A large depth of field LIBS measuring system for elemental analysis of moving samples of raw coal

• An optical system for LIBS analysis with a large depth of field has been developed.
• A device that reproduces the behavior of raw coal on a conveyor belt has been developed.
• LIBS coal measurements are in good agreement with standard ASTM analysis.
• The measuring system is suitable for application in power plants.

We present preliminary results of laboratory tests carried out on moving samples of coal by means of an innovative LIBS system with a large depth of field. The measuring system has been conceived to operate on line in a coal fired power plant. To duplicate at laboratory level the real situation, the coal samples are sequentially positioned under the measuring head by means of a translation/rotation unit that allows reproducing the behavior of the raw coal transported by a conveyor belt. Experimental results show that both carbon and hydrogen concentration as well as the content of some inorganic components (Al, Ca, Fe, Si) can be evaluated with good accuracy.