Sprinkler for Steam Turbine Generator Bearings

[powering2002]

Dear All

I work at steam power plant. Last year, insurance came to our site and gave recommendation that we should install fire protection (sprinkler) for steam turbine generator bearings. then we asked our vendor (MHI). MHI said that the bearing that is used in our power plant is directed lubrication type. So it could reduce the temperature of bearing. MHI told us to conduct a study before applying that technology (sprinkler for turbine bearings).
In this occasion, i would like to ask some questions.
1. Should we follow the recommendation of the insurance (installing sprinkler for steam turbine generator bearings)?
2. Does NFPA Code Allow us not to install sprinkler for steam turbine generator bearings if we have directed lubrication type bearing?
Thanks..

 

[chicopee]

That's a new one on me. Did the insurer tell you the reason for that sprinkler?

 

[skdesigner]

See NFPA 850-2010 7.7.4.2 Turbine Generator bearings

Note that the lube oil skid should be protected in accordance with 850-2010 7.7.4.1.3.

 

[chicopee]

skdesigner, I just read this article "Steam Turbine Fire Protection will Reduce Repair Costs at

http://www.power-eng.com/articles/issue-11/features/steam-turbine-fire..."

interesting article. I would never have though about such type of protection. I had done boiler and machinery inspection at five major utility companies in MA and CT and yet none had fire protection at their turbines between 1970's and 1980's. Perhaps now things have changed. Recently, there was also an OP on fire protection on utility owned power transformers and these locations had none, yet, someone posted pictures, albeit, from locations in India about such protection.
I am amazed that this article mentions sprinkler water as an extinguishing agent, I would have thought that dry chemical agent similar to those used over deep fat fryers would have been a better choice.

 

[Sdpaddler50]

Dry chem would cause serious damage to the adjacent equipment and not be able to control a fire very well involving a 3 dim, pool fire of an ignitable liquid.

 

[chicopee]

Sprinkler water could spread that pool of fire, couldn't it?

 

[Sdpaddler50]

Water can only extinguish a flammable liquid fire if the flash point of the liquid is less than 212F. Otherwise, it is cooling, and controlling the fire and may require the FD to eventually snuff it out. Foam will do it. I am not a power plant specialist but I know water, and I believe water spray is the preferred method for these oil fires around steam and gas turbines where high pressure lube oil fires are a possiblity. The lube oils probably have fp's >200F, so it will likely extinguish the fire. As far as spreading the fire, I believe that is why the more current preferred method is a water mist or spray system with a fine mist as opposed to large drops that have a high impact velocity, but I will defer to others who know this industry, because I don't claim to.