Marine LNG (Liquefied Natural Gas) loading and unloading shore pipe communicating device
By designing a LNG loading and unloading shore pipe device made of low-temperature stainless steel, and using a detachable short pipe and emergency shutdown system, the connection instability and leakage risks during the loading and unloading of liquefied natural gas is solved, and safe and reliable loading and transportation of ultra-low temperature liquefied natural gas is achieved.
Patent Information
- Application Number
- CN202510443846.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-07-04
AI Technical Summary
The prior art is difficult to effectively solve the difficulty and high technical requirements in loading, unloading, storage and transportation caused by the ultra-low temperature characteristics of liquefied natural gas. Especially in the LNG loading and unloading process, there are problems such as unstable connection, leakage risk and complex operation.
A marine LNG loading and unloading shore pipe device is designed, which is made of 316L low-temperature stainless steel, including detachable short pipes, fixed short pipes, sweeping cabin spray branch pipelines, low-temperature LNG special emergency shutdown butterfly valves and other components. Through nitrogen purge and emergency shutdown systems, the stability and safety of the connection are ensured, and rapid connection and leakage protection are achieved.
It realizes safe and reliable loading and transportation between ships and shores, meeting the operating requirements of sweeping cabins, driving gas, and cooling cabins, and improving the safety and efficiency of the loading and unloading process.
Smart Images
Figure CN120251907A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of LNG ship design and construction, and particularly relates to a marine LNG loading and unloading through-shore pipe device. Background Art
[0002] LNG, as a globally recognized clean energy, has received extensive attention and application in the energy field. When the temperature drops to -163°C under normal pressure, liquefied natural gas will be converted into a liquid state, and this process reduces the volume of natural gas to 1 / 600 of its gaseous state. The liquefied state is the ideal transportation state for this clean energy. However, due to the ultra-low temperature characteristics of the above liquefied natural gas, it poses difficulties and high technical requirements in the processes of loading, unloading, storage, and transportation. The LNG loading and unloading through-shore pipe device of the present invention is an important part of the loading and unloading pipeline of liquefied natural gas ships (LNGC). This invented device meets the above characteristics of ultra-low temperature and easy volatilization of liquefied natural gas, and specifically relates to relevant technologies such as ship-shore special connection for LNG loading and unloading, emergency shutdown system, liquefied natural gas spraying for cold storage, scavenging of residual cargo in the cargo hold, purging of residual LNG and air in the pipeline, and pressure release of the pipeline. It can meet important operation steps such as tank cleaning, gas purging, cold storage, and purging in the ultra-low temperature LNG cargo loading and unloading process. This invented device is arranged at the end of each liquid phase pipe in the LNG ship cargo manifold area. Summary of the Invention
[0003] To solve the above problems, the present invention provides a marine LNG loading and unloading through-shore pipe device, and the technical solution adopted is as follows: A marine LNG loading and unloading through-shore pipe device includes a horizontally arranged fixed short pipe. One end of the fixed short pipe is connected to a detachable short pipe through a flange, and the other end is connected to the LNG liquid phase main pipe. A through-shore connection flange is provided at the free end of the detachable short pipe.
[0004] A nitrogen purging pipe extends from above the fixed short pipe, and a double shut-off valve is provided on the nitrogen purging pipe. Two scavenging and spraying branch pipes extend from below the fixed short pipe, and the other ends of the two scavenging and spraying branch pipes merge into a scavenging and spraying main pipe. A special emergency shutdown butterfly valve is provided between the fixed short pipe and the two scavenging and spraying branch pipes; an LNG special shut-off valve is provided on one of the scavenging and spraying branch pipes, and at the same time, a drain pipe extends downward, and the drain pipe is equipped with a double shut-off valve.
[0005] An LNG special safety valve and a pressure gauge are also provided on the fixed short pipe. The LNG special safety valve is connected to the safety valve pipeline of the ship, and the pressure gauge is connected to the fixed short pipe through a pressure gauge branch pipe.
[0006] For the above-mentioned marine LNG loading and unloading through-shore pipe device, further, the special emergency shutdown butterfly valve is controlled by an emergency shutdown system ESD.
[0007] The above-mentioned marine LNG loading and unloading through-shore pipe device, further, the whole through-shore pipe device is made of low-temperature-resistant stainless steel 316L material.
[0008] The above-mentioned marine LNG loading and unloading through-shore pipe device, further, the through-shore connecting flange is connected to the mechanical connecting device at the end of the special filling arm of the LNG terminal.
[0009] The above-mentioned marine LNG loading and unloading through-shore pipe device, further, a fixed support is arranged below the fixed short pipe and is supported above the deck through the fixed support.
[0010] The marine LNG loading and unloading through-shore pipe device of the present invention is an important part of the LNG cargo handling system. The relevant mechanisms are reasonably arranged, safe and reliable in use, and better meet the relevant requirements of important operation steps such as tank cleaning, gas purging, cold tanking, and purging in the ultra-low temperature LNG cargo loading and unloading process, so as to realize the shore-to-ship loading, unloading and transportation of this ultra-low temperature clean energy. Description of the Drawings
[0011] Figure 1 is the overall structural schematic diagram of the present invention; Figure 2 is the structural schematic diagram of the detachable short pipe; Figure 3 is the structural schematic diagram of the fixed short pipe and its components; Figure 4 is the structural schematic diagram of the tank cleaning spraying branch pipeline and its components; Figure 5 is the closed pipe section diagram formed by the docking of the present invention and the liquid cargo loading arm; Among them, 1 - detachable short pipe, 2 - fixed short pipe, 3 - tank cleaning spraying branch pipeline, 4 - special emergency shutdown butterfly valve, 5 - safety valve pipeline, 6 - LNG liquid phase main pipeline, 7 - tank cleaning spraying main pipeline, 8 - nitrogen purging pipe, 9 - double stop valve, 10 - LNG special stop valve, 11 - drain pipe. Detailed Embodiments
[0012] As Figure 1 and Figure 2As shown in the figure, a marine LNG loading and unloading through-shore pipe device is composed of a detachable short pipe, a fixed short pipe, a stripping and spraying branch pipeline, a cryogenic LNG special emergency shut-off butterfly valve, a safety valve pipeline, an LNG liquid-phase main pipeline, a stripping and spraying main pipeline. All the relevant components of the LNG loading and unloading through-shore pipe device of the present invention are made of cryogenic-resistant stainless steel 316L material. The standard flange at the outer end of the detachable short pipe is mechanically connected to the end mechanical connection device of the special filling arm at the LNG terminal to form a special quick connection and quick release QCDC system for LNG ship loading and unloading. Since the above-mentioned detachable short pipe 1 and the docking device of the special filling arm at the terminal form an ultra-low temperature liquefied natural gas LNG ship shore-to-shore transmission loop, and the whole loop transmits ultra-low temperature liquefied natural gas LNG, the standard flange at the outer end of the detachable short pipe of the device of the present invention is set with a raised sealing surface, and the surface roughness of the sealing surface is increased by a traditional method to not more than 3.2 microns with high-precision requirements. In addition, since all the relevant components of the detachable short pipe are made of cryogenic-resistant stainless steel 316L material and combined with the above high technical requirements, it can meet the transmission of ultra-low temperature liquefied natural gas LNG and ensure no leakage. This detachable short pipe is an optimized solution for this set of devices. It is connected to the fixed short pipe of the liquefied natural gas LNG liquid-phase pipeline through the inner standard flange. Its preferred feature is that due to the high standard requirements for the transmission of liquefied natural gas LNG, the surface roughness requirements of the above-mentioned outer end standard flange are very high. During the operation of the ship for many years, if the outer end standard flange is damaged such as worn or rusted, a new detachable short pipe can be quickly and conveniently replaced without rectifying the whole pipeline to achieve the purpose of repair and restoration.
[0013] As Figure 1 and Figure 3 shown, the detachable short pipe is connected to the fixed short pipe of the liquefied natural gas LNG liquid-phase pipeline through the inner standard flange. This section of short pipe of the fixed short pipe is named the fixed short pipe because this section of pipe is the bearing and fixing component at the end of the whole invention device and the liquid-phase pipe. Therefore, a fixed welding support is provided at the lower end of the fixed short pipe. As Figure 2 shown, the lower end of the fixed welding support is connected to the strong hull structure, making the whole liquid-phase pipeline and the invention device fixed firmly, and can absorb the load transmitted due to the movement of the ship relative to the fixed terminal when the liquid cargo loading and unloading arm is connected to the device of the present invention during loading and unloading of goods.
[0014] One end of the fixed short pipe is provided with a standard connection flange for connecting with the detachable short pipe 1. A nitrogen purge pipe, a safety valve branch pipe, a pressure gauge branch pipe, and a pressure gauge branch pipe are sequentially arranged at the upper end of the fixed short pipe.
[0015] It is preferred to set double stop valves on the nitrogen purge pipe, and set standard flanges and blind flange covers at the ends of the branch pipes. Double stop valves can better ensure that ultra-low temperature liquefied natural gas LNG will not leak under any circumstances. Because liquefied natural gas LNG is a flammable and explosive gas, at the beginning and end of each LNG loading, the nitrogen pipeline on the ship or on the shore needs to be connected to the nitrogen purge pipe to purge the oxygen in the liquid phase pipeline in the header area until the oxygen content meets the standard. At the end of each loading and unloading, the nitrogen pipeline on the ship or on the shore needs to be connected to the nitrogen purge pipe to purge the liquefied natural gas LNG in the liquid phase pipeline back to the LNG cargo tank.
[0016] A low-temperature LNG special safety valve is installed on the upper end of the safety valve branch and connected to the corresponding special safety valve pipeline. Since the boiling point of liquefied natural gas LNG is -163°C, any closed pipe section with residual LNG may form a high-pressure steam drum. The special safety valve is connected to the corresponding special safety valve pipeline to prevent the closed space formed by the low-temperature LNG special emergency shut-off butterfly valve and the standard flange at the outer end of the detachable short pipe from causing a high-pressure steam drum or even causing over-pressure damage to the pipeline in the case of residual LNG. Its working principle is that the LNG loading and unloading shore pipe device of this patent is arranged with a low-temperature LNG special safety valve installed on the upper end of the safety valve branch and connected to the corresponding special safety valve pipeline. When the above situation occurs, the gas pressure of the high-pressure steam drum exceeds the set value of the LNG special safety valve, and the safety valve opens to release the gaseous LNG in this closed pipe section to the special safety valve pipeline and enter the special system.
[0017] A low-temperature LNG-specific pressure gauge is installed on the upper end of the pressure gauge branch pipe to monitor the pressure in the pipeline in real time during the liquefied natural gas (LNG) loading and unloading and related process operations to ensure the safety of related operating procedures.
[0018] A low-temperature LNG special emergency shut-off butterfly valve with remote control function is set at the other end of the fixed short pipe. This special emergency shut-off butterfly valve is a remote control valve and is controlled by the emergency shut-off system ESD dedicated to the LNG cargo handling system. When there are any events that do not meet the process requirements during the LNG loading and unloading process or there are related abnormal parameters in the system such as abnormal cargo tank pressure or excessive liquid level, the special emergency shut-off butterfly valve and the valve on the onshore liquid cargo filling arm are linked together to immediately close, stop the LNG loading and unloading operations, and prevent the spread of related abnormal conditions.
[0019] The tank stripping and spraying branch pipelines are respectively connected to the LNG loading and unloading shore pipes at the front and rear positions of the special emergency shut-off butterfly valve of the device of the present invention, that is, the fixed short pipe at the front end of the special emergency shut-off butterfly valve and the LNG liquid phase main pipe at the rear end. Figure 4As shown, a cryogenic LNG special stop valve is also provided between the fixed short pipe connected to the tank cleaning and spraying branch pipeline and the LNG liquid phase main pipeline at the rear end. Such a connection method enables the tank cleaning and spraying branch pipeline to functionally constitute a bypass pipeline of the LNG loading and unloading through-pipe of the device of the present invention at the same time. This bypass pipeline can control the opening and closing of the pipeline through the cryogenic LNG special stop valve. This bypass pipeline is mainly used to purge the residual LNG or oxygen in the closed pipe section formed by the connection of the fixed short pipe and the onshore liquid cargo loading arm through the nitrogen purge pipe when the emergency shut-off butterfly valve is in the closed state. When the detachable short pipe of the LNG loading and unloading through-pipe device of the present invention is connected to the liquid cargo loading arm on the dock, the special emergency shut-off butterfly valve can form a closed pipe section from the fixed short pipe, the detachable short pipe and the end of the mechanical docking device of the liquid cargo loading arm itself, such as Figure 5 shown, so as to inject nitrogen into this closed pipe section through the nitrogen purge pipe and test the connection seal of the detachable short pipe and the mechanical docking device of the liquid cargo loading arm itself by the soap bubble method. This method is also an innovative test method in the LNG loading and unloading process, saving additional test devices compared with the original method, and at the same time ensuring that ultra-low temperature liquid cannot overflow from the docking port at the beginning of loading and unloading.
[0020] The tank cleaning and spraying branch pipeline and its affiliated tank cleaning and spraying main pipelines are pipelines with a smaller diameter than the LNG liquid phase main pipeline that connect to the LNG tank in addition to the LNG liquid phase main pipeline in the LNG loading and unloading through-pipe device of the present invention. This pipeline is mainly used to complete important process operations such as tank cleaning, gas purging, and tank cooling in the LNG cargo loading and unloading process that do not require starting the liquid phase main pipeline.
[0021] A drain pipe is provided below the tank cleaning and spraying branch pipeline. A double stop valve is provided on the drain pipe, and a standard flange and a corresponding blind flange cover are provided at the end of the drain pipe. The drain pipe and related accessories are mainly used to purge the air in the closed pipe section formed by the connection of the standard flange at the outer end of the detachable short pipe and the onshore liquid cargo loading arm during the relevant preparation process before loading and unloading LNG cargo, and when the special stop valve and the emergency shut-off butterfly valve are in the closed state, such as Figure 5 shown in the shaded area, from the ends of the fixed short pipe, the detachable short pipe and the mechanical docking device of the liquid cargo loading arm itself. During the above purging operation, the double stop valve provided on the drain pipe needs to be kept open, thus forming a discharge channel for air and nitrogen used for purging.
Claims
1. A marine LNG loading and unloading through-shore pipe device, characterized in that, There is a fixed short pipe arranged horizontally. One end of the fixed short pipe is connected with a detachable short pipe through a flange, and the other end is communicated with the LNG liquid main pipe. A shore connection flange is arranged at the free end of the detachable short pipe; A nitrogen purge pipe extends above the fixed short pipe, and a double shut-off valve is arranged on the nitrogen purge pipe. Two tank cleaning spray branch pipes extend below the fixed short pipe, and the other ends of the two tank cleaning spray branch pipes converge into the tank cleaning spray main pipe. A special emergency shutdown butterfly valve is arranged on the fixed short pipe and in the middle of the two tank cleaning spray branch pipes; An LNG special shut-off valve is arranged on one of the tank cleaning spray branch pipes, and a drain pipe extends downward at the same time; An LNG special safety valve and a pressure gauge are also arranged on the fixed short pipe. The LNG special safety valve is connected with the safety valve pipeline of the ship, and the pressure gauge is connected with the fixed short pipe through a pressure gauge branch pipe.
2. The marine LNG loading and unloading through-shore pipe device according to claim 1, wherein, The special emergency shutdown butterfly valve is controlled by the emergency shutdown system ESD.
3. A shore connection pipe device for marine LNG loading and unloading according to claim 1, characterized in that, The whole shore connection pipe device is made of low-temperature resistant stainless steel 316L material.
4. A marine LNG loading and unloading through-shore pipe device according to claim 1, characterized in that, The shore connection flange is connected with the mechanical connection device at the end of the special filling arm of the LNG terminal.
5. The marine LNG loading and unloading through-shore pipe device according to claim 1, wherein A fixed support is arranged below the fixed short pipe and is supported above the deck through the fixed support.
6. The marine LNG loading and unloading through-shore pipe device according to claim 1, characterized in that, A double shut-off valve is arranged on the drain pipe.