Simulation study of NH<sub>3</sub> concentration measurement based on QCL-TDLAS

Abstract

As a new gas concentration measurement technology, tunable diode laser absorption spectroscopy (TDLAS) is widely used in the field of NH3 concentration measurement. Using Matlab visual modeling and simulation software Simulink to realize the direct absorption measurement process simulation of NH3 concentration TDLAS with mid-and-far infrared quantum cascade laser (QCL) and near-infrared distributed feedback laser (DFB) as light source, under the environmental parameters of flue gas denitration and normal temperature and pressure respectively, the sensitivity, detection limit and resolution of NH3 concentration measurement were theoretically analyzed. The results show that theoretical sensitivity of the QCL-TDLAS system is about 50 times higher, compared with the traditional near-infrared DFB source. The detection limit and resolution can reach the ppb level, and the trace NH3 concentration measurement capability is greatly improved. The simulation process and results provide theoretical basis for QCL-TDLAS technology in NH3 concentration measurement.