Integrated Measurement For Density And Viscosity Of Heavy Medium Suspension Based On Differential Pressure

In coal preparation process, density and viscosity are two of the most important parameters of heavy medium suspension which need to be accurately measured. Currently, the isotope densimeter was commonly used to detect the density of heavy medium suspension, but the radioactivity is harmful to people. Furthermore, there is a lack of on-line device to detect the viscosity of heavy medium suspension till now. Most coal preparation plants use a magnetic material content detecting device to measure the magnetic powder content of the suspension firstly, then compute the coal-content of suspension combined with the density detected by isotope densimeter, and take the coal-content as an indicator of suspension viscosity. However, the measurement error of this method is large.This paper presents an integrated measurement method for density and viscosity of heavy medium suspension based on differential pressure, which achieves density measurement without radioactivity and on-line measurement of viscosity. That method installs a differential pressure sensor on a byroad which is beside the vertical main loop pipeline of heavy medium suspension. When suspension is stability flow in the byroad, the density could be measured according to the output of sensor. While closing the valves of the byroad, heavy medium suspension will start to settle, the viscosity of suspension would be obtained through the settling process.The purpose of this study is to verify the measurement method presented above through a series of experiments, and to establish the measurement model which measuring viscosity from settling curves. The experiments include two parts. One part is the settling experiments of heavy medium suspension. Through a differential pressure device, 34 groups of settling curves were obtained. The other part is the calibration experiments of suspension's viscosity employing a viscometer called SV10 and a stirrer named RW20.The measurement error of density in laboratory is±0.0083g/cm3, and±0.0037 g/cm3 in industry plant due to the smaller range and bigger diaphragm area of sensors. About to viscosity, this paper provides two different ways to establish the measurement model. In the first way on support vector machine, the"SVR model"which extracts features using experience and the"KPCA+SVR model"which extracts features using kernel principle component analysis were obtained. In the other way on kernel partial least squares, the"KPLS model"was build. The measurement errors of these three models are±0.183mPa·s,±0.133mPa·s and±0.129mPa·s respectively. Using the same methods, the coal-content measurement model was established and the measuring errors are 3.6%, 2.5% and 4.0% respectively.The industrial prototype which designed according to the method proposed by this paper has been running in the coal preparation plant. The results show that the integrated measurement for density and viscosity of heavy medium suspension based on differential pressure can be applied in coal preparation industry.