Effluent composition

Ca plug flow)- the case where the effluent composition is fixed instead of the reactor size. Equations 8-152 and 8-154 can be manipulated to show that for small Dg /uL,... 

The material balance around the riser requires the reactor effluent composition. Two techniques are used to obtain this composition. Both techniques require that the coke yield be calculated. 

In specifying effluent treatment processes, two specifications are used in conceptual design. The simplest case is where the concentration at the outlet of an effluent treatment process is specified to be a fixed value. Targeting with a fixed outlet concentration is illustrated in Figure 26.39a. The effluent composite curve is first constructed. The outlet concentration for the effluent treatment is specified and the slope of the treatment line pivoted around this value until the treatment line pinches with the effluent composite curve. The slope of the line will then dictate the minimum treatment flowrate. 

In order to moderate the thermal effects associated with the reaction, large quantities of steam are usually injected with the butene feed. Steam/butene ratios of 10 to 20 are typical of the conditions employed in many industrial reactors. If equilibrium is achieved within the reactor, determine the effluent composition corresponding to the conditions enumerated below. 

If one has a feed stream containing these gases in stoichiometric proportions (H2/CO = 2) at 200 atm and 275 °C, determine the effluent composition from the reactor ... 

What are the reactor effluent composition and conditions Are any chemical separation steps or physical operations required in order to bring the effluent to a point where it is satisfactory for the desired end use ... 

What is the final effluent composition from a network of such reactors (We might also require the composition of the stream leaving each reactor.)... 

For a first-order reaction, we showed that for a cascade composed of equal-sized reactors, equation 8.3.42 governed the effluent composition from the nth reactor. 

If the initial condition of the reactor contents is known and if the feedstream conditions are specified, it is possible to solve equation 8.6.1 to determine the effluent composition as a function of time. The solution may require the use of material balance relations for other species or a total material balance. This is particularly true of variable volume situations where the following overall material balance equation is often useful. 

Hence the area under the curve of y versus CA multiplied by the ratio of stoichiometric coefficients represents the overall change in valuable product concentration between the inlet and outlet streams in a plug flow reactor or in a batch reactor. For the case of a CSTR the instantaneous yield is evaluated at the effluent composition, and the corresponding equation is... 

The effluent composition is readily obtained by writing a material balance on each species and solving the resultant set of equations. Hence,... 

The feed stream consists of A dissolved in a solvent S such that the initial concentration of A is 2 kmoles/m3. If 50% of the A fed to a flow reactor undergoes reaction, determine the effluent composition ... 

This same result can also be obtained by considering the response of the effluent composition from a CSTR to a step function change in input concentration and using equation 11.1.4 to determine F(t). 

Equations 11.1.33 and 11.1.39 provide the basis for several methods of estimating dispersion parameters. Tracer experiments are used in the absence of chemical reactions to determine the dispersion parameter )L this value is then employed in a material balance for a reactive component to predict the reactor effluent composition. We will now indicate some methods that can be used to estimate the dispersion parameter from tracer measurements. 

The design q>roblem can be approached at various levels of sophistication using different mathematical models of the packed bed. In cases of industrial interest, it is not possible to obtain closed form analytical solutions for any but the simplest of models under isothermal operating conditions. However, numerical procedures can be employed to predict effluent compositions on the basis of the various models. In the subsections that follow, we shall consider first the fundamental equations that must be obeyed by all packed bed reactors under various energy transfer constraints, and then discuss some of the simplest models of reactor behavior. These discussions are limited to pseudo steady-state operating conditions (i.e., the catalyst activity is presumed to be essentially constant for times that are long compared to the fluid residence time in the reactor). 

Consequently the integration limits are from (tM, C ) = (4t, 3.242 or 1.672) to [0, Cexlt). Results are shown in the second table for several starting values of t, and appear to be quite insensitive to those values. The second figure also shows that quite different starting values result in essentially the same effluent composition. 

Example 10-4 MCFC Effluent Composition - Ignoring the Water Gas Shift Reaction... 

Example 10-6 SOFC Effluent Composition - Accounting for Shift and Reforming Reactions... 

Inlet Composition (lb mols/hr) Effluent Composition (lb mols/hr) Effluent Composition (mol fraction)... 

A pulse test procedure [6] begins with an injection of a small pulse of the feed mixture to be separated into a desorbent stream flowing through a packed adsorbent column at a fixed flow rate and temperature. The on-line column effluent composition is then determined as a function of time or volume of desorbent passed by gas or liquid chromatography. Particularly important is the sequence and time when each of the feed components exit the packed adsorbent column because these characteristics describe the specific adsorbate and adsorbent interactions. By determining the interactions using the pulse test, the separation process can be optimized. 

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