Biomass pyrolysis coupled with iron oxide reduction and biochar activation modification device and method

Abstract

The application relates to a biomass pyrolysis coupling iron oxide reduction and biochar activation modification device and method, and belongs to the field of chemical non-ferrous metallurgy environmental protection technology. The biomass pyrolysis coupling iron oxide reduction and biochar activation modification device comprises a gas conveying unit, a biomass pyrolysis zone, a hematite reduction zone and an activation zone; wherein the bottom of the biomass pyrolysis zone is communicated with the bottom of the hematite reduction zone through a pipeline, and a heat tracing device is arranged between the hematite reduction zone and the biomass pyrolysis zone and the activation zone; the top of the hematite reduction zone is communicated with the bottom of the activation zone through a pipeline, the top of the activation zone is communicated with the top of a molecular sieve through a pipeline, the bottom of the molecular sieve is communicated with the top of a circulating pump through a pipeline, and the bottom of the circulating pump is communicated with the gas conveying unit through a pipeline. The application can solve the problems of more tar and CO2 emission, low utilization value of pyrolysis carbon and low reduction degree of biomass direct reduced iron in the prior art.

Description

Technical Field

[0001] This application relates to the fields of chemical, non-ferrous metallurgy and environmental protection technology, and in particular to a device and method for biomass pyrolysis coupled with iron oxide reduction and biochar activation and modification. Background Technology

[0002] Traditional blast furnace ironmaking relies on coke, which is not only energy-intensive but also produces large amounts of carbon dioxide emissions. Biomass, as a renewable resource, is carbon-neutral. Its pyrolysis and gasification produce gaseous products rich in hydrogen and carbon monoxide, which are considered ideal clean reducing agents that can be used to replace traditional fossil fuels and achieve green ironmaking.

[0003] However, there are many problems in the traditional pyrolysis-reduction reaction process:

[0004] First, tar is generated during pyrolysis. High tar content not only leads to energy waste, reduced gasification efficiency, equipment corrosion, and pipeline blockage, but also pollutes the environment. Existing purification technologies are energy-intensive and prone to catalyst deactivation. Second, the gas quality produced by traditional pyrolysis reduction reactions is low, mainly manifested in a high CO2 content (up to 30%) and an H2 content (below 20%). The utilization value of pyrolysis char is low; the generated pyrolysis char has a small specific surface area and low adsorption capacity, making it difficult to achieve high-value utilization. In addition, the ability of biomass to directly reduce iron oxide needs to be improved, especially under low-temperature pyrolysis conditions, the reduction of iron oxides such as hematite is incomplete. Many processes still only reduce it to ferrous oxide, without completely reducing it to elemental iron.

[0005] Therefore, there is an urgent need to develop new reaction devices and processes to achieve multiple breakthroughs, such as efficient removal and resource utilization of tar, upgrading of syngas (reducing CO2 content and increasing H2 content), and enhancing the reducing activity of iron ore, by regulating the reaction system, strengthening multi-module synergy, and improving product value. Summary of the Invention

[0006] In view of this, this application provides a biomass pyrolysis coupled with iron oxide reduction and biochar activation modification device and method. It utilizes a biomass pyrolysis coupled with an iron-supported oxygen carrier to promote tar reforming and macromolecular decomposition. Phenolic compounds and polycyclic aromatic hydrocarbons in the tar are decomposed into smaller molecules (such as CH4, CO2, H2, etc.) through the catalytic action of the iron-supported oxygen carrier. By introducing an activation reaction, the activated carbon reacts with CO2 at high temperature (C + CO2 → 2CO), which not only makes the pyrolysis carbon a higher-quality activated carbon but also generates more reducing gases, thus solving the problems of high tar and CO2 emissions and low utilization value of pyrolysis carbon.

[0007] The first aspect of this application provides a biomass pyrolysis coupled iron oxide reduction and biochar activation modification device, the biomass pyrolysis coupled iron oxide reduction and biochar activation modification device comprising a gas conveying unit, a biomass pyrolysis zone, a hematite reduction zone and an activation zone;

[0008] The bottom of the biomass pyrolysis zone is connected to the bottom of the hematite reduction zone via a pipeline, and a heat tracing device is provided between the hematite reduction zone, the biomass pyrolysis zone, and the activation zone. The top of the hematite reduction zone is connected to the bottom of the activation zone via a pipeline, the top of the activation zone is connected to the top of the molecular sieve via a pipeline, the bottom of the molecular sieve is connected to the top of the circulating pump via a pipeline, and the bottom of the circulating pump is connected to the gas delivery unit via a pipeline.

[0009] Preferably, the top of the biomass pyrolysis zone is connected to the top of the flow meter control rate device via a pipe, and the bottom of the flow meter control rate device is connected to the gas delivery unit via a T-junction.

[0010] Preferably, the flow rate adjustment range of the flow meter control rate device is 1~1000mL / min.

[0011] Preferably, the biomass pyrolysis zone, hematite reduction zone, and activation zone are all connected to a temperature control unit, which is externally connected to a computer; the computer controls the temperature control unit and further independently regulates the temperature of the biomass pyrolysis zone, hematite reduction zone, and activation zone.

[0012] Preferably, the heat tracing device uses an electric heat tracing cable to maintain the gas pipeline temperature at ≥100℃, with a temperature control accuracy of ±5℃.

[0013] Preferably, the gas delivery unit is an N2 bottle.

[0014] The second aspect of this application also provides a method for operating the above-mentioned biomass pyrolysis coupled iron oxide reduction and biochar activation modification device, the specific process of which is as follows:

[0015] S1. Weigh and record the weights of the pretreated biomass raw materials, pyrolytic carbon raw materials, and hematite raw materials. Load them into the corresponding pipes and complete the assembly and gas connection of the experimental equipment. Turn on the carrier nitrogen gas in the gas delivery unit to purge the entire device to remove the air. At the same time, use soap foam to check the air tightness of the device. If there is a leak, investigate the cause. If the air tightness is good, adjust the gas flow rate to 50 mL / min and set the temperature parameters for this experiment through the temperature control unit. Molecular sieves can adsorb some moisture and tar to prevent damage to the circulation pump.

[0016] S2. Then, purge the pipeline with N2 for 10 minutes to ensure an oxygen-deficient environment. Then, start the circulation pump to keep the gas circulating in the reaction system.

[0017] S3. After the purging procedure is completed, turn on the heating program and the heating device in sequence, turn off the nitrogen gas and adjust the circulation flow rate to 50 mL / min through the flow meter control rate device. When the experimental temperature reaches the preset value, turn off the circulation pump and stop heating to start cooling.

[0018] S4. After the entire reaction system is cooled to below 50°C, the synthesis gas in the collection device is purged with nitrogen into the aluminum foil gas bag, and the composition of the synthesis gas is analyzed by GC. The solid products in the pyrolysis furnace of the biomass pyrolysis zone, the reduction furnace of the hematite reduction zone, and the activation furnace of the activation zone are collected, weighed and recorded, and the experimental data are organized for subsequent analysis.

[0019] S5. Take out some pyrolytic carbon and activated carbon samples for BET testing and elemental analysis. Grind the direct reduced iron into powder and then perform XRD analysis.

[0020] Preferably, in step S1, the biomass raw material is rod-shaped pine wood pellets with a diameter of 6.5 mm and a length of 10~25 mm. The pretreatment process of the biomass raw material is as follows: before use, it is dried in an electric heating drying oven at 105℃ for 2 hours. After drying, the sample is quickly transferred to a sealed bag and stored in a desiccator.

[0021] In step S1, the pyrolytic carbon raw material is the product pyrolytic carbon from a pure pyrolysis experiment at 700℃. The pretreatment process of the pyrolytic carbon raw material is as follows: the experiment is carried out after drying in a drying oven at 100℃ for 2 hours.

[0022] In step S1, the hematite raw material is natural hematite, and the natural hematite is composed of Fe2O3 and SiO2. The pretreatment process of the hematite raw material is as follows: before use, it is ground in an agate mortar and sieved to a particle size range of 0.2~0.5mm, dried in an electric heating drying oven at 105℃ for 2h, and after drying, the sample is quickly transferred to a sealed bag and stored in a desiccator.

[0023] Preferably, in step S1, the temperature control unit is set to the following temperature ranges: 400~1000℃ for the biomass pyrolysis zone, 700~1200℃ for the hematite reduction zone, and 700~1000℃ for the activation zone, with a temperature control accuracy of ±5℃ for each zone.

[0024] Preferably, in step S4, the pyrolysis product is pyrolytic carbon; the reduction product is direct reduced iron; and the activation product is activated carbon.

[0025] Compared with the prior art, this application has the following advantages:

[0026] (1) In this application, biomass pyrolysis and iron oxide reduction are carried out in situ, and iron oxide is reduced by pyrolysis gas while tar is further cracked.

[0027] (2) The addition of a pyrolysis carbon activation unit in this application can improve the quality of syngas. First, under the same hematite weight conditions, the content of H2 and CO in syngas increases after the activation reaction is introduced. Second, it has a good carbon emission reduction effect, reducing the CO2 content in syngas from 15.22~18.93% to 4.01~5.98%.

[0028] (3) The internal structure of the activated biochar product of this application changes from a relatively flat structure to a porous layered structure, and the specific surface area is significantly increased. The specific surface area of ​​the activated biochar is 13 m². 2 / g increased to 341~523 m 2 / g, the activated pyrolytic carbon has a more developed pore structure and stronger adsorption capacity, which improves the utilization value of pyrolytic carbon.

[0029] (4) The pyrolysis-reduction-activation cycle mode of this application has a higher iron ore processing capacity. After the activation reaction is introduced, the amount of hematite that can be reduced per unit mass of biomass is greatly improved, and the optimal raw material ratio of biomass to hematite is increased from 4:1 to 1:1. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the biomass pyrolysis coupled iron oxide reduction and biochar activation modification device of this application;

[0032] Figure 2 This is a three-dimensional structural schematic diagram of the biomass pyrolysis coupled iron oxide reduction and biochar activation modification device of this application;

[0033] Figure 3 A schematic diagram of the working method of a biomass pyrolysis coupled iron oxide reduction and biochar activation modification device;

[0034] Figure 4 XRD pattern of hematite raw material;

[0035] Figure 5The diagram shows the adsorption curves and pore size comparison of pyrolytic carbon and activated carbon. In the diagram, A is the adsorption isotherm of pyrolytic carbon, B is the adsorption isotherm of activated carbon, C is the pore size distribution of pyrolytic carbon, and D is the pore size distribution of activated carbon.

[0036] Figure 6 XRD patterns of hematite of different weights after reduction.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Gas delivery unit; 2. Biomass pyrolysis zone; 3. Hematite reduction zone; 4. Activation zone; 5. Circulating pump; 6. Molecular sieve; 7. Heating device; 8. Temperature control unit; 9. Flow meter rate control device. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] First, those skilled in the art should understand that these embodiments are merely for explaining the technical principles of this application and are not intended to limit the scope of protection of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0041] Secondly, it should be noted that in the description of this application, the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0042] Traditional pyrolysis-reduction processes in related technologies suffer from several problems: First, tar is produced during pyrolysis, leading to energy waste, reduced gasification efficiency, equipment corrosion, and pipeline blockage, as well as environmental pollution. Existing purification technologies are energy-intensive and prone to catalyst deactivation. Second, the quality of gases produced by traditional pyrolysis-reduction reactions is low, characterized by high CO2 content (up to 30%) and H2 content (below 20%). The utilization value of pyrolysis char is also low, with a small specific surface area and low adsorption capacity, making high-value utilization difficult. Furthermore, the ability of biomass to directly reduce iron oxide needs improvement, especially under low-temperature pyrolysis conditions where the reduction of iron oxides such as hematite is incomplete; many processes only reduce it to ferrous oxide, not entirely to elemental iron.

[0043] To solve the above technical problems, such as Figure 1 and Figure 2 As shown in the embodiment of this application, a device for biomass pyrolysis coupled with iron oxide reduction and biochar activation modification is provided. The device includes a gas conveying unit 1, a biomass pyrolysis zone 2, a hematite reduction zone 3, and an activation zone 4.

[0044] The bottom of the biomass pyrolysis zone 2 is connected to the bottom of the hematite reduction zone 3 via a pipe, and a heat tracing device 7 is installed between the biomass pyrolysis zone 2 and the hematite reduction zone 3. Both the biomass pyrolysis zone 2 and the hematite reduction zone 3 are connected to the heat tracing device 7 via pipes. The top of the hematite reduction zone 3 is connected to the bottom of the activation zone 4 via a pipe. The top of the activation zone 4 is connected to the top of the molecular sieve 6 via a pipe. The bottom of the molecular sieve 6 is connected to the top of the circulating pump 5 via a pipe. The bottom of the circulating pump 5 is connected to the gas delivery unit 1 via a pipe.

[0045] For example, the bottom of the molecular sieve 6 is connected to the top of the circulation pump 5 via a pipe. The function of the molecular sieve 6 is to filter the circulating gas and prevent contamination of the circulation pump 5. The circulation pump 5 plays a role in propelling the gas in the experiment, thus forming a circulation.

[0046] Furthermore, the top of the biomass pyrolysis zone 2 is connected to the top of the flow meter control rate device 9 via a pipe, and the bottom of the flow meter control rate device 9 is connected to the gas delivery unit 1 via a three-way pipe.

[0047] Furthermore, the flow rate adjustment range of the flow meter control rate device 9 is 1~1000mL / min.

[0048] Furthermore, the biomass pyrolysis zone 2, the hematite reduction zone 3, and the activation zone 4 are all connected to a temperature control unit 8, which is externally connected to a computer. The computer controls the temperature control unit 8 and further independently regulates the temperature of the biomass pyrolysis zone 2, the hematite reduction zone 3, and the activation zone 4.

[0049] Furthermore, the heat tracing device 7 uses an electric heat tracing cable to maintain the gas pipeline temperature at ≥100℃, with a temperature control accuracy of ±5℃.

[0050] Furthermore, the gas delivery unit 1 is an N2 bottle used to deliver inert gases such as nitrogen.

[0051] like Figure 3 As shown, the operating method of the above-mentioned biomass pyrolysis coupled with iron oxide reduction and biochar activation modification device first involves pre-treating and loading the raw materials. Then, the reduction of the biomass pyrolysis coupled with an iron-supported oxygen carrier promotes the reforming of tar and the decomposition of macromolecules. This allows phenols and polycyclic aromatic hydrocarbons in the tar to be decomposed into smaller molecules (such as CH4, CO2, and H2) through the catalytic action of the iron-supported oxygen carrier. Next, the pyrolysis carbon is further physically activated through a fixed bed containing pyrolysis carbon, consuming some water vapor and CO2, thus improving the composition of the syngas. The specific process is as follows:

[0052] S1. Weigh and record the weights of the pretreated biomass raw materials, pyrolytic carbon raw materials, and hematite raw materials. Load them into the corresponding pipes and complete the assembly and gas connection of the experimental equipment. Turn on the carrier nitrogen gas in the gas delivery unit 1 to purge the entire device to remove the air. At the same time, use soap foam to check the air tightness of the device. If there is a leak, investigate the cause. If the air tightness is good, adjust the gas flow rate to 50 mL / min and set the temperature parameters for this experiment through the temperature control unit 8. The molecular sieve 6 can adsorb some moisture and tar to prevent damage to the circulation pump.

[0053] S2. Then, purge the pipeline with N2 for 10 minutes to ensure an oxygen-deficient environment. Then, start the circulation pump 5 to continuously circulate the gas in the reaction system.

[0054] S3. After the purging procedure is completed, turn on the heating program and the heating device 7 in sequence, turn off the nitrogen gas and adjust the circulation flow rate to 50 mL / min through the flow meter control rate device 9. When the experimental temperature reaches the preset value, turn off the circulation pump 5 and stop heating to start cooling.

[0055] S4. After the entire reaction system has cooled to below 50°C, purge the syngas in the collection device with nitrogen into an aluminum foil gas bag, and analyze the composition of the syngas using GC (GC analysis of syngas composition means: after the entire reaction system has cooled to below 50°C, purge the syngas in the collection device with nitrogen into an aluminum foil gas bag, and analyze the composition of the syngas using GC (gas chromatography). The analysis results of the gas composition are: the main components of the syngas after circulation are H2 (35~45%), CO (48~57%), CO2 (4~6%), and CH4 (1~2%). Collect the solid products in the pyrolysis furnace of biomass pyrolysis zone 2, the reduction furnace of hematite reduction zone 3, and the activation furnace of activation zone 4, weigh and record them, and organize the experimental data for subsequent analysis.

[0056] S5. Take out a portion of the pyrolytic carbon and activated carbon samples for BET testing (BET testing refers to the BET specific surface area test of the carbon samples, used to measure the specific surface area, pore volume, pore size distribution, and nitrogen adsorption-desorption curves of the particles. Specific surface area data shows that the specific surface area of ​​the pyrolytic carbon increases to 300~400 m² after activation). 2 / g indicates that the physical activation reaction successfully introduced a large number of micropores. The pore size distribution and nitrogen adsorption-desorption curve test results are as follows: Figure 5 As shown, Figure 5 The adsorption isotherm type of the pyrolytic carbon shown in Figure A is Type III, indicating that the material has a limited adsorption capacity and a small specific surface area. Figure 5 The adsorption isotherm of activated carbon shown in Figure B is of type I, indicating that the material is a microporous material. Figure 5 C and Figure 5 Comparative analysis of the medium and small particles showed that the pore volume of the activated carbon increased by nearly ten times and the average pore size was also smaller, indicating that the physical activation reaction successfully introduced a large number of micropores. Elemental analysis was also performed, with direct reduced iron ground into powder and then subjected to XRD analysis.

[0057] Specifically, in step S1, the biomass raw material is rod-shaped pine wood particles with a diameter of 6.5 mm and a length of 10-25 mm. The pretreatment process of the biomass raw material is as follows: before use, it is dried in an electric heating drying oven at 105℃ for 2 hours to minimize the interference of moisture on the pyrolysis reaction. After drying, the sample is quickly transferred to a sealed bag and stored in a desiccator to avoid changes in physical properties caused by moisture absorption. In step S1, the pyrolysis carbon raw material is the product of a pure pyrolysis experiment at 700℃. The pretreatment process of the pyrolysis carbon raw material is as follows: after drying in a drying oven at 100℃ for 2 hours, the experiment is conducted. In step S1, the hematite raw material is natural hematite. X-ray diffraction analysis of the raw material phase is used, such as... Figure 4As shown, the natural hematite is composed of Fe2O3 and SiO2. The pretreatment process of the hematite raw material is as follows: before use, it is ground in an agate mortar and sieved to a particle size range of 0.2~0.5mm, dried in an electric heating drying oven at 105℃ for 2h, and after drying, the sample is quickly transferred to a sealed bag and stored in a desiccator to ensure the uniformity of the reduction reaction interface.

[0058] Specifically, in step S1, the temperature control unit 8 is set to the following temperature ranges: 400~1000℃ for biomass pyrolysis zone 2, 700~1200℃ for hematite reduction zone 3, and 700~1000℃ for activation zone 4, with a temperature control accuracy of ±5℃ for each zone. The activation product is activated carbon.

[0059] Specifically, in step S4, the pyrolysis product is pyrolytic carbon. After grinding the pyrolytic carbon to a particle size of less than 0.1 mm, its specific surface area and pore size distribution are measured using a specific surface area and micropore analyzer. Figure 5 As shown, the contents of C, H, N, and O elements were obtained using an elemental analyzer; the reduction product was direct reduced iron. The reduced hematite product was ground into particles with a diameter of less than 0.08 mm, and Fe2O3, Fe3O4, FeO, and elemental Fe were characterized using X-ray diffraction (XRD). Figure 6 As shown.

[0060] For example, such as Figure 3 As shown, this embodiment provides a method for achieving direct reduction of iron, syngas, and activated carbon through a biomass pyrolysis gas-hematite reduction-pyrolysis carbon activation cycle. The process includes the following steps:

[0061] Raw material pretreatment:

[0062] Biomass raw materials: Pine wood pellets (diameter 6.5mm, length 0~25mm, moisture content ≤10%) are selected and dried at 105℃ for 2 hours for later use;

[0063] Hematite: Grind to a particle size of 0.2~0.5mm;

[0064] Pyrolytic carbon: The product of pure pyrolysis experiment at 700℃, which was dried in a drying oven at 105℃ for 1 hour before the experiment.

[0065] Process steps and parameter optimization:

[0066] (1) Step 1: Loading

[0067] Pyrolysis furnace (biomass pyrolysis zone 2): loaded with 4.0g of pine wood pellets, spread into a uniform thin layer;

[0068] Reduction furnace (hematite reduction zone 3): loaded with 1.0g of hematite powder;

[0069] Activation furnace (activation zone 4): loaded with 4.0g of pyrolytic carbon.

[0070] (2) Step 2: Device pre-start

[0071] Use a gas cylinder to purge air from the N2 replacement device to maintain an oxygen content of ≤0.1%;

[0072] Start the heat tracing device;

[0073] Set the flow rate of circulation pump 5 to 0.5 L / min.

[0074] (3) Step 3: Synergistic pyrolysis-reduction-activation pyrolysis stage: The temperature is increased to 700℃ (preferred range 600~800℃) at 10℃ / min to generate pyrolysis gas and biochar;

[0075] Reduction stage: The reduction furnace is simultaneously heated to 950℃ (preferred range 850~1050℃), and the pyrolysis gas reacts with hematite to produce metallic iron (Fe) and ferrous oxide (FeO), etc.

[0076] Activation stage: The activation furnace is heated to 950℃ and reacts with the reduced gas to generate activated carbon with high specific surface area.

[0077] (4) Step 4: Cycling and product collection analysis

[0078] The gas returns to the pyrolysis furnace through the outlet of the activation furnace, forming a cycle of "pyrolysis gas → reduction → activation → regeneration". The gas flow rate is controlled at 50 mL / min using a circulation pump and a flow meter.

[0079] Reduced iron product: After cooling, it is taken out from the bottom of the reduction furnace. XRD analysis shows that it is a Fe / FeO mixed phase. Under certain reaction conditions, pure elemental iron can be obtained.

[0080] Carbon products: Samples were taken and analyzed after cooling to room temperature under nitrogen protection. The specific surface area increased to 300–400 m² / g after activation, indicating that the physical activation reaction successfully introduced a large number of micropores. The carbon content of the activated carbon sample was significantly increased.

[0081] Syngas: Collected and analyzed by GC, the main components of the syngas after circulation are H2 (35~45%), CO (48~57%), CO2 (4~6%), and CH4 (1~2%).

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A working method of a biomass pyrolysis coupling iron oxide reduction and pyrolysis carbon activation modification device, characterized in that, The biomass pyrolysis coupling hematite reduction and pyrolysis carbon activation modification device comprises a gas conveying unit (1), a biomass pyrolysis zone (2), a hematite reduction zone (3) and an activation zone (4); The bottom of the biomass pyrolysis zone (2) is communicated with the bottom of the hematite reduction zone (3) through a pipeline, and the hematite reduction zone (3) is provided with a heat tracing device (7) between the biomass pyrolysis zone (2) and the activation zone (4); the top of the hematite reduction zone (3) is communicated with the bottom of the activation zone (4) through a pipeline, the top of the activation zone (4) is communicated with the top of a molecular sieve (6) through a pipeline, the bottom of the molecular sieve (6) is communicated with the top of a circulating pump (5) through a pipeline, and the bottom of the circulating pump (5) is communicated with the gas conveying unit (1) through a pipeline; The top of the biomass pyrolysis zone (2) is connected with the top of a flow meter control rate device (9) through a pipeline, and the bottom of the flow meter control rate device (9) is communicated with the gas conveying unit (1) through a three-way pipe; The working method of the biomass pyrolysis coupling hematite reduction and pyrolysis carbon activation modification device is as follows: S1, first, the weights of the pretreated biomass raw material, pyrolysis carbon raw material and hematite raw material are measured and recorded, and then they are loaded into the corresponding pipelines and the assembly and gas connection of the experimental equipment are completed; the carrier gas nitrogen in the gas conveying unit (1) is opened, the entire device is purged to discharge the air in the device, and the air tightness of the device is detected by using soap foam; if there is air leakage, the reason is investigated; if the air tightness is good, the gas flow is adjusted to 50 mL / min, and the temperature parameters of this experiment are set through the temperature control unit (8); the molecular sieve (6) adsorbs part of the water and tar to prevent damage to the circulating pump; S2, then, N2 is used to purge for 10 min to ensure that the pipeline forms an oxygen-deficient environment, and then the circulating pump (5) is started to make the gas continuously circulate in the reaction system; S3, after the purging program is completed, the heating program and the heat tracing device (7) are opened in sequence, the nitrogen is closed, and the circulating flow is adjusted to 50 mL / min through the flow meter control rate device (9); when the experimental temperature reaches the preset value, the circulating pump (5) is closed, the heating is stopped, and the cooling is started; S4, after the entire reaction system is cooled to below 50℃, the synthetic gas in the collection device is collected in an aluminum foil gas bag by purging with nitrogen, and the composition of the synthetic gas is analyzed by using GC; the solid products in the pyrolysis furnace of the biomass pyrolysis zone (2), the reduction furnace of the hematite reduction zone (3) and the activation furnace of the activation zone (4) are collected, weighed and recorded, and the experimental data are arranged for subsequent analysis; In step S4, the pyrolysis product is biomass pyrolysis carbon; the reduction product is direct reduced iron, and the activation product is activated carbon; S5, part of the biomass pyrolysis carbon and activated carbon samples are taken out for BET testing and elemental analysis, and the direct reduced iron is ground into a powder for XRD analysis. The biomass raw material in step S1 is a stick-shaped pine particle with a diameter of 6.5 mm and a length of 10-25 mm. The pretreatment process of the biomass raw material is as follows: drying at 105℃ for 2 h in an electric hot air drying oven before use, and then quickly transferring the dried sample to a sealed bag and storing in a desiccator; The pyrolysis carbon raw material in step S1 is the product pyrolysis carbon of a 700℃ pure pyrolysis experiment. The pretreatment process of the pyrolysis carbon raw material is as follows: drying at 100℃ for 2 h in a drying oven before the experiment; The hematite raw material in step S1 is natural hematite. The composition of the natural hematite is Fe2O3 and SiO2. The pretreatment process of the hematite raw material is as follows: grinding with an agate mortar before use, sieving to a particle size range of 0.2-0.5 mm, drying at 105℃ for 2 h in an electric hot air drying oven, and then quickly transferring the dried sample to a sealed bag and storing in a desiccator; The temperature control unit (8) in step S1 is set to a temperature of: the temperature control range of the biomass pyrolysis zone (2) is 400-1000℃, the temperature control range of the hematite reduction zone (3) is 700-1200℃, and the temperature control range of the activation zone (4) is 700-1000℃, and the temperature control accuracy is ±5℃.

2. The operating method of the biomass pyrolysis coupled iron oxide reduction and pyrolytic carbon activation modification device according to claim 1, characterized in that, The flow rate control device (9) has a flow rate adjustment range of 1-1000 mL / min.

3. The method according to claim 1, wherein the method is characterized by: The biomass pyrolysis zone (2), the hematite reduction zone (3), and the activation zone (4) are all connected to the temperature control unit (8), and the temperature control unit (8) is connected to a computer. The temperature control unit (8) is controlled by the computer, and the temperatures of the biomass pyrolysis zone (2), the hematite reduction zone (3), and the activation zone (4) are independently adjusted.

4. The method according to claim 1, wherein the method is characterized by: The heat tracing device (7) uses an electric heat tracing band to maintain the temperature of the gas pipeline at ≥100℃, and the temperature control accuracy is ±5℃.

5. The method according to claim 1, wherein the method is characterized by: The gas delivery unit (1) is an N2 bottle.

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