Gas Processing Systems
NOx CONTROL WET SCRUBBER
Nitrogen Oxide Removal from Process Exhaust
Ergil designs and manufactures NOx control wet scrubbers that remove nitrogen oxides and acid fumes from industrial exhaust. Gas passes through packed or spray stages where scrubbing liquid absorbs NO₂ and converted NOx. Oxidant and caustic dosing improve removal of NO, which dissolves poorly in water alone. The result is visible brown fume removed and emissions held within permit limits.
NOx Chemistry
NO₂ dissolves in alkaline liquid. NO does not. An oxidation step converts NO to NO₂, then caustic absorption captures it as nitrite and nitrate salts.
Scrubber Stages
Quench or pre-wash, oxidizing stage, alkaline absorption stage, mist eliminator, stack. Stages arranged in one tower or in separate vessels.
Oxidants and Reagents
Sodium chlorite, hypochlorite, hydrogen peroxide or ozone for oxidation. Sodium hydroxide for acid neutralization. Reducing agents such as sodium sulfite in dedicated reduction stages. Choice depends on gas composition and cost.
Removal Performance
High NO₂ removal in the alkaline stage. Overall NOx removal depends on the NO/NO₂ ratio, oxidant dose and contact time. Design targets agreed with the customer emission limit.
Packing and Internals
Structured or random packing with spray headers, liquid distributors and chevron mist eliminator. Packing sized for low pressure drop and wetted-area control.
Process Control
pH and ORP control the dosing pumps. Recirculation flow, level and bleed control. Alarms for low pH and low oxidant.
Effluent Handling
Spent liquor contains nitrite and nitrate salts. Bleed stream goes to wastewater treatment. Dosing and bleed rates set to keep salts in solution.
Materials
FRP, polypropylene, PVDF or stainless steel 316L. Duplex or alloy for hot or chloride-rich gas. Lining on request.
Applications
Nitric acid plants, metal pickling and etching, fertilizer and explosives plants, battery and electronics manufacturing, chemical reactors, nitration processes and laboratory exhaust.
Fume Management
Hood and duct connections, exhaust fan and stack included on request. Sized for the full gas flow from the source.
Construction Standards
Fabrication to EN or ASME codes, hydrotest, FAT, material and weld documentation. ATEX options available.
Ergil NOx control wet scrubbers help plants meet emission rules and remove brown fume, with stable control and clear chemical dosing.
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