Dynamic Properties of a Radiometric Monitoring System

On-line radiometric monitors (nuclear meters) have been in use in the industry for many years. They have been utilised for coal quality monitoring, in the control systems for coal blending, or for separating coals in the heavy media separation process. Their operation is based on the scattering or the 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 a monitor of the density of water/coal mixture have been presented and discussed. The analysis of monitors with constant time of measurement shows that it is possible to determine the optimal time for which the dynamic error is the smallest. The analysis also shows that the monitors in which the time of measurement is variable and adapts to changes of the input signal give better result. A fuzzy logic decision table has been applied to control the time of measurement according to variations of the input signal. The simulation of the system operation has been performed with the use of the Matlab (Simulink) program package. Key-Words: nuclear meter dynamics, stochastic signal, stochastic signal filtration, adaptive monitor.