The specific components of denitrification agents vary significantly depending on the treatment process and application, and are mainly divided into the following three categories:
Wet process denitration agent.
Core components: mainly composed of calcium carbonate (CaCO3, limestone), when used in conjunction with existing desulfurization systems, its reaction products can also serve as denitrification reducing agents. ‌‌
Auxiliary ingredients: Adding oxidants (such as wet flue gas denitrification additives) to accelerate the conversion of nitric oxide (NO) to nitrogen dioxide (NO ₂), improving denitrification efficiency to over 95%. ‌‌
Dry process denitrification agent.
Reducing agent component: Urea serves as the core reducing agent, accounting for 47%~70%, and participates in denitrification reaction by producing ammonia gas through pyrolysis. ‌‌
Auxiliary materials: Bentonite, sodium carbonate, magnesium oxide, etc. are used to adjust reaction conditions, and hydroxymethylcellulose and calcium hydroxide are used to improve the water resistance of denitrification agents. ‌‌
No ammonia denitrification agent.
Substrate: Calcium hydroxide (Ca (OH) ₂) as the main carrier. ‌‌
Catalyst: Adding manganese based or manganese copper based materials to enhance the decomposition of nitrogen oxides through catalytic action. ‌‌
Application of urea in denitrification technology
Urea is an important raw material for some denitrification processes, especially in the following scenarios:
In dry denitrification technology, ammonia gas is directly used as a reducing agent component and participates in selective non catalytic reduction (SNCR) reaction through pyrolysis. ‌‌
In the selection of reducing agents for SCR denitrification technology, urea has become a substitute for liquid ammonia and ammonia water due to its safety and transportation convenience, but it needs to be hydrolyzed to generate ammonia gas to exert its effect. ‌‌
Other auxiliary components
Catalyst carrier: Titanium dioxide (TiO ₂), activated carbon (AC), etc. are used to load metal oxides such as vanadium, iron, copper, etc., to improve the reaction efficiency of SCR technology. ‌‌
Oxidants: Ozone (O3), hydrogen peroxide (H ₂ O ₂), etc. are used to enhance the oxidation effect of NO in wet processes. ‌‌