Flue gas desulfurization in hard coal and lignite-fired power plants

The flue gas desulphurization (FGD) system removes the sulphur compounds (SO2, SO3) and acids from the flue gas. The majority of sulphur removal systems use wet FGDs, where the gases are passed up in a tower against a counterflow of a limestone slurry to remove SO2, SO3, HCl and HF. The limestone concentration entering the absorption tower needs to be controlled for efficient operations. Gypsum is produced as a solid reaction product and is removed from the slurry by hydro cyclones. The wet gypsum is further dewatered and processed in the wet gypsum storage hall, producing a useful by-product.

Traditionally the concentration measurement of the limestone-slurry has been measured using nucleonic density meters, since this was the only reliable technology for this application. Straight tube Coriolis meters have now been introduced to enable density measurement in this application. The new KROHNE OPTIMASS 7400 single straight tube Coriolis flowmeter with a titanium measuring tube is field proven as a suitable solution for the measurement of both density and flow of the limestone slurry. Simple flow measurements of these abrasive liquids can be solved with the OPTISONIC 6300 W/F ultrasonic clamp-on flowmeters, or the inline OPTIFLUX magnetic flowmeter. The patented drop antenna of the OPTIWAVE 6500 radar level gauge reliably avoids any dust build-up and drastically improves the availability of radar sensors in the lime silo environment.