China Nonferrous Metallurgy

Given the current lack of a mature system and conclusions regarding the pneumatic conveying of wet granular materials in dense phase, this paper explores the flow mechanisms and flow patterns of wet granular dense phase pneumatic conveying, providing theoretical support for the optimization design of pneumatic conveying systems. The study employs a bidirectional coupling numerical simulation method using computational fluid dynamics (CFD) and discrete element method (DEM) to analyze the motion forms of dry and wet granular plugs in horizontal pipelines and the trajectories of particle movement. It further investigates the impact of moisture content on the conveying flow pattern, conveying efficiency, and pressure drop during conveying.The results indicate that under the same gas velocity, wet particles can form plug flow, while dry particles initially exhibit plug flow, which then evolves into dune flow as the plug is penetrated by the gas, ultimately becoming bottom flow. As the gas velocity increases, the pressure drop per unit length of the horizontal pipeline shows a trend of first decreasing and then increasing.Under the condition of mass flow rate of 0.5kg/s and water content of 5%, the pipeline pressure drop is the lowest when the conveying speed is 9m/s, which is the best economic speed value.The pressure curve of wet particles remains in a highly fluctuating unstable state; when two monitoring points are located outside the plug, the axial pressure difference is nearly zero, while when the monitoring points are inside the plug, the axial pressure difference can reach -600Pa. By analyzing and monitoring the pressure drop changes during the conveying of wet particles, signs of equipment failure can be detected in a timely manner, allowing for early warnings of potential issues and the implementation of preventive measures to avoid equipment damage and production interruptions.