Superficial steam plants

Other studies have indicated that nickel, which is incorporated into the superficial oxide layers on Incoloy 800 steam generator tubes, is present there in the form of neutral atoms. Schuster et al. (1988) analyzed contamination layers from different PWR plants using AES and XPS techniques their results showed, besides an almost homogeneous Co distribution over the whole thickness of the oxide layers, that they consist of a Cr-Fe spinel in which, with the exception of the uppermost regions (some nanometers), nickel is exclusively present in its atomic state and not as a chemically bound constituent of a nickel ferrite. The existence of Ni imder the conditions prevailing in the PWR primary circuit can be explained by thermodynamic causes. By analogy, it seems justifiable to assume that cobalt... 

The power of the Reynolds number at high superficial velocities has values between 0.5 and 1 in the literature. Many references use 0.75. This has also been found in the pilot plant in Figure 3.6, but the power decreases at very high loads [119]. The reason is probably a combined impact of the superficial mass velocity on the radial effective conductivity and the heat transfer coefficient at the tube wall emphasising the need for a fundamental description using CFD. Results shown by Dixon et al. in [160] [484] for steam reforming in narrow tubes are promising. 

Hydrodiffusion is a steam distillation method, whereby steam is fed to the plant material from the top. Steam penetrating the plant matrix condenses and forces the essential oil to diffuse to the surface. Because of gravity, oil leaves the vessel together with the condensate water from the bottom of the still. Powdering the material results in better oil yields. This technique is suitable both for superficial and subcutaneous oils. The disadvantage of this technique is the undesired extraction of coumarins, psoralens, and chlorophyll into the oil. Therefore, hydrodiffusion has not become a widely used distillation technique. 

---