Achieving stability under inaccessible conversions using CSTR cascades

Multiple steady states in an isothermal CSTR for reaction rates of the form R=kC/(1+KC)2 exhibit concentration multiplicity for a certain parameter range of the Damkohler number, Da. The unstable steady state of the above reaction rate form is very difficult to be observed and maintained. In this work the graphical solution method as proposed by Chen and Crynes (1987) is modified to attain a cascade of CSTRs that are capable of achieving this inaccessible steady state. The modified numerical scheme is based on optimization search. This method was successful in achieving the inaccessible steady state by two CSTRs cascade. The comparison with the graphical method showed that the modified method is faster and more accurate in solving the CSTR problem. The CSTR cascade gives better stability and tolerance to a probable control system failure.