Wearing full bunker gear, ESTI technician Bob Carr thrusts the flaming end of a 10-foot pole into a drifting cloud of LNG vapor, setting the leading edge ablaze. Slowly, almost lazily, the flames burn through the extended cloud back to the vapor's source, a specially built reinforced concrete pit.
The flames turn the pit into a bubbling caldron of fire and unyielding ice. Moisture condensed from foam used to control previous test fires has solidified into a frozen layer that shields the supercold LNG in the bottom of the pit. As the LNG dissipates, vapor continues to force its way up through the porous ice to feed the flames.
Different types of foams are applied with varying degrees of success. Finally, dry chemical snuffs out the flames, leaving the LNG to vent into the atmosphere.
This exercise conducted at BP's new LNG training and research project at Texas A&M University's Emergency Services Training Institute represents a simulation of what would be a serious accident involving a major LNG spill in liquid form, said Richard Coates, BP's group fire adviser.
"In its refrigerated form, LNG spills onto the ground like a liquid and, at the same time, vaporizes," he said. "You can allow it to stay there and just vaporize away and, provided you can control the vapor, the LNG is not going anywhere. You can contain it with high expansion foams."
If the vapor happens to find an ignition source, foam can greatly reduce the radiated heat, Coates said. Part of the work at the LNG project is determining which type of foam works best under these circumstances.
"Most likely you won't want to put the fire out because you don't want this vapor cloud to return," Coates said.
BP Group Technology, in conjunction with BP Global LNG, and working as a joint partner with Texas A&M, developed the new training facility in College Station, TX. September marked the inaugural testing of the new training facility, followed in October by the first class of industrial emergency responders to attend LNG courses.
In addition to importing LNG into existing terminals in the United States, BP is proposing to build its own import facilities in New Jersey and Texas. The company has interests in export operations around the globe and is the world's second largest non-state supplier of natural gas to liquefaction plants, in addition to operating its own LNG vessels.
The September testing and October training each consumed 20,000 gallons of LNG transported to the site by tanker truck. Classes and demonstrations were supervised by Coates and Kirk Richardson, ESTI's senior fire instructor for LNG and marine courses.
Demonstrations illustrated rapid phase transitions (RPT) on unignited LNG pools, vapor cloud control and ignition and the first experimental use of compressed air foam systems on large LNG pool fires.
"This LNG fire ground is the world's first full integrated detection and suppression LNG ground where you can carry out workshops, tests and experiments on LNG vapor clouds, spills and fire," Coates said. At present, the LNG props consist of three concrete pits, one constructed in an L-shape to simulate the trenches used to carry pipework and divert any LNG spills into containment pits.
Angus Fire, Hale Products, International Paint, Knowsley SK, Micropack Detection and Zellweger Analytics supported the LNG initiative with their latest technology.
"BP is funding the construction of the main LNG fire ground with the Texas Engineering Extension Service," Coates said. "But this testing couldn't be done without manufacturers providing and donating equipment that we at BP feel is the best in the world for this purpose."
Sitting at the edge of the pits were two large devices that could easily have been mistaken for jet engines. These latest Turbex fixed high expansion foam generators were designed by Angus Fire specifically to control LNG spills. Using high expansion foam, the Turbex is capable of up to a 500-to-one expansion ratio. Tests were conducted using high, medium and low expansion foam.
"Depending on what you're trying to do, low and medium expansion foam have their place," Coates said. "It is fairly obvious that it was the high expansion foam together with the large Turbex generating system that are very effective at immediate large scale application into the large pits."
The units had to be significantly upgraded from the standard industrial and marine models to withstand the heat and the cryogenic aspects of LNG spills, said Mike Wilson, Angus Fire product manger.
"Historically, there is not much test work on LNG," he said. "Of that, you might have conflicting isolated tests that may have worked under certain circumstances and not others. We are very keen to be involved here to further develop our knowledge and data base on how various foams work on LNG in different expansions."
Early testing at ESTI showed that different systems can be applied successfully to different situations, Wilson said.
"While powder can clearly put the fire out, that is not always an advantage because you then build up a low vapor level above the liquid which is vaporizing in the flammable limits between five and 15 percent," he said.
That vapor is then free to find a new ignition source.
"Foam has a big advantage in two ways," Wilson said. "One is the dispersion of vapors. If you have an unignited spill you might put foam on the ground to try and warm the LNG. You can warm it with water, but the reaction is rather severe. Foam is a gentle way of warming it, encouraging the vapors to rise upward and out of the way of any ignition source."
If it should ignite, foam can be an effective fire control mechanism, cooling the heat of the flames, he said.
"We saw that using a low application rate of high expansion foam works extremely well at reducing the radiation of heat at the top of the fire," Wilson said. "The idea is to apply it fast enough and at a high enough rate to get control quickly and avoid potential damage to the surrounding plant and equipment."
As the lower portion of the foam freezes, ice cubes build up within the foam blanket, venting the vapor in a controlled way and producing candling flames on the surface that are less intense, he said. The foam bubbles insulates the LNG from the heat source above, controlling the release of vapor. As the heat breaks down the foam blanket, more foam must be applied.
"The best way we've found of doing that is with fixed LNG version Turbex units which are designed for this type of application and have been field tested to 1,000 degrees Centigrade inside and outside the unit," Wilson said.
Selection of foam concentrate from the wide range of high expansion foams available is also important, he said.
"You have to be careful about which product you use for LNG because the ones that drain much more quickly do not have the stability to provide the fire control we are looking for," Wilson said.
Another foam variation tested was the use of compressed air foam. Coates said the tests proved that CAFS have a future in controlling LNG spills.
"We used it with a five-inch opening rather than a nozzle," Coates said. "It showed itself to be relatively effective on controlling the fire in a small pit. The key thing is that because it uses such a small amount of water the foam was very dry."
Marvin O. Johns, regional manager for Hale, said that 3.2 gallons of foam and only 47 gallons of water were enough to bring the small LNG pit under control. A later test using AR-AFFF took the same amount of foam and 57 gallons of water to control. Hale, which brought its CAF demonstration truck to the site, utilized a 210 cfm air compressor and a 60 gpm pump.
"We found that the thermal heat coming off the fire was significantly reduced as compared to a high expansion foam," Johns said. "With this foam and the tightness of the bubbles it gave me a blanket over the top that helped suppress the vapor. But with those straight surfaces up the side of the pit there is no way to keep the LNG vapor from coming up there."
Dominic Colletti, Hale's foam system product manager, attended the testing conducted in September. He noted that more municipal departments are using CAFS on full sized pumpers equipped with split tanks that can carry both Class A and B foam.
"This testing gives us the opportunity to gauge the results and inform municipal people what effects compressed air Class B foam has on LNG," Colletti said. "If LNG becomes as big as what we think it will become, this is one more tool for our municipal people."
Zellweger Analytic and Micropack Detection used the opportunity to demonstrate detectors that key off infrared and visual information, respectively. Knowsley SK provided a new style of fire hydrant and oscillating water monitors that were used to give real time protection to nearby exposures. International Paint tested its Chartek fireproofing against the intense LPG flames.
"We're providing structural steel columns that have been coated with Chartek that will be placed somewhere in the fire envelope so that people can see what the material is like when it is triggered under these extreme heats," said Craig Scott, regional manager for International Paint.
According to Coates, many improvements are slated for the LNG training facility in 2005. Permanent gas and flame detectors will be installed for extended monitoring when the site is in use. Also, three more projects are scheduled to be added to the fire ground.
"We're going to further develop what is already the only fire ground like this in the world," Coates said. "By April 2005 this facility will have the most advanced detection and suppression available."