Search

The scale-up of biorefineries to compete with fossil fuel production is limited by the high overland transportation cost of lignocellulosic biomass. Pipeline hydro-transport of agricultural or forest residue biomass to biorefineries could be a cost-effective and sustainable solution to this problem. The upward flow of chopped maize stover (also known as corn stover) aqueous slurries through a vertical pipe section of a 29 m long, 50 mm diameter in a closed pipeline loop was studied. The frictional pressure drops of maize stover slurries were measured at several particle sizes (from <3.2–19.2 mm), slurry solid concentrations (5–40% [mass]), and slurry velocities (0.5–4.3 m s−1). The results were analysed and compared with wheat straw. For specific concentrations and flow rates, particle size, shape, and flexibility are the factors that most reduced drag, which was highest (by 32%) for the largest particle size of maize stover. For velocities ≥2.5 m s−1, maize stover suspensions (other than the 3.2 mm particle size) were more effective in reducing drag than wheat straw, whereas at lower velocities (≤2.0 m s−1), wheat straw had more influence (other than the 19.2 mm). The results for critical concentrations for maximum drag reduction, onset velocity, threshold concentration for minimum onset velocity, and their variations with respect to particle size, particle type, and slurry concentrations provide new insights that require further investigation in larger diameter pipes. The results here will be beneficial for the design and operation of long-distance pipeline hydro-transport of biomass. • Hydro-transport of ground maize stover was examined in a vertical pipe section. • Frictional behaviour of two feedstocks was compared at various flow conditions. • Particle size, shape, and fibre flexibility were dominant in drag reduction (DR). • Onset velocity of DR lowest for largest particle size of maize stover. • Critical concentration for the maximum DR of maize stover lower than wheat straw. [ABSTRACT FROM AUTHOR]

The use of biofuels helps mitigate greenhouse gas emissions. Earlier studies have shown that transporting biomass in horizontal pipelines in the form of water-based slurries significantly reduces transportation costs. The frictional behaviour of water-based chopped wheat straw slurry in a vertical pipeline has not been studied and this is the focus of this study. In situ concentrations of water-based conventional solids of medium sand, glass beads, and fine sand and straw slurry flows were determined by measuring their delivered concentrations in pseudo-homogeneous regimes for prepared concentrations of 1–6% (dry volume of conventional solids) and 5–25% (saturated mass of straw), respectively. Two grades of sand and glass beads with mean particle diameters of 0.103, 0.447, and 0.5 mm, respectively, and straw with a nominal particle length of 19.2 mm were utilised. The delivered concentrations for the straw slurries and fine sand were close to their corresponding prepared concentrations and were homogeneous. There was a large discrepancy between prepared and delivered concentrations for the medium-sized sand and glass beads slurries. The pressure drop of straw slurries over the range of velocities of 0.5–4.2 m s−1 and mass concentrations of 5–25% through the vertical pipe showed a maximum drag reduction of 19% at a concentration of 25% (mass) and at a 3.5 m s−1 velocity. For concentrations of 5–20% (mass), the straw slurries showed drag-reducing capabilities in the mixed and turbulent flow regions for various velocities that were different from horizontal flows. • The pumping of aqueous slurries of chopped wheat straw was studied in a pipeline. • Friction losses in the vertical pipeline were measured over a range of variables. • The delivered and prepared concentrations for wheat straw slurries were identical. • Straw slurries in vertical upward flows behaved differently than horizontal flows. • Drag reduction appeared at even low velocities and mass concentrations of straw. [ABSTRACT FROM AUTHOR]