A method and device for self-powered thermal biomass conditioning pyrolysis co-production of high-value liquid and solid products

Abstract

The application provides a self-powered heat type biomass conditioning pyrolysis method and device for co-production of high-value liquid and solid products, and belongs to the technical field of biomass processing. The device provided by the application mainly comprises a feeding module, a pyrolysis module, a condensation module and a self-powered heating module. Based on in-situ conditioning pyrolysis integration, the pyrolysis path is in-situ regulated by adding a trace amount of potassium metal salt, the self-powered electric heating molten salt precise temperature control technology is used, the conditioning pyrolysis process is uniform, stable and controllable, and the oil and carbon products can be simultaneously upgraded. After the reaction, the potassium salt catalyst does not need to be separated and can be directly used as high-value field-return biochar or subsequent activated raw material, and the quality of the biochar is further improved. The device has simple structure and precise temperature control, the oil and carbon products prepared have high quality, the catalyst does not need to be separated, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of biomass treatment technology, and relates to the high-value treatment of biomass pyrolysis, specifically to a method and apparatus for co-producing high-value liquid and solid products by self-powered heating biomass conditioning pyrolysis. Background Technology

[0002] Biomass pyrolysis is a thermal conversion technology that transforms biomass macromolecules into three-phase products—pyrolysis oil, pyrolysis gas, and pyrolysis char—through thermochemical decomposition under anaerobic or hypoxic conditions. It is simple to implement, has low operating costs, and is widely applicable, making it one of the most promising technologies for the high-value utilization of biomass. However, the three-phase products obtained from direct pyrolysis are often of low quality, requiring separate upgrading routes for solid and liquid products (bio-oil and biochar), making the process complex and challenging. Research has found that introducing specific catalysts during catalytic pyrolysis can significantly improve product quality and regulate product distribution, but technical bottlenecks remain, such as difficulties in catalyst separation and precise temperature control.

[0003] Among these factors, pyrolysis temperature is particularly important, serving as a key factor influencing the pyrolysis pathway and product distribution. Especially for catalytic pyrolysis, which demands higher temperature control, precise temperature control at each stage has a decisive impact on the properties of the final product. Therefore, achieving precise control of pyrolysis temperature to finely regulate the quality and yield distribution of pyrolysis products, ensuring their stability and consistency, is extremely important for subsequent quality improvement, high-value utilization, and industrial applications.

[0004] Traditional heating methods, such as flue gas heating, utilize the hot flue gas generated by fuel combustion to transfer heat through indirect or direct heat conduction and convection. While these methods offer advantages such as mature technology and low heating costs, they suffer from poor temperature uniformity of the hot flue gas at the front end, high thermal inertia, and slow response speed of the heating system, making it difficult to achieve rapid and precise temperature regulation. Emerging microwave heating technology, while offering advantages such as fast heating speed and high uniformity, still suffers from drawbacks such as high sensitivity to raw material properties, difficulty in controlling temperature uniformity, and low temperature measurement accuracy. This is particularly true for pyrolysis processes involving thermochemical reactions, where the microwave absorption properties of intermediate products constantly change with increasing carbonization, further exacerbating the difficulty of precise temperature control. Consequently, pyrolysis products are often primarily utilized as low-value energy sources such as coke and fuel gas, making it difficult to cover the high electricity costs.

[0005] Existing technology CN116855267A discloses a sustainable self-powered biomass pyrolysis co-production system, which includes a biomass pyrolysis oil recovery and utilization system, a pyrolysis gas circulation energy supply system, and a biomass pyrolysis co-production system. However, this technology cannot achieve stable and precise control of the catalytic pyrolysis process. Existing technology CN115505409A discloses a biomass pyrolysis self-regulating device and process for preparing high-quality bio-oil and co-producing biochar, including an integrated biomass pyrolysis self-regulating device, a first condenser, a second condenser, a biomass oil collection tank, an induced draft fan, and a gas combustion chamber. This device employs a unique layered pyrolysis bed within the pyrolysis chamber, using the heat generated by the combustion of non-condensable gases produced during pyrolysis to provide the heat required for pyrolysis and control the pyrolysis temperature, thus achieving directional pyrolysis. However, this technology cannot overcome the difficulty of catalyst separation. There is an urgent need for innovative research and development of new technologies to meet the precise temperature control requirements of the biomass catalytic pyrolysis process, overcome the industrialization drawbacks of catalyst separation difficulties, and promote the high-value utilization of biomass pyrolysis. Summary of the Invention

[0006] This invention addresses the difficulties in precise temperature control and catalyst separation during biomass catalytic pyrolysis in existing technologies by providing a method and apparatus for co-producing high-value liquid and solid products through self-powered heating biomass conditioning pyrolysis. The apparatus mainly includes a feeding module, a pyrolysis module, a condensation module, and a self-powered heating module. Based on in-situ integrated conditioning pyrolysis, the pyrolysis path is controlled in situ by adding trace amounts of potassium metal salt. Utilizing self-powered heating molten salt for precise temperature control, the conditioning pyrolysis process is uniform, stable, and controllable, achieving synergistic upgrading of oil and char products. Its purpose is to overcome the inherent defects of traditional biomass catalytic pyrolysis technologies, such as difficulties in catalyst separation and poor precise temperature control, thereby promoting the high-value utilization of biomass pyrolysis.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a preparation device for high-value liquid and solid products by biomass conditioning pyrolysis with self-powered heating, including a feeding module, a pyrolysis module, a condensation module, and a self-powered heating module.

[0009] The feeding module consists of air compressor A, air compressor B, and a pneumatic feeding device. The pneumatic feeding device includes a tank, a fluidizing air inlet, a conveying air inlet, a feed port, and a discharge port. The pyrolysis module consists of a pyrolysis reactor, a catalyst storage tank, and a biochar storage tank. The pyrolysis reactor includes a raw material inlet, a catalyst inlet, a gas outlet, a pyrolysis oil and gas outlet, a pyrolysis biochar outlet, a stirrer, a molten salt heating layer, and a reactor body. The condensation module consists of a condenser, a bio-oil aging tank, an oil-water separator, a light bio-oil storage tank, and a heavy bio-oil storage tank. The condenser includes a pyrolysis oil and gas inlet, a liquid outlet, a gas outlet, and a condenser body. The bio-oil aging tank includes a liquid inlet, a light liquid outlet, a heavy bio-oil outlet, and a tank body. The oil-water separator includes a light liquid inlet, a light bio-oil outlet, a heavy bio-oil outlet, and a separator body. The self-powered heating module includes a pyrolysis gas storage tank, an internal combustion generator set, and a molten salt storage tank.

[0010] The fluidizing air inlet of the pneumatic feeding device is connected to air compressor A, and the conveying air inlet is connected to air compressor B; the pyrolysis reactor is heated by molten salt, the raw material inlet is connected to the outlet of the pneumatic feeding device, the catalyst inlet is connected to the outlet of the catalyst storage silo, the pyrolysis oil and gas outlet is connected to the condenser inlet, and the pyrolysis char outlet is connected to the biochar storage silo inlet.

[0011] The condenser gas outlet is connected to the pyrolysis gas storage tank, and the liquid outlet is connected to the liquid inlet of the bio-oil aging tank; the light liquid outlet of the bio-oil aging tank is connected to the light liquid inlet of the oil-water separator, and the heavy bio-oil outlet is connected to the heavy bio-oil storage tank; the light bio-oil outlet of the oil-water separator is connected to the light bio-oil storage tank, and the heavy bio-oil outlet is connected to the heavy bio-oil storage tank.

[0012] The pyrolysis gas storage tank is connected to the internal combustion generator set to supply it with gaseous fuel; the electrical energy generated by the internal combustion generator set heats the molten salt storage tank through an electric heater, and any insufficient electricity is input from the external power grid.

[0013] On the other hand, the present invention provides a method for preparing high-value liquid and solid products by self-powered heating biomass conditioning pyrolysis, based on the above-mentioned preparation apparatus, comprising the following steps:

[0014] (1) Feeding process: Biomass raw material particles are added to the pneumatic feeding device through the feeding port; after feeding is completed, the fluidizing air inlet and outlet of the pneumatic feeding device are opened, and the conveying air inlet and feeding port are closed; the raw material inlet and air outlet of the pyrolysis reactor are opened, and the catalyst inlet, pyrolysis oil and gas outlet and pyrolysis carbon outlet are closed; the raw material particles inside the fluidized pneumatic feeding device of air compressor A are opened, and then the conveying air inlet of air compressor B and the pneumatic feeding device are opened to send the fluidized raw material particles into the pyrolysis reactor;

[0015] (2) Reaction process: Open the catalyst inlet of the pyrolysis reactor and input the catalyst (the catalyst ratio is 0.1-2 wt.% of the raw material, and the catalyst includes, but is not limited to, potassium salts such as potassium phosphate, potassium carbonate, and potassium acetate); then, open the oil and gas outlet of the pyrolysis reactor and close the pyrolysis raw material inlet, catalyst inlet, pyrolysis carbon outlet, and gas outlet; start the stirrer until the reaction is completed, and perform conditioning pyrolysis of the biomass in the pyrolysis reactor under an oxygen-free or inert atmosphere by constant-temperature molten salt heating, with a pyrolysis temperature of 400-700 °C. o C, time 30-120 min; after the reaction is completed, open the pyrolysis char outlet of the pyrolysis reactor and store the biochar generated by pyrolysis into the biochar storage silo.

[0016] (3) Condensation process: The hot oil-gas mixture generated by the pyrolysis reactor is condensed and separated by a condenser. The pyrolysis gas obtained by cooling enters the pyrolysis gas storage tank for later use. The bio-oil obtained by condensation enters the bio-oil aging tank for natural aging and stratification. The heavy components at the bottom are precipitated and enter the heavy bio-oil storage tank. The crude light bio-oil components at the top enter the oil-water separator for secondary separation. The small amount of heavy components separated also enters the heavy bio-oil storage tank. The refined light bio-oil obtained by separation enters the light bio-oil storage tank.

[0017] (4) Heating process: The pyrolysis gas stored in the pyrolysis gas storage tank enters the internal combustion generator set. The electrical energy generated by combustion heats the molten salt storage tank through the electric heater, providing the heat required for the pyrolysis reactor. The insufficient electricity is provided by the external power grid.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) This invention innovatively proposes a new approach of in-situ conditioning and conditioning integration. By adding trace amounts of potassium metal salt, the pyrolysis pathway is controlled in-situ. It has high low-temperature activity and good catalytic cracking performance, which can significantly increase the content of effective small molecule components in light bio-oil, improve the porosity and yield of pyrolysis biochar, and achieve simultaneous quality improvement of oil and char products. In addition, the biochar after reaction does not need to be separated from the potassium salt catalyst and can be directly used as biochar for returning to the field (at this time, the potassium salt is a nutrient element), or further activated to produce activated carbon (the in-situ loaded potassium salt can further improve the activation performance).

[0020] (2) This invention proposes a new technology for precise temperature control of self-powered electrothermal molten salt. The generated pyrolysis gas enters the internal combustion generator set and is converted into electrical energy. The temperature of the molten salt heat transfer medium is precisely controlled by electric heating. The precise temperature control of the external heat source enables fine regulation of the quality and yield distribution of pyrolysis products. The dynamic stirrer in the reactor is coupled to ensure the stability and consistency of the pyrolysis products. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the preparation apparatus of the present invention; in the figure: 1, pneumatic feeding device; 2, pyrolysis reactor; 3, catalyst storage tank; 4, condenser; 5, bio-oil aging tank; 6, oil-water separator; 7, light bio-oil storage tank; 8, pyrolysis gas storage tank; 9, internal combustion generator set; 10, molten salt storage tank; 11, biochar storage tank; 12, heavy bio-oil storage tank; 13, air compressor A; 14, air compressor B.

[0022] Figure 2 This is a schematic diagram of the pneumatic feeding device of the present invention; in the figure: 1-1, fluidizing air inlet; 1-2, conveying air inlet; 1-3, feeding port; 1-4, discharging port; 1-5, tank body.

[0023] Figure 3 This is a schematic diagram of the pyrolysis reactor of the present invention; in the figure: 2-1, raw material inlet; 2-2, catalyst inlet; 2-3, gas outlet; 2-4, pyrolysis oil and gas outlet; 2-5, pyrolysis carbon outlet; 2-6, stirrer; 2-7, molten salt heating layer; 2-8, reactor body.

[0024] Figure 4 This is a schematic diagram of the condenser of the present invention; in the figure: 4-1, pyrolysis oil and gas inlet; 4-2, liquid outlet; 4-3, gas outlet; 4-4, condenser body.

[0025] Figure 5 This is a schematic diagram of the structure of the bio-oil aging tank of the present invention; in the figure: 5-1, liquid inlet; 5-2, light liquid outlet; 5-3, heavy bio-oil outlet; 5-4, tank body.

[0026] Figure 6 This is a schematic diagram of the oil-water separator of the present invention; in the figure: 6-1, light liquid inlet; 6-2, light bio-oil outlet; 6-3, heavy bio-oil outlet; 6-4, separator body. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0028] Example 1: A self-powered heating biomass conditioning pyrolysis co-production device and method for high-value liquid and solid products

[0029] Figure 1 A device for co-producing high-value liquid and solid products through biomass conditioning pyrolysis with self-powered heating was demonstrated.

[0030] It includes a feeding module, a pyrolysis module, a condensation module, and a self-powered heating module. The feeding module includes air compressor A (13), air compressor B (14), and a pneumatic feeding device (1). The fluidizing air inlet (1-1) of the pneumatic feeding device is connected to air compressor A (13), and the conveying air inlet (1-2) is connected to air compressor B (14); the feed port (1-3) is used to add bio-oil raw material particles, and the typical biomass raw material is lignocellulosic agricultural and forestry waste. The discharge port (1-4) is connected to the raw material inlet (2-1) of the pyrolysis reactor and is used to transport the biomass raw material to the pyrolysis reactor (2).

[0031] The pyrolysis module includes a pyrolysis reactor (2), a catalyst storage tank (3), and a biochar storage tank (11). The pyrolysis reactor (2) is equipped with a molten salt heating layer (2-7) on the outside and a stirrer (2-6) inside, which is heated by constant temperature molten salt heat. The catalyst inlet (2-2) is connected to the outlet of the catalyst storage tank (3), the pyrolysis oil and gas outlet (2-4) is connected to the condenser inlet (4-1), and the pyrolysis carbon outlet (2-5) is connected to the inlet of the biochar storage tank (11).

[0032] The condensation module includes a condenser (4), a bio-oil aging tank (5), an oil-water separator (6), a light bio-oil storage tank (7), and a heavy bio-oil storage silo (12). The gas outlet (4-3) of the condenser is connected to the pyrolysis gas storage tank (8), and the liquid outlet (4-2) is connected to the liquid inlet (5-1) of the bio-oil aging tank; the light liquid outlet (5-2) of the bio-oil aging tank is connected to the light liquid inlet (6-1) of the oil-water separator, and the heavy bio-oil outlet (5-3) is connected to the heavy bio-oil storage silo (12); the light bio-oil outlet (6-2) of the oil-water separator is connected to the light bio-oil storage tank (7), and the heavy bio-oil outlet (6-3) is connected to the heavy bio-oil storage silo (12).

[0033] The self-powered heating module includes a pyrolysis gas storage tank (8), an internal combustion generator set (9), and a molten salt storage tank (10). The pyrolysis gas storage tank (8) is connected to the internal combustion generator set (9) to supply it with gaseous fuel; the electrical energy generated by the internal combustion generator set (9) heats the molten salt storage tank (10) through an electric heater, and any insufficient electrical energy is input from the external power grid.

[0034] A method for producing controllable high specific surface area narrow mesoporous activated carbon based on thermal oxidation using the above-mentioned apparatus includes the following specific steps:

[0035] Feeding process: Biomass raw material particles are added to the pneumatic feeding device (1) through the feeding port (1-3); after feeding is completed, the fluidizing air inlet (1-1) and the discharge port (1-4) of the pneumatic feeding device are opened, and the conveying air inlet (1-2) and the feeding port (1-3) are closed; the raw material inlet feeding port (2-1) and the air outlet (2-3) of the pyrolysis reactor are opened, and the catalyst inlet (2-2), the pyrolysis oil and gas outlet (2-4) and the pyrolysis carbon outlet (2-5) are closed; the raw material particles inside the fluidized pneumatic feeding device of the air compressor A (13) are opened, and then the air compressor B (14) and the conveying air inlet (1-2) of the pneumatic feeding device are opened to send the fluidized raw material particles into the pyrolysis reactor (2).

[0036] Reaction process: Open the catalyst inlet (2-2) of the pyrolysis reactor and input the catalyst from the catalyst storage tank (3); then, open the oil and gas outlet (2-4) of the pyrolysis reactor, and close the pyrolysis feedstock inlet (2-1), catalyst inlet (2-2), gas outlet (2-3) and pyrolysis carbon outlet (2-5); start the stirrer (2-6) until the reaction is completed, and condition the biomass in the pyrolysis reactor (2) under an anaerobic or inert atmosphere by constant temperature molten salt heating, with a pyrolysis temperature of 400-700 °C. o C, time 30-120 min; after the reaction is completed, open the pyrolysis char outlet (2-5) of the pyrolysis reactor and store the biochar generated by pyrolysis into the biochar storage bin (11).

[0037] Condensation process: The hot oil-gas mixture generated by the pyrolysis reactor (2) is condensed and separated by the condenser (4). The pyrolysis gas obtained by cooling enters the pyrolysis gas storage tank (8) for later use. The bio-oil obtained by condensation enters the bio-oil aging tank (5) for natural aging and stratification. The heavy components at the bottom enter the heavy bio-oil storage tank (12), and the crude light bio-oil components at the top enter the oil-water separator (6) for secondary separation. The small amount of heavy components separated also enters the heavy bio-oil storage tank (12), and the refined light bio-oil obtained by separation enters the light bio-oil storage tank (7).

[0038] Heating process: The pyrolysis gas stored in the pyrolysis gas storage tank (8) enters the internal combustion generator set (9). The electrical energy generated by combustion heats the molten salt storage tank (10) through the electric heater, providing the constant temperature heat required by the pyrolysis reactor (2). The insufficient electricity is provided by the external power grid.

[0039] The light bio-oil stored in the light bio-oil storage tank (7) has significantly higher content of effective small molecular components such as carboxyl groups and more uniform and stable content of each component compared to ordinary pyrolysis products. It can be used directly as agricultural foliar fertilizer or green pesticide, which can significantly increase crop yield and reduce the amount of pesticides and fertilizers used. Its commercial name is "wood vinegar". The heavy bio-oil stored in the heavy bio-oil storage tank (12) can replace coal tar as a raw material for daily chemical products. The biochar stored in the biochar storage silo (11) has significantly higher porosity and yield compared to ordinary pyrolysis products. It is also rich in trace elements such as K and P and can be used directly as a high-quality green carbon-based fertilizer.

[0040] Example 2: A method for preparing controllable high specific surface area narrow mesoporous activated carbon based on thermal oxidation

[0041] Based on the apparatus and method of Example 1, if the pyrolysis raw material is a biomass raw material rich in silicon, such as rice husk or wheat bran:

[0042] The light bio-oil stored in the light bio-oil storage tank (7) is conditioned and pyrolyzed and obtained as a foliar fertilizer or green pesticide. When used directly, it is called "rice husk vinegar". The biochar stored in the biochar storage tank (11) is conditioned and pyrolyzed and obtained as a foliar fertilizer or green pesticide. In addition to the above advantages, it is rich in silicon and is especially beneficial for the planting of staple crops such as rice and wheat. It is called "silicon carbon fertilizer".

[0043] Example 3: A method for preparing controllable high specific surface area narrow mesoporous activated carbon based on thermal oxidation

[0044] Based on the apparatus and method of Example 1, if the biochar obtained from pyrolysis is subsequently used for further activation to prepare active materials:

[0045] The biochar obtained from conditioning and pyrolysis stored in the biochar storage silo (11) has significantly improved porosity and yield compared to ordinary pyrolysis char. Moreover, the K catalyst that is retained does not need to be separated, which can further improve the activation effect. It is rich in trace elements such as K and P, and the biomass-based activated carbon produced has higher porosity and requires less activator.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A self-powered thermo-biomass conditioning pyrolysis cogeneration of high value liquid and solid products preparation device, characterized in that, The utility model relates to a pyrolysis system of biomass, including: feed module, pyrolysis module, condensation module, self-powered heat module; The feed module includes air compressor A (13), air compressor B (14) and pneumatic feeding device (1);The pyrolysis module includes pyrolysis reactor (2), catalyst storage (3) and biochar storage (11);The condensation module includes condenser (4), bio-oil aging tank (5), oil-water separator (6), light bio-oil storage tank (7) and heavy bio-oil storage (12);The self-powered heat module includes pyrolysis gas storage tank (8), internal combustion generator set (9) and molten salt storage tank (10); The pneumatic feeding device (1) is equipped with fluidization wind import (1-1), conveying wind import (1-2), feeding opening (1-3), discharge port (1-4) and tank body (1-5);The pyrolysis reactor (2) is equipped with raw material import (2-1), catalyst import (2-2), gas outlet (2-3), pyrolysis oil gas outlet (2-4), pyrolysis carbon outlet (2-5), agitator (2-6), molten salt heating layer (2-7) and reactor body (2-8);The condenser (4) is equipped with pyrolysis oil gas import (4-1), liquid outlet (4-2), gas outlet (4-3) and condenser body (4-4);The bio-oil aging tank (5) is equipped with liquid import (5-1), light liquid outlet (5-2), heavy bio-oil outlet (5-3) and pool body (5-4);The oil-water separator (6) is equipped with light liquid import (6-1), light bio-oil outlet (6-2), heavy bio-oil outlet (6-3) and separator body (6-4).

2. The preparation device according to claim 1, characterized in that The pneumatic feeding device fluidization wind import (1-1) is connected with air compressor A (13), the pneumatic feeding device conveying wind import (1-2) is connected with air compressor B (14), and the pneumatic feeding device discharge port (1-4) is connected with the pyrolysis reactor raw material import (2-1), to convey biomass raw material to the pyrolysis reactor (2).

3. The preparation device according to claim 1, characterized in that The pyrolysis reactor (2) is externally provided with molten salt heating layer (2-7) to heat in the form of constant-temperature molten salt heat;The catalyst import (2-2) is connected with the catalyst storage (3) outlet, the pyrolysis oil gas outlet (2-4) is connected with the pyrolysis oil gas import (4-1), and the pyrolysis carbon outlet (2-5) is connected with the biochar storage (11) inlet.

4. The preparation device according to claim 1, characterized in that The condenser gas outlet (4-3) is connected with the pyrolysis gas storage tank (8), and the liquid outlet (4-2) is connected with the bio-oil aging tank liquid import (5-1);The bio-oil aging tank light liquid outlet (5-2) is connected with the oil-water separator light liquid import (6-1), and the heavy bio-oil outlet (5-3) is connected with the heavy bio-oil storage (12);The oil-water separator light bio-oil outlet (6-2) is connected with the light bio-oil storage tank (7), and the heavy bio-oil outlet (6-3) is connected with the heavy bio-oil storage (12).

5. The preparation device according to claim 1, characterized in that The pyrolysis gas storage tank (8) is connected with the internal combustion generator set (9) and supplies gas fuel for the internal combustion generator set (9), and the electric energy generated by the internal combustion generator set (9) heats the molten salt storage tank (10) through the electric heater, and the insufficient part of electric quantity is input by external power grid.

6. A method for the production of self-powered thermal biomass conditioning pyrolysis co-production of high value liquid and solid products, characterized by, The preparation device according to any one of claims 1-5, comprising the following steps: S1, feeding process: biomass raw material particles are added to the pneumatic feeding device (1) through the feeding port (1-3); after the feeding is completed, the fluidizing air inlet (1-1) and the discharge port (1-4) of the pneumatic feeding device are opened, and the conveying air inlet (1-2) and the feeding port (1-3) are closed; the raw material inlet (2-1) and the gas outlet (2-3) of the pyrolysis reactor are opened, and the catalyst inlet (2-2), the pyrolysis oil gas outlet (2-4) and the pyrolysis carbon outlet (2-5) are closed; air compressor A (13) is opened to fluidize the raw material particles in the pneumatic feeding device, and then air compressor B (14) and the conveying air inlet (1-2) of the pneumatic feeding device are opened, so that the fluidized raw material particles are sent into the pyrolysis reactor (2); S2, reaction flow: open the pyrolysis reactor catalyst inlet (2-2), input catalyst from the catalyst storage (3); open the pyrolysis reactor oil gas outlet (2-4), close the pyrolysis reactor raw material inlet (2-1), catalyst inlet (2-2), gas outlet (2-3) and pyrolysis carbon outlet (2-5); start the stirrer (2-6) until the reaction is completed, and the biomass in the pyrolysis reactor (2) is subjected to conditioning pyrolysis in a constant temperature molten salt heating mode under an oxygen-free or inert atmosphere, the pyrolysis temperature is 400-700 o C, time 30-120 min; after the reaction is completed, open the pyrolysis reactor pyrolysis carbon outlet (2-5), and store the pyrolysis generated biochar into the biochar storage (11); S3, condensing process: the hot oil gas mixture generated by the pyrolysis reactor (2) is condensed and separated by the condenser (4), and the cooled pyrolysis gas is stored in the pyrolysis gas storage tank (8) for later use; the condensed bio-oil is aged and stratified in the bio-oil aging tank (5), the heavy components at the bottom are stored in the heavy bio-oil storage tank (12), the crude light bio-oil components at the top are separated in the oil-water separator (6) for secondary separation, and the separated heavy components are also stored in the heavy bio-oil storage tank (12); the refined light bio-oil is separated and stored in the light bio-oil storage tank (7); S4, heating process: the pyrolysis gas stored in the pyrolysis gas storage tank (8) is sent to the internal combustion generator set (9), the generated electric energy is used to heat the molten salt storage tank (10) through an electric heater, and the required constant temperature heat for the pyrolysis reactor (2) is provided, and the insufficient electric energy is provided by an external power grid; The catalyst in step S2 includes a metal potassium salt, and the metal potassium salt includes K2CO3, K3PO4 or CH3COOK; the catalyst accounts for 0.5%-2.0% of the mass fraction of the raw material.

7. The preparation method according to claim 6, characterized in that, The biomass raw material in step S1 includes agricultural and forestry waste, and the agricultural and forestry waste includes rice husk, straw and bamboo chips.

8. The preparation method according to claim 6, characterized in that, The temperature of the molten salt in the molten salt storage tank (10) in step S4 is 400-700 o C, and the pyrolysis reaction time in the pyrolysis reactor (2) is 30-120 min.

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