Plug adiabatic

AJ Isothermal—always use a plug flow reactor (Bj Adiabatic... 

Kinetic for Adiahalic or Non-adiabatic Plug-Flow Reacior Same as Case 1 n dV = - 1- AH,I — dV R - Same as Case 4 with km and K fTi... 

Adiabatic plug flow reactors operate under the condition that there is no heat input to the reactor (i.e., Q = 0). The heat released in the reaction is retained in the reaction mixture so that the temperature rise along the reactor parallels the extent of the conversion. Adiabatic operation is important in heterogeneous tubular reactors. 

If there is no heat exchange on passing the plug, i.e.f the process is adiabatic, as Joule and Kelvin assumed,... 

An ignition experiment at 1-butene concentrations as high as 5% was performed to test instability in reaction behavior as an indication of unsafe operation (5% 1-butene in air 0.1 MPa 400 °C) [103]. The degree of conversion increased linearly and converged without any sign of instability. The power input corresponded to 6.5 W with an adiabatic temperature rise of more than 2000 °C. Plugging, however, was the major concern under these severe conditions. 

For a single plug flow reactor optimum conditions for adiabatic operation are, obtained by varying the feed temperature so that the Average... 

Assume steady-state, adiabatic operation, and use the pseudohomogeneous, one-dimensional plug-flow model. 

The stirred reactor may be compared to a plug flow reactor in which premixed fuel-air mixtures flow through the reaction tube. In this case, the unbumed gases enter at temperature T0 and leave the reactor at the flame temperature T. The system is assumed to be adiabatic. Only completely burned products leave the reactor. This reactor is depicted in Fig. 4.50. 

For the plug flow reactor or any similar adiabatic system, it is also possible to define an average specific heat that takes its explicit definition from... 

The size of reactor needed for a given duty is found as follows. For plug flow tabulate the rate for various Xp along this adiabatic operating line, prepare the y -rp) versus Xp plot and integrate. For mixed flow simply use the rate at the conditions within the reactor. Figure 9.8 illustrates this procedure. 

Figure 9.8 Finding reactor size for adiabatic operations of plug flow and mixed flow reactors.

Figure 9.9 Best location for the adiabatic operating line. For plug flow, a trial and error search is needed to find this line for mixed flow, no search is needed.

Find the size of adiabatic plug flow reactor to react the feed of Example 9.5 (F q = 1000 mol/min and AO 4 mol/liter) to 80% conversion. 

EXAMPLE 9J ADIABATIC PLUG FLOW REACTOR WITH RECYCLE... 

Figure 19.10 Sketch showing why plug flow is used for steep adiabatic lines, and mixed flow (packed beds with large recycle) for lines with small slope.

In an adiabatic fixed bed, heat is not exchanged with the environment through the reactor wall. Note that for the derivation of eq. (5.226), it has been assumed that the flow is ideal plug flow and thus the radial dispersion term is eliminated in an adiabatic fixed bed, the assumption of perfect radial mixing is not necessary since no radial gradients exist. 

The Joule-Thomson experiment can be described as adiabatic expansion in a pipe through a porous plug, as pictured schematically in Fig. 3.11. 

Figure 3.11 Joule-Thomson porous-plug experiment, showing the initial state P, L, Tx (left) and final state Pf, Vf, 7> (right) of the gas as it passes reversibly through the porous plug under fixed pressures PA, Pf and adiabatic conditions.

The percent of adiabatic compression work that was being wasted across the partially plugged in-line filter basket was then... 

When an open system in steady flow undergoes an adiabatic process without performing external work, the enthalpy of the system regains its initial value at each equilibrium state, and the entropy increases as before. Example Successive, slow expansions through porous plugs P[. Py - (Fig. 2), when we have... 

Fig. 2. Successive, slow adiabatic expansions of gas through porous plugs.

The reactor system may consist of a number of reactors which can be continuous stirred tank reactors, plug flow reactors, or any representation between the two above extremes, and they may operate isothermally, adiabatically or nonisothermally. The separation system depending on the reactor system effluent may involve only liquid separation, only vapor separation or both liquid and vapor separation schemes. The liquid separation scheme may include flash units, distillation columns or trains of distillation columns, extraction units, or crystallization units. If distillation is employed, then we may have simple sharp columns, nonsharp columns, or even single complex distillation columns and complex column sequences. Also, depending on the reactor effluent characteristics, extractive distillation, azeotropic distillation, or reactive distillation may be employed. The vapor separation scheme may involve absorption columns, adsorption units,... 

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