A method for detecting the tightness of a methanol system of a generator

Abstract

The application discloses a kind of generator methanol system tightness detection methods, it is applicable to large ship generator methanol common rail system machine outer double-wall pipe detection.This method is implemented in four stages: first, the annular space of double-wall pipe outer pipe is filled with 1.5~3.5bar detection gas, to complete the outer pipe tightness verification with spray pot leak detection;Again, keep the outer pipe pressure, 8~10bar gas is filled into inner pipe, and the inner pipe leakage state is judged by annular space pressure sensor;Subsequently, the machine inside and outside system is separated by cross-connection, and whether the balloon expands at the connection module is used to distinguish the leakage area;Finally, the machine outside double-wall pipe is divided into three sections to form independent loop, and the leakage point is located by checking and segmenting liquid inlet pipe and liquid return pipe step by step.The application is strict in detection, accurate in positioning, can quickly check high-pressure methanol system leakage, fills the blank of large ship generator methanol machine outside system tightness detection method, and guarantees the safe and stable operation of system under 600bar high-pressure working condition.

Description

Technical Field

[0001] This invention relates to the field of marine power system testing technology, specifically to a method for testing the tightness of a generator methanol system. Background Technology

[0002] Currently, while the methanol common rail system for large ship generators has undergone bench testing, its external auxiliary systems have not been verified on actual ships. The key to the operation of the external methanol system lies in its airtightness, requiring stable operation under 600 bar high pressure. Given methanol's low viscosity, strong permeability, and toxicity, double-walled pipe connections are used throughout the system in the engine room area to ensure operational safety.

[0003] In existing technologies, there is a lack of a systematic, efficient, and accurate method for leak detection in methanol generator systems. Especially during the troubleshooting phase after system installation, it is often difficult to quickly locate leaks, particularly in the internal pipes, where leaks cannot be visually observed. This makes the troubleshooting process time-consuming and labor-intensive, impacting the construction and operational efficiency of ships. Furthermore, traditional external pipe pressure testing methods are insufficient for accurately determining leaks in the internal pipes under high-pressure operating conditions.

[0004] Therefore, it is necessary to provide a method for detecting the tightness of a generator methanol system to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a leak detection method suitable for methanol common rail systems of large ship generators, which can accurately locate leak points in layers and sections.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for testing the tightness of a generator methanol system includes the following steps:

[0008] Phase 1: Perform a leak test on the outer pipe of the double-walled pipe of the generator methanol system. Fill the annular space between the outer and inner pipes with test gas, maintaining the pressure at 1.5~3.5 bar. Use a spray bottle to check all flange or ferrule connections on the outer pipe. If bubbles are observed, it is determined that there is a leak in the outer pipe and the leak is repaired. If there are no bubbles, it is determined that there is no leak in the outer pipe, and proceed to Phase 2.

[0009] The second stage involves conducting a leak test on the inner tube of the double-walled pipe of the generator methanol system, maintaining a stable pressure of 1.5~3.5 bar within the annular space, and introducing 8~10 bar of test gas into the inner tube. A pressure sensor is installed within the annular space of the double-walled pipe to monitor the pressure rise and fall trend within the annular space. Based on the pressure difference between the inner and outer pipes and the pressure increase per unit time, the system determines whether the inner tube is leaking, the size of the leak, and preliminarily estimates the leak range.

[0010] The third stage: After initially determining that there is a leak in the inner tube, the leak area is divided and determined. The internal and external gas detection systems are separated by a bridging method. A balloon is placed on the internal interface of the generator body connection module. If the balloon inflates, the leak is determined to be from the internal system of the generator. If the balloon does not inflate, the leak is determined to be from the external system of the generator.

[0011] Phase 4: Once the leak is determined to originate from the external system, the external double-walled pipe of the generator methanol system is first divided into three sections: from the high-pressure pump outlet to the double-walled pipe inlet, from the leaking module to the connecting module, and the inlet module. Each section's inlet and return pipes are connected by a jumper pipe to form an independent double-walled pipe loop. Each loop is checked one by one to locate the leaking loop. Then, the inlet and return pipes of the leaking loop are separated. First, the inlet pipe is checked for leakage. If the inlet pipe is not leaking, it is determined that the leakage is in the return pipe of the loop. The specific leaking pipe section is identified and the leak test is completed.

[0012] Preferably, the detection gas is nitrogen.

[0013] Preferably, in the fourth stage, the tightness of the pipe section installation is confirmed by checking the sealing surface, alignment status, installation torque, and three-dimensional error of the piping system installation.

[0014] Preferably, in the fourth stage, after the system is reset and the inner tube is pressurized, the square flange of the return pipe connection module is opened to observe the leakage situation at that point in order to determine the direction of the gas source.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. It fills the gap in the testing method for the airtightness of the external methanol engine system of large ship generators and forms a standardized testing process.

[0017] 2. By adopting the strategy of "from the outside to the inside, segmented isolation, and step-by-step investigation", the source of leakage can be quickly identified and the leakage point can be accurately located through a four-level progressive investigation of the outer pipe, inner pipe, interval, and pipe section, which greatly improves the investigation efficiency.

[0018] 3. Adaptable to 600bar high-pressure methanol common rail systems, meeting the rapid maintenance needs during ship construction and operation, and improving system safety and operation and maintenance efficiency. Attached Figure Description

[0019] Figure 1 This is a pipeline diagram of the method for testing the tightness of a generator methanol system;

[0020] Figure 2 This is a schematic diagram illustrating the principle of a method for testing the tightness of a generator methanol system;

[0021] Among them, 1-double-walled pipe, 2-high-pressure pump, 3-leakage module, 4-connection module, 5-engine inlet module, 6-generator, 7-third deck, 8-methanol day tank, 9-methanol supply unit, 10-methanol filter, 11-valve assembly unit, 12-upper deck, 13-first deck, 14-engine room platform Detailed Implementation

[0022] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and not for limiting the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixed connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, terms such as "upper," "lower," "bottom," and "top" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements of this invention, and do not specifically refer to any component or element in this invention, and should not be construed as limiting this invention.

[0025] like Figures 1 to 2 As shown, this invention provides a method for testing the tightness of a generator methanol system. Its core design concept is to employ a phased, segmented elimination method for complex external double-walled pipe systems. The following description uses a specific implementation scenario based on real-ship testing experience with the high-pressure methanol system of a generator on a 16,000 TEU container ship.

[0026] Test Preparation: First, confirm that the external double-walled pipe of the generator methanol system is installed correctly. Prepare tools such as a nitrogen source, pressure regulating valve, pressure gauge, pressure sensor, hoses, connectors, spray bottle, foaming solution, and balloon. Install the pressure sensor at an appropriate position in the annular space of the double-walled pipe for continuous pressure monitoring.

[0027] Phase 1 Implementation: The goal of this phase is to ensure the airtightness of the outer pipe of the double-walled pipe, which is the foundation for subsequent testing. Nitrogen gas is introduced into the annular space between the outer and inner pipes of double-walled pipe 1, and the pressure is maintained steadily at 2.0 bar. Operators use a spray bottle filled with foaming agent to spray all possible leak points on the outer pipe, such as flange connections and compression fittings, and carefully observe. If bubbles continue to appear at a certain point, it indicates a leak in the outer pipe at that location, requiring tightening or sealing until the bubbles disappear. Only after confirming that all outer pipe connections are leak-free can the next phase proceed.

[0028] Phase Two Implementation: While maintaining stable pressure in the annular space, nitrogen is introduced into the inner pipe of the methanol system, raising the pressure to 9 bar. At this point, the pressure in the inner pipe is significantly higher than the pressure in the annular space. Analysis is performed by monitoring the pressure sensor readings in the annular space in real time: if the annular space pressure remains stable or only decreases very slowly, the inner pipe is considered to be well-sealed; if the annular space pressure shows a continuous and significant upward trend, it indicates a leak in the inner pipe, with high-pressure nitrogen entering the annular space through the leak point, causing the pressure increase. Based on the rate of pressure increase per unit time, the size of the leak can be preliminarily determined. Combined with the system piping layout, the pipe section where the leak might occur can be preliminarily predicted based on the time and rate of pressure increase, such as: near the high-pressure pump section, the middle section, or near the generator section.

[0029] Phase Three Implementation: After Phase Two determined that a leak existed in the internal pipe and preliminarily estimated the leak area, it was necessary to determine whether the leak source was inside the generator body (internal system) or in the external piping (external system). A jumper hose was used to create an independent loop in the external piping system at the connection module, isolating the nitrogen supply between the internal and external systems. Then, an uninflated balloon was placed on the internal interface of the generator body connection module. The balloon's state was observed: if the balloon gradually inflated, it indicated that nitrogen was leaking from inside the generator body through this interface, thus determining that the leak originated from the internal system; if the balloon remained deflated, it indicated that no gas was leaking from the internal interface, thus determining that the leak originated from the isolated external system.

[0030] Phase Four Implementation: Once the leak is determined to originate from the external system, a detailed segmentation and localization of the complex external piping is required. First, loop-level localization is performed: the external double-walled piping system is divided into three logical segments—the segment from the outlet of high-pressure pump 2 to the inlet of double-walled pipe 1, the segment from leak module 3 to connection module 4, and the segment entering the machine module 5. By bridging the external pipes, the inlet and return pipes of each segment are connected, forming three independent, closed double-walled pipe detection loops. Then, the detection processes of Phases One and Two are repeated sequentially for these three loops: external pipe pressure testing for leaks, and internal pipe pressurization to observe changes in the annular space pressure. The loop where the annular space pressure rises significantly is the loop with the leak.

[0031] Next, pipe-level location is performed: After locating the leaking loop, it's necessary to further determine whether the leak is in the inlet or return pipe of that loop. Remove the bridging between the inlet and return pipes of that loop, and first inspect the inlet pipe section separately. By checking the integrity of the sealing surfaces at both ends of the inlet pipe, the accuracy of the installation alignment, whether the installation torque meets standards, and whether the three-dimensional installation error of the piping system is within allowable limits, the installation tightness is comprehensively assessed. If all conditions are met, it is initially assumed that the inlet pipe is leak-free. Then, the system piping is reset, and 9 bar of nitrogen is injected into the inner pipe again. Subsequently, the square flange of the return pipe located at the connection module of that loop is opened. Observe whether there is obvious gas ejection or leakage signs: if so, based on the pipeline direction, it can be determined that the gas originates from the return pipe, thus ultimately confirming that the leak point is located in the return pipe of that loop or its connection point; if there is no leak, the assumption of the inlet pipe needs to be re-examined, or the bridging area needs to be checked. Through this method, the leak point can be located to a specific pipe segment or joint, completing the tightness verification and troubleshooting.

[0032] In this embodiment, the above method was successfully used to detect and locate leaks in the actual ship system, ensuring the stable operation of the methanol medium at 600 bar pressure. This method has clear steps and rigorous logic, effectively solving the problems of difficult leak detection and location in high-pressure methanol double-walled pipe systems.

[0033] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for detecting the tightness of a generator methanol system, characterized in that, Includes the following steps: Phase 1: Perform a leak test on the outer pipe of the double-walled pipe of the generator methanol system. Fill the annular space between the outer and inner pipes with test gas, maintaining the pressure at 1.5~3.5 bar. Use a spray bottle to check all flange or ferrule connections on the outer pipe. If bubbles are observed, it is determined that there is a leak in the outer pipe and the leak is repaired. If there are no bubbles, it is determined that there is no leak in the outer pipe, and proceed to Phase 2. The second stage involves conducting a leak test on the inner tube of the double-walled pipe of the generator methanol system, maintaining a stable pressure of 1.5~3.5 bar within the annular space, and introducing 8~10 bar of test gas into the inner tube. A pressure sensor is installed within the annular space of the double-walled pipe to monitor the pressure rise and fall trend within the annular space. Based on the pressure difference between the inner and outer pipes and the pressure increase per unit time, the system determines whether the inner tube is leaking, the size of the leak, and preliminarily estimates the leak range. The third stage: After initially determining that there is a leak in the inner tube, the leak area is divided and determined. The internal and external gas detection systems are separated by a bridging method. A balloon is placed on the internal interface of the generator body connection module. If the balloon inflates, the leak is determined to be from the internal system of the generator. If the balloon does not inflate, the leak is determined to be from the external system of the generator. Phase 4: Once the leak is determined to originate from the external system, the external double-walled pipe of the generator methanol system is first divided into three sections: from the high-pressure pump outlet to the double-walled pipe inlet, from the leaking module to the connecting module, and the inlet module. Each section's inlet and return pipes are connected by a jumper pipe to form an independent double-walled pipe loop. Each loop is checked one by one to locate the leaking loop. Then, the inlet and return pipes of the leaking loop are separated. First, the inlet pipe is checked for leakage. If the inlet pipe is not leaking, it is determined that the leakage is in the return pipe of the loop. The specific leaking pipe section is identified and the leak test is completed.

2. The method for detecting the tightness of a generator methanol system according to claim 1, characterized in that: The detection gas is nitrogen.

3. The method for detecting the tightness of a generator methanol system according to claim 1, characterized in that: In the fourth stage, the tightness of the pipe section installation is confirmed by checking the sealing surface, alignment status, installation torque, and three-dimensional error of the piping system installation.

4. The method for detecting the tightness of a generator methanol system according to claim 1, characterized in that: In the fourth stage, after the system is reset and the inner tube is pressurized, the square flange of the return pipe connection module is opened to observe the leakage situation and determine the direction of the gas source.

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