Particles pneumatic transport

Gases carrying solid particles wholly or partly in suspension ( pneumatic transport ). 

In the riser tube, the gas velocity of chlorine, is greater than both of the terminal velocities of the slag particle and the petrocoke particle, makes the particles to be at a pneumatic transport state. No agglomeration occurs in the riser tube. At the top of the riser tube, a... 

Pneumatic and hydraulic conveying, in which the solid particles are transported along a pipeline in suspension in a fluid, are discussed in Volume 1, Chapter 5, and in a book by Mills (2003) see also Mills et al. (2004). 

Either a liquid or a gas can be used as the carrier fluid, depending on the size and properties of the particles, but there are important differences between hydraulic (liquid) and pneumatic (gas) transport. For example, in liquid (hydraulic) transport the fluid-particle and particle-particle interactions dominate over the particle-wall interactions, whereas in gas (pneumatic) transport the particle-particle and particle-wall interactions tend to dominate over the fluid-particle interactions. A typical practical approach, which gives reasonable results for a wide variety of flow conditions in both cases, is to determine the fluid only pressure drop and then apply a correction to account for the effect of the particles from the fluid-particle, particle-particle, and/or particle-wall interactions. A great number of publications have been devoted to this subject, and summaries of much of this work are given by Darby (1986), Govier and Aziz (1972), Klinzing et al. (1997), Molerus (1993), and Wasp et al. (1977). This approach will be addressed shortly. 

One major difference between pneumatic transport and hydraulic transport is that the gas-solid interaction for pneumatic transport is generally much smaller than the particle-particle and particle-wall interaction. There are two primary modes of pneumatic transport dense phase and dilute phase. In the former, the transport occurs below the saltation velocity (which is roughly equivalent to the minimum deposit velocity) in plug flow, dune flow, or sliding bed flow. Dilute phase transport occurs above the saltation velocity in suspended flow. The saltation velocity is not the same as the entrainment or pickup velocity, however, which is approximately 50% greater than the saltation velocity. The pressure gradient-velocity relationship is similar to the one for hydraulic transport, as shown in... 

Yang, W. C., and Keaims, D. L., Estimating the Acceleration Pressure Drop and the Particle Acceleration Length in Vertical and Horizontal Pneumatic Transport Lines, Pneumotransport 3, pp. D7-89 (1976a)... 

Fluidized Bed Tests. These tests have direct relevance to all applications where particles are subjected to conditions of fluidization. Some authors believe that these tests can also to some extent simulate the stress of pneumatic transport. Coppingeretal. (1992) found at least a good correlation with the attrition resistance in dense-phase pneumatic conveying when they tested various powders in a slugging fluidized bed. 

Cabrejos, F. J., and Klinzing, G. E., Minimum Conveying Velocity in Horizontal Pneumatic Transport and the Pickup and Saltation Mechanisms of Solid Particles, Bulk Solids Handling, 14(3) 541-550 (1994)... 

When a chemical reaction occurs in the system, each of these types of behavior gives rise to a corresponding type of reactor. These range from a fixed-bed reactor (Chapter 21-not a moving-particle reactor), to a fluidized-bed reactor without significant carryover of solid particles, to a fast-fluidized-bed reactor with significant carryover of particles, and ultimately a pneumatic-transport or transport-riser reactor in which solid particles are completely entrained in the rising fluid. The reactors are usually operated commercially with continuous flow of both fluid and solid phases. Kunii and Levenspiel (1991, Chapter 2) illustrate many industrial applications of fluidized beds. 

M. Halstensen, S. de Silva, K.H. Esbensen, Acoustic monitoring of pneumatic transport lines - from noise to information, KONA Powder and Particle, 16, 170-178 (1998). 

When the particles reach the bottom of the collection plate they fall into a hopper for subsequent evacnation into a collection device snch as a dumpster or are pneumatically transported to a storage silo for storage and disposal. Because of their fine natnre, these particles are not typically reintroduced into the FCCU for rense. 

The probability of the formation of polymer agglomerates is appreciably increased by electrostatic interactions. This phenomenon is, inter alia, also known in the handling of polymer powders. Owing to the fact that the polymer particles are not electrically conductive, electrostatic charging occurs in pneumatic transport systems in an... 

J. Li, D.J. Mason, A computational investigation of transient heat transfer in pneumatic transport of granular particles, Powder Technol. 112 (2000) 273-282. 

The adhesion of colloidal particles to solid substrates is of fundamental and technological importance (e.g. pneumatic transport of powders, printing, filtration, detergency, air pollution). In general,... 

For pneumatic transport of solids in a dilute suspension, the effects of apparent mass, Basset force, diffusion, and electric charge of the particles may be ignored. Thus, the dynamic equation of a small particle in a gas medium is given by... 

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