Removal of SOx by dry scrubbing

The dry sorption process refers to the practice of injecting a dry alkaline mineral into a flue gas stream to reduce acid gas emissions (i.e. SO₃/H₂SO₄, HCl, SO₂, and HF). Two basic steps are considered:

• The first step is injection of a dry sorbent into the entrained flow reactor providing sufficient physical and chemical reaction time to catch and agglomerate acidic gas and organic compounds as well as heavy metals.
• During the second step, these compounds are removed by a downstream particulate matter control device such as a baghouse filter, electrostatic precipitator or candle filter.

Hydrated lime (Ca [OH]₂) is normally used as the absorbent, either directly as calcium hydroxide in the form of a dry powder or produced on site from calcium oxide (CaO) in a dry hydration plant. Other often used sorbents are trona (Na₂CO₃ ∙ NaHCO₃ ∙ 2H₂O) and sodium bicarbonate (NaHCO₃). 

Working Principle