invention decouples the "preheating" and "deep reduction" processes of iron ore through a multi-stage circulating fluidized bed design. In the first-stage circulating fluidized bed system, biomass combustion provides heat; even if steam is generated, it only affects the preheating stage and does not affect the deep reduction in the second-stage circulating fluidized bed system, ensuring a high metallization rate of the product. Specifically, the metallization rate reaches 91-95%, which is superior to traditional gas-based vertical shaft furnaces (75-85%) and single hydrogen-based fluidized beds (typically <85% due to steam suppression).

[0045] The method of this invention introduces biomass coke (a byproduct of primary heating) as an in-situ coating agent to form a physical isolation layer, which fundamentally inhibits the adhesion between iron grains and completely solves the adhesion problem; in particular, the secondary circulating fluidized bed system can operate continuously and stably for more than 120 hours without adhesion, breaking through the core bottleneck of fluidized bed ironmaking industrialization.

[0046] This invention enables the efficient cascade utilization of biomass, allowing it to serve simultaneously as fuel, gasification feedstock (producing reducing gas), and carbon coating agent, thereby improving biomass utilization efficiency and economic benefits. Therefore, it boasts strong raw material adaptability and low cost: 0-8mm iron ore powder can be used directly, eliminating the need for agglomeration; biomass sources are wide-ranging, and the system is compatible with different types (wood chips, straw, rice husks, etc.).

[0047] The method of this invention has a high degree of energy efficiency integration: tail gas recycling makes the system thermal efficiency >80%, and the coupling of water electrolysis for hydrogen production and biomass energy realizes the maximum cascade utilization of energy. Through simulation experiments, CFD simulation confirmed that the atmosphere in the combustion zone and gasification zone in the primary bed coexists stably; SEM images show that a complete biomass char coating layer is formed on the surface of iron particles.

[0048] This technology provides a complete technological path for green, zero-carbon metallurgy, which is expected to reduce the steel industry's dependence on fossil fuels and provide a key technological solution for achieving the industry-wide goal of "carbon neutrality." The "zero-carbon steel" or "green steel" produced using this process will become an important raw material for downstream high-end manufacturing (such as new energy vehicles, high-end equipment, and green buildings), meeting the carbon footprint requirements of the supply chain.

[0049] In summary, compared with existing technologies, the method of this invention integrates the device structure of biomass combustion heating, gasification gas supply and multi-stage fluidized bed reduction, and proposes methods including biomass diversion and energy conversion, iron ore preheating and solid-solid separation, multi-path synergistic reduction and adhesion inhibition, and energy closed loop and near-zero emissions to prepare low-carbon, high-energy-efficiency, and high-purity iron products. This method is stable, easy to implement, low-cost, and highly efficient, which is conducive to large-scale industrial production and promotion. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of a biomass multi-path synergistic reduction device for iron ore according to the present invention. Detailed Implementation

[0052] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0053] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0054] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.

[0055] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0056] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0057] A biomass multi-pathway synergistic reduction device for iron ore, such as Figure 1 As shown, the biomass multi-path synergistic reduction device for iron ore includes a biomass supply and diversion unit, a primary circulating fluidized bed system, a secondary circulating fluidized bed system, and a gas circulation and energy integration system.

[0058] Specifically, the biomass supply and distribution unit includes a biomass silo for storing and transporting biomass raw materials, and a distributor for distributing the biomass raw materials to two paths for combustion and gasification according to a preset ratio. The distributor's function is to distribute the biomass raw materials to the two paths according to a preset ratio: one path is used for direct combustion and heating, and the other path is used for gasification to produce syngas. The outlet of the biomass silo is connected to the distributor through a feeder, which enables a stable and controllable supply of biomass raw materials.

[0059] Specifically, the primary circulating fluidized bed system includes a combustion furnace, the bottom of which is divided into two regions—a combustion zone and a gasification zone—by an air distribution plate to meet differentiated reaction conditions; a fluidizing air inlet connected to the tail gas pipeline of the primary circulating fluidized bed is provided below the air distribution plate; an iron ore powder inlet is provided at the top of the combustion furnace; the top of the combustion furnace is connected to the air inlet of the primary gas-solid separator via a pipeline; and a solid distributor is provided directly below the solid outlet of the primary gas-solid separator.

[0060] Specifically, the primary gas-solid separator is used to separate high-temperature gas from solid particles (preheated iron ore powder, biomass coke, and ash); the solid distributor...

[0061] Specifically, the combustion chamber is a vertical cylindrical container. The combustion zone has a first biomass inlet and a gas inlet. The gas inlet contains a mixture of air and O2 after passing through an air separator. Its function is to provide the main heat required by the system through combustion. The gasification zone has a second biomass inlet and an H2O inlet for the tail gas from the secondary circulating fluidized bed after passing through a condenser. Its function is to convert solid biomass into syngas rich in CO and H2 as a reducing agent donor for the secondary circulating fluidized bed.

[0062] Specifically, the solids distributor is equipped with a first discharge port and a second discharge port. The first discharge port is connected to the bottom of the combustion furnace via a return pipe to maintain material circulation in the primary bed. The second discharge port connects the iron ore powder from the iron ore powder inlet to the lower part of the reduction reaction zone of the secondary circulating fluidized bed via a conveying pipeline. The function of the solids distributor is to dynamically adjust the distribution of solid materials within the system, enriching the iron ore powder through density differences to achieve the conveying of preheated ore powder to the secondary bed.

[0063] Specifically, the iron ore powder inlet is used to feed iron ore powder to be preheated, the main component of which is Fe2O3, which acts as a catalyst for biomass gasification while preheating; the fluidizing air inlet is used to utilize the waste heat and chemical energy of the primary bed flue gas, while providing the fluidizing medium (biomass ash).

[0064] Specifically, the secondary circulating fluidized bed system includes a reduction reaction furnace, the bottom of which is provided with an air distribution plate, a solid inlet, a gas inlet, and an iron discharge port.

[0065] Specifically, the reduction reaction furnace is a vertical cylindrical container, the gas inlet is used to introduce H2 from the water electrolysis unit and syngas generated in the primary fluidized bed gasification zone, and the iron outlet is used to discharge the metallic iron produced by reduction.

[0066] Specifically, the solid inlet is connected to the second outlet of the solid distributor for introducing preheated iron ore powder and residual biomass coke from the bottom of the primary fluidized bed; the top outlet of the reduction reactor is connected to the inlet of the secondary gas-solid separator, which separates the reacted gas from the incompletely reacted solid particles, enabling the solid material to circulate within the secondary bed and ensuring high reduction and metallization rates; a return feed inlet is located directly below the solid outlet of the secondary gas-solid separator, and the outlet of the return feedlet is connected to the upper part of the reduction reactor, which transports the incompletely reacted solid particles back to the reaction zone.

[0067] Specifically, the gas circulation and energy integration system includes a primary gas circulation pipeline and a secondary gas circulation pipeline. The primary gas circulation pipeline includes a connecting pipeline between the gas outlet of the primary gas-solid separator and the inlet of the gasification zone of the combustion furnace. The H2O and CO2 after combustion are used as gasifying agents and directly used in the biomass gasification process. The secondary gas circulation pipeline includes a connecting pipeline between the gas outlet of the secondary gas-solid separator and the gas inlet at the bottom of the reduction reaction furnace.

[0068] Specifically, a water vapor concentration detection device is installed in the secondary gas circulation pipeline. When the concentration is less than 3%, the gas outlet of the secondary gas-solid separator is connected to the fluidizing air inlet at the bottom of the secondary circulating fluidized bed furnace to participate in the circulation as supplementary reducing gas. When the concentration exceeds 3%, the waste heat and unreacted chemical energy (H2, CO) of the high-temperature flue gas (CFB2 reduction tail gas) of the secondary circulating fluidized bed system are recovered to the primary circulating fluidized bed system to improve the overall system energy efficiency.

[0069] An application method for the biomass multi-path synergistic reduction of iron ore apparatus, comprising the following steps: S1. Biomass Diversion and Energy Conversion: Based on the composition of the iron ore powder to be reduced and the final iron product metallization rate requirement, the biomass raw material and its diversion ratio in the diverter are selected. The biomass raw material is divided into two paths by the diverter: one path of biomass raw material is transported into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO + H2; the other path of biomass raw material enters the combustion zone of the combustion furnace and co-combusts with hydrogen to provide the main heat source for the system. S2. Iron ore preheating and solid-solid separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas and circulating hot bed material in the combustion furnace and is rapidly preheated; the preheated mixture is captured by the primary gas-solid separator and sorted by the solid distributor based on density differences: the denser hot iron ore powder preferentially enters the secondary circulating fluidized bed system, while the light biomass coke and ash are returned to the primary circulating fluidized bed system for circulation or discharged; S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reaction furnace of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas and biomass coke. Biomass coke acts as an in-situ coating agent, covering the particle surface of hot iron ore powder, thereby effectively blocking the connection of iron grains and completely solving the problem of fluidized bed adhesion and flow loss. S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air to achieve the recycling of chemical and thermal energy. The system's only carbon source is biomass feedstock (carbon neutralization), and the hydrogen source is electrolyzed water (zero carbon), thus achieving near-zero carbon emissions throughout the entire process.

[0070] In particular, biomass raw materials include sawdust, straw, rice husks, etc., and are widely available.

[0071] In particular, iron ore powder smaller than 8mm is used directly, eliminating the need for agglomeration.

[0072] Specifically, the rapid preheating rate is 90-180℃ / min, the preheating temperature is 800-950℃, and the preheating time is 5-12 min; the density of the hot iron ore powder is greater than 4.3-5.0 g / cm³. 3 .

[0073] Specifically, the temperature for the synergistic reduction is 780-950℃, and the time is 35-90 min; the thickness of the biomass coke coating on the surface of the hot iron ore powder particles is 0.02-0.20 mm.

[0074] In particular, the synergistic effect of multiple reducing agents (H2 / CO / biochar) increases the reduction rate by more than 30%.

[0075] In particular, the final metallization rate of iron products is stable at over 91%, which is better than that of traditional gas-based shaft furnaces (75-85%) and single hydrogen-based fluidized beds (usually <85% due to water vapor inhibition).

[0076] In particular, the carbon emission intensity is less than 0.1 tons of CO2 per ton of iron, which is at least 95% lower than that of a traditional blast furnace.

[0077] In particular, after the secondary circulating fluidized bed system had been running continuously for 120 hours, a shutdown inspection revealed that there were no large pieces of coke or agglomerated material inside the bed, and the fluidizing air pressure was stable.

[0078] In particular, energy balance calculations show that, thanks to gas circulation, the system’s overall thermal efficiency exceeds 80%.

[0079] Example 1

[0080] This embodiment describes an application method of the biomass multi-pathway synergistic reduction iron ore device, as described above. Figure 1 As shown, the application method of the biomass multi-path synergistic reduction iron ore device is as follows: S1. Biomass Diversion and Energy Conversion: Based on the raw material composition of the iron ore powder to be reduced (hematite powder <8mm) and the requirement of a final iron product metallization rate of over 95%, wood chip biomass raw material is selected, and its diversion ratio in the distributor is 50:50. The biomass raw material is divided into two paths by the distributor: one path of biomass raw material is transported into the gasification zone of the combustion furnace, where it reacts with water vapor to generate syngas of CO + H2; the other path of biomass raw material enters the combustion zone of the combustion furnace, where it is co-combusted with hydrogen to provide the main heat source for the system. S2. Iron Ore Preheating and Solid-Solid Separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas, and circulating hot bed material in the combustion furnace and rapidly preheated to 900℃ at a heating rate of 150℃ / min for 6 minutes. The preheated mixture is captured by a primary gas-solid separator and then sorted by a solid distributor based on density differences: higher density (density greater than 4.8 g / cm³) is selected from the solids. 3 Hot iron ore powder is preferentially fed into the secondary circulating fluidized bed system, while light biomass coke and ash are returned to the primary circulating fluidized bed system for recycling or discharged. S3. Multi-path Synergistic Reduction and Adhesion Suppression: In the reduction reactor of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas, and biomass coke. Biomass coke acts as an in-situ coating agent, covering the surface of the hot iron ore particles, effectively preventing iron grain aggregation and completely solving the fluidized bed adhesion and flow loss problem. The coke / iron ore ratio is 1:10, the synergistic reduction temperature is 850℃, and the time is 45 min. The biomass coke coating thickness on the surface of the hot iron ore particles is 0.05-0.15 mm. The synergistic effect of multiple reducing agents (H2 / CO / biomass coke) increases the reduction rate by 35%. S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air, realizing the recycling of chemical and thermal energy. The system's sole carbon source is biomass feedstock (carbon neutralization), and the hydrogen source is electrolytic water (zero carbon), thus achieving near-zero carbon emissions throughout the entire process. The final iron product metallization rate remains stable at over 95%.

[0081] In this embodiment, scanning electron microscopy (SEM) was performed on the discharged iron blocks. The results showed that the iron particles were clearly separated by a carbon layer, with no obvious sintering neck formation, which directly demonstrated the mechanism of biomass coke coating inhibiting adhesion. System carbon accounting showed that the carbon emission intensity was less than 0.1 tons of CO2 / ton of iron, which is about 95% lower than that of traditional blast furnaces, proving the effect of near-zero emissions.

[0082] After the secondary circulating fluidized bed system had been running continuously for 120 hours, a shutdown inspection revealed that there were no large pieces of coke or agglomerated material inside the bed, and the fluidizing air pressure was stable.

[0083] Energy balance calculations show that, thanks to gas circulation, the system’s overall thermal efficiency exceeds 80%.

[0084] Example 2

[0085] This embodiment describes an application method of the biomass multi-pathway synergistic reduction iron ore device, as described above. Figure 1 As shown, the application method of the biomass multi-path synergistic reduction iron ore device is as follows: S1. Biomass Diversion and Energy Conversion: Based on the raw material composition of the iron ore powder to be reduced (magnetite powder <8mm) and the requirement of a final iron product metallization rate of over 91%, rice husk biomass raw material is selected, and its diversion ratio in the distributor is 30:70. The biomass raw material is divided into two paths by the distributor: one path of biomass raw material is transported into the gasification zone of the combustion furnace, where it reacts with water vapor to generate syngas of CO + H2; the other path of biomass raw material enters the combustion zone of the combustion furnace, where it is co-combusted with hydrogen to provide the main heat source for the system. S2. Iron Ore Preheating and Solid-Solid Separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas, and circulating hot bed material in the combustion furnace and rapidly preheated to 880℃ at a heating rate of 120℃ / min for 8 minutes. The preheated mixture is captured by a primary gas-solid separator and then sorted by a solid distributor based on density differences: higher density (density greater than 4.6 g / cm³) is selected from the solids. 3 Hot iron ore powder is preferentially fed into the secondary circulating fluidized bed system, while light biomass coke and ash are returned to the primary circulating fluidized bed system for recycling or discharged. S3. Multi-path Synergistic Reduction and Adhesion Suppression: In the reduction reactor of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously synergistically reduced by hydrogen, syngas, and biomass coke, with a coke / iron powder ratio of 1:15. Biomass coke acts as an in-situ coating agent, covering the surface of the hot iron ore powder particles, effectively preventing iron grain aggregation and completely solving the fluidized bed adhesion and flow loss problem. The synergistic reduction temperature is 820℃, and the time is 60 min. The thickness of the biomass coke coating on the surface of the hot iron ore powder particles is 0.03-0.10 mm. The synergistic effect of multiple reducing agents (H2 / CO / biomass coke) increases the reduction rate by 32%. S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air, realizing the circulation of chemical and thermal energy. The system's sole carbon source is biomass feedstock (carbon neutralization), and the hydrogen source is electrolyzed water (zero carbon), thus achieving near-zero carbon emissions throughout the process. The final iron product metallization rate remained stable at over 91%, slightly lower than in Example 1, but demonstrating the system's adaptability to high-ash biomass. After 120 hours of continuous operation of the secondary fluidized bed, a shutdown inspection revealed no large clumps of coke or agglomerates within the bed, and the fluidizing air pressure remained stable, proving the long-term effectiveness of the process in suppressing agglomeration. Energy balance calculations show that, thanks to gas circulation, the system's overall thermal efficiency exceeds 80%.

[0086] In this embodiment, scanning electron microscopy (SEM) was performed on the discharged iron blocks. The results showed that the iron particles were clearly separated by a carbon layer, with no obvious sintering neck formation, which directly demonstrated the mechanism of biomass coke coating inhibiting adhesion. System carbon accounting showed that the carbon emission intensity was less than 0.05-0.1 tons of CO2 / ton of iron, which is about 95% lower than that of traditional blast furnaces, proving the effect of near-zero emissions.

[0087] As can be seen from the above, the present invention solves three major industry problems simultaneously—reduction efficiency, adhesion inhibition, and carbon emissions—through the aforementioned working mechanism.

[0088] Example 3

[0089] This embodiment describes an application method of the biomass multi-pathway synergistic reduction iron ore device, as described above. Figure 1 As shown, the application method of the biomass multi-path synergistic reduction iron ore device is as follows: S1. Biomass Diversion and Energy Conversion: Based on the raw material composition of the iron ore powder to be reduced (limonite powder with a particle size of 0-8mm and a Fe2O3·nH2O content ≥85%) and the requirement of a final iron product metallization rate of over 93%, straw biomass raw material is selected and its diversion ratio in the distributor is 40:60. The biomass raw material is divided into two paths by the distributor: one path of biomass raw material is transported into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO+H2; the other path of biomass raw material enters the combustion zone of the combustion furnace and co-combusts with hydrogen to provide the main heat source for the system.

[0090] S2. Iron Ore Preheating and Solid-Solid Separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas, and circulating hot bed material in the combustion furnace and rapidly preheated to 800℃ at a heating rate of 100℃ / min for 10min. The preheated mixture is then captured by a primary gas-solid separator and separated by a solid distributor based on density differences: higher density (greater than 4.3 g / cm³) is selected from the solids. 3 Hot iron ore powder is preferentially fed into the secondary circulating fluidized bed system, while light biomass coke and ash are returned to the primary circulating fluidized bed system for recycling or discharged.

[0091] S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reactor of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas, and biomass coke. Biomass coke acts as an in-situ coating agent, covering the surface of the hot iron ore powder particles, thereby effectively blocking iron grain bonding and completely solving the fluidized bed adhesion and flow loss problem. The coke / iron powder mass ratio is 1:8, the synergistic reduction temperature is 800℃, and the time is 75min. The thickness of the biomass coke coating on the surface of the hot iron ore powder particles is 0.08-0.20mm. The synergistic effect of multiple reducing agents (H2 / CO / biomass coke) increases the reduction rate by 32%.

[0092] S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air, realizing the circulation of chemical and thermal energy. The final metallization rate of iron products remains stable at 94.1%.

[0093] This embodiment verifies the system's processing capacity for low-grade limonite and straw biomass. SEM shows that a complete biochar coating layer forms on the surface of the iron particles, effectively inhibiting adhesion. System carbon accounting shows a carbon emission intensity of 0.07 tons of CO2 / ton of iron. After 120 hours of continuous operation, the secondary circulating fluidized bed system showed no adhesion, and the fluidizing air pressure remained stable. Energy balance calculations indicate that the system's overall thermal efficiency is 82%.

[0094] Example 4

[0095] This embodiment describes an application method of the biomass multi-pathway synergistic reduction iron ore device, as described above. Figure 1 As shown, the application method of the biomass multi-path synergistic reduction iron ore device is as follows: S1. Biomass Diversion and Energy Conversion: Based on the raw material composition of the iron ore powder to be reduced (hematite powder with a particle size of 0-2mm and a Fe2O3 content of ≥94%) and the requirement of a final iron product metallization rate of over 95%, wood chip biomass raw material is selected, and its diversion ratio in the distributor is 60:40. The biomass raw material is divided into two paths by the distributor: one path of biomass raw material is transported into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO+H2; the other path of biomass raw material enters the combustion zone of the combustion furnace and is co-combusted with hydrogen to provide the main heat source for the system.

[0096] S2. Iron Ore Preheating and Solid-Solid Separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas, and circulating hot bed material in the combustion furnace and rapidly preheated to 950℃ at a heating rate of 180℃ / min for 5 minutes. The preheated mixture is captured by a primary gas-solid separator and then sorted by a solid distributor based on density differences: higher density (density greater than 5.0 g / cm³) is selected from the solids. 3 Hot iron ore powder is preferentially fed into the secondary circulating fluidized bed system, while light biomass coke and ash are returned to the primary circulating fluidized bed system for recycling or discharged.

[0097] S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reactor of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas, and biomass coke. Biomass coke acts as an in-situ coating agent, covering the surface of hot iron ore powder particles, thereby effectively blocking iron grain bonding and completely solving the fluidized bed adhesion and flow loss problem. The coke / iron powder mass ratio is 1:12, the synergistic reduction temperature is 880℃, and the time is 35 min. The thickness of the biomass coke coating on the surface of hot iron ore powder particles is 0.04-0.12 mm. The synergistic effect of multiple reducing agents (H2 / CO / biomass coke) increases the reduction rate by 38%.

[0098] S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air, realizing the circulation of chemical and thermal energy. The final metallization rate of the iron product remains stable at 96.8%.

[0099] This embodiment verifies the process performance under high preheating temperature and high heating rate conditions. A higher preheating temperature (950℃) and a shorter reduction time (35 min) achieved the highest metallization rate of 96.8%, demonstrating the process's operational flexibility. SEM showed that the carbon coating layer on the iron particle surface was complete and uniform. System carbon accounting showed a carbon emission intensity of 0.05 tons of CO2 / ton of iron. No adhesion occurred after 120 hours of continuous operation of the two-stage circulating fluidized bed system. Energy balance calculations indicated a total system thermal efficiency of 84%.

[0100] Example 5

[0101] This embodiment describes an application method of the biomass multi-pathway synergistic reduction iron ore device, as described above. Figure 1 As shown, the application method of the biomass multi-path synergistic reduction iron ore device is as follows: S1. Biomass Diversion and Energy Conversion: Based on the raw material composition of the iron ore powder to be reduced (magnetite powder with a particle size of 0-6mm and a Fe3O4 content of ≥88%) and the requirement of a final iron product metallization rate of over 91%, rice husk biomass raw material is selected, and its diversion ratio in the distributor is 20:80. The biomass raw material is divided into two paths by the distributor: one path of biomass raw material is transported into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO+H2; the other path of biomass raw material enters the combustion zone of the combustion furnace and is co-combusted with hydrogen to provide the main heat source for the system.

[0102] S2. Iron Ore Preheating and Solid-Solid Separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas, and circulating hot bed material in the combustion furnace and rapidly preheated to 850℃ at a heating rate of 90℃ / min for 12 minutes. The preheated mixture is captured by a primary gas-solid separator and then sorted by a solid distributor based on density differences: higher density (density greater than 4.5 g / cm³) is selected from the solids. 3 Hot iron ore powder is preferentially fed into the secondary circulating fluidized bed system, while light biomass coke and ash are returned to the primary circulating fluidized bed system for recycling or discharged.

[0103] S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reactor of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously synergistically reduced by hydrogen, syngas, and biomass coke. Biomass coke acts as an in-situ coating agent, covering the surface of hot iron ore powder particles, thereby effectively blocking iron grain bonding and completely solving the fluidized bed adhesion and flow loss problem. The coke / iron powder mass ratio is 1:20, the synergistic reduction temperature is 780℃, and the time is 90 min. The thickness of the biomass coke coating on the surface of hot iron ore powder particles is 0.02-0.08 mm. The synergistic effect of multiple reducing agents (H2 / CO / biomass coke) increases the reduction rate by 28%.

[0104] S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air to achieve the circulation of chemical and thermal energy. The final metallization rate of the iron product remains stable at 91.5%.

[0105] This embodiment verifies the process adaptability under extreme conditions: the lowest biomass gasification split ratio (20:80), the lowest reduction temperature (780°C), and the longest reduction time (90 min). Although the metallization rate is slightly lower (91.5%), it still meets the design requirement of over 91%, demonstrating the system's stability under wide operating conditions. System carbon accounting shows a carbon emission intensity of 0.09 tons of CO2 / ton of iron. The secondary circulating fluidized bed system showed no adhesion after 120 hours of continuous operation. Energy balance calculations indicate that the system's overall thermal efficiency is 80%.

[0106] Example 6

[0107] This embodiment describes an application method of the biomass multi-pathway synergistic reduction iron ore device, as described above. Figure 1 As shown, the application method of the biomass multi-path synergistic reduction iron ore device is as follows: S1. Biomass Diversion and Energy Conversion: Based on the raw material composition of the iron ore powder to be reduced (mixed hematite and magnetite powder with a particle size of 0-4mm and a total iron content ≥55%) and the requirement of a final iron product metallization rate of over 92%, a mixture of straw and wood chips (mass ratio 1:1) is selected as the biomass raw material, and its diversion ratio in the distributor is 50:50. The biomass raw material is divided into two paths by the distributor: one path of biomass raw material is transported into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO+H2; the other path of biomass raw material enters the combustion zone of the combustion furnace and is co-combusted with hydrogen to provide the main heat source for the system.

[0108] S2. Iron Ore Preheating and Solid-Solid Separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas, and circulating hot bed material in the combustion furnace and rapidly preheated to 900℃ at a heating rate of 140℃ / min for 7 minutes. The preheated mixture is captured by a primary gas-solid separator and then sorted by a solid distributor based on density differences: higher density (density greater than 4.7 g / cm³) is selected from the solids. 3 Hot iron ore powder is preferentially fed into the secondary circulating fluidized bed system, while light biomass coke and ash are returned to the primary circulating fluidized bed system for recycling or discharged.

[0109] S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reactor of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas, and biomass coke. Biomass coke acts as an in-situ coating agent, covering the surface of the hot iron ore powder particles, thereby effectively blocking iron grain bonding and completely solving the fluidized bed adhesion and flow loss problem. The coke / iron powder mass ratio is 1:10, the synergistic reduction temperature is 860℃, and the time is 50 min. The thickness of the biomass coke coating on the surface of the hot iron ore powder particles is 0.05-0.15 mm. The synergistic effect of multiple reducing agents (H2 / CO / biomass coke) increases the reduction rate by 33%.

[0110] S4. Energy Closed Loop and Near-Zero Emissions: The high-temperature flue gas (containing unreacted H2 / CO) from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air to achieve the circulation of chemical and thermal energy. The final metallization rate of the iron product remains stable at 95.5%.

[0111] This embodiment verifies the system's adaptability to mixed mineral powders and mixed biomass. The mixed biomass feedstock (straw + sawdust) demonstrates the system's compatibility with different types of biomass. The mixed mineral powder (hematite + magnetite) demonstrates the system's adaptability to feedstock fluctuations. SEM shows that the carbon coating layer on the iron particles is intact. System carbon accounting shows a carbon emission intensity of 0.06 tons of CO2 / ton of iron. The secondary circulating fluidized bed system showed no agglomeration after 120 hours of continuous operation. Energy balance calculations indicate that the system's overall thermal efficiency is 83%.

[0112] The above-mentioned solution, proposed by the present invention, is a method for improving the high-cycle fatigue performance of TiAl alloy by shot peening. It can solve the technical problems in the prior art, such as the inability to achieve orders-of-magnitude improvement in the high-cycle fatigue performance of TiAl alloy, poor practicality, low depth and uniformity of residual compressive stress field distribution, and the introduction of residual compressive stress often accompanied by a significant increase in surface roughness and the generation of surface damage such as microcracks.

[0113] The method of this invention combines biomass energy with water electrolysis to produce hydrogen, thereby eliminating dependence on fossil fuels and achieving near-zero carbon dioxide emissions in the ironmaking process from the source. The carbon emission intensity is <0.1 tons CO2 / ton of iron, which is more than 95% lower than that of traditional blast furnaces (about 1.8 tons).

[0114] This invention decouples the "preheating" and "deep reduction" processes of iron ore through a multi-stage circulating fluidized bed design. In the first-stage circulating fluidized bed system, biomass combustion provides heat; even if steam is generated, it only affects the preheating stage and does not affect the deep reduction in the second-stage circulating fluidized bed system, ensuring a high metallization rate of the product. Specifically, the metallization rate reaches 91-95%, which is superior to traditional gas-based vertical shaft furnaces (75-85%) and single hydrogen-based fluidized beds (typically <85% due to steam suppression).

[0115] The method of this invention introduces biomass coke (a byproduct of primary heating) as an in-situ coating agent to form a physical isolation layer, which fundamentally inhibits the adhesion between iron grains and completely solves the adhesion problem; in particular, the secondary circulating fluidized bed system can operate continuously and stably for more than 120 hours without adhesion, breaking through the core bottleneck of fluidized bed ironmaking industrialization.

[0116] This invention enables the efficient cascade utilization of biomass, allowing it to serve simultaneously as fuel, gasification feedstock (producing reducing gas), and carbon coating agent, thereby improving biomass utilization efficiency and economic benefits. Therefore, it boasts strong raw material adaptability and low cost: 0-8mm iron ore powder can be used directly, eliminating the need for agglomeration; biomass sources are wide-ranging, and the system is compatible with different types (wood chips, straw, rice husks, etc.).

[0117] The method of this invention has a high degree of energy efficiency integration: tail gas recycling makes the system thermal efficiency >80%, and the coupling of water electrolysis for hydrogen production and biomass energy realizes the maximum cascade utilization of energy. Through simulation experiments, CFD simulation confirmed that the atmosphere in the combustion zone and gasification zone in the primary bed coexists stably; SEM images show that a complete biomass char coating layer is formed on the surface of iron particles.

[0118] This technology provides a complete technological path for green, zero-carbon metallurgy, which is expected to reduce the steel industry's dependence on fossil fuels and provide a key technological solution for achieving the industry-wide goal of "carbon neutrality." The "zero-carbon steel" or "green steel" produced using this process will become an important raw material for downstream high-end manufacturing (such as new energy vehicles, high-end equipment, and green buildings), meeting the carbon footprint requirements of the supply chain.

[0119] In summary, compared with existing technologies, the method of this invention integrates the device structure of biomass combustion heating, gasification gas supply and multi-stage fluidized bed reduction, and proposes methods including biomass diversion and energy conversion, iron ore preheating and solid-solid separation, multi-path synergistic reduction and adhesion inhibition, and energy closed loop and near-zero emissions to prepare low-carbon, high-energy-efficiency, and high-purity iron products. This method is stable, easy to implement, low-cost, and highly efficient, which is conducive to large-scale industrial production and promotion.

[0120] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0121] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0122] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0123] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for the multi-pathway synergistic reduction of iron ore by biomass, characterized in that, The biomass multi-path synergistic reduction device for iron ore includes a biomass supply and diversion unit, a primary circulating fluidized bed system, a secondary circulating fluidized bed system, and a gas circulation and energy integration system.

2. The apparatus for the multi-pathway synergistic reduction of iron ore by biomass according to claim 1, characterized in that, The biomass supply and diversion unit includes a biomass silo for storing and transporting biomass raw materials, and a diverter for distributing biomass raw materials to combustion and gasification paths according to a preset ratio. The outlet of the biomass silo is connected to the diverter via a feeder.

3. The apparatus for the multi-pathway synergistic reduction of iron ore by biomass according to claim 1, characterized in that, The primary circulating fluidized bed system includes a combustion furnace. The bottom of the combustion furnace is divided into two areas, a combustion zone and a gasification zone, by an air distribution plate. A fluidizing air inlet connected to the tail gas pipe of the primary circulating fluidized bed is provided below the air distribution plate. An iron ore powder inlet is provided at the top of the combustion furnace. The top of the combustion furnace is connected to the air inlet of the primary gas-solid separator through a pipeline. A solid distributor is provided directly below the solid outlet of the primary gas-solid separator.

4. The apparatus for the multi-path synergistic reduction of iron ore by biomass according to claim 3, characterized in that, The solid distributor is provided with a first discharge port and a second discharge port. The first discharge port is connected to the bottom of the combustion furnace through a return pipe, and the second discharge port connects the iron ore powder from the iron ore powder inlet to the lower part of the reduction reaction zone of the secondary circulating fluidized bed through a conveying pipeline.

5. The apparatus for the multi-path synergistic reduction of iron ore by biomass according to claim 1, characterized in that, The secondary circulating fluidized bed system includes a reduction reaction furnace, the bottom of which is provided with an air distribution plate, a solid inlet, a gas inlet, and an iron discharge port.

6. The apparatus for the multi-path synergistic reduction of iron ore by biomass according to claim 5, characterized in that, The solid inlet is connected to the second outlet of the solid distributor; the top outlet of the reduction reaction furnace is connected to the inlet of the secondary gas-solid separator, and the inlet of the return material device is located directly below the solid outlet of the secondary gas-solid separator. The outlet of the return material device is connected to the upper part of the reduction reaction furnace.

7. The apparatus for the multi-path synergistic reduction of iron ore by biomass according to claim 1, characterized in that, The gas circulation and energy integration system includes a primary gas circulation pipeline and a secondary gas circulation pipeline. The primary gas circulation pipeline includes a connecting pipeline between the gas outlet of the primary gas-solid separator and the inlet of the gasification zone of the combustion furnace. The secondary gas circulation pipeline includes a connecting pipeline between the gas outlet of the secondary gas-solid separator and the gas inlet at the bottom of the reduction reaction furnace.

8. A method for applying the apparatus for the multi-path synergistic reduction of iron ore based on claim 1, characterized in that, The application method of the biomass multi-path synergistic reduction device for iron ore is as follows: S1. Biomass diversion and energy conversion: Based on the composition of the iron ore powder to be reduced and the metallization rate requirement of the final iron product, the biomass raw material and its diversion ratio in the diverter are selected. One biomass raw material is fed into the gasification zone of the combustion furnace and reacts with water vapor to generate syngas of CO + H2; the other biomass raw material enters the combustion zone of the combustion furnace and is co-combusted with hydrogen to provide the main heat source for the system. S2. Iron ore preheating and solid-solid separation: The iron ore powder to be reduced is mixed with high-temperature flue gas, syngas and circulating hot bed material in the combustion furnace and is rapidly preheated; the preheated mixture is captured by the primary gas-solid separator and sorted by the solid distributor based on density differences: the denser hot iron ore powder preferentially enters the secondary circulating fluidized bed system, while the light biomass coke and ash are returned to the primary circulating fluidized bed system for circulation or discharged; S3. Multi-path synergistic reduction and adhesion inhibition: In the reduction reaction furnace of the secondary circulating fluidized bed system, hot iron ore powder is simultaneously reduced by hydrogen, syngas and biomass coke, in which biomass coke acts as an in-situ coating agent, covering the particle surface of hot iron ore powder. S4. Energy closed loop and near-zero emissions: The high-temperature flue gas from the secondary circulating fluidized bed system is returned to the combustion furnace of the primary circulating fluidized bed system and used as fluidizing air to realize the circulation of chemical energy and thermal energy.

9. The application method of the biomass multi-path synergistic reduction device for iron ore according to claim 8, characterized in that, The rapid preheating process involves a heating rate of 90-180℃ / min, a preheating temperature of 800-950℃, and a preheating time of 5-12 min; the density of the hot iron ore powder is greater than 4.3-5.0 g / cm³. 3 .

10. The application method of the biomass multi-path synergistic reduction device for iron ore according to claim 8, characterized in that, The temperature for the synergistic reduction is 780-950℃, and the time is 35-90 min; the thickness of the biomass coke coating on the surface of the hot iron ore powder particles is 0.02-0.20 mm.

Images