MCERTS for EMIRAK Emissions System

The EMIRAK emissions system from Signal (UK) has now been MCERTS certified for measuring CO, O2 and NOx including the 75ppm range required for gas turbine power stations and other low NOx concentration processes.

Successful emissions monitoring from gas turbine power generators requires appropriate consideration of their unique characteristics and how they differ from other large combustion processes. When selecting CEMS equipment for gas turbines, it is important to choose a system designed specifically for this application. In particular, the emission limit values (ELVs) for NOx are typically around 60mg/m3 (expressed as NO2 equivalent), which equates to just 30ppm of NO2. Following EA guidance, which specifies that the maximum operating range should be 2.5 times the ELV, a 60mg/m3 ELV would allow a maximum range of 75ppm NOx, considerably below that available on many gas analysers.

In addition, the NO2 fraction of the NOx is much higher when compared to other large combustion processes. This is as a result of the high air dilution in gas turbines, which allows oxidation of NO to NO2 prior to flue exit. There can also be a high level of water vapour, due to the levels of hydrogen in natural gas. With higher levels of NO2 and water vapour, it is important not to allow condensing water vapour in the sample to cause loss of NO2 due to its solubility.

The Signal Ambitech “Emirak” CEM is a heated extractive system utilising a chemiluminescent detector and has been successfully employed in gas turbine power generator applications throughout the world for the past 20 years. Currently over 3000MW of electricity is being generated in the UK by plants using this equipment including a recent installation in Baglan Bay, South Wales, for the advanced 9H gas turbine manufactured by General Electric. The MCERTS certificate containing impressive performance specifications is available to view on the Sira website.