Study of the Hydro-transport of Agricultural Biomass Residue in Vertical and Inclined Pipelines
Creators: Javed, Kashif
Publisher: name: University of Alberta Library
Year: 2023

<p>The increasing energy demand, dependency on fossil fuels, reduction in their reserves, and rise in greenhouse gas (GHG) emissions have drawn global attention toward a more viable alternative, such as biofuels produced from agricultural residue biomass, which is an abundantly available type of lignocellulosic biomass globally. Currently, commercial-scale bio-based energy facilities have capacities significantly below those of fossil fuel-based plants, mainly due to the high transportation cost of biomass feedstocks. Earlier research has demonstrated that transporting biomass as water-based slurries through horizontal pipes from farms to bio-refineries significantly reduces transportation costs. However, for a long-distance large-scale biomass pipeline network, inclined and vertical pipe sections will be needed in addition to the horizontal pipe sections to meet the on-site processing at the biomass-based facility or to adapt to the route’s topography throughout the pipeline layout. There is a very limited understanding of the behavior of biomass slurry when flowing through inclined and vertical pipes. This study designed and built a 29 m closed-circuit lab-scale pipeline facility with vertical and inclined test sections to examine the hydro-transport of knife-milled and pre-classified agricultural residue biomass (ARB) particles through pipes at different angles. The aqueous suspensions (or slurries/mixtures) of two different ARB feedstocks (i.e., wheat straw and corn stover) were prepared over a wide range of particle size and slurry saturated mass concentrations. The slurry was pumped over a range of slurry bulk velocities through a closed pipeline loop with vertical and inclined pipe sections at different angles. The research&#39;s primary goals are to (1) experimentally investigate the frictional behaviour and delivered concentration of a specific particle size group of wheat straw water suspensions in vertical upward flows at varied flow conditions, (2) experimentally study how particle size, slurry solid mass concentration, and bulk velocity affect frictional pressure drops and delivered concentrations of wheat straw-water slurries in vertical upward flows, (3) compare the frictional behaviour of corn stover and wheat straw-water slurries in vertical upward flows under varying flow conditions, (4) develop empirical correlation to predict the frictional pressure drop of ARB slurry flows across vertical pipes, (5) experimentally examine how different pipe inclinations impact the frictional behaviour of wheat-straw water suspensions under varying flow conditions. The study findings indicate that several factors, including feedstock, particle size, particle type, slurry concentration, slurry velocity, and pipe inclination, significantly influence the frictional behaviour of the ARB slurries. ARB slurries exhibit drag reduction, which increases with particle size and concentrations. The maximum drag reduction for a particular particle size depends on slurry velocity, feedstock, and pipe tilt; however, the associated critical concentration of maximum drag reduction is a vital function of particle size and suspension velocity regardless of the pipe slope. Most corn stover suspensions in vertical upward flows reduce drag better than wheat straw for velocities ≥ 2.5 m/s, while wheat straw suspensions dominate for low rates (i.e., ≤2.0 m/s). The proposed empirical correlation precisely predicts the frictional pressure drop of ARB slurry flows in vertical pipes, providing a base case for other fibrous biomass materials. Furthermore, the onset velocity of drag reduction reduces for most ARB suspensions in vertical or inclined flows initially up to a specific threshold concentration, after which the slurry behaviour reverses and drag reduction onset velocity increases. Finally, the inclined flows of wheat straw slurries demonstrate maximum drag reduction and minimum onset velocity compared to uphill flows for all the flow conditions. However, uphill flows show nonmonotonic variations in onset velocity and drag reduction, requiring further investigation involving various particle sizes and higher slopes. The research outcomes may assist in designing and operating a long-distance integrated pipeline network for biomass transportation to produce biofuels on a large scale.</p>