Six-lump kinetic modelling of adiabatic plug-flow riserreactor in an industrial FCC unit

Abstract

A six-lump kinetic model is presented that describes the catalytic cracking reactions taking place in an industrial riser-reactor. In this scheme, C3’s (propane and propylene gases) and C4’s (butane and butylenes gases) components of liquefied petroleum gas are predicted independently, as well as gasoline, dry gas, and coke. The riser-reactor is modelled as a plug-flow reactor operating adiabatically. Model-predicted yields of gasoline, C3’s, C4’s, fuel gas, coke, and riser-reactor outlet-temperature, agree reasonably well with plant data obtained from an operating industrial riser-reactor. Sensitivity analysis carried out on the riser-reactor indicates that inlet-temperature of gas-oil (feed), catalystto-gas oil ratio, and mass flowrate of gas-oil, are important process variables that affect the operation of the riser-reactor. It is shown that the minimum catalyst-to-gas oil ratio required for maximum conversion of gas-oil is 3. Simulation results using catalyst-to-gas oil ratio of 6.5, inlettemperature of gas-oil of 505K, and mass flowrate of gas-oil of 67.8 kg/s, give yields of 45.81 % gasoline, 6.32 % C3’s, 10.68 % C4’s, 5.42 % fuel gas, 5.11 % coke, and 26.66 % of unconverted gas-oil