Model established and simulation of lignite drying system based on flue gas recirculation

To improve efficiency of lignite drying system and recovery of dry exhaust moisture and heat,a lignite drying system based on flue gas recirculation technology was proposed,and the mathematical model was established by MATLAB. The energy saving,security and water recovery efficiency of the system were simulated and analyzed. The results showed that the system was low temperature drying,which used flue gas as drying medium,the oxygen content and moisture of drying medium reduced significantly,the process was more reliable and effective. The heat transfer and mass transfer intensity and thermal efficiency of the system were improved. Compared to the traditional coal drying systems which used flue gas and air mixture as drying medium,the coal consumption of the system reduced to 39. 60 kg / t by7. 62%,thermal efficiency and exergy efficiency was 4. 31% and 3. 01% respectively,recycling water flow was 1. 73 t / h and no new pollutants generated,the system was more environmentally friendly. The moisture content of the drying medium reduced by 37. 21 g / kg and the dry intense was enhanced,which shortened drying time. The oxygen concentration reduced by 7. 84%,which solved the security problem of lignite drying system.