Reactor Calculations

Here, since the measurements were done in an integral reactor, calculation must start with the Conversion vs. Temperature function. For an example see Appendix G. Calculation of kinetic constants starts with listed conversion values as vX and corresponding temperatures as vT in array forms. The Vectorize operator of Mathcad 6 tells the program to use the operators and functions with their scalar meanings, element by element. This way, operations that are usually illegal with vectors can be executed and a new vector formed. The v in these expressions indicates a vector. 

Source Fogler, H. S., 1974. The Elements of Chemical Kinetics and Reactor Calculations— A Self-Paced Approach, Prentice-Hall, Inc., Englewood Cliffs, NJ... 

Ethylene is to be converted by catalytic air oxidation to ethylene oxide. The air and ethylene are mixed in the ratio 10 1 by volume. This mixture is combined with a recycle stream and the two streams are fed to the reactor. Of the ethylene entering the reactor, 40% is converted to ethylene oxide, 20% is converted to carbon dioxide and water, and the rest does not react. The exit gases from the reactor are treated to remove substantially all of the ethylene oxide and water, and the residue recycled. Purging of the recycle is required to avoid accumulation of carbon dioxide and hence maintain a constant feed to the reactor. Calculate the ratio of purge to recycle if not more than 8% of the ethylene fed is lost in the purge. What will be the composition of the corresponding reactor feed gas ... 

This volume is appreciably larger than the volume of plug flow reactor calculated in Illustration 8.3 for the same reaction conditions and fraction conversion. However, the cost of such a reactor would be considerably less than the cost of a tubular reactor of the size determined in Illustration 8.3. 

Assuming that the reactions occur at constant Tin a constant-volume batch reactor, calculate ... 

Reactor calculations could relate to the fractional conversion of solid and the time for replacement of a given amount of solid (bed weight) to ensure that the outlet gas composition is within specifications. Such calculations are complicated by the unsteady-... 

The concentration readings in Table Ell.l represent a continuous response to a pulse input into a closed vessel which is to be used as a chemical reactor. Calculate the mean residence time of fluid in the vessel t, and tabulate and plot the exit age distribution E. 

A lipase from Rhizomucor miehei is immobilized onto a porous polyamide support with a bead diameter of 0.3 mm and used for the hydrolysis of 100 mM caprylin at pH 7.0 and 30°C, in a continous plug flow reactor. Calculate the amount of immobilized lipase needed to achieve a conversion degree of 97% with an inlet flow rate of 1 l.min ... 

Fio. 1.21. Continuous stirred-tank reactors calculation of unit output... 

The conversion in 1 hr is 65% in a batch reactor. Calculate (1) the rate constant and specify the rate equation, (2) the time at which the rate passes through the maximum, and (3) the type of optimum reactor system needed for the plant to process 200 m3/hr. What would be the reactor volume in this system ... 

Reactor Model. The design of an industrial packed-bed reactor requires a reactor model as well as the chemical and the heat and mass transfer parameters of the catalyst bed - gas stream system. Since these parameters are model-specific, it seemed advisable to employ a continuum model for the reactor calculation. This is the only model to date for which the literature contains consistent data for calculating heat and mass transfer parameters (5,6,7). This model in its... 

Typical reactor calculations would take about five times the average particle time constant t. For these cases the approximate relations were used to predict some of the reactor conditions as a function of time. To give an idea of the dependence of the computation time and accuracy on the time increment, At, three different cases are compared in Table III. 

A particular case of flow nonuniformity is inherent to all randomly packed tubes (Fig. 8). This is due to the fact that the catalyst pellets make only point contact with the wall, whereas they overlap and cross over one another inside the packing, thereby reducing the free volume and hence the velocity. The conditions for a spherical packing are illustrated schematically in Figure 8. The radially varying empty space distribution and velocity distribution must be taken into account in detailed reactor calculations, as well as in the determination of accurate heat transport parameters [17, 18]. This will be addressed in the next section. 

Provided the particle settling velocities vt are known, this equation allows the calculation of )e,s Usually, experiments at non-zero liquid rates are used to evaluate t , and )e,s separately. A similar concentration profile might occur in practice if slurry column reactors are operated close to the conditions given by the minimum suspension criterium. In this case, reactor calculations should take the solids concentration profiles into account. A recommended correlation for the solids dispersion coefficient for small particles is given by Kato et al. [15] ... 

Typical range values for plasma parameters in rf diode and high density reactors, (calculation is done for a CF4 plasma assuming Maxwell-Boltzmann distributions)... 

J. Kjaer, Computer Methods in Catalytic Reactor Calculations, Haldor Topsoe, Vedaek 1972. 

Two possible calculations can be used to determine the volume of the denitrification reactor calculation in which denitrification is allowed to occur in the same tank where nitrification is also occurring and calculation in which denitrification is done in a separate tank or in a separate portion of the same tank as in the oxidation ditch reactor. Where denitrification and nitrification occurs in the same tank, the process is a batch process, an example of which is the sequencing batch reactor (SBR). 

CO and C02 were always present in the product gas steam from pyrolysis whenever steam was used as diluent in the feedstream to metal reactors. Calculations indicated that, in general, approximately l%-5% of the steam reacted with coke to form carbon oxides and hydrogen. These values are significantly higher than the values obtained in commercial reactors that have much smaller surface-to-volume ratios than do the tubes used in the present investigation. Based on the results of the present investigation there were, however, some cases in which the metal surfaces... 

The process is to be designed for a 95% overall conversion of propane. The reaction products are separated into two streams the first, which contains H2, C3H6, and 0.555% of the propane that leaves the reactor, is taken off as product the second stream, which contains the balance of the unreacted propane and 5% of the propylene in the first stream, is recycled to the reactor. Calculate the composition of the product, the ratio (moles recycled)/(mole fresh feed), and the single-pass conversion. 

One hundred mol/h of butane (C4Hio) and 5000 mol/h of air are fed into a combustion reactor. Calculate the percent excess air. 

A. CDP1-Ab Batch Reactor Calculations A Hint of Things to Come... 

The concentrations of the individual species, CAit) and Cp(f), in the different globules are determined from batch reactor calculations. For a constant-volume batch reactor, where q reactions are taking place, the coupled mole balance equations are... 

Derive the E t) function for turbulent flow in a tubular reactor. Calculate the conversion if an elementary isomerization occurs. The specific reaction rate is k =0.1 s the centerline velocity is 10 dm/s, and the reactor length is 100 dm. = 10 dm. 

Oxygen at 21°C and 1 atm with 80% relative humidity is supplied to a biotech reactor. Calculate ... 

The cyclohexane vapors are condensed, separated by distillation, and recycled in the process. Three volumes of hydrogen are recycled for every volume of feed stock, which consists of cyclohexane containing 5 mol % benzene. To initiate a design for the reactor, calculate standard heat of reaction per g mol of CeHu. 

Fooler The Elements of Chemical Kinetics and Reactor Calculations A Self-Paced Approach Himmelblau Basic Principles and Calculations in Chemical Engineering, 5th edition Holland Fundamentals and Modeling of Separation Processes Absorption, Distillation, Evaporation, and Extraction... 

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