WO2020010675A1

WO2020010675A1 - Method and device for biomass pyrolysis and low temperature tar removal based on microwave hotspot

Info

Publication number: WO2020010675A1
Application number: PCT/CN2018/102928
Authority: WO
Inventors: 罗虎; 孔令照; 鲍利伟; 王昊; 孙予罕
Original assignee: 中国科学院上海高等研究院
Priority date: 2018-07-12
Filing date: 2018-08-29
Publication date: 2020-01-16
Also published as: CN108913177B; CN108913177A

Abstract

Provided are a method and device for biomass pyrolysis and low temperature tar removal based on a microwave hotspot, the method including the following steps: 1) under anaerobic conditions, pyrolyzing a first biomass to obtain a solid biochar bed; 2) under anaerobic conditions, subjecting the biochar bed layer obtained in step 1) to microwave heating to form a microwave hot spot region; and 3) under anaerobic conditions, adding a second biomass to form a biomass pyrolysis bed layer above the biochar bed layer, pyrolyzing same, and then in situ removing tar from the biochar bed layer across the microwave hot spot region. In the present invention, microwaves are is used as a heating means, and a high ash biochar generated by pyrolysis is used as a catalyst for tar removal and as a carrier for microwave hot spot generation to form a high temperature microwave hotspot region having both a microwave field and a catalytic performance on the surface of the biochar. After biomass pyrolysis tar generation, immediate in situ removal in the microwave hotspot region is realized, the overall reaction temperature is lowered, and the reaction time is shortened.

Description

Method and device for low-temperature removal of biomass pyrolysis tar based on microwave hot spots

Technical field

The invention relates to a method for removing pyrolysis tar, in particular to a method and a device for low-temperature removal of biomass pyrolysis tar based on microwave hot spots.

Background technique

Biomass pyrolysis tar is a kind of liquid mixture containing low molecular and high molecular oxygen compounds with complex composition. It mainly contains acid, alcohol, ester, ketone, and phenol, etc. It has acidity and its pH value is 2 ～ 4. In the meantime, the candle is strong and easily decomposed and unstable. The elements are mainly composed of C, H, O, N and S, which will not only cause waste of energy, but also seriously endanger process equipment. How to convert tar to syngas to the greatest extent in the reaction process is not only of great value to the biomass-to-syngas technology itself, but also has a positive effect on reducing greenhouse gas emissions and reducing the blockage of pipes and rot candles by tar.

At present, the biomass pyrolysis and gasification process often uses a two-stage or three-stage process, which separates the pyrolysis and gasification of the biomass, so that each reaction is performed under relatively independent conditions, thereby increasing the concentration of syngas. However, the multi-stage structure increases the complexity of the reaction, increases the operating cost, limits the processing capacity of the equipment, and it is difficult to achieve the purpose of efficient and low-cost utilization of biomass. At the same time, a large amount of tar will be generated in the pyrolysis and gasification process. The removal of tar mainly includes physical, thermal cracking and catalytic cracking. Among them, the physical method mainly based on adsorption and absorption is difficult to achieve the fundamental removal of tar; The thermal cracking temperature is generally higher than 1000 ° C, which increases the operating cost and equipment requirements. Catalytic reforming has attracted wide attention due to its faster reaction rate and higher removal efficiency. Common catalysts include catalysts such as Ni. Reaction temperature The range is 700-900 ° C. At the same time, the carbon deposition, deactivation and wear of the catalyst are involved in the reaction process. How to remove tar in the process of biomass pyrolysis at low temperature, high efficiency and low cost, and increase the content of syngas in the product of biomass pyrolysis and gasification is of great significance.

Microwave heating has the advantages of immediacy, integrity, selectivity and high efficiency. When microwave heating technology is applied to biomass pyrolysis, the content of synthesis gas in the product is higher than that of conventional pyrolysis. At the same time, biochar is a solid in the pyrolysis process. The product, which has a porous structure, contains more alkali metal carbonates in the ash, has the basic conditions for catalytic conversion and catalytic cracking of tar, and is a carbon catalyst with great application potential.

Aiming at the above-mentioned tar removal problem, combined with the characteristics of biochar and microwave heating, the hot spot effect during microwave heating is used to strengthen and promote the removal of tar, and a low-temperature removal of biomass pyrolysis tar based on microwave hot spots is provided. The method and device realize low-temperature and high-efficiency removal of tar in a reactor.

Summary of the invention

In view of the shortcomings of the prior art described above, the object of the present invention is to provide a method and a device for low-temperature removal of biomass pyrolysis tar based on microwave hotspots. Microwaves are used as heating means to pyrolyze biomass and remove tar. In addition, the two processes are coupled in a reactor, and the high-ash biochar generated by pyrolysis is used as a catalyst for tar removal and a carrier generated by microwave hot spots, and a high-temperature microwave hot spot area having both a microwave field and catalytic performance is formed on the surface of biochar . In the continuous reaction process, the biomass pyrolysis tar is removed in situ in the microwave hotspot immediately after it is generated, thereby reducing the overall reaction temperature and shortening the reaction time.

In order to achieve the above object and other related objects, a first aspect of the present invention provides a method for low-temperature removal of biomass pyrolysis tar based on microwave hot spots, including the following steps:

1) pyrolyzing the first biomass under anaerobic conditions to obtain a solid product that forms a biochar bed;

2) Under an anaerobic condition, microwave the biochar bed obtained in step 1) to form a microwave hot spot area;

3) Under anaerobic conditions, add a second biomass, form a biomass pyrolysis bed above the biochar bed and perform pyrolysis, and then remove the tar through the biochar bed in the microwave hotspot area.

In the continuous reaction process, the biomass pyrolysis tar is removed in situ in the microwave hot spot immediately after it is generated. The biomass pyrolysis process and the tar in-situ removal process are coupled in a reactor, that is, the tar in-situ removal is located below the biomass pyrolysis, and the pyrolysis solid product gradually accumulates into a bio-char bed for the in-situ removal of tar.

Preferably, it further includes at least one of the following technical features:

1) Biomass pyrolysis and tar removal in situ are performed in the same reactor;

2) The mass ratio of the second biomass to the solid product obtained from the pyrolysis of the first biomass is 1: 5 to 1:15, such as 1: 5 to 1: 6.67, 1: 6.67 to 1:10, or 1:10 to 1:15;

3) The ash content in the first biomass and the second biomass is 10-15% by weight, such as 10-13.24% by weight or 13.24-15% by weight. The ash includes inorganic salts and metal oxides, and is mainly derived from crops in high saline-alkali areas. , Such as straw, reeds and cotton stalks growing in high saline soil (Shanghai Chongming);

4) The metal content in the biochar bed is 10-30% by weight, such as 10-11% by weight, 11-23% by weight, 23-29% by weight, or 29-30% by weight, ensuring the dielectric loss factor of the metal salt and the carbon skeleton in the biochar The difference in the absorption of microwave energy causes the microwave energy to be non-uniform and induces the generation of microwave hotspots. High-ash biochar produced by pyrolysis is used as a catalyst for tar removal and as a carrier for microwave hotspots. Metal salts and metal oxides in ash and the like The difference in the dielectric loss factor of the biochar skeleton will cause uneven microwave energy absorption and distribution, and instantaneous high-temperature microwave hot spots will be generated in local areas of the biochar, thereby promoting reactions such as reforming, cracking, and water-gas shift.

More preferably, in feature 4), the metal includes one or more of Al, K, Ca, Mg, Fe, and Co.

Preferably, step 1), step 2) and step 3) obtain the anaerobic condition by passing inert gas.

Preferably, in step 2), the effective reaction temperature for microwave heating is 400-600 ° C, such as 400-450 ° C, 450-500 ° C, or 500-600 ° C.

The power range of the microwave heating equipment is 20 ～ 1500W, and the power can be adjusted steplessly according to the set temperature.

Preferably, the method further comprises: condensing and separating the product obtained in step 3), and performing gas chromatographic analysis on the obtained gas phase product, realizing the online analysis test of the gas composition, and adjusting the flow rate through a regulating valve before entering the gas chromatography. The condensation may adopt liquid nitrogen secondary condensation. The gas phase product obtained by condensation and separation can also be separated to obtain an inert gas, which is recycled to step 1) as a carrier gas to promote the reforming reaction of carbon dioxide with methane and water, and improve the yield of synthesis gas after various reactions.

According to a second aspect of the present invention, a device for low-temperature removal of biomass pyrolysis tar based on microwave hotspots includes a device body and a microwave heating component, and the microwave heating component is movably disposed around an outer wall of the device body. The position of the microwave heating component can be appropriately adjusted according to changes in the height and position of the biochar bed to achieve the concentrated use of microwave energy. The microwave heating power range is 20 ~ 1500W, and the power can be adjusted steplessly according to the set temperature.

The microwave heating component can be moved up and down along the outer wall of the device body. The position of the microwave hotspot area (microwave enhanced area) can be adjusted according to the reaction process, that is, the position of the microwave hotspot area can be made according to the height and position of the biochar bed. Appropriate adjustment to achieve the concentrated use of microwave energy.

Preferably, it further comprises a heat insulation layer, which is provided between the microwave heating component and the device body, and the heat insulation layer is provided around the outer wall of the device body.

Preferably, an infrared temperature measuring unit is provided in the thermal insulation layer, and a mode in which the infrared temperature measurement and the thermocouple temperature measurement are mutually corrected can be used to measure and feedback the microwave heating temperature.

Preferably, a biomass feed port is provided above the device body.

Preferably, it further comprises a condensing component and a gas chromatograph, and the device body communicates with the gas chromatograph via the condensing component.

Preferably, it further comprises an inert gas supply component, and the inert gas supply component is in communication with the device body.

More preferably, the inert gas supplying component includes a connected inert gas storage unit and a gas flow meter.

Compared with the prior art, the present invention has at least one of the following beneficial effects:

1) Utilize the hot spot effect in the microwave heating process to strengthen the transition area between pyrolysis and gasification reactions to achieve low-temperature and efficient removal of pyrolysis tar.

2) Using cheap biochar as a catalyst, it can participate in subsequent gasification reactions after eliminating tar, avoid problems such as catalyst deactivation and regeneration, and reduce the reaction cost.

3) Make full use of the differences in the dielectric properties of the metal elements in the high-ash biochar and the biochar framework to form microwave hotspots based on metal elements. The instantaneous high temperature provided by them can promote the tar molecules CC / CO to break and strengthen the tar removal. In addition to heat transfer and material transfer, the average reaction temperature is reduced and the energy efficiency of the reaction is improved.

4) Coupling the pyrolysis and tar removal reaction of biomass in a reactor, which is beneficial to the rapid in-situ removal of pyrolysis tar, which simplifies the reaction process and operation procedures, and avoids the heating / cooling during the traditional heating process. The disadvantages are slow process and excess energy.

5) The microwave-enhanced area is adjusted according to the reaction process, which can make full use of microwave energy to achieve directional supply of energy and integrally strengthened heating, thereby reducing energy loss and improving reaction efficiency.

6) The present invention uses cheap biochar as a catalyst and uses microwave enhanced heating to avoid problems such as catalyst deactivation and regeneration, increases the tar removal rate, reduces the reaction cost, and increases the efficiency of biomass pyrolysis and gasification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a device for low-temperature removal of biomass pyrolysis tar based on microwave hot spots of the present invention.

Reference signs:

A- biomass pyrolysis stage;

B- removable microwave assisted tar removal stage;

C-gasification stage.

FIG. 2 is a schematic diagram of a device for low-temperature removal of biomass pyrolysis tar based on microwave hot spots of the present invention.

Reference signs:

1- device body;

2-Microwave heating components;

3- insulation layer;

4- Infrared temperature measurement unit;

5-Biomass inlet;

6- Condensing components;

7-gas chromatograph;

8- inert gas storage unit;

9-gas flow meter.

detailed description

The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention may also be implemented or applied through different specific embodiments, and various details in this specification may also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

The conceptual diagram of the device for low-temperature biomass pyrolysis tar removal based on microwave hot spots of the present invention is shown in Figure 1. A is a biomass pyrolysis stage, B is a mobile microwave-assisted tar removal stage, and C is a gasification stage. In the present invention, microwave is used as a heating means, and the two processes of biomass pyrolysis and tar removal are coupled in one reactor, and the high-ash biochar generated by pyrolysis is used as a catalyst for tar removal and a carrier generated by microwave hot spots. A high-temperature microwave hotspot area with both a microwave field and catalytic properties is formed on the surface of biochar. In the continuous reaction process, the biomass pyrolysis tar is removed in situ in the microwave hotspot immediately after it is generated, thereby reducing the overall reaction temperature and shortening the reaction time.

A device for low-temperature removal of biomass pyrolysis tar based on microwave hotspots, as shown in FIG. 2, includes a device body 1, a microwave heating component 2, and a thermal insulation layer 3. The thermal insulation layer 3 is provided on the microwave heating component 2 and the device. Between the main bodies 1, the thermal insulation layer 3 is provided around the outer wall of the device body 1, and an infrared temperature measuring unit 4 is provided inside the thermal insulation layer 3; a biomass feed inlet 5 is provided above the device body 1; It includes a condensing part 6 and a gas chromatograph 7. The device body 1 is in communication with the gas chromatograph 7 via the condensing part 6. It also includes an inert gas supply part, which is in communication with the device body 1. The inert gas supply component includes a connected inert gas storage unit 8 and a gas flow meter 9.

Example 1

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tar based on microwave hot spots, as shown in Fig. 2, 60 g of straw (with an ash content of 10.15 wt%, Shanghai Chongming) was weighed. As the quartz reaction tube, nitrogen was used as Carrier gas with a flow rate of 100 mL / min. The straw was pyrolyzed at 500 ° C for 30 minutes to obtain 20 g of biochar, which contains 11 wt% of the metal, which is Al, K, Ca, Mg, and Fe. Biochar bed and get initial tar content. The biochar bed was heated to 500 ° C by microwave, and 2g of original straw was added to the top (the ash content was 10.15 wt%, Shanghai Chongming). The pyrolysis of the straw produced tar steam, which was purged with a carrier gas (N ₂ 100mL / min) Through the biochar bed, tar molecules undergo a removal reaction on the surface of the biochar (thermal cracking, catalytic reforming, and reforming reactions between gas molecules), and the reacted gases are fully condensed in a two-stage condenser of liquid nitrogen After that, the remaining tar product was obtained, and the tar removal rate was calculated from the original tar content after weighing. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, TDX-1 packed column, and column oven) were used. The temperature is 100 ° C), and the gas product is analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 2

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tar based on microwave hot spots, as shown in Fig. 2, 60 g of straw (with an ash content of 10.15 wt%, Shanghai Chongming) was weighed. As the quartz reaction tube, nitrogen was used as Carrier gas with a flow rate of 100 mL / min. The straw was pyrolyzed at 500 ° C for 30 minutes to obtain 20 g of biochar, which contains 11 wt% of the metal, which is Al, K, Ca, Mg, and Fe. Biochar bed and get initial tar content. The bed of biochar was heated to 600 ° C by microwave, and 4g of original straw (with an ash content of 10.15% by weight, Shanghai Chongming) was added to the top. The pyrolysis of the straw produced tar steam and passed through the biochar bed under a carrier gas sweep. Layer, tar molecules undergo a removal reaction (thermal cracking, catalytic reforming, and reforming reactions between gas molecules) on the surface of the biochar. The reacted gases are fully condensed in a liquid nitrogen two-stage condenser to obtain the remaining tar product. After weighting, the pyrolysis tar removal rate was calculated with the original tar content. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, TDX-1 packed column, and the oven temperature at 100 ° C) was used. The products were analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 3

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tar based on microwave hot spots, as shown in FIG. 2, 60g of reed straw (15.08 wt% ash content, Shanghai Chongming) was weighed. As the quartz reaction tube, nitrogen was used as Carrier gas with a flow rate of 100 mL / min. The reed straw was pyrolyzed at 500 ° C for 30 min to obtain 20 g of biochar, which contains 29 wt% of the metal, which is K, Ca, Mg, Fe and Co. Start the biochar bed and get the initial tar content. The biochar bed was heated to 400 ° C by microwave, and 1.3 raw reed straw was added to the top (the ash content was 15.08wt%, Shanghai Chongming). The reed pyrolysis produced tar steam, which was purged with a carrier gas (N ₂ 100mL / min) Through the biochar bed, tar molecules undergo a removal reaction on the surface of the biochar (thermal cracking, catalytic reforming, and reforming reactions between gas molecules), and the reacted gases are fully condensed in a two-stage condenser of liquid nitrogen After that, the remaining tar product was obtained, and the tar removal rate was calculated from the original tar content after weighing. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, TDX-1 packed column, and column oven) were used. The temperature is 100 ° C), and the gas product is analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 4

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tar based on microwave hot spots, as shown in FIG. 2, 60g of reed straw (15.08 wt% ash content, Shanghai Chongming) was weighed. As the quartz reaction tube, nitrogen was used as Carrier gas with a flow rate of 100 mL / min. The reed straw was pyrolyzed at 400 ° C for 30 minutes to obtain 20 g of biochar, which contains 29 wt% of the metal, which is K, Ca, Mg, Fe, and Co. Start the biochar bed and get the initial tar content. The bed of biochar was heated to 600 ° C with microwave, and 3g of original reed straw (15.08wt%, Shanghai Chongming) was added on top of it. Pyrolysis of the reed produced tar steam, which was purged with carrier gas (N ₂ 100mL / min) Through the biochar bed, tar molecules undergo a removal reaction on the surface of the biochar (thermal cracking, catalytic reforming, and reforming reactions between gas molecules), and the reacted gases are fully condensed in a two-stage condenser of liquid nitrogen After that, the remaining tar product was obtained, and the tar removal rate was calculated from the original tar content after weighing. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, TDX-1 packed column, and column oven) were used. The temperature is 100 ° C), and the gas product is analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 5

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tars based on microwave hot spots, as shown in FIG. 2, 60 g of cotton straw (ash content of 13.24 wt%, Shanghai Chongming) was weighed. As for the quartz reaction tube, nitrogen was used as Carrier gas with a flow rate of 100 mL / min. The cotton straw was pyrolyzed at 500 ° C for 30 min to obtain 20 g of biochar, which contains 23 wt% of the metal, which is Al, K, Ca, Mg, Fe, and Co. As the starting biochar bed, and get the starting tar content. The biochar bed was heated to 600 ° C by microwave, and 4g of original cotton straw (13.24% by weight, Shanghai Chongming) was added on top of it. The cotton straw was pyrolyzed to generate tar vapor, which was purged with carrier gas (N ₂ 100mL / min) Through the biochar bed, tar molecules undergo a removal reaction (thermal cracking, catalytic reforming, and reforming reactions between gas molecules) on the surface of the biochar. The reacted gas is fully contained in a two-stage condenser of liquid nitrogen. Residual tar product was obtained after condensation, and the tar removal rate was calculated from the original tar content after weighing. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as carrier gas, TDX-1 packed column, column The oven temperature is 100 ° C), and the gas products are analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 6

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tars based on microwave hot spots, as shown in FIG. 2, 60 g of cotton straw (ash content of 13.24 wt%, Shanghai Chongming) was weighed. In a quartz reaction tube, nitrogen was used as a load Gas, the flow rate is 100mL / min, and the cotton straw is pyrolyzed at 500 ° C for 30min to obtain 20g of biochar, which contains 23wt% of the metal, which is Al, K, Ca, Mg, Fe, and Co, as Start the biochar bed and get the initial tar content. The biochar bed was heated to 500 ° C by microwave, and 1.3g of original cotton straw (13.24% by weight, Shanghai Chongming) was added on top of it. The cotton straw was pyrolyzed to generate tar steam, which was purged with carrier gas (N ₂ 100mL / min) Through the biochar bed, tar molecules are removed on the surface of the biochar (thermal cracking, catalytic reforming, and reforming reactions between gas molecules), and the reacted gases are in a two-stage condenser of liquid nitrogen. After full condensation, the remaining tar product was obtained. After weighing, the tar removal rate was calculated from the original tar content. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, and TDX-1 packed column, The oven temperature was 100 ° C), and the gas product was analyzed on-line to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 7

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tar based on microwave hot spots, as shown in Fig. 2, 60 g of straw (with an ash content of 10.15 wt%, Shanghai Chongming) was weighed. In a quartz reaction tube, nitrogen was used as the carrier. Gas, the flow rate is 100mL / min, and the straw is pyrolyzed at 500 ° C for 30min to obtain 20g of biochar, which contains 11wt% of the metal, which is Al, K, Ca, Mg and Fe, as the starting point Biochar bed and get initial tar content. The biochar bed was heated to 450 ° C by microwave, and 2g of original straw was added to the top (the ash content was 10.15 wt%, Shanghai Chongming). The pyrolysis of the straw produced tar steam, which was purged with a carrier gas (N ₂ 100mL / min) Through the biochar bed, tar molecules undergo a removal reaction on the surface of the biochar (thermal cracking, catalytic reforming, and reforming reactions between gas molecules), and the reacted gases are fully condensed in a two-stage condenser of liquid nitrogen After that, the remaining tar product was obtained, and the tar removal rate was calculated from the original tar content after weighing. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, TDX-1 packed column, and column oven) were used. The temperature is 100 ° C), and the gas product is analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Example 8

Using the above-mentioned apparatus for low-temperature removal of biomass pyrolysis tars based on microwave hot spots, as shown in FIG. 2, 60 g of reed straw (15.08 wt% ash content, Shanghai Chongming) was weighed. In a quartz reaction tube, nitrogen was used as a load Gas, the flow rate is 100mL / min, and the reed straw is pyrolyzed at 500 ° C for 30min to obtain 20g of biochar, which contains 29wt% of the metal, which is K, Ca, Mg, Fe, and Co as the starting point Biochar bed and get initial tar content. The biochar bed was heated to 600 ° C by microwave, and 3g of original straw (with an ash content of 10.15% by weight, Shanghai Chongming) was added on top of it. Pyrolysis of the straw produced tar steam under a carrier gas purge (N ₂ 100mL / min) Through the biochar bed, tar molecules undergo a removal reaction on the surface of the biochar (thermal cracking, catalytic reforming, and reforming reactions between gas molecules), and the reacted gases are fully condensed in a two-stage condenser of liquid nitrogen After that, the remaining tar product was obtained, and the tar removal rate was calculated from the original tar content after weighing. At the same time, a gas chromatograph (Shimadzu 2014C, TCD detector, Ar as the carrier gas, TDX-1 packed column, and column oven) were used. The temperature is 100 ° C), and the gas product is analyzed online to obtain the volume content of hydrogen in the synthesis gas. The results are shown in Table 1.

Table 1 Example reaction results

The above is only a preferred embodiment of the present invention, and is not a limitation on the form and substance of the present invention. It should be noted that, for those skilled in the art, without departing from the method of the present invention, Several improvements and additions can be made, and these improvements and additions should also be regarded as the protection scope of the present invention. Those skilled in the art, without departing from the spirit and scope of the present invention, when they can make use of the technical content disclosed above to make some changes, modifications, and equivalent changes are equivalent to the present invention Equivalent embodiments; meanwhile, any equivalent changes, modifications and evolutions made to the above embodiments according to the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

A method for low-temperature removal of tar from biomass pyrolysis based on microwave hotspots, which comprises the following steps:

1) pyrolyzing the first biomass under anaerobic conditions to obtain a solid product that forms a biochar bed;

2) Under an anaerobic condition, microwave the biochar bed obtained in step 1) to form a microwave hot spot area;

3) Under anaerobic conditions, a second biomass is added, a biomass pyrolysis bed is formed above the biochar bed and pyrolyzed, and then the tar is removed in situ through the biochar bed in the microwave hotspot area.
The method according to claim 1, further comprising at least one of the following technical features:

1) Biomass pyrolysis and tar removal in situ are performed in the same reactor;

2) The mass ratio of the second biomass to the solid product obtained by pyrolysis of the first biomass is 1: 5 to 1:15;

3) The ash content in the first biomass and the second biomass is 10-15 wt%;

4) The metal content in the biochar bed is 10-30% by weight.
The method according to claim 2, wherein in the feature 4), the metal comprises one or more of Al, K, Ca, Mg, Fe, and Co.
The method according to claim 1, characterized in that, in steps 1), 2) and 3), an anaerobic condition is obtained by passing an inert gas.
The method according to claim 1, wherein in step 2), the effective reaction temperature of microwave heating is 400-600 ° C.
The method according to claim 1, further comprising: condensing and separating the product obtained in step 3), and performing gas chromatography analysis on the obtained gas phase product.
A device for low-temperature removal of biomass pyrolysis tar based on microwave hotspots is characterized in that it comprises a device body (1) and a microwave heating component (2), and the microwave heating component (2) is movably arranged around the device The outer wall of the body (1).
The device according to claim 7, further comprising a thermal insulation layer (3), which is provided between the microwave heating component (2) and the device body (1), and the thermal insulation layer (3) 3) Surround the outer wall of the device body (1).
The device according to claim 8, characterized in that an infrared temperature measuring unit (4) is provided in the heat-preserving layer (3).
The device according to claim 7, characterized in that a biomass feed port (5) is provided above the device body (1).
The device according to claim 7, further comprising a condensing component (6) and a gas chromatograph (7), the device body (1) passing through the condensing component (6) and the gas chromatograph ( 7) Connect.
The device according to claim 7, further comprising an inert gas supply member, said inert gas supply member being in communication with said device body (1).
The device according to claim 12, characterized in that said inert gas supplying component comprises a connected inert gas storage unit (8) and a gas flow meter (9).