Lignocellulosic biomass particle shape and size distribution analysis using digital image processing for pipeline hydro-transportation

Pipeline hydro-transportation has a significant potential to replace truck transportation of agricultural biomass for production of fuels and chemicals. Apart from several operating parameters, biomass particlesʹ shape and size are key factors affecting biomass slurry (water–feedstock mixture) mechanical and chemical properties. Using an image processing approach and ImageJ software, a user-coded plugin was developed to process sample images, measure particle dimensions, and analyse the particle size distributions and corresponding parameters of knife-milled wheat straw and corn stover, which had been pre-classified into four nominal size groups. Particle surface roughness and its degradation during pumping time were also investigated. Investigation of the particle aspect ratio confirmed not only the minor importance of the “width parameter”, but also the significance of the fibrous nature of the test material in pipeline transportation. It was also observed that, the errors involved in nominal sizing brought about noticeable under- and over-estimation of the real dimensions of the particles. Amongst three size distribution functions of Rosin–Rammler, Gaudin–Schuhmann, and log-normal studied, the Rosin–Rammler equations were fitted with least error in all the scenarios. Comparison of Rosin–Rammler approach and size guide number model indicated that for the case of fibrous materials, the size guide number model was more reliable than the Rosin–Rammler approach. Finally, the impact of particle shape and size on biomass slurry mechanical behaviour was analysed.