Laser-based, optical, and traditional diagnostics of no and temperature in 400 kw pilot-scale furnace

Abstract

A fast sensor for simultaneous high temperature (above 800 K) diagnostics of nitrogen oxide (NO) concentration and gas temperature (T) based on the spectral fitting of low-resolution NO UV absorption near 226 nm was applied in pilot-scale LKAB’s Experimental Combustion Furnace (ECF). The experiments were performed in plasma and/or fuel preheated air at temperatures up to 1550 K, which is about 200 K higher than the maximal temperature used for the validation of the developed UV NO sensor previously. The UV absorption NO and T measurements are compared with NO probe and temperature measurements via suction pyrometry and tuneable diode laser absorption (TDL) using H2 O transitions at 1398 nm, respectively. The agreement between the NO UV and NO probe measurements was better than 15%. There is also a good agreement between the temperatures obtained using laser-based, optical, and suction pyrometer measurements. Comparison of the TDL H2 O measurements with the calculated H2 O concentrations demonstrated an excellent agreement and confirms the accuracy of TDL H2 O measurements (better than 10%). The ability of the optical and laser techniques to resolve various variations in the process parameters is demonstrated.