Spray Dryer Absorption (SDA) is a dry scrubbing process that is generally used for low-sulfur coal.

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Spray Dryer Absorption (SDA) is a dry scrubbing process that is generally used for low-sulfur coal. SDA FGD systems are typically located after the air preheaters, and the waste products are collected either in a baghouse or electrostatic precipitator. However, to achieve sulfur dioxide (SO2) reduction above 80% with good reagent use, the dry scrubber is generally followed by a baghouse.