Sparged reactor vessel

Animal cells are more sensitive to shearing than micro-organisms because they have no cell wall. Therefore in many shearing investigations used animal cells. But unfortunately most of these investigations were carried out in laminar flow systems like viscosimeters and channels. As mentioned above (see Sect. 4.2), the relationships are not comparable to technical reactors such as sparged impeller vessels. 

Pre-reduced catalyst (typically 2 g) was added with 300 ml of 2,2,4-trimethylpentane (Lancaster Synthesis Ltd) to the reactor vessel. An in-situ reduction of the catalyst was performed by sparging H2 (280 cm3 min 1) through this mixture for 30 minutes while stirring at 800 rpm. During this time the vessel was heated to 328 K. The stirrer was then turned off. 

White liquor oxidation occurs under more severe reaction conditions than black liquor oxidation. Again, gas-liquid mass transfer is essential, and several reactor designs have been used for this purpose, including sparged stirred vessels, pipeline reactors (Thring et al., 1995), and buss loop reactors. 

Fusion Process. In the fusion process, also frequendy referred to as fusion cook, inert gas is continuously sparged from the bottom of the reactor to carry away water vapor from the reaction mixture. The exhaust is then either vented away or sent to a fume scmbber, which is frequendy a small vessel with water atomi2ing no22les. After the reaction is completed, the finished resin may be discharged, filtered, and packaged without solvent. More frequendy, it is cooled to a safe temperature, then dissolved in the desired type and amount of solvent in a thinning tank, filtered, and packaged, or pumped... 

In an airlift fermenter, mixing is accomplished without any mechanical agitation. An airlift fermenter is used for tissue culture, because the tissues are shear sensitive and normal mixing is not possible. With the airlift, because the shear levels are significantly lower than in stirred vessels, it is suitable for tissue culture. The gas is sparged only up to the part of the vessel cross section called the riser. Gas is held up, fluid density decreases causing liquid in the riser to move upwards and the bubble-free liquid to circulate through the down-comer. The liquid circulates in airlift reactors as a result of the density difference between riser and down-comer. 

Example 11.18 Consider a gas-sparged CSTR with reaction occurring only in the liquid phase. Suppose a pilot-scale reactor gives a satisfactory product. Propose a scaleup to a larger vessel. 

Hydrodynamics of slurry reactors include the minimum gas velocity or power input to just suspend the particles (or to fully homogeneously suspend the particles), bubble dynamics and the holdup fractions of gas, solids and liquid phases. A complicating problem is the large variety in reactor types (sec Fig. I) and the fact that most correlations are of an empirical nature. We will therefore focus on sparged slurry columns and slurries in stirred vessels. 

In activity tests, sections of the Zn composite were used as agitation paddles in a batch reactor and compared to granular zinc, which was loaded into a similar vessel with an inert agitator (Fig. 23). The reactors were charged with 1 L of water and sparged with nitrogen to remove dissolved oxygen. TCE was then added to a concentration of 1(X)0 ppm. A chloride selective electrode was used to monitor chloride ion formation as a function of reaction time. First order kinetics were assumed, and rate constants were calculated per mass of Zn. 

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