Heavy-duty single-cone vacuum dryer

The single-cone dryer is a derivative of the conical mixer. On the basis of the original single mixing function, it introduces a drying function (by adding a heating jacket outside the original conical cylinder), which can dry the material while stirring, achieving a dual-function effect with one machine. It can not only be used for drying heat-sensitive materials It can also be used for the mixing, reaction and drying of powder and powder, powder and liquid. This machine can effectively solve the problems of long working hours, low efficiency, high noise, easy caking, multiple leakage points, difficult maintenance, and inconvenient operation and cleaning of traditional drying equipment. It is a high-efficiency drying equipment with low unit energy consumption, high efficiency and good effect among similar domestic and foreign equipment currently used in the industry, and can be widely promoted in the pharmaceutical, chemical, pesticide, food and other industries.

In recent years, with the rapid development of the chemical industry and its growing scale, as the output and production capacity of products increase, equipment is constantly evolving towards larger series. The increase in output requires a corresponding increase in the heat exchange area, and the specifications are getting larger and larger. The power of the motor needed is also greater, and the occupied area is larger, resulting in an increase in production costs. The increase in output requires a corresponding rise in the pressure and temperature of the heating medium, which leads to a thicker wall thickness of the equipment cylinder and jacket, an increase in production costs, but a decrease in heat transfer efficiency. To solve the above-mentioned technical problems, Wuxi Srui has developed a large heavy-duty vacuum single cone dryer (Invention Patent No. : (202111275944.6) By setting up a double internal heating helical ribbon agitator in the lower cone, especially with a variable pitch helical ribbon, the linear velocities at each point on the helical ribbon surface are different during operation. Under its action, the material undergoes irregular convection, shearing, mixing and diffusion, forming a three-dimensional motion in all directions. Moreover, the internal heating helical ribbon is equipped with a new type of internal inclined structure, which can effectively solve the problem of material adhesion to the inner wall of the equipment cylinder. It has strong applicability and can achieve efficient forced heat transfer performance for materials with high viscosity, poor heat penetration, and prone to balling and clumping.

The heavy-duty single-cone vacuum dryer comprises a dryer body, which is composed of an upper cover and a lower cone. The upper cover is detachably connected to the upper end of the lower cone, characterized in that: The lower cone is provided with a double internal heating helical ribbon stirrer, which is a variable pitch helical ribbon stirrer. The lower end of the lower cone is fixed with a base plate, and a compressed air pulse fluidization device is also provided on the base plate. The compressed air pulse fluidization device is connected to the internal space of the lower cone. The base plate is also equipped with a pneumatic discharge ball valve. The outer surface of the upper cover is provided with a coil-type heating device. The outer surface of the lower cone is also provided with a spiral heating jacket. The top of the upper cover is provided with a pulse vacuum bag filter and an observation window. The upper cover is also connected to the main material pipeline.

Technical improvement of heavy-duty single-cone vacuum dryer

(1) Variable pitch internal heating helical ribbon stirrer

① Double internal heating helical ribbon agitator: During operation, the force is evenly distributed, the deformation caused by the rotation of the main shaft is small, and the heat transfer area is large.

The smaller the lead, the smaller the lift Angle of the helical ribbon, and the more turns it makes from the bottom to the top, thus the larger the heating area of the helical ribbon. The lead of the helical ribbon should not be too small; otherwise, the lifting Angle of the helical ribbon will be too small, causing the material to easily accumulate on the surface of the helical ribbon, affecting the stirring effect and discharge. The helical strip has a large lead and a large lift Angle. Although it does not accumulate material, the number of helical strip turns is small, and the heat transfer area is also small. To address the above issues, we adopted the method of multi-head helical tape, which was wound in the same direction with multi-head helical tape. This not only solved the problems of lead and lift Angle but also addressed the issue of heat transfer area.

② High-strength helical ribbon support rods: With low resistance and high strength, they enhance the effect of shearing and mixing materials, reduce the number of helical ribbon support rods, and minimize the impact on the instability of the hollow stirring shaft's operation caused by the lateral resistance of the material on the support rods when the hollow helical ribbon rotates.

③ Variable pitch helical ribbon agitator: It improves the three-directional compound movement of materials in the axial, radial and circumferential directions inside the machine, making the stirring and mixing effect reach the best state.

④ The external extension design of the twin-screw ribbon agitator features a staggered serrated scraping device, which reduces the load on the main shaft during operation and can efficiently break the material into lumps, effectively solving the problem of caking.

⑤ An adjustable scraper is set at the lower end of the shaft, closely adhering to the bottom plate of the cone to improve the stirring and mixing effect of the material at the bottom of the cone.

⑥ The circulation problem of the heat medium in the hollow shaft and the hollow helical ribbon has been solved

If the heat medium does not circulate well in the hollow shaft and hollow screw ribbon, the material will cool down quickly, affecting the normal operation process. For this reason, we have conducted extensive research work. While ensuring the continuous rotation of the hollow shaft and hollow helical ribbon, the heat medium enters from the top and, after circulating through all the hollow shafts and hollow helical ribbons, flows out from the top. That is, the heat medium enters and exits through two separate channels without being related to each other, allowing the heat medium to circulate fully within the machine and significantly improving the drying efficiency.

(2) Internal heating helical ribbon spindle

The new type of stirring main shaft enables the material to achieve a three-directional compound motion of axial, radial and circumferential movement inside the machine. It spirals from the bottom to the top for material lifting and then falls back to the bottom. With a long movement stroke, its stirring and mixing effect is extremely excellent.

② Low shear force helical ribbon stirring paddles are adopted to gently mix the materials at low speed and low energy consumption. The intensity of the mixture and the mixing time are both relatively low.

Based on the traditional jacket heating, the internal heat of the inner heating ribbon is utilized to make the entire heating area reach 140% of the container, significantly enhancing the heating efficiency.

④ By adopting a new type of internal heating helical ribbon structure, the agitator and the conical filter have a good adhesion and scraping effect on the wall, which enables the material to be filtered under thin-layer filter cake conditions and improves the filtration efficiency.

⑤ The new type of stirring main shaft and internal heating screw ribbon have strong applicability. Materials with high viscosity, poor heat penetration, and prone to balling and clumping can achieve efficient forced heat transfer performance.

⑥ The bottom of the agitator is closely attached to the bottom of the cone and the sealing spherical surface of the discharge valve, avoiding dead corners, improving the drying and mixing efficiency, and ensuring clean discharge without residue.

(3) New type of lower cone

The new type of lower cone can significantly reduce the overall height of the dryer, facilitating equipment installation and lowering the infrastructure investment cost of the workshop building.

② Reduce caking: The short shaft and the main shaft have small rotational disturbance deformation, high main shaft accuracy, and a small gap with the inner wall of the lower cone.

③ By using a compressed air pulse fluidization device at the bottom of the container, the areas with poor mixing performance at the lower part of the container can be eliminated.

④ Spiral semi-return pipe jacket

With the development of modern chemical industry, chemical production is trending towards large-scale and industrialized development. The output of individual production facilities is increasing, and single-cone vacuum dryers are also gradually moving towards large-scale development. At this point, the diameter of the single-cone dryer increases, and the cone lengthens. Especially when the jacket pressure is higher than 1.0MPa, the thickness of the inner cylinder wall increases, which adds difficulty to the design and manufacture of the vacuum single-cone dryer and correspondingly raises the manufacturing cost of the equipment. Therefore, it is relatively economical and reasonable to achieve the purpose of thinning the wall and enhancing the pressure-bearing capacity of the inner cylinder by choosing an appropriate jacket structure.

(4) The upper cover coil-type heating device has a good heating effect, is simple and efficient to manufacture, and does not affect the production of multiple process pipe openings on the upper cover.

(5) New type of base plate

① Set up a heating jacket to enhance the drying effect;

② The detachable main shaft support structure facilitates the disassembly, assembly and replacement of the shaft sleeve.

③ The material temperature transmitter and vacuum sampler are set on the base plate, which reduces the manufacturing difficulty of the conical heating jacket.

④ The installation structure of the new type of discharge ball valve ensures that the sealing ball closely adheres to the bottom plate plane, achieving discharge without dead corners.

Process flow chart of heavy-duty single-cone vacuum dryer

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