Hydraulic transport

In the hydraulic transport of solids through steel pipelines, inhibitors of the sodium-zinc-phosphate glass type have been shown" to be effective. In the case of coal slurries the polyphosphate type was rejected because the de-oxygenating action of the coal lowered the inhibitor effectiveness. Hexavalent chromium compounds at 20 p.p.m. were more effective". ... 

Liquids mixed with solid particles ( hydraulic transport ). 

There were several studies of hydraulic transport in the 1950s, sparked off particularly by an interest in the economic possibilities of transportation of coal and other minerals over long distances. Newitt et al.p2) working with solids of a range of particle sizes (up to 5 fim) and densities (1180-4600 kg/m3) in a 25 mm diameter pipe, suggested separate correlations for flow with a bed deposit and tor conditions where the particles were predominantly in heterogeneous suspension. 

In Volume 2, the drag coefficient C D(= Cp/2) is used in the calculation of the behaviour of single particles. However, C0 is used in this Chapter to facilitate comparison with the results of other workers in the field of Hydraulic Transport. 

The sensitivity of the pressure drop to the coefficient of solids-surface friction /j.f may well account for the wide scatter in the results shown earlier in Figure 5.10. Unfortunately this quantity has been measured by only very few investigators. It must be emphasised that in the design of any hydraulic transport system it is extremely important to have a knowledge of the coefficient of friction. 

There have been several studies involving the use of media consisting of fine dense particles suspended in water for transporting coarse particles. The fine suspension behaves as a homogeneous fluid of increased density, but its viscosity is not sufficiently altered to have a significant effect on the pressure drop during turbulent flow, the normal condition for hydraulic transport. The cost of the dense particles may, however, be appreciable and their complete separation from the coarse particles may be difficult. 

Chhabra. R. P. In Civil Engineering Practice, Volume 2, Cheremisinoff, P. N., Cheremisinoff, N. P. and Cheng, S. L. eds (Technomic Pub. Press PA, 1988). Hydraulic transport of solids in horizontal pipes. 

Z.ANDl. I. (cd) In Advances in Solid-Liquid Flow in Pipes and its Applications. Hydraulic Transport of Bulky Materials (Pergamon, Oxford, 1971). 

Durand, R, and Condolios, E. Proceedings of a Colloquium on the Hydraulic Transport of Coal, National Coal Board, London (1952), Paper IV. The hydraulic transportation of coal and solid materials in pipes. 

Khan, A. R PIRIE, R. L. and Richardson, J. F. Chem. Eng. Sci. 42 (1987) 767. Hydraulic transport of solids in horizontal pipelines — predictive methods for pressure gradient. 

Al.-SAl.lHt, I.. Ph.D. Thesis, University of Wales (1989). Hydraulic transport of coarse particles in vertical pipelines. 

Explain the various mechanisms by which particles may be maintained in suspension during hydraulic transport in a horizontal pipeline and indicate when each is likely to be important. 

Hydraulic transport, vertical flow 1.96, 210 Hydrocyclones 55 Hygrometer 758... 

Bavarian and Fan [3, 4] reported a similar phenomenon occurring in a three-phase fluidized bed. In their case, the hydraulic transport of a packed bed occurred at the start-up of a gas-liquid-solid fluidized bed. Although the cause was different from the case reported in the present study, similar phenomena were observed in both cases. 

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... 

Fig. 15-4, except that transport is possible in the dense phase in which the pressure gradient, though quite large, is still usually not as large as for hydraulic transport. The entire curve shifts up and to the right as the solids mass flux increases. A comparison of typical operating conditions for dilute and dense phase pneumatic transport is shown in Table 15-1. 

McKay, G., Murphy, W.R. and Jodieri-Dabbaghzadeh, S., Fluidisation and hydraulic transport of carrot pieces, ]. Food Eng, 6 (1987) 377-399. 

A.G. Bain and S.T. Bonnington, The Hydraulic Transport of Solids by Pipeline, Pergamon, New York, 1970. 

Vlasak P., Buchtelova M. (1979), Contemporary trends of development of hydraulic transportation in the world. In Hydraulic transport of materials through pipes. CSVTS,... 

Although atrazine has a soil half-life of 30-90 days, transport out of this zone into receiving waters leads to longer half-lives [101]. For pesticides with high water solubilities, such as atrazine, tributary inputs can be a major source, and environmental response to sources is controlled by long hydraulic residence times and slow transformation rates. Despite the fact that only 1% of the applied atrazine is lost by transport to rivers and lakes, and another 1% by aerial transport, the large quantities applied, together with efficient hydraulic transport result in accumulation in aquatic systems. 

P. Marjanovic, M. Sasic, Hydraulic transport of ash in thermopower stations, Proceedings of the 4th Yugoslav Thermal Symposium, Belgrade, Yugoslavia, 1975 (in Serbian). 

M. Sasic, P. Marjanovic, On the methods for calculation of hydraulic transport and their reliability in practice. Part 1, Proceedings of the 5th International Conference on Hydraulic Transport of Solids in Pipes, vol. 1, Hanover, Germany, 1978, pp. A5 61-A5 76. 

P. Maijanovic, I. Vuskovic, L. Bodiroga, Hydraulic Transport of granular activated carbon in water refinery plant, Symposium on Water Supply, Belgrade, Yugoslavia, 1987 (in Serbian). 

The tailings from the various flotation stages of an industrial separation process can be combined and hydraulically transported by pipeline ([90,606], see also Section 10.2). Sometimes the tailings pipelines are dose to the separation plants, and therefore are of modest length, but it is not uncommon for such pipelines to extend for several tens of kilometres to a settling basin. 

Stephens, H.S. Gittins, L. (Eds.) Proc. 7th Int. Conf. Hydraulic Transport of Solids in Pipes, BHRA Fliud Engineering Cranford, U.K., 1980. 

Horsley, R.R. Reizes, J.A. The Effect of Zeta Potential on the Head Loss Gradient for Slurry Pipelines with Varying Slurry Concentrations, in Proc. 7 Int. Conf. Hydraulic Transport of Solids in Pipes, Stephens, H.S. Gittins, L. (Eds.), BHRA Fliud Engineering Cranford, U.K., 1980, pp. 163-172. 

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