Optimizing coal water slurry concentration via synergistic coal blending and particle size distribution

Abstract This study explores strategies to enhance coal utilization efficiency, enable on-site coal conversion, transition thermal coal into raw coal, and improve the energy efficiency of coal water slurry (CWS) gasification. By optimizing coal blending and particle size distribution, CWS concentration can be significantly increased. The results demonstrate that, under the constraints of liquid slag discharge technology, a maximum blending ratio of 10% high-rank Panji coal (CP coal) achieves a slurry concentration of 60.5%. This process elevates the coal ash flow temperature by 90°C and narrows the gasification operating range by 44°C, attributed to a notable increase in the relative content of CaAl 2 Si 2 O 8 . Further improvements are achieved by blending finely ground CP coal (CP*) with low-rank Shenhua coal (SH coal) at a 9:1 ratio and increasing CWS additive concentration to 3.0‰, resulting in a slurry concentration of 63.5%. A comprehensive technical and economic evaluation identifies the optimal configuration as incorporating 10% CP* and 0.2% CWS additives into SH coal. Compared to the SH CWS gasification process, Scheme D enhances the effective gas composition and flow rate, reduces costs by 4.19%, and significantly lowers CO 2 emissions. The proposed approach offers substantial economic and environmental benefits, supporting the development of clean coal technology.