Pressure-resistant supergravity reaction device and method for preparing low-sodium pseudo-boehmite

Abstract

This invention discloses a pressure-resistant, high-gravity reaction device and a method for preparing low-sodium boehmite. The device includes a packing layer, which is divided into an upper packing layer and a lower packing layer. The upper packing layer is equipped with an upper baffle and an upper packing annular column. The upper baffle is a disk with one or more concentric concave annular grooves, and the upper packing annular column is a multi-layered concentric annular column filled with packing. The lower packing layer is equipped with a lower baffle and a lower packing annular column. The lower packing annular column is a multi-layered concentric annular column filled with packing, and the lower baffle is a disk with at least one concentric concave annular groove, which is arranged radially from the outer edge to the inner edge. The special packing structure solves the sealing problem without adding new sealing devices, controls the fluid flow path, is suitable for pressurized conditions, and improves mass transfer efficiency. Using this device in processes such as carbon fractionation for preparing boehmite slurry, rapid slurry heating, and sodium-free aging not only prevents the generation of impurities but also effectively reduces the sodium content of the product.

Description

Technical Field

[0001] This invention relates to a pressure-resistant hypergravity reaction device and a method for preparing low-sodium pseudoboehmite, belonging to the fields of hypergravity chemical process intensification technology and aluminum hydroxide production. Background Technology

[0002] High-gravity devices used for gas-liquid two-phase flow include counter-current, co-current, and cross-current rotating packed beds. Rotating packed beds directly connected to the atmosphere and used under certain pressure conditions present dynamic sealing problems. Cross-current rotating packed beds only have a dynamic sealing problem between the drive shaft and the housing. However, co-current and counter-current rotating packed beds also have a dynamic sealing problem between the inner edge of the packing layer and the gas outlet. The dynamic sealing of cross-current rotating packed beds is similar to that of drive shaft sealing in pumps and reactors. Since the drive shaft is small, ordinary skeleton oil seals and mechanical seals can solve the dynamic sealing problem between the drive shaft and the housing. Therefore, the sealing problem of cross-current rotating packed beds has been solved, and pressure-resistant cross-current rotating packed beds have been applied. Counter-current and co-current rotating packed beds require driving the gas and liquid phases to flow inside the rotating packing to achieve counter-current or co-current contact. A dynamic sealing device should be installed between the inner edge of the packing layer and the gas outlet to prevent short-circuiting of the gas without contacting the liquid inside the rotating packing layer. For larger counter-current and co-current rotating packed beds, the inner edge of the packing layer is large and the distance from the gas outlet is far, making it difficult to guarantee precision. Ordinary sealing devices require a high degree of precision and cannot be connected to rotating packing beds. Therefore, the dynamic sealing problem of pressure-resistant counter-current and parallel-flow rotating packing beds is quite challenging. Counter-current and parallel-flow rotating packing beds cannot solve the dynamic sealing problem, which will lead to gas leakage and make them unsuitable for use in chemical production processes that are directly connected to the atmosphere and maintain a certain pressure.

[0003] Chinese patent CN106237971A, "A High-Pressure Hypergravity Rotating Bed," utilizes an internal and external magnet drive system and designs a sealing device between the motor drive shaft and the housing, avoiding direct insertion of the motor drive shaft into the rotating packed bed housing. Chinese patent CN107511116A, "A High-Temperature, High-Pressure Hypergravity Hydrogenation Reactor and Its Application," incorporates an ultrasonic probe, a rotating disk, and a sealing device. Both of these inventions address the sealing problem between the drive shaft and the housing, but they do not solve the sealing problem of counter-current rotating packed beds. Chinese patents, including CN103831075B "A Motor-Built Hypergravity Rotary Bed Device and Its Application," all integrate the rotating packed bed within the tank. While this increases the pressure resistance of the equipment, it still fails to control the counter-current or co-current contact of gas and liquid within the packing layer, thus not solving the sealing problem of the counter-current rotating packed bed. Chinese patent CN115738902A discloses a pressure-resistant hypergravity reactor, designing a sealing device for a counter-current rotating packed bed, which includes complex labyrinth seals and mechanical seals, resulting in a complex structure requiring high precision in manufacturing. Chinese patent CN101549274B discloses a hypergravity rotating bed device, mentioning a gas sealing device for the counter-current bed, but without specifying its structure.

[0004] Stator-rotor and counter-current shearing rotary packed beds, like counter-current rotary packed beds, also involve the sealing problem of controlling the gas flow path. Chinese patents CN1290605C (stator-rotor reactor), CN114247264A (a high-gravity coupled ultrasonic extraction and regeneration device), CN101745245B (a multi-stage counter-current rotary bed reactive distillation device), CN104760931B (a photocatalytic water-to-hydrogen reaction device), CN114308323A (a high-shear preparation device for nanofluids), CN113941223A (a device for capturing CO2), and CN114259867A (a device for simultaneous desulfurization and denitrification of coal-fired flue gas) are all stator-rotor rotary packed beds, and all involve an alternating nested upper stator and lower rotor. This structure exhibits good effects in enhancing dispersion, mixing, and mass transfer. However, a horizontal gap still exists between the stator and rotor, leading to significant gas leakage under high-speed rotation and high gas pressure. Chinese patents CN103463829B (disclosing a reverse shear rotating packed bed mass transfer and reaction device), CN103463936B (disclosing a device for removing sulfur dioxide from waste gas), CN103480259B (disclosing a flue gas desulfurization device), and CN112933885B (disclosing a method and device for selectively absorbing ammonia from melamine tail gas under hypergravity non-equilibrium) all involve reverse shear rotating packed beds, addressing the issues of counter-rotation of the upper and lower rotors and sealing. All employ labyrinth seals to solve the gas sealing problem. Labyrinth seal devices require high precision. While the labyrinth seal combined with high-speed rotation can alleviate gas leakage under normal pressure, achieving such high precision is not feasible for large-scale hypergravity equipment, and high installation accuracy is also required.

[0005] The challenge of dynamic sealing between the packing layer and the gas outlet in counter-current rotating packed beds lies in the dynamic sealing of a high-speed rotating object, especially when the packing layer is large. Its unique characteristics include: 1) high packing layer rotation speed and a large sealing size range; 2) the sealing area is a blank zone, without a rotating shaft or any support, and the inner edge of the packing layer does not need to bear torque or provide transmission; 3) this sealing location is in direct contact with the material, and no lubricant, sealing oil, or coolant can be stored or added; 4) this sealing location is inside the shell, with both the inner and outer sides of the sealing device directly contacting the gas, effectively preventing gas flow between the rotating object and the stationary shell. Existing mechanical seals are complex and bulky, unsuitable for sealing large-sized rotating devices. The precision of labyrinth seals used in hypergravity devices cannot be guaranteed, resulting in poor sealing performance and unsuitability for high gas pressure conditions. Therefore, this invention designs a pressure-resistant counter-current and co-current hypergravity device that does not require additional sealing devices. By changing the structure of the packing layer, it not only solves the sealing problem of this type of device, but also enhances the gas-liquid mass transfer and reaction process, making it more suitable for large-size hypergravity devices.

[0006] Boehmite (a crystalline form of aluminum hydroxide) prepared under certain conditions possesses advantages such as high pore volume, large specific surface area, and colloidal properties. Therefore, boehmite is used as a binder for catalysts and a precursor for the preparation of activated alumina (γ-Al₂O₃). It is also used to prepare reforming catalysts and hydrocracking catalysts with nano-alumina as the support, exhibiting high economic value. However, the production requirements for high-quality boehmite are quite stringent. Reducing the sodium oxide content and improving colloidal properties and pore volume can enhance the catalytic performance of boehmite. Therefore, most methods for preparing boehmite for catalysts employ the aluminum alkoxide process or use chlorine- and sodium-free raw materials. However, sodium aluminate is the lowest-cost raw material, a direct product of bauxite smelting, requiring no secondary processing. Sodium-free raw materials, on the other hand, require secondary processing, increasing production costs. Chinese patent CN115259189A discloses a hydrothermal treatment technology for producing boehmite from ammonium aluminum carbonate, and CN112939039B discloses an aluminum alkoxide process technology. Chinese patent CN109179461B discloses a low-sodium boehmite and its preparation method, which still achieves a sodium oxide content of less than 0.1% through multiple filtrations and filtrate exchange. Zhang Hao published a dissertation entitled "Research on a New Process for Low-Alkali Aging Production of Boehmite," which studied the effects of aging alkalinity, temperature, time, and solid-liquid separation rate on the sodium oxide content in boehmite. The reaction time was 15 minutes, and after three washings, the sodium oxide content in the product was approximately 0.2%, the colloidal properties were approximately 96%, and the impurities were approximately 1.0%. Du Shanguo et al.'s research, "Research on Low-Alkalinity Aging Process of Boehmite," has similar content and results to Zhang Hao's work. The petroleum catalyst industry has increasingly higher requirements for the sodium content of boehmite. Improving oil quality necessitates continuously reducing the sodium content of boehmite; therefore, developing a low-cost, low-sodium boehmite preparation process is essential.

[0007] The carbonation process is a production process for preparing boehmite using sodium aluminate and carbon dioxide. This process is relatively simple, with safe and widely available raw materials and the lowest production cost. Chinese patent CN85100161A, "Producing Boehmite by Carbonation Process (CO2 Method)," uses a bubble column reactor to carbonate and gel at low temperature and low concentration to obtain boehmite, but the reaction time is relatively long. Chinese patent CN1168659C, "A Method for Preparing Activated Alumina," also discloses a bubble column method for preparing activated alumina. Both of these methods use bubble column reactors, which are large in volume and occupy a lot of space. They are also intermittent processes with long carbonation times, making the reaction prone to unevenness and the formation of boehmite impurities.

[0008] As a process intensification technology in chemical engineering, hypergravity enhancement technology has received widespread attention and research in the preparation of aluminum hydroxide and boehmite. Chinese patent CN1116185A, "Preparation Method of Ultrafine Particles," discloses a one-step method for directly preparing ultrafine aluminum hydroxide under hypergravity conditions in a rotating packed bed. Chinese patent CN1258639A, "Preparation Method of Ultrafine Aluminum Hydroxide," discloses a two-step method for preparing ultrafine aluminum hydroxide under hypergravity conditions involving carbonic acid decomposition and hydrothermal treatment, yielding ultrafine aluminum hydroxide with an average particle size of approximately 1-5 nm and an aspect ratio of 5-100 nm. Literature such as "Research on the Preparation of γ-Al₂O₃ by Continuous Carbon Separation under Hypergravity" reports hypergravity carbon separation reaction processes. All of the above methods employ cyclic reactions and batch production, and the cross-flow rotating packed bed reaction has low efficiency.

[0009] A pressure-resistant countercurrent hypergravity reactor is used to increase the reaction pressure, thereby improving the reaction rate and efficiency. This results in aluminum hydroxide with small particle size and minimal particle agglomeration, reducing the formation of the impurity boehmite. Rapid heating and high-temperature filtration are employed to quickly separate the solid from the sodium-containing solution. Simultaneously, the crystallinity of the boehmite is rapidly increased, preventing the secondary spontaneous decomposition of sodium aluminate and the formation of boehmite. Aging treatment in a sodium-free environment reduces the entrainment and inclusion of sodium ions during crystal growth, thus producing low-sodium boehmite with high colloidal properties. Therefore, this invention proposes a pressure-resistant hypergravity reactor and a method for preparing high-performance boehmite. Summary of the Invention

[0010] The present invention aims to provide a pressure-resistant hypergravity reaction device and a method for preparing high-performance pseudoboehmite using the device.

[0011] This invention divides the packing layer structure into an upper and lower cross-packing structure. The upper packing layer is directly fixed to the shell, so that gas must enter the packing layer. The rotating lower packing layer and the stationary upper packing layer form a strong gas resistance. The lower and upper packing layers directly form a certain cavity area. The packing layer also has a large gap, which can prevent gas leakage under high pressure, thus realizing a pressure-resistant hypergravity device that is directly connected to the atmosphere. This device increases the pressure of carbon dioxide gas, accelerates the gas-liquid mass transfer rate of carbon dioxide, improves the reaction rate, achieves rapid reaction, precise control of the reaction endpoint, accelerates crystal nucleation, and enables continuous production. Rapid heating of the slurry quickly increases the crystallinity of boehmite, avoiding the accelerated hydrolysis of sodium aluminate during heating to form impurities like boehmite, and relaxes the carbon reaction endpoint conditions. Rapid filtration separates sodium ions from boehmite, allowing the boehmite to age in a sodium-free or low-sodium environment, reducing the entrainment and encapsulation of sodium ions during boehmite growth, and decreasing washing difficulty and water usage. It improves product performance, producing boehmite products with good colloidal properties, high pore volume, large specific surface area, and low sodium oxide content. This invention innovatively improves the packing layer structure, eliminates the sealing device, and simplifies the installation of the packing components, improving the effectiveness of the original packing structure while effectively preventing gas leakage without passing through the packing, achieving good sealing performance, and is suitable for gas-liquid reactions under certain pressure.

[0012] This invention provides a pressure-resistant hypergravity reaction device, comprising a packing layer, a motor, a shell, a liquid distributor, a gas inlet, a gas outlet, a liquid inlet, a liquid outlet, and a drive shaft;

[0013] The packing layer is divided into an upper packing layer and a lower packing layer. The upper packing layer includes an upper baffle and upper packing annular columns. The upper baffle is a disc with one or more concentric annular grooves and is fixed to the upper part of the housing. The upper packing annular columns are multi-layered concentric annular columns filled with packing material and are located between the upper and lower baffles. They can be fixed to either the upper or lower baffle. The lower packing layer includes a lower baffle and lower packing annular columns. The lower packing annular columns are multi-layered concentric annular columns filled with packing material. The lower baffle is a disc with at least one concentric annular groove, located between the lower packing annular columns, preferably between the outermost two layers. The lower baffle is fixed to a drive shaft connected to the motor and rotates with the drive shaft. The concentric annular grooves are arranged radially from the outer edge to the inner edge. The number of concentric annular grooves on the upper and lower baffles is designed according to the size of the packing layer and the pressure resistance.

[0014] The upper packing ring column is fixedly installed on the downward protruding annular surface of the concave annular groove of the upper baffle; the lower packing ring column is fixed on the lower baffle and located in the space enclosed by the upward protruding annular surface of the concave annular groove of the upper baffle; the upper and lower packing ring columns are nested alternately, with the lower packing ring column embedded between the two concave annular grooves of the upper baffle, and the outermost upper packing ring column embedded in the concave annular groove of the lower baffle.

[0015] The upper packing ring column of the upper packing layer described in this invention can also be installed on the lower baffle of the lower packing layer. Except for the outermost upper packing ring column nested in the concave concentric ring groove of the lower packing layer, the upper packing ring column and the lower packing ring column are nested together to form a whole.

[0016] The lower baffle of the present invention has multiple liquid channels on the outer edge surface of the concave annular groove, which facilitates the outflow of liquid entering the annular groove. The liquid channels are uniformly spaced circular holes along the circumference, with openings along the transverse or longitudinal lines of the outer edge surface of the concave annular groove. At least one concave annular groove is provided on both the upper and lower baffles, arranged radially towards the center.

[0017] The upper baffle of this invention can be directly and tightly fixed to the shell, or the upper baffle can be kept horizontal to the plane of the shell. The inner and outer edges of the upper baffle are respectively fixed to the sides of two supporting sealing rings, and the two supporting sealing rings are directly fixed to the upper part of the shell. The outer edge of the upper baffle is provided with an eave, which is lower than the top surface of the upper baffle.

[0018] The packing layer, liquid inlet, drive shaft, and housing of this invention are concentric circles. The liquid inlet is connected to a liquid distributor, which is located inside the packing layer. The gas inlet and gas outlet are interchangeable to achieve co-current or counter-current contact. In one case, the liquid inlet is nested within the gas outlet, forming an inner and outer sleeve structure, allowing counter-current contact between the gas and liquid phases, while the gas inlet is located on one side of the housing. In another case, the liquid inlet is nested within the gas inlet, allowing co-current contact between the gas and liquid phases, while the gas outlet is located on one side of the housing.

[0019] The packing material in the packing layer described in this invention includes various chemical packing materials and catalysts.

[0020] The pressure-resistant hypergravity reaction apparatus provided by this invention can be used to prepare pseudoboehmite, specifically including the following steps: Sodium aluminate solution and CO2-containing gas are continuously introduced into the pressure-resistant hypergravity apparatus for reaction. Under the action of a hypergravity field, rapid reaction is achieved, the reaction endpoint is precisely controlled, and a slurry is continuously generated. The slurry is rapidly heated and rapidly filtered to obtain a gel. The gel is rapidly dispersed in a weakly alkaline or neutral aqueous solution at a certain temperature and aged, followed by washing, filtration, and drying processes to prepare pseudoboehmite powder.

[0021] The specific process conditions for the preparation method of pseudoboehmite of the present invention are as follows: sodium aluminate solution concentration of 0.1~2.0 mol / L, Al2O3 content of 5~100 g / L, carbon dioxide content in the gas of 15%~100%, pressure of 0.1~1.0 MPa, and reaction temperature of 10~40°C. The reaction conditions are as follows: ℃, centrifugal rotation speed 100~2000rpm; pH of slurry 8~13; rapid heating time of slurry less than 15min, heating temperature 80~90℃; rapid filtration time less than 30min, preferably controlled within 10min; weakly alkaline or neutral aqueous solution is a sodium-free solution, including solutions with added inorganic electrolytes such as ammonium carbonate and ammonium bicarbonate, dispersants, grain growth regulators, pore expanders, etc., as well as pure water and deionized water; dispersants include triethylhexylphosphonic acid, polyacrylamide, etc.; grain growth regulators are polyhydroxy alcohols, specifically glucose, gluconic acid, etc.; pore expanders are melamine, urea, etc.; temperature of weakly alkaline or neutral aqueous solution 70~99℃, aging time 0.5~3.5h; washing requirement is that the pH of the liquid after washing is 7~9; drying temperature 80-110℃.

[0022] The pseudoboehmite prepared by this invention has a sodium oxide content of less than 0.08%, a colloidal property of greater than 96%, and a pore volume greater than 0.36 cm³. 3 / g, specific surface area greater than 360 m² 2 / g.

[0023] The pressure-resistant supergravity device provided by this invention can also be applied to chemical unit operations such as gas-liquid two-phase reaction, absorption, stripping, heat exchange, and crystallization.

[0024] The beneficial effects of this invention are:

[0025] (1) This invention provides a pressure-resistant hypergravity device, which adopts a special packing structure, solves the sealing problem of this type of device without adding a new sealing device, controls the gas flow path, meets the pressurization requirements of co-current and counter-current rotating packing beds, realizes enhanced gas-liquid mass transfer and reaction process, improves gas-liquid mass transfer rate and reaction rate, enriches the packing structure of hypergravity device, broadens the application range of hypergravity device, and is more suitable for large-size hypergravity device.

[0026] (2) This invention not only enables rapid and continuous preparation of boehmite, but also significantly improves the performance of boehmite products. It not only prevents the generation of impurities, but also effectively reduces the sodium content of the products. Not only is the high sodium carbonate concentration of the first filtrate suitable for direct use as raw material for sintered bauxite, but it also saves water consumption in the washing process. Attached Figure Description

[0027] Figure 1This is a schematic diagram of the counter-current pressure-resistant supergravity device (3 upper baffle concave annular grooves).

[0028] Figure 2 for Figure 1 Three-view diagram of the upper and middle packing layers.

[0029] Figure 3 for Figure 1 Cross-sectional view of the upper and middle packing layers.

[0030] Figure 4 for Figure 1 Three-view diagram of the middle and lower packing layer.

[0031] Figure 5 for Figure 1 Cross-sectional view of the middle and lower packing layers.

[0032] Figure 6 The image shows the three views of the concave annular groove in the lower packing layer.

[0033] Figure 7 This is a schematic diagram of the pressure-resistant supergravity device (one upper baffle concave annular groove).

[0034] Figure 8 A process flow diagram for preparing pseudoboehmite.

[0035] Figure 9 The image shows the X-ray diffraction (XRD) pattern of the product obtained in Example 1.

[0036] In the diagram: 1: Shell; 2: Packing layer; 3: Gas inlet; 4: Liquid inlet; 5: Gas outlet; 6: Liquid outlet; 7: Liquid distributor; 8: Motor; 9: Upper baffle; 10: Upper packing annular column; 11: Lower baffle; 12: Lower packing annular column; 13: Upper baffle concave annular groove; 14: Lower baffle concave annular groove; 15: Liquid channel; 16: Eaves on the outer edge of the upper baffle; 17: Support sealing ring; 18: Drive shaft. Detailed Implementation

[0037] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments.

[0038] like Figures 1-7 As shown, a pressure-resistant hypergravity reaction device includes a packing layer 2, a motor 8, a shell 1, a liquid distributor 7, a gas inlet 3, a gas outlet 5, a liquid inlet 4, a liquid outlet 6, and a drive shaft 18.

[0039] The packing layer 2 is divided into an upper packing layer and a lower packing layer. The upper packing layer is provided with an upper baffle 9 and an upper packing annular column 10. The upper baffle 9 is a disc with one or more concentric concave annular grooves and is fixed to the upper part of the shell. The upper packing annular column is a multi-layered concentric annular column filled with packing. The lower packing layer is provided with a lower baffle 11 and a lower packing annular column 12. The lower packing annular column is a multi-layered concentric annular column filled with packing. The lower baffle is a disc with at least one concave concentric annular groove. The concave annular groove 14 of the lower baffle is located between the lower packing annular columns, preferably between the outermost two layers of the lower packing annular column 12. The lower baffle is fixed on the drive shaft connected to the motor and rotates with the drive shaft. The number of concave annular grooves in the upper and lower baffles is designed according to the size of the packing layer and the pressure resistance.

[0040] Each layer of upper packing ring column 10 is fixedly installed in the space formed by the downward protruding annular surface of the concave annular groove 13 of the upper baffle and the lower baffle; the lower packing ring column is fixed in the space enclosed by the upward protruding annular surface of the concave annular groove of the lower baffle and the upper baffle; the upper and lower packing ring columns are staggered and nested, with the lower packing ring column embedded between the two concave annular grooves of the upper baffle, and the outermost upper packing ring column embedded in the concave annular groove of the lower baffle.

[0041] The upper packing ring column 10 of the upper packing layer described in this invention can also be installed on the lower baffle of the lower packing layer. Except for the outermost upper packing ring column nested in the concave concentric ring groove of the lower packing layer, it is connected to the lower packing column to form a whole.

[0042] The lower baffle concave annular groove 14 of the present invention has multiple channels 15 on its outer edge surface, which facilitate the outflow of liquid entering the annular groove. The channels are evenly spaced circular holes along the circumference, with openings along the transverse or longitudinal lines of the outer edge surface of the concave annular groove. At least one concave annular groove is provided on both the upper and lower baffles, arranged radially towards the center.

[0043] The upper baffle of this invention can be directly and tightly fixed to the shell, or the upper baffle can be kept horizontal to the plane of the shell. The inner and outer edges of the upper baffle are respectively fixed to the sides of two supporting sealing rings 17, and the two supporting sealing rings 17 are directly fixed to the upper part of the shell. The outer edge of the upper baffle is provided with an eave, and the eave 16 of the outer edge of the upper baffle is lower than the top surface of the upper baffle.

[0044] The packing layer, liquid inlet, drive shaft, and housing described in this invention have concentric circular surfaces. The gas inlet and gas outlet are interchangeable (achieving co-current or counter-current contact). The liquid inlet is nested within the gas outlet, forming an inner and outer sleeve structure, allowing the gas and liquid phases to achieve counter-current contact; the liquid inlet is nested within the gas inlet, allowing the gas and liquid phases to achieve co-current contact.

[0045] The packing material in the packing layer described in this invention includes various chemical packing materials and catalysts.

[0046] The following specific examples illustrate the method for rapidly and continuously preparing high-performance pseudoboehmite using the aforementioned countercurrent pressure-resistant hypergravity device. Example 1

[0047] A sodium aluminate solution, an intermediate product of the industrial Bayer process for producing alumina, was prepared at a concentration of 0.2 mol / L and placed in the feed tank. The controller of the high-gravity reactor was turned on, and the reactor was operated, with the rotation speed of the rotating bed packing material controlled at 1000 rpm. Carbon dioxide gas at a certain pressure (60% by volume) was introduced into the high-gravity reactor, maintaining a gas pressure of 0.17 MPa. The feed pump was turned on, and the sodium aluminate solution was transported to the high-gravity reactor via a liquid flow meter. The sodium aluminate solution then entered the reactor packing material through a liquid distributor. The sodium aluminate solution and carbon dioxide underwent gas-liquid contact in the packing material. The pH of the liquid at the liquid outlet was 10.5, reaching the reaction control endpoint, and the solution was then transferred to a liquid storage tank, achieving a rapid and continuous production process. The liquid was rapidly heated to 90°C for 10 minutes and then rapidly filtered for 1 minute. The gel was dispersed in deionized water at 90°C, stirred until completely and uniformly dispersed, and aged by constant temperature stirring for 1 hour. The aged feed solution was filtered and washed with deionized water until the pH of the filtrate was neutral. The filter cake was dried at 110 °C for 4 hours to obtain boehmite solid, which was then ground into powder. The X-ray diffraction pattern of the product is as follows. Figure 9 It has a colloidal index of 98.5%, a crystallinity of 65%, and a specific surface area of ​​380 m². 2 / g, pore volume 0.36 cm³ 3 / g, with a sodium oxide content of 0.02%. This method reduces reaction time, realizes a continuous carbon production process, and the first filtrate has a high sodium carbonate concentration. The filtrate in industry can be directly used as a raw material liquid for sintering bauxite, saving washing water consumption, improving the crystallinity and colloidal properties of boehmite, and the sodium oxide content is far lower than the requirements of low sodium grades in industry standards. Example 2

[0048] The implementation process was similar to that of Example 1, except that the raw material was a 0.3 mol / L sodium aluminate solution, the gas source was flue gas containing approximately 100% carbon dioxide, the pressure was 0.15 MPa, the reaction endpoint was pH=11, and the gel was dispersed in deionized water at 95°C. The product had a gel solubility index of 96.3% and a specific surface area of ​​386 m². 2 / g, pore volume 0.40 cm³ 3 / g, sodium oxide content is 0.06%. Example 3

[0049] The implementation process is similar to that of Example 1, except that sodium aluminate solution, an intermediate product of the sintering process for producing alumina, is used as the raw material. A sodium aluminate solution with a concentration of 0.25 mol / L is prepared. The gas source is flue gas containing approximately 36% carbon dioxide at a pressure of 0.2 MPa. The gel is then deposited into deionized water at 95°C. The product has a gel solubility index of 97% and a specific surface area of ​​385 m². 2 / g, pore volume 0.38 cm³ 3 / g, sodium oxide content is 0.03%. Example 4

[0050] The implementation process was similar to that of Example 1, using a 0.5 mol / L sodium aluminate solution. The gas source was flue gas containing approximately 50% carbon dioxide, at a pressure of 0.2 MPa. The reaction endpoint was pH = 11.18. The product had a colloidal index of 97.2% and a specific surface area of ​​377 m². 2 / g, pore volume is 0.39 cm³ 3 / g, sodium oxide content is 0.063%.

Claims

1. A pressure-resistant hypergravity reaction device, comprising a packing layer, a motor, a shell, a liquid distributor, a gas inlet, a gas outlet, a liquid inlet, a liquid outlet, and a drive shaft; characterized in that: The packing layer is divided into an upper packing layer and a lower packing layer. The upper packing layer includes an upper baffle and an upper packing annular column. The upper baffle is a disc with multiple concentric concave annular grooves and is fixed to the upper part of the shell. The upper packing annular column is a multi-layered concentric annular column filled with packing material and is located between the upper and lower baffles. The lower packing layer includes a lower baffle and a lower packing annular column. The lower packing annular column is a multi-layered concentric annular column filled with packing material. The lower baffle is a disc with a concave annular groove, which is located between the outermost two layers of the lower packing annular column. The lower baffle is fixed to a drive shaft connected to a motor and rotates with the drive shaft. The concave annular grooves are arranged radially from the outer edge to the inner edge. Each layer of upper packing ring columns is fixedly installed on the downwardly protruding annular surface of the concave annular groove of the upper baffle; the lower packing ring columns are fixed on the lower baffle, located in the space enclosed by the upwardly protruding annular surfaces of the concave annular grooves of the lower and upper baffles; the upper and lower packing ring columns are staggered and nested, with the lower packing ring columns embedded between the two concave annular grooves of the upper baffle, and the outermost upper packing ring columns embedded in the concave annular groove of the lower baffle; except for the outermost upper packing ring columns nested in the concentric concave annular grooves of the lower packing layer, the other upper packing ring columns are fixed on the lower baffle of the lower packing layer, nesting and combining with the lower packing ring columns to form a whole; the outer edge of the upper baffle is provided with an eave, which is lower than the plane of the upper baffle.

2. The pressure-resistant hypergravity reaction device according to claim 1, characterized in that: The lower baffle has multiple liquid channels on the outer edge of the concave annular groove, so that the liquid entering the lower baffle can easily flow out through the liquid channels. The liquid channels are circular holes evenly distributed along the circumference or openings along the transverse or longitudinal lines of the outer edge of the lower baffle's concave annular groove.

3. The pressure-resistant hypergravity reaction device according to claim 1, characterized in that: The upper baffle is directly and tightly fixed to the shell, or the upper baffle is kept horizontal to the plane of the shell, and the inner and outer edges of the upper baffle are respectively fixed to the sides of the two supporting sealing rings, and the two supporting sealing rings are directly fixed to the upper part of the shell.

4. The pressure-resistant hypergravity reaction device according to claim 1, characterized in that: The packing layer, liquid inlet, drive shaft, and housing are concentric circles; the liquid inlet is connected to the liquid distributor, which is located inside the packing layer; the gas inlet and gas outlet can be interchanged to achieve parallel or countercurrent contact.

5. The pressure-resistant hypergravity reaction device according to claim 4, characterized in that: The liquid inlet is nested within the gas outlet, forming an inner and outer sleeve structure, allowing the gas and liquid phases to achieve countercurrent contact. The gas inlet is located on one side of the shell. Alternatively, the liquid inlet is nested within the gas inlet, allowing the gas and liquid phases to achieve parallel flow contact. The gas outlet is located on one side of the shell.

6. The application of the pressure-resistant hypergravity reaction apparatus according to any one of claims 1 to 5 in the preparation of low-sodium pseudoboehmite.

7. The application according to claim 6, characterized in that... Includes the following steps: Sodium aluminate solution and CO2-containing gas are continuously passed into a pressure-resistant hypergravity device for reaction. Under the action of the hypergravity field, a rapid reaction is achieved, the reaction endpoint is precisely controlled, and a slurry is continuously generated. The slurry is rapidly heated and then rapidly filtered to obtain a gel. The gel is then rapidly dispersed in a weakly alkaline or neutral aqueous solution at a certain temperature and aged. After washing, filtration, and drying, pseudoboehmite powder is prepared.

8. The application according to claim 7, characterized in that: The specific process conditions for preparing pseudoboehmite are as follows: sodium aluminate solution concentration of 0.1~2.0 mol / L, Al2O3 content of 5~100 g / L, carbon dioxide content in gas of 15%~100%, pressure of 0.1~1.0 MPa, reaction temperature of 10~40 ℃, and centrifugal rotation speed of 100~2000 rpm; the reaction endpoint condition is a slurry pH of 8~13; rapid heating time of slurry is less than 15 min, heating temperature is 80~90 ℃, and rapid filtration time is less than 30 min. The weakly alkaline or neutral aqueous solution is a sodium-free solution, including inorganic electrolytes containing ammonium carbonate and ammonium bicarbonate, dispersant, grain growth regulator, pore-expanding agent solution, and deionized water; the dispersant includes triethylhexylphosphonic acid or polyacrylamide; the grain growth regulator is a polyhydroxy alcohol, including glucose or gluconic acid; the pore-expanding agent is melamine or urea; the temperature of the weakly alkaline or neutral aqueous solution is 70~99 ℃, and the aging time is 0.5~3.5 h; The washing requirements are: the pH of the washed liquid should be 7-9; the drying temperature should be 80-110 ℃; the prepared pseudoboehmite should have a sodium oxide content of less than 0.08%, a colloidal property of greater than 96%, and a pore volume of greater than 0.36 cm³. 3 / g, specific surface area greater than 360 m² 2 / g.

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