Experimental Research On Separation And Upgrading Of Lignite In The Pulsating Fluidized Bed

Energy shortage has become a global problem. Lignte resources account for 1/8 of the total coal reserves in China. Along with the continuous development and utilization of high quality coal resources, how efficient use of lignite become a topic worthy of further research. In this paper, the pulsating flow is introducted into the gas-solid fluidized bed, which can significantly inhibit the bubble formation and growth, reduce channeling and short circuits. The quality of fluidization can be modified, and the fine coal can be separated efficiently in the pulsed fluidized bed.This dissertation mainly focuses on the influence of various operating factors on drying characteristics of fine lignte in plused fluidized bed and establish the drying model under different inlet temperatures, which is the most suitable description in plused fluidized bed. This paper also study the influence of various operating factors on lignte separation under cold and thermal condition, then determine the optimum operating condition using orthogonal test.In the process of drying lignite in the pulsating fluidized bed, the drying rate was influenced greatly by the inlet temperature, gas velocity and pulse frequency, but it was less affected by the bed height. The increase of inlet temperature, gas velocity and pulsation frequency reduced the moisture content and increased the drying rate. There had no basically effect on the lignite drying when the gas velocity and the pulse frequency exceeded a certain range. The fitting results under different temperature combined with thin layer drying model showed that the Logarithmic model was the best suited for describing lignte drying.The separating experiments were conducted in the plused fluidized bed with different operating conditions using fine coal with-6+3mm and-3+1mm size fraction. The ash segregation standard deviation was used as an index to evaluate the effects of factors. Based on the determination of optimal range of each factor owing to the single factor experiment, the Box-Behnken response surface method was used to study the interactions between factors and determined the optimal separation conditions of-6+3 mm and-3+1 mm fine coal respectively. The separation indicated the separation effect of lignite under the thermal condition was better than that of the cold state. and the probable error E values of-6+3 mm and-3+1 mm fine coal separated in an intermittent separation system using a pulsed fluidized bed were 0.12~0.16 and 0.10~0.16, respectively.