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Storage and Flow of Solids

01 Jan 1964-
About: The article was published on 1964-01-01 and is currently open access. It has received 585 citations till now. The article focuses on the topics: Flow (mathematics).
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Patent
21 May 2020
TL;DR: In this article, the authors present compositions comprising polysaccharide particles with an average size of about 0.1-10 mm and a weight-average degree of polymerization (DPw) of at least 100.
Abstract: Disclosed herein are compositions comprising polysaccharide particles with an average size of about 0.1-10 mm. These particles comprise at least (i) about 50%-90% by weight water or an aqueous solution, and (ii) about 10%-50% by weight insoluble alpha-glucan, or an insoluble cationic ether thereof, comprising alpha-1,3-glycosidic linkages and having a weight-average degree of polymerization (DPw) of at least about 100. Further disclosed are methods of preparing these compositions, as well as systems for storing and/or moving them.

4 citations

Book ChapterDOI
01 Jan 2002
TL;DR: The Janssen formula predicts vertical and lateral pressure exerted on a silo by a granular material as an exponential function of the depth of fill as mentioned in this paper, which is the most widely used analytical solution for the calculation of pressures in silos.
Abstract: Handling bulk solid materials is one of the least understood areas associated with solid processing plants (Knowlton et al., 1994). For that reason, mechanics of granular materials have recently gained growing interest among researchers and industrial practitioners. New theoretical approaches and experimental methods have been developed for procedures such as material characterisation and silo design. Silo design based on Janssen’s (1895) equation with necessary material parameters such as bulk density, coefficient of friction on the wall and pressure ratio allows for calculation of wall and floor loads with acceptable accuracy. Although one hundred years old, Janssen’s equation is still the most widely used analytical solution for the calculation of pressures in silos. A review of 13 design codes by Wilms (1991) showed that all of them use the Janssen formula to calculate pressure distribution in deep vertical wall silo. The Janssen formula predicts vertical and lateral pressure exerted on a silo by a granular material as an exponential function of the depth of fill: $$ \eqalign{ & {\sigma _z} = {{\rho gD} \over {4k\mu }}\left[ {1 - {e^{{{4k\mu } \over D}z}}} \right] \cr & {\sigma _x} = k{\sigma _z} \cr} $$ (1) where: D - silo diameter (m); g - acceleration of gravity (9.81 m/s2); k - lateral to vertical pressure ratio (Janssen’s constant); z - vertical co-ordinate, depth of grain in silo (m); μ- coefficient of wall friction; ρ- bulk density (kg/m ); σ x - lateral pressure (Pa); σ z - vertical pressure (Pa).

4 citations

Dissertation
01 Jan 2008
TL;DR: In this article, a partial equilibrium model was used to examine supply potentials for reed canary grass (Phalaris arundinacea L.) in Vasterbotten County, northern Sweden.
Abstract: This thesis focuses on two main areas: methods for assessing regional supply potentials of reed canary grass (Phalaris arundinacea L.) (RCG); and process technology for the production of high-quality RCG pellets. Partial equilibrium modelling, incorporating a break-even price approach, was used to examine supply potentials for RCG in Vasterbotten County, northern Sweden. A remote sensing method, using black and white orthophoto interpretation, was developed, by which abandoned fields with low preparation costs (on average 173 SEK (ha)-1) could be distinguished from fields with high preparation costs (on average 3990 SEK (ha)-1). Based on the assumptions made, RCG production would predominantly be viable in the coastal area of Vasterbotten County, and production equal to 1.3 TWh could be supplied at a farmgate fuel price of 116 SEK MW-1h-1. Pelletizing RCG allows it to be transported, stored and handled more easily. To determine the optimum conditions for RCG pelletizing, experiments were performed in an experimental design incorporating the factors: moisture content, steam addition, raw material density, and die temperature. Pre-compaction of the raw material was an efficient method for avoiding uneven pellet production. Through multiple response optimization, process settings were identified for the production of RCG pellets with a bulk density ≥ 650 kg m-3 and a durability ≥ 97.5%. To clarify the underlying mechanisms in the pelletizing process, the influences of moisture content and normal stress on the kinematic wall friction properties of RCG powder were studied. A steep increase in the kinematic wall friction with increasing normal stress was found in the normal stress interval 50-150 MPa. Multiple linear regression modelling of kinematic wall friction measurements at high normal stresses (65 to 376 MPa) revealed a local maximum at moisture contents of 13–16% and normal stresses of 150–225 MPa. Kinematic wall friction and pellet durability maxima occurred in overlapping moisture content ranges; it was, therefore, hypothesised that the two properties were correlated.

4 citations

Journal ArticleDOI
TL;DR: In this paper, a physically based model for the shock Hugoniot of a powdered material is described, which allows separate identification of the cold and thermal contributions to pressure and specific internal energy.
Abstract: A physically based model for the shock Hugoniot of a powdered material is described which allows separate identification of the cold and thermal contributions to pressure and specific internal energy. Special features of this model are provision for the effects of porosity on the stress state and an empirically determined cold loading contribution to pressure. The model was tested against published Hugoniot data for iron and gave excellent agreement for shock pressures ranging from low to high values. This shock Hugoniot was used to explore the shocked state of 4 samples of iron powder derived from commercially available material. The purpose of this study was to investigate the effect of powder particle characteristics and initial starting densities on the shocked state. The powder samples investigated had a range of morphologies and sizes. Powders with either a large shape factor or high internal friction, as determined in shear cell experiments, exhibited a higher stiffness in the cold loading curve. In the shocked state, this translated into a higher cold component of pressure and energy than found in the other powders. The effect of initial powder density was studied by applying the Hugoniot model to two impact initiated shock loadings, one for a stainless steel flyer impacting at 0.5 km/s and one at the higher velocity of 2.0 km/s. Both were applied to iron powder targets preloaded to a range of initial densities. For a given impact event, the proportion of shock energy in the thermal mode was found to decrease with increasing initial density. This decrease was more pronounced at higher shock strengths. As a result of the decreasing component of thermal energy with higher initial density, there was a reduction in the continuum temperature behind the shock. However, the corresponding increase in the component of cold energy with the falling relative contribution from the thermal energy lead to increasing density behind the shock suggesting that there is a trade off in terms of temperature and density achievable with a given impact event.

4 citations