NewEcotube® nitrogen oxides reduction installation (NOX)
The NOX reduction system offered by ICS is based on a modified Ecotube System technology developed in cooperation with the Swedish company Ecomb AB. The new NOx reduction installation is based on ICS patent application no. P.243551 (hereinafter referred to as the deNOx system). Unlike many technologies available on the market, it combines two methods of nitrogen oxide reduction:
- a primary method (based on a combination of primary air stratification and flue gas recirculation, leading to optimized combustion),
- and a secondary method – Selective Non-Catalytic Reduction (SNCR), i.e. the injection of a reagent (ammonia water) into the boiler furnace chamber.
The NOx reduction system for boilers utilizes two fans:
- a process gas fan that replaces the secondary air system and its fans. The process gas fan introduces process gas (a mixture of secondary air and flue gases, or flue gases alone, or air alone) into the boiler’s combustion chamber under a pressure of several kilopascals through a system of injection lances mounted on the boiler walls,
- a flue gas recirculation fan that introduces flue gases into individual air zones below the grate through a modernized primary air distribution system.
In some boilers, this fan also supplies the medium for the Pneumatic Grate Sealing System (SPDR) (ICS patent application no. P.419237).
The proposed technology, utilizing both internal and external flue gas recirculation as well as stratification of air introduced into the combustion chamber in the form of high-energy jets, ensures a more uniform temperature distribution and creates an optimal temperature window for the SNCR process. It also results in a low oxygen concentration in the flue gases (depending on boiler conditions). This significantly reduces baseline NOx emissions, improves the mixing of flue gases with the reagent, and consequently lowers reagent consumption in the secondary method while simultaneously improving combustion efficiency through reduced CO emissions and lower oxygen and fly ash content in the flue gases.
Additional advantages of the deNOx technology compared to other emission reduction techniques include:
- improved turbulence, i.e. better mixing of gases with the reagent, which enhances combustion quality, reduces NOx emissions, and minimizes reagent consumption,
- the ability to achieve a lower stoichiometric ratio in the combustion zone, resulting in higher boiler efficiency and a lower flue gas flow rate (depending on boiler condition),
- increased thermal performance of the boiler’s combustion chamber, potentially translating into higher overall thermal output due to higher average heat flux on the chamber walls,
- longer intervals between boiler maintenance shutdowns,
- no water consumption for flue gas temperature regulation, thus avoiding heat losses associated mainly with the energy required for water evaporation.
The NewEcotube technology is automatically controlled by an autonomous near-boiler deNOx system control unit, dedicated to each boiler individually.
