Absolute diode laser-based in situ detection of HCl in gasification processes

The release of HCl is an important parameter for industrial combustion and gasification processes, which must be determined in the ppm range for active process control and optimization. Based on a low power vertical-cavity surface-emitting laser (VCSEL) at 1.74 mu m, we developed a new tuneable diode laser absorption spectrometer for calibration-free, absolute in situ HCl detection using the (HCl)-Cl-35 (2 a dagger 0) R(3) absorption line with minimized cross-sensitivity to CO2 and H2O. The spectrometer was applied to in situ measurements in a gasification process (T = 1,130A degrees C, P = 1 atm, L = 28 cm) and yielded an optical resolution of 2.3 center dot 10(-4), i.e. a HCl sensitivity of 45 ppm (13 ppm center dot m).