A system utilizing bog to cool pipes

Abstract

The invention relates to a system for cooling a pipeline through boil off gas (BOG). The system comprises the cooled pipeline, a liquefied natural gas (LNG) pipeline and a BOG gas-phase pipeline, wherein a first valve is arranged on the top of the cooled pipeline; the LNG pipeline and the BOG gas-phase pipeline are located above the first valve and are communicated with the cooled pipe through the first valve; the LNG pipeline is provided with a pore plate. By utilization of the system for cooling the pipeline through the BOG, influences on precooling of the pipeline by heavy component gathering are prevented, the cost is reduced, the pipeline cooling risks are reduced, and the precooling effect is improved.

Description

technical field [0001] The present invention relates to a system for cooling pipes using BOG. Background technique [0002] The liquefied natural gas (LNG) pipeline system is an important part of the LNG receiving station. Its normal operation is the condition to ensure the normal production of the LNG receiving station. Due to the low temperature and large size of the low-temperature pipeline in the LNG receiving station, its trial operation includes later maintenance. Putting into use has always been a difficult point in the industry, and LNG pipelines are usually made of austenitic stainless steel. Austenitic stainless steel has excellent low-temperature performance, but has a large coefficient of linear expansion. Under the LNG temperature condition, the shrinkage rate of stainless steel is about 3 / 1000. For the 304L material pipeline, when the working temperature is -162℃, the 100m pipeline shrinks about 300mm. In order to prevent the stress caused by cold shrinkage b...

AI Technical Summary

Problems solved by technology

The commonly used method is to uniformly cool the pipeline after vaporizing liquid nitrogen. There are two problems in this method. First, it needs to purchase additional liquid nitrogen and rent a vaporizer, which requires additional costs; second, because the temperature of liquid nitrogen is -196°C, and The design temperature of austenitic stainless steel is generally -165°C. If it is not well controlled during the pre-cooling process, small droplets of liquid nitrogen will be produced, which will cause great damage to the pipeline.

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