Special boehmite hydrothermal device and use method

Abstract

The invention discloses a special boehmite hydrothermal device and a use method, and relates to the technical field of chemical engineering, the special boehmite hydrothermal device comprises a reaction tank, the top of the reaction tank is provided with a magnetic stirring device, the upper end of the reaction tank is provided with a feed inlet, the feed inlet is connected with a secondary feeding assembly, and the secondary feeding assembly is provided with a balance pipeline communicated with the reaction tank; the secondary feeding assembly comprises a balance cavity pipe, a discharging end valve is fixed to the end, close to the reaction tank, of the balance cavity pipe, a feeding end valve is fixed to the other end of the balance cavity pipe, a raising assembly is rotationally connected to the interior of the balance cavity pipe, and a heating pipe is wound around the exterior of the balance cavity pipe. A heat preservation layer wrapping the balance cavity pipe is arranged outside the heating pipe, the communicating position of the balance pipeline and the balance cavity pipe is tangent to the raising assembly, secondary feeding is completed on the premise that the high-temperature and high-pressure environment of the reaction tank is not damaged through cooperation of the balance cavity pipe, the balance pipeline and the valve, and the continuity and stability of reaction are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a special boehmite hydrothermal device and its usage method. Background Technology

[0002] Boehmite, a precursor of γ-Al₂O₃, is widely used in ceramic materials, composite materials, surface protective layers, optical materials, catalysts and support materials, semiconductor materials, and coatings due to its unique chemical, optical, and mechanical properties. Uniform and stable dispersion is crucial for boehmite to exhibit its superior nanomaterial properties. Boehmite prepared by the sol-gel method is characterized by small particle size, large specific surface area, and large pore volume; however, agglomeration is severe during post-processing. Many studies mention using surfactants to address this issue, but achieving ideal results is difficult. Hydrothermal synthesis produces ultrafine oxide powders with narrow particle size distribution and less particle agglomeration. Combining the advantages of sol-gel and hydrothermal synthesis, boehmite was prepared using organoaluminum alkoxides. The effects of temperature, pH, and time on the structure and properties of boehmite were investigated. Current boehmite preparation methods involve reacting raw materials and water in a reactor to obtain boehmite. However, the morphology and size of the boehmite obtained by this method are often consistent with the morphology of the raw materials, failing to meet diverse requirements.

[0003] Chinese patent application number CN202422183404.0 discloses a constant temperature and pressure mixing tank, including a tank body, a feeding pipe, and a pressure relief valve. The pressure relief valve is fixedly embedded on one side of the top of the tank body. A preheating chamber is located above the tank body. The feeding pipe passes through the preheating chamber and connects to the tank body. A uniform heating pipe is sleeved on the outside of the tank body. The preheating chamber and the uniform heating pipe are connected by a guide pipe. The preheating chamber includes a water tank and a cover. The cover is screwed to the upper side of the water tank. A connecting pipe is fixedly embedded on one side of the bottom of the cover. High-temperature steam is injected into the uniform heating pipe, and the high-temperature steam spirals upward along the uniform heating pipe, uniformly heating the material in the tank to ensure consistent heating. Combined with the mixing action of the stirring impeller, local overheating or uneven heating can be avoided, ensuring the reaction can proceed fully. New liquid raw materials are injected into the upper connecting pipe, where they flow in a tortuous manner. Simultaneously, hot steam is transferred to the preheating chamber via the guide pipe.

[0004] Chinese patent application number CN201610873458.7 discloses a constant temperature and pressure fermentation tank for edible fungi. The tank features a sickle-shaped stirring paddle mounted on a stirring shaft, fixedly connected to the shaft by fasteners. Two heating tubes are vertically positioned on either side of the stirring shaft. A condenser tube is installed in the lower middle part of the heating tubes. A control box is located on one side of the tank's outer wall. A drain pipe is located at the bottom of the tank near an automatic water level detector, controlled by a solenoid valve. The automatic water level detector is connected to a control pump via an electrical connection. One end of the control pump is connected to the bottom of the tank via a water pipe, and the other end is connected to a water storage tank via another water pipe. The tank has a simple structure and ensures constant temperature and pressure during fermentation, guaranteeing the stability of the fermented material's performance in various aspects.

[0005] The above solution may encounter the following problems during use: 1. If secondary materials need to be added, the reaction must be stopped first, and the temperature and pressure inside the reaction vessel must be reduced. After the materials are added, the temperature and pressure must be increased again, which will cause the reaction process to break down and significantly reduce production efficiency. During the depressurization and material addition process, outside air or impurities can easily enter the reaction vessel, which may not only contaminate the materials and affect the purity of the product, but also change the temperature and pressure conditions of the reaction, resulting in reaction fluctuations and an increase in by-products.

[0006] 2. If secondary materials are directly introduced into the high-temperature reaction vessel without preheating, they will absorb a large amount of heat instantly, causing a sudden drop in the local temperature inside the reaction vessel, disrupting the original temperature balance of the reaction, and potentially slowing down or even stopping the reaction rate. Summary of the Invention

[0007] To address the above problems, this invention provides a special boehmite hydrothermal device and its usage method; To achieve the above objectives, the present invention provides the following technical solution: a special boehmite hydrothermal device and its usage method, comprising a reaction vessel, wherein a magnetic stirring device is installed on the top of the reaction vessel, a feed inlet is provided at the upper end of the reaction vessel, and a secondary feeding component is connected to the feed inlet; The secondary feeding assembly is equipped with a balance pipe connecting to the reaction tank. A balance valve is installed on the balance pipe. The secondary feeding assembly includes a balance chamber tube. A discharge valve is fixed at one end of the balance chamber tube near the reaction tank, and a feed valve is fixed at the other end of the balance chamber tube. A lifting assembly is rotatably connected inside the balance chamber tube. A heating tube is wound around the outside of the balance chamber tube, and an insulation layer is provided outside the heating tube to wrap the balance chamber tube. The connection between the balance pipe and the balance chamber tube is tangent to the lifting assembly.

[0008] Preferably, the lifting assembly includes a lower lifting wheel, a middle lifting wheel, and an upper lifting wheel. The lower lifting wheel, the middle lifting wheel, and the upper lifting wheel have the same structure. A plurality of first stirring blades are provided between the lower lifting wheel and the middle lifting wheel, and a plurality of second stirring blades are provided between the middle lifting wheel and the upper lifting wheel, with the direction opposite to that of the first stirring blades.

[0009] Preferably, the lowering wheel includes two fixed rings arranged one in front of the other, and a plurality of V-shaped plates arranged along its circumference are fixed between the two fixed rings. The V-shaped plates are V-shaped, and the lower end of the balancing pipe is directly opposite the V-shaped groove of the V-shaped plate.

[0010] Preferably, the V-shaped plate has a V-shaped cavity inside that communicates with the balance chamber tube. The V-shaped cavity is V-shaped, and the first and second stirring blades are in contact with the inner wall of the balance chamber tube.

[0011] Preferably, the discharge valve adopts a double-seal structure, including an inner main sealing ring and an outer auxiliary sealing ring, and the main sealing ring and the auxiliary sealing ring are made of high and low temperature resistant fluororubber or metal-graphite composite material.

[0012] Preferably, pressure sensors for collecting pressure signals are installed in the and respectively, the pressure sensors are electrically connected to an external controller, and pressure relief valves and temperature sensors are respectively provided on the and respectively.

[0013] Preferably, a Laval pipe is installed inside the balancing pipe near the balancing chamber pipe, and a one-way valve is provided at the end of the balancing pipe near the reaction vessel.

[0014] Preferably, the reaction vessel is surrounded by a coiled pipe, and multiple supports are fixed along the circumference of the outer wall of the reaction vessel, with the supports located above the coiled pipe.

[0015] A method for using a special boehmite hydrothermal device includes the following steps: S1: Open the feed valve to allow the material to be added to enter the balance chamber tube, then close the feed valve. S2: The material in the equilibrium chamber is heated by the heating tube to make it consistent with the temperature difference inside the reaction vessel; S3: Slowly open the balance valve, and the high-pressure gas in the reaction vessel enters the interior of the balance chamber tube. The high-pressure gas passing through the Laval tube will be accelerated, generating a large impact force, which will drive the lifting component to rotate, so that the material in the balance chamber tube is heated evenly. S4: When the pressure inside the reaction vessel and the balance chamber tube is the same, open the discharge valve and close the balance valve. The material in the balance chamber tube enters the interior of the reaction vessel. After the feeding is completed, close the discharge valve and release the pressure in the balance chamber tube through the pressure relief valve.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By coordinating the balancing chamber tube, balancing pipes, and valves, secondary feeding is completed without disrupting the high-temperature and high-pressure environment of the reaction vessel, ensuring the continuity and stability of the reaction.

[0017] 2. The pressure difference between the reaction vessel and the feeding assembly creates an airflow that drives the lifting assembly with the first and second stirring blades to rotate, allowing the material to be fully lifted and mixed within the chamber tube. Combined with the heating tube and insulation layer, this significantly improves heating efficiency and the uniformity of material heating.

[0018] 3. The airflow-driven stirring is achieved by utilizing pressure difference, eliminating the need for additional power devices and saving energy; at the same time, automatic pressure regulation and control are achieved through pressure sensors, balance valves, etc., improving the automation level and operational safety of the device.

[0019] 4. The double-sealing structure of the discharge valve, along with the installation of the pressure relief valve and temperature sensor, effectively solves the sealing problem under high temperature and high pressure, while ensuring pressure and temperature safety during the operation of the device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the secondary feeding component of the present invention; Figure 3 This is a cross-sectional schematic diagram of the secondary feeding component of the present invention; Figure 4 This is a schematic diagram of the internal structure of the secondary feeding component of the present invention; Figure 5 This is a schematic diagram of the lifting component of the present invention; Figure 6 This is a cross-sectional schematic diagram of the lower impeller of the present invention; Figure 7 This is an external schematic diagram of the secondary feeding component of the present invention.

[0021] The diagram is labeled as follows: 1. Reaction vessel; 2. Secondary feeding assembly; 11. Feed inlet; 12. Support; 13. Pipeline; 14. Magnetic stirring device; 21. Feed end valve; 22. Balance chamber pipe; 23. Heating pipe; 24. Insulation layer; 25. Balance pipe; 26. Lifting assembly; 27. First stirring blade; 28. Second stirring blade; 29. ​​Discharge end valve; 251. Laval pipe; 252. Balance valve; 261. Lower lifting wheel; 262. Middle lifting wheel; 263. Upper lifting wheel; 2611. Fixing ring; 2612. V-shaped plate; 2613. V-shaped cavity. Detailed Implementation

[0022] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0023] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4 A special boehmite hydrothermal device and its usage method are disclosed, comprising a reaction tank 1. A magnetic stirring device 14 is installed on the top of the reaction tank 1 to perform basic stirring of the main materials inside the tank, solving the problem of uneven mixing of the main materials and ensuring the uniformity of the reaction. Simultaneously, the use of the magnetic stirring device 14 improves working efficiency, ensuring the device can operate for extended periods and preventing overheating protection due to prolonged motor operation, which would reduce efficiency. An inlet 11 is provided at the upper end of the reaction tank 1, and a secondary feeding assembly 2 is connected to the inlet 11 for secondary feeding under high temperature and high pressure conditions. A balance pipe 25 is provided on the secondary feeding assembly 2, connecting to the reaction tank 1. A balance valve 252 is provided on the balance pipe 25, used to regulate the pressure balance between the reaction tank 1 and the secondary feeding assembly 2. The secondary feeding assembly 2 includes a balance chamber pipe 22. A discharge valve 29 is fixed at one end of the balancing chamber tube 22 near the reaction tank 1. This valve adopts a double-seal structure, including an inner main sealing ring and an outer auxiliary sealing ring. The material is high and low temperature resistant fluororubber or metal-graphite composite material, which has excellent sealing performance and solves the sealing problem under high temperature and high pressure, ensuring that the pressure of the reaction tank 1 does not leak during the feeding process. A feed valve 21 is fixed at the other end of the balancing chamber tube 22 to control the entry of secondary materials. A lifting assembly 26 is rotatably connected inside the balancing chamber tube 22. A heating tube 23 is wound around the outside of the balancing chamber tube 22. The heating tube 23 is used to preheat or heat the secondary added materials. An insulation layer 24 is provided on the outside of the heating tube 23 to wrap the balancing chamber tube 22, which can reduce heat loss and improve heating efficiency. The connection between the balancing pipe 25 and the balancing chamber tube 22 is tangent to the lifting assembly 26, which facilitates the airflow to drive the lifting assembly 26 to rotate.

[0024] Please see Figure 3 , Figure 4 , Figure 5 and Figure 6The lifting assembly 26 includes a lower lifting wheel 261, a middle lifting wheel 262, and an upper lifting wheel 263. The lower lifting wheel 261, middle lifting wheel 262, and upper lifting wheel 263 have identical structures. Multiple first stirring blades 27 are arranged between the lower lifting wheel 261 and the middle lifting wheel 262, and multiple second stirring blades 28, opposite in direction to the first stirring blades 27, are arranged between the middle lifting wheel 262 and the upper lifting wheel 263. Through the lifting components in different directions, the material can be fully lifted and mixed within the cavity tube. When the lifting assembly 26 rotates, when the V-shaped plate 2612 reaches the lowest point of the balance cavity tube 22, the V-shaped plate 2612 will carry the material and rotate. At this time, when the lower lifting wheel 261 is at 90 degrees, the material outside the V-shaped plate 2612 begins to gradually fall until it all falls. Meanwhile, the V-shaped cavity 2613 and the V-shaped plate... The material between the V-shaped plate 2612 and the balance chamber tube 22 will continue to be carried and rotated. When the lifting wheel 261 rotates 180 degrees, the material between the V-shaped plate 2612 and the balance chamber tube 22 will gradually fall until it all falls. The material in the V-shaped cavity 2613 will begin to fall. When the lifting wheel 261 rotates 270 degrees, the material in the V-shaped cavity 2613 will be completely discharged, thereby better heating the material. At the same time, in conjunction with the second stirring blade 28, the material newly added to the balance chamber tube 22 will not move down quickly, ensuring the efficiency of material heating. Meanwhile, the first stirring blade 27 will push the material down. When the high temperature and high pressure in the balance chamber tube 22 meet the requirements, the discharge valve 29 is opened, and the first stirring blade 27 will quickly add the material inside the balance chamber tube 22 into the reaction tank 1.

[0025] Please see Figure 5 and Figure 6 The lowering wheel 261 includes two fixed rings 2611 arranged front and rear, and a plurality of V-shaped plates 2612 arranged along its circumference are fixed between the two fixed rings 2611. The V-shaped plates 2612 are V-shaped, and the lower end of the balancing pipe 25 is directly opposite the V-shaped groove of the V-shaped plate 2612, so that the airflow impacts the V-shaped plate and drives the lifting assembly 26 to rotate. The V-shaped plate 2612 has a V-shaped cavity 2613 that communicates with the balancing chamber pipe 22. The V-shaped cavity 2613 is V-shaped and can lift and mix the material. The first stirring blade 27 and the second stirring blade 28 are in contact with the inner wall of the balancing chamber pipe 22 to ensure smooth rotation.

[0026] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4The V-shaped plate 2612 has an internal V-shaped cavity 2613 that communicates with the balance chamber tube 22. The V-shaped cavity 2613 is V-shaped. The first stirring blade 27 and the second stirring blade 28 are fitted against the inner wall of the balance chamber tube 22. The discharge valve 29 adopts a double-seal structure, including an inner main sealing ring and an outer auxiliary sealing ring. The main sealing ring and the auxiliary sealing ring are made of high and low temperature resistant fluororubber or metal-graphite composite material. Pressure sensors for collecting pressure signals are installed in the reaction tank 1 and the balance chamber tube 22, respectively. The pressure sensors are electrically connected to the balance valve 252 and to an external controller, enabling automatic pressure adjustment. Control: The reaction tank 1 and the balance chamber pipe 22 are respectively equipped with a pressure relief valve and a temperature sensor. The pressure relief valve is used for safe pressure relief when the pressure is too high, and the temperature sensor is used to monitor the temperature to ensure the safe operation of the device. The balance pipe 25 is equipped with a Laval pipe 251 at the end near the balance chamber pipe 22, which can accelerate the airflow and enhance the driving force on the lifting component 26. The balance pipe 25 is equipped with a one-way valve at the end near the reaction tank 1 to prevent backflow of materials or gas. The reaction tank 1 is surrounded by a manifold 13. Multiple supports 12 are fixed along the circumference of the outer wall of the reaction tank 1 to support the reaction tank 1. The supports 12 are located above the manifold 13.

[0027] How to use this invention: Open the feed valve 21 to feed the material to be added a second time into the balance chamber tube 22. Then close the feed valve 21 and start the heating tube 23 to heat the material in the balance chamber tube 22, so that the temperature of the material is closer to the temperature difference inside the reaction tank 1. The material is fed in a sealed manner through the sealed feed valve 21 to avoid external interference. Preheating the material in advance can eliminate the impact of temperature difference on the reaction and ensure the stability of the reaction. Slowly open the balance valve 252. The high temperature and high pressure gas in the reaction tank 1 is accelerated through the balance pipe 25 and the Laval pipe 251 and impacts the V-shaped plate 2612 of the lifting assembly 26. The airflow drives the lower lifting wheel 261, the middle lifting wheel 262, the upper lifting wheel 263 and the first stirring blade 27 and the second stirring blade 28 to rotate, so that the material in the balance chamber tube 22 rotates. The material is thoroughly lifted and mixed by the stirring blades and V-shaped cavity, achieving uniform heating. The pressure difference between the reaction tank 1 and the secondary feeding assembly 2 forms the driving airflow, eliminating the need for an additional power unit and saving energy. The bidirectional design of the stirring blades and the material lifting process significantly improve heating uniformity and efficiency. When the internal pressure of the reaction tank 1 and the balance chamber tube 22 reaches equilibrium, the discharge valve 29 is opened and the balance valve 252 is closed, allowing the material to enter the reaction tank 1 under pressure equilibrium. After feeding is completed, the discharge valve 29 is closed, and the pressure relief valve is used to depressurize the balance chamber tube 22, completing the primary and secondary feeding process. The entire feeding process is carried out in a sealed environment under pressure equilibrium, completely solving the problem of feeding damaging the reaction environment in high-temperature and high-pressure reactions. The pressure relief operation ensures the safety of subsequent use of the equipment.

[0028] In summary, this device achieves stable secondary feeding under high temperature and high pressure through a continuous process of "feeding preheating - airflow stirring - pressure holding feeding". It also achieves efficient and uniform heating of materials by means of a stirring structure driven by pressure difference. It has the advantages of energy saving, high degree of automation and safe and reliable operation. At the same time, under the premise of ensuring high temperature and high pressure in reaction tank 1, the addition of some other substances, such as template agent and inducer, can produce very fine boehmite seed crystals and control the morphology and size of boehmite.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A special boehmite hydrothermal device, characterized in that: The reaction vessel (1) is equipped with a magnetic stirring device (14) on the top of the reaction vessel (1), and a feed inlet (11) is provided at the upper end of the reaction vessel (1). A secondary feeding assembly (2) is connected to the feed inlet (11). The secondary feeding assembly (2) is provided with a balance pipe (25) connecting to the reaction tank (1). The balance pipe (25) is provided with a balance valve (252). The secondary feeding assembly (2) includes a balance chamber pipe (22). One end of the balance chamber pipe (22) near the reaction tank (1) is fixed with a discharge valve (29). The other end of the balance chamber pipe (22) is fixed with a feed valve (21). The inside of the balance chamber pipe (22) is rotatably connected with a lifting assembly (26). The outside of the balance chamber pipe (22) is wrapped with a heating pipe (23). The outside of the heating pipe (23) is provided with a heat insulation layer (24) that wraps the balance chamber pipe (22). The connection between the balance pipe (25) and the balance chamber pipe (22) is tangent to the lifting assembly (26).

2. The special boehmite hydrothermal device according to claim 1, characterized in that: The lifting assembly (26) includes a lower lifting wheel (261), a middle lifting wheel (262), and an upper lifting wheel (263). The lower lifting wheel (261), the middle lifting wheel (262), and the upper lifting wheel (263) have the same structure. A plurality of first stirring blades (27) are provided between the lower lifting wheel (261) and the middle lifting wheel (262), and a plurality of second stirring blades (28) opposite in direction to the first stirring blades (27) are provided between the middle lifting wheel (262) and the upper lifting wheel (263).

3. A special boehmite hydrothermal device according to claim 2, characterized in that: The lowering wheel (261) includes two fixed rings (2611) arranged in front and behind, and a plurality of V-shaped plates (2612) arranged along its circumference are fixed between the two fixed rings (2611). The V-shaped plates (2612) are V-shaped, and the lower end of the balance pipe (25) is directly opposite the V-shaped groove of the V-shaped plate (2612).

4. A special boehmite hydrothermal device according to claim 3, characterized in that: The V-shaped plate (2612) has a V-shaped cavity (2613) inside that communicates with the balance chamber tube (22). The V-shaped cavity (2613) is V-shaped, and the first stirring blade (27) and the second stirring blade (28) are attached to the inner wall of the balance chamber tube (22).

5. A special boehmite hydrothermal device according to claim 4, characterized in that: The discharge valve (29) adopts a double sealing structure, including an inner main sealing ring and an outer auxiliary sealing ring, and the main sealing ring and the auxiliary sealing ring are made of high and low temperature resistant fluororubber or metal graphite composite material.

6. A special boehmite hydrothermal device according to claim 5, characterized in that: Pressure sensors for collecting pressure signals are installed in (1) and (22) respectively. The pressure sensors are electrically connected to (252) and to an external controller. Pressure relief valves and temperature sensors are respectively installed on (1) and (22).

7. A special boehmite hydrothermal device according to claim 6, characterized in that: The balance pipe (25) has a Laval pipe (251) installed inside the end near the balance chamber pipe (22), and a one-way valve is provided at the end of the balance pipe (25) near the reaction vessel (1).

8. A special boehmite hydrothermal device according to claim 7, characterized in that: The reaction vessel (1) is surrounded by a pipe (13), and a plurality of supports (12) are fixed along its circumference on the outer wall of the reaction vessel (1), with the supports (12) located above the pipe (13).

9. A method of using a special boehmite hydrothermal device, characterized in that: A special boehmite hydrothermal device according to claim 8, characterized in that it includes the following steps: S1: Open the feed valve (21) and the material to be added enters the interior of the balance chamber tube (22). Close the feed valve (21). S2: The material in the equilibrium chamber tube (22) is heated by the heating tube (23) so that the temperature difference between the material and the inside of the reaction vessel (1) is consistent. S3: Slowly open the balance valve (252), and the high-pressure gas in the reaction tank (1) enters the interior of the balance chamber tube (22). The high-pressure gas passing through the Laval tube (251) will be accelerated, generating a large impact force, which will drive the lifting component (26) to rotate, so that the material in the balance chamber tube (22) is heated evenly. S4: When the pressure inside the reaction tank (1) and the balance chamber tube (22) is consistent, open the discharge valve (29) and close the balance valve (252). The material in the balance chamber tube (22) enters the interior of the reaction tank (1). After the feeding is completed, close the discharge valve (29) and depressurize the balance chamber tube (22) through the pressure relief valve.

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