Velocity Consecutive

CALCULATE DIFFERENCE BETWEEN VELOCITIES IN CONSECUTIVE ITERATIONS... 

Dehydration of ethanol has been effected over a variety of catalysts, among them synthetic and naturally occurring aluminas, siUca-aluminas, and activated alumina (315—322), hafnium and 2irconium oxides (321), and phosphoric acid on coke (323). Operating space velocity is chosen to ensure that the two consecutive reactions. 

A truck carr) ing two tanks containing a very unstable and hazardous gas is involved in an accident that results in tlie consecutive explosion of the tanks -one innncdiately, the second approximately a minute later. The total mass of tlie emission resulting from the explosion of each tank is 30,000 g. The wind velocity is 1 m/s from the north, and tlie effective height of emission is 30 meters at the time of tlie accident. Calculate the concentration of tliis gas at 500 meters south but 100 meters east from the site 10 minutes after tlie explosion of tlie first tank. Assume tliat stability category D applies. 

Fig. 6. Dependence of relative molar concentrations Wj/nA0 of reaction components on reciprocal space velocity W/F (hr kg mole-1) in the consecutive demethylation of m-xylene. Temperature 330°C, catalyst Ni-AljOs (55% wt. AljOs), initial molar ratio of reactants 0 = 5. The curves were calculated (1—xylene, 2—toluene, 3—benzene) the points are experimental values.

The design methods de.scribed above rely on correlations of the overall reactor average quantities obtained from experimental tanks of different scales. The most important deficiency of these methods is that local effects are not taken into consideration, while these might be responsible for the overall reactor performance. Accordingly, if none of the above scale-up criteria is found satisfactory (see e.g. data of Middleton et ai, 1986) a more fundamental approach must be applied, although not necessarily as complex as the one presented in Section 5.4.S.2. Such an approach was presented by Paul et al. (1971) who found that the yield of the desired intermediate in a system of consecutive reactions (iodination of L-tjrosine) correlates reasonably with fluctuations of the velocity, So, these fluctuations could be chosen as a criterion for scale-up of the reactor. The average value for u in the upper part of the tank was evaluated from ... 

Fig. 5.1.6 These images display the three components of velocity in five consecutive slices through the transverse cross section of the capillary. The direction of bulk flow is from slice 1 to 5 with each slice 300-pm thick and contiguous. Positive axial velocity is out of the page. A negative x component represents flow...

V average molecular velocity for competitive consecutive reactions... 

Catalyst Activity Measurements. Activity measurements for thiophene HDS and the consecutive hydrogenation of butene were carried out in a Pyrex-glass, fixed-bed reactor at 625 K and at atmospheric pressure as described in Ref. (9). Before the measurements the catalysts were presulfided in 2% H2S in H2 at 675 K. For each catalyst conversions were measured at different space velocities of the thiophene/H2 mixture (2.5 thiophene) and the catalytic activities are here expressed as pseudo first-order rate constants as-... 

FIGURE 11.8 Several consecutive frames of FCC catalyst in the bed region of a 6 inch (15 cm) diameter fluidized bed at a superficial gas velocity of 2 ft/sec (0.61 m/sec). Images were collected at 4000 frames per second with a 20 xs exposure time. 

In his experiment the piston underwent several velocity increments, thus propagating a series of consecutive small shock waves thru the medium, each succeeding wave having higher velocity than the one in front of it. Eventually then, the waves all catch up with the first one. The result is a disturbance of finite amplitude with a very steep front. The last of these diagrams (c), represents the front as a discontinuous change in pressure in real substances, the processes of diffusion and heat conditions make this impossible, and a finite pressure slope is maintained. 

Again, since the velocity of a reaction is proportional to the amount of the reacting substances present in the system, the second reaction will be the slowest at the start, and gradually become faster. The speed of formation of the iodine is therefore the resultant velocity of two consecutive reactions and the belated appearance of the iodine—the period of induction—corresponds with the time required for the first reaction to make enough hydriodic acid to enable the second reaction to make sufficient iodine to colour the starch. 

The time of return can itself be made the criterion of success, by forgetting about the B region and counting two consecutive crossings of S as independent transitions if and only if they are separated by a time interval greater than some characteristic time To, e.g. the autocorrelation time of the velocity normal to... 

The catalytic hydrogenation of linoleic esters has also been treated kinetically by Boelhouwer et al,88. If the velocity constants of the consecutive reactions are represented by kx and k2 and first order kinetics are assumed, the following equations hold ... 

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