Description of BS ISO 17179:2016 2016

This International Standard specifies the fundamental structure and the most important performance characteristics of automated measuring systems for ammonia (NH ₃) to be used on stationary source emissions, for example, combustion plants where SNCR/SCR NO _x control systems (deNO _x systems) are applied. The procedures to determine the performance characteristics are also specified. Furthermore, it describes methods and equipment to determine NH ₃ in flue gases including the sampling system and sample gas conditioning system.

This International Standard describes extractive systems, based on direct and indirect measurement methods, and in situ systems, based on direct measurement methods, in connection with a range of analysers that operate using, for example, the following principles:

• ammonia conversion to, or reaction with NO, followed by chemiluminescence (CL) NO _x difference measurement for ammonia (differential NO _x);

• ammonia conversion to, or reaction with NO, followed by non-dispersive ultraviolet (NDUV) spectroscopy NO _x difference measurement for ammonia (differential NO _x);

• Fourier transform infrared (FTIR) spectroscopy;

• non-dispersive infrared (NDIR) spectroscopy with gas filter correlation (GFC);

• tuneable laser spectroscopy (TLS).

The method allows continuous monitoring with permanently installed measuring systems of NH ₃ emissions, and is applicable to measurements of NH ₃ in dry or wet flue gases, for process monitoring, long term monitoring of the performance of deNO _x systems and/or emission monitoring.

Other equivalent instrumental methods can be used, provided they meet the minimum requirements proposed in this International Standard. The measuring system can be calibrated with certified gases, in accordance with this International Standard, or comparable methods.

The differential NO _x technique using CL has been successfully tested on some power plants where the NO _x concentration and NH ₃ concentration in flue gas after deNO _x systems are up to 50 mg (NO)/m ³ and 10 mg (NH ₃)/m ³, respectively. AMS based on FTIR, NDIR with GFC and TLS has been used successfully in this application for measuring ranges as low as 10 mg (NH ₃)/m ³.

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