BOG management system for LNG lightering operation

Abstract

The invention provides a BOG management system for LNG lightering operation, which relates to the field of LNG lightering; the system comprises a BOG gas phase three-way regulating valve, a lightering LNG buffer tank, GCU (Gas Control Unit) equipment, reliquefaction equipment and a liquid phase three-way valve; before lightering, the cabin pressure of the lightering LNG buffer tank can be checked, the pressure can be quickly reduced, and the cabin pressure of a loaded ship is reduced, so that conditions can be created for lightering operation, and the starting rapidness of the lightering operation is realized; ship-ship butt joint is rapidly achieved, and lightering operation time is shortened; BOG generated in the LNG ship lightering process is safely treated, and the cabin pressure of a loaded ship in the lightering process is precisely controlled; the lightering LNG buffer tank is connected into the lightering system of the loaded ship, so that the cabin capacity of the loaded ship is indirectly enlarged, the lightering operation has more abundant space to enhance the BOG treatment capacity, and the lightering safety is improved; the BOG treatment system effectively determines the application of the reliquefaction device and the GCU device, optimizes the reliquefaction capability and avoids the waste of BOG.

Description

technical field [0001] The invention relates to the field of LNG transfer, in particular to a BOG management system for LNG transfer operation. Background technique [0002] The purpose of the ship-to-ship transfer (STS transfer) operation in the LNG water transportation trade is to carry out LNG storage and storage operations according to the needs of transportation and storage. , fuel bunkering operations, LNG ship changing operations, and large-scale LNG ships that cannot enter the shallow water channel to transfer to shallow-draft LNG ships. When transferring, it is often necessary to put two LNG carriers side by side. Complete the LNG ship transfer operation. [0003] If the loaded ship is suspended and waiting for a long time, it is difficult to effectively consume natural gas (BOG) through the main engine. When the pressure of the loading ship is greater than that of the unloading ship, the natural gas gas pipelines of the two ships cannot be connected, so the exces...

AI Technical Summary

Problems solved by technology

[0003] If the loaded ship is suspended and waiting for a long time, it is difficult to effectively consume natural gas (BOG) through the main engine. When the pressure of the loading ship is greater than the pressure of the unloading ship, the natural gas gas pipelines of the two ships cannot be connected, so the excess natural gas (BOG) of the loaded ship must be processed first

[0004] A large amount of natural gas (BOG) is often produced during the ship transfer operation, and the temperature of the loaded ship is relatively high, so it is necessary to depressurize the LNG tank and LNG pipeline of the loaded ship. In addition, during the transfer and unloading process of the liquid cargo tank of the LNG carrier, the volume displacement of the transfer and the work heat of the transfer pump will be transferred to the LNG, and there will be factors such as heat inhalation caused by cold insulation leakage and heat leakage, which will also increase the transfer operation. A large amount of BOG is produced, and when the LNG cabin pressure of the loaded ship is higher than that of the unloaded ship, the transfer operation will fail

[0005] For large LNG carriers with membrane tanks, the bearing pressure range is low, generally less than 0.035-0.04MP a , there will be more BOG due to large tank capacity. If it cannot be processed quickly, in order to protect the safety of the cargo tank, it is generally selected to be emptied. Natural gas is a greenhouse gas and a combustible gas. Empty, especially during ship transfer It will pollute the air and cause an explosion risk to the operation site. Therefore, the cabin pressure control of LNG ship transfer operation is a technical difficulty

Images