Evaluation of the MKS On-Line FTIR MultiGas™ Analyzer for Gas Turbine Applications

A side-by-side comparison between the MKS On-Line MultiGas™ analyzer (MGA) and conventional continuous emissions monitoring systems (CEMS) was performed under various test rig operating conditions at Solar Turbines Incorporated (Solar). The CEMS used an array of single gas analyzers (SGA’s) to measure NO_X, CO, CO₂, O₂ and UHC (unburned hydrocarbons). The MGA, which uses Fourier transform infrared (FTIR) spectrometry to make its measurements, simultaneously analyzed the exhaust stream for ten compounds: NO, NO₂, CO, CO₂, H₂O, CH₄, H₂CO (formaldehyde), N₂O, SO₂, and NH₃. Both dry and wet samples were collected using the MGA. The only calibration grade gas required was nitrogen, which was used as a zero (or purge) gas. Overall, the comparison between the CEMS and the MGA was very favorable, with the NO emissions within 0.1 ppmV (∼5%) and CO₂ emissions within about 6% of each other. Larger differences were observed for NO₂ and CO, but were most likely caused by sensor sensitivity range and sample handling problems with the in-house conventional CEMS.