Study On Dynamic Characteristics And Heat And Mass Transfer Of Lignite Drying Process

Lignite is a low metamorphic grade coal, with high water content, high volatile, lowcalorific value and low ash melting point, especially high moisture content not onlyseverely reduces the calorific value of lignite but also increases transportation costs.Practice shows that different drying devices determine different processes, it is urgent todevelop efficient lignite drying device and process systems which are the core technology.The study of them has important academic value and engineering significance.Test selection SZ-200t/h Vibration Francis drying system as the research object, thispaper conducted research and qualitative characteristics of heat and mass transfer kineticsof lignite. First, using test method for drying lignite characteristics under differentconditions studied, the results showed that: with the increase of the temperature of thedrying medium, lignite particle size became lower, the drying effect became better.Secondly, establishing a physical and mathematical model of lignite particles, by usingFLUENT software its numerical simulation, the change in the temperature field and theconvective heat transfer coefficient under different conditions. Analyses showed that: thegreater the wind velocity, the smaller lignite particle size and higher when the inlet airtemperature, the bigger convective heat transfer coefficient, the higher the rate of drying.Finally, a lignite particle heat and mass transfer mathematical equations were established.Through numerical calculations MATLAB, different operating conditions and lignitedrying curve temperature curve were collected, with numerical and experimental resultswithin the error range of8.6%. This further testified the heat and mass transfer equationwas more reasonable, in line with the heat and mass migration of lignite particles inside.Studies have shown that, SZ-200t/h vibration Francis drying systems can meet thedifferent particle size and moisture lignite drying of the indicator, based on the simulationresults obtained by fitting the gas-solid heat transfer correlation, can provide theoreticalguidance to optimizing the design and engineering practice drying apparatus.