Processing treatment method and system for coating on inner wall of tube bundle of straight tube heat exchanger

Abstract

The invention discloses a straight pipe heat exchanger tube bundle inner wall coating processing treatment method and system. The system comprises a tube bundle clamping and conveying module, an annular precise spraying module, a coating supplying and recycling module, a rapid curing module and a central control system. The method comprises the steps that after surface pretreatment is conducted on a tube bundle to be coated, the tube bundle is clamped to a rotary conveying device, the tube bundle is driven to rotate around the axis of the tube bundle at a constant speed and move in the axial direction, meanwhile, 360-degree surrounding spraying is conducted on the tube bundle through an annular spray head assembly capable of being opened and closed, and a uniform spiral coating is formed; in the spraying process, a negative pressure recovery system is started to collect the sprayed paint; and after spraying is completed, online curing is conducted in the rapid curing module. Full-automatic operation of tube bundle coating is achieved, and the tube bundle coating device has the advantages of being uniform in coating, free of dead corners, accurate and controllable in thickness, high in construction efficiency, high in coating utilization rate, good in environmental protection performance and the like and is particularly suitable for corrosion prevention, scaling prevention, abrasion resistance and other functional coating of the inner wall of a straight tube bundle of equipment such as a heat exchanger and a condenser.

Description

Technical Field

[0001] This invention relates to the field of surface treatment, and in particular to a method and system for processing a coating on the inner wall of a straight tube heat exchanger tube bundle. Background Technology

[0002] Heat exchangers are critical equipment in industrial production processes such as chemical, power, shipbuilding, and energy technology. Heat exchanger tube bundles are exposed to corrosive media or high-speed fluids under high temperature and pressure environments for extended periods, making them highly susceptible to corrosion, scaling, and wear. This leads to decreased heat exchange efficiency, increased energy consumption, and even safety accidents such as equipment perforation and leakage. Once a leak occurs, it causes plant shutdown and requires significant manpower and resources for repair and maintenance. Therefore, the anti-corrosion coating protection of heat exchanger tube bundles is particularly important. Surface coating of the tube bundles (such as epoxy anti-corrosion coatings, ceramic wear-resistant coatings, and anti-scaling coatings) is an effective means to extend their service life and ensure safe operation.

[0003] Currently, common methods for coating the inner walls of tube bundles mainly include manual brushing, dip coating, or spraying. Manual brushing or roller coating is inefficient, produces uneven coating thickness, relies heavily on worker experience for quality, makes it difficult to ensure coating integrity between dense tube bundles, and is labor-intensive, posing safety and health hazards. Dip coating, while covering all surfaces, is difficult to control in terms of coating thickness, easily leads to liquid accumulation inside the tube bundle, and results in significant paint waste and difficult subsequent cleaning. Using ordinary spray guns to coat tube bundles is problematic because the guns cannot reach the inner walls. Furthermore, during spraying, dense tube bundles are prone to a "shadow effect," making it difficult to cover the tube walls facing away from the spray gun, resulting in low paint utilization, severe overspray, and significant environmental pollution. This is particularly true for the inner walls of heat exchanger tube bundles, where the tube pores are small and the spraying space is limited, making traditional spraying methods difficult to implement.

[0004] Therefore, existing technologies suffer from problems such as poor coating uniformity, low construction efficiency, serious paint waste, and environmental pollution. Furthermore, it is difficult to achieve uniform coating inside the heat exchanger tube bundle. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a coating system and method that features uniform coating, controllable thickness, high construction efficiency, high degree of automation, high coating utilization, and is suitable for dense straight pipe bundles. It can be used for anti-corrosion, anti-scaling, antibacterial, or special functional coatings.

[0006] An automated coating system for straight tube bundles of heat exchangers includes: Tube bundle rotation and conveying module: used to clamp and drive the tube bundle to rotate at a constant speed along its axis, and to drive the tube bundle to move horizontally along its axis.

[0007] The annular precision spraying module's core is an annular nozzle assembly with eight evenly distributed air atomizing nozzles 9 within its inner ring. This annular nozzle assembly can open and close radially to accommodate tube bundles of different diameters and can perform 360° surround spraying without blind spots while the tube bundle rotates. The spraying module is equipped with annular rollers for convenient axial linear movement along the inner wall of the tube bundle. A camera 10 is installed at the front end of the spraying module for surface inspection after spraying. During spraying the inner wall of the straight tube bundle in the heat exchanger, the spraying module is slowly and evenly pulled out from the inside out. Alternatively, if the tube bundle is tilted between 5-10° during spraying, the annular nozzle assembly can automatically move using gravity and its built-in power and rollers until the inner wall of that tube bundle is fully sprayed.

[0008] The dual-station paint supply and recovery module includes a precision metering, mixing, and conveying system for A / B two-component paint, as well as a negative pressure paint recovery system located below the spraying station. The recovery system effectively collects and filters oversprayed paint particles, some of which can be recycled.

[0009] A rapid curing module can be installed: located downstream of the spraying station, it can use infrared radiation heating, UV curing or hot air circulation device to quickly surface dry or cure the coated tube bundle.

[0010] Central control system: Integrates a PLC or industrial computer to coordinate and control all process parameters such as the rotation / movement speed of the tube bundle, spraying start / stop, paint flow rate, atomization pressure, curing temperature, and time. It also collects and records appearance inspection data acquired by the spraying module camera 10.

[0011] The coating method based on the above system includes the following steps: S1: Pretreatment: Surface pretreatment of the straight tube bundle to be coated, including dust removal, degreasing, sandblasting or shot blasting, to make its surface clean and achieve the specified roughness.

[0012] S2: System Preparation and Parameter Setting: Clamp the pretreated tube bundle onto the rotary drive device. Based on the tube bundle diameter, coating type, and target thickness, set process parameters such as tube bundle rotation speed, axial movement speed, coating flow rate, atomization pressure, curing temperature, and time in the central control system.

[0013] S3: Automated closed-loop spraying: a) Install the annular nozzle assembly and insert it into the tube bundle to be sprayed.

[0014] b) Start the system, and the tube bundle begins to rotate at a constant speed.

[0015] c) The spraying module starts and begins to spray atomized paint.

[0016] d) The tube bundle moves at a constant speed along the axial direction while rotating. The annular nozzle is slowly pulled out, and the continuous spraying combined with the spiral forward movement of the tube bundle ensures that the entire outer surface of the tube bundle receives a spirally superimposed coating of uniform thickness.

[0017] e) The negative pressure recovery system is started simultaneously to collect the oversprayed paint.

[0018] S4: Online rapid curing: The coated tube section enters the rapid curing module while moving, and is rapidly cured under set conditions to form a stable coating.

[0019] S5: Cooling and Unloading: After the cured tube bundle is cooled, it stops rotating and moving, and the coated tube bundle is unloaded.

[0020] Advantages of this invention: Uniform coating without dead angles: By combining "tube bundle rotation + ring-shaped spraying + axial movement", a uniform coating covering 360° of the outer surface of the tube bundle is achieved, completely eliminating the "shadow effect".

[0021] Precise and controllable thickness: By precisely controlling the tube bundle rotation speed, moving speed and coating output, the coating thickness can be digitally and precisely controlled with good repeatability.

[0022] High efficiency and automation: The entire process is automated and continuous, significantly improving coating efficiency and reducing labor costs and intensity. A 360° camera is installed at the front of the spraying module to record and monitor the spraying effect, reducing defects and recording the spraying process for easy archiving and retrieval. During spraying, the nozzle bundle tilts between 5-10°, and the annular nozzle assembly moves automatically using gravity, internal power, and rollers.

[0023] High material utilization and environmental protection: The ring-shaped spraying has good focusing properties, and with the negative pressure recovery system, it significantly reduces paint overspray and waste, with a paint utilization rate of over 85%, thus improving the working environment.

[0024] High adaptability: By adjusting the size and process parameters of the annular nozzle's traveling wheels, it can be applied to tube bundles of different diameters, demonstrating good versatility.

[0025] Stable and reliable quality: The process flow is managed by a central control system, eliminating human interference and ensuring the stability and consistency of coating quality. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the automated coating system of the present invention; Figure 2 This is a side view cross-sectional diagram of the annular precision spraying module; Figure 3This is a schematic diagram of the movement trajectory of the tube bundle during the spraying process, covered by a spiral line. In the diagram, the components are: 1. Central control system; 2. Paint supply module; 3. Compressed air supply module; 4. Circular spraying module; 5. Tube bundle rotation and conveying module; 6. Negative pressure recovery system; 7. Simple and rapid curing module; 8. Wheels; 9. Air atomizing nozzle; 10. Camera; 11. Data transmission line and paint supply system. Detailed Implementation

[0027] The present invention will be further explained below with reference to specific implementation schemes, but it is not limited to the present invention. The structures, proportions, sizes, etc. shown in the accompanying drawings are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0028] A method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle includes the following steps: S1: Surface pretreatment: Cleaning and surface roughening of the straight tube bundles to be coated; S2: Clamping and parameter setting: Clamp the pretreated tube bundle into the tube bundle rotation and conveying module 5, and set the process parameters including rotation speed, axial movement speed and coating flow rate in the central control system 1. S3: Automated closed-loop spraying: Start the tube bundle rotation and conveying module 5 to drive the tube bundle to rotate at a constant speed around its axis and move horizontally along its axis; start the annular spraying module 4 to spray the moving tube bundle 360° around it to form a spiral coating; simultaneously start the negative pressure recovery system 6 to collect the oversprayed paint. S4: Online rapid curing: Allows the sprayed tube bundle section to enter the rapid curing module 7 for curing treatment; S5: Cooling and unloading: Obtain the painted tube bundle.

[0029] In step S3, the annular spraying module 4 includes an annular support that can be opened and closed radially, on which multiple atomizing nozzles 9 are evenly arranged circumferentially; the annular spraying module 4 is equipped with a data transmission line and a paint supply system 11 inside, a camera 10 at the front end, and wheels 8 on the outside.

[0030] Eight air atomizing nozzles 9 are evenly arranged on the annular support.

[0031] The curing process in step S4 is infrared radiation heating, UV light curing, or hot air circulation curing.

[0032] During the spraying process in step S3, the axis of the tube bundle is tilted at an angle of 5° to 10° with the horizontal direction.

[0033] In step S3, surface inspection data is collected by a camera 10 located at the front end of the annular spraying module 4. The sprayed surface is monitored in real time.

[0034] A coating processing system for the inner wall of a straight tube heat exchanger tube bundle includes: a central control system 1 for setting and controlling all process parameters; a coating supply module 2 for supplying coating; a compressed air supply module 3 for providing atomizing air source; and an annular spraying module 4 connected to the coating supply module 2 and the compressed air supply module 3 for performing 360° circumferential spraying on the tube bundle. The tube bundle rotation and conveying module 5 is used to clamp the tube bundle and drive it to rotate and move axially simultaneously; the negative pressure recovery system 6 is located below the spraying station and is used to recover oversprayed paint; the rapid curing module 7 is located downstream of the spraying station and is used to cure the coating; wherein, the central control system 1 is electrically connected to the paint supply module 2, the compressed air supply module 3, the annular spraying module 4, the tube bundle rotation and conveying module 5, the negative pressure recovery system 6 and the rapid curing module 7 to coordinate and control the entire coating process.

[0035] The annular spraying module 4 includes a radially openable annular support and multiple atomizing nozzles evenly arranged thereon.

[0036] The paint supply module 2 is a precision metering and mixing conveying system for A / B dual-component paint.

[0037] The system also includes a tilting mechanism for rotating the tube bundle and tilting the delivery module 5 or the clamped tube bundle by 5° to 10° during the spraying process.

[0038] Taking a set of carbon steel straight tube bundles of a shell-and-tube heat exchanger as an example, the implementation process of the present invention will be specifically explained.

[0039] Object to be painted: Tube material: carbon steel Pipe diameter: Φ25 mm Pipe length: 6 m Coating type: Epoxy anti-corrosion coating Preprocessing steps: The tube bundle is sandblasted to achieve the following surface condition: Cleanliness level: Sa 2.5 Surface roughness: Ra 40–70 μm Process parameter settings Set the following parameters in the central control system 1: Tube bundle rotation speed: 20 rpm Axial moving speed of the tube bundle: 0.3 m / min Paint flow rate: 200 ml / min Curing method: Infrared radiation heating Curing temperature: 80-120℃ Curing time: 3 min Painting execution: The pre-treated tube bundle is clamped into the rotation and conveying module 5, and the system is started. It is clamped by chucks at both ends, and the chucks are driven by servo motors to achieve uniform rotation. At the same time, the entire clamping mechanism is mounted on a linear guide rail and is driven by another servo motor to move horizontally along the tube bundle axis.

[0040] The annular spraying module 4 is slowly pulled out from one end of the tube bundle, while the tube bundle rotates at a constant speed and moves axially to achieve spiral full-coverage spraying. The paint supply module 2 and compressed air supply module 3 are activated, and the spraying parameters are controlled by the central control platform to begin spraying. During the spraying process, the negative pressure recovery system 6 is activated simultaneously to collect the oversprayed paint.

[0041] Curing and cooling: The coated tube bundle enters the simple rapid curing module 7 for infrared curing at a set temperature. After curing, it is allowed to cool naturally before being removed. All process parameters, including speed, temperature, and flow rate, are integrated and controlled by a PLC in the central control cabinet 7.

[0042] Paint finish: The coating thickness is uniform, controlled between 150–170 μm. Adhesion rating: Level 1, cross-cut adhesion The surface is free of defects such as missed coating, sagging, and bubbles. The total coating time for a single tube bundle is approximately 25 minutes, including curing time, which is more than 300% more efficient than traditional manual coating.

[0043] Matters not covered in this invention are common knowledge.

[0044] 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 method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle, characterized in that, Includes the following steps: S1: Surface pretreatment: Cleaning and surface roughening of the straight tube bundles to be coated; S2: Clamping and parameter setting: Clamp the pretreated tube bundle into the tube bundle rotation and conveying module (5), and set the process parameters including rotation speed, axial movement speed and coating flow rate in the central control system (1); S3: Automated closed-loop spraying: Start the tube bundle rotation and conveying module (5) to drive the tube bundle to rotate at a constant speed around its axis and move horizontally along its axis; start the ring spraying module (4) to spray the moving tube bundle around 360° to form a spiral coating; start the negative pressure recovery system (6) at the same time to collect the oversprayed material. S4: Online rapid curing: The tube bundle segment that has been sprayed is put into the rapid curing module (7) for curing treatment; S5: Cooling and unloading: Obtain the painted tube bundle.

2. The method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle according to claim 1, characterized in that, In step S3, the annular spraying module (4) includes an annular support that can be opened and closed radially, on which multiple atomizing nozzles (9) are evenly arranged circumferentially; the annular spraying module (4) is equipped with a data transmission line and a paint supply system (11) inside, a camera (10) at the front end, and wheels (8) on the outside.

3. The method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle according to claim 2, characterized in that, Eight air atomizing nozzles (9) are evenly arranged on the annular support.

4. The method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle according to claim 1, characterized in that, The curing process in step S4 is infrared radiation heating, UV light curing, or hot air circulation curing.

5. The method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle according to claim 1, characterized in that, During the spraying process in step S3, the axis of the tube bundle is tilted at an angle of 5° to 10° with the horizontal direction.

6. The method for processing the coating on the inner wall of a straight tube heat exchanger tube bundle according to claim 1, characterized in that, In step S3, appearance inspection data is collected by a camera (10) located at the front end of the annular spraying module (4). Real-time monitoring of the sprayed surface.

7. A coating processing system for the inner wall of a straight tube heat exchanger tube bundle for implementing the method according to any one of claims 1-6, characterized in that, include: The central control system (1) is used to set and control all process parameters; The coating supply module (2) is used to supply coatings; The compressed air supply module (3) is used to provide atomizing air source; the annular spraying module (4) is connected to the paint supply module (2) and the compressed air supply module (3) and is used to perform 360° circumferential spraying on the tube bundle; the tube bundle rotation and conveying module (5) is used to clamp the tube bundle and drive it to rotate and move axially at the same time; the negative pressure recovery system (6) is set below the spraying station and is used to recover the oversprayed paint; the rapid curing module (7) is set downstream of the spraying station and is used to cure the coating. The central control system (1) is electrically connected to the paint supply module (2), compressed air supply module (3), ring spraying module (4), tube bundle rotation and conveying module (5), negative pressure recovery system (6) and rapid curing module (7) to coordinate and control the entire coating process.

8. The coating processing system for the inner wall of a straight tube heat exchanger tube bundle according to claim 7, characterized in that, The annular spraying module (4) includes an annular support that can be opened and closed radially and a plurality of atomizing nozzles evenly arranged thereon.

9. The coating processing system for the inner wall of a straight tube heat exchanger tube bundle according to claim 7, characterized in that, The coating supply module (2) is a precision metering and mixing conveying system for A / B dual-component coatings.

10. The coating processing system for the inner wall of a straight tube heat exchanger tube bundle according to claim 7, characterized in that, The system also includes a tilting mechanism for tilting the tube bundle rotation and transport module (5) or the clamped tube bundle by 5° to 10° during the spraying process.

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