Method and system for processing gas in a gas storage facility for a gas tanker

A gas treatment method of a gas storage facility, on board a ship, the method comprising:

• extracting a first gas in a liquid state from a first tank or a first vessel,
• a first subcooling of the first gas in the liquid state,
• splitting the subcooled first gas into two portions;
• storing a first portion of the subcooled first gas in the liquid state in a lower part of the first tank or of the first vessel or of a second tank or of a second vessel, so as to constitute a reserve layer of cold of the first gas in the liquid state at a bottom of the first tank or the second tank or of the first vessel or the second vessel;
• cooling a gas in a vapor state using the first gas stored in the reserve layer of cold of the first tank or the second tank or the first vessel or the second vessel,
• wherein the subcooled first gas, which is stored at the bottom of the first tank or the second tank or the first vessel or the second vessel, creates a refrigerating power that can be subsequently used, the reserve layer of cold being stored at the bottom of located in the first tank or the second tank or the first vessel or the second vessel in a durable manner below an amount of the first gas in the liquid state, forming a liquid-liquid interface, and
• the method further comprises spraying a second portion of the subcooled first gas stored in the reserve layer of cold into the first tank or the second tank or the first vessel or the second vessel and into a layer of the gas in the vapor state.