Flow reactors design equations

Develop a plug-flow-reactor design equation from the material balance. To properly size a reactor for this reaction and feedstock, a relationship between reactor volume, conversion rate of feed,... 

To carry out the integrations in the batch and plug-flow reactor design equations (2-9) and (2-16), as well as to evaluate the CSTR design equation (2-13), we need to know how the reaction rate —r varies with the concentration (hence conversion) of thereacting species. This relationship between reaction rate and concentration is developed in Chapter 3,... 

If both sides of the plug-flow reactor design equation (2-16) are divided by the entering volumetric flow rate and then the left-hand side is put in terms of space time, the equation takes the form... 

Rates were calculated using a plug-flow reactor design equation and the differential conversion of n-butane to each of the products. Activity decreases quickly within ten minutes and deactivates significantly more slowly for the remainder of the reaction up to one hour. Rapid deactivation followed by much slower deactivation on sulfated zirconia has been reported by several authors (9). 

Before one can obtain a numerical value for t from the integral form of the plug-flow reactor design equation, given by (22-27), it is necessary to focus on the dimensionless kinetic rate law, which could be rather complex. 

Solution. Write the tubular flow reactor design equation and substitute the rate expression. 

Example 1.4 Determine the reactor design equations for the various elementary reactions in a piston flow reactor. Assume constant temperature, constant density, and constant reactor cross section. (Whether or not all these assumptions are needed will be explored in subsequent chapters.)... 

Chapter 1 treated the simplest type of piston flow reactor, one with constant density and constant reactor cross section. The reactor design equations for this type of piston flow reactor are directly analogous to the design equations for a constant-density batch reactor. What happens in time in the batch reactor happens in space in the piston flow reactor, and the transformation t = z/u converts one design equation to the other. For component A,... 

Computational Scheme for Gas-Phase PFRs. A general procedure for solving the reactor design equations for a piston flow reactor using the marching-ahead technique (Euler s method) has seven steps ... 

Chapter 8 combined transport with kinetics in the purest and most fundamental way. The flow fields were deterministic, time-invariant, and calculable. The reactor design equations were applied to simple geometries, such as circular tubes, and were based on intrinsic properties of the fluid, such as molecular dif-fusivity and viscosity. Such reactors do exist, particularly in polymerizations as discussed in Chapter 13, but they are less typical of industrial practice than the more complex reactors considered in this chapter. 

Kinetic Rate Lam y/Vfateriat Balance reaction/deactivation/ reactor design equation, heat/mass transpat/ fluid-flow model,... 

Equating the time of passage through the tubular reactor to that of the time required for the batch reaction, gives the equivalent ideal-flow tubular reactor design equation as... 

The viability of one particular use of a membrane reactor for partial oxidation reactions has been studied through mathematical modeling. The partial oxidation of methane has been used as a model selective oxidation reaction, where the intermediate product is much more reactive than the reactant. Kinetic data for V205/Si02 catalysts for methane partial oxidation are available in the literature and have been used in the modeling. Values have been selected for the other key parameters which appear in the dimensionless form of the reactor design equations based upon the physical properties of commercially available membrane materials. This parametric study has identified which parameters are most important, and what the values of these parameters must be to realize a performance enhancement over a plug-flow reactor. 

All chemical reactors have at least one thing in common Chemical species are created or destroyed. In developing a general reactor design equation, we focus on what happens to the number of moles of a particular species i. Consider a region of space where chemical species flow into the... 

A batch reactor has no inlet or outlet flows, so n, o = = 0. Perfect mixing is assumed for this ideal reactor, and the rate r is independent of position. This changes our generation term in the general reactor design equation to... 

Dibular Flow Reactor (PFR). After multiplying both sides of the tubular reactor design equation (1-10) by -1, we express the mole balance equation for species A in the reaction given by Equation (2-2) as... 

The inherent difficulty in designing chemical reactors, which is due to two factors (i) Global reaction rates depend on the local flow conditions, which are not known a priori, and (ii) even when the global reaction rate expressions are known, solving the reactor design equations is a formidable task that rarely can be performed in the design exercise. 

Section 1.2 developed rate expressions for elementary reactions. These expressions are now combined with the material balances of Section 1.1 to develop reactor design equations, that is, equations to predict final concentrations in a batch reactor or outlet concentrations in a flow reactor. Since reaction rate expressions have units of concentration per time, it may seem that is identical to da/dt. This is true only for... 

Much study has been given to liquid-metal heat transfer in recent years, primarily in connection with its use in nuclear reactors. Design equations, all based on heat-momentum analogies, are available for flow in tubes, in annuli, between plates, and outside bundles of tubes. The equations so obtained are of the form... 

The outer wall of the double-pipe configuration at radius Routside is thermally insulated from the surroundings. Identify the acceptable range of the flow rate ratio parameter xj/ that corresponds to a well-behaved novel reactive system which does not exhibit thermal runaway. The appropriate reactor design equations are summarized in Table 4-6. 

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