Typical Baseline
A typical 250 MW CFBC (circulating fluidised bed combustion) boiler running on conventional castable in the cyclone, return-leg and burning zone tends to experience 8–11 forced outages per year from refractory failure, abrasive bed-ash erosion compounded by thermal cycling during start-stop cycles. Each outage costs a captive plant approximately ₹70–90 lakh per day (USD 74,000–95,000) in alternative grid power, calculated at the ~₹3/kWh differential between captive generation and industrial grid tariff.
Diagnostic Pattern
- Cyclone hot face: typical abrasion wear ~1.2 mm/1000 hours on conventional castable
- Return leg: thermal cycling cracks every 4–6 weeks
- Baseline refractory: conventional castable (~15% cement), designed for static furnaces, not CFBC
- Bed temperature: 850–900°C, but wall temperature spikes to ~1100°C during transients
Recommended Specification
- Cyclone hot face: erosion-resistant LCC-70 with SiC additive (15% SiC)
- Cyclone backup: IFB-26 insulating brick, 65 mm
- Return leg: LCC-70 standard, 100 mm hot face
- Burner walls: precast LCC-80 panels (replaceable in 4 hours)
- Total refractory replaced: 38 tonnes castable + 22 m³ insulation
Installation Best-Practice
- Plant shutdown window: 8 days for full burner-zone re-cast
- Castable poured in 200 mm lifts using forced-action mixer
- Anchors: SS-310 V-anchors at 250 mm centres
- Dry-out: per Calderys standard CFBC schedule (extended to 96 hours total)
- Pre-commissioning: hydrostatic test of all penetrations
Expected Outcome Range
Illustrative, not project results. Actual outcomes vary with operating conditions and installation quality.
- Expected forced outages from refractory: 8–11/year → 2–3/year (~70% reduction typical)
- Expected grid power cost saved: ~₹4.5–5 crore/year (USD 475,000–530,000)
- Castable cost per tonne of fuel burnt: similar (premium castable costs offset by lower outage frequency)
- Plant load factor (PLF) improvement: typically +1.5 to +2.0 percentage points year-on-year
- Major refractory shutdown deferred from 18 months to 28–32 months
“CFBC boiler refractory is a different discipline from static furnace refractory. For this application class, erosion-resistant LCC with SiC additive in cyclone hot faces is essential, conventional castable engineered for static duty is not the right specification regardless of how it is rated thermally.”