Preparation of high concentration coal water slurry with good fluidity based on only modified fine particles under bimodal distribution using the second fluid and the second particle

• Published in: Fuel (Guildford) 2022-06, Vol.317, p.123461, Article 123461
• Main Authors: Yao, Dingsong, Zhao, Hui, Chen, Zhekun, Liu, Haifeng
• Format: Article
• Language: English
• Subjects: Coal; Coal water slurry; Cushions; Fluidity; Friction reduction; Gasification; Hydrophobicity; Only modify; Particulate composites; Rheological properties; Rheology; Slurries; Surface modification; Ultrafines; Viscosity
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.123461

[Display omitted] •Influence of modification methods on rheology characteristics of CWS was studied.•Only modified fine particles were found to sharply reduce viscosity and improve fluidity of CWS.•The oil film mechanism acted as an “air cushion” was proposed to interpret the change of CWS rheology.•The concentration of CWS prepared through only modified fine particles increased by around 5 wt%. Coal water slurry (CWS) is the clean and efficient liquid coal-based fuel. CWS with the high solid content, low viscosity and good fluidity is conducive to efficient gasification and pipeline transport. Surface modification of particle has been demonstrated to contribute to improving the rheology of slurry. In this study, the slurry preparation method of selective particle modification was proposed, which focuses on the effect of modified particle size. Three different methods of surface modification with the kerosene suspension containing ultrafine particles were studied and compared. In method Ⅰ, the suspension was direct added to the mixture of coarse and fine particles. In method Ⅱ and method III, the suspension only modified the coarse and fine particles respectively, then mixing the composite particles with another particle. The apparent viscosity, fluidity and the hydrophobicity of the particle surface were researched. Method III was found to be optimum for reducing apparent viscosity and improving fluidity. The thin hydrophobic oil membrane that coats the surface of the fine particles like an “air cushion”, which can effectively reduce the friction between the particles. The concentration of CWS prepared by method III can increase from 62.7 wt% to 67.0 wt%, and the slurry still has a good fluidity.