I have written about Liquefied Natural Gas (LNG) in the past. Earlier, I discussed the large quantities of this liquid which was being imported into the USA. Then, with the discovery of large amounts of natural gas being found, we are exporting this super cold product.
For the Land-Based Firefighter we also must deal with LNG being transported via truck on our highways and locomotives on our railroads. Not only is it being transported on these means of transport, LNG is now also fueling the same trucks and locomotives which are delivering the LNG.
My “LNG for the First Responder” training programs have been covering all these previous hazards, but we Firefighters are now being presented with a new area of risk with LNG.
Many new ships and work boats are being built with the ability to either run entirely on LNG or by using a “duel fuel” concept whereby they can run on either LNG or standard marine fuels such as diesel or heavy bunker fuel oil. And LNG is not a passing fad, “The global trade in LNG has almost trebled from 100 million tonnes a year in 2000 to nearly 300 million tonnes last year. Shell expects demand for LNG to roughly double by 2035….”
The process of fueling a vessel is termed “Bunkering” (See Figure 1 above). Due to many existing and future environmental regulations these ships and boats must meet very rigid emission constraints. Emissions of oxides of nitrogen (NOx), sulfur oxides (SOx), and particulate matter must be reduced to levels impossible to meet with existing marine fuels. (Figure 2). The International Maritime Organization (IMO) 0.5% Sulphur cap regulation is due to come into effect in 2020.
Due to this, and the fact that the price of LNG has been reduced due to a surplus of supply, it is only natural that LNG fueled ships are what the future holds.
And, if we are going to have LNG fueled commercial vessels we are also going to need the means of bunkering (fueling) these vessels with LNG.
What this means to us, the Land Based or Marine Firefighter, is that we will have to add to our knowledge base and tool list the means of dealing with any fire or emergency involving LNG.
Even if your port does not currently have an LNG bunkering facility, vessels may still be bunkered while in your port. LNG fuel tanker trucks and ISO containers can be brought to the vessel by truck and then have the LNG transferred to the vessel. That’s not so “farfetched”. It is currently being done in many ports throughout the world.
In the USA, the port of Jacksonville, Florida has been bunkering large LNG fueled container ships for several years.
Initially the LNG was trucked in ISO containers from another state. Several of these containers were then hooked up to a manifold on the dock (See Figure 3) and the LNG was transferred to the ship. This same port is currently constructing two permanent LNG bunkering facilities which will serve to fuel more container ships and possibly some of the new LNG fueled cruise ships now under construction.
Another method of bunkering these vessels is via a dedicated bunkering ship or barge. This bunkering barge or bunkering ship can be brought alongside the water-side of a vessel loading or unloading its contents at a dock. The bunkering can then take place while the vessels cargo is being handled.
Regardless of the method, LNG will be present and will be transferred to a vessel. The Land Base Firefighter must be aware of the fueling process, the dangers involved, the safety measures required, and the national and international regulations covering this process.
In my previous articles (March 2016) I covered the properties of LNG of which the Land-Based Firefighter must be aware. If you attempt to control and LNG emergency with water or if you attempt to extinguish and LNG fire with water, you will be in for a shock.
Water will not extinguish an LNG fire. If fact, water will increase the liquid’s vaporization and will therefore also increase the size of the flame. In certain instances when water is plunged into a pool of flaming LNG there may also be what will appear to be an explosion. It actually is a Rapid Phase Transition (RPT). The natural gas had been reduced in size 600 times as it was converted into a liquid. When your fire stream is plunged into the LNG pool the natural gas wants to flash back into a gas. There may not be enough room for this immediate expansion and the RPT causes a pressure wave as the gas attempts to expand.
The same RPT can occur when large quantities of LNG are plunged into a pool of water. You don’t really have to understand the phenomenon of a RPT. What you do need to know if that water should be kept away for an LNG pool or an LNG fire.
The extinguishing agent of choice is dry chemical. This agent will interrupt the chain reaction which occurs during a fire. Chain reaction is the fourth side of the Tetrahedron we all learned when we became Firefighters.
Extinguishing an LNG fire may not be the proper action in many circumstances. If LNG in the open is burning the flame is consuming the methane. Once you extinguish the flame any remaining LNG will still be vaporizing into methane gas which can find enclosed spaces. The natural gas from vaporized LNG does not explode in the open but when confined such as in a basement or underground structures it can explode violently.
Whenever possible, let the LNG burn itself out while you protect exposures. Sometimes this is not possible such as when there is an immediate life hazard or the danger to surrounding exposures is too great.
OK, that’s the bad news. The good news is that at most LNG fires and emergencies the LNG portion of the even will be over before the arrival of first responders. This is because all the safety measures which must be in place will either prevent the release of LNG or limit the amount of the spill. Please read my previous article to learn some of the other dangers of this “super cold” liquid. In that article I also discussed some of the land-based modes of transportation such as truck and locomotives which are now being fueled with LNG.
In part 2 of this article we will discuss some of those safety measures which have kept transportation of LNG safe in the marine environment and how those same safety measures are being applied to the new bunkering of LNG fueled vessels.
Until next time; Stay Safe
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