De-Nox System

High Dust Configuration In the case of high-dust configuration, the SCR reactor is installed right at the rear of the economizer, and this location becomes the front of the air pre-heater. The biggest benefit of this structure is the fact that there is no separate pre-heating required to insert gas into the SCR reactor. Generally, the inserted gas is 300-430°C. The basic advantage of a high-dust system is the low initial investment cost and the savings in operational costs. Low Dust Configuration In this arrangement, the catalyst becomes placed in the rear of the electrostatic precipitator or the bag-filter. Since the gas at the rear of the electrostatic precipitator is inserted into the SCR reactor, extremely small particles of dust are inserted; on the other hand, a lot of SO2 is also inserted. Since the temperature of emission gas does not reach the reactive temperature of De-NOx Catalyst, in many cases it requires an extra temperature-raising system. Tail End Arrangement This structure is widely being applied in Western Europe. Also, this is used for remodeling of the original generating facilities. The SCR facility is installed at the very rear of other emission gas treatment facility. (eg. At the rear of a precipitator or Desulfurization Facility (FGD)) Since there is a very small amount of dust or SO2 in the emission gas, exposure of catalyst to catalyst toxin may be prevented. Since the temperature of emission gas does not reach the reactive temperature of De-NOx Catalyst, in many cases it requires an extra temperature-raising system.