Effect of Agitation Speed

Figure 4 Effect of agitation speed on reaction rate.

Figure 13.31. Effect of agitator speed on efficiency for the system acetone-xylene-ester ...

In a mixer-settler, the effect of agitation speed on the extraction or stripping... 

Fig. 10. Effect of agitation speed on cell concentration (A) and regeneration frequency (B) of rice calli in TBR without (o, ) and with (a, ) supports. Dotted lines show the results of the control culture...

Solution As an approximation assume that the effect of agitator speed on kiOg is the same as shown in Fig. 10-7 for solution of oxygen in aqueous solutions. The power input P will be approximately proportional to the 2.5 power of the stirrer speed N. Then the ratio of (P/IOn to P/I tso will be as follows ... 

In reactions involving gas-liquid mixing, one of the first things to determine is the controlling process (bulk) chemical reaction or mass transfer. Experimentally, this is done by checking the effect of agitator speed on rate of reaction, as shown in Figure 9.22. 

Several of the factors of Figure 3 controlling the activity and selectivity of the biphasic selective hydrogenation of ,/ -unsaturated aldehydes to allylic alcohols, for instance, 3-methyl-2-butenaldehyde to 3-methyl-2-buten-l-ol (Eq. 11) with rutheni-um-sulfonated phosphine catalysts were investigated [11], such as the effect of agitation speed and the influence of aldehyde, ligand, and metal concentrations. Under optimized reaction conditions, where gas-liquid mass transfer was not rate-determining, the kinetic equation (Eq. 12) was found to apply. A zero-order dependence with respect to the concentration of the ,/i-unsaturated aldehyde was found. 

The effect of agitation speed indicated that beyond 16.7,Hz the rate of hydroformylation was independent of agitation speed. This suggests that gas-liquid and liquid-liquid mass transfer effects can be eliminated beyond an agitation speed of 16.7, Hz, indicating kinetic regime. All the experiments for the kinetic studies were carried out at 16.7, Hz and at catalyst phase hold up of 0.4. The rate data for the purpose of kinetics is discussed below. 

Effect of Agitation Speed A few experiments were carried out at 333 K at various agitation speeds and the results are shown in Figure 3. For agitation speeds > 700 rpm, the initial rates were found to be unaffected by agitation indicating the absence of external mass transfer resistance at 333 K. 

FIGURE 3 EFFECT OF AGITATION SPEED ON INITIAL RATE OF REACION Catalyst loadiiig= 2.0 x 10 g/ciii Partial pressure of 11, = 6.8 atin... 

Fio. 9. Effect of agitation speed on rate of heparin degradation catalyzed by immobilized heparinase at T = 37°C, pH 7.4, E = 230 units/mL, and Cb = 0.1 mg/mL. Ratio of volume of fluid phase to volume of beads, 200 1. Each point is mean of 10 independent experiments [from Bernstein et al. (50)]. 

In this study, the effects of agitation speed and catalyst loading level on reaction rates were assessed at a constant hydrogen pressure of I.l bar. Debenzylation of both benzyl ether and N-phenylbenzylamine was carried out at 50°C, while that of... 

Figure 3 Effects of agitation speed on hydrogen uptake 10% benzyl ether in THE solvent, 50°C, 1.1 bar hydrogen, 5%Pd/CPS3. The activity value is based on the time required for 1.0 liter hydrogen consumption.

Figure 2.25 Effect of agitator speed on secondary nucleation rate for steel and plastic impellers. [From J.N. Ness and E.T. White (1976), Collision Nucleation in an Agitated Crystallizer, AIChE Symposium Series 72 (153), pp. 64-73. Used by permission of the American Institute of Chemical Engineers. 1976 AIChE.]...

Fig. 4. Effect of agitator speed on oxygen uptake and dissolved oxygen in 201 novobiocin fermentation with impellers of DJD, = 0A, apparent viscosity 300 cp air flow rate 5 slm lower probe ( ) opposite the lower impeller, behind a baffle upper probe (O) near liquid surface behind a bafile...

Manipulation of PSDs is generally attained through modification of surfactant concentrations (mostly in emulsion polymerizations) [48,49], agitation speeds (mostly in suspension polymerizations) [50], and initial catalyst size distributions and reaction times (residence time distributions in continuous reactors, mostly in coordination polymerizations) [51]. Effects of agitation speeds and surfactant concentrations on the PSD of polymer particles produced in suspension and emulsion polymerizations are discussed in detail in Chapters 5 and 6, respectively. When the catalyst is fed into the reactor as a solid material, as in typical polyolefin reactions, then the residence times and the initial PSD of the catalyst particles are used to manipulate the PSD of the final polymer product. Similar strategies are used in seeded emulsion polymerizations, where an initial load of preformed particles can be used to improve the control over the concentration of polymer particles in the latex and over the PSD of the final polymer product. 

At higher Froude numbers (>3), the mixing time is linear with mixer volume (not the diameter). The effect of agitator speed is significant in this range. 

Effects of Agitation Speed and Dissoived Oxygen in Xanthan Fermentations... 

In other polysaccharide fermentations such as alginate, curdlan, and pullulan gums, the effects of agitation speed and dissolved oxygen are more complex. Pena... 

Amanullah, A., R. Blair, C. R. Thomas, and A. W. Nienow (1999). Effects of agitation speed on mycelial morphology and protein production in chemostat cultures of recombinant Aspergillus oryzae, Biotechnol Bioeng., 62(4), 434-446. 

Figure 1 indicates the effect of agitation speed on the dissolution rate for the case of 0.1 [mol L ] sulfuric acid at different temperatures. From these results, it is obvious that the dissolution rate of limestone is controlled by liquid-phase mass transfer, because the rate is proportional to the 0.57... 

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