High pressure aeration

For hydrocarbons in high-pressure fractionators Strigle [82] reports there is aeration of the rather low surface tension liquid phase. This effect increases with the lower surface tension and as the vapor density increases, thus... 

High-purity High-pressure boilers De-aeration may be required BS 2486 1978... 

For some applications, notably feed-water treatment for high-pressure boilers, removal of oxygen is essential. For most industrial purposes, however, de-aeration is not applicable, since the water used is in continuous contact with air, from which it would rapidly take up more oxygen. Attention must therefore be given to creating conditions under which oxygen will stifle rather than stimulate corrosion. 

Leger and Mallet, 1988). When aminocarb was irradiated by a high pressure xenon-mercury lamp (). = 253.7 nm) in aerated and degassed ethanol and cyclohexene solutions, 4-(dimethylamino)-... 

Downcomer aeration factor prediction. The fractional liquid holdup varies from about 0.3 in the froth zone to close to unity in the clear liquid zone (Fig. 6.12a). The height of each zone is a complex function of system properties, operating conditions, and downcomer geometry. This makes it practically impossible to theoretically predict the average downcomer aeration factor <(>. . Correlations in the literature (e.g., 46) are based on limited data obtained in atmospheric pressure simulator work with small downcomers. It is therefore difficult to recommend them for commercial-size applications. Zuiderweg (17) presented a plot of downcomer aeration factors derived theoretically from commercial-scale high-pressure flood data. However, the plot is based on a handful of data and is therefore difficult to recommend for general aeration factor prediction. 

Pressurization could be carried out on the entire feed stream (full-flow pressure flotation) or a fraction of the feed stream while the remainder is introduced directly without aeration into the flotation tank (split-flow pressure flotation). The spht-flow system offers a cost saving over the full-flow units, since only a portion of the influent needs to be pressurized. In both cases, however, if the sohd particles in the feed stream are flocculated before introducing to the flotation tank, the high shear during pressurization, aeration, and pressure release can destroy the floes. Also, if the particle loading in the feed stream is high, both systems are susceptible to block e of the air release devices. To minimize these problems, recycle-flow pressure flotation is often practiced (Fig. 19-71). In this process, the feed stream, flocculated or otherwise, is introduced directly into the process vessel, and part of the clarified effluent is pressurized, aerated, and recycled to the flotation tank in which it is mixed with the flocculated feed. The air bubbles are released as they attach to the floes and float to the tank surface. The recycle-flow devices are found to offer the highest unit capacities. 

Okazaki and Shiga [15] further observed the effect of ESR transitions on the spin-adduct yield. They irradiated the de-aerated sample solution with a 500-W ultra-high-pressure mercury lamp and the X-band microwave for 30 s at 23 1 C. After a specified waiting time (1.0 min), they recorded the ESR spectrum of the spin adduct. They used a flow system to change the solution without changing the filling factor of the sample solution in the ESR... 

At high pressures, the difference between vapor and liquid density becomes smaller, and separation of vapor from liquid in the downcomer becomes difficult. Because of the more difficult separation, downcomer aeration increases, raising both downcomer frictional losses and froth backup in the downcomer. High liquid flow rates also increase tray pressure drop, tray liquid level, and frictional losses in the downcomer. For this reason, downcomer flooding is favored at high pressures and high liquid rates. 

Obviously, evaluation of such balanced distribution depends on the thermodynamical environment and the nature of formation fluids. With increase in pressure, temperature increases the role of chemical interactions. This is why in conditions of high pressures and temperature solution of the set task is substantially complicated. For example, we will limit ourselves to a case of low pressure and temperature, which occurs, for instance, in the aeration zone. 

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