CARBON DEPOSITION IN ETHANE PYROLYSIS REACTORS

Carbon deposition during ethane pyrolysis in INCONEL 600 reactors exhibits a bimodal distribution along reactor walls. This indicates a shift in controlling mechanism from heterogeneous to homogeneous carbon formation. Carbon deposition rate decreases with the total pyrolysis running time until it reaches an asymptotic level. It increases with the number of pyrolysis-decoking cycles. Contrary to the INCONEL 600 reactors, alpha-SiC tubes produce little carbon deposition during ethane pyrolysis. The bell-shaped carbon distribution curve suggests the dominance of pyrolytic carbon formation mechanism in alpha-SiC reactors. Reactor model simulations show that both radial velocity and radial temperature distributions have significant effects on carbon deposition within the metal reactor system. This effect is not as important for the alpha-SiC reactor because the reactor wall is noncatalytic.