Guest Lecture: Online laser monitoring of metal chloride and oxygen concentration using collinear photofragmentation and atomic absorption spectroscopy

September 21, 2018 @ 3:10 pm
200 College St
Toronto, ON M5T 3A1
Nikolai DeMartini

Jan Viljanen
PhD Candidate in Applied Optics
Tampere University of Technology, Finland

Collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) is a recently developed optical method for analysing molecular concentrations and their kinetics. [1,2] The technique is based on the fragmentation of a precursor molecule and the detection of the fragment atoms via absorption spectroscopy on a common laser beam path. It has been applied to monitor concentrations of the precursors KCl and KOH in thermal conversion applications. CPFAAS studies have focused on precursor molecule concentration analysis using the maximum absorbance right after the photofragmentation. Sample lengths ranging from 1 cm to 10 m have been demonstrated in the studies [2,3]. In this work, an overview and recent development of CPFAAS is presented.

Typical CPFAAS measurement arrangement is shown in Fig 1. CPFAAS technique has been demonstrated for online monitoring of KCl, KOH, and O2 in a single particle reactor [2,3] and for KCl and PbCl2 in full-scale power plant. Typical molecular detection limits reach sub-ppm levels. The spatial resolution of the measurement can be adjusted by tuning the overlapping of the fragmenting and probing laser beams. This allows collection of localized information that is often required to support modelling work of flames and combustion processes. Online measurement of PbCl2 is a powerful demonstration of the CPFAAS technique’s ability to be applied also to monitoring of more complex molecules, such as ZnCl2, that are present in combustion processes. In addition, recent development in laser sources has brought NaCl and NaOH monitoring closer to realization.


Jan Viljanen is finalizing his PhD in the Applied Optics research group at Tampere University of Technology, Finland. Jan has previously worked with Professor Nikolai DeMartini on the application of the techniques discussed in this talk to the release of K compounds in burning biomass particles. If you would like to meet with Jan individually, he will be available from 1 – 2:30 pm on Friday, September 21st. Please contact Professor DeMartini for details.


To download the lecture abstract, click HERE