Chapter 2: Conversion and Reactor Sizing

Example

Levenspiel Plots in Terms of Concentrations

For reactions in which the rate depends only on the concentration of one species [i.e., -rA = f(CA)], it may be convenient to report -rA as a function of concentration rather than conversion. We can rewrite the design equation for a plug-flow reactor

\( V = F_{A0} \int_{0}^{X} \frac{dX}{-r_{A}} \)

in terms of the concentration, CA, rather than in terms of conversion for the special case when v = v0. We develop and discuss the following equation for space time and the figure below.

Diagram showing a rectangular shape labeled 'Design equation' with arrows entering from the left and exiting on the right, indicating flow through the equation.     

\( \tau = \int_{C_{A}}^{C_{A0}} \frac{dC_{A}}{-r_{A}} \)

Graph with a curved line sloping downwards from C_A0 to C_A1 on the x-axis, and 1 over negative r_A on the y-axis. The shaded area under the curve represents the space time τ, calculated as τ equals the integral from C_A1 to C_A0 of dC_A over negative r_A.

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