CN111378462A - A method for producing syngas from biomass and system therefor - Google Patents

Abstract

The invention belongs to the field of biomass energy, and particularly relates to a method for preparing synthesis gas from biomass and a system adopted by the method, which comprises the following steps: (1) feeding the pretreated biomass raw material into a microwave pyrolysis reactor for reaction to obtain a pyrolysis volatile component and a pyrolysis solid-phase material; (2) feeding large-particle pyrolysis solid-phase materials in the pyrolysis solid-phase materials into a biological coke gasifier, and obtaining a biochar product and crude synthesis gas under the action of an activating agent; (3) and (3) feeding the pyrolysis volatile components, the small-particle pyrolysis solid-phase materials and the crude synthesis gas into a tar cracker, and performing tar removal treatment and reforming reaction of small hydrocarbon molecules under the action of working gas to obtain the target product biomass synthesis gas. The invention is convenient for controlling the reaction process and regulating and controlling the product, can obviously reduce the process cost of preparing the synthesis gas by the biomass, and has high quality of the target product.

Description

A method for producing syngas from biomass and system therefor

technical field

The invention belongs to the field of biomass energy, and in particular relates to a method for producing synthesis gas from biomass and a system used therefor.

Background technique

As an important chemical raw material, syngas has important application value in the synthesis of methanol, dimethyl ether, light olefins and fuel oil. At present, syngas mostly comes from petroleum refining and coal gasification processes, but fossil energy is not renewable and there are pollution problems of harmful gases such as sulfur and nitrogen in the process. Develop applications at scale. Biomass is a cheap and large amount of renewable energy, and the content of sulfur and nitrogen in biomass is generally lower than that of conventional fossil-based raw materials. Therefore, it is of great practical significance to explore the development of biomass-to-synthesis gas technology. However, in the actual development and application process, it is found that the high volatile content in biomass will lead to the production of a large amount of tar in the gasification, which seriously affects the purity and composition of the syngas. In response to the above problems, two main biomass gasification technology routes have been developed at present: one is the biomass direct steam technology route, which includes the direct gasification reaction of biomass and steam in a fixed bed or a fluidized bed. The biggest problem of this route is that combustion gas needs to be introduced in the gasification process, which will dilute the effective components of the gas product. There are also high-temperature steam (1000 ℃) instead of conventional low-temperature steam to obtain higher-quality syngas. However, the production of high-temperature steam requires special equipment and consumes additional energy, resulting in a high overall cost. The other is the biomass pyrolysis gasification technology route. The biggest advantage of this technology is that it is carried out under anoxic or anaerobic conditions, which can obtain high-quality syngas products, but the amount of tar produced is more than the direct water of biomass. The steam technology route limits the further application of this technology.

Aiming at the problem of excessive tar generation in the biomass pyrolysis process, Chinese Invention Patent 201910381117.1 discloses a biomass synthesis gas production method and device, which utilizes a hydraulic mechanical furnace exhaust gasifier to gasify biomass, and utilizes biomass The sensible heat of the syngas heats biomass drying and gasification. By capturing the tar in the syngas and using it for recirculation combustion, the tar content in the syngas is reduced, and the energy consumption in the biomass gasification process is reduced, but this method The use of lye to capture tar has the problem of waste liquid treatment and discharge, which is not conducive to large-scale application. Chinese invention patent 201910392371.1 discloses a biomass microwave catalytic pyrolysis method and its device. Biochar generated after biomass pyrolysis is used to remove tar from pyrolysis gas, and then enters into catalytic cracking to obtain biomass synthesis The biggest feature of this method is that the pyrolysis, tar removal, catalytic reforming and catalyst regeneration are coupled in the microwave integrated device, and the microwave power is reasonably adjusted according to the heat absorption and exothermic conditions of each reaction, which improves the energy utilization efficiency. The biochar in the method is only used for tar removal and catalyst regeneration, resulting in the consumption of a large amount of biochar, which seriously affects the high-quality utilization of biochar.

SUMMARY OF THE INVENTION

The present invention aims to overcome the deficiencies of the prior art and provide a biomass-to-synthesis gas method that is convenient for reaction process control and product regulation, can significantly reduce the cost of the biomass-to-synthesis gas process, and has high target product quality.

The present invention also provides a biomass-to-synthesis gas system matched with the above method.

In order to solve the above-mentioned technical problems, the present invention is achieved in this way:

A method for producing synthesis gas from biomass can be implemented according to the following steps:

(1) The pretreated biomass raw material is sent to a microwave pyrolysis reactor for reaction to obtain pyrolysis volatile components and pyrolysis solid phase materials;

(2) sending the large-particle pyrolysis solid phase material in the pyrolysis solid phase material obtained in step (1) into the biocoke gasifier, and under the action of the activator, the biochar product and crude synthesis gas are obtained;

(3) The pyrolysis volatile components and small particle pyrolysis solid phase materials obtained in step (1) and the crude synthesis gas obtained in step (2) are sent to the tar cracker, and under the action of the working gas, detar treatment and carbonization are carried out. The reforming reaction of small hydrogen molecules produces the target product biomass synthesis gas.

As a preferred solution, the pretreatment process in step (1) of the present invention: the pretreatment process in step (1): the dried biomass is heated to 120-220°C under the action of high-temperature airflow, and the holding time is 1 to 10 minutes, then cooled and pulverized to less than 5 mm, and then physically extruded under the condition of 10 to 20 MPa to obtain biomass raw materials; the reaction temperature of the microwave pyrolysis reactor is 300 to 800 ° C; the reaction time is 5 ~30 minutes; the reaction temperature of the microwave pyrolysis reactor is 600-900° C.; the reaction time is 5-20 minutes.

Further, in step (3) of the present invention, one or more combinations of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, potassium acetate, sodium acetate, sodium formate, potassium formate, etc. are introduced.

Further, in the step (3) of the present invention, the working gas is one or more mixtures of water vapor, carbon dioxide, carbon monoxide, and oxygen; the flow rate is controlled at 0.1-1 m ³ /h.

Further, the activator in step (2) of the present invention is formic acid, acetic acid, oxalic acid, acrylic acid, methacrylic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, citric acid, tartaric acid, malic acid , ascorbic acid, benzoic acid, terephthalic acid, mellitic acid, salicylic acid, caffeic acid or picric acid or a mixture of two or more.

Further, potassium carbonate is introduced into the gasification reaction in step (3) of the present invention; the mass ratio of the potassium carbonate to the working gas is 0.005-0.05:1.

Further, in the gasification reaction of step (2) of the present invention, the preheated gas generated by the pretreatment in step (1) is introduced; the flow rate is controlled at 0.5-2 m ³ /h; the difference between the preheated gas and the activator is The mass ratio is 0.1 to 1:1.

Further, in the step (2) of the present invention, the reaction temperature of the biocoke gasifier is 600-900°C; the reaction time is 10-30 minutes; the reaction temperature of the tar cracker in the step (3) is 800-1100°C °C; the reaction time is 5 to 10 minutes.

The system used in the above-mentioned biomass-to-synthesis gas method includes a biomass silo, a microwave pyrolysis reactor, a tar cracker, a biocoke gasifier and a gas-solid separator;

The discharge port of the biomass silo is communicated with the feed port of the microwave pyrolysis reactor; the feed port of the tar cracker is connected with the pyrolysis volatile components and the small particle pyrolysis solid phase of the microwave pyrolysis reactor. The material outlet is communicated; the feed inlet of the biological coke gasifier is communicated with the large particle pyrolysis solid-phase material outlet of the microwave pyrolysis reactor; the gas-phase material outlet of the tar cracker is communicated with the inlet of the gas-solid separator;

A working gas inlet is fixedly arranged in the upper region of the tar cracker;

An activator inlet is fixedly arranged in the middle area of the biocoke gasifier; at the lower part of the biocoke gasifier, an electric furnace grate I is laterally arranged at the discharge port of the granular biochar; in the electric furnace There is a biochar screw discharge mechanism on the castor I.

As a preferred solution, the microwave pyrolysis reactor of the present invention adopts a horizontal horizontal moving bed reactor with a material conveying screw mechanism inside; both the biological coke gasifier and the tar cracker adopt a longitudinal moving bed reactor.

Compared with the prior art, the present invention has the following characteristics:

1. According to the reaction characteristics and application characteristics of the pyrolysis solid phase materials of different sizes, the present invention uses the pyrolysis solid phase materials according to their sizes for classification and utilization, and uses the smaller size pyrolysis solid phase materials for the cracking and removal of tar, so that the Larger size pyrolysis solid phase materials are used for the preparation of biochar products, and the processes of pyrolysis, gasification and tar cracking are coupled through three interconnected reactors, realizing three reaction process control, product control and The continuous operation of the system has achieved the goal of co-production of biomass syngas and biochar products.

2. The present invention aims at the problems of rapid deactivation and poor use effect commonly existing in conventional biocoke removal from tar, and the working gas of the basic compound can be used to make up for the problem that the biocoke itself is weak due to its catalytic effect. The pore-enlarging and activating effect of biocoke improves the reactivity of biocoke, and ensures the acquisition of high-quality biomass synthesis gas products.

3. The present invention uses the generated high-temperature syngas for biomass preheating to reduce microwave heating energy consumption and activate biomass, and uses the acid preheated gas generated by biomass preheating for the activation process of biochar to reduce activation High-quality biochar was used as a microwave absorber and catalyst for microwave heating of biomass to improve the microwave energy utilization efficiency and reduce the tar generated during the pyrolysis process. The above process innovation can significantly reduce the process cost of biomass to syngas and improve the process economy.

Description of drawings

FIG. 1 is a schematic diagram of the biomass-to-synthesis gas system of the present invention.

In the figure: 1, biomass silo; 2, microwave pyrolysis reactor; 3, material conveying screw mechanism; 4, biocoke gasifier; 5, stirring paddle I; 6, biochar discharge screw mechanism; 7, electric Grate I; 8. Tar cracker; 9. Electric grate II; 10. Stirrer II; 11. Residue discharge screw mechanism; 12. Gas-solid separator.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention. The following non-limiting examples may enable those of ordinary skill in the art to more fully understand the present invention, but do not limit the present invention in any way. In the following examples and comparative examples, the raw materials used are all commercially available unless otherwise specified.

As shown in Figure 1, a method for producing synthesis gas from biomass is implemented as follows:

(1) The pretreated biomass raw material is sent to a microwave pyrolysis reactor for reaction to obtain pyrolysis volatile components and pyrolysis solid phase materials;

(2) sending the large-particle pyrolysis solid phase material in the pyrolysis solid phase material obtained in step (1) into the biocoke gasifier, and under the action of the activator, the biochar product and crude synthesis gas are obtained;

(3) The pyrolysis volatile components and small particle pyrolysis solid phase materials obtained in step (1) and the crude synthesis gas obtained in step (2) are sent to the tar cracker, and under the action of the working gas, detar treatment and carbonization are carried out. The reforming reaction of small hydrogen molecules produces the target product biomass synthesis gas.

The biomass raw material in step (1) of the present invention can be derived from any lignocellulose-containing material such as corn stover, rice husk, wheat straw, wood block, leaf or branch; the biomass pretreatment process includes preheating, Pulverization, mixing and molding; pretreatment process in step (1): pretreatment process in step (1): the dried biomass is heated to 120-220°C under the action of high-temperature airflow, and the holding time is 1 to 10 minutes, then cooled and pulverized to less than 5 mm, and then physically extruded under the condition of 10 to 20 MPa to obtain biomass raw materials; the reaction temperature of the microwave pyrolysis reactor is 300 to 800 ° C; the reaction time is 5 ~30 minutes; the reaction temperature of the microwave pyrolysis reactor is 600 ~ 900 ℃; the reaction time is 5 ~ 20 minutes; the maximum dimension of the raw material does not exceed 40mm, preferably 10 ~ 20mm; the high temperature air flow comes from the system The synthesis gas product in the biomass, the heat exchange method is non-contact indirect heat exchange; the microwave power density is 0.1×10 ⁵ to 1×10 ⁵ W/m ³ ; the pyrolysis product of biomass is pyrolysis volatile Component and pyrolysis solid phase material, wherein the pyrolysis solid phase material is biological semi-coke, in terms of mass percentage, the pyrolysis volatile components account for 50-75 wt%, and the biological semi-coke accounts for 25-50 wt%; The non-condensable gas content in the reactive component reaches more than 90%.

The activator in step (2) of the present invention is formic acid, acetic acid, oxalic acid, acrylic acid, methacrylic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, citric acid, tartaric acid, malic acid, ascorbic acid, One or more mixtures of benzoic acid, terephthalic acid, mellitic acid, salicylic acid, caffeic acid or picric acid can also be introduced into the preheated gas generated by biomass pretreatment to further strengthen the gas The pyrolysis and small molecular hydrocarbons carrying tar are converted into synthesis gas products, and the flow rate is controlled at 0.5-2 m ³ /h; the mass ratio of preheating gas to water vapor is preferably 0.1-1:1.

^The reaction temperature ^of the biocoke gasifier in step ( ² ) of the present invention is 600-900° C.; the reaction time is 10-30 minutes; The solid-phase material is biocoke with a larger particle size, and the particle size of the biocoke is greater than 5 mm; the gasification products of the biocoke are crude syngas and biochar, in terms of the mass percentage of the gasification products, the crude syngas components account for 50~ 80wt%, biochar is 20-50wt%; the non-condensable gas content in the crude syngas component reaches more than 99%.

In step (2) of the present invention, the biochar obtained from the biocoke gasification reactor is used in two parts, one part is powdered and small particle biochar used as a microwave absorbent to be reused in the microwave pyrolysis reaction process, and the other part is directly used as a biochar product ; the mass ratio of the biochar to biomass used in the microwave pyrolysis reaction process is 0.05-0.5:1; the specific surface area of the bio-char is 1000-2000 m ² /g; The biochar of the present invention has excellent surface properties, which can not only enhance the microwave absorption effect of the biomass system, but also the porous channel structure of the biochar can effectively remove the condensable components and tars in the pyrolysis volatiles produced by the pyrolysis process. Online cracking and removal can reduce the content of pyrolysis tar, which is beneficial to reduce the pressure of subsequent tar removal.

In the step (3) of the present invention, one or more combinations of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, potassium acetate, sodium acetate, sodium formate, potassium formate, etc. can be introduced; preferably, Potassium carbonate is introduced into the gasification reaction; the mass ratio of the potassium carbonate to the working gas is 0.005-0.05:1. The working gas is one or a mixture of two or more of water vapor, carbon dioxide, carbon monoxide, and oxygen; the flow rate is controlled at 0.1 to 1 m ³ /h; the reaction temperature of the tar cracker is 800 to 1100 ° C; the reaction time 5 to 10 minutes; microwave power density 0.5×10 ⁵ to 5×10 ⁵ W/m ³ . The small particle pyrolysis solid phase material is biocoke with smaller particle size, and the particle size of the biocoke is not more than 5mm. In the tar cracking process, the biocoke with smaller particle size can fully contact and react with the pyrolysis volatile components and the crude synthesis gas from the biocoke gasification reactor, especially after the working gas containing potassium carbonate is introduced, it can make up Due to the weak catalytic effect of biocoke itself, the reactivity of biocoke is improved through the pore-enlarging and activating effect of potassium carbonate on biocoke, which ensures the acquisition of high-quality biomass synthesis gas products; the product of the tar cracker is: Syngas and a small amount of carbon-containing residues, in terms of the mass percentage of the product, where the synthesis gas accounts for 90-95%, and the carbon-containing residues are 5-10wt%; the hydrogen/carbon monoxide ratio in the synthesis gas is between 1.0-2.0, and the carbon dioxide content less than 15%, other impurity gases no more than 0.5%, the tar content in the gas is less than 20mg/Nm ³ , and the syngas yield in the whole process is no less than 1.5Nm ³ /kg dry basis delimed biomass.

The system used in the above-mentioned biomass-to-synthesis gas method includes a biomass silo 1, a microwave pyrolysis reactor 2, a tar cracker 8, a biocoke gasifier 4 and a gas-solid separator 12;

The outlet of the biomass silo 1 is communicated with the inlet of the microwave pyrolysis reactor 2; the inlet of the tar cracker 8 is connected to the pyrolysis volatile components and small particles of the microwave pyrolysis reactor 2 The pyrolysis solid-phase material outlet is communicated; the feed inlet of the biocoke gasifier 4 is communicated with the large-particle pyrolysis solid-phase material outlet of the microwave pyrolysis reactor 2; the gas-phase material outlet of the tar cracker 8 is communicated with the gas-phase material outlet. The inlets of the solid separator 12 are communicated;

A working gas inlet is fixed in the upper region of the tar cracker 8;

An activator inlet is fixedly arranged in the middle area of the biocoke gasifier 4; at the lower part of the biocoke gasifier 4, an electric furnace grate I7 is arranged laterally at the discharge port of the granular biochar; There is a biochar screw discharge mechanism 6 on the electric grate I7.

The microwave pyrolysis reactor 2 of the present invention adopts a horizontal horizontal moving bed reactor with a material conveying screw mechanism 3 inside; the biological coke gasifier 4 and the tar cracker 8 both adopt a longitudinal moving bed reactor.

The microwave pyrolysis reactor of the invention is used for receiving biomass raw materials, and after the reaction, pyrolysis volatile components and pyrolysis solid phase materials are obtained; the biocoke gasifier is used for receiving large particle pyrolysis solid phase materials from the microwave pyrolysis reactor With the activator from the activator feed line, through the gas-solid countercurrent contact reaction, crude synthesis gas and biochar are obtained; the tar cracker is used to receive the pyrolysis volatile components, small particle pyrolysis solid phase from the microwave pyrolysis reactor Materials, crude syngas from biocoke gasifier and working gas from working gas pipeline, through gas-solid co-current contact reaction, gas-phase materials rich in biomass syngas and a small amount of carbon-containing residue are obtained; gas-solid separator is used to receive The gas phase material from the tar cracker is separated to obtain high-quality biomass syngas and carbonaceous residues.

The microwave pyrolysis reactor 2 of the present invention adopts a horizontal horizontal moving bed reactor, and is equipped with a segmented non-equidistant material conveying screw mechanism 3. The diameter of the screw blade is 1/2 to 2/3 of the inner diameter of the reactor, and the screw pitch is the same as the screw blade. The ratio of the diameters is 1:0.5~2, and the pitch is reduced in stages from the feeding end to the discharging section to ensure the stability of the material level of the bed; the material conveying screw mechanism 3 not only plays the role of pushing and conveying, but also has The functions of dispersing and mixing prevent material agglomeration, aggregation and blockage, and ensure the continuous and stable movement of materials. The spiral types include screw type, spiral belt type, vane type, etc.

The biological coke gasifier 4 and the tar cracker 8 of the present invention adopt a longitudinal moving bed reactor with a multi-stage stirring structure inside. The diameter of the stirring plate is 1/2 to 3/4 of the inner diameter of the reactor. The acute angle is 5 to 30°, the number of stirring stages is 2 to 5 (the number of vertical layers of stirring blades), the stirring blades of each stage are 180°, and the adjacent multi-stage stirring blades are 90° to each other. The structure plays the role of loosening, dispersing and mixing. The stirring types include paddle type, anchor type, turbine type, etc. The vertical stirring moving bed prevents material agglomeration, aggregation and material blocking, and ensures the continuous and stable movement of the material.

In the present invention, the bottom of the biocoke gasifier 4 and the top of the tar cracker 8 are respectively provided with an electric grate I7 and an electric grate II9, which are used to realize the screening of biochar/biocoke, and the electric grate I7 adopts horizontal rotation. The powdered biochar is discharged in the way of electric control of the rotation frequency. The residue discharge screw mechanism 11 arranged at the bottom of the tar cracker 8 discharges the residue from the residue discharge port. The microwave pyrolysis reactor 2, the biological coke gasifier 4 and the tar cracker 8 of the present invention are respectively provided with a certain number of microwave quartz windows on the walls of the reactors, each window corresponds to a microwave generator, and the power of a single microwave generator is 500~ 2000W, the specific number of windows is set according to the volume of the reactor, generally 2 to 10, to ensure that the power density in the reactor is 0.1×10 ⁵ to 5×10 ⁵ W/m ³ .

The gas-solid separator described in the present invention is based on one or more means of gravity sedimentation, centrifugal separation, filter screen separation, static electricity, adsorption, etc., but is not limited to the above methods, and the gas-solid separator can be specifically a cyclone One or more of separators, bag filters, electrostatic precipitators, adsorption separators.

As shown in Figure 1, the preheated biomass raw material of the present invention is sent from the biomass silo 1 to the microwave pyrolysis reactor 2 through the material conveying screw mechanism 3, and after the reaction, the pyrolysis volatile components and the pyrolysis solid phase are obtained. The material, of which the large-sized pyrolysis solid phase material enters the biocoke gasifier 4, and under the action of the stirring slurry I5 and the activator, a gasification reaction occurs to generate crude syngas and biochar, and the biochar acts on the electric grate I7. Next, a part of the large-sized biochar is discharged through the biochar discharge screw mechanism 6 to be used as a biochar product, and the other part of the powdery/small particle biochar is discharged back to the biomass microwave reactor 2 through the electric grate II9; pyrolysis Volatile components, small-sized pyrolysis solid phase materials and crude synthesis gas from biocoke gasifier 4 enter tar cracker 8, and under the action of stirring paddle II10 and working gas, tar cracking and heavy hydrocarbon small molecules occur. The overall reaction is carried out to generate syngas-rich gas-phase material and a small amount of carbon-containing residue. The gas-phase material enters the gas-solid separator 12 for gas-solid separation to obtain a high-quality biomass synthesis gas product, and the carbon-containing residue is discharged through the residue discharge screw 11.

Example 1

The air-dried biomass was heated to 180°C under the action of high-temperature airflow for 10 minutes, then cooled and pulverized to less than 5mm, and mixed uniformly according to the mass ratio of biomass to biochar of 1:0.1, and then under the condition of 15MPa Physical extrusion molding to obtain biomass raw materials with a maximum dimension of 10 mm, and the gas generated during the preheating process is preheated gas I.

The above biomass raw materials were sent into a microwave pyrolysis reactor, and under the conditions of a pyrolysis temperature of 800 °C, a pyrolysis time of 15 minutes, and a microwave power density of 0.5×10 ⁵ W/m ³ , gaseous pyrolysis volatiles and bio-chemicals were obtained. Semi-coke, in which pyrolysis volatile components account for 70%, and biological semi-coke accounts for 30%; the above-mentioned biocoke with a size of more than 5mm is sent to the biocoke gasifier, and the gasification temperature is 850 ° C and the reaction time is 20 minutes. , under the conditions of activator flow rate of 1m ³ /h (mass ratio of preheating gas and water vapor is 1:1), and microwave power density of 2×10 ⁵ W/m ³ , crude synthesis gas and biochar were obtained, of which crude synthesis gas was obtained. The gas component accounts for 70wt%, the biochar is 30wt%, and the biochar specific surface area is 1500m ² /g; the pyrolysis volatile components, the biocoke with a size of less than 5mm, and the crude syngas from the biocoke gasifier are sent into Tar cracker at 900°C; reaction time 10 minutes; microwave power density 2×10 ⁵ W/m ³ , working gas flow 0.5m ³ /h (mass ratio of potassium carbonate to water vapor 0.05:1) Under the action of the reaction, a gas-phase product rich in syngas is generated. The gas-phase product is separated from gas and solid to obtain a high-quality biomass syngas product. The biomass syngas concentration is 85.8%, the hydrogen/carbon monoxide ratio is 1.9, and the carbon dioxide content is 14%. The other impurity gas is 0.2%, the tar content in the gas is 10 mg/Nm ³ , and the synthesis gas yield is 1.6Nm ³ /kg dry basis delimed biomass.

It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention, and those of ordinary skill in the art should understand that the present invention can still be modified or It is equivalent to replacement to achieve the same technical effect; as long as the needs of use are met, they are all within the protection scope of the present invention.

Claims (10)

1. a method for producing synthesis gas from biomass, is characterized in that, is implemented as follows: (1) The pretreated biomass raw material is sent to a microwave pyrolysis reactor for reaction to obtain pyrolysis volatile components and pyrolysis solid phase materials; (2) sending the large-particle pyrolysis solid phase material in the pyrolysis solid phase material obtained in step (1) into the biocoke gasifier, and under the action of the activator, the biochar product and crude synthesis gas are obtained; (3) The pyrolysis volatile components and small particle pyrolysis solid phase materials obtained in step (1) and the crude synthesis gas obtained in step (2) are sent to the tar cracker, and under the action of the working gas, detar treatment and carbonization are carried out. The reforming reaction of small hydrogen molecules produces the target product biomass synthesis gas. 2 . The method for producing syngas from biomass according to claim 1 , wherein: the pretreatment process in the step (1): the pretreatment process in the step (1): the air-dried biomass is Under the action of high-temperature airflow, it is heated to 120-220 ° C, the holding time is 1-10 minutes, then cooled and pulverized to less than 5 mm, and then physically extruded under the condition of 10-20 MPa to obtain biomass raw materials; the microwave pyrolysis reaction The reaction temperature of the reactor is 300-800 DEG C; the reaction time is 5-30 minutes; the reaction temperature of the microwave pyrolysis reactor is 600-900 DEG C; and the reaction time is 5-20 minutes. 3. The method for producing synthesis gas from biomass according to claim 2, characterized in that: in the step (3), potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, potassium acetate, sodium acetate, One or more combinations of sodium formate, potassium formate, etc. 4 . The method for producing synthesis gas from biomass according to claim 3 , wherein in the step (3), the working gas is one or a mixture of two or more of water vapor, carbon dioxide, carbon monoxide, and oxygen; 5 . The flow rate is controlled at 0.1-1 m ³ /h. 5 . The method for producing synthesis gas from biomass according to claim 4 , wherein the activator in the step (2) is formic acid, acetic acid, oxalic acid, acrylic acid, methacrylic acid, succinic acid, and succinic anhydride. 6 . , glutaric acid, adipic acid, citric acid, tartaric acid, malic acid, ascorbic acid, benzoic acid, terephthalic acid, mellitic acid, salicylic acid, caffeic acid or a mixture of two or more of them . 6 . The method for producing synthesis gas from biomass according to claim 5 , wherein potassium carbonate is introduced into the gasification reaction in the step (3); the mass ratio of the potassium carbonate to the working gas is 0.005 to 0.05. 7 . :1. 7 . The method for producing synthesis gas from biomass according to claim 6 , wherein the preheated gas generated by the pretreatment in step (1) is introduced into the gasification reaction in the step (2); the flow rate is controlled at 0.5～2m ³ /h; the mass ratio of the preheating gas to the activator is 0.1～1:1. 8 . The method for producing synthesis gas from biomass according to claim 7 , wherein the reaction temperature of the biocoke gasifier in the step (2) is 600-900° C.; the reaction time is 10-30 minutes; In the above step (3), the reaction temperature of the tar cracker is 800-1100°C; the reaction time is 5-10 minutes. 9. The system used in the method for producing synthesis gas from biomass according to any one of claims 1 to 8, characterized in that it comprises a biomass silo (1), a microwave pyrolysis reactor (2), and a tar cracker (8) , biological coke gasifier (4) and gas-solid separator (12); The outlet of the biomass silo (1) is communicated with the inlet of the microwave pyrolysis reactor (2); the inlet of the tar cracker (8) is connected with the heat of the microwave pyrolysis reactor (2). The de-volatile components and the small-particle pyrolysis solid-phase material outlet are communicated; the feed inlet of the biocoke gasifier (4) is communicated with the large-particle pyrolysis solid-phase material outlet of the microwave pyrolysis reactor (2); The gas-phase material outlet of the tar cracker (8) communicates with the inlet of the gas-solid separator (12); A working gas inlet is fixedly arranged in the upper area of the tar cracker (8); An activator inlet is fixedly arranged in the middle area of the biocoke gasifier (4); at the lower part of the biocoke gasifier (4), an electric furnace grate I is laterally arranged at the discharge port of the granular biochar (7); a biochar screw discharge mechanism (6) is provided on the electric grate I (7). 10. The system used in the method for producing synthesis gas from biomass according to claim 9, characterized in that: the microwave pyrolysis reactor (2) adopts a horizontal horizontal moving bed reactor, and is equipped with a material conveying screw mechanism (3). ); the biological coke gasifier (4) and the tar cracker (8) both use longitudinal moving bed reactors.

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