The droplets that appear in annular gas‐liquid flows are formed by the eruption of wavelets from the surface of the wall layer. Ninety per cent of the volume of this dispersed liquid is carried by only about 10% of the drops. We find, as suggested by Wicks and Dukler, that the distribution of drop sizes can be characterized by an upper limit, log normal function with only one of the three parameters, the volume median diameter, a strong function of flow conditions. A method for predicting the average diameter is suggested which is consistent with a theoretical interpretation based on a Kelvin‐Helmholtz mechanism, whereby the destabilizing force is the pressure variation over the wavelets.
Major economic incentives exist for processing resid containing high levels of nickel and vanadium in catalytic crackers. The amount of resid which can be fed to current units is limited by the cracking catalyst's ability to rapidly deactivate the deposited metals and thus prevent excessive coke and gas formation. Development of more metals-tolerant cracking catalyst would be aided by knowledge of the behavior of nickel and vanadium on the surface of cracking catalyst. Toward this goal, we have investigated the behavior of these metals on a commercially available cracking catalyst. It has been found that nickel can occupy several types of sites on the cracking catalyst surface. Different metal-impregnation compounds and techniques can influence which sites are occupied. Some nickel sites were found to be more active for coke and gas production than others. Vanadium was found to interact with nickel in a manner which inhibits the deactivation behavior of nickel. This result indicates that metals-resistant cracking catalyst must be evaluated in the presence of both nickel and vanadium.
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