An accelerated seawater erosion corrosion testing device and method adapted to ORV heat exchanger plates

Abstract

This invention relates to the field of simulation testing equipment technology, specifically to an accelerated seawater erosion corrosion testing device and method adapted to ORV heat exchanger plates. The device includes a frame, a liquid supply unit, a spray unit, a splash guard, and a flow rate detection component. The frame is used to vertically suspend the test specimen. The liquid supply unit includes a storage tank and a circulation pump. The spray unit is located above the frame and is used to spray the test liquid onto the surface of the test specimen. The storage tank, circulation pump, spray unit, and storage tank are sequentially connected to form a liquid circulation loop. Under the action of gravity, the liquid flows downward along the surface of the test specimen and returns to the storage tank. The flow rate detection component is located below the test specimen to obtain the flow rate of the downstream liquid. This invention replicates the actual laminar flow erosion conditions by vertically suspending the specimen and using gravity-driven liquid film flow. The flow rate is adjustable and controllable, with a short test cycle and high accuracy.

Description

Technical Field

[0001] This invention relates to the field of simulation testing equipment technology, and in particular to a seawater erosion corrosion accelerated testing device and method adapted to ORV heat exchange plates. Background Technology

[0002] The Open Rack Vaporizer (ORV) is a core heat exchange device in an LNG receiving terminal. The heat exchange unit consists of multiple star-shaped finned tubes and upper and lower manifolds welded together to form heat exchange plates. During operation, seawater overflows from the top of the plates under gravity and flows vertically downwards along the outer surface of the finned tubes. Its main function is to absorb heat from the seawater through the heat exchange tube bundle, converting the liquefied natural gas (LNG) inside the tube bundle from bottom to top into a gaseous state (NG). The heat exchange tubes, gas manifold, and liquid manifold are all made of aluminum alloy.

[0003] The external medium of the ORV, seawater, is an extremely complex corrosive system. During ORV operation, seawater simultaneously exerts a dual destructive effect on its surface coating through high-speed physical erosion and chloride ion electrochemical corrosion, making the coating's working environment quite harsh. To protect the aluminum alloy heat exchange substrate, the outer surfaces of the ORV finned tubes and manifolds are uniformly coated with an aluminum-zinc alloy protective coating. As a barrier protecting the equipment, the assessment of the aluminum-zinc coating's resistance to seawater erosion corrosion is crucial. With a designed service life of 25 years, coating failure will directly cause seawater corrosion of the aluminum alloy substrate, leading to heat exchange tube leaks and threatening the continuous and safe operation of the LNG receiving terminal. Therefore, before coating commissioning and on-site repairs, erosion corrosion simulation tests matching the local seawater quality and flow velocity must be conducted to predict the coating's service life.

[0004] There are two main types of testing methods with defects: (1) Rotation scouring test method; relying on the impeller to drive the coated test piece to rotate in the seawater to form a relative water flow, the equipment is small in size and consumes little water, but there are inherent defects: the impeller rotation generates a large number of eddies and turbulence, the water flow impact angle and flow pattern are completely inconsistent with the vertical laminar scouring condition of ORV from top to bottom; the test piece is a small flat plate sample, which cannot reproduce the fin structure and manifold structure of ORV, the diversion and flow erosion effect of water flow along the curved fin is completely missing, the test data is distorted and cannot guide the actual ORV coating selection. (2) Sea-mounted test; the coated test piece is directly immersed in the near-shore sea area, which can only simulate static seawater corrosion and cannot reproduce the high-velocity continuous gravity scouring condition of ORV; the test cycle is as long as several years, the research and development and verification efficiency is extremely low, and the marine environmental variables are uncontrollable, the repeatability of different batches of tests is poor, which seriously restricts the research and development progress of new seawater erosion resistant coatings.

[0005] Therefore, there is an urgent need for a seawater erosion corrosion accelerated testing device and method adapted to ORV heat exchanger plates to solve the problems of insufficient accuracy and low efficiency of existing erosion corrosion testing methods. Summary of the Invention

[0006] In view of this, the present invention aims to propose a seawater erosion corrosion accelerated testing device and method adapted to ORV heat exchange plates, so as to solve the problems of insufficient accuracy and low efficiency of existing erosion corrosion testing methods.

[0007] The technical solution of this invention is implemented as follows:

[0008] One object of the present invention is to disclose a seawater erosion corrosion accelerated testing device adapted to ORV heat exchanger plates, comprising:

[0009] The frame is used to vertically suspend and fix the test piece;

[0010] The liquid supply unit, located below the frame, includes a liquid storage tank and a circulation pump for storing and transporting the test liquid;

[0011] A spraying unit, disposed above the frame, includes a spraying assembly for spraying the test liquid onto the surface of the test piece;

[0012] A splash guard is installed on the outside of the frame to reduce liquid splashing and evaporation loss during the test;

[0013] A flow rate detection component is disposed below the test piece to obtain the flow rate of the liquid flowing under the surface of the test piece;

[0014] The liquid storage tank, the circulation pump, the spray unit, and the liquid storage tank are connected in sequence to form a liquid circulation loop. The test liquid is transported to the top of the test piece by the spray assembly, and then flows downward along the surface of the test piece under the action of gravity, and flows back to the liquid storage tank.

[0015] Optionally, the test piece is an open-frame vaporizer heat exchange plate, which is formed by welding multiple finned tubes with an upper manifold and a lower manifold, and the test liquid is natural seawater or artificial simulated seawater.

[0016] Optionally, the spraying unit includes two sets of spraying components, respectively disposed on both sides of the top of the frame, for spraying the test liquid onto the front and back of the test piece from both sides.

[0017] Optionally, the rack includes:

[0018] A top-mounted hook is used to suspend the test piece.

[0019] A vertical positioning limit rod is set vertically along both sides of the test piece to limit the lateral displacement of the test piece;

[0020] Fine-tuning supports are located on both sides of the bottom of the test piece and are used to calibrate the verticality of the test piece.

[0021] Optionally, the liquid supply unit further includes a filter assembly, which is disposed at the liquid inlet of the circulation pump and is used to intercept impurities in the test liquid.

[0022] Optionally, the spray assembly includes a water spray pipe and nozzles disposed on the water spray pipe. The two ends of the water spray pipe are provided with rotary sealing elbows, which are used to adjust the spray angle of the nozzles. The water spray pipe is independently equipped with a flow regulating valve and a flow meter.

[0023] Optionally, the splash shield is formed by splicing transparent anti-corrosion plates. The top of the splash shield has a perforation for the spray assembly to pass through, and the bottom is sealed to the liquid storage tank. The seams of the splash shield are provided with sealing strips, and the bottom of the inner side of the splash shield is provided with a guide groove, which is connected to the liquid storage tank.

[0024] Optionally, the liquid storage tank is a sealed box with a reflux inlet at the top, a drain valve at the bottom, and a feed port on the side wall.

[0025] Another object of the present invention discloses a seawater erosion corrosion accelerated testing method adapted to ORV heat exchanger plates, based on the seawater erosion corrosion accelerated testing device adapted to ORV heat exchanger plates described in any of the above claims, comprising the following steps:

[0026] The test piece is vertically suspended and fixed on the frame;

[0027] The test liquid is injected into the storage tank;

[0028] The circulation pump is started, and the test liquid is sprayed onto the surface of the test piece through the spray assembly. Under the action of gravity, it flows down the surface of the test piece and back to the storage tank.

[0029] The flow rate of the liquid at the bottom of the test piece is obtained by the flow rate detection component, and the output power of the circulation pump and / or the flow rate of the spray component are adjusted to make the flow rate reach a predetermined value.

[0030] A scouring test is conducted according to a predetermined test cycle to detect the morphology and / or thickness of the coating on the surface of the test piece.

[0031] Optionally, the predetermined value is the actual measured flow velocity of the seawater at the bottom of the open-frame gasifier in the target sea area, or 1.2 to 3 times the actual measured flow velocity.

[0032] Compared with the prior art, the seawater erosion corrosion accelerated testing device and method adapted to ORV heat exchanger plates of the present invention have the following advantages:

[0033] 1. This invention uses a vertical frame to suspend the test piece vertically and, in conjunction with top spraying and gravity recirculation, creates a vertical laminar erosion flow field. It uses complete open-frame vaporizer heat exchange plates as test pieces to reproduce the flow around the curved surface of finned tubes and the accelerated erosion effect at the end of the manifold. This solves the problems of flow field morphology distortion and lack of structural erosion effect caused by eddy current turbulence and small flat plate test pieces in the traditional rotating erosion method, improves the test accuracy, and realizes high-precision simulation evaluation of coatings under real gravity-driven laminar flow conditions.

[0034] 2. This invention combines the adjustment of the output power of the circulating pump with the adjustment of the flow rate of the spraying component, so that the surface velocity of the specimen can be continuously adjusted within the range of the on-site reference flow rate to twice the reference flow rate. This solves the problem that existing equipment cannot meet the dual testing requirements of long-term verification under the same working conditions and accelerated aging screening. It realizes the flexible switching between the two modes of conventional evaluation and accelerated testing, and significantly shortens the research and verification cycle of new corrosion-resistant coatings.

[0035] 3. This invention establishes a closed-loop flow velocity calibration system by setting up independent spray units on both sides in conjunction with flow velocity detection components. It monitors the flow velocity of the liquid flowing down the bottom of the test specimen in real time and dynamically adjusts the output power of the circulating pump and the spray flow rate, so that the flow velocity on the surface of the specimen is accurately matched with the actual measured reference flow velocity. This solves the problem that existing scouring test devices cannot quantitatively reproduce the specific flow velocity conditions at the bottom of ORV equipment in the target sea area, and realizes the accurate mapping between accelerated laboratory tests and long-term service conditions in the field.

[0036] 4. This invention constructs a liquid supply circulation loop in conjunction with a sealed splash guard and a filter assembly to form a long-term circulating supply system for natural seawater. The storage tank, circulation pump, spray unit, and storage tank are connected in sequence to achieve closed-loop recycling of seawater. The pre-filter assembly intercepts impurities such as silt and algae in the seawater, and the splash guard, together with the guide channel, collects splashed liquid and returns it to the storage tank. This solves the problems of seawater evaporation loss, water quality changes, and nozzle blockage that lead to unsustainable experiments during long-term operation of open-type flushing equipment, and enables stable operation of several months of continuous experiments with a single sample of natural seawater. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1 This is a three-dimensional structural diagram of the overall device of the present invention;

[0039] Figure 2 This is a partial structural diagram of the test plate suspension fixture of the present invention;

[0040] Figure 3This is a schematic diagram of the water spray pipe assembly with a rotating nozzle on one side according to the present invention;

[0041] Figure 4 This is an AA cross-sectional view of the single-sided rotating nozzle of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Frame; 11. Top lifting hook; 12. Fine-tuning support; 13. Vertical positioning limit rod; 2. Test piece; 21. Finned tube; 22. Lower manifold; 23. Upper manifold; 3. Spray unit; 31. Water spray pipe; 32. Rotary sealing elbow; 33. Nozzle; 34. Flow regulating valve; 35. Flow meter; 4. Splash shield; 5. Liquid supply unit; 6. Flow rate detection component; 7. Liquid storage tank. Detailed Implementation

[0044] 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.

[0045] like Figures 1-4 As shown, an accelerated seawater erosion corrosion testing device adapted to ORV heat exchanger plates includes a frame 1, a liquid supply unit 5, a spray unit 3, a splash guard 4, and a flow rate detection component 6. The frame 1 is used to vertically suspend and fix the test piece 2; the liquid supply unit 5 is located below the frame 1 and is used to store and transport the test liquid; the spray unit 3 is located above the frame 1 and is used to spray the test liquid onto the surface of the test piece 2; the splash guard 4 is located outside the frame 1 and is used to reduce liquid splashing and evaporation loss during the test; the flow rate detection component 6 is located below the test piece 2 and is used to obtain the flow rate of the liquid flowing down the surface of the test piece 2. Among the above components, the liquid storage tank 7, the circulation pump, the spray unit 3, and the liquid storage tank 7 are sequentially connected by pipelines to form a liquid circulation loop. After the test liquid is transported to the top of the test piece 2 by the spray component, it flows down the surface of the test piece 2 under gravity and returns to the liquid storage tank 7.

[0046] By vertically suspending the test specimen and combining it with top spraying and gravity recirculation, the test liquid forms a vertical laminar flow pattern from top to bottom on the surface of the test specimen. This is highly consistent with the actual operation of an open-frame gasifier, where seawater flows downwards along the heat exchange plate surface by gravity. This eliminates the flow field distortion caused by eddies and turbulence generated by impeller rotation in the traditional rotary scouring method, thus improving the test accuracy. Simultaneously, the flow velocity of the liquid flowing down from the bottom of the test specimen 2 is acquired in real time by the flow velocity detection component 6. Based on this, the output power of the circulating pump and / or the flow rate of the spray component are adjusted, allowing the surface velocity of the test specimen 2 to be continuously adjustable within the range of the reference velocity to twice the reference velocity. This enables rapid establishment and flexible switching of test conditions, shortening the test cycle from several years in the traditional sea-based suspended plate method to less than three months, solving the problems of long test cycles and low R&D verification efficiency in the sea-based suspended plate method.

[0047] Preferably, the test piece 2 is an ORV finned tube test plate, which is made by welding multiple star-shaped finned tubes 21 with an upper manifold 23 and a lower manifold 22. Its specifications, materials and welding process are completely consistent with the heat exchange plates of the ORV equipment on site, so as to fully reproduce the flow characteristics of seawater flowing around the curved surface of the finned tube 21 and the accelerated erosion at the end of the manifold under actual working conditions, thereby avoiding the problem of missing structural erosion effect caused by using small flat plate test pieces.

[0048] Specifically, the frame 1 is a vertical frame structure. Preferably, the frame 1 is constructed entirely of stainless steel resistant to seawater corrosion or steel structural profiles coated with anti-corrosion coating, welded or bolted together; the height of the frame 1 is not less than 2500mm and the width is not less than 1800mm, to ensure complete accommodation of the test piece 2 of the open-frame vaporizer heat exchange plate specifications.

[0049] Based on this, the liquid supply unit 5 is located below the frame 1, including a liquid storage tank 7 and a circulation pump. The liquid storage tank 7 is used to store the test liquid, and the circulation pump is used to transport the test liquid in the liquid storage tank 7 to the spray unit 3. Preferably, the circulation pump is a seawater-specific corrosion-resistant pump, and its flow-through parts are made of duplex stainless steel or engineering plastic to adapt to high chloride ion media environments; the rated head of the pump is not less than 20m, and the rated flow rate is not less than 10m³ / h.

[0050] Accordingly, the spray unit 3 includes a spray assembly, which includes a water spray pipe 31 and a nozzle 33 disposed on the water spray pipe 31.

[0051] In addition, the flow rate detection assembly 6 includes a portable flow rate detector and a mounting base disposed at the bottom of the test piece 2, wherein the flow rate detector is detachably mounted on the mounting base.

[0052] like Figure 2As shown, in a specific embodiment, in order to achieve vertical suspension and precise positioning of the test piece 2 on the frame 1, the frame 1 is provided with a suspension positioning structure. The suspension positioning structure includes a hoisting component set at the top of the frame 1, a limiting component set on both sides of the frame 1, and a support adjustment component set at the bottom of the frame 1. The three components work together to achieve the functions of rapid hoisting, lateral limiting, and verticality calibration of the test piece 2.

[0053] Furthermore, the lifting assembly is a top lifting hook 11, which is installed on the top crossbeam of the frame 1 and used to suspend the test piece 2. Preferably, there are two or more top lifting hooks 11, which are spaced apart along the width direction of the top crossbeam to ensure uniform force on the test piece 2 when suspended. The top lifting hooks 11 are preferably U-shaped hooks or shackle hooks to facilitate quick assembly and disassembly of the test piece 2.

[0054] The limiting component consists of vertical positioning limiting rods 13, which are vertically mounted on the frame 1 along both sides of the test piece 2 to limit the lateral displacement of the test piece 2. There are two vertical positioning limiting rods 13, one on the left and one on the right, with a gap of 5mm to 20mm between each limiting rod and the side of the test piece 2. The height of the limiting rods is not less than the height of the test piece 2 to ensure that the test piece 2 does not sway laterally during the test.

[0055] The support adjustment assembly is a fine-tuning support base 12, which is located on both sides of the bottom of the test piece 2 and is used to calibrate the verticality of the test piece 2. The fine-tuning support base 12 includes a fixed base and a movable support block. The movable support block is connected to the fixed base through a threaded adjustment mechanism or a wedge adjustment mechanism. Rotating the adjustment handle drives the movable support block to move up and down slightly, thereby applying a small adjustment force to the bottom of the test piece 2 to make the test piece 2 reach a completely vertical state. The adjustment accuracy of the fine-tuning support base 12 is ±0.5mm.

[0056] Through the coordinated operation of the top hoisting hook 11, the vertical positioning limit rod 13 and the fine-tuning support 12, the test piece 2 can be vertically centered and suspended on the frame 1, with lateral limiting and anti-swaying, and precise verticality calibration, ensuring the attitude stability of the test piece 2 during the test.

[0057] In one optional embodiment, to further ensure precise control of the distance between the spray assembly and the test specimen 2, water pipe mounting brackets that can move back and forth can be provided on both sides of the frame 1. The mounting brackets are equipped with scales to precisely control the distance between the spray assembly and the surface of the test specimen 2. The mounting brackets are slidably connected to the frame 1 via linear guides or a screw and nut mechanism. The operator can adjust the spray assembly to a predetermined distance according to the reading on the scale, thereby ensuring the symmetry of the spray water volume on both sides and the repeatability of the test conditions.

[0058] Accordingly, to prevent impurities such as silt and algae mixed in with natural seawater from clogging the nozzle 33 and affecting the uniformity of spraying, the liquid supply unit 5 has also been optimized. In one specific embodiment, the liquid supply unit 5 further includes a filter assembly, which is located at the inlet of the circulating pump to intercept impurities in the test liquid.

[0059] Preferably, the filter assembly includes a primary coarse filter and a secondary fine filter arranged in series. The primary coarse filter has a mesh size of 20 to 40 mesh and is used to intercept larger impurities such as silt particles and seaweed fragments in seawater; the secondary fine filter has a mesh size of 80 to 120 mesh and is used to intercept finer suspended solids, protecting the nozzle 33 from clogging. Both filter screens are woven from 316L stainless steel that is resistant to seawater corrosion, and the filter screen frames are removable for easy regular cleaning and replacement.

[0060] In addition to the filtration components, the storage tank 7 in the liquid supply unit 5 is also specifically designed to meet the needs of long-term storage and recycling of natural seawater. In one specific embodiment, the storage tank 7 is a sealed container with a volume of 2.5 m³ to 5 m³, preferably 3 m³, to meet the requirements of completing long-term continuous experiments with a single intake of natural seawater. The storage tank 7 is made of polyethylene, polypropylene, or stainless steel with an anti-corrosion lining to withstand the corrosiveness of seawater. The top of the storage tank 7 is equipped with a reflux inlet, the bottom with a drain valve, and the side wall with a feed port. The reflux inlet is connected to the guide channel at the bottom of the splash guard 4 for collecting refluxed seawater. The drain valve is located at the lowest point of the storage tank 7 to facilitate the periodic discharge of deposited silt and salt. The feed port is used to replenish seawater or add experimental additives such as corrosion inhibitors and simulated marine organisms.

[0061] In addition, the suction pipe of the circulating pump is located on one side of the bottom of the liquid storage tank 7, and the end of the suction pipe is equipped with an anti-vortex cover to prevent vortices from being generated at the pump inlet and drawing in air. The outlet pipe of the circulating pump is equipped with a pressure gauge and a flow regulating valve 34 for monitoring and regulating the total flow of the system.

[0062] Based on this, a preferred implementation of the spray unit 3 is dual-sided synchronous spraying. In a specific embodiment, the spray unit 3 includes two sets of spray components, respectively disposed on both sides of the top of the frame 1, for spraying the test liquid onto the front and back sides of the test piece 2 from both sides. The two sets of spray components operate independently, and their respective spray flow rate and spray angle can be adjusted, thereby enabling comparison of coating performance under different spray parameter conditions within the same test cycle, which is beneficial to improving test efficiency and data comparability.

[0063] like Figure 3As shown, each spray assembly includes a water spray pipe 31 and nozzles 33 disposed on the water spray pipe 31. The water spray pipe 31 is horizontally arranged on the top of the frame 1, and its length is not less than the width of the test piece 2. Multiple nozzles 33 are evenly spaced along the length of the water spray pipe 31, with a spacing of 50mm to 150mm between adjacent nozzles 33 to ensure that the water flow can uniformly cover the entire surface of the test piece 2. The outlet diameter of the nozzles 33 is 2mm to 8mm, preferably 4mm to 6mm, and can be replaced according to the required spray flow rate and spray speed.

[0064] Based on the arrangement of the water spray pipe 31 and nozzle 33, rotating sealing elbows 32 are provided at both ends of the water spray pipe 31. The rotating sealing elbows 32 are used to adjust the spray angle of the nozzles 33. The angle adjustment range of the rotating sealing elbows 32 is 0° to 360°. The operator can adjust the spray direction of the nozzles 33 at any angle in the vertical plane by rotating the rotating sealing elbows 32. Preferably, the spray angle is set to tilt downwards by 10° to 30°, so that the seawater is sprayed at a certain impact angle to the top of the test piece 2 and then flows downwards along the surface, simulating the initial impact force of the seawater when it reaches the top of the plate, and ensuring the mainstream flow pattern driven by gravity.

[0065] To precisely control the flow rate of each spray pipe and achieve independent adjustment on both sides, each spray pipe 31 is independently equipped with a flow regulating valve 34 and a flow meter 35. The flow regulating valve 34 is a needle valve or ball valve, used to precisely control the flow rate of one side of the spray pipe; the flow meter 35 is a float flow meter or electromagnetic flow meter, used to display the current flow rate value in real time. By independently adjusting the flow rate of the two spray pipes 31, different spray parameters can be applied to the front and back of the test piece, thereby allowing for simultaneous comparison of the erosion corrosion resistance of two different coatings within the same test cycle, significantly improving test efficiency.

[0066] In one specific embodiment, to enable real-time observation of the coating condition during the test and prevent seawater spillage, the splash guard 4 is formed by splicing transparent anti-corrosion sheets, preferably polycarbonate sheets or plexiglass sheets, with a thickness of 3mm to 8mm. Using transparent materials allows operators to directly observe the changes in the coating condition on the surface of the test piece 2 during the test without opening the splash guard 4.

[0067] For the openings on the splash guard 4 where spray pipes need to pass through, the top of the splash guard 4 has a perforation for the spray assembly to pass through. The spray pipe 31 passes through the perforation and extends into the interior of the splash guard 4. A sealing sleeve or sealing brush is provided at the perforation to prevent seawater from splashing out. The bottom of the splash guard 4 is sealed and connected to the liquid storage tank 7. The lower edge of the splash guard 4 extends into the return inlet of the liquid storage tank 7 or is connected to the return inlet flange.

[0068] For the joints between the panels of the splash shield 4, a sealing strip is provided at the joints of the splash shield 4. The sealing strip is made of seawater-resistant silicone rubber or EPDM rubber to ensure that the joints between the panels of the splash shield 4 are completely sealed, preventing seawater splashing and evaporation loss.

[0069] Furthermore, to collect splashed droplets adhering to the inner wall of the splash shield 4 and allow them to flow back to the storage tank 7, a guide channel is provided on the inner bottom of the splash shield 4. The guide channel is arranged along the inner circumference of the splash shield 4, and is annular or U-shaped. The bottom of the guide channel is inclined, and the lowest point is connected to the storage tank 7. A small amount of seawater splashed onto the inner wall of the splash shield 4 flows into the guide channel under the action of gravity, and then flows back to the storage tank 7 through the guide channel, further reducing seawater loss.

[0070] By combining the splash guard 4 with the flow channel, the seawater loss during the entire test is extremely low. A single use of 2.5 to 3 tons of natural seawater can meet the needs of long-term tests for more than three months, solving the problem of continuous water replenishment and water quality changes caused by water evaporation and splashing in open-type flushing equipment.

[0071] In one specific embodiment, to achieve real-time monitoring and closed-loop control of the liquid flow velocity flowing down the surface of the test piece 2 during the test, the flow velocity detection component 6 includes a flow velocity detector and a mounting base disposed at the bottom of the test piece 2. The flow velocity detector is detachably mounted on the mounting base. The flow velocity detector is preferably a portable electromagnetic flow meter or a propeller-type flow meter, with a measurement accuracy of not less than ±0.05 m / s and a measurement range covering 0.5 m / s to 5.0 m / s.

[0072] Based on the structure and selection of the flow velocity meter described above, the mounting base is fixed to the bottom of the lower manifold 22 of the test piece 2 or to a dedicated velocity measuring bracket. The mounting base is equipped with a snap-fit ​​or threaded interface compatible with the flow velocity meter. During the test, the probe of the flow velocity meter is inserted into the falling seawater stream at the bottom of the test piece 2 to detect the seawater flow velocity in real time and feed the data back to the operator. Based on the reading of the flow velocity meter, the operator dynamically adjusts the output power of the circulation pump (e.g., by adjusting the pump speed through a frequency converter) and / or the opening of the flow regulating valve 34 on the spray assembly to ensure that the seawater flow velocity at the bottom of the test piece 2 accurately reaches the predetermined value.

[0073] Through the aforementioned flow velocity monitoring and closed-loop adjustment settings, the precise matching between the seawater flow velocity inside the experimental device and the actual measured bottom flow velocity of the open-frame gasifier was achieved, solving the defect that existing experimental devices cannot quantitatively reproduce the specific flow velocity conditions of the target sea area.

[0074] This invention also provides a test method for an accelerated seawater erosion corrosion test apparatus adapted to ORV heat exchange plates based on any of the above embodiments. The test method using the above-described test apparatus will be described in detail below with reference to specific embodiments.

[0075] Example 1

[0076] This embodiment takes the ORV equipment of an LNG receiving station in the Yellow Sea as an example to conduct a scouring corrosion test on the aluminum-zinc coating.

[0077] Step 1: On-site operating condition parameter acquisition.

[0078] A field trip was conducted to the target LNG receiving terminal located in the Yellow Sea. With the ORV (Organizational Return Vehicle) equipment operating normally, a portable current meter was used to measure the actual falling velocity of the seawater at the bottom of the ORV equipment (at the LNG manifold), and this was recorded as the baseline velocity value (the measured value in this embodiment was 1.8 m / s). Simultaneously, approximately 3 tons of natural seawater from this area were collected and transported to the laboratory in sealed storage tanks. Water quality testing was performed on the collected seawater, and parameters such as chloride ion concentration, pH value, dissolved oxygen content, and sediment content were recorded as baseline water quality data for the experiment.

[0079] Step 2: Preparation of test plates.

[0080] Test piece 2 was welded according to the actual structure of the ORV heat exchanger plates. Test piece 2 consists of 20 star-shaped finned tubes 21 welded together with upper manifold 23 and lower manifold 22. The center distance between upper manifold 23 and lower manifold 22 is 2100mm, and the total width of the plates is 1500mm. The specifications, materials, and welding process of the finned tubes 21 are completely consistent with the ORV equipment on site.

[0081] Different types of coatings were prepared on the front and back sides of the test piece 2. For example, a common Al-Zn alloy coating was sprayed on the front side of the plate, and a rare earth element modified aluminum alloy coating was sprayed on the back side. The spraying process parameters (spraying distance, spraying angle, number of spray passes, curing temperature and time, etc.) for both coatings were strictly consistent with the coating preparation process of the on-site ORV equipment, and the coating thickness was uniformly controlled within 250μm±20μm. After spraying, the initial coating thickness was measured at multiple points using a coating thickness gauge and recorded, and the initial macroscopic morphology of the coating was photographed and archived using a digital camera.

[0082] Step 3: Suspension and positioning of the sample.

[0083] The prepared test piece 2 is hoisted to the center position of the frame 1 and suspended and fixed by the top hoisting hook 11. Adjust the fine-tuning support seats 12 on both sides, and use a level or plumb line to calibrate the verticality of the test piece 2 to ensure that the test piece 2 is completely vertical in the vertical plane, with a deviation not exceeding ±1mm / m.

[0084] Using the scale on the mounting bracket, adjust the distance between the two water spray pipes 31 and the surface of the test piece 2 to be equal. In this embodiment, the distance is set to 120mm. Rotate the rotary sealing elbow 32 to adjust the spray angle of the nozzle 33 so that the spray direction of the nozzle 33 is tilted downward by 15° to ensure that the water flow can fully cover the finned tube 21 area and be evenly distributed.

[0085] Step 4: Seawater filling and pipeline inspection.

[0086] All 3 tons of collected natural seawater from the Yellow Sea were poured into the bottom storage tank 7. The primary coarse filter and the secondary fine filter of the filtration assembly were turned on, and all water spray pipes 31 and nozzles 33 were checked for blockages. The splash guard 4 was closed and all sealing strips at the joints were sealed to reduce seawater evaporation loss during the test.

[0087] Step 5: Pre-testing of the circulating spray system.

[0088] Start the circulation pump, and seawater is transported to the double-sided spray pipes 31 through the circulation pump. It is then sprayed onto the top of the test piece 2 through the nozzles 33. Under the action of gravity, the seawater flows downward along both sides of the test piece 2 and flows back to the storage tank 7.

[0089] The flow velocity meter was fixed to the mounting base at the bottom of the test piece 2 to monitor the flow velocity of the falling seawater in real time. The output power of the circulation pump (adjusted via a frequency converter) and the flow regulating valves 34 on each spray pipe 31 were adjusted synchronously to stabilize the reading of the flow velocity meter at the reference flow velocity of 1.8 m / s. The operating frequency of the circulation pump and the readings of the flow meters 35 on each branch pipe were recorded at this time as standard operating parameters for subsequent tests.

[0090] Step Six: Long-term Cyclic Test.

[0091] The equipment operates continuously for 24 hours a day, conducting continuous seawater spraying and scouring tests. The standard test cycle is set at 90 days (three months). The equipment is stopped once a week at a fixed time, the splash guard 4 is opened, and the macroscopic morphology of the coating on both sides of the test piece 2 is photographed in its entirety. The focus is on recording whether defects such as blistering, peeling, pitting, and erosion grooves appear on the coating surface, as well as their location and extent.

[0092] During the experiment, water samples were taken weekly to test key water quality parameters such as chloride ion concentration and pH value to ensure water quality stability. If the water level dropped due to evaporation, deionized water was added through the feed inlet to bring it back to the initial level. Every 30 days, bottom sediment was discharged through the drain valve and fresh seawater was added to maintain seawater activity.

[0093] Step 7: Performance testing after the test is terminated.

[0094] After 90 days of continuous testing, turn off the circulation pump and stop spraying. Remove test piece 2, rinse the surface with clean water to remove residual sea salt and corrosion products, and let it air dry naturally.

[0095] The overall coating morphology of the test specimen 2 on both sides was photographed again and compared with the morphology photos recorded before the test and weekly. At least 20 measurement points were selected on the front and back of the plate using a coating thickness gauge (covering different positions such as the top, side, root and manifold surface of the finned tube 21) to measure the remaining coating thickness and calculate the thickness reduction and average corrosion erosion rate at each measurement point.

[0096] Based on the test data, the failure rates of ordinary Al-Zn coatings and rare earth modified coatings were compared under the same scouring conditions. The scouring and corrosion resistance of the two coatings under seawater scouring in the Yellow Sea was evaluated, and the preferred coating scheme for this sea area was determined.

[0097] Example 2

[0098] The difference between this embodiment and Embodiment 1 is that the flow rate setting value is different in step five.

[0099] The seawater flow velocity at the bottom of test specimen 2 was calibrated to 1.5 times the on-site reference flow velocity, i.e., 2.7 m / s (1.8 m / s × 1.5), and an accelerated aging test was conducted. Due to the increased flow velocity, the wall shear force increased, the erosion corrosion rate accelerated, and the test cycle was correspondingly shortened to 45 days. Other operations (weekly photo recording, post-test inspection and evaluation, etc.) remained consistent with Example 1.

[0100] After the experiment, the coating damage under the 45-day accelerated condition was compared with the coating damage under the 90-day baseline condition in Example 1 to establish a conversion model between accelerated testing and long-term field service. For example, if the coating thickness reduction under the accelerated condition reaches the same level as the 90-day reduction under the baseline condition, it can be preliminarily determined that 1.5 times the flow rate for 45 days is approximately equivalent to the scouring corrosion effect of the 90-day baseline condition. This conversion model can be used for the rapid screening of new coating materials, significantly shortening the R&D verification cycle.

[0101] In one alternative implementation, the acceleration factor is not limited to 1.5 times, but can be flexibly selected in the range of 1.2 times to 3.0 times according to the test requirements. The higher the acceleration factor, the shorter the test cycle, but it should be noted that excessively high flow rates may change the dominant mechanism of erosion corrosion (such as changing from corrosion-dominant to erosion-dominant). Therefore, an acceleration factor of 1.2 times to 1.8 times is preferred.

[0102] The working principle and beneficial effects of the device of this invention are explained as follows: During operation, the circulating pump draws natural or artificially simulated seawater from the storage tank 7. After passing through a pre-filter to intercept impurities such as silt and algae, the clean seawater is delivered to the double-sided spray pipes 31 at the top of the frame 1. The seawater is sprayed at a certain angle and speed through nozzles 33 on the spray pipes 31 onto the top of the vertically suspended test piece 2. Subsequently, driven by gravity, the seawater flows from top to bottom along the finned tubes 21 on both sides of the test piece 2 in a laminar flow state. When flowing over the curved surface of the finned tubes 21, a flow around them is generated; when flowing to the lower manifold 22, an accelerated erosion effect is generated at the end, completely replicating the actual flow pattern of seawater along the heat exchange plate surface during the actual operation of the open-frame gasifier. The seawater flowing through the entire test piece 2, carrying erosion products, falls from the bottom of the plates into the storage tank 7, and then flows back into the tank body through the return inlet at the top of the storage tank 7, forming a complete closed-loop circulation circuit. The splash guard 4 effectively blocks seawater splashing during the test, and the diversion channel collects the splashed seawater and returns it to the storage tank 7, greatly reducing seawater evaporation and loss. A single water intake of 2.5 to 3 tons can meet the needs of long-term testing for more than 90 consecutive days. During the test, the flow rate detector monitors the seawater flow rate at the bottom of the test piece 2 in real time. The operator dynamically adjusts the output power of the circulation pump and / or the opening of the flow regulating valve 34 according to the flow rate reading to make the bottom flow rate accurately match the actual measured reference flow rate on site, so as to achieve accurate simulation of the same working conditions. Alternatively, accelerated testing can be carried out by increasing the flow rate to 1.2 to 3.0 times the reference flow rate, and the coating failure data equivalent to several years of field service can be obtained within 45 to 90 days.

[0103] Through the synergistic effect of the above structures, this invention solves the problems of distorted flow field morphology, lack of structural erosion effect, and inability of experimental data to guide actual coating selection caused by eddy current turbulence and small flat plate samples in the traditional rotary scouring method. At the same time, it solves the problems of long test cycles and extremely low R&D verification efficiency of the actual sea-mounted plate method. It provides an efficient, accurate, and repeatable special test method for evaluating the seawater erosion corrosion resistance of the surface coating of open-frame gasifiers.

[0104] The seawater erosion corrosion accelerated testing device and method adapted to ORV heat exchanger plates provided by this invention can be widely used in scenarios such as material selection, process optimization, and service life estimation of the surface protective coating of LNG receiving station open-frame vaporizers. Furthermore, with appropriate adjustments (such as changing the specimen fixing fixture and adjusting the spray parameters), this device can also be applied to the erosion corrosion performance testing of surface coatings on other plate-type components, demonstrating broad industrial application prospects.

[0105] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A seawater erosion corrosion accelerated testing device adapted to ORV heat exchanger plates, characterized in that, include: A frame (1) is used to vertically suspend and fix the test piece (2); The liquid supply unit (5) is located below the frame (1) and includes a liquid storage tank (7) and a circulation pump for storing and transporting test liquid; A spray unit (3) is disposed above the frame (1) and includes a spray assembly for spraying the test liquid onto the surface of the test piece (2); A splash guard (4) is installed on the outside of the frame (1) to reduce liquid splashing and evaporation loss during the test; A flow rate detection component (6) is disposed below the test piece (2) and is used to obtain the flow rate of the liquid flowing under the surface of the test piece (2); The liquid storage tank (7), the circulation pump, the spray unit (3) and the liquid storage tank (7) are connected in sequence to form a liquid circulation loop. The test liquid is transported to the top of the test piece (2) through the spray assembly, and then flows down along the surface of the test piece (2) under the action of gravity and flows back to the liquid storage tank (7).

2. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 1, characterized in that, The test piece (2) is an open-frame gasifier heat exchange plate, which is made by welding multiple finned tubes (21) with an upper manifold (23) and a lower manifold (22). The test liquid is natural seawater or artificial simulated seawater.

3. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 1, characterized in that, The spray unit (3) includes two sets of spray components, which are respectively arranged on the top two sides of the frame (1) for spraying the test liquid onto the front and back of the test piece (2) from both sides.

4. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 3, characterized in that, The rack (1) includes: Top hanging hook (11) is used to suspend the test piece (2); A vertical positioning limit rod (13) is set vertically along both sides of the test piece (2) to limit the lateral displacement of the test piece (2); Fine-tuning support (12) is set on both sides of the bottom of the test piece (2) to calibrate the verticality of the test piece (2).

5. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 1, characterized in that, The liquid supply unit (5) also includes a filter assembly, which is located at the inlet of the circulating pump and is used to intercept impurities in the test liquid.

6. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 1, characterized in that, The spray assembly includes a water pipe (31) and a nozzle (33) disposed on the water pipe (31). The two ends of the water pipe (31) are provided with rotating sealing elbows (32), which are used to adjust the spray angle of the nozzles (33). The water pipe (31) is independently equipped with a flow regulating valve (34) and a flow meter (35).

7. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 1, characterized in that, The splash shield (4) is formed by splicing transparent anti-corrosion plates. The top of the splash shield (4) is provided with a perforation for the spray assembly to pass through, and the bottom is sealed and connected to the liquid storage tank (7). The joint of the splash shield (4) is provided with a sealing strip, and the bottom of the inner side of the splash shield (4) is provided with a guide groove, which is connected to the liquid storage tank (7).

8. The seawater erosion corrosion accelerated testing device adapted to ORV heat exchange plates according to claim 1, characterized in that, The storage tank (7) is a sealed box with a reflux inlet at the top, a drain valve at the bottom, and a feed inlet on the side wall.

9. A method for accelerating seawater erosion corrosion testing of ORV heat exchanger plates, characterized in that, The seawater erosion corrosion accelerated testing device based on any one of claims 1-8 and adapted to ORV heat exchange plates includes the following steps: The test piece (2) is vertically suspended and fixed on the frame (1); The test liquid is injected into the storage tank (7); Start the circulation pump, and the test liquid is sprayed onto the surface of the test piece (2) through the spray assembly. Under the action of gravity, it flows down along the surface of the test piece (2) and back to the storage tank (7). The flow rate of the liquid at the bottom of the test piece (2) is obtained by the flow rate detection component (6), and the output power of the circulation pump and / or the flow rate of the spray component are adjusted to make the flow rate reach a predetermined value. A scouring test is conducted according to a predetermined test cycle to detect the morphology and / or thickness of the coating on the surface of the test piece (2).

10. The seawater erosion corrosion accelerated test method for ORV heat exchanger plates according to claim 9, characterized in that, The predetermined value is the actual measured flow velocity of the seawater at the bottom of the open-frame gasifier equipment in the target sea area, or 1.2 to 3 times the actual measured flow velocity.

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