Switchgrass can be used in a number of biofuel applications, but moving it - especially feeding it into boilers - can be problematic, said Klein Ileleji, an assistant professor of agricultural and biological engineering.
While corn and soybeans are round and spherical, switchgrass is shaped more like matchsticks, causing pieces to interlock and disrupt its ability to flow. Those blockages cost time and can be dangerous for those tasked with breaking the clog, he said.
"In any facility ¨l in a power plant or in a processing facility ¨l when you have a blockage, it's a processing nightmare," said Ileleji, whose findings are in the current issue of the journal Transactions of the ASABE.
Ileleji compared circularity, roundness and aspect ratio for corn, soybean and switchgrass that had been hammermilled to three different sizes. Aspect ratio, which has the greatest effect on the ability of switchgrass to flow, is the ratio of a switchgrass particle's length to its width.
Conventional wisdom held that grinding switchgrass into smaller pieces would bring its aspect ratio closer to that of corn and soybeans, which have ratios close to 1 and no problems with flowability.
"Switchgrass is not a good flowable feedstock. You would think grinding it smaller would help," Ileleji said. "But grinding does not necessarily change the morphological characteristics in switchgrass that are important for flow."
Ileleji's testing showed that hammermilling - one of the most common grinding techniques, which beats and breaks biomass until it is small enough to pass through screens - breaks switchgrass in a way that keeps its aspect ratio about the same no matter the size. Unless the switchgrass is milled into a powder, those high aspect ratios would keep causing switchgrass to interlock and clog in bulk flow.
Ileleji said processors could save money with the information because they can stop hammermilling switchgrass when it fits through a 6.4 mm screen, the largest Ileleji tested.
"Grinding consumes a lot of energy. It is one of the highest energy costs in a processing facility," Ileleji said. "It's better to grind switchgrass through a 6.4 mm screen than to use more energy to grind through a smaller screen expecting that its handling characteristics would be improved dramatically."
Ileleji said he would study flow behavior of switchgrass through hoppers to try to find ways to keep it from creating blockages. Duke Energy and the Purdue Energy Center funded his research, which is part of his doctoral student Cedric Ogden's research on the flow mechanics of switchgrass bulk solid in hoppers under gravity discharge.
Abstract on the research in this release is available at: http://www.purdue.edu/newsroom/research/2010/100412IelejiMorphology.html
Brian Wallheimer | EurekAlert!
Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University
New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Materials Sciences
18.01.2017 | Information Technology
18.01.2017 | Ecology, The Environment and Conservation