LNG or gas unloading method

Abstract

The invention discloses a liquid unloading method for liquefied natural gas or coal gas. The liquefied natural gas (LNG) liquid unloading process comprises the following steps: connecting three metal flexible pipes with an unloading platform, pressurizing a cryogenic liquid tanker by using an unloading supercharger to form a pressure difference between the cryogenic liquid tanker and a storage tank, unloading the LNG into the storage tank, and unloading residual gas in the cryogenic liquid tanker to user pipe network by using a medium pressure gas supply system. Compared with the existing liquid unloading method, the invention decreases the residual gas of the cryogenic liquid tanker from 0.4MPa to 0.15Mpa, and the residual gas in the tanker also decreases from 500kg to below 200kg, so as to meet the requirements of customers and save gas unloading time from the original 1 h to 15 min; and the safety coefficient is improved and the production cost is reduced.

Description

technical field

[0001] The invention relates to a method for unloading low-temperature liquid, in particular to a method for unloading low-temperature liquefied natural gas or coal gas from a low-temperature tank car into a storage tank. Background technique

[0002] At present, during the unloading process of liquefied natural gas (LNG), after the liquid phase of the LNG tank car is unloaded, the pressure of the residual gas in the tank car reaches 0.4MPa, and it can no longer be unloaded. The requirement shall not exceed 200kg.

[0003] Chinese patent application CN102829329A discloses a new method for unloading and conveying liquid ammonia. Under the working condition of liquid ammonia unloading: first, connect the tank car connection joint on the unloading pump inlet pipeline and the unloading gas phase communication pipeline with the liquid ammonia tank car. The unloading pump inlet valve, the rear unloading pump inlet valve, the unloading control valve, the liquid pha...

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