Experiment And Numerical Simulating On Characteristics Of Mixing Movement For Particles Of Oil Shale In Rotating Retorting

Oil Shale is a kind of fossil energy. The mean residence time (MRT) and mixing (M) of oil shale in rotary retorting is the key parameters, which affect the production of retorting gas and the optimization of operation and structure parameters on rotary retorting directly. Research work is built on self-designed laboratory-scale cool simulator rotary retorting. The experiment and theory research studies the motion & mixing characteristics (MRT & M) in rotary retorting.The research studies residence time distribution of oil shale particle in rotary retorting with changing operating parameters and structure parameters. Experimental results show that the MRT reduced with an increase in the degree of filling, the angle and the speed of rotary retorting, and the MRT of Spur lifting flight little. Through statistical analysis of the residence time, the residence time distribution of oil shale particle in rotary retorting do not reject normality after reduce the straggler residence time.The experiment studies exit and mixing degree of axial direction of oil shale particle and solid heat carrier in rotary retorting with changing operating parameters and structure parameters. The mixing degree optimized by using right-angled flights forms at 20% vessel filling percentage and 3.24°dip angle with 13.3rpm rotation speed during statistic analysis, then the mixing degree of rotary retorting was at best mixed results. Orthogonal test direct analysis was used to analyze the test data, which identified the optimal conditions (right angle,100mm,4.33°,7.7r/min) of the rotary retorting axial extent of mixing of oil shale and solid heat carrier, in accordance with the impact of mixing the mixed factors were the lifting flight types, the vessel filling percentage, the angle, the rotational speed of rotary retorting and the outlet baffle.The research studies the impact of the vessel filling percentage, rotational speed and other operating parameters on particle motion model through observed the mixed progress of different density distribution oil shale particle in rotary retorting, at the same time, researches mixed mechanism of particles. When the filling degree is less then 33%, right-angled flights and straight flights dominated by the convective mixing into shear mixing effects enhance and the integral effect of mixed reduced with the reduce on the speed of rotary retorting; when the filling degree is 50%, right-angled flights is better than straight flights with the reduce on the speed of rotary retorting.The research simulates the mixing of particles in rotary retorting by use of discrete element method (DEM), the impact of flights forms, vessel filling percentage and rotational speed on two kinds of particles in rotary retorting are studied. Experimental results show that radial mixing is poor when rotary retorting without flights installed, the moon pattern appears in which the small particles concentrate in a central core and the large particles distribute in the periphery, there is dead region with inferior mixing. The flights destroyed segregation in "lifting and castrating" particles periodically which causes the segregation of particles with flights installed. The flights form and the rotational speed of rotary retorting have influences on particle mixing inordinately, which is closely related to filling degree, when the filling degree is 16.7%, the mixing is optimum in rotary retorting containing right-angled flights with the same speed, the rotational speed has little effect on mixing quality, when the filling degree is 33.3%, the mixing is optimum in rotary retorting containing 120°angled flights with the rotational speed is lOr/min. There have large influences on particle mixing between different particle diameters in axial mixing, the axial movement of large particles is faster than small particles.The forecast to the mean residence time and extent of mixing is useful to the forecasting of the distillation effect of oil shale particle and solid heat carrier in rotary retorting. In order to improve the accuracy of predicting performance for the mean residence time and extent of mixing, a support vector machine (SVM) model is employed, and parameters of the SVM model optimized by grid regression and best parameters were obtained. The compositions of the operation and structure parameters were employed as inputs, and the mean residence time and extent of mixing was used as outputs of the SVM model. The model was verified with the experiment datum, result of prediction by the optimized SVM model was compared with the test datum, and the result show the SVM model has achieved good predicting performance for both the mean residence time and extent of mixing.