Effect of 0–1 mm pulverized coal on desulfurization and upgrading of low grade lignite in dry cascade separation bed with compound force field

Abstract

Coal is the important pillar of national economic development. China has a rich variety of coal resources, of which low-grade lignite resources have huge reserves. As the consumption of high-quality coal resources intensifies and its output is declining, strengthening the efficient use of low-grade lignite is an important measure to ensure energy supply and safety, and to stabilize industrial energy production. This paper mainly studies the influence of the characteristics of 0–1 mm coal powder in the dry cascade separation bed with compound force field on the spatial migration law of low-grade lignite and the uniformity and stability of the density of the autogenous medium bed. The regional spatial distribution of sulfur content of low-grade lignite under different autogenous medium content was systematically studied. The emphasis is on the influence of the particle size and density composition of 0–1 mm coal powder on the uniform stability of the autogenous medium bed density. At the same time, the spatial distribution and cascade separation of low grade lignite in the variable distance regional autogenous medium bed are analyzed. The test results show that when the content is 12.5–20%, the sulfur content of the upper and lower materials is relatively stable in the high and low density material enrichment areas, and the sulfur content of the middle material has a large fluctuation range. At this time, a autogenous medium fluidized bed with uniform and stable density can be formed; The 0.125–0.25 mm coal powder particles are uniformly distributed along the XOY section and XOZ section, which is the dominant particle size fraction for forming an autogenous fluidized bed; Coal particles with a density of 1.6–1.8 g/cm3 can form a fluidized bed with stable density, which is the dominant density fraction for forming an autogenous medium bed. During the dynamic sorting process, the materials in zone I present a differentiated distribution, realizing the separation of low-density materials. The spatial distribution of materials in zone II fluctuates greatly, realizing the separation of medium and high-density materials. The materials are distributed relatively evenly in zone III, which realizes the conveying and separation of high-density materials. The yield of clean coal is 65.12%, the ash content is 9.89%, the sulfur content is 0.99%, the gangue yield is 34.88%, the ash content is 44.98%, and the sulfur content is14.89%. The probable error of E is 0.07 g/cm3, and the high-precision desulfurization, ash reduction and quality improvement of low-grade lignite by the dry cascade separation bed is realized.