Double-shaft hydrothermal carbonization reactor

Abstract

The application discloses a double-shaft hydrothermal carbonization reaction kettle, which is characterized by the following aspects: the horizontal shaft stirring and the vertical shaft stirring are arranged, so that the uniformity of the stirring of the materials in the kettle body is improved, and the temperature distribution is more uniform; the feeding port is arranged at the middle of the bottom of the kettle body, and the discharging port is arranged at the middle of the top of the kettle body, so that the materials can form regular convection along the central axis of the kettle body, the double-layer stirring structure is matched to reduce the material deposition dead angle, the circulating pipeline connected between the feeding port and the discharging port is arranged, the circulating pump is matched to realize the backflow of the top carbon slurry to the kettle bottom, the material reaction residence time is prolonged, the mass transfer and heat transfer effects in the kettle are strengthened, the hydrothermal carbonization reaction uniformity is improved, and finally, the valves are additionally arranged at the inlet and outlet of the circulating pump, so that the two working conditions of the material circulation operation and direct discharging can be flexibly switched, the high-pressure medium in the kettle can be isolated when the circulating pump is overhauled, and the equipment operation safety is improved. The application is especially suitable for the hydrothermal carbonization reaction of high-solid-content and high-viscosity organic solid waste, and the overall treatment capacity is larger, and the reaction efficiency is higher.

Description

[0001] This application is The application number is: 202310222204.9 Application date: July 21, 2023 The invention is titled: Dual-shaft hydrothermal carbonization reactor. Divisional application of the invention patent Technical Field

[0002] This invention belongs to the field of chemical reaction vessel technology, and particularly relates to a biaxial hydrothermal carbonization reactor. Background Technology

[0003] Hydrothermal carbonization (HTC) technology is based on the high-pressure chemistry theory proposed by Friedrich Bergius, the German chemist who won the 1931 Nobel Prize in Chemistry. This method simulates the natural formation of coal, oil, and natural gas, reproducing this reaction process—which takes millions of years in nature—in a few hours under appropriate temperature, pressure, and pH conditions. The HTC reaction is carried out under conditions of evacuated air and added catalyst, at temperatures of 180-200°C and pressures of 20-35 bar, carbonizing organic materials (such as biological waste or sludge) into HTC biochar within hours. This method is conducted in an aquatic environment, thus eliminating the need for drying the input material, and is particularly suitable for water-rich biological organic waste and sludge. After dehydration, the HTC biochar has a low moisture content and, due to its high calorific value, can be used for climate-friendly power generation in coal-fired power plants or as a fossil fuel alternative in cement plants or waste incineration plants.

[0004] Industrial hydrothermal carbonization systems can be implemented using either batch or continuous production. Batch production involves feeding materials into the reactor in batches, heating them in a closed environment, and then subjecting them to a hydrothermal carbonization reaction at a fixed temperature and pressure. After the reaction time is reached, the materials are cooled, the reaction products are discharged, and the next batch is processed, repeating this cycle. Continuous production involves materials continuously entering the reaction system, remaining in the reactor for a fixed time, and then continuously discharging. Batch production, due to its low efficiency, is generally only used for research and small-scale production applications and is not adopted for large-scale industrial production; continuous production is suitable for large-scale industrial applications. Currently, there are few cases of continuous hydrothermal carbonization production, mainly due to its small processing capacity and high requirements for feed moisture content and flowability. Only materials with high flowability and high thermal conductivity are suitable for hydrothermal carbonization. Materials with high solids content have poor flowability and low thermal conductivity, resulting in high stirring resistance in the reactor, uneven stirring, uneven material temperature, low reaction efficiency, and reduced processing effectiveness. Therefore, the production capacity of existing reactors is relatively small, generally less than 100 t / d, which affects construction investment and operating costs. Summary of the Invention

[0005] The purpose of this invention is to provide a twin-shaft hydrothermal carbonization reactor, which aims to solve the technical problems of high stirring resistance, uneven material temperature, low reaction efficiency, and small production capacity in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A twin-shaft hydrothermal carbonization reactor, characterized in that it comprises a reactor body for containing materials and two sets of stirring components inside it. The reactor body is equipped with a heating element. The two sets of stirring components are a horizontal axis stirring component and a vertical axis stirring component. The horizontal axis stirring component is located at the bottom of the reactor body and is used to stir the materials at the bottom of the reactor body. The vertical axis stirring component is located above the horizontal axis stirring component and is used to stir the materials at the top. The reactor body has a feed inlet at the bottom and a discharge outlet at the top. The feed inlet is located at the middle of the bottom of the reactor, and the discharge outlet is located at the middle of the top of the reactor. A circulation pipeline is also provided between the feed inlet and the discharge outlet of the reactor body. The circulation pipeline includes a circulation pipe and a circulation pump. The inlet end of the circulation pipe is connected to the feed inlet of the reactor body, and the outlet end of the circulation pipe is connected to the discharge outlet of the reactor body. The circulation pump is installed on the circulation pipe and is used to return part of the discharged biochar slurry to the reactor body. Valves are provided at both the inlet and outlet of the circulation pump.

[0007] Preferably, the horizontal axis stirring assembly includes a horizontal axis driven by a motor, the horizontal axis is horizontally disposed at the bottom of the vessel, a plurality of stirring paddles are spaced apart along the length of the horizontal axis, the motor is disposed outside the vessel and its output shaft is connected to the end of the horizontal axis.

[0008] Preferably, there are two motors, which are respectively located at both ends of the horizontal axis.

[0009] Preferably, the bottom of the vessel is spherical, and the stirring paddle on the horizontal axis is longer in the middle and shorter at both ends.

[0010] Preferably, the vertical shaft stirring assembly includes a vertical shaft driven by a second motor, the vertical shaft being vertically disposed in the middle of the vessel body, and a plurality of stirring blades being spaced apart along the length of the vertical shaft, and the second motor being disposed at the top of the vessel body.

[0011] Preferably, the stirring paddles on the vertical shaft are arranged with alternating lengths along its length.

[0012] Preferably, the heating element is a heating jacket wrapped around the outer wall of the vessel and filled with heat-conducting oil.

[0013] Preferably, both the vertical and horizontal axes are provided with heat transfer oil inlet pipes and heat transfer oil outlet pipes, and the stirring paddles around the vertical and horizontal axes are provided with heat transfer oil channels. The inlet and outlet of the heat transfer oil channels in the stirring paddles are respectively connected to the heat transfer oil inlet pipe and the heat transfer oil outlet pipe.

[0014] Preferably, the vessel body is a vertical cylinder with a height-to-diameter ratio of 10:8 to 10:2, and both its upper and lower ends are spherical caps; the volume of the vessel body is 5 to 50 m³. 3 The processing capacity of the reactor is 30-400 t / d.

[0015] Preferably, the material inside the reactor is dehydrated sludge, plant straw, or livestock and poultry manure.

[0016] The beneficial effects of adopting the above technical solution are as follows: Compared with the prior art, the present invention uses a horizontal axis stirring assembly to stir the bottom of the reactor where the material has high viscosity, poor flowability, and high resistance. As the hydrothermal carbonization reaction progresses, the viscosity of the material decreases, the flowability increases, and the resistance decreases. A vertical axis stirring assembly is used to process the upper material, which has low viscosity, high flowability, and low resistance, resulting in more uniform stirring. Once the hydrothermal carbonization reaction is complete, the material is discharged from the outlet. The present invention combines horizontal and vertical axis stirring, which improves the uniformity of material stirring within the reactor, results in more uniform temperature, greater processing capacity, and higher reaction efficiency. By positioning the feed inlet at the bottom center and the discharge outlet at the top center of the reactor, the material can form a regular convection flow along the reactor's central axis. This, combined with a double-layer stirring structure, reduces dead zones for material sedimentation. A circulation pipeline connecting the feed and discharge inlets, along with a circulation pump, allows the top carbon slurry to flow back to the bottom, extending the material's residence time, enhancing mass and heat transfer within the reactor, and improving the uniformity of the hydrothermal carbonization reaction. Finally, valves are added to the inlet and outlet of the circulation pump, allowing for flexible switching between material circulation and direct discharge modes, and also isolating the high-pressure medium inside the reactor during pump maintenance, thus improving equipment safety. This invention is particularly suitable for hydrothermal carbonization of high-solids, high-viscosity organic waste, offering greater overall processing capacity and higher reaction efficiency. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a schematic diagram of the structure of a biaxial hydrothermal carbonization reactor provided in an embodiment of the present invention; In the diagram: 1—Bottle body; 2—Motor; 3—Vertical shaft; 4—Agitator; 5—Heat transfer oil jacket; 6—Motor; 7—Horizontal shaft; 8—Agitator; 9—Inlet; 10—Outlet; 11—Circulation pump; 12—Circulation pipe. Detailed Implementation

[0019] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] See Figure 1The present invention provides a dual-shaft hydrothermal carbonization reactor, comprising a reactor body 1 for containing materials and two sets of stirring components inside it. The reactor body is equipped with a heating component. The two sets of stirring components are a horizontal axis stirring component and a vertical axis stirring component. The horizontal axis stirring component is located at the bottom of the reactor body 1 and is used to stir the materials at the bottom of the reactor body. The vertical axis stirring component is located above the horizontal axis stirring component and is used to stir the materials at the top. The reactor body 1 has a feed inlet 9 at the bottom and a discharge outlet 10 at the top.

[0021] As a preferred structure, the vertical shaft stirring assembly includes a vertical shaft 3 driven by a motor 2. The vertical shaft 3 is vertically positioned in the middle of the vessel body 1, and several stirring paddles 4 are spaced apart along the length of the vertical shaft 3. The motor 2 is located at the top of the vessel body 1. The stirring paddles 4 on the vertical shaft 3 are arranged with alternating lengths along its length. This structure allows for intense turbulence of the material under stirring, greatly improving the material reaction efficiency and processing capacity. A circulation pipeline connecting the inlet 9 and the outlet 10 is then added, along with a circulation pump 11 to achieve the return of the top carbon slurry to the bottom of the vessel, extending the material's residence time, enhancing mass and heat transfer within the vessel, and improving the uniformity of the hydrothermal carbonization reaction. Finally, valves are added to the inlet and outlet of the circulation pump 11, allowing for flexible switching between material circulation operation and direct discharge, and also isolating the high-pressure medium inside the vessel during pump maintenance, thus improving equipment operational safety.

[0022] Meanwhile, the horizontal axis stirring assembly includes a horizontal axis 7 driven by a motor 6. The horizontal axis 7 is horizontally positioned at the bottom of the vessel body 1. Several stirring paddles 4 are spaced apart along the length of the horizontal axis 7. The motor 6 is located outside the vessel body 1, and its output shaft is connected to the end of the horizontal axis 7. There are two motors 6, which are respectively located at both ends of the horizontal axis 7.

[0023] In one specific embodiment of the present invention, such as Figure 1 As shown, the heating component is a heating jacket 5 filled with heat-conducting oil and wrapped around the outer wall of the vessel body 1. The heated heat-conducting oil is introduced into the heating jacket 5 to heat the material inside the vessel body. The uniform heating of the material is achieved by the cooperation of the vertical shaft stirring assembly and the horizontal shaft stirring assembly, thereby improving the reaction rate.

[0024] To achieve rapid heating of the material inside the reactor, heat transfer oil inlet and outlet pipes (not shown in the figure) are provided within both the vertical axis 3 and the horizontal axis 7. Heat transfer oil channels (not shown in the figure) are also provided within the stirring paddles surrounding the vertical and horizontal axes. The inlets and outlets of these channels are connected to the heat transfer oil inlet and outlet pipes, respectively. During stirring, the heat transfer oil within the stirring paddles accelerates the heating of the material in the middle of the reactor, further increasing the heating rate and thus accelerating the reaction.

[0025] Further optimize the above technical solutions, such as Figure 1 As shown, a circulation pipeline is provided between the inlet 9 and outlet 10 of the reactor body 1. This circulation pipeline includes a circulation pipe 12 and a circulation pump 11. The inlet end of the circulation pipe 12 is connected to the inlet 9 of the reactor body 1, and the outlet end of the circulation pipe 12 is connected to the outlet 10 of the reactor body 1. The circulation pump 11 is mounted on the circulation pipe 12 and is used to return a portion of the discharged biochar slurry to the reactor body 1. Valves are installed at both the inlet and outlet of the circulation pump to control the material flow rate according to actual conditions. This structure improves the fluidity and temperature distribution uniformity of the material entering the reactor body, ensures stable temperature within the reactor body, improves the heat transfer efficiency and reaction efficiency of the material, shortens the reaction time, and increases the processing capacity of the reactor.

[0026] In specific manufacturing, the vessel body 1 is a vertical cylinder with spherical caps at both the top and bottom. To ensure thorough mixing of the material at the bottom of the vessel body 1, the stirring paddle 4 on the horizontal shaft 7 is longer in the middle and shorter at both ends. This structure improves the uniformity of material mixing.

[0027] In the specific design, the height-to-diameter ratio of vessel 1 is 10:8 to 10:2, and the volume of vessel 1 is 5 to 50 m³. 3 The processing capacity of the reactor is 30-400 t / d.

[0028] The reactor body 1 provided by this invention can process high-solids, high-viscosity organic solid waste, and is especially suitable for hydrothermal carbonization reactions of materials such as dewatered sludge, plant straw, and livestock and poultry manure. The following are several specific embodiments.

[0029] Example 1 Hydrothermal carbonization reactor: 2.5m in diameter, 6m in height, 32m³ in volume. 3 Sludge treatment capacity: 230t / d; Bottom horizontal shaft agitator: 15kw motor, 4 pairs of agitators, 1m agitator diameter at both ends, and 1.6m agitator diameter in the middle; Upper vertical shaft agitator: motor power 25kw, 5 pairs of agitators, alternating between long and short agitators, the long agitator is 1m long and the short agitator is 0.8m long; The feed inlet is located at the middle of the bottom of the reactor, and the discharge outlet is located at the middle of the top. Heating is achieved using a heat transfer oil jacket.

[0030] (1) Dewatered sludge with a moisture content of 8% from a sewage treatment plant in Chuzhou was heated to 180°C by a preheating system and mixed with sulfuric acid. The amount of sulfuric acid added was 10g / 100gDS of the amount of dry sludge to be treated. The sludge was squeezed into the reactor from the feed inlet at a feed rate of 9.6t / h. (2) The reactor is heated by a heat transfer oil jacket to maintain the reaction temperature at 180℃; (3) The material flows from bottom to top and stays in the reactor for 3 hours; (4) The biochar slurry is discharged from the reactor outlet at a rate of 9.6 t / h. (5) After the biochar slurry is cooled, solid-liquid separation is performed. The fluidity of the biochar slurry and the moisture content of the solid-liquid separation cake are tested.

[0031] Example 2 Hydrothermal carbonization reactor: 1.8m in diameter, 5m in height, 14m³ in volume. 3 Sludge treatment capacity: 100t / d; Bottom horizontal shaft agitator: 10kw motor, 5 pairs of agitators, 0.6m agitator diameter at both ends, and 1.2m agitator diameter in the middle; Upper vertical stirring: motor power 20kw, 5 pairs of stirring blades, alternating between long and short, the long stirring blade is 0.8m long and the short stirring blade is 0.6m long; The feed inlet is located at the middle of the bottom of the reactor, and the discharge outlet is located at the middle of the top. Heating is achieved using a heat transfer oil jacket.

[0032] (1) Dewatered sludge with a moisture content of 8% from a sewage treatment plant in Chuzhou was heated to 180°C by a preheating system and mixed with sulfuric acid. The amount of sulfuric acid added was 10g / 100gDS of the amount of dry sludge to be treated. The sludge was squeezed into the reactor from the feed inlet at a feed rate of 4.2t / h. (2) The reactor is heated by a heat transfer oil jacket to maintain the reaction temperature at 180℃; (3) The material flows from bottom to top and stays in the reactor for 3 hours; (4) The biochar slurry is discharged from the outlet of the reactor at a rate of 4.2 t / h; (5) After the biochar slurry is cooled, solid-liquid separation is performed. The fluidity of the biochar slurry and the moisture content of the solid-liquid separation cake are tested.

[0033] Comparative Example 1 Hydrothermal carbonization reactor: 2.5m in diameter, 6m in height, 32m³ in volume. 3 Sludge treatment capacity: 230t / d; Vertical single-axis stirring: motor power 40kw, from bottom to top, 5 pairs of stirring blades, alternating between long and short, the long stirring blade is 1m long and the short stirring blade is 0.8m long; The feed inlet is located at the middle of the bottom of the reactor, and the discharge outlet is located at the middle of the top. Heating is achieved using a heat transfer oil jacket.

[0034] (1) Dewatered sludge with a moisture content of 8% from a sewage treatment plant in Chuzhou was heated to 180°C by a preheating system and mixed with sulfuric acid. The amount of sulfuric acid added was 10g / 100gDS of the amount of dry sludge to be treated. The sludge was squeezed into the reactor from the feed inlet at a feed rate of 9.6t / h. (2) The reactor is heated by a heat transfer oil jacket to maintain the reaction temperature at 180℃; (3) The material flows from bottom to top and stays in the reactor for 3 hours; (4) The material is discharged from the outlet of the reactor at a rate of 9.6 t / h; (5) After the biochar slurry is cooled, solid-liquid separation is performed. The fluidity of the biochar slurry and the moisture content of the solid-liquid separation cake are tested.

[0035] Comparative Example 2 Comparative Example 1 uses the same reactor, but the residence time of the material in the reactor is 5 hours, and the processing capacity is 140 t / d. Other processing steps are the same as in Comparative Example 1.

[0036] Comparative Example 3 Hydrothermal carbonization reactor: Diameter 1.6m, height 4.3m, volume 8.6m³ 3 Sludge treatment capacity of 50t / d; Vertical single-shaft stirring: 15kw motor, 4 pairs of stirring blades of the same length from bottom to top, stirring diameter 1.2m; The feed inlet is located at the middle of the bottom of the reactor, and the discharge outlet is located at the middle of the top. Heating is achieved using a heat transfer oil jacket.

[0037] (1) Dewatered sludge with a moisture content of 8% from a sewage treatment plant in Chuzhou was heated to 180°C by a preheating system and mixed with sulfuric acid. The amount of sulfuric acid added was 10g / 100gDS of the amount of dry sludge to be treated. The sludge was squeezed into the reactor from the feed inlet at a feed rate of 2.1t / h. (2) The reactor is heated by a heat transfer oil jacket to maintain the reaction temperature at 180℃; (3) The material flows from bottom to top and stays in the reactor for 3 hours; (4) The material is discharged from the outlet of the reactor at a rate of 2.1 t / h; (5) After the biochar slurry is cooled, solid-liquid separation is performed. The fluidity of the biochar slurry and the moisture content of the solid-liquid separation cake are tested.

[0038] Table 1

[0039] Notes*: × – Poor liquidity; ○ – Moderate liquidity; ◎ – Good liquidity The results are shown in Table 1. Sludge with 80% moisture content entering the reactor has high viscosity and poor flowability. Using the twin-shaft stirring equipment of this invention, the stirring is more uniform, the material temperature is more uniform, and the reaction efficiency is high. Especially in the early stages of hydrothermal carbonization, the horizontal shaft tumbling stirring makes the stirring more uniform and efficient for materials with high viscosity and high resistance. As the hydrothermal carbonization reaction proceeds, the viscosity of the material decreases, the flowability increases, and the resistance decreases. Vertical stirring, with alternating long and short stirring paddles, easily creates turbulence, resulting in even higher efficiency. This is reflected in the good flowability of the produced biochar slurry and the low moisture content of the biochar cake after solid-liquid separation. In contrast, traditional single-shaft vertical stirring results in uneven stirring, leading to uneven material temperature distribution and reduced hydrothermal carbonization reaction efficiency. Although extending the residence time can improve the hydrothermal carbonization reaction effect, it is still not as good as the treatment effect of the technical solution of this invention. Comparative Example 3 shows that reducing the reactor volume and reducing the processing capacity can improve the hydrothermal reaction efficiency and treatment effect. Therefore, the traditional single-shaft stirring has a lower processing capacity, while the technical solution of this invention has a larger processing capacity and higher processing efficiency.

[0040] In summary, the present invention has the following beneficial effects: 1. The biaxial hydrothermal carbonization reactor provided by the present invention adopts biaxial stirring, with horizontal stirring at the bottom and vertical stirring at the top; 2. This invention addresses the issue of high material viscosity, poor flowability, and high stirring resistance in the initial stage of hydrothermal carbonization reaction. It employs a transverse tumbling stirring method with short stirring paddles at both ends and a long stirring paddle in the middle, thereby improving the uniformity of material stirring. 3. As the hydrothermal carbonization process progresses, the viscosity of the material decreases, its fluidity increases, and its resistance decreases. Vertical stirring is adopted, resulting in high stirring efficiency and more uniform stirring. In the axial direction, as the viscosity of the material decreases, the length of the stirring blades on the stirring shaft alternates, creating intense turbulence. 4. The twin-shaft hydrothermal carbonization reactor provided by this invention fully utilizes the characteristics of strong horizontal tilting stirring force and high vertical stirring space utilization efficiency, resulting in high reaction efficiency and large processing capacity. 5. The biaxial hydrothermal carbonization reactor provided by this invention can achieve the reduction, stabilization and harmless treatment of solid waste with high organic content, retain the organic matter and resources, facilitate end-of-pipe resource utilization and reduce carbon emissions.

[0041] Many specific details have been set forth in the foregoing description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed above.

Claims

1. A twin-shaft hydrothermal carbonization reactor, characterized in that: The device includes a vessel body for containing materials and two sets of stirring assemblies inside it. The vessel body is equipped with a heating element. The two sets of stirring assemblies are a horizontal axis stirring assembly and a vertical axis stirring assembly. The horizontal axis stirring assembly is located at the bottom of the vessel body and is used to stir the materials at the bottom of the vessel body. The vertical axis stirring assembly is located above the horizontal axis stirring assembly and is used to stir the materials at the top. The bottom of the vessel body is provided with a feed inlet and the top is provided with a discharge outlet. The feed inlet is located at the middle of the bottom of the reactor, and the discharge outlet is located at the middle of the top of the reactor. A circulation pipeline is also provided between the feed inlet and the discharge outlet of the reactor body. The circulation pipeline includes a circulation pipe and a circulation pump. The inlet end of the circulation pipe is connected to the feed inlet of the reactor body, and the outlet end of the circulation pipe is connected to the discharge outlet of the reactor body. The circulation pump is installed on the circulation pipe and is used to return part of the discharged biochar slurry to the reactor body. Valves are provided at both the inlet and outlet of the circulation pump.

2. The twin-shaft hydrothermal carbonization reactor according to claim 1, characterized in that: The horizontal axis stirring assembly includes a horizontal axis driven by a motor. The horizontal axis is horizontally positioned at the bottom of the vessel. Several stirring paddles are spaced apart along the length of the horizontal axis. The motor is located outside the vessel and its output shaft is connected to the end of the horizontal axis.

3. The twin-shaft hydrothermal carbonization reactor according to claim 2, characterized in that: There are two motors, which are respectively located at both ends of the horizontal shaft; the bottom of the vessel is spherical, and the stirring paddle on the horizontal shaft is longer in the middle and shorter at both ends.

4. The twin-shaft hydrothermal carbonization reactor according to claim 2, characterized in that: The vertical shaft stirring assembly includes a vertical shaft driven by a second motor. The vertical shaft is vertically arranged in the middle of the vessel body, and several stirring blades are arranged at intervals along the length of the vertical shaft. The second motor is located at the top of the vessel body.

5. The twin-shaft hydrothermal carbonization reactor according to claim 4, characterized in that: The stirring paddles on the vertical shaft are arranged in alternating lengths along its length.

6. The twin-shaft hydrothermal carbonization reactor according to claim 1, characterized in that: The heating element is a heating jacket wrapped around the outer wall of the vessel and filled with heat-conducting oil.

7. The twin-shaft hydrothermal carbonization reactor according to claim 4, characterized in that: Both the vertical and horizontal axes are equipped with heat transfer oil inlet pipes and heat transfer oil outlet pipes. The stirring paddles around the vertical and horizontal axes are equipped with heat transfer oil channels. The inlet and outlet of the heat transfer oil channels in the stirring paddles are respectively connected to the heat transfer oil inlet pipe and the heat transfer oil outlet pipe.

8. The twin-shaft hydrothermal carbonization reactor according to claim 7, characterized in that: Both ends of the vessel are spherical crown-shaped; the processing capacity of the reactor is 30-400 t / d.

9. The twin-shaft hydrothermal carbonization reactor according to claim 8, characterized in that: The material inside the reactor is dehydrated sludge, plant straw, or livestock and poultry manure.

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