Hazard Control Technologies has developed an excellent reputation in the power industry due to HCT’s long-term association as a member and sponsor of the PRB Coal Users’ Group and F-500 Encapsulator Agent’s uncanny ability to mitigate coal fires. This led to the development of specialized equipment, training courses, application specific fire suppression systems and DustWash, dust mitigation solution.
Coal Handling Hazards
HCT and PRB Coal Users’ Group have paved the way to industry best practices for handling sub-bituminous coal. Although all coals present a combustible dust hazard, sub-bituminous coals oxidize rapidly and frequently spontaneously ignite. These fires can be mitigated if handled properly. Spraying water on sub-bituminous coal causes a violent flashover that can lead to an explosion. The addition of 1% F-500 Encapsulator Agent into water prevents this flashover. It has the ability to make the coal dust nonflammable. F-500 EA also has surface tension reduction properties that allow it to penetrate deep below the surface and into the pores of the coal.
As a first defense, many power plants have F-500 EA Fire Extinguishers strategically placed throughout the coal handling system. These are excellent for small fires near a transfer chute or conveyor belt. HCT also offers other portable F-500 EA delivery systems for any requirement around the power plant. Once a deep-seated fire develops in the stockpile, silo or bunker, HCT’s Piercing Rod Systems are recommended. With a FLIR thermal imaging camera included, the location can be pinpointed and direct the piercing rod into position where F-500 EA is injected into the hot spot. One of the keys to handling coal safely is the prevention of combustible dust build-up. HCT’s Concentrate Control Supply (CCS) systems can be used for dust control and DustWash can be added to safely remove float dust. HCT presents courses to power plants that raise the awareness of coal handling hazards teaching vigilance to every employee. Hands-on training teaches power plant teams or local firefighters how to use piercing rods for deep-seated stockpile or silo fires.
Under Turbine Lube Oil
Large quantities of mineral oil circulate to lubricate high-speed turbine bearings. Leaks occur and the tremendous heat easily ignites the hot oil. Systems are in place to apply water, but these fires are so hot, structural damage to buildings can occur, not to mention millions of dollars of damage to the turbines, generators and financial losses of not producing power. They are also a Class B, three-dimensional fire, making extinguishment difficult for plain water. Even fixed suppression systems with foam additives are ineffective (NFPA 11-Annex A.1.1 – Foam is not suitable for three-dimensional flowing liquid fuel or for gas fires).
FM Global performed life-sized turbine fire testing and found the NFPA fixed suppression application rate of .25 gpm/ft2 was inadequate and recommended .40 gpm/ft2. Hoping to avoid a redesign of their existing suppression system and the associated capital expense, a major power company commissioned independent testing to see if F-500 EA could improve the firefighting performance sufficiently to avoid installing a new suppression system. The test results proved adding 3% F-500 EA to water permanently reduced temperatures from 1200 to 115°F in seconds, whereas plain water only dropped the temperature to about 300°F, and then experienced periodic increases. Also, in another test, the F-500 EA was able to extinguish the fire with 83% less water. Simply adding an F-500 EA Concentrate Control Supply (CCS) system into the water line can greatly increase the performance of a planned or existing turbine fixed suppression system.
Transformers that are adjacent to buildings or other transformers or equipment should be protected with an F-500 EA Concentrate Control Supply (CCS) system. Transformers usually contain large amounts of oil and have large metal mass that retains the heat. Even after the power is removed, these fires do not respond to water, foam or even powder.
A New York City transformer fire in 2009 burned for hours waiting for ConEdison to turn off the power. Meanwhile, huge amounts of foam and water were applied to surrounding structures. When the power was turned off, foam and powder was unsuccessfully applied to the transformer. It continually reignited. The hazmat unit decided to try F-500 Encapsulator Agent which they had used previously on transformers and Class D metal fires. The transformer fire was out in two minutes and cooled to 100°F in a few more minutes. ConEd then began testing AFFF, AR-AFFF and F-500 EA on 50,000 volts. It was decided foam was too conductive due to the bubble to bubble contact back to the nozzle. The F-500 EA was further tested at Fresh Kills Substation in October, 2010 on a 345,000 volt overhead conductor. Using three different nozzles, they concluded that F-500 EA can be applied at a 25 feet distance with a 30° conical pattern or at 125 feet with a straight stream. The volume of water and pressure had no influence on the outcome. The encapsulator agent quickly removed the heat without creating scalding steam, encapsulated the fuel making the oil nonflammable and nonignitable and penetrated deep into the transformer casing. At the same time, the encapsulator agent interrupted the free radical chain reaction, reducing toxic smoke and increasing visibility. Obviously, with F-500 EA, less water is used so diking is rarely needed and using less agent saves money.
If an F-500 EA CCS system is not installed the plant fire brigade or local firefighters should be equipped to fight the transformer fire with F-500 EA on hand.
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