Some process conditions, like temperature, increase the specific reagent consumption of dry flue gas cleaning processes. These higher consumptions generate more by-product, waste more unreacted reagent, and significantly increase the compliance cost. Injection of calcium reagent at high temperatures (900 – 1000°C) helps the reaction with sulfur components. However, an injection like this can also affect the ash behavior, especially by lowering the ash melting point.
CleanCalco® Depurcal is an engineered hydrated lime containing magnesium, and is optimized for high-temperature injection. The product, when injected early in the process and between 900 and 1000°C in a boiler, is directly thermally activated to create a micro-structure and porosity. This helps to:
- directly neutralize SO3, SO2, HF and some HCl.
- protect the equipment from aggressive acid gases.
- increase the ash melting point thanks to the magnesium content, thus improving the cleanness of the tube-sheet and consequently the thermal efficiency of the boiler.
Used initially in Waste-to-Energy plants (but also applicable in heat and power boilers), this treatment is extremely efficient in reducing pollutants in the boiler itself. It allows the downstream duct sorbent injection to operate as a simple polishing FGC step.
- Direct neutralization of acids (SO2, SO3, HF and HCl) in boiler/furnace.
- Stable pollutant load in the downstream polishing FGC unit (no peak).
- Optimized and low consumption of sorbent at the polishing step.
- Reduction of PCDD (dioxins) and PCDF (furans) formation.
- More porous, friable ash thanks to melting point modification.
- Cleaner boiler/furnace.
- Reduced boiler/furnace corrosion.
- Improved boiler efficiency.
- Savings on maintenance.
- Increased reliability of FGC unit.