Plug flow reactor assumptions

The trickle bed reactor allows for plug flow reactor assumptions even at extremely low liquid-flow rates. The trickle bed is classified as a continuous heterogeneous catalytic reactor. 

In a properly operated bubble-column reactor, the liquid phase can be considered to be perfectly mixed, i.e. concentrations in the liquid are the same everywhere and correspond to those in the effluent. The gas is supposed to flow like a piston, i.e. the reactor is a plug-flow reactor with respect to the gas. These two assumptions are not entirely true, but within a certain flow regime they are not far from the reality. 

The Plug Flow Reactor (PFR)—Basic Assumptions and Design Equations... 

Plug flow reactor Sometimes called a piston flow or a perfect flow reactor. The plug flow reactor has continuous input and output of material. The plug flow assumption generally requires turbulent flow. No radial concentration gradients are assumed. 

This reactor has continuous input and output of material through a tube. Assumptions made for the plug flow reactor (PFR) are (1) material passes through the reactor in incremental slices (each slice is perfectly mixed radially but has no forward or backward mixing between slices each slice can be envisioned as a miniature CSTR), (2) composition and conversion vary with residence time and can be correlated with reactor volume or reactor length, and (3) the reactor operates at steady state. 

Plug Flow Reactor. A PFR is a continuous flow reactor. It is an ideal tubular type reactor. The assumption we make is that the reaction mixture stream has the same velocity across the reactor cross-sectional area. In other words, the velocity profile across the reactor is a flat one. In a PFR there is no axial mixing along the reactor. The condition of plug flow is met in highly turbulent flows, as is usually the case in chemical reactors. 

These assumptions lead to the picture of the flow as that of a plug of fluidum with uniform properties being pushed through the tube. In a plug flow reactor the mass balance for a component A over an infinitesimal reactor element, as defined in Figure 7.1, gives ... 

Up to this point it has been assumed that the composition and the temperature are uniform throughout the complete reactor for perfect mixing, or within an infinitesimal volume element for plug flow. These assumptions usually hold for... 

A cooled plug flow reactor when axial dispersion is negligible, a usual assumption for tubular reactors with no mixing tr, tco, C [Pg.2999]

Generalized function mostly unit operations like continuous stirred tank reactor or plug flow reactor for react and distillation column or evaporator for separate" and also new combined operations assumptions are necessary due to lack of some data in advance calculations with linear mass- and energy balances short-cut methods ... 

Another first-order reaction is to be studied at the same flow rate in the vessel characterized in Prob. 6-12. Measurements for this reaction in a plug-flow reactor, operating at the same mean residence time, gave a conversion of 75.2%. (a) Calculate the value of the rate constant for this reaction. (6) Calculate the conversion expected for this reaction in the reactor of Prob. 6-12. (c) Are any assumptions made in obtaining the answer to part (b)l If the reaction were second order, would additional assumptions be necessary to use the same procedure for part (6) ... 

The plug-flow reactor (PFR) is a mathematical model that depicts a certain type of continuous reactor operation. The model is based on three assumptions ... 

In the preceding sections, we discussed the operation of plug-flow reactors with gas-phase reactions under the assumption that the pressure does not vary along the reactor. However, in some applications, the pressure significantly changes and, therefore, affects the reaction rates. In this section, we incorporate the variation in pressure into the design equations. For convenience, we divide the discussion into two parts tubular tube with uniform diameter and packed-bed reactors. 

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

The assumptions made in deriving (he design equation Tor a plug-flow reactor are ... 

Quantitative treatment of plug flow reactors is somewhat cumbersome, therefore several assumptions are usually made. The fluid composition is considered to be unform along the reactor cross section (i.e. there is no radial dispersion). This is valid only when... 

Ideal mixing and plug flow. The batch, contlnuous-stirred-tank, and plug-flow reactors are defined by certain idealized assumptions on the fluid flow. The batch and continuous-stirred-tank reactors are assumed to be ideally well mixed, which means that the temperature, pressure and species concentrations are independent of spatial position within the reactor. The plug-flow reactor describes a special type of flow in a itube in which the fluid.is well.mixed in the radial direction and varies... 

The reactor models presented in Chapters 4 7 were based on specific flow assumptions, such as the well-mixed reactor and plug flow reactors. Experimental reactors must retain these flow attributes if we wish to use the simple material balances for estimating model parameters. 

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