Apparatus and method for reforming biomass pyrolysis to produce hydrogen-rich gas and light aromatic hydrocarbons

Abstract

This invention provides an apparatus and method for producing hydrogen-rich gas and light aromatics through biomass pyrolysis reforming. The apparatus includes a high-temperature pyrolysis in-situ reforming unit and a low-temperature non-in-situ reforming unit for volatiles. The high-temperature pyrolysis in-situ reforming unit employs external heating and utilizes heat-conducting baffles to enhance heat transfer. The heat transfer and volatile release directions are arranged radially opposite, allowing volatiles to pass through the high-temperature semi-coke layer for in-situ catalytic reforming and thermal cracking. After entering the volatile release channel, the volatiles undergo further high-temperature reforming. The low-temperature non-in-situ reforming unit receives the high-temperature volatiles and hot semi-coke generated in the high-temperature section. Utilizing the catalytic effect of the porous biomass semi-coke and the synergistic effect of the secondary reforming agent, deep reforming is performed, increasing the hydrogen content and the selectivity of light aromatics. This invention achieves the simultaneous preparation of hydrogen-rich gas and light aromatics. It has strong raw material applicability, is suitable for scale-up production, and offers technical, economic, and environmental benefits through low-carbon conversion and high-value-added utilization.

Description

Technical Field

[0001] This invention belongs to the field of resource and environmental technology, and specifically relates to an apparatus and method for producing hydrogen-rich gas and light aromatics by biomass pyrolysis reforming. Background Technology

[0002] Biomass is the only renewable carbon source on Earth, possessing advantages such as large reserves, wide distribution, strong substitutability for fossil fuels, and zero-carbon properties. Hydrogen energy is an important clean energy form for future energy transition and achieving the "dual-carbon" goal. Light aromatics (mainly including monocyclic aromatics such as benzene, toluene, and xylene) are important chemical raw materials, currently primarily derived from fossil fuels. The lignin component in biomass is rich in benzene ring structures, providing a raw material advantage for the production of aromatics from biomass. Therefore, developing biomass pyrolysis technology capable of simultaneously producing hydrogen-rich gas and light aromatics is of great significance for promoting the resource utilization and industrial upgrading of biomass.

[0003] Pyrolysis-reforming technology is widely used to produce hydrogen-rich gases and bio-oils due to its advantages such as high efficiency, speed, stability, and strong adaptability to raw materials. Existing technologies generally employ rapid pyrolysis devices, such as fluidized beds, entrained fluidized beds, and sputtered beds, with typical operating conditions including high heating rates (10... 3 ~10 4 The process boasts high efficiency (℃ / s), relatively low temperature (400-500℃), and short gas residence time (seconds). However, the hydrogen yield is limited, and the main product is low-quality bio-oil, characterized by high density, strong acidity and corrosiveness, low calorific value, high viscosity, and high water, oxygen, and dust content. This results in poor thermal stability, easy deterioration, and difficulty in storage, severely restricting its large-scale utilization.

[0004] To address these issues, researchers have attempted to improve product quality through catalytic reforming. For example, Chinese patent CN113214851A uses pyrolysis gas reflux to improve biochar quality and remove tar; Chinese patent CN117660029A removes tar from the semi-coke layer under high-temperature aerobic and water vapor atmosphere to increase hydrogen content. However, these methods mostly employ a two-stage process of "pyrolysis to generate volatiles first, followed by catalytic reforming," with the pyrolysis stage itself lacking effective reaction control. Since the yield of bio-oil and water during biomass pyrolysis is as high as 60%-80%, complete conversion cannot be achieved solely through downstream catalytic reforming units; furthermore, under the goal of hydrogen production, structurally stable light aromatics in bio-oil are easily over-destroyed, leading to a decrease in hydrogen production instead of an increase.

[0005] Regarding in-situ pyrolysis control, Chinese patent CN115181589A uses gasified syngas to promote catalytic pyrolysis, but the products are mainly methane-rich fuel gas with a low hydrogen concentration. Patents CN117511587A and CN102703097A respectively regulate the direction of volatiles by setting gas collecting internal components or heat-conducting plates in the pyrolysis unit to achieve the generation of light tar. However, the common feature of the above devices is that the heat transfer direction is the same as the volatile release direction, and the volatiles are discharged from the low-temperature zone. This operation method is more suitable for raw materials with low oxygen content such as coal and oil shale, but for biomass with high oxygen content, the release of volatiles from the low-temperature zone will lead to the generation of a large amount of water and high oxygen content components in the oil, and the quality of bio-oil is still poor.

[0006] Reforming and upgrading methods for bio-oils include thermal cracking, catalytic reforming, steam reforming, and CO2 reforming, but a single method is unlikely to achieve ideal results. Among these, thermal cracking requires a high temperature of 900-1200℃ to effectively break down oxygen-containing functional groups. As for catalysts, natural ores, synthetic catalysts, and biochar have all shown certain effects, especially biochar produced during the pyrolysis process, which has significant technical and economic value.

[0007] In summary, there is currently a lack of biomass pyrolysis reforming devices and methods capable of simultaneously producing hydrogen-rich gas and light aromatics, suitable for small-particle-size biomass feedstocks, and easily scalable. To address the technical challenges of low hydrogen yield and poor bio-oil quality in existing technologies, there is an urgent need to develop a new process that combines reaction regulation and reactor innovation to achieve efficient and clean conversion and high-value utilization of biomass. Summary of the Invention

[0008] The purpose of this invention is to provide an apparatus and method for producing hydrogen-rich gas and light aromatics through biomass pyrolysis reforming. This invention combines high-temperature pyrolysis in-situ reforming of biomass with low-temperature non-in-situ reforming of volatiles. The high-temperature pyrolysis in-situ reforming apparatus generates hydrogen-rich gas and low-oxygen biomass oil, while the non-in-situ reforming of volatiles further enhances the hydrogen content and selectivity of light aromatics in the gas, thereby realizing the production of high-quality chemicals and clean energy from biomass and improving resource and energy utilization efficiency.

[0009] This invention first provides an apparatus for producing hydrogen-rich gas and light aromatics through biomass pyrolysis reforming, comprising:

[0010] The biomass high-temperature pyrolysis in-situ reforming device is used to perform high-temperature pyrolysis on biomass raw materials and to reform the released volatiles in-situ during the pyrolysis process. The volatile matter low-temperature non-in-situ reforming device is connected in series with the biomass high-temperature pyrolysis in-situ reforming device. It is used to receive high-temperature volatile matter and high-temperature biomass semi-coke generated from the high-temperature pyrolysis in-situ reforming device, and to perform low-temperature non-in-situ reforming on the high-temperature volatile matter. The biomass high-temperature pyrolysis in-situ reforming device adopts an external heating method, and the heat transfer direction inside the device is set to be opposite to the volatile matter release direction in the radial direction.

[0011] Preferably, the biomass high-temperature pyrolysis in-situ reforming device comprises: The pyrolysis reactor has, in a radial direction from the outside to the inside, a volatile matter release zone, a biomass pyrolysis zone, and a central reforming channel. A heating zone, located outside the pyrolysis reactor, is used to provide a heat source; Multiple heat-conducting baffles are installed inside the pyrolysis reactor, with one side connected to the wall of the heating zone, penetrating the volatile release zone and extending to the vicinity of the central reforming channel, to enhance radial heat transfer; The reforming agent addition device is connected to the central reforming channel and is used to introduce gaseous reforming agent into the pyrolysis zone.

[0012] Preferably, the top and the side near the heating zone of the volatile matter release zone are sealed, the upper part of the side near the pyrolysis zone is sealed, the lower part is provided with a porous screen or fence structure, and a gas channel is opened at the bottom to guide the volatile matter out; the central reforming channel adopts a porous screen or fence structure, and its open area is immersed in the material layer of the biomass pyrolysis zone.

[0013] In the biomass pyrolysis zone of this invention's high-temperature pyrolysis in-situ reforming device, heat transfer and volatile matter release are reversed radially. The side closer to the volatile matter release zone is a high-temperature zone, and the side closer to the central reforming channel is a low-temperature zone. Heat is transferred from the high-temperature zone to the low-temperature zone. Biochar is first generated in the high-temperature zone, and the generated volatile matter enters the volatile matter release zone. In the low-temperature zone, the volatile matter generated by pyrolysis migrates to the biochar layer on the high-temperature zone side, undergoing high-temperature pyrolysis radially. The biochar has a certain catalytic effect, and volatile matter undergoes catalytic reforming as it passes through the high-temperature biochar layer. Because a continuous reforming agent is introduced into the central channel, the reforming agent and volatile matter undergo reforming in the high-temperature biochar layer of the pyrolysis zone, improving biochar quality and increasing its specific surface area. After leaving the pyrolysis zone, the volatile matter continues to undergo high-temperature pyrolysis and reforming reactions in the volatile matter release zone. Since the temperature in the volatile matter release zone is greater than or equal to that in the pyrolysis zone, the high-temperature pyrolysis and reforming reactions are more effective.

[0014] Preferably, the volatile matter low-temperature non-in-situ reforming device comprises: The reforming reactor is equipped with a volatile matter uniform distribution device and a low-temperature reforming zone for containing biomass semi-coke. A heating zone is located outside the reforming reactor to maintain the reaction temperature at 600-900°C; A secondary reforming agent addition device is connected to the reforming reactor and is used to introduce reforming agent into the reforming zone (18); A semi-coke cooling and discharge system is located at the bottom of the reforming reactor to cool and discharge the biochar after the reaction.

[0015] Preferably, the biomass high-temperature pyrolysis in-situ reforming device and the volatile matter low-temperature non-in-situ reforming device are connected by a high-temperature screw feeder for conveying pyrolysis high-temperature semi-coke, and the gas outlet of the volatile matter release zone is directly connected to the gas inlet of the low-temperature non-in-situ reforming device, with gas leakage prevented by material seal or mechanical seal.

[0016] Based on the aforementioned apparatus, the present invention also provides a method for producing hydrogen-rich gas and light aromatics through biomass pyrolysis reforming, comprising the following steps: S1. High-temperature in-situ reforming step: Biomass raw materials are added to the biomass high-temperature pyrolysis in-situ reforming device and subjected to high-temperature pyrolysis under external heating conditions. Heat transfer is enhanced by heat-conducting baffles and the direction of heat transfer is controlled to be opposite to the direction of volatile release, so that the released volatiles pass through the high-temperature semi-coke layer and undergo in-situ thermal decomposition and catalytic reforming reactions with the introduced reforming agent and high-temperature semi-coke in the pyrolysis zone and volatile release zone, generating primary reformed volatiles and high-temperature semi-coke. S2, Low-temperature non-in-situ reforming step: The primary reforming volatiles and high-temperature semi-coke generated in step S1 are introduced into the low-temperature non-in-situ reforming unit for volatiles. The volatiles pass through the bed formed by the high-temperature semi-coke and undergo non-in-situ catalytic reforming reaction with the reforming agent introduced in the second step at 600-900℃, which further improves the hydrogen content and selectivity of light aromatics in the product, and generates hydrogen-rich gas and light aromatic products. S3. Post-processing steps: The hydrogen-rich gas and light aromatics generated in step S2 are subjected to gas-solid separation, cooling, condensation and gas-liquid separation to obtain high-purity hydrogen products and light aromatic oil products.

[0017] In step S1, the reforming agent includes one or more of CO2, H2O, and H2; the temperature of the high-temperature pyrolysis is 800-1100℃; and the residence time of the volatiles in the volatiles release zone is no more than 30 seconds.

[0018] In step S2, the temperature of the low-temperature reforming is 600-900℃; the residence time of the volatiles in the reforming zone of the low-temperature reforming unit is no more than 60 seconds.

[0019] In step S3, the separated CO2 and / or H2 portions are recycled back to steps S1 and / or S2 as reforming agents.

[0020] The biomass raw materials include one or more of the following: biomass, coal, oil shale, organic solid waste, waste plastics, sludge, electronic solid waste, and wind turbine blades. The raw material particle size is ≤80mm and the moisture content is ≤20%.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes biomass pyrolysis to prepare hydrogen-rich gas and light aromatics. The generated green hydrogen can be widely used in the synthesis of green chemicals and fuels, and the generated light aromatics are important chemical raw materials, thus achieving high-value-added conversion of biomass resources. The CO2 generated by this invention is returned to the pyrolysis system as a reforming agent, making its low-carbon emission properties even more pronounced. The pyrolysis reforming device of the present invention has a simple structure and makes full use of reaction regulation and reactor innovation to achieve in-situ reforming of volatiles. Through high temperature and low temperature distributed reforming strategies, the selectivity of light aromatics and the amount of hydrogen generated are improved. It makes full use of the catalytic effect of pyrolysis semi-coke and avoids the use of expensive catalysts. In the pyrolysis device of this invention, the volatiles are filtered through multiple layers when passing through the biomass pyrolysis carbon layer, resulting in a very low content of light bio-oil dust, eliminating the need for an additional complex oil dust separation system. The biochar generated in the pyrolysis device of this invention has a larger specific surface area and a wider range of utilization pathways due to repeated interaction with the reforming agent, CO2 and water vapor playing a partial activation role. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the principle and apparatus structure for preparing hydrogen-rich gas and light aromatics by biomass pyrolysis provided by the present invention. Figure 2 This is a flowchart of the steps of the method for preparing hydrogen-rich gas and light aromatics by biomass pyrolysis provided by the present invention; Figure 3 This invention provides an apparatus for preparing hydrogen-rich gas and light aromatics through biomass pyrolysis, as described in Example 1 of the present invention. Figure 4 This invention provides an apparatus for preparing hydrogen-rich gas and light aromatics through biomass pyrolysis, as described in Example 2 of the present invention. Figure 5 This invention provides an apparatus for preparing hydrogen-rich gas and light aromatics through biomass pyrolysis, as described in Example 3 of the present invention. Figure 6 This invention provides an apparatus for preparing hydrogen-rich gas and light aromatics through biomass pyrolysis, as described in Example 4 of the present invention. Among them, 1. Biomass, 2. Feeder, 3. Reforming gas, 4. High-temperature flue gas, 5. Medium-temperature flue gas, 6. High-temperature pyrolysis in-situ reforming unit, 7. Heating zone of high-temperature pyrolysis in-situ reforming unit, 8. Thermal baffle, 9. Volatile matter release channel, 10. Pyrolysis zone, 11. Central reforming gas channel, 12. Pyrolysis reactor, 13. Volatile matter generated from high-temperature pyrolysis in-situ reforming, 14. Secondary reforming gas, 15. Pyrolysis high-temperature semi-coke, 16. Low-temperature pyrolysis reforming unit, 17. Heating zone of reforming unit, 18. Reforming zone of low-temperature reforming unit, 19. Low-temperature flue gas, 20. Cooling system, 21. High-temperature screw feeder, 22. High-temperature hydrogen-rich gas + light aromatics, 23. Biochar storage tank, 24. Screw slag discharger, 25. Cyclone separator, 26. High-temperature hydrogen-rich gas + light aromatics after dust removal, 27. Heat exchanger, 28. Low-temperature hydrogen-rich gas + light aromatics, 29 Light aromatics storage tank, 30 Condenser, 31 Hydrogen-rich gas, 32 Gas separation device, 33 Separated gas components, 34 Volatile matter uniform distribution device, 35 Throat, 36 Spiral low-temperature reforming device, 37 Air, 38 Ash, 39 Circulating fluidized bed biomass semi-coke burner, 40 Return valve. Detailed Implementation

[0023] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0025] The present invention provides the principle and apparatus structure for the preparation of hydrogen-rich gas and light aromatics by biomass pyrolysis, as follows: Figure 1As shown, the system includes a high-temperature pyrolysis in-situ reforming unit 6 and a low-temperature pyrolysis reforming unit 16. The high-temperature pyrolysis in-situ reforming unit 6 includes a heating zone 7, a pyrolysis reactor 12, a central reforming gas channel 11, and a feeding device 2. The pyrolysis reactor includes heat-conducting baffles 8, a volatile matter release channel 9, a pyrolysis zone 10, and a central reforming gas channel 11. The high-temperature pyrolysis in-situ reforming unit 6 is externally heated, relying on the arranged heat-conducting baffles 8 to enhance heat transfer and increase the heat transfer rate. No inert gas is introduced into the pyrolysis reactor; the reforming gas 3 from the pyrolysis process is introduced through the central reforming gas channel 11 and diffuses outwards from the center. Biomass 1 with a particle size ≤80mm and moisture content ≤20% enters the pyrolysis reactor 12 through the feeder 2. The temperature of the heating zone is set between 800-1100℃, and the temperature of the volatile matter gas channel is close to that of the heating zone. In the pyrolysis reactor, the temperature is high on the side near the volatile matter release zone and low on the side near the central reforming gas channel 11. Heat transfer is enhanced using heat-conducting baffles. Biomass pellets first pyrolyze on the high-temperature side, generating a high-temperature biomass semi-coke bed. The released volatile matter enters the volatile matter release zone. Heat is gradually transferred from the high-temperature biomass semi-coke to adjacent biomass pellets. The volatile matter released after the pyrolysis of adjacent biomass pellets passes radially through the high-temperature biomass semi-coke bed. During this process, catalytic reforming of the semi-coke and gas-phase reforming between volatile matter and reforming agent occur, accompanied by thermal decomposition of the volatile matter. Fatty acids, hydrocarbon chains, and oxygen-containing functional groups in the volatile matter gradually break down, generating more small-molecule gaseous components (H2, CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, etc.). Polycyclic aromatic hydrocarbons in the volatile matter gradually undergo condensation reactions, generating heavier components. Furthermore, the introduced reforming agent has a certain activation effect on the biomass semi-coke, improving its specific surface area and pore structure.

[0026] After the volatiles enter the volatiles release channel 9, the residence time of the volatiles is controlled within 60 seconds. Under high temperature and in an environment containing reforming agents (H2, CO2, water vapor, etc.), the thermal cracking and reforming reactions gradually intensify, the heavy components in the gas phase bio-oil polymerize more intensely, and carbon deposits are generated. At the same time, the aliphatic hydrocarbons, oxygen-containing components and functional groups in the bio-oil are further reformed and cracked, generating more small molecule non-condensable gas components.

[0027] The low-temperature pyrolysis reforming unit 16 mainly consists of a heating zone 17, a volatile matter uniform distribution device 34, a cooling system 20, and a screw conveyor 24. The pyrolytic high-temperature semi-coke 15 and volatile matter gas generated in the high-temperature pyrolysis in-situ reforming unit 6 enter the low-temperature pyrolysis reforming unit 16 through the high-temperature screw feeder 21 and the volatile matter release channel 9, respectively. To ensure uniform distribution of volatile matter in the low-temperature pyrolysis reforming unit 16, a volatile matter uniform distribution device 34 is provided. The temperature of the heating zone is maintained by electric heating or flue gas heating, at 600-900℃, with a residence time of 10-30 seconds. The secondary reforming gas 14 is a mixture of one, two, or more reforming agents, such as CO2, H2O, and H2. The reforming agent is introduced into the high-temperature pyrolysis in-situ reforming unit 6, where it comes into uniform contact with the biomass semi-coke and volatiles. Through the gas-solid catalytic reforming of the biomass semi-coke and the gas-gas reforming of the reforming agent and volatiles, the conversion of bio-oil components into light aromatics is promoted. During this process, non-condensable small-molecule gases such as H2, CO, and CO2 are further generated. Simultaneously, the reforming agent has a certain activating effect on the biomass semi-coke, helping to maintain its catalytic activity during the low-temperature reforming process. During the reforming process, the biomass semi-coke bed and volatiles slowly move downwards. After being cooled by the cooling system 20, they are discharged into the biochar storage tank 23 via the screw conveyor 24. The generated high-temperature hydrogen-rich gas + light aromatics 22 is discharged from the bottom and undergoes gas-solid separation through the cyclone separator 25. The high-temperature hydrogen-rich gas + light aromatics 26 after dust removal is cooled by the heat exchanger 27. The cooled hydrogen-rich gas + light aromatics 28 is condensed by the condenser 30, and the generated light aromatics enter the light aromatics storage tank 29. After the hydrogen-rich gas is separated by the gas separation device 32, the separated gas components 33 (H2, CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, etc.) are obtained. A portion of the separated H2 and CO2 are supplied as reforming agents to the high-temperature and low-temperature pyrolysis reforming units.

[0028] Figure 2 The present invention provides a flowchart of the steps for preparing hydrogen-rich gas and light aromatics by biomass pyrolysis.

[0029] Example 1 This embodiment provides a method such as Figure 3The illustrated biomass pyrolysis unit for producing hydrogen-rich gas and light aromatics includes a high-temperature pyrolysis in-situ reforming unit 6 and a low-temperature pyrolysis reforming unit 16. The heating zone of the high-temperature pyrolysis in-situ reforming unit 6 is heated by high-temperature flue gas 4 at a temperature of 800-1100°C. The discharged medium-temperature flue gas 5 enters the low-temperature pyrolysis reforming unit 16 and is heated to a temperature of 600-900°C before being discharged as low-temperature flue gas 19. The high-temperature pyrolysis in-situ reforming unit 6 relies on external heating, with heat transfer from the high-temperature biomass semi-coke on the high-temperature side heating the biomass particles on the inner side, while heat transfer is enhanced by heat-conducting baffles 8. The low-temperature pyrolysis reforming unit 16 maintains its temperature through external heating and the pyrolysis high-temperature semi-coke 15 from the high-temperature pyrolysis in-situ reforming unit 6, as well as the volatiles 13 generated during the high-temperature pyrolysis in-situ reforming.

[0030] Biomass 1 with a particle size ≤30mm and moisture content ≤20% enters the pyrolysis reactor 12 through the feeder 2. Reforming gas 3 (volume ratio of CO2 to water vapor 1:1-1:2) enters the pyrolysis reactor 12 through the central reforming gas channel 11. Biomass 1 undergoes high-temperature pyrolysis in the pyrolysis reactor to generate gaseous volatile components (pyrolysis gas, bio-oil, pyrolysis water) and solid biomass semi-coke. The volatiles from the pyrolysis of biomass particles close to the wall of the volatile release channel 9 directly enter the volatile release channel 9, while the volatiles released from biomass particles far from the volatile release channel 9 need to pass through the already generated biomass semi-coke layer. Since the high-temperature pyrolysis in-situ reforming device 6 is a slow pyrolysis, the release rate of volatiles is limited, and the gas residence time in the high-temperature pyrolysis semi-coke 15 is relatively long (10s), and the effects of gas-solid catalytic reforming and gas-gas reforming are more obvious. By controlling the rotational speed of the high-temperature screw feeder 21, adjusting the axial movement speed of the pyrolysis high-temperature semi-coke 15 and the temperature distribution within the reactor, the temperature near the central reforming gas channel 11 is maintained at 700℃. The volatiles generated in the pyrolysis reactor 12 gradually enter the volatiles release channel 9, where the temperature is 900-1100℃. The residence time of the volatiles in the channel is maintained at 10-20 seconds, allowing the heavy components in the bio-oil to fully react with the reforming agent. Simultaneously, oxygen-containing functional groups and aliphatic hydrocarbons undergo thermal decomposition, with CH4 and C2-C3 undergoing thermal decomposition to generate more H2.

[0031] The volatiles 13 generated by high-temperature pyrolysis in-situ reforming enter the low-temperature pyrolysis reforming unit 16 through the volatiles uniform distribution device 34, and come into contact with the secondary reforming gas 14 to begin gas-phase reforming. The volume ratio of CO2 to water vapor is maintained at 1:1-1:3. The pyrolysis high-temperature semi-coke 15 is uniformly added to the low-temperature pyrolysis reforming unit 16 through the high-temperature screw feeder 21 to form the low-temperature reforming unit reforming zone 18, which catalytically reforms the volatiles. The height of the low-temperature reforming unit reforming zone 18 in the reactor is controlled by the rotation speed of the screw slag discharger 24, the gas residence time is maintained at 10-20 seconds, and the temperature at the center of the reactor is maintained at 650-800℃. After being cooled by the cooling system 20, the reformed biomass semi-coke is discharged through the spiral slag discharger 24. The generated high-temperature hydrogen-rich gas + light aromatic hydrocarbons 22 are discharged from the bottom and pass through the cyclone separator 25 for dust removal, the heat exchanger 27 for heat exchange, the condenser 30 for gas-liquid separation, and the gas separation device 32 for separating various gas components 33 (H2, CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, etc.). A portion of the separated H2 and CO2 are supplied as reforming agents to the high-temperature and low-temperature pyrolysis reforming units.

[0032] Example 2 This embodiment provides a method such as Figure 4 The biomass pyrolysis device shown is used to produce hydrogen-rich gas and light aromatics. This biomass pyrolysis device integrates a high-temperature pyrolysis in-situ reforming unit 6 and a low-temperature pyrolysis reforming unit 16 into one device. There is no high-temperature semi-coke conveying device in the middle. The design of the throat 35 is used to increase the height of the high-temperature semi-coke bed to play a material sealing role. At the same time, the throat 35 is used to achieve uniform mixing of high-temperature semi-coke. The rest is the same as in Example 2.

[0033] Example 3 This embodiment provides a method such as Figure 5 The apparatus shown is for preparing hydrogen-rich gas and light aromatics by biomass pyrolysis. The low-temperature pyrolysis reforming apparatus is a spiral low-temperature pyrolysis reforming apparatus 36. Biomass semi-coke 15 from the high-temperature pyrolysis in-situ reforming apparatus 6, volatiles 13 generated by high-temperature pyrolysis in-situ reforming, and secondary reforming agent 14 interact in the spiral low-temperature pyrolysis reforming apparatus 36. The residence time is controlled by the spiral rotation speed. The outer shell of the reforming apparatus is provided with a flue gas channel. All other aspects are the same as in Example 2.

[0034] Example 4 This embodiment provides a method such as Figure 6The illustrated biomass pyrolysis apparatus for producing hydrogen-rich gas and light aromatics includes a high-temperature pyrolysis in-situ reforming unit 6 and a low-temperature pyrolysis reforming unit 16. Flue gas is supplied by a circulating fluidized bed biomass semi-coke burner 39, using air 37 as the carrier gas and oxidant, and biomass semi-coke as fuel. Ash 38 is discharged from the bottom and returned via a return valve 40. All other operations are the same as in Example 2.

[0035] Application Example 1 This application example provides a typical application of preparing hydrogen-rich gas and light aromatics using biomass pyrolysis as described in Example 1, as detailed below: (1) Compressed corn stalk pellets with a particle size ≤ 40 mm and a moisture content of 15% are fed into the pyrolysis zone 10 of the high-temperature pyrolysis in-situ reforming unit 6 via a screw feeder. The high-temperature pyrolysis in-situ reforming unit 6 is heated by high-temperature flue gas. The temperature of the heating zone is 1000℃, the temperature of the volatile matter release channel 9 is 1000℃, the number of heat-conducting baffles 8 is 6, the temperature around the central reforming gas channel 11 is 800℃, the reforming agent introduced is CO2 + water vapor, the volume ratio of CO2 / water vapor is 1:1, the mass ratio of CO2 to biomass raw material is 0.1, the average residence time of the generated volatile matter in the radial direction is 5 seconds, and the residence time in the volatile matter release channel 9 is about 8 seconds. The composition of the generated gas and the quality of the bio-oil are shown in Table 1.

[0036] (2) In the low-temperature pyrolysis reforming unit 16, the heating zone temperature is maintained at 800℃, the bio-semi-coke bed temperature is about 750℃, and the reforming agents are CO2 and water vapor, with a CO2 to water vapor volume ratio of 1:2. The gas residence time of volatiles in the low-temperature pyrolysis reforming unit 16 is about 8 seconds. The gas composition and bio-oil quality are shown in Table 1. Compared with the gas composition in the high-temperature pyrolysis in-situ reforming unit 6, after low-temperature pyrolysis-reforming treatment, the H2 volume content increases from 37% to 55%, the oxygen and water content in the bio-oil decreases significantly, and the contents of benzene, toluene, and xylene increase from 30%, 25%, and 18% to 42%, 31%, and 20%, respectively. The high content of hydrogen and light aromatics is beneficial for the high-value utilization of hydrogen-rich gas and aromatics.

[0037] Table 1 Operating conditions and experimental results

[0038] Note: wt.% - mass percentage; In summary, the apparatus and method for producing hydrogen-rich gas and light aromatics from biomass pyrolysis provided by this invention are suitable for processing small-particle-size biomass feedstocks, have strong feedstock applicability, are suitable for scale-up, can generate high-quality hydrogen-rich gas and light aromatics, have significant carbon emission reduction effects, and have technical, economic and environmental benefits of low-carbon conversion and high-value-added utilization.

[0039] Comparative Example 1: The device in which heat transfer is in the same direction as volatile release. Experimental conditions: The same device structure as in Example 1 of this invention was used, but the operation method was changed so that the heat transfer direction was the same as the volatile release direction (i.e., the volatiles were discharged from the low temperature zone). The other conditions were the same as in Application Example 1.

[0040] Expected results: H2 content approximately 30-35%, bio-oil water content 15-20%, oxygen content 12-18%, and benzene / toluene / xylene content lower than the combined operation data of this invention.

[0041] Results Analysis: When the heat transfer direction is the same as the volatile release direction, the gas collection channel should be placed in the center of the reactor. Heat is transferred from the high-temperature zone (near the heating zone) to the low-temperature zone (near the center zone), and volatiles are also released from the high-temperature zone to the low-temperature zone. When the volatiles generated in the high-temperature zone pass through the semi-coke layer in the low-temperature zone, the degree of in-situ thermal cracking and catalytic reforming of the volatiles with the introduced reforming agent and bio-semi-coke is low. Moreover, because the central gas collection channel is located in the low-temperature zone of the reactor, the thermal cracking effect is very poor, resulting in a low degree of cracking of bio-oil in the generated volatiles and a low degree of water participation in the reaction. This leads to low H2 content in the gas generated in S1 and high water and O content in the bio-oil. When the aforementioned low-quality bio-oil and hydrogen-containing gas are introduced into S2, the load on the S2 treatment increases. Since S2 is a low-temperature reforming unit, the reforming effect is limited, and the deoxygenation capacity is suppressed. Ultimately, this results in high water content, high oxygen content, and low light aromatics in the generated bio-oil, and low hydrogen content in the generated gas.

[0042] Comparative Example 2: Control experiment without the addition of reforming agent Experimental conditions: The same apparatus as in Example 1 was used, but no reforming agent was introduced (CO2, H2O, and H2 were not added).

[0043] Expected results: H2 content approximately 25-30%, bio-oil quality between that of high-temperature operation alone and high-low temperature combined operation.

[0044] Results Analysis: Without reforming agent, the volatiles generated in S1 are released from the low-temperature zone to the high-temperature zone. Upon passing through the high-temperature semi-coke layer, catalytic cracking occurs instead of catalytic reforming. The bio-oil after catalytic cracking enters the gas collecting channel for further high-temperature cracking. Compared to catalytic reforming, catalytic cracking more readily generates carbon deposits, reducing H2 and CO yields, and more readily generates polycyclic aromatic hydrocarbons (PAHs) rather than monocyclic aromatic hydrocarbons (MOHs). Furthermore, because reforming agents promote the formation of a well-developed pore structure and porous surface in biochar, they are beneficial for improving its catalytic activity. Without reforming agent, the H2 content in the gas generated in S1 is reduced, and the bio-oil contains lower levels of light aromatic hydrocarbons while increasing levels of heavy PAHs. When the aforementioned hydrogen-containing gas and bio-oil enter S2, due to the low temperature and underdeveloped pore structure of the biochar, the catalytic effect of the biochar on the bio-oil is poor. This results in a very limited improvement in the quality of the hydrogen-containing gas and bio-oil by S2, ultimately leading to low hydrogen content in the hydrogen-containing gas and low-quality bio-oil.

Claims

1. An apparatus for producing hydrogen-rich gas and light aromatics through biomass pyrolysis reforming, comprising: The biomass high-temperature pyrolysis in-situ reforming device is used to perform high-temperature pyrolysis on biomass raw materials and to reform the released volatiles in-situ during the pyrolysis process. The volatile matter low-temperature non-in-situ reforming device is connected in series with the biomass high-temperature pyrolysis in-situ reforming device. It is used to receive high-temperature volatile matter and high-temperature biomass semi-coke generated from the high-temperature pyrolysis in-situ reforming device, and to perform low-temperature non-in-situ reforming on the high-temperature volatile matter. The biomass high-temperature pyrolysis in-situ reforming device adopts an external heating method, and the heat transfer direction inside the device is set to be opposite to the volatile matter release direction in the radial direction.

2. The apparatus according to claim 1, characterized in that: The biomass high-temperature pyrolysis in-situ reforming device includes: The pyrolysis reactor has, in a radial direction from the outside to the inside, a volatile matter release zone, a biomass pyrolysis zone, and a central reforming channel. A heating zone, located outside the pyrolysis reactor, is used to provide a heat source; Multiple heat-conducting baffles are installed inside the pyrolysis reactor, with one side connected to the wall of the heating zone, penetrating the volatile release zone and extending to the vicinity of the central reforming channel, to enhance radial heat transfer; The reforming agent addition device is connected to the central reforming channel and is used to introduce gaseous reforming agent into the pyrolysis zone.

3. The apparatus according to claim 2, characterized in that: The top and side near the heating zone of the volatile matter release zone are sealed, the upper part of the side near the pyrolysis zone is sealed, the lower part is provided with a porous screen or fence structure, and a gas channel is opened at the bottom to guide the volatile matter out; the central reforming channel adopts a porous screen or fence structure, and its open area is immersed in the material layer of the biomass pyrolysis zone.

4. The apparatus according to claim 1, characterized in that: The volatile matter low-temperature non-in-situ reforming device includes: The reforming reactor is equipped with a volatile matter uniform distribution device and a low-temperature reforming zone for containing biomass semi-coke. A heating zone is located outside the reforming reactor to maintain the reaction temperature at 600-900°C; A secondary reforming agent addition device is connected to the reforming reactor and is used to introduce reforming agent into the reforming zone (18); A semi-coke cooling and discharge system is located at the bottom of the reforming reactor to cool and discharge the biochar after the reaction.

5. The apparatus according to any one of claims 1-4, characterized in that: The biomass high-temperature pyrolysis in-situ reforming device and the volatile matter low-temperature non-in-situ reforming device are connected by a high-temperature screw feeder for conveying pyrolysis high-temperature semi-coke. The gas outlet of the volatile matter release zone is directly connected to the gas inlet of the low-temperature non-in-situ reforming device, and gas leakage is prevented by material seal or mechanical seal.

6. A method for producing hydrogen-rich gas and light aromatics by biomass pyrolysis reforming using the apparatus described in any one of claims 1-5, comprising the following steps: S1. High-temperature in-situ reforming step: Biomass raw materials are added to the biomass high-temperature pyrolysis in-situ reforming device and subjected to high-temperature pyrolysis under external heating conditions. Heat transfer is enhanced by heat-conducting baffles and the direction of heat transfer is controlled to be opposite to the direction of volatile release, so that the released volatiles pass through the high-temperature semi-coke layer and undergo in-situ thermal decomposition and catalytic reforming reactions with the introduced reforming agent and high-temperature semi-coke in the pyrolysis zone and volatile release zone, generating primary reformed volatiles and high-temperature semi-coke. S2, Low-temperature non-in-situ reforming step: The primary reforming volatiles and high-temperature semi-coke generated in step S1 are introduced into the low-temperature non-in-situ reforming unit for volatiles. The volatiles pass through the bed formed by the high-temperature semi-coke and undergo non-in-situ catalytic reforming reaction with the reforming agent introduced in the second step at 600-900℃, which further improves the hydrogen content and selectivity of light aromatics in the product, and generates hydrogen-rich gas and light aromatic products. S3. Post-processing steps: The hydrogen-rich gas and light aromatics generated in step S2 are subjected to gas-solid separation, cooling, condensation and gas-liquid separation to obtain high-purity hydrogen products and light aromatic oil products.

7. The method according to claim 6, characterized in that: In step S1, the reforming agent includes one or more of CO2, H2O, and H2; the temperature of the high-temperature pyrolysis is 800-1100℃; and the residence time of the volatiles in the volatiles release zone is no more than 30 seconds.

8. The method according to claim 6, characterized in that: In step S2, the temperature of the low-temperature reforming is 600-900℃; the residence time of the volatiles in the reforming zone of the low-temperature reforming unit is no more than 60 seconds.

9. The method according to claim 6, characterized in that: In step S3, the separated CO2 and / or H2 portions are recycled back to steps S1 and / or S2 as reforming agents.

10. The method according to claim 6, characterized in that: The biomass raw materials include one or more of the following: biomass, coal, oil shale, organic solid waste, waste plastics, sludge, electronic solid waste, and wind turbine blades. The raw material particle size is ≤80mm and the moisture content is ≤20%.

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