Dry Scrubber Unit
DEC.DSU™
The Dry Scrubber Unit (DEC.DSU™) is an engineered dry-phase acid gas abatement system for industrial exhaust streams where liquid waste disposal is restricted, or where the exhaust chemistry favours a solid-phase reagent. By introducing an alkaline sorbent — injected as a powder, formed as a pellet, or structured as an extruded absorption honeycomb — into the flue gas, the system neutralises Hazardous Air Pollutants (HAPs) without generating liquid effluent. The reacted byproduct is captured by a high-efficiency downstream filtration stage and, depending on the reagent and target pollutant, may be recovered as a marketable material.
DEC designs and engineers DEC.DSU™ systems across the full range of dry scrubbing configurations: from simple in-duct sorbent injection on compact installations to multi-stage fixed-bed and honeycomb-reactor units targeting sub-ppm emission limits on large industrial kilns. Each system is sized against the specific gas volume, pollutant profile, temperature envelope, and discharge requirement of the application.
principles of operation | Dry Scrubber Unit • DEC.DSU™
Dry scrubbing combines chemical neutralisation and physical capture to eliminate acidic gases and particulate matter from industrial exhaust. Unlike Wet Scrubber Unit (DEC.WSU™), no scrubbing liquor is used; the reagent and its reaction products remain in the solid phase throughout, eliminating the need for effluent treatment or water make-up.
The core chemistry is an acid–base reaction between the alkaline sorbent and the acidic gas species in the flue stream. Common target pollutants include hydrogen fluoride (HF), hydrogen chloride (HCl), sulfur dioxide (SO2), and sulfur trioxide (SO3).
Reaction kinetics depend on flue gas temperature, reagent surface area, contact time, and the stoichiometric ratio of reagent to pollutant. DEC engineers each system to optimise these parameters for the specific pollutant load and the required removal efficiency.
From reaction to capture | Dry Scrubber Unit • DEC.DSU™
- Sorbent introduction
A dry alkaline sorbent - hydrated lime (Ca(OH)2), sodium bicarbonate (NaHCO3), trona, or an engineered structured absorbent - is introduced into the flue gas. The introduction method (powder injection, fixed bed, or structured honeycomb block) is determined by the application.
- Gas–solid contact and reaction
Acidic gas molecules diffuse to the sorbent surface, adsorb, and undergo chemical neutralisation. The product of this reaction is a dry, solid salt. Residence time and specific surface area of the sorbent govern capture efficiency at this stage.
- Particulate collection
The treated gas stream, carrying entrained sorbent and reaction-product particles, passes through a high-efficiency particulate control device — typically a pulse-jet fabric filter (baghouse) or a ceramic candle filter. The filter simultaneously removes unreacted sorbent, reaction salts, and any pre-existing particulate matter from the gas phase.
- Byproduct handling
Collected solids are discharged via screw conveyor or pneumatic system for disposal or, in the case of calcium fluoride produced from HF neutralisation, potential recovery as a commercially valuable fluoride product.
available configurations | Dry Scrubber Unit • DEC.DSU™
DEC.DSU™ systems are supplied in three principal configurations, matched to the pollutant loading, required removal efficiency, operational philosophy, and space constraints of the installation.
- Dry Sorbent Injection • DSU_DSI™
Powdered sorbent is pneumatically injected into the ductwork upstream of a fabric filter. Low capital cost, compact footprint; best suited to moderate removal targets (up to ~90% HCl, up to ~70% SO2) and retrofitting existing filter installations.
- Circulating Dry Scrubber • DSU_CDS™
A dedicated reaction vessel ensures extended gas–sorbent contact time via recirculation of partially reacted material. Achieves >95% removal of HCl and HF; well-suited to waste-to-energy, cement, and metal processing applications.
- Honeycomb Absorption Block • DSU_HAB™
Extruded structured absorbent blocks (DEC.HAB™), typically calcium-hydroxide-based, are stacked in a fixed-bed reactor. High reagent utilisation, low pressure drop, and no moving parts. Optimised for HF removal from kiln and glass industry exhaust at temperatures up to 300 °C.
contact DEC
If you are looking for a reliable and efficient Dry Scrubber Unit, feel free to contact DEC: we can help you assess your needs and recommend the best DSU for your operation.
