JP7451311B2 - How to form a coating film - Google Patents

Description

Embodiments of the present invention relate to a method of forming a coating film.

There are several types of energy supply methods, and the current main method is the combined cycle power generation method. A combined cycle power generation plant uses combustion gas to drive a gas turbine and sends exhaust gas to a heat recovery steam generator (HRSG). The main part of an exhaust heat recovery boiler is composed of finned piping called heat transfer tubes. Exhaust gas is passed through the outer surface of the heat transfer tubes, and residual heat from the exhaust gas is transferred to hot water or steam flowing inside the heat transfer tubes. do. In combined cycle power generation plants, residual heat from exhaust gas is used to generate steam, and the resulting steam is guided to a steam turbine to drive a generator. This has resulted in a power generation plant with higher efficiency than various conventional power generation methods.

On the other hand, the exhaust heat recovery boiler, which is an essential device for the above-mentioned combined cycle power generation method, is also a device that is likely to form a corrosive environment inside the device. Exhaust heat recovery boilers reach a high temperature when operating and reach a temperature similar to the outside air temperature when stopped, which tends to create a high-humidity environment inside the equipment, which increases the risk especially when stopped. The high humidity inside the equipment is also affected by the humidity in the external environment due to rain, etc., and internal equipment (heat exchanger tubes, stubs, etc. in the heat exchange section) has a risk of corrosion.

An exhaust heat recovery boiler is a large piece of equipment with a scale of several stories, and the number of heat exchanger tubes is in the hundreds. When a rust layer is formed on a heat exchanger tube due to corrosion, heat transfer, which is the main required performance of the heat exchanger tube, is inhibited by the rust layer, resulting in a serious problem of reduced heat transfer efficiency. In addition, if equipment is damaged due to corrosion, parts may become thinner due to thinning or local corrosion, reducing the durability of the equipment and, in severe cases, causing leakage of hot water or steam. .

Furthermore, if corrosion occurs and progresses on the outer surface of the heat exchanger tubes and a rough rust layer is formed, peeling occurs due to the airflow of exhaust gas sent from the gas turbine to the exhaust heat recovery boiler when the plant is started up. In some cases, the peeled rust is discharged from the exhaust heat recovery boiler to the outside environment through a chimney or the like, causing problems such as being scattered around.

Therefore, in order to prevent corrosion from occurring inside the exhaust heat recovery boiler, it is being considered to apply coating or thermal spraying to the members before they are installed in the exhaust heat recovery boiler as a rust preventive measure. On the other hand, the configuration of an exhaust heat recovery boiler is optimized to obtain high heat recovery efficiency, and in many cases, heat exchanger tubes are arranged closely. Therefore, it has been considered virtually impossible to attempt rust prevention measures such as painting or thermal spraying on piping and parts such as heat transfer tubes and stubs after the plant has been installed.

In particular, with anti-corrosion coatings and thermal spraying, it is necessary to properly cover the surface to be rust-prevented, as insufficient formation of a coating film or thermal spraying layer has the risk of inhibiting function expression and not achieving effective effects. It is. Therefore, for rust that has developed and progressed after equipment installation, many plants perform maintenance to remove the rust (for example, air blow cleaning) before starting the exhaust heat recovery boiler. On the other hand, inside the exhaust heat recovery boiler, heat exchanger tubes and the like are crowded and intricate, making it difficult to take measures against corrosion and rust scattering.

Against this background, Patent Document 1 proposes a method of installing air conditioning equipment in the exhaust heat recovery boiler and air conditioning the entire interior area to prevent rust from occurring. Although such a method is effective in principle and its effectiveness has been confirmed, there are problems when installing it on existing equipment, designs with little footprint margin, and aging equipment. Moreover, Patent Document 2 proposes a method of cleaning rust generated on heat transfer tubes in order to prevent the generated rust from being released to the outside of the exhaust heat recovery boiler. However, with this method, it may be difficult to effectively suppress the occurrence of rust, and there are still issues with this method.

Japanese Patent Application Publication No. 2018-119694 Japanese Patent Application Publication No. 2002-62091

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for forming a coating film that can suppress corrosion of equipment for a power generation plant such as an existing exhaust heat recovery boiler.

The coating film forming method of the embodiment is applied to existing power generation plant equipment in which a large number of heat exchanger tubes are densely arranged and a narrow part is formed between each heat exchanger tube and an adjacent heat exchanger tube. Alternatively, a method of forming a coating film of a rust-preventing or heat-transfer coating mixture of a solid substance composed of carbon and a liquid coating material, which can be inserted into the narrow part in the depth direction. , and a tubular pole part capable of transporting the anti-corrosion or heat transfer paint and changing the construction angle of the nozzle head , and a tubular pole part provided at the tip of the pole part and inserted in the depth direction into the narrow part. If possible, and by changing the spray angle from 30° to 120° and using a nozzle part that sprays the anti-corrosion or heat transfer paint , by changing the construction angle of the nozzle head and changing the nozzle spray angle, it is possible to Forming coatings on power generation plant equipment to provide anti-corrosion effects, or performing maintenance to maintain and improve heat transfer characteristics .

FIG. 3 is a diagram for explaining a method of forming a coating film according to an embodiment. FIG. 3 is a diagram for explaining a method of forming a coating film according to an embodiment. FIG. 3 is a diagram for explaining a method of forming a coating film according to an embodiment. A diagram schematically showing a state when the spray angle is about 30°. The figure which shows typically the state when a spray angle is about 60 degrees. The figure which shows typically the state when a spray angle is about 100 degrees. The figure which shows typically the structure of the modification of a nozzle part and a pole part. The figure which shows typically the structure of the modification of a nozzle part and a pole part. The figure which shows typically the structure of the modification of a nozzle part and a pole part. (a) and (b) are diagrams for explaining the enforcement state. FIG. 3 is a diagram for explaining the relationship between the distance between the nozzle part and the construction location. Diagram for explaining the actual enforcement process. FIG. 3 is a diagram for explaining a case where a coating film is formed on the umbrella portion. (a), (b), and (c) are diagrams for explaining the enforcement state. (a), (b), and (c) are diagrams for explaining the enforcement state. The figure which shows the example which has the mechanism which can change the angle of a nozzle part in a pole part. The figure which shows the example which has the mechanism which can change the angle of a nozzle part in a pole part.

Hereinafter, a method for forming a coating film according to an embodiment will be described with reference to the drawings.

First, an example of the arrangement of heat exchanger tubes in the exhaust heat recovery boiler will be described with reference to FIG. In this example of an exhaust heat recovery boiler, the heat exchanger tubes are arranged horizontally, and the one shown on the left side in Figure 1 is the frontmost (first row) heat exchanger tube. 1, the second row of heat exchanger tubes and the third row of heat exchanger tubes are shown toward the right side in FIG. The interval between the heat exchanger tubes in each row (the interval between the centers of the heat exchanger tubes) is 84 mm, and the interval formed between the heat exchanger tubes in each row is about 20 mm (20.5 mm). Further, the interval between the heat exchanger tubes between each row (the interval between the centers of the heat exchanger tubes) is 100 mm. The heat exchanger tubes in the first, second, and third rows are arranged in a staggered manner. As shown on the left side of Figure 1, each heat transfer tube has a piping section (main tube) through which fluid flows, and a tube that protrudes around this piping section to increase heat transfer efficiency. It is equipped with a large number of fins.

When forming a coating film on the heat exchanger tubes in the waste heat recovery boiler with the above configuration, since there is a gap of about 20 mm between the heat exchanger tubes in each row, the nozzle part 11 and the pole part 10 ( For example, if a nozzle diameter of 16 mm and a pole diameter of 12 mm are used, it is possible to approach the heat exchanger tubes in the first and second rows. However, when inserting a nozzle, pole, etc. into the gap between the heat transfer tubes when painting or thermal spraying the heat transfer tubes, the minimum gap is determined by the contact point between the fin tips of the heat transfer tube (hereinafter referred to as the minimum gap). ). This minimum gap is about 10 mm in the case shown in FIG. 1, which is about half of the gap (about 20 mm) formed between adjacent heat exchanger tubes. Therefore, even though the nozzle 11 and the pole 10 can be inserted into the gap (approximately 20 mm) formed by adjacent heat exchanger tubes, they cannot actually be inserted in the depth direction. As described above, it is difficult to form a coating film in the depth direction of the heat exchanger tube arrangement. Therefore, in reality, it has been difficult to apply coating, thermal spraying, etc. to the existing exhaust heat recovery boiler, which has already been constructed, in order to prevent rust or improve heat transfer.

In this embodiment, a tubular pole part 10 that can be inserted into a narrow part in the depth direction and can transport anti-rust or heat transfer paint, and a tubular pole part 10 provided at the tip of the pole part 10, The nozzle part 11 can be inserted in the depth direction at an angle of 30° to 120° and sprays anti-rust or heat transfer paint. form. In this embodiment, as described above, the minimum gap (Y) of the narrow portion formed by one heat exchanger tube and an adjacent heat exchanger tube is 10 mm. On the other hand, the diameter (X) of the pole portion 10 is 8 mm, and the diameter (X) of the nozzle portion 11 is 10 mm. That is, there is a relationship of X≦Y. According to this embodiment, as shown in FIG. 1, the nozzle can be inserted between the heat exchanger tubes vertically in the depth direction. Moreover, as shown in FIG. 2, in this embodiment, the nozzle part 11 and the pole part 10 can be inserted and removed from the heat exchanger tubes arranged in a staggered manner instead of perpendicularly to the depth direction of the heat exchanger tubes. It is also possible to form a coating film on the third row of heat exchanger tubes, etc. A configuration having this relationship enables film formation by painting or thermal spraying on the heat exchanger tubes arranged in the depth direction, compared to the heat exchanger tubes arranged densely.

FIG. 3 shows a case where the diameter of the pole 10 is 6 mm and the diameter of the nozzle 11 is 8 mm. In this case, the nozzle part 11 and the pole part 10 can be moved in and out of the narrow part between the heat exchanger tubes in the depth direction, in and out of the pole in the longitudinal direction, changing the insertion angle, or in the direction of the rotation axis of the pole. This is an example of a shape, mechanism, or dimension that allows for rotation. In the above-mentioned relationship of X≦Y, if X is sufficiently small compared to Y, the nozzle part 10 and the pole part 11 can easily move from the second row to several rows in the depth direction in the narrow part between the heat exchanger tubes. It becomes possible to put in and take out. The pole part 10 has a diameter that allows it to enter and exit an extremely narrow gap formed by, for example, a staggered arrangement of heat exchanger tubes. The degree of freedom of movement of the pole part 10 during insertion of the heat exchanger tube 10 is increased, and it becomes possible to approach several heat exchanger tubes arranged in the same row. This allows the pole to be moved horizontally or diagonally at a single insertion point, reducing the risk of mispainting. In addition, it can be expected that the coating efficiency will be improved by one-time insertion.

In this embodiment, a rust-preventing paint is used, which is a mixture of a solid substance and a liquid paint. The solid substance is a substance composed of metal and carbon, and this solid substance has a form of one or more of particles, fibers, flakes, and capsules. When the solid substance is metal, for example, the solid substance contains an amount such that the metal weight ratio after film formation is 60% or more. Therefore, if the diameter of the pole part 10 and the diameter of the nozzle part 11 are made thinner as described above, there is a high possibility that solid substances will clog and it will be impossible to spray the anticorrosive paint.

In this embodiment, when using an airless atomizer, appropriate application is possible by optimizing the secondary pressure. In the operation of a coating machine, the temporary pressure and secondary pressure are one of the parameters that determine the discharge pressure, and in this embodiment, the secondary pressure is adjusted to 6.5 MPa or more and 13.5 MPa or less to perform painting. conduct. In the setting range of the secondary pressure, it is more preferably set to 7.5 MPa or more and 12.5 MPa or less. The discharge pressure shall be set appropriately depending on the manner of discharge. Note that if the discharge pressure is too high, the adhesion of the paint to the object to be coated will decrease.

For example, as a coating machine, for example, ALS-433C manufactured by Anest Iwata Co., Ltd. can be used. In addition, as an example of the pressure magnification at this time, it is preferable to set it as 30:1 etc.

In this embodiment, when using an air coating machine, by setting the diameter of the coating nozzle to 1 mm or more and 3.5 mm or less, clogging, solidification, etc. can be suppressed, and necessary and sufficient paint can be discharged. You can also secure the quantity. More preferably, the diameter of the coating nozzle is 2 mm or more and 2.5 mm or less.

For example, as a coating machine, a coating machine such as W-200-201G manufactured by Anest Iwata Co., Ltd. can be used. Further , an example of the diameter of the paint nozzle is 2.0 mm.

One of the means to realize the formation of a coating film having an appropriate coating thickness is to suppress overcoating (excessively thick film) and failure to coat (formation of uncoated areas, etc.). However, for example, plant structures and the like are large in size and complex in shape, and therefore require appropriate coating film formation and coating efficiency above a certain level. For example, in the case of exhaust heat recovery boilers, etc., the construction target is extremely large, and the construction area is large, with some having a total number of pipes of 10,000 or more. One of the major factors that influences the coating film formation range or application efficiency is the spray angle. If the spray angle is too narrow, the necessary coating areas may not be sufficiently covered, or the coating efficiency may be significantly reduced. On the other hand, if the spray angle is too wide, the spray will scatter to areas that are not intended for construction. Spattered paint not only adheres to unnecessary areas, but also burdens the installer and leads to excessive paint consumption.

For example, FIG. 4 is a schematic diagram when the spray angle is approximately 30°. When the spray angle is 30°, approximately one heat transfer tube is the main target for construction. Since the spray angle is narrow, it is necessary to insert and spray from four locations, but this reduces the possibility of excessive multi-layer coating. If the spray angle is smaller than 30°, there is a possibility that unpainted areas will appear.

For example, FIG. 5 is a schematic diagram when the spray angle is about 60°. Although it depends on the shape and arrangement of the construction target, when the spray angle is 60°, approximately two heat exchanger tubes are the main construction targets. The spray angle is wide, making it possible to perform the necessary work by inserting and spraying from two locations. The spray time is shortened compared to the case where the spray angle is narrow. In addition, since it is possible to form a coating film even when painting from a small number of insertion points, it is possible to reduce the possibility of excessive multi-layer coating, and it is also possible to spray by inserting from insertion points other than the insertion points shown in Figure 5. It is also possible to form multiple layers by spraying from two or more different insertion points, instead of repeating coating from insertion at one point.

For example, FIG. 6 is a schematic diagram when the spray angle is 100°. Although it depends on the shape and arrangement of the construction target, when the spray angle is 100°, approximately three heat exchanger tubes are the main construction targets. The spray angle is extremely wide, making it possible to perform the necessary work by inserting and spraying from two locations. The spray time is significantly reduced compared to the case where the spray angle is narrow. Furthermore, since it is possible to form a coating film even when coating from a small number of insertion points, the possibility of excessive multilayer coating can be reduced. Even if the insertion frequency is low, there is a high possibility of covering the target area, and by increasing the number of insertion points, it is also possible to form an ideal film with multiple layers of thin coatings. Therefore, it is suitable for cases where construction time is limited even though the number of objects to be constructed is enormous. On the other hand, when the same paint is sprayed for the same application time, the density of the sprayed paint tends to be low. By performing this work while moving the nozzle by inserting and removing it, it is possible to temporarily shorten the distance between the work area and the nozzle tip, and form a film more densely.

For the above reasons, the spray angle of the nozzle part 11 (indicated by the double-sided arrow in FIG. 1) is preferably in the range of 30° or more and 120°C or less, and preferably in the range of 60° or more and 100°C or less. More preferred. The distribution form of the scattered particles of the coating film is not limited by the structure of the nozzle part 11, and may include a straight nozzle, circular (with scattering within the circle: fan-shaped nozzle, full conical nozzle, wide angle fan-shaped nozzle, etc.), circular (with scattering within the circle). Any form may be used, such as an elliptical shape (e.g., an eccentric uniform fan-shaped nozzle), or a plurality of divisions (lily of the valley nozzle, hexagonal 10-head spout, etc.). When painting heat exchanger tubes, when the nozzle head moves through the gap between the heat exchanger tubes, most of the time the nozzle head moves through the smallest gap. On the other hand, if the spray angle is narrow, more paint will be applied in the direction of nozzle movement, leading to a decrease in the efficiency with which the paint adheres to the heat exchanger tubes forming the gap. On the other hand, if the injection is performed at, for example, 60°, the paint will easily adhere to the fin portions and the main tube portions of the heat exchanger tubes, and an improvement in the adhesion efficiency can be expected.

7 to 9 show that among the shapes of the nozzle part 11 and the pole part 10, the shape of one or more of the nozzle part 11, the pole part 10, or the connection point between the nozzle part 11 and the pole part 10 is structurally Alternatively, this is an example in which the material is variable. FIG. 7 shows an example in which the pole portion 10 can be flexibly deformed and can maintain the deformed state. FIG. 8 shows an example in which the pole portion 10 is straight when viewed from the top, but has an angle when viewed from the side. FIG. 9 shows an example in which the pole section 10 has a movable section. In both cases, there is no dimensional problem when the pole part 10 and nozzle part 11 are inserted into and taken out from a narrow part, but when the nozzle tip is located at a location wider than the minimum interval between heat transfer tubes, there is a degree of freedom in the injection angle from the nozzle. Take a configuration that produces According to this configuration, the nozzle part 11 and the pole part 10 can pass through the minimum gap Y, and the pole part 10 can be freely rotated in the wider gap part, moved up and down, moved the tip part, etc. in the coating direction. It is possible to obtain degrees. Improving the degree of freedom in the coating direction through one-time insertion not only improves coating efficiency, but also makes it possible to form a coating film that follows the shape even when the object to be coated has a complex shape. .

FIG. 10 shows a method of inserting the nozzle part 11 and the pole part 10 into the heat transfer tube from the outside to the inside, passing through the narrow part continuously or intermittently, and moving the tube as calculated from the narrow part dimensions and the nozzle or pole diameter. An example is shown in which construction is performed while maintaining or changing the insertion angle within the dimensional limit range. FIG. 10A shows an example where the construction target location is relatively close to the insertion location of the nozzle portion 11, and the likelihood of the tilt angle of the nozzle portion 11 is high. It can be seen that it is possible to perform construction over a relatively wide range of objects by changing the insertion angle with one insertion.

On the other hand, FIG. 10(b) is an example where the construction target location is located deep in the depth direction from the insertion location of the nozzle portion 11, and shows a case where the likelihood of the swinging angle of the nozzle portion 11 is low. Construction is carried out by inserting and removing the nozzle portion 11 and the pole 10 from the insertion point (outside of the workpiece) toward the workpiece location (inner side of the workpiece). In addition, although the tip of the nozzle part 11 is fanned using the pole part 10, the range in which fanning is possible is narrowed due to the construction object located on the outer surface side. By constructing the heat exchanger tube in the position at which it was first inserted, and changing the angle of the pole portion 10, it becomes possible to construct the adjacent heat exchanger tube as well. By using the combination of inserting and removing the nozzle part 11 and the pole part 10 and tilting, it becomes possible to target a wider range of construction in the depth direction than the range that can be constructed only by inserting and removing the nozzle part 11 and the pole part 10.

FIG. 11 shows the relationship of distance to the construction target. If Li is the shortest distance between the object to be constructed and the tip of the nozzle during construction, then Lo (distance to a point on the outer periphery of the spray range during paint film spraying) is the shape of the object to be constructed. The relationship Li<Lo holds unless the shape is unique. Regarding the relationship between Li and Lo, Lo tends to increase as the spray angle increases. On the other hand, in order to form an appropriate coating film, it is necessary to perform the application at an appropriate application distance, and it is preferable to perform application so that Lo is 5 mm or more and 300 mm or less. As a result, the distance from the object to be constructed is long, and unevenness in the coating film due to lack of sprayed paint or the like is suppressed. In addition, by avoiding contact between the workpiece and the nozzle, it is possible to prevent formation of an inappropriate paint film due to partial removal of the paint film after construction.

FIG. 12 is a diagram for explaining the actual enforcement process. For example, regarding the construction direction for the object to be constructed, in many cases it is possible to paint the surface by applying it from one direction. On the other hand, when the object to be constructed is large or immovable and has a surface to be constructed of 180 degrees or more, two or more construction directions are required. A coating film is applied to achieve the expected functionality of the coating film, and the required coverage, coating spots, and expected values and tolerance values for uncoated areas vary depending on the functionality. It is common that each requires film formation above a certain value, and although the values themselves differ depending on the various cases, the required film thickness, film properties, and coverage rate are determined by the action and effective range of the coating film to be applied. It has a mechanism that satisfies the following.

When heat transfer tubes are coated in an exhaust heat recovery boiler, it is often done to prevent rust or improve heat transfer efficiency. The process for coating the entire circumferential direction of the heat exchanger tube with anti-rust coating or heat transfer efficiency improving coating is divided into processes shown in FIGS. 12(1) to 12(4). First, a coating film is formed at a predetermined location by advancing and retracting the nozzle (1). Next, the heat exchanger tubes are approached in the same direction, but the same construction is carried out from a different angle from the gap between the heat exchanger tubes than in (1) (2). By these two processes, it is possible to form a coating film on one side of the heat exchanger tube. In an exhaust heat recovery boiler, several to more than ten rows of piping are arranged, and the piping is divided into blocks. Next, for one block of the heat exchanger tube group, the same construction is performed diagonally from the opposite side to the previous construction (3), (4). This makes it possible to form a coating film over the entire circumferential direction of the heat exchanger tube.

Further, as shown in FIG. 13, the construction is carried out by passing a nozzle through the gap between the large structures on the front and back sides of the umbrella section, respectively. By changing the nozzle head construction angle and the nozzle wide angle, it is possible to form a film from two construction angles. It becomes possible to carry out construction work in which a coating film can be formed on the required surface of the construction object without installing excessive scaffolding or intruding into narrow spaces.

FIG. 14 is a diagram for explaining how the heat exchanger tube is applied to the main tube and the fin portion. (a) shows a diagram when the pole section 10 is operated in the vertical direction in a narrow part, following the gap between the heat exchanger tubes. In this film formation, when there is a certain distance or more from the heat transfer tube, the film formation ratio on the main tube side of the heat transfer tube main tube and fin portion tends to be high (b), and the nozzle and the main tube are close to each other. In this case, the ratio of covering the main pipe and fin portions may increase. By optimizing this distance, it becomes possible to form an appropriate coating film on both the main tube and the fin portion (c). Furthermore, in the case of a nozzle with multiple blowholes, a single insertion allows for construction with a high degree of freedom regarding the distance, blowing angle, and blowing direction.

FIG. 15 shows an example in which one part of the pole part 10 is fixed manually or with a jig or the like, and the tip is manipulated to construct the narrow part between the heat exchanger tubes. In this type of film formation, when there is a certain distance or more from the heat exchanger tube, the film formation ratio on the fin part of the heat exchanger tube's main tube and fin part tends to be higher (a) and (b). As a result, a coating film is formed on the upper and lower surfaces of the fin portion (b) and (c). When the nozzle and the main pipe are close to each other, both the main pipe and the fin portion are coated. Therefore, by carrying out the construction using a process that combines the process shown in FIG. 14 and the process shown in FIG. 15, it is possible to control the properties of the coating film on the main pipe and the fin portion, and form an appropriate coating film.

FIG. 16 shows an example in which a mechanism for changing the angle of the nozzle part 11 is provided near the tip of the pole part 10. This may be a specification in which the nozzle itself includes a mechanism for varying the spray angle. The mechanically variable nozzle may also be a nozzle with a high degree of freedom, such as a juggling nozzle. Since the spray angle is variable, it is possible to change the spray on the main tube and fin portion each time the angle is changed. At this time, by manipulating the pole in the vertical direction following the gaps between the heat exchanger tubes, it becomes possible to apply the coating film to the main tube and fin surfaces of the heat exchanger tubes with higher efficiency.

FIG. 17 shows an example in which a mechanism that can change the angle of the nozzle part 11 is provided near the tip of the pole part 10, and the construction angle can be changed perpendicularly to the longitudinal direction of the heat exchanger tube. There is. According to this example, it is possible to reduce the effect of the fin portion, which is disposed approximately perpendicularly to the main tube, on the paint as an inhibitory factor. This makes it possible to form a relatively uniform coating over a wide range of the main pipe portion.

In each of the above-mentioned methods for forming a coating film, it is preferable to spray a gas such as air or an inert gas at least one of before, during (before drying), and after the application of the paint. For example, dust and rough rust layers are removed by spraying inert gas before construction. During construction, spraying gas reduces uneven adhesion and thickness of the paint film and coating fluid, making the paint film more uniform and reducing uncoated areas. After application, it has the effect of speeding up the drying of uncured components and the drying of the coating film. It also includes the spraying of gas with controlled gas conditions, including the spraying of heated gas and water vapor. This makes it possible to accelerate the curing of the coating film and shorten the drying time.

In each of the above-mentioned coating film formation methods, the formed coating film may not only be rust-proof, but also coated, heat transfer (heat transfer), heat-insulating, water-repellent or water-permeable surface modification, charging or electrostatic, surface modification, etc. It can have any one or more of the following functions: infiltrating deposits, peeling off surface deposits, and fixing surface deposits.

As an example of coating, there is protection of the base material by an organic resin coating, which has the role of protecting the base material part. In addition, in the case of protection against physical damage, etc., there are cases where it is not essential to cover the entire object to be painted. When the purpose is to block the environment, complete coverage is important.

In the case of rust prevention, for example, in the case of a paint having sacrificial anodic action, it is desirable to use a form that covers the entire object to be painted. However, sacrificial anode action provides sufficient protection for the base material in the short term as long as the required amount of coating film is formed within the range covered by electric lines of force and the range covered by cathodic protection. Depending on the season, the entire covering may not be necessary.

Regarding heat transfer, this is an example of promoting heat transfer by applying a material on the surface that has higher heat transfer than the base material part or the base material attachment part. Regarding the coverage area, if the coating film has higher heat conductivity than the base material or if high heat conductivity at the interface can be ensured, full-surface coating is also desirable. On the other hand, if an improvement is seen even in a part where heat conductivity is degraded or in a part of the part, it may be applied to only a part of the part. In insulation, it can be seen as roughly the opposite effect of heat transfer.

As an example of water repellency, there is an example of suppressing the formation of a water film in a place where formation of a water film is disliked. Effects such as preventing the dissolution of flying components and suppressing reactions through water are obtained. Regarding hydrophilization, it generally has the opposite effect and has the effect of hindering concentration and crystallization.

Regarding charging or static electricity, electrical properties may be imparted and, for example, effects such as improving the effect of subsequent electrodeposition coating may be exhibited. Infiltration into surface deposits takes the form of, for example, infiltrating a metal-containing component into a rough rust layer that acts as a heat insulating layer to form a coating film. If the formed layer is easily removable, surface deposits can be removed together with the layer by peeling it off. On the contrary, a form in which the forming layer can be firmly fixed to the base material along with the deposits is a form in which the deposits on the surface are fixed and the deposits are prevented from falling off.

In a form where the coating film imparts heat transfer performance to the object to be coated or to the deposits attached to the surface of the object to be coated, a coating film containing a metal component is formed. If there is an oxide film or rough rust on the surface of the heat exchanger tube, or if there are deposits attached, the paint film containing metal components will infiltrate into the pores and cracks of the rust layer, come into contact with the base material, or damage the rust layer. It becomes a composite layer that embraces the When the heat transfer performance of a coating film or composite layer is high, it is possible to alleviate the decrease in heat transfer caused by rust and deposits and improve heat transfer performance.

A form in which the coating film has an effect of preventing rust, suppressing corrosion occurrence, or alleviating a corrosive environment will be explained. The rust-preventing function can be expressed in various ways, but for example, a rust-preventing paint containing a rust-preventing chemical may be used in a tubular material or capsule. According to this example, the anticorrosion chemical oozes out of the coating film, thereby promoting corrosion protection in areas where the base material is exposed and under the coating film. Most exhibit antirust performance by forming a film on the surface of the base material and controlling pH. In this case, while it is desirable to cover the object to be coated with a coating film, it is possible to obtain some effects even if a coating film of a certain amount or more is formed on a location where rust prevention is required.

There is a form in which the coating film can exhibit one or more of the following actions: environmental adjustment type, film forming type, reaction suppression type, deposition type, sacrificial anode type, or both. There are no strict limitations on the anticorrosion method, and the embodiment includes the case where a coating film having an anticorrosion effect is formed. Full coverage or partial coverage can be selected by taking into account the anti-corrosion effect and the disadvantages to the original function of the equipment.

A case will be described in which the coating film contains elements having a low potential, such as zinc, aluminum, and tin, relative to the metal portion of the object to be coated. For example, many of the heat transfer tubes in exhaust heat recovery boilers are made of carbon steel. By applying a coating containing an element having a lower potential than iron, which is the main constituent of carbon steel, it is possible to obtain the effect of developing a sacrificial anode effect.

Next, a case where the coating film contains at least one selected from silicates, phosphates, nitrites, chromates, and ammonium salts will be described. Each salt is a salt that exhibits a rust-preventing effect, and exerts its rust-preventing effect by acting from the coating film into the water film near the base material or on exposed areas. Although it is desirable that the coating area of the object to be coated be large, for example, in the case of a coating film containing volatile nitrite or the like, the antirust effect can be achieved even if the coating is not completely covered.

In the above description, the nozzle portion and the pole portion are used in each case, but any type of device may be used as long as it has a mechanism through which paint, particles, etc. can pass through and be sprayed. Use a nozzle with an appropriate tip or a tipless nozzle that does not easily clog, and use it under appropriate coating conditions. In addition, it can be carried out by appropriately combining a coating machine that can be operated with electric power or compressed air, a hopper that stirs the paint, an auxiliary device that appropriately sieves the thermal spray powder, etc.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

10...pole part, 11...nozzle part.

Claims (10)

A solid material made of metal or carbon is added to existing power generation plant equipment where a large number of heat exchanger tubes are arranged closely together and narrow areas are formed between the heat exchanger tubes and adjacent heat exchanger tubes. , a coating film forming method for forming a coating film of rust prevention or heat transfer paint mixed with liquid paint,
a tubular pole part that can be inserted into the narrow part in the depth direction, can transport the rust preventive or heat transfer paint , and can change the nozzle head construction angle ;
a nozzle part provided at the tip of the pole part, capable of being inserted into the narrow part in the depth direction, and spraying the anti-rust or heat transfer paint by changing the spray angle from 30° to 120°; ,
By changing the construction angle of the nozzle head and the nozzle spray angle, it is possible to form a coating film on existing power generation plant equipment to achieve a rust prevention effect, or to maintain and improve heat transfer characteristics. A method for forming a coating film characterized by carrying out maintenance. Claim 1, wherein the solid substance is one or more metals in the form of particles, fibers, flakes, and capsules, and the metal weight ratio after film formation is 60% or more. The method for forming a coating film described in . The method for forming a coating film according to claim 1 or 2, wherein the solid substance includes a substance composed of one or more of carbon in the form of particles, fibers, flakes, and capsules. . According to any one of claims 1 to 3, the coating film of the anti-rust or heat transfer paint is formed using an airless coating machine at a secondary pressure of 6.5 MPa or more and 13 MPa or less. How to form a coating film. Any one of claims 1 to 3, wherein a coating film of the anti-corrosion or heat transfer paint is formed using an air coating machine, with the aperture of the nozzle part in a range of 1 mm or more and 3.5 mm or less. The method for forming the coating film described in section. forming a coating film twice on a heat exchanger tube group consisting of a large number of heat exchanger tubes from one side at least at a first angle and a second angle at different angles;
A step of forming a coating film twice on a heat exchanger tube group consisting of a large number of heat exchanger tubes from the other surface at different angles from the diagonal of the first angle and the second angle. The method for forming a coating film according to any one of claims 1 to 5. The method for forming a coating film according to claim 6, wherein the heat transfer tube group is installed in an exhaust heat recovery boiler installed in a combined cycle power generation plant. Claim 1, further comprising a step of blowing air or an inert gas at least either before the step of forming the paint film, during the step of forming the paint film, or after the step of forming the paint film. 8. The method for forming a coating film according to any one of items 7 to 7. The method for forming a coating film according to any one of claims 1 to 8, wherein the anticorrosive coating contains a metal element that has a low potential with respect to a metal part of the object to be coated. According to any one of claims 1 to 9, the rust-preventing coating film contains at least one selected from silicates, phosphates, nitrites, chromates, and ammonium salts. The method for forming the coating film described above.

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