3454 Silica Road
Sylvania, Ohio 43560
Phone : 419.841.9984
Fax: 419.841.9535
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3454 Silica Road, Sylvania, Ohio 43560
Phone: 419.841.9984    Fax: 419.841.9535

Selective Catalytic Reduction Systems

The industry standard for NOx control technology

Control of toxic nitrogen oxides (NOx) calls for selective catalytic reduction systems (SCR). This air pollution control technology blends the exhaust waste streams with a reagent chemical – anhydrous ammonia, aqueous ammonia or urea – before passing the combination over a catalyst bed. Total NOx reduction takes place in the SCR systems through the resulting chemical reaction, transforming the previously hazardous air pollutants into harmless water and nitrogen.

This reduction chemistry is at the heart of selective catalytic reduction systems NOx control for particulate emission. Using either anhydrous ammonia or aqueous ammonia as the reagent chemical, the process can be expressed through the following equations:

4NO + 4NH3 + O2 → 4N2 + 6H2O
2NO2 + 4NH3 + O2 → 3N2 + 6H2O
NO + NO2 + 2NH3 → 2N2 + 3H2O

The use of urea as the reagent chemical for SCR Systems is expressed in the following equation:

4NO + 2(NH2)2CO + O2 → 4N2 + 4H2O + 2CO2

NOx control through selective catalytic reduction systems requires close attention to design and implementation of the SCR catalyst. The three fundamental elements of the design – proper size, composition and space velocity – take into account the ideal operating temperature range, the viscosity of the reagent chemical mixture, and the carefully estimated flow of NOx for abatement.

The design of SCR systems also rigorously controls the flow of ammonia to meet environmental requirements. The exacting standards and tuning of selective catalytic reduction systems are essential in meeting the specific requirements for each unique application.

All NOx control systems and stores of prepared reagent chemicals are fully integrated into all plant operations. Monitoring for the ideal reaction temperatures – between 440.33-836.33 degrees Fahrenheit depending on residence time – is easily maintained with integrated controls. Minimum temperatures required for the catalytic reaction to assure NOx control and compliance remains dependant on fuel types and catalyst geometry.

SCR systems are often used in conjunction with regenerative and recuperative thermal oxidizers to form a completely integrated air pollution control solution.

Contact the experts in selective catalytic reduction system design and implementation at Combustion Controls Solutions & Environmental Services today for a consultation.

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