Supercritical hydrothermal synthesis nano tin oxide system and safety control method thereof

Abstract

The invention discloses a supercritical hydrothermal synthesis nano tin oxide system and a safety control method thereof, and belongs to the technical field of supercritical hydrothermal synthesis. The invention provides a supercritical hydrothermal synthesis nano tin oxide system which comprises a material conveying unit, a mixed reaction unit, a temperature and pressure reduction unit, a product post-treatment unit, a wastewater storage tank unit, an accident water tank unit and a safety valve assembly which are connected in sequence, an inlet of the accident water tank unit is respectively connected with outlets of the material conveying unit, the mixed reaction unit and the cooling and depressurizing unit through a safety valve assembly, so that a pressure regulation and control system for the supercritical hydrothermal synthesis nano tin oxide system is formed; the pressure change of the system is responded in real time through interlocking of the safety valve assembly and the accident water tank unit, the pressure of the supercritical hydrothermal synthesis system is accurately controlled, and a stable reaction environment is provided for nucleation, crystallization and growth of nano tin oxide, so that the quality and stability of a nano tin oxide product are improved.

Description

Technical Field

[0001] This invention relates to the field of supercritical hydrothermal synthesis technology, specifically to a supercritical hydrothermal synthesis system for nano-tin oxide and its safety control method. Background Technology

[0002] As a new generation of high-efficiency energy storage devices, the performance of the negative electrode material in lithium-ion batteries directly affects the battery's energy density and cycle life. Among many negative electrode materials, nano-tin oxide (… Not only does it have a theoretical specific capacity far exceeding that of carbon materials, but it also boasts advantages such as simple synthesis process, excellent safety performance, and low raw material cost. Therefore, it is regarded as a next-generation lithium-ion battery anode material with great commercial prospects. Its performance optimization and preparation technology innovation are of great significance to promoting the upgrading of the lithium-ion battery industry.

[0003] Traditional methods for preparing nano-tin oxide mainly include hydrothermal / solvothermal methods, electrodeposition, electrospinning, chemical vapor deposition, and template methods. However, these methods generally have limitations: First, they have low reaction efficiency, with most methods involving long reaction times and preparation cycles, making it difficult to meet the needs of large-scale production; second, they suffer from significant process complexity and cost issues, with some methods having stringent equipment requirements (such as chemical vapor deposition) and cumbersome process steps, resulting in high production costs; third, product control is difficult, with template methods easily damaging the microstructure of nanomaterials when removing organic solvents or templates, and existing methods cannot simultaneously achieve high production efficiency, low energy consumption, and precise control over product particle size and morphology; fourth, they are not environmentally friendly, with some methods relying on organic solvents, posing a pollution risk.

[0004] Currently, supercritical hydrothermal synthesis is an efficient and green method for preparing nano-tin oxide. The principle involves using water or an organic solvent during the reaction process, where the reactants undergo rapid nucleation, crystallization, and growth in supercritical water to synthesize nano-tin oxide powder. However, the existing technology still faces a key bottleneck: insufficient pressure control precision in the reaction system leads to excessive pressure fluctuations during production. This pressure instability directly results in uneven particle size distribution and poor morphological consistency in the nano-tin oxide product, severely affecting its quality and stability.

[0005] Therefore, how to achieve precise control of the pressure in the supercritical hydrothermal synthesis system in order to improve the quality and stability of nano-tin oxide products has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a supercritical hydrothermal synthesis system for nano-tin oxide and its safety control method, so as to overcome the problem of poor stability of nano-tin oxide products due to insufficient pressure control precision in the supercritical hydrothermal synthesis process in the prior art.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: A supercritical hydrothermal synthesis system for nano-tin oxide, comprising: A material conveying unit, the outlet of which is connected to a mixing reaction unit, is used to convey materials required for the supercritical hydrothermal synthesis reaction, the materials including pure water, precursors and additives; A mixing reaction unit, the outlet of which is connected to a cooling and depressurization unit, is used to carry out a supercritical hydrothermal synthesis reaction; The cooling and depressurization unit is connected to the product post-processing unit at its outlet, and is used to cool and depressurize the fluid after the supercritical hydrothermal synthesis reaction. The product post-processing unit, whose outlet is connected to the wastewater storage tank unit, is used to separate, purify, dope and coat the nano tin oxide product. The wastewater storage tank unit has its inlet connected to the outlets of the mixing reaction unit and the cooling and depressurization unit, respectively, and is used to store the wastewater generated by the supercritical hydrothermal synthesis reaction. The emergency water tank unit and the safety valve assembly are provided. The inlet of the emergency water tank unit is connected to the outlet of the material conveying unit, the mixing reaction unit and the cooling and depressurization unit via the safety valve assembly. The system is used to achieve safe control of the pressure of the supercritical hydrothermal synthesis of nano-tin oxide system by storing the fluid that triggers the safety valve assembly and cooling the high-temperature fluid.

[0008] A further improvement of the present invention is that the material conveying unit includes a pure water storage tank, a precursor storage tank, an additive storage tank, a first high-pressure metering pump, a second high-pressure metering pump, a third high-pressure metering pump, a first damper, a second damper, a third damper, a first safety valve, a second safety valve, and a third safety valve. The outlet of the pure water storage tank is connected to the inlet of the emergency water tank unit via a first high-pressure metering pump, a first damper, and a first safety valve. The outlet of the precursor storage tank is connected to the inlet of the emergency water tank unit via a second high-pressure metering pump, a second damper, and a second safety valve. The outlet of the additive storage tank is connected to the inlet of the emergency water tank unit via a third high-pressure metering pump, a third damper, and a third safety valve.

[0009] A further improvement of the present invention is that the material conveying unit further includes a first pressure sensor, a second pressure sensor, and a third pressure sensor. The first pressure sensor is disposed on the first high-pressure metering pump and is used to measure the motor pressure of the first high-pressure metering pump; the second pressure sensor is disposed on the second high-pressure metering pump and is used to measure the motor pressure of the second high-pressure metering pump; and the third pressure sensor is disposed on the third high-pressure metering pump and is used to measure the motor pressure of the third high-pressure metering pump.

[0010] A further improvement of the present invention is that the mixing reaction unit includes a heater, a mixer, and a reactor; The first outlet of the cooling and depressurization unit is connected to the inlet of the heater, the outlet of the heater is connected to the first inlet of the mixer, the second high-pressure metering pump is connected to the second inlet of the mixer, the third high-pressure metering pump is connected to the third inlet of the mixer, and the outlet of the mixer is connected to the reactor.

[0011] A further improvement of the present invention is that the mixing reaction unit further includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a first pressure gauge, a second pressure gauge, a ninth safety valve, a fourth pressure sensor, and a fifth pressure sensor. The first temperature sensor is installed on the heater; the second and third temperature sensors are installed at the inlet and outlet of the reactor, respectively; the first and second pressure gauges are installed at the inlet and outlet of the mixer, respectively; the ninth safety valve is installed at the inlet of the reactor; and the fourth and fifth pressure sensors are installed at the outlet of the reactor in sequence.

[0012] A further improvement of the present invention is that the cooling and depressurization unit includes a quench cooler and a depressurizer; The reactor outlet is connected to the pressure reducing device inlet via a quench cooler; The reactor inlet, reactor outlet, quench cooler outlet, and pressure reducer outlet are all connected to the inlet of the emergency storage tank unit.

[0013] A further improvement of the present invention is that the cooling and depressurization unit further includes a first temperature display, a third pressure gauge, a sixteenth safety valve, a second temperature display, a twenty-first safety valve, and a fourth pressure gauge; The first temperature display, the third pressure gauge, and the sixteenth safety valve are all located at the outlet of the quench cooler, while the second temperature display, the twenty-first safety valve, and the fourth pressure gauge are all located at the outlet of the pressure reducer.

[0014] A further improvement of the present invention is that it also includes a first electrically controlled pressure valve, a second electrically controlled pressure valve, a manually controlled pressure valve, and a fifth pressure gauge; The pressure reducer outlet is divided into three paths: the first path is connected to the product post-processing unit via the first electric pressure control valve; the second path is connected to the product post-processing unit via the second electric pressure control valve; the third path is connected to the product post-processing unit via the manual pressure control valve; and the fifth pressure gauge is installed at the inlet of the product post-processing unit.

[0015] A further improvement of the present invention is that the inlet and outlet of the reactor, quencher, and pressure reducer are all connected to the inlet of the wastewater storage tank unit.

[0016] This invention also provides a safety control method for the supercritical hydrothermal synthesis of nano-tin oxide system as described above, comprising: conveying pure water, precursors, and additives to a mixing reaction unit via a material conveying unit to carry out a supercritical hydrothermal synthesis reaction, obtaining a high-temperature and high-pressure nano-tin oxide suspension; after cooling and depressurizing by a cooling and depressurizing unit, obtaining a room-temperature and atmospheric-pressure nano-tin oxide suspension; storing the wastewater generated by the supercritical hydrothermal synthesis reaction in a wastewater storage tank unit; and conveying the room-temperature and atmospheric-pressure nano-tin oxide suspension to a product post-processing unit for separation, cleaning, and drying to synthesize nano-tin oxide powder. When the pressure of the supercritical hydrothermal synthesis system for nano-tin oxide reaches the set upper limit pressure, the safety valve assemblies corresponding to the outlets of the material conveying unit, mixing reaction unit, and cooling and depressurization unit will activate to release pressure, and the fluid will enter the emergency water tank unit. If the fluid is at room temperature, the cooling water in the emergency water tank unit will not cool the fluid; if the fluid is at high temperature, the cooling water in the emergency water tank unit will cool the fluid, and the cooled fluid will be stored in the emergency water tank unit.

[0017] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The supercritical hydrothermal synthesis system for nano-tin oxide provided by this invention includes a material conveying unit, a mixing reaction unit, a cooling and depressurization unit, a product post-processing unit, a wastewater storage tank unit, an emergency water tank unit, and a safety valve assembly connected in sequence. The inlet of the emergency water tank unit is connected to the outlets of the material conveying unit, the mixing reaction unit, and the cooling and depressurization unit via the safety valve assembly, forming a pressure control system for the supercritical hydrothermal synthesis of nano-tin oxide. Through the interlocking of the safety valve assembly and the emergency water tank unit, the system responds in real time to pressure changes, precisely controlling the pressure of the supercritical hydrothermal synthesis system and providing a stable reaction environment for the nucleation, crystallization, and growth of nano-tin oxide, thereby improving the quality and stability of the nano-tin oxide product.

[0018] Furthermore, a damper is installed after the high-pressure metering pump to stabilize the reaction pressure; a pressure sensor is installed on the high-pressure metering pump to interlock with the motor of the high-pressure metering pump. When the pressure of the high-pressure metering pump exceeds the set value, the motor interlocked with the high-pressure metering pump is regulated by the pressure sensor to further reduce the system pressure.

[0019] Furthermore, safety valves are installed on the reactor, quencher, and pressure reducer to prevent safety hazards in the reaction system caused by blockage.

[0020] Furthermore, temperature sensors are installed on the heater, mixer, and reactor. When the temperature of the mixing reaction unit does not reach the supercritical temperature or the temperature is too high, the average values ​​of the second and third temperature sensors are interlocked with the average value of the first temperature sensor to control the power of the heater, thereby achieving temperature control of the supercritical hydrothermal synthesis of nano-tin oxide system.

[0021] Furthermore, by installing a manual pressure control valve on the step-down transformer, the risk of the system failing to operate normally due to damage to one of the step-down transformer outlets can be prevented, thereby improving the stability of the system. Attached Figure Description

[0022] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the connection of a supercritical hydrothermal synthesis system for nano-tin oxide according to the present invention; Among them, 1-pure water storage tank; 2-precursor storage tank; 3-additive storage tank; 4-first high-pressure metering pump; 5-second high-pressure metering pump; 6-third high-pressure metering pump; 7-first damper; 8-second damper; 9-third damper; 10-heater; 11-mixer; 12-reactor; 13-quench cooler; 14-pressure reducer; 15-product post-processing unit; 16-wastewater storage tank unit; 17-emergency water tank unit; V1-first safety valve; V2-second safety valve; V3-third safety valve; V9-ninth safety valve; V16-sixteenth safety valve; V21-twenty-first safety valve; V26-then... One electrically controlled pressure valve; V27 - Second electrically controlled pressure valve; V28 - Manually controlled pressure valve; TIC1 - First temperature sensor; TIC2 - Second temperature sensor; TIC3 - Third temperature sensor; TI1 - First temperature display; TI2 - Second temperature display; PIC1 - First pressure sensor; PIC2 - Second pressure sensor; PIC3 - Third pressure sensor; PIC4 - Fourth pressure sensor; PIC5 - Fifth pressure sensor; PI1 - First pressure gauge; PI2 - Second pressure gauge; PI3 - Third pressure gauge; PI4 - Fourth pressure gauge; PI5 - Fifth pressure gauge. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and 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, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This is an explanation of the present invention and not a limitation thereof.

[0030] A supercritical hydrothermal synthesis system for nano-tin oxide, comprising: A material conveying unit, the outlet of which is connected to a mixing reaction unit, is used to convey materials required for the supercritical hydrothermal synthesis reaction, the materials including pure water, precursors and additives; A mixing reaction unit, the outlet of which is connected to a cooling and depressurization unit, is used to carry out a supercritical hydrothermal synthesis reaction; The cooling and depressurization unit is connected to the product post-processing unit 15 at its outlet, and is used to cool and depressurize the fluid after the supercritical hydrothermal synthesis reaction. Product post-processing unit 15, the outlet of which is connected to wastewater storage tank unit 16, is used to separate, clean and dry the cooled and depressurized fluid to synthesize nano tin oxide powder. Wastewater storage tank unit 16, the inlet of which is connected to the outlet of the mixing reaction unit and the cooling and depressurization unit respectively, is used to store wastewater generated by the supercritical hydrothermal synthesis reaction; The emergency water tank unit 17 and the safety valve assembly are provided. The inlet of the emergency water tank unit 17 is connected to the outlet of the material conveying unit, the mixing reaction unit and the cooling and depressurization unit via the safety valve assembly. The system is used to achieve safe control of the pressure of the supercritical hydrothermal synthesis of nano-tin oxide system by storing the fluid that triggers the safety valve assembly and cooling the high-temperature fluid.

[0031] Specifically, the material conveying unit includes a pure water storage tank 1, a precursor storage tank 2, an additive storage tank 3, a first high-pressure metering pump 4, a second high-pressure metering pump 5, a third high-pressure metering pump 6, a first damper 7, a second damper 8, a third damper 9, a first safety valve V1, a second safety valve V2, and a third safety valve V3. The outlet of pure water storage tank 1 is connected to the inlet of emergency water tank unit 17 via the first high-pressure metering pump 4, the first damper 7, and the first safety valve V1. The outlet of precursor storage tank 2 is connected to the inlet of emergency water tank unit 17 via the second high-pressure metering pump 5, the second damper 8, and the second safety valve V2. The outlet of additive storage tank 3 is connected to the inlet of emergency water tank unit 17 via the third high-pressure metering pump 6, the third damper 9, and the third safety valve V3.

[0032] Specifically, the material conveying unit further includes a first pressure sensor PIC1, a second pressure sensor PIC2, ​​and a third pressure sensor PIC3. The first pressure sensor PIC1 is installed on the first high-pressure metering pump 4 and is used to measure the motor pressure of the first high-pressure metering pump 4. The second pressure sensor PIC2 is installed on the second high-pressure metering pump 5 and is used to measure the motor pressure of the second high-pressure metering pump 5. The third pressure sensor PIC3 is installed on the third high-pressure metering pump 6 and is used to measure the motor pressure of the third high-pressure metering pump 6.

[0033] Specifically, the mixing reaction unit includes a heater 10, a mixer 11, and a reactor 12; The first outlet of the cooling and depressurization unit is connected to the inlet of the heater 10, the outlet of the heater 10 is connected to the first inlet of the mixer 11, the second high-pressure metering pump 5 is connected to the second inlet of the mixer 11, the third high-pressure metering pump 6 is connected to the third inlet of the mixer 11, and the outlet of the mixer 11 is connected to the reactor 12.

[0034] Specifically, the mixing reaction unit also includes a first temperature sensor TIC1, a second temperature sensor TIC2, a third temperature sensor TIC3, a first pressure gauge PI1, a second pressure gauge PI2, a ninth safety valve V9, a fourth pressure sensor PIC4, and a fifth pressure sensor PIC5. The first temperature sensor TIC1 is installed on the heater 10; the second temperature sensor TIC2 and the third temperature sensor TIC3 are installed at the inlet and outlet of the reactor 12, respectively; the first pressure gauge PI1 and the second pressure gauge PI2 are installed at the inlet and outlet of the mixer 11, respectively; the ninth safety valve V9 is installed at the inlet of the reactor 12; and the fourth pressure sensor PIC4 and the fifth pressure sensor PIC5 are installed sequentially at the outlet of the reactor 12.

[0035] Specifically, the cooling and depressurization unit includes a quench cooler 13 and a depressurizer 14; The outlet of reactor 12 is connected to the inlet of pressure reducer 14 via quench cooler 13; The inlet of reactor 12, the outlet of reactor 12, the outlet of quencher 13, and the outlet of pressure reducer 14 are all connected to the inlet of the emergency storage tank unit.

[0036] Specifically, the cooling and depressurization unit also includes a first temperature display TI1, a third pressure gauge PI3, a sixteenth safety valve V16, a second temperature display TI2, a twenty-first safety valve V21, and a fourth pressure gauge PI4. The first temperature display TI1, the third pressure gauge PI3, and the sixteenth safety valve V16 are all located at the outlet of the quench cooler 13, while the second temperature display TI2, the twenty-first safety valve V21, and the fourth pressure gauge PI4 are all located at the outlet of the pressure reducer 14.

[0037] Specifically, it also includes the first electric pressure control valve V26, the second electric pressure control valve V27, the manual pressure control valve V28, and the fifth pressure gauge PI5; The outlet of the pressure reducer 14 is divided into three paths: the first path is connected to the product post-processing unit 15 via the first electric pressure control valve V26; the second path is connected to the product post-processing unit 15 via the second electric pressure control valve V27; and the third path is connected to the product post-processing unit 15 via the manual pressure control valve V28. The fifth pressure gauge PI5 is installed at the inlet of the product post-processing unit 15.

[0038] Specifically, the inlet and outlet of reactor 12, quencher 13 and pressure reducer 14 are all connected to the inlet of wastewater storage tank unit 16.

[0039] Based on the same inventive concept, this invention also provides a safety control method for the supercritical hydrothermal synthesis of nano-tin oxide system as described above, comprising: Pure water, precursors, and additives are transported to the mixing reaction unit via a material conveying unit for supercritical hydrothermal synthesis to obtain a high-temperature and high-pressure nano-tin oxide suspension. After cooling and depressurization by a cooling and depressurization unit, a room-temperature and atmospheric-pressure nano-tin oxide suspension is obtained. The wastewater generated by the supercritical hydrothermal synthesis reaction is stored in the wastewater storage tank unit 16. The room-temperature and atmospheric-pressure nano-tin oxide suspension is transported to the product post-processing unit 15 for separation, cleaning, and drying to synthesize nano-tin oxide powder. When the pressure of the supercritical hydrothermal synthesis of nano-tin oxide system reaches the set upper limit pressure, the safety valve components corresponding to the outlets of the material conveying unit, mixing reaction unit, and cooling and depressurization unit will activate to release pressure, and the fluid will enter the emergency water tank unit 17. If the fluid is at room temperature, the cooling water in the emergency water tank unit 17 will not cool the fluid; if the fluid is at high temperature, the cooling water in the emergency water tank unit 17 will cool the fluid, and the cooled fluid will be stored in the emergency water tank unit 17.

[0040] Example 1 See Figure 1 A supercritical hydrothermal synthesis system for nano-tin oxide includes a material conveying unit, a mixing reaction unit, a cooling and depressurization unit, a product post-processing unit, a wastewater storage tank unit, and an emergency water tank unit. The material conveying unit includes a pure water storage tank 1, a precursor storage tank 2, an additive storage tank 3, a high-pressure metering pump, and a damper. The pure water storage tank 1 is connected to the inlet of the first high-pressure metering pump 4, the precursor storage tank 2 is connected to the inlet of the second high-pressure metering pump 5, the additive storage tank 3 is connected to the inlet of the third high-pressure metering pump 6, the outlets of the second high-pressure metering pump 5 and the third high-pressure metering pump 6 are connected to the mixing reaction unit, and the outlets of the first high-pressure metering pump 4, the second high-pressure metering pump 5, and the third high-pressure metering pump 6 are respectively connected to the first damper 7, the second damper 8, and the third damper 9. A first pressure sensor PIC1, a second pressure sensor PIC2, ​​and a third pressure sensor PIC3 are respectively installed at the outlets of the first high-pressure metering pump 4, the second high-pressure metering pump 5, and the third high-pressure metering pump 6. The mixing reaction unit includes a heater 10, a mixer 11, and a reactor 12. The outlet of the heater 10, the outlet of the second high-pressure metering pump 5, and the outlet of the third high-pressure metering pump 6 are respectively connected to the mixer 11. The outlet of the mixer 11 is connected to the inlet of the reactor 12. A first temperature sensor TIC1 is installed at the heater 10. A first pressure gauge PI1 is installed at the outlet of the heater 10. A second pressure gauge PI2, a second temperature sensor TIC2, and a safety valve V9 are installed at the outlet of the mixer 11. A safety valve V12, a third temperature sensor TIC3, a fourth pressure sensor PIC4, and a fifth pressure sensor PIC5 are installed at the outlet of the reactor 12. The cooling and depressurization unit includes a quench cooler 13 and a depressurizer 14. A first temperature display TI1 and a third pressure gauge PI3 are installed at the outlet of the quench cooler 13. A second temperature display TI2, a fourth pressure gauge PI4, and a twenty-first safety valve V21 are installed at the outlet of the depressurizer 14. A first electrically controlled pressure valve V26, a second electrically controlled pressure valve V27, and a manually controlled pressure valve V28 are installed between the product post-processing unit 15 and the depressurizer 14. The wastewater storage tank unit 16 is connected to the inlet and outlet of the reactor 12, the quench cooler 13, and the depressurizer 14, respectively. The wastewater storage tank unit 16 is also connected to the outlet of the product post-processing unit 15. The emergency water tank unit 17 is connected to the first high-pressure metering pump 4, the second high-pressure metering pump 5, the third high-pressure metering pump 6, the reactor 12, the quench cooler 13, and the safety valve of the depressurizer 14, respectively.

[0041] Wastewater storage tank unit 16 is connected to the inlet and outlet of reactor 12, quench cooler 13 and pressure reducer 14 respectively. The purpose of setting up forward and reverse flushing is to store the wastewater from the forward and backwashing of reactor 12, quench cooler 13 and pressure reducer 14 to prevent system blockage.

[0042] When the temperature at the reaction unit does not reach the supercritical temperature or is too high, the average values ​​of the second temperature sensor TIC2 and the third temperature sensor TIC3 are interlocked with the average value of the first temperature sensor TIC1 to control the power of the heater 10 and achieve system temperature control. The motors of the first high-pressure metering pump 4, the second high-pressure metering pump 5, and the third high-pressure metering pump 6 are interlocked with the first pressure sensor PIC1, the second pressure sensor PIC2, ​​and the third pressure sensor PIC3, respectively. A fourth pressure sensor PIC4 and a fifth pressure sensor PIC5 are installed after the reactor 12, which are respectively connected to the first electrically controlled valve V26 and the second electrically controlled pressure valve. V27 is used for interlock control; a first electric pressure control valve V26, a second electric pressure control valve V27, and a manual pressure control valve V28 are installed between the product post-processing unit 15 and the pressure reducer 14, with a spare pressure control valve connected in parallel; the inlet of the emergency water tank unit 17 is connected to the safety valves of the first high-pressure metering pump 4, the second high-pressure metering pump 5, the third high-pressure metering pump 6, the reactor 12, the quench cooler 13, and the pressure reducer 14 for interlock control; a first temperature display TI1 and a third pressure gauge PI3 are installed at the outlet of the quench cooler 13, and a second temperature display TI2, a fourth pressure gauge PI4, and a twenty-first safety valve V21 are installed at the outlet of the pressure reducer 14.

[0043] Preferably, the structure of the quencher 13 is not limited to the form of a shell-and-tube type, finned type or spiral plate type, etc., and can increase the heat exchange area and improve the preheating temperature of pure water.

[0044] Preferably, the heater 10 is not limited to the form of a resistance heater, an infrared heater, or an electromagnetic induction heater.

[0045] Preferably, the mixer 11 is not limited to the form of a sleeve-type countercurrent mixer, a T-type three-way mixer, or a cross-type jet mixer.

[0046] Preferably, the step-down transformer 11 is in the form of a capillary structure. The method for synthesizing nano-tin oxide using the above-mentioned supercritical hydrothermal synthesis system is as follows: Sodium stannate trihydrate and urea are added to precursor storage tank 2 and additive storage tank 3 respectively to prepare solutions. Pure water from the pure water storage tank is pressurized by the first high-pressure metering pump 4, and after heat exchange in the quencher 13, it enters the heater 10. The sodium stannate trihydrate solution is pressurized by the second high-pressure metering pump 5 and enters the mixer 11. The urea solution is pressurized by the third high-pressure metering pump 6 and enters the mixer 11. The above reaction raw materials are mixed in the mixer 11, and then sequentially passed through the reactor 12, quencher 13, and depressurizer 14 to obtain a nano-tin oxide suspension. The synthesized nano-tin oxide suspension is cooled and depressurized by the quencher 13 and depressurizer 14, and then further depressurized by the first electric pressure control valve V26, the second electric pressure control valve V27, or the manual pressure control valve V28 to reduce the pressure to room temperature and pressure. Then it enters the product post-processing unit for separation, cleaning, and drying to synthesize nano-tin oxide powder.

[0047] Safety control methods for supercritical hydrothermal synthesis of nano-tin oxide systems include: The motors of the first high-pressure metering pump 4, the second high-pressure metering pump 5, and the third high-pressure metering pump 6 are interlocked with the first pressure sensor PIC1, the second pressure sensor PIC2, ​​and the third pressure sensor PIC3, respectively. When the pressure of the high-pressure metering pump is too high, the corresponding pressure sensor will regulate the motor of the corresponding high-pressure metering pump to reduce the pressure. An electric pressure regulating valve is installed after the pressure reducer 14 and interlocked with the pressure gauge after the reactor 12 to control the system pressure. When the temperature of heater 10 does not reach the supercritical temperature, the average values ​​of the second temperature sensor TIC2 and the third temperature sensor TIC3 are interlocked with the average value of the first temperature sensor TIC1 to control the power of the heater and achieve control of the system temperature. The inlet of the emergency water tank unit 17 is connected to the safety valves of the first high-pressure metering pump 4, the second high-pressure metering pump 5, the third high-pressure metering pump 6, the reactor 12, the quench cooler 13, and the pressure reducer 14 for interlock control. When one or more of the first high-pressure metering pump 4, the second high-pressure metering pump 5, the third high-pressure metering pump 6, the reactor 12, the quench cooler 13, and the pressure reducer 14 are overpressurized, the safety valve opens to release pressure, and the leaked fluid enters the emergency water tank unit.

[0048] A fourth pressure sensor PIC4 and a fifth pressure sensor PIC5 are installed downstream of reactor 12. They are interlocked with electrically controlled valve V26 and the second electrically controlled pressure valve V27, respectively. When the pressure at the reactor position is higher or lower than the reaction pressure, the fourth pressure sensor PIC4 and the fifth pressure sensor PIC5 will transmit current signals to the electrically controlled valve V26 and the second electrically controlled pressure valve V27, respectively. The electrically controlled valve V26 or the second electrically controlled pressure valve V27 will reduce or increase the pressure to ensure the production stability and reliability of the system.

[0049] Wastewater storage tank unit 16 is connected to the inlet and outlet of reactor 12, quench cooler 13 and pressure reducer 14 respectively. The purpose of setting up forward and reverse flushing is to store the wastewater from the forward and backwashing of reactor 12, quench cooler 13 and pressure reducer 14 to prevent system blockage.

[0050] The supercritical hydrothermal synthesis system for nano-tin oxide provided in this embodiment includes a material conveying unit, a mixing and reaction unit, a cooling and depressurization unit, a product post-processing unit, a wastewater storage tank unit, and an emergency water tank unit. Through the safety control method of the supercritical hydrothermal synthesis system for nano-tin oxide, over-temperature control, over-pressure control, and anti-blockage control of the system can be achieved, realizing the safe and reliable operation of the supercritical hydrothermal synthesis system for nano-tin oxide, laying the foundation for the industrialization of supercritical hydrothermal synthesis technology.

[0051] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of this invention. Their purpose is to clearly illustrate the concept, principle, and application of this invention through specific examples, and is by no means intended to limit the scope of protection of this invention to these specific embodiments. In fact, the true value of this invention lies in its proposed technical ideas and innovations, rather than its manifestations or implementation methods.

[0052] For those skilled in the art, after thoroughly reading and understanding the technical solution of this invention, they are fully capable of making various changes, modifications, or equivalent substitutions to the specific implementation of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the range of technical parameters, optimizing the algorithm flow to improve efficiency, and replacing some technical components to achieve better compatibility or reduce costs. As long as these modified technical solutions substantially retain the technical features claimed by the original invention, that is, they can still achieve the core functions and effects of this invention, then these changes should be considered to fall within the scope of protection of the pending claims of this invention.

[0053] Furthermore, with the continuous progress and development of technology, new technical means and methods are constantly emerging, which provides ample space for further improvement and perfection of this invention. Therefore, the scope of protection of this invention should also include reasonable and foresightful improvements and extensions based on existing technology. As long as these improvements and extensions do not depart from the basic principles and core concepts of this invention, they should be considered equivalents of this invention and are equally protected by patent rights.

Claims

1. A supercritical hydrothermal synthesis system for nano-tin oxide, characterized in that, include: A material conveying unit, the outlet of which is connected to a mixing reaction unit, is used to convey materials required for the supercritical hydrothermal synthesis reaction, the materials including pure water, precursors and additives; A mixing reaction unit, the outlet of which is connected to a cooling and depressurization unit, is used to carry out a supercritical hydrothermal synthesis reaction; The cooling and depressurization unit is connected to the product post-processing unit (15) at its outlet, and is used to cool and depressurize the fluid after the supercritical hydrothermal synthesis reaction. The product post-processing unit (15) is connected to the wastewater storage tank unit (16) at its outlet. It is used to separate, clean and dry the fluid after cooling and depressurization to synthesize nano-tin oxide powder. Wastewater storage tank unit (16), the inlet of which is connected to the outlet of the mixing reaction unit and the cooling and depressurization unit respectively, for storing wastewater generated by supercritical hydrothermal synthesis reaction; The emergency water tank unit (17) and the safety valve assembly are provided. The inlet of the emergency water tank unit (17) is connected to the outlet of the material conveying unit, the mixing reaction unit and the cooling and depressurization unit via the safety valve assembly. The system is used to achieve safe control of the pressure of the supercritical hydrothermal synthesis nano tin oxide system by storing the fluid that triggers the safety valve assembly and cooling the high-temperature fluid.

2. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 1, characterized in that, The material conveying unit includes a pure water storage tank (1), a precursor storage tank (2), an additive storage tank (3), a first high-pressure metering pump (4), a second high-pressure metering pump (5), a third high-pressure metering pump (6), a first damper (7), a second damper (8), a third damper (9), a first safety valve (V1), a second safety valve (V2), and a third safety valve (V3). The outlet of the pure water storage tank (1) is connected to the inlet of the emergency water tank unit (17) via the first high-pressure metering pump (4), the first damper (7), and the first safety valve (V1). The outlet of the precursor storage tank (2) is connected to the inlet of the emergency water tank unit (17) via the second high-pressure metering pump (5), the second damper (8), and the second safety valve (V2). The outlet of the additive storage tank (3) is connected to the inlet of the emergency water tank unit (17) via the third high-pressure metering pump (6), the third damper (9), and the third safety valve (V3).

3. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 2, characterized in that, The material conveying unit also includes a first pressure sensor (PIC1), a second pressure sensor (PIC2), and a third pressure sensor (PIC3). The first pressure sensor (PIC1) is installed on the first high-pressure metering pump (4) and is used to measure the motor pressure of the first high-pressure metering pump (4). The second pressure sensor (PIC2) is installed on the second high-pressure metering pump (5) and is used to measure the motor pressure of the second high-pressure metering pump (5). The third pressure sensor (PIC3) is installed on the third high-pressure metering pump (6) and is used to measure the motor pressure of the third high-pressure metering pump (6).

4. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 2, characterized in that, The mixing reaction unit includes a heater (10), a mixer (11), and a reactor (12). The first outlet of the cooling and depressurization unit is connected to the inlet of the heater (10), the outlet of the heater (10) is connected to the first inlet of the mixer (11), the second high-pressure metering pump (5) is connected to the second inlet of the mixer (11), the third high-pressure metering pump (6) is connected to the third inlet of the mixer (11), and the outlet of the mixer (11) is connected to the reactor (12).

5. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 4, characterized in that, The mixing reaction unit also includes a first temperature sensor (TIC1), a second temperature sensor (TIC2), a third temperature sensor (TIC3), a first pressure gauge (PI1), a second pressure gauge (PI2), a ninth safety valve (V9), a fourth pressure sensor (PIC4), and a fifth pressure sensor (PIC5). The first temperature sensor (TIC1) is installed on the heater (10); the second temperature sensor (TIC2) and the third temperature sensor (TIC3) are installed at the inlet and outlet of the reactor (12), respectively; the first pressure gauge (PI1) and the second pressure gauge (PI2) are installed at the inlet and outlet of the mixer (11), respectively; the ninth safety valve (V9) is installed at the inlet of the reactor (12); and the fourth pressure sensor (PIC4) and the fifth pressure sensor (PIC5) are installed at the outlet of the reactor (12) in sequence.

6. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 4, characterized in that, The cooling and depressurization unit includes a quench cooler (13) and a depressurizer (14). The outlet of reactor (12) is connected to the inlet of pressure reducer (14) via quench cooler (13); The inlet of reactor (12), the outlet of reactor (12), the outlet of quencher (13) and the outlet of pressure reducer (14) are all connected to the inlet of the emergency storage tank unit.

7. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 6, characterized in that, The cooling and depressurization unit also includes a first temperature display (TI1), a third pressure gauge (PI3), a sixteenth safety valve (V16), a second temperature display (TI2), a twenty-first safety valve (V21), and a fourth pressure gauge (PI4). The first temperature display (TI1), the third pressure gauge (PI3) and the sixteenth safety valve (V16) are all located at the outlet of the quench cooler (13), and the second temperature display (TI2), the twenty-first safety valve (V21) and the fourth pressure gauge (PI4) are all located at the outlet of the pressure reducer (14).

8. The supercritical hydrothermal synthesis system for nano-tin oxide according to claim 6, characterized in that, It also includes a first electrically controlled pressure valve (V26), a second electrically controlled pressure valve (V27), a manually controlled pressure valve (V28), and a fifth pressure gauge (PI5); The outlet of the pressure reducer (14) is divided into three paths: the first path is connected to the product post-processing unit (15) via the first electric pressure control valve (V26); the second path is connected to the product post-processing unit (15) via the second electric pressure control valve (V27); and the third path is connected to the product post-processing unit (15) via the manual pressure control valve (V28). The fifth pressure gauge (PI5) is installed at the inlet of the product post-processing unit (15).

9. A supercritical hydrothermal synthesis system for nano-tin oxide according to claim 6, characterized in that, The inlet and outlet of the reactor (12), quencher (13) and pressure reducer (14) are all connected to the inlet of the wastewater storage tank unit (16).

10. The safety control method for the supercritical hydrothermal synthesis of nano-tin oxide system as described in any one of claims 1 to 9, characterized in that, include: Pure water, precursors and additives are transported to the mixing reaction unit through the material conveying unit for supercritical hydrothermal synthesis reaction to obtain high temperature and high pressure nano tin oxide suspension. After cooling and depressurization by the cooling and depressurization unit, nano tin oxide suspension at room temperature and pressure is obtained. Wastewater generated by supercritical hydrothermal synthesis reaction is stored in wastewater storage tank unit (16). Nano tin oxide suspension at room temperature and pressure is transported to product post-processing unit (15) for separation, cleaning and drying to synthesize nano tin oxide powder. When the pressure of the supercritical hydrothermal synthesis nano-tin oxide system reaches the set upper limit pressure, the safety valve assembly corresponding to the outlet of the material conveying unit, the mixing reaction unit and the cooling and depressurization unit will be activated to release pressure, and the fluid will enter the emergency water tank unit (17). If the fluid is at room temperature, the cooling water in the emergency water tank unit (17) will not cool the fluid; if the fluid is at high temperature, the cooling water in the emergency water tank unit (17) will cool the fluid and store the cooled fluid in the emergency water tank unit (17).

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