There is a constant increase in the demand for petroleum products including gasoline
due to the increasing population and advances in technology. The Fluid Catalytic
Cracking Unit (FCCU) has played a major role in gasoline production, which has made
it an important area of research. This study presents the simulation of FCCU using a
modified five-lump kinetic model for the description of the catalytic cracking of heavy
oil (HO) into light cycle oil (LCO), gasoline (GA), light gas (LG) and coke (CK) using
Kaduna Refining and Petrochemical Company's (KRPC) FCCU as a case study. The
cracking of HO in the riser-reactor was simulated as instantaneous vapourisation with
a quasi-steady-state dynamic. The heat transfer resistance considered negligible in past
works, was accounted for based on the temperature difference between the catalyst and
gas. The mass transfer resistance was taken into cognisance in the continuity equation
of the riser-reactor. A thorough description of the hydrodynamic model, momentum
and energy balances, was presented with the former comprising the hydrostatic head of
the catalyst, the solid acceleration, solid and gas frictions in the riser reactor, as against
the general norm in the literature. The resulting stiff ODEs were solved numerically
using the MATLAB-R2019a bulti-in routine, ode23tb, to determine salient process
variables investigated. Sensitivity analyses were carried out to determine optimal
conditions considering the change in catalyst-to-oil ratio (COR) and catalyst
temperature ( cat T ) using MINITAB-2017. The separator and regenerator were
modelled inclusive of the dense and dilute beds of the regenerator. KRPC data was used
to validate the simulated results, which gave the yields as HO-17.85%, LCO-14.95%,
GA-50%, LG-16.73% and CK-5.13%, with %error of < ±3 for HO, LCO, GA, and
CK, while it gave 6.43% for LG. The best-optimised condition was given at COR=3.35
and cat T =900K. At this condition, the yield of GA, the premium product, was 56.78%.
Catalyst deactivation from this study was not by coking activity alone but also due to
adsorption characteristics of asphaltenes, resins, aromatics, and basic nitrogen. Catalyst
activity is indirectly proportional to coke deposited. The separator model shows that
energy was not lost as the outlet temperature of 786.85K was similar to the inlet
temperature. The mass flow rate of CO and CO2 at the entry point was zero but exited
the dense bed after the combustion of coke to CO and CO2 at 0.0345 kg/s and 0.165863
kg/s respectively. CO was further reduced in the dilute bed to 0.0344891 kg/s, and CO2
increased to 0.1658642 kg/s. The temperature obtained from the simulation of the dilute
bed is 926K which agrees well with the industrial data of 924K, %error being 0.002.
This model can be adopted in improving the yield of gasoline and used for higher lumps
if needed. It is suggested that the height of the reactor could be reduced to 12.75 m as
more than 86% of cracked products would have been obtained to reduce both capital
and operational costs. The results obtained from the regenerator dense bed confirms
efficiency of combustion in the reactor