Application: The Topsøe SCR DeNOx process removes NOx from flue gases through reactions with an ammonia-based reducing agent over a specially designed fixed-bed monolithic catalyst. By carefully selecting the catalyst parameters, channel size and chemical composition, the process covers a wide range of operating conditions and flue-gas dust contents and may be applied to practically all types of refinery units including furnaces, boilers, crackers and FCC units.
Products: The Topsøe SCR DeNOx converts NOx into inert nitrogen and water vapor. The process may be designed for NOx reductions in excess of 95% and with an ammonia leakage of just a few ppm.
Description: The reducing agent such as ammonia or urea, aqueous or pure, is injected into the flue gas stream in stoichiometric proportion to the amount of NOx in the flue gas, controlled by measurement of flue gas flow and NOx concentration. The injection takes place in a grid over the entire cross-section of the flue-gas duct to ensure a uniform distribution of NOx and ammonia upstream the SCR catalyst vessel.
The process incorporates Topsøe’s well-proven corrugated monolithic DNX catalyst. DNX is manufactured in small units, which may be combined into larger modules to match any requirement in terms of vessel dimensions and pressure drop, and in both horizontal and vertical vessel configurations.
The DNX catalyst is based on a fiber-reinforced ceramic carrier, which gives a unique combination of a high strength and a high micro-porosity. The high micro-porosity provides a superior resistance to catalyst poisons and low weight. The fibers add flexibility to the catalyst so that it can tolerate a wide range of heating and cooling rates.
Operating conditions: Typical operating conditions range from 300°C to 500°C (570–930°F), up to 3 bar (44 psia) and up to 50 g/Nm3 of dust in the flue gas.
Licensor: Haldor Topsøe A/S.