System and process for preparing nano yttrium oxide by spray pyrolysis method based on double closed-loop fluid control

Abstract

The invention relates to the technical field of rare earth nano material preparation, in particular to a system for preparing nano yttrium oxide by a spray pyrolysis method based on double closed-loop fluid control, which comprises a yttrium salt solution storage tank and a cooling water tank. The atomizing nozzle adopts a self-cleaning design, high-pressure N2 is sprayed for 0.2 s every 30 s, impurity blockage can be effectively prevented, it is ensured that the atomizing process is stable and efficient, frequent manual maintenance is not needed, the production cost and equipment loss are reduced, nano yttrium oxide particles prepared through double-closed-loop fluid control and an accurate pyrolysis process are uniform in particle control, and the particle size of the nano yttrium oxide particles is reduced. The specific surface area reaches 120 + / -5m < 2 > / g, and the sphericity is And in addition, when the temperature of the reaction furnace exceeds the standard, the emergency cooling system is rapidly started, rapidly cooled and stabilized in a safe range, reaction out-of-control and equipment damage are avoided, the safety and reliability of the production process are greatly improved, and the product quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth nanomaterial preparation, in particular to a system for preparing nano yttrium oxide by a spray pyrolysis method based on double closed-loop fluid control. Background Art

[0002] Rare earth nanomaterials refer to materials made from rare earth elements at the nanoscale (1-100nm). They combine the properties of rare earth elements and nanomaterials, and exhibit unique advantages and broad application prospects in the fields of optics, catalysis, magnetism, etc.

[0003] The traditional preparation process lacks high-precision atomization control, which makes it difficult to accurately match the liquid flow rate and the atomizing gas pressure, resulting in uneven droplet sizes. During the pyrolysis process, the uneven droplets are heated differently, resulting in large differences in the particle size of the final product and a wide distribution. At the same time, the agglomeration phenomenon is serious. This is because the control of temperature and atmosphere during the pyrolysis process is not precise enough to meet the precise conditions required for the formation of nano-yttrium oxide, affecting the performance of the material and limiting its application in high-end fields. In addition, the traditional preparation process does not have a nozzle cleaning function. After long-term use, the atomizing nozzle is easily clogged by impurities in the precursor solution. It not only affects the atomization effect and reduces production efficiency, but also requires frequent shutdowns for manual cleaning or replacement of nozzles, increasing maintenance costs and equipment losses. Moreover, the process lacks an emergency cooling function. When the temperature in the reactor rises abnormally due to various reasons, it cannot be cooled quickly, which may cause the reaction to get out of control, damage the equipment, and cause safety accidents. It will also seriously affect the quality of the product, resulting in problems such as abnormal crystal structure and increased impurities, further reducing the product qualification rate and causing economic losses. In order to solve the above technical problems, we have designed a system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control. Summary of the Invention

[0004] The purpose of the present invention is to provide a system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control, which has the advantages of uniform product particle size, emergency cooling function and nozzle self-cleaning function, and solves the problems of traditional preparation processes lacking high-precision atomization control and lacking nozzle cleaning function and emergency cooling function.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a system for preparing nano-yttrium oxide by spray pyrolysis method based on double closed-loop fluid control, comprising a yttrium salt solution storage tank and a cooling water tank, wherein the bottom of the left side of the yttrium salt solution storage tank is fixedly connected with an online conductivity meter, the discharge end of the yttrium salt solution storage tank is connected to a corrosion-resistant gear pump through a pipeline, the discharge end of the corrosion-resistant gear pump is connected to a pulse damping system through a pipeline, the right side of the pulse damping system is connected to a mass flow meter through a pipeline, the right end of the mass flow meter is connected to an ultrasonic atomizer through a pipeline, the output end of the ultrasonic atomizer is connected to a dual-fluid atomizing nozzle through a pipeline, the right side of the dual-fluid atomizing nozzle is connected to a vertical tubular reactor through bolts, and the dual-fluid The left side of the top of the atomizing nozzle is connected to a gas mass flow controller, the right side of the bottom of the dual-fluid atomizing nozzle is connected to an air pipe, the bottom end of the air pipe is connected to a nitrogen bottle, the left side of the top of the vertical tubular reactor is fixedly connected to a laser diffractometer, the top of the left side of the cooling water tank is connected to a water pump by bolts, the inner wall of the vertical tubular reactor is fixedly connected to a cooling coil, the right side of the cooling water tank is penetrated and fixedly connected to a refrigeration unit, the refrigeration end of the refrigeration unit penetrates into the interior of the cooling water tank and is connected to a cooling fin by bolts, the top of the right side of the vertical tubular reactor is connected to a pressure relief valve, the discharge end of the vertical tubular reactor is connected to an electrostatic collector through a pipeline, and the discharge end of the electrostatic collector is connected to a cyclone separator through a pipeline.

[0006] Preferably, the right end of the dual-fluid atomizing nozzle penetrates into the interior of the vertical tubular reactor, and the detection end of the laser diffractometer penetrates into the interior of the vertical tubular reactor.

[0007] Preferably, a pressure gauge is fixedly connected to the right side of the top of the vertical tubular reactor, the liquid outlet end of the water pump passes through the vertical tubular reactor and is connected to the top of the cooling coil, and the liquid inlet end of the water pump passes through the interior of the cooling water tank.

[0008] Preferably, a reflux pipe is fixedly connected to the left side of the bottom of the cooling water tank, and the left end of the reflux pipe passes through the interior of the vertical tubular reactor and is connected to the bottom end of the cooling coil.

[0009] Preferably, the left side of the top of the cooling water tank is connected to a water injection pipe, and a pipe cap is provided on the surface of the water injection pipe through a threaded sleeve.

[0010] Preferably, a temperature sensor is connected to the right side of the bottom of the inner cavity of the cooling water tank via bolts, and there are several cooling fins.

[0011] Preferably, the flow accuracy of the corrosion-resistant gear pump is ±0.2%, and the frequency of the ultrasonic atomization generator is 1.7 MHz.

[0012] Preparation process of nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control:

[0013] A: First, prepare a 0.5 mol / L yttrium nitrate-ethanol solution in a yttrium salt solution storage tank. The viscosity is 2.1 ± 0.1 cP and the surface tension is 28 mN / m. At the same time, add 0.5 wt% polyethylene glycol as a dispersant.

[0014] B: The precursor solution is delivered by a corrosion-resistant gear pump, and the mass flow meter monitors the liquid flow in real time. The flow rate is controlled at 0.5-20 mL / min, which is set to 8 mL / min in this process. At the same time, the gas mass flow controller controls the flow of carrier gas and reaction gas, and the gas pressure is controlled at 0.1-0.5 MPa, which is 0.3 MPa in this process. The liquid and gas are mixed and atomized through a two-fluid atomizing nozzle. The ultrasonic atomizing generator has a frequency of 1.7 MHz, which can efficiently convert the liquid into tiny droplets, and finally form droplets with an average particle size of D50 = 8 μm. This process is based on a double closed-loop collaborative control system. The liquid flow rate is dynamically coupled with the atomizing gas pressure, following the atomization stability model Qg = k·Ql·ρ, ensuring a stable atomization process and producing uniform and fine droplets.

[0015] C: The carrier gas carries the droplets into the vertical tubular reactor, which has three independent temperature zones. The droplets first enter the preheating zone and stay there for 2 seconds. The main purpose is to remove the solvent and make the droplets initially dry; then enter the reaction zone, with a heating rate of 500℃ / s and a stay of 1.5 seconds. The precursor decomposes at this stage; finally enter the slow cooling zone, stay for 30 seconds, and pass a 5% H2 / Ar mixed gas to control the crystal form. During the pyrolysis process, the O2 concentration is controlled in stages, with 15vol% in the pyrolysis zone to provide sufficient oxygen for the decomposition of the precursor, and 2vol% in the slow cooling zone to prevent excessive oxidation of the product during the cooling process, thereby ensuring the crystal structure and performance of the product;

[0016] D: The products after pyrolysis are recovered by an electrostatic collector and a cyclone separator. The voltage of the electrostatic collector is adjustable from 0 to 30 kV, and is set to 25 kV in this process. A high-voltage electric field is used to charge the product particles and adsorb them on the plates. The plate spacing is 50 mm. The cyclone separator is made of 316L stainless steel and uses centrifugal force to further separate and collect the remaining product particles, achieving efficient product recovery.

[0017] E: The dual-fluid atomizing nozzle adopts a silicon carbide lining structure with a surface roughness of Ra < 0.1μm. The smooth lining surface can reduce the adhesion of impurities in the precursor solution. Every 30 seconds, the system will control the electric valve on the surface of the air pipe to open, so that the high-pressure N2 inside the nitrogen bottle is ejected from the air pipe. The powerful air pressure impact force is used to quickly blow away the precursor impurities and scaling attached to the inner wall and outlet of the dual-fluid atomizing nozzle. Due to the intermittent injection design of the pulse gas circuit, it does not affect the normal atomization work, but can clean the nozzle in time to maintain its good atomization performance, avoid the deterioration of the atomization effect and the reduction of production efficiency due to blockage, reduce the frequency of manual cleaning or replacement of the nozzle, and reduce maintenance costs and equipment loss.

[0018] F: When the temperature of the vertical tubular reactor exceeds the standard, the cooling water tank, water pump, cooling coil, refrigeration unit and temperature sensor work together to cool the vertical tubular reactor. The temperature sensor in the cooling water tank monitors the water temperature in real time. The refrigeration end of the refrigeration unit cools and reduces the temperature of the water in the cooling water tank through the cooling fins to ensure that there is a low-temperature cooling medium in the water tank. At the same time, the water pump starts to work to pump out the low-temperature water in the cooling water tank and transport it to the inner wall of the vertical tubular reactor through the cooling coil. The cooling coil surrounds the inside of the vertical tubular reactor. The low-temperature water flows in the cooling coil and absorbs the heat in the vertical tubular reactor through heat exchange, so that the temperature of the reactor is reduced. The hot water after absorbing the heat flows back to the cooling water tank through the reflux pipe. This cycle is repeated, continuously taking away the heat in the reactor, achieving rapid cooling, preventing the reaction from getting out of control, protecting equipment safety, avoiding quality problems such as abnormal crystal structure and increased impurities in the product, and improving the product qualification rate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention cooperates with a cooling water tank, an online conductivity meter, a corrosion-resistant gear pump, a pulse damping system, a mass flow meter, an ultrasonic atomizer, a dual-fluid atomizer nozzle, a vertical tubular reactor, a gas mass flow controller, an air pipe, a nitrogen bottle, a laser diffractometer, a water pump and a cooling coil. The atomizer nozzle adopts a self-cleaning design and sprays 0.2s of high-pressure N2 every 30s, which can effectively prevent impurity blockage and ensure a stable and efficient atomization process. Frequent manual maintenance is not required, reducing production costs and equipment losses. In terms of particle control, through double closed-loop fluid control and precise pyrolysis process, the prepared nano yttrium oxide particles are uniform and have a specific surface area of ​​120±5m 2 / g, sphericity>95%, which can meet the needs of high-end applications. In addition, when the reactor temperature exceeds the standard, the emergency cooling system starts quickly, quickly cools down and stabilizes it within a safe range, avoiding runaway reaction and equipment damage, greatly improving the safety and reliability of the production process and ensuring product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 It is a schematic cross-sectional view of the local structure of the present invention.

[0023] In the figure: 1. Yttrium salt solution storage tank; 2. Cooling water tank; 3. Online conductivity meter; 4. Corrosion-resistant gear pump; 5. Pulse damping system; 6. Mass flow meter; 7. Ultrasonic atomizer; 8. Two-fluid atomizing nozzle; 9. Vertical tubular reactor; 10. Gas mass flow controller; 11. Gas pipe; 12. Nitrogen cylinder; 13. Laser diffractometer; 14. Water pump; 15. Cooling coil; 16. Refrigeration unit; 17. Cooling plate; 18. Pressure relief valve; 19. Electrostatic collector; 20. Cyclone separator; 21. Pressure gauge; 22. Reflux pipe; 23. Temperature sensor. DETAILED DESCRIPTION

[0024] See also Figure 1-Figure 2A system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control includes an yttrium salt solution storage tank 1 and a cooling water tank 2. An online conductivity meter 3 is fixedly connected to the bottom of the left side of the yttrium salt solution storage tank 1. By setting up the online conductivity meter 3, the solution conductivity can be measured in real time to quickly reflect the changes in the ion concentration in the solution. Once the solution concentration deviates, it can be adjusted in time to avoid abnormal preparation process caused by unstable solution concentration, thereby ensuring the repeatability and stability of experiments or production. The discharge end of the yttrium salt solution storage tank 1 is connected to a corrosion-resistant gear pump 4 through a pipeline. The discharge end of the corrosion-resistant gear pump 4 is connected to a pulse damping system 5 through a pipeline, the right side of the pulse damping system 5 is connected to a mass flow meter 6 through a pipeline, the right end of the mass flow meter 6 is connected to an ultrasonic atomizer 7 through a pipeline, the output end of the ultrasonic atomizer 7 is connected to a dual-fluid atomizing nozzle 8 through a pipeline, the right side of the dual-fluid atomizing nozzle 8 is connected to a vertical tubular reactor 9 through bolts, the left side of the top of the dual-fluid atomizing nozzle 8 is connected to a gas mass flow controller 10, the right side of the bottom of the dual-fluid atomizing nozzle 8 is connected to an air pipe 11, and the bottom of the air pipe 11 is connected to the bottom of the air pipe 11. The end is connected to a nitrogen bottle 12, and the left side of the top of the vertical tubular reactor 9 is fixedly connected to a laser diffractometer 13. By setting the laser diffractometer 13, the droplet particle size can be collected in real time to provide feedback data for the double closed-loop fluid control, so as to adjust the liquid flow and gas pressure in time to ensure that the droplet particle size is always in the ideal range, thereby ensuring the particle size uniformity of the pyrolysis product. The top of the left side of the cooling water tank 2 is connected to a water pump 14 by bolts, and the inner wall of the vertical tubular reactor 9 is fixedly connected to a cooling coil 15. By setting the cooling coil 15, the coolant and the reactor can be increased. The contact area of ​​the furnace can efficiently transfer heat, so that the reaction furnace can be cooled quickly, ensuring that the reaction is carried out within the appropriate temperature range, ensuring the safe operation of the equipment and the stability of the product. The right side of the cooling water tank 2 is fixedly connected with a refrigeration unit 16, and the refrigeration end of the refrigeration unit 16 passes through the interior of the cooling water tank 2 and is connected with a cooling plate 17 by bolts. The top of the right side of the vertical tubular reactor 9 is connected to a pressure relief valve 18, and the discharge end of the vertical tubular reactor 9 is connected to an electrostatic collector 19 through a pipeline, and the discharge end of the electrostatic collector 19 is connected to a cyclone separator 20 through a pipeline.

[0025] The right end of the two-fluid atomizing nozzle 8 penetrates into the interior of the vertical tubular reactor 9 , and the detection end of the laser diffractometer 13 penetrates into the interior of the vertical tubular reactor 9 .

[0026] A pressure gauge 21 is fixedly connected to the right side of the top of the vertical tubular reactor 9. By setting the pressure gauge 21, the pressure inside the vertical tubular reactor 9 can be monitored in real time, and pressure data can be provided to the operator so that abnormal pressure conditions can be discovered in time and corresponding measures can be taken to ensure that the reaction process is safe and stable. The liquid outlet end of the water pump 14 passes through the vertical tubular reactor 9 and is connected to the top of the cooling coil 15. The liquid inlet end of the water pump 14 passes through the interior of the cooling water tank 2.

[0027] A return pipe 22 is fixedly connected to the left side of the bottom of the cooling water tank 2. By setting the return pipe 22, the hot water in the cooling coil 15 is returned to the cooling water tank 2, thereby realizing the recycling of the coolant, ensuring the continuity and stability of the cooling system, reducing energy consumption, and helping to maintain the stability of the coolant level in the cooling water tank 2. The left end of the return pipe 22 passes through the interior of the vertical tubular reactor 9 and is connected to the bottom end of the cooling coil 15.

[0028] The left side of the top of the cooling water tank 2 is connected with a water injection pipe. By providing the water injection pipe, it is convenient for the user to add cooling medium to the interior of the cooling water tank 2. The surface of the water injection pipe is threadedly sleeved with a pipe cap.

[0029] A temperature sensor 23 is bolted to the right side of the bottom of the inner cavity of the cooling water tank 2. By setting the temperature sensor 23, the coolant temperature can be monitored in real time, providing temperature data for the operation of the refrigeration unit 16 and the water pump 14, realizing precise control of the cooling system, and ensuring that the coolant temperature always meets the cooling requirements of the reactor. The number of cooling fins 17 is several.

[0030] The flow accuracy of the corrosion-resistant gear pump 4 is ±0.2%, and the frequency of the ultrasonic atomization generator 7 is 1.7 MHz.

[0031] Example 1:

[0032] Preparation process of nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control:

[0033] A: First, prepare a 0.5 mol / L aqueous solution of yttrium acetate as the raw material in yttrium salt solution storage tank 1, with a viscosity of 2.1±0.1 cP and a surface tension of 28 mN / m. At the same time, add 0.5 wt% polyethylene glycol PEG-4000 as a dispersant;

[0034] B: The precursor solution is delivered by a corrosion-resistant gear pump 4, and the mass flow meter 6 monitors the liquid flow in real time, and the flow rate is controlled at 8 mL / min. At the same time, the gas mass flow controller 10 controls the flow of the carrier gas N2 and the reaction gas O2, and the gas pressure is controlled at 0.3 MPa. The liquid and gas are mixed and atomized through a dual-fluid atomizing nozzle 8, wherein the ultrasonic atomizing generator 7 has a frequency of 1.7 MHz, which can efficiently convert the liquid into tiny droplets, and finally form droplets with an average particle size of D50 = 8 μm. This process is based on a double closed-loop collaborative control system, in which the liquid flow rate is dynamically coupled with the atomizing gas pressure, and follows the atomization stability model Qg = k·Ql·ρQg is the gas flow rate, Ql is the liquid flow rate, and ρ is the solution density, ensuring that the atomization process is stable and produces uniform and fine droplets;

[0035] C: The carrier gas carries the droplets into the vertical tubular reactor 9, which has three independent temperature zones. The droplets first enter the preheating zone at 300°C and stay there for 2 seconds. The main purpose is to remove the solvent and preliminarily dry the droplets; then enter the reaction zone at 800°C, with a heating rate of 500°C / s and stay for 1.5 seconds. The precursor decomposes at this stage; finally enter the slow cooling zone at 500°C, stay for 30 seconds, and pass a 5% H2 / Ar mixed gas for crystal form regulation. During the pyrolysis process, the O2 concentration is controlled in stages, with a pyrolysis zone of 15 vol% to provide sufficient oxygen for the decomposition of the precursor and a slow cooling zone of 2 vol% to prevent excessive oxidation of the product during the cooling process, thereby ensuring the crystal structure and performance of the product;

[0036] D: The products after pyrolysis are recovered by electrostatic collector 19 and cyclone separator 20. The voltage of electrostatic collector 19 is set to 25kV. The high voltage electric field is used to charge the product particles and adsorb them on the electrode plates. The distance between the electrode plates is 50mm. The cyclone separator 20 is made of 316L stainless steel. The centrifugal force further separates and collects the remaining product particles to achieve efficient product recovery.

[0037] E: The dual-fluid atomizing nozzle 8 adopts a silicon carbide lining structure with a surface roughness of Ra < 0.1μm. The smooth lining surface can reduce the adhesion of impurities in the precursor solution. Every 30 seconds, the system will control the electric valve on the surface of the air pipe 11 to open, so that the high-pressure N2 inside the nitrogen bottle 12 is ejected from the air pipe 11. The powerful air pressure impact force is used to quickly blow away the precursor impurities and scaling attached to the inner wall and outlet of the dual-fluid atomizing nozzle 8. Due to the intermittent injection design of the pulse gas circuit, it does not affect the normal atomization work, and can clean the nozzle in time to maintain its good atomization performance, avoid the problem of poor atomization effect and reduced production efficiency due to blockage, reduce the frequency of manual cleaning or replacement of the nozzle, and reduce maintenance costs and equipment loss;

[0038] F: When the temperature of the vertical tubular reactor 9 exceeds the standard, the cooling water tank 2, the water pump 14, the cooling coil 15, the refrigeration unit 16 and the temperature sensor 23 work together to cool the vertical tubular reactor 9. The temperature sensor 23 in the cooling water tank 2 monitors the water temperature in real time. The refrigeration end of the refrigeration unit 16 cools and lowers the temperature of the water in the cooling water tank 2 through the cooling plate 17 to ensure that there is a low-temperature cooling medium in the water tank. At the same time, the water pump 14 starts to work, pumps out the low-temperature water in the cooling water tank 2, and transports it through the cooling coil 15. The hot water is sent to the inner wall of the vertical tubular reactor 9, and the cooling coil 15 surrounds the inside of the vertical tubular reactor 9. The low-temperature water flows in the cooling coil 15 and absorbs the heat in the vertical tubular reactor 9 through heat exchange, so that the temperature of the reactor is reduced. The hot water after absorbing the heat flows back to the cooling water tank 2 through the reflux pipe 22. This cycle is repeated, continuously taking away the heat in the reactor, achieving rapid cooling, preventing the reaction from getting out of control, protecting the safety of the equipment, avoiding quality problems such as abnormal crystal structure and increased impurities in the product, and improving the product qualification rate.

[0039] Example 2:

[0040] Preparation process of nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control:

[0041] A: First, prepare a 0.5 mol / L yttrium nitrate-ethanol solution in yttrium salt solution storage tank 1. The viscosity of the solution is 2.1±0.1 cP and the surface tension is 28 mN / m. At the same time, 0.5 wt% polyethylene glycol PEG-4000 is added as a dispersant.

[0042] B: The precursor solution is delivered by a corrosion-resistant gear pump 4, and the mass flow meter 6 monitors the liquid flow in real time, and the flow rate is controlled at 8 mL / min. At the same time, the gas mass flow controller 10 controls the flow of the carrier gas N2 and the reaction gas O2, and the gas pressure is controlled at 0.3 MPa. The liquid and gas are mixed and atomized through a dual-fluid atomizing nozzle 8, wherein the ultrasonic atomizing generator 7 has a frequency of 1.7 MHz, which can efficiently convert the liquid into tiny droplets, and finally form droplets with an average particle size of D50 = 8 μm. This process is based on a double closed-loop collaborative control system, in which the liquid flow rate is dynamically coupled with the atomizing gas pressure, and follows the atomization stability model Qg = k·Ql·ρQg is the gas flow rate, Ql is the liquid flow rate, and ρ is the solution density, ensuring that the atomization process is stable and produces uniform and fine droplets;

[0043] C: The carrier gas carries the droplets into the vertical tubular reactor 9, which has three independent temperature zones. The droplets first enter the preheating zone at 300°C and stay there for 2 seconds. The main purpose is to remove the solvent and preliminarily dry the droplets; then enter the reaction zone at 800°C, with a heating rate of 500°C / s and stay for 1.5 seconds. The precursor decomposes at this stage; finally enter the slow cooling zone at 500°C, stay for 30 seconds, and pass a 5% H2 / Ar mixed gas for crystal form regulation. During the pyrolysis process, the O2 concentration is controlled in stages, with a pyrolysis zone of 15 vol% to provide sufficient oxygen for the decomposition of the precursor and a slow cooling zone of 2 vol% to prevent excessive oxidation of the product during the cooling process, thereby ensuring the crystal structure and performance of the product;

[0044] D: The products after pyrolysis are recovered by electrostatic collector 19 and cyclone separator 20. The voltage of electrostatic collector 19 is set to 25kV. The high voltage electric field is used to charge the product particles and adsorb them on the electrode plates. The distance between the electrode plates is 50mm. The cyclone separator 20 is made of 316L stainless steel. The centrifugal force further separates and collects the remaining product particles to achieve efficient product recovery.

[0045] E: The dual-fluid atomizing nozzle 8 adopts a silicon carbide lining structure with a surface roughness of Ra < 0.1μm. The smooth lining surface can reduce the adhesion of impurities in the precursor solution. Every 30 seconds, the system will control the electric valve on the surface of the air pipe 11 to open, so that the high-pressure N2 inside the nitrogen bottle 12 is ejected from the air pipe 11. The powerful air pressure impact force is used to quickly blow away the precursor impurities and scaling attached to the inner wall and outlet of the dual-fluid atomizing nozzle 8. Due to the intermittent injection design of the pulse gas circuit, it does not affect the normal atomization work, and can clean the nozzle in time to maintain its good atomization performance, avoid the problem of poor atomization effect and reduced production efficiency due to blockage, reduce the frequency of manual cleaning or replacement of the nozzle, and reduce maintenance costs and equipment loss;

[0046] F: When the temperature of the vertical tubular reactor 9 exceeds the standard, the cooling water tank 2, the water pump 14, the cooling coil 15, the refrigeration unit 16 and the temperature sensor 23 work together to cool the vertical tubular reactor 9. The temperature sensor 23 in the cooling water tank 2 monitors the water temperature in real time. The refrigeration end of the refrigeration unit 16 cools and lowers the temperature of the water in the cooling water tank 2 through the cooling plate 17 to ensure that there is a low-temperature cooling medium in the water tank. At the same time, the water pump 14 starts to work, pumps out the low-temperature water in the cooling water tank 2, and transports it through the cooling coil 15. The hot water is sent to the inner wall of the vertical tubular reactor 9, and the cooling coil 15 surrounds the inside of the vertical tubular reactor 9. The low-temperature water flows in the cooling coil 15 and absorbs the heat in the vertical tubular reactor 9 through heat exchange, so that the temperature of the reactor is reduced. The hot water after absorbing the heat flows back to the cooling water tank 2 through the reflux pipe 22. This cycle is repeated, continuously taking away the heat in the reactor, achieving rapid cooling, preventing the reaction from getting out of control, protecting the safety of the equipment, avoiding quality problems such as abnormal crystal structure and increased impurities in the product, and improving the product qualification rate.

[0047] In summary: the system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control solves the problems of the traditional preparation process lacking high-precision atomization control and lacking nozzle cleaning and emergency cooling functions through the cooperation of a cooling water tank 2, an online conductivity meter 3, a corrosion-resistant gear pump 4, a pulse damping system 5, a mass flow meter 6, an ultrasonic atomization generator 7, a dual-fluid atomization nozzle 8, a vertical tubular reactor 9, a gas mass flow controller 10, an air pipe 11, a nitrogen bottle 12, a laser diffractometer 13, a water pump 14 and a cooling coil 15.

Claims

1. A system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control, comprising an yttrium salt solution storage tank (1) and a cooling water tank (2), characterized in that: An online conductivity meter (3) is fixedly connected to the bottom of the left side of the yttrium salt solution storage tank (1), the discharge end of the yttrium salt solution storage tank (1) is connected to a corrosion-resistant gear pump (4) through a pipeline, the discharge end of the corrosion-resistant gear pump (4) is connected to a pulse damping system (5) through a pipeline, the right side of the pulse damping system (5) is connected to a mass flow meter (6) through a pipeline, the right end of the mass flow meter (6) is connected to an ultrasonic atomization generator (7) through a pipeline, the output end of the ultrasonic atomization generator (7) is connected to a dual-fluid atomization nozzle (8) through a pipeline, the right side of the dual-fluid atomization nozzle (8) is connected to a vertical tubular reactor (9) through bolts, the left side of the top of the dual-fluid atomization nozzle (8) is connected to a gas mass flow controller (10), and the right side of the bottom of the dual-fluid atomization nozzle (8) is connected to a gas The vertical tubular reactor (9) is provided with a tube (11), the bottom end of the air tube (11) is connected to a nitrogen bottle (12), the left side of the top of the vertical tubular reactor (9) is fixedly connected to a laser diffractometer (13), the top of the left side of the cooling water tank (2) is connected to a water pump (14) by bolts, the inner wall of the vertical tubular reactor (9) is fixedly connected to a cooling coil (15), the right side of the cooling water tank (2) is fixedly connected to a refrigeration unit (16), the refrigeration end of the refrigeration unit (16) passes through the interior of the cooling water tank (2) and is connected to a cooling plate (17) by bolts, the top of the right side of the vertical tubular reactor (9) is connected to a pressure relief valve (18), the discharge end of the vertical tubular reactor (9) is connected to an electrostatic collector (19) by a pipeline, and the discharge end of the electrostatic collector (19) is connected to a cyclone separator (20) by a pipeline.

2. The system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to claim 1, characterized in that: The right end of the dual-fluid atomizing nozzle (8) penetrates into the interior of the vertical tubular reactor (9), and the detection end of the laser diffractometer (13) penetrates into the interior of the vertical tubular reactor (9).

3. The system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to claim 1, characterized in that: A pressure gauge (21) is fixedly connected to the right side of the top of the vertical tubular reactor (9), the liquid outlet end of the water pump (14) passes through the vertical tubular reactor (9) and is connected to the top end of the cooling coil (15), and the liquid inlet end of the water pump (14) passes through the interior of the cooling water tank (2).

4. The system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to claim 1, characterized in that: A reflux pipe (22) is fixedly connected to the left side of the bottom of the cooling water tank (2), and the left end of the reflux pipe (22) penetrates into the interior of the vertical tubular reactor (9) and is connected to the bottom end of the cooling coil (15).

5. The system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to claim 1, characterized in that: The left side of the top of the cooling water tank (2) is connected to a water injection pipe, and a pipe cap is provided on the surface of the water injection pipe through a threaded sleeve.

6. The system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to claim 1, characterized in that: A temperature sensor (23) is connected to the right side of the bottom of the inner cavity of the cooling water tank (2) via bolts, and the number of the cooling fins (17) is several.

7. The system for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to claim 1, characterized in that: The flow accuracy of the corrosion-resistant gear pump (4) is ±0.2%, and the frequency of the ultrasonic atomization generator (7) is 1.7 MHz.

8. The process for preparing nano-yttrium oxide by spray pyrolysis based on double closed-loop fluid control according to any one of claims 1 to 7: A: First, prepare a 0.5 mol / L yttrium nitrate-ethanol solution in the yttrium salt solution storage tank (1) with a viscosity of 2.1±0.1 cP and a surface tension of 28 mN / m, and add 0.5 wt% polyethylene glycol (PEG-4000) as a dispersant; B: The precursor solution is transported by a corrosion-resistant gear pump (4), and the mass flow meter (6) monitors the liquid flow in real time. The flow rate is controlled at 0.5-20 mL / min, which is set to 8 mL / min in this process. At the same time, the gas mass flow controller (10) controls the flow of the carrier gas (N2) and the reaction gas (O2), and the gas pressure is controlled at 0.1-0.5 MPa, which is 0.3 MPa in this process. The liquid and gas are mixed and atomized through a dual-fluid atomizing nozzle (8), wherein the ultrasonic atomizing generator (7) has a frequency of 1.7 MHz, which can efficiently convert the liquid into tiny droplets, and finally form droplets with an average particle size of D50 = 8 μm. This process is based on a double closed-loop collaborative control system, in which the liquid flow rate is dynamically coupled with the atomizing gas pressure, and follows the atomization stability model Qg = k·Ql·ρ (Qg is the gas flow rate, Ql is the liquid flow rate, and ρ is the solution density), ensuring that the atomization process is stable and produces uniform and fine droplets; C: The carrier gas carries the droplets into the vertical tubular reactor (9), which has three independent temperature zones. The droplets first enter the preheating zone (300°C) and stay there for 2 seconds. The main purpose is to remove the solvent and make the droplets initially dry; then enter the reaction zone (800°C), with a heating rate of 500°C / s and stay for 1.5 seconds. The precursor decomposes at this stage; finally enter the slow cooling zone (500°C), stay for 30 seconds, and pass 5% H2 / Ar mixed gas to adjust the crystal form. During the pyrolysis process, the O2 concentration is controlled in stages. The pyrolysis zone is 15vol% to provide sufficient oxygen for the decomposition of the precursor, and the slow cooling zone is 2vol% to prevent the product from being over-oxidized during the cooling process, thereby ensuring the crystal structure and performance of the product. D: The products after pyrolysis are recovered by an electrostatic collector (19) and a cyclone separator (402). The voltage of the electrostatic collector (19) is adjustable from 0 to 30 kV, and is set to 25 kV in this process. The high voltage electric field is used to charge the product particles and adsorb them on the plates. The distance between the plates is 50 mm. The cyclone separator (20) is made of 316L stainless steel and further separates and collects the remaining product particles through centrifugal force, achieving efficient product recovery. E: The dual-fluid atomizing nozzle (8) adopts a silicon carbide lining structure with a surface roughness of Ra < 0.1 μm. The smooth lining surface can reduce the adhesion of impurities in the precursor solution. Every 30 seconds, the system will control the electric valve on the surface of the air pipe (11) to open, so that the high-pressure N2 inside the nitrogen bottle (12) is ejected from the air pipe (11). The powerful air pressure impact force is used to quickly blow away the precursor impurities and scale attached to the inner wall and outlet of the dual-fluid atomizing nozzle (8). Due to the interval injection design of the pulse gas circuit, it does not affect the normal atomization work, and can clean the nozzle in time to maintain its good atomization performance, avoid the problem of poor atomization effect and reduced production efficiency caused by blockage, reduce the frequency of manual cleaning or replacement of the nozzle, and reduce maintenance costs and equipment loss; F: When the temperature of the vertical tubular reactor (9) exceeds the standard, the cooling water tank (2), the water pump (14), the cooling coil (15), the refrigeration unit (16) and the temperature sensor (23) work together to cool the vertical tubular reactor (9). The temperature sensor (23) in the cooling water tank (2) monitors the water temperature in real time. The refrigeration end of the refrigeration unit (16) cools and lowers the temperature of the water in the cooling water tank (2) through the cooling plate (17) to ensure that there is a low-temperature cooling medium in the water tank. At the same time, the water pump (14) starts to work and pumps out the low-temperature water in the cooling water tank (2). The cooling coil (15) is transported to the inner wall of the vertical tubular reactor (9), and the cooling coil (15) surrounds the interior of the vertical tubular reactor (9). Low-temperature water flows in the cooling coil (15) and absorbs heat in the vertical tubular reactor (9) through heat exchange, thereby reducing the temperature of the reactor. The hot water after absorbing the heat flows back to the cooling water tank (2) through the return pipe (22). This cycle is repeated, continuously taking away the heat in the reactor, achieving rapid cooling, preventing the reaction from getting out of control, protecting the safety of the equipment, avoiding quality problems such as abnormal crystal structure and increased impurities in the product, and improving the product qualification rate.

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