System and method for re-condensing boil off gas (BOG) of liquefied natural gas

Abstract

The invention discloses a system and a method for re-condensing a boil off gas (BOG) of a liquefied natural gas. The system comprises a liquefied natural gas storage device, a BOG re-condensing device and a liquefied natural gas conveying device, wherein the BOG re-condensing device comprises a static mixer and a gas-liquid separator, an outlet in the top of the gas-liquid separator is connected with a BOG main pipe of a liquefied natural gas storage tank, an outlet in the bottom of the gas-liquid separator is connected with a liquefied natural gas low-pressure outward conveying main pipe, one end of the static mixer is connected with the gas-liquid separator, the other end of the static mixer is connected with the liquefied natural gas low-pressure outward conveying main pipe, and the BOG main pipe is sequentially connected with a compressor and a heat exchanger to be connected with the static mixer. The method includes mixing the liquefied natural gas and the BOG in the static mixer, then feeding the liquefied natural gas and the BOG into the gas-liquid separator, returning a separated gas to the BOG main pipe, and feeding a separated liquid phase into a booster pump outside the tank. According to the system and the method for re-condensing the BOG of the liquefied natural gas, by means of a static mixing and condensation manner, condensation efficiency of the BOG is increased, energy consumption is reduced, and purposes of saving equipment investment and facilitating system operation and maintenance are achieved.

Description

technical field [0001] The invention relates to the field of liquefied natural gas storage and delivery systems, and more particularly, to a system and method for recondensing liquefied natural gas boil-off gas. Background technique [0002] Liquefied natural gas (LNG) is a high-quality energy source with the characteristics of high calorific value and low combustion pollution. The main function of the LNG receiving station is to receive LNG transported by ocean-going ships, store and gasify it to obtain gaseous natural gas (NG) products, and supply gas to urban residents and / or industrial users through the natural gas pipeline network. [0003] During the production process of the LNG receiving station, due to various factors such as storage tanks, pipelines, equipment, etc. absorbing heat from the environment, unloading flash evaporation, and atmospheric pressure changes, a certain amount of evaporation will be released from the LNG in the LNG storage and transportation sy...

AI Technical Summary

Problems solved by technology

[0011] The internal components of the recondenser (such as Pall rings, separator devices, deflectors, internal pipes, etc.) are complex, and the logic control is relatively complicated

And because the condensation method in the recondenser is static contact, the condensation efficiency is low, usually up to about 58%

On the other hand, the existing recondensation process has disadvantages such as relatively high energy consumption, large equipment investment, and inconvenient maintenance to a certain extent.

Images