Satyanarayanan S

The present study reports developing a bench-top Laser-Induced Breakdown Spectroscopy (LIBS) set up for the online analysis of powder samples without sample preparation. The powder particle blow-off during pulsed laser ablation was mitigated by adding a blow gas (an inert gas blown across the ablation surface) and a suction unit (for extraction of the blow gas and blown-off particle cloud) to the existing LIBS setup. The influence of a blow-gas combined with a suction unit on LIBS emission intensity from coal powder and flyash particles is studied in the present work. The effect of the blow gas flow rate and the suction pressure was studied on the LI-BS emission intensity and removal of the laser blown-off particle cloud. The combination gas flow at 2 lpm (liter per minute) flow rate and suction at 925 mbar (absolute) show an increase in the LIBS emission intensity and effective particle removal. The ratio of LIBS emission intensity of the powder sample and solid-target (pellet) sample improved from 0.25 without the Ar gas flow and the suction unit to 0.85, which is by a factor of 3.4 times with the proposed approach.

Laser-Induced Breakdown Spectroscopy (LIBS) technique is used to determine the emission intensity of inorganic elements, such as Si, Fe, Mg, Al, Ca, Na, and K in coal samples. The average emission intensity of the inorganic elements increases with the ash content of the coal sample with R2 = 0.82. Using the LIBS data, partial least square regression (PLSR)-based multivariate analysis was performed to determine the coal ash content. The PLS approach combined with the LIBS technique resulted in the coefficient of correlation R2 = 0.93, root-mean-square error RMSE = 3.5%, standard deviation SD = 11.7% and resolution = 3.7% corresponding to the reference ash data.