Rheology of fibre suspension flows in the pipeline hydro-transport of biomass feedstock

Abstract

In the hydro-transport of biomass feedstock by pipeline to bio-refineries, the rheology of the biomass slurry directly impacts the specifications and, therefore the cost of pipeline components. In this study, the rheological characteristics of untreated fine wood chip slurries across a broad range of slurry temperatures (5–15 °C) and solids concentrations (3–15 wt% dry-matter) were experimentally studied. Slurry samples were pumped in a closed-circuit pipeline facility where slurry flow longitudinal pressure drops were simultaneously measured. The rheological characteristics of the samples were then measured using a rotational viscometer with a vane-in-cup geometry. At low slurry concentrations (˂6 wt% dry-matter), the biomass slurry exhibited Newtonian behaviour; however, non-Newtonian (shear-thinning) behaviour was seen at higher slurry concentrations. In order to approximate the corresponding rheological parameters, different well-known non-Newtonian viscosity models (power-law, Bingham, Casson, and Herschel-Bulkley) were applied to experimental data. In addition, a new approach for approximating the apparent viscosity of biomass slurries using longitudinal pressure drop measurements was introduced and validated. The method has not been previously applied to non-Newtonian biomass slurries under turbulent flow regimes. • Rheological characteristics of untreated wood chip biomass slurries were studied. • Biomass slurry samples were made off a closed-circuit pipeline facility. • Rotational viscometer with vane-in-cup geometry was used over range of temperatures. • Corresponding rheological parameters were approximated using well-known models. • A pressure drop-based method proposed to approximate viscosity of slurry flows.