A drying control method for producing hemihydrate gypsum whiskers by using a rapid flashing technique

Abstract

The application discloses a drying control method for producing gypsum whiskers by using flash drying technology, and integrates the control of hot air shearing force field, hot air flow field distribution, water-containing gypsum whisker concentration field, water-containing gypsum whisker rheological behavior, apparent moisture rapid vaporization of gypsum whiskers and superdispersion behavior of gypsum whiskers in the drying process based on the flash drying mechanism, so that the calcium sulfate hemihydrate whiskers formed under the hydrothermal system rapidly pass through the high-temperature environment, the time for the calcium sulfate hemihydrate whiskers to change the structure and morphology under the high-temperature environment is greatly shortened, and the genetic property in the gypsum whisker production process is achieved, the whisker products produced by using the application have the advantages of stable quality, low whisker breakage rate and good dispersion degree, and thus technical support is provided for the large-scale production of inorganic crystal materials by the hydrothermal method.

Description

Technical Field

[0001] This invention relates to the field of stabilization control in promoting the final drying of hemihydrate gypsum whiskers by hydrothermal production, and particularly to a drying control method for producing hemihydrate gypsum whiskers using flash technology. Background Technology

[0002] Currently, industrial-scale mass production remains a technological bottleneck for the hydrothermal method of gypsum production. This involves not only the hydrothermal preparation process but also the drying process, and the ability to inherit the initial state of the product in situ, which is particularly crucial for the application of inorganic single crystal materials. Because the drying process is conducted in a high-temperature environment, hydrated inorganic crystal materials are prone to secondary crystallization and phase transformation under high-temperature and humid conditions, as well as particle agglomeration and clumping. This is one of the main factors hindering the stable implementation of the hydrothermal method in industrial applications. Furthermore, the hemihydrate gypsum whiskers produced by thermal crystallization in the hydrothermal system contain approximately 20% apparent water during solid-liquid separation. This makes the whiskers highly susceptible to phase transformation, secondary crystal growth, and brittle fracture during drying, leading to product instability and severely hindering product application. Although domestic and international research institutions have made beneficial attempts at drying whiskers, such as calcination kiln whisker drying, tunnel kiln whisker drying, drum drying, and chain whisker drying, none of these methods can suppress the secondary recrystallization process of whiskers. This results in excessive brittleness of the whisker products, causing significant breakage when mixed with materials such as rubber, asphalt, and engineering plastics. Consequently, the performance of composite materials degrades and fluctuates, severely hindering the market absorption of gypsum whiskers. Therefore, this invention, based on the concept of in-situ genetic flash drying, aims to create a favorable environment for the rapid vaporization and evaporation of surface moisture in gypsum whiskers during the drying process. This avoids structural and morphological changes in gypsum whiskers during drying, thus providing technical support for the large-scale production of hydrothermal whiskers.

[0003] National Utility Model Patent CN210135765U discloses a whisker chain dryer, characterized by: a whisker preparation component and a drying chamber. The drying chamber is connected to the whisker preparation component, and a conveying component is provided between the drying chamber and the whisker preparation component. The whiskers prepared by the whisker preparation component are transported to the drying chamber via the conveying component. The drying chamber includes a shell, and a receiving cavity is provided inside the shell. Multiple rows of air supply components are arranged in the receiving cavity, and the air supply components are arranged along the length direction of the conveying component. The height of the air supply components is higher than the height of the conveying component. The air supply components are used to provide air energy to the whiskers on the conveying component and dry the whiskers through air energy. By setting up multiple rows of air supply components, the air volume provided to the whiskers can be increased, which can improve the drying effect of the whisker drying component. However, due to the excessively long drying time, the gypsum whiskers are prone to secondary crystallization, resulting in a significant increase in the brittleness of the whiskers.

[0004] National Utility Model Patent CN202221007831.8 discloses a drying device for the production of calcium sulfate whiskers. Its features include: a screening chamber within the housing, a feed hopper communicating with the screening chamber at the top of the housing, a screening frame within the screening chamber, a moving rod at one end of the screening frame, a positioning frame on the outside of the housing, a crank within the positioning frame, and a motor whose output end is fixedly connected to the center of the bottom of the crank. A fixed column is fixedly connected to the top of the crank near its edge, and a connecting rod is rotatably connected to the fixed column. The connecting rod is rotatably connected to the moving rod. Although this device can agitate the calcium sulfate whisker raw material, improving the uniformity of whisker drying, it still cannot solve the problem of excessively long gypsum retention during the drying process, resulting in high brittleness during secondary crystallization.

[0005] National Utility Model Patent CN216790788U discloses an auxiliary device for drying calcium sulfate whiskers. Its features include: a drying cylinder and a support frame for the drying cylinder; a conveyor belt is installed inside the drying cylinder; and a dispersing frame is installed inside the drying cylinder. The dispersing frame consists of a connecting frame and dispersing blocks, with multiple dispersing blocks evenly distributed below the connecting frame. The bottom of each dispersing block is in contact with the surface of the conveyor belt, and the two can slide relative to each other. Each dispersing block has a triangular prism structure, with one ridge facing away from the direction of travel of the conveyor belt. Although this device can disperse calcium sulfate whiskers multiple times during transport and form new wavy cross-sections, further improving the drying efficiency of the drying cylinder, the limited rotation speed means that the whiskers are prone to secondary crystallization and brittleness at low speeds, while at high speeds, the whiskers are easily broken, thus failing to solve the problem of rapid flash evaporation.

[0006] In summary, this invention not only solves the problems of hot air shear force field control, hot air flow field distribution control, hydrated gypsum whisker concentration field control, hydrated gypsum whisker rheological behavior control, rapid vaporization control of apparent moisture in gypsum whiskers, and ultradispersion behavior of gypsum whiskers during the drying process, but also integrates gypsum whisker product stabilization control, rapid vaporization of apparent water, and ultradispersion into a unified system, thus providing a guarantee for the drying equipment of gypsum whiskers for large-scale hydrothermal production. The drying control method for producing hemihydrate gypsum whiskers using flash technology is a newly developed technology. Calcium sulfate whiskers produced by the drying system using this technology have advantages such as high product quality, high dispersion, and low whisker product breakage. Summary of the Invention

[0007] The purpose of this invention is to provide a drying control method for producing hemihydrate gypsum whiskers using flash technology, which allows hemihydrate calcium sulfate whiskers formed in a hydrothermal system to pass through a high-temperature environment at extremely high speed. This aims to greatly shorten the time for hemihydrate gypsum whiskers to change their structure and morphology under high temperature conditions, thereby achieving the heritability in the gypsum whisker production process and providing technical support for the large-scale production of inorganic crystal materials by hydrothermal method.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] This invention discloses a drying control method for producing hemihydrate gypsum whiskers using flash flash technology, comprising:

[0010] Ambient air is blown into a direct-fired heating furnace and heated to 400-500℃. The air enters tangentially from the bottom of the drying equipment, with a hot air volume of 3000-30000 m³ / h and an air pressure of 1200-25000 Pa. Simultaneously, the material is quantitatively added by a continuously variable frequency double-spiral shaftless feeder. To prevent relatively large clumps of whiskers from agglomerating, a disperser is installed in the fluidization section to ensure full contact between the hot air and the gypsum whiskers. The residence time in the high-temperature zone of the drying chamber is extremely short, and the speed of the disperser is 0-120 r / min. Under the synergistic effect of the disperser and the high-speed hot air flow, the gypsum whiskers are fluidized, which not only expands the evaporation area of ​​the apparent water but also improves the mass and heat transfer rate between the gypsum whiskers and the hot air. This allows the water molecules on the surface of the whiskers to flash vaporize rapidly, completing the drying process within 2-4 seconds.

[0011] Meanwhile, to avoid the problem of whiskers colliding with each other and breaking due to collisions with the vessel wall during fluidization, the cutting force field angle is 5-10°. After passing through the classifier at the top of the drying chamber, the ultra-dispersed whiskers enter the cyclone separator and pulse bag filter along with the drying exhaust gas for gas-solid separation. The finished whiskers are then discharged uniformly through the product storage tank.

[0012] Furthermore, the outlet air temperature is 120-180℃, the main unit inner diameter is 500-2000mm, the main unit height is 2000-10000mm, the drying capacity is 200-2000 kgH2O / h, and the product output after drying is 1-30t / h / unit.

[0013] Furthermore, the discharge temperature is ≤45℃.

[0014] Furthermore, the material contact parts in the drying equipment are made of 304 stainless steel.

[0015] Furthermore, the three-phase AC voltage is 380V and 50Hz.

[0016] Furthermore, the classifier at the top of the drying chamber is a multi-angled perforated circular distribution disk to ensure the super-dispersion and uniformity of humidity of the whisker products.

[0017] Furthermore, the product recovery rate is >99.8%, and the whisker breakage rate is <10%.

[0018] Furthermore, it also includes a remote intelligent control system for realizing the intelligent operation of the drying control method.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] The flash drying method of this invention adopts a fully enclosed negative pressure operation, with no dust leakage, a product recovery rate of >99.8%, and a whisker breakage rate of <10%. It can be used for continuous production with stable product quality. It is a high-efficiency and energy-saving gypsum whisker drying device that integrates drying, dispersion, and grading. The grader at the top of the drying chamber is a multi-angled perforated circular distribution plate, which can ensure the super-dispersion and uniformity of humidity of the whisker product.

[0021] This invention integrates a synergistic control technology encompassing hot air shear force field control, hot air flow field distribution control, hydrous gypsum whisker concentration field control, hydrous gypsum whisker rheological behavior control, rapid vaporization control of apparent moisture in gypsum whiskers, and ultra-dispersion behavior of gypsum whiskers. By rapidly vaporizing the apparent water in the whiskers during the drying process, it avoids changes in the structure, morphology, and properties of gypsum crystals due to secondary crystallization, thereby facilitating the large-scale production of gypsum whiskers using the hydrothermal method. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram illustrating the principle of flash drying.

[0024] Figure 2 This is a process flow diagram of the drying control method for producing hemihydrate gypsum whiskers using flash technology according to the present invention. Detailed Implementation

[0025] Example 1:

[0026] First, ambient temperature air is blown into a direct-fired heating furnace and heated to 500℃. The air then enters tangentially from the bottom of the drying equipment, with a hot air volume of 3000 m³ / h and an air pressure of 1200 Pa. Simultaneously, material is quantitatively added by a continuously variable frequency double-spiral shaftless feeder. The disperser rotates at 0 r / min, with a cutting force field angle of 5°. After passing through a top classifier, the material resides in the dryer for 2 seconds. Ultra-dispersed whiskers, along with the drying exhaust gas, enter a cyclone separator and a pulse bag filter for gas-solid separation. The finished whiskers are then discharged through a product storage tank. The system features an outlet air temperature of 120℃, a main unit inner diameter of 500 mm, a main unit height of 2000 mm, a drying capacity of 200 kgH₂O / h, a post-drying product output of 1 t / h, a recovery method of a high-efficiency cyclone separator + pulse bag filter, an outlet temperature ≤45℃, and the material contact parts in the drying equipment are made of 304 stainless steel. The three-phase AC voltage is 380V and 50Hz. The method of this invention adopts a fully enclosed negative pressure operation, with no dust leakage, a product recovery rate of >99.8%, and a whisker breakage rate of <8%.

[0027] Example 2:

[0028] First, ambient temperature air is blown into the direct-fired heating furnace by a blower and heated to 400℃. The air enters tangentially from the bottom of the drying equipment with a hot air volume of 30,000 m³ / h and a pressure of 25,000 Pa. Simultaneously, the material is quantitatively added by a continuously variable frequency double-spiral shaftless feeder. To avoid agglomeration of relatively large clumps of whiskers, a disperser is installed in the fluidization section to ensure full contact between the hot air and the gypsum whiskers. The residence time in the high-temperature zone of the drying chamber is extremely short, and the speed of the disperser is 120 r / min. Under the synergistic effect of the disperser and the high-speed hot air flow, the gypsum whiskers are fluidized, which not only expands the evaporation area of ​​the apparent water but also improves the mass and heat transfer rate between the gypsum whiskers and the hot air. This allows the water molecules on the surface of the whiskers to flash vaporize rapidly, completing the drying process within 4 seconds. Meanwhile, to avoid whisker collisions and breakage due to collisions with the vessel wall during fluidization, the cutting force field angle is 10°. After passing through a top classifier, the ultra-dispersed whiskers, along with the drying exhaust gas, enter a cyclone separator and a pulse bag filter for gas-solid separation. The finished whiskers are then discharged through a product storage tank. The outlet air temperature is 180℃, the main unit inner diameter is 500~2000mm, the main unit height is 10000mm, the drying capacity is 2000 kgH2O / h, the product output after drying is 30t / h / unit, the recovery method is a high-efficiency cyclone separator + pulse bag filter, the discharge temperature is ≤45℃, the material contact parts in the drying equipment are made of 304 stainless steel, and the three-phase AC voltage is 380V and 50Hz. The method of this invention adopts a fully enclosed negative pressure operation, with no dust leakage, a product recovery rate >99.8%, and a whisker breakage rate <10%.

[0029] Example 3:

[0030] First, ambient temperature air is blown into the direct-fired heating furnace by a blower and heated to 400~500℃. The hot air enters tangentially from the bottom of the drying equipment with a hot air volume of 10000 m³ / h and an air pressure of 10000 Pa. At the same time, the material is quantitatively added by a stepless variable frequency double spiral shaftless feeder. To avoid the aggregation of relatively large lumps of whiskers, a disperser is installed in the fluidization section to ensure full contact between the hot air and the gypsum whiskers. The residence time in the high-temperature zone of the drying chamber is extremely short, and the speed of the disperser is 60 r / min. Under the synergistic effect of the disperser and the high-speed hot air flow, the gypsum whiskers are fluidized, which not only expands the evaporation area of ​​the apparent water but also improves the mass and heat transfer rate between the gypsum whiskers and the hot air. This allows the water molecules on the surface of the whiskers to flash vaporize rapidly, completing the drying process within 2~4 seconds. Meanwhile, to avoid whisker collisions and breakage due to collisions with the vessel wall during fluidization, the cutting force field angle is 8°. After passing through a top classifier, the ultra-dispersed whiskers, along with the drying exhaust gas, enter a cyclone separator and a pulse bag filter for gas-solid separation. The finished whiskers are then discharged through a product storage tank. The outlet air temperature is 160℃, the main unit inner diameter is 1000mm, the main unit height is 8000mm, the drying capacity is 1000 kgH2O / h, the product output after drying is 10t / h, the recovery method is a high-efficiency cyclone separator + pulse bag filter, the discharge temperature is ≤45℃, the material contact parts in the drying equipment are made of 304 stainless steel, and the three-phase AC voltage is 380V and 50Hz. The method of this invention adopts a fully enclosed negative pressure operation, with no dust leakage, a product recovery rate >99.8%, and a whisker breakage rate <6%.

[0031] Example 4:

[0032] First, ambient temperature air is blown into the direct-fired heating furnace by a blower and heated to 400~500℃. The air enters tangentially from the bottom of the drying equipment, with a hot air volume of 8000 m³ / h and an air pressure of 8000 Pa. At the same time, the material is quantitatively added by a stepless variable frequency double spiral shaftless feeder. To avoid the aggregation of relatively large clumps of whiskers, a disperser is installed in the fluidization section to ensure full contact between the hot air and the gypsum whiskers. The residence time in the high-temperature zone of the drying chamber is extremely short, and the speed of the disperser is 40 r / min. Under the synergistic effect of the disperser and the high-speed hot air flow, the gypsum whiskers are fluidized, which not only expands the evaporation area of ​​the apparent water but also improves the mass and heat transfer rate between the gypsum whiskers and the hot air. This allows the water molecules on the surface of the whiskers to flash vaporize rapidly, completing the drying process within 2~4 seconds. Meanwhile, to avoid whisker collisions and breakage due to collisions with the vessel wall during fluidization, the cutting force field angle is 6°. After passing through a top classifier, the ultra-dispersed whiskers, along with the drying exhaust gas, enter a cyclone separator and a pulse bag filter for gas-solid separation. The finished whiskers are then discharged through a product storage tank. The outlet air temperature is 140℃, the main unit inner diameter is 1200mm, the main unit height is 6000mm, the drying capacity is 800 kgH2O / h, the dried product output is 8t / h, the recovery method is a high-efficiency cyclone separator + pulse bag filter, the outlet temperature is ≤45℃, the material contact parts in the drying equipment are made of 304 stainless steel, and the three-phase AC voltage is 380V and 50Hz. The method of this invention adopts a fully enclosed negative pressure operation, with no dust leakage, a product recovery rate >99.8%, and a whisker breakage rate <10%.

[0033] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A drying control method for producing hemihydrate gypsum whiskers using flash flash technology, characterized in that, include: Ambient air is blown into a direct-fired heating furnace and heated to 400-500℃. The air enters tangentially from the bottom of the drying equipment, with a hot air volume of 3000-30000 m³ / h and an air pressure of 1200-25000 Pa. Simultaneously, the material is quantitatively added by a continuously variable frequency double-spiral shaftless feeder. To prevent relatively large lumps of hemihydrate gypsum whiskers from agglomerating, a disperser is installed in the fluidization section to ensure full contact between the hot air and the hemihydrate gypsum whiskers. The residence time in the high-temperature zone of the drying chamber is extremely short, and the speed of the disperser is 0-120 r / min. Under the synergistic effect of the disperser and the high-speed hot air flow, the hemihydrate gypsum whiskers are fluidized, which not only expands the evaporation area of ​​the apparent water but also improves the mass and heat transfer rate between the hemihydrate gypsum whiskers and the hot air. This allows the water molecules on the surface of the hemihydrate gypsum whiskers to flash vaporize rapidly, completing the drying process within 2-4 seconds. Meanwhile, to avoid collisions between hemihydrate gypsum whiskers and breakage due to collisions with the vessel wall during fluidization, the cutting force field angle is 5-10°. After passing through the classifier at the top of the drying chamber, the ultra-dispersed hemihydrate gypsum whiskers enter the cyclone separator and pulse bag filter along with the drying exhaust gas for gas-solid separation. The finished hemihydrate gypsum whiskers are then discharged uniformly through the product storage tank. Product recovery rate > 99.8%, hemihydrate gypsum whisker breakage rate < 10%.

2. The drying control method for producing hemihydrate gypsum whiskers using flash flash technology according to claim 1, characterized in that, The outlet air temperature is 120-180℃, the main unit inner diameter is 500-2000mm, the main unit height is 2000-10000mm, the drying capacity is 200-2000 kgH2O / h, and the output of dried products is 1-30t / h / unit.

3. The drying control method for producing hemihydrate gypsum whiskers using flash flash technology according to claim 1, characterized in that, Discharge temperature ≤45℃.

4. The drying control method for producing hemihydrate gypsum whiskers using flash flash technology according to claim 1, characterized in that, The parts in contact with the material in the drying equipment are made of 304 stainless steel.

5. The drying control method for producing hemihydrate gypsum whiskers using flash flash technology according to claim 1, characterized in that, Three-phase AC voltage: 380V and 50Hz.

6. The drying control method for producing hemihydrate gypsum whiskers using flash flash technology according to claim 1, characterized in that, The classifier at the top of the drying chamber is a multi-angled perforated circular distribution disc to ensure the super-dispersibility and uniformity of humidity of the hemihydrate gypsum whisker product.

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