Steam Turbine Insulation: Heat Loss & Savings
Steam-turbine casings and valve chests run hot over a very large surface, so a bare or poorly re-lagged turbine wastes a lot of recoverable heat. Removable insulation pads cover the casing while allowing the frequent inspection turbines require.
Heat loss vs insulated — by surface temperature
| Surface temp | Bare loss | Insulated | Outer surface | Reduction |
|---|---|---|---|---|
| 250 °C | 2,300 W/m² | 152 W/m² | 35 °C | 93.4% |
| 350 °C | 3,300 W/m² | 255 W/m² | 46 °C | 92.3% |
| 450 °C | 4,300 W/m² | 381 W/m² | 58 °C | 91.1% |
Per-m² flat-surface flux, ASTM C680 / ISO 12241, 50 mm Lamella (≤220 °C) or 100 mm Wired mat (>220 °C), 20 °C ambient. Multiply by the bare area.
Worked examples (per year, 8,000 h, natural gas)
| Item | Heat saved | Energy/yr | CO₂/yr | € saved/yr |
|---|---|---|---|---|
| A steam-turbine casing (15 m², 350 °C) | 45.7 kW | 430 MWh | 86.8 t | €24,930 |
| A turbine inlet / valve chest (4 m², 400 °C) | 13.9 kW | 131 MWh | 26.5 t | €7,608 |
FAQ
How much heat does a bare steam turbine lose?
At 20 °C ambient (ASTM C680): a steam-turbine casing (~15 m², 350 °C) loses about 45.7 kW; a turbine inlet / valve chest (~4 m², 400 °C) about 13.9 kW. Insulating a steam-turbine casing saves ≈430 MWh and ≈86.8 t CO₂ per year (8,000 h).
Can you insulate steam-turbine casings and similar?
Yes. Turbine casings are opened for overhaul and monitored for distortion, so insulation must be removable. Inzonex pads come off in sections and refit precisely. Inzonex covers steam-turbine casings, valve chests, governor and inlet assemblies. The outer surface drops to a touch-safe ≤45 °C and the part stays serviceable.
How much does steam turbine insulation save?
Each item saves up to 96% of its bare loss. A steam-turbine casing at 350 °C saves ≈24,930 €/yr of energy (≈430 MWh, ≈86.8 t CO₂) at typical gas prices; payback is usually under two years.
What insulation thickness is used?
Up to 220 °C surface: 50 mm mineral-wool (Lamella); above 220 °C: 100 mm (Wired mat), because conductivity rises with temperature. Both keep the outer surface ≤45 °C.