Call us: +44 (0) 1908 227722 | Email us here |


Most of the NOx (oxides of nitrogen) formed during combustion processes is the result of two oxidation mechanisms:

Thermal NOx - reaction of nitrogen in the combustion air with excess oxygen at elevated temperatures.

Fuel NOx - oxidation of nitrogen that is chemically bound in the coal and oil.

Although NOx emissions can be reduced through improvements to the combustion plant, most reduction is achieved in practice through post-combustion treatment.


SNCR - Selective Non-Catalytic Reduction
SCR - Selective Catalytic Reduction

 In both cases, the fundamental reaction is the same. 
A source of ammonia (NH3) is injected into the flue gas stream to act as a reducing agent, transforming NOx to harmless nitrogen.
Any unreacted NH3 then itself becomes an environmental pollutant.


"Ammonia slip" is an important process measurement for control of De-NOx.
TDLAS is ideally suited to measuring the low levels of NH3 for "ammonia slip" control, and fast response allows direct feedback to injection systems.
In some cases, the reaction of sulphur oxides with excess ammonia can result in Ammonium Bisulphate (ABS) formation whch can affect sampling systems. 
Choice of analyser and sampling system then becomes an important consideration when measuring NH3.


For more information

Telephone us on on +44 (0)1908 227722

Gasmet Technologies (UK) Limited
Woolleys Farm
Welford Road

Gasmet Technologies (UK) Limited is a subsidiary of Gasmet Technologies Oy

Tel: +44 (0)1908 227722
Fax: +44 (0)1908 227733

Privacy Policy
Site Map
© 2019 Copyright

Safe Contractor ISO 9001 Registered