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** Time constant of reaction for batch reactors **

** Time, reaction, in a batch reactor concentration profile of species **

Fig. 2.4 Time histories of Ca (continuous line), Cpi (dotted line), and Cp2 ( dashed line) in a batch reactor for parallel reactions of A producing Pi, via an equilibrium limited reaction, and P2, via an irreversible reaction. Initial conditions are Cao = 1 molm-3, |

Figure 1. Monomer concentrations with Figure 2. Variation of monomer ratio reaction time in a batch reactor. Key with reaction time in a batch reactor. |

This example illustrates the use of the design equations to determine the volume of a batch reactor (VO for a specified rate of production Pr(C), and fractional conversion (/A) in each batch. The time for reaction (0 in each batch in equation 12.3-22 is initially unknown, and must first be determined from equation 12.3-21. [Pg.301]

For the PFR the expressions for these quantities are the same as given in Chapter 1 for the batch reactor with no volume change, with the time of reaction given by the residence time in the reactor. For product B of a Type II reaction [Pg.282]

For the case where all of the series reactions obey first-order irreversible kinetics, equations 5.3.4, 5.3.6, 5.3.9, and 5.3.10 describe the variations of the species concentrations with time in an isothermal well-mixed batch reactor. For series reactions where the kinetics do not obey simple first-order or pseudo first-order kinetics, the rate expressions can seldom be solved in closed form, and it is necessary to resort to numerical methods to determine the time dependence of various species concentrations. Irrespective of the particular reaction rate expressions involved, there will be a specific time [Pg.324]

This example shows that t and r are not, in general, identical. Now which is the natural performance measure for reactors For batch systems Chapter 3 shows that it is the time of reaction however, holding time does not appear anywhere in the performance equations for flow systems developed in this chapter, Eqs. 13 to 19, while it is seen that space-time or does naturally appear. Hence, r or V/F o is the proper performance measure for flow systems. [Pg.110]

The rate equations of Chapter 1 were given, for the most part, as they pertain to homogeneous batch reactions. While the purpose there was to treat descriptive kinetics, the results obtained pertain also to the operation of homogeneous batch reactors. One of the features of such a reactor was said to be that all the molecules in the reactor at a given time of reaction had been there for the same amount of time in other words, they had the same age. A second feature implied in the treatment was the intimate association, on a molecular scale, of all species contained in the reactor. [Pg.231]

To derive the overall kinetics of a gas/liquid-phase reaction it is required to consider a volume element at the gas/liquid interface and to set up mass balances including the mass transport processes and the catalytic reaction. These balances are either differential in time (batch reactor) or in location (continuous operation). By making suitable assumptions on the hydrodynamics and, hence, the interfacial mass transfer rates, in both phases the concentration of the reactants and products can be calculated by integration of the respective differential equations either as a function of reaction time (batch reactor) or of location (continuously operated reactor). In continuous operation, certain simplifications in setting up the balances are possible if one or all of the phases are well mixed, as in continuously stirred tank reactor, hereby the mathematical treatment is significantly simplified. [Pg.751]

The introductory example may be reworked using the Gamma distribution, since the special case given there is n = 1. Let c(x, 0) = Cogn( ) where C0 is the total initial concentration. Let the first order rate constant be k(x) = kx and make time dimensionless as kt. This reaction time or intensity of reaction—severity of reaction as the oil people have it—is really the Dam-kohler number, Da, for the reactor, with t the time of reaction if it is a batch reactor or the residence time if a PFTR. Thus [Pg.214]

** Time constant of reaction for batch reactors **

** Time, reaction, in a batch reactor concentration profile of species **

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