Research And Application On Drying Lignite Upgrading Technology

Lignite with low water content,degree of coalification,high volatile content and low calorific value of lignite,accounting for 13% of coal reserves in China,how to efficient utilization of lignite has important significance for the development of national economy in china.At present,drying lignite quality technology is one of the key methods to improve the utilization efficiency of lignite.Firstly,the drying dynamics characteristics of Yimin lignite were studied,and the k value of drying rate characteristic constant was obtained by introducing particle size distribution coefficient,which was similar to the mean value of drying rate characteristic constant k of different particle size.According to the drying rate and existing form of moisture of lignite,the lignite drying process is divided into three stages of drying,analyzed its drying equation model with linear drying model,Wang model and Page model is more reasonable.The relationship between lnk and 1/T was established according to Arrhenius empirical formula,and the evaporation activation energy Ea=17.088 k J/mol of lignite and the pre factor A=12.47min^-1 was obtained.Secondly,Secondly,the drying test of 35t/h industrialized vibration mixed flow bed flue gas,1.2t/h semi industrial steam tube and 0.5t/h semi industrial steam tube rotary were carried out.Set up the processing ability of the 0.5t/h steam tube rotary drying test-bed,supporting dust removal and gas water recycling design.According to the test results,whether flue gas drying or steam drying,lignite drying process is mainly physical dehydration,lignite moisture can be dried to 20%²5%,that is the water can be changed from high to medium high,the calorific grade changed from low to medium.Dry lignite may appear spontaneous combustion in storage,it is necessary to attach great importance to the actual operation.Dry lignite basically no relapse occurs in the short term,the water is more stable.Considering the rate of powder,drying system thermal efficiency,environmental protection and so on,steam tube rotary dryer is slightly better than that of the steam pipe type drying device,the both are better than that of vibration mixed bed flue gas drying device.The control of oxygen content in dryer and dust catcher is the key to safe operation,needing more focus on monitoring.By reducing the temperature of exhausted gas,it can recover the moisture in coal,and the index of recovering water is better,after physical settlement,it can be directly used as water for desulfurization system.