The Technical Analysis on Upgrade and Coupling of Low-Quality Coal

Bin Zhao^1,2, Qiang Yao¹, Shan Lu¹, Qinggong Wang², Junfu Lv²

¹Key Laboratory for Modem Metallurgy Technology of Ministry of Education, Hebei United University, Tangshan, China.
²Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing, China.

DOI: 10.4236/epe.2014.613039                

Abstract

Experimental study was conducted with regard to upgrading low-quality coal by low temperature pyrolysis technology and fluidization classification technology, which laid the theoretical foundation for research and development of low-quality coal upgrading process. Firstly, a pyrolysis pilot experiment of long-flame coal was performed and the optimum pyrolysis conditions were found. When the final pyrolysis temperature was 450?C and the residence time was 10 minutes, the content of semicoke volatile dry ash-free was about 22.89% and the content of semicoke ash was about 16.1%. More than 5% of the ash needs to be removed before entering the pyrolysis fluidized bed. Thus, classification tests were carried out to pick out the coal particles with the target size of 500 μm, using a gas-solid fluidized bed coal picker. It was found that the separating effect of coal particles was the most satisfactory when the inlet velocity at the bottom was 3.27 m/s. The percentage of particles with diameters less than 500 μm was as low as 28.7% in the coarse samples. Based on the test results, a novel process of low-quality coal upgrade and coupling was proposed, which realized the sorting, grading, drying and pyrolysis of low-quality coal through the multi-stage fluidized bed integrated process.

Keywords

Low-Quality Coal, Low Temperature Pyrolysis, Fluidized Bed Particle Classification

Conflicts of Interest

The authors declare no conflicts of interest.

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