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).
Particular features:
- Highly reliable solution with low CAPEX
- Reagent used in dry form.
- SOx-removal results (limited to approx. 70%efficiency is pending on temperature and watercontent of fluegas)
- Small footprint equipment.
- Different kinds of dry reagent can be used.
- Dry reaction products (removed from gas in the precipitator) can be recycled to feed.
Working Principle
Working Principle of Dry sorption with entrained flow reactorA dry reagent for SOx removal is injected to the raw gas upstream of the Entrained Flow Reactor where the chemical reaction takes place.
Reaction products are removed from the gas together with the furnace dust (dedusting) in the dedusting equipment.
The essential process stages are:
- Absorbent preparation and dosing
- Removal of SOx (acid gases) in the reactor
- Particulate removal device (ESP, bag filter, candle filter)
- Solids recirculation and product discharge
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