Dense-phase pneumatic conveying: A review
TL;DR: In the last twenty years, several commercial systems for dense-phase pneumatic conveying have been developed as mentioned in this paper, however, despite an extensive literature, the subject is very confusing, particularly for the beginner.
About: This article is published in Powder Technology.The article was published on 1986-12-01. It has received 113 citations till now.
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TL;DR: In this paper, Lagrangian-type numerical simulation was carried out on plug flow of cohesionless, spherical particles conveyed in a horizontal pipe and the motion of individual particles contacting each other was calculated using the equations of motion and a modified Cundall model.
1,608 citations
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20 May 2005
TL;DR: In this paper, Brownian Dynamics for the Simulation of Granular Flows is used to simulate the simulation of granular flows in a dynamical model with event-driven molecular dynamics.
Abstract: Molecular Dynamics.- Event-Driven Molecular Dynamics.- Direct Simulation Monte Carlo.- Rigid-Body Dynamics.- Cellular Automata.- Bottom-to-Top Reconstruction.- Brownian Dynamics for the Simulation of Granular Flows.
617 citations
TL;DR: The boundary between fast fluidization and dilute-phase pneumatic transport is set by the type A choking velocity, at which the uniform suspension collapses and particles start to accumulate in the bottom region of the transport line as mentioned in this paper.
293 citations
TL;DR: In this paper, a case study outlining the principles of measuring the mass flow rate of solids in a vertical channel is shown, along with various levels of visualization and processing of tomographic data obtained in a pilot plant-scale pneumatic conveying system.
Abstract: Transient three-dimensional multiphase flows are a characteristic feature of many industrial processes. The experimental observations and measurements of such flows are extremely difficult, and industrial process tomography has been developed over the last decade into a reliable method for investigating these complex phenomena. Gas-solids flows, such as those in pneumatic conveying systems, exhibit many interesting features and these can be successfully investigated by using electrical capacitance tomography. This paper discusses the current state of the art in this field, advantages and limitations of the technique and required future developments. Various levels of visualization and processing of tomographic data obtained in a pilot-plant-scale pneumatic conveying system are presented. A case study outlining the principles of measuring the mass flow rate of solids in a vertical channel is shown.
172 citations
TL;DR: The emphasis is given to the modelling of key phenomena such as flow regimes and transition, pipe wear, particle attrition, and electrostatics in the gas-solid flow characteristics and process performance over a broad range of conditions.
144 citations
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TL;DR: The behavior of solids fluidized by gases falls into four clearly recognizable groups, characterized by density difference (ϱs −ϱf) and mean particle size as discussed by the authors, and a numerical criterion which distinguishes between groups A and B has been devised and agrees well with published data.
3,007 citations
TL;DR: In this paper, the interaction between a turbulent wind and the motion of uniform saltating grains of sand or soil, so massive as to fail to enter into suspension, is examined on the basis of two complementary hypotheses.
Abstract: The interaction between a turbulent wind and the motion of uniform saltating grains of sand or soil, so massive as to fail to enter into suspension, is examined on the basis of two complementary hypotheses. The first asserts that the effect of the moving grains on the fluid outside the region to which saltation is confined is similar to that of solid roughness of height comparable with the depth of the saltation layer. The second requires the concentration of particles engaging in the saltation to adjust itself so that the shear stress exerted by the wind on the ground—different from that acting on the fluid outside the saltation layer by an amount accountable to the change in horizontal momentum suffered by the particles in their passage through the fluid—is just sufficient to maintain the sand-strewn surface in a mobile state.Existing experimental data on the wind profiles outside the saltation region and the horizontal flux of particles through it are shown to be consistent with these hypotheses.The second hypothesis implies a self-balancing mechanism for controlling the concentration of saltating particles. For if the concentration is too low the shear stress at the surface rises above the value required merely to secure mobility and more particles are encouraged to leave the surface; conversely, too large a concentration depresses the surface stress, and the consequent loss of surface mobility inhibits saltation and reduces th concentration of particles until equilibrium is restored.
1,051 citations
TL;DR: In this article, an experimental study has been made of the motion of long bubbles in closed vertical tubes and the influence of viscosity and surface tension on the bubble velocity is clarified.
Abstract: An experimental study has been made of the motion oflong bubbles in closed
tubes. The influence of viscosity and surface tension on the bubble velocity is
clarified. A correlation of bubble velocities in vertical tubes is suggested and is
shown to be useful for the whole range of parameters investigated. In addition,
the effect of tube inclination angle on bubble velocity is presented, and certain
features of the flow are described qualitatively.
351 citations
TL;DR: In this article, a 3-inch diameter riser 30 feet in length using solids ranging in particle Reynolds number from 100 to 3500 was studied in vertical pneumatic conveying.
Abstract: Vertical pneumatic conveying was studied in a 3-inch diameter riser 30 feet in length using solids ranging in particle Reynolds number from 100 to 3500. Particle to gas mass flow ratios varied from 0 to 8 and pipeline conditions extended from dilute flow down into the choking region.
Average particle hold-up was determined by means of a series of quick-closing valves and particle slip velocity was often found to be greater than the calculated terminal velocity. The reasons for this are examined.
Frictional pressure losses in the riser were also determined and compared with literature data. The phenomenon of choking is considered briefly.
On a etudie le transport pneumatique et vertical, dans un tuyau de 30 pieds de longueur et 3 pouces de diametre, en utilisant des matieres solides dont les nombres de Reynolds des particules variaient entre 100 et 3500. Les rapports d'ecoulement entre les particules et le gaz variaient de 0 a 8 et les conditions dans le tuyau se sont etendues d'un ecoulement dilue a la region d'engorgeinent.
On a determine la retention moyenne des particules, au moyen d'une serie de soupapes qui fermaient rapidement, et l'on a souvent trouve que la velocite de glissement etait plus elevee que la velocite terminate qu'on avait calculee; on en analyse les raisons.
On a aussi determine les pertes de pression dues a la friction dans le tuyau et les a comparees avec les donnees publiees. On considere brievement le phenomene d'engorgement.
145 citations