Numerical Simulation For Tubular Airflow Drying Of Lignite And Structure Optimization

Lignitic coal，a kind of bituminous coal，accounts for a large proportion of coal resources inthe word，and there is abundant of it in china. Because of the high humidity ratios，thermalefficiency of lignitic coal is very low when it is used directly for combustion and cost too muchin transportation，these greatly limited the mining of lignitic coal. The study focuses ondeveloping efficient Lignite drying technology and equipments, so as to greatly improve theefficiency of the Lignite drying.Airflow drying is one of the mainstream drying methods in recent years, it specially fits forthe powder materials, equipment needed is simple and do well in particles drying. In this study,the Tubular airflow dryer was selected for the equipment to dry the lignite; drying process wassimulated on the basis of experiment. Firstly, introduced theoretical knowledge of thehydrodynamics and computational program that numerical simulation required, and discussedthe choices of turbulence model; successfully completed using the Euler model in calculating themovement of a large number of particles in pipeline, then analyzed gas-solid flow fields and thedifferent drying results that led by various factors. Calculation results agreed well withexperiment results, it shows that the model has good accuracy and predictive capability and ismore vivid in demonstrating the flows and heat transfer of the gas-solid flow. Relying on allthose conclusions, proposed four new drying tubes that are different in structure, analyzedgas-solid flow fields in them, explored their heat transfer efficiency and the advantages anddisadvantages in the drying process. Conducted a preliminary exploration in improving thestructure of the dryer in the premise of achievable，it provides a theoretical basis for optimaldesign of the tube-type Gas flow dryer in industry.