Simulation of dynamic properties of nuclear meters applied in coal preparation control systems

Online nuclear meters have been in use in the coal industry for many years. They have been utilized for coal quality monitoring, in control systems for coal blending or for treating coal in the heavy media separation process. Their operation is based on the scattering or absorption of incident gamma radiation, and the derived density or ash value is the result of a time-averaged measurement. In this paper, dynamic models of ash monitors are presented and discussed. The analysis of monitors with constant time of measurement shows that it is possible to determine optimal time for which the dynamic error is the smallest. The analysis also shows that the best results are given by the monitors in which the time of measurement is variable and adapts to changes of the input signal. An example of a coal blending control system which stabilizes coal quality of the blend is presented. The simulation of the system operation was performed with the use of the Matlab (Simulink) program package