The Influence of Particle Size Distribution and Nonionic Surfactant on the Rheology of Coal Water Fuels Produced Using Iranian and Venezuelan Coals

Abstract

Coal water fuels (CWF) are aqueous suspensions of fine coal and are used as fluid fuel. Their solid content must be as high as possible. Unfortunately, when the coal particles are coarse, there is a fast settling inside pipelines and tanks; on the other hand, with fine coal particles the CWF viscosity increases and it is difficult to pump the slurry through pipelines. A solution is a mixture of fine and coarse coal with a bimodal particle size distribution and appropriate surfactant to improve the coal surface wettability. The fine/coarse coal ratio, the total amount of solid, the additives, and the presence of entrapped air bubbles have a strong influence on the rheological properties of CWF. By modifying these parameters it is possible to prepare an "optimum" coal water fuel with high solids content and low viscosity.