细粒褐煤脉动气固流化床干燥分选协同提质

Synergy of drying and separation of fine lignite in pulsed gas-solid fluidized bed

煤炭的清洁高效利用是能源领域长期发展的要求.脉动流化床传质传热效率及分选精度高,可对褐煤实现有效的脱水提质.基于热态脉动空气重介质流化床流化试验,研究了不同操作条件对流化床密度及密度稳定性的影响规律和细粒褐煤的干燥脱水效果,并对-6+1 mm细粒褐煤进行了干燥分选协同提质试验.结果表明:增大气流速度、温度及脉动频率,均可提高细粒褐煤的干燥速率,影响床层密度及其稳定性.在温度与脉动能量的耦合作用下,干燥分选同时进行,水分灰分协同脱除,最佳干燥分选条件为温度T=120℃,气速u/u_(mf)=1.3,脉动频率f=4.36 Hz.在最佳条件下对-6+1 mm褐煤进行分选,可能偏差E值可低至0.16 g/cm^(3),精煤发热量可达18.670 kJ·g^(-1),能够达到脱水脱灰一体化的要求.这为细粒褐煤的脱水提质提供试验基础.

Clean and efficient utilization of coal is a requirement of long-term development in the energy field. A pulsed fluidized bed has the characteristics of high heat transfer efficiency and separation accuracy,effectively dewatering and improving the quality of lignite. Based on a pulsed fluidized bed under thermal condition,the effect of different operating conditions on the fluidized bed density and the dewatering effect of-6+1 mm lignite were studied. In addition,an experiment was carried out to determine the synergistic improvement of drying and separation of fine lignite. The results show that the increase of gas velocity,airflow temperature and pulsation frequency can significantly improve the drying rate of fine lignite. The gas velocity,airflow temperature and pulsation frequency also have significant effects on the bed density and its stability. The minimum value of bed density occurs at the temperature T=120 ℃,the gas velocity u/umf=1.2 and the pulsation frequency f=3.49 Hz,and the spatial distribution of bed density is also more stable. Under the synergistic effect of temperature and pulsating energy,the optimal separation conditions are the temperature T=120 ℃,the gas velocity u/u_(mf)=1.3,and the pulsation frequency f=4.36 Hz. After the lignite is dewatered and refined under the optimal conditions,the E value can be as low as 0.16 g/cm^(3) and the calorific value can be increased to 18.670 kJ·g^(-1),which can meet the requirements of dewatering and ash removal integration. This provides an experimental basis for the dewatering and upgrading of fine-grained lignite.