Detection Improvement of Unburned Carbon Content in Fly Ash Flow Using LIBS with a Two-Stage Cyclone Measurement System

Abstract

Fly ash contents can be considered as a basis for optimal and stable boiler combustion control and fly ash quality control in power plants, especially the unburned carbon in fly ash. The real-time and quantitative measurement of the contents in fly ash was studied using a constructed two-stage cyclone measurement system and detected using the laser-induced breakdown spectroscopy (LIBS) technique. The surrounding gas effect, such as the CO2 effect on the unburned carbon content, was studied comprehensively in this paper. The CO2 effect was eliminated using this proposed combination method of a two-stage cyclone measurement system and LIBS with a 1 ns pulse-width laser according to the efficient gas–particle separation and the controlled laser-induced plasma processes of particle flow. The quantitative analysis was improved using the plasma temperature correction method, with the intensity ratio of the emission pair from magnesium as the plasma temperature indicator. The measurement of the unburned carbon content in fly ash with the temperature correction method presented the concordant results analyzed by the chemical analysis method. The feasibility and improved detection ability for the real-time measurement of fly ash contents in power plants are demonstrated.

Atomic spectrometry update – a review of advances in environmental analysis

“…Measurement of unburnt C in fly ash can be a useful indicator of combustion efficiency within coal-fired power plants. A new two-stage cyclone enabled 34 better C measurements by on-line LIBS. Fly ash and CO 2 were separated effectively from a combustion gas stream.…”

Sample Temperature Effect on Steel Measurement Using SP-LIBS and Collinear Long-short DP-LIBS

“…Therefore, a plasma temperature correction method was proposed to improve the quantitative analysis capability of LIBS signal by our group, which was described in the previous work. [34][35][36][37] Theoretical analysis shows that the dependence of emission intensity on plasma temperature can be corrected using the plasma temperature correction factor according to the temperature indicator which is the intensity ratio of different spectral lines from the same element. In the actual process, the plasma from LIBS process is inhomogeneous and complex.…”

An image auxiliary method for laser-induced breakdown spectroscopy analysis of coal particle flow

“…It is necessary to take measures to ensure the repeatability and stability of spectral data. Some researchers committed to reducing the probability of low quality laser breakdown by transforming and optimizing the LIBS experimental system, such as employing a conical tube, 22 dual lens, 23 short laser pulse width, 24 two-stage cyclone measurement system, 25 and other attempts. 26 However, although equipment optimization can improve the stability of measurement to a certain extent, it is still unable to avoid the generation of the invalid spectrum.…”