The pyrolysis technique is a prime method for production of olefins in the petrochemical industry today. Due to the rapidly growing demand for propylene, there may be a need for processes producing propylene independently from ethylene. Isobutane is an attractive feedstock for cracking because isobutene is also produced in addition to propylene. Isobutene and methanol react to form methyl tert-butyl ether (MTBE). It is an important oxygenated gasoline with a high octane number. At present the market requirements of MTBE are skyrocketing as a result of environmental consciousness. The molecular structure of isobutane tends to produce high yield of propylene and isobutene among most of hydrocarbon feedstocks. This paper deals with a mathematical model of the cracking reactor. In the model, isobutane reaction kinetics, material/energy balance of cracked gases, heat transfer mechanisms such as radiation in the cracking furnace, heat conduction and convection of tube, pressure drop across the tubular reactor are all considered. The model leads to a set of nonlinear ordinary differential equations, including thirteen cracked-gas mass balances plus overall energy and pressure drop differential equations. By means of the model, we are able to solve and predict product distribution in the exit coil numerically. In addition, we can take advantage of this model by selecting proper operating parameters and thus obtain optimal product yields.
中國化學工程學會會誌=Journal of the Chinese institute of chemical engineers 27(2)，頁79-89