Application of a Kinetic Model for Catalytic Cracking. Effects of Charge Stocks

Kinetic Analysis of Complex Reactions Using FEMLAB

“…As shown in Fig. 8 which correlates the gasoline yield and gasoil conversion, the numerical simulation accurately reproduced the results reported by the Mobil scientists [11]. The computing time is less than 1 min for each case.…”

“…Mobil scientists pioneered this research and proposed a lumped reaction network describing such processes that centers mainly on the interest of gasoline production [11,12]. It was believed that the coke produced during the cracking is the main cause of catalyst deactivation, and the gasoline yield is governed by the relative reaction rates in the parallel-serial reaction network as shown in Fig.…”

“…Again, the non-linear stiff problem solver fldaspak was used to ensure convergence. Simulation was conducted using typical process parameters obtained by experiment [11,12]. A feedstock P3 containing 46.2 wt % paraffin, 35.1 wt % naphthenes and 18.6 wt % aromatics gives kinetic rate constants k 1 = 28.0, k 2 = 1.86, k 3 = 6.0 and catalyst deactivation rate constant k d = 30.5, all with the unit of h ±1 (weight fraction ±1 ), in a Fluid Catalytic Cracker (FCC) operated at 482 C. Two catalyst residence times (t c = 1.25 and 5.0 min) were used for activity calculations.…”

Fluid catalytic cracking: Selectivity and product yield patterns

“…Gasoline cracking activation energy is almost twice that of gasoil and thus as temperature is lowered the gasoline cracking rate declines more than the gasoil cracking rate and higher selectivity results. Nace et al [4] applied the three fraction model to gasoils of widely differing molecular composition and properties and showed that high concentrations of paraffins and or naphthenes have the highest rate constant for gasoil cracking and gasoline formation. Recycle and coker feed stocks have lower rate constants than virgin gasoils.…”

Why FCC riser is taller than model predictions?

“…However, deviation was quite prominent in the inlet and exit regions. They used more rigorous fluid dynamic equations based on particulate phase fluctuating energy explained by Gidaspow,16 but took the simplest three-lump model proposed in a twin article by Weekman et al 17,18 Applying a conservative approach, Souza et al 11 considered 2-D flow with six lumps. However, the continuity and momentum equations were greatly simplified due to assumptions of incompressible homogeneous mixture with laminar flow.…”