That is why we are wondering if there are other FB plants that have the scrubber installed. It seems unusual and unnecessary, however, we are working with a plant that has one and is having problems with corrosion and deposition downstream of the scrubber.
In the USA, a new CFB boiler will be required to have a dry scrubber installed. That is determined by the EPA as Best Available Controllable Technology.
The fluid bed boiler normally uses limestone as the bed medial, and this will remove 85-03% of so2. However, there are many cases where the bed media is not limestone- it can be sand ( riverbed sand- round edges as opposed to millsand with sharp edges)or other inert media.
These inert media are used if you are burning garbage or other material that would form a eutectic slag if limetone were used. In those cases, a scrubber is used.
When we consider that the Ca/S ratio in the bed increases a lot if higher SOx efficiencies are required then a supplementary FGD might be the best economical solution despite the higher capital cost.
A downstream FGD system can operate with Ca/S ratio as low as 1.1. The furnace bed can operate with Ca/S ratio as high as 2.5 (for very high efficiencies and high S content).
This may be true for very high sulfur fuels as petcoke (up to 7% S)
I think Jacksonville CFB power plant was planned this way.
