Thermodynamic Modeling of Gasoline Production Process through Thermal Cracking of Heavy Hydrocarbons

In this paper, equilibrium thermodynamics of thermal cracking of heavy hydrocarbons for gasoline production has been investigated. Equilibrium calculations have been performed using the Gibbs free energy minimization method. The dependence of products yield on the operating conditions including temperature (300-1200K), pressure (1-30atm) and the steam to feed ratio (0-0.5) has been studied. Results showed that increasing temperature has a positive impact on the production of gasoline. For instance, in a constant pressure of 1atm, increasing temperature from 500 to 800K led to increasing gasoline yields from 5.41% to 8.92%. This is due to the endothermic nature of thermal cracking of heavy hydrocarbons. However, with increasing pressure at constant temperature, the amount of gasoline production decreased. This circumstance represents the adverse effect of pressure on gasoline yield. Results depicted that with increasing steam ratio from zero to 0.5, gasoline yield declined 45%. It can be concluded that the optimum operating conditions for gasoline production through thermal cracking of heavy hydrocarbons is within a temperature range of 8001200K, the pressure range of 1-5atm and in the absence of steam.