CFBC ash characterization: The case of the Provence 250 MW unit
- Electricite de France, Chatou (France). Direction des Etudes et Recherches
- Univ. Paris 7 Val-de-Marne, Creteil (France). Lab. Interuniversitaire des Systemes Atmospheriques
The Provence 250 MW Circulating Fluidized Bed Combustion Unit (Gardanne, France) is burning a high sulfur (2 to 4%), high ash content (30%) local lignite. This peculiar fuel already contains about 15% of CaO which allows it to capture the sulfur dioxide in situ without adding any complementary sorbent. The ash chemical composition (bed ash and ESP ash) reflects the particularities of the coal: calcium compounds are mainly preponderant (40% assessed between 19% as CaSO{sub 4}, 12% as free lime and 9% as calcium silicates and aluminates) compared to silica (13%) and other oxides (less than 5% each). The presence of calcium sulfide ({approximately} 0.3%) can be attributed to both intensified air staging and high SO{sub 2} concentration in the furnace. It could pose handling and disposal problems due to reaction with moisture (H{sub 2}S release). Batch leaching tests have shown that considerable amounts of sulfates are released into the water (up to 2 g/l). However, the rainwater effect on a landfill is different from a batch test: due to high lime content, wetted ash tends to harden and becomes impermeable. The hardening is due to hydration and partial crystallization (gypsum and ettringite formation). However, hardened samples do not seem to retain compounds from leaching: high quantities of calcium and sulfates are still leached from these crushed samples.
- OSTI ID:
- 355851
- Report Number(s):
- CONF-9705116--; ISBN 0-7918-1557-9
- Country of Publication:
- United States
- Language:
- English
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