Stationary-state relationship and flow diagram

The stationary-state composition has dimensionless concentration ass and Pss satisfying the simultaneous equations 

Adding these gives a simple linear relationship between the two concentrations  

A number of points need to be made about this result. First, unlike the similar relationship (6.11), eqn (6.50) only applies at the stationary state. Secondly, the numerator really contains two contributionsrthe inflow of B, as P0, and the amount of A that has been converted to B, as 1 — ass. The denominator then shows that the stationary-state concentration of the autocatalyst is always less than this. Of course this shortfall between the amount of B present in the reactor and that which has flowed in or been produced merely.reflects the number of such molecules which have then reacted further to produce C. Thus, the denominator increases as the rate 

To obtain a single stationary-state equation, we now substitute for /Sss, from (6.50) into (6.48), giving 

In the flow diagram, Fig. 6.13, the reaction rate curve R is still given by the simple cubic 

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