Feasibility Studies of the Sequential Dewatering/Dry Separation of Chinese Lignite in a Vibration Fluidized-Bed Dryer: Effect of Physical Parameters and Operation Conditions

Abstract

The combined dewatering process and dry separation in a vibration fluidized-bed dryer was developed to upgrade Chinese lignite in terms of moisture and ash for effective utilization in power plants. The influence of operational parameters (fluidizing gas velocity, vibration strength, bed height, and drying temperature) and lignite properties (particle size and moisture content) on the drying or separation characteristics of −6−1 mm lignite was examined in a laboratory-scale vibration fluidizedbed dryer. Both operational parameters and lignite properties had a significant effect on the drying and separation performance. The drying and separation behaviors of a vibration fluidized bed were both enhanced in comparison to the case without vibration under the same operating conditions. Moreover, with the change in gas velocity, the drying and separation processes could be combined in the same vibration fluidized-bed dryer. Both processes achieved promising results compared to those of the fixed gas velocity condition, which was confirmed by the low calorific value analysis. A sequential drying and separation system in a vibrofluidized-bed dryer was also designed on the basis of the separation and drying characteristic results.

Recent advances in beneficiation for low rank coals

“…8. Zhao et al [66] found that the fluidizing gas velocity, vibration strength, bed height and drying temperature had significant effect on the drying and separation performance of 6-3 mm and 3-1 mm size fractions lignite. Meanwhile, the drying and separation performance is significantly affected by lignite properties, such as lignite particles and surface moisture content.…”

“…8. Schematic representation of a sequential drying and separation process in a vibro-fluidized-bed dryer [66]. clean coal with 66.41% total sulfur, 97.71% inorganic sulfur and 79.52% ash content.…”

Comparative studies on the effect of mineral matter on physico-chemical properties, inherent moisture and drying kinetics of Chinese lignite

“…For the size of 1-3 mm, the dry beneficiation method using a special vibration fluidized bed can be found in our previous studies [14,36]. After fluidization for a certain time, this bed was divided into five layers in the axial direction and the ash content of each layer was measured.…”

“…Numerous coal cleaning technologies associated to de-watering [6][7][8][9][10] and de-ashing [11][12][13][14] processes have been proposed to sustainably utilize these lignites. However, most of them were not yet widely practiced by the power industry considering the high consumption of energy required during cleaning processes.…”

Synergistic Effects of Ultrasound and Electrolysis on the Dehydration of Fine Lignite Coal

“…[6,7] Therefore, the development of al ignite dehydration technology would assist in increasingi ts comprehensive utilization and save production costs.T he current commonly used methodi sd rying, such as by using non-evaporation dewatering, hot air, pyrogenation, and hot pressing. [8] However, the high volatile component content in lignite easily causes fires and explosions.M oreover, its drying efficiencyi sl ow and the product moisturei s usuallyu nstable because of the high lignite moisture content. [9] Moisture control of fine lignite has therefore become ar esearche mphasis andh otspoti nt he coal preparation industry and is am ajor challenge in the coal industry in terms of time,l abor, and cost savings.I ti sa lso one of the bottlenecks that limits the development of clean coal technology.…”