System for supercritical hydrothermal synthesis of barium titanate and safe and intelligent regulation and control method

Abstract

The invention discloses a system for supercritical hydrothermal synthesis of barium titanate and a safety and intelligent regulation and control method. The system comprises a raw material supply module, and an outlet of the raw material supply module is connected with a reaction-heat exchange coupling module and an emergency pressure relief module; an outlet of the reaction-heat exchange coupling module is respectively connected with a gradient cooling pressure reduction module and an emergency pressure relief module; the reaction-heat exchange coupling module comprises a mixer I, a heater, a mixer II and a cooling water circulating device; an inlet of the mixer I is connected with an outlet of the raw material supply module; a stop valve group and a temperature sensor group are arranged on the reactor I and the reactor II; outlets of the mixer II and the reactor I are connected to the emergency pressure relief module; the cooling water circulating device is connected with the gradient cooling depressurization module; and an outlet of the gradient cooling depressurization module is respectively connected with the product treatment module and the emergency pressure relief module. The functions of raw material supply, reaction heat exchange, cooling pressure reduction, product separation, emergency pressure relief and the like are divided into independent modules, and interfaces of all the modules are standardized and cooperate with one another.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supercritical hydrothermal synthesis equipment, and particularly relates to a system for synthesizing barium titanate by supercritical hydrothermal method and a safe and intelligent control method. BACKGROUND

[0002] Barium titanate is a key dielectric material for manufacturing high dielectric constant capacitors and multilayer ceramic capacitors (MLCCs), and is also commonly used in PTC thermistors, resonators, ultrasonic sensors and other devices. With the development of electronic products towards miniaturization and high performance, the requirements for particle size, purity and consistency of barium titanate powder are becoming increasingly stringent, and the demand for cost reduction in batch production is also becoming increasingly urgent. These factors drive the continuous improvement of barium titanate material preparation technology.

[0003] Currently, the main preparation methods of barium titanate powder include solid phase synthesis, sol-gel method and hydrothermal method. The solid phase method is simple in process and easy to obtain raw materials, but has the disadvantages of high energy consumption, high reaction temperature, coarse grain, wide particle size distribution, etc. It often needs to be crushed by ball milling to obtain fine powder, which increases the process and the risk of introducing impurities. The sol-gel method can realize uniform mixing at the molecular level, reduce the reaction temperature, and obtain powder with small particle size and uniform chemical composition, but the process flow is complex, the cost of precursor is high, and particle agglomeration is easy to occur during drying and calcination. The dispersion and batch stability of the prepared powder still need to be optimized. The powder prepared by the hydrothermal method usually has the advantages of uniform particle size, good dispersion and accurate stoichiometric ratio, etc. However, the traditional hydrothermal method often uses intermittent reaction, and a single reaction usually takes several hours or even tens of hours, with limited single batch yield. Frequent temperature rising and falling and opening and sampling for cleaning make the production efficiency low, the equipment maintenance work heavy, and the energy consumption high. This batch kettle process is difficult to meet the demand of modern industry for large-scale continuous production of barium titanate powder.

[0004] Supercritical hydrothermal synthesis technology is a green synthesis technology for the preparation of nano-metal powder. When the reaction medium water is in a supercritical state, the dielectric constant and viscosity of water decrease significantly, and the mass transfer capacity improves, which is beneficial to the rapid reaction and crystal nucleus formation of the precursor. Under the supercritical hydrothermal environment, the nucleation and growth process of barium titanate can be completed in a few seconds or even less time, so the supercritical hydrothermal method is considered as a promising process for the efficient preparation of nano-barium titanate powder. At the same time, since water is used as the medium and rapid reaction and separation can be achieved, the supercritical hydrothermal synthesis conforms to the concept of green chemistry and has advantages in environmental friendliness. However, the existing hydrothermal or supercritical hydrothermal synthesis system still has some defects in practical application: the temperature control has a lag, the heating mode is single, the sensor arrangement is limited, which easily leads to uneven particle size or unstable crystal form of the product. Secondly, the pipe blockage, valve failure or heating abnormality under high temperature and high pressure conditions are easy to cause accidents, and the existing device lacks perfect safety protection design. Thirdly, it is still difficult to accurately control the particle size of the product, and there is no timely and efficient cooling means after the reaction is completed.

[0005] In summary, although the existing preparation technology can prepare high-performance powder to a certain extent, it still cannot meet the actual needs in terms of rapid and accurate control of reaction temperature, safe and reliable operation of the system, accurate regulation of product particle size and modular expansion of equipment. Therefore, it is urgent to provide a system for supercritical hydrothermal synthesis of barium titanate and a safety and intelligent control method. SUMMARY

[0006] The purpose of the present application is to provide a system for supercritical hydrothermal synthesis of barium titanate and a safety and intelligent control method to overcome the shortcomings of the prior art.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: In a first aspect, the present application provides a system for supercritical hydrothermal synthesis of barium titanate, comprising a raw material supply module, a reaction-heat exchange coupling module, a gradient cooling and pressure reduction module, an emergency pressure relief module and a product treatment module. The outlet of the raw material supply module is connected to the reaction-heat exchange coupling module and the emergency pressure relief module, respectively. The outlet of the reaction-heat exchange coupling module is connected to the gradient cooling and pressure reduction module and the emergency pressure relief module, respectively. The reaction-heat exchange coupling module comprises a mixer one, a heater, a mixer two and a cooling water circulation device. The inlet of the mixer one is connected to the outlet of the raw material supply module, the outlets of the mixer one and the heater are connected to the inlet of the mixer two, the outlet of the mixer two is connected to the inlet of the reactor one, the reactor two is connected in parallel to the reactor one, and the stop valve group and the temperature sensor group are arranged on the reactor one and the reactor two. The outlet of the mixer two and the reactor one is connected to the emergency pressure relief module. The cooling water circulating device is connected with a fourth high-pressure delivery pump, and the outlet of the fourth high-pressure delivery pump is connected with the gradient cooling pressure-reducing module. The outlet of the gradient cooling pressure-reducing module is connected with the product processing module and the emergency pressure relief module respectively.

[0008] Further, the raw material supply module comprises a titanium precursor storage tank, a barium precursor storage tank and a deionized water storage tank; the outlets of the titanium precursor storage tank, the barium precursor storage tank and the deionized water storage tank are respectively connected with a first high-pressure delivery pump, a second high-pressure delivery pump and a third high-pressure delivery pump; the inlets of the first high-pressure delivery pump, the second high-pressure delivery pump and the third high-pressure delivery pump are respectively provided with a flow meter FIC1, a flow meter FIC2 and a flow meter FIC3; the outlets of the first high-pressure delivery pump, the second high-pressure delivery pump and the third high-pressure delivery pump are respectively provided with a pressure gauge PIC1, a pressure gauge PIC2 and a pressure gauge PIC3, and the outlets of the first high-pressure delivery pump and the second high-pressure delivery pump are connected with the inlet of the mixer one, and the outlet of the third high-pressure delivery pump is connected with the emergency pressure relief module.

[0009] Further, the gradient cooling pressure-reducing module comprises a water spray desuperheater, a quenching heat exchanger, a slow cooling heat exchanger and a pressure reducer connected in sequence; the inlet of the water spray desuperheater is connected with the outlet of the mixer two and the reactor one; the inlet of the quenching heat exchanger is provided with a temperature sensor TIC4 and a pressure gauge PIC5; and the outlet of the quenching heat exchanger is provided with a temperature sensor TIC5 and a pressure gauge PIC6. The pressure reducer is connected with the product processing module, and an electric pressure control valve V13 and an electric pressure control valve V12 are connected in parallel on the pipeline connecting the pressure reducer and the product processing module.

[0010] Further, the product processing module comprises a first-stage centrifugation, a second-stage centrifugation, a third-stage centrifugation, an ultrasonic washing device, a vacuum drying device and a nano barium titanate storage device connected in sequence; the first-stage centrifugation is connected in parallel with a standby centrifugation, and the outlet and the inlet of the standby centrifugation are respectively provided with a stop valve V13 and a stop valve V14. The third-stage centrifugation is further connected with a membrane separation device and a reaction by-product collection device, and the membrane separation device is connected with the deionized water storage tank.

[0011] Further, the emergency pressure relief module comprises a first safety valve V1, a second safety valve V2, a third safety valve V3, a fourth safety valve V5, a fifth safety valve V6, a sixth safety valve V7 and an accident water tank (27). The interlocking of the first safety valve V1, the second safety valve V2 and the third safety valve V3 acts on the raw material supply module, the interlocking of the fourth safety valve V5, the fifth safety valve V6 and the sixth safety valve V7 acts on the reaction-heat exchange coupling module, each safety valve is connected with the inlet of the emergency water tank, and the emergency water tank is connected with a stop valve V17.

[0012] Further, the stop valve group includes a stop valve V8 and a stop valve V9 arranged at the outlet and the inlet of the reactor one respectively and a stop valve V10 and a stop valve V11 arranged at the outlet and the inlet of the reactor two respectively; The temperature sensor group includes a temperature sensor TIC1, a temperature sensor TIC2 and a temperature sensor TIC3 arranged at the heater, the inlets of the reactor one and the reactor two and the outlets of the reactor one and the reactor two respectively, and the three temperature sensors are interlocked; and a pressure gauge PIC4 is arranged at the outlet of the reactor.

[0013] Further, the mixer one adopts a jet collision type mixer, the mixing mode is the mixing of the barium precursor and the titanium precursor, the mixer two adopts a Laval type mixer, the mixing mode is the mixing of the precursor and the supercritical water; and the reactor one and the reactor two are externally provided with a heat preservation structure.

[0014] Further, the quenching heat exchanger and the slow cooling heat exchanger adopt a jacket type heat exchanger, a coil type heat exchanger or a fin type heat exchanger, and the depressor adopts a capillary tube.

[0015] In the second aspect, the application provides a safety and intelligent control method for synthesizing barium titanate by supercritical hydrothermal reaction, which adopts the above system and includes the following steps: The deionized water in the raw material supply module is heated and sent to the gradient cooling depressurization module for preheating, heated to a target temperature in the heater, and then sent to the mixer two after being in a supercritical state; and the barium precursor in the raw material supply module is sent to the mixer one. The barium precursor, the titanium precursor and the deionized water in a supercritical state are mixed in the mixer two and heated, and then the reaction fluid flows into the reactor one and the reactor two for supercritical hydrothermal reaction. The reaction fluid is cooled and depressurized to normal temperature and pressure by the gradient cooling depressurization module. The reaction fluid cooled and depressurized to normal temperature and pressure is transmitted to the product processing module for processing, the obtained nanometer barium titanate powder is stored, the deionized water is sent to the raw material supply module for continuous circulation, and the reaction byproduct is recycled and sold.

[0016] Further, when overpressure occurs in any pipeline of the raw material supply module, the first safety valve V1, the second safety valve V2 or the third safety valve V3 is triggered, so that the material directly enters the emergency water tank for discharge. When the reaction-heat exchange coupling module is over-pressured, the fourth safety valve V5 or the fifth safety valve V6 or the sixth safety valve V7 is triggered, so that the material is directly discharged into the emergency water tank for relief; When the emergency relief module is over-temperature, the cooling water in the cooling water circulating device is sprayed to the emergency water tank for spraying through the action of the stop valve V17 on the emergency water tank, and the action is continued until the temperature of the emergency relief module is reduced to room temperature.

[0017] Compared with the prior art, the present application has the following beneficial technical effects: The present application provides a system for supercritical hydrothermal synthesis of barium titanate, which adopts supercritical hydrothermal continuous reaction, uses multi-stage reactor design and high-efficiency mixer to enable the precursor to react rapidly and sufficiently, greatly shortens the reaction time, and improves the production efficiency. The gradient cooling and pressure reduction module can terminate the reaction in time to avoid excessive grain growth and ensure that the obtained nano barium titanate powder has small particle size and uniform distribution. In addition, the reaction-heat exchange coupling design recycles the reaction heat, improving the energy utilization efficiency. The present application divides the functions of raw material supply, reaction heat exchange, cooling and pressure reduction, product separation, emergency pressure relief, etc. into independent modules, and the interfaces of the modules are standardized and mutually cooperative. The modular structure facilitates flexible configuration and expansion for different production scales or process requirements, and facilitates daily maintenance and component replacement, improving the maintainability and expandability of the equipment. The system process has strong adaptability, and can meet different precursor ratio or production capacity requirements by adjusting the parameter settings of each module, having a wide range of applications.

[0018] Specifically, the system is provided with perfect safety interlocking and emergency handling mechanism, and each module pipeline is provided with a safety valve and an emergency pressure relief device. Once over-temperature or over-pressure occurs, the pressure and temperature can be automatically and quickly released, avoiding danger. Combined with the pressure self-balancing design, the pressure of each section is stable and controlled during operation, significantly improving the safety and reliability of high-temperature and high-pressure reaction.

[0019] Specifically, through online sensing monitoring of multiple parameters such as temperature, pressure, and flow, automatic adjustment of heating power, pumping rate, and valve opening and closing can be realized, and the reaction can be maintained in a stable state under the set conditions in real time. Compared with the prior art, the present system can more accurately control the reaction temperature and pressure, reduce manual intervention, and ensure that the reaction is always in the optimal state, thereby making the product quality more stable and consistent. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The present application provides a system for supercritical hydrothermal synthesis of barium titanate, which adopts supercritical hydrothermal continuous reaction, uses multi-stage reactor design and high-efficiency mixer to enable the precursor to react rapidly and sufficiently, greatly shortens the reaction time, and improves the production efficiency. The gradient cooling and pressure reduction module can terminate the reaction in time to avoid excessive grain growth and ensure that the obtained nano barium titanate powder has small particle size and uniform distribution. In addition, the reaction-heat exchange coupling design recycles the reaction heat, improving the energy utilization efficiency. The present application divides the functions of raw material supply, reaction heat exchange, cooling and pressure reduction, product separation, emergency pressure relief, etc. into independent modules, and the interfaces of the modules are standardized and mutually cooperative. The modular structure facilitates flexible configuration and expansion for different production scales or process requirements, and facilitates daily maintenance and component replacement, improving the maintainability and expandability of the equipment. The system process has strong adaptability, and can meet different precursor ratio or production capacity requirements by adjusting the parameter settings of each module, having a wide range of applications.

[0021] In the figure, 1, titanium precursor storage tank; 2, barium precursor storage tank; 3, deionized water storage tank; 4, first high-pressure delivery pump; 5, second high-pressure delivery pump; 6, third high-pressure delivery pump; 7, mixer one; 8, heater; 9, mixer two; 10, reactor one; 11, reactor two; 12, water spray desuperheater; 13, quench heat exchanger; 14, slow cooling heat exchanger; 15, cooling water circulating device; 16, fourth high-pressure delivery pump; 17, pressure reducer; 18, first centrifugal; 19, standby centrifugal; 20, second centrifugal; 21, third centrifugal; 22, ultrasonic washing device; 23, vacuum drying device; 24, nano barium titanate storage device; 25, membrane separation device; 26, reaction by-product collection device; 27, emergency water tank. DETAILED DESCRIPTION

[0022] Hereinafter, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0023] In the description of the present application, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0025] In the present application, unless specifically defined otherwise and limited in the specification, the terms "mount", "connected", "connection", "fixed", and the like, should be construed broadly and do not necessarily require a direct connection or attachment between two elements. These terms can include indirect connections between two elements in the form of an indirect connection through one or more intermediate elements. In addition, a connection between two elements can be a mechanical connection, an electrical connection, or a communication connection. It will be apparent to those skilled in the art that these terms can have the same meaning as the corresponding terms used in the art.

[0026] In the present application, unless specifically defined otherwise and limited in the specification, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. "Under", "below" and "underneath" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0027] It should be understood that the terms "comprise" and "include" as used in the specification and the appended claims indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0028] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0029] It should be further understood that the term "and / or" as used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations thereof.

[0030] Various structural diagrams according to the disclosed embodiments of the present application are shown in the accompanying drawings. These drawings are not drawn to scale, in which certain details are exaggerated for the purpose of clarity and certain details can be omitted. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are only exemplary, and in actuality there can be deviations due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes and relative positions can be additionally designed by those skilled in the art according to actual needs.

[0031] Although the existing preparation technology can prepare high-performance powder to some extent, it still cannot meet the actual needs in rapid and accurate control of reaction temperature, safe and reliable operation of the system, accurate regulation of product particle size, and modular expansion of equipment. The present application is a system for supercritical hydrothermal synthesis of barium titanate, which realizes higher reaction efficiency, more optimal particle size uniformity and more perfect safety protection through modular equipment design and intelligent process control, and meets the demand for large-scale preparation of high-performance barium titanate powder.

[0032] Referring to Figure 1 , specifically includes a raw material supply module for transporting titanium precursors, barium precursors and deionized water; a reaction-heat exchange coupling module for supercritical hydrothermal synthesis reaction and system heat recovery; a gradient cooling and pressure reduction module for terminating supercritical hydrothermal reaction and cooling and pressure reduction of the post-reaction fluid; an emergency pressure relief module for cooling water system circulation and rapid and safe handling of reactants in the event of system abnormalities; and a product treatment module for solid-liquid separation of the post-reaction fluid. The outlet of the raw material supply module is connected to the reaction-heat exchange coupling module and the emergency pressure relief module; the outlet of the reaction-heat exchange coupling module is connected to the gradient cooling and pressure reduction module and the emergency pressure relief module; the outlet of the gradient cooling and pressure reduction module is connected to the product treatment module and the emergency pressure relief module; and the outlet of the gradient cooling and pressure reduction module is connected to the product treatment module and the emergency pressure relief module. The reaction-heat exchange coupling module includes a mixer one 7, a heater 8, a mixer two 9 and a cooling water circulation device 15; the inlet of the mixer one 7 is connected to the outlet of the raw material supply module, the outlets of the mixer one 7 and the heater 8 are both connected to the inlet of the mixer two 9, the outlet of the mixer two 9 is connected to the inlet of a reactor one 10, a reactor two 11 is arranged in parallel on the reactor one 10, a stop valve group and a temperature sensor group are arranged on the reactor one 10 and the reactor two 11; the outlets of the mixer two 9 and the reactor one 10 are connected to the emergency pressure relief module; and the cooling water circulation device 15 is connected with a fourth high-pressure delivery pump 16, and the outlet of the fourth high-pressure delivery pump 16 is connected to the gradient cooling and pressure reduction module. The stop valve group is used to control the reaction time of the material by controlling the fluid path, and forms a segmented structure arrangement, and the stop valve group includes stop valves V8, V9, V10 and V11; the stop valves V8 and V9 are arranged at the outlet and inlet of the reactor one 10 respectively, and the stop valves V10 and V11 are arranged at the outlet and inlet of the reactor two 11 respectively. The temperature sensor group includes three temperature sensors TIC1, TIC2 and TIC3 which are interlocked in display; the temperature sensor TIC1 is arranged on the heater 8, the temperature sensor TIC2 is arranged at the inlet of the reactor one 10 and the reactor two 11, and the temperature sensor TIC3 is arranged at the outlet of the reactor one 10 and the reactor two 11.

[0033] In a specific embodiment of the present application, the mixer 7 is a jet collision mixer, the mixing mode is the mixing of barium precursors and titanium precursors, the mixer 9 is a Laval mixer, the mixing mode is the mixing of precursors and supercritical water, the barium precursor is barium hydroxide, barium chloride, barium nitrate or barium acetate, and the titanium precursor is tetrabutyl titanate, titanium tetrachloride or titanium dioxide sol; the reactor 10 and the reactor 11 are externally provided with a heat preservation structure to reduce heat loss and ensure that the reaction temperature is maintained stable.

[0034] In some preferred embodiments of the present application, the raw material supply module comprises a titanium precursor storage tank 1, a barium precursor storage tank 2 and a deionized water storage tank 3, the outlets of the titanium precursor storage tank 1, the barium precursor storage tank 2 and the deionized water storage tank 3 are respectively connected with a first high-pressure delivery pump 4, a second high-pressure delivery pump 5 and a third high-pressure delivery pump 6; the inlets of the first high-pressure delivery pump 4, the second high-pressure delivery pump 5 and the third high-pressure delivery pump 6 are respectively provided with a flow meter FIC1, a flow meter FIC2 and a flow meter FIC3, the outlets of the first high-pressure delivery pump 4, the second high-pressure delivery pump 5 and the third high-pressure delivery pump 6 are respectively provided with a pressure gauge PIC1, a pressure gauge PIC2 and a pressure gauge PIC3, and the outlets of the first high-pressure delivery pump 4 and the second high-pressure delivery pump 5 are connected to the inlet of the mixer 7, and the outlet of the third high-pressure delivery pump 6 is connected to the emergency pressure relief module. It should be noted that each flow meter and pressure gauge is interlocked with the motor of the corresponding high-pressure delivery pump.

[0035] In some preferred embodiments of the present application, the gradient cooling and pressure reduction module comprises a water spray cooler 12, a quenching heat exchanger 13, a slow cooling heat exchanger 14 and a pressure reducer 17 connected in sequence, the inlet of the water spray cooler 12 is connected to the outlets of the mixer 9 and the reactor 10, the inlet of the quenching heat exchanger 13 is provided with a temperature sensor TIC4 and a pressure gauge PIC5, and the outlet of the quenching heat exchanger 13 is provided with a temperature sensor TIC5 and a pressure gauge PIC6; the pressure reducer 17 is connected to the product treatment module, and the electric pressure control valve V13 and the electric pressure control valve V12 are connected in parallel on the pipeline connecting the pressure reducer 17 and the product treatment module.

[0036] In a specific embodiment of the present application, the quenching heat exchanger 13 and the slow cooling heat exchanger 14 are a jacketed heat exchanger, a coil heat exchanger or a fin heat exchanger, and the pressure reducer 15 is a capillary tube.

[0037] In some preferred embodiments of the present application, the product processing module comprises a first centrifuge 18, a second centrifuge 20, a third centrifuge 21, an ultrasonic washing device 22, a vacuum drying device 23 and a nano barium titanate storage device 24 connected in sequence; the solid phase product outlet of the third centrifuge 21 is connected to the inlet of the ultrasonic washing device 22, the outlet of the ultrasonic washing device 22 is connected to the inlet of the vacuum drying device 23, and the outlet of the vacuum drying device 23 is connected to the inlet of the nano barium titanate storage device 24; the third high-pressure delivery pump 6 is interlocked with an electric proportional valve V4 and a pressure gauge TIC4. The first centrifuge 18 is connected in parallel with a standby centrifuge 19, and the outlet and the inlet of the standby centrifuge 19 are respectively provided with a stop valve V13 and a stop valve V14 for controlling the switching use of the standby centrifuge 19 and the first centrifuge 18.

[0038] The liquid phase product outlet of the third centrifuge 21 is connected to the inlet of a membrane separation device 25, the membrane separation device 25 is connected to the deionized water storage tank 3, and the deionized water after material separation is recovered to the deionized water storage tank 3; the outlet of the membrane separation device 25 is connected to a reaction byproduct collection device 26, and the reaction byproduct collection device 26 collects reaction byproducts for recycling and selling.

[0039] In some preferred embodiments of the present application, the emergency pressure relief module comprises a first safety valve V1, a second safety valve V2, a third safety valve V3, a fourth safety valve V5, a fifth safety valve V6, a sixth safety valve V7 and an accident water tank 27; the interlocking of the first safety valve V1, the second safety valve V2 and the third safety valve V3 acts on the raw material supply module, the interlocking of the fourth safety valve V5, the fifth safety valve V6 and the sixth safety valve V7 acts on the reaction-heat exchange coupling module, each safety valve is connected to the inlet of the accident water tank 27, and the accident water tank 27 is connected with a stop valve V17.

[0040] The present application also provides a safety and intelligent control method for synthesizing barium titanate by supercritical hydrothermal method, which adopts the above-mentioned system for synthesizing barium titanate by supercritical hydrothermal method, and comprises the following steps: The deionized water in the raw material supply module is heated and sent to the gradient cooling and pressure reduction module for preheating, and then sent to the heater 8 for heating to a target temperature, so that the deionized water is in a supercritical state and then sent to the mixer two 9; In a specific embodiment of the present application, the deionized water in the deionized water storage tank 3 is preheated by the third high-pressure delivery pump 6 and then sent to the heater 8 for heating to a target temperature, so that the deionized water is in a supercritical state and then sent to the mixer two 9; see Figure 1The outlet of the barium precursor tank 2 is provided with a flow meter FIC2 which is interlocked with the second high-pressure delivery pump 5 to control the outlet flow of the second high-pressure delivery pump 5 by flow indication; The barium precursor in the raw material supply module is delivered to the mixer one 7, the titanium precursor is delivered to the mixer one 7, the titanium precursor, the barium precursor and the supercritical state deionized water are mixed in the mixer two 9 and are heated, and then the reaction fluid flows into the reactor one 10 and the reactor two 11 to perform supercritical hydrothermal reaction, so that the supercritical fluid is obtained; In a specific embodiment of the present application, the titanium precursor, the barium precursor and the supercritical state deionized water are efficiently mixed in the mixer two 9 and are rapidly heated, and then flow into the reactor one 10 and the reactor two 11 to perform supercritical hydrothermal reaction, the material reaction time is controlled through the stop valve V8, the stop valve V9, the stop valve V10 and the stop valve V11, then the reaction fluid is separated from the supercritical state by using the water spray desuperheater 12, the reaction fluid is instantaneously cooled and the reaction is terminated through the quenching heat exchanger 13; the temperature sensor TIC1 of the interlocked heater 8, the inlet of the reactor one 10 and the reactor two 11 of the interlocked temperature sensor TIC2, the outlet of the mixer two 9 of the interlocked temperature sensor TIC2 and the outlet of the reactor one 10 and the reactor two 11 of the interlocked temperature sensor TIC3 are fed back online in real time through temperature, the power of the heater 8 is adjusted to control the reaction temperature, so that the reaction fluid is stably maintained in the supercritical state; The supercritical fluid is cooled and depressurized to normal temperature and pressure through the gradient cooling and depressurizing module In a specific embodiment of the present application, the temperature sensor TIC4 and the pressure gauge PIC5 are arranged at the inlet of the quenching heat exchanger 13, and the temperature sensor TIC5 and the pressure gauge PIC6 are arranged at the outlet of the quenching heat exchanger 13, so that the pipeline condition of the gradient cooling and depressurizing module is monitored online in real time; the reaction fluid which is greatly cooled is further cooled through the slow cooling heat exchanger 14, the cooling water in the cooling water circulating device 15 is sent to the slow cooling heat exchanger 14 through the fourth high-pressure delivery pump 16, and the residual heat is used to accelerate the dissolution of the barium precursor in the barium precursor tank 2; the cooled reaction fluid is reduced in pressure through the pressure reducer 17, and then is reduced to normal pressure through the electric pressure control valve V12, the electric pressure control valve V12 is interlocked with the pressure gauge PIC4 arranged at the outlet of the reactor one 10 and the reactor 11, the electric pressure control valve V12 is adjusted according to the pressure at the outlet of the reactor one 10, so that the pressure before the valve is stably maintained; The reaction fluid reduced to normal temperature and pressure is transported to the product processing module for processing, the obtained nano-barium titanate powder is stored, deionized water is sent to the raw material supply module for continuous circulation, and the reaction byproduct is recycled and sold; In a specific embodiment of the present application, after the reaction fluid reduced to normal temperature and pressure is separated by multiple stages of centrifugation, i.e., first centrifugation 18, second centrifugation 20 and third centrifugation 21, the obtained nano-barium titanate solid phase particles pass through ultrasonic washing device 22 and vacuum drying device 23, the prepared nano-barium titanate powder is stored in nano-barium titanate product storage tank 24; the inlet of first centrifugation 18 is provided with stop valve V14 for temporarily stopping the first centrifugation, and standby centrifugation 19 is connected in parallel to achieve continuous and efficient centrifugation, stop valve V15 and stop valve V16 are respectively arranged at the inlet and outlet of standby centrifugation 19 to start standby centrifugation 19, the separated liquid phase product passes through membrane separation device 25 to obtain deionized water which is sent to deionized water storage tank 3 for continuous circulation, and the reaction byproduct enters reaction byproduct collection device 26 for recycling and selling.

[0041] When the raw material supply module has overpressure in any pipeline, first safety valve V1 or second safety valve V2 or third safety valve V3 is triggered, so that the material directly enters accident water tank 27 for discharge; when the reaction-heat exchange coupling module has overpressure in any pipeline, fourth safety valve V5 or fifth safety valve V6 or sixth safety valve V7 is triggered, so that the material directly enters accident water tank 27 for discharge. When the emergency discharge module is overheated, stop valve V17 acts on accident water tank 27, so that the cooling water in cooling water circulation device 15 is sent to accident water tank 27 for spraying, and the action continues until the temperature of the emergency discharge module decreases to room temperature.

[0042] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A system for supercritical hydrothermal synthesis of barium titanate, characterized by, The module comprises a raw material supply module, a reaction-heat exchange coupling module, a gradient cooling and pressure reduction module, an emergency pressure relief module and a product processing module. The outlet of the raw material supply module is connected to the reaction-heat exchange coupling module and the emergency pressure relief module. The outlet of the reaction-heat exchange coupling module is connected to the gradient cooling and pressure reduction module and the emergency pressure relief module. The inlet of the mixer one (7) is connected to the outlet of the raw material supply module, the outlet of the mixer one (7) and the heater (8) is connected to the inlet of the mixer two (9), the outlet of the mixer two (9) is connected to the inlet of the reactor one (10), the reactor one (10) is connected in parallel with the reactor two (11), the reactor one (10) and the reactor two (11) are provided with a group of stop valves and a group of temperature sensors for number display interlocking, the outlet of the mixer two (9) and the reactor one (10) is connected to the emergency pressure relief module. The cooling water circulating device (15) is connected with the fourth high-pressure delivery pump (16), and the outlet of the fourth high-pressure delivery pump (16) is connected to the gradient cooling and pressure reduction module. The outlet of the gradient cooling and pressure reduction module is connected to the product processing module and the emergency pressure relief module.

2. The system for supercritical hydrothermal synthesis of barium titanate according to claim 1, characterized in that, The raw material supply module comprises a titanium precursor storage tank (1), a barium precursor storage tank (2) and a deionized water storage tank (3), the outlet of the titanium precursor storage tank (1), the barium precursor storage tank (2) and the deionized water storage tank (3) is connected with the first high-pressure delivery pump (4), the second high-pressure delivery pump (5) and the third high-pressure delivery pump (6) respectively, the inlet of the first high-pressure delivery pump (4), the second high-pressure delivery pump (5) and the third high-pressure delivery pump (6) is provided with the flow meter FIC1, the flow meter FIC2 and the flow meter FIC3 respectively, the outlet of the first high-pressure delivery pump (4), the second high-pressure delivery pump (5) and the third high-pressure delivery pump (6) is provided with the pressure gauge PIC1, the pressure gauge PIC2 and the pressure gauge PIC3 respectively, and the outlet of the first high-pressure delivery pump (4) and the second high-pressure delivery pump (5) is connected to the inlet of the mixer one (7), the outlet of the third high-pressure delivery pump (6) is connected to the emergency pressure relief module, and the third high-pressure delivery pump (6) is interlocked with the electric proportional valve V4 and the pressure gauge TIC4.

3. The system for supercritical hydrothermal synthesis of barium titanate according to claim 2, characterized in that, The gradient cooling and pressure reduction module comprises a water spray cooler (12), a quenching heat exchanger (13), a slow cooling heat exchanger (14) and a pressure reducer (17) connected in sequence, the inlet of the water spray cooler (12) is connected to the outlet of the mixer two (9) and the reactor one (10), the temperature sensor TIC4 and the pressure gauge PIC5 are arranged at the inlet of the quenching heat exchanger (13), and the temperature sensor TIC5 and the pressure gauge PIC6 are arranged at the outlet of the quenching heat exchanger (13). The pressure reducer (17) is connected to the product processing module, and the electric pressure control valve V13 and the electric pressure control valve V12 are arranged in parallel on the pipeline connected with the pressure reducer (17) and the product processing module.

4. The system for supercritical hydrothermal synthesis of barium titanate according to claim 3, characterized in that, The product processing module comprises a first-stage centrifuge (18), a second-stage centrifuge (20), a third-stage centrifuge (21), an ultrasonic washing device (22), a vacuum drying device (23) and a nano barium titanate storage device (24) connected in sequence; the first-stage centrifuge (18) is connected in parallel with a standby centrifuge (19), and the outlet and the inlet of the standby centrifuge (19) are respectively provided with a stop valve V14, a stop valve V15 and a stop valve V16; The third-stage centrifuge (21) is further connected in sequence with a membrane separation device (25) and a reaction by-product collecting device (26), and the membrane separation device (25) is connected to a deionized water storage tank (3).

5. The system for supercritical hydrothermal synthesis of barium titanate according to claim 4, characterized in that, The emergency pressure relief module comprises a first safety valve V1, a second safety valve V2, a third safety valve V3, a fourth safety valve V5, a fifth safety valve V6, a sixth safety valve V7 and an accident water tank (27); The interlocking of the first safety valve V1, the second safety valve V2 and the third safety valve V3 acts on the raw material supply module, and the interlocking of the fourth safety valve V5, the fifth safety valve V6 and the sixth safety valve V7 acts on the reaction-heat exchange coupling module; each safety valve is connected to the inlet of the accident water tank (27), and the accident water tank (27) is connected with a stop valve V17.

6. The system for supercritical hydrothermal synthesis of barium titanate according to claim 1, wherein The stop valve group comprises a stop valve V8 and a stop valve V9 arranged at the outlet and the inlet of the reactor one (10) respectively and stop valves V10 and V11 arranged at the outlet and the inlet of the reactor two (11) respectively; The temperature sensor group comprises temperature sensors TIC1, TIC2 and TIC3 arranged at the heater (8), the inlets of the reactor one (10) and the reactor two (11) and the outlets of the reactor one (10) and the reactor two (11) respectively, and the three temperature sensors are interlocked; the outlets of the reactor one (10) and the reactor two (11) are provided with a pressure gauge PIC4.

7. The system for supercritical hydrothermal synthesis of barium titanate according to claim 1, wherein The mixer one (7) adopts a jet collision type mixer, and the mixer two (9) adopts a Laval type mixer; the reactor one (10) and the reactor two (11) are externally provided with a heat preservation structure.

8. The system for supercritical hydrothermal synthesis of barium titanate according to claim 3, wherein The quenching heat exchanger (13) and the slow cooling heat exchanger (14) adopt a jacket type heat exchanger, a coil type heat exchanger or a fin type heat exchanger, and the pressure reducer (17) adopts a capillary tube.

9. A safe and intelligent control method for supercritical hydrothermal synthesis of barium titanate, using the system of any one of claims 1-8, characterized in that, The method comprises the following steps: The deionized water in the raw material supply module is heated and sent to the gradient cooling pressure reduction module for preheating, heated to a target temperature in the heater (8), and then sent to the mixer two (9) after being in a supercritical state; the barium precursor in the raw material supply module is sent to the mixer one (7), the titanium precursor is sent to the mixer one (7), the titanium precursor, the barium precursor and the deionized water in a supercritical state are mixed in the mixer two (9) and heated, and then the reaction fluid flows into the reactor one (10) and the reactor two (11) to perform a supercritical hydrothermal reaction, so as to obtain a supercritical fluid; The supercritical fluid is cooled and depressurized to normal temperature and pressure through the gradient cooling pressure reduction module; ​ The reaction fluid reduced to normal temperature and pressure is transported to the product processing module for processing, the obtained nano barium titanate powder is stored, deionized water is sent to the raw material supply module for continuous circulation, and the reaction byproduct is recycled and sold. 10.The safe and intelligent control method for synthesizing barium titanate by supercritical hydrothermal method according to claim 9, characterized in that, When the raw material supply module has overpressure in any pipeline, the first safety valve V1 or the second safety valve V2 or the third safety valve V3 is triggered, so that the material directly enters the emergency water tank (27) for discharge; When the reaction-heat exchange coupling module has overpressure in any pipeline, the fourth safety valve V5 or the fifth safety valve V6 or the sixth safety valve V7 is triggered, so that the material directly enters the emergency water tank (27) for discharge; When the emergency discharge module is over-temperature, the emergency water tank (27) is acted on by the stop valve V17, so that the cooling water in the cooling water circulating device (15) is sent to the emergency water tank (27) for spraying, and the action is continued until the temperature of the emergency discharge module is reduced to room temperature.

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