Numerical simulation of lignite drying in a packed moving bed dryer

A numerical model was developed for the lignite drying process in a packed moving bed dryer based on governing equations and the lumped drying rate correlation of a single lignite particle. The lumped drying rate correlation incorporated into the packed state drying model was evaluated by comparing both experimental and calculated results for the convective drying of a single particle. The drying model for the packed fixed bed was established and verified by two kinds of lignite particle experiments and then used to examine the lumped drying rate correlation and heat transfer correlation incorporated into the packed state drying model. The simulations closely matched the experimental results for the average weight loss rate and gas temperature. The developed models can be used to predict the drying process in a packed moving bed. The lignite drying behavior in the packed moving bed was simulated and the effects of the operating parameters on the drying process were analyzed with the developed numerical model. The parameters included drying gas velocity, lignite particle size, lignite particle moving velocity and lignite particle stack height.

► The developed model can predict the drying process in packed moving bed. ► Moisture contents of two Chinese lignite were efficiently reduced to about 11%. ► Low-temperature corrosion was improved with reuse of flue gas.