Optimization of a Teetered-Bed Separator Using Pulsed Water

Abstract

ABSTRACTThe teetered-bed separator (TBS) is widely used for coal particles with a size range of 2.0 mm to 0.25 mm separation based on hindered settling principles. However, a problem with teetered-bed units is the limited range of particle size in which an acceptable separation performance is achieved. To explore the probability of an extend size range of TBS, a pulsed-water supply with different frequencies and amplitudes was introduced to the traditional TBS in this study. The separation performance of 2 mm to 1 mm coarse fraction and 1 mm to 0.25 mm fine fraction were systematically compared with and without pulsed water, respectively. The results show that, for the 2 mm to 1 mm coarse fraction, little additional benefit was gained when pulsed water was used to supply the fluidization water to a traditional TBS. However, for a fine fraction of 1 mm to 0.25 mm, an optimal separation index—89.18% combustible recovery with 11.58% ash content and 468.41 efficiency index—was obtained when the frequency and amplitude were 1 Hz and 40 dm3/h, respectively. The efficiency index under the pulsed-water condition increased by 80.45, compared with that of constant upward water. It indicates that the bed was completely loosened through the forced oscillation and constant friction collision among the particles in the bed under the interaction of pulsed and continuous flow. The fine mud mechanical entrainment phenomenon in traditional TBS was avoided. Therefore, pulsed water can reduce the lower particle-size limit, which means that the upper limit size of the flotation feeding decreases. The amount of materials entered into flotation process also decreases, reducing the cost of actual industrial production.