Purging system and purging method for a ship's steam pipe network

Abstract

The present application relates to a blowing system and a blowing method for a steam pipe network of a ship. The blowing system comprises a temporary blowing pipe, an inlet end of which is connected with a steam pipe to receive steam provided by a boiler. A blowing control valve and a silencer are sequentially arranged on the temporary blowing pipe, and a discharge port is arranged at an end of the temporary blowing pipe. The temporary blowing pipe passes through a steam turbine generator unit and an upper module reheating system, and is isolated from the steam turbine generator unit and the upper module reheating system. The blowing system has a preheating mode and an intermittent blowing mode. In the preheating mode, the blowing control valve is kept open, and a pressure control valve is opened at a preset opening degree, so that the steam fills the steam pipe and the temporary blowing pipe and reaches a preset temperature. In the intermittent blowing mode, the blowing control valve is closed, and the pressure control valve is fully opened, so that the steam fills the steam pipe and the temporary blowing pipe and reaches a preset pressure, and when the temporary blowing pipe reaches the preset pressure, the blowing control valve is quickly opened to make the steam be instantaneously released.

Description

Technical Field

[0001] This invention relates to the field of marine engineering equipment technology, and in particular to a purging system and method for a ship's steam pipeline network. Background Technology

[0002] FLNG is a floating offshore facility that integrates natural gas liquefaction, storage, loading and unloading. Its core processes, such as driving steam turbines and heating reboilers in the liquefaction process, are highly dependent on a stable and clean high-temperature and high-pressure steam pipeline network.

[0003] After a new unit is put into operation or undergoes a major overhaul, the steam system pipelines will inevitably contain impurities such as welding slag, rust, and grease. If these impurities are not thoroughly purged, the high-speed flowing steam will carry them to precision equipment such as turbines and heat exchangers, causing severe erosion, scaling, and even equipment damage, leading to unplanned shutdowns. The consequences are particularly severe on FLNGs located far from shore-based support.

[0004] Current purging methods have limitations when applied to FLNG: 1. Long purging cycles, such as the procurement, deployment, and commissioning of temporary steam sources, affect the commissioning schedule of expensive vessels and increase equipment investment costs. 2. Traditional pressure-stabilized continuous circulation purging methods consume a large amount of steam, which is unsuitable for the limited fresh water and fuel resources of FLNG. Summary of the Invention

[0005] One objective of this invention is to overcome the shortcomings of existing technologies and provide a purging system for ship steam pipelines. To solve the above-mentioned technical problems, this invention adopts the following technical solution:

[0006] A purging system for a ship's steam network, the ship's steam network including a boiler, a steam turbine generator set, an upper module reheating system, and steam pipelines, the boiler being connected to the steam turbine generator set and the upper module reheating system via steam pipelines, the steam pipelines being equipped with pressure control valves; the purging system includes: The temporary purging pipeline is connected to the steam pipeline at its inlet end to receive steam supplied by the boiler. The temporary purging pipeline is equipped with a purging control valve and a silencer in sequence. The end of the temporary purging pipeline is equipped with a discharge port. The temporary purging pipeline passes through the steam turbine generator set and the upper module reheating system, and is isolated from the steam turbine generator set and the upper module reheating system. The purging system has a preheating mode and an intermittent purging mode. In the preheating mode, the purging control valve remains open and the pressure control valve opens at a preset opening degree, so that steam fills the steam pipeline and the temporary purging pipeline and reaches the preset temperature. In intermittent purging mode, the purging control valve is closed and the pressure control valve is fully open, so that steam fills the steam pipeline and the temporary purging pipeline and reaches the preset pressure. When the temporary purging pipeline reaches the preset pressure, the purging control valve is quickly opened to release the steam instantly.

[0007] In one embodiment, the purging system for the ship's steam network includes a pipeline inspection device installed on a temporary purging pipeline and used to detect the pressure and temperature on the temporary purging pipeline.

[0008] In one embodiment, the purging system of the ship's steam network includes a purging detection device, which is installed on a temporary purging pipeline. The purging detection device includes a target inserter and a target plate. The target inserter is installed on the temporary purging pipeline, and the target plate is detachably fixed to the target inserter and can extend into the interior of the temporary purging pipeline.

[0009] In one embodiment, the temporary purge line includes: The first purging branch is connected to the steam pipeline at its inlet end. The first purging branch passes through the steam turbine generator set and is isolated from the steam turbine generator set. A purging control valve and a silencer are installed in sequence on the first purging branch. The second purging branch is connected in parallel with the first purging branch. The inlet end of the second purging branch is connected to the steam pipeline. The second purging branch passes through the upper module reheating system and is isolated from the upper module reheating system. A purging control valve and a silencer are installed sequentially on the second purging branch.

[0010] In one embodiment, the purging system for the ship's steam network also includes a control device connected to a pressure control valve. The ship is equipped with an inertial detection device, which is used to detect the ship's rolling motion; The control device is connected to the inertial detection device and is used to control the opening of the pressure control valve according to the amplitude of the ship's rolling motion.

[0011] In one embodiment, the inlet end of the turbine generator set is sealed with a blind flange during purging.

[0012] In one embodiment, during purging, the inlet end of the upper module reheating system is sealed with a blind flange.

[0013] In one embodiment, a drain valve and a drain valve are sequentially provided on the temporary purging line; and / or, Several pipe supports are installed on the outside of the temporary purging pipeline.

[0014] Another object of the present invention is to provide a purging method for a ship's steam pipeline network, which utilizes the purging system for a ship's steam pipeline network described in any of the above claims; the purging method includes: During the preparation phase, temporary purging pipelines, purging control valves, and silencers are installed, and the turbine generator set and the upper module reheating system are isolated. During the preheating stage, the purge control valve is opened, and the pressure control valve is opened at a preset opening degree, so that steam fills the steam pipeline and the temporary purge pipeline and reaches the preset temperature. During the intermittent purging phase, close the purging control valve and fully open the pressure control valve to allow steam to fill the steam pipeline and temporary purging pipeline and reach the preset pressure. When the temporary purging pipeline reaches the preset pressure, quickly open the purging control valve to release the steam instantly. During the testing and acceptance phase, after repeating the intermittent purging phase 3 to 4 times, a target plate is set on the temporary purging pipeline for target testing. The target quality is considered to be qualified if it meets the following requirements: within a 10mm×10mm area on the target plate, there are no more than 2 impact marks with a diameter not exceeding 0.5mm; and the purging is deemed qualified if two consecutive target tests are qualified.

[0015] In one embodiment, after the purging is deemed satisfactory, the method further includes: During the recovery phase, after the purging system has cooled to a safe temperature, the temporary purging pipelines, purging control valves, and silencers are removed, and the ship's steam network is restored to normal operation.

[0016] As can be seen from the above technical solution, the present invention has at least the following advantages and positive effects: In this invention, the purging system includes a temporary purging pipeline, the inlet of which is connected to a steam pipeline to receive steam supplied by the boiler. A purging control valve and a silencer are sequentially installed on the temporary purging pipeline, and a discharge port is located at the end of the pipeline. The temporary purging pipeline passes through the turbine generator set and the upper module reheating system, and is isolated from both. The purging system has a preheating mode and an intermittent purging mode. In the preheating mode, the purging control valve remains open, and the pressure control valve is opened at a preset opening degree, allowing steam to fill the steam pipeline and the temporary purging pipeline and reach a preset temperature. In the intermittent purging mode, the purging control valve is closed, and the pressure control valve is fully open, allowing steam to fill the steam pipeline and the temporary purging pipeline and reach a preset pressure. When the temporary purging pipeline reaches the preset pressure, the purging control valve is quickly opened, causing the steam to be released instantaneously.

[0017] This purging system adds temporary purging pipelines to the ship's existing steam network to purge the steam pipelines, turbine generator sets, and the inlet pipes of the upper module reheating system, ensuring the safety of the steam network equipment. The purging system utilizes the original ship boiler as the sole steam source throughout the entire process, eliminating the need for additional temporary boilers or external steam sources. This saves on the procurement, deployment, and commissioning of temporary boilers and reduces equipment investment costs.

[0018] The purging system features a preheating mode and an intermittent purging mode. The preheating mode preheats the steam and temporary purging lines, preventing thermal stress damage during purging due to excessive temperature differences. It also helps loosen accumulated impurities such as scale and welding slag within these lines, facilitating thorough removal. The intermittent purging mode allows for steam accumulation and intermittent pulsed release, creating a "burst"-like thermal shock force. The resulting high-speed airflow shock wave carries away impurities from the steam and temporary purging lines, achieving efficient and thorough removal and ensuring no blind spots in the purging process, while minimizing steam consumption. This preheating-intermittent purging method not only guarantees thorough purging but also reduces steam and freshwater consumption, making the system more suitable for the limited resources of offshore platforms and effectively solving the problem of high steam consumption in traditional pressure-stabilized circulating purging. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the purging system of a ship steam pipeline network according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic flowchart of a method for purging a ship's steam pipeline network according to an embodiment of the present invention.

[0021] The annotations in the attached figures are explained as follows: 10-Boiler; 20-Steam turbine generator set; 30-Upper module reheating system; 40-Steam pipeline; 41-Pressure control valve; 42-Desuperheater; 43-Condensate collection unit; 44-Steam trap; 50 - Temporary purge line; 51 - Purge control valve; 52 - Silencer; 53 - First purge branch; 54 - Second purge branch; 60-Pipeline inspection device; 70-Purge inspection device; 71-Target inserter; 72-Target plate. Detailed Implementation

[0022] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations herein are for illustrative purposes only and not intended to limit the present invention.

[0023] In the description of this application, it should be understood that, in the embodiments shown in the accompanying drawings, the indications of direction or positional relationships (such as up, down, left, right, front, and back, etc.) are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. These descriptions are appropriate when these elements are in the positions shown in the accompanying drawings. If the description of the positions of these elements changes, these directional indications also change accordingly.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0025] The purging system for ship steam pipelines of this invention (hereinafter referred to as the purging system) is mainly used for purging the steam pipelines of FLNG. FLNG is a floating liquefied natural gas production, storage, and offloading (LNG) facility, which is a floating offshore facility integrating natural gas liquefaction, storage, and loading / unloading. FLNG can be converted from LNG carriers (liquefied natural gas transport vessels), retaining the original LNG carrier's boilers, turbine units, etc., and can accordingly add several turbine generator sets and several topside module steam reheating systems, depending on the specific circumstances.

[0026] Therefore, for retrofitted FLNGs, the purging system of this invention can utilize steam generated by the boilers of the original LNG carrier to purify the steam network of the retrofitted FLNG, including both the old and new networks, to ensure the safe and reliable operation of the FLNG. For new FLNGs, the purging system of this invention can utilize steam generated by the boilers configured on the new FLNG to purify the steam network of the new FLNG, to ensure the safe and reliable operation of the FLNG.

[0027] refer to Figure 1 For ships, such as those retrofitting FLNG or building new FLNG, the steam network may include a boiler 10, a turbine generator set 20, an upper module reheating system 30, and steam pipelines 40. The boiler 10 is connected to the turbine generator set 20 and the upper module reheating system 30 via steam pipelines 40. A pressure control valve 41 is installed on the steam pipelines 40.

[0028] Optionally, the ship's steam network may also include a desuperheater 42 installed downstream of the pressure control valve 41. The desuperheater 42 is mainly used to reduce the steam temperature. It can adjust the high-temperature steam output from the boiler 10 to the safe temperature range allowed by the turbine generator set 20 and the purging process, prevent the overheated steam from damaging downstream equipment, and help control the purging temperature to avoid thermal stress in the pipeline or equipment due to excessive temperature difference.

[0029] Optionally, the ship's steam network may also include a condensate collection unit 43 and a steam trap 44. The condensate collection unit 43 is connected to the outlet end of the boiler 10 and is arranged in parallel with the steam pipeline 40. The steam trap 44 is installed on the pipeline connecting the condensate collection unit 43 and the boiler 10. The steam trap 44 is used to promptly remove condensate generated during the pipeline start-up phase to prevent water hammer, pipeline vibration, and impact damage. The condensate collection unit 43 is mainly used to collect condensate, preventing water blockage from affecting steam flow and purging efficiency, and ensuring that the steam entering the steam pipeline 40 is in a dry saturated or superheated state.

[0030] refer to Figure 1 The purging system includes a temporary purging line 50, the inlet of which is connected to a steam line 40 to receive steam supplied by the boiler 10. A purging control valve 51 and a silencer 52 are sequentially installed on the temporary purging line 50, and a discharge port is provided at the end of the temporary purging line 50.

[0031] The purge control valve 51 is mainly used to control the steam flow of the temporary purge pipeline 50 and to achieve pulsed steam release. The silencer 52 works in conjunction with the purge control valve 51, significantly reducing noise during high-pressure steam discharge (reducing strong noise from 110dB+ to below 85dB), meeting on-site safety and environmental protection requirements, and also helping to reduce exhaust velocity and minimize the impact of steam emissions on the surrounding environment. The discharge port of the temporary purge pipeline 50 is connected to the external environment, allowing steam to be discharged into the atmosphere after passing through the silencer.

[0032] refer to Figure 1 The temporary purging pipeline 50 passes through the turbine generator set 20 and the upper module reheating system 30, and is isolated from the turbine generator set 20 and the upper module reheating system 30.

[0033] The turbine generator set 20 and the upper module reheating system 30 are the protected objects and target equipment of the purging system. The purpose of the purging system is to remove impurities from the inlet pipes of the turbine generator set 20 or the upper module reheating system 30, preventing impurities from entering the turbine generator set 20 and causing blade damage or affecting the operation of the upper module reheating system 30. When purging the inlet pipes of the turbine generator set 20 and the upper module reheating system 30, the purging system must first isolate and protect the turbine generator set 20 and the upper module reheating system 30 to prevent steam from carrying impurities into them.

[0034] See Figure 1 In one embodiment, the temporary purging line 50 includes a first purging branch 53 and a second purging branch 54. The inlet end of the first purging branch 53 is connected to the steam line 40, and the first purging branch 53 passes through the steam turbine generator set 20 and is isolated from the steam turbine generator set 20. A purging control valve 51 and a silencer 52 are sequentially provided on the first purging branch 53.

[0035] The number of first purging branches 53 can be multiple, and multiple first purging branches 53 can be connected in parallel and arranged one-to-one with several steam turbine generator sets 20, so as to purge the inlet pipes of each steam turbine generator set 20 respectively.

[0036] Optionally, during purging, the inlet end of the turbine generator set 20 can be sealed with a blind flange.

[0037] like Figure 1 As shown, the second purging branch 54 is connected in parallel with the first purging branch 53. The inlet end of the second purging branch 54 is connected to the steam pipeline 40. The second purging branch 54 passes through the upper module reheating system 30 and is isolated from the upper module reheating system 30. A purging control valve 51 and a silencer 52 are sequentially provided on the second purging branch 54.

[0038] The number of second purging branches 54 can be multiple, and the multiple second purging branches 54 can be connected in parallel and arranged one-to-one with several platform upper module reheating systems 30, so as to purge the inlet pipes of each platform upper module reheating system 30 respectively.

[0039] Optionally, during purging, the inlet end of the upper module reheating system 30 can be sealed with a blind flange.

[0040] By setting up the first purging branch 53 and the second purging branch 54, the turbine generator set 20 and the upper module reheating system 30 can be purged independently or simultaneously, improving the operational flexibility of the purging system.

[0041] In embodiments of the present invention, the purging system has a preheating mode and an intermittent purging mode. In the preheating mode, the purging control valve 51 remains open, and the pressure control valve 41 is opened at a preset opening degree, allowing steam to fill the steam pipeline 40 and the temporary purging pipeline 50 and reach a preset temperature. In the intermittent purging mode, the purging control valve 51 is closed, and the pressure control valve 41 is fully open, allowing steam to fill the steam pipeline 40 and the temporary purging pipeline 50 and reach a preset pressure. When the temporary purging pipeline 50 reaches the preset pressure, the purging control valve 51 is quickly opened to release the steam instantaneously.

[0042] The preheating mode preheats the steam pipeline 40 and the temporary purging pipeline 50, preventing thermal stress damage to the pipelines caused by excessive temperature differences during purging. It also helps loosen accumulated impurities such as oxide scale and welding slag within the steam pipeline 40 and the temporary purging pipeline 50, facilitating thorough removal of these impurities. The intermittent purging mode allows for the accumulation and intermittent pulsed release of steam, creating a "burst"-like thermal shock force. The resulting high-speed airflow shock wave carries away impurities from the steam pipeline 40 and the temporary purging pipeline 50, achieving efficient and thorough removal of impurities and ensuring no blind spots during purging.

[0043] In one embodiment, a drain valve and a drain valve may be sequentially installed on the temporary purge line 50 to form a drainage path, thereby facilitating the timely discharge of condensate within the temporary purge line 50 and preventing water hammer. For example, the drain valve and drain valve may be installed on each of the first purge branches 53 and upstream of the purge control valve 51 to discharge condensate from each of the first purge branches 53. The drain valve and drain valve may also be installed on each of the second purge branches 54 and upstream of the purge control valve 51 to discharge condensate from each of the second purge branches 54.

[0044] Of course, at other nodes on each of the first purge branch 53 and each of the second purge branch 54, such as other locations where condensate needs to be drained, steam traps and drain valves can be installed to form multiple drainage paths, depending on the specific situation.

[0045] In one embodiment, several pipe supports are provided on the outside of the temporary purging pipeline 50, such as several pipe supports on the outside of each first purging branch 53 and each second purging branch 54. The pipe supports are used to support the temporary purging pipeline 50, such as the first purging branch 53 and the second purging branch 54, and to withstand the purging reaction force, thereby ensuring the stable and reliable operation of the purging.

[0046] refer to Figure 1In one embodiment, the purging system of the ship's steam network includes a pipeline detection device 60, which is installed on a temporary purging pipeline 50 and used to detect the pressure and temperature on the temporary purging pipeline 50. For example, each first purging branch 53 and each second purging branch 54 is provided with a pipeline detection device 60 to detect the pressure and temperature on the first purging branch 53 and the second purging branch 54, respectively.

[0047] Optionally, the pipeline detection device 60 may include a pressure gauge or pressure sensor to detect pipeline pressure. The pipeline detection device 60 may also include a thermometer or thermocouple to detect pipeline temperature.

[0048] By setting up the pipeline detection device 60, the steam pressure and temperature on the temporary purging pipeline 50 can be detected in real time, providing data support for controlling the pressure regulating valve 41 and the purging control valve 51, ensuring the reliable operation of the purging system, and ensuring that the purging system operates within the set safe pressure and temperature range.

[0049] See Figure 1 In one embodiment, the purging system of the ship's steam network includes a purging detection device 70, which is installed on a temporary purging pipeline 50. For example, a set of purging detection devices 70 can be installed on each of the first purging branches 53 and each of the second purging branches 54 to detect the effect and quality of purging.

[0050] The purging detection device 70 may include a target inserter 71 and a target plate 72, with the target inserter 71 disposed on the temporary purging line 50. For example, the target inserter 71 may be installed in a pre-reserved mounting port on each of the first purging branches 53. The target inserter 71 may also be installed in a pre-reserved mounting port on each of the second purging branches 54.

[0051] Optionally, the target plate 72 can be made of polished copper or aluminum. The target plate 72 is detachably fixed to the target inserter 71 and can extend into the interior of the temporary purge line 50. For example, the target plate 72 can be fixed to the target inserter 71 on each of the first purge branches 53 and the second purge branches 54 using screws, etc., and can extend into the corresponding line to detect the cleanliness of the steam in the line, thereby reflecting the purging effect and quality in the line.

[0052] In this embodiment, by setting up the purging detection device 70, the purging effect and quality can be detected and judged, ensuring that the purging effect is quantifiable and traceable, and ensuring that the purging effect and quality can meet the commissioning and subsequent operation requirements of the turbine generator set 20 and the upper module reheating system 30.

[0053] In one embodiment, the purging system for the ship's steam network further includes a control device connected to the pressure control valve 41. Optionally, the control device may be a PLC (Programmable Logic Controller).

[0054] Optionally, the control device can be connected to the purge control valve 51 and the pipeline detection device 60, such as a pressure sensor and a temperature sensor, respectively. The control device can control the opening and closing of the purge control valve 51, or control the opening and closing and opening degree adjustment of the pressure control valve 41, based on the detection signal from the pipeline detection device 60.

[0055] Optionally, the vessel is equipped with an inertial detection device, such as an inertial sensor. The inertial detection device is used to detect the vessel's rolling motion. The control device is connected to the inertial detection device and is used to control the opening degree of the pressure control valve 41 according to the amplitude of the vessel's rolling motion.

[0056] In this embodiment, the control device can monitor the hull roll amplitude in real time. When the hull roll amplitude exceeds the preset threshold (±5°), the control device can automatically fine-tune the opening of the pressure control valve 41 (±1%~2%), thereby dynamically maintaining the steam flow rate and ensuring that the cleaning force ratio (CFR≥1.5) always meets the standard. This helps to solve the industry problem of uneven purging effect and incomplete impurity removal caused by swaying at sea, and helps the purging system to better adapt to the FLNG marine operating conditions.

[0057] The ship steam network purging system of this embodiment adds a temporary purging pipeline 50 to the existing steam network to purge the steam pipeline 40, the turbine generator set 20, and the inlet pipeline of the upper module reheating system 30, which helps ensure the safety of the steam network equipment. The purging system uses the original ship boiler 10 as the sole steam source throughout the entire process, eliminating the need for additional temporary boilers or external steam sources, thus saving on the procurement, deployment, and commissioning processes of temporary boilers and reducing equipment investment costs.

[0058] The purging system features a preheating mode and an intermittent purging mode. The preheating mode preheats the steam pipeline 40 and the temporary purging pipeline 50, preventing thermal stress damage during purging due to excessive temperature differences. It also helps loosen accumulated impurities such as oxide scale and welding slag within these pipelines, facilitating thorough removal. The intermittent purging mode allows for steam accumulation and intermittent pulsed release, creating a "burst"-like thermal shock force. The resulting high-speed airflow shock wave carries away impurities from the steam pipeline 40 and the temporary purging pipeline 50, achieving efficient and thorough removal and ensuring no blind spots in the purging process. This preheating-assisted intermittent purging method not only guarantees thorough purging but also helps reduce steam and freshwater consumption, making the purging system more suitable for the limited resources of offshore platforms and effectively solving the problem of high steam consumption in traditional pressure-stabilized circulating purging.

[0059] See Figure 2 The present invention also provides a method for purging a ship's steam pipeline network, which uses the purging system for the ship's steam pipeline network described in any of the above embodiments for purging.

[0060] The purging method includes: S10, Preparation stage: Install temporary purging pipeline 50, purging control valve 51 and silencer 52, and isolate turbine generator set 20 and upper module reheating system 30.

[0061] For example, the core of the preparation phase is to complete system isolation, temporary equipment installation, and safety protection, laying the foundation for purging operations. The specific operations are roughly as follows: System Isolation and Inspection: Confirm that the prefabrication, installation, hydrostatic testing, airtightness testing, and non-destructive testing (RT / UT) of the steam pipeline network for LNG to FLNG conversion are all completed and qualified, and that all relevant records are complete. Completely isolate the FLNG steam pipeline network and purging system from other systems. Install blind flanges on the turbine generator set 20 side to prevent purging impurities from entering the turbine generator set 20. Check that pipeline supports and hangers are installed in place, fixed supports are secure, sliding supports are not jammed, and pipeline thermal displacement markings are clear.

[0062] Equipment dismantling and temporary component installation: Dismantle steam pipeline internals, pressure reducing control valves, thermometers, thermocouple sheaths, desuperheater 42 nozzles, and other components that are easily damaged or obstruct steam flow, and install temporary short pipes of the same specifications. Dismantle the interface valves of turbine generator set 20 and install temporary blind pipes of the same specifications. Close and secure the valves for high-pressure steam to the upper module reheating system 30, as well as the bypass and desuperheater 42 discharge valves; replace the flow meter and gate valve of turbine generator set 20 with temporary short pipes. Close and secure the pipeline valves of the upper module reheating system 30 and install blind flanges.

[0063] Temporary purging equipment installation: Install temporary purging piping 50, including temporary carbon steel fittings, elbows, reducers, etc., and connect temporary purging piping 50 to silencer 52 and target inserter 71. Temporary purging piping 50 is equipped with steel pipe supports adapted to fluid pressure to cope with purging reaction forces. A purging control valve 51 is installed at the end of temporary purging piping 50 to control steam pulse release. Temporary thermocouples, thermometers, and pressure gauges are installed to monitor temperature and pressure parameters during the purging process. All drip lines (such as drainage paths) extend to the ground, and warning tape fencing is erected around them to remind personnel of the risk of hot condensate discharge.

[0064] Safety and personnel preparation: Set up protective barriers and warning signs around silencer 52 and temporary purging pipeline 50 to clearly define the work boundaries and restrict unauthorized personnel from entering; the operators should be familiar with the purging process, parameters and emergency plan after technical briefing and safety training, and be equipped with personal protective equipment (PPE) and earplugs; identify the pipeline thermal expansion and vibration risk areas in advance, set up isolation zones and safe operating parameters to reduce the impact of vibration.

[0065] S20, preheating stage: open the purge control valve 51 and open the pressure control valve 41 at a preset opening degree, so that steam fills the steam pipeline 40 and the temporary purge pipeline 50 and reaches the preset temperature.

[0066] For example, the main purpose of the preheating stage is to preheat the pipeline to avoid thermal stress damage caused by excessive temperature differences during purging, and to loosen accumulated impurities in the pipeline, such as oxide scale and welding slag. The specific operation is roughly as follows: Start the two core process boilers 10 retained from the original LNG ship and put them in an idling state. Discharge the steam to the condensate collection unit 43 through the steam trap 44 on the branch line connected in parallel with the steam pipeline 40. Open the purge control valve 51 on the temporary purge pipeline 50 before the silencer 52, and open all manual discharge ports (non-steam traps) and drainage paths on the temporary purge pipeline 50. The operator controls the entire process until only pure steam is discharged (without condensate or impurities), achieving precise adaptation between the old and new pipeline networks.

[0067] The pressure control valve 41 is opened at a preset opening degree, for example, 5%, to preheat the entire steam pipeline 40 and the temporary purging pipeline 50. During the process, the temperature change is monitored in real time, the heating rate is controlled to be ≤50℃ / h, and the pipeline wall temperature is recorded every 15 minutes until the wall temperature rises to 300℃~450℃. The warm-up process is then maintained for 30~60 minutes.

[0068] During the warm-up process, continuously inspect the pipeline for any abnormal vibrations or leaks, and check for any deformation of the supports and hangers. If any abnormality is found, immediately close the pressure control valve 41, reduce the pressure and vent the system before troubleshooting and handling.

[0069] S30, during the intermittent purging phase, close the purging control valve 51 and fully open the pressure control valve 41, so that steam fills the steam pipeline 40 and the temporary purging pipeline 50 and reaches the preset pressure. When the temporary purging pipeline 50 reaches the preset pressure, quickly open the purging control valve 51 to release the steam instantly.

[0070] For example, the main purpose of the intermittent purging stage is to use an adaptive intermittent purging method to generate thermal shock through steam accumulation and pulse release, thereby achieving efficient removal of impurities and strictly controlling the cleaning force ratio (CFR) ≥ 1.5. The specific operation is roughly as follows: After the warm-up is completed, close all manual vents, close the purge control valve 51 on the temporary purge line 50, and fully open the pressure control valve 41. Gradually increase the steam supply through the original ship boiler 10 until the steam line 40 and the temporary purge line 50 are filled with steam and the required purge pressure, such as 42 barg, is reached.

[0071] During this process, the liquid level of the original ship boiler 10 can be adjusted in real time to be slightly higher than the normal liquid level, ensuring sufficient steam supply during the purging process and giving full play to the output advantages of the original ship boiler 10 without the need for additional steam.

[0072] During this process, the control device can monitor the hull roll amplitude in real time. When the roll amplitude exceeds the preset threshold (±5°), it automatically fine-tunes the opening of the pressure control valve 41 (±1%~2%) to maintain a stable steam flow rate, ensure that the cleaning force ratio meets the standard, and adapt to the rolling conditions at sea.

[0073] When the temporary purging line 50 reaches the preset pressure (e.g., 42 barg), quickly and fully open the purging control valve 51 to release steam in high-speed pulses. The thermal shock effect causes the pipe metal to contract, loosening internal deposits and impurities. The rapidly expanding steam then blows out the loosened impurities, thoroughly removing accumulated debris and ensuring a complete purging process. Operators must immediately evacuate the purging area to avoid the risk of high noise levels. Overpressure purging, welding, and hammering of the pipes are strictly prohibited during the purging process.

[0074] Continue purging until the pressure, feedwater level, and steam temperature of boiler 10 reach the allowable limits, or until the burner of boiler 10 automatically shuts off. Immediately close pressure control valve 41 to stop steam supply. Keep purging control valve 51 open. After the pressure of boiler 10 recovers and the pipeline cools down naturally, close purging control valve 51 to prepare for the next round of purging.

[0075] Repeat the above purging process several times, and then conduct purging quality testing and acceptance.

[0076] S40, Detection and acceptance stage: after repeating the intermittent purging stage for 3 to 4 times, arrange a target plate 72 on the temporary purging pipeline 50 for shooting test. The shooting test is considered qualified if the quality meets the following requirements: within a 10mm×10mm area on the target plate 72, there are no more than 2 impact marks with a diameter not exceeding 0.5mm; when two consecutive shooting tests are qualified, the purging is determined as qualified.

[0077] For example, the main purpose of the detection and acceptance stage is to detect and judge the purging effect, formulate clear acceptance criteria, and ensure that the pipeline cleanliness meets the commissioning requirements of the steam turbine generator unit 20. The specific operation is generally as follows: It can be understood that when repeating the purging process of the above intermittent purging stage, it is not necessary to install the target plate 72 for the first 3 to 4 times of purging, and the impurity content is fed back only through an online monitoring device (such as flow rate and pressure). Before each subsequent purging, the polished copper (or aluminum) target plate 72 is installed through the target inserter 71. After purging is completed, the target plate 72 is taken out, numbered and registered, and the surface condition of the target plate 72 is recorded.

[0078] The target plate 72 can be a surface-polished copper target plate, which extends into the steam flow channel inside the temporary purging pipeline 50 through the target inserter 71 during each purging. The exposure time for a single purging can be 20 minutes to 60 minutes. The insertion and removal of the target plate 72 can be completed without interrupting steam supply. Wear gloves when removing the target plate to avoid scratching the surface of the target plate 72 and getting scalded.

[0079] Acceptance criteria: The impact marks on the surface of the target plate 72 shall meet the requirements of industry specifications and the turbine manufacturer, and the specific criteria are: within the 10mm×10mm area in the region with the highest concentration of impurities on the target plate 72, there are no more than 2 impact marks with a diameter not exceeding 0.5mm. When two consecutive target plates 72 both meet the above criteria, the purging is determined as qualified.

[0080] Treatment for unqualified condition: If the detection of the target plate 72 does not meet the standard, adjust the purging pressure and pulse frequency, and continue intermittent purging until two consecutive target plates 72 meet the acceptance criteria. During the purging process, monitor the steam pressure, temperature and cleaning force ratio in real time to ensure CFR ≥ 1.5 and avoid incomplete cleaning.

[0081] In one embodiment, after the purging is qualified, the method further comprises: S50, Restoration stage: after the purging system is cooled to a safe temperature, remove the temporary purging pipeline 50, the purging control valve 51 and the muffler 52, and restore the normal operation of the marine steam pipeline network.

[0082] For example, the main purpose of the restoration stage is to restore the normal operation of the FLNG steam pipeline network after the purging is qualified. The specific operation is generally as follows: After the purging is deemed satisfactory, allow the steam pipeline 40 and the temporary purging pipeline 50 to cool to a safe operating temperature. Remove the temporary equipment such as the temporary purging pipeline 50, silencer 52, target inserter 71, and purging control valve 51. Reinstall the valves, instruments, pipeline internals, and other components of the previously removed steam pipeline network to restore the steam pipeline network to its normal operating configuration.

[0083] Before restoration, ensure that steam line 40 and temporary purging line 50 are fully depressurized and vents are open to avoid residual steam posing a safety hazard. Organize and archive relevant documents such as purging records and target plate 72 inspection reports.

[0084] In this embodiment, the purging method is strictly implemented in five stages: preparation, preheating, intermittent purging, testing and acceptance, and recovery. The preparation stage employs comprehensive safety measures, standardizing the isolation of the work area, personnel operations, and temporary pipeline installation, thus mitigating safety risks associated with high temperature, high pressure, and high noise. Operators are professionally trained, the process is controllable, and the emergency response plan is comprehensive, adapting to the safety requirements of the complex offshore operating environment for LNG-to-FLNG conversion. The entire purging process utilizes the original ship's two core process boilers 10 as the sole steam source, eliminating the need for additional temporary boilers or external steam sources. Low-pressure pre-purging and high-pressure pulse purging are used for both new and old pipelines. During the purging process, the steam flow rate can be adaptively adjusted in conjunction with the ship's swaying, thereby helping to thoroughly remove impurities such as welding slag and rust from the pipelines. This prevents impurities from entering the turbine generator set 20 and the upper module reheating system 30, effectively preventing equipment damage such as blade erosion and jamming, and reducing the risk of unplanned shutdowns. Multiple purgings followed by target plate 72 testing help reduce steam consumption and ensure that the purging effect and quality meet the commissioning and subsequent operation requirements of the turbine generator set 20 and the upper module reheating system 30.

[0085] The purging system and method for ship steam pipelines in this invention are adaptable to sea conditions with high purging stability. It incorporates a ship roll adaptive adjustment mechanism that monitors the ship's roll amplitude in real time, automatically fine-tunes the pressure control valve opening, maintains stable steam flow rate and cleaning force ratio, solves the problem of uneven purging effect caused by sea rolling, and ensures stable purging parameters within a ±6° roll range, thus adapting to the characteristics of FLNG floating operations at sea.

[0086] The purging system and method for ship steam pipelines in this invention are highly efficient, energy-saving, and cost-controllable. It utilizes the existing boilers of the LNG ship as the sole steam source to provide purging steam for both new and old pipelines, eliminating the need for additional temporary boilers or external steam sources. This eliminates the procurement, deployment, and commissioning processes of temporary boilers, significantly reducing equipment investment costs. Simultaneously, it optimizes the purging process and target plate inspection cycle, shortening the purging period and reducing steam and fresh water consumption. This helps adapt to the limited resources of offshore platforms and solves the problems of high costs and long construction periods caused by adding new equipment.

[0087] The ship steam pipeline purging system and method of this invention are safe, reliable, and compliant with HSE requirements. They employ comprehensive safety protection measures, standardize work area isolation, personnel operation, and temporary pipeline installation, and mitigate safety risks associated with high temperature, high pressure, and high noise. Operators are professionally trained, the process is controllable, and emergency plans are comprehensive, adapting to the safety requirements of the complex offshore operating environment for LNG to FLNG conversion. Specifically designed for the high temperature, high pressure, and high noise environment at sea, the system optimizes the design of temporary pipeline supports and work area isolation, sets safe operating parameters based on the original ship equipment layout, and pre-identifies pipeline thermal expansion and vibration risks, forming a safety protection system suitable for FLNG offshore operations.

[0088] The purging system and method for ship steam pipelines in this invention have clear acceptance standards and strong traceability. It establishes quantified target plate testing and acceptance standards, combined with a target plate numbering and registration system, ensuring that the purging effect is quantifiable and traceable, meeting the commissioning and subsequent operation requirements of equipment such as steam turbine generator sets. It can provide a replicable technical reference for similar LNG-to-FLNG conversion projects.

[0089] The purging system and method for ship steam pipelines according to embodiments of the present invention, in practical application, show that the purging scheme is suitable for sea conditions involving rolling and swaying. During the purging process, pressure and flow velocity remain stable, and the cleaning power ratio is consistently maintained above 1.5. After eight rounds of intermittent purging, two consecutive target plates passed inspection, with no more than two impact marks (diameter ≤ 0.5mm) within a 10mm × 10mm area on the target plates. Impurities at the junction of new and old pipelines were thoroughly removed, steam consumption was reduced by 32%, the purging period was shortened by 28%, and all pipelines passed purging without any abnormalities such as pipeline vibration or leakage.

[0090] The purging system and purging method for the ship steam pipeline network of this invention, after purging, ensure that the steam pipeline network returns to normal operation, the turbine generator set and the upper module reheating system are successfully commissioned, and there are no equipment failures caused by impurities entering.

[0091] The above embodiments are merely illustrative examples of structures. The structures in each embodiment are not fixed combinations. In the absence of structural conflicts, the structures in multiple embodiments can be arbitrarily combined and used.

[0092] Although the invention has been described with reference to several typical embodiments, it should be understood that the terminology used is illustrative and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A purging system for a ship's steam network, the ship's steam network comprising a boiler, a steam turbine generator set, an upper module reheating system, and steam pipelines, wherein the boiler is connected to the steam turbine generator set and the upper module reheating system via the steam pipelines, and a pressure control valve is provided on the steam pipelines; characterized in that, The purging system includes: A temporary purging pipeline is connected at its inlet end to the steam pipeline to receive steam supplied by the boiler. A purging control valve and a silencer are sequentially installed on the temporary purging pipeline. A discharge port is provided at the end of the temporary purging pipeline. The temporary purging pipeline passes through the steam turbine generator set and the upper module reheating system, and is isolated from the steam turbine generator set and the upper module reheating system. The purging system has a preheating mode and an intermittent purging mode. In the preheating mode, the purging control valve remains open and the pressure control valve is opened at a preset opening degree, so that steam fills the steam pipeline and the temporary purging pipeline and reaches the preset temperature. In the intermittent purging mode, the purging control valve is closed and the pressure control valve is fully open, so that steam fills the steam pipeline and the temporary purging pipeline and reaches the preset pressure. When the temporary purging pipeline reaches the preset pressure, the purging control valve is quickly opened to release the steam instantly.

2. The purging system for ship steam pipelines according to claim 1, characterized in that, It includes a pipeline testing device, which is installed on the temporary purging pipeline and is used to detect the pressure and temperature on the temporary purging pipeline.

3. The purging system for ship steam pipelines according to claim 1, characterized in that, The device includes a purging detection device, which is installed on the temporary purging pipeline. The purging detection device includes a target inserter and a target plate. The target inserter is installed on the temporary purging pipeline, and the target plate is detachably fixed to the target inserter and can extend into the interior of the temporary purging pipeline.

4. The purging system for ship steam pipelines according to claim 1, characterized in that, The temporary purging line includes: The first purging branch has its inlet end connected to the steam pipeline. The first purging branch passes through the steam turbine generator set and is isolated from the steam turbine generator set. The first purging branch is provided with the purging control valve and the silencer in sequence. The second purging branch is connected in parallel with the first purging branch. The inlet end of the second purging branch is connected to the steam pipeline. The second purging branch passes through the upper module reheating system and is isolated from the upper module reheating system. The purging control valve and the silencer are sequentially provided on the second purging branch.

5. The purging system for ship steam pipelines according to claim 1, characterized in that, It also includes a control device, which is connected to the pressure control valve; The ship is equipped with an inertial detection device, which is used to detect the ship's rolling motion; The control device is connected to the inertial detection device and is used to control the opening degree of the pressure control valve according to the amplitude of the ship's rolling motion.

6. The purging system for ship steam pipelines according to claim 1, characterized in that, During the purging process, the inlet end of the steam turbine generator set is sealed with a blind flange.

7. The purging system for ship steam pipelines according to claim 1, characterized in that, During the purging process, the inlet end of the upper module reheating system is sealed with a blind flange.

8. The purging system for ship steam pipelines according to claim 1, characterized in that, The temporary purging pipeline is equipped with a drain valve and a drain valve in sequence; and / or Several pipe supports are installed on the outside of the temporary purging pipeline.

9. A method for purging a ship's steam pipeline network, characterized in that, The purging is performed using the ship steam network purging system according to any one of claims 1-8; the purging method includes: During the preparation phase, temporary purging pipelines, purging control valves, and silencers are installed, and the turbine generator set and the upper module reheating system are isolated. During the preheating stage, the purge control valve is opened, and the pressure control valve is opened at a preset opening degree, so that steam fills the steam pipeline and the temporary purge pipeline and reaches the preset temperature. During the intermittent purging phase, close the purging control valve and fully open the pressure control valve to allow steam to fill the steam pipeline and temporary purging pipeline and reach the preset pressure. When the temporary purging pipeline reaches the preset pressure, quickly open the purging control valve to release the steam instantly. During the testing and acceptance phase, after repeating the intermittent purging phase 3 to 4 times, a target plate is set on the temporary purging pipeline for target testing. The target quality should meet the following requirements: within a 10mm×10mm area on the target plate, there should be no more than 2 impact marks with a diameter not exceeding 0.5mm. Two consecutive successful target tests are considered as successful purging.

10. The purging method for a ship's steam pipeline network according to claim 9, characterized in that, After the purging process is deemed satisfactory, the following steps are also included: During the recovery phase, after the purging system has cooled to a safe temperature, the temporary purging pipeline, the purging control valve, and the silencer are removed, and the normal operation of the ship's steam network is restored.

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