Backflow prevention type pipe cleaning apparatus using air guide tube

Abstract

A backflow prevention pipe cleaning device using an air guide tube according to the present invention comprises: a pump for circulating cleaning fluid within a pipe; a compressor for supplying compressed air; and an air jet assembly including an air connection part formed in communication with the pipe in a direction perpendicular to the pipe and connected to the compressor via a solenoid valve, and an air guide tube inserted and fixed inside the air connection part, wherein the inlet end receives the compressed air in a direction perpendicular to the pipe and the outlet end is bent to face the direction of flow of the cleaning fluid within the pipe, thereby discharging the compressed air in the direction of flow of the cleaning fluid within the pipe. According to the backflow prevention pipe cleaning device using an air guide tube according to the present invention, by simply inserting and fixing an air guide tube with an outlet end bent inside the air connection part, the problem of pump idling and stopping due to backflow of compressed air is fundamentally resolved, and the compressed air and cleaning liquid are sprayed in the same direction, thereby having the effect of significantly improving scale removal efficiency.

Description

Technology Field

[0001] The present invention relates to a backflow prevention pipe cleaning device using an air guide tube, and more specifically, to a pipe cleaning device that prevents backflow of compressed air and improves scale removal efficiency by circulating a cleaning liquid within a pipe and simultaneously spraying compressed air in the direction of flow of the cleaning liquid, and inserting and fixing an air guide tube with an outlet end formed by bending inside an air connection part. Background Technology

[0002] Piping is a critical component for transporting fluids in various fields, such as heating and cooling systems, water supply facilities, and industrial process lines. Over time, the accumulation of scale, rust, and foreign substances on the inner walls can obstruct fluid flow or cause corrosion of the pipes themselves.

[0003] To resolve this, a pipe cleaning device was being used that physically removes scale by circulating a cleaning solution within the pipes while simultaneously injecting compressed air.

[0004] Conventional pipe cleaning devices, as shown in FIG. 8, consist of a pump that circulates cleaning fluid, a compressor that generates compressed air, and an air tank. They adopted a method in which an air connection is formed perpendicularly to the outer wall of the pipe, and compressed air supplied from the compressor is directly injected into the pipe through the air connection. However, in this method, since the air connection is formed perpendicularly to the pipe, compressed air is injected in the pipe in a direction opposite to the direction of flow of the cleaning fluid, causing a backflow phenomenon toward the pump. This backflow phenomenon caused the pump to idle and stop, resulting in the interruption of the cleaning operation, and also led to a decrease in the durability of the pump due to repeated backflow.

[0005] To prevent this, measures such as installing check valves at the piping connections of the air connection or lowering the pressure of the air supply line were attempted; however, the check valve installation method had the problem of the check valve malfunctioning or becoming clogged due to the cleaning solution and scale during the cleaning process, and the method of lowering the air pressure had the limitation of reduced cleaning efficiency due to a decrease in the physical impact force on the scale.

[0006] Therefore, there is a growing need for a pipe cleaning device that can fundamentally block the backflow of compressed air without structural changes to the air connection while simultaneously improving cleaning efficiency. Prior art literature

[0007] Korean Registered Patent No. 10-1690588 The problem to be solved

[0008] The present invention was devised to overcome the problems of the above technology, and its main purpose is to provide a device that fundamentally blocks the backflow of compressed air and simultaneously sprays the compressed air and cleaning liquid in the same direction by inserting and fixing an air guide pipe, which is bent so that its outlet end faces the direction of flow of the cleaning liquid, into an air connection part formed perpendicular to the pipe, thereby significantly improving the efficiency of scale removal on the inner wall of the pipe.

[0009] Another objective of the present invention is to maximize the physical impact force on the scale on the inner wall of the pipe by tapering the air guide pipe so that the outer diameter decreases from the bending starting point to the outlet end, thereby increasing the flow velocity of the compressed air and cleaning liquid according to the Bernoulli principle.

[0010] Another objective of the present invention is to simultaneously maximize the physical impact force on scale and the chemical cleaning power of the cleaning liquid by forming an extension portion at the outlet end that is tapered in the outer diameter and extended in the direction of flow of the cleaning liquid, thereby utilizing the pressure difference caused by the increased flow velocity of compressed air passing through the tapered section to actively suck in the cleaning liquid inside the pipe and mix and spray it with the compressed air. means of solving the problem

[0011] To achieve the above objective, a backflow prevention pipe cleaning device using an air guide tube according to the present invention comprises: a pump for circulating cleaning fluid within a pipe; a compressor for supplying compressed air; and an air jet assembly comprising an air connection part formed in communication with the pipe in a direction perpendicular to the pipe and connected to the compressor via a solenoid valve, and an air guide tube inserted and fixed inside the air connection part, wherein the inlet end receives the compressed air in a direction perpendicular to the pipe and the outlet end is bent to face the direction of flow of the cleaning fluid within the pipe, thereby discharging the compressed air in the direction of flow of the cleaning fluid within the pipe.

[0012] In addition, the air guide tube is characterized by having an inlet end formed with an outer diameter corresponding to the inner diameter of the air connection part so as to be tightly inserted and fixed to the air connection part, and being tapered so that the outer diameter decreases from the bending starting point to the outlet end.

[0013] In addition, the air guide tube is characterized by further including an extension portion that is extended so as to be tapered outwardly toward the outlet end and directed toward the direction of flow of the cleaning liquid. Effects of the invention

[0014] According to the backflow prevention pipe cleaning device using an air guide tube according to the present invention,

[0015] 1) It has the advantage of significantly improving scale removal efficiency by spraying compressed air and cleaning liquid in the same direction, while fundamentally resolving the problem of pump idling and stopping caused by backflow of compressed air through a simple structural improvement of inserting and fixing an air guide tube with an outlet end bent inside the air connection part,

[0016] 2) By forming the expansion section as a double pipe structure and forming a connecting hole in the first pipe and an inlet hole in the second pipe, the cleaning liquid within the piping is sucked in and mixed in stages via the inlet hole → separated space → connecting hole → compressed air flow, thereby improving the suction volume of the cleaning liquid and the uniformity of mixing compared to a single expansion section structure, and

[0017] 3) By coating a surface treatment layer containing polysilazane and hexagonal boron nitride on the outer surface of the second tube, it has the effect of maintaining surface stability for a long time without cracking or peeling in a repeated pressure pulse environment, suppressing scale adhesion, and preserving the open state of the inlet hole for a long time. Brief explanation of the drawing

[0018] FIG. 1 is a conceptual diagram showing the overall configuration of the backflow prevention pipe cleaning device of the present invention and the installation state of the air guide pipe. FIG. 2 is a plan view showing the compressor and air jet assembly connected to the piping. FIG. 3 is a conceptual diagram showing the state in which the outlet end of an air guide tube inserted and fixed inside an air connection part is bent so as to face the direction of flow of the cleaning fluid. FIG. 4 is a perspective plan view showing an example of a bent structure of an air guide tube inserted and fixed inside an air connection part. FIG. 5 is a plan view showing a tapered structure from the bending start point of an air guide tube to the outlet end. FIG. 6 is a plan view showing a structure in which an extension is formed at the outlet end of an air guide tube. FIG. 7 is a detailed plan view showing the double tubular structure and surface treatment layer of the expansion section. Fig. 8 is a photograph of a conventional pipe cleaning device. Specific details for implementing the invention

[0019] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The attached drawings are not drawn to scale, and the same reference numerals in each drawing refer to the same components.

[0020] FIG. 1 is a conceptual diagram showing the overall configuration of the backflow prevention type pipe cleaning device of the present invention and the installation state of the air guide pipe, and FIG. 2 is a plan view showing the state in which the compressor and air jet assembly are connected to the pipe.

[0021] As can be seen from FIG. 1, the backflow prevention pipe cleaning device of the present invention (hereinafter also abbreviated as 'pipe cleaning device') has the main purpose of improving the problem in which air flows back toward the pump side and the pump idles or stops when compressed air is injected directly into the pipe during conventional pipe cleaning operations, by inserting and fixing an air guide pipe inside the air connection part and forming the outlet end so as to face the direction of flow of the cleaning liquid, thereby discharging the compressed air in the direction of flow of the cleaning liquid.

[0022] Specifically, as can be seen from FIGS. 1 and FIGS. 2, the pipe cleaning device of the present invention is based on including a pump (20), a compressor (30), and an air jet assembly (100).

[0023] First, the pipe (10) is the cleaning target of the present invention and refers to a pipe in which problems have occurred such that scale (a solid deposit formed by the deposition of mineral components such as calcium and magnesium on the inner wall of the pipe), rust, foreign substances, etc. are deposited on the inner wall, thereby obstructing the flow of fluid or causing corrosion of the pipe (10) itself.

[0024] The material of the pipe (10) is not particularly limited and can be applied to pipes of various materials such as steel pipes, copper pipes, stainless steel pipes, and PVC pipes.

[0025] In addition, the use of the pipe (10) is not limited, and any pipe where scale buildup occurs, such as heating and cooling pipes, water supply pipes, and industrial process pipes, is applicable.

[0026] The pump (20) serves to circulate the cleaning fluid within the pipe (10).

[0027] The pump (20) is connected to a cleaning solution tank (not shown) that stores the cleaning solution, and pressurizes the cleaning solution supplied from the cleaning solution tank into the pipe (10), and forms a circulation structure in which the cleaning solution that passes through the pipe (10) is returned to the cleaning solution tank. At this time, the inlet and outlet of the cleaning solution are connected to each end of the pipe (10), and are connected to the pump (20) and the cleaning solution tank through connecting means such as hoses and couplings.

[0028] A check valve (21) is installed in the circulation line between the pump (20) and the piping (10) to prevent backflow of the cleaning fluid.

[0029] In addition, a pressure gauge (not shown) is installed in the circulation line to check the circulation pressure of the cleaning solution in real time, and the operator can indirectly determine the cleaning status and the progress of scale removal inside the pipe (10) through the reading of the pressure gauge.

[0030] The type of pump (20) is not particularly limited and can be appropriately selected and used according to the viscosity and circulation flow rate of the cleaning fluid, such as a centrifugal pump or a gear pump.

[0031] Here, the cleaning solution refers to a liquid agent for dissolving or peeling off scale, rust, foreign substances, etc., deposited on the inner wall of the pipe (10).

[0032] These cleaning solutions can be appropriately selected and used among acidic cleaning solutions, alkaline cleaning solutions, or neutral cleaning solutions depending on the material of the pipe (10) and the type of scale.

[0033] For example, hydrochloric acid-based or citric acid-based cleaning solutions are effective for removing calcium carbonate-based scale, and sodium hydroxide-based cleaning solutions are effective for removing oily foreign substances.

[0034] The compressor (30) generates compressed air and supplies it to the air jet assembly (100) described later.

[0035] Here, compressed air refers to air in the atmosphere compressed and stored in a high-pressure state, and in the present invention, it is used as a means to remove scale and foreign substances attached to the inner wall of a pipe (10) that are difficult to remove with only a cleaning solution by means of physical impact force.

[0036] In other words, the purpose is to significantly improve scale removal efficiency compared to circulating the cleaning solution alone by injecting compressed air together with the cleaning solution in the direction of flow.

[0037] The compressor (30) includes an air tank that compresses and stores air from the atmosphere, and the compressed air stored in the air tank is supplied to the air jet assembly (100).

[0038] The type of compressor (30) is not particularly limited, and can be selected and used according to the required pressure and flow rate, such as reciprocating type, screw type, etc.

[0039] A pressure regulator (regulator, not shown) may be installed in the air supply line between the compressor (30) and the air jet assembly (100), and the pressure of the compressed air supplied to the air jet assembly (100) can be adjusted to suit the working conditions.

[0040] For example, depending on the diameter of the pipe (10) and the degree of scale accumulation, the pressure of the compressed air can be adjusted in the range of 2 to 7 bar.

[0041] The air jet assembly (100) guides compressed air supplied from a compressor (30) into a pipe (10) and sprays it in the direction of flow of the cleaning liquid, and specifically includes an air connection part (110) and an air guide pipe (120).

[0042] The air connection part (110) is formed on the outer wall of the pipe (10) in a direction perpendicular to the longitudinal direction of the pipe (10) and serves as a passage for introducing compressed air supplied from the compressor (30) into the pipe (10).

[0043] If the air connection part (110) is installed along the length direction of the pipe (10), compressed air can be supplied directly in the direction of flow of the cleaning liquid, but in this case, the structure of the pipe (10) that was previously installed must be significantly changed or the pipe (10) must be cut and inserted inline, so construction is complex and costs increase.

[0044] On the other hand, if the air connection part (110) is formed in a direction perpendicular to the pipe (10), it can be simply connected to the outer wall of the pipe (10), making construction easy and minimizing structural changes to the pre-installed pipe (10).

[0045] If the compressed air introduced in this manner at a right angle is injected directly into the pipe (10), it acts in the opposite direction to the direction of flow of the cleaning liquid and can cause backflow toward the pump (20), and the direction change is handled by the air guide pipe (120) described later.

[0046] The air connection part (110) is connected to the compressor (30) via a solenoid valve, and the supply of compressed air is controlled according to the opening and closing operation of the solenoid valve.

[0047] At this time, the solenoid valve is an electronic valve whose opening and closing is controlled by an electric signal, and it is suitable for controlling an intermittent injection method as it can rapidly and accurately repeat the supply and blocking of compressed air according to the electric signal received from the controller (200).

[0048] The response speed of the solenoid valve is not particularly limited, but it is preferable to use one with a response time of 100 ms or less for precise control of the intermittent injection cycle.

[0049] The method of joining the pipe (10) of the air connection part (110) is not particularly limited and can be selected and applied according to the material of the pipe (10) and the working environment, such as welding, screw joining, or flange joining.

[0050] In addition, the material of the air connection part (110) is not particularly limited, and can be selected and used from metal materials with pressure resistance and corrosion resistance, such as stainless steel, brass, and carbon steel, depending on the type of cleaning solution and working environment.

[0051] In addition, the inner diameter of the air connection part (110) is not specifically limited, for example, when the diameter of the pipe (10) is 25 to 100 mm, the inner diameter of the air connection part (110) can be selected in the range of 10 to 25 mm.

[0052] FIG. 3 is a conceptual diagram showing the state in which the outlet end of an air guide tube inserted and fixed inside an air connection is bent so as to face the direction of flow of the cleaning liquid, and FIG. 4 is a perspective plan view showing an embodiment of the bent structure of an air guide tube inserted and fixed inside an air connection.

[0053] The air guide tube (120) is inserted and fixed inside the air connection part (110), and the inlet end receives compressed air supplied from the compressor (30) in a direction perpendicular to the pipe (10), and the outlet end is bent and formed to face the direction of flow of the cleaning liquid inside the pipe (10) so as to discharge the compressed air in the direction of flow of the cleaning liquid inside the pipe (10).

[0054] At this time, the method of inserting and fixing the air connection part (110) of the air guide tube (120) is not particularly limited.

[0055] For example, methods such as forming the outer diameter of the air guide tube (120) to correspond to the inner diameter of the air connection part (110) and pressing it in tightly, welding the outer surface of the air guide tube (120) and the inner surface of the air connection part (110) to fix it, or forming screw threads on the outer surface of the air guide tube (120) and screwing it into the inner surface of the air connection part (110) may be applied. When applying the screw connection method, it is preferable to use airtightness maintenance means such as wrapping sealing tape, inserting an O-ring, or applying sealant to prevent leakage of compressed air through the gaps in the screw threads. Regardless of which method is applied, airtightness must be maintained so that compressed air does not leak through the gap between the air guide tube (120) and the air connection part (110).

[0056] The fact that the outlet end of the air guide tube (120) is formed by bending it so as to face the direction of flow of the cleaning liquid means that the outlet end of the air guide tube (120) is formed in a bent shape so that the discharge direction of the compressed air introduced perpendicularly through the air connection part (110) aligns with the direction of flow of the cleaning liquid.

[0057] For example, various bending shapes may be applied, such as the outlet end of the air guide tube (120) being bent at 90° so that it is discharged completely parallel to the direction of flow of the cleaning liquid, the outlet end being bent at 45° so that it is discharged at an angle toward the direction of flow of the cleaning liquid, or the outlet end being bent toward the central axis of the pipe (10) so that compressed air is concentrated and discharged toward the central part of the cross-section of the pipe (10).

[0058] Among these, the shape in which the outlet end is bent at a 90° angle parallel to the direction of flow of the cleaning solution is considered the most effective in terms of backflow prevention and cleaning efficiency. In this case, it can be implemented not only in a form that achieves a 90° angle in one go with a single inclined bend, but also in a multi-stage bend form that changes direction step by step through multiple bends.

[0059] For example, a configuration in which two 45° bends are arranged in series to ultimately achieve a 90° direction change, or a configuration in which three 30° bends are arranged sequentially, may be applied. Compared to a single-stage bend configuration, the multi-stage bend configuration can reduce pressure loss and vortices that occur when the compressed air is changed direction, making it advantageous in terms of discharge efficiency.

[0060] Meanwhile, as shown in FIG. 4, a shape in which the outlet end is bent at approximately 55° is also an effective embodiment. In this case, the compressed air is discharged toward the central part of the pipe (10) while maintaining an angle of inclination with respect to the direction of flow of the cleaning liquid, so there is an advantage that the mixture of compressed air and cleaning liquid is evenly sprayed over the entire inner wall of the pipe (10).

[0061] In addition, compared to the 90° bend shape, it is easier to bend, and the outlet end of the air guide tube (120) does not come close to the inner wall of the pipe (10), so it has the advantage of being universally applicable regardless of the diameter of the pipe (10).

[0062] The material of the air guide tube (120) is also not particularly limited, and can be selected from metal materials that are easy to bend and have pressure resistance and corrosion resistance, such as stainless steel, brass, and copper pipe.

[0063] It is preferable that the inner diameter of the air guide tube (120) be smaller than the inner diameter of the air connection part (110) in order to increase the flow rate of compressed air and cleaning liquid according to the Bernoulli principle and improve the efficiency of removing scale from the inner wall of the pipe (10). For example, if the inner diameter of the air connection part (110) is 15 mm, the inner diameter of the air guide tube (120) can be selected in the range of 6 to 10 mm.

[0064] The operation flow of the pipe cleaning device of the present invention is described below.

[0065] First, when the pump (20) is driven, the cleaning liquid stored in the cleaning liquid tank is pumped into the pipe (10) and begins to circulate. The cleaning liquid flows into the inlet side of the pipe (10), comes into contact with scale and foreign matter on the inner wall of the pipe (10), flows along the direction of travel, is discharged to the outlet side of the pipe (10), and is then recovered back into the cleaning liquid tank.

[0066] At the same time, compressed air generated in the compressor (30) is supplied to the air connection part (110) through the solenoid valve. Since the air connection part (110) is connected in a direction perpendicular to the pipe (10), the compressed air flows into the air connection part (110) in a direction perpendicular to the pipe (10).

[0067] The inlet end of the air guide tube (120), which is inserted and fixed inside the air connection part (110), receives this compressed air in a perpendicular direction, and the direction of travel of the compressed air is changed to the direction of travel of the cleaning liquid by the bending structure of the outlet end and discharged into the pipe (10).

[0068] In this way, by discharging compressed air in the same direction as the direction of flow of the cleaning solution, the phenomenon of compressed air flowing back toward the pump (20) is blocked, and the cleaning solution and compressed air are sprayed together in the direction of flow of the cleaning solution, thereby increasing the physical peeling force against scale on the inner wall of the pipe (10).

[0069] In summary, the pipe cleaning device of the present invention provides a characteristic that fundamentally resolves the problem of the pump (20) running idle and stopping due to backflow of compressed air through a simple structural improvement of forming the outlet end of the air guide pipe (120) in the direction of flow of the cleaning liquid, while simultaneously spraying the compressed air and cleaning liquid together in the same direction to significantly improve the scale removal efficiency of the inner wall of the pipe (10).

[0070] Additionally, the pipe cleaning device of the present invention may further include a controller (200) to maximize the physical peeling force against scale on the inner wall of the pipe (10) compared to the circulation of the cleaning liquid alone by periodically opening and closing a solenoid valve during the circulation operation of the pump (20) to intermittently spray compressed air.

[0071] The controller (200) controls the overall operation of the pipe cleaning device of the present invention, and in particular, during the circulation operation of the pump (20), it functions to periodically open and close the solenoid valve to intermittently inject compressed air.

[0072] The controller (200) may be implemented as a timer circuit or a microprocessor-based control unit and is electrically connected to the pump (20) and the solenoid valve. Additionally, it may include an input means for an operator to set the intermittent injection cycle and injection time, and a display means for checking the current operating status.

[0073] The controller (200) may be connected to a pressure sensor (not shown) that monitors the operating status of the compressor (30) and a pressure gauge (not shown) that checks the circulation pressure in the pipe (10).

[0074] Based on the signal received from the pressure sensor, if the pressure in the air tank of the compressor (30) drops below a set value, the opening and closing operation of the solenoid valve can be temporarily suspended so that the compressor (30) can resume intermittent injection after recovering sufficient pressure.

[0075] The operation flow of such a controller (200) is described as follows.

[0076] When an operator sets the intermittent injection cycle and injection time on the controller (200) and inputs a drive command, the controller (200) first drives the pump (20) to start circulating the cleaning fluid within the pipe (10).

[0077] When the circulation of the cleaning fluid stabilizes, the controller (200) opens the solenoid valve according to a set cycle to spray compressed air into the pipe (10) through the air jet assembly (100), and closes the solenoid valve when the set spraying time has elapsed.

[0078] By repeating this opening and closing motion, the cleaning fluid circulation flow is maintained, and a repetitive physical peeling force is applied to the scale on the inner wall of the pipe (10) by periodic air shock, thereby improving cleaning efficiency.

[0079] At this time, the intermittent injection cycle and injection time are not specifically limited, for example, a method can be applied in which the solenoid valve is opened and closed at intervals of 3 to 10 seconds and the injection time per cycle is set to 0.5 to 2 seconds.

[0080] According to such a controller (200), it is possible to apply a repetitive physical peeling force to the scale on the inner wall of the pipe (10) by intermittently injecting compressed air during the circulation operation of the pump (20), as well as prevent overload of the pump (20) and disturbance of the cleaning fluid circulation flow that may occur during continuous injection, thereby maintaining the advantage of stable operation of the equipment.

[0081] FIG. 5 is a plan view showing a tapered structure from the bending start point of an air guide tube to the outlet end.

[0082] Furthermore, in order to increase the flow rate of compressed air and cleaning fluid passing through the air guide tube (120) and improve the efficiency of removing scale from the inner wall of the pipe (10), the air guide tube (120) may have a tapered structure.

[0083] Specifically, the inlet end of the air guide tube (120) is formed with an outer diameter corresponding to the inner diameter of the air connection part (110) and is inserted and fixed in close contact with the air connection part (110).

[0084] Here, "outer diameter corresponding to the inner diameter of the air connection part (110)" means that the outer diameter of the inlet end of the air guide tube (120) is formed to be substantially the same as the inner diameter of the air connection part (110) so that the two are in close contact without any gap.

[0085] In this way, by inserting and fixing the inlet end to the air connection part (110) in close contact, the compressed air supplied from the compressor (30) can be guided to flow only through the inside of the air guide tube (120) without leaking through the gap between the air guide tube (120) and the air connection part (110).

[0086] Various methods such as press fitting, welding, and screw connection can be applied to the connection method between the inlet end of the air guide tube (120) and the air connection part (110), but airtightness must be maintained regardless of which method is applied.

[0087] As shown in FIG. 5, the air guide tube (120) can be tapered so that its outer diameter decreases from the bending starting point to the exit end.

[0088] The form of the taper treatment is not particularly limited; for example, a straight taper form in which the outer diameter decreases linearly from the bending start point to the exit end, a curved taper form in which the outer diameter decreases curvilinearly, or a multi-stage taper form in which the outer diameter decreases in steps may be applied. Among these, the straight taper form is the most desirable because it is easy to process and the change in flow velocity is uniform.

[0089] However, when tapering, the outer diameter of the bending starting point must be formed smaller than the inner diameter of the air connection part (110).

[0090] This is because the bending starting point is located near the bottom of the air connection part (110), and if the outer diameter of the point where the taper starts is the same as or larger than the inner diameter of the air connection part (110), the bending part of the air guide tube (120) interferes with the inner wall of the air connection part (110), making insertion impossible or causing the bending shape to be deformed.

[0091] For example, when the inner diameter of the air connection part (110) is 15 mm, it is preferable to form the outer diameter of the inlet side end to be 15 mm so as to insert it tightly, and to form the outer diameter of the bending starting point to be 12 mm or less so as to prevent interference with the inner wall of the air connection part (110).

[0092] In this way, it is preferable to have a section where the outer diameter gradually decreases from the entrance end to the bending start point, or to form a stepped section before the bending start point so that the air guide tube (120) can be freely bent without interference with the inner wall of the air connection part (110).

[0093] In this way, by tapering so that the outer diameter decreases from the bending starting point to the outlet end, the flow velocity of the compressed air and cleaning liquid passing through the air guide tube (120) increases as it approaches the outlet end according to the Bernoulli principle.

[0094] For example, if the inner diameter of the bending start point is 12 mm and the inner diameter of the exit end is 6 mm, the cross-sectional area ratio becomes 4:1, and the flow velocity at the exit end increases by about 4 times compared to the bending start point.

[0095] The increased flow rate in this way significantly improves the physical impact force applied to the scale on the inner wall of the pipe (10), thereby increasing the cleaning efficiency.

[0096] In summary, the inlet end of the air guide tube (120) is inserted and fixed tightly into the air connection part (110) to accurately discharge the cleaning liquid in the direction of flow without leakage of compressed air, and the flow velocity increases toward the outlet end due to the taper treatment of the bent part of the air guide tube (120), thereby providing the characteristic of maximizing the physical impact force on the scale on the inner wall of the pipe (10).

[0097] Figure 6 is a plan view showing a structure in which an extension is formed at the outlet end of an air guide tube.

[0098] Furthermore, in order to maximize the mixing of compressed air and cleaning liquid by actively drawing the cleaning liquid in the pipe (10) into the air flow at the point where the flow velocity increases and the pressure decreases at the outlet end due to the tapered treatment described above, the air guide pipe (120) may further include an extension (140) that is extended so as to be tapered outward from the outlet end and extended toward the direction of the cleaning liquid's flow, as shown in FIG. 6.

[0099] The expansion section (140) is formed in the shape of a diffuser that opens outward from the outlet end, and the cleaning liquid inside the pipe (10) is sucked into the expansion section (140) by the pressure difference generated as the compressed air accelerated while passing through the tapered section passes through the expansion section (140).

[0100] The cleaning solution sucked in in this way is mixed with compressed air and sprayed toward the inner wall of the pipe (10), thereby producing an effect where the physical impact force on the scale and the chemical cleaning force of the cleaning solution act simultaneously compared to the injection of compressed air alone.

[0101] The expansion angle and length of the expansion section (140) are not specifically limited, for example, the expansion angle can be selected from 15 to 30° and the length from 1 to 3 times the inner diameter of the air guide tube (120). If the expansion angle is too large, the suction efficiency is reduced, and if it is too small, it is difficult to perform the function of the expansion section (140), so it is preferable to apply it within the above range.

[0102] Additionally, if the length of the extension (140) is excessively long, it may interfere with the inner wall of the pipe (10), and if it is excessively short, the amount of cleaning fluid sucked in may be insufficient, which may reduce the mixing spray effect. Therefore, it is preferable to set the end of the extension (140) to be located near the central axis of the pipe (10) by considering the inner diameter of the pipe (10) and the installation position of the air guide pipe (120).

[0103] As a result, the expansion section (140) has a simple structure in which the outer diameter tapers at the outlet end, and by using the pressure difference caused by the increase in the flow velocity of compressed air passing through the tapered section, it actively sucks in the cleaning liquid inside the pipe (10), and by mixing the sucked cleaning liquid with compressed air and spraying it at high pressure toward the inner wall of the pipe (10), it provides the characteristic of simultaneously maximizing the physical impact force on the scale and the chemical cleaning power of the cleaning liquid compared to spraying compressed air alone.

[0104] Figure 7 is a detailed plan view showing the double tubular structure and surface treatment layer of the expansion section.

[0105] Furthermore, in order to maximize the suction efficiency of the cleaning fluid by the previously described expansion part (140), the expansion part (140) may be formed as a double tubular structure as shown in FIG. 7.

[0106] Specifically, the expansion portion (140) is formed as a double tubular structure comprising a first tubular body (141) that is extended so as to be tapered outwardly toward the outlet end and in the direction of flow of the cleaning liquid, and a second tubular body (142) that is arranged to surround the outer surface of the first tubular body (141) at a certain interval.

[0107] A certain gap is formed between the first pipe (141) and the second pipe (142), and this gap serves as a buffer space where the cleaning liquid inside the pipe (10) flows in and temporarily stays before joining with the air flow inside the first pipe (141).

[0108] In the first tube (141), a plurality of connecting holes (141a) are formed at regular intervals along the length direction of the expansion portion (140).

[0109] The connecting hole (141a) serves to connect the space between the first pipe (141) and the second pipe (142) with the inside of the first pipe (141), and becomes a passage through which cleaning fluid is sucked into the low-pressure area formed inside the first pipe (141) due to the increased flow velocity of compressed air passing through the tapered section.

[0110] The shape of the connecting hole (141a) is not particularly limited and can be formed in various shapes such as circular, elliptical, or slit-shaped.

[0111] For example, as shown in FIG. 7, if three connecting holes (141a) are arranged at equal intervals along the longitudinal direction of the extension (140), even suction of cleaning fluid is achieved throughout the entire interior of the first tube (141).

[0112] In the second pipe body (142), multiple inlet holes (143) are formed at regular intervals along the length direction of the expansion part (140) through which the cleaning liquid inside the pipe (10) flows into the space between the first pipe body (141) and the second pipe body (142).

[0113] The inlet hole (143) penetrates the outer wall of the second pipe body (142) to connect the spaced space and the inside of the pipe (10), and forms a flow path in which the cleaning liquid circulating inside the pipe (10) is introduced into the spaced space through the inlet hole (143), then passes through the connecting hole (141a) and is mixed with the air flow inside the first pipe body (141) and discharged.

[0114] For example, as shown in FIG. 7, three inlet holes (143) are arranged at equal intervals on the outer wall of the second pipe (142), but are arranged staggered with the connecting holes (141a), so that the cleaning liquid is evenly dispersed within the spaced-apart space and then flows into the connecting holes (141a), thereby improving the uniformity of mixing.

[0115] According to this double pipe structure, the cleaning liquid inside the pipe (10) is actively sucked in along the path from the inlet hole (143) → the spaced-out space → the connecting hole (141a) → the air flow inside the first pipe (141), and the compressed air and cleaning liquid are sufficiently mixed and then sprayed at high pressure toward the inner wall of the pipe (10), thereby producing the effect of significantly improving scale removal efficiency.

[0116] The operation flow of such a double tubular structure is explained as follows.

[0117] When the compressor (20) is driven and the cleaning fluid circulates within the pipe (10), compressed air is supplied from the compressor (30). As the compressed air passes through the tapered section of the air guide pipe (120), the flow velocity increases and the pressure decreases. This low-pressure state is maintained inside the first pipe body (141), and a suction force is generated inside the first pipe body (141).

[0118] At the same time, the cleaning liquid circulating inside the pipe (10) flows into the gap between the first pipe (141) and the second pipe (142) through the inlet hole (143) formed on the outer wall of the second pipe (142), and the cleaning liquid temporarily remaining in the gap is sucked into the first pipe (141) through the connecting hole (141a) by the suction force inside the first pipe (141) and mixed with compressed air. The compressed air and cleaning liquid thus mixed are sprayed at high pressure toward the inner wall of the pipe (10) through the outlet of the expansion part (140).

[0119] According to this double pipe structure, compared to a single expansion section (140) structure, the suction amount of cleaning liquid is increased and the mixing of compressed air and cleaning liquid is carried out stepwise within the spaced space, thereby improving the uniformity of the mixture. Furthermore, the suction amount and mixing ratio can be adjusted according to the arrangement combination of the inlet hole (143) and the connecting hole (141a), providing characteristics that allow for optimization according to the diameter of the pipe (10) and the degree of scale accumulation.

[0120] The second pipe body (142) described above is located in a position directly exposed to the cleaning liquid and scale circulating within the pipe (10). Whenever compressed air is periodically supplied in an intermittent injection manner, repetitive pressure pulses are applied to the entire expansion section (140), raising concerns that surface damage and scale adhesion may occur on the outer surface of the second pipe body (142). In particular, as the pressure pulses are repeated, micro-cracks may progress on the outer surface of the second pipe body (142), or scale may adhere to the outer surface, blocking the inlet hole (143) and thereby blocking the cleaning liquid suction path.

[0121] To solve this, as shown in FIG. 7, a surface treatment layer (142b) comprising polysilazane and hexagonal boron nitride is coated on the outer surface of the second tube (142).

[0122] That is, the surface treatment layer (142b) of the present invention is introduced to achieve surface stabilization of the outer surface of the second tube (142) in a repeated pressure pulse environment, and the characteristics of the two materials constituting it are as follows.

[0123] Polysilazane is an inorganic polymer compound with a Si-N bond as its main chain, represented by the chemical formulas (SiH_2NH)_n or (R_1R_2Si-NR_3)_n. The Si-N bonds within the molecule exhibit the characteristic of converting into SiO_2 and Si_3N_4 series ceramic structures under thermal and oxidizing environments. During the firing process following coating, it forms a dense ceramic matrix, thereby demonstrating excellent chemical resistance, heat resistance, and pressure resistance. This material has been used in the fields of semiconductor insulating films and heat-resistant coatings.

[0124] In the surface treatment layer (142b), polysilazane forms a ceramic matrix to provide a function of protecting the outer surface of the second tube (142) from cleaning liquid and scale. Additionally, after firing, a dense SiO2·Si3N4 composite ceramic layer is formed in close contact with the outer surface, which suppresses the adhesion of scale and prevents the blockage of the inlet hole (143).

[0125] Hexagonal boron nitride (h-BN) is an inorganic compound with a layered structure in which boron (B) and nitrogen (N) form a hexagonal lattice through sp2 hybrid bonding, and its chemical formula is denoted as (BN)_n.

[0126] It has a layered structure similar to graphite and exhibits excellent thermal conductivity, electrical insulation, and low friction characteristics, so it was being used in high-temperature lubricants and heat dissipation fillers.

[0127] In the surface treatment layer (142b), the hexagonal boron nitride is dispersed within the polysilazane ceramic matrix and provides a function to improve surface stability by suppressing crack propagation caused by repeated pressure pulses through an interlayer sliding mechanism, and also has a function to reduce the adhesion of scale to the outer surface due to low friction characteristics.

[0128] By forming a composite network with a ceramic matrix of polysilazane and a layered structure of hexagonal boron nitride, crack propagation caused by repeated loading, which is weak for the hard ceramic layer alone, is suppressed by the interlayer energy absorption mechanism of hexagonal boron nitride, thereby exhibiting a surface stabilization synergy effect that exceeds the simple sum of the two components.

[0129] Furthermore, the combination of these has significantly superior durability in a repetitive pressure pulse environment compared to simple fluorine-based water-repellent coatings such as polytetrafluoroethylene (PTFE) and fluorinated acrylate. While fluorine-based coatings have excellent water-repellent and anti-fouling properties, they cannot form a ceramic matrix and are susceptible to cracking and peeling due to repetitive loading. In contrast, the polysilazane-hexagonal boron nitride combination of the present invention forms a dense ceramic composite network, thereby maintaining the long-term stability of the surface treatment layer (142b) without cracking or peeling.

[0130] In summary, the surface treatment layer (142b) of the present invention can provide the advantage of maintaining surface stability by preventing cracking and peeling of the outer surface of the second tube (142) in a repeated pressure pulse environment, as well as maintaining the cleaning fluid suction function of the double tube structure stably for a long period of time by suppressing the adhesion of scale and preventing blockage of the inlet hole (143).

[0131] Furthermore, it is more preferable that the surface treatment layer (142b) of the present invention includes three additional compositions to simultaneously achieve improved flexibility in a repetitive pressure pulse environment, increased crosslinking density, and reduced surface energy, while maintaining the basic properties based on a ceramic composite network of polysilazane and hexagonal boron nitride.

[0132] Specifically, the surface treatment layer may comprise, based on 100 parts by weight thereof, 45 to 55 parts by weight of polysilazane, 5 to 15 parts by weight of hexagonal boron nitride, 15 to 25 parts by weight of octakis(3,3,3-trifluoropropyl)octasilsesquioxane, 10 to 15 parts by weight of diphenylsilanediol, and 10 to 20 parts by weight of 4,4′-bis(perfluorohexyl)benzophenone.

[0133] Furthermore, it is more preferable that the surface treatment layer (142b) of the present invention includes three additional compositions to simultaneously achieve improved flexibility in a repetitive pressure pulse environment, increased crosslinking density, and reduced surface energy, while maintaining the basic properties based on a ceramic composite network of polysilazane and hexagonal boron nitride.

[0134] Here, if the polysilazane is less than 45 parts by weight, the density of the ceramic matrix is ​​insufficient, which reduces the crack prevention effect caused by repeated pressure pulses, and if it exceeds 55 parts by weight, the hardness of the coating layer becomes excessively high, increasing brittleness and making it vulnerable to cracking, so it has critical significance to limit it to 45 to 55 parts by weight.

[0135] In addition, if the hexagonal boron nitride is less than 5 parts by weight, the crack propagation inhibition effect due to the layered structure is not sufficiently expressed, and if it exceeds 15 parts by weight, aggregation occurs within the polysilazane ceramic matrix, which reduces the uniformity of the coating layer, so it is preferable to limit it to 5 to 15 parts by weight.

[0136] Octakis(3,3,3-trifluoropropyl)octasilsesquioxane is a fluorine-containing POSS (Polyhedral Oligomeric Silsesquioxane) compound in which a 3,3,3-trifluoropropyl group is substituted into a silsesquioxane cage structure in which eight silicon atoms are connected by oxygen bridges, and its chemical formula is represented as [CF_3CH_2CH_2SiO_1.5]_8.

[0137] It exhibits low surface energy and excellent chemical resistance due to intramolecular fluorine substituents, while the Si-O cage core provides thermal stability and mechanical stiffness. This material has been used in fields such as polymer composite fillers.

[0138] In the surface treatment layer (142b), octakis(3,3,3-trifluoropropyl)octasilsesquioxane is dispersed within the polysilazane ceramic matrix and provides a function to inhibit the adhesion of scale and foreign substances by reducing the surface energy of the coating layer.

[0139] In addition, the Si-O cage structure chemically bonds with the ceramic matrix to reinforce the flexibility of the coating layer, thereby serving to suppress crack propagation caused by repetitive pressure pulses.

[0140] In particular, in combination with polysilazane, the Si-O cage structure acts as a crosslinking point in the ceramic matrix, improving the network density of the entire coating layer; this exhibits a synergistic effect that simultaneously enhances pressure resistance and flexibility compared to polysilazane alone.

[0141] If the octakis(3,3,3-trifluoropropyl)octasilsesquioxane in the surface treatment layer (142b) is less than 15 parts by weight, there is a problem that the surface energy reduction and flexibility reinforcement effects are not sufficiently expressed, and if it exceeds 25 parts by weight, there is a problem that the compatibility with the polysilazane ceramic matrix is ​​reduced and phase separation occurs within the coating layer, so it is preferable to set it to 15 to 25 parts by weight.

[0142] Diphenylsilanediol is an organic silane compound in which two phenyl groups and two hydroxyl groups are bonded to a silicon atom, and its chemical formula is represented as (C_6H_5)_2Si(OH)_2.

[0143] This is because the hydroxyl group (-OH) reacts with the Si-N bond of polysilazane and the Si-O structure of octakis(3,3,3-trifluoropropyl)octasilsesquioxane to form Si-O-Si cross-links, and the phenyl group imparts hydrophobicity and flexibility to the coating layer.

[0144] This material was being used in the fields of silicone resin crosslinking agents and organic-inorganic hybrid coatings.

[0145] In the surface treatment layer (142b), diphenylsilanediol improves the network density of the entire coating layer through a cross-linking reaction with polysilazane and octakis(3,3,3-trifluoropropyl)octasilsesquioxane, strengthens the adhesion between the coating layer and the outer surface of the second tube (142), and has the function of improving the durability of the coating layer by suppressing the penetration of cleaning solution through hydrophobicity imparted by the phenyl group.

[0146] In particular, in combination with polysilazane, the hydroxyl groups of diphenylsilanediol react with the Si-N bonds of polysilazane to form a Si-O-Si crosslinked structure, thereby improving the density of the ceramic matrix after firing and exhibiting a synergistic effect that significantly increases the adhesion between the coating layer and the substrate.

[0147] In the surface treatment layer (142b), if the amount of diphenylsilanediol is less than 10 parts by weight, the crosslinking density is insufficient, which causes a problem of reduced adhesion and durability of the coating layer, and if it exceeds 15 parts by weight, the brittleness of the coating layer increases due to excessive crosslinking, making it vulnerable to cracking caused by repeated pressure pulses, so it is preferable to set it to 10 to 15 parts by weight.

[0148] 4,4′-bis(perfluorohexyl)benzophenone is a fluorine-containing aromatic ketone compound in which a perfluorohexyl group (-C_6F_13) is substituted at the 4,4′ position of the benzophenone backbone, and its chemical formula is represented as (C_6F_13-C_6H_4)_2CO.

[0149] Here, the high fluorine content of the perfluorohexyl group exhibits extremely low surface energy, and the benzophenone backbone possesses UV absorption properties along with the characteristic of inducing photocrosslinking reactions within the coating layer.

[0150] This material was being used in the fields of fluorine-based water-repellent and anti-fouling coatings and photocrosslinkable functional coatings.

[0151] In the surface treatment layer (142b), 4,4′-bis(perfluorohexyl)benzophenone is oriented with perfluorohexyl groups on the outermost edge of the coating layer to minimize surface energy, thereby providing a function that fundamentally inhibits the attachment of scale, cleaning fluid and foreign substances.

[0152] In addition, the photocrosslinking reaction by the benzophenone backbone strengthens intermolecular bonds within the coating layer, thereby inhibiting the delamination of the surface layer under a repetitive pressure pulse environment.

[0153] In particular, in combination with octakis(3,3,3-trifluoropropyl)octasilsesquioxane, the fluorine groups of the two components are arranged complementarily to form a uniform ultra-low surface energy layer across the entire coating layer, thereby exhibiting a significantly enhanced effect in inhibiting scale adhesion compared to each component alone.

[0154] In the surface treatment layer (142b), if the amount of 4,4′-bis(perfluorohexyl)benzophenone is less than 10 parts by weight, the surface energy reduction effect is insufficient, and the scale adhesion inhibition function is reduced. If the amount exceeds 20 parts by weight, the fluorine content in the coating layer becomes excessive, which reduces compatibility with the polysilazane ceramic matrix and causes a decrease in the uniformity of the coating layer. Therefore, it is preferable to set the amount to 10 to 20 parts by weight.

[0155] As such, the surface treatment layer (142b) composed of five types of compositions, including polysilazane, hexagonal boron nitride, octakis(3,3,3-trifluoropropyl)octasilsesquioxane, diphenylsilanediol, and 4,4′-bis(perfluorohexyl)benzophenone, does not perform only independent roles but forms a complex network structure in which each component is organically combined to exhibit the following comprehensive characteristics.

[0156] First, the network density is strengthened by the cross-linking reaction of diphenylsilanediol using a ceramic matrix of polysilazane as a framework, thereby ensuring mechanical strength of the entire coating layer and adhesion to the outer surface of the second tube (142).

[0157] Second, the layered structure of hexagonal boron nitride and the Si-O cage structure of octakis(3,3,3-trifluoropropyl)octasilsesquioxane are dispersed within the ceramic matrix to block crack propagation paths caused by repeated pressure pulses, thereby ensuring long-term durability of the coating layer.

[0158] Third, the fluorine groups of octakis(3,3,3-trifluoropropyl)octasilsesquioxane and 4,4′-bis(perfluorohexyl)benzophenone are oriented at the outermost edge of the coating layer to form an ultra-low surface energy layer, thereby fundamentally suppressing the attachment of scale and foreign substances and maintaining the long-term open state of the inlet hole (143).

[0159] As a result, the five types of composite surface treatment layers (142b) of the present invention simultaneously provide mechanical rigidity, crack resistance, and contamination adhesion inhibition properties within a single coating layer, thereby providing properties as a composite network coating that is maintained stably for a long period without cracking or peeling in a repeated pressure pulse environment.

[0160] In the following, to verify the effect of the surface treatment layer (142b) of the present invention, coating layers according to the examples and comparative examples were each prepared, and the amount of scale adhesion under high-speed air-washing liquid mixed flow conditions, resistance to cracking and peeling of the coating layer under a repetitive pressure pulsation environment, nucleation delay time under dissolved inorganic salt conditions, and crystal growth inhibition characteristics were compared and evaluated.

[0161] <Example 1>

[0162] Example 1 was prepared with a two-component composition comprising 80 parts by weight of polysilazane and 20 parts by weight of hexagonal boron nitride.

[0163] First, a polysilazane solution was prepared by dissolving polysilazane in a dibutyl ether solvent at a concentration of 20 wt%. Hexagonal boron nitride powder (average particle size 2 μm) was added to the polysilazane solution and uniformly dispersed using an ultrasonic disperser (40 kHz, 30 minutes) to prepare a coating solution. The prepared coating solution was applied to the outer surface of the second tube (142) by a spray coating method, with the application being 3 times and the coating thickness being approximately 10 μm per application, thereby forming a total coating thickness of approximately 30 μm.

[0164] At this time, the second tube (142) is made of stainless steel (SUS316L) with an outer diameter of 20 mm, an inner diameter of 16 mm, and a length of 80 mm, and this is the same in Example 2 and Comparative Examples 1 and 2 below.

[0165] After coating, the surface treatment layer (142b) was completed by drying at room temperature for 30 minutes and then firing at 250°C for 1 hour to convert the polysilazane into a SiO2·Si3N4 composite ceramic matrix.

[0166] <Example 2>

[0167] Example 2 was prepared with a 5-component composition comprising 50 parts by weight of polysilazane, 10 parts by weight of hexagonal boron nitride, 20 parts by weight of octakis(3,3,3-trifluoropropyl)octasilsesquioxane, 12 parts by weight of diphenylsilanediol, and 8 parts by weight of 4,4′-bis(perfluorohexyl)benzophenone.

[0168] First, polysilazane was dissolved in a dibutyl ether solvent at a concentration of 20 wt%, then diphenylsilanediol was added and stirred at 60°C for 2 hours to induce a polysilazane-diphenylsilanediol crosslinking reaction.

[0169] Subsequently, hexagonal boron nitride powder (average particle size 2 μm) was dispersed using an ultrasonic disperser (40 kHz, 30 min), followed by the sequential addition of octakis(3,3,3-trifluoropropyl)octasilsesquioxane and 4,4′-bis(perfluorohexyl)benzophenone, and the mixture was stirred at room temperature for 1 hour to prepare a uniform 5-component coating solution.

[0170] The manufactured coating solution was applied to the outer surface of the second tube (142) by a spray coating method, with three applications and a total coating thickness of about 30 μm.

[0171] After coating, the surface treatment layer (142b) was completed by drying at room temperature for 30 minutes, then baking at 250°C for 1 hour, and subsequently inducing a photocrosslinking reaction of 4,4′-bis(perfluorohexyl)benzophenone by additionally performing ultraviolet irradiation (UV, 365 nm, 3 J / cm²).

[0172] <Comparative Example 1>

[0173] Comparative Example 1 is a fluorine-based water-repellent coating, prepared with a two-component composition comprising 70 parts by weight of polytetrafluoroethylene (PTFE) and 30 parts by weight of fluorinated acrylate.

[0174] First, a coating solution was prepared by adding fluorinated acrylate to a PTFE dispersion (water-based, solid content 60 wt%) and stirring at room temperature for 1 hour.

[0175] The manufactured coating solution was applied to the outer surface of the second tube (142) by a spray coating method, with a total coating thickness of approximately 30 μm.

[0176] After application, the surface treatment layer was completed by drying at room temperature for 30 minutes and then firing at 380°C for 30 minutes to form a PTFE coating layer.

[0177] <Comparative Example 2>

[0178] Comparative Example 2 is a chemical-resistant inorganic coating prepared with a two-component composition comprising 75 parts by weight of bisphenol A epoxy resin and 25 parts by weight of nano-SiO₂ (average particle size 20 nm).

[0179] Although epoxy-based coatings exhibit excellent chemical resistance and adhesion, they fail to form a ceramic matrix and are susceptible to cracking and peeling due to repetitive loading; therefore, they were selected as the subject for durability comparison in a repetitive pressure pulse environment according to the present invention.

[0180] First, a bisphenol A type epoxy resin was dissolved in a methyl ethyl ketone (MEK) solvent at a concentration of 30 wt%, and then nano SiO₂ was uniformly dispersed using an ultrasonic disperser (40 kHz, 30 min) to prepare a coating solution. A curing agent (4,4′-diaminodiphenylsulfone, DDS) was added in an equivalent ratio of 1:1 to the epoxy resin and stirred for 30 minutes, and then applied to the outer surface of the second tube (142) by a spray coating method, with a total coating thickness of approximately 30 μm.

[0181] After application, the surface treatment layer was completed by curing at 180°C for 2 hours.

[0182] [Experiment 1: Comparative Evaluation of Scale Adhesion Amount Under High-Speed ​​Air-Cleaning Fluid Mixing Flow Conditions]

[0183] This experiment was conducted in accordance with ASTM D4541 (Test of Coating Layer Adhesion Strength) and ASTM D3274 (Test of Coating Surface Contamination) to quantitatively evaluate the amount of scale adhesion to the coating surface in a high-speed flow environment.

[0184] First, three specimens of the second tubular body (142) with a surface treatment layer formed according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were prepared for each.

[0185] A supersaturated calcium carbonate (CaCO₃) solution was used as the test fluid and was prepared with a calcium ion (Ca^2+) concentration of 500 mg / L, a bicarbonate ion (HCO₃^-) concentration of 610 mg / L, and a pH of 8.2, with the Langelier Saturation Index (LSI) set to 1.8.

[0186] Here, LSI is an index that quantifies the tendency of calcium carbonate precipitation in an aqueous solution, and if LSI > 0, it indicates a tendency for scale formation, and the larger the value, the faster the rate of scale formation.

[0187] The test apparatus installed the specimen in a circulation pipe loop with an inner diameter of 25 mm and used a compressor (maximum discharge pressure 7 bar) to create an air-cleaning fluid mixed flow (air velocity 18 m / s, cleaning fluid velocity 2.3 m / s). The test temperature was maintained at 60°C using a constant temperature water bath (±0.5°C precision).

[0188] The test time was set to 72 hours. After the test was completed, the specimens were removed, washed three times with distilled water, and dried in a 105°C dryer for 2 hours. Then, the amount of scale adhesion (mg / cm²) on the specimen surface was measured using an electronic balance (Mettler Toledo XPE205) with a precision of 0.01 mg. The average of the measurements from three specimens was adopted as the final result.

[0189] Table 1 below shows the experimental results.

[0190] division furtherance Scale adhesion amount (mg / cm²) Example 1 Polysilazane + h-BN 2.14 Example 2 5-component composite coating 1.37 Comparative Example 1 PTFE + Fluoroacrylate 3.86 Comparative Example 2 Epoxy resin + nano SiO2 5.43

[0191] Referring to Table 1, the scale adhesion amount of Example 2 was the lowest at 1.37 mg / cm², and Example 1 showed a significantly lower adhesion amount of 2.14 mg / cm² compared to Comparative Example 1 (3.86 mg / cm²) and Comparative Example 2 (5.43 mg / cm²).

[0192] In the case of Comparative Example 1, despite the water-repellent properties of the PTFE series, under high-speed air-cleaning liquid mixed flow conditions, scale was concentrated on the fine irregularities on the surface of the coating layer, resulting in an adhesion amount approximately 1.8 times higher than that of Example 1.

[0193] Comparative Example 2 is judged to have shown the highest adhesion amount because multiple nucleation sites of calcium carbonate crystals were formed due to the hydrophilic characteristics of the epoxy matrix.

[0194] Example 2 is judged to be the result of effectively suppressing the adhesion of calcium carbonate crystals by forming an ultra-low surface energy layer through the fluorine groups of octakis(3,3,3-trifluoropropyl)octasilsesquioxane and 4,4′-bis(perfluorohexyl)benzophenone being oriented at the outermost edge of the coating layer.

[0195] [Experiment 2: Evaluation of Coating Layer Cracking and Delamination Resistance in Repetitive Pressure Pulsation Environments]

[0196] This experiment was conducted in accordance with ISO 4624 (Coating Layer Adhesion Test Method) and ASTM D1640 (Coating Layer Drying and Curing Characteristics Evaluation Method) to quantitatively evaluate the cracking and peeling resistance of the coating layer in a cyclic pressure pulsation environment.

[0197] First, three specimens of the second tubular body (142) with a surface treatment layer formed according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were prepared for each.

[0198] The pressure pulsation test device was configured to repeatedly apply pressure between 0.5 bar and 6 bar at a cycle of 1 Hz using a hydraulic servo actuator (maximum pressure 10 bar, pressure control precision ±0.05 bar).

[0199] Here, 1 Hz means a pressure rise-fall cycle once per second, which is set to a harsher condition than the intermittent injection cycle (3 to 10 seconds) of the controller (200).

[0200] The test temperature was maintained at 60°C using a constant temperature water bath, and the test fluid used was the same supersaturated calcium carbonate solution (LSI 1.8) as in Experiment 1.

[0201] The total number of iterations was set to 10,000 cycles, and specimens were removed at intervals of 2,500 cycles to observe the surface of the coating layer using an optical microscope (magnification 200×, Olympus BX53M) and the crack occurrence area percentage (%) was calculated using ImageJ image analysis software.

[0202] Here, the crack area ratio refers to the percentage of the cracked area relative to the total coating area. After completing 10,000 cycles, a pull-off test in accordance with ISO 4624 was performed to measure the adhesion strength (MPa) of the coating layer, and the retention rate (%) of the remaining adhesion strength relative to the initial adhesion strength was calculated.

[0203] The following Table 2 shows the experimental results.

[0204] division Crack area percentage (%) after 10,000 cycles Initial bond strength (MPa) Remaining adhesion strength retention rate (%) Example 1 2.8 18.4 92.6 Example 2 1.4 19.1 95.3 Comparative Example 1 8.6 9.3 74.2 Comparative Example 2 12.3 14.7 71.8

[0205] As can be seen from Table 2, the crack occurrence area rate after 10,000 cycles was lowest in Example 2 at 1.4%, and Example 1 at 2.8%, which was significantly lower than Comparative Example 1 (8.6%) and Comparative Example 2 (12.3%).

[0206] In terms of the retention rate of residual adhesion strength, Example 2 maintained a high level at 95.3% and Example 1 at 92.6%, whereas Comparative Example 1 was relatively lower at 74.2% and Comparative Example 2 at 71.8%.

[0207] In the case of Comparative Example 1, the PTFE-based coating had a low initial adhesion strength (9.3 MPa), so it was determined that interfacial delamination between the coating layer and the substrate occurred early in a repeated pressure pulsation environment.

[0208] Comparative Example 2 is judged to have gradually progressed cracks as plastic deformation due to repeated loading accumulated because the epoxy matrix failed to form a ceramic structure.

[0209] On the other hand, it is determined that Example 2 achieved excellent crack resistance and adhesion strength retention rate simultaneously in a repeated pressure pulsation environment through the combined action of the polysilazane ceramic matrix, the inhibition of interlayer crack propagation by hexagonal boron nitride, the flexibility reinforcement of octakis(3,3,3-trifluoropropyl)octasilsesquioxane, and the improvement of crosslinking density by diphenylsilanediol.

[0210] [Experiment 3: Evaluation of Nucleation Delay Time and Crystal Growth Inhibition Properties under Dissolved Inorganic Salt Conditions]

[0211] This experiment was conducted in accordance with ASTM D2688 (Method for Evaluating Scale Inhibition Performance in Pipes) to quantitatively evaluate the nucleation delay time and crystal growth inhibition characteristics of calcium carbonate crystals on a coating surface under dissolved inorganic salt conditions.

[0212] The experimental method is as follows.

[0213] Three specimens of the second tubular body (142) with a surface treatment layer formed according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were prepared for each.

[0214] The test fluid used was the same calcium carbonate supersaturated solution as in Experiment 1 (Ca^2+ concentration 500 mg / L, HCO_3^- concentration 610 mg / L, pH 8.2, LSI 1.8).

[0215] The test apparatus fixed the specimen vertically in a 250 mL glass cell and filled it with the test fluid, then maintained the temperature at 60°C using a constant temperature water bath (±0.5°C precision) and stirred it constantly with a magnetic stirrer (300 rpm).

[0216] The nucleation delay time was defined as the elapsed time (in minutes) from the start of the test until the first calcium carbonate crystal nucleus was visually observed on the coating surface, and was measured by observing the surface at 30-minute intervals using an optical microscope (magnification 100×, Olympus BX53M).

[0217] Crystal growth inhibition characteristics were evaluated by calculating the crystal coverage area ratio (%) per unit area of ​​the coating surface using ImageJ image analysis software at 24 hours after the start of the test.

[0218] Here, the crystal coverage area ratio refers to the percentage of the area covered by calcium carbonate crystals relative to the total coating area. The average of the measurements from three specimens was adopted as the final result.

[0219] Table 3 below shows the experimental results.

[0220] division Nucleation latency (minutes) Determined coverage area percentage (%) after 24 hours Example 1 186 12.4 Example 2 274 7.8 Comparative Example 1 112 21.3 Comparative Example 2 64 29.4

[0221] Referring to Table 3, the nucleation delay time was longest in Example 2 at 274 minutes, while Example 1 showed a significantly longer delay time of 186 minutes compared to Comparative Example 1 (112 minutes) and Comparative Example 2 (64 minutes). In terms of crystal coverage area ratio after 24 hours, Example 2 was the lowest at 7.8%, while Example 1 maintained a lower level of 12.4% compared to Comparative Example 1 (21.3%) and Comparative Example 2 (29.4%).

[0222] In the case of Comparative Example 1, the nucleation delay time was longer and the crystal coating area ratio was lower compared to Comparative Example 2 due to the water-repellent properties of the PTFE series; however, it is determined that the inhibition effect is inferior compared to the example because crystal nuclei are formed around the fine defects on the surface of the coating layer.

[0223] Comparative Example 2 is judged to have the shortest nucleation delay time and the highest crystal coverage area ratio due to the hydrophilic surface characteristics of the epoxy matrix.

[0224] On the other hand, Example 2 is judged to be the result of the ultra-low surface energy layer formed by the fluorine groups of octakis(3,3,3-trifluoropropyl)octasilsesquioxane and 4,4′-bis(perfluorohexyl)benzophenone raising the interfacial energy barrier required for the nucleation of calcium carbonate crystals, thereby delaying nucleation itself and suppressing the crystal growth rate even after nucleation.

[0225] When combining the results of Experiments 1 to 3 above, it was confirmed that the surface treatment layer (142b) of the present invention exhibits significantly superior performance compared to simple fluorine-based coatings and epoxy-based coatings in all of the following: inhibition of scale adhesion in a high-speed air-washing liquid mixed flow environment, resistance to cracking and peeling in a repeated pressure pulsation environment, and characteristics of nucleation delay and crystal growth inhibition in dissolved inorganic salt conditions.

[0226] In particular, Example 2, which is a composite composition of five components, showed consistently improved results in all evaluation items compared to Example 1, which is a composition of two components, thereby proving that the five-component composition of the present invention exhibits a composite synergistic effect that exceeds simple summation.

[0227] As explained above, the configuration and operation of the backflow prevention pipe cleaning device using an air guide tube according to the present invention have been described in the above description and drawings; however, this is merely an example, and the concept of the present invention is not limited to the above description and drawings. It is understood that various changes and modifications are possible within the scope of the technical concept of the present invention. Explanation of the symbols

[0228] 10: Piping 20: Pump 21: Check valve 30: Compressor 100: Air jet assembly 110: Air connection part 120: Air guide tube 140: Extension 141: First pipe body 141a: Connecting hole 142: Second pipe body 142a: Inlet port 142b: Surface treatment layer 200: Controller

Claims

Claim 1 A backflow prevention pipe cleaning device using an air guide tube, comprising: a pump for circulating cleaning fluid within a pipe; a compressor for supplying compressed air; and an air jet assembly including an air connection part formed in communication with the pipe in a direction perpendicular to the pipe and connected to the compressor via a solenoid valve, and an air guide tube inserted and fixed inside the air connection part, wherein the inlet end receives the compressed air in a direction perpendicular to the pipe and the outlet end is bent and formed to face the direction of flow of cleaning fluid within the pipe, thereby discharging the compressed air in the direction of flow of cleaning fluid within the pipe; wherein the air guide tube further comprises an extension part in which the outer diameter is extended tapered outwardly from the outlet end and extended toward the direction of flow of cleaning fluid, wherein the inlet end is formed with an outer diameter corresponding to the inner diameter of the air connection part and is inserted and fixed in close contact with the air connection part, and the outer diameter is tapered such that it becomes smaller from the bending starting point toward the outlet end. Claim 2 In claim 1, the backflow prevention type pipe cleaning device further comprises a controller that periodically opens and closes the solenoid valve during the circulation operation of the pump to intermittently spray compressed air. Claim 3 delete Claim 4 delete Claim 5 A backflow prevention pipe cleaning device according to claim 1, wherein the expansion portion is formed as a double pipe structure comprising a first pipe body extending outwardly to the outlet side end with a tapered outer diameter and extending toward the direction of flow of the cleaning liquid, and a second pipe body arranged to surround the outer surface of the first pipe body at a certain interval, wherein a plurality of communication holes are formed penetratingly through the first pipe body at a certain interval along the length direction of the expansion portion, and a plurality of inlet holes are formed penetratingly through the second pipe body at a certain interval along the length direction of the expansion portion for the cleaning liquid in the pipe to flow into the space between the first pipe body and the second pipe body. Claim 6 A backflow prevention pipe cleaning device according to claim 5, characterized in that the outer surface of the second pipe body is coated with a surface treatment layer comprising polysilazane and hexagonal boron nitride. Claim 7 A backflow prevention pipe cleaning device according to claim 6, wherein the surface treatment layer comprises, based on 100 parts by weight of the surface treatment layer, 45 to 55 parts by weight of polysilazane, 5 to 15 parts by weight of hexagonal boron nitride, 15 to 25 parts by weight of octakis(3,3,3-trifluoropropyl)octasilsesquioxane, 10 to 15 parts by weight of diphenylsilanediol, and 10 to 20 parts by weight of 4,4′-bis(perfluorohexyl)benzophenone.

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