What is gassing up in LNG?
During gassing up, the inert gas in the cargo tanks is replaced with warm LNG vapor. This is done to remove carbon dioxide and to complete drying of the tanks. The LNG vapour is lighter than the inert gas, which allows the inert gases in the cargo tank to be exhausted up the tank filling line to the liquid header.
What is gassing up and cooling down?
The gassing up and cooling down is a specialized service to bring the storage tanks on LNG carriers, after dry-docking, to natural environment and later cool it down to cryogenic temperature (minus 160 degrees Celsius) before loading its next cargo.
What is purging in a tanker vessel?
In fire and explosion prevention engineering, purging refers to the introduction of an inert (i.e. non-combustible) purge gas into a closed system (e.g. a container or a process vessel) to prevent the formation of an ignitable atmosphere.
How much gas does an LNG tanker use?
The question is, how much cargo can it handle? A Q-Max tanker can carry about 266,000 cubic meters of LNG, equal to roughly 5.5 billion cubic feet of natural gas in the vapor form burned in furnaces, water heaters and kitchen ranges.
Why is gas detection on tankers required?
Chemical cargoes carried in bulk are normally toxic in nature. Gas generated from the oil/ petroleum product can be considered as toxic as they contain HC which is harmful for humans.
What is gas freeing in tankers?
marine. The procedure of removing dangerous and explosive gases from the interior of tanks (usually vapours originating in the cargo of oil tankers and chemical carriers).
What is gas purging procedure?
Gas Purge & Testing A purge is carried out in order to remove the hazardous gas from the line. This is done by injecting an inert gas into the pipe. The inert gas mixes with the gas in the pipework. This stops the hazard of a combustible mixture which could cause harm to workers on the site.
Why do we purge cargo tanks?
After tank cleaning operations, the cargo tanks may be purged with inert Gas to reduce the hydrocarbon gas concentration inside the tank atmosphere. Go on with purging by IG until the hydrocarbon content reduces to the required / desired level.
What would happen if an LNG tanker explodes?
As a frosty liquid, kept at minus-260 degrees Fahrenheit, LNG cannot explode or catch fire. Various studies agree that if a tanker is breached by a bomb or missile, the liquid flowing from its icy storage instantaneously would become a gas and ignite. The result: an extremely hot fire, as wide as three football fields.
What does a gas detector detect?
Gas detectors can be used to detect combustible, flammable and toxic gases, and oxygen depletion. This type of device is used widely in industry and can be found in locations, such as on oil rigs, to monitor manufacturing processes and emerging technologies such as photovoltaic.
What is the equipment used to detect gas inside the tanks?
Explosimeter: These are modern gas detectors used to check the composition of gases inside the tank and flammability level. The sensor used in explosimeter is of catalytic type, also known as “Pellistor”, which are poison resistant element.
How does LNG get into the cargo tank?
It is then fed to the main vaporizer and the LNG vapour produced is passed at a temperature warmer than the dew point temperature existing within the cargo tanks through the vapor header and into each tank via the vapor suction fitted in the upper part of the tank. This method of gassing up is called “Piston Flow Method”.
What happens to the gas in a gassing up tank?
During gassing up, the inert gas in the cargo tanks is replaced with warm LNG vapor. This is done to remove carbon dioxide and to complete drying of the tanks. exhausted up the tank filling line to the liquid header. The inert gas then vents to the atmosphere via the vent mast.
Why does inert gas freeze in LNG tanks?
This is because, inert gas contains about 14% carbon-dioxide, which will freeze at around -60ºC and produces a white powder which can block valves, filters and nozzles. During gassing up, the inert gas in the cargo tanks is replaced with warm LNG vapor. This is done to remove carbon dioxide and to complete drying of the tanks.
What is the gassing up method for LNG?
This method of gassing up is called “Piston Flow Method”. In this the lighter specific gravity LNG vapor is injected from top and the heavier IG is displaced from bottom. Fig:Gassing up with venting from vent mast (2) Requirement to purge with Nitrogen. At the start of the operation, the piping system and main vaporizer contain inert gas.