Numerical Simulation Of Dense Phase Plug Flow Pneumatic Conveying

Pneumatic conveying is a mode of transport using airflow in the pipeline for conveying materials. Earlier pneumatic conveying was majorly the dilute phase pneumatic conveying.However, due to its shortcomings, dilute phase pneumatic conveying is being replaced by dense-phase pneumatic conveying. The system of pneumatic conveying mainly consists of gas source device, feeding device, conveying device, material-gas separation device and control device. The system has been widely used in many industries.In this paper, the significance and contents of the research are put forward based on the research progress and present situations both at home and abroad. Previous study on dense-phase pneumatic conveying was mainly concentrated in experiments and designs with less theoretical research. And the research of material plug was usually conducted by using the CFD software FLUENT, however, could not reveal the mechanism of material flow from the perspective of particle size. This paper introduces the discrete element software EDEM and carries out the simulation analysis of dense phase plug flow pneumatic conveying based on coupling EDEM-FLUENT platform, which can solve the conveying problems from the perspective of particles.The EDEM software and EDEM-FLUENT coupling method have been analyzed and the results are as follows. Based on the dense-phase pneumatic conveying simulation in vertical pipe using EDEM-FLUENT coupling method,we found the flow form of material plug and the influence of the inlet gas velocity on material plug movement speed. And will also show the influence on the pressure drop determined by factors like gas velocity, particle mass flow rate as well as the diameter of the pipe.We will also analyze the conveying in horizontal pipeline, achieving the ways in which material plugs of different flow patterns are formed and conveyed. In addition, we will also adopt a method to determine the flow pattern by pressure changes. We will attach greater importance to the analysis of material plug flow mechanism and reveal this mechanism respectively from the angles of the straight tube observation, the logic of speed changes of Gas-solid two phase in certain cross-section of the pipe, and the contact force analysis of particle、flow and pipe.On the basis of the above conclusions, the pipeline with horizontal, bent and vertical forms combined. Analyzed how the materials move in such pipeline under certain conditions.And determine which initial conditions can make the material plug for continuous dense phase conveying in the whole pipe. Analyzed the phenomenon of blocking pipe and put forward solutions.Finally, the BP neural network will be introduced to the dense phase pneumatic conveying system and used as a research method to predict the pressure drop in the conveying. The error between the predicted result and simulation result is small which indicates applying neural network to the pressure drop prediction can get better effect.