Bed frequency of oscillation

The bed frequency of oscillation, f, can be calculated from the time of the upswing motion, T, and the time of the downswing motion, T, where ... 

Figure 23. Effect of drum speed on bed frequency of oscillation for a drum without lifters.

The slurry bed within the drum was found to oscillate. The bed frequency of oscillation was found to be a strong function of the drum rotational speed. A mathematical model was developed to predict the bed frequency of oscillation. The model predictions were in reasonable agreement with the experimental measurements. 

D Mean particle size, mm F Bed frequency of oscillation, s Solids mass flow rate, kg/s Fr Froude number for slurry flow in the drum, V/[2 g R (Ss - 1) ] Fr, Modified Froude number for pipe... 

It can be observed that N2O decomposes and consequently O2 is stoichiometrically produced, but both N2O and O2 outlet concentrations oscillate in a quite regular way after about one hour from the start and during about one day of run. Moreover, the average values of N2O and O2 outlet concentrations have been respectively increasing and decreasing in the first 800 minutes and stabilise The frequency of the oscillations of N2O outlet concentration is about 30 minutes, i e at least four order of magnitude greater than the residence time, while their maximum amplitude is about 100 ppm It is worthwhile to point out that the catalytic bed temperature axially measured is always constant in the whole experiment ( 0 1 C)... 

On the other hand, the major frequency / of spontaneous oscillation of the system composed of the plenum chamber capacity, the distributor resistance, and the bed inertia, particularly when the distributor resistance is small, is given by (Moritomi et al., 1980)... 

In the inertial microbalance, the mass located at the tip of an oscillating tapered quartz element is detected as a change in its vibrational frequency. The design of this equipment provides a packed bed of catalyst through which all the gas is forced to flow, and the classical methods of testing for differential operation in an ideal plug-flow fixed-bed reactor can therefore be applied. 

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