Integrated method and device for converting biomass / organic solid waste into synthesis gas based on membrane separation purification

Abstract

The present application relates to a kind of integrated biomass / organic solid waste conversion system and method for clean synthesis gas based on membrane separation reinforcement, the system includes oxygen permeation membrane, feeding device, filter membrane component and pyrolysis gasification reactor, for the pyrolysis gasification of biomass, organic solid waste or its mixture.The filter membrane component is assembled in pyrolysis gasification reactor, for the in-situ purification dust removal of gas generated by pyrolysis gasification.The filter membrane component can be filled with integrated or granular catalyst between pyrolysis gasification reactor, for the catalytic reforming of tar in gas generated by pyrolysis gasification, realize in-situ tar removal.Pyrolysis gasification membrane reactor can carry out biomass / organic solid waste pyrolysis gasification and catalytic reforming, to obtain high-quality clean synthesis gas.Pyrolysis gasification membrane reactor couples porous membrane and catalyst, with pyrolysis gasification, crude gas purification and reforming tar integration function.

Description

An integrated biomass / organic solid waste conversion method and apparatus for syngas production based on membrane separation and purification Technical Field

[0001] This invention patent belongs to the field of biomass / organic solid waste resource utilization technology, and specifically relates to an integrated biomass / organic solid waste conversion method and apparatus for producing synthetic fuel based on membrane separation enhancement. Background Technology

[0002] Greenhouse gas emissions have caused global warming, which has become a focus of attention for countries around the world. CO2 is the main source of greenhouse gases, and the high-value utilization of agricultural and forestry waste is an important way to achieve CO2 emission reduction. my country produces more than 3.5 billion tons of organic waste (such as corn cobs and sugarcane stalks) every year, but the overall utilization rate is not high (<10%). Biomass gasification to produce syngas is considered to be the most promising industrial development path in the 21st century due to its strong adaptability of raw materials, high conversion efficiency and diverse application of products [1]. The preparation of liquid fuels from syngas, such as bio-methanol and bio-jet fuel, is very important for promoting the low-carbon development of energy in my country. Whether this route can be put into practical application depends on the development of a compact reaction system and equipment.

[0003] The process of producing syngas from biomass at high temperatures is extremely complex, involving four overlapping processes: drying, pyrolysis, oxidation, and reduction. The crude gas produced by biomass gasification not only contains H2, CO, and CO2, but also impurities such as tar, small-molecule hydrocarbons, and particulate residues. These impurities can easily lead to catalyst deactivation and equipment blockage, affecting the synthesis of downstream liquid fuels. This hinders the rapid development of biomass gasification technology and limits its large-scale market application.

[0004] Syngas purification generally includes three units: dust removal, tar removal, and separation of impurity gases. High-temperature dust removal technology includes filtration dust removal (ceramic, particle layer, metal micropore and silicon carbide (SiC) etc.), cyclone dust removal and electrostatic dust removal technology. Yu Guangsuo et al. [2] reviewed the coke generation mechanism in the biomass gasification process. The article showed that the composition of biomass and ash components have a significant impact on coke formation. Apicella et al. [3] showed that the particle size of coke and semi-coke generated in the coal gasification process is about 0.1-1μm and 10-100μm, respectively. Therefore, it is expected that membranes with suitable pore size can quantitatively retain solid particles in the volatiles generated in the biomass gasification process. Porous SiC membranes are used for gas purification and have advantages such as good heat transfer performance, high mechanical strength, and thermal shock resistance. They not only have high purification efficiency and low flow resistance, but also reduce equipment space. In recent years, they have been used for high-temperature flue gas dust removal. Applying SiC membranes to biomass gasification processes is expected to achieve in-situ dust removal and separation of impurity gases from crude gas. In this process, solid particles in the crude gas are trapped by the microporous SiC membrane. The preliminarily purified syngas is evenly distributed into the SiC membrane microchannels and contacts the active center of the catalyst to achieve tar catalytic cracking and reforming. The reformed and upgraded syngas achieves in-situ separation of syngas and impurity gases through the small pore structure of the molecular sieve membrane on the outer layer of the ceramic membrane.

[0005] Regarding the syngas purification system, WO2011 / 019477A1[4] reported a coal-to-syngas purification system, which includes a water-gas shift reactor, a first operating unit, and a second operating unit. The first operating unit includes an H2 / CO2 permeation membrane to provide hydrogen-rich gas on the permeate side and a hydrogen-poor gas flow on the permeate side. The second operating unit recovers H2 and CO from the hydrogen-poor gas flow on the permeate side to obtain a separate CO2-rich gas flow. This process mainly enriches single-component or multi-component gases through the membrane and does not involve solid particle retention. Xie Jianjun et al.[5] reported a study on the purification of crude gas composition of biomass gasification by high-temperature ceramics. The purification device used included a biomass gasifier for biomass pyrolysis gasification, a cyclone separator for dust removal, a ceramic tube dust removal chamber for further dust removal, and a spray tower for tar removal. The results showed that the dust concentration at the dust collector outlet was 10-40 mg / m³. 3 The dust removal rate is 92.3%–99.8%, and the tar removal rate is 31.0%–92.5%. The ceramic tube dust removal chamber and the gasification device are two separate units in this process.

[0006] Catalytic reforming is a crucial component of biomass gasification processes, used to further convert pyrolysis products such as tar and hydrocarbons into syngas. Currently, catalysts primarily utilize natural catalysts (such as dolomite and olivine), inorganic salt catalysts (such as alkali metals and metal oxides), and synthetic catalysts (such as nickel-based and semi-coke-based metal catalysts). The volatile pyrolysis products have complex compositions and readily form solid carbon layers, leading to catalyst deactivation. Therefore, obtaining catalysts with high-temperature resistance to sintering and carbon deposition is a key research focus in this field.

[0007] CA 2787672[6] discloses a gasification reforming method for cracking organic impurities in a gas. In this method, the gasified gas is contacted with at least one catalyst in the presence of an oxidizing medium. The gasified gas is discharged after a multi-step treatment. The first stage includes a zirconium catalyst bed and a noble metal catalyst bed. The second stage includes a metal catalyst. In this method, the oxidizing medium is fed into the first stage bed. The noble metal catalyst reduces the risk of deactivation and increases the lifespan of the metal catalyst. However, this method does not involve membrane separation purification.

[0008] RU2638350C1[7] reports an integrated membrane-catalytic reactor, which is a hollow cylinder with a catalyst composition of nickel-45%, aluminum-5%, and Co3O4-50%, using a palladium alloy-containing hydrogen selective membrane to separate hydrogen to obtain ultrapure hydrogen. In addition, US10193176B2[8] reports a system and method for synthesizing ultrapure hydrogen from biomass waste. The invention includes a gasifier, an oil and tar filter, a steam generator, a water-gas shift reactor ("WGS"), a heat exchange two-phase water separator, a scrubber, and a hydrogen separator. Hydrogen fluid conduits connect the gasifier and the steam generator to the WGS, the WGS to the two-phase separator, the two-phase separator to the scrubber, and the scrubber to the hydrogen separator to obtain high-purity hydrogen. The process does not involve high-temperature porous membrane purification for dust removal or catalytic reforming for tar removal.

[0009] Currently, the various units (gasification, purification, catalytic reforming, etc.) in the biomass pyrolysis gasification process are relatively independent, resulting in bottlenecks such as low system integration and large footprint. Given the dispersed nature of biomass resources, small-scale, modular gasification systems hold greater promise. Developing compact, modular gasification systems allows for flexible adjustments to scale, feedstock, and site selection, reducing the biomass collection radius (generally <50 km). Therefore, constructing a novel integrated reactor with enhanced membrane separation to achieve in-situ purification of syngas during the gasification process is a worthwhile research direction.

[0010] [1] Li Xueqin, Liu Peng, Wu Youqing, Lei Tingzhou, Wu Shiyong, Huang Sheng, Current status and prospects of biomass gasification technology, Forest Products Chemistry and Industry 42(2022)113-120.

[0011] [2] Q.He, Q.Guo, K.Umeki, L.Ding, F.Wang, G.Yu, Soot formation during biomass gasification: Acritical review, Renewable and Sustainable Energy Reviews, 139 (2021) 110710.

[0012] [3]B.Apicella,O.Senneca,C.Russo,S.Heuer,L.Cortese,F.Cerciello,V.Scherer,M.Schiemann,A.Ciajolo,Separation and characterization ofcarbonaceous particulate(soot and char)produced from fast pyrolysis of coalin inert and CO2atmospheres,Fuel,201(2017)118-123.

[0013] [4] K. Anthony, Yu-Chung, AHRadhakrishna, KPPrakash, MSMichael, LWCook, Syngas cleanup section with carbon capture and hydrogen-sensitive membrane, 2011, PCT US2011 / 042291, WO 2011 / 019477 A1.

[0014] [5] Xie Jianjun, Lang Lin, Yang Wenshen, Liu Huacai, Chen Jian, Yin Xiuli, Wu Chuangzhi, Experimental study on high temperature ceramic purification of crude gas dust from biomass gasification, Chemical Industry Progress, 36(2017)2903-2909.

[0015] [6] S.Pekka, K.Esa, H.Ilkka, Method of reforming gasification gas, 2018, PCT / FI2011 / 050181, WO 2011 / 107661.

[0016] [7]Tsodikov Mark Veniaminovich,Fedotov Aleksej Stanislavovich,AntonovDmitrij Olegovich,Uvarov Valerij Ivanovich,KSN,Integrated membrane-catalytic reactor and coproduction method of synthesis gas and ultrapurehydrogen,Russia,2006,RU 2638350 C1.

[0017] [8]H.Tawfik, System and method for production of ultra-pure hydrogen from biomass, 2019, US10193176B2. Summary of the Invention

[0018] The technical problem this invention aims to solve is that current biomass pyrolysis gasification processes involve relatively independent units (gasification, purification, catalytic reforming, etc.), resulting in bottlenecks such as low system integration and large footprint. This patent proposes an integrated biomass / organic solid waste conversion system and method for synthetic fuel production based on membrane separation enhancement. This system can meet the requirements of multi-point decentralized layout and reduce the collection radius of biomass / organic solid waste (generally <50 km). This invention integrates a pyrolysis gasification membrane reactor into a single system, realizing the preparation of clean fuel gas through biomass pyrolysis gasification reforming. Specifically, the pyrolysis gasification membrane reactor uses a porous silicon carbide membrane for crude gas purification and integrates it with the biomass gasification process. Simultaneously, an integral catalyst is used for the reforming and removal of impurities such as tar from the crude gas, thereby improving the overall efficiency of biomass gasification and reforming reactions.

[0019] The technical solution adopted in this invention:

[0020] A method for biomass conversion to syngas based on membrane reaction includes the following steps:

[0021] The oxygen-containing feed gas, gasification agent, and biomass feed are mixed and continuously fed into the membrane reactor.

[0022] On the feed side of the membrane reactor, the biomass undergoes pyrolysis and gasification. After particulate impurities are removed by the filter membrane in the membrane reactor, the gasification products enter the permeate side of the filter membrane. Furthermore, the reaction residence time of the mixed feed is controlled by baffles on the feed side.

[0023] The permeation side is supplied with carrier gas to purge the gasification products. After condensation and removal of liquid components, syngas containing mainly CO and H2 is obtained.

[0024] The permeate side of the filter membrane is also provided with a catalytic reforming catalyst layer, on which the gasification products undergo catalytic reforming.

[0025] The membrane reactor is tubular, with the raw material side inside the tube. A filter membrane is installed on the tube wall. The filter membrane is made of silicon carbide with a pore size of 0.05-100μm, a tube diameter of 1-10cm, a thickness of 0.1-1cm, and a length of 200-1000mm. A rotating rod is installed inside the tube, with baffles distributed on the rod. The effective baffle diameter is 1-25mm, the angle between the effective baffle and the tube cross-section is 0-45°, the effective baffle rotates for 1-20s every 30s, and the rotation speed of the effective baffle is 10-500r / min.

[0026] The catalyst in the catalytic reforming catalyst layer is any one or more of Ca, Zn, Mg, Fe, K, and Ni-based catalysts.

[0027] The vaporizing agent is selected from any one or more of carbon dioxide, air, oxygen, and water vapor.

[0028] The membrane reactor operates in a temperature range of 400–1000℃.

[0029] The biomass raw material has a particle size of 0.1-5 mm, an ash content of 0.5-15%, and a carbon content of 35-60%.

[0030] The weight ratio of gasification agent to biomass raw material is 0.5-2.

[0031] The oxygen-containing raw gas is obtained by separating the oxygen through an oxygen-permeable membrane to enrich the oxygen content.

[0032] The residence time of biomass feedstock in the reactor is 5-1200s.

[0033] During the synthesis process, the yield of semi-coke is predicted and calculated using the following formula:

[0034] Y = a * x 1 2 +b*x2 2 +c*x1*x2+d*x1+e*x2+f;

[0035] x1 refers to the carbon content (%) in the biomass, x2 refers to the membrane pore size (μm); Y is the semi-coke yield; a / b / c / d / e / f are parameters;

[0036] An apparatus for biomass conversion to syngas based on membrane reaction, comprising:

[0037] Oxygen-permeable membranes are used to separate oxygen from feed gas.

[0038] A mixer used to mix oxygen and a vaporizing agent;

[0039] The feeder is used to mix biomass feedstock with oxygen and gasifying agent and then transport it into the membrane channel of the pyrolysis gasification membrane reactor.

[0040] The pyrolysis vaporization membrane reactor is equipped with a porous tubular membrane, with the tube side connected to the feeder and the shell side connected to the condenser.

[0041] The porous tubular membrane is made of ceramic with a pore size of 0.05-100μm, a tubular membrane diameter of 1-10cm, a tubular membrane thickness of 0.1-1cm, and a tubular membrane length of 200-1000mm.

[0042] The tubular membrane is further provided with a catalytic reforming catalyst layer on its permeation side.

[0043] The present invention has the following beneficial effects:

[0044] This invention proposes an integrated biomass / organic solid waste conversion system and method for producing synthetic fuels based on membrane separation enhancement. The system integrates a pyrolysis gasification membrane reactor into a single system, enabling the production of clean fuel gas through biomass pyrolysis gasification and reforming. Specifically, the pyrolysis gasification membrane reactor utilizes a porous silicon carbide membrane for crude fuel gas purification and is integrated with the biomass gasification process. Simultaneously, an integral catalyst is used for the reforming and removal of impurities such as tar from the crude fuel gas, thereby comprehensively improving the efficiency of both biomass gasification and reforming reactions. Attached Figure Description

[0045] Figure 1 is a schematic diagram of the vertical continuous injection pyrolysis vaporization membrane reaction system and method for generating clean synthesis gas according to the present invention.

[0046] Figure 2 is a schematic diagram of the rotating baffle of the vertical continuous injection pyrolysis vaporization membrane reaction system and method for generating clean synthesis gas according to the present invention.

[0047] Figure 3 is a schematic diagram of the vertical intermittent pyrolysis vaporization membrane reaction system and method for generating clean synthesis gas according to the present invention.

[0048] Figure 4 is a schematic diagram of the horizontal continuous injection pyrolysis vaporization membrane reaction system and method for generating clean synthesis gas according to the present invention.

[0049] Figure 5 is a schematic diagram of a biomass gasification reforming unit.

[0050] Figure 6 is a schematic diagram of the analysis process for tar and solid particle content in the product.

[0051] Figure 7 shows the effect of temperature on the distribution of poplar and corn cob products: (a) Poplar gas and semi-coke yield, (a') Poplar gas composition and H2 / CO, (b) Corn cob gas and semi-coke yield, (b') Corn cob gas composition and H2 / CO.

[0052] Figure 8 shows the effect of different S / B ratios on the distribution of poplar products: (a) gas and semi-coke yields, (b) gas composition and H2 / CO ratio.

[0053] Figure 9 shows the filter paper obtained with different SiC membrane pore sizes: no membrane (a) and membrane pore sizes of 50 μm (b), 10 μm (c) and 0.1 μm (d).

[0054] Figure 10 shows SEM images (1-2) and particle size distribution (3) of solid particles in the tar produced by the pyrolysis and gasification of poplar wood at 800℃ at different magnifications. (a): No gasifying agent, no silicon carbide membrane; (b): Gasifying agent is water vapor, S / B (water vapor to biomass mass ratio) = 1; (c): Gasifying agent is water vapor, S / B (water vapor to biomass mass ratio) = 1. The pore size of the silicon carbide membrane is 0.1 μm.

[0055] Figure 11 is a physical image of a cyclic monolithic nickel-based catalyst.

[0056] Figure 12 shows the effect of the cyclic monolithic nickel-based catalyst on the product distribution: (a) tar yield, (b) gas production, (c) gas composition distribution and H2 / CO, and (d) solid particle yield and rejection rate.

[0057] Figure 13 is a surface plot showing the impact on the semi-coke yield prediction process.

[0058] in:

[0059] In Figure 1, 1-Oxygen-permeable membrane; 2-Inlet pipe; 3-Mixer; 4-Raw material hopper; 5-Feeder; 6-Filter membrane; 7-Catalyst; 8-Reactor; 9-Gasifier; 10-Semi-coke collector; 11-Cooling unit; 12-Centrifugal pump; 13-Compressor;

[0060] In Figure 3, 1-filter membrane; 2-catalyst; 3-reactor; 4-gasifier; 5-cooling unit; 6-centrifugal pump; 7-compressor; In Figure 4, 1-oxygen permeable membrane; 2-inlet pipe; 3-mixer; 4-raw material hopper; 5-feeder; 6-filter membrane; 7-catalyst; 8-reactor; 9-gasifier; 10-semi-coke collector; 11-cooling unit; 12-centrifugal pump; 13-compressor; Detailed Implementation

[0061] The invention will now be further described with reference to the accompanying drawings.

[0062] As shown in Figure 1, the present invention relates to an integrated biomass organic solid waste conversion device for producing synthetic fuel based on membrane separation enhancement, comprising:

[0063] Oxygen-permeable membranes are used to separate oxygen from feed gas.

[0064] The pyrolysis gasification membrane reactor has a porous membrane installed inside, and the retention side of the porous membrane is connected to the biomass feed device and the permeation side of the oxygen-permeable membrane; the retention side of the porous membrane is used for the biomass pyrolysis gasification reaction, and the porous membrane is used to purify particulate impurities in the mixture of the pyrolysis gasification reaction.

[0065] Catalytic reforming catalysts are mixed with biomass feedstocks or placed on the outside of porous membrane tubes in pyrolysis gas membrane reactors to reform purified gases. During the synthesis of feedstock gas, biomass materials can directly undergo pyrolysis to generate syngas containing H2 and CO. The porous membrane surface used may not have catalytic properties. Alternatively, catalytic cracking catalysts can be used on the outside for deep cracking and reducing oil generation.

[0066] In addition to biomass, the biomass mentioned can also be one or more of waste plastics, household waste, urban sludge, gutter oil, industrial waste oil, coal, or their semi-coke products.

[0067] The porous membrane is tubular or bag-type, and if a catalytic reforming catalyst is present, it is located on the outside or inside of the porous membrane tube.

[0068] The porous membrane is made of silicon carbide or ceramic.

[0069] The porous membrane tube may or may not include baffles, which are used to regulate the reaction residence time of biomass and other raw materials in the membrane tube.

[0070] The pyrolysis gasification membrane reactor includes a vertical membrane reactor (Figures 1 and 3) and a horizontal membrane reactor (Figure 4).

[0071] The catalytic reforming catalyst is one or more of biomass semi-coke, coal semi-coke, and tire semi-coke, and the active component of the catalyst is any one or more of metals such as Ca, Zn, Mg, Fe, K, and Ni.

[0072] The mass ratio of the active component of the catalytic reforming catalyst to the semi-coke is 0.01:1 to 0.10:1.

[0073] The biomass feeder is a screw feeder.

[0074] It also includes a gasifying agent delivery device connected to the retrieval side of the porous membrane for mixing the gasifying agent into the feedstock of the catalytic reforming reaction.

[0075] The vaporizing agent is selected from any one or more of carbon dioxide, air, oxygen, and water vapor.

[0076] Based on the above apparatus, in one example, the present invention provides an integrated apparatus for converting biomass organic solid waste into synthetic fuel based on membrane separation enhancement, comprising:

[0077] Based on the above methods, the membrane reaction-based biomass conversion to syngas apparatus of the present invention includes:

[0078] Oxygen-permeable membranes are used to separate oxygen from feed gas.

[0079] A mixer used to mix oxygen and a vaporizing agent;

[0080] The feeder is used to mix biomass feedstock with oxygen and gasifying agent and then transport it into the membrane channel of the pyrolysis gasification membrane reactor; the pyrolysis gasification membrane reactor is equipped with a porous tubular membrane, with the tube side connected to the feeder and the shell side connected to the condenser.

[0081] The following is a detailed implementation and testing process of this patent:

[0082] Gasification Experiment

[0083] Biomass was used as the raw material, with a dosage of approximately 3g. The reaction temperature was 700-900℃, nitrogen was used as the carrier gas, and the flow rate was 200ml·min. -1 The gasifying agent was water vapor, with S / B (water vapor to biomass mass ratio) of 0.6, 1, and 1.4. The silicon carbide membranes had pore sizes of 0.1, 10, and 50 μm. The silicon carbide membranes were 200 mm long, with an outer diameter of 35 mm and an inner diameter of 23 mm. The reaction apparatus is shown in Figure 5. Before the reaction began, nitrogen was used to purge the entire reaction system, and the vaporization chamber and gasifier were preheated to 130°C and 800°C, respectively. After reaching the set temperatures, the water injection pump was turned on, and the basket containing biomass was slowly lowered into the constant temperature zone to begin the reaction. The reaction time was 20 min to ensure complete biomass reaction. The volatiles produced in the reaction were condensed using a four-stage condenser. Ice water was used as the coolant in the first and fourth stage cold traps, while liquid nitrogen was used in the second and third stage cold traps. Non-condensable gases were collected through a gas bag and analyzed offline using gas chromatography-TCD (GC-TCD) to determine the composition and yield of the gaseous products. The product obtained from the cold trap was thoroughly washed with tetrahydrofuran (THF) and transferred to a sample vial for subsequent product analysis.

[0084] Product analysis methods

[0085] The analysis of tar and particulate matter content in the product was performed according to the national standard GB / T 40508-2021 "Determination of Tar and Dust Content in Biomass Gas". The analytical process is shown in Figure 6. The filter paper used was an organic quantitative filter paper with a pore size of 0.1 μm, and the filtration device was a sand core filter. The solid residue after the biomass reaction is semi-coke, and its yield, Y, can be obtained by weighing. char The formulas for calculating the solid particle content and solid particle retention rate in tar are shown in formulas (1) and (2).

[0086]

[0087]

[0088] In the formula, Y particle m1 represents the yield of solid particles, in %; m2 represents the mass of blank filter paper, in grams (g); m3 represents the mass of filter paper after filtration of the sample, in grams (g); m4 represents the mass of filter paper after filtration of the sample. biomass X represents the mass of raw biomass, expressed in grams (g); particle Y1 represents the solid particle retention rate, in %; Y2 represents the solid particle yield in the blank experiment, in %; Y1 represents the solid particle yield when using a silicon carbide membrane, in %.

[0089] The filtrate was transferred to a sample bottle for rotary evaporation to remove the solvent from the mixture. The rotary evaporation conditions were: 0°C for the cooling circulation device, 31°C for the water bath, and 35 r / min for the rotary evaporation speed. The rotary evaporation was terminated when the sample was uniform and bubble-free, and no liquid droplets fell after 20 seconds. The tar content in biomass gasification fuel gas was calculated using formula (3).

[0090]

[0091] In the formula, Y tar This indicates the tar content in syngas, expressed in grams per cubic meter (g / m³). 3 m0 represents the mass of the rotary evaporator flask, in grams (g); m3 represents the sum of the masses of the rotary evaporator flask and the tar, in grams (g); V represents the volume of the fuel gas, in cubic meters (m³). 3 Test Result Analysis:

[0092] 1) Properties of raw materials

[0093] Poplar wood and corn cob raw materials represent forestry and agricultural raw materials, respectively. Their industrial and elemental analysis results are shown in Table 1. The ash content and carbon content of poplar wood are 4.9% and 46.47%, respectively, higher than those of corn cob (1.94% and 41.25%).

[0094] Table 1. Industrial and elemental analysis of poplar and corn cob raw materials.

[0095]

[0096] a Air-dried base; b Anhydrous and ash-free substrate; c : Calculated by difference.

[0097] 2) Effect of reaction temperature on product distribution

[0098] Figure 7 shows the effect of different gasification temperatures (700-900℃) on the distribution of gasification products from poplar (a) and corn cob (b). With increasing temperature, the gas yield from poplar rapidly increased from 42.70% at 700℃ to 60.2% at 800℃, then slowly increased to 68.7% at 900℃. This process was accompanied by a gradual decrease in the semi-coke yield, from 8.9% at 700℃ to 2.8% at 900℃. Corn cob feedstock exhibited a similar trend, but the changes in gas and semi-coke yields were more significant in the 800-900℃ range. The gas yield increased from 51.9% at 800℃ to 76.2% at 900℃, while the semi-coke yield decreased from 7.3% at 800℃ to 1.1% at 900℃. The gaseous composition distributions of poplar and corn cob raw materials are shown in Figures 7(a') and (b'). The components in the poplar gaseous products increase with increasing temperature, but show a slow increasing trend after 800℃. The H2 / CO ratio continues to increase after 800℃, but the increasing trend of H2 / CO in the corn cob gaseous products slows down after 800℃. Therefore, considering the reaction energy consumption, gaseous product yield, and composition, 800℃ was selected as the reaction condition for subsequent experiments.

[0099] Experimental conditions: Poplar wood and corn cob particle size 1-2 mm, biomass amount approximately 3 g, reaction temperature 700-900℃, nitrogen as carrier gas, flow rate 200 ml / min -1 .

[0100] 3) Effect of gasifying agent on product distribution

[0101] Figure 8 further examines the effect of gasifying agent dosage on the distribution of poplar products. As shown in Figure 8(a), the addition of the gasifying agent promotes the gasification reaction of poplar semi-coke, decreasing the yield of poplar semi-coke from ~11% to ~3-5%, while simultaneously increasing the yield of poplar gas from ~51% to ~63%. Increasing the gasifying agent to biomass addition ratio (S / B) from 0.6 to 1.4 has a relatively small effect on the gas yield and semi-coke yield. However, regarding the gas composition, Figure 8(b) shows that with the increase of S / B, the yield of H2 in biomass fuel gas gradually increases. When S / B is greater than 1, the yields of CO2 and CH4 tend to stabilize. This phenomenon should be attributed to the reforming reaction of CO2 and CH4 gases with water vapor. Furthermore, when S / B is greater than 1, the growth trend of H2 / CO slows down. Therefore, in subsequent experiments, this project plans to use S / B = 1.

[0102] Experimental conditions: Poplar wood was used as raw material with a particle size of 1-2 mm, and the amount of biomass used was approximately 3 g. The reaction temperature was 800℃, nitrogen was used as the carrier gas, and the flow rate was 200 ml / min. -1 The gasifying agent is water vapor, and the S / B (water vapor to biomass mass ratio) is 0, 0.6, 1, and 1.4.

[0103] 4) The effect of silicon carbide film pore size on product distribution

[0104] Table 2 shows the yield and retention rate of solid particles in poplar gasification fuel under different experimental conditions, and Figure 9 shows the filter paper image after sample filtration. Under membrane-free and gasifying agent-free conditions, the yield of solid particles in the fuel was approximately 0.23%. When the silicon carbide membrane used had a pore size of 0.1 μm, the yield decreased to 0.02%, with a corresponding retention rate of approximately 91%. To further improve the retention rate, a membrane with a smaller pore size may be required. On the other hand, since the solid particles in the fuel consist of two parts—biomass ash and coke—in-situ catalytic reforming can promote the in-situ gasification of coke and reduce the solid particle content in the fuel. Therefore, in addition to using a smaller pore size membrane, using a highly efficient catalyst to promote in-situ coke reforming may also be a more effective strategy, and further research will be conducted in the future.

[0105] Experimental conditions: Poplar wood was used as raw material with a particle size of 1-2 mm, and the amount of biomass used was approximately 3 g. The reaction temperature was 800℃, nitrogen was used as the carrier gas, and the flow rate was 200 ml / min. -1 The gasifying agent is water vapor, and the S / B (water vapor to biomass mass ratio) = 1. The silicon carbide membrane is 200 mm long, with an outer diameter of 35 mm, an inner diameter of 23 mm, and pore sizes of 50 μm, 10 μm, and 0.1 μm.

[0106] Table 2. Solid particle yield and particle retention rate in poplar gasification fuel under different experimental conditions.

[0107]

[0108]

[0109] Solid particle characterization (SEM)

[0110] Figure 10 shows the SEM images and particle size distribution of solid particles in the tar product obtained from poplar wood at 800℃. Compared with the solid particles obtained in Figure (a) without a gasifying agent and without a silicon carbide membrane, the particle size of the solid particles obtained in Figure (b) with a gasifying agent and without a silicon carbide membrane is significantly reduced, with the average particle size decreasing from ~0.43 μm to ~0.36 μm. This result indicates that water vapor has a reforming effect on tar and can inhibit the formation of carbon deposits from volatile tar. When a silicon carbide membrane with a pore size of 0.1 μm is used, the number of particles in the SEM image (c) of the solid particles in the tar product obtained from pyrolysis and gasification is significantly reduced, and the particle size of the solid particles is also significantly reduced to ~0.22 μm. This value is greater than that of the silicon carbide membrane pore size, which may be related to the secondary reaction of volatiles outside the membrane. Excessive polymerization of volatiles leads to an increase in particle size. Experimental conditions: Poplar wood was used as raw material with a particle size of 1-2 mm, and the amount of biomass used was approximately 3 g. The reaction temperature was 800℃, nitrogen was used as the carrier gas, and the flow rate was 200 ml / min. -1 The silicon carbide film is 200 mm long, 35 mm in outer diameter, 23 mm in inner diameter, and has a pore size of 0.1 μm.

[0111] Catalytic reforming experiment in membrane reactor

[0112] Corn cobs (1-2 mm in diameter) were selected as the biomass feedstock, with approximately 3 g of biomass used. The reaction pressure was 0.1 MPa, the reaction temperature was 800℃, and nitrogen (N2) was used as the carrier gas at a flow rate of 200 ml / min. -1 The gasifying agent was steam, with an S / B (steam to biomass mass ratio) of 1.0. The biomass gasification reforming tar catalyst was a monolithic nickel-based catalyst prepared using cyclic foamed silicon carbide (SiC) as a support (Figure 11), with an outer diameter of 65 mm, an inner diameter of 39 mm, and a height of 30 mm. Two catalyst pieces, weighing approximately 80 g in total, were used in a single test, packed on the outside of an 8 cm long membrane tube. The silicon carbide membrane had a pore size of 0.1 μm. The biomass gasification tar reforming membrane reactor is shown in Figure 11. Parallel experiments were conducted on the biomass gasification reforming process, with the reactor containing neither a membrane nor catalyst, nor a membrane and either a blank cyclic foamed silicon carbide or a monolithic nickel-based catalyst.

[0113] Before the reaction begins with the loading of the monolithic cyclic nickel-based catalyst, the catalyst needs to be reduced at 500°C for 2 hours in a reducing atmosphere consisting of H2 (20 vol.%) and N2 (80 vol.%). After reduction, the entire reaction system is purged with nitrogen, and the vaporization chamber and gasifier are preheated to 130°C and 800°C, respectively. Once the set temperatures are reached, the injection pump is turned on to allow water to enter the vaporization chamber, mix thoroughly with the carrier gas, and then introduce it into the reactor. The feed valve is then opened to allow biomass to enter the isothermal zone of the membrane reactor from the top. The reaction is allowed to proceed for 20 minutes to ensure complete biomass reaction. The volatiles produced in the reaction are condensed using a four-stage condenser. The coolant in the first and fourth stage cold traps is ice water, while the coolant in the second and third stage cold traps is liquid nitrogen. Non-condensable gases are collected in a gas bag and analyzed offline using gas chromatography-TCD (GC-TCD) to determine the composition and yield of the gaseous products. The products obtained in the cold traps are thoroughly washed with tetrahydrofuran (THF) and transferred to sample vials for subsequent product analysis.

[0114] Product analysis methods

[0115] The analysis of tar and solid particle content in the product was carried out in accordance with the national standard GB / T 40508-2021 "Determination of Tar and Dust Content in Biomass Gas", and the analysis procedure was the same as that in the gasification experiment.

[0116] Test Result Analysis:

[0117] 1) Properties of raw materials

[0118] Corn cob raw material represents agricultural raw material, and its industrial analysis and elemental analysis results are shown in Table 1 of the gasification experiment section.

[0119] 2) Effect of monolithic nickel-based catalysts on product distribution

[0120] Figure 12 shows the effects of three reactors on product distribution: no membrane and no catalyst (Blank), membrane and no catalyst (Blank-M), and membrane and monolithic nickel-based catalyst (15Ni5La / S1-SiC-M). Compared with the group without membrane and no catalyst, the group with membrane and no catalyst showed no significant change in tar content, but reduced syngas yield and hydrogen-to-carbon ratio (H2 / CO), decreased solid particle content in volatiles, and a rejection rate of 42.5%. The group with membrane and monolithic nickel-based catalyst showed a decrease in tar content to 2.0% and an increase in syngas yield to 58.1 mmol / g. corncob Furthermore, the H2 / CO ratio was increased, and the tar removal rate and solid particle retention rate reached 85.2% and 95.9%, respectively.

[0121] Experimental conditions: Corn cobs (particle size 1-2 mm) were used as biomass feedstock, with an amount of approximately 3 g. The reaction pressure was 0.1 MPa, the reaction temperature was 800℃, and nitrogen (N2) was used as the carrier gas at a flow rate of 200 ml / min. -1 The gasifying agent is steam, and the S / B (steam to biomass mass ratio) = 1.0. The biomass gasification reforming tar catalyst is a monolithic nickel-based catalyst (15Ni5La / S1-SiC) prepared using annular foamed silicon carbide (SiC) with an outer diameter of 65 mm, an inner diameter of 39 mm, and a height of 30 mm as a support. Two catalyst pieces were used in a single test, and the pore size of the silicon carbide membrane is 0.1 μm.

[0122] Based on the above tests, this patent also constructs a method for predicting the yield of half-coke in syngas production based on membrane pore size and biomass feedstock characteristics, which is calculated using the following formula:

[0123] Y=a*x1^2+b*x2^2+c*x1*x2+d*x1+e*x2+f;

[0124] Where x1 refers to the carbon content (%) in biomass, x2 refers to the membrane pore size (μm); Y is the semi-coke yield; a / b / c / d / e / f are parameters; the test data are used to construct training sample data and validation sample data, and the following prediction formula is obtained after modeling (Figure 13): Y=-0.0037*x1^2-0.0101*x2^2-0.0287*x1*x2+0.4366*x1+1.7512*x2+0.0198;

[0125] Based on data tested at S / B = 1 and 800℃, the comparison of calculated / predicted values ​​in some training and validation samples is as follows (Table 3):

[0126] Table 3

[0127]

[0128] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0129] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0130] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for biomass conversion to syngas based on membrane reaction, characterized in that, The process includes the following steps: A mixture of oxygen-containing feed gas, a gasifying agent, and biomass feed is continuously fed into a membrane reactor; on the feed side of the membrane reactor, a pyrolysis and gasification reaction of the biomass takes place, and after particulate impurities are removed by a filter membrane in the membrane reactor, the gasification products enter the permeate side of the filter membrane; the reaction residence time of the mixed feed is controlled by baffles on the feed side; a carrier gas is supplied to the permeate side to purge the gasification products, and after condensation and removal of liquid components, syngas mainly containing CO and H2 is obtained; a catalytic reforming catalyst layer is also provided on the permeate side of the filter membrane, and the gasification products are placed on the catalytic reforming catalyst layer. Catalytic reforming is performed; the membrane reactor is tubular, with the feed side inside the tube and a filter membrane on the tube wall. The filter membrane is made of silicon carbide with a pore size of 0.05-100 μm, a tube diameter of 1-10 cm, a thickness of 0.1-1 cm, and a length of 200-1000 mm. A swivel is provided inside the tube, with baffles distributed on the swivel. The baffles rotate 1-20 seconds every 30 seconds, and the rotation speed of the baffles is 10-500 r / min. The catalyst in the catalytic reforming catalyst layer is any one or more of Ca, Zn, Mg, Fe, K, and Ni-based catalysts.

2. The method for biomass conversion to syngas based on membrane reaction according to claim 1, characterized in that, The vaporizing agent is selected from any one or more of carbon dioxide, air, oxygen, and water vapor.

3. The method for biomass conversion to syngas based on membrane reaction according to claim 1, characterized in that, The membrane reactor operates at a temperature range of 400–1000℃; the biomass feedstock has a particle size of 0.1–5 mm, an ash content of 0.5–10%, and a carbon content of 35–55%; the weight ratio of the gasifying agent to the biomass feedstock is 0.5–2; the oxygen-containing feedstock gas is obtained by oxygen enrichment after separation treatment through an oxygen-permeable membrane; the residence time of the biomass feedstock in the reactor is 5–1200 s.

4. A device for biomass conversion to syngas based on membrane reaction, characterized in that, include: Oxygen-permeable membranes are used to separate oxygen from feed gas. A mixer used to mix oxygen and a vaporizing agent; A feeder is used to mix biomass feedstock with oxygen and a gasifying agent and then convey the mixture into the membrane channel of the pyrolysis gasification membrane reactor. The pyrolysis gasification membrane reactor is equipped with a porous tubular membrane, with the tube side connected to the feeder and the shell side connected to a condenser. The porous tubular membrane is made of ceramic, with a pore size of 0.05-100 μm, a tube diameter of 1-10 cm, a thickness of 0.1-1 cm, and a length of 200-1000 mm. A catalytic reforming catalyst layer is also provided on the permeate side of the tubular membrane. The catalyst in the catalytic reforming catalyst layer is any one or more of Ca, Zn, Mg, Fe, K, and Ni-based catalysts.

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