DESIGN OF A FLUE-GAS PROBE FOR AMMONIA MEASUREMENT

The emission of nitrogen oxides from combustion can be limited by sele ctive catalytic reduction (SCR) and selective non-catalytic reduction (SNR) by ammonia. In order to control the ammonia slip in these proces ses it is desirable to measure the ammonia outlet concentration contin uously. The problems in doing this are discussed, among which are homo geneous and heterogeneous reactions of ammonia with nitric oxide in th e sampling system. The design and test of a diluting flue gas probe is presented, where ammonia is converted to and detected as nitric oxide . The efficiency of various converter designs for the probe was studie d in the laboratory.