Seawater film forming device and method for marine copper-nickel alloy heat exchange tube

Abstract

The invention relates to the field of metal material corrosion and protection, and provides a seawater film-forming device and method for a marine copper-nickel alloy heat exchange tube, and the seawater film-forming method comprises the following steps: S1, preparing the seawater film-forming device; s2, calculating the total flow Q of the pipeline system: Q = n * A * v * 3600 / 1000000; s3, determining the flow of the sea water pump, wherein the flow of the sea water pump is equal to 1.2-1.3 Q; s4, building a seawater film forming device; s5, setting the flow velocity of a pipeline, namely debugging the water by using a starter to ensure that the flow velocity in the heat exchange pipe reaches 1.0-3.0 m / s; and S6, seawater film forming time: forming a film after the heat exchange tube is continuously scoured by seawater for 20-60 days. According to the seawater film forming method for the marine copper-nickel alloy heat exchange tube, the seawater film forming method is easy to operate and convenient to implement; the film forming effect is good; no chemical agent is used, so that the method is environment-friendly.

Description

Technical Field

[0001] This invention relates to the field of corrosion and protection of metallic materials, and more specifically, to a seawater film formation device and method for marine copper-nickel alloy heat exchange tubes. Background Technology

[0002] Copper-nickel alloys exhibit excellent resistance to seawater corrosion and antifouling properties, while also possessing superior cold and hot working and welding performance. They are commonly used piping materials for condensers and heat exchangers in marine engine units both domestically and internationally. Currently, commonly used heat exchange tube specifications for marine heat exchange equipment include Ф10×1mm, Ф14×1mm, Ф16×1.25mm, Ф16×2.0mm, Ф19×2.2mm, and Ф35×2.5mm, with lengths ranging from 500mm to 3000mm. Although copper-nickel alloys have been used as heat exchange tubes for decades, early corrosion and leakage problems still occur frequently during use. Research indicates that the seawater corrosion resistance of copper-nickel alloys depends on the dense protective film (also called corrosion product film or passivation film) formed on the surface. The formation and evolution mechanism of the protective film on the surface of B30 copper-nickel alloy is influenced by a variety of factors, including the material itself and the operating environment. Material factors include chemical composition, microstructure, surface condition, and residual stress, while operating environment factors include seawater flow rate, dissolved oxygen concentration, pH value, salinity, and pollutant sulfides.

[0003] Heat exchangers used on ships typically use seawater as the cooling medium to cool and condense the received exhaust steam, condensate, and drain water before sending it to the condensate system. Additionally, lubricating oil coolers in the power system use seawater to cool the lubricating oil, reducing its temperature before returning it to the oil tank. For heat exchangers and coolers, the heat exchange tubes are the weakest link in terms of corrosion resistance within the entire heat exchange system. Due to differences in the installation sequence of various systems, equipment, and components during ship construction, and variations in testing items during the commissioning phase, heat exchangers often struggle to maintain continuous dynamic operation under seawater conditions after being installed on board and exposed to seawater. This can easily lead to poor initial film formation quality in the copper-nickel alloy heat exchange tubes. Consequently, early and abnormally rapid corrosion and leakage problems occur after the ship enters the operational phase.

[0004] To improve the corrosion resistance of copper-nickel alloy heat exchange tubes, the currently widely adopted method is to pre-passivate the heat exchange tubes to form a film. This mainly involves immersing the heat exchange tubes in chemical solutions such as ferrous sulfate, potassium persulfate, and benzotriazole for a certain period of time, causing a chemical reaction on the tube surface to form a film. However, this method has problems such as complex film formation process, unstable film quality, and environmental pollution from industrial wastewater.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a seawater film-forming device and method for marine copper-nickel alloy heat exchange tubes, in order to solve the problems of complex film-forming processes, unstable film quality, and environmental pollution caused by the production of industrial wastewater in the prior art, which uses chemical agents to cause chemical reactions on the surface of the tubes to form a film.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A method for forming a seawater film on a marine copper-nickel alloy heat exchanger tube, the method comprising the following steps:

[0009] S1. Preparation of seawater film forming device: The seawater film forming device includes a seawater pump, filter, solenoid valve, flow meter and heat exchange assembly. The heat exchange assembly includes multiple heat exchange units, and each heat exchange unit includes a heat exchange tube and two quick connectors.

[0010] S2. Calculation of the total flow rate Q of the piping system: The total flow rate Q of the piping system is calculated according to the following formula:

[0011] Q = n × A × v × 3600 / 1000000

[0012] Where: Q is the total flow rate of the pipeline system (unit: m³ / s). 3 / h), n is the number of heat exchange tubes, and A is the cross-sectional area inside the heat exchange tube (unit: mm). 2 v is the flow velocity inside the heat exchange tube (unit: m / s);

[0013] S3. Determine the seawater pump flow rate: The seawater pump flow rate range is 1.2Q~1.3Q. Select the seawater pump according to the seawater pump flow rate range.

[0014] S4. Seawater film forming device setup: Seawater enters the seawater pump through the water intake pipe. The seawater pump is connected in sequence to the filter, solenoid valve, flow meter, and heat exchange assembly. The seawater pump, filter, solenoid valve, flow meter, and two adjacent heat exchange assemblies are connected by connecting pipes. The other end of the heat exchange assembly is connected to the drain pipe. The quick connector is installed at both ends of the heat exchange pipe.

[0015] S5. Pipeline flow rate setting: Turn on the running water to test and ensure that the flow rate in the heat exchange tube reaches 1.0 to 3.0 m / s;

[0016] S6. Seawater film formation time: The heat exchange tubes form a film after being continuously flushed with seawater for 20 to 60 days.

[0017] Furthermore, after the film is formed on the heat exchange tube, it is determined whether the inner wall surface of the heat exchange tube exhibits a uniform yellowish-brown or brownish-red color, and whether the corrosion current density under the potentiodynamic polarization curve measured in seawater is not greater than 1 uA / cm. 2 And whether the low-frequency impedance modulus is not less than 105 Ω·cm 2 If so, it indicates that the heat exchanger tube film layer is of good quality.

[0018] Furthermore, if the heat exchanger tube film layer is of good quality, the mud and sand inside each heat exchanger tube should be rinsed with tap water, then quickly dried with compressed air, and then caps should be put on both ends of each heat exchanger tube. Finally, the tubes should be separated and protected before being sealed and stored as a whole.

[0019] Furthermore, the outlet of the drain pipe is more than 10 meters away from the inlet of the water intake pipe.

[0020] Furthermore, the water intake of the water pipe is located more than 1 meter below the seabed.

[0021] Furthermore, the heat exchange tube is made of a copper-nickel alloy.

[0022] Furthermore, the heat exchange tube has a diameter of Φ10~Φ35mm and a wall thickness of 1~2.5mm.

[0023] Furthermore, the heat exchange tubes form a film after being continuously flushed with seawater for 20 to 30 days.

[0024] In a second aspect, the present invention provides a seawater film-forming device for a marine copper-nickel alloy heat exchanger tube. The seawater film-forming device uses any one of the seawater film-forming methods for a marine copper-nickel alloy heat exchanger tube. The seawater film-forming device includes a seawater pump, a filter, a solenoid valve, a flow meter, and a heat exchange assembly. The inlet pipe is sequentially connected to the seawater pump, the filter, the solenoid valve, the flow meter, the heat exchange assembly, and the outlet pipe.

[0025] Compared with the prior art, the seawater film formation device and method for marine copper-nickel alloy heat exchange tubes described in this invention have the following advantages:

[0026] 1. The present invention discloses a seawater film formation method for marine copper-nickel alloy heat exchange tubes. The seawater film formation method is simple to operate and easy to implement; the film formation effect is good and the film quality is stable; no chemical agents are used, which is environmentally friendly.

[0027] 2. The seawater film forming device for marine copper-nickel alloy heat exchange tubes described in this invention has a simple composition, is easy to assemble, and can be reused.

[0028] 3. The seawater film formation method and apparatus for marine copper-nickel alloy heat exchange tubes described in this invention are interconnected and work together to achieve seawater film formation on copper-nickel alloy heat exchange tubes with diameters of Φ10~Φ35mm and wall thicknesses of 1~2.5mm before equipment installation. This improves their resistance to seawater corrosion, reduces the risk of corrosion leakage in the early stages of use, enhances equipment reliability, and thus extends the service life of the equipment. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a seawater film-forming device for a marine copper-nickel alloy heat exchanger tube according to an embodiment of the present invention.

[0030] Figure 2 This is a topographic image of the inner wall of a heat exchange tube obtained using a seawater film formation method for a marine copper-nickel alloy heat exchange tube as described in Embodiment 1 of the present invention.

[0031] Figure 3 This is a topographic image of the inner wall of a heat exchange tube obtained using a seawater film formation method for a marine copper-nickel alloy heat exchange tube as described in Embodiment 2 of the present invention.

[0032] Figure 4 This is a topographic image of the inner wall of a heat exchange tube obtained using a seawater film formation method for a marine copper-nickel alloy heat exchange tube as described in Embodiment 3 of the present invention.

[0033] Figure 5 This is a topographic view of the inner wall of the heat exchange tube described in Comparative Example 1 of the present invention.

[0034] Figure 6 This is a topographic image of the inner wall of a heat exchanger tube obtained using the seawater film formation method for a marine copper-nickel alloy heat exchanger tube as described in Comparative Example 2 of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Seawater pump; 2. Filter; 3. Connecting pipe; 4. Solenoid valve; 5. Flow meter; 6. Quick connector; 7. Heat exchange tube; 8. Heat exchange assembly; 80. Heat exchange unit; 9. Water intake pipe; 10. Drain pipe. Detailed Implementation

[0037] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0038] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0039] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Existing technologies that use chemical agents to form a film on the surface of pipes have problems such as complex film-forming processes, unstable film quality, and environmental pollution from industrial wastewater.

[0043] To address the aforementioned technical problems, the applicant proposes a seawater film formation method for marine copper-nickel alloy heat exchange tubes, the seawater film formation method comprising the following steps:

[0044] S1. Preparation of seawater film-forming equipment: (e.g.) Figure 1 As shown, the seawater film-forming device includes a seawater pump 1, a filter 2, a solenoid valve 4, a flow meter 5, and a heat exchange assembly 8. The heat exchange assembly 8 includes multiple heat exchange units 80, and each heat exchange unit 80 includes a heat exchange tube 7 and two quick connectors 6.

[0045] S2. Calculation of the total flow rate Q of the piping system: The total flow rate Q of the piping system is calculated according to the following formula:

[0046] Q = n × A × v × 3600 / 1000000

[0047] Where: Q is the total flow rate of the pipeline system (unit: m³ / s). 3 / h), n is the number of heat exchange units 80, and A is the cross-sectional area inside the heat exchange tube 7 (unit: mm). 2 v is the flow velocity inside heat exchange tube 7 (unit: m / s);

[0048] S3. Determine the flow rate of the seawater pump: The flow rate range of seawater pump 1 is 1.2Q~1.3Q. Select seawater pump 1 according to the flow rate range of seawater pump 1.

[0049] S4. Construction of seawater film-forming device: such as... Figure 1 As shown, seawater enters the seawater pump 1 through the water intake pipe 9. The seawater pump 1 is connected in sequence to the filter 2, solenoid valve 4, flow meter 5, and heat exchange assembly 8. The seawater pump 1, filter 2, solenoid valve 4, flow meter 5 and two adjacent heat exchange assemblies 8 are connected by connecting pipes 3. The other end of the heat exchange assembly 8 is connected to the drain pipe 10. The quick connector 6 is installed at both ends of the heat exchange tube 7. The quick connector 6 can connect the heat exchange tube 7 conveniently and without damage, avoiding scratches on the surface film of the heat exchange tube 7 during disassembly and assembly.

[0050] S5. Pipeline flow rate setting: Start the machine water for debugging. Adjust the speed of seawater pump 1 and the valve opening of solenoid valve 4, and observe the flow meter 5 to ensure that the flow rate in heat exchange tube 7 reaches 1.0~3.0m / s.

[0051] S6. Seawater film formation time: The heat exchange tube 7 forms a film after being continuously flushed with seawater for 20 to 60 days.

[0052] The present invention discloses a seawater film formation method for marine copper-nickel alloy heat exchange tubes. This method utilizes seawater itself to physically scour the inner wall of the copper-nickel alloy heat exchange tube, forming a stable and corrosion-resistant protective film. It has the following advantages:

[0053] I. Seawater film formation method is simple to operate and easy to implement.

[0054] II. The film-forming effect is good and the film quality is stable.

[0055] Third, it does not use chemical agents and completely eliminates chemical wastewater pollution, making it environmentally friendly;

[0056] IV. Significantly improves the low-frequency impedance modulus of the heat exchanger tube, with a low-frequency impedance modulus ≥10. 5 Ω·cm 2 The corrosion current density of the heat exchange tubes was reduced to ≤1uA / cm². 2 This not only improves the corrosion resistance of copper-nickel alloy heat exchange tubes, but also enhances the long-term protective stability of the film layer.

[0057] Specifically, the cross-sectional area A inside heat exchanger tube 7 is calculated using the following formula:

[0058] A = π × d 2 / 4

[0059] d=D-2t

[0060] Where: d is the inner diameter of heat exchange tube 7 (in mm), D is the outer diameter of heat exchange tube 7 (in mm), and t is the wall thickness of heat exchange tube 7 (in mm).

[0061] Specifically, after the film is formed on the heat exchange tube 7, it is determined whether the inner wall surface of the heat exchange tube 7 exhibits a uniform yellowish-brown or brownish-red color, and whether the corrosion current density under the potentiodynamic polarization curve measured in seawater is not greater than 1 uA / cm. 2 And whether the low-frequency impedance modulus is not less than 10 5 Ω·cm 2 If so, it indicates that the film layer of heat exchange tube 7 is of good quality.

[0062] Specifically, if the film layer of heat exchange tube 7 is of good quality, the mud and sand inside each heat exchange tube 7 should be rinsed with tap water, then quickly dried with compressed air, and then caps should be put on both ends of each heat exchange tube 7. Finally, the tubes should be separated and protected one by one before being sealed and stored as a whole.

[0063] Specifically, the outlet of the drain pipe 10 is more than 10 meters away from the inlet of the water intake pipe 9.

[0064] This setup prevents the discharged seawater from being immediately drawn back into the pipeline.

[0065] Specifically, the inlet of water intake pipe 9 is located more than 1 meter above the seabed.

[0066] This design prevents the intake of foreign objects such as seabed mud and shells, which could cause blockages in the pipes.

[0067] Specifically, the heat exchange tube is made of a copper-nickel alloy.

[0068] Specifically, the heat exchange tube 7 has a diameter of Φ10~Φ35mm and a wall thickness of 1~2.5mm.

[0069] Preferably, the heat exchange tube 7 forms a film after being continuously flushed with seawater for 20 to 30 days.

[0070] Specifically, the connecting pipe 3 is made of PE.

[0071] It should be noted that the seawater used in this application meets the Class I or Class II seawater quality requirements stipulated in GB3097-1997 "Seawater Quality Standard".

[0072] In a second aspect, the present invention provides a seawater film-forming device for a marine copper-nickel alloy heat exchanger tube. The seawater film-forming device uses any one of the seawater film-forming methods for a marine copper-nickel alloy heat exchanger tube. The seawater film-forming device includes a seawater pump 1, a filter 2, a solenoid valve 4, a flow meter 5, and a heat exchange assembly 8. The seawater pump 1 is sequentially connected to the filter 2, the solenoid valve 4, the flow meter 5, and the heat exchange assembly 8.

[0073] In summary, this technology provides a green, efficient, and reliable pretreatment solution for marine copper-nickel alloy heat exchange tubes. Through precise hydrodynamic calculations and system design, it utilizes natural seawater at specific flow rates and times to generate a high-quality protective film on the inner wall of the heat exchange tube in situ, thereby eliminating complex chemical treatment processes and completely eliminating chemical wastewater pollution. It has significant application value in the fields of shipbuilding and marine engineering.

[0074] Example 1

[0075] This embodiment proposes a seawater film formation method for marine copper-nickel alloy heat exchange tubes. The heat exchange tube is made of BFe30-1-1 copper-nickel alloy, with a diameter of Φ10mm, a wall thickness of 1.0mm, and a length of 1000mm. The number of heat exchange tubes 7, n, is 135, and the flow velocity v inside the heat exchange tube 7 is 2.5m / s.

[0076] In this embodiment, the cross-sectional area A inside the heat exchange tube 7 is calculated to be π × (10 - 2 × 1). 2 / 4=50.27mm 2 .

[0077] The seawater film formation method includes the following steps:

[0078] S1. Preparation of seawater film forming device: The seawater film forming device includes a seawater pump 1, a filter 2, a solenoid valve 4, a flow meter 5, and a heat exchange assembly 8. The heat exchange assembly 8 includes multiple heat exchange units 80, and each heat exchange unit 80 includes a heat exchange tube 7 and two quick connectors 6.

[0079] S2. Calculation of the total flow rate Q of the piping system: The total flow rate Q of the piping system is calculated according to the following formula:

[0080] Q = n × A × v × 3600 / 1000000

[0081] Where: Q is the total flow rate of the pipeline system (unit: m³ / s). 3 / h), n is the number of heat exchange units 80, and A is the cross-sectional area inside the heat exchange tube 7 (unit: mm). 2 v is the flow velocity inside heat exchange tube 7 (unit: m / s);

[0082] S3. Determine the flow rate of the seawater pump: The flow rate range of seawater pump 1 is 1.2Q~1.3Q. Select seawater pump 1 according to the flow rate range of seawater pump 1.

[0083] S4. Seawater film forming device setup: Seawater enters seawater pump 1 through water intake pipe 9. Seawater pump 1 is connected in sequence to filter 2, solenoid valve 4, flow meter 5, and heat exchange component 8. The two adjacent components of seawater pump 1, filter 2, solenoid valve 4, flow meter 5 and heat exchange component 8 are connected by connecting pipe 3. The other end of heat exchange component 8 is connected to drain pipe 10. Quick connector 6 is installed at both ends of heat exchange pipe 7.

[0084] S5. Pipeline flow rate setting: Start the machine water for debugging. Adjust the speed of seawater pump 1 and the valve opening of solenoid valve 4, and observe the flow meter 5 to ensure that the flow rate in heat exchange tube 7 reaches 2.5m / s.

[0085] S6. Seawater film formation time: The heat exchange tube 7 forms a film after being continuously flushed with seawater for 30 days.

[0086] Specifically, the cross-sectional area A inside heat exchanger tube 7 is calculated using the following formula:

[0087] A = π × d 2 / 4

[0088] d=D-2t

[0089] Where: d is the inner diameter of heat exchange tube 7 (in mm), D is the outer diameter of heat exchange tube 7 (in mm), and t is the wall thickness of heat exchange tube 7 (in mm).

[0090] Specifically, after the film is formed on the heat exchange tube 7, performance tests are conducted. The tests involve manually determining whether the inner wall surface of the heat exchange tube 7 exhibits a uniform yellowish-brown or brownish-red color, and whether the corrosion current density under the potentiodynamic polarization curve measured in seawater is no greater than 1 uA / cm². 2 And whether the low-frequency impedance modulus is not less than 10 5 Ω·cm 2 If so, it indicates that the film layer of heat exchange tube 7 is of good quality.

[0091] Specifically, if the membrane quality of heat exchange tube 7 is good, the mud and sand inside each heat exchange tube 7 should be rinsed with tap water, then quickly dried with compressed air, and then caps should be put on both ends of each heat exchange tube 7. Finally, after protecting each tube individually, they should be placed in a wooden box for overall sealing and preservation.

[0092] Specifically, the outlet of the drain pipe 10 is 15 meters away from the inlet of the water intake pipe 9.

[0093] Specifically, the inlet of water intake pipe 9 is located 1.5 meters from the seabed.

[0094] Specifically, the heat exchange component 8 is arranged indoors, which can prevent it from getting wet in the rain.

[0095] In this embodiment, the total flow rate of the pipeline system is calculated to be Q = n × A × v × 3600 / 1000000 = 135 × 50.27 × 2.5 × 3600 / 1000000 = 61.08 m³. 3 / h.

[0096] In this embodiment, 1.2Q = 73m 3 / h, 1.3Q=79 m 3 / h, seawater pump 1 flow range = 1.2Q~1.3Q = 73~79m 3 / h, based on the flow range of seawater pump 1, a commercially available stainless steel seawater pump with a power of 2.2kw and a maximum flow rate of 80 m³ / h was selected. 3 / h, head 20 meters.

[0097] Specifically, the outlet of the drain pipe 10 is 15 meters away from the inlet of the water intake pipe 9.

[0098] Specifically, the inlet of water intake pipe 9 is located 1.5 meters from the seabed.

[0099] Specifically, the heat exchange tube 7 forms a film after being continuously flushed with seawater for 30 days.

[0100] It should be noted that the seawater used in this embodiment meets the Class I seawater quality requirements stipulated in GB3097-1997 "Seawater Quality Standard".

[0101] In a second aspect of this embodiment, a seawater film-forming device for a marine copper-nickel alloy heat exchanger tube is provided. The seawater film-forming device uses any one of the seawater film-forming methods for a marine copper-nickel alloy heat exchanger tube. The seawater film-forming device includes a seawater pump 1, a filter 2, a solenoid valve 4, a flow meter 5, and a heat exchange component 8. The seawater pump 1 is sequentially connected to the filter 2, the solenoid valve 4, the flow meter 5, and the heat exchange component 8.

[0102] Example 2

[0103] In this embodiment, unlike in Embodiment 1, the heat exchange tube 7 has a diameter of Ф16mm, a wall thickness of 1.25mm, and a length of 1800mm. The number of heat exchange tubes 7, n, is 150, and the flow velocity v inside the heat exchange tube 7 is 1.2m / s.

[0104] In this embodiment, the cross-sectional area A inside the heat exchange tube 7 is calculated to be π × (16 - 2 × 1.25). 2 / 4 = 143.14 mm 2 .

[0105] In this embodiment, the total flow rate of the pipeline system is calculated to be Q = n × A × v × 3600 / 1000000 = 150 × 143.14 × 1.2 × 3600 / 1000000 = 92.75 m³. 3 / h.

[0106] In this embodiment, 1.2Q = 111m 3 / h, 1.3Q=120m 3 / h, seawater pump 1 flow range = 1.2Q~1.3Q = 111~120m 3 / h, based on the flow range of seawater pump 1, a commercially available stainless steel seawater pump with a power of 4kw and a maximum flow rate of 120 m³ / h was selected. 3 / h, head 22 meters.

[0107] Specifically, the outlet of the drain pipe 10 is 20 meters away from the inlet of the water intake pipe 9.

[0108] Specifically, the inlet of water intake pipe 9 is located 1.2 meters from the seabed.

[0109] Specifically, the heat exchange tube 7 forms a film after being continuously flushed with seawater for 20 days.

[0110] Example 3

[0111] In this embodiment, unlike Embodiment 1, the heat exchange tube 7 is made of BFe10-1-1 copper-nickel alloy, has a diameter of Ф32mm, a wall thickness of 2.5mm, and a length of 1200mm. The number of heat exchange tubes 7, n, is 30, and the flow velocity v inside the heat exchange tube 7 is 2.0m / s.

[0112] In this embodiment, the cross-sectional area A inside the heat exchange tube 7 is calculated to be π × (32 - 2 × 2.5). 2 / 4=572.56 mm 2 .

[0113] In this embodiment, the total flow rate of the pipeline system is calculated to be Q = n × A × v × 3600 / 1000000 = 30 × 572.56 × 2.0 × 3600 / 1000000 = 123.67 m³. 3 / h.

[0114] In this embodiment, 1.2Q = 148m 3 / h, 1.3Q=161m 3 / h, seawater pump 1 flow range = 1.2~1.3Q = 148~161m 3 / h, based on the flow range of seawater pump 1, a commercially available stainless steel seawater pump with a power of 7.5kw and a maximum flow rate of 155m³ / h was selected. 3 / h, head 30 meters.

[0115] Comparative Example 1

[0116] Unlike Example 2, no seawater film-forming method was used, and no treatment was performed.

[0117] Comparative Example 2

[0118] Unlike Example 2, the seawater film-forming method was not used. Instead, natural seawater was injected into the heat exchange tube 7 and then sealed at both ends, allowing it to stand still for 20 days.

[0119] Performance testing:

[0120] 1. The morphology of the film layer on the inner wall of the heat exchange tube obtained by the seawater film formation method for marine copper-nickel alloy heat exchange tubes described in Example 1 was observed and photographed using a Welling PXLM645DB handheld portable industrial video endoscope. The results are as follows: Figure 2 As shown; the morphology of the film layer on the inner wall of the heat exchange tube obtained by the seawater film formation method for marine copper-nickel alloy heat exchange tubes described in Example 2 was observed and photographed using a Welling PXLM645DB handheld portable industrial video endoscope, and the results are as follows. Figure 3 As shown; the morphology of the film layer on the inner wall of the heat exchange tube obtained by the seawater film formation method for marine copper-nickel alloy heat exchange tubes described in Example 3 was observed and photographed using a Welling PXLM645DB handheld portable industrial video endoscope, and the results are as follows. Figure 4 As shown; the morphology of the film layer on the inner wall of the marine copper-nickel alloy heat exchange tube described in Comparative Example 1 was observed and photographed using a Welling PXLM645DB handheld portable industrial video endoscope, and the results are as follows. Figure 5 As shown; the morphology of the film layer on the inner wall of the heat exchange tube obtained by the seawater film formation method of the marine copper-nickel alloy heat exchange tube described in Comparative Example 2 was observed and photographed using a Welling PXLM645DB handheld portable industrial video endoscope, and the results are as follows. Figure 6 As shown.

[0121] 2. Samples were cut from the heat exchange tubes obtained using the seawater film formation method for marine copper-nickel alloy heat exchange tubes described in Examples 1-3 and Comparative Examples 1-2. Electrochemical tests were performed on the seawater-formed heat exchange tube samples using a DH7006B electrochemical workstation, referring to GB / T24196-2009 "Electrochemical Test Methods for Corrosion of Metals and Alloys - Guidelines for Potentiostatic and Potentiodynamic Polarization Measurement". A three-electrode system was used, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the sample as the working electrode. The samples were encapsulated with epoxy resin, leaving only a 10 mm × 10 mm exposed area. The test results are shown in Table 1.

[0122] Table 1 Performance Tests

[0123]

[0124] Depend on Figures 2-4 As shown, after the heat exchange tube 7 obtained by the seawater film formation method of marine copper-nickel alloy heat exchange tubes described in Examples 1-3 is formed, a uniform brown protective film layer appears on the inner wall surface of the heat exchange tube 7. No obvious corrosion spots were found, but local sediment was deposited during the seawater scouring process.

[0125] Depend on Figure 5 and Figure 6 It can be seen that the heat exchange tube 7 obtained in Comparative Examples 1 and 2 has a silvery-white inner wall with a metallic luster and no brown protective film layer.

[0126] As shown in Table 1, the electrochemical test results of the heat exchange tubes 7 obtained in Comparative Examples 1 and 2 do not meet the requirements for good film quality proposed in this invention. After film formation, the heat exchange tubes 7 obtained using the seawater film formation method for marine copper-nickel alloy heat exchange tubes described in Examples 1 and 3 were analyzed and calculated based on the potentiodynamic polarization curves to obtain the low-frequency impedance modulus and corrosion current density of the tube sample. The results showed that the corrosion current density was ≤1 μA / cm². 2 Low-frequency impedance modulus ≥10 5 Ω·cm 2 .

[0127] Based on the combined results of the inner wall morphology and electrochemical tests, it is evident that the quality of the heat exchanger film obtained using the seawater film formation method for marine copper-nickel alloy heat exchanger tubes described in Examples 1-3 is good.

[0128] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for seawater film formation on marine copper-nickel alloy heat exchange tubes, characterized in that, The seawater film formation method includes the following steps: S1. Preparation of seawater film forming device: The seawater film forming device includes a seawater pump (1), a filter (2), a solenoid valve (4), a flow meter (5) and a heat exchange component (8). The heat exchange component (8) includes multiple heat exchange units (80), each heat exchange unit (80) includes a heat exchange tube (7) and two quick connectors (6). S2. Calculation of the total flow rate Q of the piping system: The total flow rate Q of the piping system is calculated according to the following formula: Q = n × A × v × 3600 / 1000000 Where: Q is the total flow rate of the pipeline system (unit: m³ / s). 3 / h), n is the number of heat exchange tubes (7), and A is the cross-sectional area inside the heat exchange tube (7) (unit: mm). 2 v is the flow velocity (in m / s) inside the heat exchange tube (7). S3. Determine the flow rate of the seawater pump: The flow range of the seawater pump (1) is 1.2Q~1.3Q. Select the seawater pump (1) according to the flow range of the seawater pump (1). S4. Seawater film forming device setup: Seawater enters the seawater pump (1) through the water intake pipe (9). The seawater pump (1) is connected in sequence to the filter (2), solenoid valve (4), flow meter (5), and heat exchange assembly (8). The two adjacent seawater pumps (1), filters (2), solenoid valves (4), flow meters (5), and heat exchange assembly (8) are connected by connecting pipes (3). The other end of the heat exchange assembly (8) is connected to the drain pipe (10). The quick connector (6) is installed at both ends of the heat exchange pipe (7). S5. Pipeline flow rate setting: Turn on the machine water for debugging to ensure that the flow rate in the heat exchange tube (7) reaches 1.0~3.0m / s; S6. Seawater film formation time: The heat exchange tube (7) forms a film after being continuously flushed by seawater for 20 to 60 days.

2. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 1, characterized in that, After the film is formed on the heat exchange tube (7), it is determined whether the inner wall surface of the heat exchange tube (7) shows a uniform yellowish-brown or brownish-brown color, and whether the corrosion current density under the potentiodynamic polarization curve measured in seawater is not greater than 1 μA / cm. 2 And whether the low-frequency impedance modulus is not less than 10 5 Ω·cm 2 If so, it indicates that the film quality of the heat exchange tube (7) is good.

3. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 2, characterized in that, If the membrane quality of the heat exchange tube (7) is good, use tap water to rinse the mud and sand inside the heat exchange tube (7) one by one, then quickly blow it dry with compressed air, then put tube caps on both ends of each heat exchange tube (7), and finally separate and protect each tube before sealing and storing the whole tube.

4. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 1, characterized in that, The outlet of the drain pipe (10) is more than 10 meters away from the inlet of the water intake pipe (9).

5. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 1, characterized in that, The inlet of the water intake pipe (9) is located more than 1 meter away from the seabed.

6. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 1, characterized in that, The heat exchange tube (7) is made of copper-nickel alloy.

7. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 1, characterized in that, The heat exchange tube (7) has a diameter of Φ10~Φ35mm and a wall thickness of 1~2.5mm.

8. The seawater film formation method for a marine copper-nickel alloy heat exchanger tube according to claim 1, characterized in that, The heat exchange tube (7) forms a film after being continuously flushed by seawater for 20 to 30 days.

9. A seawater film-forming device for marine copper-nickel alloy heat exchange tubes, characterized in that, The seawater film forming device uses a seawater film forming method for a marine copper-nickel alloy heat exchange tube as described in any one of claims 1 to 8. The seawater film forming device includes a seawater pump (1), a filter (2), a solenoid valve (4), a flow meter (5), and a heat exchange assembly (8). The inlet pipe (9) is sequentially connected to the seawater pump (1), the filter (2), the solenoid valve (4), the flow meter (5), the heat exchange assembly (8), and the drain pipe (10).

Images