Nozzle mixers

V-mixer - comparison with conventional nozzle mixer... 

M 39][P 37] Using an azo-type competitive reaction, the selectivities were compared for the V-type micro mixers and conventional nozzle mixers with and without internals as a function of a specific power parameter [122,123], Considerably lower amounts of consecutive products, indicative of good mixing, are formed. All mixers show increasing mixing efficiency on enhancing the power. 

Results of calculations (Figure 9) show that the concentration variance increases with increases in both the power input for mixinge and the molecular weight ratio of the species. The cross-diffusion effects can affect the process of particle production only in the case of fast mixers (e.g., nozzle mixers), characterized by extremely large values of the rate of energy dissipation. It should be noted particle nucleation is very sensitive to supersaturation (Section 5) and... 

In 1989, the steam-water power reactor concept was presented by Alekseev and colleagues working in the former USSR [16]. The use of steam-water mixture for the reactor cooling is a key feature of the concept. There are two versions of the steam-water mixture preparation and distribution system. In one, the steam is supplied externally by steam blowers to the RPV and it mixes with feedwater in the special nozzle mixers set at the fuel assembly inlet. In the other, the steam is circulated in the RPV by jet pumps. The steam-water mixture is prepared in the jet pumps. The diagram of the steam-water power reactor is shown in Fig. B.24 [3]. There is no description on the feasibility of steam-water mixture generation. The plant system is indirect cycle. The primary pressure is 16.0 MPa. The core inlet and outlet temperatures are 347 and 360°C, respectively. The core inlet quality is 40%. The average void fraction of the core is estimated to be 93%. The core average coolant density is estimated to be 0.14 g/cm. It should be pointed out that the technical and safety problems will be similar to those of the steam cooled FBR. 

Liquid should be direc ted into the batch materials and not onto bare mixer surface since this could cause buildup. Nozzle spray pressure should be sufficient to penetrate the batch but not so high as to cause heavy splashing. The hquid should be added to the well-mixed... 

Bubble Reactors In bubble columns the gas is dispersed by nozzles or spargers without mechanical agitation. In order to improve the operation, redispersion at intei vals may be effected by static mixers, such as perforated plates. The liquid may be clear or be a slurry. 

FIG. 27-33 Inspirator (gas-jet) mixer feeding a large port premix nozzle of the flame retention type. High-velocity gas emerging from the spud entrains and mixes with air induced in proportion to the gas flow. The mixture velocity is reduced and pressure is recovered in the ventnii section. (F om North Ameiioan Comhnstion Handbook, 3d ed., Notih American Manufacturing Company Cleveland 1996. )... 

P 5] Layers of 4,4 -bipyridyl (0.3 mol 1 in dichloromethane), ethyl bromoacetate (0.3 mol in dichloromethane) and a separation layer of dichloromethane were fitted into each other by means of a concentric separation mixer (three-fluid nozzle with three tubes having diameters of 1.5, 3 and 4 mm, slotted into each other) [78]. Thereby, two circular liquid layers of a thickness of 200 pm and a center stream of 1.5 mm diameter were generated. The reaction temperature was 22 °C. The reaction solution was inserted as droplets or a continuous stream either directly or via... 

All the driers discussed above are unsuitable for mixtures with a high liquid proportion (slurries). For such mixtures spray driers (see Fig. 7.2-11) or cyclone driers (see Fig. 7.2-12) are effective. In the former the sluri-y is injected into the drier by a nozzle that atomizes the suspension. Small droplets fall down countercurrently to the hot gas that rises in the conical drier zone. In cyclone driers the sluriy and the hot gas flow cocurrently. Driers of both kinds are characterized by short residence times. Therefore, they are particularly suitable for temperature sensitive products. A significant proportion of driers of all kinds, appropriately modified, can also be operated as solids mixers and/or granulators. 

Figure 7.8 Rapid-mixing rapid-freezing apparatus.Two syringes (2) are filled with a solution of enzyme and substrate, respectively. By applying a large force (I) on the syringes, the solutions are driven into the mixer (3) whereafter the reaction starts.The reaction mixture flows through a reaction hose (4) and is then sprayed via a thin nozzle (5) in a funnel filled with cold isopentane (—I40°C). This causes a rapid (Sms) quenching of the reaction.The frozen powder is subsequently collected in an EPR tube attached to the funnel (6) and then is ready for EPR measurements.The funnel and EPR tube are held in a dewar with isopentane (—l40°C).The reaction time can be varied by changing the length and diameter of the reaction hose.

As previously mentioned, plant personnel were successful at mitigating the black streaks with the use of static mixers positioned inside the injection nozzle. Since the degraded resin was soft and leathery, it was easily broken into smaller particles as they passed through the mixer. Thus, the particles were not eliminated they were just reduced in size such that they did not create as many black streaks. The additional pressure and time that was required to inject the resin through the static mixers and into the mold, however, increased the cycle time to an unacceptable level. Although static mixers can be used to mitigate these types of problems, they do not eliminate the root cause of the degradation problem. 

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