Modeling of pyrolysis furnace producing ethylene

Molecular reaction schemes for the thermal cracking of ethane and propane have been derived from observed product distribution, radical mechanisms and thermodynamic principles. Molecular models were developed using two different approaches, equilibrium approach and kinetic approach. The models were implemented using the ASPEN PLUS process simulation program.; Since the reactions in commercial pyrolysis furnaces do not reach complete equilibrium, a restricted equilibrium approach was studied. Restrictions on the reactions were based on a trial and error analysis to match the product distribution from a commercial reactor. A good fit was obtained for the major components in the product stream, but not for the minor components.; Simple kinetic models of the cracking process were also developed. First, kinetic parameters obtained from the literature were used in these models. However, the results did not match the product distributions from commercial furnaces. Therefore, kinetic parameters were calculated using a nonlinear least-squares regression procedure. The product distributions for the models with regressed parameters were found to match the commercial data reasonably well. However, more industrial data at different operating conditions are needed to fully test the applicability of these models.