A continuous discharge reaction kettle unit for pseudo-boehmite

Abstract

The present application relates to a kind of continuous discharge reaction kettle unit of pseudo-boehmite, belong to inorganic material synthesis equipment technical field;Including stepped main reactor, the stepped main reactor is in vertical direction and presents stepped variable-diameter structure, at least including first stage reaction section and second stage reaction section from top to bottom, the top of the stepped main reactor is equipped with the feed inlet being connected with the discharge port of the premixing unit, the stepped main reactor is equipped with boost system, the stepped variable-diameter structure cooperates boost system and is synergistically regulated slurry flow rate and residence time;By variable-diameter structure, material flow cross section is changed, gradient flow rate and uniform turbulent flow field are formed, cooperate boost system active flow guide and push, accurately regulate slurry flow rate and each stage residence time, completely solve the problem of traditional equipment flow field disorder, short circuit flow, dead zone, inhibit solid slurry settlement and plugging failure from root, substantially improve the stability of equipment continuous operation.

Description

Technical Field

[0001] This invention relates to a continuous discharge reactor unit for pseudoboehmite, belonging to the technical field of inorganic material synthesis equipment. Background Technology

[0002] Boehmite is a core precursor material for the preparation of alumina, catalyst supports, and adsorbents. Its key performance parameters, such as grain size, particle size distribution, pore volume, and specific surface area, directly determine the performance of the final materials. Currently, the industrial synthesis of boehmite mainly adopts an acid-base neutralization precipitation reaction process, and the corresponding reaction equipment is mostly a traditional single-diameter stirred reactor, a split multi-reactor series reactor, or a conventional tubular reactor.

[0003] Existing equipment has many inherent defects in continuous production processes:

[0004] Firstly, the traditional equal-diameter reaction vessel has a simple cavity structure, which cannot adapt to the dynamic changes in the reaction of boehmite, such as volume expansion in the early stage, viscosity increase in the later stage, and easy sedimentation of solid particles. Dead zones and short-circuit flow are easily formed inside the vessel, resulting in uneven distribution of material residence time and insufficient reaction saturation. For example, Chinese Patent Publication No. CN114288977A discloses an apparatus and method for preparing boehmite, which uses a single equal-diameter cylindrical vessel with an internal stirring device, but no segmented variable-diameter structure. This results in uneven material mixing, easy formation of dead zones, and a wide particle size distribution and poor stability of the product.

[0005] Secondly, high-solids-content slurries face significant resistance during vertical transport. Stable cross-stage transport cannot be achieved solely through gravity flow or a single stirring structure. Long-term operation can easily lead to solid deposition and pipeline blockage, resulting in extremely short continuous operating times and poor production stability. For example, Chinese Patent Publication No. CN112694112A discloses a method for the continuous preparation of pseudoboehmite, comprising a series of primary reactors, secondary reactors, and an aging device. This device consists of multiple independent reactors of equal diameter connected in series via flanges or pipelines. Each reactor is independently processed and installed, rather than a single-unit stepped variable-diameter structure. This results in a large equipment footprint, numerous connection points prone to leakage, and a wide distribution of material residence time.

[0006] Third, existing multi-reactor series equipment uses a split flange connection structure, which occupies a large area, has poor sealing, and each chamber cannot achieve independent and precise temperature control. This makes it unsuitable for the segmented reaction mechanism of "low-temperature nucleation and high-temperature crystal growth" of boehmite, resulting in uneven particle size, poor pore structure parameter stability, and inconsistent product quality. Fourth, existing discharge structures lack online filtration, backwashing, and real-time parameter monitoring functions, requiring frequent shutdowns for maintenance and preventing long-term continuous industrial production. For example, Chinese Patent Publication No. CN120381811A discloses a continuous synthesis device and method for boehmite, using straight or spiral tubes of uniform diameter throughout as reaction / aging units. It lacks a stepped gradient diameter structure, has poor adaptability to high solids content slurries, is prone to sedimentation and blockage, and has weak residence time control capabilities.

[0007] In summary, existing pseudoboehmite synthesis equipment suffers from technical problems such as uneven material mixing, easy blockage in conveying, inability to control reaction parameters in stages, poor product quality, and low stability during continuous operation. There is an urgent need for a targeted integrated continuous reaction unit to solve these problems. Summary of the Invention

[0008] The purpose of this invention is to provide a continuous discharge reactor unit for pseudo-boehmite, which aims to solve the technical problems of high vertical conveying resistance of solid slurry, uneven material residence time distribution due to staged settling, incomplete reaction, easy equipment blockage, inability to accurately control temperature in stages, and poor product quality stability in existing continuous reaction devices.

[0009] The present invention discloses a continuous discharge reactor unit for boehmite, comprising a stepped main reactor. The stepped main reactor has a stepped variable diameter structure in the vertical direction and includes at least a first-stage reaction section and a second-stage reaction section from top to bottom. The top of the stepped main reactor is provided with a feed inlet connected to the discharge port of the premixing unit. The stepped main reactor is equipped with a booster system. The stepped variable diameter structure, together with the booster system, coordinates the slurry flow rate and residence time to suppress solid slurry settling and blockage, and optimize the particle size uniformity of boehmite.

[0010] The stepped main reactor adopts a progressively expanding diameter structure with a large diameter at the top and a small diameter at the bottom. This stepped diameter structure alters the material flow cross-section, creating a low-speed, gentle turbulent flow field in the upper, large-diameter reaction section to meet the need for uniform nucleation in the initial stage of the reaction. The lower, small-diameter reaction section creates a high-speed, strong shear flow field to meet the needs of preventing sedimentation and promoting grain growth in the later stages of the high-solids-content slurry, thus constructing a gradient velocity distribution that matches the reaction kinetics. Simultaneously, a conical transition section ensures a smooth flow transition, eliminating dead zones for material accumulation. Furthermore, a booster system actively guides and propels the flow. A variable-frequency booster spiral dynamically compensates for slurry flow resistance and precisely controls the cross-section conveying rate. Wall-mounted booster blades break up boundary layer material and regulate the overall flow field. The variable-diameter structure pre-sets graded velocity ranges, and the booster system dynamically locks the residence time at each stage. Together, these two mechanisms achieve refined, segmented matching control of slurry flow rate and residence time, fundamentally suppressing solid slurry sedimentation and blockage, and simultaneously optimizing the uniformity of boehmite grain growth and particle size.

[0011] The stepped main reactor adopts a progressively expanding diameter structure with a small diameter at the top and a large diameter at the bottom, precisely adapting to the dynamic changes in the slurry properties during the pseudo-boehmite reaction process. In the initial stage of the reaction, the freshly mixed slurry has low solids content and a small volume. The small-diameter cavity at the top can increase the turbulent flow rate of the slurry, enhance the micro-mixing effect, and promote synchronous and uniform nucleation, avoiding the problem of uneven crystal nucleus size caused by local concentration differences. As the reaction progresses, solid microcrystals are continuously generated, and the slurry viscosity and overall volume gradually increase. The progressively expanding large-diameter cavity at the bottom can effectively accommodate the slurry's reaction expansion, reducing the flow rate of the high-viscosity slurry in the later stages, extending the crystal growth residence time, and providing a stable and gentle flow field environment for the regular growth of crystals. Meanwhile, the upper and lower diameter-changing sections achieve a smooth flow field transition through a conical transition section. Combined with the active flow guidance and pushing by the booster system, this compensates for the material flowability in the low-speed zone at the bottom of the large-diameter cavity, completely eliminating wall stagnation and sedimentation. Through a gradient flow field control mechanism of "upper section accelerating for stable nucleation, lower section decelerating for stable crystal growth," the segmented reaction kinetics are precisely matched, significantly optimizing the uniformity of boehmite particle size and the stability of continuous equipment operation. In specific implementation, the method of gradually reducing or increasing the inner diameter is selected according to the operational requirements.

[0012] As two independently implementable stepped reactor structure schemes of the present invention, the first is a segmented multi-reactor integrated molding structure, with each reaction section being an independent reactor unit. Each reactor unit corresponds to a first-level reaction section, and the overall assembly is a vertical integrated stepped variable-diameter reactor structure, which differs from traditional split flange series equipment. It has high integration, no exposed connecting pipes, and good sealing performance. An internal overflow channel is provided between two adjacent reactor units. The upper opening of the overflow channel is located on the upper part of the side wall of the upper reaction section, and the lower opening connects to the top of the lower reaction section. The inner wall of the channel is smooth and is equipped with booster blades to prevent material deposition and blockage. The material is continuously overflowed and transported step by step by relying on the liquid level difference, with no dead corners and not easy to blockage.

[0013] Material enters the first-stage reaction section from the top main inlet, and the liquid level gradually rises. When the liquid level reaches the opening height of the overflow channel, excess slurry flows by gravity into the next-stage reaction section through the built-in overflow channel. Each stage follows this overflow flow pattern, with the final stage having a main outlet at the bottom, achieving a continuous feeding → progressive overflow → continuous bottom discharge process. A booster system assists in agitating the slurry to prevent solid deposition and blockage at the overflow channel inlet. The inner wall of the overflow channel is smoothed, with a channel inclination angle ≥45°, utilizing gravity for self-cleaning. Small agitator blades (belonging to the booster system) are added at the channel inlet to continuously agitate the inlet slurry. The bottom of the overflow channel has no dead corners and smoothly transitions to the next stage cavity.

[0014] Secondly, the stepped main reactor is a single-shell, integrated structure without separate flanges or series connections. The reactor body has a stepped diameter variation in the vertical direction, comprising at least a first-stage and a second-stage reaction section from top to bottom, with the inner diameter of each stage gradually decreasing or increasing. This integrated stepped diameter variation design allows for precise adaptation to changes in slurry volume, flowability, and viscosity at different stages of the boehmite reaction. Furthermore, it enables the material to generate abrupt velocity changes and differentiated turbulent flows in each reaction stage, effectively eliminating dead zones and short-circuit flows within the reactor and promoting uniform dispersion of solid particles. The top of the stepped main reactor has an inlet connected to the outlet of the premixing unit. The stepped main reactor is equipped with a booster system, which includes a booster screw conveyor positioned between adjacent reaction sections and / or booster stirring blades mounted on the inner wall of the reactor. Through the coordinated structure of the variable-diameter reactor body and the booster system, the slurry from the previous reaction stage is actively and stably pushed into the next reaction stage, completely solving the problems of sedimentation, accumulation, and cross-stage blockage of high-solids content slurry, significantly reducing the difference in residence time between different stages of the material, and ensuring reaction uniformity. The inner diameter of each reaction stage gradually decreases or increases and is connected by a conical transition section with a cone angle of 30°-90°. The entire shell is continuous without splicing gaps, has high structural strength, can completely eliminate dead corners for material accumulation, and forms a continuous gradient flow field in conjunction with the variable-diameter structure.

[0015] The continuous discharge reactor unit for pseudoboehmite described in this invention further includes:

[0016] The premixing unit is equipped with at least two independent feed lines, each with a flow control valve to precisely regulate the feed ratio of each reactant. The premixing unit also has a pre-stirring and guiding structure to fully premix and homogenize the feed materials, ensuring that the material entering the main reactor has uniform composition and stable concentration, thus avoiding the problem of uneven local reaction.

[0017] An aging reactor is connected to the bottom outlet of the stepped main reactor. The aging reactor is equipped with a temperature control jacket and multi-stage baffles, which can perform constant temperature aging treatment on the initially reacted slurry to regulate the grain morphology, improve the pore structure, and further enhance the uniformity and stability of the product.

[0018] The system also includes a continuous discharge unit located at the end of the aging reactor. The continuous discharge unit includes a discharge pump and an online filter connected to the discharge pump, which can filter and remove impurities from the aged slurry online, achieving continuous, stable, and clean discharge throughout the process.

[0019] Preferably, the ratio of the inner diameter of each reaction section in the stepped main reactor is 1:0.6-0.9 or 1:1.2-1.8, and the ratio of the height to the inner diameter of each reaction section is 1-3:1. By defining precise cavity ratio parameters, the dynamic changes in slurry volume, viscosity, and solid content throughout the entire process of boehmite nucleation and grain growth are adapted to ensure uniform flow field and residence time matching process requirements in each reaction section.

[0020] Preferably, the booster system includes at least one booster screw conveyor, which is installed in the connecting channel between adjacent reaction sections. Its screw blades extend to the upper part of the next-level reaction section. The booster screw conveyor adopts a variable frequency speed regulation setting, which can dynamically adjust the pushing speed according to the real-time viscosity and solid content of the slurry to adapt to different production conditions.

[0021] Preferably, the booster system further includes booster stirring blades disposed on the inner wall of each reaction section. The booster stirring blades are arranged in a spiral or layered manner along the inner wall of the vessel, and the tilt angle of the booster stirring blades is 15°-60°. The booster stirring blades can continuously shear and guide the low-velocity material in the boundary layer of the vessel, eliminating the problem of material deposition on the wall surface and realizing dynamic renewal and uniform flow of materials throughout the vessel.

[0022] The variable-diameter structure and the booster system work together through flow field pre-setting and dynamic compensation mechanisms: the stepped variable-diameter structure pre-sets gradient flow velocity ranges from the first-stage reaction section to the Nth-stage reaction section based on the slurry volume and viscosity change trends at each stage of the pseudo-boehmite reaction (e.g., the first stage uses low-speed gentle turbulence to promote nucleation, and the final stage uses high-speed shear to prevent sedimentation), forming a basic passive flow field control; the booster system senses or actively intervenes in real time to dynamically compensate for the above gradient flow field—in stages where the viscosity increases sharply or the solid content increases, the booster screw conveyor starts or accelerates, actively pushing the material to overcome flow resistance and break the boundary layer stagnation; in stages where the flow velocity is too fast, the booster stirring blades form reverse damping or lateral flow guidance at a specific angle (15°-60°) to avoid material short-circuiting; finally, the passive graded flow velocity window provided by the variable-diameter structure and the active flow velocity fine-tuning provided by the booster system are coupled together, so that the deviation between the actual residence time and the theoretical optimal residence time of each stage of the reaction section is controlled within ±5%. This synergistic mechanism of preset gradient + real-time compensation is not a simple superposition of variable diameter structure and stirring / conveying device, but a deep adaptation to the reaction kinetics characteristics of pseudo-boehmite.

[0023] Preferably, the stepped main reactor is further equipped with a staged stirring system, which includes a first stirrer located in the middle of the first-stage reaction section and a second stirrer located at the bottom of the final-stage reaction section. The first and second stirrers are driven and speed-adjusted independently. The staged stirring system and the booster system work independently and collaboratively. The first stirrer is mainly responsible for the homogeneous mixing of materials and particle suspension to prevent agglomeration in the initial stage of the reaction. The second stirrer is mainly responsible for preventing the sedimentation of high-solids materials at the bottom. The booster system focuses on achieving stable material transport across stages. The three work together to achieve precise staged and zoned reaction and transport.

[0024] Preferably, each stage of the stepped main reactor is equipped with an independent outer jacket or heating coil for independent temperature control of each stage. To address the differentiated thermal effects and reaction requirements at different stages of the boehmite precipitation reaction, a vertical temperature gradient can be constructed within the reactor. This allows for precise low-temperature control of the nucleation rate in the first stage reaction and temperature increases in subsequent stages to promote orderly grain growth, thus achieving refined control of the reaction process at the equipment level.

[0025] Preferably, the premixing unit is a cavity-type premixing device, which has multiple sets of spiral guide vanes with different rotation directions inside to achieve forced convection and homogeneous mixing of multiple materials; the aging reactor adopts a segmented independent temperature control jacket, combined with staggered multi-stage baffles, to effectively extend the effective aging time of materials and avoid the problem of material short-circuiting loss.

[0026] Preferably, the unit of this invention is also equipped with online pH monitoring devices and online temperature monitoring devices, forming a closed-loop monitoring and control system for the entire process parameters. The online pH monitoring device is located at the material outlet of the stepped main reactor, and can continuously collect the pH data of the slurry after the reaction is completed in real time. This provides accurate feedback on the acid-base environment of the system during the nucleation and crystal growth reactions, promptly capturing acid-base fluctuations in the reaction system. By linking the flow control valve of the premixing unit at the front end, the material ratio is fine-tuned, continuously calibrating the reaction environment to ensure a stable boehmite nucleation rate and uniform crystal growth, avoiding problems such as uneven crystal size and abnormal agglomeration caused by acid-base fluctuations. When fine-tuning the material ratio, adjustments are made by regulating the flow control valve of one material; for example, when dealing with gaseous and liquid materials, the liquid material remains unchanged, while the flow control valve of the gaseous material is adjusted. The online temperature monitoring device is equipped with multi-point distributed temperature sensors, which are respectively deployed inside the independent jacket of each reaction section of the stepped main reactor and the segmented jacket of the aging reactor. It can independently and in real time monitor the reaction temperature of each reaction section and the constant temperature of the aging stage, accurately feedback the real-time changes of the temperature control parameters of each segment, and, based on the reaction characteristics of boehmite "segmented nucleation, gradient crystal growth, and constant temperature aging", link and regulate the input temperature and flow rate of the temperature control medium in each jacket, accurately match the optimal temperature process for different reaction stages, realize the whole process, segmented, and refined closed-loop temperature control of the unit, ensure the stability of the reaction process from both temperature and acid-base dimensions, and significantly improve the consistency of batch product quality.

[0027] Compared with the prior art, the present invention has the following significant advantages:

[0028] 1. This invention features a pioneering stepped variable diameter main reactor structure, which, combined with a dedicated booster system, forms a synergistic control mechanism. By changing the material flow cross-section through the variable diameter structure, a gradient flow velocity and a uniform turbulent flow field are formed. With the active guidance and pushing of the booster system, the slurry flow velocity and residence time at each stage are precisely controlled, completely solving the problems of turbulent flow field, short-circuit flow, and dead zone in traditional equipment. It suppresses solid slurry sedimentation and material blockage from the root, and significantly improves the stability of continuous operation of the equipment.

[0029] 2. This invention features two switchable stepped reactor forming structures: a segmented multi-reactor integrated structure and a single-reactor shell structure, adaptable to different production conditions and equipment specifications. The segmented multi-reactor integrated structure is equipped with a built-in overflow channel, achieving sealed, step-by-step overflow conveying with no exposed pipes or dead zones for material accumulation. The single-reactor shell structure, with a 30°-90° conical transition section, boasts strong structural integrity and excellent flow field continuity. Both structures differ from traditional equal-diameter reactors and split-series equipment, demonstrating significant innovation.

[0030] 3. The present invention adopts an independent staged stirring structure, with the upper and lower stage stirrers independently adjustable in speed and working together to meet the needs of material homogenization and anti-agglomeration in the early stage of reaction and anti-settling at the bottom in the later stage of reaction. In conjunction with the booster system and the stepped variable diameter structure, multiple collaborations are achieved to realize precise staged and zoned reaction, so that the nucleation and grain growth processes of pseudoboehmite are synchronized and regular, and the particle size uniformity of the product is significantly optimized.

[0031] 4. Each stage of the reaction process in this invention is equipped with an independent temperature control structure. Combined with precise chamber ratio parameters and a full-process online monitoring device, it can achieve precise closed-loop control of temperature, pH, flow rate, and residence time during the reaction process. This perfectly matches the segmented reaction mechanism of boehmite, effectively improving the reaction conversion rate and product quality stability. The core performance of the product, such as particle size distribution uniformity, specific surface area, and pore volume, is significantly better than that of traditional equipment products.

[0032] 5. This invention adopts an integrated structure of pre-mixing, mid-stage stepped reaction, post-aging modification, and continuous discharge at the end. The equipment has high integration, low failure rate, and does not require frequent shutdown for maintenance. It can realize long-term continuous and stable industrial production of pseudoboehmite, and has extremely high industrial application value. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of a stepped continuous discharge reactor unit for boehmite as described in Embodiment 1 of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of a stepped main reactor as described in Embodiment 2 of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of a booster screw conveyor;

[0036] Figure 4 This is a schematic diagram of the internal structure of the aging reactor;

[0037] Figure 5 This is a flowchart of the process flow of the present invention.

[0038] In the diagram: 10. Premixing unit; 11. First feed line; 12. Second feed line; 13. Third feed line; 14. Flow control valve; 15. Pre-mixing device; 16. Spiral guide vane;

[0039] 20. Stepped main reactor; 21. First stage reaction section; 22. Second stage reaction section; 23. Third stage reaction section; 24. Conical transition section; 25. First agitator; 26. Second agitator; 27. Boosting screw conveyor; 271. Helical blades; 272. Drive motor; 273. Boosting stirring blades;

[0040] 30. Apparatus jacket;

[0041] 40. Aging reactor; 41. Temperature control jacket; 42. Baffle plate; 43. Connecting pipelines;

[0042] 50. Continuous discharge unit; 51. Discharge pump; 52. Online filter; 53. Backwash pipeline; 54. Backwash pump; 55. Switching valve; 56. Discharge pipeline. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0044] Example 1

[0045] This embodiment provides a continuous discharge reactor unit for pseudoboehmite, including a premixing unit 10, a stepped main reactor 20, an aging reactor 40, and a continuous discharge unit 50.

[0046] The premixing unit 10 is equipped with three independent feed lines (first feed line 11, second feed line 12, and third feed line 13), and each line is equipped with a flow control valve 14, which can precisely control the feed ratio of aluminum salt solution, alkaline solution, and buffer solution. Inside the premixing unit 10, spiral guide vanes 16 and pre-stirring devices 15 are arranged sequentially along the material flow direction.

[0047] The spiral guide vanes 16 are multiple sets of spiral guide plates fixed to the inner wall of the premixing unit 10, with each set of spiral guide vanes 16 rotating in opposite directions (alternating between left-handed and right-handed rotation). After entering the premixing unit 10, each material first flows through the spiral guide vanes 16. Under the forced guidance of the spiral guide vanes 16, the material flows along the spiral path and generates multiple diversions, cross-directions, and convergences, achieving preliminary static mixing and homogenization of multiple materials.

[0048] The pre-stirring device 15 is located downstream of the spiral guide vane 16 and includes a stirring motor (not shown), a stirring shaft, and stirring blades mounted on the shaft. After the material has undergone preliminary mixing, it enters the main chamber of the premixing unit 10, where the pre-stirring device 15 performs active mechanical stirring to further shear, tumble, and disperse the material, preventing solid particles from settling and ensuring uniform discharge concentration and stable composition. The pre-stirring device 15 and the spiral guide vane 16 work together; the former performs passive premixing, while the latter achieves active deep homogenization, jointly ensuring that the material entering the stepped main reactor 20 reaches a highly uniform and stable state.

[0049] The stepped main reactor 20 adopts a segmented multi-reactor integrated molding structure, with three independent reactor units. Each reactor unit corresponds to a first-level reaction section. The overall vertical assembly is a stepped variable diameter structure with a larger upper section and a smaller lower section. The reaction sections are the first-level reaction section 21, the second-level reaction section 22, and the third-level reaction section 23, with an inner diameter ratio of 1:0.75:0.6 and a height-to-inner diameter ratio of 2:1. An internal overflow channel is set between adjacent reactor units. The upper opening of the overflow channel is located on the upper side wall of the upper reaction section, and the lower opening connects to the top of the lower reaction section. The inner wall of the channel is smooth and, in conjunction with the booster blades (i.e., booster stirring blades 273), achieves self-cleaning and anti-clogging. The material is conveyed by overflow in stages based on the liquid level difference.

[0050] Each reaction stage is equipped with an independent outer jacket (vessel jacket 30), enabling independent temperature control in each stage. The vessel is equipped with a staged stirring system. The first stirrer 25 is located in the middle of the first-stage reaction stage 21 for homogenizing and mixing materials and preventing particle agglomeration. The second stirrer 26 is located at the bottom of the final reaction stage (third-stage reaction stage 23) specifically for preventing sedimentation of high-solids slurry at the bottom. The two stirrers are driven and adjusted independently.

[0051] The booster system includes an interstage variable frequency booster screw conveyor 27 and a vessel wall booster stirring blade 273. The booster screw conveyor 27 is driven by a drive motor 272, and its screw blades 271 extend to the upper part of the next reaction section, allowing for dynamic adjustment of the conveying rate. The vessel wall booster stirring blade 273 has an inclination angle of 30° and is spirally arranged on the inner wall of each stage of the vessel, continuously shearing the boundary layer material and preventing material accumulation on the wall.

[0052] The aging reactor 40 is connected to the bottom outlet of the main reactor via a connecting pipe 43. It is internally equipped with a segmented temperature control jacket 41 and multi-stage staggered baffles 42 to extend the aging time of the slurry and regulate the grain structure. A continuous discharge unit 50 is located at the end of the aging reactor 40.

[0053] The continuous discharge unit 50 includes a discharge pump 51, an online filter 52, a backwash pipeline 53, a backwash pump 54, a switching valve 55, and a discharge pipeline 56. Specifically, the inlet of the discharge pump 51 is connected to the bottom outlet of the aging reactor 40 via the discharge pipeline 56, and the outlet is connected to the inlet of the online filter 52; the outlet of the online filter 52 is connected to the downstream finished product discharge pipeline; one end of the backwash pipeline 53 is connected to the outlet of the backwash pump 54, and the other end is connected to the backwash inlet of the online filter 52; the inlet of the backwash pump 54 is connected to the backwash medium source; the switching valve 55 is installed on the backwash pipeline 53 to control the on / off state of the backwash medium.

[0054] The discharge pump 51 is preferably a screw pump, diaphragm pump, or hose pump adapted to conveying high-solids-content slurries, and adopts a variable frequency speed control setting to automatically adjust the conveying flow rate according to changes in production load and filter inlet and outlet pressure difference. A pressure gauge is provided at the outlet end of the discharge pump 51 for real-time monitoring of the pump outlet pressure.

[0055] The inline filter 52 has a housing made of 304 or 316L stainless steel and contains multiple layers of composite filter screens or sintered metal filter elements, with a filtration accuracy of 50-200 mesh. The top cover of the inline filter 52 has a detachable flange structure for easy maintenance and filter element replacement; the bottom of the housing has a slag discharge port and a manual drain valve. The discharge pump 51 is integrated with the inline filter 52 and installed on the same equipment base, with a short pipe directly connecting the pump outlet and the filter inlet.

[0056] The backwash medium is preferably clean, filtered slurry. The head of the backwash pump 54 is 1.5-2.0 times the rated pressure of the discharge pump 51. The switching valve 55 is a pneumatic or electric ball valve, and its on / off state is interlocked with that of the discharge pump 51 and the backwash pump 54.

[0057] The inner wall of the discharge pipe 56 is polished, and the feed end is equipped with a bottom valve or shut-off valve. The pipe is also equipped with a flushing port.

[0058] The continuous discharge unit 50 operates as follows: During normal filtration and discharge, the switching valve 55 is closed, the backwash pump 54 is not working, and the discharge pump 51 extracts the slurry from the aging reactor 40 and sends it to the online filter 52 for filtration. Qualified slurry enters the downstream process. When the inlet and outlet pressure difference of the online filter 52 reaches the set threshold or the operating time reaches the preset cycle, the control system opens the switching valve 55 and starts the backwash pump 54. Clean slurry enters the online filter 52 through the backwash pipeline 53, backwashing the filter screen. The washed-off solid particles are returned to the aging reactor 40 with the slurry or discharged into the waste collection device. After backwashing is completed, the system automatically resumes normal discharge. This achieves continuous, stable, and clean discharge.

[0059] The unit is equipped with online pH monitoring devices and online temperature monitoring devices to monitor the acidity and alkalinity of the reaction system and temperature parameters at each stage in real time, thereby achieving closed-loop control.

[0060] Example 2

[0061] This embodiment is basically the same in structure as Embodiment 1, except that: the stepped main reactor 20 adopts an integrated single-shell structure with no splicing gaps. The inner diameters of the three reaction sections (first-stage reaction section 21, second-stage reaction section 22, and third-stage reaction section 23) decrease progressively from top to bottom, with an inner diameter ratio of 0.65:0.8:1. Each reaction section is smoothly connected by a conical transition section 24 with a cone angle of 45°, completely eliminating dead corners for material accumulation. This embodiment does not have a built-in overflow channel; it relies on a variable-diameter flow field and a booster system (booster screw conveyor 27 and booster stirring blades 273) to achieve progressive material conveying. A feed inlet is provided at the top of the reactor body, and a multi-point distributed feeder can be optionally equipped to improve the uniformity of feeding. The remaining premixing unit 10, aging reactor 40, continuous discharge unit 50, staged stirring system (first stirrer 25 and second stirrer 26), booster system, and monitoring structure are completely consistent with Embodiment 1.

[0062] Comparative Example

[0063] A traditional equal-diameter single-stage stirred reactor is used, with a uniform inner diameter, no stepped diameter change structure, no segmented independent temperature control, no composite booster system, and no staged stirring structure. The other process parameters for feeding, reaction, aging, and discharging are consistent with those in Example 1.

[0064] Testing revealed that the particle size uniformity (D90 / D10) of the products in Examples 1 and 2 of this application were 1.08 and 1.11, respectively, while the uniformity of the comparative product was above 1.52. During 240 hours of continuous operation, the reaction conversion rate of the examples remained stable between 96% and 98%, while the conversion rate of the comparative product dropped below 89% after 72 hours of operation, and signs of pipeline blockage appeared. This indicates that the unit of this invention has achieved technical effects far exceeding those expected from conventional equipment modifications in terms of stability and product consistency during long-term continuous production. The core performance characteristics of Examples 1 and 2 of this invention, such as grain regularity, specific surface area, and pore volume, are significantly superior to those of the traditional comparative product, resulting in a substantial improvement in both continuous equipment operation stability and product quality.

[0065] To further verify the synergistic effect between the stepped variable diameter structure and the booster system in this invention, comparative test group 1 (using only the stepped variable diameter structure, without starting the booster system) and comparative test group 2 (using only the booster system, with a constant diameter vessel) were set up and compared with Embodiment 1 of this invention. The test results are as follows:

[0066] Table 1 Performance Comparison under Different Configurations

[0067]

[0068] As shown in the table above, when only the stepped variable diameter structure is used without activating the booster system, although the initial flow field is improved, a 3-5 mm thick deposition layer still appears at the bottom of the second-stage reaction section 22 after 48 hours of continuous operation, and the residence time distribution width is relatively large. When only the booster system is used and the vessel body has a constant diameter structure, although deposition can be suppressed to a certain extent, the material residence time distribution width is increased by more than 40% compared with Example 1 of this invention, and the reaction conversion rate and product particle size uniformity are significantly worse than those of this invention. Only when both the stepped variable diameter structure and the booster system are activated simultaneously can the excellent effect of no deposition for 240 hours, a residence time distribution width of less than 15%, and a product particle size non-uniformity as low as 1.08 be achieved. This comparative result fully demonstrates the unexpected technical effect brought about by the "synergistic regulation of the stepped variable diameter structure and the booster system" in this invention.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A continuous discharge reactor unit for pseudoboehmite, characterized in that, The reactor includes a stepped main reactor (20), which has a stepped variable diameter structure in the vertical direction and includes at least a first-stage reaction section (21) and a second-stage reaction section (22) from top to bottom. The top of the stepped main reactor (20) is provided with a feed inlet that is connected to the discharge port of the premixing unit (10). The stepped main reactor (20) is equipped with a booster system. The stepped variable diameter structure, together with the booster system, coordinates the flow rate and residence time of the slurry to suppress the settling and blockage of solid slurry and optimize the uniformity of the particle size of the pseudo-boehmite.

2. The continuous discharge reactor unit for pseudoboehmite according to claim 1, characterized in that, It also includes a premixing unit (10), an aging reactor (40), and a continuous discharge unit (50); The premixing unit (10) is provided with at least two independent feed pipelines, and each feed pipeline is provided with a flow control valve (14) for regulating the feed ratio of each material. The premixing unit (10) is provided with a pre-stirring and guiding structure for fully premixing and homogenizing each feed material. The aging reactor (40) is connected to the bottom outlet of the stepped main reactor (20). The aging reactor (40) is equipped with a temperature control jacket (41) and a multi-stage baffle plate (42) for constant temperature aging of the slurry after reaction, extending the effective reaction time and regularizing the grain structure. The continuous discharge unit (50) is located at the end of the aging reactor (40) and is used for continuous discharge.

3. The continuous discharge reactor unit for pseudoboehmite according to claim 1, characterized in that, The stepped main reactor (20) is a segmented multi-reactor integrated molding structure. Each reaction section is an independent reactor unit, and a single reactor section corresponds to a first-level reaction section. The whole assembly is a vertical integrated stepped variable diameter reactor structure.

4. The continuous discharge reactor unit for boehmite according to claim 3, characterized in that, An internal overflow channel is provided between two adjacent reactor units. The upper opening of the overflow channel is located on the upper part of the side wall of the upper reaction section, and the lower opening is connected to the top of the lower reaction section. The inner wall of the channel is smooth and is equipped with a stirring blade (273) to prevent material deposition and blockage.

5. The continuous discharge reactor unit for pseudoboehmite according to claim 1, characterized in that, The stepped main reactor (20) is an integrated single-reactor shell structure. The inner diameter of each reaction section gradually decreases or increases, and they are connected by a conical transition section (24). The cone angle of the conical transition section (24) is 30°-90°.

6. The continuous discharge reactor unit for pseudoboehmite according to claim 1, characterized in that, The stepped main reactor (20) is equipped with a graded stirring system. The graded stirring system includes a first stirrer (25) located in the middle of the first stage reaction section (21) and a second stirrer (26) located at the bottom of the last stage reaction section. The first stirrer (25) and the second stirrer (26) are driven and adjusted independently. The first stirrer (25) is used to achieve homogeneous mixing and suspension to prevent agglomeration of materials, and the second stirrer (26) is used to prevent the bottom material from settling. It works in coordination with the booster system to achieve graded and zoned precise stirring and conveying.

7. The continuous discharge reactor unit for pseudoboehmite according to claim 1, characterized in that, The ratio of the inner diameter of each reaction section of the stepped main reactor (20) is 1:0.6-0.9 or 1:1.2-1.8; the ratio of the height to the inner diameter of each reaction section is 1-3:

1.

8. The continuous discharge reactor unit for pseudoboehmite according to claim 1, characterized in that, Each stage of the stepped main reactor (20) is equipped with an independent reactor body jacket (30) or a heat tracing coil.

9. A continuous discharge reactor unit for boehmite according to claim 1, characterized in that, The booster system includes a booster screw conveyor (27) disposed between adjacent reaction sections and / or booster stirring blades (273) disposed on the inner wall of the vessel. The booster screw conveyor (27) is installed in the connecting channel between adjacent reaction sections. The screw blades (271) of the booster screw conveyor (27) extend to the upper part of the next stage reaction section. The booster screw conveyor (27) adopts a variable frequency speed regulation setting and is equipped with a drive motor (272). The booster stirring blades (273) are arranged in a spiral or layered manner along the inner wall of the vessel. The inclination angle of the booster stirring blades (273) is 15°-60°, which is used to form a shearing and guiding effect on the boundary layer material of the vessel.

10. A continuous discharge reactor unit for boehmite according to claim 1, characterized in that, It also includes an online pH monitoring device and an online temperature monitoring device. The online pH monitoring device is located at the outlet of the stepped main reactor (20) to monitor the acidity and alkalinity of the reaction system in real time. The online temperature monitoring device is located in the vessel jacket (30) of each reaction section of the stepped main reactor (20) and the temperature control jacket (41) of the aging reactor (40) to provide real-time feedback of temperature control parameters.

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