Bubble small

In stirred-slurry reactors, momentum is transferred to the liquid phase by mechanical stirring as well as by the movement of gas bubbles. Small particles are used in most cases, and the operation is usually carried out in tank reactors with low height-to-diameter ratios. The operation is in widespread use for processes involving liquid reactants, either batchwise or continuous— for example, for the batchwise hydrogenation of fats as referred to in Section II. 

Voids in material Fine bubbles Small bubbles randomly in part Large voids Moisture in system Pouring technique Dirty mold High exotherm Casting technique Dirty molds Mold design... 

The aerated stirred vessel has been widely operated in chemical industries. The aim of gas-liquid mixing is to make the bubbles small in order to accelerate the mass transfer between the gas and the liquid. In the case of gas-liquid mixing, the gas that flows out from a sparger is trapped once by the impeller and then discharged as bubbles. The mixing state of the gas-liquid mixing is classified into three states ... 

The phenomenon of very diluted solutions is well known in radiochemistry. Carrier-free radioactive isotopes could be mentioned as an example. The term denotes a radioisotope of an element in pure form, that is, essentially undiluted, with a stable isotope. The chemical concentration of these radioisotopes is usually very low. For example, 1 kBq radioactivity (applied typically in a tracer experiment) is equivalent to cca. 2 10 12 mol in the case of 137Cs or 90Sr isotopes. In the case of such low concentrations, no chemical system can be considered homogeneous because all surfaces, the wall of the laboratory vessels, or any contaminants in the solution (such as air bubbles, small particles, great molecules, etc.) can initiate interfacial processes and the subsequent formation of heterogeneous phases (adsorption, colloid formation, precipitation, etc.). This is the result of the simple fact that the number of molecules on the surfaces is more than, or at least similar to, the number of particles in the solution. Even in a solution containing... 

Gelatin capsules are manufactured by a dipping pro-cess. The process starts by the preparation of a concentrated solution of gelatin or other suitable polymer in hot demineralized water. This solution is subjected to a low pressure to remove entrapped air bubbles. Small aliquots of this solution are (20-30 L) are taken. To this are added colorants, either solutions of soluble dyes or suspensions of pigments, preservatives, process aids, such as disodium lauryl sulfate solution, and water to adjust the viscosity. The final solution has a concentration of 25-30 wt%o of gelatin. This solution is then delivered to the capsule-manufacturing machine. 

First melt morphology -many large gas bubbles -small gas bubbles... 

The dotted curve corresponds to solid bubbles. It was obtained by recalculations from experiments on spherical glass balls with a density of 2.37 g/m. Significant surfactant effects appear for large bubbles. Small bubbles rise as solid spheres, even in thoroughly cleaned liquids from a = 0.03 cm (Re = 36) and at c > lO M up to a = 0.065 cm (Re = 182). It is typical that even at such low concentrations as lO M the velocity of bubbles is essentially decelerated. 

If the polydispersity of bubbles is high, the process of particle recovery is performed by a two-stage flotation even without an additional introduction of centimicron bubbles. Small bubbles mostly capture particles and large bubbles mostly coalesce with small bubbles. The capture process is useful and a high rate of the coalescence process can be disturbing. Indeed, it leads to... 

With two capacitance probes positioned at a known separation distance (as in a fluidized bed), the velocity of the solids phase interface can be determined by measurement of a disturbance such as a bubble. Small probes can be designed to be used within the system or mounted flush with the walls and may include a... 

The embryos that trigger vapor formation in a superheated liquid are microscopic bubbles small regions where the density is smaller than in the bulk. To calculate the rate of homogeneous nucleation in a superheated liquid according to the classical theory, one must therefore consider the energetics of bubble formation. The contents of vapor embryos can be treated as an ideal gas except near the critical point. Let P be the pressure inside the critical nucleus. Then, P being the bulk pressure in the superheated... 

As for other particle flocculators, the power is derived from the drag force on the rising bubbles. Small bubbles will rise in a laminar regime (Stokes). 

The correlation in Eq. (31) is recommended for use in the Reynolds number range 20potential flow result in Eq. (30). Even the minute amounts of surfactant present in tap water are sufficient to immobilize the surface of bubbles small enough to be approximately spherical. The upper Reynolds number range for the correlation in Eq. (31) roughly coincides with the largest Reynolds number for which one might expect contaminated bubbles to be approximately spherical. 

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