Liquid gassed

FIG. 14-26 Entrainment correlation. L/G = liquid-gass mass ratio and P and Pg = liquid and gas densities. [Fair, PetyChem. Eng., 33(10), 45 (September... 

Figure 15.18 Power curves for shear-thinning liquid. Gassed power number versus Reynolds number at Qo = 0.5 and 1 vvm 10 < /te < 1100 DT,...

Impeller Reynolds number and equations for mixing power for particle suspensions are in Sec. 5. Dispersion of gasses into liquids is in Sec. 14. Usually, an increase in mechanical agitation is more effective than is an increase in aeration rate for improving mass transfer. 

This temperature increase can be detected by a sensor and the heat stored is thus called sensible heat. Sensible heat storage in most cases uses as storage materials solids (stone, brick,...) or liquids (water,...). Gasses have... 

Gasses due to their low heat capacity do not store and transport as much heat as similar volumes of a liquid. Therefore their low heat transfer coefficients are often not a special problem. From analytical model for a simple heat storage given previously, we know that the temperature of the heat transfer fluid on the outlet of the storage model was... 

Liquid cryogenic gasses like nitrogen or helium should always be handled in well ventilated places. When a liquefied gas container fails, for example, by a sudden leak due to mechanical damage, large amounts of gas may come free with the risk of asphyxiation and/or cold bums. 

Whereas in Gas Recycle the product must be removed at the same temperature and pressure at which it is formed, in Liquid Recycle the separation of product (and byproducts) from catalyst is independent of the conditions under which the products were formed. This added degree of control brings a variety of benefits. Since large gas flows are no longer required in the reactor, the liquid expansion due to gassing is reduced and more catalyst can be contained in a specific reaction vessel. Reactor temperature and reactant concentrations can be tuned for optimum catalyst performance. The conditions in the separation system can likewise be tuned for optimum performance. In particular, more severe conditions will permit better control over the concentration of heavies in the catalyst solution. 

The Eulerian gas velocity field required in both the mass balance and the above transport equation for nh is found by an approximate method first, the complete field of liquid velocities obtained with FLUENT is adapted downward because the power draw is smaller under gassed conditions next, in a very simple way of one-way coupling, the bubble velocity calculated from the above force balance is just added to this adapted liquid velocity field. This procedure makes a momentum balance for the bubble phase redundant this saves a lot of computational effort. 

The transfer hydrogenation methods described above are sufficient to carry out laboratory-scale studies, but it is unlikely that a direct scale-up of these processes would result in identical yields and selectivities. This is because the reaction mixtures are biphasic liquid, gas. The gas which is distilled off is acetone from the IPA system, and carbon dioxide from the TEAF system. The rate of gas disengagement is related to the superficial surface area. As the process is scaled-up, or the height of the liquid increases, the ratio of surface area to volume decreases. In order to improve de-gassing, parameters such as stirring rates, reactor design and temperature are important, and these will be discussed along with other factors found important in process scale-up. 

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