Study On Flow Patterns And Solid-Mass Flow-Rate Prediction In Dense-Phase Pneumatic Conveying Of Pulverized Coal

Based on the application of the flow gasification technology of pulverized coal,the conveying experiments of several kinds of industrial coals under different operation conditions were carried in a self-built pneumatic conveying facility in laboratory with a pipe diameter of 50mm.In this research,the flow pattern of the pulverized coal was investigated by ECT system when running through the vertical pipe.Meanwhile,the pressure along the venturi was obtained and applied to the real-time online prediction of solid flow rate.The flow patterns in the vertical pipe were divided,and then the detailed flow patterns were defined.After that,the differences of signal characteristics and the quasi-number characteristics of different flow patterns were analyzed according to the comparative studies of the signal characteristics,the system transport range and the cross-section between different flow patterns.To interpret the such differences of flow patterns,the transformation of the flow patterns together with stability of those were understood from the interaction bet,ween gas and coal point of view.In this paper,conveying experiments of two kinds of industrial coal-Jincheng coal and Yangchangwan coal were carried out.Overall,the research can be organized as two parts.In the first part,the physical properties of the two kinds of pulverized coal were measured firstly,and then the two-dimensional ECT diagrams of flow pattern were compared.Afterward,such differences between the two kinds of pulverized coal were explained by means of the mechanical properties(shear characteristics)of the pulverized coal and the theory of the gas-solid interaction.Finally,comparison of the transportation stability of the two kinds of pulverized coal were performed from the two-dimensional ECT flow pattern diagrams,were combined to compare the difference of.With respect to the second part,different ECT flow patterns were obtained by changing the flow rate and proportion of the three-way gas.The relationship between flow patterns and operating conditions was investigated by comparing,the relationship between the flow patterns and operation conditions were observed by comparing the flow patterns and stability,and the reasons for different flow patterns under different operating conditions were explained.Based on the flow characteristics of gas-coal mixtures along the venture,the flow rate of pulverized coal was determined by the diferential pressure-flow algorithm,and thus could be used to predict the real-time flow rate.To demonstrate efficiency and accuracy of the proposed method in this work,the predicted results were compared to those measured by other industrial methods(i.e.,powder mass flowmeter,weighting module,ECT)and the differences between the fitting coefficients of flow rates of different experimental devices were qualitatively analyzed.