Research Of The Mill Noise Detection Device For Identification Of The Mill Load

The mill is the core part of cement milling system. At present, in most of our cementplants, the control of the mill is based on the experience of the operator manual control, cannot make the mill run in a stable, efficient state and the power consumption of mill is high,thus the production and operation uneconomical. One of the main reasons for this situation isthe ball mill load testing has not been resolved.In this paper, the development of the cement mill load testing is analyzed, the methods ofnoise detection, the mill current detection, the pressure difference detection and shaftvibration spectrum are compared, and these methods were analyzed and summarized. Aimingat the specific technological characteristics of the cement mill, the noise law is used andcombined with the popular embedded digital signal processing chip (DSP) to design the newgrinding sound detection device, which has a practical value-oriented identification of the millload, providing reliable data for the mill optimization control.The signal spectrum of mill noise can reflect the conditions of mill workers accurately,but through on-site research to know the mill internal and environmental impact whichdetermines the mill noise signal can not be pure, it contains a large number of interferingsignals. By spectrum analysis of mill noise signal and related literature inspection, thespectrum of the effective mill noise signal mainly distributed in the500~2500Hz band.Aiming at the spectrum characteristics of and the interference signal, the FIR digitalfilter designed by frequency of cover method (FRM) is used to process mill noise. Digitalsignal processing, computing capacity, the filter detection process on the host computerprocessing, is bound to increase the burden on the host computer, and the site of the signalacquisition and computing power of the DCS control system is not strong, reach the grindingsound detect the minimum requirements, in order to better digital signal, sampling andfiltering, this paper adopts special chip of DSP chips as a grinding sound signal detection,DSP chip is designed specifically for digital signal processing microprocessors, computingspeed, high-speed I/O interface and dedicated multiplier hardware.In this paper, the TI’s TMS320VC5502DSP chip is taken as the core to set up thehardware system of the mill noise detection devices, which includes the audio interface circuit of the device using TLV320AIC23B chip, the power supply circuit of the device designed bythe TPS73HD301chip, the reset circuit with a power-on reset, manual reset and automaticreset function using MAX706R chip, the clock circuit of the device, and the simulationinterface circuit in order to achieve device-circuit debugging features of the program.On the basis of the completion for the hardware design of the device, the software of millnoise detection device is designed by the CCS v3.1system software. And the software of millnoise detection device includes the associated register program (DMA, McBSP, I2C),system initialization procedure and the mill noise signal filtering procedures.At the end of the paper, the site of the mill noise signal is collected and processed by thedesign device, and the results are accordance with the MATLAB simulation experiments. Andthe hardware and software designations have been verified, realizing the acquisition andfiltering functions of the mill noise detection device. The effect is satisfactory, and has goodpractical value and application prospect.