Geothermal Well: NFPA 850, H2S 500 ppm, Flash Separator and Kizildere Lessons

Turkey is the world's 4th largest geothermal producer at 1,700 MW. Denizli Kizildere is 242 MW, Aydin Germencik 162 MW. Geothermal fluid at 200-250 C carries CO2, H2S and CH4. NFPA 850 treats flash separators, pentane ORC units and H2S abatement as fire hazards.

Geothermal Fluid

• CO2: 90 percent of gases
• H2S: 100-500 ppm (toxic)
• CH4: 1-5 percent
• Temperature: 180-250 C
• Wellhead pressure: 10-25 bar

Flash Separator Safety

• 1st flash: 180 C, 10 bar
• 2nd flash: 120 C, 2 bar
• Demister: Captures silica particulate
• Rupture disc: MAWP x 1.1
• Emergency vent: Upward flare

Pentane ORC Risk

• Binary cycle: n-pentane/isobutane
• Flash point: -49 C Class IA
• LEL: 1.4 percent
• Sprinkler: Deluge 12.2 L/min/m2
• Ex electrical: Zone 1 binary

H2S Abatement

• LO-CAT: H2S to S (redox)
• Stretford: Older tech
• Reinjection: NCG + water
• Monitoring: 10 ppm TLV-TWA
• SCBA: Above 100 ppm

Kizildere and Lessons

• Kizildere Denizli: 242 MW, online 1984
• Germencik Aydin: 162 MW
• Efe Aydin: 47 MW
• 2020 pentane leak: US Puna
• The Geysers CA: 1,517 MW world's largest

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