Pumpless circulation method for small skid-mounted evaporation gas reliquefaction and recovery device for liquefied natural gas

Abstract

The invention provides a pumpless circulation method for a small skid-mounted evaporation gas reliquefaction and recovery device for liquefied natural gas. The pumpless circulation method includes the steps: taking a regenerative cryo refrigerator (3) as a cold source to perform condensation and liquidation on boil off gas (9) generated from the liquefied natural gas (2) in a cryogenic storage tank (1); enabling the liquefied natural gas (2) formed in condensation to flow back to the cryogenic storage tank (1) under the action of gravity through a pipeline. Circular reciprocating flow of gas liquid inside the system is sustained under the action of differential pressure and gravity, and cryopumps are not required to provide circular power, so that the integral structure and technological process of the device are simplified, energy consumption is lowered, and economical efficiency in operation of the device in improved; real-time monitoring and stepless regulation can be performed on cryogenic temperature and output cold of the cryo refrigerator according to changes of actual pressure and heat loads inside the cryogenic storage tank, zero consumption of a storage tank system can be realized, and stability, reliability and control precision in operation of the device are improved.

Description

technical field [0001] The present invention relates to the technical field of reliquefaction and recovery of boil-off gas (BOG) and its control during storage and transportation of liquefied natural gas (LNG), more specifically, it relates to the pumpless circulation of a small skid-mounted BOG reliquefaction recovery device and control methods. Background technique [0002] Liquefied natural gas (LNG for short), the main component is methane, is recognized as the cleanest energy on earth. Colorless, odorless, non-toxic and non-corrosive, its volume is 1 / 625 of the volume of the same volume of gaseous natural gas, and the weight of liquefied natural gas is only about 45% of the same volume of water. Gaseous natural gas is compressed and cooled to its boiling point (-161.5°C) to become LNG, stored in low-temperature storage tanks, transported by special ships or tank trucks, and re-gasified when used. Compared with gaseous natural gas, due to its small size and high storag...

AI Technical Summary

Problems solved by technology

The BOG reliquefaction method currently mainly adopts the conventional nitrogen expansion or mixed refrigerant liquefaction process, but the device process used in this method is complicated, the equipment is too much, the price is expensive, and it is not suitable for LNG transport tankers and small LNG storage. Use of tanks and LNG vehicle filling stations

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