Rotary electrostatic coating pipe baking and curing device

Abstract

This invention relates to a rotary electrostatic plastic-coated tube array baking and curing device. A rotating assembly is installed within a housing. The rotating assembly includes a central rotating shaft driven by a motor, with wheel disks at both ends. Multiple plastic-coated tube arrays are arranged between the two wheel disks. An electric heater is installed at the bottom of the housing, and two cross-flow fans are installed above the electric heater, spaced apart on both sides of the lower part of the rotating assembly. Air duct baffles are installed on both sides of the rotating assembly above the cross-flow fans. The electric heater and cross-flow fans on both sides of the bottom, separated by air duct baffles, allow for heating and baking of the plastic-coated tube arrays on the rotating assembly. This invention ensures uniform heating of the plastic-coated tube arrays, resulting in the plastic powder melting and adhering evenly to the tube wall. This avoids uneven plasticizing caused by uneven flow and temperature, guaranteeing the quality of the plastic coating and curing. It is suitable for large-scale production of plastic coating and curing on the surfaces of bare tubes or finned tubes, improving production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of baking and curing technology of electrostatically coated steel composite heat exchange tubes, and in particular, a baking and curing device for a rotary electrostatically coated tube array. Background Technology

[0002] Heat exchangers are widely used in fields such as flue gas waste heat recovery and wastewater concentration, but corrosion significantly reduces their service life. To address this corrosion problem, fluoroplastic tubes and fluoroplastic-steel composite tube heat exchangers have begun to be used. Fluoroplastic-steel composite tubes are made by applying a layer of soluble fluoroplastic to the surface of a steel pipe using a hot-melt spraying process, which provides both corrosion resistance and high pressure resistance.

[0003] However, this hot-melt spraying process can only coat a single pipe, resulting in very low production efficiency. Furthermore, it is only suitable for coating fusible fluoroplastics and cannot process non-fusible fluoroplastics such as polytetrafluoroethylene (PTFE). Electrostatic coating and curing is a mature process suitable for mass production, applicable to various types of plastic powders, and highly efficient for assembly line production. However, for the curing of electrostatic coatings on slender pipes, the uneven thickness of the plasticized layer generated along the flow significantly affects its heat transfer and corrosion resistance. Especially for thicker plasticized layers, if temperature control is uneven or has large errors, and heating and cooling times are long, it will cause uneven thickness of the plasticized layer along the flow of the molten layer, affecting product quality.

[0004] Traditional baking and curing production lines are either suspended and mobile or stationary, making it difficult to overcome the aforementioned problems. Therefore, there is a need to develop a new baking and curing device that can control the uniformity of the molten plasticized layer outside the heat exchange tubes, achieve high-efficiency large-scale production, and adapt to the curing of various plastic powders. Summary of the Invention

[0005] To address the problem of uneven plasticized layer thickness that is difficult to avoid in traditional composite pipe coating and curing devices during the baking and curing process, this invention proposes a rotary electrostatic plastic-coated pipe array baking and curing device. The plastic-coated pipe array is fixed on a wheel and rotates continuously inside a heating and curing chamber to obtain a composite heat exchange pipe with a uniform plasticized layer thickness. Therefore, the technical solution adopted by the present invention is: a rotary electrostatic plastic-coated pipe rack baking and curing device, comprising a housing, characterized in that a rotating assembly is provided inside the housing, the rotating assembly includes a central rotating shaft driven by a motor, the central rotating shaft has wheel disks at both ends, and multiple plastic-coated pipe racks are arranged between the two wheel disks, an electric heater is provided at the bottom of the housing, and two cross-flow fans are provided above the electric heater, spaced apart on both sides of the lower part of the rotating assembly, and air duct baffles are provided on both sides of the rotating assembly above the cross-flow fans. With electric heaters and cross-flow fans on both sides of the bottom, and air duct baffles separating the air ducts on both sides, the plastic-coated pipe racks on the rotating assembly are heated and baked.

[0006] Preferably, an air distribution plate is provided between the two cross-flow fans. Hot air is drawn in from the top of the air duct, blown past the electric heater, blown out from the bottom, and then evenly blown onto the powder-coated pipe array after passing through the air distribution plate.

[0007] Preferably, one end of the wheel is fixed, while the other end can move on the rotating shaft. This facilitates clamping plastic-coated pipe arrays of different lengths.

[0008] Preferably, the plastic-coated pipe array is made by using horizontal and vertical fixing angle steels to tightly fix the plastic-coated pipes onto two wheel discs.

[0009] Preferably, the rotating shaft is fixed in a bearing and connected to a drive motor via a coupling. The plastic powder coating on the outer surface of the tube bank is heated and melted. To avoid uneven thickness caused by the flow and to make the tubes heat more evenly, the drive motor drives the rotating wheel to rotate the tube bank together.

[0010] Preferably, the housing includes a lower box and an upper box cover, and the upper box cover is removable.

[0011] Preferably, an oxygen meter and an exhaust valve are installed on one side of the top of the upper casing. The exhaust valve can be a check valve, which can be opened and closed without manual operation.

[0012] Preferably, a temperature sensor is also installed on the upper casing. The temperature sensor detects the heating temperature and controls the power of the electric heater via an external electrical control box.

[0013] Preferably, a nitrogen valve is installed on one side of the lower chamber. To prevent oxidation of the plasticized layer, a nitrogen inlet pipe and inlet valve are provided along the axial direction of the cross-flow fan. Nitrogen is blown in to displace the air inside the chamber and discharged from the exhaust valve on the upper chamber cover until the oxygen meter reading is lower than the specified value. This nitrogen is also used to blow in the curing and cooling process to control the cooling rate.

[0014] The beneficial effects of this invention are as follows: It proposes a plastic-coated tube curing device that heats and rotates at the same time, so that the plastic-coated tube is heated evenly and the plastic powder on its surface is uniformly adhered to the tube wall after melting. This avoids uneven plasticizing layer caused by uneven flow and temperature, and can ensure the quality of plastic coating curing. It is suitable for mass production of plastic coating curing on the surface of bare tubes or finned tubes, and improves production efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention.

[0016] Figure 2 for Figure 1 AA cross-section view.

[0017] In the attached diagram: 1. Upper housing cover; 2. Wheel disc; 3. Horizontal fixed angle steel; 4. Vertical fixed angle steel; 5. Fixed square tube; 6. Plastic-coated pipe; 7. Oxygen meter; 8. One-way exhaust valve; 9. Bearing seat; 10. Central rotating shaft; 11. Air distribution plate; 12. Nitrogen valve; 13. Electric heater; 14. Cross-flow fan; 15. Lower housing; 16. Drive motor; 17. Coupling; 18. Fixing pin; 19. Air duct baffle; 20. Temperature sensor. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 and Figure 2 The rotary electrostatic plastic-coated pipe baking and curing device shown includes: an upper box cover 1, a wheel 2, a horizontal fixed angle steel 3, a vertical fixed angle steel 4, a fixed square tube 5, a plastic-coated pipe 6, an oxygen meter 7, a one-way exhaust valve 8, a bearing seat 9, a rotating shaft 10, an air distribution plate 11, a nitrogen valve 12, an electric heater 13, a cross-flow fan 14, a lower box 15, a drive motor 16, a coupling 17, a fixing pin 18, an air duct isolation plate 19, and a temperature sensor 20.

[0020] A rotating wheel assembly is installed inside the housing consisting of an upper cover and a lower housing. The rotating wheel assembly includes a central rotating shaft 10 driven by a motor. The central rotating shaft has wheel disks 2 at both ends, and multiple plastic-coated pipe rows are arranged between the two wheel disks 2. An electric heater 13 is installed at the bottom of the housing. A cross-flow fan 14 is installed above the electric heater 13. There are two cross-flow fans, which are spaced apart on both sides of the lower part of the rotating wheel assembly. Air duct baffles 19 are installed on both sides of the rotating wheel assembly above the cross-flow fans.

[0021] The baking and curing oven is divided into upper and lower parts. The upper cover is removable, facilitating the installation and removal of the coated tubing. The lower chamber is fixed, with a rotating shaft secured by a bearing seat. A drive motor is mounted outside the lower chamber, driving the rotating wheel via a coupling. One end of the rotating wheel is fixed, while the other end is axially adjustable and secured with a pin to accommodate changes in the tubing length.

[0022] The plastic-coated pipe array consists of plastic-coated pipes and square tubes fixed at both ends. They are horizontally installed and stacked one by one, secured with horizontal and vertical angle steel to prevent displacement during rotation. Two sets of electric heaters and two cross-flow fans are installed at the bottom of the lower chamber. The power of the electric heaters is controlled by a temperature sensor. Air duct baffles are also located on both sides of the lower chamber to isolate the rotating space from the airflow of the cross-flow fans, allowing hot air to circulate within the chamber. The plastic-coated pipe array is fixed between two discs by fasteners and rotates slowly by a drive motor, ensuring uniform heating of the pipe array. The molten plastic layer on its surface continuously changes its flow direction as the pipe array rotates, maintaining a uniform surface thickness.

[0023] Specifically, a perforated air distribution plate is installed above the air outlet of the cross-flow fan to ensure that the airflow is evenly directed toward the plastic-coated pipe array.

[0024] Specifically, the plastic-coated pipe is tightly fixed to the two wheel discs 2 by horizontal fixing angle steel 3 and vertical fixing angle steel 4.

[0025] An oxygen meter 7 and an exhaust valve 8 are installed on one side of the top of the upper chamber cover 1. A temperature sensor 20 is also installed on the upper chamber cover. For high-temperature plasticizing, it is necessary to control the oxygen concentration inside the chamber by replacing the air inside the chamber with nitrogen. A one-way exhaust valve and an oxygen meter are installed on the upper chamber cover. A nitrogen inlet is opened at the lower chamber along the axis of the cross-flow fan, and a nitrogen valve is installed to introduce nitrogen to control the atmosphere inside the chamber and control the cooling rate of the plastic-coated pipes.

[0026] The working process of this invention is as follows: First, remove the upper casing. Then, carefully hoist the electrostatically coated pipe arrays, row by row, onto the rotating wheel to avoid impact and vibration. After installing the pipe arrays on the half-wheel, use the bottom-fixed rotatable vertical fixing angle steel to laterally press the square tubes of the pipe array to make them neat and tight. Then fix the upper end, and then fix the horizontal fixing angle steel. Finally, hoist the upper casing onto the lower casing.

[0027] For high-temperature plasticizing requiring controlled atmosphere, open the nitrogen gas source, nitrogen valve, and exhaust valve to replace the air inside the chamber. Once the oxygen concentration at the exhaust port reaches the set value, close the nitrogen valve. Turn on the drive motor to slowly increase the speed of the rotor to a fixed speed, then turn on the cross-flow fan and power on the electric heater. Adjust the temperature according to the specific baking and curing process requirements of the coated material. Cooling is performed according to the curing process requirements. First, lower the temperature setpoint and reduce the electric heating power until the electric heating is stopped. To adjust the cooling rate, open the nitrogen valve to blow in nitrogen and turn on the cross-flow fan for circulation. After complete cooling, remove the upper chamber cover, take off the cured coated pipe array, and remove the fixed square tubes at both ends of the pipe array to obtain the steel-plastic composite pipe. One production cycle is then complete.

[0028] This invention is specifically designed for the electrostatic baking and curing of the plastic coating layer on PVC-U composite tubes for heat exchangers, providing composite heat exchange tubes for the production of corrosion-resistant and fouling-resistant heat exchangers. The coated tube array is not limited to plain tubes but can also be finned tubes. The corrosion-resistant layer of the heat exchange tubes produced by this device has a uniform and controllable thickness.

[0029] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A rotary electrostatic plastic coating tube baking and curing device, comprising a housing, characterized in that... The housing is provided with a rotating wheel assembly, which includes a central rotating shaft (10) driven by a motor. The central rotating shaft is provided with a wheel (2) at both ends. Multiple plastic-coated pipe rows are provided between the two wheel (2). An electric heater (13) is provided at the bottom of the housing. A cross-flow fan (14) is provided above the electric heater (13). There are two cross-flow fans, which are spaced apart on both sides of the lower part of the rotating wheel assembly. Air duct baffles (19) are provided on both sides of the rotating wheel assembly above the cross-flow fans.

2. The rotary electrostatic plastic coating tube baking and curing device according to claim 1, characterized in that... A wind distribution plate (11) is installed between the two cross-flow fans.

3. The rotary electrostatic plastic coating tube baking and curing device according to claim 1, characterized in that... One end of the wheel (2) is fixed, and the other end can move on the central rotating shaft (10).

4. The rotary electrostatic plastic coating tube baking and curing device according to claim 1, characterized in that... The plastic-coated pipe array is secured to two discs (2) by horizontal fixing angle steel (3) and vertical fixing angle steel (4).

5. The rotary electrostatic plastic coating tube baking and curing device according to claim 1, characterized in that... The central rotating shaft is fixed in the bearing and connected to the drive motor (16) through the coupling (17).

6. The rotary electrostatic plastic coating tube baking and curing device according to claim 1, characterized in that... The housing includes a lower housing (15) and an upper housing cover (1), the upper housing cover being removable.

7. A rotary electrostatic plastic coating tube baking and curing device according to claim 6, characterized in that... An oxygen meter (7) and an exhaust valve (8) are provided on one side of the top of the upper box cover (1).

8. A rotary electrostatic plastic coating tube baking and curing device according to claim 7, characterized in that... A temperature sensor (20) is also installed on the upper cover.

9. A rotary electrostatic plastic coating tube baking and curing device according to claim 8, characterized in that... A nitrogen valve (12) is installed on one side of the lower housing.

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