A method and system for preparing corn straw biochar based on pyrolysis temperature regulation

Abstract

The application belongs to the technical field of biomass resource utilization, and discloses a corn straw biochar preparation method and system based on pyrolysis temperature regulation, which comprises the following steps: drying, crushing and sieving corn straw, placing the corn straw in a pyrolysis reactor, discharging air by introducing inert gas, heating to the pyrolysis temperature at a set heating rate and keeping constant temperature, and finally cooling and collecting the solid product. By precisely controlling the pyrolysis temperature, the method realizes the synergistic regulation of the pore structure, fixed carbon content, volatile matter and potassium occurrence form of the corn straw biochar. Compared with the prior art, the method does not need to add chemical modifiers, and the process conditions are mild and controllable, effectively solving the problems of strong hydrophilicity, high viscosity and poor fluidity of traditional biochar used in coal water slurry system, and improving the stability and conveying performance of the biochar-coal powder multi-component slurry.

Description

Technical Field

[0001] This invention belongs to the field of biomass resource utilization technology, specifically a method and system for preparing corn straw biochar based on pyrolysis temperature control. Background Technology

[0002] The annual output of corn stalks is enormous, and a large amount of agricultural and forestry waste is not being efficiently utilized. Open burning and indiscriminate dumping not only waste resources but also cause air pollution and ecological and environmental problems. Biomass pyrolysis carbonization is an important technological path to achieve the reduction and high-value utilization of agricultural and forestry solid waste. It can convert low-grade biomass into carbon-rich, porous, and chemically stable biochar materials, which have broad application prospects in energy utilization, pollution control, and soil improvement.

[0003] Current research on biochar preparation mainly focuses on improving specific surface area and adsorption performance, while targeted preparation technologies for biochar specifically designed for coal-water slurry gasification remain relatively lacking. The fixed carbon content, volatile matter, pore structure, surface functional groups, and alkali metal occurrence forms of biochar directly affect its dispersibility, flowability, and system viscosity when blended with coal powder. Traditional pyrolysis processes often employ single-temperature carbonization, making it difficult to precisely control the physicochemical properties of biochar. The resulting biochar typically has a high content of hydrophilic groups, uneven pore development, and uncontrollable potassium migration and transformation. When blended with coal powder, it easily exhibits problems such as high viscosity, poor flowability, and insufficient stability, failing to meet the long-term stable operation requirements of industrial coal-water slurry gasification.

[0004] Corn stalks are rich in potassium, and the migration, transformation, and storage forms of potassium during pyrolysis directly affect the hydrophilicity / hydrophobicity and reactivity of biochar surfaces. Current technologies have not yet clarified the synergistic regulation mechanism of pyrolysis temperature on potassium speciation and pore structure, and lack controllable preparation schemes for jointly optimizing biochar structure and alkali metals through temperature fields. Summary of the Invention

[0005] This invention provides a method and system for preparing corn straw biochar based on pyrolysis temperature control. It solves the problems of traditional pyrolysis processes that often use a single temperature for carbonization, making it difficult to accurately control the physicochemical properties of biochar. The biochar prepared in this way usually has a high content of hydrophilic groups, uneven pore development, uncontrollable potassium migration and transformation, and is prone to high viscosity, poor fluidity, and insufficient stability when compounded with coal powder to form a slurry.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing corn straw biochar based on pyrolysis temperature control, comprising the following steps: The corn stalks are dried, crushed, and sieved to obtain corn stalk powder; The corn stalk powder is placed in a pyrolysis reactor, and an inert gas is introduced into the reactor to expel the air inside the reactor. The reactor is heated to the set pyrolysis temperature at a set heating rate and held at the set temperature for a set holding time. After pyrolysis is complete, stop heating, cool to room temperature, and collect the solid product.

[0007] According to one embodiment of the present invention, the steps of drying, crushing and sieving corn stalks are as follows: the corn stalks are dried to constant weight in a forced-air drying oven, crushed and then sieved through a 60-mesh standard sieve.

[0008] According to one embodiment of the present invention, drying corn stalks to constant weight in a forced-air drying oven specifically involves placing the corn stalks in a forced-air drying oven at 105°C for 24 hours.

[0009] According to one embodiment of the present invention, the inert gas is nitrogen with a purity of 99.99%.

[0010] According to one embodiment of the present invention, the inert gas flow rate introduced into the reactor is 0.5 NL / min, and the purging is continued for 5 min.

[0011] According to one embodiment of the present invention, in the programmed temperature rise pyrolysis step, the heating rate is 5°C / min and the isothermal holding time is 60min.

[0012] According to one embodiment of the present invention, the pyrolysis temperature is in the range of 400°C to 500°C.

[0013] According to one embodiment of the present invention, heating is stopped after pyrolysis is completed, and inert gas is continuously introduced until the temperature drops to room temperature.

[0014] This invention also provides a corn straw biochar preparation system based on pyrolysis temperature control, used to realize a method for preparing corn straw biochar based on pyrolysis temperature control, comprising: The raw material supply unit includes a biomass feeding device, a carrier gas supply device, and a preheating module. The preheating module is connected to the biomass feeding device, and the carrier gas supply device is connected to the preheating module. The reaction simulation unit includes a reactor body, a temperature / atmosphere control module, and a sensor group. The reactor body is connected to the preheating module, the temperature / atmosphere control module is connected to the reactor body, and the sensor group is installed on the reactor body. The product separation and detection unit includes a cyclone separator, a condenser, a surface area analyzer, a gas chromatograph, and a high-performance liquid chromatograph. The inlet of the cyclone separator is connected to the reaction furnace body, the solid outlet of the cyclone separator is connected to the condenser, and the surface area analyzer, the gas chromatograph, and the high-performance liquid chromatograph are respectively connected to the condenser. The parameter control unit includes a PLC controller, a touch screen, and a frequency converter module. The PLC controller is electrically connected to the temperature / atmosphere control module, the sensor group, the frequency converter module, the gas chromatograph, and the high-performance liquid chromatograph, respectively. The touch screen is electrically connected to the PLC controller. The data processing unit is electrically connected to the PLC controller; The exhaust gas treatment unit is connected to the exhaust port of the reactor body.

[0015] According to one embodiment of the present invention, the reaction simulation unit further includes a catalytic bed disposed in the reactor body; the frequency conversion module of the parameter control unit is electrically connected to the heating element of the reactor body; in the product separation and detection unit, the gas outlet of the cyclone separator is connected to the tail gas treatment unit.

[0016] Compared with existing technologies, this invention has the following advantages: This invention provides a method for preparing corn stalk biochar based on pyrolysis temperature control. The corn stalks are dried, crushed, and sieved, then placed in a pyrolysis reactor. Inert gas is introduced to purge air, and the temperature is raised to the pyrolysis temperature at a set rate and maintained at a constant temperature. Finally, the solid product is collected after cooling. This method achieves synergistic regulation of the pore structure, fixed carbon content, volatile matter, and potassium content of corn stalk biochar by precisely controlling the pyrolysis temperature. Compared with existing technologies, this method does not require the addition of chemical modifiers, and the process conditions are mild and controllable. It effectively solves the problems of strong hydrophilicity, high viscosity, and poor flowability of traditional biochar used in coal-water slurry systems, improving the stability and transport performance of biochar-coal powder multi-component slurry. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram illustrating the preparation system of an embodiment of the present invention; Figure 2 This is a schematic diagram of the process flow of the preparation method according to an embodiment of the present invention; In the diagram, 1-Raw material supply unit; 11-Biomass feeding device; 12-Catalyst feeding device; 13-Carrier gas supply device; 14-Preheating module; 2-Reaction simulation unit; 21-Reaction furnace body; 22-Catalyst bed; 23-Temperature / atmosphere control module; 24-Sensor group (temperature, pressure, atmosphere); 3-Product separation and detection unit; 31-Cyclone separator; 32-Condenser collector; 33-Gas chromatograph; 34-High performance liquid chromatograph; 35-Specific surface area analyzer; 4-Parameter control unit; 41-PLC controller; 42-Touch screen; 43-Frequency conversion module; 5-Data processing unit; 6-Tail gas treatment unit. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," and "set up" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components.

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, the biochar preparation and characterization system used in this invention includes: a raw material supply unit 1, a reaction simulation unit 2, a product separation and detection unit 3, a parameter control unit 4, a data processing unit 5, and a tail gas treatment unit 6.

[0025] The raw material supply unit 1 includes a biomass feeding device 11, a carrier gas supply device 13, and a preheating module 14. The preheating module 14 is connected to the biomass feeding device 11 and is used to dry and preheat the corn stalk powder. The carrier gas supply device 13 is connected to the preheating module 14 and is used to supply the system with inert gases such as high-purity nitrogen. This unit, through continuous feeding and preheating, ensures the uniformity of the dry state of the raw materials, providing a stable input for subsequent pyrolysis and avoiding the impact of fluctuations in the moisture content of the raw materials on the quality of the carbonized products.

[0026] The reaction simulation unit 2 includes a reactor body 21, a temperature / atmosphere control module 23, and a sensor array 24. The reactor body 21 is connected to the preheating module 14 and contains a quartz boat for carrying materials and a catalyst bed 22. The temperature / atmosphere control module 23 is connected to the reactor body 21 and controls the heating rate, holding time, and inert gas flow rate. The sensor array 24 is mounted on the reactor body 21 to monitor temperature, pressure, and atmosphere composition in real time. The beneficial effects of this unit are: through precise temperature / atmosphere control, the set pyrolysis curve can be accurately reproduced (e.g., heating to 475℃ at 5℃ / min and holding for 60min); the real-time feedback from the sensor array ensures the repeatability and reliability of the pyrolysis process, providing a hardware foundation for studying the evolution of biochar at different temperatures.

[0027] The product separation and detection unit 3 includes a cyclone separator 31, a condenser 32, a surface area analyzer 35, a gas chromatograph 33, and a high-performance liquid chromatograph 34. The inlet of the cyclone separator 31 is connected to the reactor body 21 for gas-solid separation; the solid outlet of the cyclone separator 31 is connected to the condenser 32 for collecting solid biochar; the surface area analyzer 35, gas chromatograph 33, and high-performance liquid chromatograph 34 are connected to the condenser 32 to determine the specific surface area, pore volume, volatile matter, fixed carbon, and potassium elemental speciation of the biochar. This unit achieves online separation and rapid multi-parameter characterization of pyrolysis products, significantly improving data acquisition efficiency and analytical accuracy compared to traditional manual sampling followed by offline detection.

[0028] The parameter control unit 4 includes a PLC controller 41, a touch screen 42, and a frequency converter module 43. The PLC controller 41 is electrically connected to the temperature / atmosphere control module 23, the sensor group 24, the frequency converter module 43, the gas chromatograph 33, and the high-performance liquid chromatograph 34, respectively. The touch screen 42 is electrically connected to the PLC controller 41, providing a human-machine interface. The frequency converter module 43 is electrically connected to the heating element of the reactor body 21 to achieve power regulation. This unit achieves fully automated control of the entire process. Operators can set parameters such as pyrolysis temperature and heating rate via the touch screen. The system automatically executes and records data, reducing human error and improving experimental efficiency.

[0029] The data processing unit 5 is electrically connected to the PLC controller 41 and is used to store and analyze the data collected by the sensors and detection instruments, and generate temperature-time curves, specific surface area-temperature relationship graphs, etc.

[0030] The exhaust gas treatment unit 6 is connected to the exhaust port of the reactor body 21, and the gas outlet of the cyclone separator 31 is also connected to the exhaust gas treatment unit 6 to purify the volatile organic compounds and harmful gases generated by pyrolysis and meet environmental emission requirements.

[0031] The various units of the above system work together to form a closed-loop preparation-characterization platform from raw materials to products, providing reliable equipment support for implementing the method of the present invention, which is conducive to process scale-up and industrial application.

[0032] The process flow of the method of the present invention is as follows: Figure 2 As shown, it mainly includes four core steps: raw material pretreatment, inert atmosphere establishment, programmed temperature pyrolysis, and cooling and collection.

[0033] (a) Raw material pretreatment The collected corn stalks were placed in a 105℃ forced-air drying oven for 24 hours to remove surface free water; they were then pulverized using a high-speed pulverizer and passed through a 60-mesh standard sieve to obtain uniformly sized stalk powder; the powder was then dried again at 105℃ to constant weight to remove internal bound water and sealed for later use.

[0034] Low-temperature slow drying avoids damage to the straw fiber structure by high temperature; passing through a 60-mesh sieve ensures uniform particle size, which is conducive to uniform heat transfer during pyrolysis and avoids product quality fluctuations caused by incomplete carbonization inside large particles; secondary drying to constant weight can completely remove moisture and prevent moisture from reacting with biochar at high temperature or causing product pore collapse.

[0035] (ii) Establishing an inert atmosphere Weigh 10g of dried corn stalk powder and spread it evenly in a quartz boat. Push the quartz boat into the constant temperature zone of a horizontal tube furnace. Introduce 99.99% pure nitrogen into the furnace at a flow rate of 0.5NL / min and purge for 5 minutes to completely remove the air from the furnace and create an anaerobic pyrolysis environment.

[0036] To avoid oxygen participating in pyrolysis and causing biochar oxidation and combustion, the yield of carbonization products is guaranteed; at the same time, an appropriate purging time can economically reduce the residual oxygen content in the furnace to the ppm level, preventing the unintended introduction of oxygen-containing functional groups.

[0037] (III) Programmed temperature pyrolysis The furnace temperature was raised to 400℃, 425℃, 450℃, 475℃ and 500℃ respectively at a uniform rate of 5℃ / min. After reaching the set temperature, the temperature was kept constant for 60 minutes to allow the corn stalks to be fully pyrolyzed and carbonized.

[0038] A uniform heating rate of 5℃ / min is used. A sufficiently slow heating rate allows volatiles to precipitate slowly, enabling the pore structure to develop gradually without causing structural breakage due to rapid gas production. Excessive heating may cause surface hardening and internal voids. Maintaining a constant temperature for 60 minutes ensures complete carbonization, resulting in a product with a stable, fixed carbon content.

[0039] (iv) Cooling and Sample Collection After pyrolysis, heating was stopped, and the product was allowed to cool naturally to room temperature under continuous nitrogen protection. The solid product was then removed and labeled as PC-400, PC-425, PC-450, PC-475, and PC-500 series biochar, respectively.

[0040] Cooling under nitrogen protection can prevent high-temperature biochar from oxidizing upon contact with air during the cooling process, thus maintaining the stability of its surface chemical properties.

[0041] Example 1 Corn stalks were dried in a 105℃ forced-air drying oven for 24 hours, pulverized, and passed through a 60-mesh standard sieve. They were then dried again at 105℃ to constant weight. 10g of the pretreated stalk powder was weighed and evenly spread in a quartz boat, then pushed into the constant-temperature zone of a horizontal tube furnace. Nitrogen gas with a purity of 99.99% was introduced at a flow rate of 0.5 NL / min for 5 minutes to purge the stalks. The temperature was increased to 400℃ at a rate of 5℃ / min and held at that temperature for 60 minutes. Heating was stopped, and the mixture was allowed to cool naturally to room temperature under nitrogen protection. The product was then labeled PC-400. Analysis showed that the obtained biochar had a volatile content of 18.86%, fixed carbon of 47.15%, a specific surface area of ​​1.991 m² / g, a total potassium content of approximately 14 mg / g, and a water-soluble potassium content of 72.36%.

[0042] Example 2 Except for the pyrolysis isothermal temperature being set at 425°C, all other conditions were the same as in Example 1, and the product was labeled PC-425. The volatile matter content was 18.64%, fixed carbon 45.39%, and water-soluble potassium 70.49%.

[0043] Example 3 Except for the pyrolysis isothermal temperature being set at 450℃, all other conditions were the same as in Example 1, and the product was labeled PC-450. The volatile matter content was 14.36%, fixed carbon was 51.51%, oxygen-containing functional groups were significantly reduced, and the specific surface area was significantly increased. This indicates that at 450℃, hemicellulose and cellulose were essentially completely decomposed, lignin began deep carbonization, and pores began to develop.

[0044] Example 4 Except for the pyrolysis isothermal temperature being set at 475℃, all other conditions were the same as in Example 1, and the product was labeled PC-475. The volatile matter content was 12.91%, fixed carbon was 52.38%, the specific surface area reached its maximum value of 4.471 m² / g, the pore volume reached its maximum value of 0.014 cm³ / g, the proportion of water-soluble potassium decreased to 67.81%, the proportion of organically bound potassium increased, and the number of hydrophilic groups (such as hydroxyl and carboxyl groups) significantly decreased.

[0045] The most significant advantages of this embodiment are: the biochar obtained by pyrolysis at 475℃ has the highest specific surface area and pore volume, a well-developed pore structure, and the fewest oxygen-containing functional groups and the lowest proportion of water-soluble potassium on its surface. This means that its surface has the strongest hydrophobicity, which can effectively reduce the viscosity and improve the flowability of the system when compounded with coal powder to form a slurry. In addition, potassium exists in an organically bound and residual state, and is not easily dissolved during the slurry formation process, thus preventing foaming or decreased stability of the slurry. Therefore, 475℃ is the optimal pyrolysis temperature for preparing biochar for coal-water slurry.

[0046] Example 5 Except for the pyrolysis isothermal temperature being set at 500℃, all other conditions were the same as in Example 1, and the product was labeled PC-500. The volatile matter content was 10.88%, the fixed carbon content was 53.53%, and the specific surface area decreased compared to 475℃. This is because at excessively high temperatures, minerals (such as potassium salts) inside the biochar melt and migrate to the surface, blocking some of the micropores; simultaneously, the condensation of volatile matter may also cause pore blockage.

[0047] Based on the data from Examples 1 to 5, the following evolutionary patterns can be summarized: Within the range of 400-475℃, as the pyrolysis temperature increases: The fixed carbon content gradually increased from 47.15% to 52.38%; The volatile matter content decreased from 18.86% to 12.91%; The number of oxygen-containing functional groups continues to decrease, and the surface hydrophobicity is enhanced; The specific surface area increased from 1.991 m² / g to 4.471 m² / g, and the pore volume increased from approximately 0.006 cm³ / g to 0.014 cm³ / g. The total potassium content decreased from approximately 14 mg / g to approximately 11 mg / g, with the proportion of water-soluble potassium decreasing from 72.36% to 67.81%, while the proportion of organically bound and residual potassium increased.

[0048] When the temperature rises to 500℃, the specific surface area decreases to about 3.5 m² / g, but the fixed carbon still continues to increase to 53.53%.

[0049] The above patterns indicate that pyrolysis temperature has a coupled regulatory effect on the physical structure and surface chemical properties of biochar. 475℃ represents the optimal balance between pore development and surface hydrophobicity, achieving both maximum specific surface area and a low level of hydrophilic groups, while minimizing the proportion of water-soluble potassium. This synergistic optimization mechanism is the core innovation of this invention, effectively solving the problems of existing technologies that solely pursue high specific surface area while neglecting surface hydrophilicity, or focus only on functional group changes while ignoring pore structure.

[0050] The complete working process of implementing the method of the present invention using the above system is as follows: Corn stalks, after pretreatment, are added to the biomass feeding device 11 and preheated and dried at 105°C in the preheating module 14. The carrier gas supply device 13 provides high-purity nitrogen gas to purge the reactor body 21 at a flow rate of 0.5 NL / min. The operator sets the pyrolysis temperature (e.g., 475°C), heating rate (5°C / min), and holding time (60 min) via the touch screen 42. The PLC controller 41 adjusts the heating power of the reactor body 21 through the frequency converter 43 and executes the program according to the set curve. The sensor group 24 monitors the temperature and pressure inside the furnace in real time and feeds it back to the PLC controller 41 to ensure that the temperature deviation is less than ±2°C. The gas-solid mixture generated by pyrolysis is separated by the cyclone separator 31. The solid biochar falls into the condenser collector 32 for cooling, and the tail gas enters the tail gas treatment unit 6 for purification before being discharged into the air. The specific surface area analyzer 35, the gas chromatograph 33, and the high performance liquid chromatograph 34 automatically sample and analyze the products. The data is recorded by the data processing unit 5 and a report is generated.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0052] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing corn straw biochar based on pyrolysis temperature control, characterized in that, Includes the following steps: The corn stalks are dried, crushed, and sieved to obtain corn stalk powder; The corn stalk powder is placed in a pyrolysis reactor, and an inert gas is introduced into the reactor to expel the air inside the reactor. The reactor is heated to the set pyrolysis temperature at a set heating rate and held at the set temperature for a set holding time. After pyrolysis is complete, stop heating, cool to room temperature, and collect the solid product.

2. The method according to claim 1, characterized in that, The specific steps for drying, crushing, and sieving corn stalks are as follows: dry the corn stalks to a constant weight in a forced-air drying oven, crush them, and then pass them through a 60-mesh standard sieve.

3. The method for preparing corn straw biochar based on pyrolysis temperature control according to claim 1, characterized in that, The process of drying corn stalks to constant weight in a forced-air drying oven involves placing the corn stalks in a forced-air drying oven at 105℃ for 24 hours.

4. The method for preparing corn straw biochar based on pyrolysis temperature control according to claim 1, characterized in that, The inert gas is nitrogen with a purity of 99.99%.

5. The method for preparing corn straw biochar based on pyrolysis temperature control according to claim 1, characterized in that, The inert gas flow rate was 0.5 NL / min, and the purging was continued for 5 min.

6. The method for preparing corn straw biochar based on pyrolysis temperature control according to claim 1, characterized in that, In the programmed heating pyrolysis step, the heating rate is 5℃ / min, and the isothermal holding time is 60min.

7. The method for preparing corn straw biochar based on pyrolysis temperature control according to claim 1, characterized in that, The pyrolysis temperature is in the range of 400℃ to 500℃.

8. The method for preparing corn straw biochar based on pyrolysis temperature control according to claim 1, characterized in that, After pyrolysis is complete, heating is stopped, and inert gas is continuously introduced until the temperature drops to room temperature.

9. A corn straw biochar preparation system based on pyrolysis temperature control, characterized in that, A method for preparing corn straw biochar based on pyrolysis temperature control as described in any one of claims 1-8 includes: The raw material supply unit (1) includes a biomass feeding device (11), a carrier gas supply device (13) and a preheating module (14). The preheating module (14) is connected to the biomass feeding device (11), and the carrier gas supply device (13) is connected to the preheating module (14). The reaction simulation unit (2) includes a reactor body (21), a temperature / atmosphere control module (23) and a sensor group (24). The reactor body (21) is connected to the preheating module (14), the temperature / atmosphere control module (23) is connected to the reactor body (21), and the sensor group (24) is installed on the reactor body (21). The product separation and detection unit (3) includes a cyclone separator (31), a condenser (32), a surface area analyzer (35), a gas chromatograph (33), and a high performance liquid chromatograph (34). The inlet of the cyclone separator (31) is connected to the reactor body (21), and the solid outlet of the cyclone separator (31) is connected to the condenser (32). The surface area analyzer (35), the gas chromatograph (33), and the high performance liquid chromatograph (34) are respectively connected to the condenser (32). The parameter control unit (4) includes a PLC controller (41), a touch screen (42), and a frequency converter (43). The PLC controller (41) is electrically connected to the temperature / atmosphere control module (23), the sensor group (24), the frequency converter (43), the gas chromatograph (33), and the high performance liquid chromatograph (34), respectively. The touch screen (42) is electrically connected to the PLC controller (41). The data processing unit (5) is electrically connected to the PLC controller (41); The exhaust gas treatment unit (6) is connected to the exhaust port of the reactor body (21).

10. A corn straw biochar preparation system based on pyrolysis temperature control according to claim 9, characterized in that, The reaction simulation unit (2) also includes a catalytic bed (22) disposed in the reactor body (21); the frequency conversion module (43) of the parameter control unit (4) is electrically connected to the heating element of the reactor body (21); in the product separation and detection unit (3), the gas outlet of the cyclone separator (31) is connected to the tail gas treatment unit (6).

Images