The requirement for SCR & SNCR (DeNOx)

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For decades, coal has been the predominant fuel choice for many power stations globally, despite being one of the most polluting sources of energy. As environmental regulations in regions like Europe, China, and India have tightened with stringent emission limits, coal-fired power stations face increasing challenges and costs to comply. Consequently, they are adopting advanced technologies such as Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR).

SCR systems are not limited to large boilers but are also deployed in small boilers, gas turbines, diesel engines, and even automobiles. These systems have demonstrated significant reductions in nitrogen oxides (NOx) emissions, ranging from 70% to 95%. NOx is a primary pollutant produced during fossil fuel combustion, contributing to environmental issues such as smog, acid rain, and reduced visibility. It also poses health risks, including respiratory problems, prompting widespread adoption of NOx reduction technologies in power stations worldwide.


Implementing SCR technology represents a proactive approach by power stations to mitigate their environmental impact and ensure compliance with stringent emissions regulations. By reducing NOx emissions, SCR systems not only improve air quality but also support efforts to safeguard human health and promote sustainable energy practices globally. As coal-fired power plants increasingly invest in SCR and SNCR technologies, they contribute to a cleaner and healthier environment while navigating the evolving landscape of environmental compliance.

How it works

In the combustion process, nitrogen reacts with oxygen under high temperatures to form nitrogen oxides (NOx), which include nitrogen monoxide (NO) and nitrogen dioxide (NO2). Meeting stringent emission limits for NOx requires plants to implement DeNOx processes to reduce these emissions to permissible levels.


DeNOx processes typically involve reacting nitrogen oxides in the flue gas with ammonia water or urea at elevated temperatures. Ammonia or urea reacts with both NO and NO2 to convert them into nitrogen (N2), water vapor (H2O), and in the case of urea, carbon dioxide (CO2). Selective Catalytic Reduction (SCR) DeNOx systems are commonly installed in large coal-fired power stations, where they effectively reduce NOx emissions. For smaller to mid-size incineration plants and power stations using Circulating Fluidized Bed (CFB) boilers, Selective Non-Catalytic Reduction (SNCR) technology is often employed to achieve similar emission reduction goals.


By implementing DeNOx technologies like SCR and SNCR, combustion plants improve air quality by significantly reducing NOx emissions, thereby mitigating environmental impacts such as smog formation and acid rain. These technologies not only ensure compliance with emissions regulations but also support sustainable practices in energy production, contributing to cleaner and healthier environments worldwide.

What we do

In order to effectively manage Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) systems, continuous monitoring is essential throughout the entire process. This monitoring ensures that these emissions control technologies operate efficiently and effectively. CODEL provides a comprehensive range of advanced products designed to monitor both input and output gases, as well as flow and dust emissions, using cutting-edge technology. These monitoring solutions are engineered to deliver reliable and accurate data, enabling operators to optimize the performance of SCR and SNCR systems while ensuring compliance with stringent environmental regulations. By leveraging state-of-the-art monitoring technology from CODEL, industries can enhance their operational efficiency, minimize environmental impact, and maintain sustainable practices in emissions control.

SNCR Process
SCR Process

Suitable Products

The DCEM2100 is a dual-pass transmissometer configured for the continuous measurement of opacity and dust concentration in flue gases.

Opacity / Dust

CODEL’s unique flow monitors measure the velocity of stack gases using a highly accurate time of flight measurement that is derived from a cross correlation analysis of the infra-red emissions of the turbulent gas.

Gas Flow

The GCEM40E hot extractive multi-channel gas analyser is CODEL’s industry-proven continuous emissions monitor for difficult applications

CO, NOx, SO2, HCl, CH4, CO2 & H2O

The GCEM40 analyser is an in-situ device which is cost-effective, low maintenance and designed both for process control and emissions monitoring.

CO, NOx, SO2, HCl, CH4, CO2 & H2O

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