Automatic control of jet grinding on the basis of acoustic monitoring of mill operating zones

Abstract

Purpose. Increasing the jet mill productivity by use of automatic control of the grinding chamber filling level based on the acoustic monitoring results of the jet grinding process. Methodology. Simulation is performed in MATLAB. Acoustic signals of the mill operating zones are used to determine the grinding process parameters. Findings. A simulation model of the automatic jet mill control system is created, which takes into account the inertia of material flows in the grinding chamber and classifier, as well as the main disturbing influences on the process of forming the mill output flow. To analyze the control process, there are three main parts the information component (regulator and technical means of automation), a set of mathematical models that describe the physical processes in the grinding chamber and in the classifier. A study on the automatic control process of the grinding chamber filling is made under the condition of determining the controlled value indirectly through spectral analysis of the acoustic signal in the mill. The insignificant influence of perturbations on the controlled quantity due to very slow filling of the chamber with material in comparison with the period of stream fluctuations at a chamber entrance owing to perturbation action is shown. Originality. For the first time the possibility has been proved of using a relay regulator in control of the grinding chamber filling, determined indirectly through spectral analysis of the acoustic signal in a jet mill. The efficiency of the mill operation at automatic control of the grinding chamber filling according to the relay law is investigated. Practical value. It is shown that with the transition from automated to automatic control of the grinding chamber filling, the mill productivity increases by 1015%. The obtained results are used to build a system of automatic jet mill control.