Plug-flow reactor modeling

The results confirm that the adsorption of ammonia is very fast and that ammonia is strongly adsorbed on the catalyst surface. The data were analyzed by a dynamic isothermal plug flow reactor model and estimates of the relevant kinetic parameters were obtained by global nonlinear regression over the entire set of runs. The influences of both intra-particle and external mass transfer limitations were estimated to be negligible, on the basis of theoretical diagnostic criteria. 

A similar spatial mean velocity (bulk mean velocity) is used for the plug flow reactor model. Thus, plug flow with dispersion is a natural match, where the mixing that truly occurs in any reactor or environmental flow is modeled as dispersion. This is the model that will be applied to utilize dispersion as a mixing model. 

Plug Flow Reactor. The plug flow reactor model requires only a residence time tf). So, the tracer cloud is used to determine tp. 

The plug flow reactor model predicts that there will be 1 % of the trichloroethylene remaining at the bottom of the stripping tower. 

To describe the reactor behavior, a simplified isothermal dispersed plug-flow reactor model was used. The well-known mass balance of this model for steady-state conditions can be formulated as [14, 15] ... 

In addition to these experiments, a simplified isothermal 1-D dispersed plug-flow reactor model of the membrane reactor was used to carry out theoretical studies [47]. The model used consisted of the following mass balance equations for the feed and sweep sides ... 

Again, the simple isothermal 1-D plug-flow reactor model provides a good basis for quantitative descriptions. This model allows to explore the potential of using series connections of several membrane reactor segments. The corresponding mass balance for a component i and a segment k can be formulated as follows ... 

Fig. 12.18. Comparison of the optimized reduced amounts that should be dosed and the corresponding internal compositions for a fixed-bed reactor (discrete dosing, top) and a membrane reactor (continuous dosing, bottom). A triangular network of parallel and series reactions was analyzed using an adapted plug-flow reactor model, Eq. 48. One stage (left) and 10 stages connected in series (right) were considered. All reaction orders were assumed to be 1, except for those with respect to the dosed component in the consecutive and parallel reactions (which were assumed to be 2) [66].

Most commonly, distributed parameter models are applied to describe the performance of diesel particulate traps, which are a part of the diesel engine exhaust system. Those models are one- or two-dimensional, non-isothermal plug-flow reactor models with constant convection terms, but without diffusion/dispersion terms. 

Yield-Based Reactor Fractional Conversion Reactor Combined Specification Model Well-Stirred Reactor Model Plug Flow Reactor Model Two Phase Chemical Equilibrium General Phase and Chemical Equilibrium... 

A one-dimensional pseudohomogeneous plug flow reactor model assuming isothermality was used to simulate experimental results. The continuity and kinetic expressions used were as follows ... 

Example 9.11 Modeling of a nonisothermal plug flow reactor Tubular reactors are not homogeneous, and may involve multiphase flows. These systems are called diffusion convection reaction systems. Consider the chemical reaction A -> bB described by a first-order kinetics with respect to the reactant A. For a nonisothermal plug flow reactor, modeling equations are derived from mass and energy balances... 

A plug-flow reactor models the conventional plug-flow behavior, assuming radial mixing but no axial dispersion. The reaction kinetics must be specified, and the model has the same limitations as the CSTR model. 

Different orders of deactivation will be used in the modeling. A simplification will be that the activity function for all components is the same. Using the reaction scheme given in figure 2 and the reaction rates as described by equation 1, in combination with a plug flow reactor model, mass balances can be derived for the different lumped groups, resulting in ... 

Plug Flow Reactor Model for Mixed-Phase Reactor... 

In practice, the fluid velocity profile is rarely flat, and spatial gradients of concentration and temperature do exist, especially in large-diameter reactors. Hence, the plug-flow reactor model (Fig. 7.1) does not describe exactly the conditions in industrial reactors. However, it provides a convenient mathematical means to estimate the performance of some reactors. As will be discussed below, it also provides a measure of the most efficient flow reactor—one where no mixing takes place in the reactor. The plug-flow model adequately describes the reactor operation when one of the following two conditions is satisfied ... 

The underlying assumptions of the plug-flow reactor model and when they are satisfied in practice... 

Let us consider a two-dimensional system for the fuel cell similar to a plug flow reactor model. 

In the previous examples, we have exploited the idea of an effectiveness factor to reduce fixed-bed reactor models to the same form as plug-flow reactor models. This approach is useful and solves several important cases, but this approach is also limited and can take us only So far. In the general case, we must contend with multiple reactions that are not first order, nonconstant thermochemical properties, and nonisothermal behavior in the pellet and the fluid. For these cases, we have no alternative but to solve numerically for the temperature and species concentrations profiles in both the pellet and the bed. As a final example, we compute the numerical solution to a problem of this type. 

Plug flow is a simplified and idealized picture of the motion of a fluid, whereby all the fluid elements move with a uniform velocity along parallel streamlines. This perfectly ordered flow is the only transport mechanism accounted for in the plug flow reactor model. Because of the uniformity of o>nditions in a cross section the steady-state continuity equation is a very simple ordinary differential equation. Indeed, the mass balance over a differential volume element for a reactant A involved in a single reaction may be written ... 

The Plug Flow Reactor Model Basic Assumptions and Design Equations... 

The chromatographic bed can be described by discrete equilibrium stages or by a plug-flow reactor model. 

Plug flow reactor models must be constructed with a frame of reference in mind. An observer riding along on the tracer slug would see no change in concentration over the modeled time and could infer nothing about the reactor. 

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