Power & Energy Captive Power Plant · CFBC Boiler · Maharashtra

SiC tiles + chemically-bonded LCC: 4 → 12 months in the cyclone

Q: Is this spec worth it for a 30 TPH boiler?

Often yes if your bed material is abrasive and your cyclone velocity is in the CFBC design band. We'd run a wear-velocity survey first — if your throat velocity is well below 22 m/s a less aggressive spec may be enough.

Q: Does this apply to AFBC boilers too?

AFBC operates with much lower particulate carryover so the erosion regime is different — usually a chemically-bonded LCC alone is sufficient, no SiC tile needed. We spec by application, not by category.

Q: Can we phase the install across two outages?

Yes — most plants we work with do the cyclone in one outage and the bed area in a second outage. We'll plan the sequencing around your shutdown calendar.

A 60 TPH CFBC boiler was losing cyclone-tile lining every 4 months to abrasive erosion. Switching from cast SiC blocks to dense pressed SiC tiles backed with chemically-bonded LCC tripled life to 12 months — a full annual-shutdown cycle.

Cyclone tile life

Before

4 months

After

12 months

Gain

3×

Forced outages from erosion

Before

2 / yr

After

0 / yr

Gain

−100%

Replacement spend / yr

Before

₹ 3.8 cr

After

₹ 1.4 cr

Gain

−63%

The Problem

A 60 TPH circulating fluidised-bed combustion (CFBC) boiler operating on washery-reject coal was losing the cyclone-section refractory tile lining every 4 months. Particulate erosion at the cyclone throat and lower barrel was the dominant failure. Two forced outages per year were attributed directly to spalled tiles letting the carbon-steel shell see hot bed material. Annual replacement spend ran at ₹3.8 cr.

Site Survey Findings

What our site engineer measured, sampled, and recorded before specifying any change.

▸ Cyclone gas velocity at the throat measured at 24–28 m/s — at the upper end of CFBC design range.
▸ Bed-material sampling showed silica content 38% and average particle size 240 µm — abrasive load was high.
▸ Existing tiles were cast SiC in 200 × 200 mm format with mortar joints. Joint mortar was failing first, allowing tiles to lift; once one tile was lost, neighbours followed quickly.
▸ Anchor system was conventional Y-anchor — adequate for a calmer environment but not for the cyclone's vibration + thermal cycling combination.

The Spec We Proposed

Zone-by-zone re-spec — change only what the wear data justifies, leave the rest alone.

▸ Cyclone throat and lower barrel re-lined with dense pressed SiC tiles (>85% SiC, <2% open porosity) in 100 × 100 mm format — smaller tiles distribute thermal-stress and vibration loads.
▸ Backing layer: chemically-bonded LCC with hot MOR > 10 MPa at 1000 °C — gives a stiff, vibration-resistant substrate that doesn't shed under the tile.
▸ Joint material: SiC-bearing chemically-bonded mortar with phosphate binder — survives the temperature + abrasion cycle far better than the conventional silicate mortar in service.
▸ Anchor system: dual Y-anchors at 100 mm pitch (vs. 150 mm previously), 310SS, with vermiculite tip caps to absorb thermal expansion of the tile.
▸ Install supervision included a hold point after every 10 m² of tile placement — joint thickness audited at <1.5 mm.

Outcome

First installation ran the full annual planned-shutdown cycle (12 months) with no forced outage attributed to refractory. Visual inspection at planned shutdown showed tile thickness loss of 4–6 mm — well within tolerance for a second campaign with selective replacement only of the worst tiles at the throat. Forced outages from cyclone erosion dropped from 2 per year to 0. Annual replacement spend dropped from ₹3.8 cr to ₹1.4 cr (full reline material + selective campaign-2 maintenance). The plant has now adopted this spec for the second boiler at the same site.

Lessons Applied to Other Plants

What this engagement taught us — now standard practice on every comparable plant we engage with.

▸ In high-velocity cyclone applications, dense pressed SiC outperforms cast SiC blocks at the same SiC content because of lower porosity and more uniform grain bonding.
▸ Smaller tile format (100 × 100 mm) costs slightly more to install but distributes vibration and thermal loads better than 200 × 200 mm — net win on campaign life.
▸ Joint material is as important as tile material in erosion environments. A premium tile with conventional mortar will lose joints first, then tiles. Spec the joint, not just the tile.

A note on customer anonymisation: Customer name, exact location, and proprietary process data are withheld at our customer's request as standard NDA practice. Technical details (failure modes, lining specs, before/after metrics, reasoning) are reported as-measured and as-documented in our engagement file.

Frequently asked

Is this spec worth it for a 30 TPH boiler? +

Often yes if your bed material is abrasive and your cyclone velocity is in the CFBC design band. We'd run a wear-velocity survey first — if your throat velocity is well below 22 m/s a less aggressive spec may be enough.

Does this apply to AFBC boilers too? +

AFBC operates with much lower particulate carryover so the erosion regime is different — usually a chemically-bonded LCC alone is sufficient, no SiC tile needed. We spec by application, not by category.

Can we phase the install across two outages? +

Yes — most plants we work with do the cyclone in one outage and the bed area in a second outage. We'll plan the sequencing around your shutdown calendar.

Have a similar wear pattern at your plant?

Send us your campaign-life numbers, slag/feed chemistry if available, and a few photos of the failure. We'll come back with a survey plan and an indicative re-spec.

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SiC tiles + chemically-bonded LCC: 4 → 12 months in the cyclone

Outcome metrics

The Problem

Site Survey Findings

The Spec We Proposed

Outcome

Lessons Applied to Other Plants

Frequently asked

Have a similar wear pattern at your plant?