Flue Gas Denitrification System (DeNOx)

Flue Gas Denitrification System (DeNOx) is used to reduce nitrogen oxides (NOx) in industrial flue gas. The system introduces a suitable reducing agent into the gas stream and promotes a chemical reaction that converts nitrogen oxides primarily into nitrogen and water.

Two commonly used processes are Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). SCR uses a catalyst to facilitate the reaction at a controlled temperature, while SNCR introduces the reducing agent directly into a suitable high-temperature section without a catalyst.

The reducing agent may include ammonia or urea-based materials, depending on the selected process. An injection system distributes the reagent into the flue gas to achieve sufficient contact with the nitrogen oxides.

In an SCR system, the treated gas passes through a catalyst layer after reagent injection. The catalyst provides an active reaction surface and supports the conversion of NOx. In an SNCR system, the reaction takes place within a defined temperature window inside the furnace or flue gas duct.

The system can include reagent storage, preparation equipment, metering devices, injection lances, mixers, catalyst modules where applicable, temperature sensors, and control components. Operating parameters such as flue gas temperature, NOx concentration, gas flow, reagent dosage, and oxygen content influence the treatment process.

Main Components

• Flue gas inlet

• Reducing agent storage and preparation unit

• Metering system

• Reagent injection system

• Mixing section

• SCR catalyst module or SNCR reaction zone

• Temperature sensors

• NOx monitoring instruments

• Control system

• Treated gas outlet

DeNOx Processes

SCR

Selective Catalytic Reduction uses a catalyst to promote the reaction between nitrogen oxides and the injected reducing agent. The gas passes through the catalyst layer under controlled temperature conditions.

SNCR

Selective Non-Catalytic Reduction injects the reducing agent directly into a high-temperature flue gas zone. The reaction occurs without a catalyst when the gas temperature is within the required range.

Operating Factors

• Flue gas temperature

• NOx concentration

• Gas flow rate

• Reducing agent dosage

• Oxygen concentration

• Reaction residence time

• Catalyst condition for SCR systems

Applications

• Industrial boilers

• Power generation

• Cement kilns

• Waste incineration

• Steel and metallurgical processes

• Chemical processing

• Industrial furnaces

• Combustion flue gas treatment