If I Had a Million Dollars…
July 28th, 2009 | by Dr. Saraf |
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In February of this year, Sandia National Laboratory (SNL) kick-started a $7.9-million test program to evaluate large LNG fires on water. SNL built a two-meter-deep pond 120 meters in diameter, spilled LNG on the pond and ignited it. This produced a LNG pool fire 20-m (66-feet) in diameter. The plan is to create a 100-m pool fire.
Why Burn A Fuel?
LNG is imported in the U.S. using giant LNG tankers that can store up to 265,000 m3 or 70-million gallons of LNG. The concern is that these tankers may be breached either due to a terrorist attack or from tanker collision resulting in a huge spill of LNG and a massive pool fire. The estimates vary on the size and magnitude of the fire. The consequences following large LNG spills was a topic of hot discussion in 2003-05 with 50+ proposed LNG terminals. During that time, I was in Boston and controversy over LNG safety heated up to a point that Somerville Senator Capuano wanted to blow up a tanker to put an end to the speculation as to what-can-happen.
Thankfully sanity prevailed.
How about Testing on a Larger Scale?
The previous largest LNG pool fire field test was the Montoir test series conducted in 1989 - the pool size was 35-m (115-feet). However, Montoir tests were conducted on land and scaling the thermal radiation models for extremely large fires on water is not evident. For example, it is very likely that beyond a certain critical diameter, the LNG pool will break up into smaller pools (or a complex shape) resulting in multiple small pool fires rather than a single large flame.
It became apparent that no field trial will match LNG spill from an entire tanker; therefore, a mathematical model based on conservative assumptions has to be applied for estimating thermal hazard zones.SNL’s fire studies are aimed at generating data to refine fire and thermal radiation models.
What Will We Learn from these Large Fires?
Anyone who has done experiments will agree how difficult it is to create controlled test conditions. For field tests discussed earlier the degree of uncertainty is significant…consequently, there is considerable variability in data. For example, surface emissive power of LNG flames in field test has been reported to be between 50-250 kW/m2. That’s a wide range! All this makes it difficult to reach definite conclusions from field trials.
As someone who has closely worked with consequence models for last ten years, I’m interested in how the tests compare with the existing models. However, SNL test outcome is not going to change prudent risk assessment strategies and it won’t provide additional information for decision making.
If I had $7.9-million to spend, I’m not sure I would BURN the Benjamins…would you?
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One Response to “If I Had a Million Dollars…”
By Heather Sutton on Sep 9, 2009 | Reply
Dear Dr Saraf,
Can you please say what toxins are in the emissions of burning methane? I am assured by my local member of parliament that burning methane gas is clean - ‘Just like the gas you use at home’. I can’t believe that this is a valid argument.
In the summer the first LNG carrier came into the South Hook LNG site - Exxon and Qatar - and the flare from the terminal turned into a fireball on the top of a small stack. This went off and on for about 2 weeks. Some of the locals said they felt ill and ash was found on their cars, the local Health and Safety officer admitted that he didn’t immediately turn up to see what was happening. The fire was so bright local people didn’t need to put on their electric lights. The company and the other official bodies failed to answer a phone call saying they would phone back, and they didn’t.
We have been told that at least half the gas in the carrier was burned off over the 2 weeks. This accident seems to have been caused by a faulty valve. Added to which there was a loud knocking noise which could be heard some miles away while the carrier was on the jetty.
May I suggest that this could become useful data for your investigations. I think you would find that David Robinson - ds.robinson1@btinternet.com - has a great deal of information which you might find useful. He has been monitoring the shipping in the Haven very closely and quoting Sandia whenever he can, he sent our campaign group your email. You might also find it useful to visit the area because there are 2 very large sites here with severe safety problems. On the site at the other terminal Dragon LNG, the heat from that flare set the grass on fire and local residents saw a fire caused by garbage in the site and had to alert the security men at the gate.
There are regular shipping accidents in the Haven, a narrow channel with a dog leg in it, a lot of shipping, pleasure craft and a passenger ferry to Ireland twice a day. We also have very high south-westerly winds often reaching gale force.
We have no plausible emergency plan for a local evacuation and no plausible risk assessment either.
Heather Sutton