Whirling process

Fluid-Elastic Coupling Fluid flowing over tubes causes them to vibrate with a whirling motion. The mechanism of fluid-elastic coupling occurs when a critical velocity is exceeded and the vibration then becomes self-excited and grows in amplitude. This mechanism frequently occurs in process heat exchangers which suffer vibration damage. 

Important for polymer processing is the fact that when the concentration of a hard filler is increased in the composite, the unsteady flow (in the sense of large-scale distortions) of the extrudate occurs at higher shear rates (stresses) than in the case of the base polymer [200, 201,206]. Moreover, the whirling of the melt flow is even suppressed by small additions of filler [207]. 

Convective bulk transport is also an extremely important factor in the suspension of solids in a stirred tank (this is also responsible for the flow pattern at the tank bottom). P/V cannot be used as a scale-up criterion in this process either. Measurements have shown that the minimum rotational speed, ncrit, of the stirrer which is necessary for the suspension (whirling-up) of particles in the turbulent regime is given by the appropriate Froude number ... 

Blowdec A process for converting waste plastics into diesel fuel. The plastic is injected into a bed of hot whirling sand. Developed in Slovakia from 1997. 

To remedy the fault, Nazi experts first rub the diamond with genuine eau-de-Cologne and, while still damp, placing it in very fine sawdust where it is whirled in a rubber-lined container or shaker, driven by mechanical means, until the proper degree of brilliance and lustre is restored. The process ends with a final polishing with a specially prepared chamois leather. The treatment costs from one hundred to one thousand Reichmarks, and takes the best part of three months to complete, according to the deterioration in the gem that has taken place.65... 

The Blowdec depolymerization process from Slovakia converts waste plastics into low-sulphur diesel fuel [35]. The main principle is the processing of waste plastics in a hot whirling bed of hot sand in the BLOWDEC reactor (Figure 15.19). The plastic is heated to 430°C. The process allows for simultaneous cracking of hydrocarbons and inhibition of coke formation. The fluidized sand bed products three types of cracking reactions mechano-activation thermal and catalytic (Si02/aluminosilicates). The process is covered under the US Patent 6,165,349. The process enables the economical conversion of mixed waste plastics into liquid hydrocarbons, mainly low-sulphur (25 ppm) diesel... 

Water in Dust Settlement.—In nearly every case where water can be used it has a beneficial effect. It is of much assistance in the Cottrell process of dust settlement to be described later. The more finely divided the water, the less need be the amount used but that the effect is somewhat independent of the quantity, that is that a large quantity in bulk will do effective work is shown by the experiments of Iles. Jets of water were allowed to flow down through a tin box with slightly inclined alternate shelves so as to give the water a tortuous course. From 90 to 95 per cent of the smoke and fume was collected from the gas ascending the box. Humidifying can be accomplished by nozzles or by centrifugal apparatus, which whirls the water into an impalpable mist. 

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