关键词: 煤, 重选, 分质利用, 热解, 燃烧, 气化

Abstract:

Pre-separation of different macerals in coal based on the physical properties and then quality-based utilization are effective process to realize clean and efficient use of coal. According to the density difference of different macerals in coal, a sub-bituminous coal was separated by gravity separation method into maceral concentrates that was enriched in vitrinite, inertinite and mineral, respectively. Compared with the raw coal, the vitrinite increased from 48.25% to 76.02% in the vitrinite-rich sample, the inertinite increased from 43.96% to 63.98% in the inertinite-rich sample, and the minerals content increased from 10.47% to 61.99% in the mineral-rich sample. By thermogravimetry-mass spectrometry analysis, the pyrolysis behavior and the gas evolution of different maceral concentrates were investigated, and the combustion and gasification reaction characteristics were also discussed. The results show that the amount of volatiles from pyrolysis of vitrinite-rich sample is significantly higher than that of raw coal and inertinite-rich sample, indicating that the separation processes successfully separate and enrich some of the functional groups of the coal. Moreover, the pyrolysis characteristic temperatures of the maceral concentrates are basically the same, indicating that the main reaction components of the vitrinite-rich and inertinite-rich sample are similar, but the contents are different. Combustion experiments show that the overall trend of combustion curves of the vitrinite-rich, inertinite-rich sample and raw coal are similar, reflecting little difference in combustion activity. CO₂ gasification experiments show that the gasification reactivity of vitrinite-rich sample is the lowest, and the gasification reactivity of inertinite-rich sample is close to that of the raw coal gasification. Comparing the calculated reaction curve of raw coal with the experimental curve, it is found that the coal separation process and the separation of vitrinite, inertinite and minerals have little effect on the volatile liberation in the pyrolysis process, while decreasing the combustion and gasification reaction activity.

Key words: coal, gravity separation process, quality-based utilization, pyrolysis, combustion, gasification