Continuous hydrothermal carbonization device

Abstract

The invention relates to the technical field of organic waste hydrothermal carbonization treatment, and discloses a continuous hydrothermal carbonization device which comprises a feeding unit, a reaction unit and a separation unit, the feeding unit comprises a feeding bin, a mixer and a pressurization assembly which are communicated in sequence, the pressurization assembly is communicated with an inlet of the reaction unit, and the separation unit is communicated with an outlet of the reaction unit; the pressurizing assembly comprises two stages of pressurizing pistons which are connected in parallel; the separation unit comprises a cooling and pressure reducing assembly and a product filtering separator which are communicated in sequence, the cooling and pressure reducing assembly is communicated with an outlet of the reaction unit, the cooling and pressure reducing assembly comprises two channels which are connected in parallel, the two channels are communicated with a heat exchanger, the heat exchanger is communicated with a water inlet pipe, and an outlet of the water inlet pipe is communicated with the feeding bin. According to the scheme, the two-stage pressurizing piston feeding and two-channel pressure-reducing cooling discharging design is combined, so that the continuity and the solid-liquid uniform mixing effect of the hydrothermal reaction process are improved, the mass transfer and heat transfer efficiency in the hydrothermal reaction process is effectively improved, and the overall reaction efficiency and continuity are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrothermal carbonization treatment of organic wastes such as crop straws, restaurant kitchen waste, sewage sludge, etc., and in particular to a continuous hydrothermal carbonization device. Background Art

[0002] Hydrothermal reaction technology uses a high-temperature, high-pressure hydrothermal reaction environment to efficiently convert organic waste such as crop straw, restaurant kitchen waste, and sewage sludge into high-value-added products such as biochar, achieving heavy metal stabilization and the recovery of nutrients such as phosphorus, providing a low-carbon and environmentally friendly solution for waste reduction, harmlessness, and resource utilization. However, the continuity of hydrothermal reactions still faces technical problems, such as the difficulty in ensuring the long-term stable operation and sealing of reactors in high-pressure and high-temperature environments, equipment corrosion, and high energy consumption; uneven solid-liquid mixing during continuous feeding and discharging, resulting in low mass and heat transfer efficiency and difficulty in controlling the reaction process; product separation is difficult to achieve efficiently in a continuous process, which can easily cause pipeline blockage. These problems lead to insufficient process stability when hydrothermal reactions are applied on a large scale, and it is difficult to match the continuity and economic requirements of industrial production, limiting its widespread promotion.

[0003] For example, the prior art CN108129001A discloses a continuous hydrothermal carbonization system and process for livestock and poultry manure, which includes a fermentation tank, a high-pressure sludge pump, a heater, a carbonization reactor, a cooler, a storage tank, a sludge pump, and a solid-liquid separator connected in sequence. The fermentation tank is also connected to a first gas collection device via a pipeline, and the storage tank is also connected to a second gas collection device via a pipeline. A continuous hydrothermal carbonization process for livestock and poultry manure is also disclosed, which includes fermenting pretreated livestock and poultry manure in an anaerobic fermentation tank, and then continuously inputting the power provided by the high-pressure sludge pump into the heater, carbonization reactor, and cooler. The cooled carbonized product is separated by a solid-liquid separator to obtain hydrothermal charcoal and carbonized liquid. However, the prior art still has the following technical problems: (1) Although the existing technology also has a circulating heating device, it transfers heat through a medium. For example, the heat recovered in the cooler is transferred to the reaction material in the heater. This process involves two heat transfers, resulting in a large energy loss. There are still problems such as uneven heat transfer and low mass and heat transfer efficiency.

[0004] (2) The existing technology uses heat transfer medium to control the temperature of the reaction materials in the heater, carbonization reactor and cooler. In addition to the low heat conduction efficiency, the heat transfer medium needs to be descaled and decontaminated after long-term operation, which increases the volume and cost of sewage treatment.

[0005] (3) The reaction materials in the existing technology need to be fermented in advance before entering the continuous hydrothermal carbonization system for treatment, which will lead to a longer process and increased costs.

[0006] (4) The equipment in the existing continuous hydrothermal carbonization system has no replacement, which makes it prone to failure during continuous operation. Once a failure occurs, the system can only be shut down for maintenance and cannot continue production, affecting production continuity.

[0007] In view of this, the development of a continuous hydrothermal carbonization device not only effectively makes up for the shortcomings of existing technologies, but also simplifies the processing flow, reduces costs, reduces energy consumption, etc., which is of great significance to equipment protection and safety in the continuous production process. Summary of the Invention

[0008] The present invention aims to provide a continuous hydrothermal carbonization device to solve the technical problem of uneven solid-liquid mixing in the continuous feeding and discharging process of the existing hydrothermal carbonization device, which leads to low mass and heat transfer efficiency.

[0009] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a continuous hydrothermal carbonization device, comprising a feeding unit, a reaction unit, and a separation unit, wherein the feeding unit comprises a feeding bin, a mixer, and a pressurizing assembly connected in sequence, the pressurizing assembly is connected to the inlet of the reaction unit, and the pressurizing assembly comprises two-stage pressurizing pistons connected in parallel; the separation unit comprises a cooling and decompression assembly and a product filter separator connected in sequence, the cooling and decompression assembly is connected to the outlet of the reaction unit, the cooling and decompression assembly comprises two parallel channels, the two channels are connected with a heat exchanger, the heat exchanger is connected with a water inlet pipe, and the outlet of the water inlet pipe is connected to the feeding bin.

[0010] The principles and advantages of this solution are: 1. This scheme combines a two-stage pressurized piston feeding and a dual-channel pressure-reducing and cooling discharging design, which improves the continuity of the hydrothermal reaction process and the solid-liquid mixing effect, thereby effectively improving the mass and heat transfer efficiency during the hydrothermal reaction process, and further improving the overall reaction efficiency and continuity.

[0011] 2. This solution effectively recovers the heat from the high-temperature materials in the reaction unit by setting up heat exchangers on the dual channels, and uses the recovered heat to heat the inlet water. On the one hand, it recovers the heat in the post-reaction materials while reducing the heat required for heating the materials in the hydrothermal reaction stage, effectively reducing energy consumption. The applicant has found through long-term experiments that using a heat exchanger to recover the heat energy at the reactor outlet and preheat the feed liquid can effectively save more than 20% of energy; on the other hand, the heated inlet water is mixed with the raw materials to be treated (such as crop straw, restaurant kitchen waste, sewage sludge and other organic wastes), which effectively improves the mixing effect during the solid-liquid mixing process, thereby further improving the mass transfer and heat transfer efficiency during the hydrothermal reaction process.

[0012] 3. The feeding unit of this scheme is configured as a continuous stirring system by setting the mixer to facilitate further mixing of the solid-liquid mixture initially mixed in the feeding bin, and then feeding it to the reaction unit through a two-stage pressurized piston, which is beneficial to ensure the continuity of material feeding, thereby ensuring the continuous progress of the hydrothermal reaction and improving production efficiency.

[0013] 4. This solution utilizes a dual-channel decompression and cooling assembly and a matching heat exchanger to achieve heat exchange, cooling, and pressure reduction of the reaction materials. After cooling and pressure reduction, the reaction materials are then filtered and separated by a product filter, utilizing the residual pressure to achieve initial separation of solid products from gaseous and liquid products, further enhancing the continuity of raw material mixing, reaction, and separation. Depending on needs, solid and liquid products can be discharged intermittently, while gaseous products can be discharged continuously.

[0014] 5. This solution utilizes a closed system, with mixed materials transported throughout the entire process through sealed pipelines, preventing the escape of harmful gases (such as H2S and NH3) and reducing the risk of VOC emissions. Furthermore, the high-temperature, high-pressure environment can completely inactivate pathogens (e.g., E. coli inactivation rate >99.9%), eliminating biological contamination.

[0015] Preferably, as an improvement, a stirrer is provided in the mixer.

[0016] Technical effect: This solution adopts the above-mentioned setting, which facilitates enhancing fluid turbulence through spiral blades or microchannel structures, shortening the mixing time while ensuring the solid-liquid mixing effect.

[0017] Preferably, as an improvement, the reaction unit includes a preheater and a reactor connected in sequence, and the preheater and the reactor are both tubular reactors with external jacket heating; the outlet end of the two-stage pressurizing piston is connected to the inlet end pipeline of the preheater, and the outlet end of most reactors is connected to the inlet end of the dual channel.

[0018] Technical Effect: This solution utilizes the aforementioned setup, where the material is heated to a predetermined temperature in a preheating tube before entering the reactor. This facilitates rapid temperature increase, effectively improving the speed and efficiency of the hydrothermal reaction. Furthermore, the preheater also enhances the continuity of the hydrothermal reaction. Jacket heating, on the other hand, allows for heating of the mixture using various heating methods, such as electric heating, a molten salt bath, or supercritical fluid heating, facilitating energy supply adaptation to diverse processing environments.

[0019] Preferably, as an improvement, the inlet end of the preheater and the reactor is located at the bottom, and the outlet end is located at the top.

[0020] Technical effect: This solution adopts the above-mentioned setting, so that the mixed material flows from bottom to top, which facilitates to extend its residence time and rapid reaction in the preheater and reactor, promotes sufficient preheating and reaction, and thus improves the hydrothermal reaction effect.

[0021] Preferably, as an improvement, the tops of the preheater and the reactor are both provided with a safety valve, a thermocouple, and a pressure gauge.

[0022] Technical effect: This solution adopts the above-mentioned settings, which facilitates real-time monitoring of temperature and pressure through pressure gauges and thermocouples. If the pressure suddenly rises or the temperature gets out of control, emergency pressure relief or interlock shutdown is triggered. The emergency pressure relief pipeline is connected to a safe area to prevent overpressure explosion and improve the safety of system production.

[0023] Preferably, as an improvement, this solution also provides a continuous hydrothermal carbonization process, which is completed based on the above-mentioned continuous hydrothermal carbonization device and includes the following steps: Step 1: The incoming water exchanges heat with the reaction product and then mixes with the organic waste to form a mixed material; Step 2: Pressurize the mixed material and convey it to the preheater to preheat the mixed material; Step 3: transporting the preheated mixed material to the reactor, heating it to complete the hydrothermal reaction, and obtaining a reaction product; Step 4: The reaction product is separated into gas, solid and liquid phases after heat exchange with water to obtain gas product, solid product and liquid product.

[0024] Technical effect: This solution adopts the above-mentioned settings to facilitate improving the continuity and efficiency of the hydrothermal reaction. Specifically, this solution effectively ensures that the material enters the reactor continuously and stably through a combined design of pressurized conveying and preheating, avoiding the energy consumption and time loss of the start-up and shutdown of the intermittent process. The continuous reactor design can achieve 24-hour uninterrupted operation, effectively improving the processing capacity. In this solution, the initial temperature rise of the preheater not only enables the mixed material to undergo a hydrothermal reaction quickly after entering the reactor, but also initiates a partial hydrolysis reaction, reducing local over-reactions caused by sudden temperature changes in the reactor. Precise temperature control in the reactor (±5°C fluctuation) ensures that the organic matter is fully carbonized, and the physical and chemical properties (such as porosity and calorific value) of the generated hydrochar are more stable.

[0025] Preferably, as an improvement, in step 1, the temperature of the influent after heat exchange is 80-90° C.; and the mixing ratio of the influent and the organic waste is 1:3-1:5.

[0026] Technical Effect: This solution utilizes the above-mentioned configuration to maximize cascaded thermal energy utilization and improve mixing efficiency. Specifically, by controlling the inlet water temperature after heat exchange, waste heat from the reaction products can be effectively recovered while avoiding the risk of excessive temperature rise leading to heat exchanger scaling (e.g., carbonate deposition at temperatures above 95°C). Furthermore, this temperature range allows for the initial activation of readily hydrolyzable components in the organic waste (such as pectin and hemicellulose), shortening the time it takes to reach the target temperature in the subsequent reactor and reducing energy consumption in the main reactor by approximately 20%. Furthermore, at this temperature, the viscosity of the mixture of organic waste (such as sludge and food waste) and water is significantly reduced, ensuring stable operation of the transfer pump and reducing the risk of pipeline blockage. Finally, it inhibits the activity of anaerobic bacteria, preventing fermentation and gas production during transfer, and improving operational safety. Regarding the control of the mixing ratio of inlet water and organic waste, this mixing ratio achieves a moisture content of approximately 75-83% after mixing, meeting optimal reaction conditions for hydrothermal carbonization. Water, acting as a heat transfer medium, facilitates heat penetration from the aqueous phase to the solid particles, ensuring uniform heat transfer. On the other hand, sufficient moisture reduces excessive carbonization of organic matter caused by localized high temperatures, effectively inhibiting coking. The applicant discovered through long-term experiments that when the moisture content is low, the reaction tends to solid-state carbonization, producing hydrothermal char with a higher calorific value, but the reaction time needs to be extended. When the moisture content is high, the reaction tends to hydrolysis and liquefaction, increasing the concentration of organic acids in the liquid product, making it suitable for subsequent resource extraction. By flexibly adjusting the solid-liquid mixing ratio, it can be adapted to different raw material characteristics (e.g., high-fiber straw requires a higher moisture content).

[0027] Preferably, as an improvement, in step 2, the pressurized pressure is 2.5-3.5 MPa.

[0028] Technical Effect: This solution utilizes organic waste, such as crop straw, restaurant waste, and sewage sludge, which can easily adhere to pipes and become difficult to transport. This solution utilizes the aforementioned configuration to facilitate continuous delivery of the reactants. The applicants have discovered through long-term experiments that excessive pressure increases energy consumption and equipment wear, while insufficient pressure results in discontinuous material delivery.

[0029] Preferably, as an improvement, in step 2, the preheating temperature is 120-150°C.

[0030] Technical Effect: This solution adopts the above-mentioned configuration to preheat the reaction materials in advance, effectively ensuring a rapid reaction after entering the reactor, thereby improving reaction efficiency and effect. The applicant has found through long-term experiments that if the preheating temperature is too high, carbonization will be triggered prematurely, leading to pipe blockage; while if the preheating temperature is too low, the hydrolysis reaction will be insufficient.

[0031] Preferably, as an improvement, in step three, the temperature of the hydrothermal reaction is 200-240° C., and the reaction residence time is 45-90 min.

[0032] Technical Effect: This solution adopts the above-mentioned configuration, which effectively ensures the full carbonization of organic matter through precise temperature control within the reactor, resulting in hydrothermal char with more stable physical and chemical properties (such as porosity and calorific value). The applicant has discovered through long-term experiments that if the temperature of the hydrothermal reaction is too high, it will lead to excessive decomposition of organic matter, generating a large amount of small-molecule organic matter (such as acetic acid and phenols), causing the hydrothermal char skeleton to collapse; if the temperature of the hydrothermal reaction is too low, carbonization will be incomplete and the rigid structure of the biomass (such as cellulose and lignin) cannot be fully opened, resulting in an incomplete polycondensation reaction and incomplete formation of the char skeleton. If the reaction residence time is too long, the specific surface area of the hydrothermal char will decrease due to the collapse of micropores; if the reaction residence time is too short, the char structure will be loose due to insufficient polycondensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the continuous hydrothermal carbonization device in Example 1 of the present invention.

[0034] The reference numerals in the drawings of the specification include: feed bin 11, mixer 12, pressurizing piston 13, hydraulic pump 14, hydraulic oil tank 15, preheater 21, reactor 22, safety valve 23, thermocouple 24, pressure gauge 25, jacket 26, separator 31, dual channel 32, heat exchanger 33, and water inlet pipe 34. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following examples and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used are all commercially available.

[0036] Example 1 This solution provides a continuous hydrothermal carbonization device, such as Figure 1 As shown, it includes a feeding unit, a reaction unit, and a separation unit.

[0037] The feed unit consists of a sequentially connected feed bin 11, a mixer 12, and a pressurizing assembly. The mixer 12 houses an agitator. The pressurizing assembly is connected to the inlet of the reaction unit and includes two parallel stages of pressurizing pistons 13. Each stage of the pressurizing pistons 13 is powered by a hydraulic pump 14 connected to a hydraulic oil tank 15.

[0038] The separation unit includes a cooling and decompression assembly and a product filter separator 31, which are connected in series. The cooling and decompression assembly is connected to the outlet of the reaction unit. The cooling and decompression assembly includes two parallel channels 32, which are connected to a heat exchanger 33. The heat exchanger 33 is connected to a water inlet pipe 34, and the outlet of the water inlet pipe 34 is connected to the feed bin 11. This solution uses heat exchanger 33 to recover heat energy from the outlet of the reactor 22, preheating the incoming water before mixing it with the organic waste feedstock, effectively saving energy by over 20%.

[0039] The reaction unit includes a preheater 21 and a reactor 22, which are connected in sequence. Both the preheater 21 and the reactor 22 are tubular reactors 22, which are heated by an external jacket 26. The inlet end of the preheater 21 and the reactor 22 are located at the bottom, and the outlet end is located at the top. The tops of the preheater 21 and the reactor 22 are both equipped with a safety valve 23, a thermocouple 24, and a pressure gauge 25. The temperature, pressure, and flow rate are dynamically adjusted by setting PID control, and remote monitoring and data traceability are achieved through the integration of the SCADA system. The inner wall of the reactor 22 is polished (Ra ≤ 0.4 μm) to reduce scaling. In addition, online cleaning can be used, and acid / alkali solution is periodically injected to dissolve sediments, effectively preventing blockage and scaling.

[0040] The outlet of the two-stage pressurizing piston 13 is connected to the inlet of the preheater 21 through a pipeline. The outlet of most reactors 22 is connected to the inlet of the dual-channel 32. Because the reaction medium contains acidic / alkaline substances, or because biomass hydrolyzes at high temperatures to produce organic acids such as formic acid, acetic acid, and levulinic acid, the pressure-bearing components of reactors 22 are made of corrosion-resistant 316L stainless steel. This material is resistant to high pressures and temperatures, with a design pressure resistance of 22 MPa and a temperature resistance of 350°C.

[0041] This solution also provides a continuous hydrothermal carbonization process, which is completed by relying on the above-mentioned continuous hydrothermal carbonization device and includes the following steps: Step 1: The influent water is heat-exchanged with the reaction product and then mixed with the organic waste to form a mixed material. As a reference, the temperature of the influent water after heat exchange is 80-90° C. The mixing ratio of the influent water to the organic waste is 1:3-1:5.

[0042] For reference, the organic waste in this embodiment is crop straw.

[0043] Step 2: Pressurize the mixed material and transport it to the preheater to preheat the mixed material. For reference, the pressurized pressure is 2.5~3.5MPa and the preheating temperature is 120~150℃.

[0044] Step 3: The preheated mixed material is transported to the reactor and heated to complete the hydrothermal reaction to obtain a reaction product; as a reference, the temperature of the hydrothermal reaction is 200-240°C, and the reaction residence time is 45-90 minutes.

[0045] During this stage, the waste organic matter will undergo the following three changes: (1) Hydrolysis stage: In the early stage of the reaction, cellulose / hemicellulose is mainly degraded into monosaccharides; (2) Dehydration / decarboxylation stage: After the above monosaccharides are dehydrated to furfural, a series of reactions occur at high temperature to form an aromatized carbon skeleton; (3) Polycondensation maturity stage: The above aromatized carbon skeleton condenses to form a stable porous structure Step 4: The reaction product is separated into gas, solid and liquid phases after heat exchange with water to obtain gas product, solid product and liquid product.

[0046] Example 2 This embodiment is basically the same as Example 1, except that the organic waste in this embodiment is kitchen waste.

[0047] Example 3 This embodiment is basically the same as Example 1, except that the organic waste in this embodiment is sewage sludge.

[0048] In Comparative Examples 1 to 10, the waste organic matter is all crop straw, and the differences in other process conditions are detailed in Table 1.

[0049] Table 1 Comparison of different parameter controls in Examples 1 to 3 and Comparative Examples 1 to 10

[0050] Experimental Example 1: Effects of different parameter controls on organic waste treatment The inventors tested the hydrothermal carbonization treatment results in Examples 1 to 3 and Comparative Examples 1 to 10 in Table 1 with reference to the test methods in the standard documents in Table 2, specifically including indicators such as equipment failure interval, flow fluctuation rate, hydrothermal carbon moisture content, porosity, heavy metal (Cd) leaching, calorific value and energy saving rate. The test results are recorded in Table 3.

[0051] Table 2 Test reference standards

[0052] Table 3 Test results

[0053] Experimental data show that this scheme effectively improves the processing continuity of the scheme (equipment failure interval is greater than 25 days) by combining and optimizing the continuous hydrothermal carbonization device and the continuous hydrothermal carbonization process, and effectively saves energy consumption by about 20%. The quality of the prepared hydrothermal carbon is also good.

[0054] During the research and development process, the inventors discovered that if the preheating temperature is too high (Comparative Example 5), premature carbonization in the preheating section can lead to scaling in the pipes, resulting in large flow rate fluctuations and a significant reduction in calorific value. If the preheating temperature is too low (as in Comparative Example 6), insufficient hydrolysis can significantly increase the water content in the hydrochar (the water content in Comparative Example 8 is 16.5%, a 94% increase compared to 8.5% in Example 1). If the reaction temperature is too high (as in Comparative Example 7), organic matter decomposition can lead to elevated liquid COD, reducing the calorific value and significantly increasing heavy metal dissolution. If the reaction temperature is too low (as in Comparative Example 8), incomplete carbonization can increase the water content. If the residence time is too short (as in Comparative Example 9), incomplete polycondensation can increase the porosity of the hydrochar, leading to ineffective adsorption. If the residence time is too long (as in Comparative Example 10), micropore collapse can reduce the calorific value.

[0055] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A continuous hydrothermal carbonization device, characterized in that: It includes a feeding unit, a reaction unit, and a separation unit. The feeding unit includes a feeding bin, a mixer, and a pressurizing component connected in sequence. The pressurizing component is connected to the inlet of the reaction unit. The pressurizing component includes two-stage pressurizing pistons connected in parallel. The separation unit includes a cooling and decompression component and a product filter separator connected in sequence. The cooling and decompression component is connected to the outlet of the reaction unit. The cooling and decompression component includes two parallel channels. The two channels are connected with a heat exchanger. The heat exchanger is connected with a water inlet pipe. The outlet of the water inlet pipe is connected to the feeding bin.

2. A continuous hydrothermal carbonization device according to claim 1, characterized in that: A stirrer is provided in the mixer.

3. A continuous hydrothermal carbonization device according to claim 2, characterized in that: The reaction unit includes a preheater and a reactor connected in sequence, both of which are tubular reactors with external jacket heating; the outlet end of the two-stage pressurizing piston is connected to the inlet end pipeline of the preheater, and the outlet end of most reactors is connected to the inlet end of the dual channel.

4. A continuous hydrothermal carbonization device according to claim 3, characterized in that: The inlet end of the preheater and the reactor is located at the bottom, and the outlet end is located at the top.

5. The continuous hydrothermal carbonization device according to claim 4, characterized in that: The tops of the preheater and the reactor are both equipped with safety valves, thermocouples and pressure gauges.

6. A continuous hydrothermal carbonization process, characterized in that: The continuous hydrothermal carbonization device according to any one of claims 1 to 5 is completed, comprising the following steps: Step 1: The incoming water exchanges heat with the reaction product and then mixes with the organic waste to form a mixed material; Step 2: Pressurize the mixed material and convey it to the preheater to preheat the mixed material; Step 3: transporting the preheated mixed material to the reactor, heating it to complete the hydrothermal reaction, and obtaining a reaction product; Step 4: The reaction product is separated into gas, solid and liquid phases after heat exchange with water to obtain gas product, solid product and liquid product.

7. The continuous hydrothermal carbonization device according to claim 6, characterized in that: In step 1, the temperature of the influent after heat exchange is 80-90° C.; the mixing ratio of the influent and the organic waste is 1:3-1:

5.

8. The continuous hydrothermal carbonization device according to claim 7, characterized in that: In step 2, the pressurized pressure is 2.5-3.5 MPa.

9. The continuous hydrothermal carbonization device according to claim 8, characterized in that: In step 2, the preheating temperature is 120-150°C.

10. The continuous hydrothermal carbonization device according to claim 9, characterized in that: In step 3, the temperature of the hydrothermal reaction is 200-240° C., and the reaction residence time is 45-90 min.

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