SNCR stands for Selective Non-Catalytic Reduction, it is a NOx reduction method. Ammonia is injected into the flue gases to reduce the NOx back to H2O and N2. The key to success is being able to get the ammonia mixed with the flue gas rapidly and well, so the reactions can take place within the temperature window of around 1800 degrees Fahrenheit . As the temperature drops, the reaction slows dramatically and insufficient reduction may be an issue or unreacted ammonia may now be your emission pollutant.
EFFECTIVE AND PRECISE NOx REDUCTION METHODS
A SCR, which stands for Selective Catalytic reduction, relies on the same chemical reactions, but they are promoted by the presence of a bed of catalyst. The catalyst is very effective in a lower and wider temperature range and can allow the reduction of NOx to very low levels.
REDUCING COSTS AND CLEANER PRODUCTIONS
It is also possible to use a combination of the two, knocking down a large portion of the NOx with an SNCR, and cleaning up the balance with an SCR. This can have the advantage of reducing the cost and making the installation easier by requiring a much smaller catalyst bed.
The source of the ammonia is chosen based on several criteria. Anhydrous ammonia, when available by pipeline or locally, would often be the best choice economically, however the safety considerations of handling ammonia in this form can present obstacles. Aqueous ammonia is much safer to handle if imported via truck and storing on site, but its dilution results in higher shipping costs. Urea is a fairly safe form to obtain ammonia in, but requires solid handling and mixing facilities.
Each NOx reduction technology, or combination requires careful consideration to determine the best technical and economic solution. A full study is needed to evaluate the regulatory requirements, ammonia sources, storage requirements, injection technologies, catalyst, and installation.
BD Energy Systems’ dedicated team of experts have the ability to perform this evaluation, hand-in-hand with our clients, to provide the best solution possible.
THE BEST SOLUTIONS AT THE BEST PRICES
