Xia Wencheng

Experimental study on improving the separation performance of liquid-solid fluidized bed using flotation reagent and newly designed aeration unit

ABSTRACT In the study, a pilot-scale liquid-solid fluidized bed (LSFB) apparatus was modified by adding an aeration unit, which enabled us to test the effect of air addition on LSFB separation performance for fine coal (0.25 ~ 1.00 mm). Upward water flow velocity, aeration volume and flotation reagent (Kerosene and 2-Caprylic alcohol) dosage varied throughout the experiment. The optimum results from the three experimental conditions (without aeration, with aeration only, with aeration and reagent) were compared by their respective probable error (Ep) values. The Ep values of the three experimental conditions were 0.109, 0.08 and 0.07, respectively. The results indicated that the addition of air obviously enhanced LSFB performance, while the addition of flotation reagent further improved the separation result.

Fast Predicting the Washability of Coal Using Digital Image Processing Method

Based on the demand of real-time control and digital coal preparation, a pure new MATLAB-based image recognition system was developed to compute the coal particle density distribution through the digital image processing method, 13 of 29 image feature parameters was selected to be most representative image characteristic parameters through the analysis of statistics and graphs. Take the above parameters as the input of RBF neural network, the density level of coal particles could be estimated, combined with the cross-sectional area of coal particles and the ash content of each density level, the washability curve could be drawed. Experement show, the absolute error of the total ash is 0.545%, which meets the China standards of coal preparation(GB/T477-1998); the related coefficients of each indicator in both actual and predicted float-and-sink material are all close to 1, while the curves of λ, β, θ and δ are very similar and the deviation of ξ curve is relatively large.