1 research outputs found
Modelling and simulation of an industrial RFCCU‑riser reactor for catalytic cracking of vacuum residue
A one-dimensional adiabatic mathematical model was developed for the riser reactor of an industrial residue fluid catalytic
cracking unit (RFCCU). A seven-lump kinetic model was presented for the catalytic cracking of vacuum residue, taking
cognisance of diffusion resistance, which is a departure from the general norm in the literature. Also, heat transfer resistance
between the fluid and solid phases was incorporated into the energy balances for instantaneous and one-dimensional
vaporization of feedstock. The developed model was a set of twelve coupled, highly non-linear and stiff ordinary differential
equations, ODEs, which was numerically solved with an implicit MATLAB built-in solver, ode23t, designed deliberately
for handling stiff differential equations to circumvent the problem of instability associated with explicit methods. An excellent
agreement was achieved between the industrial RFCCU plant data and the simulated results of this study, with average
absolute deviation being < ± 5% for instantaneous vaporization of feedstock in all cases investigated. Moreover, the simulated
results revealed that half of the reactor was relatively redundant as this accounted for only 3% of the conversion. Hence, the
findings of this study could be useful to the production practice for the Khartoum Refinery Compan