Steam and gas turbines spin at 3000 rpm while bearing housings circulate 60-80 bar mineral oil. A leak onto the 600 C turbine shell ignites instantly. NFPA 851 sets fire-protection rules for hydroelectric, thermal and nuclear plants.
Turbine Oil Properties
- Mineral oil (ISO VG 32/46): Flash 210 C, fire 240 C
- Phosphate ester (Fyrquel): Fire-resistant, 260 C fire
- System pressure: 60-80 bar lube, 210 bar control
- Tank volume: 20-40 m3 large turbine
- Temperature: Return 50-60 C, supply 40 C
NFPA 851 Sprinklers
- Deluge system: 10.2 L/min/m2 under turbine
- Area: Bearing pedestal + oil drain zone
- K-factor: K=115 (8.0) standard
- Activation: UV/IR flame or heat
- Duration: 30 min minimum
- Drainage: 4 inch discharge + flame arrestor
Fire-Resistant Fluid
- FM DS 7-98: FR fluid preferred
- HFDU: Synthetic ester biodegradable
- HFC: Water-glycol 35-60 percent
- Retrofit: Seal change on existing system
- Cost: 3-5x mineral oil
Detection and Interlock
- UV/IR flame: 5 m dia bearing pedestal
- Heat detector: 88 C spot
- Turbine trip: Fire -> emergency shutdown
- Lube oil pump: Emergency DC 45 min coast-down
- H2 cooling: Generator CO2 purge
Turkish Plant Examples
- Ataturk HEP: 8x300 MW Francis turbines
- Afsin Elbistan: 4x360 MW lignite
- Hamitabat: Combined-cycle gas turbine
- Akkuyu NPP: 4x1200 MW VVER - NFPA 805
- Maintenance: Turbine oil analysis every 3 months
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Sources & Further Reading
NFPA 851, NFPA 850, FM DS 7-98, IEEE 979, API 614. NFPA 851 Hydroelectric Generating Plants.