Effect of 3–0 mm fine coal migration characteristics on high sulfur lignite separation in compound dry cleaning apparatus

Abstract

Coal is the significant basic energy to promote the national economic development. Promoting the energy development is of great significant to realizing the energy strategic goals of Carbon Peak and Carbon Neutrality. In this paper, the influence of the migration behavior of 3–0 mm pulverized coal in the bed space on the separation of high-sulfur lignite using compound dry separation bed was mainly investigated. The migration characteristics of differentiated density and size particles in the bed space was emphatically analyzed and the optimum leading density and particle size composition to form autogenous medium bed were determined. The influence of vibration intensity and airflow velocity on the spatial stability of bed density was systematically investigated. The distribution law of low-grade high-sulfur lignite in compound dry separation bed was analyzed and the distribution area of bed products was determined. The experimental results show that when ρ = 1.8–2.0 g/cm3, d = 0.5–0.25 mm, the pulverized coal particles are distributed uniformly along bed height direction and the fluidization quality of bed reaches the optimum and they are the optimum leading particle size and density composition for forming autogenous medium bed. As the vibration amplitude and frequency increase, the density standard deviation decreases firstly and then increases. When A = 2.4 mm, f = 21 Hz, the density stability of bed space reaches the best and the influence of vibration frequency on the spatial stability of bed density is more sensitive compared with the influence of vibration amplitude. Under the condition (A = 2.4 mm, f = 21 Hz), when the airflow velocity range is Uv = 0.112–0.203 m/s, the bed density could keep being distributed uniformly and stably. Under the optimum operating conditions, the compound dry separation tests for low-grade high-sulfur lignite was conducted. The distribution law of sulfur content in the bed was analyzed and the distribution area of bed products was determined. Area Ⅰ is the low density material separation area; Area Ⅱ is the middle and high density product transition and separation area; Area III is the high density product migration area. The yield of clean coal is 73.06 % and the sulfur content, ash content and caloric value are 0.96 %、9.37 % and 12.38 MJ/Kg, respectively. The probable value (Ep) is 0.08 g/cm3 and the high-precision separation of low-grade high-sulfur lignite using compound dry separation bed has been realized.