Effects of Laser Wavelength on Properties of Coal LIBS Spectrum
QIAN Yan1, ZHONG Sha2, HE Yong1*, Ronald Whiddon1, WANG Zhi-hua1, CEN Ke-fa1
1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
2. Jiangsu Power Design Institute, Co. Ltd. of China Energy Engineering Group, Nanjing 211200, China
Abstract：In face of the complicated and changeable coal in Chinese power stations, the on-line measurement of coal elemental composition is extremely significant in terms of enhancing the safety and efficiency of boilers as well as lowering the waste emission during operation. In this work, laser induced breakdown spectroscopy (LIBS) was applied to coal quality measurement. Laser wavelength was changed as 355，532 and 1 064 nm to investigate the influence on coal LIBS features, including plasma time evolution and the spectral lines intensity-time characteristics of different elements. Energy threshold for shielding effect was also tested to verify how it varies with laser wavelengths. Additionally, coal LIBS spectrum was analyzed under different laser wavelengths. It has been proven by experiments that higher intensity of coal LIBS spectrum and energy threshold can be easily achieved when using laser of 532 nm, making it a fantastic energy source for coal LIBS tests. Results of these experiments serve to guide the industrial application of LIBS technology in the field of coal quality measurement.
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