Measurements of ammonia slip with a Laser Stark spectrometer at VKR Power Station 'Shamrock'

A newly developed infrared Laser Stark Spectrometer has been validated with wet chemical methods at a coal-fired power station. The automated instrument was positioned behind a DeNOx- reactor to measure ammonia slip in low dust conditions. Agreement between chemical data and spectroscopic results is obtained if it is assumed that part of the ammonia is bound to water in the form of molecular NH4OH. The equilibrium constant of NH3+H2O≤≥NH4OH has been determined at 100 and 300 deg C. The influence of the flow rate of the flue gas through the sampling system on the measured concentration has been investigated. The dynamic response of the reactor for a stepwise enhancement of the NH3 injection has been measured. Simultaneous monitoring of NH3 and NO concentrations at 8 different positions along a path across the reactor leads to the conclusion that NH3 slip cannot always be inferred from NO values. Filtering experiments in a high dust environment are presented as a supplement. (author). 10 refs.; 26 figs.; 2 tabs