The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shahab Sokhansanj - One of the best experts on this subject based on the ideXlab platform.
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Techno-economic assessment of Pellets produced from steam pretreated biomass feedstock
Biomass and Bioenergy, 2016Co-Authors: Hassan Shahrukh, Amit Kumar, Adetoyese Olajire Oyedun, Bahman Ghiasi, Linoj Kumar, Shahab SokhansanjAbstract:Abstract Minimum production cost and optimum plant size are determined for pellet plants for three types of biomass feedstock – forest residue, agricultural residue, and energy crops. The life cycle cost from harvesting to the delivery of the Pellets to the co-firing facility is evaluated. The cost varies from 95 to 105 $ t −1 for regular Pellets and 146–156 $ t −1 for steam pretreated Pellets. The difference in the cost of producing regular and steam pretreated Pellets per unit energy is in the range of 2–3 $ GJ −1 . The economic optimum plant size (i.e., the size at which pellet production cost is minimum) is found to be 190 kt for regular pellet production and 250 kt for steam pretreated pellet. Sensitivity and uncertainty analyses were carried out to identify sensitivity parameters and effects of model error.
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effects of thermal treatment on energy density and hardness of torrefied wood Pellets
Fuel Processing Technology, 2015Co-Authors: Jianghong Peng, Shahab Sokhansanj, Jingsong Wang, Jim C Lim, Hanchao Peng, Dening JiaAbstract:Abstract Three types of wood Pellets samples, including two types of commercial Pellets and one type of lab-made control Pellets were torrefied in a fixed bed unit to study the effect of thermal pretreatment on the quality of wood Pellets. The quality of wood Pellets was mainly characterized by the pellet density, bulk density, higher heating value, Meyer hardness, saturated moisture uptake, volumetric energy density, and energy yield. Results showed that torrefaction significantly decreased the pellet density, hardness, volumetric energy density, and energy yield. The higher heating value increased and the saturated moisture content decreased after torrefaction. In view of the lower density, lower hardness, lower volumetric energy density, and energy yield of torrefied Pellets, it is recommended that biomass should be torrefied and then compressed to make strong Pellets of high hydrophobicity and volumetric energy density.
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Pelletization of torrefied sawdust and properties of torrefied Pellets
Applied Energy, 2012Co-Authors: Xinhua Liu, Robert Legros, C. Jim Lim, Shahab SokhansanjAbstract:Pelletization of torrefied sawdust from a fluidized bed reactor was investigated to quantify the energy consumption and pellet properties, including moisture adsorption, pellet density and Meyer hardness. Energy consumptions in compaction and extrusion for torrefied sawdust were significantly higher than those for untreated sawdust at the same compression temperature, while the moisture uptake rate of Pellets decreased with increasing the severity of torrefaction. The densities of torrefied Pellets were lower than the control pellet due to the loss of chemically bonded water and low-melting point compounds during torrefaction which act as a binding agent when softened at similar to 100 degrees C. The properties of Pellets were affected by the removal of most low-melting or - softening point components. (C) 2012 Elsevier Ltd. All rights reserved.
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economics of producing fuel Pellets from biomass
Applied Engineering in Agriculture, 2006Co-Authors: Sudhagar Mani, Shahab Sokhansanj, Anthony F TurhollowAbstract:An engineering economic analysis of a biomass pelleting process was performed for conditions in North America. The pelletization of biomass consists of a series of unit operations: drying, size reduction, densifying, cooling, screening, and warehousing. Capital and operating cost of the pelleting plant was estimated at several plant capacities. Pellet production cost for a base case plant capacity of 6 t/h was about $51/t of Pellets. Raw material cost was the largest cost element of the total pellet production cost followed by personnel cost, drying cost, and pelleting mill cost. An increase in raw material cost substantially increased the pellet production cost. Pellet plants with a capacity of more than 10 t/h decreased the costs to roughly $40/t of Pellets. Five different burner fuels – wet sawdust, dry sawdust, biomass Pellets, natural gas, and coal were tested for their effect on the cost of pellet production. Wet sawdust and coal, the cheapest burner fuels, produced the lowest pellet production cost. The environmental impacts due to the potential emissions of these fuels during the combustion process require further investigation.
M Valovic - One of the best experts on this subject based on the ideXlab platform.
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compatibility of pellet fuelling with elm suppression by rmps in the asdex upgrade tokamak
Nuclear Fusion, 2020Co-Authors: M Valovic, P Lang, A Kirk, W Suttrop, A Bock, P J Mccarthy, M Faitsch, B Plockl, Eurofusion Mst TeamAbstract:It is demonstrated that tokamak plasma can be fuelled by Pellets while simultaneously maintaining ELM suppression by external resonant magnetic perturbations (RMPs). Pellets are injected vertically from high field site and deposited at outer part of plasma cross section. Each pellet triggers a benign MHD event followed by a short lived ELM-free phase. The ELM suppression phase with pellet fuelling lasts 11 pellet cycles and is terminated by intentionally increasing the pellet rate to cause a transition to the ELMy phase.
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density control by Pellets in plasmas with elm mitigation by rmps in the asdex upgrade tokamak
Plasma Physics and Controlled Fusion, 2018Co-Authors: M Valovic, L Garzotti, P Lang, A Kirk, W Suttrop, M Cavedon, M Dunne, R Fischer, L Guimarais, N LeutholdAbstract:This paper describes the extension of the previous experimental database on density control by Pellets and ELM control by RMPs in the ASDEX Upgrade tokamak. A stationary low triangularity plasma is sustained by simultaneous pellet fuelling and RMP ELM control at ion pedestal collisionality of ν *i,ped ~ 0.5. Refuelling of the RMP induced density pump-out requires a pellet rate of Φpel ~ 0.073 P aux/T t,ped. The duration of refuelling of density pump-out can be minimised to about 3 energy confinement times. Pellet fuelling increases or preserves ion pedestal pressure with respect to unfuelled ELM suppressed/mitigated phase. Pellets cause transition from ELM suppression to ELMy regime: At low triangularity, the first pellet triggers a transition to an ELMy phase but subsequent ELMs are not modulated by Pellets. At elevated triangularity, initial Pellets trigger ELM-like events but in-between Pellets ELM suppression is preserved. In later phase, as density increases the plasma transitions to an ELMy phase similar to low triangularity case.
Goran Alderborn - One of the best experts on this subject based on the ideXlab platform.
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occurrence of fragmentation during compression of Pellets prepared from a 4 to 1 mixture of dicalcium phosphate dihydrate and microcrystalline cellulose
European Journal of Pharmaceutical Sciences, 1999Co-Authors: Fredrik Nicklasson, Barbro Johansson, Goran AlderbornAbstract:The occurrence of pellet fragmentation during the compression of Pellets prepared mainly from a hard pharmaceutical filler material was investigated. The Pellets consisted of 4 parts dicalcium phosphate dihydrate (generally considered as a hard material) to 1 part microcrystalline cellulose (used as a pellet forming material). Pellets of two porosities, 36% and 55%, were prepared. Compacts formed at 100 MPa applied pressure were fractured and the fracture surfaces were then visually examined. Lubricated Pellets were also compacted in order to obtain tablets which could be easily deaggregated. Pellets retrieved from deaggregated tablets were compared with uncompacted Pellets with respect to size and fracture resistance. The results showed that many Pellets exposed in the tablet fracture surface were fractured, especially those with higher porosity. However, the lubricated Pellets retrieved from deaggregated tablets were similar in size to the uncompacted Pellets, i.e. fragmentation of these Pellets was minimal. Furthermore, these retrieved Pellets were more resistant to fracture than the original uncompacted Pellets, indicating that the formation of cracks or flaws in the Pellets during compaction was also minimal. It was thus concluded that deformation and probably densification, and not fragmentation, was the dominant compression mechanisms of this pellet formulation.
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effect of pellet size on degree of deformation and densification during compression and on compactability of microcrystalline cellulose Pellets
International Journal of Pharmaceutics, 1998Co-Authors: Barbro Johansson, Fredrik Nicklasson, Goran AlderbornAbstract:Abstract Microcrystalline cellulose Pellets (size fractions 425–500 and 1250–1400 μ m, porosity 38%) were prepared and compacted. The porosity and tensile strength of tablets of unlubricated Pellets were determined. Tablets of lubricated Pellets were deaggregated and the porosity and the main dimensions of the retrieved Pellets were measured. The dominating mechanisms of compression for the Pellets were deformation and densification. The original size of the Pellets did not affect the volume or porosity changes of the tablet with tablet formation pressure. Consequently, the degree of densification of individual Pellets, which occured during compression, was independent of the original pellet size. However, the degree of deformation of individual Pellets during compression was higher for larger Pellets. There was thus a different dependence of pellet size for the dominating mechanisms of compression for this type of aggregates. An explanation for this is that deformation is a phenomenon related to the force distribution in the pellet bed during compression, while densification is related to the total stress applied to the pellet bed during compression. The results obtained in this study have also shown that the compactability of Pellets at moderate applied pressures was independent of the original pellet size, but at 160 MPa, the larger Pellets formed tablets of a slightly higher tensile strength.
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degree of pellet deformation during compaction and its relationship to the tensile strength of tablets formed of microcrystalline cellulose Pellets
International Journal of Pharmaceutics, 1996Co-Authors: Barbro Johansson, Goran AlderbornAbstract:The degree of deformation and densification of Pellets during compression have been quantified. The relationship between the degree of deformation of the Pellets and their compactability were also studied. Two sets of Pellets of microcrystalline cellulose, showing a marked difference in intragranular porosity, were prepared by extrusion-spheronization. The Pellets were mixed with a lubricant and compacted at a series of applied pressures. The individual Pellets were retrieved after compression by tablet deaggregation and the porosity (densification behaviour) and dimensions (deformation behaviour) of the retrieved Pellets were determined. Tensile strength of compacts prepared of unlubricated Pellets was also determined. The incidence of pellet fragmentation was almost non-existent during the compression for both sets of Pellets. The low porosity Pellets showed only limited local permanent deformation during compression and the pellet porosity was unaffected by the compression. The high porosity Pellets showed both a high compression-induced change in shape and a marked decrease in pellet porosity. Tensile strength values of tablets of unlubricated Pellets indicated that a marked bulk structure deformation of the Pellets was necessary for the formation of intergranular contacts of a high bonding force in the compact.
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compression behaviour and compactability of microcrystalline cellulose Pellets in relationship to their pore structure and mechanical properties
International Journal of Pharmaceutics, 1995Co-Authors: Barbro Johansson, M Wikberg, Ragnar Ek, Goran AlderbornAbstract:Abstract Two series of microcrystalline cellulose Pellets were produced by extrusion-spheronization and the size fraction 710–1000 μm was prepared by sieving. The preparation procedure gave nearly spherical Pellets with similar shape and surface characteristics but markedly different porosity and mechanical properties. The Pellets compressed by permanent deformation rather than by fragmentation. The degree of pellet deformation increased with an increased original pellet porosity while the mechanical strength of the Pellets was not a primary factor in the compression behaviour of the Pellets. The compactability of the Pellets related directly to the original pellet porosity. The results indicate thus that the pellet porosity determined the degree of their deformation during compression which in turn controlled the pore structure and the tensile strength of the compact formed. A high degree of pellet deformation gave a low intergranular separation distance in the compact and promoted the formation of intergranular bonds of a high bonding force.
David Agar - One of the best experts on this subject based on the ideXlab platform.
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A comparative economic analysis of torrefied pellet production based on state-of-the-art Pellets
Biomass & Bioenergy, 2017Co-Authors: David AgarAbstract:Abstract Torrefied Pellets have fuel properties superior to those of conventional wood Pellets and potentially allow greater rates of co-firing and thus larger reductions in net CO 2 emissions. Despite the growing amount of scientific output on torrefaction, the economic feasibility of torrefied pellet production is still a topic of considerable uncertainty. This is an obstacle for decision makers looking to implement sustainable energy policies. This paper compares the economics of torrefied Pellets to conventional wood Pellets. Working backwards from demonstrated pellet properties, this work attempts to answer the following question: Based on state-of-the-art torrefied Pellets, what would be the maximum capital investment required for a torrefied pellet plant so that production is economically viable? Herein, the production costs of torrefied Pellets are calculated based on inputs in production. The market value of the produced Pellets is estimated and a cash-flow analysis is carried out. Three economic indicators are calculated and compared for a torrefied and conventional pellet production scenario. A sensitivity analysis is carried out for selected process inputs and the cost of CO 2 through co-firing Pellets is estimated. The results indicate that state-of-the-art torrefied pellet production cannot compete with conventional Pellets even with transatlantic product transport distances. A high capital investment cost and a low heating value are the main barriers to economic feasibility of state-of-the-art torrefied Pellets.
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experimentally determined storage and handling properties of fuel Pellets made from torrefied whole tree pine chips logging residues and beech stem wood
Fuel, 2014Co-Authors: T Jarvinen, David AgarAbstract:Abstract Torrefaction is currently of interest for the production of a new generation of fuel Pellets suitable for increasing co-firing rates at pulverised-coal power plants. However, few results have been reported on properties of Pellets which can currently be produced from torrefied materials. This data is required in order to evaluate the suitability of this fuel for its primary application. The objective of this study was to obtain measured results on storage and handling properties of Pellets made of torrefied pine, logging residues (with and without wheat flour binder) and beech. Experimental methods, most of which adhere to standard procedures, are described. The measured properties include calorific value, bulk density, durability, hardness and equilibrium moisture content (EMC). Additionally, EMC isotherms of torrefied beech wood are presented. The results are analysed and their influence on the feasibility of large-scale pellet production is discussed. The measured and derived values presented will be of use in determining feasibility of torrefied pellet production in offsetting the use of fossil coal. From the results the following statements can be made regarding produced pellet samples: • Feedstock choice has a strongly influence on properties of torrefied Pellets. • Durability of torrefied Pellets is problematic compared to wood Pellets. • Outdoor heap storage of torrefied Pellets is not recommended. • Logging residues do not seem to be an optimal feedstock choice for torrefied Pellets. • Wheat flour does not appear suitable as binder for torrefied Pellets production due to water absorption. • Pelletising using high die temperature (above 170 °C) should be investigated.
L R Baylor - One of the best experts on this subject based on the ideXlab platform.
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reduction of edge localized mode intensity on diii d by on demand triggering with high frequency pellet injection and implications for iter
Physics of Plasmas, 2013Co-Authors: L R Baylor, S K Combs, T C Jernigan, S J Meitner, N Commaux, R C Isler, E A Unterberg, N H Brooks, T E Evans, A W LeonardAbstract:The injection of small deuterium Pellets at high repetition rates up to 12× the natural edge localized mode (ELM) frequency has been used to trigger high-frequency ELMs in otherwise low natural ELM frequency H-mode deuterium discharges in the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)]. The resulting pellet-triggered ELMs result in up to 12× lower energy and particle fluxes to the divertor than the natural ELMs. The plasma global energy confinement and density are not strongly affected by the pellet perturbations. The plasma core impurity density is strongly reduced with the application of the Pellets. These experiments were performed with Pellets injected from the low field side pellet in plasmas designed to match the ITER baseline configuration in shape and normalized β operation with input heating power just above the H-mode power threshold. Nonlinear MHD simulations of the injected Pellets show that destabilization of ballooning modes by a local pressure perturbation is responsible for the pellet ELM triggering. This strongly reduced ELM intensity shows promise for exploitation in ITER to control ELM size while maintaining high plasma purity and performance.
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pellet fuelling elm pacing and disruption mitigation technology development for iter
Nuclear Fusion, 2009Co-Authors: L R Baylor, S K Combs, J B O Caughman, D T Fehling, C R Foust, S Maruyama, T C Jernigan, S J Meitner, P B Parks, A L QuallsAbstract:Plasma fuelling with pellet injection, pacing of edge localized modes (ELMs) by small frequent Pellets and disruption mitigation with gas jets or injected solid material are some of the most important technological capabilities needed for successful operation of ITER. Tools are being developed at the Oak Ridge National Laboratory that can be employed on ITER to provide the necessary core pellet fuelling and the mitigation of ELMs and disruptions. Here we present progress on the development of the technology to provide reliable high throughput inner wall pellet fuelling, pellet ELM pacing with high frequency small Pellets and disruption mitigation with gas jets and shattered Pellets. Examples of how these tools can be employed on ITER are discussed.
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experimental study of pellet delivery to the iter inner wall through a curved guide tube at steady state pressure
21st IEEE NPS Symposium on Fusion Engineering SOFE 05, 2005Co-Authors: S K Combs, L R Baylor, J B O Caughman, D T Fehling, C R Foust, S Maruyama, J M Mcgill, D A RasmussenAbstract:Injection of solid hydrogen Pellets from the magnetic high-field side will be the primary technique for depositing fuel particles into the core of International Thermonuclear Experimental Reactor (ITER) burning plasmas. This injection scheme will require the use of a curved guide tube to route the Pellets from the acceleration device, under the divertor, and to the inside wall launch location. In an initial series of pellet tests in support of ITER, single 5.3-mm-diam cylindrical D2 Pellets were shot through a mock-up of the planned ITER curved guide tube. Those data showed that the pellet speed had to be limited to ap300 m/s for reliable delivery of intact Pellets. Also, microwave cavity mass detectors located upstream and downstream of the test tube indicated that ap10% of the pellet mass was lost in the guide tube at 300 m/s. The tube base pressure for that test series was ap10-4 torr. However, for steady-state pellet fueling on ITER, the guide tube will operate at an elevated pressure due to the pellet erosion in the tube. Assuming the present design values for ITER pellet fueling rates/vacuum pumping and a 10% pellet mass loss during flight in the tube, calculations suggest a steady-state operating pressure in the range of 10-20 torr. Thus, experiments to ascertain the pellet integrity and mass loss under these conditions have been carried out. Also, some limited test data were collected at a tube pressure of ap100 torr. No significant detrimental effects have been observed at the higher tube pressures. The new test results are presented and compared to the baseline data previously reported
