Rheological Properties of Methacoal Suspensions Formulated from Texas Lignite. Final Report

摘要

Rheological properties of Methacoal suspensions were evaluated as a function of shear rate, solids volume fraction, particle size distribution, and initial lignite moisture content. The suspensions were mostly quite stable, highly shear thinning, and the apparent viscosity increased exponentially with solids fraction. The viscosity data were fit by various models, and the model parameters were found to correlate with the fraction of fines in the suspension. Final correlations showed the apparent viscosity to be a minimum at a particular fraction of fines in suspension, the value of which depends upon the shear rate. The extent of this minimum is more pronounced as the lignite moisture content is reduced. Stable Methacoal suspensions were less compact and more fluid than comparable water suspensions. It was demonstrated that larger quantities of Methacoal suspensions with good stability and flow properties could be produced using a continuous Dispax homogenizer. Representative tube flow data were obtained for some of these suspensions in a specially constructed tube flow viscometer in laminar flow, which increased the effective range of viscosity measurements by over an order of magnitude. A bench scale pipe flow facility has been constructed incorporating eight tubes with diameters up to 1 1/2 in., each 40 ft. long, capable of obtaining data in the turbulent flow range as well. This facility can operate either continuously using a centrifugal slurry pump, or on a once through basis using pressurized air drive. (ERA citation 05:011193)